Polyether modified silicone oil with low cyclosiloxane residue and preparation method thereof

Abstract

The invention belongs to the technical field of synthesis of polyether modified silicone oil, and particularly relates to polyether modified silicone oil with low cyclosiloxane residue and a preparation method thereof. The preparation method comprises the following steps: preparing hydrogen-containing silicone oil by taking octamethylcyclotetrasiloxane (D4) and hexamethyldisiloxane (MM) as reaction materials; the preparation method comprises the following steps: mixing hydrogen-containing silicone oil with allyl polyether, and carrying out hydrosilylation reaction under the action of a platinum catalyst and a methyl butynol inhibitor; carrying out post-treatment purification on the obtained polyether polyol modified silicone oil crude product to obtain polyether modified silicone oil with low cyclosiloxane residue; the D4 content is less than or equal to 8ppm, the D5 content is less than or equal to 10ppm, the D6 content is less than or equal to 6ppm, the total cyclosiloxane residual quantity is less than or equal to 23ppm, and the total residual quantity amplification is less than or equal to 20.5% after storage for 6 months under the condition of 40 DEG C / 75% RH.

Description

Technical Field

[0001] The present invention belongs to the technical field of the synthesis of polyether-modified silicone oil, and particularly relates to a polyether-modified silicone oil with low cyclic siloxane residue and a preparation method thereof. Background Art

[0002] As a kind of functional material with both the hydrophobicity of silicone and the hydrophilicity of polyether, polyether-modified silicone oil has important application values in the fields of textile auxiliaries, personal care products, industrial defoaming, etc. Its core preparation process usually includes the synthesis of terminal hydrogen-containing silicone oil and the hydrosilylation grafting of polyether segments. However, in the prior art, it is difficult to avoid the residue of cyclic siloxane (such as D4, D5, D6, etc.) impurities during the production process, which seriously restricts the environmental safety and application performance of the product. D4 is octamethylcyclotetrasiloxane, D5 is decamethylcyclopentasiloxane, and D6 is dodecamethylcyclohexasiloxane.

[0003] In the synthesis stage of terminal hydrogen-containing silicone oil, the traditional process uses acidic catalysts such as concentrated sulfuric acid to catalyze the ring-opening polymerization of D4. Although this method has mild reaction conditions, due to the thermodynamic equilibrium, there are always unreacted D4 monomers and by-product D5 and D6 cyclic monomers in the system. In addition, if there is trace acidic residue during the catalyst neutralization process, it may cause the degradation and recombination of the siloxane chain during subsequent storage or high-temperature processing, further exacerbating the formation of cyclic siloxane. Even if the solid catalyst is removed by filtration, the acidic components remaining in the liquid phase are still difficult to completely remove, resulting in a decrease in the product stability.

[0004] In the hydrosilylation reaction stage, the prior art generally uses chloroplatinic acid as a catalyst (the dosage of chloroplatinic acid is 50 - 200 ppm of the mass of hydrogen-containing silicone oil), but its selectivity for the polyether double bond is relatively low. To ensure the grafting efficiency, it is necessary to greatly increase the molar ratio of Si-H bond to double bond (usually >1:1, that is, the Si-H bond is in excess). At this time, the grafting efficiency ≥95%. If the Si-H bond is not in excess, it will lead to a decrease in the grafting efficiency. The excess Si-H bond is prone to break during subsequent hydrolysis to form active silanol groups, and then generate D4 - D6 cyclic monomers through condensation reaction. This side reaction not only increases the content of cyclic impurities, but also may cause the broadening of the product molecular weight distribution, affecting the uniformity of the surfactant.

[0005] Regarding the above-mentioned residual problems, the existing post-treatment technologies have significant limitations. Although conventional vacuum distillation can remove some low-boiling cyclic siloxanes (such as the boiling point of D4 is about 175 °C), the removal efficiency of high-boiling D5 (boiling point 210 °C) and D6 (boiling point above 250 °C) is low. The activated carbon adsorption process has limited adsorption capacity for cyclic siloxanes with relatively low polarity, especially the removal rate of D4 / D5 is less than 50%. In the existing technologies (such as CN110256527A), it is difficult to achieve the co-removal of polycyclic siloxanes by a single treatment method. Eventually, the residual amount of cyclic siloxanes in the finished product such as the polyether-modified silicone oil described in CN105985395A is generally > 1000 mg / kg, while the EU regulation (EU) 2018 / 35 requires that the total amount of D4 / D5 in cosmetics < 100 mg / kg, which is difficult to meet the increasingly strict environmental protection regulations.

[0006] In summary, the inherent defects of the synthesis process of terminal hydrogen-containing silicone oil, the insufficient selectivity of the hydrosilylation reaction system, and the inefficiency of the post-treatment technology in the existing technologies jointly lead to the problem of excessive residual cyclic siloxanes in the polyether-modified silicone oil surfactant. It is urgent to optimize the catalyst system, improve the reaction path and integrate multi-stage purification technology to fundamentally reduce the content of environmental risk substances such as D4-D6. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to provide a polyether-modified silicone oil with low residual cyclic siloxanes and its preparation method.

[0008] To solve the above technical problems, the present invention provides a preparation method of a polyether-modified silicone oil with low residual cyclic siloxanes, including the following steps:

[0009] (1) Synthesis of hydrogen-containing silicone oil:

[0010] 1.1), Under the protection of an inert gas (nitrogen), using octamethylcyclotetrasiloxane (D4) and hexamethyldisiloxane (MM, as a capping agent) as reaction materials, and carrying out ring-opening polymerization reaction under the action of an acidic composite catalyst (the reaction time is about 6 ± 0.5 h, and the reaction temperature is about 60 ± 10 °C); the molar ratio of octamethylcyclotetrasiloxane: hexamethyldisiloxane = 9-11:1 (preferably 10-10.5:1);

[0011] 1.2), Adding sodium bicarbonate to the reaction product obtained in step 1.1) to neutralize the acidic composite catalyst (trifluoromethylsulfonic acid in the acidic composite catalyst), and after filtration, the obtained filtrate is hydrogen-containing silicone oil;

[0012] Note: The dosage of sodium bicarbonate is about 4-4.5 times the mass of trifluoromethylsulfonic acid; trifluoromethylsulfonic acid in the acidic composite catalyst is removed by filtration after neutralization; while trimethylchlorosilane in the acidic composite catalyst can be removed by subsequent distillation (wiped film molecular distillation);

[0013] The obtained hydrogen-containing silicone oil has an Si-H content of 0.5-1.2 wt% and a number-average molecular weight of 4000-6000 g / mol;

[0014] (2) Hydrosilylation reaction:

[0015] Under the protection of an inert gas (nitrogen), according to the molar ratio of Si-H bond: allyl group = 1:1-1.25 (preferably 1:1.05-1.2), the hydrogen-containing silicone oil obtained in step (1) is mixed with allyl polyether, and first dehydrated (dehydrated at -0.095 MPa and 70±10 °C for 1.5±0.5 h); then platinum catalyst and methyl butynol (i.e., 2-methyl-3-butyn-2-ol, as an inhibitor) are added for reaction; the reaction temperature is 80-120 °C, and the reaction time is 3-6 hours (preferably react at 100±10 °C for 5±0.5 h) to obtain a crude polyether polyol-modified silicone oil;

[0016] (3) Post-treatment and purification:

[0017] The crude polyether polyol-modified silicone oil obtained in step (2) is subjected to post-treatment and purification; a polyether-modified silicone oil with low cyclic siloxane residue is obtained (the total content of D4-D6 is ≤24 ppm, preferably ≤23 ppm).

[0018] As an improvement to the preparation method of the polyether-modified silicone oil with low cyclic siloxane residue of the present invention: the post-treatment and purification in step (3) are carried out in the following steps in sequence:

[0019] The crude polyether polyol-modified silicone oil obtained in step (2) is subjected to nitrogen bubbling combined with ultrasonic-assisted degassing, then subjected to wiped film molecular distillation (for high-vacuum separation), then supercritical CO2 extraction (to enrich active ingredients), and finally adsorption refining using BFT-CMMC adsorbent; a polyether-modified silicone oil with low cyclic siloxane residue is obtained.

[0020] As a further improvement to the preparation method of the polyether-modified silicone oil with low cyclic siloxane residue of the present invention: in step 1.1): the acidic composite catalyst is prepared by mixing trifluoromethanesulfonic acid and trimethylchlorosilane according to a mass ratio of 1:(1±0.1), and the addition amount of the acidic composite catalyst is 0.05-0.12 wt% of the mass of octamethylcyclotetrasiloxane (D4);

[0021] In step 1.2): pass through a 0.45 μm filter;

[0022] In step (2): the addition amount of the platinum catalyst is 6-16 ppm of the mass of the hydrogen-containing silicone oil, and the addition amount of methyl butynol is 0.05-0.1% of the mass of the hydrogen-containing silicone oil; the platinum catalyst is karstedt platinum catalyst;

[0023] In step (3): The material is passed through a fixed-bed adsorption column filled with BFT-CMMC adsorbent, with an adsorption temperature of 40 - 60°C and a flow rate of 1 - 3 BV / h.

[0024] As a further improvement to the preparation method of the polyether-modified silicone oil with low cyclic siloxane residues of the present invention: Step (3) includes the following steps:

[0025] 3.1) Degassing pretreatment:

[0026] The crude polyether polyol-modified silicone oil (800 - 900 g) obtained in step (2) is subjected to nitrogen bubbling combined with ultrasonic-assisted degassing;

[0027] The above-mentioned crude product is added to a 10 L glass reaction kettle (equipped with an ultrasonic probe and a nitrogen distributor with a pore size of 10 - 30 μm), and at 120 - 140°C, a nitrogen flow rate of 4 - 6 L / min, an ultrasonic power of 200 - 400 W, and ultrasonic oscillation is carried out for 2 - 4 hours (thereby effectively removing dissolved gases and volatile impurities);

[0028] 3.2) Film scraping molecular distillation (for high-vacuum separation):

[0029] A film scraping molecular distillation device is used to process for 3 ± 0.5 hours at 110 - 150°C, a system pressure ≤ 0.5 kPa, and a liquid film thickness ≤ 100 μm; thereby achieving efficient purification of the target components;

[0030] Note: The KDL-5 type molecular distillation device (evaporation area 0.5 m 2 , film scraping rotation speed 200 - 300 rpm) can be used;

[0031] 3.3) Supercritical CO2 extraction (to enrich active ingredients):

[0032] Countercurrent extraction is carried out under the conditions of 15 - 20 MPa and 50 - 60°C, adding 2 - 5% ethanol (v / v) as an entrainer, and circulating for 4 - 6 hours, thereby ensuring selective extraction;

[0033] Note: In a 10 L pressure-resistant extraction kettle (20 MPa); preferably, countercurrent extraction is carried out under the conditions of 15 MPa and 50°C, adding 3% ethanol (v / v) as an entrainer, and circulating for 4 hours;

[0034] 3.4) Adsorption refining:

[0035] The material is passed through a fixed-bed adsorption column filled with BFT-CMMC adsorbent (the adsorbent dosage is about 1 - 5 kg), the adsorption temperature is 40 - 60°C, and the flow rate is 0.5 - 2 BV / h; after accurately removing residual impurities, the product is obtained.

[0036] As a further improvement to the preparation method of the polyether-modified silicone oil with low cyclic siloxane residue of the present invention: The allyl polyether in step (2) is a copolymer of ethylene oxide (EO) and propylene oxide (PO), with an EO / PO molar ratio of 2:1 and a molecular weight of 1500 - 2500 g / mol.

[0037] As a further improvement to the preparation method of the polyether-modified silicone oil with low cyclic siloxane residue of the present invention: The preparation steps of the BFT-CMMC adsorbent include:

[0038] I. Synthesis of titanium-zinc ferrite magnetic core:

[0039] According to the molar ratio of Ti:Zn:Fe = 1:(3 ± 0.1):(26 ± 0.5), zinc nitrate, ferric chloride and tetrabutyl titanate are dissolved in water, and the pH is adjusted to 11 - 12, and the TiZnFeO magnetic core is obtained through a hydrothermal reaction; the hydrothermal reaction is carried out at 200 ± 20 °C for 24 ± 2 h;

[0040] Note: The pH is adjusted using ammonia water (concentrated ammonia water);

[0041] II. Coating with graphitic carbon nitride (g-C3N4):

[0042] Melamine is prepared into a g-C3N4 precursor;

[0043] The TiZnFeO magnetic core and the g-C3N4 precursor are dispersed in solvent I to form a suspension, with a mass ratio of TiZnFeO magnetic core:g-C3N4 precursor = 1:(0.5 ± 0.05);

[0044] Then, solvent I is removed (solvent I is evaporated), and under the protection of an inert gas (argon), annealing is carried out at 300 ± 20 °C for 2 ± 0.5 h to obtain g-C3N4-coated particles;

[0045] Note: The g-C3N4-coated particles are graphitic carbon nitride (g-C3N4) with a dense coating layer on the surface;

[0046] III. Construction of a mesoporous SiO2 shell (mesoporous SiO2 shell with three-level pores):

[0047] Using CTAB and PMMA microspheres as double template agents, a SiO2 shell is grown through the sol-gel method, and the templates are removed by gradient calcination to form a mesoporous SiO2 shell (mesoporous SiO2 shell with three-level pores) as a mesoporous material;

[0048] CTAB is cetyltrimethylammonium bromide, and PMMA is poly(methyl methacrylate);

[0049] IV. Surface bifunctional modification:

[0050] The mesoporous material is successively grafted with phenylboronic acid groups and perfluoroalkylsilanes to obtain a surface bifunctionalized modification product;

[0051] V. Product post-treatment:

[0052] The surface bifunctionalized modification product is subjected to spherical granulation.

[0053] As a further improvement to the preparation method of the polyether-modified silicone oil with low cyclic siloxane residues of the present invention: Step three includes the following steps:

[0054] 3.1) Dual-template agent loading:

[0055] The g-C3N4-coated particles are added to Solvent I to obtain a g-C3N4-coated particle suspension;

[0056] CTAB and PMMA microspheres (particle size 200 ± 40 nm) are added to the g-C3N4-coated particle suspension, and magnetic stirring is carried out (stirring at 800 ± 100 rpm for 24 ± 2 h) to allow the template agent to be fully adsorbed on the surface of the g-C3N4-coated particles;

[0057] The mass ratio of g-C3N4-coated particles: CTAB: PMMA microspheres = 0.5: (2 ± 0.1): (1 ± 0.05);

[0058] 3.2) Growth of SiO2 by sol-gel method:

[0059] A mixed solution of tetraethyl orthosilicate (TEOS) and ammonia water (28 wt%) is added dropwise to the product obtained in step 3.1) (the dropping time is about 4 - 6 minutes), and the reaction is carried out at 40 ± 10 °C for 6 ± 1 h;

[0060] For every 1 g of PMMA microspheres in the product obtained in step 3.1), (5 ± 0.5) mL of tetraethyl orthosilicate and (2 ± 0.2) mL of ammonia water are used;

[0061] After the reaction, the precipitate is collected by centrifugation and washed;

[0062] 3.3) Gradient calcination for pore formation:

[0063] The washed precipitate obtained in step 3.2) is heated to 350 ± 30 °C and kept warm for 3 ± 0.5 h to remove CTAB, and then continuously heated to 600 ± 50 °C and kept warm for 2 h ± 0.5 to remove PMMA. After cooling (naturally cooled to room temperature), a mesoporous SiO2 shell layer (mesoporous SiO2 shell layer with three-level pores) is obtained;

[0064] Step four includes the following steps:

[0065] 4.1) Grafting of phenylboronic acid groups:

[0066] Dissolve 3-acrylamidophenylboronic acid in borate buffer (pH = 9), add the mesoporous material obtained in step 3, and react at 70 ± 10 ° C for 12 ± 1 h; the mass ratio of 3-acrylamidophenylboronic acid to mesoporous material is (1.5 ± 0.1): 1;

[0067] After the reaction is completed, the solid obtained is washed and dried to obtain the grafted product;

[0068] 4.2) Perfluoroalkylsilane modification:

[0069] Mix perfluorododecyltrimethoxysilane and the grafted product obtained in step 4.1) in solvent II and react at 110±10°C for 24±2h under inert gas (nitrogen). Add 2±0.2mL of perfluorododecyltrimethoxysilane for every 1g of the grafted product obtained by mesoporous material.

[0070] After the reaction is completed, the solid obtained is washed and vacuum activated to obtain a surface bifunctional modified product.

[0071] As a further improvement of the preparation method of the polyether-modified silicone oil containing low-cyclic siloxane residues of the present invention:

[0072] In the step 1:

[0073] For every 0.1 mol of tetrabutyl titanate, use 200±50 mL of deionized water;

[0074] After the hydrothermal reaction, the mixture was cooled to room temperature, and the resulting precipitate was washed with ethanol and deionized water (centrifugal washing) in sequence, and then vacuum dried (60±10°C for 12±1h) to obtain a TiZnFeO magnetic core (titanium zinc ferrite magnetic core).

[0075] Step 2:

[0076] Melamine was heated to 550±30℃ under inert gas protection and calcined for 4±0.5h to obtain g-C3N4 precursor (light yellow powder);

[0077] The solvent I is anhydrous ethanol; 200±50mL of anhydrous ethanol is used for every 1g of TiZnFeO magnetic core;

[0078] Note: The heating rate is 5±0.5℃ / min;

[0079] In step 3.1), solvent I is anhydrous ethanol; 100±20 mL of anhydrous ethanol is used for every 0.50 g of g-C3N4 coated particles;

[0080] In step 3.2), washing with an ethanol / hydrochloric acid mixture (V / V = 9:1) and deionized water in sequence;

[0081] In Step 3.3): the heating rate for heating to 350 ± 30 °C is 2 ± 0.5 °C / min, and the heating rate for heating to 600 ± 50 °C is 5 ± 0.5 °C / min;

[0082] In Step 4.1): for every 1.5 g of 3-acrylamidophenylboronic acid, 100 ± 20 mL of borate buffer solution is used; after the reaction is completed, it is washed with acetone and dried at 80 ± 10 °C for 6 ± 0.5 h;

[0083] In Step 4.2): Solvent II is toluene (anhydrous toluene); for every 2 mL of perfluorododecyltrimethoxysilane, 50 ± 10 mL of toluene is used;

[0084] After the reaction is completed, the obtained solid is washed with toluene and ethanol, and then vacuum-activated at 120 ± 10 °C for 4 ± 0.5 h to obtain a surface bifunctionalized modified product.

[0085] As a further improvement to the preparation method of the polyether-modified silicone oil with low cyclic siloxane residue of the present invention: the spherical granulation in Step Five:

[0086] First, polyvinyl alcohol binder is added to the surface bifunctionalized modified product, and then spherical particles (with a diameter of 1.0 ± 0.2 mm) are prepared. After drying (drying at 80 ± 10 °C for 12 ± 1 h), it is calcined at 500 ± 20 °C for 1 ± 0.1 h to obtain a BFT-CMMC adsorbent;

[0087] The polyvinyl alcohol binder is 2.5 - 3.5% (preferably 3%) of the weight of the surface bifunctionalized modified product.

[0088] As a further improvement to the preparation method of the polyether-modified silicone oil with low cyclic siloxane residue of the present invention: the regeneration method of the BFT-CMMC adsorbent includes the following steps:

[0089] (1) The adsorbent bed is rinsed reversely with methanol or ethanol, and the rinsing volume is 5 - 10 BV;

[0090] (2) Under nitrogen protection, it is calcined at 400 - 600 °C for 2 - 4 hours to remove organic residues.

[0091] Note: The specific surface area retention rate of the regenerated adsorbent is ≥95%, and it can be recycled ≥5 times.

[0092] The present invention also provides a polyether-modified silicone oil with low cyclic siloxane residues (which can be used as a surfactant) prepared by any of the above methods: its D4 content is ≤8 ppm, D5 content is ≤10 ppm, D6 content is ≤6 ppm, and the total cyclic siloxane residue content is ≤24 ppm (preferably ≤23 ppm), and the increase in the total residue content is ≤20.5% after storage at 40°C / 75% RH for 6 months.

[0093] In the present invention:

[0094] 1. In the synthesis of hydrogen-containing silicone oil:

[0095] The present invention uses an acidic composite catalyst of trifluoromethanesulfonic acid and trimethylchlorosilane (mass ratio of 1:1 ± 0.1), and hexamethyldisiloxane (MM) is used as a capping agent to carry out ring-opening polymerization of D4 at a low temperature of 60 ± 10°C.

[0096] In the prior art: The traditional process uses concentrated sulfuric acid to catalyze the ring-opening polymerization of D4, which requires high temperature (80 - 100°C) and cannot inhibit the regeneration of cyclic monomers.

[0097] Therefore, the technical advantages of the present invention are:

[0098] Through the synergistic effect of strong acidity (trifluoromethanesulfonic acid) and silylation (trimethylchlorosilane), the capping rate of the acidic composite catalyst is improved; the capping agent MM converts the terminal hydroxyl group into an inert Si-O-Si structure, enhancing the storage stability; the reaction temperature of the present invention is greatly reduced compared with the prior art, and the residues of D4 - D6 are also effectively reduced.

[0099] 2. In the hydrosilylation reaction:

[0100] The present invention uses a supported platinum catalyst (6 - 16 ppm) + methylbutynol inhibitor system, and controls the Si-H:allyl ratio to be as low as 1:1.05 at least.

[0101] In the prior art: Chloroplatinic acid catalyst (50 - 200 ppm) is used without an inhibitor, and an excessive amount of Si-H bonds (molar ratio > 1:1.5) is required.

[0102] Therefore, the technical advantages of the present invention are: The amount of platinum catalyst is reduced, the non-selective addition is inhibited by methylbutynol, and the grafting efficiency is improved; the hydrolysis side reaction is reduced, and the generation rate of D4 - D6 is decreased. The molecular weight distribution PDI is optimized.

[0103] 3. In the post-treatment and purification:

[0104] The present invention integrates ultrasonic-assisted degassing, wiped-film molecular distillation, supercritical CO2 extraction, and BFT-CMMC adsorption refining.

[0105] Prior art: Only vacuum distillation (120 °C / 10 kPa) or activated carbon adsorption (D4 / D5 removal rate < 50%) is used.

[0106] Therefore, the technical advantages of the present invention are:

[0107] Supercritical CO2 extraction selectively removes high-boiling cyclic siloxanes (high D5 / D6 removal rate);

[0108] The BFT-CMMC adsorbent has a high adsorption capacity for D4-D6 through phenylboronic acid-perfluoroalkyl bifunctional groups;

[0109] The four-step collaborative process enables the total residual cyclic siloxanes to be ≤ 23 ppm.

[0110] During the preparation process of the BFT-CMMC adsorbent of the present invention: gradient calcination for pore formation is set; an adsorbent with good adsorption effect can be obtained.

[0111] In summary, the beneficial effects / technical advantages of the present invention are mainly reflected in:

[0112] 1. Ultra-low residual cyclic siloxanes: The total content of D4-D6 ≤ 23 ppm (EU standard < 100 ppm), meeting the strictest cosmetic regulations;

[0113] 2. High stability: The increase in cyclic siloxanes after 6 months of storage < 20.5% (while the traditional process > 30%);

[0114] 3. Process synergy: High removal rate of cyclic siloxanes in the synthesis of hydrogen-containing silicone oil - addition reaction - purification process;

[0115] 4. Economy: The amount of catalyst used is reduced, and the adsorbent can be recycled at least 5 times or more;

[0116] 5. Application performance: Excellent molecular weight distribution PDI.

[0117] A preparation method for significantly reducing the residues of cyclic siloxanes (including octamethylcyclotetrasiloxane D4, decamethylcyclopentasiloxane D5, dodecamethylcyclohexasiloxane D6) in polyether-modified silicone oil through an innovative process. The obtained product is particularly suitable for fields with strict restrictions on the content of cyclic siloxanes, such as cosmetics and personal care products. Detailed implementation manners

[0118] The present invention will be further described below in conjunction with specific embodiments, but the protection scope of the present invention is not limited thereto:

[0119] In the present invention:

[0120] The ultrasonic power is 300 W - 400 W;

[0121] The mass concentration of concentrated ammonia water is 28%; the mass concentration of hydrochloric acid is 37%;

[0122] The density of perfluorododecyltrimethoxysilane is about 1.5 g / mL;

[0123] PMMA microspheres (particle size 200 nm) can be purchased from, for example, Suzhou Zhiyi Microsphere Technology Co., Ltd.

[0124] The formulation of the borate buffer solution with pH = 9 is as follows: Weigh 1.79 g of NaHPO4·12H2O and 0.381 g of Na2BO4·10H2O and dissolve them in 1 L of ultrapure water.

[0125] The polyvinyl alcohol binder is a conventional general-purpose PVA binder with a PVA content of 8 - 12% and a water content of 80 - 85%; the average degree of polymerization of polyvinyl alcohol is about 1700, for example.

[0126] Adsorbent Example 1. A preparation method of a BFT - CMMC adsorbent, which successively performs the following steps:

[0127] I. Preparation of titanium zinc ferrite magnetic core

[0128] 1.1). Preparation of precursor solution:

[0129] Dissolve zinc nitrate hexahydrate [Zn(NO3)2·6H2O, 89.25 g (0.3 mol)], iron(III) chloride hexahydrate [FeCl3·6H2O, 702.83 g (2.6 mol)] and tetrabutyl titanate [Ti(OBu)4, 34.03 g (0.1 mol)] in 200 mL of deionized water, add concentrated ammonia water (about 10 mL) to adjust the pH to 11.5, and ultrasonically disperse for 30 min to form a homogeneous solution.

[0130] 1.2). Hydrothermal reaction:

[0131] Transfer the homogeneous solution obtained in step 1.1) to a 500 mL polytetrafluoroethylene - lined reaction kettle, and react at 200 °C for 24 h. After the reaction is completed, naturally cool to room temperature, collect the precipitate by applying an external magnetic field (0.5 T), and centrifuge and wash successively with ethanol (500 mL × 3 times) and deionized water (500 mL × 3 times) (8000 rpm × 5 min), and vacuum - dry at 60 °C for 12 h to obtain 256 g of black powder - shaped Ti 0.1 Zn 0.3 Fe 2.6 O4 as the titanium zinc ferrite magnetic core.

[0132] II. Coating with graphitic carbon nitride (g - C3N4)

[0133] 2.1). Preparation of g - C3N4 precursor:

[0134] Put melamine (10 g) in an alumina crucible, then place it in a tube furnace and heat it to 550 °C at a rate of 5 °C / min, and calcine it for 4 h under a nitrogen atmosphere to obtain a pale yellow powder-like g-C3N4 precursor (about 1.8 g).

[0135] 2.2), Ultrasonic-assisted self-assembly coating:

[0136] Disperse 1.00 g of the titanium-zinc ferrite magnetic core (Ti 0.1 Zn 0.3 Fe 2.6 O4) obtained in step one and 0.5 g of the g-C3N4 precursor obtained in step 2.1) in 200 mL of absolute ethanol, and ultrasonically treat for 2 h to form a stable suspension.

[0137] Then remove the solvent (absolute ethanol) by rotary evaporation (60 °C, 200 mbar), and anneal at 300 °C for 2 h under argon protection to form particles with a dense graphitic carbon nitride (g-C3N4) coating layer on the surface; hereinafter simply referred to as g-C3N4-coated particles, with a mass of about 1.45 g.

[0138] III. Construction of the tertiary mesoporous SiO2 layer:

[0139] Using CTAB (cetyltrimethylammonium bromide) and PMMA (polymethyl methacrylate) microspheres (particle size about 200 ± 40 nm) as dual template agents, grow the SiO2 shell layer by the sol-gel method, and gradiently calcine to remove the templates to form multi-level pores, obtaining a tertiary pore mesoporous SiO2 shell layer as a mesoporous material.

[0140] Specifically as follows:

[0141] 3.1), Loading of dual template agents:

[0142] Take 0.5 g of the g-C3N4-coated particles obtained in step two and add them to 100 mL of ethanol (absolute ethanol) to obtain a g-C3N4-coated particle suspension;

[0143] Add 2 g of CTAB and 1 g of PMMA microspheres (particle size 200 nm) to the above g-C3N4-coated particle suspension, and magnetically stir (800 rpm) for 24 h to allow the template agents to be fully adsorbed on the surface of the g-C3N4-coated particles.

[0144] 3.2), Growth of SiO2 by sol-gel method:

[0145] Dropwise add a mixed solution of tetraethyl orthosilicate (TEOS, 5 mL) and ammonia water (28 wt%, 2 mL) to the product obtained in step 3.1) (the dropping time is about 5 minutes), and react at 40 °C for 6 h. After the reaction, centrifuge to collect the precipitate, and wash it successively with an ethanol / hydrochloric acid mixed solution (V / V = 9:1, 200 mL × 3 times) and deionized water (200 mL × 3 times).

[0146] 3.3) Gradient calcination for pore formation:

[0147] Place the washed precipitate obtained in step 3.2) in a muffle furnace, heat it to 350 °C at a rate of 2 °C / min and hold for 3 h to remove CTAB, then continue to heat it to 600 °C at a rate of 5 °C / min and hold for 2 h to remove the PMMA template, and naturally cool to room temperature to obtain a mesoporous SiO2 shell layer (mesoporous SiO2 shell layer with three - level pore channels), as a mesoporous material, and the product mass is about 2.1 g.

[0148] The mesoporous material is detected by the conventional nitrogen adsorption - desorption isotherm (BET method), and the detection results are as follows:

[0149] Micropores (<2 nm): DFT model analysis shows that the micropore proportion is about 15%, which comes from the ultra - small pore channels formed by the pyrolysis of CTAB molecular templates;

[0150] Mesopores (2 - 50 nm): The BJH model shows that the main peak is located at 3.8 nm (corresponding to the CTAB micelle template), and the secondary peak is located at 25 nm (corresponding to the PMMA microsphere gap);

[0151] Macropores (>50 nm): The mercury intrusion porosimetry (MIP) measures that the average macropore diameter is 180 nm, which is composed of the macroscopic pore channels left after the calcination of PMMA microspheres (200 nm).

[0152] The total pore volume is 1.2 cm 3 / g, among which the micropore volume is 0.18 cm 3 / g, the mesopore volume is 0.75 cm 3 / g, the macropore volume is 0.27 cm[[ID=2८]] 3 / g, and the specific surface area reaches 850 m[[ID=३०]] 2 / g.

[0153] It should be noted that: The specific surface area of traditional activated carbon is 1200 m 2 / g, but the pore diameters are disordered.

[0154] IV. Surface bifunctional modification: Graft phenylboronic acid groups and perfluoroalkylsilanes onto the mesoporous material in sequence to obtain a surface - bifunctionalized modification product;

[0155] Specifically as follows:

[0156] 4.1) Grafting of phenylboronic acid groups:

[0157] Dissolve 3-acrylamidophenylboronic acid (1.5 g) in borate buffer solution (100 mL) with pH = 9, add 1 g of the mesoporous material obtained in Step 3, and reflux at 70 °C for 12 h. After the reaction, filter, wash the obtained filter cake with acetone (100 mL × 3 times), and dry at 80 °C for 6 h. The obtained product is named the grafted product, about 1.08 g.

[0158] 4.2) Perfluoroalkylsilane modification:

[0159] Mix 2 mL of perfluorododecyltrimethoxysilane with the grafted product obtained in Step 4.1) in 50 mL of toluene (anhydrous toluene), and react at 110 °C for 24 h under nitrogen protection.

[0160] After the reaction, filter, and ultrasonically clean the obtained filter cake successively with toluene (50 mL × 2 times) and ethanol (50 mL × 2 times), and activate in vacuum at 120 °C for 4 h. The obtained product is named the surface bifunctionalized modification product, about 1.05 g.

[0161] V. Product post-treatment (spherical granulation):

[0162] Mix 100 g of the surface bifunctionalized modification product obtained in Step 4 with 3.00 g of polyvinyl alcohol binder (i.e., the dosage of polyvinyl alcohol binder is 3 wt% of the surface bifunctionalized modification product), and prepare spherical particles with a diameter of 1.0 ± 0.2 mm through an extrusion spheronizer (die hole diameter 1.0 mm, rotation speed 1200 rpm). After drying at 80 °C for 12 h, calcine at 500 °C for 1 h to enhance the mechanical strength, and obtain the BFT-CMMC adsorbent, about 95 g.

[0163] Example 1:

[0164] 1. Synthesis of hydrogen-containing silicone oil:

[0165] 1.1) Preparation of acidic composite catalyst

[0166] The acidic composite catalyst is obtained by mixing trifluoromethanesulfonic acid and trimethylchlorosilane in a mass ratio of 1:1;

[0167] 1.2) In a 1 L three-necked flask (equipped with mechanical stirring, thermometer and nitrogen protection), add 580 g of octamethylcyclotetrasiloxane (D4, 1.96 mol) and 29 g of hexamethyldisiloxane (MM, 0.19 mol, as a capping agent), and heat up to 60 °C; slowly add dropwise (the dropping time is about 5 minutes) 0.49 g of acidic composite catalyst, keep the temperature and maintain the reaction for 6 h, and the stirring rate is 300 rpm. After the reaction is completed, the viscosity of the system increases significantly. Measured by a Brookfield viscometer, the viscosity is about 2000 mPa·s at 25 °C.

[0168] In this case, the dosage of the acidic composite catalyst is 0.084 wt% of the dosage of D4.

[0169] 1.3), Add 1 g of sodium bicarbonate to the three-necked flask to neutralize the trifluoromethanesulfonic acid in the acidic composite catalyst; stir for 30 min.

[0170] Then, pressurized filtration is carried out through a 0.45 μm polytetrafluoroethylene (PTFE) membrane filter to obtain about 609 g of colorless and transparent hydrogen-containing silicone oil.

[0171] In this case, the dosage of sodium bicarbonate is about 4.1 times the mass of trifluoromethanesulfonic acid;

[0172] Hydrogen-containing silicone oil index: Si-H content 0.8 wt% (determined by titration method); number-average molecular weight 5000 g / mol (determined by GPC);

[0173] Note: After the reaction of trifluoromethanesulfonic acid with sodium bicarbonate to form the corresponding salt, phase separation from the hydrogen-containing silicone oil is achieved when passing through the polytetrafluoroethylene (PTFE) membrane filter.

[0174] 2. Hydrosilylation:

[0175] In a 1 L three-necked flask (equipped with mechanical stirring, thermometer and nitrogen protection), add about 609 g of hydrogen-containing silicone oil (content 0.8 wt%, 0.1 mol Si-H) and 210 g of allyl polyether (EO / PO = 2:1, number-average molecular weight 2000, 0.105 mol allyl). Dehydrate at -0.095 MPa and 70 °C for 1.5 h, then add 6.70 mg of platinum catalyst and 536 mg of methylbutynol (inhibitor), and react at 100 °C for 5 h to obtain a crude product of polyether polyol-modified silicone oil (residual Si-H content is 0.012 wt%).

[0176] The platinum catalyst is karstedt platinum catalyst.

[0177] In this case, mol(Si-H:allyl) = 1:1.05; platinum catalyst:hydrogen-containing silicone oil = 11 ppm (i.e., 1.1*10 -5 ) mass ratio, methylbutynol:hydrogen-containing silicone oil = 0.088% mass ratio.

[0178] The grafting rate in this case is 98.5%, and the grafting rate is the molar ratio of the actually participating Si-H bonds to the total amount of the initial Si-H bonds.

[0179] 3. Post-treatment:

[0180] 3.1), Pretreatment (pretreatment is carried out by nitrogen bubbling combined with ultrasonic-assisted degassing):

[0181] Put about 810 g of the crude polyether polyol modified silicone oil obtained in step 2 into a 10 L glass reaction kettle (equipped with a 200 W, 40 kHz ultrasonic probe and a nitrogen distributor with a pore size of 10 μm), and introduce nitrogen at a rate of 5 L / min at 120 - 140 °C (the nitrogen enters the glass reaction kettle after passing through the nitrogen distributor), while applying ultrasonic oscillation for 2 hours to effectively remove dissolved gases and volatile impurities (trace amounts of D4, D5, D6, etc.).

[0182] 3.2), wiped film molecular distillation (high vacuum separation is carried out by wiped film molecular distillation):

[0183] Use a KDL-5 type molecular distillation device (evaporation area 0.5 m 2 , wiping film rotation speed 200 - 300 rpm) for the crude polyether polyol modified silicone oil after pretreatment obtained in step 3.1), control the liquid film thickness ≤ 100 μm at an evaporation temperature of 120 °C and a system pressure of 0.5 kPa for 3 hours to achieve efficient purification of the target components. Collect the light components (containing residual cyclic siloxanes D4 - D6, oligomers, etc.) separated at the condenser outlet of the KDL-5 type molecular distillation device, and collect the purified substance at the bottom of the evaporator, named polyether polyol modified silicone oil purify I;

[0184] 3.3), supercritical CO2 extraction (enrich active ingredients by supercritical CO2 extraction):

[0185] Put the polyether polyol modified silicone oil purify I obtained in step 3.2) into a 10 L pressure-resistant extraction kettle (20 MPa), carry out countercurrent extraction at 15 MPa and 50 °C, add 3% ethanol (v / v) as an entrainer, and cycle for 4 hours to ensure selective extraction. Collect the extraction phase at the extraction kettle separator outlet of the 10 L pressure-resistant extraction kettle, named polyether polyol modified silicone oil purify II;

[0186] 3.4), adsorption refining (refine using adsorbent):

[0187] About 2 kg of BFT-CMMC adsorbent is filled in the middle part of a fixed bed adsorption column (Φ20×100 cm), that is, the bed volume BV corresponding to the BFT-CMMC adsorbent is 6.5 L. The polyether polyol modified silicone oil purify II obtained in step 3.3) passes through the BFT-CMMC adsorbent at a flow rate of 2 BV / h (13 L / h) and is adsorbed at 50 °C; after removing residual impurities, finally collect the refined product at the adsorption column outlet of the fixed bed adsorption column, and the amount of the product (polyether modified silicone oil with low cyclic siloxane residue) is about 650 g.

[0188] 4. Detection shows:

[0189] The D4 content is 4.8 ppm, and the test is carried out with reference to GB / T 33308-2016;

[0190] The D5 content is 7.2 ppm, and the test is carried out with reference to ISO 18857-2:2009;

[0191] The D6 content is 4.1 ppm, and the test is carried out with reference to EPA 8270E;

[0192] The total content of D4-D6 is 16.1 ppm. After the sample is stored at 40 °C / 75% RH for 6 months, the total remaining content of D4-D6 increases to 19.1 ppm (change rate < 20%), proving that there is no significant cyclic body recombination.

[0193] Example 2: Change the dosage of allyl polyether in the "hydrosilylation" in Step 2 of Example 1 to 200 g (containing 0.1 mol of allyl), and keep the dosage of hydrogen-containing silicone oil unchanged, that is, Si-H:allyl = 1:1; the rest is the same as Example 1. The grafting rate of this case is 97.2%. The amount of the finally obtained product is about 642 g.

[0194] Example 3: Change the dosage of allyl polyether in the "hydrosilylation" in Step 2 of Example 1 to 220 g (containing 0.11 mol of allyl), and keep the dosage of hydrogen-containing silicone oil unchanged, that is, Si-H:allyl = 1:1.10; the rest is the same as Example 1. The grafting rate of this case is 97.8%. The amount of the finally obtained product is about 661 g.

[0195] Example 4: Change the dosage of allyl polyether in the "hydrosilylation" in Step 2 of Example 1 to 240 g (containing 0.120 mol of allyl), and keep the dosage of hydrogen-containing silicone oil unchanged, that is, Si-H:allyl = 1:1.20; the rest is the same as Example 1. The grafting rate of this case is 96.5%. The amount of the finally obtained product is about 674 g.

[0196] Comparative Example 1: Change the dosage of allyl polyether in the "hydrosilylation" in Step 2 of Example to 160 g (containing 0.08 mol of allyl), and keep the dosage of hydrogen-containing silicone oil unchanged, that is, Si-H:allyl = 1:0.8; the rest is the same as Example 1. The grafting rate of this case is 82.3%.

[0197] Comparative Example 2: Change the dosage of allyl polyether in the "hydrosilylation" in Step 2 of Example 1 to 260 g (containing 0.13 mol of allyl), and keep the dosage of hydrogen-containing silicone oil unchanged, that is, Si-H:allyl = 1:1.3; the rest is the same as Example 1. The grafting rate of this case is 89.7%.

[0198] The comparison of the above cases is shown in Table 1 below:

[0199] Table 1

[0200]

[0201] Example 5: Change the dosage of the platinum catalyst in the "hydrosilylation" in Step 2 of Example 1 to 3.65 mg, that is, the platinum catalyst is 6 ppm of the dosage of the hydrogen-containing silicone oil; the rest is the same as Example 1. The grafting rate of this case is 95.1%.

[0202] Example 6: Change the dosage of the platinum catalyst in the "hydrosilylation" in Step 2 of Example 1 to 9.74 mg, that is, the platinum catalyst is 16 ppm of the dosage of the hydrogen-containing silicone oil; the rest is the same as Example 1. The grafting rate of this case is 97.2%.

[0203] Comparative Example 3: Change the dosage of the platinum catalyst in the "hydrosilylation" in Step 2 of Example 1 to 2.44 mg, that is, the platinum catalyst is 4 ppm of the dosage of the hydrogen-containing silicone oil; the rest is the same as Example 1. The grafting rate of this case is 78.6%.

[0204] Comparative Example 4: Change the dosage of the platinum catalyst in the "hydrosilylation" in Step 2 of Example 1 to 12.18 mg, that is, the platinum catalyst is 20 ppm of the dosage of the hydrogen-containing silicone oil; the rest is the same as Example 1. The grafting rate of this case is 93.8%.

[0205] The comparison of the above cases is shown in Table 2 below:

[0206] Table 2

[0207]

[0208]

[0209] Example 7: Change the dosage of methylbutynol in the "hydrosilylation" in Step 2 of Example 1 to 305 mg, that is, the methylbutynol inhibitor accounts for 0.05% of the dosage of the hydrogen-containing silicone oil; the rest is the same as Example 1. The grafting rate of this case is 95.7%.

[0210] Example 8: Change the dosage of methylbutynol in the "hydrosilylation" in Step 2 of Example 1 to 609 mg, that is, the methylbutynol inhibitor accounts for 0.1% of the dosage of the hydrogen-containing silicone oil; the rest is the same as Example 1. The grafting efficiency of this case is 97%.

[0211] Example 9: Change the dosage of methylbutynol in the "hydrosilylation" in Step 2 of Example 1 to 426 mg, that is, the methylbutynol inhibitor accounts for 0.07% of the dosage of the hydrogen-containing silicone oil; the rest is the same as Example 1. The grafting efficiency of this case is 96.4%.

[0212] Comparative Example 5: In the "hydrosilylation" in Step 2 of Example 1, the amount of methylbutynol was changed to 183 mg, that is, the methylbutynol inhibitor accounted for 0.03% of the amount of hydrogen-containing silicone oil; the rest was the same as in Example 1. The grafting efficiency of this case was 85.2%.

[0213] Comparative Example 6: In the "hydrosilylation" in Step 2 of Example 1, the amount of methylbutynol was changed to 731 mg, and the methylbutynol inhibitor accounted for 0.12% of the amount of hydrogen-containing silicone oil; the rest was the same as in Example 1. The grafting efficiency of this case was 90.1%.

[0214] The comparison of the above cases is shown in Table 3 below:

[0215] Table 3

[0216]

[0217] Comparative Example 7: Omit the "film scraping molecular distillation" in Step 3.2) of Example 1, that is, directly perform the "supercritical CO2 extraction" in Step 3.3) on the pretreated polyether polyol modified silicone oil crude product obtained in Step 3.1); the rest was the same as in Example 1.

[0218] Comparative Example 8: Omit the "supercritical CO2 extraction" in Step 3.3) of Example 1, that is, directly perform the "adsorption purification" in Step 3.4) on the purified polyether polyol modified silicone oil I obtained in Step 3.2), and the rest was the same as in Example 1.

[0219] Comparative Example 9: Omit the "adsorption purification" in Step 3.4) of Example 1, that is, directly use the purified polyether polyol modified silicone oil II obtained in Step 3.3) as the product; the rest was the same as in Example 1.

[0220] Comparative Example 10: Completely omit the post-treatment steps in the entire Step 3, that is, only treat the polyether polyol modified silicone oil crude product obtained in Step 2 by conventional vacuum distillation (120 °C / 10 kPa) for 1 hour, and the rest was the same as in Example 1.

[0221] The comparison of the obtained results is shown in Table 4 below.

[0222] Table 4

[0223]

[0224] Example 10: In Step 3.4) of Example 1, the amount of BFT-CMMC adsorbent was changed from 2 kg to 1 kg (that is, the amount was halved), and the rest was the same as in Example 1.

[0225] Comparative Example 11: In Step 3.4) of Example 1, the BFT-CMMC adsorbent was changed to industrial activated carbon (200 mesh, specific surface area 1200 m 2 / g), the dosage remains unchanged at 2 kg; the rest is the same as in Example 1.

[0226] Comparative Example 12: Change the BFT-CMMC adsorbent in step 3.4) of Example 1 to silica gel (particle size 2 - 5 mm, pore size 3 nm), and the dosage remains unchanged at 2 kg; the rest is the same as in Example 1.

[0227] Comparative Example 13: Change the BFT-CMMC adsorbent in step 3.4) of Example 1 to molecular sieve (type 13X, pore size ), and the dosage remains unchanged at 2 kg; the rest is the same as in Example 1.

[0228] The comparison of the obtained results is shown in Table 5 below.

[0229] Table 5

[0230]

[0231] Example 11: Regenerate the used BFT-CMMC adsorbent in Example 1: First, backwash the bed with 10 BV of methanol (65 L) in the reverse direction, and then calcine the washed BFT-CMMC adsorbent at 500 °C for 3 h under nitrogen protection to remove organic residues. The specific surface area of the regenerated adsorbent maintains 98.7% of the initial value (measured by the BET method). After refilling, perform adsorption refining, and the rest is the same as in Example 1. The above is for 1 cycle of reuse.

[0232] Examples 12 - 15: Repeat the regeneration process of Example 11, and the number of cycles of reuse increases to 2 - 5 times.

[0233] The comparison of the obtained results is shown in Table 6 below.

[0234] Table 6

[0235] Number Adsorbent type Number of cycles D4 (ppm) D5 (ppm) D6 (ppm) Total content (ppm) Example 1 BFT-CMMC 0 4.8 7.2 4.1 16.1 Example 11 BFT-CMMC 1 5.1 7.6 4.7 17.4 Example 12 BFT-CMMC 2 5.4 8.1 5.0 18.5 Example 13 BFT-CMMC 3 5.9 8.7 5.4 20.0 Example 14 BFT-CMMC 4 6.3 9.2 5.8 21.3 Example 15 BFT-CMMC 5 6.8 9.9 6.1 22.8

[0236] After 5 cycles, the adsorption capacity still remains > 80% (total content in Example 14 is 22.8 ppm vs 16.1 ppm for the new adsorbent).

[0237] Comparative Example 1 of BFT-CMMC adsorbent

[0238] Change the gradient calcination pore formation in step 3.3) of Preparation Example 1 of BFT-CMMC adsorbent to a one-step calcination process (directly raise the temperature to 600 °C and hold for 5 h, skipping the 350 °C stage). The rest is similar to Preparation Example 1 of BFT-CMMC adsorbent, and the obtained product is named BFT-CMMC adsorbent A, which is used in Example 1.

[0239] Comparative Example 2 of BFT-CMMC adsorbent

[0240] In step 3.1) of BFT-CMMC Preparation Example 1, the loading of the dual template was cancelled, that is, the amounts of CTAB and PMMA microspheres were both changed to 0; the rest was similar to BFT-CMMC Adsorbent Preparation Example 1, and the obtained product was named BFT-CMMC Adsorbent B, which was used in Example 1.

[0241] Comparative Example 3 of BFT-CMMC adsorbent

[0242] The BFT-CMMC adsorbent was subjected only to the phenylboronic acid group grafting in step 4.1), and the subsequent perfluoroalkylsilane modification was omitted, i.e., the amount of perfluorododecyltrimethoxysilane in step 4.2) was changed to 0. The remaining procedures were similar to those in BFT-CMMC Adsorbent Preparation Example 1. The resulting product was named BFT-CMMC Adsorbent C, and this BFT-CMMC Adsorbent C was used in Example 1.

[0243] Comparative Example 4 of BFT-CMMC adsorbent

[0244] Cancel the titanium zinc ferrite magnetic core (Ti) of BFT-CMMC preparation example 1 0.1 Zn 0.3 Fe 2.6 O4), the "TiZnFeO magnetic core" in step 2 was replaced with ordinary Fe3O4 (i.e., Zn / Ti doping was omitted), the amount remained unchanged, and the rest was similar to BFT-CMMC adsorbent preparation example 1. The obtained product was named BFT-CMMC adsorbent D, and this BFT-CMMC adsorbent D was used in Example 1.

[0245] The results are compared in Table 7 below.

[0246] Table 7

[0247]

[0248] Finally, it should be noted that the above examples are merely specific embodiments of the present invention. Obviously, the present invention is not limited to the above examples and is subject to numerous variations. All variations that can be directly derived or conceived by a person of ordinary skill in the art from the disclosure of the present invention are considered to be within the scope of protection of the present invention.

Claims

1. A preparation method of a polyether-modified silicone oil with low cyclic siloxane residue, characterized in that It includes the following steps: (1) Synthesis of hydrogen-containing silicone oil: 1.1) Under the protection of inert gas, using octamethylcyclotetrasiloxane and hexamethyldisiloxane as reaction materials, ring-opening polymerization reaction is carried out under the action of an acidic composite catalyst; the molar ratio of octamethylcyclotetrasiloxane to hexamethyldisiloxane is 9 - 11:1; 1.2) Add sodium bicarbonate to the reaction product obtained in step 1.1) to neutralize the acidic composite catalyst, and after filtration, the obtained filtrate is hydrogen-containing silicone oil; (2) Hydrosilylation reaction: Under the protection of inert gas, according to the molar ratio of Si-H bond to allyl group of 1:1 - 1.25, mix the hydrogen-containing silicone oil obtained in step (1) with allyl polyether, and dehydrate first; then add a platinum catalyst and methylbutynol for reaction; the reaction temperature is 80 - 120 °C, and the reaction time is 3 - 6 hours to obtain a crude product of polyether polyol-modified silicone oil; (3) Post-treatment and purification: Carry out post-treatment and purification on the crude product of polyether polyol-modified silicone oil obtained in step (2); Obtain polyether-modified silicone oil with low cyclic siloxane residue.

2. The preparation method of the polyether-modified silicone oil with low cyclic siloxane residue according to claim 1, characterized in that: The post-treatment and purification in step (3) are carried out in the following steps in sequence: Carry out nitrogen bubbling combined with ultrasonic-assisted degassing on the crude product of polyether polyol-modified silicone oil obtained in step (2), then carry out wiped-film molecular distillation, then supercritical CO2 extraction, and finally carry out adsorption refining using BFT-CMMC adsorbent; obtain polyether-modified silicone oil with low cyclic siloxane residue.

3. According to the preparation method of the polyether-modified silicone oil with low cyclic siloxane residue described in claim 2, it is characterized in that: In step 1.1): The acidic composite catalyst is prepared by mixing trifluoromethanesulfonic acid and trimethylchlorosilane according to a mass ratio of 1:(1 ± 0.1), and the addition amount of the acidic composite catalyst is 0.05 - 0.12 wt% of the mass of octamethylcyclotetrasiloxane; the ring-opening polymerization reaction is carried out for 6 ± 0.5 h, and the reaction temperature is 60 ± 10 °C; In step 1.2): Pass through a 0.45 μm filter; In step (2): The addition amount of the platinum catalyst is 6 - 16 ppm of the mass of the hydrogen-containing silicone oil, and the addition amount of methylbutynol is 0.05 - 0.1% of the mass of the hydrogen-containing silicone oil; the platinum catalyst is karstedt platinum catalyst; In step (3): Pass the material through a fixed-bed adsorption column filled with BFT-CMMC adsorbent, the adsorption temperature is 40 - 60 °C, and the flow rate is 1 - 3 BV / h.

4. According to the preparation method of the polyether-modified silicone oil with low cyclic siloxane residue described in claim 3, it is characterized in that: The allyl polyether in step (2) is a copolymer of ethylene oxide (EO) and propylene oxide (PO), and the EO / PO molar ratio is 2:

1.

5. The preparation method of the polyether-modified silicone oil with low cyclic siloxane residue according to any one of claims 1 to 4, characterized in that The preparation steps of the BFT-CMMC adsorbent include: I. Synthesis of titanium-zinc ferrite magnetic core: According to the molar ratio of Ti:Zn:Fe = 1:(3 ± 0.1):(26 ± 0.5), dissolve zinc nitrate, ferric chloride and tetrabutyl titanate in water, adjust the pH to 11 - 12, and obtain TiZnFeO magnetic core through hydrothermal reaction; the hydrothermal reaction is carried out at 200 ± 20 °C for 24 ± 2 h; II. Graphite carbon nitride coating: Prepare melamine into a g-C3N4 precursor; Disperse the TiZnFeO magnetic core and the g-C3N4 precursor in Solvent I to form a suspension, where the mass ratio of the TiZnFeO magnetic core to the g-C3N4 precursor is 1:(0.5±0.05); Then remove Solvent I, and anneal at 300±20°C for 2±0.5 h under the protection of inert gas to obtain g-C3N4-coated particles; III. Construction of mesoporous SiO2 shell: Using CTAB and PMMA microspheres as double templating agents, grow the SiO2 shell by the sol-gel method, and gradiently calcine to remove the templates to form a mesoporous SiO2 shell as the mesoporous material; CTAB is cetyltrimethylammonium bromide, and PMMA is polymethyl methacrylate; IV. Surface bifunctional modification: Graft phenylboronic acid groups and perfluoroalkylsilanes onto the mesoporous material in sequence to obtain a surface bifunctional modification product; V. Product post-treatment: Perform spherical granulation on the surface bifunctional modification product.

6. The preparation method of the polyether-modified silicone oil with low cyclic siloxane residue according to claim 5, wherein: The step III includes the following steps: 3.1) Loading of double templating agents: Add the g-C3N4-coated particles into Solvent I to obtain a g-C3N4-coated particle suspension; Add CTAB and PMMA microspheres to the g-C3N4-coated particle suspension, and stir magnetically to allow the templating agents to be fully adsorbed on the surface of the g-C3N4-coated particles; The mass ratio of the g-C3N4-coated particles to CTAB to PMMA microspheres is 0.5:(2±0.1):(1±0.05); 3.2) Growth of SiO2 by sol-gel method: Dropwise add a mixed solution of tetraethyl orthosilicate and ammonia water to the product obtained in step 3.1), and react at 40±10°C for 6±1 h; For every 1 g of the PMMA microspheres in the product obtained in step 3.1), (5±0.5) mL of tetraethyl orthosilicate and (2±0.2) mL of ammonia water are used; After the reaction, centrifuge to collect the precipitate and wash it; 3.3) Gradient calcination for pore formation: Heat the washed precipitate obtained in step 3.2) to 350±30°C and hold for 3±0.5 h to remove CTAB, continue to heat to 600±50°C and hold for 2 h±0.5 to remove PMMA, and after cooling, obtain the mesoporous SiO2 shell; The step IV includes the following steps: 4.1) Grafting of phenylboronic acid groups: Dissolve 3-acrylamidophenylboronic acid in a borate buffer solution, add the mesoporous material obtained in step III, and react at 70±10°C for 12±1 h; the mass ratio of 3-acrylamidophenylboronic acid to the mesoporous material is (1.5±0.1):1; After the reaction, wash and dry the obtained solid to obtain the grafted product; 4.2) Modification with perfluoroalkylsilane: Mix perfluorododecyltrimethoxysilane with the grafted product obtained in step 4.1) in Solvent II, and react at 110±10°C for 24±2 h under the protection of inert gas; for every 1 g of the grafted product obtained from the mesoporous material, 2±0.2 mL of perfluorododecyltrimethoxysilane is used; After the reaction is completed, the obtained solid is washed and then activated under vacuum to obtain a surface bifunctionalized modified product.

7. The method for preparing a polyether-modified silicone oil with low cyclic siloxane residue according to claim 6, characterized in that: In the first step: For every 0.1 mol of tetrabutyl titanate, 200 ± 50 mL of deionized water is used; After the hydrothermal reaction is completed and cooled to room temperature, the obtained precipitate is washed successively with ethanol and deionized water, and then dried under vacuum to obtain a TiZnFeO magnetic core; In the second step: Melamine is heated to 550 ± 30 °C under the protection of an inert gas and calcined for 4 ± 0.5 h to obtain a g-C3N4 precursor; The solvent I is anhydrous ethanol; for every 1 g of the TiZnFeO magnetic core, 200 ± 50 mL of anhydrous ethanol is used; In step 3.1): The solvent I is anhydrous ethanol; for every 0.50 g of the g-C3N4-coated particles, 100 ± 20 mL of anhydrous ethanol is used; In step 3.2): Wash successively with an ethanol / hydrochloric acid mixture (V / V = 9:1) and deionized water; In step 3.3): The heating rate for heating to 350 ± 30 °C is 2 ± 0.5 °C / min, and the heating rate for heating to 600 ± 50 °C is 5 ± 0.5 °C / min; In step 4.1): For every 1.5 g of 3-acrylamidophenylboronic acid, 100 ± 20 mL of borate buffer solution is used; after the reaction is completed, wash with acetone and dry at 80 ± 10 °C for 6 ± 0.5 h; In step 4.2): The solvent II is toluene; for every 2 mL of perfluorododecyltrimethoxysilane, 50 ± 10 mL of toluene is used; After the reaction is completed, the obtained solid is washed with toluene and ethanol, and then activated under vacuum at 120 ± 10 °C for 4 ± 0.5 h to obtain a surface bifunctionalized modified product.

8. The preparation method of the polyether-modified silicone oil surfactant with low cyclic siloxane residue according to claim 7, characterized in that The spherical granulation in the fifth step: First, add polyvinyl alcohol as a binder to the surface bifunctionalized modified product, and then prepare to obtain spherical particles. After drying, calcine at 500 ± 20 °C for 1 ± 0.1 h to obtain a BFT-CMMC adsorbent; The polyvinyl alcohol binder is 2.5 - 3.5% of the weight of the surface bifunctionalized modified product.

9. The preparation method of the polyether-modified silicone oil surfactant with low cyclic siloxane residue according to any one of claims 2 to 8, characterized in that: The regeneration method of the BFT-CMMC adsorbent includes the following steps: (1) Reverse-flush the adsorbent bed with methanol or ethanol, and the flushing volume is 5 - 10 BV; (2) Under the protection of nitrogen, calcine at 400 - 600 °C for 2 - 4 hours to remove organic residues.

10. A polyether-modified silicone oil with low cyclic siloxane residue prepared by using any one of the methods according to claims 1 - 9.

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