Vinyl silicone oil and preparation method thereof

Abstract

The invention discloses vinyl silicone oil and a preparation method thereof, and belongs to the technical field of organic silicon materials. The preparation method comprises the following steps: carrying out vacuum molecular distillation and purification on raw materials, preparing a bidentate carboxylate ligand from hydroxyl-carboxyl bidentate substituted aromatic acid, carrying out ion exchange on the bidentate carboxylate ligand and P5 < + > Cl <-> to prepare a P5 < + >-L catalyst, finally catalyzing ring-opening copolymerization of D4, D4Vi and an end-capping reagent, and carrying out glacial acetic acid quenching, stepped vacuum devolatilization and filtration to obtain the product. The product is applied to the fields of high-end electronics, medical use and the like. In order to overcome the defects of poor catalyst selectivity, non-uniform vinyl distribution and high residue in the prior art, the invention provides a bidentate ligand phosphazene salt catalytic system, realizes selective polymerization of monomers through the synergistic effect of bidentate coordination and zwitterions, solves the problems of continuous blocks of MeViSiO units, metal residues and excessive volatile impurities, and improves the yield of the catalyst. The product is high in purity and stable in performance, and meets the requirements of high-end fields.

Description

Technical Field

[0001] This invention relates to the field of organosilicon materials technology, and in particular to a vinyl silicone oil and its preparation method. Background Technology

[0002] Vinyl silicone oil, as a core raw material for addition-type silicone materials, is widely used in high-end fields such as electronic packaging, optical devices, and medical materials due to its excellent temperature resistance, insulation, and mechanical compatibility. The uniformity of vinyl distribution in its molecular chain and the amount of residual vinyl groups directly determine the crosslinking performance and safety of downstream materials, making it a key focus of industry research and development. Currently, industrially, vinyl silicone oil is mostly prepared using octamethylcyclotetrasiloxane (D4) as the base monomer and methylvinylcyclotetrasiloxane as the functional monomer, synthesized via ring-opening polymerization. However, in existing preparation technologies, the catalytic system generally lacks monomer insertion selectivity, easily leading to the formation of continuous block structures in the MeViSiO units. This results in downstream products exhibiting problems such as excessively dense local crosslinking, high brittleness, and poor fatigue resistance, making it difficult to meet the requirements of high-end applications.

[0003] To address the aforementioned issues, existing technologies often attempt to regulate vinyl distribution by adjusting monomer ratios and optimizing polymerization process parameters. Some studies have also employed phosphazene salt catalysts to replace traditional alkali metal catalysts in order to reduce metal ion residues and improve polymerization controllability. Some schemes have also attempted to introduce bidentate aromatic acids as ligands to prepare modified phosphazene salt catalysts.

[0004] However, existing solutions still have significant shortcomings: First, process adjustments alone cannot solve the problem of monomer selective polymerization at the catalytic mechanism level, and the problem of continuous MeViSiO blocks has not been fundamentally improved; second, the bidentate aromatic acid ligands used in modified phosphazene salt catalysts are mostly customized products, lacking targeted structural selection, and the synergistic coordination of hydroxyl and carboxyl groups is not fully utilized, resulting in limited improvement in catalytic selectivity; third, some processes have low solvent recycling rates and ineffective recovery of by-products, resulting in poor industrial economics, and the residual volatile cyclosiloxanes in the products are prone to exceed the standard, making them unsuitable for demanding applications such as medical and flexible displays. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a vinyl silicone oil and its preparation method.

[0006] The technical solutions provided by the embodiments of the present invention are as follows: A method for preparing a vinyl silicone oil includes the following steps: S1. Raw material pretreatment: Octamethylcyclotetrasiloxane, 1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane, and 1,3-divinyltetramethyldisiloxane were purified by vacuum molecular distillation at a temperature of 95-125℃, a vacuum of 1-4 Pa, and a distillation rate of 4-9 mL / h. The moisture content of the purified raw materials was <40 ppm. The above-mentioned raw material pretreatment process employs vacuum molecular distillation for purification. The core principle relies on the short-range molecular motion of molecular distillation and the low boiling point characteristics under vacuum to achieve the purification and dehydration of the raw materials. Octamethylcyclotetrasiloxane, 1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane, and 1,3-divinyltetramethyldisiloxane are all organosilicon cyclic / oligomers. At distillation temperatures of 95-125℃ and a high vacuum environment of 1-4 Pa, the mean free path of the raw material molecules increases, allowing them to rapidly move from the evaporation surface to the condensation surface for separation, thus avoiding the high-temperature pyrolysis of conventional distillation. Mix with reflux; control the distillation rate of 4-9 mL / h to ensure full separation of raw material molecules, while preventing impurities from co-distilling with the raw material. Trace amounts of water and low-boiling-point light impurities in the raw material, with boiling points much lower than the target raw material under the vacuum and temperature conditions, will be preferentially separated and removed, while the raw material itself will be enriched and collected on the condensation surface, ultimately achieving the purification of the raw material, reducing the water content of the purified raw material to below 40 ppm, effectively removing aqueous impurities that will affect the subsequent polymerization reaction, avoiding problems such as catalyst deactivation and uneven degree of polymerization, and ensuring the controllability and selectivity of the subsequent ring-opening polymerization reaction; S2. Preparation of multi-active-center organophosphorus nitrile salt catalysts: S201. Under nitrogen protection, phosphorus pentachloride and tris(dimethylamino)phosphorus were reacted in anhydrous toluene at a low temperature of -25 to -15°C for 0.5 to 1 h. The mixture was then heated to room temperature and refluxed for 65 to 75 h. After cooling, the precipitate was removed by filtration, and the solvent and excess raw material were removed by vacuum distillation. The mixture was washed three times with anhydrous diethyl ether and dried under vacuum for 4 to 6 h to obtain white P5. + Cl - solid; Phosphorus pentachloride and tris(dimethylamino)phosphorus in a molar ratio of 1:(9.5-10.5) undergo a multi-step N-nucleophilic addition-elimination reaction to generate the target product tetrakis[tris(dimethylamino)imino]phosphorus chloride. In tris(dimethylamino)phosphorus, the nitrogen atom in the dimethylamino group has a lone pair of electrons, which is the nucleophilic center of the reaction. The dimethylamino group is a functional group formed by connecting one nitrogen atom to two methyl groups. The main reaction formula is:

[0007] The target product is P5 as described in the process. + The cation combines with chloride ions via ionic bonds to form an ionic solid, P5.+ Cl - In the reaction, an excess of tris(dimethylamino)phosphine is added, which serves both as a reaction reagent and as a solvation aid, thereby increasing the yield of the target product. Low-temperature initiation stage (-25 to -15℃, 0.5~1h): In anhydrous toluene solvent, the phosphorus atom in phosphorus pentachloride carries a strong electrophilic positive charge due to its bond with a strongly electronegative chlorine atom, thus becoming the reaction center. The nitrogen atom in the dimethylamino group of tris(dimethylamino)phosphide has strong nucleophilicity, and its lone pair electrons launch a nucleophilic attack on the electrophilic P atom of phosphorus pentachloride, resulting in an N-nucleophilic addition reaction to form a primary reaction intermediate connected by PN coordinate bonds. At the same time, an elimination reaction is carried out to generate Me2NCl (dimethylaminochloride) as a byproduct. The low temperature environment at this stage is the classic temperature control method described in the literature, which can effectively suppress side reactions such as self-polymerization of tris(dimethylamino)phosphide and polychlorination of phosphorus pentachloride, and only complete the reaction initiation, laying the foundation for the subsequent construction of the phosphorus-nitrogen skeleton. Reflux ring-forming stage (toluene reflux temperature, 65-75h): After heating the system to the toluene reflux temperature, the primary intermediate continues to undergo a series of N-nucleophilic addition-elimination reactions with excess tris(dimethylamino)phosphine in the system. Each step involves the nucleophilic N atom of tris(dimethylamino)phosphine attacking the electrophilic P center of the intermediate, progressively constructing a multi-phosphorus PN framework bridged by N atoms, while continuously generating Me₂NCl (dimethylaminochloride) as a byproduct. After multiple addition-elimination steps, the PN framework undergoes rearrangement and aromatization, ultimately forming a structurally stable tetra(tris(dimethylamino)phosphine-n-phosphine-n-phosphine)phosphonium cation (i.e., P₅). + The cation combines with chloride ions in the system through ionic bonds to generate tetrakis(tris(dimethylamino)phosphine-amino)phosphine solid crude product that is insoluble in toluene. The unreacted excess tris(dimethylamino)phosphine and Me2NCl byproducts in the system are retained in the toluene solution. After multiple addition-elimination steps, a structurally stable tetra(tris(dimethylamino)phosphine-1,4-phosphonium)phosphonium cation (i.e., P5) is finally formed. + The cation combines with chloride ions in the system through ionic bonds to generate tetrakis(tris(dimethylamino)phosphine-amino)phosphine solid crude product that is insoluble in toluene. The excess tris(dimethylamino)phosphine and byproducts in the system are retained in the toluene solution. Post-processing purification stage: After the reaction was completed, the system was cooled, and the solid crude tetrakis(tris(dimethylamino)phosphine-amino)chloride was separated by filtration. The toluene filtrate containing dissolved byproducts and excess raw materials was removed. The crude product was subjected to vacuum distillation to remove the toluene solvent and trace amounts of low-boiling-point byproducts adsorbed on the solid surface. After washing three times with anhydrous diethyl ether, residual polar impurities in the crude product were removed. Finally, the product was vacuum dried for 4-6 hours to remove diethyl ether and trace amounts of water, yielding a white, high-purity solid product. S202. A substituted aromatic acid containing a hydroxy-carboxyl bidentate structure is reacted with sodium carbonate in anhydrous ethanol at a molar ratio of 1:(1.0-1.05) for 1.5-2.5 h at room temperature. The precipitate is collected by filtration, washed twice with anhydrous ethanol, and dried under vacuum for 6-8 h to obtain the bidentate carboxylate ligand Na. + L - ; Taking 5-methylsalicylic acid as an example, it undergoes a neutralization reaction with sodium carbonate at a molar ratio of 1:(1.0-1.05). 1 mol of sodium carbonate can react quantitatively with 2 mol of 5-methylsalicylic acid to produce sodium 5-methylsalicylate (Na₂O₃). + L - (L- is 5-methylsalicylate) and carbonic acid. Carbonic acid decomposes into carbon dioxide and water at room temperature. Since the reaction system is anhydrous ethanol, the trace amount of water generated will be dispersed by the ethanol system and will not affect the product structure. The specific reaction formula is as follows:

[0008] A small excess of sodium carbonate (molar ratio 1.0-1.05) is used in the reaction to ensure complete reaction of 5-methylsalicylic acid and improve product yield. 5-Methylsalicylic acid is a substituted aromatic acid containing an ortho-hydroxy-carboxyl group. The carboxyl group (-COOH) at the ortho position of its benzene ring exhibits typical organic acidity. In anhydrous ethanol, the carboxyl group can ionize. Sodium carbonate is a weak inorganic base; in the alcohol phase, it dissociates to release carbonate ions (CO3-). 2- It can react with the ionized carboxyl group, and the first step combines to form bicarbonate (HCO3-). - The second step involves further combination to form carbonic acid (H2CO3). Carbonic acid is unstable and rapidly decomposes into carbon dioxide gas and water at room temperature. This process is a typical acid-base proton transfer reaction. The hydroxyl group (-OH) at the ortho position of the benzene ring in 5-methylsalicylic acid is extremely weakly ionized due to the electronic effects of the benzene ring and carboxyl group. It cannot ionize under the weakly alkaline conditions of sodium carbonate and therefore does not participate in the neutralization reaction, remaining intact in the product structure. Ultimately, the carboxyl group of 5-methylsalicylic acid loses its charge and forms a negatively charged carboxylate group, which then combines with the ionized product from sodium carbonate via ionic bonds to form sodium 5-methylsalicylate (Na₂O₃). + L -Its molecule still retains the bidentate structure of the ortho-hydroxy-carboxylate group, which is necessary for subsequent interaction with P5. + Cl - The ion exchange reaction provides a coordination basis; The reaction is carried out in anhydrous ethanol at room temperature for 1.5-2.5 hours to ensure complete reaction of the raw materials. The generated sodium 5-methylsalicylate has low solubility in anhydrous ethanol and will precipitate out of the system as a white solid precipitate. The carbon dioxide gas generated in the reaction escapes from the system, while trace amounts of water are dispersed in the ethanol. The solid crude sodium 5-methylsalicylate can be quickly separated by filtration, and the ethanol filtrate containing trace amounts of water and unreacted sodium carbonate is removed. The crude product was washed twice with anhydrous ethanol to remove filtrate residue and trace amounts of unreacted raw materials adsorbed on the solid surface. Since anhydrous ethanol does not react with sodium 5-methylsalicylate and does not dissolve the product, product loss was avoided. Finally, the washed solid was vacuum dried for 6-8 hours to remove the ethanol solvent adsorbed on the solid surface, yielding high-purity sodium 5-methylsalicylate solid (bidentate carboxylate ligand Na). + L - The product yield is ≥92%, and the bidentate coordination structure of the ortho-hydroxy-carboxylate group is completely preserved, which can be directly used for subsequent catalyst assembly reactions. S203, under anhydrous and oxygen-free conditions, P5 + Cl - with Na + L - An ion exchange reaction was carried out in anhydrous tetrahydrofuran at a molar ratio of 1:(1.05-1.15) for 2.5-3.5 h at 20-30 °C. The sodium chloride solid was removed by filtration, the solvent was removed under reduced pressure, and methyl tert-butyl ether was added. Crystallization was carried out at -10 to -5 °C for 12-16 h. After filtration, the product was dried under vacuum for 6-8 h to obtain P5. + -L catalyst; Sodium 5-methylsalicylate (Na) + L - L - Using 5-methylsalicylate as a ligand precursor, it reacts with tetrakis[tris(dimethylamino)phosphine-imideamino]phosphine chloride (P5) + Cl - A quantitative ion exchange reaction occurs, and the reaction equation is:

[0009] The sodium chloride produced in the reaction has extremely low solubility in anhydrous tetrahydrofuran and precipitates as a white solid precipitate. The target product is P5. + -L dissolves in the reaction solvent; The above reaction is a typical double displacement ion exchange reaction, with the core driving force stemming from the low solubility of the product sodium chloride and P5. +It binds to the stable ion pair of 5-methylsalicylate in anhydrous tetrahydrofuran system, where P5 + Cl - Both sodium 5-methylsalicylate and sodium 5-methylsalicylate exist as ionic compounds. The polarity of the solvent allows for slight dissociation of the two reactants, forming free P5 groups. + Cations, Cl - Anions, and Na + Cation, 5-methylsalicylate (L - Anions; Because 5-methylsalicylic acid itself has a bidentate structure with an ortho-hydroxyl group and a carboxylate group, its electron cloud density distribution is uniform, similar to P5. + Cations have a higher charge-matching degree and can form stable, loose ion pairs through electrostatic interactions; while Na... + With Cl - The ionic bond energy is extremely high, making it difficult to dissociate in non-aqueous polar solvents, rapidly forming an insoluble sodium chloride solid precipitate. This phase difference of the product drives the reaction towards complete forward reaction. An excess of 5%–15% sodium 5-methylsalicylate can ensure the P5 concentration in the system. + Cl - Complete reaction is ensured to avoid residual chloride ions affecting subsequent catalytic performance; Meanwhile, the ortho-hydroxyl group and carboxylate group in 5-methylsalicylate do not undergo chemical changes during ion exchange, fully preserving the bidentate coordination structure, thus laying the structural foundation for selective control during subsequent catalytic polymerization of vinyl silicone oil; the anhydrous and oxygen-free environment effectively prevents P5 + The cation is deactivated by hydrolysis and the 5-methylsalicylate is oxidized, ensuring the specificity of the reaction; After the above reaction is completed, the target product P5 is present in the system. + A solution of -L tetrahydrofuran and a solid precipitate of sodium chloride were obtained. The sodium chloride solid could be rapidly separated by filtration, removing inorganic byproducts from the system. The filtrate was then subjected to reduced pressure to remove the solvent. Taking advantage of the volatility of tetrahydrofuran, it was completely removed under low temperature and pressure to obtain P5. + -L of concentrated oily substances or crude solids; Methyl tert-butyl ether was added to the crude product. Taking advantage of the extremely low low-temperature solubility of the target product in this solvent, the system was placed at -10 to -5°C for 12-16 hours to crystallize P5. + -L precipitates as regular white crystals, while trace amounts of unreacted sodium 5-methylsalicylate in the system dissolve in methyl tert-butyl ether, thus separating the product from trace impurities. Finally, the precipitated crystals are vacuum dried for 6-8 hours to completely remove the methyl tert-butyl ether solvent adsorbed on the crystal surface, yielding high-purity P5. +-L solid catalyst, with a complete bidentate coordination structure, can be directly used in the selective polymerization reaction of vinyl silicone oil; S3, Polymerization reaction: In a nitrogen-protected stainless steel reactor, pretreated raw materials are added in a molar ratio of octamethylcyclotetrasiloxane, 1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane:1,3-divinyltetramethyldisiloxane = 100:(1.2-11):(0.6-6). The temperature is raised to 65-95℃, and P5 is added at 0.015%-0.12% of the total monomer mass. + -L catalyst, stir the reaction for 3-7 hours, and the reaction system pressure is 0.12-0.28 MPa; The above reaction is an anionic ring-opening copolymerization reaction, P5 + The -L catalyst first undergoes nucleophilic activation with the cyclosiloxane monomer, followed by ring-opening of octamethylcyclotetrasiloxane D4 and 1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane, which then undergo chain propagation and chain termination reactions with the end-capping agent, ultimately generating a Vi-(Me2SiO) molecular chain. a -(MeViSiO) b The overall reaction formula for -Vi vinyl silicone oil is expressed as follows:

[0010] The 0.12-0.28 MPa in the reaction system is the autogenous pressure of the monomer and solvent at the reaction temperature, while nitrogen protection prevents oxidation of the system and deactivation of the catalyst. The above polymerization reaction belongs to controlled anionic ring-opening polymerization (AROP), which follows the classic reaction mechanism of "activation-ring opening-chain propagation-chain termination", and because P5 + The unique structure of the -L catalyst enables selective insertion of monomers, which involves four steps: Catalyst nucleophilic activation stage: P5 + 5-methylsalicylate anion in the -L catalyst (L - As a nucleophilic center, it initiates a nucleophilic attack on the Si-O bonds of D4 and D4Vi cyclosiloxane monomers at 65-95℃, polarizing the five-membered ring structure of the cyclosiloxane. The Si atoms acquire a partial positive charge, and the ring structure changes from a stable state to an activated state. This process is consistent with the literature mechanism of phosphazene salt-catalyzed ring-opening of cyclosiloxanes. The phosphazene salt cation P5 + The extremely strong basicity provides the driving force for nucleophilic activation; Ring-opening stage: The Si-O bond of the activated cyclosiloxane monomer breaks, and the original cyclic structure becomes a linear active chain end with a negatively charged oxygen atom at the chain end, forming a polysiloxane oxygen anion active species; due to the steric hindrance and electronic effect regulation of 5-methylsalicylate, D4 ​​and D4Vi monomers do not undergo continuous ring-opening, but complete the ring-opening process in an alternating manner, avoiding continuous blockage of MeViSiO units. Chain growth stage: The oxygen anions at the ends of the linear active chains continue to nucleophilically attack the unopened D4 and D4Vi monomers in the system, causing the monomers to continuously open their rings and attach to the active chains, thus achieving gradual chain growth. During the growth process, the catalyst maintains a loose bond with the ends of the active chains, preventing chain transfer and ensuring a narrow molecular weight distribution (PDI ≤ 1.12). This controllability stems from P5. + The loose ion pair formed with L is consistent with the ion pair mechanism of phosphazene salt catalyzing the ring-opening of epoxy monomers; Chain termination stage: 1,3-divinyltetramethyldisiloxane in the system acts as a capping agent. The vinyl siloxane bonds at both ends of its molecule undergo a nucleophilic reaction with the active chain end, deactivating the oxygen anion at the active chain end and terminating the molecular chain growth. The amount of capping agent is precisely controlled according to the monomer molar ratio to ultimately achieve the target structure where both ends of the molecular chain are vinyl, and the a / b ratio is controlled between 40 and 50. P5 + The catalytic mechanism of -L catalyst (5-methylsalicylate anion): P5 + The catalytic activity and selectivity of the -L catalyst originate from P5 + The superbasic nature of the cation and the 5-methylsalicylate anion (L - The bidentate structure effect of the two components, working synergistically, enables efficient and selective ring-opening copolymerization of cyclosiloxanes. P5 + The core role of cations: P5 + It is a tetrakis[tris(dimethylamino)phosphine-amino]phosphine cation, belonging to the super-base cation class of phosphazene salts. Its basicity is much higher than that of traditional KOH catalysts, which can effectively polarize the Si-O bonds of cyclosiloxanes, reduce the activation energy of ring-opening reactions, and enable the polymerization reaction to proceed efficiently at a mild temperature of 65-95℃; at the same time, P5 + It has a large steric hindrance, forms loose ion pairs with anions, and does not form strong bonds with the active chain ends, thus avoiding side reactions such as chain transfer and chain association, ensuring the controllability of the polymerization reaction, and making the molecular weight distribution of the product narrow. Selective Regulation of 5-Methylsalicylate Anion: As a catalyst anion, 5-methylsalicylate itself does not directly participate in the ring-opening reaction, but achieves selective regulation of monomer insertion through steric hindrance and electronic effects. This effect is consistent with the literature mechanism of bidentate ligand regulation of polymerization selectivity: First, the benzene ring skeleton of 5-methylsalicylate forms steric hindrance with the adjacent hydroxyl and carboxylate groups, which will block the continuous approach of D4Vi monomers and avoid the continuous ring-opening and insertion of MeViSiO units; Second, the hydroxyl group in its molecule forms a bidentate coordination structure with the carboxylate group, which selectively recognizes D4 and D4Vi monomers through the electrostatic effect of the electron cloud, so that the two monomers are inserted into the molecular chain in an alternating manner, ultimately achieving the goal of continuous MeViSiO unit molar ratio ≤5%; Synergistic catalytic effect of cations and anions: P5 + The strong alkalinity of the catalyst provides the driving force for nucleophilic ring opening, while the bidentate structure of the 5-methylsalicylate provides selectivity for monomer insertion. The catalytic system formed by these two components ensures the high efficiency of the polymerization reaction (the reaction can be completed in 3-7 hours with high conversion rate) and solves the problem of lack of monomer selectivity in traditional phosphazene alkaline catalysts. At the same time, the catalyst dosage is only 0.015%-0.12% of the total monomer mass, which is a low-concentration catalysis. This is consistent with the literature characteristics of low dosage and high activity of phosphazene salt catalysts, and it does not introduce metal residues into the product, resulting in a total metal ion residue of <8 ppb in the product. S4. Post-processing: Add 0.05-0.15 mL / g of monomer glacial acetic acid to the reaction system and stir for 15-25 min; use a step-by-step vacuum devolatilization: first, devolatilize at 115-125℃ and vacuum degree ≤150 Pa for 1.5 h, and after sampling and testing, the total content of volatile cyclosiloxanes (D3-D6) is ≤0.2%, then raise the temperature to 135-145℃ and vacuum degree ≤80 Pa for 2.5-3.5 h, and after cooling to room temperature, filter through a 0.22 μm polytetrafluoroethylene filter membrane to obtain highly selective vinyl silicone oil; The key function of adding glacial acetic acid to the polymerization system is to make P5... + -L catalysts are deactivated by oxygen anions at the active chain ends, thereby terminating the polymerization reaction. Glacial acetic acid, acting as a proton donor, reacts with two active species in the system: on the one hand, it reacts with the polysiloxane oxygen anions (Si–O) at the active chain ends. - The reaction generates neutral silanol groups (Si–OH), terminating chain growth; on the other hand, it reacts with P5 + -L catalyst anion (L -The 5-methylsalicylate ion undergoes a protonation reaction to generate 5-methylsalicylic acid (HL), completely deactivating the catalyst. Glacial acetic acid is far more acidic than 5-methylsalicylic acid and the silanol group of polysiloxane, thus efficiently transferring protons to the strongly basic anion in the system, completely eliminating its nucleophilic activity. The byproduct of the reaction, P5, is then produced. + Ac - 5-methylsalicylic acid (HL) can be effectively removed in subsequent vacuum devolatilization and filtration steps; The subsequent stepwise vacuum devolatilization is a physical separation process. Its core is to utilize the vapor pressure differences of different substances at different temperatures and vacuum levels to separate low-boiling-point impurities from high-viscosity vinyl silicone oil. The first stage is devolatilization at 115-125℃ and a vacuum of ≤150Pa for 1.5 hours. The goal of this stage is to remove most of the volatile low-boiling-point impurities in the system, mainly including unreacted cyclosiloxane monomers such as D4 and D4Vi, as well as oligomeric cyclosiloxanes (D3-D6) generated during polymerization and trace amounts of solvents and volatile byproducts. Under these conditions, the vapor pressure of these low-boiling-point substances increases significantly, volatilizes from the silicone oil, and is removed by the vacuum system. At the end of this stage, the total content of volatile cyclosiloxanes (D3-D6) can be reduced to ≤0.2%. The second stage involves heating to 135-145℃ and performing de-vaporization at a vacuum of ≤80Pa for 2.5-3.5 hours. This stage utilizes higher temperatures and vacuum levels to remove residual oligomeric cyclosiloxanes and other trace impurities with higher boiling points. Increasing the temperature significantly reduces the bulk viscosity of the high-viscosity vinyl silicone oil, enhances internal mass transfer, and makes it easier for residual low-boiling compounds encapsulated within the molecular chains to diffuse to the surface and volatilize. Increasing the vacuum level further lowers the boiling point of the system, ensuring that residual volatile components such as D3-D6 are completely removed, ultimately reducing their total content to below 0.08%. After cooling to room temperature, the system was filtered through a 0.22 μm polytetrafluoroethylene (PTFE) membrane to remove trace amounts of residual solid impurities, mainly insoluble byproducts generated during the quenching reaction, such as 5-methylsalicylic acid (HL) and P5. + Ac - The polytetrafluoroethylene (PTFE) filter membrane effectively traps micron-sized solid particles, as well as metal debris or other mechanical impurities that detach from the inner wall of the reactor. With its excellent chemical inertness and precise pore size control, it can effectively trap micron-sized solid particles while allowing liquid vinyl silicone oil to pass through smoothly, thus obtaining a clear, high-purity final product.

[0011] Preferably, the substituted aromatic acid containing a hydroxy-carboxyl bidentate structure is one of 5-methylsalicylic acid, 5-methoxysalicylic acid, or 3-hydroxy-4-methoxybenzoic acid.

[0012] Preferably, catalyst P5 +-L has a pKa value of 22.8-23.6 and a thermal decomposition temperature of ≥130℃.

[0013] Preferably, anhydrous toluene and anhydrous tetrahydrofuran are recovered and reused through distillation, with a recovery rate of over 90% and 85%, respectively; the sodium chloride solid produced by filtration is recovered according to industrial salt standards after washing and drying.

[0014] Preferably, the specific process of step-by-step vacuum devolatilization is as follows: first, devolatilize at 115-125℃ and vacuum degree ≤150Pa for 1.5h, and after sampling and testing, the total content of volatile cyclosiloxanes (D3-D6) is ≤0.2%, and then the temperature is raised to 135-145℃ and vacuum degree ≤80Pa for 2.5-3.5h.

[0015] Preferably, P5 + It is a cation with a core of tetrakis[tris(dimethylamino)imino]phosphocation, L - The catalyst is an aromatic carboxylic acid anion with a bidentate coordination structure containing hydroxyl and carboxyl groups. Through the synergistic coordination of hydroxyl and carboxyl groups in the bidentate ligand, combined with steric hindrance and electronic effects, the selective polymerization of octamethylcyclotetrasiloxane and 1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane monomers is achieved, thereby inhibiting the continuous insertion of MeViSiO units.

[0016] Preferably, the vinyl silicone oil produced by the above method is used in the preparation of high-end electronic potting compounds, addition-type liquid silicone rubber, optical lens encapsulation materials, semiconductor chip heat dissipation materials, precision mold release agents, flexible display device encapsulation materials, or medical biocompatible organosilicon materials.

[0017] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention uses substituted aromatic acids with a hydroxyl-carboxyl bidentate structure as ligands to prepare organophosphorus nitrile salt catalysts. By combining the electrostatic coordination and steric hindrance mechanism between the ligand and the cation, selective insertion of D4 and D4Vi monomers is achieved from the catalytic source. This solves the common industry problem that traditional catalysts cannot control the distribution of vinyl groups and that MeViSiO units are easy to continuously block. It also ensures uniform crosslinking and stable mechanical properties downstream from the structural level.

[0018] 2. This invention employs a synergistic catalysis of tetrakis[tris(dimethylamino)imino]phosphine cation and bidentate aromatic acid anion, combined with an anionic ring-opening polymerization mechanism that activates Si-O bonds with a superbase, to achieve highly efficient and controllable polymerization without metal participation. This solves the problems of high metal ion residue and insufficient product purity caused by traditional alkali metal catalysts, achieving a total metal ion residue of <8ppb in the product, which can be directly used in high-end clean fields such as electronics and medical applications.

[0019] 3. This invention employs a bidentate coordination structure of ortho-hydroxyl-carboxyl to precisely control the polymerization process. Combined with the synergistic mechanism of ligand electronic effects and steric hindrance effects, it significantly improves catalytic selectivity without using complex and customized ligands. This solves the problems of insufficient selectivity, difficulty in obtaining ligands, and high cost of existing phosphazene catalysts. At the same time, it achieves a volatile cyclosiloxane residue of <0.08%, and the product has high purity, high uniformity, and high industrial feasibility. Detailed Implementation

[0020] The technical solutions of this invention are described below. It should also be noted that, to make the embodiments more detailed, the following embodiments are the best and preferred embodiments; those skilled in the art can also use other alternative methods to implement some well-known technologies.

[0021] Example 1: Preparation of vinyl silicone oil: S1. Raw material pretreatment: Octamethylcyclotetrasiloxane, 1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane, and 1,3-divinyltetramethyldisiloxane were purified by vacuum molecular distillation at a temperature of 110°C, a vacuum of 2 Pa, and a distillation rate of 6 mL / h. The moisture content of the purified raw materials was <40 ppm. S2. Preparation of multi-active-center organophosphorus nitrile salt catalysts: S201. Under nitrogen protection, phosphorus pentachloride and tris(dimethylamino)phosphorus were reacted in anhydrous toluene at a molar ratio of 1:(9.5-10.5) at -20°C for 1 h. The mixture was then heated to room temperature and refluxed for 70 h. After cooling, the precipitate was removed by filtration, and the solvent and excess raw material were removed by vacuum distillation. The mixture was washed three times with anhydrous diethyl ether and dried under vacuum for 5 h to obtain white P5. + Cl - solid; S202. 5-Methylsalicylic acid and sodium carbonate were reacted in anhydrous ethanol at a molar ratio of 1:1.02 at room temperature for 2 hours. The precipitate was collected by filtration, washed twice with anhydrous ethanol, and dried under vacuum for 7 hours to obtain the bidentate carboxylate ligand Na. + L - ; S3, Polymerization reaction: In a nitrogen-protected stainless steel reactor, pretreated raw materials were added in a molar ratio of octamethylcyclotetrasiloxane, 1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane:1,3-divinyltetramethyldisiloxane = 100:6.6:3.3. The mixture was heated to 80°C, and then 0.015% (by mass) of P5 was added. + -L catalyst, stirred for 5 hours, reaction system pressure was 0.2 MPa; S4. Post-processing: Add 0.1 mL / g monomer of glacial acetic acid to the reaction system and stir for 20 min. Use a step-by-step vacuum devolatilization method: first, devolatilize at 120℃ and vacuum degree ≤150 Pa for 1.5 h. After sampling and testing, the total content of volatile cyclosiloxanes (D3-D6) is less than 0.2%. Then, raise the temperature to 140℃ and vacuum degree ≤80 Pa for 3 h. After cooling to room temperature, filter through a 0.22 μm polytetrafluoroethylene filter membrane to obtain highly selective vinyl silicone oil.

[0022] Example 2: Preparation of vinyl silicone oil: S1. Raw material pretreatment: Octamethylcyclotetrasiloxane, 1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane, and 1,3-divinyltetramethyldisiloxane were purified by vacuum molecular distillation at a temperature of 110°C, a vacuum of 2 Pa, and a distillation rate of 6 mL / h. The moisture content of the purified raw materials was <40 ppm. S2. Preparation of multi-active-center organophosphorus nitrile salt catalysts: S201. Under nitrogen protection, phosphorus pentachloride and tris(dimethylamino)phosphorus were reacted in anhydrous toluene at a molar ratio of 1:(9.5-10.5) at -20°C for 1 h. The mixture was then heated to room temperature and refluxed for 70 h. After cooling, the precipitate was removed by filtration, and the solvent and excess raw material were removed by vacuum distillation. The mixture was washed three times with anhydrous diethyl ether and dried under vacuum for 5 h to obtain white P5. + Cl - solid; S202. 5-Methylsalicylic acid and sodium carbonate were reacted in anhydrous ethanol at a molar ratio of 1:1.02 at room temperature for 2 hours. The precipitate was collected by filtration, washed twice with anhydrous ethanol, and dried under vacuum for 7 hours to obtain the bidentate carboxylate ligand Na. + L - ; S3, Polymerization reaction: In a nitrogen-protected stainless steel reactor, pretreated raw materials were added in a molar ratio of octamethylcyclotetrasiloxane, 1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane:1,3-divinyltetramethyldisiloxane = 100:6.6:3.3. The mixture was heated to 80°C, and then 0.07% (by mass) of P5 was added. + -L catalyst, stirred for 5 hours, reaction system pressure was 0.2 MPa; S4. Post-processing: Add 0.1 mL / g monomer of glacial acetic acid to the reaction system and stir for 20 min. Use a step-by-step vacuum devolatilization method: first, devolatilize at 120℃ and vacuum degree ≤150 Pa for 1.5 h. After sampling and testing, the total content of volatile cyclosiloxanes (D3-D6) is less than 0.2%. Then, raise the temperature to 140℃ and vacuum degree ≤80 Pa for 3 h. After cooling to room temperature, filter through a 0.22 μm polytetrafluoroethylene filter membrane to obtain highly selective vinyl silicone oil.

[0023] Example 3: Preparation of vinyl silicone oil: S1. Raw material pretreatment: Octamethylcyclotetrasiloxane, 1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane, and 1,3-divinyltetramethyldisiloxane were purified by vacuum molecular distillation at a temperature of 110°C, a vacuum of 2 Pa, and a distillation rate of 6 mL / h. The moisture content of the purified raw materials was <40 ppm. S2. Preparation of multi-active-center organophosphorus nitrile salt catalysts: S201. Under nitrogen protection, phosphorus pentachloride and tris(dimethylamino)phosphorus were reacted in anhydrous toluene at a molar ratio of 1:(9.5-10.5) at -20°C for 1 h. The mixture was then heated to room temperature and refluxed for 70 h. After cooling, the precipitate was removed by filtration, and the solvent and excess raw material were removed by vacuum distillation. The mixture was washed three times with anhydrous diethyl ether and dried under vacuum for 5 h to obtain white P5. + Cl - solid; S202. 5-Methoxysalicylic acid and sodium carbonate were reacted in anhydrous ethanol at a molar ratio of 1:1.02 at room temperature for 2 hours. The precipitate was collected by filtration, washed twice with anhydrous ethanol, and dried under vacuum for 7 hours to obtain the bidentate carboxylate ligand Na. + L - ; S3, Polymerization reaction: In a nitrogen-protected stainless steel reactor, pretreated raw materials were added in a molar ratio of octamethylcyclotetrasiloxane, 1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane:1,3-divinyltetramethyldisiloxane = 100:6.6:3.3. The mixture was heated to 80°C, and then 0.07% (by mass) of P5 was added. + -L catalyst, stirred for 5 hours, reaction system pressure was 0.2 MPa; S4. Post-processing: Add 0.1 mL / g monomer of glacial acetic acid to the reaction system and stir for 20 min. Use a step-by-step vacuum devolatilization method: first, devolatilize at 120℃ and vacuum degree ≤150 Pa for 1.5 h. After sampling and testing, the total content of volatile cyclosiloxanes (D3-D6) is less than 0.2%. Then, raise the temperature to 140℃ and vacuum degree ≤80 Pa for 3 h. After cooling to room temperature, filter through a 0.22 μm polytetrafluoroethylene filter membrane to obtain highly selective vinyl silicone oil.

[0024] Comparative Example 1: Compared with Example 3, P5 in Comparative Example 1 + - The amount of L catalyst added accounts for 0.15% of the total mass of the monomer, while other conditions remain unchanged.

[0025] Comparative Example 2: Compared with Example 3, Comparative Example 2 did not add P5. + -L catalyst, with other conditions remaining unchanged.

[0026] Comparative Example 3: Compared with Example 3, Comparative Example 3 used benzoic acid to react with sodium carbonate, while other conditions remained unchanged.

[0027] Comparative Example 4: Compared to Example 3, in Comparative Example 4, the KOH conventional alkaline catalyst was subjected to hot water extraction, with all other conditions remaining unchanged.

[0028] Performance testing: The dynamic viscosity at 25℃ was determined according to GB / T10247-2017 "Methods for Measurement of Fluid Viscosity"; the molecular weight and molecular weight distribution index were determined according to GB / T36214.1-2018 "Determination of Average Molecular Weight and Molecular Weight Distribution of Polymers by Volume Exclusion Chromatography - Part 1: General Rules"; the vinyl content and residual amount of volatile cyclosiloxanes (D3-D6) were determined according to GB / T36691-2018 "Methyl Vinyl Silicone Rubber"; and nuclear magnetic resonance spectroscopy (NMR) was used to determine the molecular weight and molecular weight distribution index of polymers. 1 The vinyl silicone oil was analyzed by sequence structure analysis using 1H NMR with deuterated chloroform as solvent and tetramethylsilane as internal standard. The continuous block structure without MeViSiO units was determined by the characteristic peak interval. The moisture content was determined according to GB / T6283-2008 "Determination of Moisture Content in Chemical Products - Karl Fischer Method (General Method)". The total amount of residual metal ions was determined by inductively coupled plasma mass spectrometry.

[0029] Table 1 Basic performance indicators of each sample

[0030] Table 2 Purity and structural characterization indices of each sample

[0031] Data Analysis: Based on the test data in Tables 1 and 2 above, the vinyl silicone oil prepared in Example 3 exhibits better performance. As a standard example of the present invention, Example 3 uses 5-methoxysalicylic acid to prepare a bidentate carboxylate ligand, and with a catalyst dosage of 0.07%, all performance parameters are optimal. Its dynamic viscosity and number-average molecular weight are within a reasonable range, its PDI value is the lowest, and its vinyl content is stable. Simultaneously, the residual volatile cyclosiloxanes, metal ions, and moisture content are all at extremely low levels. 1 HNMR characterization of the continuous block structure without MeViSiO units fully demonstrates the superiority of methoxy-substituted aromatic acids as ligands. Mechanistically, the bidentate ligand formed by 5-methoxysalicylic acid, with its strong electron-donating effect of the methoxy group, significantly enhances the synergistic coordination between the hydroxyl and carboxyl groups. Combined with moderate steric hindrance, it can accurately identify D4 and D4Vi monomers, enabling alternating insertion and effectively avoiding continuous block structure; P5 + The strong alkalinity of the cation can efficiently polarize the Si-O bond, reduce the ring-opening activation energy, and form a loose ion pair with the bidentate ligand with strong stability, which can avoid side reactions such as chain transfer and chain association, and ensure the controllability of polymerization. Combined with the step-by-step vacuum devolatilization and membrane filtration process, low-boiling substances and trace impurities can be completely removed, ultimately achieving high purity and high uniformity of the product, providing a core benchmark for subsequent sample comparison.

[0032] Compared to Example 3, Example 1 showed a slight deterioration in overall performance. The key differences were slightly lower dynamic viscosity, number-average molecular weight, and vinyl content compared to the standard example. Purity indicators such as residual metal ions and moisture content remained essentially the same, and there was no continuous MeViSiO block. The core mechanism causing this change is that the ligand used in Example 1 was 5-methylsalicylic acid. Compared to the 5-methoxysalicylic acid in the standard example, it lacked the electron-donating effect of the methoxy group, resulting in insufficient electron cloud density in the bidentate coordination structure. This led to a slight decrease in the selective recognition ability of D4 and D4Vi monomers, and slightly poorer monomer insertion uniformity, resulting in a slower molecular chain growth rate and consequently a slight decrease in molecular weight and dynamic viscosity. Simultaneously, the catalyst dosage in Example 1 was only 0.015%, far lower than the standard example, resulting in insufficient catalytic active sites and slightly less complete polymerization, leading to a slight decrease in vinyl content. However, because the core structure of the bidentate ligand remained unchanged, continuous block was effectively avoided, and the purity indicators remained excellent, further highlighting the importance of the methoxy ligand and appropriate catalyst dosage.

[0033] Compared to Example 3, Example 2 exhibits slightly inferior performance, with slightly lower dynamic viscosity and number-average molecular weight, and a slightly lower vinyl content than the standard example. Other purity indicators are essentially the same as the standard example, and it lacks the MeViSiO continuous block. From a mechanistic perspective, the core difference between Example 2 and the standard example lies in the ligand type. Example 2 uses 5-methylsalicylic acid as the ligand, lacking the electron-donating effect of dioxygen groups. The bidentate ligand and P5... + The ion pair formed by the cation is slightly less stable, and its activation efficiency and selective control ability for monomers are not as good as those of 5-methoxysalicylic acid ligand, resulting in insufficient molecular chain growth and slightly lower dynamic viscosity and molecular weight than the standard example. In addition, the lack of methoxy electronic regulation slightly reduces the uniformity of monomer insertion, indirectly leading to a slight decrease in vinyl content. However, the bidentate coordination structure can still effectively block the continuous insertion of D4Vi monomers, so there are no continuous blocks and the purity index remains good, which confirms the advantages of methoxy-substituted aromatic acids as ligands.

[0034] The key difference between Comparative Example 1 and Example 3 is a significantly higher molecular weight distribution index (PDI), a slight decrease in dynamic viscosity and number-average molecular weight, a vinyl content that is essentially close to the standard example, and no significant fluctuations in purity indicators such as volatile cyclosiloxane residue and metal ion residue, and the absence of MeViSiO continuous blocks. Investigating the mechanism of these changes, the only variable in Comparative Example 1 was the increased catalyst dosage to 0.15%, far exceeding the 0.07% of the standard example, indicating an excess of P5. + -L catalysts result in an excessive number of catalytically active sites in the system, leading to an excessively rapid polymerization rate and localized chain transfer during chain growth. Simultaneously, excessive catalysts can disrupt the synergistic effect of anions and cations, affecting P5. + The stability of the loose ion pairs formed with bidentate ligands decreases, and some active chain ends associate, which in turn broadens the molecular weight distribution and increases the PDI. The excessively fast polymerization rate also leads to uneven molecular chain growth, resulting in a slightly lower dynamic viscosity and number-average molecular weight than the standard example. Since the catalyst itself has no metal residue and the devolatilization and filtration processes have not been changed, the purity-related indicators remain basically consistent.

[0035] Comparative Example 2 and Example 3 show fundamentally different data; this sample has no valid performance data. 1 ¹H NMR characterization showed no polymerization reaction, which is directly related to the differences in the processes used. From the polymerization mechanism perspective, the preparation of vinyl silicone oil in this invention belongs to controlled anionic ring-opening polymerization, P5. + -L catalyst is the core driving force of the reaction: P5 +The superbasicity of the cation can polarize the Si-O bond of the cyclosiloxane, reducing the ring-opening activation energy, while the bidentate ligand enables selective insertion of monomers. The synergistic effect of the two is necessary to initiate the ring-opening, chain growth, and chain termination reactions. In Comparative Example 2, no catalyst was added, and there was no nucleophilic activation center in the system. The D4 and D4Vi monomers could not undergo the ring-opening reaction, let alone achieve molecular chain growth. Therefore, the target product could not be generated, and there was no relevant data for various performance indicators, which fully confirms the indispensability of the catalyst in the polymerization reaction.

[0036] Compared to Example 3, Comparative Example 3 showed significant deterioration in all aspects of its performance. PDI increased significantly, while dynamic viscosity, number-average molecular weight, and vinyl content decreased. Volatile cyclosiloxane residue also increased substantially. 1 ¹H NMR characterization revealed the presence of some continuous blocks of MeViSiO units, with a slight increase in residual metal ions. The core mechanism lies in the fact that, in Comparative Example 3, benzoic acid was used instead of 5-methoxysalicylic acid in the standard example to prepare the ligand. Benzoic acid only contains a carboxyl group, lacks a bidentate coordination structure, and lacks the electron-donating effect of the methoxy group, thus losing the synergistic regulatory effect of steric hindrance and electronic effects. Without the selective recognition of the bidentate ligand, the D4Vi monomer can continuously approach the active chain end and undergo ring-opening insertion, leading to the formation of locally continuous blocks of MeViSiO units. Simultaneously, the monodentate ligand interacts with P5... + The ion pairs formed by the cations are less stable and are prone to chain transfer reactions, which broadens the molecular weight distribution and increases the PDI. The continuous block structure will encapsulate some low-boiling substances, hindering their diffusion and volatilization during the devolatilization process, resulting in a significant increase in the residual volatile cyclosiloxanes. The overall performance is inferior to the standard example, highlighting the synergistic advantages of the bidentate structure and the methoxy ligand.

[0037] Compared to Example 3, Comparative Example 4 showed significantly worse performance across all indicators, making it the worst performing group among all samples. Specifically, it exhibited the lowest dynamic viscosity and number-average molecular weight, a significantly increased PDI, the lowest vinyl content, volatile cyclosiloxane residues far exceeding those of the standard example, and a sharp increase in metal ion residues. 1 1H NMR characterization revealed the presence of numerous continuous blocks of MeViSiO units. From a mechanistic perspective, Comparative Example 4 used a conventional KOH catalyst instead of the P5 catalyst of this invention. + -L catalysts, such as KOH as an alkali metal catalyst, lack monomer selectivity control and cannot suppress the continuous ring-opening insertion of D4Vi monomers, thus forming a large number of MeViSiO continuous blocks; its basicity is much weaker than P5. +The cations cannot efficiently polarize Si-O bonds, resulting in high activation energies in polymerization reactions, incomplete reactions, and a tendency for side reactions such as chain transfer and chain association, leading to a broadened molecular weight distribution and increased PDI. Simultaneously, KOH introduces a large number of metal ions, which cannot be completely removed by simple hot water extraction, resulting in a sharp increase in metal residues. The increased side reactions and incomplete reactions significantly increase the residues of volatile cyclosiloxanes, rendering the overall performance far below the requirements for high-end applications, thus highlighting the advantages of the P5 invention. + Superiority of -L bidentate ligand catalysts.

[0038] Analysis of all examples and comparative examples shows that Example 3, as a standard example, uses 5-methoxysalicylic acid to prepare bidentate ligands and controls an appropriate amount of catalyst, resulting in the best overall performance. This fully demonstrates that bidentate ligands formed by methoxy-substituted aromatic acids are compatible with P5+. + The synergistic catalytic advantage of cations enables selective insertion and controllable polymerization of monomers, ensuring high purity and uniformity of the product. The differences between Examples 1 and 2 and the standard examples mainly stem from the ligand type and catalyst dosage. The absence of a dioxygen-supported 5-methylsalicylic acid ligand and insufficient catalyst dosage lead to a slight deterioration in performance, but the bidentate structure still avoids continuous block polymerization and maintains good purity. In Comparative Example 1, excessive catalyst disrupts the synergistic effect between anions and cations, resulting in a wider molecular weight distribution, while other purity indicators remain relatively stable. In Comparative Example 2, the lack of catalyst prevents the polymerization reaction from starting, resulting in no target product formation. In Comparative Example 3, the use of a benzoic acid ligand without a bidentate structure leads to a loss of selective control, resulting in continuous block polymerization and deterioration of various performance characteristics. In Comparative Example 4, using a traditional KOH catalyst, not only fails to achieve selective polymerization of monomers but also causes a sharp increase in metal residues, significantly deteriorating performance. Overall, the 5-methoxysalicylic acid bidentate ligand used in this invention, along with P5... + The -L catalyst system, combined with appropriate process parameters, can effectively solve the problems of continuous block polymerization, high metal residue, and poor polymerization controllability in traditional preparation techniques, highlighting the technical advantages of this invention.

[0039] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. This invention discloses a vinyl silicone oil and its preparation method, belonging to the field of organosilicon material technology. The preparation method includes vacuum molecular distillation purification of raw materials, preparation of bidentate carboxylate ligands from hydroxyl-carboxyl-containing bidentate-substituted aromatic acids, and then reacting with P5... + Cl - P5 was prepared by ion exchange + The -L catalyst ultimately catalyzes the ring-opening copolymerization of D4, D4Vi, and the end-capping agent. The product is obtained through glacial acetic acid quenching, stepwise vacuum devolatilization, and filtration. The product is used in high-end electronics and medical fields. This invention addresses the shortcomings of existing technologies, such as poor catalyst selectivity, uneven vinyl distribution, and high residue levels. It proposes a bidentate ligand phosphazene salt catalytic system. Through bidentate coordination and synergistic effects of anions and cations, selective polymerization of monomers is achieved. This solves the problems of continuous block polymerization of MeViSiO units, metal residue, and excessive volatile impurities. The product has high purity and stable performance, meeting the needs of high-end applications.

2. A method for preparing the vinyl silicone oil as described in claim 1, characterized in that, Includes the following steps: S1. Raw material pretreatment: Octamethylcyclotetrasiloxane, 1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane, and 1,3-divinyltetramethyldisiloxane were purified by vacuum molecular distillation at a temperature of 95-125℃, a vacuum of 1-4 Pa, and a distillation rate of 4-9 mL / h. The moisture content of the purified raw materials was <40 ppm. S2. Preparation of multi-active-center organophosphorus nitrile salt catalysts: S201. Under nitrogen protection, phosphorus pentachloride and tris(dimethylamino)phosphorus were reacted in anhydrous toluene at a low temperature of -25 to -15°C for 0.5 to 1 h. The mixture was then heated to room temperature and refluxed for 65 to 75 h. After cooling, the precipitate was removed by filtration, and the solvent and excess raw material were removed by vacuum distillation. The mixture was washed three times with anhydrous diethyl ether and dried under vacuum for 4 to 6 h to obtain white P5. + Cl - solid; S202. A substituted aromatic acid containing a hydroxy-carboxyl bidentate structure is reacted with sodium carbonate in anhydrous ethanol at a molar ratio of 1:(1.0-1.05) for 1.5-2.5 h at room temperature. The precipitate is collected by filtration, washed twice with anhydrous ethanol, and dried under vacuum for 6-8 h to obtain the bidentate carboxylate ligand Na. + L - ; S203, under anhydrous and oxygen-free conditions, P5 + Cl - with Na + L - An ion exchange reaction was carried out in anhydrous tetrahydrofuran at a molar ratio of 1:(1.05-1.15) for 2.5-3.5 h at 20-30 °C. The sodium chloride solid was removed by filtration, the solvent was removed under reduced pressure, and methyl tert-butyl ether was added. Crystallization was carried out at -10 to -5 °C for 12-16 h. After filtration, the product was dried under vacuum for 6-8 h to obtain P5. + -L catalyst; S3, Polymerization reaction: In a nitrogen-protected stainless steel reactor, pretreated raw materials are added in a molar ratio of octamethylcyclotetrasiloxane, 1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane:1,3-divinyltetramethyldisiloxane = 100:(1.2-11):(0.6-6). The temperature is raised to 65-95℃, and P5 is added at 0.015%-0.12% of the total monomer mass. + -L catalyst, stir the reaction for 3-7 hours, and the reaction system pressure is 0.12-0.28 MPa; S4. Post-processing: Add 0.05-0.15 mL / g of monomer glacial acetic acid to the reaction system and stir for 15-25 min; perform stepwise vacuum devolatilization, cool to room temperature, and filter through a 0.22 μm polytetrafluoroethylene filter membrane to obtain highly selective vinyl silicone oil.

3. The method for preparing a vinyl silicone oil according to claim 2, characterized in that, The substituted aromatic acid containing a hydroxy-carboxyl bidentate structure in S202 is one of 5-methylsalicylic acid, 5-methoxysalicylic acid, or 3-hydroxy-4-methoxybenzoic acid.

4. The method for preparing a vinyl silicone oil according to claim 2, characterized in that, The catalyst P5 in S203 + -L has a pKa value of 22.8-23.6 and a thermal decomposition temperature of ≥130℃.

5. The method for preparing a vinyl silicone oil according to claim 2, characterized in that, Anhydrous toluene and anhydrous tetrahydrofuran in S2 are recovered and reused through distillation, with a recovery rate of over 90% and 85%, respectively. The sodium chloride solid produced by filtration is recovered according to industrial salt standards after washing and drying.

6. The method for preparing a vinyl silicone oil according to claim 2, characterized in that, The specific process of S4 step vacuum devolatilization is as follows: first, devolatilize at 115-125℃ and vacuum degree ≤150Pa for 1.5h, and after sampling and testing, the total content of volatile cyclosiloxanes (D3-D6) is ≤0.2%. Then, the temperature is raised to 135-145℃ and vacuum degree ≤80Pa for 2.5-3.5h.

7. A multi-active-center organophosphorus nitrile salt catalyst P5 used in the preparation method as described in claim 2. + -L, characterized in that, P5 + The catalyst has a tetrakis[tris(dimethylamino)imino]phosphocation as its cationic core and L⁻ as its anion, which is an aromatic carboxylate anion with a bidentate coordination structure containing hydroxyl and carboxyl groups. The catalyst achieves selective polymerization of octamethylcyclotetrasiloxane and 1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane monomers through the synergistic coordination of hydroxyl and carboxyl groups in the bidentate ligand, combined with steric hindrance and electronic effects, thereby inhibiting the continuous insertion of MeViSiO units.

8. An application of the vinyl silicone oil as described in claim 1, characterized in that, It is used in the preparation of high-end electronic potting compounds, addition-type liquid silicone rubber, optical lens encapsulation materials, semiconductor chip heat dissipation materials, precision mold release agents, flexible display device encapsulation materials, or medical biocompatible organosilicon materials.

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