A high refractive index silicone oil and its preparation method

Abstract

This invention provides a high refractive index silicone oil and its preparation method. The high refractive index silicone oil is obtained by ring-opening copolymerization of a mixture of cyclic siloxanes catalyzed by a phosphorus-nitrogen organic base catalyst. The structural formula of the high refractive index silicone oil is as follows: where R is at least one of SiMe3 and SiMe2Vi, R1 is at least one of methyl and phenyl, and m, n, o, and x are integers from 1 to 10000. The silicone oil prepared by this method has a phenyl structural unit molar fraction of not less than 40%, and its refractive index at 25°C can be flexibly adjusted between 1.50 and 1.59, with a maximum of 1.59. Simultaneously, it allows for independent adjustment of the phenyl content, vinyl content, and viscosity, thereby enabling the stable preparation of a high refractive index silicone oil with a well-defined structure and uniform performance.

Description

Technical Field

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

[0002] High-refractive-index silicone oils are a class of special organosilicon materials obtained by introducing high content of phenyl and other aryl groups into the polysiloxane backbone. Their refractive index can be increased from around 1.40 for ordinary silicone oils to over 1.55, making them valuable for applications in high-end LED packaging, precision optical device filling, high-end daily chemical products, and optical coatings. Achieving precise and synergistic control over phenyl content, vinyl content, and viscosity is a key technical challenge in preparing high-performance, high-refractive-index silicone oils.

[0003] Currently, the industrial preparation of high-refractive-index silicone oil mainly involves ring-opening copolymerization of phenylcyclosiloxane monomers with other cyclic monomers under the action of a catalyst. The catalysts used are often strong acids (such as sulfuric acid and trifluoromethanesulfonic acid) or strong bases (such as tetramethylammonium hydroxide and potassium hydroxide). However, the polymerization reaction of the above methods often requires high temperatures (>120℃) or long durations (>10 hours), resulting in high energy consumption and a tendency to induce thermal crosslinking and color degradation, severely affecting the optical transmittance of the product. To achieve a refractive index >1.50, a high proportion of phenyl monomers needs to be added, but existing catalysts lack sufficient ring-opening activity for these monomers, resulting in a typically low content of phenylsiloxane units in the obtained silicone oil, making it difficult to consistently achieve a refractive index above 1.55. Furthermore, in systems with high phenyl content, the monomer activity varies greatly, and steric hindrance is significant. Although traditional strong base catalysts have high activity, they are prone to side reactions (such as rearrangement and cyclization), leading to a wide molecular weight distribution of the product. This makes it difficult to achieve independent and precise control of phenyl content, vinyl content, and viscosity, resulting in poor batch stability of the product.

[0004] Therefore, there is an urgent need to provide a high refractive index silicone oil and its preparation method. Summary of the Invention

[0005] This invention provides a high refractive index silicone oil and its preparation method, which can solve the problems of low catalytic efficiency, poor controllability of product structure and molecular weight, and low refractive index in existing preparation methods.

[0006] In a first aspect, the present invention provides a high refractive index silicone oil, which is obtained by ring-opening copolymerization of a mixture of cyclic siloxanes catalyzed by a phosphorus-nitrogen organic base catalyst; The structural formula of this high refractive index silicone oil is as follows: Where R is at least one of SiMe3 and SiMe2Vi, R1 is at least one of methyl and phenyl, and m, n, o, x are integers from 1 to 10000.

[0007] Preferably, the high refractive index silicone oil has a refractive index of 1.50 to 1.59.

[0008] Preferably, the viscosity of the high refractive index silicone oil is 100~100000 mPa·s.

[0009] Preferably, the high refractive index silicone oil has a phenylsiloxane unit content of 40~100 mol% and a vinyl content of 0.4~2.5 mmol / g.

[0010] Preferably, the phosphorus-nitrogen organic base catalyst is selected from... , , , , , , or At least one of them.

[0011] In a second aspect, embodiments of the present invention also provide a method for preparing the high refractive index silicone oil described in any one of the first aspects above, the method comprising: (1) The cyclic siloxane mixture, the initiator and the capping agent are stirred and mixed to obtain a mixed system; wherein the cyclic siloxane mixture includes alkenyl-containing cyclotetrasiloxane and alkenyl-free cyclotetrasiloxane; (2) Add a phosphorus-nitrogen organic base catalyst to the mixture and carry out a ring-opening copolymerization reaction under heating conditions. After completion, add a terminator to terminate the reaction, separate the catalyst and the low-boiling-point component, and obtain the high refractive index silicone oil.

[0012] Preferably, the alkenyl-containing cyclotetrasiloxane is tetramethyltetravinylcyclotetrasiloxane; the alkenyl-free cyclotetrasiloxane is at least one of methylcyclotetrasiloxane or phenylcyclotetrasiloxane.

[0013] More preferably, the methylcyclotetrasiloxane is octamethylcyclotetrasiloxane, and the phenylcyclotetrasiloxane is at least one of tetramethyltetraphenylcyclotetrasiloxane or octaphenylcyclotetrasiloxane.

[0014] More preferably, the cyclic siloxane mixture is composed of tetramethyltetravinylcyclotetrasiloxane, tetramethyltetraphenylcyclotetrasiloxane, and octaphenylcyclotetrasiloxane.

[0015] Preferably, in step (1), based on the total amount of the cyclic siloxane mixture, the proportion of tetramethyltetravinylcyclotetrasiloxane is 0~20 mol%, the proportion of methylcyclotetrasiloxane is 0~50 mol%, and the proportion of phenylcyclotetrasiloxane is 30~100 mol.

[0016] Preferably, in step (1), the initiator is at least one of water, benzyl alcohol, ethylene glycol, 1,2-propanediol, 2,3-butanediol, terephthalic acid, cyclohexanediol, glycerol, trimethylolpropane, pentaerythritol, trimethylsilanol, dimethylphenylsilanol, methylsilanetriol, or hydroxymethyldiphenylsilane; and the end-capping agent is at least one of hexamethyldisiloxane or tetramethyldivinyldisiloxane.

[0017] Preferably, the amount of the initiator added is 1 to 20 mol% of the total amount of the cyclic siloxane mixture, and the amount of the capping agent added is 5 to 60 mol% of the total amount of the cyclic siloxane mixture.

[0018] Preferably, in step (2), the terminator is at least one of acetic acid, phosphoric acid, hydrochloric acid, sulfuric acid or carbon dioxide; the amount of the terminator added is preferably 1 to 1.5 times the molar equivalent of the catalyst.

[0019] Preferably, in step (2), the amount of phosphorus-nitrogen organic base catalyst added is 0.005~0.02% based on the total amount of the cyclic siloxane mixture.

[0020] Preferably, in step (2), the temperature of the ring-opening copolymerization reaction is 60~140℃ and the time is 1~4h.

[0021] Compared with the prior art, the present invention has at least the following beneficial effects: In this invention, a phosphorus-nitrogen organic-base catalyst is used to perform ring-opening copolymerization of a mixture of alkenyl-containing cyclotetrasiloxanes with methylcyclotetrasiloxanes and / or phenylcyclotetrasiloxanes. This catalyst exhibits excellent ring-opening activity for monomers with high phenyl content, resulting in mild polymerization conditions, fewer side reactions, a green and environmentally friendly process, and good batch stability, making it highly suitable for industrial production. The silicone oil prepared in this way has a phenyl structural unit molar fraction of not less than 40%, and its refractive index at 25°C can be flexibly adjusted between 1.50 and 1.59, with a maximum of 1.59. Simultaneously, the phenyl content, vinyl content, and viscosity can be independently adjusted, thereby stably producing high-refractive-index silicone oils with well-defined structures and uniform properties. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments or prior art of this specification, the drawings used in the description of the embodiments or prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this specification. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 The high refractive index silicone oil provided in Example 2 of this invention 1H NMR spectrum; Figure 2 The high refractive index silicone oil provided in Example 3 of this invention 1 H NMR spectrum; Figure 3 The high refractive index silicone oil provided in Example 4 of this invention 1 H NMR spectrum; Figure 4 The high refractive index silicone oil provided in Example 5 of this invention 1 H NMR spectrum; Figure 5 The high refractive index silicone oil provided in Example 9 of this invention 1 H NMR spectrum. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0025] This invention provides a high refractive index silicone oil, which is obtained by ring-opening copolymerization of a mixture of cyclic siloxanes catalyzed by a phosphorus-nitrogen organic base catalyst; The structural formula of this high refractive index silicone oil is as follows: Where R is at least one of SiMe3 and SiMe2Vi, R1 is at least one of methyl and phenyl, and m, n, o, x are integers from 1 to 10000.

[0026] In this embodiment of the invention, a phosphorus-nitrogen organic-base catalyst is used to perform ring-opening copolymerization of a mixture of alkenyl-containing cyclotetrasiloxanes with methylcyclotetrasiloxanes and / or phenylcyclotetrasiloxanes. This catalyst exhibits excellent ring-opening activity for monomers with high phenyl content, resulting in mild polymerization conditions, fewer side reactions, a green and environmentally friendly process, and good batch stability, making it very suitable for industrial production. The silicone oil prepared in this way has a phenyl structural unit molar fraction of not less than 40%, and its refractive index at 25°C can be flexibly adjusted between 1.50 and 1.59, with a maximum of 1.59. Simultaneously, the phenyl content, vinyl content, and viscosity can be independently adjusted, thereby stably producing high-refractive-index silicone oils with well-defined structures and uniform properties.

[0027] It should be noted that in the embodiments of the present invention, Me is methyl, Vi is vinyl, SiMe3 is trimethylsilyl, and SiMe2Vi is dimethylvinylsilyl.

[0028] According to some preferred embodiments, the high refractive index silicone oil has a refractive index of 1.50 to 1.59 (for example, it can be 1.50, 1.51, 1.52, 1.53, 1.54, 1.55, 1.56, 1.57, 1.58 or 1.59), preferably 1.56 to 1.59.

[0029] According to some preferred embodiments, the viscosity of the high refractive index silicone oil is 100~100000 mPa·s (for example, it can be 100 mPa·s, 200 mPa·s, 300 mPa·s, 500 mPa·s, 1000 mPa·s, 5000 mPa·s, 10000 mPa·s, 50000 mPa·s, 80000 mPa·s or 100000 mPa·s).

[0030] According to some preferred embodiments, the phenylsiloxane unit content of the high refractive index silicone oil is 40-100 mol% (e.g., 40 mol%, 50 mol%, 60 mol%, 70 mol%, 80 mol%, 90 mol%, or 100 mol%), preferably 60-100 mol%, and the vinyl content is 0.4-2.5 mmol / g (e.g., 0.4 mmol / g, 0.5 mmol / g, 0.8 mmol / g, 1.0 mmol / g, 1.2 mmol / g, 1.5 mmol / g, 1.8 mmol / g, 2.0 mmol / g, 2.2 mmol / g, or 2.5 mmol / g), preferably 1.5-2.5 mmol / g.

[0031] According to some preferred embodiments, the phosphorus-nitrogen organic base catalyst is selected from phosphoribosyl base catalysts; the phosphorus-nitrogen organic base catalyst is selected from... (abbreviated as CTPB) (abbreviated as C3N) 3- Me-P3), (abbreviated as C3N) 3- Py-P3), (abbreviated as t-BuP4) (abbreviated as P4) (abbreviated as P4-Guanidine) (abbreviated as P5OMe) or At least one of (abbreviated as P5OMe-Guanidine).

[0032] In the prior art, the preparation of high refractive index phenyl vinyl silicone oil mainly relies on the alkali-catalyzed equilibrium polymerization method. For example, Chinese patent CN104403105A discloses a method for preparing phenyl vinyl silicone oil with controllable refractive index, which uses a quaternary ammonium base organic strong base to catalyze tetramethyltetravinylcyclotetrasiloxane and phenylcyclosiloxane to obtain silicone oil with a refractive index of 1.43~1.55. However, the polymerization reaction time of this method is long, and the copolymerization ability of this catalytic system for monomers with high phenyl content is limited. The molar fraction of phenyl siloxane units in the obtained silicone oil is usually less than 40%, and the refractive index is difficult to stably reach above 1.55. For example, Chinese patent CN109280170A discloses a method for preparing functionalized polysiloxane copolymers catalyzed by phosphazene, using a specific type of phosphazene base catalytic system for the ring-opening polymerization of cyclosiloxanes. This method boasts advantages such as fast reaction speed, high conversion rate, and unbranched products. However, the application targets of this technology are all solid polysiloxane elastomers or rubbers with a number average molecular weight greater than 100,000, and it has not addressed the preparation of low molecular weight liquid silicone oil. Therefore, even if research has used phosphazene base catalytic systems to catalyze the ring-opening polymerization of cyclosiloxanes, the resulting product is still solid phenyl silicone rubber, and the method for obtaining high-refractive-index liquid silicone oil with a viscosity in the range of 100–100,000 mPa·s by controlling polymerization conditions has not been explored. Furthermore, existing technologies lack effective solutions to problems such as whether liquid silicone oil with a phenyl content higher than 70 mol% can stably exist and maintain a high refractive index of 1.55–1.59, and how to synergistically control vinyl content, refractive index, and viscosity.

[0033] Based on this, in this embodiment of the invention, suitable types of phosphazene base catalysts are screened and used to catalyze the ring-opening copolymerization of alkenyl-containing cyclotetrasiloxanes with methylcyclotetrasiloxanes and / or phenylcyclotetrasiloxanes. These catalysts have high catalytic activity and can rapidly and controllably prepare liquid silicone oils with high phenyl content (especially phenyl molar fraction > 64%) at lower temperatures, while simultaneously meeting the comprehensive performance requirements of independently adjustable refractive index of 1.50~1.59, viscosity of 100~100000 mPa·s, phenyl content of 40~100 mol%, and vinyl content of 0.4~2.5 mmol / g.

[0034] This invention also provides a method for preparing the high refractive index silicone oil described in any one of the above claims, the method comprising: (1) The cyclic siloxane mixture, the initiator and the capping agent are stirred and mixed to obtain a mixed system; wherein the cyclic siloxane mixture includes alkenyl-containing cyclotetrasiloxane and alkenyl-free cyclotetrasiloxane; (2) Add a phosphorus-nitrogen organic base catalyst to the mixture and carry out a ring-opening copolymerization reaction under heating conditions. After completion, add a terminator to terminate the reaction, separate the catalyst and the low-boiling-point component, and obtain the high refractive index silicone oil.

[0035] In this embodiment of the invention, an alkenyl-containing cyclotetrasiloxane is stirred and mixed with methylcyclotetrasiloxane and / or phenylcyclotetrasiloxane, an initiator and a capping agent. Then, a phosphorus-nitrogen organic base catalyst is added. By screening suitable types of phosphorus-nitrogen organic base catalysts, ring-opening polymerization can be efficiently catalyzed, and liquid silicone oil with high phenyl content, high refractive index and suitable viscosity can be prepared rapidly and controllably at a lower temperature. After the reaction is completed, a terminator is added to terminate the reaction and the catalyst and low-boiling-point components are separated.

[0036] According to some preferred embodiments, the catalyst separation methods include: adsorption followed by filtration using molecular sieves, activated carbon, or anion exchange resin; direct filtration using adsorption materials such as diatomaceous earth or silica gel; or washing with methanol, ethanol, or water. Low-boiling-point components are separated by vacuum distillation at a temperature of 120–200°C for 1–12 hours.

[0037] According to some preferred embodiments, the alkenyl-containing cyclotetrasiloxane is tetramethyltetravinylcyclotetrasiloxane; the alkenyl-free cyclotetrasiloxane is at least one of methylcyclotetrasiloxane or phenylcyclotetrasiloxane; the methylcyclotetrasiloxane is octamethylcyclotetrasiloxane, and the phenylcyclotetrasiloxane is at least one of tetramethyltetraphenylcyclotetrasiloxane or octaphenylcyclotetrasiloxane.

[0038] According to some preferred embodiments, in step (1), based on the total amount of the cyclic siloxane mixture, the proportion of tetramethyltetravinylcyclotetrasiloxane is 0-20 mol% (e.g., it can be 0 mol%, 2 mol%, 3 mol%, 4 mol%, 5 mol%, 6 mol%, 7 mol%, 8 mol%, 9 mol%, or 10 mol%), the proportion of methylcyclotetrasiloxane is 0-50 mol% (e.g., it can be 0 mol%, 1 mol%, 2 mol%, 5 mol%, 8 mol%, 10 mol%, 15 mol%, 20 mol%, 25 mol%, 30 mol%, 35 mol%, 40 mol%, 45 mol%, or 50 mol%), preferably, the proportion of phenylcyclotetrasiloxane is 30-100 mol% (e.g., it can be 0 mol%, 5 mol%, 10 mol%, 15 mol%, 20 mol%, 30 mol%, 40 mol%, 50 mol%, 60 mol%, 70 mol%, 80 mol%, 90 mol%, or 100 mol%), preferably 30-100 mol%.

[0039] In this embodiment of the invention, the phenyl content is the core factor determining the refractive index of silicone oil. By rationally controlling the type and amount of alkenyl-containing cyclotetrasiloxanes, methylcyclotetrasiloxanes, and / or phenylcyclotetrasiloxanes, the phenyl molar fraction of silicone oil can reach the target range, thereby giving the silicone oil the required high refractive index. The introduction of vinyl groups provides reaction sites for subsequent curing and crosslinking. Viscosity directly affects the processing rheological properties. By controlling the molecular weight of the initiator and end-capping agent according to their types and amounts, the viscosity of silicone oil can be controlled within the target range.

[0040] According to some preferred embodiments, the cyclic siloxane mixture is composed of tetramethyltetravinylcyclotetrasiloxane, tetramethyltetraphenylcyclotetrasiloxane, and octaphenylcyclotetrasiloxane.

[0041] According to some preferred embodiments, based on the total amount of the cyclic siloxane mixture, the proportion of tetramethyltetravinylcyclotetrasiloxane is 0-5 mol% (e.g., it can be 0 mol%, 1 mol%, 2 mol%, 3 mol%, 4 mol%, or 5 mol%), the proportion of tetramethyltetraphenylcyclotetrasiloxane is 50-70 mol% (e.g., it can be 50 mol%, 52 mol%, 55 mol%, 58 mol%, 60 mol%, 62 mol%, 65 mol%, 68 mol%, or 70 mol%), and the proportion of octaphenylcyclotetrasiloxane is 30-50 mol% (e.g., it can be 30 mol%, 32 mol%, 35 mol%, 38 mol%, 40 mol%, 42 mol%, 45 mol%, 48 mol%, or 50 mol%).

[0042] Traditionally, it is believed that high phenyl content can lead to increased rigidity of polysiloxane chains, crystallization, or the formation of solid resins, thus limiting the upper limit of phenyl content in liquid silicone oils. However, contrary to conventional wisdom, this invention employs copolymerization of two phenyl monomers, tetramethyltetraphenylcyclotetrasiloxane and octaphenylcyclotetrasiloxane. This not only introduces a higher phenyl content while maintaining good flexibility, significantly improving the refractive index of the silicone oil, but also utilizes a phosphazene alkaline catalyst to achieve rapid and controllable ring-opening polymerization under mild conditions. Furthermore, by adjusting the ratio of initiator to monomer, the molecular weight and viscosity of the product are controlled within a suitable range. When the phenyl molar fraction is greater than 70%, the resulting silicone oil remains a flowable liquid with a refractive index of 1.56–1.59, and no crystallization occurs.

[0043] According to some preferred embodiments, in step (1), the initiator is at least one of water, benzyl alcohol, ethylene glycol, 1,2-propanediol, 2,3-butanediol, terephthalic acid, cyclohexanediol, glycerol, trimethylolpropane, pentaerythritol, trimethylsilanol, dimethylphenylsilanol, methylsilanetriol, or hydroxymethyldiphenylsilane; the end-capping agent is at least one of hexamethyldisiloxane or tetramethyldivinyldisiloxane; preferably, the amount of the initiator added is 2 to 10 mol% of the total amount of the cyclic siloxane mixture (for example, it can be 2 mol%, 3 mol%, 5 mol%, 8 mol%, 9 mol%, or 10 mol%), and the amount of the end-capping agent added is 5 to 60 mol% of the total amount of the cyclic siloxane mixture (for example, it can be 5 mol%, 10 mol%, 15 mol%, 20 mol%, 25 mol%, 30 mol%, 35 mol%, 40 mol%, 45 mol%, 50 mol%, 55 mol%, or 60 mol%).

[0044] According to some preferred embodiments, in step (2), the terminating agent is at least one of acetic acid, phosphoric acid, hydrochloric acid, sulfuric acid, or carbon dioxide; the amount of the terminating agent added is preferably 1 to 1.5 times the molar equivalent of the catalyst (e.g., 1, 1.2, or 1.5 times); based on the total amount of the cyclic siloxane mixture, the amount of the phosphorus-nitrogen organic base catalyst added is 0.005 to 0.02% (e.g., 0.005%, 0.008%, 0.01%, 0.012%, 0.015%, 0.018%, or 0.02%); the temperature of the ring-opening copolymerization reaction is 60 to 140°C (e.g., 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, or 140°C), and the time is 1 to 4 hours (e.g., 1 hour, 2 hours, 3 hours, or 4 hours).

[0045] In this embodiment of the invention, polymerization can be achieved at a low temperature with only a small amount of catalyst and a reaction time of only 1 to 4 hours, enabling the rapid and controllable preparation of liquid silicone oil with high phenyl content and high refractive index.

[0046] To more clearly illustrate the technical solution and advantages of the present invention, a high refractive index silicone oil and its preparation method are described in detail below through several embodiments; in the following embodiments, reagents or instruments whose manufacturers are not specified are all conventional products that can be obtained commercially.

[0047] Example 1: (1) 19.7 g of alkenyl-containing cyclotetrasiloxane (tetramethyltetravinylcyclotetrasiloxane), 49.4 g of methylcyclotetrasiloxane (octamethylcyclotetrasiloxane), 90.7 g of phenylcyclotetrasiloxane (tetramethyltetraphenylcyclotetrasiloxane), 0.72 g of initiator (ethylene glycol) and 4.3 g of end-capping agent (tetramethyldivinyldisiloxane) were added to a 500 mL three-necked round-bottom flask and stirred to obtain a mixed system; (2) Add 16 mg of phosphazene base catalyst (CTPB) to the mixed system and carry out ring-opening copolymerization reaction at 60°C for 1 h. After completion, add 3 mg of terminator (phosphoric acid) to terminate the reaction. Add anion exchange resin for adsorption for 12 h, filter to separate and remove the catalyst, and then remove low-boiling substances by vacuum distillation at 120°C for 3 h to obtain high refractive index silicone oil.

[0048] In this embodiment of the invention, the high refractive index silicone oil was tested and found to contain 44.5 mol% phenylsiloxane units, 1.76 mmol / g vinyl content, and 1.50 refractive index.

[0049] Example 2: (1) 19.7 g of alkenyl-containing cyclotetrasiloxane (tetramethyltetravinylcyclotetrasiloxane), 140 g of phenylcyclotetrasiloxane (tetramethyltetraphenylcyclotetrasiloxane), 0.72 g of initiator (1,2-propanediol) and 4.3 g of end-capping agent (tetramethyldivinyldisiloxane) were added to a 500 mL three-necked round-bottom flask and stirred to obtain a mixed system; (2) Add 16 mg of phosphazene base catalyst (C3N) to the mixed system. 3- Me-P3 was subjected to ring-opening copolymerization at 60°C for 1 hour. After completion, 3 mg of terminator (sulfuric acid) was added to terminate the reaction. Molecular sieve adsorption was added for 12 hours. The catalyst was removed by filtration and separation. Then, low-boiling substances were removed by vacuum distillation at 150°C for 2 hours to obtain high refractive index silicone oil.

[0050] In this embodiment of the invention, the content of phenylsiloxane units was 81.5 mol%, the vinyl content was 1.78 mmol / g, and the refractive index was 1.53, as tested.

[0051] Example 3: (1) 19.7 g of alkenyl-containing cyclotetrasiloxane (tetramethyltetravinylcyclotetrasiloxane), 50.3 g of methylcyclotetrasiloxane (octamethylcyclotetrasiloxane), 89.7 g of phenylcyclotetrasiloxane (octaphenylcyclotetrasiloxane), 0.72 g of initiator (2,3-butanediol) and 4.3 g of end-capping agent (tetramethyldivinyldisiloxane) were added to a 500 mL three-necked round-bottom flask and stirred to obtain a mixed system; (2) Add 16 mg of phosphazene base catalyst (P5OMe) to the mixed system and carry out ring-opening copolymerization reaction at 120°C for 2 h. After completion, add 3 mg of terminator (acetic acid) to terminate the reaction. Add activated carbon for adsorption for 12 h, filter to separate and remove the catalyst, and then remove low-boiling substances by vacuum distillation at 150°C for 2 h to obtain high refractive index silicone oil.

[0052] In this embodiment of the invention, the content of phenylsiloxane units was 40.4 mol%, the vinyl content was 1.79 mmol / g, and the refractive index was 1.53, as tested.

[0053] Example 4: (1) 19.7 g of alkenyl-containing cyclotetrasiloxane (tetramethyltetravinylcyclotetrasiloxane), 38.1 g of methylcyclotetrasiloxane (octamethylcyclotetrasiloxane), 101.9 g of phenylcyclotetrasiloxane (octaphenylcyclotetrasiloxane), 0.72 g of initiator (2,3-butanediol) and 4.3 g of end-capping agent (tetramethyldivinyldisiloxane) were added to a 500 mL three-necked round-bottom flask and stirred to obtain a mixed system; (2) Add 16 mg of phosphazene base catalyst (P5OMe-Guanidine) to the mixed system and carry out ring-opening copolymerization reaction at 120°C for 2 h. After completion, add 3 mg of terminator (hydrochloric acid) to terminate the reaction. Add diatomaceous earth for filtration, separate and remove the catalyst, and then remove low-boiling substances by vacuum distillation at 180°C for 1.5 h to obtain high refractive index silicone oil.

[0054] In this embodiment of the invention, the content of phenylsiloxane units was 49.4 mol%, the vinyl content was 2.05 mmol / g, and the refractive index was 1.55, as tested.

[0055] Example 5: (1) 19.7 g of alkenyl-containing cyclotetrasiloxane (tetramethyltetravinylcyclotetrasiloxane), 27.9 g of methylcyclotetrasiloxane (octamethylcyclotetrasiloxane), 112.1 g of phenylcyclotetrasiloxane (octaphenylcyclotetrasiloxane), 0.72 g of initiator (terephthalic acid) and 4.4 g of end-capping agent (tetramethyldivinyldisiloxane) were added to a 500 mL three-necked round-bottom flask and stirred to obtain a mixed system; (2) Add 16 mg of phosphazene base catalyst (t-BuP4) to the mixed system and carry out ring-opening copolymerization reaction at 120°C for 2 h. After completion, pass in excess terminator (carbon dioxide) to terminate the reaction. Add silica gel to filter and separate to remove the catalyst. Then, remove low-boiling substances by vacuum distillation at 180°C for 1 h to obtain high refractive index silicone oil.

[0056] In this embodiment of the invention, the content of phenylsiloxane units was 58.62 mol%, the vinyl content was 1.84 mmol / g, and the refractive index was 1.56, as tested.

[0057] Example 6: (1) 383.8 g of alkenyl-containing cyclotetrasiloxane (tetramethyltetravinylcyclotetrasiloxane), 986.9 g of methylcyclotetrasiloxane (octamethylcyclotetrasiloxane), 1812.9 g of phenylcyclotetrasiloxane (tetramethyltetraphenylcyclotetrasiloxane), 14.5 g of initiator (ethylene glycol) and 86.9 g of end-capping agent (hexamethyldisiloxane) were added to a 5L three-necked round-bottom flask and stirred to obtain a mixed system; (2) Add 360 mg of phosphazene base catalyst (P4) to the mixed system and carry out ring-opening copolymerization reaction at 120 °C for 1 h. After completion, add 60 mg of terminator (phosphoric acid) to terminate the reaction. Add methanol to wash three times and filter to remove the catalyst. Then, remove low-boiling substances by vacuum distillation at 200 °C for 2 h to obtain high refractive index silicone oil.

[0058] In this embodiment of the invention, the content of phenylsiloxane units was 46.2 mol%, the vinyl content was 1.74 mmol / g, and the refractive index was 1.50, as tested.

[0059] Example 7: (1) 443.8 g of alkenyl-containing cyclotetrasiloxane (tetramethyltetravinylcyclotetrasiloxane), 3149.9 g of phenylcyclotetrasiloxane (tetramethyltetraphenylcyclotetrasiloxane), 16.1 g of initiator (pentaerythritol) and 144.5 g of end-capping agent (tetramethyldivinyldisiloxane) were added to a 5L three-necked round-bottom flask and stirred to obtain a mixed system; (2) Add 400 mg of phosphazene base catalyst (P4-Guanidine) to the mixed system and carry out ring-opening copolymerization reaction at 80°C for 2 h. After completion, pass an excess of terminator (carbon dioxide) to terminate the reaction. Wash with ethanol 3 times, filter to remove catalyst, and then distill under reduced pressure at 200°C for 2 h to remove low-boiling substances to obtain high refractive index silicone oil.

[0060] In this embodiment of the invention, the content of phenylsiloxane units was 81.2 mol%, the vinyl content was 1.79 mmol / g, and the refractive index was 1.53, as tested.

[0061] Example 8: (1) 1.8 g of alkenyl-containing cyclotetrasiloxane (tetramethyltetravinylcyclotetrasiloxane), 97.8 g of methylcyclotetrasiloxane (octamethylcyclotetrasiloxane), 392.2 g of phenylcyclotetrasiloxane (octaphenylcyclotetrasiloxane), 15.2 g of initiator (glycerol) and 91.3 g of end-capping agent (tetramethyldivinyldisiloxane) were added to a 1 L three-necked round-bottom flask and stirred to obtain a mixed system; (2) Add 60 mg of phosphazene base catalyst (C3N3-Py-P3) to the mixed system and carry out ring-opening copolymerization reaction at 120°C for 4 h. After completion, add 10 mg of terminator (phosphoric acid) to terminate the reaction. Wash with water 3 times, filter to remove catalyst, and then remove low-boiling substances by vacuum distillation at 160°C for 2 h to obtain high refractive index silicone oil.

[0062] In this embodiment of the invention, the content of phenylsiloxane units was 60.7 mol%, the vinyl content was 1.59 mmol / g, and the refractive index was 1.56, as tested.

[0063] Example 9: (1) 107.1 g of phenylcyclotetrasiloxane (45.1 g of octaphenylcyclotetrasiloxane and 62.0 g of tetramethyltetraphenylcyclotetrasiloxane), 0.72 g of initiator (ethylene glycol) and 10 g of end-capping agent (tetramethyldivinyldisiloxane) were added to a 1L three-necked round-bottom flask and stirred to obtain a mixed system; (2) Add 12 mg of phosphazene base catalyst (CTPB) to the mixed system and carry out ring-opening copolymerization reaction at 120°C for 4 h. After completion, add 2 mg of terminator (phosphoric acid) to terminate the reaction. Add anion exchange resin for adsorption for 12 h, filter to separate and remove the catalyst, and then remove low-boiling substances by vacuum distillation at 160°C for 2 h to obtain high refractive index silicone oil.

[0064] In this embodiment of the invention, the content of phenylsiloxane units was 100 mol%, the vinyl content was 0.92 mmol / g, and the refractive index was 1.59, as tested.

[0065] Example 10: (1) 631.8 g of phenylcyclotetrasiloxane (277.6 g of octaphenylcyclotetrasiloxane and 354.2 g of tetramethyltetraphenylcyclotetrasiloxane), 3.6 g of initiator (ethylene glycol) and 28.9 g of end-capping agent (tetramethyldivinyldisiloxane) were added to a 2L three-necked round-bottom flask and stirred to obtain a mixed system; (2) Add 32 mg of phosphazene base catalyst (CTPB) to the mixed system and carry out ring-opening copolymerization reaction at 120°C for 4 h. After completion, add 5 mg of terminator (phosphoric acid) to terminate the reaction. Add anion exchange resin for adsorption for 12 h, filter to separate and remove the catalyst, and then remove low-boiling substances by vacuum distillation at 160°C for 3 h to obtain high refractive index silicone oil.

[0066] In this embodiment of the invention, the content of phenylsiloxane units was 100 mol%, the vinyl content was 0.47 mmol / g, and the refractive index was 1.59, as tested.

[0067] Comparative Example 1: (1) Add 0.9 g of alkenyl-containing cyclotetrasiloxane (tetramethyltetravinylcyclotetrasiloxane), 107.1 g of phenylcyclotetrasiloxane (45.1 g of octaphenylcyclotetrasiloxane and 62.0 g of tetramethyltetraphenylcyclotetrasiloxane), 0.72 g of initiator (ethylene glycol) and 10 g of end-capping agent (tetramethyldivinyldisiloxane) to a 1 L three-necked round-bottom flask and stir to mix well to obtain a mixed system; (2) Add 60 mg of potassium hydroxide to the mixture and carry out a ring-opening copolymerization reaction at 140°C for 12 h. During the reaction, the octaphenylcyclotetrasiloxane monomer does not react completely and cannot obtain high refractive index silicone oil.

[0068] The performance of the high refractive index silicone oil samples provided in the examples and comparative examples was tested, and the test results are shown in Table 1 below: Refractive index test: The Abbe refractometer was used for the test at 25℃. Before the test, the instrument was calibrated with distilled water and a standard glass block. The sample was evenly coated on the surface of the refractometer prism to avoid the generation of air bubbles. After the temperature stabilized, the refractive index was read. Each sample was measured 3 times and the average value was taken. The measurement accuracy was ±0.0002.

[0069] Table 1 From Table 1 and Figures 1 to 5 As can be seen from the embodiments of the present invention, liquid silicone oil with high phenyl content can be prepared rapidly and controllably at a lower temperature, and the refractive index of the silicone oil is as high as 1.50~1.59, which enables controllable adjustment of viscosity, phenyl content and vinyl content.

[0070] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A high refractive index silicone oil, characterized in that, This high refractive index silicone oil is obtained by ring-opening copolymerization of a mixture of cyclic siloxanes catalyzed by a phosphorus-nitrogen organic base catalyst. The structural formula of this high refractive index silicone oil is as follows: Where R is at least one of SiMe3 and SiMe2Vi, R1 is at least one of methyl and phenyl, and m, n, o, x are integers from 1 to 10000.

2. The high refractive index silicone oil according to claim 1, characterized in that, The high refractive index silicone oil has a refractive index of 1.50~1.

59.

3. The high refractive index silicone oil according to claim 1, characterized in that, The viscosity of the high refractive index silicone oil is 100~100000 mPa·s.

4. The high refractive index silicone oil according to claim 1, characterized in that, The high refractive index silicone oil has a phenylsiloxane unit content of 40~100 mol% and a vinyl content of 0.4~2.5 mmol / g.

5. The high refractive index silicone oil according to claim 1, characterized in that, The phosphorus-nitrogen organic base catalyst is selected from phosphazene base catalysts; Preferably, the phosphazene base catalyst is selected from... , , , , , , or At least one of them.

6. A method for preparing a high refractive index silicone oil according to any one of claims 1 to 5, characterized in that, The preparation method includes: (1) The cyclic siloxane mixture, the initiator and the capping agent are stirred and mixed to obtain a mixed system; wherein the cyclic siloxane mixture includes alkenyl-containing cyclotetrasiloxane and alkenyl-free cyclotetrasiloxane; (2) Add a phosphorus-nitrogen organic base catalyst to the mixture and carry out a ring-opening copolymerization reaction under heating conditions. After completion, add a terminator to terminate the reaction, separate the catalyst and the low-boiling-point component, and obtain the high refractive index silicone oil.

7. The preparation method according to claim 6, characterized in that, The alkenyl-containing cyclotetrasiloxane is tetramethyltetravinylcyclotetrasiloxane; The alkenyl-free cyclotetrasiloxane is at least one of methylcyclotetrasiloxane or phenylcyclotetrasiloxane; Preferably, the methylcyclotetrasiloxane is octamethylcyclotetrasiloxane, and the phenylcyclotetrasiloxane is at least one of tetramethyltetraphenylcyclotetrasiloxane or octaphenylcyclotetrasiloxane; and / or, More preferably, the cyclic siloxane mixture is composed of tetramethyltetravinylcyclotetrasiloxane, tetramethyltetraphenylcyclotetrasiloxane, and octaphenylcyclotetrasiloxane.

8. The preparation method according to claim 7, characterized in that, In step (1), based on the total amount of the cyclic siloxane mixture, the proportion of tetramethyltetravinylcyclotetrasiloxane is 0~20 mol%, the proportion of methylcyclotetrasiloxane is 0~50 mol%, and the proportion of phenylcyclotetrasiloxane is 30~100 mol.

9. The preparation method according to claim 7, characterized in that, In step (1), the initiator is at least one of water, benzyl alcohol, ethylene glycol, 1,2-propanediol, 2,3-butanediol, terephthalic acid, cyclohexanediol, glycerol, trimethylolpropane, pentaerythritol, trimethylsilanol, dimethylphenylsilanol, methylsilanetriol or hydroxymethyldiphenylsilane. The end-capping agent is at least one of hexamethyldisiloxane or tetramethyldivinyldisiloxane; Preferably, the amount of the initiator added is 1-20 mol% of the total amount of the cyclic siloxane mixture, and the amount of the capping agent added is 5-60 mol% of the total amount of the cyclic siloxane mixture.

10. The preparation method according to claim 7, characterized in that, In step (2), the terminator is at least one of acetic acid, phosphoric acid, hydrochloric acid, sulfuric acid, or carbon dioxide; the amount of the terminator added is preferably 1 to 1.5 times the molar equivalent of the catalyst; based on the total amount of the cyclic siloxane mixture, the amount of the phosphorus-nitrogen organic base catalyst added is 0.005 to 0.02%; and / or, The ring-opening copolymerization reaction is carried out at a temperature of 60~140℃ for 1~4 hours.

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