Preparation method of high-temperature-resistant phenyl silicone resin

Abstract

The invention discloses a preparation method of high-temperature-resistant phenyl silicone resin, and relates to the field of polymer material chemistry, and the preparation method comprises the following steps: mixing diphenyl dihalosilane and an organic solvent according to a mass ratio of 1: (1-10), slowly adding the mixture into a water solvent system containing weak base for hydrolysis reaction, maintaining the alkalinity of the system to instantaneously neutralize the generated acid, and carrying out solid-liquid separation to obtain the high-temperature-resistant phenyl silicone resin. After the reaction, recrystallizing to obtain a diphenyl silanediol intermediate; dissolving the diphenyl silanediol intermediate in low-carbon alcohol or acetone, adding a strong base catalyst, and carrying out cyclization reaction to generate octaphenylcyclotetrasiloxane crystals; and dissolving the octaphenylcyclotetrasiloxane crystal in an organic solvent, adding an adsorbent, stirring, filtering, adding a precipitating agent with the volume 1-4 times that of the filtrate for recrystallization, and centrifuging and drying the precipitated crystal to obtain the octaphenylcyclotetrasiloxane crystal with the purity of 99.9% or above. According to the preparation method of the high-temperature-resistant phenyl silicone resin, the prepared phenyl silicone resin has high purity, excellent heat resistance, good toughness and stable consistency.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of high polymer material chemistry, and particularly to a preparation method of a high-temperature-resistant phenyl silicone resin. BACKGROUND

[0002] Phenyl silicone resin is an important branch of silicone high polymer materials. Due to the introduction of phenyl groups in the molecular structure, they have higher thermal stability, radiation resistance, ablation resistance, and better compatibility with organic polymers and inorganic fillers than ordinary methyl silicone resins. They are widely used in H-grade and C-grade motor and appliance high-temperature-resistant insulating paint and impregnating varnish, high-temperature coating, adhesive and sealant for aerospace vehicles, passivation layer and plastic encapsulant for semiconductor chips, and defoaming agent and lubricant under high-temperature working conditions.

[0003] Chinese patent application No. CN 202211565486.4 discloses a method for preparing phenyl silicone resin without solvent and its application. Dimethyldichlorosilane is added dropwise into methanol, part of phenyltrichlorosilane and deionized water are first added dropwise, the mixture is stirred and reacted, the remaining phenyltrichlorosilane is then added dropwise, the reaction is carried out at a reduced speed and an increased temperature, a drying agent is added for drying, low-boiling substances are removed under reduced pressure and increased temperature, and the obtained phenyl silicone resin is cooled to room temperature. The obtained product has high silicone content, good heat resistance, good water boiling stability and high gloss. Although the traditional toluene solvent is avoided, the excess alcohol methanol is used as a solvent, and a large amount of hydrogen chloride is released during the alcoholysis or hydrolysis of the selected raw material chlorosilane, resulting in too high acidity of the system, too many impurities in the hydrolysis material, poor batch stability of the phenyl silicone resin product, and inability to meet the strict requirements of high-end manufacturing industry on material consistency. In addition, the high acidity of the system requires high-quality equipment and high investment cost.

[0004] Therefore, it is necessary to provide a preparation method of a high-temperature-resistant phenyl silicone resin to solve the above problems. SUMMARY

[0005] (I) Technical problems to be solved The purpose of the present application is to provide a preparation method of a high-temperature-resistant phenyl silicone resin to solve the problems in the background art.

[0006] (II) Technical solutions To achieve the above purpose, the present application is implemented by the following technical solutions: a preparation method of a high-temperature-resistant phenyl silicone resin, comprising the following steps: (1) mixing diphenyldihalosilane and an organic solvent at a mass ratio of 1:1-10, slowly adding them into a weak base-containing aqueous solvent system to perform hydrolysis reaction, maintaining the alkalinity of the system to instantaneously neutralize the generated acid, and obtaining a diphenylsilanediol intermediate through recrystallization after the reaction; (2) The diphenylsilanediol intermediate is dissolved in a low-carbon alcohol or acetone, a strong base catalyst is added to perform a cyclization reaction, and octaphenylcyclotetrasiloxane crystals are generated; (3) The obtained octaphenylcyclotetrasiloxane crystals are dissolved in an organic solvent, an adsorbent is added and stirred, then filtered, 1-4 times the volume of a precipitating agent is added to the filtrate to perform recrystallization, the precipitated crystals are centrifuged and dried to obtain octaphenylcyclotetrasiloxane crystals with a purity of more than 99.9%; (4) The octaphenylcyclotetrasiloxane is mixed with methyltrimethoxysilane, and 1-5% of γ-methacryloyloxypropyltrimethoxysilane monomer is introduced relative to the total mass of silane, wherein the molar ratio of phenyl to methyl (Ph / Me) of octaphenylcyclotetrasiloxane to methyltrimethoxysilane is 1:1-3; (5) The mixed raw materials are subjected to a polymerization reaction at 80-105°C for 8-12 hours under the action of a strong base catalyst to obtain a prepolymer; (6) The catalyst and small molecule by-products of the prepolymer are removed, and then solidification is performed to obtain a high-temperature-resistant phenyl silicone resin.

[0007] Preferably, the halogen in the diphenyldihalosilane is chlorine or bromine.

[0008] Preferably, in step (1), the organic solvent is selected from one or more of xylene, cyclohexane, benzene, acetone diethyl ether, tetrahydrofuran, and carbon tetrachloride; and the weak base is selected from one or more of ammonia, sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate, methylamine, and ethylamine.

[0009] Preferably, the hydrolysis reaction temperature is maintained at 0-5°C, and the contact is added dropwise while stirring for 0.5-1 hours.

[0010] Preferably, in step (2), the strong base catalyst is selected from one or more of alkali metal hydroxides and quaternary ammonium bases.

[0011] Preferably, the cyclization reaction temperature is 60-80°C, and the reaction time is 4-8 hours.

[0012] Preferably, in step (3), the organic solvent is selected from one or more of benzene, toluene, xylene, acetone, diethyl ether, tetrahydrofuran, ethyl acetate, and butyl acetate; the adsorbent is one or more of diatomite, molecular sieves, and adsorption resins; and the precipitating agent is a C1-C4 alcohol, or a C5-C10 straight-chain or branched-chain alkane.

[0013] Preferably, the molar ratio of Ph / Me of octaphenylcyclotetrasiloxane to methyltrimethoxysilane is 1:1.5-2.5.

[0014] Preferably, in step (5), the strong base catalyst is a quaternary ammonium base.

[0015] (III) Beneficial Effects Compared with the prior art, the present invention provides a method for preparing high-temperature resistant phenyl silicone resin, which has the following beneficial effects: 1. The preparation method of this high-temperature resistant phenyl silicone resin employs a weak-alkali hydrolysis process, avoiding the acidic system problems caused by chlorosilane raw materials and effectively reducing the generation of impurities such as oligomeric siloxanes in the resin. Using low-carbon alcohols as solvents not only facilitates the precipitation of octaphenylcyclotetrasiloxane crystals and promotes filtration and separation, but also ensures easy solvent recovery and improved environmental friendliness. Under the same cost conditions, the purity of octaphenylcyclotetrasiloxane monomer can reach over 99.9%, laying the foundation for the subsequent preparation of high-performance resins.

[0016] 2. The preparation method of this high-temperature resistant phenyl silicone resin optimizes and determines the optimal Ph / Me molar ratio, precisely balancing the effects of phenyl and methyl groups. This ensures extremely high heat resistance while avoiding the resin's brittleness caused by excessive phenyl content. Simultaneously, the introduction of γ-methacryloyloxypropyltrimethoxysilane monomer and precise control of crosslinking density form a robust yet resilient three-dimensional network structure, further enhancing the resin's temperature resistance and anti-brittleness. The optimized phenyl silicone resin maintains stable performance in an air environment at 400℃ for extended periods and can withstand temperatures above 450℃ for short periods, making it suitable for high-temperature operating conditions in high-end applications.

[0017] 3. The preparation method of this high-temperature resistant phenyl silicone resin uses a highly efficient and low-residue catalyst, which makes the molecular weight distribution of the resin narrower and the structure more regular, reducing thermal weaknesses; at the same time, the raw material octaphenylcyclotetrasiloxane has high purity and few impurities, which effectively reduces batch-to-batch differences, and the product performance is highly predictable and reliable, which can meet the stringent requirements of high-end manufacturing industries for material consistency.

[0018] 4. The preparation method of this high-temperature resistant phenyl silicone resin uses a weak alkaline hydrolysis process to avoid corrosion of equipment by the acidic system, reduce the requirements for equipment materials, and significantly reduce equipment investment costs. The characteristics of easy solvent recovery and easy separation of impurities further reduce material loss and environmental treatment costs in the production process, and improve production economy. Detailed Implementation

[0019] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0020] Example 1 A method for preparing a high-temperature resistant phenyl silicone resin includes the following steps: (1) Preparation of diphenylsilane intermediate: 100g of diphenyldichlorosilane and 500g of xylene were mixed evenly and slowly added dropwise to a 1L deionized water system containing ammonia. The system temperature was maintained at 2℃, and ammonia was added dropwise to maintain the alkalinity of the system. After the addition was completed, the mixture was stirred for 0.8 hours. After the reaction was completed, recrystallization was performed to obtain 78g of diphenylsilane intermediate. (2) Preparation of octaphenylcyclotetrasiloxane crystals: 78g of diphenylsilanediol intermediate was dissolved in 300g of methanol, 3g of sodium hydroxide was added, and the mixture was heated to 70℃ for cyclization reaction for 6 hours. After the reaction was completed, the mixture was cooled to room temperature and filtered to obtain 63g of crude octaphenylcyclotetrasiloxane. (3) Purification of octaphenylcyclotetrasiloxane: 63g of crude octaphenylcyclotetrasiloxane was dissolved in 200g of benzene, 10g of diatomaceous earth was added, and the mixture was stirred at room temperature for 2 hours before filtration. 400g of n-hexane was added to the filtrate, and the mixture was allowed to stand and cool to crystallize. After centrifugation, the mixture was dried under vacuum at 85℃ for 4 hours to obtain 60g of purified octaphenylcyclotetrasiloxane with a purity of 99.95%. (4) Raw material mixing: Weigh 60g of purified octaphenylcyclotetrasiloxane and 143g of methyltrimethoxysilane, add 5.8g of γ-methacryloyloxypropyltrimethoxysilane, and mix evenly to obtain mixed raw materials; (5) Polymerization reaction: Add 1.5g of tetramethylammonium hydroxide to the mixed raw materials, heat to 90℃, and react at a constant temperature for 10 hours to obtain phenyl silicone resin prepolymer; (6) Removal of impurities and curing: The prepolymer is heated to 120°C and the small molecule by-products and catalyst are removed under reduced pressure. The treated prepolymer is placed in an oven and cured at 150°C for 2 hours, and then heated to 200°C for 1 hour to obtain the high-temperature resistant phenyl silicone resin product.

[0021] Example 2 A method for preparing a high-temperature resistant phenyl silicone resin includes the following steps: The difference from Example 1 is as follows: (1) Preparation of diphenylsilanediol intermediate: the organic solvent is n-hexane, the mass ratio of diphenyldichlorosilane to n-hexane is 1:10, the weak base is sodium carbonate, the hydrolysis temperature is 0℃, and the stirring time is 1 hour; (2) Preparation of octaphenylcyclotetrasiloxane crystals: Diphenylsilanediol intermediate was dissolved in acetone, tetramethylammonium hydroxide was used as a strong base catalyst, the cyclization reaction temperature was 80℃, and the reaction time was 4 hours; (3) Purification of octaphenylcyclotetrasiloxane: The organic solvent was tetrahydrofuran, and the adsorbent was adsorption resin. The precipitant was butanol. After crystallization and centrifugation, the mixture was vacuum dried at 90°C for 4 hours to obtain octaphenylcyclotetrasiloxane with a purity of 99.94%. (4) Raw material mixing: The Ph / Me molar ratio of octaphenylcyclotetrasiloxane to methyltrimethoxysilane is 1:1, and the amount of γ-methacryloyloxypropyltrimethoxysilane added is 5% of the total silane mass; (5) Polymerization reaction: The polymerization reaction temperature is 105℃ and the reaction time is 8 hours to obtain phenyl silicone resin prepolymer.

[0022] Example 3 A method for preparing a high-temperature resistant phenyl silicone resin includes the following steps: The difference from Example 1 is as follows: (1) Preparation of diphenylsilanediol intermediate: the organic solvent is tetrahydrofuran, the mass ratio of diphenyldichlorosilane to n-hexane is 1:1, the weak base is ethylamine, the hydrolysis temperature is 5℃, and the stirring time is 0.5 hours; (2) Preparation of octaphenylcyclotetrasiloxane crystals: Diphenylsilanediol intermediate was dissolved in propanol, potassium hydroxide was used as the strong base catalyst, the cyclization reaction temperature was 60℃, and the reaction time was 8 hours. (3) Purification of octaphenylcyclotetrasiloxane: The organic solvent was ethyl acetate, and the adsorbent was molecular sieve. The precipitant was methanol. After crystallization and centrifugation, the octaphenylcyclotetrasiloxane was vacuum dried at 80°C for 4 hours to obtain octaphenylcyclotetrasiloxane with a purity of 99.93%. (4) Raw material mixing: The Ph / Me molar ratio of octaphenylcyclotetrasiloxane to methyltrimethoxysilane is 1:3, and the amount of γ-methacryloyloxypropyltrimethoxysilane added is 1% of the total silane mass; (5) Polymerization reaction: The strong alkaline catalyst is tetraethylammonium hydroxide, the polymerization reaction temperature is 80℃, the reaction time is 12 hours, and phenyl silicone resin prepolymer is obtained.

[0023] Comparative Example 1 The only difference from Example 1 is that the Ph / Me molar ratio of octaphenylcyclotetrasiloxane to methyltrimethoxysilane in step (4) is 1:4. All other raw materials and process parameters are the same as in Example 1, and finally, comparative sample 1 is obtained.

[0024] Comparative Example 2 The only difference from Example 1 is that the Ph / Me molar ratio of octaphenylcyclotetrasiloxane to methyltrimethoxysilane in step (4) is 1:0.8, which exceeds the range of 1:1-3 in claim 1. The other raw materials and process parameters are the same as in Example 1, and finally, comparative sample 2 is obtained.

[0025] Comparative Example 3 The only difference from Example 1 is that γ-methacryloxypropyltrimethoxysilane was not added in step (4), while the other raw materials and process parameters were the same as in Example 1, and finally, comparative sample 3 was obtained.

[0026] To verify the performance advantages of the high-temperature resistant phenyl silicone resin prepared in this invention, key performance indicators of the finished products of Examples 1-3 and Comparative Examples 1-3 were tested. The test items included the purity of octaphenylcyclotetrasiloxane after purification, the performance retention rate under air conditions at 400℃, the short-term temperature resistance peak, tensile strength, elongation at break, and batch-to-batch performance deviation. The test results are shown in the table below:

[0027] As can be seen from the above test values, the high-temperature resistant phenyl silicone resins prepared in Examples 1-3 of this invention exhibit significant advantages in all core performance indicators and are comprehensively superior to Comparative Examples 1-3: Regarding the purity of raw materials, the purity of octaphenylcyclotetrasiloxane in Examples 1-3 was consistently above 99.9%, confirming that the weak alkaline hydrolysis and solvent crystallization purification process of this invention can efficiently prepare high-purity raw materials, laying the foundation for high-performance resins. Moreover, the purity level was basically the same as that of the comparative example, eliminating the dominant influence of raw material purity on subsequent performance differences. Regarding the balance between heat resistance and toughness, Examples 1-3 all exhibited a performance retention rate exceeding 97% after 100 hours at 400℃, with short-term peak temperatures reaching 460-470℃. Simultaneously, tensile strength remained at 8.3-8.8 MPa and elongation at break reached 11.8-12.6%, achieving an optimal match between heat resistance and toughness. In contrast, Comparative Example 1, with a Ph / Me molar ratio of 1:4 (excess phenyl), showed a slight improvement in heat resistance, but its tensile strength was only 4.5 MPa and elongation at break was 3.8%, making the resin too brittle and prone to cracking, failing to meet processing and usage requirements. Comparative Example 2, with a Ph / Me molar ratio of 1:0.8 (excess methyl), experienced a sharp drop in long-term performance retention rate at 400℃ to 68.3%, with a short-term peak temperature of only 410℃, indicating significantly insufficient heat resistance and making it unsuitable for high-temperature conditions. Regarding the effect of crosslinking density control, Comparative Example 3, due to the absence of γ-methacryloxypropyltrimethoxysilane, had insufficient crosslinking density, resulting in a performance retention rate of only 75.6% at 400℃, a tensile strength of 5.3 MPa, an elongation at break of 5.2%, and a significant decline in toughness and temperature stability. In contrast, Examples 1-3, due to the addition of 1-5 wt% of crosslinking monomers, effectively avoided this defect. Regarding product stability, the coefficient of variation of the performance retention rate at 400℃ in Examples 1-3 is only 1.1-1.3%, with minimal batch-to-batch differences and high product consistency, meeting the stringent requirements of high-end manufacturing.

[0028] In summary, this preparation method yields a high-temperature resistant phenyl silicone resin that possesses high purity, excellent heat resistance, good toughness, and stable consistency, effectively overcoming the shortcomings of existing technologies and demonstrating significant technical advantages and application value.

[0029] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a high-temperature resistant phenyl silicone resin, characterized in that, Includes the following steps: (1) Mix diphenyl dihalosilane with an organic solvent at a mass ratio of 1:1-10, and slowly add it to an aqueous solvent system containing a weak base to carry out a hydrolysis reaction. Maintain the alkalinity of the system to neutralize the generated acid instantaneously. After the reaction, recrystallize to obtain a diphenyl silanediol intermediate. (2) Dissolve the diphenylsilanediol intermediate in a low-carbon alcohol or acetone, add a strong base catalyst to carry out a cyclization reaction to generate octaphenylcyclotetrasiloxane crystals; (3) Dissolve the obtained octaphenylcyclotetrasiloxane crystals in an organic solvent, add an adsorbent, stir and filter. Add 1-4 times the volume of precipitant to the filtrate for recrystallization. Centrifuge and dry the precipitated crystals to obtain octaphenylcyclotetrasiloxane crystals with a purity of 99.9% or higher. (4) Mix the octaphenylcyclotetrasiloxane with methyltrimethoxysilane and introduce 1-5% of γ-methacryloyloxypropyltrimethoxysilane monomer relative to the total silane mass, wherein the molar ratio of phenyl to methyl in octaphenylcyclotetrasiloxane to methyltrimethoxysilane is 1:1-3. (5) The mixed raw materials are subjected to polymerization reaction at 80-105℃ for 8-12 hours under the action of a strong alkaline catalyst to obtain the prepolymer; (6) Remove the catalyst and small molecule byproducts from the prepolymer, and then cure it to obtain high temperature resistant phenyl silicone resin.

2. The method for preparing a high-temperature resistant phenyl silicone resin according to claim 1, characterized in that: The halogen in the diphenyl dihalosilane is chlorine or bromine.

3. The method for preparing a high-temperature resistant phenyl silicone resin according to claim 1, characterized in that: In step (1), the organic solvent is selected from one or more of xylene, cyclohexane, benzene, acetone ether, tetrahydrofuran, and carbon tetrachloride; the weak base is selected from one or more of ammonia, sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate, methylamine, and ethylamine.

4. The method for preparing a high-temperature resistant phenyl silicone resin according to claim 1, characterized in that: The hydrolysis reaction temperature is maintained at 0-5℃, and stirring is continued for 0.5-1 hour after the droplet is added.

5. The method for preparing a high-temperature resistant phenyl silicone resin according to claim 1, characterized in that: In step (2), the strong base catalyst is selected from one or more of alkali metal hydroxides and quaternary ammonium bases.

6. The method for preparing a high-temperature resistant phenyl silicone resin according to claim 1, characterized in that: The cyclization reaction temperature is 60-80℃, and the reaction time is 4-8 hours.

7. The method for preparing a high-temperature resistant phenyl silicone resin according to claim 1, characterized in that: In step (3), the organic solvent is selected from one or more of benzene, toluene, xylene, acetone, diethyl ether, tetrahydrofuran, ethyl acetate and butyl acetate; the adsorbent is one or more of diatomaceous earth, molecular sieve and adsorption resin; the precipitant is a C1-C4 alcohol, or a C5-C10 straight-chain alkane or branched-chain alkane.

8. The method for preparing a high-temperature resistant phenyl silicone resin according to claim 1, characterized in that: The Ph / Me molar ratio of the octaphenylcyclotetrasiloxane to methyltrimethoxysilane is 1:1.5-2.

5.

9. The method for preparing a high-temperature resistant phenyl silicone resin according to claim 1, characterized in that: In step (5), the strong alkaline catalyst is a quaternary ammonium base.

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