Preparation method of low volatile methyl phenyl silicone oil

Abstract

The application provides a preparation method of low volatile methyl phenyl silicone oil, and the synthesis raw material is easy to obtain and low in cost. By matching a hydrolyzate and an alkaline catalyst, a chain extender and an end-capping agent are separately added, methyl phenyl silicone oil with different viscosity and refractive index parameters can be designed, and by matching the alkaline catalyst and a heat-resistant agent, impurity groups in the silicone oil can be removed, the integrity of the silicone oil chain in the preparation process is ensured, oxidation and deterioration of the silicone oil chain caused by high temperature are effectively prevented, and finally, the high-quality methyl phenyl silicone oil product with low volatile content is obtained.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of silicone oil preparation, and particularly relates to a preparation method of low-volatility methyl phenyl silicone oil. BACKGROUND

[0002] Phenyl silicone oil is a linear organopolysiloxane with excellent heat resistance, cold resistance, radiation resistance and light transmission performance, and has a phenyl group in the side chain. Compared with methyl silicone oil, phenyl silicone oil has a wider application in personal care, industrial heat conduction, aerospace, nuclear power and other fields. With the progress of science and technology, the quality requirements for phenyl silicone oil are also getting higher and higher, including stable and controllable basic parameters, narrow molecular weight distribution, few impurity groups and low volatile matter.

[0003] At present, the commonly used methods for synthesizing phenyl silicone oil mainly include the following two methods:

[0004] 1) Ring-opening equilibrium polymerization method: phenyl mixed ring, methyl mixed ring or chain is used as a chain extender, and hexamethyl disiloxane or methyl polysiloxane short chain is used as an end-capping agent to perform ring-opening equilibrium polymerization reaction under the action of a catalyst. For example, Chinese invention patent CN115947944A discloses a preparation method of high-phenyl-content methyl phenyl silicone oil. Octaphenylcyclotetrasiloxane is used as a phenyl chain extender, KOH is used as a catalyst to dissolve the phenyl ring at high temperature, and then a methyl polysiloxane with a certain chain number is added as a methyl chain extender and an end-capping agent to perform equilibrium reaction. After adsorption, filtration and high-temperature low-removal, yellow transparent methyl phenyl silicone oil is obtained. This is because the high-temperature reaction condition will cause the change of the silicone oil chain. Even after adsorption and filtration with activated carbon, the color of the product silicone oil is still yellow.

[0005] 2) Hydrolyzate condensation method: through the condensation reaction of phenyl hydrolyzate, and then performing ring-opening equilibrium reaction with methyl mixed ring or chain and hexamethyl disiloxane. For example, Chinese invention patent CN109776801A discloses a preparation method of phenyl silicone oil. Methyl and phenyl co-hydrolyzate is used as a chain extender, hexamethyl disiloxane is used as an end-capping agent, and trifluoromethanesulfonic acid is used as a catalyst to perform equilibrium reaction. After the equilibrium is completed, a silazane substance is added to remove hydroxyl groups, and methyl phenyl silicone oil is obtained after high-temperature low-removal. However, in the high-temperature equilibrium reaction, trifluoromethanesulfonic acid is easy to react with the benzene ring to generate impurity groups. After the removal of hydroxyl groups by the silazane substance, the silicone oil chain number cannot be restored to the normal silicone oil chain number corresponding to the methyl end-capping amount, and subsequent high-temperature low-removal may also cause the oxidation and deterioration of the phenyl silicone oil chain. SUMMARY

[0006] In order to solve the problems of the above-mentioned preparation method of methyl phenyl silicone oil in the prior art, the application provides a preparation method of low-volatility methyl phenyl silicone oil with stable and controllable parameters, narrow molecular weight distribution and few impurity groups.

[0007] The application is implemented by the following technical solutions.

[0008] A preparation method of low volatile methyl phenyl silicone oil, comprising the following steps:

[0009] S1, condensation reaction: adding methyl and phenyl polysiloxane mixed hydrolysate into a reaction container, adding an alkaline catalyst, so that the alkaline catalyst and the methyl and phenyl polysiloxane mixed hydrolysate are subjected to condensation reaction to obtain a methyl phenyl condensate;

[0010] S2, equilibrium reaction: adding methyl polysiloxane mixed ring body and hexamethyl disiloxane into the reaction container in step S1, so that the two and the methyl phenyl condensate are subjected to first stage reaction, adding an alkaline catalyst, stirring, and performing second stage reaction under negative pressure, and performing third stage reaction by heating, and obtaining a medium breaking product by breaking medium at normal pressure;

[0011] S3, adsorption: transferring the medium breaking product in step S2 to an adsorption container, adding activated carbon for adsorption, stirring, and obtaining a crude silicone oil after filtration;

[0012] S4, low volatile removal: transferring the crude silicone oil in step S3 to a low volatile removal container, adding a heat-resistant agent, so that the heat-resistant agent and the crude silicone oil are subjected to low volatile removal to obtain a low volatile removal product;

[0013] S5, filtration: cooling the low volatile removal product in step S4 to room temperature, adding activated carbon for adsorption, stirring, and obtaining methyl phenyl silicone oil after filtration.

[0014] In the step S1, the structure of the methyl and phenyl polysiloxane mixed hydrolysate is as follows:

[0015]

[0016] In the formula, x:y=1:(1-2); x+y=(2-20); and the residual amount of methoxy is about 1%wt.

[0017] The application is based on the following reaction principle:

[0018]

[0019] Firstly, the mixed hydrolysate of methyl and phenyl polysiloxane is used as a chain extender, and through the cooperation of an alkaline catalyst, the mixed hydrolysate of methyl and phenyl polysiloxane can be promoted to perform a condensation reaction to generate a methyl phenyl condensate, and the subsequent equilibrium reaction of the methyl phenyl condensate with a methyl chain extender and an end-capping agent can also be promoted. Secondly, by separately adding the chain extender and the end-capping agent to perform an equilibrium reaction with the methyl phenyl condensate, a methyl phenyl silicone oil with different viscosity and refractive index parameters can be designed. Specifically, the viscosity is 10-5000 cs, and the refractive index is 1.4200-1.5200.

[0020] Then, the alkaline catalyst is added after the equilibrium reaction to promote the hydrolysis and condensation of residual methoxy groups, further remove the methoxy and hydroxy groups, and further improve the stability of the silicone oil. It can also strengthen the balance recovery speed of the reaction system after the balance is destroyed, and promote the uniform arrangement of the methyl units and phenyl units in the molecular chain of the methyl phenyl silicone oil, thereby ensuring the integrity of the silicone oil chain. Thirdly, by adding a heat-resistant agent, the methyl phenyl silicone oil chain is protected from oxidation during high-temperature low removal, to ensure the integrity of the silicone oil chain. The heat-resistant agent can be removed by activated carbon adsorption filtration, which is beneficial to obtain a product with low volatile matter and does not affect the end application of the phenyl silicone oil.

[0021] Preferably, the condensation reaction conditions in step S1 are as follows: vacuum degree: -0.05 to -0.1 MPa, reaction temperature: 80-120℃, stirring speed: 100-400 r / min, and reaction time: 1-5 h. After the condensation reaction, the product can be restored to normal pressure by nitrogen pressure relief to avoid oxidation of the product when it is restored to normal pressure, thereby ensuring the purity and quality of the product.

[0022] More preferably, the vacuum degree is -0.08 MPa, the reaction temperature is 100℃, the stirring speed is 200 r / min, and the reaction time is 2 h.

[0023] Preferably, the first stage reaction conditions in step S2 are as follows: reaction temperature: 80-120℃, stirring speed: 100-400 r / min, and reaction time: 1-5 h. More preferably, the reaction temperature is 90℃, the stirring speed is 200 r / min, and the reaction time is 2 h.

[0024] Preferably, the stirring time after adding the alkaline catalyst in step S2 is 0-0.5 h. More preferably, the stirring time is 0.2 h.

[0025] Preferably, the second stage reaction condition in step S2 is vacuum degree: -0.08 to -0.1 MPa, stirring speed: 100 to 400 r / min, and reaction time: 1 to 6 h; and the second stage reaction process is protected by nitrogen pressure relief. More preferably, the vacuum degree is -0.09 MPa, the stirring speed is 200 r / min, and the reaction time is 2 h.

[0026] Preferably, the third stage reaction condition in step S2 is reaction temperature: 100 to 120℃, and reaction time: 1 to 8 h. More preferably, the reaction temperature is 110℃, and the reaction time is 5 h.

[0027] Preferably, the atmospheric medium breaking condition in step S2 is reaction temperature: 150℃, and stirring time: 1 h.

[0028] Preferably, the basic catalyst in steps S1 and S2 is one of NaOH, KOH, LiOH, and (CH3)4NOH. In step S1, the basic catalyst is used to promote the condensation reaction of the methyl and phenyl polysiloxane mixed hydrolyzate to generate a methyl phenyl condensate, and to promote the subsequent equilibrium reaction of the methyl phenyl condensate with the methyl chain extender and the end-capping agent. In step S2, the basic catalyst is added after the equilibrium reaction to promote the hydrolysis and condensation of residual methoxy groups, to further remove the methoxy and hydroxy groups, to improve the stability of the silicone oil, to strengthen the balance recovery speed of the reaction system after the balance is broken, and to promote the uniform arrangement of the methyl units and the phenyl units in the molecular chain of the methyl phenyl silicone oil, thereby ensuring the integrity of the silicone oil chain.

[0029] More preferably, the basic catalyst is (CH3)4NOH. Tetramethylammonium hydroxide has high reactivity, and as the reaction temperature increases, tetramethylammonium hydroxide can be decomposed into a gas without being left in the product, thereby improving the purity and quality of the product.

[0030] Preferably, the amount of the basic catalyst in step S1 is 500 to 1000 ppm. More preferably, the amount of the basic catalyst is 800 ppm.

[0031] Preferably, the amount of the basic catalyst in step S2 is 500 to 2000 ppm. More preferably, the amount of the basic catalyst is 1000 ppm.

[0032] Preferably, the amount of the activated carbon in steps S3 and S4 is 0.1 to 3% of the weight of the methyl phenyl silicone oil, and the stirring time is 1 to 3 h. More preferably, the amount of the activated carbon is 1% of the weight of the methyl phenyl silicone oil, and the stirring time is 2 h.

[0033] Preferably, the heat-resistant agent in step S4 is one of CeO2, Fe2O3, and SnO2, and the amount of the heat-resistant agent is 0.5-2% by weight of the methylphenyl silicone oil. The heat-resistant agent can protect the methylphenyl silicone oil chain from oxidation at high temperature, effectively inhibit the oxidation and breaking of the silicone oil chain, and ensure the integrity of the silicone oil chain. The heat-resistant agent can be removed by activated carbon adsorption and filtration without affecting the end application of the phenyl silicone oil. In addition, in order to increase the compatibility of the heat-resistant agent and the silicone oil, the heat-resistant agent is surface treated with hexamethyldisilazane, and the heat-resistant agent is subjected to drying treatment before use.

[0034] More preferably, the heat-resistant agent is CeO2. The CeO2 is in irregular shape and has a particle size of 4 um. Ceria has excellent heat resistance and can maintain chemical stability at high temperature without being easily decomposed or volatilized. In addition, ceria has variable valence and can preferentially react with free radicals, thereby preventing the deterioration of the silicone oil chain.

[0035] More preferably, the amount of the heat-resistant agent is 1% by weight of the methylphenyl silicone oil.

[0036] Preferably, the de-low temperature conditions in step S4 are vacuum degree: -0.1 MPa, temperature: 250-320℃, stirring speed: 100-400 r / min, and de-low temperature time: 1-6 h. More preferably, the temperature is 300℃, the stirring speed is 300 r / min, and the de-low temperature time is 3 h.

[0037] The beneficial effects of the present application are as follows:

[0038] The application provides a preparation method of low volatile methyl phenyl silicone oil. First, methyl and phenyl polysiloxane mixed hydrolysate is used as a chain extender, and through cooperation with an alkaline catalyst, the methyl and phenyl polysiloxane mixed hydrolysate can be promoted to perform condensation reaction to generate a methyl phenyl condensate, and the methyl phenyl condensate can be promoted to perform subsequent equilibrium reaction with a methyl chain extender and an end-capping agent. Second, methyl polysiloxane mixed ring bodies are added as the methyl chain extender, and hexamethyl disiloxane is added as the end-capping agent, and through separate input of the chain extender and the end-capping agent, the methyl phenyl condensate can be promoted to perform equilibrium reaction, so that methyl phenyl silicone oil with different viscosity and refractive index parameters can be designed. Then, after the equilibrium reaction, the alkaline catalyst is supplemented, so that the residual methoxy group can be promoted to perform hydrolysis and condensation, and the methoxy group and the hydroxy group can be further removed, so that the stability of the silicone oil is improved, the balance recovery speed of the reaction system after the balance is destroyed can be improved, the uniform arrangement of the methyl unit and the phenyl unit in the molecular chain of the methyl phenyl silicone oil is promoted, and the integrity of the silicone oil chain is ensured. Third, a heat-resistant agent is added to protect the methyl phenyl silicone oil chain from being oxidized during high-temperature low-portion removal, so as to ensure the integrity of the silicone oil chain, and the heat-resistant agent can be removed through activated carbon adsorption filtration, which is beneficial to obtaining a product with low volatile matter and does not affect the application of the phenyl silicone oil at the back end.

[0039] The preparation method of the low volatile methyl phenyl silicone oil has the advantages that the synthesis raw materials are easy to obtain and the cost is low, the mixed hydrolysate and the alkaline catalyst are cooperated, the chain extender and the end-capping agent are separately input, the methyl phenyl silicone oil with different viscosity and refractive index parameters can be designed and obtained, the alkaline catalyst and the heat-resistant agent are cooperated, the impurity groups in the silicone oil can be removed, and the integrity of the silicone oil chain in the preparation process is ensured, so that the high-quality methyl phenyl silicone oil is obtained.

CONCRETE EMBODIMENT

[0040] The specific technical solutions of the application will be described below in combination with examples 1-4.

[0041] Example 1

[0042] A preparation method of low volatile methyl phenyl silicone oil comprises the following steps:

[0043] S1, condensation reaction: 300 g of methyl and phenyl polysiloxane mixed hydrolysate is added to a reaction container, 0.24 g of (CH3)4NOH is added, and the alkaline catalyst and the methyl and phenyl polysiloxane mixed hydrolysate are subjected to condensation reaction at 200 r / min under-0.08 MPa and 100 DEG C for 2 h to obtain a methyl phenyl condensate, and the normal pressure is restored through nitrogen pressure relief;

[0044] S2, equilibrium reaction: 30 g of methyl polysiloxane mixed ring body and 5 g of hexamethyldisiloxane were added to the reaction vessel described in step S1, and the two were condensed with the methylphenyl condensate at 90°C at 300 r / min for the first stage reaction for 2 h, 0.34 g of (CH3)4NOH was added, stirred for 0.2 h, the reaction temperature (90°C) was maintained, and the second stage reaction was carried out at 200 r / min under -0.09 MPa for 2 h, and then the temperature was raised to 110°C, the third stage reaction was carried out for 5 h, the temperature was raised to 150°C, and stirring was carried out for 1 h to obtain a broken medium product;

[0045] S3, adsorption: the broken medium product described in step S2 was transferred to an adsorption vessel, 1% activated carbon was added for adsorption, and stirring was carried out for 2 h to obtain a crude silicone oil after filtration;

[0046] S4, low removal: the crude silicone oil described in step S3 was transferred to a low removal vessel, 1% CeO2 was added, and the heat-resistant agent was removed from the crude silicone oil at 300 r / min under -0.1 MPa and 300°C for 3 h to obtain a low removal product;

[0047] S5, filtration: the low removal product described in step S4 was cooled to room temperature, 1% activated carbon was added for adsorption, and stirring was carried out for 2 h to obtain 262 g of methylphenyl silicone oil after filtration.

[0048] Example 2

[0049] A method for preparing a low volatile methylphenyl silicone oil, comprising the following steps:

[0050] S1, condensation reaction: 300 g of methyl and phenyl polysiloxane mixed hydrolysate was added to a reaction vessel, 0.24 g of (CH3)4NOH was added, and the alkaline catalyst was condensed with the methyl and phenyl polysiloxane mixed hydrolysate at 200 r / min under -0.08 MPa and 100°C for 2 h to obtain a methylphenyl condensate, and then the pressure was restored to normal pressure by nitrogen pressure relief;

[0051] S2, equilibrium reaction: 30 g of methyl polysiloxane mixed ring body and 5 g of hexamethyldisiloxane were added to the reaction vessel described in step S1, and the two were condensed with the methylphenyl condensate at 90°C at 300 r / min for the first stage reaction for 2 h, 0.50 g of (CH3)4NOH was added, stirred for 0.2 h, the reaction temperature (90°C) was maintained, and the second stage reaction was carried out at 200 r / min under -0.09 MPa for 2 h, and then the temperature was raised to 110°C, the third stage reaction was carried out for 5 h, the temperature was raised to 150°C, and stirring was carried out for 1 h to obtain a broken medium product;

[0052] S3, adsorption: the product of step S2 is transferred to the adsorption container, 1% activated carbon is added for adsorption, stirring for 2h, and then filtered to obtain a crude silicone oil;

[0053] S4, low removal: the crude silicone oil of step S3 is transferred to the low removal container, 1% CeO2 is added, and the heat-resistant agent and the crude silicone oil are removed at 300r / min under -0.1MPa and 300℃ for 3h to obtain a low removal product;

[0054] S5, filtration: the low removal product of step S4 is cooled to room temperature, 1% activated carbon is added for adsorption, stirring for 2h, and then filtered to obtain 258g of methyl phenyl silicone oil.

[0055] Example 3

[0056] A method for preparing a low volatile methyl phenyl silicone oil, comprising the following steps:

[0057] S1, condensation reaction: 300g of methyl and phenyl polysiloxane mixed hydrolysate is added to a reaction container, 0.24g of (CH3)4NOH is added, and the alkaline catalyst and the methyl and phenyl polysiloxane mixed hydrolysate are condensed at 200r / min under -0.08MPa and 100℃ for 2h to obtain a methyl phenyl condensate, and the pressure is restored to normal pressure by nitrogen pressure relief;

[0058] S2, equilibrium reaction: 30g of methyl polysiloxane mixed ring and 5g of hexamethyl disiloxane are added to the reaction container of step S1, and the two and the methyl phenyl condensate are reacted at 300r / min under 90℃ for 2h in the first stage, 0.34g of (CH3)4NOH is added, stirring for 0.2h, maintaining the reaction temperature (90℃), and then reacting at 200r / min under -0.09MPa for 2h in the second stage, and then the temperature is raised to 110℃ by nitrogen pressure relief and protection, and the third stage reaction is carried out for 5h, and then the temperature is raised to 150℃ and stirred for 1h to obtain a breaking medium product;

[0059] S3, adsorption: the product of step S2 is transferred to the adsorption container, 1% activated carbon is added for adsorption, stirring for 2h, and then filtered to obtain a crude silicone oil;

[0060] S4, low removal: the crude silicone oil of step S3 is transferred to the low removal container, 1% SnO2 is added, and the heat-resistant agent and the crude silicone oil are removed at 300r / min under -0.1MPa and 300℃ for 3h to obtain a low removal product;

[0061] S5, filtration: the low removal product of step S4 is cooled to room temperature, 1% activated carbon is added for adsorption, stirring for 2h, and then filtered to obtain 265g of methyl phenyl silicone oil.

[0062] Example 4

[0063] A method for preparing a low volatile methyl phenyl silicone oil, comprising the following steps:

[0064] S1, condensation reaction: 300 g of methyl and phenyl polysiloxane mixed hydrolysate is added to a reaction container, 0.24 g of (CH3)4NOH is added, and the basic catalyst and the methyl and phenyl polysiloxane mixed hydrolysate are subjected to a condensation reaction at 200 r / min under -0.08 MPa and 100°C for 2 h to obtain a methyl phenyl condensate, and the pressure is restored to normal pressure by nitrogen pressure relief;

[0065] S2, equilibrium reaction: 30 g of methyl polysiloxane mixed ring body and 5 g of hexamethyl disiloxane are added to the reaction container of step S1, and the two are subjected to a first stage reaction with the methyl phenyl condensate at 300 r / min under 90°C for 2 h, 0.34 g of (CH3)4NOH is added, stirred for 0.2 h, the reaction temperature (90°C) is maintained, and a second stage reaction is carried out at 200 r / min under -0.09 MPa for 2 h, and then the temperature is raised to 110°C by nitrogen pressure relief and protection, and a third stage reaction is carried out for 5 h, and then the temperature is raised to 150°C and stirred for 1 h to obtain a broken medium product;

[0066] S3, adsorption: the broken medium product of step S2 is transferred to an adsorption container, 1% activated carbon is added for adsorption, stirred for 2 h, and then filtered to obtain a crude silicone oil;

[0067] S4, low boiling point removal: the crude silicone oil of step S3 is transferred to a low boiling point removal container, 1% CeO2 is added, and the heat resistant agent and the crude silicone oil are subjected to low boiling point removal at 300 r / min under -0.1 MPa and 300°C for 5 h to obtain a low boiling point removal product;

[0068] S5, filtration: the low boiling point removal product of step S4 is cooled to room temperature, 1% activated carbon is added for adsorption, stirred for 2 h, and then filtered to obtain 261 g of methyl phenyl silicone oil.

[0069] Comparative Example 1

[0070] A method for preparing a low volatile methyl phenyl silicone oil, comprising the following steps:

[0071] S1, condensation reaction: 300 g of methyl and phenyl polysiloxane mixed hydrolysate is added to a reaction container, 0.24 g of (CH3)4NOH is added, and the basic catalyst and the methyl and phenyl polysiloxane mixed hydrolysate are subjected to a condensation reaction at 200 r / min under -0.08 MPa and 100°C for 2 h to obtain a methyl phenyl condensate, and the pressure is restored to normal pressure by nitrogen pressure relief;

[0072] S2, balance reaction: 30 g of methyl polysiloxane mixed ring body and 5 g of hexamethyldisiloxane were added to the reaction vessel of step S1, and the two were condensed with the methylphenyl condensate at 90°C at 300 r / min for the first stage reaction for 2 h, 0.34 g of (CH3)4NOH was added, stirred for 0.2 h, the reaction temperature (90°C) was maintained, and the second stage reaction was carried out at 200 r / min under -0.09 MPa for 2 h, the pressure was released and protected by nitrogen, the temperature was raised to 110°C, the third stage reaction was carried out for 5 h, the temperature was raised to 150°C, and stirring was carried out for 1 h to obtain a broken medium product;

[0073] S3, adsorption: the broken medium product of step S2 was transferred to an adsorption vessel, 1% activated carbon was added for adsorption, and stirring was carried out for 2 h to obtain a crude silicone oil;

[0074] S4, low removal: the crude silicone oil of step S3 was transferred to a low removal vessel, 1% CeO2 was added, and the heat-resistant agent was removed with the crude silicone oil at 300 r / min under -0.1 MPa and 300°C for 3 h to obtain a low removal product;

[0075] S5, filtration: the low removal product of step S4 was cooled to room temperature, 1% activated carbon was added for adsorption, and stirring was carried out for 2 h to obtain 265 g of methylphenyl silicone oil.

[0076] Comparative Example 2

[0077] A method for preparing a low volatile methylphenyl silicone oil, comprising the following steps:

[0078] S1, condensation reaction: 300 g of methyl and phenyl polysiloxane mixed hydrolysate was added to a reaction vessel, 0.24 g of (CH3)4NOH was added, and the basic catalyst was condensed with the methyl and phenyl polysiloxane mixed hydrolysate at 200 r / min under -0.08 MPa and 100°C for 2 h to obtain a methylphenyl condensate, and the pressure was released by nitrogen to restore normal pressure;

[0079] S2, balance reaction: 30 g of methyl polysiloxane mixed ring body and 5 g of hexamethyldisiloxane were added to the reaction vessel of step S1, and the two were condensed with the methylphenyl condensate at 90°C at 300 r / min for the first stage reaction for 2 h, 0.34 g of (CH3)4NOH was added, stirred for 0.2 h, the reaction temperature (90°C) was maintained, and the second stage reaction was carried out at 200 r / min under -0.09 MPa for 2 h, the pressure was released and protected by nitrogen, the temperature was raised to 110°C, the third stage reaction was carried out for 5 h, the temperature was raised to 150°C, and stirring was carried out for 1 h to obtain a broken medium product;

[0080] S3, adsorption: the broken medium product of step S2 was transferred to an adsorption vessel, 1% activated carbon was added for adsorption, and stirring was carried out for 2 h to obtain a crude silicone oil;

[0081] S4, de-low: the crude silicone oil in step S3 was transferred to a de-low container, and the crude silicone oil was de-low at 300 r / min under -0.1 MPa and 300 °C for 3 h to obtain a de-low product;

[0082] S5, filtration: the de-low product in step S4 was cooled to room temperature, 1% activated carbon was added for adsorption, stirred for 2 h, and then filtered to obtain 256 g of methyl phenyl silicone oil.

[0083] Comparative Example 3

[0084] A method for preparing a low volatile methyl phenyl silicone oil, comprising the following steps:

[0085] S1, condensation reaction: 300 g of methyl and phenyl polysiloxane mixed hydrolysate was added to a reaction container, 0.24 g of (CH3)4NOH was added, and the basic catalyst and the methyl and phenyl polysiloxane mixed hydrolysate were subjected to condensation reaction at 200 r / min under -0.08 MPa and 100 °C for 2 h to obtain a methyl phenyl condensate. The normal pressure was restored by nitrogen pressure relief;

[0086] S2, equilibrium reaction: 30 g of methyl polysiloxane mixed ring and 5 g of hexamethyl disiloxane were added to the reaction container in step S1, and the two were subjected to first stage reaction with the methyl phenyl condensate at 300 r / min under 90 °C for 2 h, the reaction temperature (90 °C) was maintained, and the second stage reaction was carried out at 200 r / min under -0.09 MPa for 2 h. The temperature was raised to 110 °C by nitrogen pressure relief and protection, and the third stage reaction was carried out for 5 h. The temperature was raised to 150 °C and stirred for 1 h to obtain a breaking medium product;

[0087] S3, adsorption: the breaking medium product in step S2 was transferred to an adsorption container, 1% activated carbon was added for adsorption, stirred for 2 h, and then filtered to obtain a crude silicone oil;

[0088] S4, de-low: the crude silicone oil in step S3 was transferred to a de-low container, and the crude silicone oil was de-low at 300 r / min under -0.1 MPa and 300 °C for 3 h to obtain a de-low product;

[0089] S5, filtration: the de-low product in step S4 was cooled to room temperature, 1% activated carbon was added for adsorption, stirred for 2 h, and then filtered to obtain 260 g of methyl phenyl silicone oil.

[0090] The performance tests of the above Examples 1-4 and Comparative Examples 1-3 were carried out, and the test conditions were as follows, and the test data were shown in Table 1.

[0091] Volatile matter: 5g of sample was placed in a known mass of egg tart cup (diameter 8cm, height 3cm), heated at 250℃ for 4h by blowing, and volatile matter was allowed to escape. After heating, the egg tart cup was cooled to room temperature and weighed again. The content of volatile matter was calculated.

[0092] Table 1 methylphenyl silicone oil data of examples 1-4 and comparative examples 1-3

[0093]

[0094] Note: "D" means detected, and "ND" means not detected.

[0095] As shown in Table 1, compared with comparative examples 1-4, the methylphenyl silicone oil of examples 1-4 has no odor, controllable viscosity and refractive index parameters, narrow molecular weight distribution, few impurity groups and low volatile matter. Compared with example 1, example 4 can effectively reduce the volatile matter of the methylphenyl silicone oil by increasing the low removal time, while having little effect on other properties.

[0096] Compared with example 1, the parameters of comparative examples 1-3 are poorly controllable. Among them, the methylphenyl silicone oil of comparative example 1 has higher viscosity, molecular weight distribution index and volatile matter, and residual methoxy group, without adding basic catalyst after the end of the equilibrium reaction; the methylphenyl silicone oil of comparative example 2 has higher viscosity, molecular weight distribution index and volatile matter, and irritating odor, without using heat-resistant agent in the low removal stage; the methylphenyl silicone oil of comparative example 3 has higher viscosity, molecular weight distribution index and volatile matter, and residual methoxy group, without using basic catalyst and heat-resistant agent.

[0097] The preparation method of the low volatile matter methylphenyl silicone oil of the present application is easy to obtain and has low cost. By mixing the hydrolyzate and the basic catalyst, by separately adding the chain extender and the end-capping agent, methylphenyl silicone oil with different viscosity and refractive index parameters can be designed and obtained. By combining the basic catalyst and the heat-resistant agent, impurity groups in the silicone oil can be removed, while ensuring the integrity of the silicone oil chain during preparation, thereby obtaining high-quality methylphenyl silicone oil, i.e. low volatile matter methylphenyl silicone oil with stable controllable parameters, narrow molecular weight distribution and few impurity groups.

[0098] The above only further illustrates the technical content of the present application by examples, so that the reader can more easily understand, but does not represent that the embodiments of the present application are limited to this. Any technical extension or re-creation made according to the present application is protected by the present application. The protection scope of the present application is subject to the claims.

Claims

1. A method for preparing a low-volatile methylphenyl silicone oil, characterized in that: Includes the following steps: S1. Condensation reaction: A mixture of methyl and phenyl polysiloxane hydrolysate is added to a reaction vessel, and an alkaline catalyst is added so that the alkaline catalyst reacts with the mixture of methyl and phenyl polysiloxane hydrolysate to obtain a methylphenyl condensate. S2, Equilibrium reaction: Add methyl polysiloxane mixed cyclic compound and hexamethyldisiloxane to the reaction vessel described in step S1, so that the two react with the methyl phenyl condensate in the first stage reaction. Add alkaline catalyst, stir, carry out the second stage reaction under negative pressure, raise the temperature, carry out the third stage reaction, and obtain the catalyst-breaking product by breaking the catalyst under normal pressure. S3. Adsorption: The decomposed product described in step S2 is transferred to an adsorption container, activated carbon is added for adsorption, the mixture is stirred, and filtered to obtain crude silicone oil. S4. Degradation: Transfer the crude silicone oil obtained in step S3 to a degradation container, add a heat resistant agent, and allow the heat resistant agent to degrade the crude silicone oil to obtain a degradation product. S5. Filtration: Cool the de-lowering product obtained in step S4 to room temperature, add activated carbon for adsorption, stir, and filter to obtain methylphenyl silicone oil.

2. The method for preparing low-volatile methylphenyl silicone oil according to claim 1, characterized in that: The structural formula of the methyl and phenyl polysiloxane mixed hydrolysate in step S1 is: Where x:y=1:(1~2); x+y=(2~20); methoxy residue=1%wt.

3. The method for preparing low-volatile methylphenyl silicone oil according to claim 1, characterized in that: The condensation reaction conditions described in step S1 are: vacuum degree: -0.05 to -0.1 MPa, reaction temperature: 80 to 120°C, stirring speed: 100 to 400 r / min, and reaction time: 1 to 5 h. After the condensation reaction is completed, the pressure is released by nitrogen gas to restore normal pressure.

4. The method for preparing low-volatile methylphenyl silicone oil according to claim 1, characterized in that: Step S2: The reaction conditions for the first stage are: reaction temperature: 80-120℃, stirring speed: 100-400 r / min, and reaction time: 1-5 h. After adding the alkaline catalyst in step S2, the stirring time is 0–0.5 h; The reaction conditions for the second stage in step S2 are: vacuum degree: -0.08 to -0.1 MPa, stirring speed: 100 to 400 r / min, and reaction time: 1 to 6 h. The second stage of the reaction process is protected by nitrogen pressure relief; The reaction conditions for the third stage described in step S2 are: reaction temperature: 100-120℃, reaction time: 1-8h; The atmospheric pressure decomposition conditions described in step S2 are: reaction temperature: 150℃, stirring time: 1h.

5. The method for preparing low-volatile methylphenyl silicone oil according to claim 1, characterized in that: The alkaline catalyst mentioned in steps S1 and S2 is one of NaOH, KOH, LiOH, or (CH3)4NOH.

6. The method for preparing low-volatile methylphenyl silicone oil according to claim 5, characterized in that: The amount of alkaline catalyst used in step S1 is 500-1000 ppm.

7. The method for preparing low-volatile methylphenyl silicone oil according to claim 5, characterized in that: The amount of alkaline catalyst used in step S2 is 500 to 2000 ppm.

8. The method for preparing low-volatile methylphenyl silicone oil according to claim 1, characterized in that: The stirring time in steps S3 and S4 is 1 to 3 hours.

9. The method for preparing low-volatile methylphenyl silicone oil according to claim 1, characterized in that: The heat-resistant agent mentioned in step S4 is one of CeO2, Fe2O3, and SnO2.

10. The method for preparing low-volatile methylphenyl silicone oil according to claim 1, characterized in that: The desliming conditions described in step S4 are: vacuum degree: -0.1MPa, temperature: 250~320℃, stirring speed: 100~400r / min, and desliming time: 1~6h.

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