Preparation method of methyl phenyl silicone oil with low volatile matter

Abstract

According to the preparation method of the low-volatile-matter methyl phenyl silicone oil, synthetic raw materials are easy to obtain, the cost is low, the methyl phenyl silicone oil with different viscosity and refractive index parameters can be designed by matching the mixed hydrolysate with the basic catalyst and separately feeding the chain extender and the end-capping reagent, and the low-volatile-matter methyl phenyl silicone oil can be prepared by matching the basic catalyst with the heat-resistant agent. Impurity groups in the silicone oil can be removed, the integrity of a silicone oil chain in the preparation process is ensured, oxidative deterioration of the silicone oil chain caused by high temperature is effectively prevented, and then a low-volatile-matter high-quality methyl phenyl silicone oil product is obtained.

Description

[Technical field]

[0001] The invention belongs to the technical field of silicone oil preparation, and in particular relates to a method for preparing low-volatile methylphenyl silicone oil. [Background technology]

[0002] Phenyl silicone oil is a linear organopolysiloxane with excellent heat resistance, cold resistance, radiation resistance and light transmittance, and its side chain has a phenyl group. Compared with methyl silicone oil, phenyl silicone oil has a wider range of applications in personal care, industrial thermal conductivity, aerospace, nuclear power and other fields. With the advancement of science and technology, the quality requirements for phenyl silicone oil are getting higher and higher, including stable and controllable basic parameters, narrow molecular weight distribution, few impurity groups, and low volatility.

[0003] At present, there are two common methods for synthesizing phenyl silicone oil:

[0004] 1) Ring-opening equilibrium polymerization method: using phenyl mixed ring body, methyl mixed ring body or chain as chain extender, hexamethyldisiloxane or methylpolysiloxane short chain as end capping agent, and carrying out ring-opening equilibrium polymerization reaction under the action of catalyst. For example, Chinese invention patent CN115947944A discloses a method for preparing phenylmethyl silicone oil with high phenyl content, using octaphenylcyclotetrasiloxane as phenyl chain extender, using KOH as catalyst to dissolve phenyl ring body under high temperature conditions, and then adding methylpolysiloxane with a certain number of chain segments as methyl chain extender and end capping agent to carry out equilibrium reaction, and after adsorption, filtration and high temperature desulfurization, yellow transparent methylphenyl silicone oil is obtained. This is because the high temperature reaction conditions will cause the silicone oil chain to change, even after activated carbon adsorption and filtration, the color of the product silicone oil is still yellow.

[0005] 2) Hydrolyzate condensation method: through the condensation reaction of phenyl hydrolyzate, and then with methyl mixed ring or chain, hexamethyldisiloxane for ring-opening equilibrium reaction. For example, Chinese invention patent CN109776801A discloses a method for preparing phenyl silicone oil, using methyl and phenyl co-hydrolyzate as chain extender, hexamethyldisiloxane as end-capping agent, trifluoromethanesulfonic acid as catalyst for equilibrium reaction, and after the equilibrium is completed, silazane substances are added to remove hydroxyl groups, and methylphenyl silicone oil is obtained by high-temperature deoxidation. However, in the high-temperature equilibrium reaction, trifluoromethanesulfonic acid easily reacts with benzene rings to generate impurity groups, and after the silazane substances remove the hydroxyl groups, the number of silicone oil chains cannot be restored to the number of silicone oil links corresponding to the normal methyl end-capping amount, and the subsequent high-temperature deoxidation may also cause the phenyl silicone oil chain to oxidize and deteriorate. [Summary of the invention]

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

[0007] The present invention is achieved by the following technical solutions:

[0008] A method for preparing low-volatile methylphenyl silicone oil comprises the following steps:

[0009] S1, condensation reaction: adding a mixed hydrolyzate of methyl and phenyl polysiloxane into a reaction container, adding an alkaline catalyst, so that the alkaline catalyst and the mixed hydrolyzate of methyl and phenyl polysiloxane undergo a condensation reaction to obtain a methylphenyl condensate;

[0010] S2, equilibrium reaction: adding methyl polysiloxane mixed ring body and hexamethyldisiloxane to the reaction container described in step S1, so that the two react with the methylphenyl condensate in the first stage, adding an alkaline catalyst, stirring, and carrying out the second stage reaction under negative pressure, heating, and carrying out the third stage reaction, and breaking the catalyst under normal pressure to obtain a broken catalyst product;

[0011] S3, adsorption: the broken product of step S2 is transferred to an adsorption container, activated carbon is added for adsorption, stirred, and filtered to obtain crude silicone oil;

[0012] S4, desulfurization: the crude silicone oil in step S3 is transferred to a desulfurization container, and a heat-resistant agent is added to allow the heat-resistant agent to desulfurize the crude silicone oil to obtain a desulfurization product;

[0013] S5, filtration: the desulfurization product of step S4 is cooled to room temperature, activated carbon is added for adsorption, stirred, and filtered to obtain methylphenyl silicone oil.

[0014] Wherein, the structure of the mixed hydrolyzate of methyl and phenyl polysiloxane in step S1 is:

[0015]

[0016] In the formula, x:y=1:(1-2); x+y=(2-20); the residual methoxyl group content ≈1%wt.

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

[0018]

[0019] First, a mixed hydrolyzate of methyl and phenyl polysiloxane is used as a chain extender. By using an alkaline catalyst, the condensation reaction of the mixed hydrolyzate of methyl and phenyl polysiloxane can be promoted to generate a methylphenyl condensate, and the subsequent equilibrium reaction of the methylphenyl condensate with the methyl chain extender and the end-capping agent can be promoted. Second, a methyl polysiloxane mixed ring body is added as a methyl chain extender, and hexamethyldisiloxane is used as an end-capping agent. By separately adding the chain extender and the end-capping agent, and carrying out an equilibrium reaction with the methylphenyl condensate, methylphenyl silicone oils with different viscosity and refractive index parameters can be designed. Specifically, the viscosity is 10 to 5000 cs, and the refractive index is 1.4200 to 1.5200.

[0020] Then, adding an alkaline catalyst after the equilibrium reaction can promote the hydrolysis and condensation of the residual methoxy groups, further remove the methoxy groups and hydroxyl groups, and thus improve the stability of the silicone oil. It can also enhance the equilibrium recovery speed of the reaction system after the equilibrium is destroyed, and promote the uniform arrangement of methyl units and phenyl units in the methylphenyl silicone oil molecular chain, thereby ensuring the integrity of the silicone oil chain. Third, by adding a heat-resistant agent, the methylphenyl silicone oil chain is protected from oxidation during high-temperature deoxidation to ensure the integrity of the silicone oil chain. The heat-resistant agent can be removed by activated carbon adsorption filtration, which is conducive to obtaining low-volatile products and does not affect the back-end application of phenyl silicone oil.

[0021] Preferably, the condensation reaction conditions 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 restored to normal pressure by nitrogen decompression, which can avoid oxidation of the product due to contact with oxygen when returning to normal pressure, so as to ensure the purity and quality of the product.

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

[0023] Preferably, the first stage reaction conditions of step S2 are reaction temperature: 80-120°C, stirring speed: 100-400 r / min, reaction time: 1-5 h. More preferably, reaction temperature: 90°C, stirring speed: 200 r / min, reaction time: 2 h.

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

[0025] Preferably, the reaction conditions of 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 reaction process is depressurized and protected by nitrogen. 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 conditions in step S2 are reaction temperature: 100-120° C., reaction time: 1-8 h. More preferably, reaction temperature: 110° C., reaction time: 5 h.

[0027] Preferably, the conditions for breaking the catalyst at normal pressure in step S2 are reaction temperature: 150° C., stirring time: 1 h.

[0028] Preferably, the alkaline catalyst in step S1 and step S2 is one of NaOH, KOH, LiOH, (CH3)4NOH. Among them, in step S1, the condensation reaction of the mixed hydrolyzate of methyl and phenyl polysiloxane can be promoted by the coordination of the alkaline catalyst to generate a methylphenyl condensate, and the subsequent equilibrium reaction of the methylphenyl condensate with a methyl chain extender and an end-capping agent can also be promoted. In step S2, by adding an alkaline catalyst after the equilibrium reaction, the residual methoxy group can be promoted to be hydrolyzed and condensed, and the methoxy group and hydroxyl group can be further removed, thereby improving the stability of the silicone oil, and also enhancing the equilibrium recovery speed of the reaction system after the equilibrium is destroyed, and promoting the uniform arrangement of the methyl unit and the phenyl unit in the methylphenyl silicone oil molecular chain, thereby ensuring the integrity of the silicone oil chain.

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

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

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

[0032] Preferably, the amount of activated carbon used in step S3 and step S4 is 0.1-3% of the weight of the methylphenyl silicone oil, and the stirring time is 1-3 hours. More preferably, the amount of activated carbon used is 1% of the weight of the methylphenyl silicone oil, and the stirring time is 2 hours.

[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% of the weight of the methylphenyl silicone oil. The heat-resistant agent can protect the methylphenyl silicone oil chain from being oxidized when it is deoxidized at high temperature, can effectively inhibit the oxidation and breakage of the silicone oil chain, ensure the integrity of the silicone oil chain, and the heat-resistant agent can be removed by activated carbon adsorption and filtration without affecting the back-end application of phenyl silicone oil. In addition, in order to increase the compatibility of the heat-resistant agent with silicone oil, hexamethyldisilazane is used to treat the heat-resistant agent on the surface, and the heat-resistant agent is removed and dried before use.

[0034] More preferably, the heat-resistant agent is CeO2. The CeO2 is irregular in shape and has a particle size of 4 um. Cerium dioxide has excellent heat resistance, can maintain chemical stability in a high temperature environment, is not easy to decompose or volatilize, and has a variable valence state, and can preferentially react with free radicals, thereby preventing the silicone oil chain from undergoing a deterioration reaction.

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

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

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

[0038] The present invention provides a preparation method of low-volatile methylphenyl silicone oil. First, a methyl and phenyl polysiloxane mixed hydrolyzate is used as a chain extender, and a basic catalyst is used to promote the condensation reaction of the methyl and phenyl polysiloxane mixed hydrolyzate to generate a methylphenyl condensate, and the methylphenyl condensate can also be promoted to perform a balance reaction with the methyl chain extender and the end-capping agent. Second, a methylpolysiloxane mixed ring body is added as a methyl chain extender, and hexamethyldisiloxane is used as an end-capping agent. By separately adding the chain extender and the end-capping agent, a balance reaction is performed with the methylphenyl condensate, and methylphenyl silicone oils with different viscosity and refractive index parameters can be designed. Then, after the balance reaction, an alkaline catalyst is added to promote the hydrolysis and condensation of the residual methoxy group, further remove the methoxy group and the hydroxyl group, and then improve the stability of the silicone oil, and also can strengthen the balance recovery speed of the reaction system after the balance is destroyed, and promote the uniform arrangement of the methyl unit and the phenyl unit in the methylphenyl silicone oil molecular chain, and then ensure the integrity of the silicone oil chain. Third, by adding heat-resistant agents, the methylphenyl silicone oil chain can be protected from oxidation during high-temperature deoxidation to ensure the integrity of the silicone oil chain. The heat-resistant agent can be removed by activated carbon adsorption and filtration, which is conducive to obtaining low-volatile products and does not affect the back-end application of phenyl silicone oil.

[0039] The preparation method of the low-volatile methylphenyl silicone oil of the present invention has the advantages that the synthetic raw materials are easy to obtain and the cost is low. By combining a mixed hydrolyzate with an alkaline catalyst and separately adding a chain extender and an end-capping agent, methylphenyl silicone oils with different viscosity and refractive index parameters can be designed and obtained. Furthermore, by combining an alkaline catalyst with a heat-resistant agent, impurity groups in the silicone oil can be removed, and the integrity of the silicone oil chain in the preparation process is ensured, thereby obtaining high-quality methylphenyl silicone oil. [Specific implementation method]

[0040] The specific technical scheme of the present invention is described below in conjunction with Examples 1-4:

[0041] Example 1

[0042] A method for preparing low-volatile methylphenyl silicone oil comprises the following steps:

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

[0044] S2, equilibrium reaction: add 30g of methyl polysiloxane mixed ring body and 5g of hexamethyldisiloxane to the reaction container described in step S1, carry out the first stage reaction with the methylphenyl condensate at 300r / min at 90°C for 2h, add 0.34g (CH3)4NOH, stir for 0.2h, maintain the reaction temperature (90°C), carry out the second stage reaction at 200r / min at -0.09MPa for 2h, release the pressure and protect with nitrogen, raise the temperature to 110°C, carry out the third stage reaction for 5h, raise the temperature to 150°C, stir for 1h, and obtain the broken catalyst product;

[0045] S3, adsorption: the broken product of step S2 is transferred to an adsorption container, 1% activated carbon is added for adsorption, stirred for 2 hours, and crude silicone oil is obtained after filtering;

[0046] S4, desulfurization: the crude silicone oil in step S3 is transferred to a desulfurization container, 1% CeO2 is added, and the heat-resistant agent and the crude silicone oil are desulfurized at 300r / min for 3h at -0.1MPa and 300°C to obtain a desulfurization product;

[0047] S5, filtration: the desulfurization product of step S4 was cooled to room temperature, 1% activated carbon was added for adsorption, stirred for 2 hours, and filtered to obtain 262 g of methylphenyl silicone oil.

[0048] Example 2

[0049] A method for preparing low-volatile methylphenyl silicone oil comprises the following steps:

[0050] S1, condensation reaction: 300g of methyl and phenyl polysiloxane mixed hydrolyzate is added to a reaction container, 0.24g of (CH3)4NOH is added, the alkaline catalyst and the methyl and phenyl polysiloxane mixed hydrolyzate are subjected to condensation reaction at 200r / min at -0.08MPa and 100°C for 2h to obtain a methylphenyl condensate, and the pressure is restored to normal pressure by nitrogen decompression;

[0051] S2, equilibrium reaction: add 30g of methyl polysiloxane mixed ring body and 5g of hexamethyldisiloxane to the reaction container described in step S1, carry out the first stage reaction with the methylphenyl condensate at 300r / min at 90°C for 2h, add 0.50g (CH3)4NOH, stir for 0.2h, maintain the reaction temperature (90°C), carry out the second stage reaction at 200r / min at -0.09MPa for 2h, release the pressure and protect with nitrogen, raise the temperature to 110°C, carry out the third stage reaction for 5h, raise the temperature to 150°C, stir for 1h, and obtain the broken catalyst product;

[0052] S3, adsorption: the broken product of step S2 is transferred to an adsorption container, 1% activated carbon is added for adsorption, stirred for 2 hours, and crude silicone oil is obtained after filtering;

[0053] S4, desulfurization: the crude silicone oil in step S3 is transferred to a desulfurization container, 1% CeO2 is added, and the heat-resistant agent and the crude silicone oil are desulfurized at 300r / min for 3h at -0.1MPa and 300°C to obtain a desulfurization product;

[0054] S5, filtration: the desulfurization product of step S4 was cooled to room temperature, 1% activated carbon was added for adsorption, stirred for 2 hours, and filtered to obtain 258 g of methylphenyl silicone oil.

[0055] Example 3

[0056] A method for preparing low-volatile methylphenyl silicone oil comprises the following steps:

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

[0058] S2, equilibrium reaction: add 30g of methyl polysiloxane mixed ring body and 5g of hexamethyldisiloxane to the reaction container described in step S1, carry out the first stage reaction with the methylphenyl condensate at 300r / min at 90°C for 2h, add 0.34g (CH3)4NOH, stir for 0.2h, maintain the reaction temperature (90°C), carry out the second stage reaction at 200r / min at -0.09MPa for 2h, release the pressure and protect with nitrogen, raise the temperature to 110°C, carry out the third stage reaction for 5h, raise the temperature to 150°C, stir for 1h, and obtain the broken catalyst product;

[0059] S3, adsorption: the broken product of step S2 is transferred to an adsorption container, 1% activated carbon is added for adsorption, stirred for 2 hours, and crude silicone oil is obtained after filtering;

[0060] S4, desulfurization: the crude silicone oil in step S3 is transferred to a desulfurization container, 1% SnO2 is added, and the heat-resistant agent and the crude silicone oil are desulfurized at 300r / min for 3h at -0.1MPa and 300°C to obtain a desulfurization product;

[0061] S5, filtration: the desulfurization product of step S4 was cooled to room temperature, 1% activated carbon was added for adsorption, stirred for 2 hours, and filtered to obtain 265g of methylphenyl silicone oil.

[0062] Example 4

[0063] A method for preparing low-volatile methylphenyl silicone oil comprises the following steps:

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

[0065] S2, equilibrium reaction: add 30g of methyl polysiloxane mixed ring body and 5g of hexamethyldisiloxane to the reaction container described in step S1, carry out the first stage reaction with the methylphenyl condensate at 300r / min at 90°C for 2h, add 0.34g (CH3)4NOH, stir for 0.2h, maintain the reaction temperature (90°C), carry out the second stage reaction at 200r / min at -0.09MPa for 2h, release the pressure and protect with nitrogen, raise the temperature to 110°C, carry out the third stage reaction for 5h, raise the temperature to 150°C, stir for 1h, and obtain the broken catalyst product;

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

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

[0068] S5, filtration: the desulfurization product of step S4 was cooled to room temperature, 1% activated carbon was added for adsorption, stirred for 2 hours, and filtered to obtain 261g of methylphenyl silicone oil.

[0069] Comparative Example 1

[0070] A method for preparing low-volatile methylphenyl silicone oil comprises the following steps:

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

[0072] S2, equilibrium reaction: add 30g of methyl polysiloxane mixed ring body and 5g of hexamethyldisiloxane to the reaction container described in step S1, and carry out the first stage reaction with the methylphenyl condensate at 300r / min at 90°C for 2h, maintain the reaction temperature (90°C), carry out the second stage reaction at 200r / min at -0.09MPa for 2h, release the pressure and protect with nitrogen, raise the temperature to 110°C, carry out the third stage reaction for 5h, raise the temperature to 150°C, stir for 1h, and obtain the decomposition product;

[0073] S3, adsorption: the broken product of step S2 is transferred to an adsorption container, 1% activated carbon is added for adsorption, stirred for 2 hours, and crude silicone oil is obtained after filtering;

[0074] S4, desulfurization: the crude silicone oil in step S3 is transferred to a desulfurization container, 1% CeO2 is added, and the heat-resistant agent and the crude silicone oil are desulfurized at 300r / min for 3h at -0.1MPa and 300°C to obtain a desulfurization product;

[0075] S5, filtration: the desulfurization product of step S4 was cooled to room temperature, 1% activated carbon was added for adsorption, stirred for 2 hours, and filtered to obtain 265g of methylphenyl silicone oil.

[0076] Comparative Example 2

[0077] A method for preparing low-volatile methylphenyl silicone oil comprises the following steps:

[0078] S1, condensation reaction: 300g of methyl and phenyl polysiloxane mixed hydrolyzate is added to a reaction container, 0.24g of (CH3)4NOH is added, the alkaline catalyst and the methyl and phenyl polysiloxane mixed hydrolyzate are subjected to condensation reaction at 200r / min at -0.08MPa and 100°C for 2h to obtain a methylphenyl condensate, and the pressure is restored to normal pressure by nitrogen decompression;

[0079] S2, equilibrium reaction: add 30g of methyl polysiloxane mixed ring body and 5g of hexamethyldisiloxane to the reaction container described in step S1, carry out the first stage reaction with the methylphenyl condensate at 300r / min at 90°C for 2h, add 0.34g (CH3)4NOH, stir for 0.2h, maintain the reaction temperature (90°C), carry out the second stage reaction at 200r / min at -0.09MPa for 2h, release the pressure and protect with nitrogen, raise the temperature to 110°C, carry out the third stage reaction for 5h, raise the temperature to 150°C, stir for 1h, and obtain the broken catalyst product;

[0080] S3, adsorption: the broken product of step S2 is transferred to an adsorption container, 1% activated carbon is added for adsorption, stirred for 2 hours, and crude silicone oil is obtained after filtering;

[0081] S4, desulfurization: the crude silicone oil in step S3 is transferred to a desulfurization container, and the crude silicone oil is desulfurized at 300 r / min for 3 hours at -0.1 MPa and 300° C. to obtain a desulfurization product;

[0082] S5, filtration: the desulfurization product in step S4 was cooled to room temperature, 1% activated carbon was added for adsorption, stirred for 2 hours, and filtered to obtain 256 g of methylphenyl silicone oil.

[0083] Comparative Example 3

[0084] A method for preparing low-volatile methylphenyl silicone oil comprises the following steps:

[0085] S1, condensation reaction: 300g of methyl and phenyl polysiloxane mixed hydrolyzate is added to a reaction container, 0.24g of (CH3)4NOH is added, the alkaline catalyst and the methyl and phenyl polysiloxane mixed hydrolyzate are subjected to condensation reaction at 200r / min at -0.08MPa and 100°C for 2h to obtain a methylphenyl condensate, and the pressure is restored to normal pressure by nitrogen decompression;

[0086] S2, equilibrium reaction: add 30g of methyl polysiloxane mixed ring body and 5g of hexamethyldisiloxane to the reaction container described in step S1, and carry out the first stage reaction with the methylphenyl condensate at 300r / min at 90°C for 2h, maintain the reaction temperature (90°C), carry out the second stage reaction at 200r / min at -0.09MPa for 2h, release the pressure and protect with nitrogen, raise the temperature to 110°C, carry out the third stage reaction for 5h, raise the temperature to 150°C, stir for 1h, and obtain the decomposition product;

[0087] S3, adsorption: the broken product of step S2 is transferred to an adsorption container, 1% activated carbon is added for adsorption, stirred for 2 hours, and crude silicone oil is obtained after filtering;

[0088] S4, desulfurization: the crude silicone oil in step S3 is transferred to a desulfurization container, and the heat-resistant agent and the crude silicone oil are desulfurized at 300 r / min for 3 hours at -0.1 MPa and 300° C. to obtain a desulfurization product;

[0089] S5, filtration: the desulfurization product of step S4 was cooled to room temperature, 1% activated carbon was added for adsorption, stirred for 2 hours, and filtered to obtain 260 g of methylphenyl silicone oil.

[0090] The above-mentioned embodiments 1-4 and comparative examples 1-3 were subjected to performance tests. The test conditions were as follows and the test data are shown in Table 1.

[0091] Volatile matter: 5 g of the sample was placed in an egg tart cup (8 cm in diameter, 3 cm in height) of known mass, and heated with a blast at 250°C for 4 h to allow the volatile substances to escape. After the heating was completed, the egg tart cup was cooled to room temperature and weighed again to obtain the volatile matter content by calculation.

[0092] Table 1 Methylphenyl silicone oil data of Examples 1-4 and Comparative Examples 1-3

[0093]

[0094] Note: “D” means detected, “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 volatility. Compared with Example 1, Example 4 can effectively reduce the volatility of methylphenyl silicone oil by increasing the degassing time, while having almost no effect on other properties.

[0096] Compared with Example 1, the controllability of the parameters of Comparative Examples 1-3 is poor. Among them, the methylphenyl silicone oil of Comparative Example 1 does not add an alkaline catalyst after the equilibrium reaction, has a higher viscosity, molecular weight distribution index and volatile matter, and has residual methoxy groups; the methylphenyl silicone oil of Comparative Example 2 does not use a heat-resistant agent in the deoxidation stage, has a pungent odor, has a higher viscosity, molecular weight distribution index and volatile matter; the methylphenyl silicone oil of Comparative Example 3 does not use an alkaline catalyst and a heat-resistant agent, has a pungent odor, has a higher viscosity, molecular weight distribution index and volatile matter, and has residual methoxy groups.

[0097] The preparation method of the low-volatile methylphenyl silicone oil of the present invention has the advantages that the synthetic raw materials are easy to obtain and the cost is low. By combining a mixed hydrolyzate with an alkaline catalyst and separately adding a chain extender and an end-capping agent, methylphenyl silicone oils with different viscosity and refractive index parameters can be designed and obtained. Furthermore, by combining an alkaline catalyst with a heat-resistant agent, impurity groups in the silicone oil can be removed, and the integrity of the silicone oil chain in the preparation process can be ensured, thereby obtaining high-quality methylphenyl silicone oil, that is, low-volatile methylphenyl silicone oil with stably controllable parameters, narrow molecular weight distribution and less impurity groups.

[0098] The above examples are only used to further illustrate the technical content of the present invention, so that readers can understand it more easily, but they do not mean that the implementation of the present invention is limited to this. Any technical extension or re-creation made according to the present invention is protected by the present invention. The protection scope of the present invention shall be subject to the claims.

Claims

1. A method for preparing low-volatile methylphenyl silicone oil, characterized in that: The following steps are involved: S1, condensation reaction: adding a mixed hydrolyzate of methyl and phenyl polysiloxane into a reaction container, adding an alkaline catalyst, so that the alkaline catalyst and the mixed hydrolyzate of methyl and phenyl polysiloxane undergo a condensation reaction to obtain a methylphenyl condensate; S2, equilibrium reaction: adding methyl polysiloxane mixed ring body and hexamethyldisiloxane to the reaction container described in step S1, so that the two react with the methylphenyl condensate in the first stage, adding an alkaline catalyst, stirring, and carrying out the second stage reaction under negative pressure, heating, and carrying out the third stage reaction, and breaking the catalyst under normal pressure to obtain a broken catalyst product; S3, adsorption: the broken product of step S2 is transferred to an adsorption container, activated carbon is added for adsorption, stirred, and filtered to obtain crude silicone oil; S4, desulfurization: the crude silicone oil in step S3 is transferred to a desulfurization container, and a heat-resistant agent is added to allow the heat-resistant agent to desulfurize the crude silicone oil to obtain a desulfurization product; S5, filtration: the desulfurization product of step S4 is cooled to room temperature, activated carbon is added for adsorption, stirred, and filtered to obtain methylphenyl silicone oil.

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

3. The method for preparing the low-volatile methylphenyl silicone oil according to claim 1, characterized in that: The condensation reaction conditions 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 to return to normal pressure.

4. The method for preparing the low-volatile methylphenyl silicone oil according to claim 1, characterized in that: Step S2: The first stage reaction conditions are as follows: reaction temperature: 80-120°C, stirring speed: 100-400 r / min, reaction time: 1-5 h; Step S2: after adding the alkaline catalyst, the stirring time is 0 to 0.5 h; Step S2: The reaction conditions of the second stage 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 reaction process is depressurized and protected by nitrogen; The third stage reaction conditions in step S2 are reaction temperature: 100-120° C., reaction time: 1-8 h; The conditions for breaking the catalyst at normal pressure in step S2 are reaction temperature: 150° C., stirring time: 1 h.

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

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

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

8. The method for preparing the low-volatile methylphenyl silicone oil according to claim 1, characterized in that: The amount of activated carbon used in step S3 and step S4 is 0.1-3% of the weight of the methylphenyl silicone oil, and the stirring time is 1-3 hours.

9. The method for preparing the low-volatile methylphenyl silicone oil according to claim 1, characterized in that: In step S4, the heat-resistant agent is one of CeO2, Fe2O3, and SnO2, and the amount of the heat-resistant agent is 0.5-2% of the weight of the methylphenyl silicone oil.

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

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