Process for the preparation of mq silicone resins
By adding acetonitrile during the preparation of MQ silicone resin using the sodium silicate method and controlling the reaction conditions, the gel clogging problem was solved, enabling stable and continuous production of high molecular weight MQ silicone resin, and improving production efficiency and product stability.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- WANHUA CHEM GRP CO LTD
- Filing Date
- 2024-10-28
- Publication Date
- 2026-06-16
AI Technical Summary
In the sodium silicate method for preparing MQ silicone resin, the polymerization rate of the Q group is too fast, which can easily lead to gel formation, blockage of the reactor, and affect production efficiency and stability.
Acetonitrile is used as an additive, and the hydrolysis and condensation reaction conditions, including pH value, material ratio, and stirring speed, are controlled. Continuous production is carried out through a batch reactor to avoid gel blockage.
It effectively suppressed the gelation problem, achieved stable production of high molecular weight MQ silicone resin, improved the continuity of production and the stability of each batch of products, and reduced the requirements for stirring equipment and energy consumption.
Smart Images
Figure CN119350620B_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of polymer technology, and in particular to a method for preparing MQ silicone resin. Background Technology
[0002] MQ silicone resin is composed of monofunctional silicon-oxygen units (M group: R3SiO). 1 / 2 ) and tetrafunctional silicon-oxygen units (Q group: SiO) 4 / 2 MQ resin is a high-molecular polymer with a "core-shell" structure, mainly used in pressure-sensitive adhesives, defoamers, and personal care products. Regarding the source of the Q group, its synthesis methods include the silicate ester method and the sodium silicate method. The sodium silicate method is lower in cost and has more advantages in industrial production. However, in the preparation of MQ resin using the sodium silicate method, the Q group polymerizes very quickly, easily gels, and clogs the reactor, affecting production. Summary of the Invention
[0003] Based on this, this application provides a method for preparing MQ silicone resin, the technical solution of which is as follows:
[0004] A method for preparing MQ silicone resin includes the following steps:
[0005] Water glass, acetonitrile, and acid are mixed to undergo a hydrolysis-condensation reaction, yielding a polysilicic acid solution.
[0006] The polysilicic acid solution is subjected to a capping reaction to obtain MQ silicone resin.
[0007] Compared with traditional solutions, this application has the following advantages:
[0008] Water glass can undergo hydrolysis-condensation reactions in the presence of acid. To avoid reactor blockage caused by rapid gelation due to the condensation reaction, acetonitrile is added in this application. The addition of acetonitrile can effectively suppress the gelation problem of sodium silicate, especially in the production of high-molecular-weight MQ silicone resin, thus preventing reactor blockage caused by gelation. Furthermore, compared to methods that use vigorous stirring of water glass to prevent gelation, this application has lower requirements for stirring equipment and saves energy.
[0009] Optionally, the weight-average molecular weight of the MQ silicone resin is 10,000 Da to 40,000 Da. For example, the weight-average molecular weight of the MQ silicone resin is 10,000 Da, 20,000 Da, 30,000 Da, or 40,000 Da. The above-mentioned high molecular weight MQ silicone resin can be produced by controlling the hydrolysis-condensation reaction conditions, thus avoiding the problem of gel clogging the reactor. The hydrolysis-condensation reaction conditions are related to the pH value of the mixture of water glass, acetonitrile, and acid, the mass ratio of sodium silicate in the water glass, acetonitrile, and acidic compounds in the acid, the concentration of sodium silicate in the water glass, the concentration of acidic substances in the acid, the type of acid, the temperature of the hydrolysis-condensation reaction, and the average residence time of the water glass, acetonitrile, and acid in the reactor. In particular, the concentration of sodium silicate in the water glass is crucial.
[0010] Optionally, the pH value of the mixture of water glass, acetonitrile, and acid is <3. This favors the occurrence of hydrolysis-condensation reactions. Preferably, the pH value of the mixture of water glass, acetonitrile, and acid is 1-2.
[0011] Optionally, the mass ratio of sodium silicate, acetonitrile, and acidic compound in the water glass is (8~30):(1~3):(6~36). For example, mass ratios of 8:1:6, 15:1:15, 30:1:36, 8:3:6, 15:3:15, 30:3:36, etc.
[0012] The stirring speed for mixing the water glass, acetonitrile, and acid can be from 100 rpm to 300 rpm. For example, the stirring speed can be 100 rpm, 200 rpm, or 300 rpm.
[0013] Optionally, mixing the water glass, acetonitrile, and acid agent includes the following steps:
[0014] Acetonitrile and acid are continuously introduced into the reactor. After the reactor is filled, water glass is continuously introduced.
[0015] The above method enables continuous production of MQ silicone resin. Compared to batch production, the stability of various indicators of different batches of MQ silicone resin is better. More importantly, full-tank operation of the reactor can prevent skin formation in the empty volume of the reactor, which is conducive to long-term stable production. Furthermore, full-tank operation can also improve the stability of the hydrolysis-condensation reaction and narrow the molecular weight distribution of MQ silicone resin.
[0016] Understandably, the reactor can be a conventional batch reactor in the art, with an inlet and an outlet, the inlet located at the bottom and the outlet at the top. Compared to tubular reactors, using a batch reactor can avoid molecular weight fluctuations or gelation effects caused by feed fluctuations during the preparation of high molecular weight resins.
[0017] Acetonitrile and acid can be premixed before being introduced into the reactor, for example, in a static mixer, and then continuously pumped into the reactor through the static mixer. The static mixer can be of type SV, SK, SX, SH, or SL, with 1 to 100 units.
[0018] Optionally, after introducing the water glass, the pH value of the mixture in the reactor is controlled to be <3. This is beneficial for controlling the rate of the hydrolysis-condensation reaction. Preferably, the pH value of the mixture in the reactor is controlled to be 1-2.
[0019] Understandably, after introducing water glass, the reactor's stirring function is activated. The stirring speed can be from 100 rpm to 300 rpm. For example, the stirring speeds are 100 rpm, 200 rpm, and 300 rpm.
[0020] Optionally, after the water glass is introduced, the flow rates of the water glass, acid agent, and acetonitrile are controlled so that the mass ratio of sodium silicate in the water glass, acetonitrile, and acidic compound in the acid agent introduced per unit time is (8~30):(1~3):(6~36). For example, the mass ratios introduced are 8:1:6, 15:1:15, 30:1:36, 8:3:6, 15:3:15, 30:3:36, etc.
[0021] Optionally, the concentration of sodium silicate in the water glass is 10wt% to 30wt%. A higher concentration of sodium silicate is more advantageous for obtaining MQ silicone resin with a higher molecular weight. Optionally, the concentration of sodium silicate in the water glass is 16wt% to 30wt%, for example, 16wt%, 20wt%, 25wt%, and 30wt%. This is advantageous for combining other hydrolysis and condensation reaction conditions to prepare high molecular weight MQ silicone resin without gelation problems. For example, MQ silicone resin with a weight-average molecular weight of 10000 Da to 40000 Da can be prepared. Further preparation of MQ silicone resin with a weight-average molecular weight of 15000 Da to 25000 Da is also possible.
[0022] Optionally, the concentration of the acidic substance in the acidic agent is 8 wt% to 36 wt%. For example, the concentration of the acidic substance in the acidic agent is 8 wt%, 10 wt%, 15 wt%, 20 wt%, 30 wt%, or 36 wt%.
[0023] Optionally, the acid includes at least one of hydrochloric acid and sulfuric acid.
[0024] When hydrochloric acid, acetonitrile, and an acid agent coexist in the reactor, they undergo a hydrolysis-condensation reaction to generate an aqueous polysilicic acid solution. Because all three are continuously introduced and the reactor is fully operational, the hydrolysis-condensation reaction proceeds dynamically. The residence time of the acid agent is defined as the total reactor volume divided by the acid agent flow rate, the residence time of acetonitrile is defined as the total reactor volume divided by the acetonitrile flow rate, and the residence time of water glass is defined as the total reactor volume divided by the water glass flow rate. The average residence time of the water glass, acetonitrile, and acid agent in the reactor is the average of the residence times of the water glass, acetonitrile, and acid agent. Optionally, the average residence time is 0.1 min to 10 min. Preferably, the average residence time is 0.1 min to 3 min. Optionally, the temperature of the hydrolysis-condensation reaction is 0℃ to 40℃. Preferably, the temperature of the hydrolysis-condensation reaction is 10℃ to 30℃.
[0025] Optionally, the polysilicic acid solution, alcohol reagent, capping agent, and solvent are mixed to carry out a capping reaction.
[0026] Understandably, the end-capping reaction can be carried out in another reactor, which can be a conventional batch reactor with an inlet and an outlet, the inlet being located at the top and the outlet at the bottom. Let reactor A be the reactor where the hydrolysis-condensation reaction occurs, and reactor B be the end-capping reaction. The outlet of reactor A is connected to the inlet of reactor B. While fluid is continuously introduced from the bottom inlet of a full reactor A, the hydrolysis-condensation reaction products continuously flow from the top outlet of a full reactor A into reactor B. Furthermore, the entry of substances other than the hydrolysis-condensation reaction products from reactor A into reactor B does not affect the end-capping reaction occurring in reactor B.
[0027] Optionally, the end-capping agent is selected from one or more of trimethylchlorosilane, hexamethyldisiloxane, vinyldimethylchlorosilane, and divinyltetramethyldisiloxane.
[0028] Optionally, the end-capping agent accounts for 5 wt% to 20 wt% of the total mass of the polysilicic acid solution, the end-capping agent, the alcohol reagent, and the solvent. For example, the end-capping agent accounts for 5 wt%, 10 wt%, 15 wt%, and 20 wt% of the total mass of the polysilicic acid solution, the end-capping agent, the alcohol reagent, and the solvent, respectively.
[0029] Optionally, the alcohol reagent is selected from one or more of methanol, ethanol, propanol, butanol, isopropanol, and isobutanol.
[0030] Optionally, the mass of the alcohol reagent accounts for 10wt% to 25wt% of the total mass of the polysilicic acid solution, the capping agent, the alcohol reagent, and the solvent. For example, the mass of the alcohol reagent accounts for 10wt%, 15wt%, 20wt%, and 25wt% of the total mass of the polysilicic acid solution, the capping agent, the alcohol reagent, and the solvent, respectively.
[0031] Optionally, the solvent is selected from one or more of benzene, toluene, xylene, hexamethyldisiloxane, C6-C8 straight-chain alkanes, and C6-C8 branched-chain alkanes.
[0032] Optionally, the solvent accounts for 15 wt% to 50 wt% of the total mass of the polysilicic acid solution, the capping agent, the alcohol reagent, and the solvent. For example, the solvent accounts for 15 wt%, 25 wt%, 40 wt%, and 50 wt% of the total mass of the polysilicic acid solution, the capping agent, the alcohol reagent, and the solvent, respectively.
[0033] Optionally, the reaction temperature for the end-capping reaction is 40°C to 90°C. For example, the reaction temperatures for the end-capping reaction are 40°C, 70°C, and 90°C.
[0034] Optionally, the capping reaction time is 1 h to 3 h. For example, the capping reaction time is 1 h, 2 h, or 3 h.
[0035] Optionally, after the end-capping reaction, the following steps are also included:
[0036] The products obtained from the end-capping reaction are separated into phases, and the resulting organic phase is then subjected to distillation.
[0037] Further optionally, the product obtained from the end-capping reaction is subjected to phase separation, including the following steps: allowing the product obtained from the end-capping reaction to stand for a first time to obtain a first aqueous phase and a first organic phase; mixing the first organic phase and deionized water, and allowing it to stand for a second time to obtain a second aqueous phase and a second organic phase, wherein the second organic phase is the organic phase obtained by phase separation.
[0038] Understandably, the product obtained from the end-capping reaction can be passed into reactor C and allowed to stand for the first time. Optionally, the temperature of the first standing period is 60℃~90℃. Optionally, the time of the first standing period is 0.5h~3h. Reactor C can be a conventional batch reactor in the art, having an inlet and an outlet, with the inlet located at the top, the first aqueous phase being collected from the bottom, the first organic phase being collected from the top, and the outlet of reactor B being connected to the inlet of reactor C.
[0039] Optionally, the mass ratio of the first organic phase to the demineralized water is 1:(0.5~3). For example, the mass ratio of the first organic phase to the demineralized water is 1:0.5, 1:1, 1:2, or 1:3.
[0040] The first organic phase and the demineralized water can be pre-mixed, for example, in a static mixer, and then continuously pumped into reactor D through the static mixer for a second settling period. The static mixer can be of type SV, SK, SX, SH, or SL, with 1 to 100 units. Optionally, the temperature of the second settling period is 60°C to 90°C. Optionally, the settling time is 0.5 to 3 hours. Reactor D can be a conventional batch reactor with inlet and outlet, the inlet located at the top. The second aqueous phase is collected from the bottom, and the second organic phase is collected from the top. The first organic phase and the demineralized water from reactor C are mixed through the static mixer and then connected to the inlet of reactor D.
[0041] Both the first and second aqueous phases are treated as wastewater for further treatment. The organic phase undergoes distillation. Through distillation, light components and some solvents are removed from the organic phase.
[0042] Optionally, the distillation temperature is 140°C to 160°C. For example, the distillation temperature is 140°C, 150°C, or 160°C.
[0043] The above method, by adding acetonitrile, can effectively suppress the gelation problem of sodium silicate, especially in the production of high-molecular-weight MQ silicone resin, thus avoiding reactor blockage caused by gelation. Furthermore, the method of continuously introducing acetonitrile, acid, and water glass into the reactor enables continuous production of MQ resin, ensuring stable production processes and consistent performance across batches. Attached Figure Description
[0044] To more clearly illustrate the technical solutions in the embodiments of this application and to more completely understand this application and its beneficial effects, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0045] Figure 1 The diagram shows the structural design of the MQ silicone resin production apparatus for each embodiment and comparative example. Detailed Implementation
[0046] The present application will be further described in detail below with reference to specific embodiments. The present application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of this application.
[0047] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.
[0048] the term
[0049] Unless otherwise stated or in case of contradiction, the terms or phrases used herein shall have the following meanings:
[0050] In this application, the terms "multiple", "various", "multiple times", "multi-dimensional", etc., unless otherwise specified, refer to a quantity greater than or equal to 2. For example, "one or more" means one or more or more.
[0051] In this application, "several" means at least one, such as one, two, etc., unless otherwise expressly and specifically defined.
[0052] In this application, the terms "optionally," "optionally," and "optional" refer to options that are optional, meaning they can be selected from either "with" or "without." If multiple "optional" options appear in a technical solution, unless otherwise specified and there are no contradictions or mutual constraints, each "optional" option is independent.
[0053] In this application, the terms "first aspect," "second aspect," "third aspect," and "fourth aspect," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or quantity, nor should they be construed as implicitly indicating the importance or quantity of the indicated technical features. Moreover, "first," "second," "third," and "fourth," etc., serve only a non-exhaustive enumeration purpose and should be understood not to constitute a closed limitation on quantity.
[0054] In this application, numerical intervals (i.e., numerical ranges) are involved. Unless otherwise specified, the selected numerical distributions within the aforementioned numerical intervals are considered continuous and include the two endpoints (i.e., the minimum and maximum values) of the numerical range, as well as every value between these two endpoints. Unless otherwise specified, when a numerical interval refers only to integers within that interval, it includes the two endpoint integers of the numerical range, as well as every integer between the two endpoints. In this document, this is equivalent to directly listing every integer. For example, if t is an integer selected from 1 to 10, it means that t is any integer selected from the group of integers consisting of 1, 2, 3, 4, 5, 6, 7, 8, 9, and 10. Furthermore, when multiple ranges are provided to describe features or characteristics, these ranges can be merged. In other words, unless otherwise specified, the ranges disclosed herein should be understood to include any and all subranges to which they are included.
[0055] Unless otherwise specified, the temperature parameters in this application are permitted to be either constant-temperature treatment or variations within a certain temperature range. It should be understood that the constant-temperature treatment allows temperature fluctuations within the precision range of the instrument control, such as ±5℃, ±4℃, ±3℃, ±2℃, or ±1℃.
[0056] In this application, percentage content refers to mass percentage for solid-liquid mixtures and solid-phase-solid mixtures, and volume percentage for liquid-phase-liquid mixtures, unless otherwise specified.
[0057] In this application, unless otherwise specified, percentage concentrations refer to final concentrations. The final concentration refers to the percentage of the added component in the system after its addition.
[0058] In this application, %(w / w) and wt% both represent weight percentage, %(v / v) refers to volume percentage, and %(w / v) refers to mass-volume percentage.
[0059] The following description is further illustrated with specific embodiments and comparative examples. Unless otherwise specified, the raw materials involved in the following specific embodiments and comparative examples are all commercially available. Unless otherwise specified, the instruments used are all commercially available. Unless otherwise specified, the processes involved are conventionally selected by those skilled in the art.
[0060] The following specific examples and comparative examples show that the molecular weight and its distribution were tested using gel permeation chromatography (GPC) with ethyl acetate as the mobile phase. The GPC instrument was an Agilent 1260II GPC MDS. The specific test method is as follows: the sample was dissolved in ethyl acetate, separated by gel permeation chromatography, and a standard curve was prepared using standard PS (polystyrene) for relative calibration to determine the molecular weight and molecular weight distribution of the MQ silicone resin sample.
[0061] See Figure 1 The production apparatus for MQ silicone resin in each embodiment and comparative example is the same, including reactor A 10, reactor B 20, reactor C 30, reactor D 40, and static mixer 50. The outlet of reactor A 10 is connected to the inlet of reactor B, the outlet of reactor B is connected to the inlet of reactor C, and the outlet of reactor C is connected to the inlet of reactor D via static mixer 50.
[0062] Example 1
[0063] This embodiment provides an MQ silicone resin and its preparation method, the steps of which are as follows:
[0064] At 25°C, a 10.5 wt% hydrochloric acid aqueous solution and acetonitrile were continuously fed into reactor A at flow rates of 80 g / min and 1 g / min, respectively, until the tank was full. Then, a 25 wt% water glass solution was continuously fed into the full reactor A at a flow rate of 100 g / min, causing a hydrolysis-condensation reaction to obtain a polysilicic acid aqueous solution. Stirring was maintained in reactor A to ensure effective mixing of the three materials. After the water glass was introduced, the pH of the mixture in the reactor was measured to be 1.5. The average retention time was 7 min. The polysilicic acid aqueous solution, ethanol, toluene, and hexamethyldisiloxane were continuously fed into reactor B at flow rates of 181 g / min, 65 g / min, 70 g / min, and 17 g / min, respectively, for a capping reaction at 65°C for 2 h. The capping reaction product was then transferred to reactor C for a first settling period at 65°C for 1 h, yielding a first aqueous phase and a first organic phase. The first organic phase was separated and mixed with demineralized water in a static mixer, then continuously fed into reactor D for a second settling period. The feed rate of the demineralized water was 30 g / min, the temperature of the second settling period was 65℃, and the residence time was 2 h, yielding a second aqueous phase and a second organic phase. The second organic phase was then subjected to continuous distillation at 150℃ and atmospheric pressure to remove light components and some solvent, ultimately yielding an MQ silicone resin solution. GPC analysis of the obtained product showed a weight-average molecular weight of 22013 Da and a molecular weight distribution of 1.31.
[0065] In this embodiment, reactor A did not produce gel after running for 24 hours.
[0066] Example 2
[0067] This embodiment provides an MQ silicone resin and its preparation method, the steps of which are as follows:
[0068] At 15°C, 8wt% hydrochloric acid aqueous solution and acetonitrile were continuously fed into reactor A at flow rates of 100 g / min and 3 g / min respectively until the tank was full. Then, 25wt% water glass solution was continuously added to the full reactor A at a flow rate of 100 g / min, causing a hydrolysis-condensation reaction to obtain polysilicic acid aqueous solution. Stirring was maintained in reactor A to ensure the mixing effect of the three materials. After the water glass was introduced, the pH of the mixture in the reactor was measured to be 1.3. The average retention time was 5 min. Polysilicic acid aqueous solution, isopropanol, xylene, and divinyltetramethyldisiloxane were continuously fed into reactor B at rates of 203 g / min, 50 g / min, 85 g / min, and 21 g / min respectively for end-capping reaction. The end-capping reaction temperature was 50°C, and the reaction time was 3 h. Then, the end-capping reaction product was transferred to reactor C for a first settling period at 60°C for 1.5 h, yielding a first aqueous phase and a first organic phase. The first organic phase was separated and mixed with demineralized water in a static mixer, then continuously fed into reactor D for a second settling period. The feed rate of the demineralized water was 40 g / min, the temperature of the second settling period was 70℃, and the residence time was 1 h, yielding a second aqueous phase and a second organic phase. The second organic phase was then subjected to continuous distillation at 150℃ and atmospheric pressure to remove light components and some solvent, ultimately yielding an MQ silicone resin solution. GPC analysis of the obtained product showed a weight-average molecular weight of 20816 Da and a molecular weight distribution of 1.22.
[0069] In this embodiment, reactor A did not produce gel after running for 24 hours.
[0070] Example 3
[0071] This embodiment provides an MQ silicone resin and its preparation method, the steps of which are as follows:
[0072] At 30°C, 8wt% hydrochloric acid aqueous solution and acetonitrile were continuously fed into reactor A at flow rates of 80 g / min and 2 g / min respectively until the tank was full. Then, 23wt% water glass solution was continuously fed into the full reactor A at a flow rate of 80 g / min to undergo a hydrolysis-condensation reaction, yielding a polysilicic acid aqueous solution. Stirring was maintained in reactor A to ensure effective mixing of the three materials. After the introduction of water glass, the pH of the mixture in the reactor was measured to be 1. With an average retention time of 10 min, the polysilicic acid aqueous solution, methanol, benzene, and trimethylchlorosilane were continuously fed into reactor B at flow rates of 162 g / min, 45 g / min, 60 g / min, and 19 g / min respectively for end-capping reactions. The end-capping reaction temperature was 70°C, and the reaction time was 1 h. The end-capping reaction product was then transferred to reactor C for a first settling period at 70°C for 1 h, yielding a first aqueous phase and a first organic phase. The first organic phase was separated and mixed with demineralized water in a static mixer, then continuously fed into reactor D for a second settling period. The feed rate of the demineralized water was 35 g / min, the temperature of the second settling period was 70℃, and the residence time was 2 h, yielding a second aqueous phase and a second organic phase. The second organic phase was then subjected to continuous distillation at 150℃ and atmospheric pressure to remove light components and some solvent, ultimately yielding an MQ silicone resin solution. GPC analysis of the obtained product showed a weight-average molecular weight of 18926 Da and a molecular weight distribution of 1.42.
[0073] In this embodiment, reactor A did not produce gel after running for 24 hours.
[0074] Example 4
[0075] This embodiment provides an MQ silicone resin and its preparation method, which is basically the same as that in Example 1. The main difference is that a 10.5wt% hydrochloric acid aqueous solution and acetonitrile are continuously introduced into reactor A at flow rates of 40 g / min and 0.5 g / min, respectively, until reactor A is not full. Then, a 25wt% water glass solution is continuously introduced into reactor A at a flow rate of 50 g / min, and reactor A is still not full. A hydrolysis-condensation reaction occurs to obtain a polysilicic acid aqueous solution. Stirring is maintained in reactor A to ensure the mixing effect of the three materials. After the water glass is introduced, the pH of the mixture in the reactor is measured to be 1.5. The average retention time is 7 min. The polysilicic acid aqueous solution, ethanol, toluene, and hexamethyldisiloxane are continuously introduced into reactor B at rates of 90.5 g / min, 32.5 g / min, 35 g / min, and 8.5 g / min, respectively, for end-capping reaction. The end-capping reaction temperature is 65℃, and the reaction time is 2 h. The end-capping reaction product was then fed into reactor C for a first settling period at 65°C for 1 hour, yielding a first aqueous phase and a first organic phase. The first organic phase was separated and mixed with demineralized water in a static mixer, then continuously fed into reactor D for a second settling period at 15 g / min. The second settling period was at 65°C for 2 hours, yielding a second aqueous phase and a second organic phase. The second organic phase was then subjected to continuous distillation at 150°C and atmospheric pressure to remove light components and some solvent, ultimately yielding an MQ silicone resin solution. GPC analysis showed that the product had a weight-average molecular weight of 22517 Da and a molecular weight distribution of 1.73.
[0076] As the hydrolysis-condensation reaction proceeded, it was found that in this embodiment, although no gel was produced after reactor A had been running for 120 minutes, a crust formed on the empty volume reactor wall. Furthermore, compared to the product of Example 1, the molecular weight distribution of the product in this embodiment was significantly wider, indicating that the system was unstable.
[0077] Comparative Example 1
[0078] This comparative example provides an MQ silicone resin and its preparation method, which is basically the same as Example 1. The main difference is that a 10.5wt% hydrochloric acid aqueous solution is continuously fed into reactor A at a flow rate of 40g / min, acetonitrile is not fed in, and reactor A is not full. Then, a 25wt% water glass solution is continuously fed into reactor A at a flow rate of 50g / min. Reactor A is still not full, and a hydrolysis condensation reaction occurs.
[0079] As the hydrolysis-condensation reaction proceeded, it was found that in this comparative example, reactor A produced gel and became clogged after running for 5 minutes.
[0080] Comparative Example 2
[0081] This comparative example provides an MQ silicone resin and its preparation method, which is basically the same as Example 1. The main difference is that a 10.5wt% hydrochloric acid aqueous solution is continuously fed into reactor A at a flow rate of 80g / min until the tank is full, without the introduction of acetonitrile. Then, a 25wt% water glass solution is continuously fed into the full reactor A at a flow rate of 100g / min to carry out a hydrolysis-condensation reaction.
[0082] As the hydrolysis-condensation reaction proceeded, it was found that in this comparative example, reactor A produced gel and became clogged after running for 15 minutes.
[0083] The above comparisons show that in Examples 1 to 3, the addition of acetonitrile prevented gel clogging of the reactor. Compared to Example 1, in Example 4, reactor A was equipped with acetonitrile but not fully filled. Although this suppressed gel clogging, the molecular weight distribution was wider, and the empty space was prone to crusting, which was not conducive to long-term stable production. In Comparative Example 1, reactor A was not equipped with acetonitrile and was not fully filled, resulting in gel clogging in a short time. In Comparative Example 2, although no acetonitrile was added, full filling resulted in gel clogging at a high water glass concentration (25%).
[0084] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.
[0085] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.
Claims
1. A method for preparing MQ silicone resin, characterized in that, Includes the following steps: Acetonitrile and an acid agent are continuously introduced into the reactor. After the reactor is filled, water glass is continuously introduced. After the water glass is introduced, the flow rates of the water glass, acetonitrile and acid agent are controlled so that the mass ratio of sodium silicate in the water glass, acetonitrile and acid compound in the acid agent introduced per unit time is (8~30):(1~3):(6~36), and a hydrolysis condensation reaction occurs to obtain a polysilicic acid solution. The polysilicic acid solution is subjected to a capping reaction to obtain MQ silicone resin, wherein the weight-average molecular weight of the MQ silicone resin is 10000 Da to 40000 Da.
2. The method for preparing MQ silicone resin according to claim 1, characterized in that, After the water glass is introduced, the pH value of the mixing system in the reactor is controlled to be <3.
3. The method for preparing MQ silicone resin according to claim 1, characterized in that, The average retention time of the water glass, acetonitrile, and acid in the reactor is 0.1 min to 10 min.
4. The method for preparing MQ silicone resin according to any one of claims 1 to 3, characterized in that, The concentration of sodium silicate in the water glass is 10wt%~30wt%.
5. The method for preparing MQ silicone resin according to any one of claims 1 to 3, characterized in that, The concentration of acidic substances in the acid is 8wt%~36wt%.
6. The method for preparing MQ silicone resin according to any one of claims 1 to 3, characterized in that, The acid includes at least one of hydrochloric acid and sulfuric acid.
7. The method for preparing MQ silicone resin according to any one of claims 1 to 3, characterized in that, The temperature of the hydrolysis-condensation reaction is 0℃~40℃.
8. The method for preparing MQ silicone resin according to any one of claims 1 to 3, characterized in that, The polysilicic acid solution, capping agent, alcohol reagent, and solvent are mixed to carry out a capping reaction.
9. The method for preparing MQ silicone resin according to claim 8, characterized in that, Includes at least one of the following features: (1) The end-capping agent is selected from one or more of trimethylchlorosilane, hexamethyldisiloxane, vinyldimethylchlorosilane and divinyltetramethyldisiloxane; (2) The mass of the capping agent accounts for 5 wt% to 20 wt% of the total mass of the polysilicic acid solution, the capping agent, the alcohol reagent, and the solvent; (3) The alcohol reagent is selected from one or more of methanol, ethanol, propanol, butanol, isopropanol and isobutanol; (4) The mass of the alcohol reagent accounts for 10wt% to 25wt% of the total mass of the polysilicic acid solution, the capping agent, the alcohol reagent, and the solvent; (5) The solvent is selected from one or more of benzene, toluene, xylene, hexamethyldisiloxane, C6-C8 straight-chain alkanes and C6-C8 branched-chain alkanes; (6) The mass of the solvent accounts for 15wt% to 50wt% of the total mass of the polysilicic acid solution, the capping agent, the alcohol reagent, and the solvent; (7) The reaction temperature for the end-capping reaction is 40℃~90℃; (8) The reaction time for the end-capping reaction is 1h to 3h.
10. The method for preparing MQ silicone resin according to any one of claims 1 to 3 and 9, characterized in that, Following the end-capping reaction, the following steps are also included: The products obtained from the end-capping reaction are separated into phases, and the resulting organic phase is then subjected to distillation.