A method and apparatus for the continuous production of MQ silicone resins

Abstract

The application discloses a method for continuously producing MQ silicone resin, which comprises the following steps: pumping a sulfuric acid solution and a sodium silicate aqueous solution into a feeding pipeline respectively to obtain reactants; the reactants flow and react in the feeding pipeline; after the reactants pass through the feeding pipeline, a mixed solution of an organic solvent and a silyl ether is added, and a copolymerization reaction occurs under stirring; the gel time of the reactants is controlled by the concentration of the sulfuric acid solution; after the copolymerization reaction is completed, the silyl ether is added to perform an equilibrium reaction; the reactants are left to stand and are separated into an upper organic layer and a lower acid water layer; the organic layer is treated to obtain the MQ silicone resin. The application further discloses a device for continuously producing the MQ silicone resin by implementing the above method. The application realizes continuous production of the MQ silicone resin, controls the molecular weight of the MQ silicone resin, has a relatively simple production process, is low in production cost, and is small in environmental pollution.

Description

Technical Field

[0001] The present invention relates to the field of production of MQ silicone resin, and in particular to a method and device for continuously producing MQ silicone resin. Background Art

[0002] MQ resin is a polysiloxane with a double-layer structure composed of monofunctional and tetrafunctional segments. It exhibits excellent high and low temperature resistance, corrosion resistance, adhesion, and radiation resistance, and is widely used as a surface treatment agent, reinforcement, tackifier, or other additive for polysiloxanes.

[0003] MQ resin can be prepared by various methods, primarily the ethyl silicate method and the water glass method, which use ethyl silicate or its polymerized form and sodium silicate as raw materials, respectively. The ethyl silicate method is widely used due to its ease of operation, high yield, easy structural control, and narrow product molecular weight distribution. However, the process is complex and the raw material costs are high. For example, patent CN201510807184 describes an acid-catalyzed hydrolysis reaction of ethyl orthosilicate, hexamethyldisiloxane, deionized water, and toluene. After the reaction is completed at a specific temperature and time, the reaction is heated to reflux. A base is added to neutralize the reaction to form salt, which is removed by filtration and then distilled to produce MQ silicone resin. Another example, patent CN201910868429 describes an acid-catalyzed hydrolysis reaction of ethyl orthosilicate, hexamethyldisiloxane, tetramethyldivinylsiloxane, ethanol, and toluene. After the reaction is completed at a specific temperature and time, a base is added to neutralize and promote condensation. The reaction is then connected to an oil-water separator, heated to reflux, and distilled to produce MQ silicone resin. However, the M / Q molar ratio is difficult to control by the sodium silicate method, and the molecular weight distribution of the prepared product is relatively wide.

[0004] At present, the preparation of silicone resin by the water glass method still has the following problems: (1) The production process is prone to produce gel and white precipitate, which affects the product yield and performance; (2) The yield is low; (3) The structure of MQ silicone resin is complex and difficult to control; (4) The production process is complicated and the equipment utilization rate is low. Although the industrial production of MQ silicone resin has been achieved in China, the product quality is not very ideal. Therefore, research and improvement of the process of preparing MQ silicone resin using cheap water glass as raw material, further exploration of better process conditions, improvement of yield and reduction of gelation, and simplification of production process will become the research focus of the industrial large-scale production of MQ silicone resin prepared by water glass, which is of great significance to the silicone industry. Summary of the Invention

[0005] In order to overcome the above-mentioned defects and deficiencies of the prior art, the purpose of the present application is to provide a method for continuously producing MQ silicone resin, by controlling the reaction time of the acid catalyst and sodium silicate, the longer the reaction time, the greater the molecular weight of the final product MQ silicone resin, thereby realizing the control of the molecular weight of the MQ silicone resin. In the present application, the control of the reaction time of the acid catalyst and sodium silicate is as follows: first, sulfuric acid is selected as the acid catalyst, the gel time of the reactants of the acid and sodium silicate is prolonged, and a capping agent is added before the reactants gel, the gel time of the reactants of the acid and sodium silicate can be adjusted by the concentration of sulfuric acid, thereby realizing the control of the reaction time of the acid and sodium silicate, and the MQ silicone resin with the required molecular weight range can be obtained by adjusting the different reaction times according to the production needs. In the present application, the control of the reaction time of the acid and sodium silicate can also be realized by adjusting the feeding flow rate and the feeding temperature at the same time.

[0006] Another purpose of the present application is to provide a device for continuously producing MQ silicone resin, which can continuously produce MQ silicone resin and realize the control of the molecular weight of the MQ silicone resin.

[0007] The purpose of the present application is realized by the following technical solutions:

[0008] A method for continuously producing MQ silicone resin, comprising the following steps:

[0009] (1) Pumping the sulfuric acid solution and the aqueous sodium silicate solution into the feeding pipeline respectively to obtain reactants; the reactants flow and react in the feeding pipeline; after the reactants pass through the feeding pipeline, a mixed solution of organic solvent and siloxane is added, and a copolymerization reaction occurs under stirring conditions;

[0010] Among them, the time for the reactants to pass through the feeding pipeline is less than the gel time of the reactants; the gel time is the time from the beginning of the reaction of the reactants to the appearance of gel;

[0011] The gel time of the reactants is controlled by the concentration of the sulfuric acid solution;

[0012] (2) After the copolymerization reaction is completed, a siloxane solvent is added for an equilibrium reaction;

[0013] (3) The reactants obtained in step (2) are allowed to stand and separate into layers, wherein the upper layer is an organic layer and the lower layer is an acid water layer; the organic layer is treated to obtain MQ silicone resin.

[0014] Preferably, in step (3), the reactants obtained in step (2) are allowed to stand and separate into layers, wherein the upper layer is an organic layer and the lower layer is an acid water layer; the organic layer is treated to obtain MQ silicone resin, specifically:

[0015] The organic layer is treated with acid for 2-6 times, neutralized with alkali, dissolved with water, separated to obtain the MQ silicone resin solution; the solvent is evaporated from the solution, condensed and recovered, and then dried to obtain the MQ silicone resin powder;

[0016] The acid water layer is neutralized with alkali, and then distilled to recover the organic solvent and water; the remaining solution is concentrated and dried to recover the treated sodium sulfate salt.

[0017] Preferably, the concentration of the sulfuric acid solution is 30%-50%; the mixture passes through the feeding pipe for 5s-180s.

[0018] Preferably, the gel time of the mixture is also controlled by the feeding flow rate of the sulfuric acid solution and the sodium silicate aqueous solution; the feeding flow rate of the sulfuric acid solution is greater than 20ml / min; the feeding flow rate of the sodium silicate aqueous solution is greater than 20ml / min.

[0019] Preferably, the gel time of the mixture is also controlled by the feeding temperature, which is 20℃-30℃.

[0020] Preferably, in step (1), the sulfuric acid and the sodium silicate aqueous solution are respectively pumped into the pipe to obtain the mixture, specifically:

[0021] First, the sulfuric acid solution is pumped in, and then the sodium silicate aqueous solution is pumped in, mixed by the static mixer to obtain the mixture.

[0022] Preferably, the equilibrium reaction is specifically: refluxing for 2-8 hours, and the reaction temperature is 60-80℃.

[0023] Preferably, the organic solvent is one or more of ethanol, isopropanol, and n-butanol.

[0024] Preferably, the temperature of the copolymerization reaction is 20-40℃.

[0025] Preferably, the time of the copolymerization reaction is 20-30min.

[0026] Preferably, in step (1), the mass ratio of the sulfuric acid solution to the sodium silicate aqueous solution is 1:(1.8-2.4).

[0027] Preferably, in step (1), the mass ratio of the organic solvent to the sodium silicate aqueous solution is: (1-1.5):2.

[0028] Preferably, in step (1), the mass ratio of the sodium silicate aqueous solution to the siloxane is: 6:(1-1.5).

[0029] Preferably, in step (1), the molar ratio of SiO2 / Na2O of the sodium silicate aqueous solution is 3.0-3.5.

[0030] Preferably, the molecular weight of the MQ silicone resin is 3000-20000 g / mol.

[0031] Preferably, the drying is distillation or spray drying.

[0032] An apparatus for continuously producing MQ silicone resin, used to implement the method for continuously producing MQ silicone resin, comprising a first feed pump for pumping a sulfuric acid solution, a second feed pump for pumping a sodium silicate aqueous solution, a third feed pump for pumping a mixed solution of an organic solvent and a silane ether, a fourth feed pump for pumping a silane ether solvent, a first three-way valve, a feed pipeline, a first static mixer, a second three-way valve, a second static mixer, and a reactor;

[0033] The first feed pump is connected to the first inlet of the first three-way valve, the second feed pump is connected to the second inlet of the first three-way valve, the outlet of the first three-way valve is connected to the inlet of the first static mixer, the outlet of the first static mixer is connected to the first inlet of the second three-way valve, the third feed pump is connected to the second inlet of the second three-way valve, the outlet of the second three-way valve is connected to the inlet of the second static mixer, and the outlet of the second static mixer is connected to the reactor; the fourth feed pump is connected to the reactor.

[0034] Preferably, a tongue-shaped insert is provided between the first inlet and the second inlet of the first three-way valve for isolating the first inlet from the second inlet.

[0035] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0036] (1) The method of continuously producing MQ silicone resin of the present invention first uses sulfuric acid as an acid catalyst to extend the gel time of the reactants of acid and sodium silicate. The gel time can be affected by adjusting the sulfuric acid concentration, feed flow rate, and feed temperature as needed. The reaction time of the acid catalyst and sodium silicate can also be adjusted by adjusting the length of the feed pipe. The applicant has found through experiments that the longer the reaction time between the sulfuric acid catalyst and sodium silicate, the greater the molecular weight of the final product, MQ silicone resin. Furthermore, sulfuric acid significantly extends the gel time of the reactants of acid and sodium silicate compared to hydrochloric acid or other acids.

[0037] (2) In the method for continuously producing MQ silicone resin of the present invention, after the copolymerization reaction is completed, silyl ether is added to carry out a reflux reaction, wherein a portion of the silyl ether can continue to react as a capping agent, and the other portion acts as a solvent to improve the extraction effect, so that the synthesized resin is better dissolved in the solvent, the transparency of the MQ silicone resin is improved, the solvent is recyclable, and the post-processing stratification effect is good, the resin powder is easy to form, and the process operability is improved.

[0038] (3) The method for continuously producing MQ silicone resin of the present invention uses a mixture of isopropyl alcohol and silyl ether as a capping agent to obtain MQ silicone resin with a narrow molecular weight distribution.

[0039] (4) In the method for continuously producing MQ silicone resin of the present invention, the concentration of sulfuric acid is preferably 30%-50%, which can prevent pipeline blockage while extending the gel time of the reactants of acid and sodium silicate. At the same time, it does not require higher requirements for the pump and is conducive to material conservation and reduction of waste generation.

[0040] (5) The method for continuously producing MQ silicone resin of the present invention can adjust the concentration of sulfuric acid, feed flow rate, feed temperature, etc. to prepare MQ silicone resin with a molecular weight of 3000-20000 g / mol.

[0041] (6) The acidic water layer of the present invention is neutralized with alkali, and then distilled to recover isopropyl alcohol and water. The isopropyl alcohol and water are recovered by distillation for recycling. The remaining brine is filtered, concentrated and dried to recover the only solid waste sodium sulfate salt, thereby avoiding environmental pollution problems caused by discharge.

[0042] (7) In the method for continuously producing MQ silicone resin of the present invention, the feeding order is preferably: feed A first, then feed B, so as to prevent B from entering the A material pipeline and reacting with A material to cause blockage; the device for continuously producing MQ silicone resin of the present invention is provided with a tongue-shaped insert, which also serves to prevent B from entering the A pipeline at an excessively high speed. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 This is the infrared spectrum of the MQ silicone resin prepared in Example 1 of the present invention.

[0044] Figure 2 This is the infrared spectrum of the MQ silicone resin prepared in Example 2 of the present invention.

[0045] Figure 3 This is the infrared spectrum of the MQ silicone resin prepared in Example 3 of the present invention.

[0046] Figure 4 This is the infrared spectrum of the MQ silicone resin prepared in Example 4 of the present invention.

[0047] Figure 5 This is the infrared spectrum of the MQ silicone resin prepared in Example 5 of the present invention.

[0048] Figure 6 This is the infrared spectrum of the MQ silicone resin prepared in Example 8 of the present invention.

[0049] Figure 7This is a schematic structural diagram of an apparatus for continuously producing MQ silicone resin according to Example 9 of the present invention. DETAILED DESCRIPTION

[0050] The present invention will be further described in detail below with reference to the examples, but the embodiments of the present invention are not limited thereto.

[0051] Example 1

[0052] The method for continuously producing MQ silicone resin in this embodiment is:

[0053] First, prepare material A: 50% sulfuric acid solution (2 parts), material B: sodium silicate aqueous solution (2.4 parts water glass solution + 2.4 parts water), material C: mixed solution (0.8 parts MM and 2.4 parts isopropanol), and material D (4 parts MM); under the condition of meeting the above ratios, material A of this embodiment can be selected from 200-1600g; material B can be selected from 480-2400g; and material C can be selected from 320-1620g.

[0054] First, test the stability of each pump with water, then pump in material A and material B in turn. After they stay in the pipeline to react for 20 seconds, material C is added and mixed and reacted in the reactor at room temperature for 30 minutes. Then, material D is added and the temperature is raised to 65°C and balanced with reflux reaction for 3 hours. After standing and separating, the upper layer is the organic oil phase and the lower layer is the acid water layer.

[0055] After the lower acidic water layer is discharged, it is first neutralized with alkali to neutrality, and then the isopropyl alcohol and water are recovered by distillation. The remaining solution is concentrated and dried before being recovered and processed into sodium sulfate salt;

[0056] The upper oil phase is treated with concentrated sulfuric acid 2-6 times, then neutralized with alkali solution to a weak acidity, and solid sodium carbonate to a neutral to weak alkalinity. After dissolving in water, the aqueous phase is separated to obtain a resin mother liquor. The solvent is evaporated from the solution, and the distillation process is condensed and recovered (the solvent can be reused). The white resin powder is dried.

[0057] In this embodiment, some process parameters are set as follows:

[0058] A material feed flow rate: can be selected from 30-99ml / min

[0059] B material feed flow rate: can be selected from 30-99ml / min

[0060] C material feed flow rate: can be selected from 30-99ml / min

[0061] D material feed flow rate: can be selected from 30-99ml / min

[0062] Feed temperature of sulfuric acid and sodium silicate aqueous solution: 30℃.

[0063] The GPC (Gel Permeation Chromatography) test results of the MQ silicone resin prepared in this example are as follows:

[0064] Number average molecular weight M N =2894g / mol, weight average molecular weight M w =5560g / mol, M W / M N =1.92.

[0065] The infrared test results of the MQ silicone resin prepared in this embodiment are as follows: Figure 1 As shown:

[0066] There is a CH peak at 2960cm-1, Si-CH3 peaks at 1253cm-1, 843cm-1, and 756cm-1, a Si-O-Si peak at 1077cm-1, and a Si-OH peak at 3565cm-1.

[0067] Example 2

[0068] In this embodiment, except that the time for the reactants to pass through the feed pipe is 5 seconds, the material ratio and other process parameters are the same as those in Example 1, and MQ silicone resin can be continuously produced.

[0069] The GPC (Gel Permeation Chromatography) test results of the MQ silicone resin prepared in this example are as follows:

[0070] M N =2265g / mol, M W =3163g / mol, M W / M N =1.396.

[0071] The infrared test results of the MQ silicone resin prepared in this embodiment are as follows: Figure 2 shown.

[0072] Example 3

[0073] In this embodiment, except that the time for the reactants to pass through the feed pipe is 10 seconds, the material ratio and other process parameters are the same as those in Example 1, and MQ silicone resin can be continuously produced.

[0074] The GPC (Gel Permeation Chromatography) test results of the MQ silicone resin prepared in this example are as follows:

[0075] M N =2726 g / mol, M W=5082g / mol, M W / M N =1.864.

[0076] The infrared test results of the MQ silicone resin prepared in this embodiment are as follows: Figure 3 shown.

[0077] Example 4

[0078] In this embodiment, except that the time for the reactants to pass through the feed pipe is 60 seconds, the material ratio and other process parameters are the same as those in Example 1, and MQ silicone resin can be continuously produced.

[0079] The GPC (Gel Permeation Chromatography) test results of the MQ silicone resin prepared in this example are as follows:

[0080] M N =3254 g / mol, M W =6519 g / mol, M W / M N =2.000.

[0081] The infrared test results of the MQ silicone resin prepared in this embodiment are as follows: Figure 4 shown.

[0082] Example 5

[0083] In this embodiment, except that the time for the reactants to pass through the feed pipe is 75 seconds, the material ratio and other process parameters are the same as those in Example 1, and MQ silicone resin can be continuously produced.

[0084] The GPC (Gel Permeation Chromatography) test results of the MQ silicone resin prepared in this example are as follows:

[0085] M N =3617 g / mol, M W =7250g / mol, M W / M N =2.004.

[0086] The infrared test results of the MQ silicone resin prepared in this embodiment are as follows: Figure 5 shown.

[0087] Example 6

[0088] In this embodiment, except that the concentration of material A is reduced to 44%, the material ratio and other process parameters are the same as those in embodiment 3, and MQ silicone resin can be continuously produced.

[0089] The GPC (Gel Permeation Chromatography) test results of the MQ silicone resin prepared in this example are as follows:

[0090] M N =2289 / mol, M W =4849 g / mol, M W / M N =2.054.

[0091] Example 7

[0092] In this embodiment, except that the concentration of material A is reduced to 37%, the material ratio and other process parameters are the same as those in Example 3, and MQ silicone resin can be continuously produced.

[0093] The GPC (Gel Permeation Chromatography) test results of the MQ silicone resin prepared in this example are as follows:

[0094] M N =2378 / mol, M W =3646 g / mol, M W / M N =1.731.

[0095] Example 8

[0096] This example was scaled up (150 times) with the same ratio as Example 3 and the flow rates of the corresponding pumps were adjusted to continuously produce MQ silicone resin. GPC analysis showed Mn = 2296 g / mol, Mw = 3313 g / mol, and Mw / Mn = 1.566.

[0097] In this embodiment, some process parameters are set as follows:

[0098] A material feed flow rate: can be selected between 1000-2000ml / min

[0099] B material feed flow rate: can be selected between 2000-3000ml / min

[0100] C material feed flow rate: can be selected between 2000-3000ml / min

[0101] D material feed flow rate: can be selected between 2000-3000ml / min

[0102] The infrared test results of the MQ silicone resin prepared in this embodiment are as follows: Figure 6 shown.

[0103] Comparative Example 1

[0104] In this comparative example, except that the concentration of material A is increased to 60%, the material ratio and other process parameters are the same as those in Example 1.

[0105] The result is that as soon as material A and material B come into contact, they react violently to form a gel solid, which blocks the pipeline and prevents production.

[0106] Comparative Example 2

[0107] In this comparative example, except that the feed temperature of material A is 40-60° C., the material ratio and other process parameters are the same as those in Example 1.

[0108] As a result, as soon as material A and material B came into contact, they reacted violently to form a gel solid, which blocked the pipeline and prevented production.

[0109] Analysis and discussion:

[0110] As can be seen from Examples 1-8 and Comparative Examples 1-2, using a silane ether solvent instead of toluene can produce a methyl MQ silicone resin with a narrow molecular weight distribution. At the same time, by changing the concentration of the sulfuric acid solution and the reaction time of the sodium silicate aqueous solution and sulfuric acid, the molecular weight of the obtained methyl MQ resin will vary significantly:

[0111] 1. Under the condition of the same concentration of sulfuric acid solution, as the reaction time of acid and sodium silicate solution increases, the molecular weight of the generated silicone resin will also increase; but the reaction time needs to be controlled, otherwise it will cause gel blockage or affect subsequent operations and synthesis effects and efficiency;

[0112] 2. As the concentration of sulfuric acid solution increases, the molecular weight of the generated silicone resin will also increase accordingly; but the concentration cannot be too high, preferably 30-50%.

[0113] 3. The temperature of the sulfuric acid solution should not be too high, otherwise it will cause gel to block the pipeline, preferably at 20-30℃.

[0114] Comparative Example 3

[0115] This comparative example compares the effect of the concentration of sulfuric acid solution of material A on the gel time (the time from the start of the reaction of material A and material B to the appearance of gel), and also compares the changes in gel time when material A is treated with sulfuric acid and hydrochloric acid respectively:

[0116] Under the condition of machine stirring (speed of 200-300 rpm), the gel time was tested. The results are shown in Table 1:

[0117] Table 1

[0118]

[0119] From the experiment we know that:

[0120] 1. Under machine stirring, the higher the acid concentration of material A, the shorter the gelling time. If the concentration of material A is too low, more water will be required for dilution with the same amount of acid, resulting in more wastewater. Therefore, the concentration of material A is an important factor to consider. When feeding through a pipeline, if the acid concentration of material A exceeds 50%, the feed will become clogged (the flow effect of the pipeline is not as good as that of machine stirring). In addition, without stirring or manually stirring, materials A and B will gel as soon as they come into contact. Therefore, the flow rate of the pipeline is also a factor affecting the gelling time. The gelling time can be controlled by adjusting the feed flow rate of materials A and B.

[0121] 2. When hydrochloric acid is used for material A, the gelation time is greatly shortened compared with H2SO4 of the same concentration.

[0122] Comparative Example 4

[0123] This comparative example compares the effects of using different solvents for material D on the entire resin synthesis process and product, as shown in Table 2. The experiment shows that using pure MM in excess in material D allows a portion of it to continue reacting as a capping agent, while the remaining portion acts as a solvent to enhance the extraction effect, allowing the synthesized resin to dissolve better in the solvent, improving the transparency of the MQ silicone resin, making the solvent recyclable, and achieving good post-processing delamination and easier resin powder molding, thereby improving process operability.

[0124] Table 2

[0125]

[0126] Example 9

[0127] Figure 7 It is an example of an apparatus for realizing the method for continuously producing MQ silicone resin of the present invention.

[0128] like Figure 7 As shown, the apparatus for continuously producing MQ silicone resin includes a feed pump 1 for pumping sulfuric acid solution, a feed pump 2 for pumping sodium silicate aqueous solution, a feed pump 3 for pumping a mixed solution of organic solvent and silane ether, a feed pump 4 for pumping silane ether solvent, a three-way valve 5, a feed pipeline 6, a static mixer 7, a three-way valve 8, a static mixer 9 and a reactor 10;

[0129] The feed pump 1 (connected with the A material high-level tank 11) is connected to the first inlet of the three-way valve 5, the feed pump 2 (connected with the B material high-level tank 21) is connected to the second inlet of the three-way valve 5, the outlet of the three-way valve 5 is connected to the inlet of the static mixer 7, the outlet of the static mixer 7 is connected to the first inlet of the three-way valve 8, the feed pump 3 (connected with the C material high-level tank 31) is connected to the second inlet of the three-way valve 8, the outlet of the three-way valve 8 is connected to the inlet of the second static mixer 9, and the outlet of the static mixer 9 is connected to the reactor 10; the feed pump 4 (connected with the D material high-level tank 41) is connected to the reactor 10; wherein, a tongue-shaped insert 12 is provided between the first inlet and the second inlet of the three-way valve 5, which is used to isolate the first inlet and the second inlet to prevent the B material from entering the A material pipeline and reacting with the A material to cause blockage.

[0130] The feed pipe in this embodiment can be a polytetrafluoroethylene tube.

[0131] The process of continuously producing MQ silicone resin using the device of this embodiment is as follows:

[0132] First, add material A, then add material B (to prevent material B from entering the material A pipeline and reacting with material A to cause blockage), mix them in a static mixer, and then control the reaction time of the two through the feed pipeline. Then, mix them with material C in the static mixer and enter the reactor to react. Finally, add material D for a balanced reaction.

[0133] The device of this embodiment can be a device with a capacity of 3-10L, wherein material A can be selected from 200-1600g; material B can be selected from 480-2400g; material C can be selected from 320-1620g; the applicable feed flow rate of materials A, B, and C is 20-99ml / min.

[0134] The device of this embodiment can be a device with a capacity of 300-500L, wherein material A can be selected from 40-90kg; material B can be selected from 72-120kg; material C can be selected from 50-91kg; the applicable feed flow rate of materials A, B, and C is 1-6L / min.

[0135] The device of this embodiment can be a device for mass production with a capacity of more than 500 L, and the feed flow rate of materials A, B, and C is applicable to 10-30 L / min.

[0136] The length of the pipeline determines the reaction time between materials A and B, which can control the molecular weight of the resin. When designing the pipeline, the time it takes for the reactants to pass through the feed pipe should be less than their gel time (the gel time is the time from the start of the reaction to the formation of gel). To obtain MQ silicone resin with a narrow molecular weight distribution, flow rate control not only requires ensuring that the time it takes for the reactants to pass through the feed pipe is less than the gel time, but also requires controlling the feed time of materials A, B, and C, preferably to less than 30 minutes.

[0137] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be considered as equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. A method for continuously producing MQ silicone resin, characterized in that, The following steps are involved: (1) respectively pumping a sulfuric acid solution and a sodium silicate aqueous solution into a feed pipe to obtain reactants; the reactants flow and react in the feed pipe; after the reactants pass through the feed pipe, a mixed solution of an organic solvent and a silane ether is added, and a copolymerization reaction occurs under stirring conditions; The time for the reactant to pass through the feed pipe is less than the gel time of the reactant; the gel time is the time from the start of the reaction to the appearance of gel; The gel time of the reactants is controlled by the concentration of the sulfuric acid solution; The concentration of the sulfuric acid solution is 30%-50%; the time for the mixed material to pass through the feed pipe is 5s-180s; the feed flow rate of the sulfuric acid solution is greater than 20ml / min; the feed flow rate of the sodium silicate aqueous solution is greater than 20ml / min; the temperature of the copolymerization reaction is 20-40°C; the time of the copolymerization reaction is 20-30min; the feed temperature is 20°C-30°C; (2) After the copolymerization reaction is completed, silyl ether is added to carry out equilibrium reaction; (3) The reactant obtained in step (2) is allowed to stand for separation, wherein the upper layer is an organic layer and the lower layer is an acid-water layer; the organic layer is treated to obtain MQ silicone resin.

2. The method for continuously producing MQ silicone resin according to claim 1, wherein Step (3) The reactant obtained in step (2) is allowed to stand for stratification, wherein the upper layer is an organic layer and the lower layer is an acid-water layer; the organic layer is treated to obtain MQ silicone resin, specifically: The organic layer is treated with acid 2-6 times, neutralized with alkali, dissolved with water, and separated to obtain an MQ silicone resin solution; the solvent is evaporated from the solution, condensed and recovered, and then dried to obtain the MQ silicone resin powder; The acidic aqueous layer is neutralized with alkali and then distilled to recover the organic solvent and water; the remaining solution is concentrated and dried to recover the sodium sulfate salt.

3. The method for continuously producing MQ silicone resin according to claim 1, wherein In step (1), sulfuric acid and sodium silicate aqueous solution are pumped into the pipeline respectively to obtain a mixed material, specifically: First, a sulfuric acid solution is pumped in, and then a sodium silicate aqueous solution is pumped in, and the mixture is mixed in a static mixer to obtain a mixed material.

4. The method for continuously producing MQ silicone resin according to claim 1, characterized in that The equilibrium reaction is specifically: reflux reaction for 2-8 hours, and the reaction temperature is 60-80°C.

5. A device for continuously producing MQ silicone resin, for implementing the method for continuously producing MQ silicone resin according to any one of claims 1 to 4, characterized in that: The system comprises a first feed pump for pumping a sulfuric acid solution, a second feed pump for pumping a sodium silicate aqueous solution, a third feed pump for pumping a mixed solution of an organic solvent and a silicon ether, a fourth feed pump for pumping a silicon ether solvent, a first three-way valve, a feed pipeline, a first static mixer, a second three-way valve, a second static mixer and a reactor; The first feed pump is connected to the first inlet of the first three-way valve, the second feed pump is connected to the second inlet of the first three-way valve, the outlet of the first three-way valve is connected to the inlet of the first static mixer, the outlet of the first static mixer is connected to the first inlet of the second three-way valve, the third feed pump is connected to the second inlet of the second three-way valve, the outlet of the second three-way valve is connected to the inlet of the second static mixer, and the outlet of the second static mixer is connected to the reactor; the fourth feed pump is connected to the reactor.

6. The device for continuously producing MQ silicone resin according to claim 5, characterized in that A tongue-shaped insert is provided between the first inlet and the second inlet of the first three-way valve, for isolating the first inlet from the second inlet.

Images