Method for preparing methyl MQ type silicon resin and applying solvent wastewater

Abstract

The invention relates to the field of organic silicon, in particular to a method for preparing methyl MQ type silicon resin and applying solvent wastewater. The method comprises the following steps: 1) sequentially adding a hydrochloric acid aqueous solution, a silicate aqueous solution, a mixed solvent and an organic silicon methyl end-capping reagent, stirring and reacting; or sequentially adding the hydrochloric acid aqueous solution, the silicate aqueous solution, the organic silicon methyl end-capping reagent and the mixed solvent, stirring and reacting; 2) standing and layering after the reaction to obtain an organic phase and a water phase; (3) blowing inert gas into the organic phase in the step (2) to evaporate out the first solvent, and carrying out polycondensation to obtain liquid or solid MQ type silicon resin; the first solvent is used in the step 1); and distilling the water phase obtained in the step 2) to recover the second solvent, and applying the second solvent to the step 1). The environment-friendly problems that the amount of waste water is large, the reaction is difficult to control, gelation is easy to occur, and the use amount of a solvent is large when MQ silicon resin is prepared through a water glass method are solved.

Description

Technical Field

[0001] The invention relates to the field of organic silicon, and in particular to a method for preparing a methyl MQ type silicone resin and applying solvent wastewater. Background Art

[0002] Methyl MQ silicone resin is a new type of organic silicon material with a three-dimensional spherical polymerized organic siloxane with a three-dimensional (non-linear) double-layer structure composed of Si-O bonds as the skeleton. Its structural formula is as follows: [(CH3)3SiO 1 / 2 ] a [SiO 4 / 2 ] b , where [(CH3)3SiO 1 / 2 ] is M, [SiO 4 / 2 ] is Q. Depending on the M:Q value, its performance, specifications and applications are different.

[0003] Methyl MQ silicone resin has the following excellent properties: 1. Excellent heat resistance and low temperature resistance, can be used in a temperature environment of -60℃ to +300℃. 2. Good film-forming property, moderate flexibility, aging resistance, and UV resistance. 3. Very good water repellency. 4. Good adhesion performance. 5. Excellent isolation performance, and long-lasting durability, it is a semi-permanent release agent.

[0004] It has a wide range of uses: 1. It is used to make high-temperature resistant coatings for insulation, jointing, and sealing of H-class motors. 2. It is used to paint and protect the surfaces of important items exposed to the outdoors (such as cultural relics, billboards, etc.), which can resist corrosion, weathering, and fading. 3. It is used to make various waterproof coatings. 4. It is used in the daily chemical industry to make: an ideal material for lipsticks, cosmetics, etc. 5. It can improve and adjust the peeling force of pressure-sensitive adhesives, so it can be used as a peeling force regulator for making pressure-sensitive tapes, etc. 6. It can be used to make release agents for a variety of materials. 7. It is suitable as a tackifier for bonding inorganic and organic materials. 8. It is used as a reinforcing agent in silicone rubber. The reinforced silicone rubber is colorless and transparent with high mechanical strength. 9. Other unfinished and to-be-developed applications.

[0005] There are two conventional methods for preparing methyl MQ type silicone resin: one is the silicate method and the other is the ethyl ester water glass method.

[0006] US Patent No. 4,707,531 describes that hexamethyldisiloxane is mixed with water and then ethyl silicate is added. The reaction mixture is statically separated and the lower organic layer is washed with water, concentrated and filtered to obtain the target organosilicon MQ type silicone resin.

[0007] Chinese patent CN106750304 describes that polyethyl orthosilicate and hexamethyldisiloxane are hydrolyzed under the catalysis of sulfuric acid. After the reaction is completed at a certain temperature and time, alkali is added to neutralize and generate salt. The salt is removed by filtration using the silicate method.

[0008] Dandt et al. of Dow Corning proposed to prepare copolymerized dioxygen resin and its preparation method by hydrolyzing and condensing sodium silicate (Q group raw material) with trimethylchlorosilane or hexamethyldisiloxane (Q group raw material) at low temperature to form a low molecular weight methyl MQ type silicone resin, and then obtain the methyl MQ type silicone resin that meets the application conditions through layering, solvent extraction, distilled water washing, and distillation concentration by water glass method.

[0009] It has been reported that concentrated hydrochloric acid and isopropyl alcohol are mixed and pre-cooled, and a mixture of water glass and water is quickly added and kept below 20 degrees for 5 minutes. Isopropyl alcohol, hexamethyldisiloxane, xylene, and trimethylchlorosilane are then added in sequence, heated to reflux for 2 hours, propylene oxide is added in layers to neutralize HCl, and finally isopropyl alcohol and toluene are used to adjust the resin solid content to 60%. The water glass method is also used.

[0010] Silicate method: Advantages: easy preparation, narrow molecular weight distribution of products, less wastewater. Disadvantages: high cost, and due to the large number of alkoxy residues, the pressure-sensitive adhesive made by this method has poor temperature resistance, low peeling force, and limited application.

[0011] Water glass method: Advantages: simple process, low raw material cost, high peeling force of the prepared pressure-sensitive adhesive, and good temperature resistance. High industrial production added value. Excellent performance leads to its wider application. Disadvantages: large amount of wastewater and waste solvent. The fatal disadvantage is that trimethylchlorosilane hydrolyzes quickly, the reaction is difficult to control, gel is easily produced, and HCl is produced in the later stage of the reaction, which is very corrosive. HCl also catalyzes the hydrolysis and condensation process, and the amount of reaction catalyst is difficult to control. Later research has basically replaced it with hexamethyldisiloxane, and it has been improved on this basis, but the progress is not great. The main factors affecting the raw materials, feed amount, feed sequence, catalyst, solvent and other process conditions have been studied and improved. Summary of the invention

[0012] In view of the above-mentioned shortcomings of the prior art, the purpose of the present invention is to provide a method for preparing methyl MQ type silicone resin and applying solvent wastewater, which is used to solve the environmental problems of preparing MQ type silicone resin by the water glass method, such as large amount of wastewater, difficult reaction control, easy gelation, and large amount of solvent used.

[0013] To achieve the above-mentioned purpose and other related purposes, the present invention provides a method for preparing a methyl MQ type silicone resin and applying solvent wastewater, the method comprising:

[0014] 1) adding hydrochloric acid aqueous solution, silicate aqueous solution, mixed solvent, and organosilicon methyl end-capping agent in sequence, stirring and reacting; or adding hydrochloric acid aqueous solution, silicate aqueous solution, organosilicon methyl end-capping agent, and mixed solvent in sequence, stirring and reacting;

[0015] 2) After the reaction, the mixture was allowed to stand for stratification to obtain an organic phase and an aqueous phase;

[0016] 3) blowing an inert gas into the organic phase in step 2) to evaporate the first solvent, polycondensing to obtain a liquid or solid MQ silicone resin; and using the first solvent in step 1);

[0017] 4) distilling the water phase obtained in step 2) to recover the second solvent, and using the second solvent in step 1).

[0018] The purpose of the present invention is to prepare methyl MQ type silicone resin by the water glass method with relatively cheap raw materials, which has the following advantages:

[0019] 1. Use cheaper water glass and cheaper capping agent trimethylchlorosilane;

[0020] 2. Adjust the feeding sequence and feeding amount, improve the water glass process, so that the preparation of MQ can reach higher product specifications; the molecular weight distribution and viscosity of MQ silicone resin meet the requirements;

[0021] 3. Develop solvent application and wastewater recycling processes to reduce solvent consumption and the discharge of three wastes.

[0022] 4. The optimized process meets the requirements of low cost of raw and auxiliary materials and low emission of three wastes, and is a competitive industrial production process. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 Shown is a process flow chart for the preparation of methyl MQ type silicone resin. DETAILED DESCRIPTION

[0024] The following is a detailed description of the implementation of a method for preparing a methyl MQ silicone resin and applying solvent wastewater of the present application.

[0025] "Scope" disclosed in the present application is limited in the form of lower limit and upper limit, and a given range is limited by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of a special range. The scope limited in this way can be including end values ​​or not including end values, and can be arbitrarily combined, that is, any lower limit can be combined with any upper limit to form a scope. For example, if the scope of 60-120 and 80-110 is listed for a specific parameter, it is understood that the scope of 60-110 and 80-120 is also expected. In addition, if the minimum range values ​​1 and 2 are listed, and if the maximum range values ​​3, 4 and 5 are listed, the following scope can be all expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In the present application, unless otherwise specified, the numerical range "ab" represents the abbreviation of any real number combination between a and b, wherein a and b are real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" are listed in this document, and "0-5" is just an abbreviation of these numerical combinations. In addition, when a parameter is expressed as an integer ≥ 2, it is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0026] The methods for preparing MQ silicone resin that have been reported so far, the orthosilicate route, has high cost for preparing MQ silicone resin due to the expensive raw materials, and the product lacks competitiveness. The water glass route has the advantage of low cost. The inventors of the present invention have conducted in-depth research and provided a process that can be applied to organic solvents, by-product hexamethyldisiloxane and acid water, solving the problem of the discharge of the three wastes. Cheaper raw materials have been selected. The feeding steps have been optimized, the process is simpler, the post-processing is simple and easy, environmentally friendly, the yield is high, the viscosity fluctuation of the product is small, and it is suitable for industrialization. On this basis, this application has been completed.

[0027] [Preparation of methyl MQ type silicone resin and method for applying solvent wastewater]

[0028] The present invention provides a method for preparing a methyl MQ type silicone resin and applying solvent wastewater, the method comprising:

[0029] 1) adding hydrochloric acid aqueous solution, silicate aqueous solution, mixed solvent, and organosilicon methyl end-capping agent in sequence, stirring and reacting; or adding hydrochloric acid aqueous solution, silicate aqueous solution, organosilicon methyl end-capping agent, and mixed solvent in sequence, stirring and reacting;

[0030] 2) After the reaction, the mixture was allowed to stand for separation to obtain an organic phase and an aqueous phase;

[0031] 3) blowing an inert gas into the organic phase in step 2) to evaporate the first solvent, polycondensing to obtain a liquid or solid MQ silicone resin; and using the first solvent in step 1);

[0032] 4) distilling the water phase obtained in step 2) to recover the second solvent, and using the second solvent in step 1).

[0033] In step 1) of the present invention, in order to obtain the best quality product, the present invention studies the feeding order and feeding temperature of the reaction materials, as shown in Table 1. For the convenience of description, the hydrochloric acid aqueous solution is defined as material A, the silicate aqueous solution is defined as material B, the mixed solvent is defined as material C, and the organosilicon methyl end-capping agent is defined as material D.

[0034] Table 1

[0035] experiment All feeding temperatures / ℃ Feeding order Experimental phenomenon 1 10 A / B / C / D normal 2 10 A / B / D / C normal 3 10 A / B / D / C Gel Severe 4 10 A / C / D / B Gel Severe 5 10 A / D / B / C Silicone resin is turbid and has a slightly smaller molecular weight 6 10 A / D / C / B Gel Severe

[0036] As can be seen from Table 1, in order to prevent the gel problem, the feeding sequence of the present invention must follow a certain feeding sequence. Among them, the order of materials A / B / C / D and materials A / B / D / C is the best feeding sequence. That is, hydrochloric acid aqueous solution, silicate aqueous solution, mixed solvent, and organosilicon methyl end-capping agent are added in sequence and stirred and reacted; or, hydrochloric acid aqueous solution, silicate aqueous solution, organosilicon methyl end-capping agent, and mixed solvent are added in sequence and stirred and reacted. It is further preferred to use the A / B / C / D process.

[0037] In step 1) of the present invention, the concentration of the hydrochloric acid aqueous solution is 10-30%. Optionally, the concentration of the hydrochloric acid aqueous solution is, for example, 10-15% or 15-30%. Preferably, the concentration of the hydrochloric acid aqueous solution is, for example, 10-15%. Within the aforementioned concentration range, low-concentration hydrochloric acid is used to facilitate the use of acid water, that is, the use of by-product hydrochloric acid can be achieved. Hydrochloric acid is used as a hydrolysis catalyst, and catalysts such as sulfuric acid can also be used. Because the by-product has hydrochloric acid, hydrochloric acid is preferably selected for the convenience of recycling.

[0038] The concentration of the hydrochloric acid aqueous solution is 10-30%. For example, high-concentration hydrochloric acid and water can be prepared in proportion.

[0039] In step 1) of the present invention, the modulus of the silicate aqueous solution (water glass) is 3.0-3.6. The concentration of the silicate aqueous solution is 16-18%, for example, 36.5% silicate aqueous solution and water can be mixed in a certain proportion, cooled to a certain temperature, and then used.

[0040] Optionally, the modulus of the silicate aqueous solution is 3.0-3.3 or 3.3-3.6. Preferably, the modulus of the silicate aqueous solution is 3.0-3.3.

[0041] The reaction in step 1) of the present invention must be carried out in a mixed solvent. The mixed solvent is a non-polar solvent and an alcohol mixed solvent.

[0042] Optionally, the non-polar solvent is selected from one or more of toluene, xylene, petroleum ether, dimethyl carbonate (DMC) and the like.

[0043] Optionally, the alcohol solvent is selected from one or more of methanol, ethanol, isopropanol, etc. Preferably, the alcohol solvent is isopropanol.

[0044] Further optionally, the mixed solvent is selected from a combination of a toluene-methanol mixed solution, a toluene-ethanol mixed solution, a toluene-isopropanol mixed solution, a xylene-methanol mixed solution, a xylene-ethanol mixed solution, a xylene-isopropanol mixed solution, and the like.

[0045] Optionally, the mass ratio of the alcohol to the non-polar solvent is 1:1-3:2. For example, the mass ratio of the alcohol to the non-polar solvent in the reaction system is 1:1, 3:2, etc.

[0046] In step 1) of the present invention, the organosilicon methyl end-capping agent is selected from trimethylchlorosilane and / or hexamethyldisiloxane. Optionally, the organosilicon methyl end-capping agent is trimethylchlorosilane. Trimethylchlorosilane is cheaper.

[0047] In step 1), the mass ratio of the hydrochloric acid aqueous solution, the silicate aqueous solution, the mixed solvent, and the organosilicon methyl end-capping agent is 1:2.4:1.6:(0.39-0.62). Optionally, the mass ratio of the hydrochloric acid aqueous solution, the silicate aqueous solution, the mixed solvent, and the organosilicon methyl end-capping agent can be, for example, 1:2.4:1.6:(0.39-0.50) or 1:2.4:1.6:(0.50-0.62), etc. Among them, the amount of hydrochloric acid used in the present invention must not be less than the amount of hydrochloric acid consumed by the sodium oxide of the sodium silicate, otherwise, the experiment is likely to fail and produce a large amount of solids.

[0048] In step 1) of the present invention, the hydrochloric acid aqueous solution, silicate aqueous solution, mixed solvent, and organosilicon methyl end-capping agent all need to be cooled before feeding. In order to obtain the best product quality, the present invention has studied the feeding temperature of the reaction materials. As shown in Table 2:

[0049] Table 2

[0050] experiment Feeding order All feeding temperatures / ℃ Experimental phenomenon 1 A / B / C / D 5 normal 2 A / B / C / D 10 normal 3 A / B / C / D 15 Small amount of gel 4 A / B / C / D 20 Gel Severe 5 A / B / C / D 25 Gel Severe 6 A / B / C / D 30 Gel Severe

[0051] It can be seen from Table 2 that under certain conditions of feed amount and sequence, the reaction temperature can be controlled below 15 degrees. That is, the hydrochloric acid aqueous solution, silicate aqueous solution, mixed solvent, and organosilicon methyl end-capping agent must be cooled to 0-15 degrees before feeding. Due to the extremely fast reaction speed, gel will appear if the temperature is not controlled within the above range.

[0052] In step 1) of the present invention, each material is added in sequence under stirring conditions; wherein the stirring speed is 300-350R / min. The present invention must adopt high-speed stirring. If the stirring speed is lower than the above (e.g., lower than 300R / min), when adding the materials silicate aqueous solution, mixed solvent, and organosilicon methyl end-capping agent, there may be a large number of solid gel particles or overall gel.

[0053] In step 1) of the present invention, when adding materials such as silicate aqueous solution, mixed solvent and organosilicon methyl end-capping agent, the addition time needs to be controlled. If the drop rate is fast, more gel particles will be formed, which will affect the yield and resin quality. If the drop rate is too slow, the weight average molecular weight of the silicone resin is large and the molecular weight distribution is wide. The drop rate can be controlled according to product requirements. In some embodiments, the drop feeding time of each material is 3-5 minutes.

[0054] In order to obtain the best quality silicone resin, the present invention studied the hydrolysis time of the reaction material water glass. As shown in Table 3:

[0055] Table 3

[0056]

[0057] Note: The feeding time is the time taken for all materials to be added.

[0058] The present invention finds that when the feeding time is very short or very long, the viscosity will be very high. The optimal feeding time is 5-10 minutes, and the viscosity (or molecular weight) of the silicone resin can also be controlled by the reaction time.

[0059] In step 1) of the present invention, stirring is continued for 10-30 minutes after each material is added. Optionally, stirring is continued for 10-20 minutes, 20-30 minutes. Further, the system is naturally heated to 28-30° C., and stirring is continued for 10-30 minutes at this temperature.

[0060] In step 1) of the present invention, the reaction temperature is 40-70°C. Optionally, the reaction temperature is 40-60°C, 60-70°C, 40-50°C, 50-60°C, 60-70°C. The reaction temperature needs to be strictly controlled. If the temperature is too high, gelation will occur. The reaction time is 1-3 hours. Optionally, the reaction time is 1-2 hours or 2-3 hours.

[0061] In the method for preparing methyl MQ type silicone resin and utilizing solvent wastewater provided by the present invention, step 2) is to stand and separate the layers after the reaction to obtain an organic phase and an aqueous phase.

[0062] In the method for preparing methyl MQ silicone resin and using solvent wastewater provided by the present invention, step 3) is to blow inert gas into the organic phase in step 2) to evaporate the solvent, and obtain liquid or solid MQ silicone resin by polycondensation; and the first solvent is used in step 1).

[0063] In step 3) of the present invention, the purpose of bubbling inert gas is to reduce the traditional alkali washing and water washing steps, the operation is simple, and the discharge of wastewater is greatly reduced. Further, the inert gas is selected from one of nitrogen, helium, argon, etc. Preferably, during the recovery process of the organic solvent, HCl is driven out by nitrogen bottom bubbling. Experiments have found that the use of nitrogen is very effective and can achieve an organic phase pH of 6-7. Reduce the alkali washing and water washing steps of acid water, simplify the operation, and reduce wastewater discharge. The recovered solvent is analyzed. The first solvent is a non-polar solvent containing an alcohol solvent. The ratio of the non-polar solvent to the alcohol solvent in the system can be obtained. For example, in some embodiments, the mass ratio of the non-polar solvent to the alcohol solvent is 1.2-2.4. Apply the mixed solvent of material C in step 2) in proportion, and produce hexamethyldisiloxane as a by-product. Calculate the amount of input applied to the next batch, and add solvent and trimethylchlorosilane or hexamethyldisiloxane according to the proportion.

[0064] In the method for preparing methyl MQ type silicone resin and reusing solvent wastewater provided by the present invention, step 4) is to distill the water phase obtained in step 2) to recover the second solvent, and reusing the second solvent in step 1).

[0065] In step 4) of the present invention, the front fraction of the distillation is the second solvent, and the second solvent is an alcohol aqueous solution with a water content of 15-20% and a pH value of <1, which has little effect on the reaction and can be directly applied.

[0066] In step 4) of the present invention, the intermediate fraction of the distillation is 0.25-0.5% hydrochloric acid, which is used to prepare or dilute the silicate aqueous solution after adding alkali for neutralization; and is applied to the silicate aqueous solution in step 1).

[0067] In step 4) of the present invention, when the distillation top temperature reaches a certain level, the distillation is suspended, the temperature is lowered to room temperature, and filter press is performed to obtain a 10-12% hydrochloric acid aqueous solution containing saturated sodium chloride, which is then used in the hydrochloric acid aqueous solution in step 1).

[0068] In the step 4) of the present invention, the acid water is recovered, the waste water utilization rate reaches more than 80%, and the remaining solid waste is sodium chloride solid containing wet hydrogen chloride.

[0069] In a specific embodiment, the acid water is recovered in the present invention, the reaction solvent is an alcohol solvent such as ethanol or isopropanol, the solvent is recovered at normal pressure, and the front fraction can recover 75-80% ethanol / isopropanol, which can be applied to the next batch. If methanol is used, the recovery rate is higher.

[0070] In order to realize the application of alcohol and waste acid, the present invention studies the recovery data of hydrochloric acid water containing isopropanol, as shown in Table 4:

[0071] Table 4

[0072]

[0073]

[0074] After the distillation, the hydrochloric acid with a sodium chloride concentration of 19.6% can be obtained, which fully meets the application specification of hydrochloric acid 10-15%.

[0075] The method can be applied to the next batch of the hydrochloric acid aqueous solution of material A in step 1).

[0076] The isopropanol content of the fraction before rectification is 75%, and the components are analyzed and applied to the next batch of the mixed solvent of material C in step 1).

[0077] The acid water is recovered and distilled under normal pressure. The hydrochloric acid content of the intermediate fraction is very low, 0.25-0.5%. After adding sodium hydroxide for neutralization, it can be used to prepare water glass or dilute water glass and applied to the silicate aqueous solution of material B in step 1).

[0078] Atmospheric distillation, when the acid concentration reaches more than 10%, the top temperature is 108 degrees, pause, cool to room temperature, filter press, and obtain saturated salt water with a concentration of 12%. Hydrochloric acid can be used as a catalyst in the step 1) material A, and the solid sodium chloride can be treated as a by-product and sold.

[0079] In summary, the advantages of the present invention are: low raw material cost, few by-products, high yield, simple preparation process, 100% reuse of solvent and by-product hexamethyldisiloxane, and more than about 80% reuse of waste water.

[0080] The present invention realizes that the organic phase does not need to be washed with alkali or water, and discharges very little three wastes. The overall cost of the project is low and suitable for large-scale industrial production.

[0081] The present invention can replace the end-capping agent on the basis of the present process and can be widely used in the preparation of various MQ type silicone resins containing different groups.

[0082] The present invention can control the molecular weight of the resin by changing the feeding ratio, the dropping speed, the reaction time and the like.

[0083] The following describes the embodiments of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.

[0084] When the embodiments give numerical ranges, it should be understood that, unless otherwise specified in the present invention, both endpoints of each numerical range and any numerical value between the two endpoints can be selected. Unless otherwise defined, all technical and scientific terms used in the present invention have the same meaning as those generally understood by those skilled in the art. In addition to the specific methods, equipment, and materials used in the embodiments, according to the grasp of the prior art by those skilled in the art and the record of the present invention, any methods, equipment, and materials of the prior art similar or equivalent to the methods, equipment, and materials described in the embodiments of the present invention can also be used to realize the present invention.

[0085] Example 1 (first feeding)

[0086] Experimental instruments: 1 1L four-necked reaction bottle, each equipped with a mechanical stirrer, 2 500ml two-necked bottles, 1 500ml four-necked bottle, 1 100ml two-necked bottle, several thermometers and magnetic stirrers, and several condensers.

[0087] Material preparation: Add 65g of 30% hydrochloric acid and 130g of pure water to a 1L four-necked reaction bottle, start stirring, and cool to 5-10°C in an ice-water bath; add 130g of 37% water glass (modulus 3.0-3.3) and 150g of pure water to a 500ml two-necked bottle, start stirring, and cool to 5-10°C in an ice-water bath; add 200g of toluene and 120g of isopropanol to a 500ml two-necked bottle, start stirring, and cool to 5-10°C in an ice-water bath; add 56g of trimethylchlorosilane to a 100ml two-necked bottle, start stirring, and equip it with a thermometer and magnetic stirring.

[0088] Operation steps: After the material preparation is completed, the hydrochloric acid bottle is stirred and turned on, and stirred rapidly at a stirring speed of 300-350R / min. Water glass, mixed solvent, and organosilicon methyl end-capping agent are added to the hydrochloric acid solution in sequence. The addition time of water glass, mixed solvent, and organosilicon methyl end-capping agent is 182s, 212s, and 176s, respectively. The system is naturally heated to 28-30°C and maintained at this temperature for 15-30min, then heated to 60°C, kept warm for 1.5 hours, and separated into layers to obtain 310g of organic phase and 540g of aqueous phase.

[0089] Treatment of organic phase: The organic phase was transferred to a 500ml four-necked bottle, equipped with a condenser, and 60g of toluene was added to start heating and reflux reaction for 1 hour, and the reflux was changed to short steaming, and nitrogen was bubbled at the bottom. 246g of toluene was distilled out (the toluene solution containing 12.5% ​​isopropanol was analyzed and can be used), and 122g of colorless and transparent MQ resin was obtained, with a solid content of 56% and a yield of 92.7%. pH = 6-7, viscosity 8.9mm 2 / s, weight average molecular weight: 7800.

[0090] Water phase treatment: 540g of the water phase obtained in the previous step is short-distilled again, and 88g of isopropanol aqueous solution (75% isopropanol analysis) is obtained from fraction 1# at 78-81°C, 50g of fraction 2# at top temperature 82-100°C is recycled (containing 20g of isopropanol), and 198g of fraction 3# at top temperature 100-107°C contains 0.1-0.5% hydrochloric acid (very little isopropanol content). When the top temperature reaches 107-108°C, stop cooling to room temperature, and filter to obtain 185g of hydrochloric acid containing 12.5% ​​saturated sodium chloride (hydrochloric acid titration: 12.5%), which can be directly used, and 16g of wet sodium chloride solid.

[0091] Remarks: Organic phase analysis method: Gas chromatograph-2010, DB-1 column, Col: 50℃(2min)-20℃ / min-280℃(20min), Inj: 250℃, Dec: 290℃.

[0092] Aqueous isopropanol analysis method: Karl Fischer moisture tester, model: 915KF Ti-touch

[0093] Hydrochloric acid purity analysis method: acid-base titration

[0094] Example 2 (for solvent and acid water jacket)

[0095] 1 1L four-necked reaction bottle with mechanical stirring, 2 500ml two-necked bottles, 1 500ml four-necked bottle, 1 100ml two-necked bottle, several thermometers and magnetic stirring machines, and several condensers.

[0096] Material preparation: 156g of the concentrated filtered mother liquor of hydrochloric acid in Example 1 (the amount of HCl is 156*0.125=19.5g) was added to a 1L four-necked reaction bottle, and 39g of the aqueous phase treatment fraction 3# in Example 1 (the hydrochloric acid content is very low and can be ignored) was added to prepare 10% hydrochloric acid, stirring was started, and the temperature was cooled to 5-10°C in an ice-water bath; 130g of 37% water glass (modulus 3.0-3.3) was added to a 500ml two-necked bottle, and 100g of pure water was added. 50g, start stirring, cool to 5-10°C in an ice-water bath; 246g of recovered toluene (31g of isopropanol), the aqueous phase distillation fraction in Example 1 (67g of isopropanol), 22g of fresh isopropanol were added to a 500ml two-necked bottle, stirring was started, and the temperature was cooled to 5-10°C in an ice-water bath; 56g of trimethylchlorosilane was added to a 100ml two-necked bottle, stirring was started, and a thermometer and magnetic stirring were used.

[0097] Operation steps: After the preparation is completed, the hydrochloric acid bottle is stirred and turned on, and stirred rapidly at a stirring speed of 300-350R / min. In the order of water glass, mixed solvent, and organosilicon methyl end-capping agent, they are rapidly added dropwise to the hydrochloric acid solution. The addition time of water glass, mixed solvent, and organosilicon methyl end-capping agent is 187s, 232s, and 184s, respectively. The system is naturally heated to 28-30°C and maintained at this temperature for 15min, then heated to 60°C, kept warm for 1.5 hours, and separated into layers to obtain 321g of organic phase and 536g of aqueous phase.

[0098] Organic phase treatment: The organic phase was transferred to a 500ml four-necked bottle, equipped with a condenser, and 60g of toluene was added. The temperature was raised and refluxed for 1 hour, and the reflux was changed to short distillation, and nitrogen was bubbled at the bottom. 252g of toluene was distilled out (the toluene solution containing 12.8% isopropanol was analyzed and can be used for application). 125g of colorless and transparent MQ resin was obtained, with a solid content of 54.9% and a yield of 93.15%. pH = 6-7, viscosity 9.6mm 2 / s, weight average molecular weight: 8142.

[0099] Aqueous phase treatment: After combining fraction 2# in Example 1 and the aqueous phase in Example 2, follow the aqueous phase treatment steps of Example 1 to recover isopropanol and hydrochloric acid and analyze their contents, and apply the results based on the content analysis.

[0100] Starting from the second application, the amount of fresh isopropyl alcohol added will become less and less, and even no fresh isopropyl alcohol will need to be added.

[0101] The amount of hydrochloric acid in the process system of the invention is sufficient and no fresh hydrochloric acid is needed.

[0102] The invention applies Examples 3-6 as shown in Table 5:

[0103] Table 5

[0104]

[0105] Note: All subsequent application methods follow the method of Example 2, and other ingredients, addition order, and addition time are the same as before.

[0106] During the application of the present invention, although the index of the resin does not change much, the appearance has an obvious downward trend. After analysis, it is due to the enrichment of iron ions in the silicone resin. The introduction of iron ions can also be controlled by controlling the iron ions in hydrochloric acid and trimethylchlorosilane. It has been verified by multiple experiments that the color of the obtained resin has been significantly improved by the redistillation method of white hydrochloric acid and trimethylchlorosilane in the early stage. The color of the silicone resin will turn yellow only after the number of applications is significantly increased to 5-6 times. After the color turns yellow, the silicone resin can be washed with water to remove the color in the silicone resin. When it is found that the silicone resin turns yellow, the hydrochloric acid is recovered and no longer applied, and the colorless hydrochloric acid with a content of about 10% recovered by new white acid or short-steamed hydrochloric acid continues to be applied.

[0107] In summary, the present invention effectively improves and optimizes the method for preparing MQ silicone resin by the water glass method, solves the problems of fast hydrolysis rate, difficult reaction control, and easy gelation in the process of trimethylchlorosilane end-capping; simplifies the operation steps, reduces the steps of alkali washing and water washing, and greatly reduces wastewater discharge. It also realizes the 100% application of all solvents, and the cost of hydrochloric acid is reduced by not needing to add hydrochloric acid later, and the wastewater generated is almost fully applied, and the acid content of the wastewater to be treated is less than 1%, which greatly reduces the cost of wastewater treatment.

[0108] The above examples are for the purpose of illustrating the embodiments disclosed by the present invention and are not to be construed as limiting the present invention. In addition, the various modifications listed herein and the variations of the methods in the invention are obvious to those skilled in the art without departing from the scope and spirit of the present invention. Although the present invention has been specifically described in conjunction with various specific preferred embodiments of the present invention, it should be understood that the present invention should not be limited to these specific embodiments. In fact, various modifications as described above that are obvious to those skilled in the art to obtain the invention should be included within the scope of the present invention.

Claims

1. A method for preparing a methyl MQ type silicone resin and applying solvent wastewater, the method comprising: 1) adding hydrochloric acid aqueous solution, silicate aqueous solution, mixed solvent and organosilicon methyl end-capping agent in sequence, stirring and reacting; Alternatively, add hydrochloric acid aqueous solution, silicate aqueous solution, organosilicon methyl end-capping agent and mixed solvent in order, and stir to react; 2) After the reaction, the mixture was allowed to stand for separation to obtain an organic phase and an aqueous phase; 3) blowing an inert gas into the organic phase in step 2) to evaporate the first solvent, polycondensing to obtain a liquid or solid MQ type silicone resin; and using the first solvent in step 1); 4) distilling the water phase obtained in step 2) to recover the second solvent, and using the second solvent in step 1).

2. The method for preparing methyl MQ type silicone resin and utilizing solvent wastewater as claimed in claim 1, characterized in that: Also includes any one or more of the following features: A1) In step 1), the concentration of the aqueous hydrochloric acid solution is 10-30%; A2) in step 1), the modulus of the silicate aqueous solution is 3.0-3.6; A3) In step 1), the concentration of the silicate aqueous solution is 16-18%; A4) in step 1), the mixed solvent is a mixed solvent of a non-polar solvent and an alcohol; A5) in step 1), the organosilicon methyl end-capping agent is selected from trimethylchlorosilane and / or hexamethyldisiloxane; A6) In step 1), the mass ratio of the hydrochloric acid aqueous solution, the silicate aqueous solution, the mixed solvent, and the organosilicon methyl end-capping agent is 1:2.4:1.6:(0.39-0.62).

3. The method for preparing methyl MQ type silicone resin and utilizing solvent wastewater as claimed in claim 2, characterized in that: Also includes any one or more of the following features: A11) In step 1), the concentration of the hydrochloric acid aqueous solution is 10-15%; A21) In step 1), the modulus of the silicate aqueous solution is 3.0-3.3; A41) In step 1), the non-polar solvent is selected from one or more of toluene, xylene, petroleum ether, and dimethyl carbonate; A42) In step 1), the alcohol solvent is selected from one or more of methanol, ethanol, and isopropanol; A42) In step 1), the mass ratio of the alcohol to the non-polar solvent is 1:1-3:2; A51) In step 1), the organosilicon methyl end-capping agent is trimethylchlorosilane.

4. The method for preparing methyl MQ type silicone resin and utilizing solvent wastewater as claimed in claim 3, characterized in that: In feature A42), the alcohol solvent is isopropanol.

5. The method for preparing methyl MQ type silicone resin and utilizing solvent wastewater as claimed in claim 1, characterized in that: Also includes any one or more of the following features: B1) In step 1), the hydrochloric acid aqueous solution, silicate aqueous solution, mixed solvent, and organosilicon methyl end-capping agent must be cooled to 0-15°C before adding; B2) In step 1), each material is added in sequence under stirring; wherein the stirring speed is 300-350R / min; B3) In step 1), when adding the silicate aqueous solution, the mixed solvent and the organosilicon methyl end-capping agent, the feeding time of each material is 3-5 minutes; B4) In step 1), stirring is continued for 10-30 minutes after each material is added.

6. The method for preparing methyl MQ type silicone resin and utilizing solvent wastewater as claimed in claim 1, characterized in that: Also includes any one or more of the following features: C1) In step 1), the reaction temperature is 40 to 70°C; C2) In step 1), the reaction time is 1 to 3 hours.

7. The method for preparing methyl MQ type silicone resin and utilizing solvent wastewater as claimed in claim 6, characterized in that: Also includes any one or more of the following features: C11) In step 1), the reaction temperature is 50-60°C; C12) In step 1), the reaction time is 1 to 2 hours.

8. The method for preparing methyl MQ type silicone resin and utilizing solvent wastewater as claimed in claim 1, characterized in that: In step 3), the inert gas is selected from one of nitrogen, helium and argon.

9. The method for preparing methyl MQ type silicone resin and utilizing solvent wastewater as claimed in claim 1, characterized in that: In step 3), the first solvent is a non-polar solvent containing an alcohol solvent.

10. The method for preparing methyl MQ type silicone resin and utilizing solvent wastewater as claimed in claim 1, characterized in that: Also includes any one or more of the following features: D1) In step 4), the front fraction of the distillation is the second solvent, and the second solvent is an alcohol aqueous solution; D2) In step 4), the intermediate fraction of the distillation is 0.25-0.5% hydrochloric acid, which is used to prepare or dilute the silicate aqueous solution after adding alkali for neutralization; and is applied to the silicate aqueous solution in step 1); D3) In step 4), when the distillation reaches the top temperature, it is suspended, cooled to room temperature, and filtered to obtain a 10-12% hydrochloric acid aqueous solution containing saturated sodium chloride, which is used in the hydrochloric acid aqueous solution in step 1).

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