Preparation method of vinyl MQ resin

Abstract

The invention discloses a preparation method of vinyl MQ resin, which comprises the following steps: adding MQ resin, a benzene series solvent, vinyl dimethyl chlorosilane and organic weak base into a reaction system for reaction, and washing with water to remove impurities after the reaction is finished to obtain a vinyl MQ resin solution. According to the method, the utilization rate of the end-capping reagent can reach 95% or above.

Description

Technical Field

[0001] The invention belongs to the technical field of MQ resin synthesis, and in particular relates to a method for efficiently end-capping and synthesizing vinyl MQ resin. Background Art

[0002] MQ resin is a kind of resin containing M unit (R 3 SiO 1 / 2 ) and Q units (SiO2) with a "core-shell" structure of organic silicone resin, which has excellent reinforcement and viscosity-increasing effects, good film-forming properties and a high glass transition temperature. This makes it suitable for use in pressure-sensitive adhesives, release agents, liquid silicone rubber and other fields. Its excellent compatibility with silicone oil makes its products optically transparent, which is also an important reason why MQ resin is irreplaceable in the optical field.

[0003] When MQ resin is end-capped with vinyl, vinyl MQ resin can be obtained. Since vinyl has the possibility of further reaction, it has strong competitiveness in the field of enhancement and reinforcement. Vinyl MQ resin is usually obtained by end-capping MQ resin, but the end-capping process is time-consuming and inefficient. In order to solve this problem, Dow Corning has increased the reaction rate by adding polar organic compounds. Under the same reaction process, the end-capping rate of the end-capping agent has increased by about one time (CN105873985A). Despite this, there are still about 40% of the end-capping agents that are not end-capped and are wasted. For industrialization, it is necessary to reduce the cost increase caused by the waste of end-capping agents.

[0004] Therefore, there is a need for a method for efficiently end-capping and synthesizing vinyl MQ resins in the art. Summary of the invention

[0005] In view of the above problems existing in the prior art, the present invention provides a method for preparing a vinyl MQ resin, and by adding an organic weak base as a reaction accelerator, the utilization rate of the end-capping agent can be achieved to be above 95%.

[0006] In order to achieve the above technical effects, the present invention adopts the following technical solutions:

[0007] The invention provides a method for preparing a vinyl MQ resin. The method uses MQ resin as a raw material, dimethylvinyl chlorosilane as a capping agent to carry out a capping reaction, and adds an organic weak base as a reaction accelerator to prepare the vinyl MQ resin.

[0008] In one embodiment, the organic weak base used in the end-capping reaction process of the present invention is an organic base that is generally understood in the art to be incompletely ionized after being dissolved in water; preferably, the organic weak base is one or more nitrogen-containing organic compounds with a conjugate acid pKa (acidity coefficient) between 5 and 14.

[0009] In a specific embodiment, the organic weak base is one or more of alkylamine, pyridine, alkylpyridine, imidazole, alkylimidazole, etc., preferably one or more of triethylamine and pyridine.

[0010] In a specific embodiment, the molar ratio of the organic weak base to dimethylvinylchlorosilane is 0.87 to 1.13:1, for example, 0.87:1, 0.90:1, 0.93:1, 0.95:1, 0.98:1, 1.0:1, 1.03:1, 1.05:1, 1.08:1, 1.10:1, 1.13:1, etc.

[0011] In one embodiment, the raw material MQ resin used in the present invention has a structure as shown in the following formula [(R 1 2R 2 1SiO 1 / 2 ) a (R 1 3SiO 1 / 2 ) b (HSiO2) c (SiO2) d ],

[0012] Among them, R 1 are independently hydrogen, an alkane with a carbon number not exceeding 10 (e.g., a C1-C8 alkane), preferably a methyl group, an ethyl group, etc.; R 2 are independently hydrogen, aryl, olefin with no more than 8 carbon atoms, or alkyne with no more than 8 carbon atoms, preferably vinyl, propenyl, or ethynyl;

[0013] (a+b): (c+d) = 0.5 to 1.2, preferably 0.7 to 1.0, 0≤a<c<b<d.

[0014] In a specific embodiment, the MQ resin has a weight average molecular weight of 5000 to 28000 g / mol, for example, 5000 g / mol, 7000 g / mol, 10000 g / mol, 12000 g / mol, 15000 g / mol, 18000 g / mol, 20000 g / mol, 23000 g / mol, 25000 g / mol, 28000 g / mol, etc.

[0015] In a specific embodiment, the molar ratio of the dimethylvinyl chlorosilane to the hydroxyl group in the MQ resin is 0.4 to 0.9:1, for example, 0.4:1, 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1, etc.

[0016] In one embodiment, a solvent is added during the end-capping reaction of the present invention;

[0017] The solvent is a benzene series, preferably one or more of benzene, toluene, xylene, ethylbenzene, propylbenzene, trimethylbenzene, etc., more preferably one or more of toluene, xylene, and ethylbenzene.

[0018] In a specific embodiment, the mass ratio of the solvent to the MQ resin is 0.6 to 1:1, for example, 0.6:1, 0.7:1, 0.8:1, 0.9:1, 1:1, etc.

[0019] In one embodiment, the end-capping reaction process of the present invention has a reaction temperature of 50 to 100°C, for example 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, etc., preferably 65 to 90°C, and a reaction time of 0.1 to 24h, for example 0.1h, 0.5h, 1h, 3h, 5h, 8h, 10h, 12h, 15h, 18h, 20h, 24h, etc., preferably 0.5 to 2h.

[0020] In one embodiment, the end-capping reaction process of the present invention is carried out in a protective gas, and the protective gas can be one or more of nitrogen and argon.

[0021] In a specific application, a method for preparing a vinyl MQ resin of the present invention comprises the following steps:

[0022] Under nitrogen protection, a solvent, MQ resin, dimethylvinyl chlorosilane and an organic weak base are sequentially added into the reaction system, and the temperature is raised to 50-100° C. to react for 0.1-24 hours to obtain a reaction mother solution;

[0023] Then, water is added for washing (preferably an equal amount of clean water), and after washing with water three times, the upper organic phase is collected and the solvent is removed by distillation under reduced pressure to obtain the product vinyl MQ resin.

[0024] According to the preparation method provided by the invention, the utilization rate of the end-capping agent can reach more than 95%, and the synthesized vinyl MQ resin has a vinyl content of 1.5 to 4 wt% and a hydroxyl content of 0 to 1.5 wt%.

[0025] The vinyl MQ resin synthesized by the invention is suitable for the fields of liquid silicone rubber reinforcement, LED packaging or release agent.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] The method provided by the invention improves the utilization rate of the end-capping agent and reduces the production cost. Meanwhile, the obtained product has stable quality and excellent performance, and is suitable for the fields of liquid silicone rubber reinforcement, LED packaging or release agent. DETAILED DESCRIPTION

[0028] The following examples will further illustrate the method provided by the present invention, but the present invention is not limited to the listed examples, and should also include any other known changes within the scope of the rights claimed by the present invention.

[0029] In the embodiments and comparative examples of the present invention, the sources of the main raw materials used are as follows. Unless otherwise specified, other raw materials and reagents were purchased from commercial sources:

[0030] The MQ resin used in the examples was prepared by referring to the method disclosed in patent CN113321809B:

[0031] MQ resin 1#: Its structure is [(R 1 2R 2 1SiO 1 / 2 ) a (R 1 3SiO 1 / 2 ) b (HSiO2) c (SiO2) d ], where R 1 Methyl, R 2 The hydroxyl content is 2.85% as measured by FTIR, and the weight average molecular weight is 19987 as measured by GPC;

[0032] MQ resin 2#: Its structure is [(R 1 2R 2 1SiO 1 / 2 ) a (R 1 3SiO 1 / 2 ) b (HSiO2) c (SiO2) d ], where R 1 Methyl, R 2 H, a=0, b=0.7, c=0.15, d=0.85; FTIR measured the hydroxyl content to be 2.25%, GPC measured the weight average molecular weight to be 15487;

[0033] Dimethylvinylchlorosilane: Xinyaqiang Silicon Chemical Co., Ltd.;

[0034] Pyridine: Beijing Inokai Technology Co., Ltd.;

[0035] Xylene: Sinopec Qingdao Refining and Chemical Co., Ltd.;

[0036] Triethylamine: Beijing Inokai Technology Co., Ltd.;

[0037] Sodium hydroxide: Beijing Inokai Technology Co., Ltd.;

[0038] Calcium carbonate: Beijing Inokai Technology Co., Ltd.

[0039] Example 1

[0040] A mechanical stirrer, a condenser and a thermometer were installed on a 2L three-necked reaction bottle and nitrogen was replaced to ensure a nitrogen atmosphere in the system. Subsequently, 800gMQ resin 1#, 500g xylene, 145g dimethylvinyl chlorosilane and 95g pyridine (the molar ratio of the end-capping agent, MQ hydroxyl and accelerator was 0.9:1:0.9) were added under nitrogen protection, and the temperature was raised to 80°C for reaction after stirring. After 2 hours, the heating was stopped and the mixture was poured into a separating funnel. An equal amount of clean water was added to shake and separate the liquids. The upper organic phase was collected and washed three times to obtain a xylene solution of vinyl MQ resin. The solvent was removed by vacuum distillation to obtain vinyl MQ resin powder. The vinyl content was 3.87wt% and the hydroxyl content was 0.36wt% as measured by FTIR. The weight average molecular weight measured by GPC was 19527.

[0041] The conversion rate of the end-capping agent in the system was monitored by GC. After 0.5 h of reaction, the conversion rate of the end-capping agent was 77.3%, after 1 h of reaction, the conversion rate of the end-capping agent was 95.0%, and after 2 h of reaction, the conversion rate of the end-capping agent was 97.8%.

[0042] Example 2

[0043] A mechanical stirrer, a condenser and a thermometer were assembled on a 2L three-necked reaction bottle and nitrogen substituted to ensure a nitrogen atmosphere in the system. Subsequently, 800gMQ resin 2#, 600g xylene, 102g dimethylvinyl chlorosilane and 88.8g 2-methylpyridine (the molar ratio of the end-capping agent, MQ hydroxyl and accelerator was 0.8:1:0.9) were added under nitrogen protection, and the temperature was raised to 70°C for reaction after stirring. After 2h, the heating was stopped and the mixture was poured into a separating funnel. 1000g of clean water was added to shake and separate the liquids. The upper organic phase was collected and washed three times to obtain a xylene solution of vinyl MQ resin. The solvent was removed by vacuum distillation to obtain a vinyl MQ resin powder. The vinyl content was 2.85wt% and the hydroxyl content was 0.49wt% as measured by FTIR. The weight average molecular weight measured by GPC was 15877.

[0044] The conversion rate of the end-capping agent in the system was monitored by GC. After 0.5 h of reaction, the conversion rate of the end-capping agent was 75.8%, after 1 h of reaction, the conversion rate of the end-capping agent was 95.2%, and after 2 h of reaction, the conversion rate of the end-capping agent was 98.3%.

[0045] Example 3

[0046] A mechanical stirrer, a condenser and a thermometer were installed on a 2L three-necked reaction bottle and nitrogen was replaced to ensure a nitrogen atmosphere in the system. Subsequently, 800gMQ resin 1#, 700g toluene, 64.5g dimethylvinyl chlorosilane and 36.3g imidazole (the molar ratio of the end-capping agent, MQ hydroxyl and accelerator was 0.4:1:0.4) were added under nitrogen protection, and the temperature was raised to 95°C for reaction after stirring. After 12 hours, the heating was stopped and the mixture was poured into a separating funnel. 1000g of clean water was added to shake and separate the liquids. The upper organic phase was collected and washed three times to obtain a xylene solution of vinyl MQ resin. The solvent was removed by vacuum distillation to obtain vinyl MQ resin powder. The vinyl content was 1.80wt% and the hydroxyl content was 1.72wt% as measured by FTIR. The weight average molecular weight measured by GPC was 19885.

[0047] The conversion rate of the end-capping agent in the system was monitored by GC. After 0.5 h of reaction, the conversion rate of the end-capping agent was 88.3%, after 1 h of reaction, the conversion rate of the end-capping agent was 97.5%, after 2 h of reaction, the conversion rate of the end-capping agent was 99.1%, and after 12 h of reaction, the conversion rate of the end-capping agent was 99.3%.

[0048] Example 4

[0049] A mechanical stirrer, a condenser and a thermometer were installed on a 2L three-necked reaction bottle and nitrogen was replaced to ensure a nitrogen atmosphere in the system. Subsequently, 800gMQ resin 1#, 500g xylene, 64.5g dimethylvinyl chlorosilane and 47.9g triethylamine (the molar ratio of the end-capping agent, MQ hydroxyl and accelerator was 0.4:1:0.35) were added under nitrogen protection, and the temperature was raised to 55°C for reaction after stirring. After 8 hours, the heating was stopped and the mixture was poured into a separating funnel. 1000g of clean water was added to shake and separate the liquids. The upper organic phase was collected and washed three times to obtain a xylene solution of vinyl MQ resin. The solvent was removed by vacuum distillation to obtain vinyl MQ resin powder. The vinyl content was 1.7wt% and the hydroxyl content was 1.82wt% as measured by FTIR. The weight average molecular weight measured by GPC was 19855.

[0050] The conversion rate of the end-capping agent in the system was monitored by GC. After 0.5 h of reaction, the conversion rate of the end-capping agent was 80.7%, after 1 h of reaction, the conversion rate of the end-capping agent was 88.9%, after 2 h of reaction, the conversion rate of the end-capping agent was 92.6%, and after 8 h of reaction, the conversion rate of the end-capping agent was 92.7%.

[0051] Comparative Example 1

[0052] The method of Example 1 was followed except that the accelerator pyridine was not added, and other operations and conditions remained unchanged to obtain vinyl MQ resin powder, which had a vinyl content of 0.85 wt % and a hydroxyl content of 2.31 wt % as measured by FTIR, and a weight average molecular weight of 19565 as measured by GPC.

[0053] The conversion rate of the end-capping agent in the system was monitored by GC. After 0.5 h of reaction, the conversion rate of the end-capping agent was 8.2%, after 1 h of reaction, the conversion rate of the end-capping agent was 13.9%, and after 2 h of reaction, the conversion rate of the end-capping agent was 21.6%.

[0054] Comparative Example 2

[0055] The method of Example 1 was followed, except that the promoter pyridine was replaced by an equal amount of catalyst isopropanol, and other operations and conditions remained unchanged to obtain a vinyl MQ resin powder, which had a vinyl content of 2.33 wt % and a hydroxyl content of 1.45 wt % as measured by FTIR, and a weight average molecular weight of 20110 as measured by GPC.

[0056] The conversion rate of the end-capping agent in the system was monitored by GC. After 0.5 h of reaction, the conversion rate of the end-capping agent was 25.3%, after 1 h of reaction, the conversion rate of the end-capping agent was 37.8%, and after 2 h of reaction, the conversion rate of the end-capping agent was 55.7%.

[0057] Comparative Example 3

[0058] The method of Example 1 was followed, except that the promoter pyridine was replaced by an equal amount of calcium carbonate (inorganic weak base), and other operations and conditions remained unchanged to obtain a vinyl MQ resin powder, which had a vinyl content of 2.55 wt % and a hydroxyl content of 1.32 wt % as measured by FTIR, and a weight average molecular weight of 20026 as measured by GPC.

[0059] The conversion rate of the end-capping agent in the system was monitored by GC. After 0.5 h of reaction, the conversion rate of the end-capping agent was 30.3%, after 1 h of reaction, the conversion rate of the end-capping agent was 44.9%, and after 2 h of reaction, the conversion rate of the end-capping agent was 60.2%.

[0060] Comparative Example 4

[0061] The method of Example 1 was followed, except that the promoter pyridine was replaced by an equal amount of sodium hydroxide (strong base), and other operations and conditions remained unchanged to obtain a vinyl MQ resin powder, which had a vinyl content of 2.95 wt % and a hydroxyl content of 0.9 wt % as measured by FTIR, and a weight average molecular weight of 16506 as measured by GPC.

[0062] The conversion rate of the end-capping agent in the system was monitored by GC. After 0.5 h of reaction, the conversion rate of the end-capping agent was 50.2%, after 1 h of reaction, the conversion rate of the end-capping agent was 69.6%, and after 2 h of reaction, the conversion rate of the end-capping agent was 77.6%.

[0063] As can be seen from Example 1, Example 2, Example 3 and Comparative Example 1, Comparative Example 2, organic weak bases such as pyridine and triethylamine can promote the end-capping of the end-capping agent. Compared with Comparative Example 1 and Comparative Example 2 without adding a promoter, the end-capping agent conversion rate is greatly improved and the end-capping rate is greatly improved. Therefore, the addition of an organic weak base promoter improves the utilization rate and end-capping rate of the end-capping agent, reduces the cost of the process route for preparing vinyl MQ resin by MQ end-capping, and greatly improves environmental protection. When an inorganic weak base is used, the effect is not good due to uneven dispersion. When a strong base is used, the molecular structure of the MQ resin is rearranged and the molecular weight is reduced, which will reduce the application performance of the vinyl MQ resin, such as mechanical properties.

[0064] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any simple modification or equivalent change made to the above embodiment based on the technical essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. A method for preparing a vinyl MQ resin, characterized in that: The vinyl MQ resin is prepared by using MQ resin as a raw material, dimethylvinyl chlorosilane as a capping agent to carry out a capping reaction, and adding an organic weak base as a reaction accelerator.

2. The preparation method according to claim 1, characterized in that: The organic weak base is one or more nitrogen-containing organic compounds whose conjugate acid pKa is between 5 and 14; Preferably, the organic weak base is one or more of alkylamine, pyridine, alkylpyridine, imidazole, alkylimidazole, preferably one or more of triethylamine and pyridine.

3. The preparation method according to claim 1 or 2, characterized in that: The molar ratio of the organic weak base to dimethylvinylchlorosilane is 0.87-1.13:

1.

4. The preparation method according to any one of claims 1 to 3, characterized in that The MQ resin has a structure as shown below [(R 1 2R 2 1SiO 1 / 2 ) a (R 1 3SiO 1 / 2 ) b (HSiO2) c (SiO2) d ], Among them, R 1 are independently hydrogen or an alkane with a carbon number not exceeding 10, preferably a methyl or ethyl group; R 2 are independently hydrogen, aryl, olefin with no more than 8 carbon atoms, or alkyne with no more than 8 carbon atoms, preferably vinyl, propenyl, or ethynyl; (a+b): (c+d) = 0.5 to 1.2, preferably 0.7 to 1.0, 0≤a<c<b<d.

5. The preparation method according to any one of claims 1 to 4, characterized in that: The weight average molecular weight of the MQ resin is 5000 to 28000 g / mol.

6. The preparation method according to any one of claims 1 to 5, characterized in that: The molar ratio of the dimethylvinyl chlorosilane to the hydroxyl group in the MQ resin is 0.4-0.9:

1.

7. The preparation method according to any one of claims 1 to 6, characterized in that: A solvent is added during the end-capping reaction; The solvent is a benzene series, preferably one or more of benzene, toluene, xylene, ethylbenzene, propylbenzene, and trimethylbenzene, more preferably one or more of toluene, xylene, and ethylbenzene; Preferably, the mass ratio of the solvent to the MQ resin is 0.6 to 1:

1.

8. The preparation method according to any one of claims 1 to 7, characterized in that: The end-capping reaction process has a reaction temperature of 50 to 100° C., preferably 65 to 90° C., and a reaction time of 0.1 to 24 h, preferably 0.5 to 2 h.

9. The preparation method according to any one of claims 1 to 8, characterized in that: The end-capping reaction process is carried out in a protective gas, and the protective gas is one or more of nitrogen and argon.

10. The preparation method according to any one of claims 1 to 9, characterized in that: The synthesized vinyl MQ resin is suitable for liquid silicone rubber reinforcement, LED encapsulation or release agent fields.