Process for the preparation of guanidine-modified silicone oils and alkoxy-terminated silicone oils

Abstract

The application belongs to the field of organic silicon material, and discloses a guanidine modified silicone oil catalyst and a preparation method of alkoxy-terminated silicone oil. The catalyst is prepared by the reaction of carbodiimide and aminopropyl polysiloxane. The catalyst is used to catalyze the dehydrogenation condensation reaction of hydroxyl silicone oil and alkoxy-terminated agent, and the alkoxy-terminated silicone oil is prepared through the steps of dehydration, reaction and neutralization. The guanidine modified silicone oil is used as the catalyst, the problems of expensive price and easy poisoning of traditional platinum catalyst and the heavy metal problem of organic tin catalyst are avoided. The method has mild reaction conditions and simple process, the catalyst has good compatibility with raw materials, and the end-capping rate can be effectively improved. The obtained product has excellent storage stability and is suitable for the field of dealcoholized silicone rubber.

Description

Technical Field

[0001] This invention belongs to the field of organosilicon materials, specifically relating to the preparation method of guanidine-modified silicone oil catalyst and alkoxy-terminated silicone oil. Background Technology

[0002] Hydroxyl-terminated polydimethylsiloxane is a basic polymer for dealcoholized silicone rubber. By replacing the hydroxyl groups at the ends of its molecular chain with alkoxy functional groups, alkoxy-terminated polydimethylsiloxane can be prepared. This structural change can reduce its reaction rate with the catalyst, avoid the sudden increase in system viscosity from affecting the rubber compound formulation process, and at the same time enhance the adhesion strength between silicone rubber and the substrate.

[0003] Patent CN104558612B uses organic amine salts as catalysts to promote the reaction of α,ω-dihydroxypolydimethylsiloxane with alkoxysilanes to prepare alkoxy-terminated polysiloxane polymers. This method not only improves the end-capping rate, but also allows the catalyst to react with excess end-capping agent to generate amides that are harmless to the stability of the product, thus eliminating the need for subsequent processing.

[0004] Patent CN113512197B involves first mixing methyltrimethoxysilane, vinyltrimethoxysilane, and zinc acetylacetone catalyst evenly, then taking the supernatant and adding it to a reaction vessel along with α,ω-dihydroxypolydimethylsiloxane and 100cSt dimethyl silicone oil, and reacting at room temperature to obtain alkoxy-terminated silicone oil.

[0005] In organosilicon chemistry, dehydrogenation condensation reactions offer advantages such as simplicity and high efficiency due to the ease with which the released small-molecule hydrogen gas escapes from the matrix. However, the catalysts traditionally used for this reaction are mainly platinum-based or organotin-based systems: the former, while requiring small amounts and possessing synergistic flame-retardant and high-temperature resistance properties, is expensive and prone to poisoning; the latter contains heavy metals and has been restricted in the use of silicone rubber and related products. Patent CN102575011B discloses a non-metallic guanidine catalyst that can be used in the dehydrogenation condensation reaction during silicone rubber vulcanization. It exhibits high catalytic efficiency, low dosage, and mild vulcanization conditions, and can be activated at room temperature. However, this small-molecule guanidine catalyst may have limited compatibility with silicone oil, and is prone to volatilization or migration, affecting the long-term performance of the product.

[0006] Based on the above background, this invention fully utilizes the advantages of dehydrogenation condensation reaction and proposes a new method for preparing alkoxy-terminated silicone oil by designing and synthesizing guanidine-modified silicone oil as a catalyst. Summary of the Invention

[0007] The purpose of this invention is to provide a novel guanidine-modified silicone oil catalyst and a new method for preparing alkoxy-terminated silicone oil. This invention, through the design of a guanidine-modified silicone oil catalyst, achieves highly efficient catalytic dehydrogenation condensation reaction under mild conditions, yielding alkoxy-terminated silicone oil with high end-capping rate, storage stability, and no metal ions. This solves the problems of high cost, easy poisoning, and heavy metal content of traditional platinum / tin catalysts, as well as poor compatibility and easy migration of small molecule guanidine catalysts with silicone oil.

[0008] The basic concept of the technical solution adopted in this invention is as follows: A guanidine-modified silicone oil catalyst has the following structure: ; Where 1≤p≤50, and R is any one of isopropyl, tert-butyl, cyclohexyl or trimethylsilyl.

[0009] As one embodiment, the synthetic route of the guanidine-modified silicone oil catalyst is as follows: carbodiimide molecules are reacted with aminopropyl polysiloxane at 60~100℃ for 3~6h, and unreacted small molecules are removed under reduced pressure to obtain the guanidine-modified silicone oil catalyst. The carbodiimide molecule is selected from any one of N,N′-diisopropylcarbodiimide, N,N′-ditert-butylcarbodiimide, N,N′-dicyclohexylcarbodiimide or di(trimethylsilyl)carbodiimide; The structure of the aminopropyl polysiloxane is as follows: ; Where 1≤p≤50; the molar ratio of the carbodiimide molecule to aminopropyl polysiloxane is 2~2.2:1.

[0010] The present invention further provides a method for preparing alkoxy-terminated silicone oil, which involves dehydrating hydroxyl silicone oil, then adding a capping agent to the dehydrated hydroxyl silicone oil under a N2 atmosphere and carrying out a dehydrogenation condensation reaction with a guanidine-modified silicone oil catalyst as described in any of the above contents. After the reaction is completed, the temperature is lowered to room temperature and a neutralizing agent is added to obtain the alkoxy-terminated silicone oil.

[0011] As one embodiment, the method for preparing the alkoxy-terminated silicone oil includes the following steps: Step S1: Dehydrate the hydroxyl silicone oil at 100~120℃ and a vacuum of 90~99kPa for 2~4 hours. Step S2: Under a N2 atmosphere, add a capping agent and the guanidine-modified silicone oil catalyst as described in any one of claims 1-2 to the dehydrated hydroxyl silicone oil from step S1 to carry out a dehydrogenation condensation reaction; control the reaction temperature at 30~100℃ and the reaction time at 4~8h. Step S3: After the reaction is complete, cool to room temperature and add a neutralizing agent. Stir for 1-2 hours to obtain the alkoxy-terminated silicone oil.

[0012] As one embodiment, in the method for preparing the alkoxy-terminated silicone oil, the structure of the hydroxyl silicone oil is as follows: ; R1, R2, R3, and R4 are any one of -CH3, -CH2CH2CF3, and -C6H5, and are mutually independent, with 10 ≤ m ≤ 1000; The molecular structure of the alkoxy-terminated silicone oil is as follows: ; Among them, R5, R6, and R7 are any one of methyl, methoxy, and ethoxy, and methyl is not used at the same time, and 10 ≤ n ≤ 1000.

[0013] In one embodiment, the capping agent is any one of trimethoxysilane, triethoxysilane, methyldimethoxysilane, or methyldiethoxysilane.

[0014] In one embodiment, the molar ratio of the hydroxyl silicone oil to the end-capping agent is 1:2 to 2.4; the amount of the guanidine-modified silicone oil catalyst added is 0.01% to 1% of the total mass of the reaction system, wherein the total mass of the reaction system is the total mass of the hydroxyl silicone oil, end-capping agent and catalyst before dehydration.

[0015] In one embodiment, the neutralizing agent is any one of organosilicon phosphate, phosphoric acid, glutaric acid, and valeric acid, and the amount added is 0.01% to 1% of the total mass of the reaction system.

[0016] Compared with the prior art, the present invention has the following advantages: 1. This invention designs and synthesizes a novel guanidine catalyst that has good compatibility with organosilicon systems and can efficiently catalyze the reaction between Si-OH and Si-H.

[0017] 2. The reaction principle of the alkoxy-terminated silicone oil preparation method of the present invention is dehydrogenation condensation, which is rapid, easy to remove by-products (hydrogen), has a high end-capping rate, and good product storage stability.

[0018] 3. The alkoxy-terminated silicone oil preparation method of the present invention uses hydroxyl silicone oil as the main raw material, and the alkoxy silicone oil product has low cost.

[0019] 4. The alkoxy-terminated silicone oil preparation method of the present invention is suitable for producing methyl series, trifluoropropyl series and phenyl series alkoxy silicone oils, and has a wide range of applications.

[0020] 5. The product obtained by the alkoxy-terminated silicone oil preparation method of the present invention is colorless and transparent, and does not contain metal ions, which can meet the targeted application needs of downstream dealcoholized silicone rubber in special fields such as electronics and electrical appliances. Attached Figure Description

[0021] Figure 1 For the guanidine-modified silicone oil a in Example 1 1 The HNMR spectrum showed that hydrogen atoms in various chemical environments were clearly assigned, and there were no other impurity peaks, confirming that the structure was consistent with the target product.

[0022] Figure 2 The trimethoxy-terminated silicone oil in Example 5 1 HNMR spectrum; molecular structure is consistent with the target product.

[0023] Figure 3 The trimethoxy-terminated silicone oil in Example 5 29 SiNMR spectrum; molecular structure is consistent with the target product. Detailed Implementation

[0024] To make the objectives, features, and advantages of the technical solutions proposed in this invention more apparent and understandable, the embodiments of the technical solutions proposed in this invention are described clearly and completely below. Obviously, the described embodiments are only a part of the embodiments of the proposed technical solutions, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0025] In this invention 1 The equipment and testing conditions for the HNMR spectrum were as follows: a German BRUKER 500MHz nuclear magnetic resonance spectrometer (AVANCENEO500), with CDCl3 as the solvent and no internal standard added.

[0026] Example 1 N,N′-diisopropylcarbodiimide (0.2 mol, 25.24 g) was reacted with 1,3-bis(aminopropyl)tetramethyldisiloxane. (0.1 mol, 24.85 g) was reacted at 60 °C for 3 h, and unreacted small molecules were removed under reduced pressure to obtain guanidine-modified silicone oil a.

[0027]

[0028] The guanidine-modified silicone oil a 1 HNMR spectrum as follows Figure 1As shown. The chemical shifts of the hydrogen on the methyl group (1) are 1.047–1.034 ppm; the chemical shifts of the hydrogen on the methine group (2) are 2.886–2.874 ppm. The chemical shift of hydrogen on imino group 3 is 4.557 ppm; the chemical shift of hydrogen on methylene group 4 is 3.020~2.979 ppm; the chemical shift of hydrogen on methylene group 5 is 1.549~1.487 ppm; the chemical shift of hydrogen on methylene group 6 is 0.591~0.557 ppm; the chemical shift of hydrogen on methyl group 7 is 0.008~-0.007 ppm; and the chemical shift of the solvent deuterated chloroform is 7.31 ppm.

[0029] Example 2 N,N′-di-tert-butylcarbodiimide (0.24 mol, 37.02 g) was reacted with aminopropyl polysiloxane. (0.1 mol, 387.45 g) was reacted at 100 °C for 6 h, and unreacted small molecules were removed under reduced pressure to obtain guanidine-modified silicone oil b.

[0030] Example 3 N,N′-dicyclohexylcarbodiimide (0.2 mol, 41.27 g) was reacted with 1,3-bis(aminopropane)tetramethyldisiloxane. (0.1 mol, 24.85 g) was reacted at 60 °C for 3 h, and unreacted small molecules were removed under reduced pressure to obtain guanidine-modified silicone oil c.

[0031] Example 4 Di(trimethylsilyl)carbodiimide (0.2 mol, 37.28 g) was reacted with 1,3-bis(aminopropane)tetramethyldisiloxane. (0.1 mol, 24.85 g) was reacted at 60 °C for 3 h, and unreacted small molecules were removed under reduced pressure to obtain guanidine-modified silicone oil d.

[0032] Example 5 Step S1: Apply hydroxyl silicone oil (0.1 mol, 83.2 g) was dehydrated at 100 °C and 90 kPa for 2 h. Step S2: Under N2 atmosphere, add end-capping agent trimethoxysilane (0.2 mol, 24.44 g) and guanidine modified silicone oil catalyst a (1.08 g) to the above hydroxy silicone oil to carry out dehydrogenation condensation reaction, control the reaction temperature at 30℃ and the reaction time at 4 h; Step S3: After the reaction is complete, cool to room temperature and add the neutralizing agent organosilicon phosphate (1.08 g). Stir for 1 hour to obtain trimethoxy-terminated silicone oil. The product is colorless and transparent.

[0033] The obtained trimethoxy-terminated silicone oil was subjected to... 1 HNMR and 29 SiNMR characterization, such as Figure 2 and Figure 3 As shown. Figure 2 In the methoxy group, the chemical shift of H on group 1 is 3.532~3.451 ppm; the chemical shift of H on group 2, the methyl group connected to Si, is 0.028~-0.009 ppm; the chemical shift of the solvent deuterated chloroform is 7.190 ppm; and the chemical shift of water is 1.501 ppm. Figure 3 In the sample, the chemical shift of Si 1 is -85.335 ppm, and the chemical shift of Si 2 is -21.955 ppm. The structure is consistent with expectations, and the absence of Si-OH indicates that the end-capping efficiency of this reaction is >99%.

[0034] The viscosity of the product, measured using a cone-plate viscometer, is 31.02 cSt.

[0035] GPC characterization revealed: Mn = 1021 g / mol, Mw = 1543 g / mol, and molecular weight distribution was 1.51. After the obtained alkoxy silicone oil was stored at 40°C for 30 days, its viscosity was 31.04 cSt, and the viscosity change was less than 1%, which could be due to error. This indicates that the trimethoxy-terminated silicone oil has good storage stability. The product underwent NTU turbidity testing, and the turbidity was 0.2%, indicating that the trimethoxy-terminated silicone oil has good transparency.

[0036] Comparative Example 1 Step S1: Apply hydroxyl silicone oil (0.1 mol, 83.2 g) was dehydrated at 100 °C and 90 kPa for 2 h. Step S2: Under a N2 atmosphere, add the end-capping agent trimethoxysilane (0.2 mol, 24.44 g) and platinum catalyst a (the platinum catalyst a is a caster catalyst, and the amount added is 2 ppm based on platinum) to the above-mentioned hydroxyl silicone oil to carry out a dehydrogenation condensation reaction. Control the reaction temperature at 30°C and the reaction time at 4 h to obtain trimethoxy-terminated silicone oil. The product has a light yellow appearance.

[0037] After the obtained alkoxy silicone oil was stored at 40°C for 7 days, its viscosity increased from 35.12 cSt to 48.35 cSt, indicating that the trimethoxy-terminated silicone oil prepared under this condition contained residual Si-OH and did not have good storage stability.

[0038] Example 6 Step S1: Apply hydroxyl silicone oil (0.001 mol, 74.09 g) was dehydrated at 120 °C and 99 kPa for 2 h. Step S2: Under N2 atmosphere, add end-capping agent triethoxysilane (0.0024 mol, 0.004 g) and guanidine modified silicone oil catalyst b (0.01 g) to the above hydroxy silicone oil to carry out dehydrogenation condensation reaction, control the reaction temperature at 100℃ and the reaction time at 8 h; Step S3: After the reaction is complete, cool to room temperature and add neutralizing agent phosphoric acid (0.01g). Stir for 1 hour to obtain triethoxy-terminated silicone oil.

[0039] Example 7 Step S1: Apply hydroxyl silicone oil (0.1 mol, 173.60 g) was dehydrated at 120 °C and 90 kPa for 2 h. Step S2: Under N2 atmosphere, add end-capping agent methyldimethoxysilane (0.24 mol, 25.49 g) and guanidine modified silicone oil catalyst c (1.99 g) to the above hydroxyl silicone oil to carry out dehydrogenation condensation reaction, control the reaction temperature at 30℃ and the reaction time at 4 h; Step S3: After the reaction is complete, cool to room temperature and add glutaric acid (1.99 g) as a neutralizing agent. Stir for 1 h to obtain methyldimethoxy-terminated silicone oil.

[0040] Example 8 Step S1: Apply hydroxyl silicone oil (0.1 mol, 151.40 g) was dehydrated at 120 °C and 90 kPa for 4 h. Step S2: Under N2 atmosphere, add end-capping agent methyldiethoxysilane (0.24 mol, 32.22 g) and guanidine modified silicone oil catalyst d (1.86 g) to the above hydroxyl silicone oil to carry out dehydrogenation condensation reaction, control the reaction temperature at 100℃ and the reaction time at 4 h; Step S3: After the reaction is complete, cool to room temperature and add neutralizing agent and valeric acid (1.86 g). Stir for 2 h to obtain methyldiethoxy-terminated silicone oil.

Claims

1. A guanidine-modified silicone oil catalyst, characterized in that, The structure is as follows: ； Where 1≤p≤50, and R is any one of isopropyl, tert-butyl, cyclohexyl or trimethylsilyl.

2. The guanidine-modified silicone oil catalyst according to claim 1, characterized in that, The synthetic route of the guanidine-modified silicone oil catalyst is as follows: carbodiimide molecules are reacted with aminopropyl polysiloxane at 60~100℃ for 3~6 h, and unreacted small molecules are removed under reduced pressure to obtain the guanidine-modified silicone oil catalyst. The carbodiimide molecule is selected from any one of N,N′-diisopropylcarbodiimide, N,N′-ditert-butylcarbodiimide, N,N′-dicyclohexylcarbodiimide or di(trimethylsilyl)carbodiimide; The structure of the aminopropyl polysiloxane is as follows: ； Where 1≤p≤50; the molar ratio of the carbodiimide molecule to aminopropyl polysiloxane is 2~2.2:

1.

3. A method for preparing an alkoxy-terminated silicone oil, characterized in that, Hydroxy silicone oil is dehydrated, and then, under a N2 atmosphere, a capping agent is added to the dehydrated hydroxy silicone oil and a guanidine-modified silicone oil catalyst as described in any one of claims 1-2 is carried out in a dehydrogenation condensation reaction. After the reaction is completed, the temperature is lowered to room temperature and a neutralizing agent is added to obtain the alkoxy-capped silicone oil.

4. The method for preparing alkoxy-terminated silicone oil according to claim 3, characterized in that, Includes the following steps: Step S1: Dehydrate the hydroxyl silicone oil at 100~120℃ and a vacuum of 90~99 kPa for 2~4 h. Step S2: Under a N2 atmosphere, add a capping agent and the guanidine-modified silicone oil catalyst as described in any one of claims 1-2 to the dehydrated hydroxyl silicone oil from step S1 to carry out a dehydrogenation condensation reaction; control the reaction temperature at 30~100℃ and the reaction time at 4~8h. Step S3: After the reaction is complete, cool to room temperature and add a neutralizing agent. Stir for 1-2 hours to obtain the alkoxy-terminated silicone oil.

5. The method for preparing alkoxy-terminated silicone oil according to claim 3, characterized in that, The structure of the hydroxyl silicone oil is as follows: ； R1, R2, R3, and R4 are any one of -CH3, -CH2CH2CF3, and -C6H5, and are mutually independent, with 10 ≤ m ≤ 1000; The molecular structure of the alkoxy-terminated silicone oil is as follows: ； Among them, R5, R6, and R7 are any one of methyl, methoxy, and ethoxy, and methyl is not used at the same time, and 10≤n≤1000.

6. The method for preparing alkoxy-terminated silicone oil according to claim 3, characterized in that, The capping agent is any one of trimethoxysilane, triethoxysilane, methyldimethoxysilane, or methyldiethoxysilane.

7. The method for preparing alkoxy-terminated silicone oil according to claim 3, characterized in that, The molar ratio of the hydroxyl silicone oil to the end-capping agent is 1:2 to 2.4; the amount of the guanidine-modified silicone oil catalyst added is 0.01% to 1% of the total mass of the reaction system, wherein the total mass of the reaction system is the total mass of the hydroxyl silicone oil, end-capping agent and catalyst before dehydration.

8. The method for preparing alkoxy-terminated silicone oil according to claim 3, characterized in that, The neutralizing agent is any one of organosilicon phosphate, phosphoric acid, glutaric acid, and valeric acid, and the amount added is 0.01% to 1% of the total mass of the reaction system.

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