A simple preparation method of hydroxyalkyl-terminated polysiloxane

Abstract

The invention relates to a simple preparation method of hydroxyl-terminated polysiloxane. The method directly uses dimethylchlorosilane and double-bond alcohol as raw materials, firstly performs alcoholysis reaction on the dimethylchlorosilane and the double-bond alcohol, and then the alcoholysis product itself undergoes hydrosilylation reaction and then reacts with hydroxyl-terminated polysiloxane, thereby avoiding the side reaction of hydroxyl groups in a ring-opening polymerization method and the step of synthesizing hydrogen-terminated polysiloxane by hydrosilylation method in the prior art, and omitting the existing reaction steps of hydroxyl protection and deprotection. The method has the advantages of low cost, simple operation, mild reaction conditions, simple post-treatment, easy control of product batch stability, good product quality, strong practicality, and the like, and is suitable for industrial production.

Description

Technical Field

[0001] The invention relates to a simple preparation method of hydroxyalkyl-terminated polysiloxane, belonging to the technical field of organic silicon polymers. Background Art

[0002] Polysiloxane is a type of polymer with a main chain structure of Si-O-Si, and is the most important type of raw material / product in silicone materials. Silicone materials based on polysiloxane (such as silicone oil, silicone rubber, etc.) have many excellent properties, such as high and low temperature resistance, aging resistance, weather resistance, hydrophobicity, flame retardancy and physiological inertness, etc. They are used in sealing, bonding, lubrication, demoulding, defoaming, inert filling, etc., and are widely used in aerospace, electronics and electrical, construction, medical, food and other industries.

[0003] In order to expand the application range of polysiloxane, functional units are usually introduced into polysiloxane to modify it to prepare functionalized polysiloxane. Hydroxyl polysiloxane is a typical representative. Hydroxyl groups are modified on the end groups or side chains of polysiloxane, and can react with isocyanate, carboxylic acid and other groups to prepare silicone-modified polyurethane and polyester materials. Hydroxyl-terminated polysiloxane is generally prepared by two methods. One is to first prepare a hydroxyl-terminated agent, and then prepare it by a balanced reaction with a siloxane mixed ring or linear body; the other is to first prepare a hydrogen-terminated polysiloxane, and then prepare it by a hydrosilylation reaction with an alcohol containing a double bond. However, the preparation steps of the hydroxyl-terminated agent in the former method are complicated and costly, and the hydroxyl group is prone to side reactions during the polymerization process, and the batch stability of the obtained product is poor; the latter method must protect the hydroxyl group before hydrosilylation, and then deprotect it after hydrosilylation. The process is complicated, the cost is high, the reaction cycle is long, and it is not suitable for industrial production.

[0004] Chinese patent document CN110922600A discloses a class of hydroxyl organosilicon compounds and their preparation methods and applications. Hydroxyl organosilicon compounds include hydroxyl silane compounds, hydroxyl linear polysiloxanes or hydroxyl silicone resins. This method requires amino organosilicon compounds / polymers as starting materials and is obtained by ring-opening reaction with epoxy compounds. The cost is high, the reaction cycle is long, and it is not suitable for industrial production. Summary of the invention

[0005] In view of the shortcomings of the prior art, especially the complex preparation steps, high cost, side reactions of hydroxyl groups in the polymerization process, and unstable batches, the present invention provides a simple preparation method for hydroxyl-terminated polysiloxane.

[0006] The preparation method of the present invention does not require the hydroxyl protection and deprotection of the existing method, avoids the side reaction of the hydroxyl group in the existing ring-opening polymerization, has simple process, mild reaction, low cost, good batch stability, high production efficiency, safety and economy, and is suitable for industrial production.

[0007] The technical solution of the present invention is as follows:

[0008] A simple method for preparing hydroxyl-terminated polysiloxane comprises the following steps:

[0009] (1) Dimethylchlorosilane and an organic solvent are uniformly mixed to obtain a mixed solution, and a double-bond-containing alcohol is slowly added dropwise to the mixed solution in a cold water bath. After the addition is completed, the mixture is stirred and reacted at room temperature for 1 to 5 hours to obtain an organic solution of an alcoholysis product;

[0010] (2) adding a hydrosilylation catalyst to the organic solution of the alcoholysis product, heating the reaction for 0.5 to 24 hours, and obtaining an organic solution of the hydrosilylation product;

[0011] (3) Adding hydroxyl-terminated polysiloxane to an organic solution of a hydrosilylation product, adding a catalyst, heating and stirring the solution for 20 minutes to 24 hours, returning the temperature to room temperature after the reaction is completed, and removing low-boiling substances by vacuum distillation to obtain hydroxyl-terminated polysiloxane.

[0012] Preferably according to the present invention, in step (1), the organic solvent is selected from n-hexane, petroleum ether, toluene, xylene, tetrahydrofuran, ether, dioxane, dichloromethane, chloroform, dimethyl sulfoxide or solvent oil.

[0013] Preferably, according to the present invention, in step (1), the structural formula of the alcohol containing a double bond is shown in Formula I below:

[0014]

[0015] Preferably according to the present invention, in step (1), the volume ratio of the organic solvent to dichlorosilane is 0 to 1000:1.

[0016] Further preferably, in step (1), the volume ratio of the organic solvent to dichlorosilane is 50 to 800:1.

[0017] Further preferably, in step (1), the volume ratio of the organic solvent to dichlorosilane is 50 to 200:1.

[0018] Preferably, according to the present invention, step (1) can also be carried out without the participation of an organic solvent, that is, the amount of organic solvent used is 0.

[0019] Preferably according to the present invention, in step (1), the molar ratio of the alcohol containing a double bond to dimethylsilane is (1-3):(1-3).

[0020] Most preferably, in step (1), the molar ratio of the alcohol containing a double bond to dimethylsilane is 1:1.

[0021] Preferably, according to the present invention, in step (1), the by-product hydrogen chloride generated is absorbed in the tail gas portion using water or alkaline solution.

[0022] Preferably according to the present invention, in step (2), the hydrosilylation catalyst is a platinum, palladium, iridium metal catalyst, or chloroplatinic acid, or a Karstedt catalyst.

[0023] Further preferably, in step (2), the hydrosilylation catalyst is chloroplatinic acid or Karstedt catalyst.

[0024] Preferably according to the present invention, in step (2), the amount of the hydrosilylation catalyst used is 1 to 100 ppm, calculated based on the mass ratio of the alcoholysis product.

[0025] Preferably according to the present invention, in step (2), the heating reaction temperature is 60 to 120°C.

[0026] According to the preferred embodiment of the present invention, in step (3), the hydroxyl-terminated polysiloxane has a structural formula as shown in Formula II below:

[0027]

[0028] In the formula, R 1 , R 2 , R 3 , R 4 It is methyl, ethyl, phenyl, trifluoropropyl, and ethyl nitrile.

[0029] Preferably according to the present invention, in step (3), the molecular weight of the hydroxyl-terminated polysiloxane is 500 to 500,000 g / mol.

[0030] Preferably, according to the present invention, in step (3), the molar ratio of the hydroxyl group in the hydroxyl-terminated polysiloxane to the dimethylchlorosilane in the hydrosilylation product is 1:2-5.

[0031] Preferably according to the present invention, in step (3), the catalyst is selected from organic amines, organic tin, trifluoromethanesulfonic acid, and acidic resins.

[0032] Preferably, according to the present invention, in step (3), the amount of the catalyst used is 0.05wt% to 5wt% of the mass ratio of the hydroxyl-terminated polysiloxane.

[0033] Preferably, in step (3), the heating and stirring reaction temperature is 80-150°C.

[0034] The structural formula of the hydroxyl-terminated polysiloxane obtained by the present invention through simple steps is shown in the following formula III:

[0035]

[0036] In the formula, R 1 ~R 4 is one of the substituents selected from hydrogen, a straight-chain hydrocarbon group having 1 to 18 carbon atoms, a branched alkyl group or a cyclic alkyl group, a linear or branched unsaturated hydrocarbon group having 2 to 10 carbon atoms containing one or more unsaturated double bonds, an aromatic hydrocarbon group having 6 to 12 carbon atoms, or the above substituents containing heteroatoms such as S, N, O, and F; R 1 ~R 4 the same or different; X is selected from hydrogen, a straight-chain hydrocarbon group having 1 to 18 carbon atoms, a branched alkyl group or a cyclic alkyl group, a linear or branched unsaturated hydrocarbon group having 2 to 10 carbon atoms containing one or more unsaturated double bonds, or one of the above substituents containing S, N, O, or F heteroatoms; n ranges from 0 to 3000.

[0037] A hydroxyl-terminated polysiloxane is prepared by the method.

[0038] The technical features and advantages of the present invention are as follows:

[0039] 1. The present invention directly uses dimethylchlorosilane and alcohol containing double bonds as raw materials, dimethylchlorosilane and alcohol containing double bonds are first subjected to alcoholysis reaction, the alcoholysis product itself undergoes hydrosilylation reaction, and then reacts with hydroxyl-terminated polysiloxane, thereby avoiding the side reaction of hydroxyl groups in the ring-opening polymerization method and the step of synthesizing hydrogen-terminated polysiloxane by hydrosilylation method in the prior art, and omitting the existing hydroxyl protection and deprotection reaction steps, and has the advantages of low cost, simple operation, mild reaction conditions, simple post-treatment, easy control of product batch stability, good product quality, strong practicality, etc., and is suitable for industrial production;

[0040] 2. The final product of the present invention, hydroxyalkyl-terminated polysiloxane, has a high yield, and the reaction yield is above 95%. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 This is the H NMR spectrum of the hydroxypropyl-terminated polysiloxane obtained in Example 1;

[0042] Figure 2 This is the H-NMR spectrum of the 1-methylhydroxypropyl-terminated polysiloxane obtained in Example 3;

[0043] Figure 3 This is the H-NMR spectrum of the (3-hydroxyethoxypropyl)-terminated polysiloxane obtained in Example 4. DETAILED DESCRIPTION

[0044] The present invention is further described below in conjunction with specific examples, but the protection scope of the present invention is not limited thereto.

[0045] Example 1

[0046] The preparation method of hydroxypropyl terminated polysiloxane comprises the following steps:

[0047] (1) After dimethylchlorosilane (4.730 g, 0.05 mol) and 100 mL of toluene were mixed evenly, allyl alcohol (2.904 g, 0.05 mol) was slowly added dropwise to the mixed solution in a cold water bath. After the addition was completed, the mixture was stirred and reacted at room temperature for 2 h. The generated byproduct hydrogen chloride was absorbed at the tail gas part with alkaline solution. After the reaction was completed, a toluene solution of the alcoholysis product was obtained;

[0048] (2) adding 3 ppm chloroplatinic acid (isopropanol solution) to the toluene of the alcoholysis product and reacting at 90° C. for 5 h to obtain a toluene solution of the hydrosilylation product;

[0049] (3) Add 125 g of hydroxyl-terminated polydimethylsiloxane with a molecular weight of 5000 g / mol to the toluene solution of the hydrosilylation product, add dibutyltin dilaurate (0.125 g) and stir the mixture at 100° C. for 8 h. After the reaction is completed, return the mixture to room temperature and remove low-boiling substances by vacuum distillation to obtain 128.5 g of hydroxypropyl-terminated polysiloxane with a yield of 96.9%.

[0050] The H NMR spectrum of the obtained hydroxypropyl terminated polysiloxane is as follows: Figure 1 As shown, through Figure 1 It can be seen that the present invention successfully synthesizes hydroxyl-terminated polysiloxane directly using dimethylchlorosilane and double-bond-containing alcohol as raw materials.

[0051] Example 2

[0052] The preparation method of hydroxypropyl terminated polysiloxane comprises the following steps:

[0053] (1) After dimethylchlorosilane (4.730 g, 0.05 mol) and 100 mL of toluene were mixed evenly, allyl alcohol (2.904 g, 0.05 mol) was slowly added dropwise to the mixed solution in a cold water bath. After the addition was completed, the mixture was stirred and reacted at room temperature for 2 h. The generated byproduct hydrogen chloride was absorbed at the tail gas part with alkaline solution. After the reaction was completed, a toluene solution of the alcoholysis product was obtained;

[0054] (2) adding 3 ppm chloroplatinic acid (isopropanol solution) to the toluene of the alcoholysis product and reacting at 90° C. for 5 h to obtain a toluene solution of the hydrosilylation product;

[0055] (3) Add 50 g of hydroxyl-terminated polydimethylsiloxane with a molecular weight of 2000 g / mol to the toluene solution of the hydrosilylation product, add an acidic resin (0.5 g), stir and react at 90° C. for 8 h, return to room temperature after the reaction, remove low-boiling substances by vacuum distillation, and obtain 55.6 g of hydroxypropyl-terminated polysiloxane. Yield: 96.4%.

[0056] Example 3

[0057] The preparation method of 1-methylhydroxypropyl terminated polysiloxane comprises the following steps:

[0058] (1) After dimethylchlorosilane (4.730 g, 0.05 mol) and 100 mL of xylene were mixed evenly, 1-methylallyl alcohol (3.605 g, 0.05 mol) was slowly added dropwise to the mixed solution in a cold water bath. After the addition was completed, the mixture was stirred and reacted at room temperature for 5 h. The generated byproduct hydrogen chloride was absorbed at the tail gas part with alkaline solution. After the reaction was completed, a toluene solution of the alcoholysis product was obtained;

[0059] (2) adding 5 ppm of Karstedt catalyst to the xylene of the alcoholysis product and reacting at 90° C. for 3 h to obtain a toluene solution of the hydrosilylation product;

[0060] (3) Add 125 g of hydroxyl-terminated polydimethylsiloxane with a molecular weight of 5000 g / mol to a xylene solution of the hydrosilylation product, add tri-n-butylamine (1.25 g), and stir the reaction at 100° C. for 8 h. After the reaction is completed, return the temperature to room temperature, and remove low-boiling substances by vacuum distillation to obtain 129.6 g of 1-methylhydroxypropyl-terminated polysiloxane with a yield of 97.2%.

[0061] The H NMR spectrum of the prepared 1-methylhydroxypropyl terminated polysiloxane is as follows: Figure 2 As shown, through Figure 2 It can be seen that the present invention successfully synthesizes hydroxyl-terminated polysiloxane directly using dimethylchlorosilane and double-bond-containing alcohol as raw materials.

[0062] Example 4

[0063] The preparation method of (3-hydroxyethoxypropyl) terminated polysiloxane comprises the following steps:

[0064] (1) After dimethylchlorosilane (4.730 g, 0.05 mol) and 50 mL of xylene were mixed evenly, allyl hydroxyethyl ether (5.106 g, 0.05 mol) was slowly added dropwise to the mixed solution in a cold water bath. After the addition was completed, the mixture was stirred and reacted at room temperature for 5 h. The generated byproduct hydrogen chloride was absorbed at the tail gas site with alkaline solution. After the reaction was completed, a toluene solution of the alcoholysis product was obtained;

[0065] (2) adding 10 ppm of Karstedt catalyst to the xylene of the alcoholysis product and reacting at 70° C. for 3 h to obtain a toluene solution of the hydrosilylation product;

[0066] (3) Add 125 g of hydroxyl-terminated polydimethylsiloxane with a molecular weight of 5000 g / mol to the toluene solution of the hydrosilylation product, add trifluoromethylsulfonic acid (0.25 g), and stir the reaction at 100° C. for 8 h. After the reaction is completed, return the temperature to room temperature, and remove low-boiling substances by vacuum distillation to obtain 130.2 g of (3-hydroxyethoxypropyl)-terminated polysiloxane with a yield of 96.5%.

[0067] The H NMR spectrum of the obtained (3-hydroxyethoxypropyl) terminated polysiloxane is as follows: Figure 3 As shown, through Figure 3 It can be seen that the present invention successfully synthesizes hydroxyl-terminated polysiloxane directly using dimethylchlorosilane and double-bond-containing alcohol as raw materials.

Claims

1. A simple method for preparing a hydroxyl-terminated polysiloxane, comprising the following steps: (1) Dimethylchlorosilane and an organic solvent are mixed evenly to obtain a mixed solution. In a cold water bath, an alcohol containing a double bond is slowly added dropwise to the mixed solution. After the addition is completed, the mixture is stirred at room temperature for 1 to 5 hours to obtain an organic solution of an alcoholysis product. (2) adding a hydrosilylation catalyst to the organic solution of the alcoholysis product, heating the reaction for 0.5 to 24 hours, and obtaining an organic solution of the hydrosilylation product; (3) adding a hydroxyl-terminated polysiloxane to an organic solution of a hydrosilylation product, adding a catalyst, wherein the catalyst is selected from an organic amine, an organic tin, trifluoromethanesulfonic acid, and an acidic resin, and the amount of the catalyst is 0.05 wt% to 5 wt% of the mass ratio of the hydroxyl-terminated polysiloxane, heating and stirring the reaction for 20 min to 24 h, returning the temperature to room temperature after the reaction is completed, and removing low-boiling substances by reduced pressure distillation to obtain a hydroxyl-terminated polysiloxane; The structural formula of the hydroxyl-terminated polysiloxane is shown in the following formula III: Formula III, In the formula, R 1 ~R 4 is a straight-chain hydrocarbon group, a branched-chain alkyl group or a cyclic alkyl group having 1 to 18 carbon atoms, or an aromatic hydrocarbon group having 6 to 12 carbon atoms; R 1 ~R 4 are the same or different; X is selected from a linear hydrocarbon group, a branched alkyl group or a cyclic alkyl group having 1 to 18 carbon atoms; and n ranges from 0 to 3000.

2. The preparation method according to claim 1, characterized in that: In step (1), the organic solvent is selected from n-hexane, petroleum ether, toluene, xylene, tetrahydrofuran, ether, dioxane, dichloromethane, chloroform, and dimethyl sulfoxide.

3. The preparation method according to claim 1, characterized in that: In step (1), the structural formula of the alcohol containing a double bond is shown in Formula I below: Formula Ⅰ.

4. The preparation method according to claim 1, characterized in that: In step (1), the volume ratio of the organic solvent to dimethylchlorosilane is 5 to 200:

1.

5. The preparation method according to claim 1, characterized in that: In step (1), the molar ratio of the double bond-containing alcohol to dimethylchlorosilane is (1-3): (1-3).

6. The preparation method according to claim 1, characterized in that: In step (2), the hydrosilylation catalyst is a platinum, palladium, iridium metal catalyst, or chloroplatinic acid, or a Karstedt catalyst.

7. The preparation method according to claim 1, characterized in that: In step (2), the amount of the hydrosilylation catalyst is 1-100 ppm, based on the mass ratio of the alcoholysis product, and the heating reaction temperature is 60-120°C.

8. The preparation method according to claim 1, characterized in that: In step (3), the hydroxyl-terminated polysiloxane has the structural formula shown in the following formula II: Formula II, In the formula, R 1 , R 2 , R 3 , R 4 is methyl, ethyl, phenyl, trifluoropropyl, nitrileethyl; The molecular weight of the hydroxyl-terminated polysiloxane is 500-500000 g / mol.

9. The preparation method according to claim 1, characterized in that: In step (3), the molar ratio of the hydroxyl group in the hydroxyl-terminated polysiloxane to the dimethylchlorosilane in the hydrosilylation product is 1:2-5, and the heating and stirring reaction temperature is 80-150°C.

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