CN111378135A - A kind of preparation method of low-viscosity alkoxy-terminated polydimethylsiloxane - Google Patents

Abstract

The invention provides a preparation method of low-viscosity alkoxy-terminated polydimethylsiloxane, comprising the following steps: (1) mixing DMC and hexamethyldisiloxane, heating up, adding phosphoric acid dropwise, stirring and refluxing Remove water to obtain silicophosphate terminator; (2) heat up the linear body, add potassium hydroxide aqueous solution, stir the polycondensation reaction, add silicophosphate terminator, and continue the reaction to obtain hydroxy silicone oil; (3) add hydrogen-containing double head to Hydroxy silicone oil, stir until the mixture is uniform, add phosphazene catalyst at the temperature, add ammonia gas terminator to the stirring reaction, and continue the reaction to obtain low-viscosity hydrogen-containing silicone oil; (4) Mix low-viscosity hydrogen-containing silicone oil, vinyltrimethoxysilane, platinum The catalysts are mixed, and the reaction is stirred to obtain a low viscosity alkoxy terminated polydimethylsiloxane. The low-viscosity alkoxy-terminated polydimethylsiloxane prepared by the invention has lower viscosity, better hardness, elongation at break and stability.

Description

A kind of preparation method of low-viscosity alkoxy-terminated polydimethylsiloxane

technical field

The invention relates to a preparation method of low-viscosity alkoxy-terminated polydimethylsiloxane.

Background technique

Polydimethylsiloxane (PDMS, polydimethylsiloxane) is a hydrophobic silicone material. It has applications in various fields such as medicine, daily chemicals, food, construction, etc. It has hundreds of derivatives. The commonly used polysiloxanes are: polydimethylsiloxane, cyclomethylsiloxane , aminosiloxane, polymethylphenylsiloxane, polyether polysiloxane copolymer. The modified polydimethylsiloxane is a chemical reaction on the branch or main chain of the silicone oil to introduce different functional groups. Due to the introduction of various special functional groups, the modified polydimethylsiloxane is better. Many special excellent performance. At present, a common practice is to perform end-capping modification on polydimethylsiloxane, and the types of end-capping include terminal hydroxyl groups, terminal methyl groups, terminal alkoxy groups, allylsilyl groups, and the like.

SUMMARY OF THE INVENTION

The technical problem to be solved by the present invention is to provide a preparation method of low-viscosity alkoxy-terminated polydimethylsiloxane, and the prepared low-viscosity alkoxy-terminated polydimethylsiloxane has lower viscosity, and good hardness, elongation at break and stability.

For solving the above-mentioned technical problems, the technical scheme of the present invention is:

A preparation method of low-viscosity alkoxy-terminated polydimethylsiloxane, comprising the following steps:

(1) after mixing DMC and hexamethyldisiloxane, the temperature is raised to 160-180 ℃, phosphoric acid is added dropwise, stirred for 6-8 hours and refluxed to remove water to obtain a silicophosphate terminator;

(2) the linear body is heated up to 130-150 ℃, after adding the potassium hydroxide aqueous solution, the polycondensation reaction is stirred, and the viscosity is monitored on-line. Before reaching the target viscosity, the silicophosphate terminator obtained in step (1) is added, and the reaction is continued for 5-50 minutes. Vacuuming and decompression distillation to remove low-boiling substances to obtain hydroxyl silicone oil;

(3) adding the hydrogen-containing double head to the hydroxy silicone oil obtained in step (2), stirring until the mixture is uniform, adding the phosphazene catalyst after the temperature is raised to 55-65 ° C, adding the ammonia gas terminator after the stirring reaction reaches the target viscosity, and continuing the reaction 3 -After 6 hours, the low-boiling substances are removed by vacuum distillation to obtain low-viscosity hydrogen-containing silicone oil;

(4) Mixing the low-viscosity hydrogen-containing silicone oil obtained in step (3), vinyltrimethoxysilane and platinum catalyst, and stirring the reaction to obtain a low-viscosity alkoxy-terminated polydimethylsiloxane.

Further, in the step (1) of the present invention, the mass ratio of DMC, hexamethyldisiloxane and phosphoric acid is (60-80):(5-15):(10-20).

Further, in the step (1) of the present invention, the stirring speed is 200-400 r/min.

Further, in the step (2) of the present invention, the mass concentration of the potassium hydroxide aqueous solution is 10%, and the mass ratio of the linear body, the potassium hydroxide aqueous solution, and the silicophosphate terminator is 40000:1:(1.5-2) .

Further, in the step (2) of the present invention, the target viscosity is 1000-1500 mPa·s.

Further, in step (3) of the present invention, the mass ratio of hydroxy silicone oil, hydrogen-containing double-head, phosphazene catalyst, and ammonia gas terminator is (70-90):(10-20):(0.1-0.6 ):(1-6).

Further, in the step (3) of the present invention, the stirring speed during the stirring reaction is 400-800 r/min.

Further, in the step (3) of the present invention, the target viscosity is 2500-3000 mPa·s.

Further, in step (4) of the present invention, the mass ratio of low-viscosity hydrogen-containing silicone oil, vinyltrimethoxysilane, and platinum catalyst is (60-80):(20-30):(0.3-0.6).

Further, in the step (4) of the present invention, the process of the stirring reaction is: firstly heated to 25-35 °C for stirring reaction for 30-40 minutes, then heated to 70-80 °C for stirring reaction for 2-3 hours, when stirring reaction The stirring speed is 300-500r/min.

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

In the invention, the hydrogen-containing double head is used as the functional material, the linear body is selected as the basic raw material to prepare the hydroxy silicone oil, and then the functional material is used to modify the polydimethylsiloxane to obtain the low-viscosity hydrogen-containing silicone oil, which is then mixed with ethylene The alkoxy-terminated polydimethylsiloxane with low viscosity, good hardness, elongation at break and stability was prepared by addition of alkoxytrimethoxysilane under the action of platinum catalyst.

Detailed ways

The present invention will be described in detail below with reference to specific embodiments. The exemplary embodiments and descriptions of the present invention are used to explain the present invention, but are not intended to limit the present invention.

Example 1

Follow the steps below to prepare low viscosity alkoxy terminated polydimethylsiloxane:

(1) After mixing DMC and hexamethyldisiloxane, the temperature was raised to 170° C., phosphoric acid was added dropwise, and stirring was performed at a speed of 300 r/min for 7 hours to remove water and reflux to obtain a silicophosphate terminator, DMC, hexamethyldisiloxane The mass ratio of alkane and phosphoric acid is 70:10:15;

(2) heating the linear body to 140° C., adding a potassium hydroxide aqueous solution with a mass concentration of 10% and then stirring the polycondensation reaction, monitoring the viscosity online, and adding the silicophosphate terminator obtained in step (1) before reaching the target viscosity of 1200 mPa·s, After continuing to react for 30 minutes, the low-boiling substance was removed by vacuum distillation to obtain hydroxy silicone oil, and the mass ratio of linear body, potassium hydroxide aqueous solution, and silicophosphate terminator was 40000:1:1.8;

(3) Add the hydrogen-containing double head to the hydroxy silicone oil obtained in step (2), stir until the mixture is uniform, add the phosphazene catalyst after the temperature is raised to 60 °C, and then add ammonia after the stirring reaction reaches the target viscosity of 2700 mPa·s at a stirring speed of 600 r/min. The gas terminator, vacuuming and decompressing distillation to remove low-boiling substances after continuing to react for 4 hours to obtain low-viscosity hydrogen-containing silicone oil, the mass ratio of hydroxy silicone oil, hydrogen-containing double-head, phosphazene catalyst, and ammonia gas terminator is 80:15: 0.3:3;

(4) Mix the low-viscosity hydrogen-containing silicone oil, vinyltrimethoxysilane and platinum catalyst obtained in step (3) with a mass ratio of 70:25:0.4, first heat to 30°C and stir for 35 minutes, and then heat to 75°C The low-viscosity alkoxy-terminated polydimethylsiloxane was obtained by stirring the reaction for 2.5 hours, and the stirring speed during the stirring reaction was 400 r/min.

Example 2

Follow the steps below to prepare low viscosity alkoxy terminated polydimethylsiloxane:

(1) After mixing DMC and hexamethyldisiloxane, the temperature was raised to 160° C., phosphoric acid was added dropwise, and the water was refluxed for 8 hours under stirring at 200 r/min to obtain a silicophosphate terminator, DMC, hexamethyldisiloxane The mass ratio of alkane and phosphoric acid is 60:5:10;

(2) heating the linear body to 130° C., adding a potassium hydroxide aqueous solution with a mass concentration of 10% and then stirring the polycondensation reaction, monitoring the viscosity on-line, and adding the silicophosphate terminator obtained in step (1) before reaching the target viscosity of 1000 mPa·s, After continuing the reaction for 5 minutes, the low-boiling substance was removed by vacuum distillation to obtain hydroxy silicone oil, and the mass ratio of linear body, potassium hydroxide aqueous solution, and silicophosphate terminator was 40000:1:1.5;

(3) Add the hydrogen-containing double head to the hydroxy silicone oil obtained in step (2), stir until the mixture is uniform, add the phosphazene catalyst after the temperature is raised to 55 °C, and then add ammonia after the stirring reaction reaches the target viscosity of 2500 mPa·s at a stirring speed of 800 r/min. Gas terminator, vacuuming and decompressing distillation to remove low-boiling substances after continuing to react for 6 hours to obtain low-viscosity hydrogen-containing silicone oil, the mass ratio of hydroxy silicone oil, hydrogen-containing double-head, phosphazene catalyst, and ammonia gas terminator is 70:10: 0.1:1;

(4) Mix the low-viscosity hydrogen-containing silicone oil, vinyltrimethoxysilane, and platinum catalyst obtained in step (3) with a mass ratio of 60:20:0.3, first heat to 25°C and stir for 40 minutes, and then heat to 70°C The low-viscosity alkoxy-terminated polydimethylsiloxane was obtained by stirring the reaction for 3 hours, and the stirring speed during the stirring reaction was 300 r/min.

Example 3

Follow the steps below to prepare low viscosity alkoxy terminated polydimethylsiloxane:

(1) After mixing DMC and hexamethyldisiloxane, the temperature was raised to 180° C., phosphoric acid was added dropwise, and stirring was performed at a speed of 400 r/min for 6 hours to remove water under reflux to obtain a silicophosphate terminator, DMC, hexamethyldisiloxane The mass ratio of alkane and phosphoric acid is 80:15:20;

(2) heating the linear body to 150° C., adding a potassium hydroxide aqueous solution with a mass concentration of 10% and then stirring the polycondensation reaction, monitoring the viscosity on-line, and adding the silicophosphate ester terminator obtained in step (1) before reaching the target viscosity of 1500 mPa·s, After continuing the reaction for 50 minutes, the low-boiling substance was removed by vacuum distillation to obtain hydroxy silicone oil, and the mass ratio of linear body, potassium hydroxide aqueous solution, and silicophosphate terminator was 40000:1:2;

(3) Add the hydrogen-containing double head to the hydroxy silicone oil obtained in step (2), stir until the mixture is uniform, add the phosphazene catalyst after the temperature is raised to 65 °C, and then add ammonia after the stirring reaction reaches the target viscosity of 3000 mPa·s at a stirring speed of 400 r/min. Gas terminator, vacuuming and decompressing distillation to remove low-boiling substances after continuing to react for 3 hours to obtain low-viscosity hydrogen-containing silicone oil, the mass ratio of hydroxy silicone oil, hydrogen-containing double-head, phosphazene catalyst, and ammonia gas terminator is 90:20: 0.6:6;

(4) Mix the low-viscosity hydrogen-containing silicone oil, vinyltrimethoxysilane, and platinum catalyst obtained in step (3) with a mass ratio of 80:30:0.6, first heat to 35° C. and stir for 30 minutes, and then heat to 80° C. The low-viscosity alkoxy-terminated polydimethylsiloxane was obtained by stirring the reaction for 2 hours, and the stirring speed during the stirring reaction was 500 r/min.

Example 4

Follow the steps below to prepare low viscosity alkoxy terminated polydimethylsiloxane:

(1) After mixing DMC and hexamethyldisiloxane, the temperature was raised to 175° C., phosphoric acid was added dropwise, and stirring was performed at a speed of 350 r/min for 7.5 hours to remove water under reflux to obtain silicophosphate terminator, DMC, hexamethyldisiloxane The mass ratio of alkane and phosphoric acid is 75:12:16;

(2) heating the linear body to 135° C., adding a potassium hydroxide aqueous solution with a mass concentration of 10% and then stirring the polycondensation reaction, monitoring the viscosity online, and adding the silicophosphate terminator obtained in step (1) before reaching the target viscosity of 1100 mPa·s, After continuing to react for 40 minutes, the low-boiling substance was removed by vacuum and reduced pressure distillation to obtain hydroxy silicone oil, and the mass ratio of linear body, potassium hydroxide aqueous solution, and silicophosphate terminator was 40000:1:1.6;

(3) Add the hydrogen-containing double head to the hydroxy silicone oil obtained in step (2), stir until the mixture is uniform, add the phosphazene catalyst after the temperature is raised to 60 °C, and then add ammonia after the stirring reaction reaches the target viscosity of 2600 mPa·s at a stirring speed of 500 r/min. Gas terminator, vacuuming and depressurizing distillation to remove low-boiling substances after continuing to react for 5 hours to obtain low-viscosity hydrogen-containing silicone oil, the mass ratio of hydroxy silicone oil, hydrogen-containing double-head, phosphazene catalyst, and ammonia gas terminator is 85:17: 0.5:5;

(4) Mix the low-viscosity hydrogen-containing silicone oil, vinyltrimethoxysilane and platinum catalyst obtained in step (3) with a mass ratio of 75:28:0.5, first heat to 30°C and stir for 35 minutes, and then heat to 75°C The low-viscosity alkoxy-terminated polydimethylsiloxane was obtained by stirring the reaction for 2.5 hours, and the stirring speed during the stirring reaction was 450 r/min.

Comparative Example 1

The difference from Example 1 is that step (3) is not included.

Comparative Example 2

The difference from Example 1 is that vinyltrimethoxysilane in step (4) is replaced by dimethylvinylsiloxane.

Performance Testing

The viscosity, hardness, elongation at break and stability of the products prepared in Examples 1-4 and Comparative Examples 1-2 were measured respectively.

The viscosity refers to GB/T 10427-2008, and is tested with a rotational viscometer.

The hardness refers to GB/T 531.1-2009, and the hardness tester is used for testing.

The elongation at break refers to GB/T 528-2009, and is tested by a universal material testing machine.

The stability test method is: measure the elongation at break of each product before and after being placed at room temperature for 12 months, calculate the change rate, change rate = (initial elongation at break - elongation at break placed at room temperature for 12 months) / The initial elongation at break × 100%, the lower the change rate, the better the stability.

The test results are shown in Table 1:

Viscosity (mPa s) Hardness (degree) Elongation at break (%) Change rate (%) Example 1 1260 35 421.8 5.22 Example 2 1320 32 420.9 5.29 Example 3 1290 34 421.2 5.27 Example 4 1300 31 420.5 5.25 Comparative Example 1 3640 35 421.7 10.46 Comparative Example 2 1260 26 395.4 5.23

Table 1

It can be seen from Table 1 that the low-viscosity alkoxy-terminated polydimethylsiloxanes prepared in Examples 1-4 of the present invention have lower viscosity, better hardness, elongation at break and stability. Part of the steps in Comparative Examples 1-2 are different from those in Example 1. Among them, the viscosity and rate of change of Comparative Example 1 are significantly increased, indicating that the hydrogen-containing double-head can effectively reduce the viscosity of the product and stabilize the product. The performance plays a better role in improving, while the hardness and elongation at break of Comparative Example 2 are significantly decreased, indicating that vinyltrimethoxysilane can play a better role in improving the hardness and elongation at break of the product.

The above-mentioned embodiments merely illustrate the principles and effects of the present invention, but are not intended to limit the present invention. Anyone skilled in the art can modify or change the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes made by those with ordinary knowledge in the technical field without departing from the spirit and technical idea disclosed in the present invention should still be covered by the claims of the present invention.

Claims (10)

1. A preparation method of low-viscosity alkoxy-terminated polydimethylsiloxane is characterized by comprising the following steps: the method comprises the following steps:

(1) heating DMC and hexamethyldisiloxane to 160-180 ℃, dripping phosphoric acid, stirring for 6-8 hours, refluxing and removing water to obtain a silicophosphate terminator;

(2) heating the linear body to 130-150 ℃, adding a potassium hydroxide aqueous solution, stirring for polycondensation reaction, monitoring the viscosity on line, adding the silicon phosphate terminating agent obtained in the step (1) before reaching the target viscosity, continuing to react for 5-50 minutes, vacuumizing, decompressing and distilling to remove low-boiling-point substances to obtain hydroxyl silicone oil;

(3) adding hydrogen-containing double end sockets into the hydroxyl silicone oil obtained in the step (2), stirring until the mixture is uniformly mixed, heating to 55-65 ℃, adding a phosphazene catalyst, stirring to react until the target viscosity is reached, adding an ammonia terminating agent, continuing to react for 3-6 hours, and then vacuumizing and distilling under reduced pressure to remove low-boiling-point substances to obtain low-viscosity hydrogen-containing silicone oil;

(4) and (4) mixing the low-viscosity hydrogen-containing silicone oil obtained in the step (3), vinyl trimethoxy silane and a platinum catalyst, and stirring to react to obtain the low-viscosity alkoxy-terminated polydimethylsiloxane.

2. The method of claim 1, wherein the alkoxy terminated polydimethylsiloxane having a low viscosity is prepared by the following steps: in the step (1), the mass ratio of DMC, hexamethyldisiloxane to phosphoric acid is (60-80): 5-15): 10-20.

3. The method of claim 1, wherein the alkoxy terminated polydimethylsiloxane having a low viscosity is prepared by the following steps: in the step (1), the stirring speed is 200-400 r/min.

4. The method of claim 1, wherein the alkoxy terminated polydimethylsiloxane having a low viscosity is prepared by the following steps: in the step (2), the mass concentration of the potassium hydroxide aqueous solution is 10%, and the mass ratio of the linear body, the potassium hydroxide aqueous solution and the silicon phosphate terminator is 40000:1 (1.5-2).

5. The method of claim 1, wherein the alkoxy terminated polydimethylsiloxane having a low viscosity is prepared by the following steps: in the step (2), the target viscosity is 1000-1500 mPas.

6. The method of claim 1, wherein the alkoxy terminated polydimethylsiloxane having a low viscosity is prepared by the following steps: in the step (3), the mass ratio of the hydroxyl silicone oil, the hydrogen-containing double end socket, the phosphazene catalyst and the ammonia terminator is (70-90): (10-20): 0.1-0.6): 1-6.

7. The method of claim 1, wherein the alkoxy terminated polydimethylsiloxane having a low viscosity is prepared by the following steps: in the step (3), the stirring speed during the stirring reaction is 400-800 r/min.

8. The method of claim 1, wherein the alkoxy terminated polydimethylsiloxane having a low viscosity is prepared by the following steps: in the step (3), the target viscosity is 2500-3000 mPas.

9. The method of claim 1, wherein the alkoxy terminated polydimethylsiloxane having a low viscosity is prepared by the following steps: in the step (4), the mass ratio of the low-viscosity hydrogen-containing silicone oil, the vinyl trimethoxy silane and the platinum catalyst is (60-80): (20-30): 0.3-0.6).

10. The method of claim 1, wherein the alkoxy terminated polydimethylsiloxane having a low viscosity is prepared by the following steps: in the step (4), the stirring reaction process is as follows: firstly heating to 25-35 ℃ and stirring for reaction for 30-40 minutes, then heating to 70-80 ℃ and stirring for reaction for 2-3 hours, wherein the stirring speed during the stirring reaction is 300-.