CN113429620B - Hydrophobic polyurethane foam modified by organosilicon compound and preparation method thereof - Google Patents

Abstract

The invention discloses hydrophobic polyurethane foam modified by an organic silicon compound and a preparation method thereof, belonging to the field of preparation and application of oil-water separation materials.A carbamate group is generated by the reaction of an isocyanate group and a hydroxyl group, an organic silicon chain segment is introduced into a polyurethane main chain, and then the polyurethane foam is prepared by the reaction with water; after chromic acid etching, silane with long carbon chains is grafted on the surface of the polyurethane foam, and the silane with long carbon chains is hydrolyzed to generate silicon hydroxyl which can be dehydrated and condensed with hydroxyl on the surface of the polyurethane foam, so that the hydrophobic polyurethane foam modified by organic silicon is obtained. The invention reasonably introduces the silicon compound into the polyurethane system, thereby improving the oil-water selectivity of the polyurethane foam and improving the hydrophobicity and lipophilicity of the polyurethane foam. The test results of the morphology characterization and the water contact angle also prove that the hydrophobic polyurethane foam prepared by the invention can obviously improve the problem of poor oil-water selectivity of the polyurethane foam in the oil-water separation process.

Description

Hydrophobic polyurethane foam modified by organosilicon compound and preparation method thereof

technical field

The invention belongs to the field of preparation and application of oil-water separation materials, and relates to a hydrophobic polyurethane foam modified by an organosilicon compound and a preparation method thereof.

Background technique

With the rapid development of economy and society, environmental issues are becoming more and more noteworthy. Frequent oil spills and the discharge of oily wastewater have caused great harm to the water environment, resulting in the emergence of many studies on oil-water separation. Among many studies, adsorption has attracted much attention due to its simple implementation and the recyclability of oil products. Traditional oil-absorbing materials have disadvantages such as low oil absorption ratio and poor durability, which limit the practical application of materials. Therefore, stable, durable, and high-capacity substrates are currently in urgent need of development for oil-water separation.

Polyurethane foam is a type of polyurethane product with mature technology, low material density, excellent elasticity and rich pore structure, and can be used repeatedly as a stable oil-water separation material. However, polyurethane foam has a certain degree of hydrophilicity, which makes it absorb water while absorbing oil, resulting in poor oil-water selectivity, so hydrophobic modification is required.

Contents of the invention

The object of the present invention is to overcome the disadvantage of poor oil-water selectivity of oil-water separation substrate polyurethane foam in the above-mentioned prior art, and provide a hydrophobic polyurethane foam modified with organosilicon compounds and a preparation method thereof.

In order to achieve the above object, the present invention adopts the following technical solutions to achieve:

A preparation method of a hydrophobic polyurethane foam modified by an organosilicon compound, comprising the following steps:

Step 1) mixing the isocyanate-terminated polyurethane prepolymer with the dried organosilicon compound, and obtaining the organosilicon-modified polyurethane prepolymer after the mixing reaction;

Step 2) mixing and stirring the silicone-modified polyurethane prepolymer and deionized water to obtain a mixed solution, and foaming and curing the mixed solution to obtain a polyurethane foam;

Step 3) After the polyurethane foam is washed and dried in sequence, it is immersed in chromic acid for etching, and after etching, it is washed and dried in sequence, and the polyurethane foam after the second drying is impregnated with long carbon chain silicone The grafting reaction is carried out in the compound solution, and the hydrophobic polyurethane foam modified by the organosilicon compound is obtained after drying.

Preferably, in step 1), the organosilicon compound is hydroxyl-terminated polydimethylsiloxane or aminopropyl-terminated polydimethylsiloxane.

Preferably, in step 1),

When the organosilicon compound is hydroxyl-terminated polydimethylsiloxane, the mixing reaction conditions are: temperature 70-80°C, time 40-60min;

When the organosilicon compound is aminopropyl-terminated polydimethylsiloxane, the mixing reaction conditions are as follows: temperature 20-35° C., time 40-60 minutes.

Preferably, in step 1), the mass ratio of the isocyanate-terminated polyurethane prepolymer to the dried organosilicon compound is (4-20):1;

In step 2), when the silicone-modified polyurethane prepolymer is mixed with deionized water, the mass ratio of deionized water to isocyanate-terminated polyurethane prepolymer is (1.5-2.5):1.

Preferably, in step 3), the long carbon chain organosilicon compound is hexadecyltrimethoxysilane or octadecyltrichlorosilane.

Preferably, in step 3), the solvent in the long carbon chain organosilicon compound solution is cyclohexane;

In the long carbon chain organosilicon compound solution, the volume ratio of the long carbon chain organosilicon compound to cyclohexane is (1-5):100.

Preferably, in step 3),

During etching, the feed ratio of polyurethane foam to chromic acid is (0.8-1.2) g: 30ml;

The concentration of chromic acid is 10-100g/L, and the etching time is 0.5-3min.

Preferably, during the preparation of the silicone-modified polyurethane prepolymer in step 1), acetone is added dropwise to the mixed solution after the mixing reaction;

The feeding ratio of acetone to isocyanate-terminated polyurethane prepolymer is (0.18-0.3) ml: 10 g.

Preferably, in step 1), the drying conditions of the organosilicon compound are: temperature 110-140° C., time 2-4 hours.

In step 2), the stirring conditions are: temperature 20-35° C., time 40-60 s; the foaming and curing conditions are: temperature 20-35° C., time 5-10 minutes.

In step 3), the washing before etching is to alternately wash with deionized water and ethanol for 2 to 3 times; the washing after etching is to wash with deionized water;

Drying conditions are: temperature 60 ~ 80 ℃, time 4 ~ 6h;

The dipping conditions are: temperature 20-35°C, time 30-60min.

An organosilicon compound-modified hydrophobic polyurethane foam prepared according to the preparation method of the organosilicon compound-modified hydrophobic polyurethane foam, the water contact angle of the organosilicon compound-modified hydrophobic polyurethane foam is in the range of 138° to 148° °.

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

The invention discloses a method for preparing hydrophobic polyurethane foam modified by organosilicon compounds. Firstly, the hydroxyl-terminated polydimethylsiloxane is used to react with the isocyanate-terminated polyurethane prepolymer, wherein the isocyanate group and the hydroxyl group React to form urethane groups, introduce silicone segments into the polyurethane main chain, and then react with water to prepare polyurethane foam; after chromic acid etching, chromic acid etching can increase the surface roughness of polyurethane foam and generate hydroxyl groups , and then graft long carbon chain silanes on the surface of the polyurethane foam, and the hydrolysis of the long carbon chain silanes produces silicon hydroxyl groups that can dehydrate and condense with the hydroxyl groups on the surface of the polyurethane foam to obtain organosilicon-modified hydrophobic polyurethane foams. The invention reasonably introduces the silicon compound into the polyurethane system, thereby improving the oil-water selectivity of the polyurethane foam and improving the hydrophobicity and lipophilicity of the polyurethane foam. The test results of morphology characterization and water contact angle also prove that the hydrophobic polyurethane foam prepared by the present invention can significantly improve the problem of poor oil-water selectivity of the polyurethane foam during the oil-water separation process.

Further, the proportion of hydroxyl-terminated polydimethylsiloxane and isocyanate-terminated polyurethane prepolymer first considers the isocyanate equivalent in the polyurethane prepolymer, and requires the presence of isocyanate groups in the silicone-modified polyurethane prepolymer. In order to react with water in the foaming process. Secondly, in terms of reaction time, if the reaction time is short, the reaction between the hydroxyl group and the isocyanate group is complete. If the reaction time is long, the viscosity of the system will increase, which will affect the subsequent foaming process.

Furthermore, when mixing with deionized water in step 2, if the mass ratio of water is too large, there will be water remaining after the reaction; if the water is too small, the system will viscous and solidify rapidly during stirring, and the cells will be uneven and fine.

Further, the concentration and time of the chromic acid solution are selected. When the concentration of the chromic acid solution is low, it is difficult to achieve the effect of roughening the polyurethane foam surface or the effect is not obvious; If it causes great damage, the mechanical strength will decrease, which is not conducive to the repeated use of foam.

Further, the concentration of the long carbon chain organic silicon solution is optimized. When the concentration of the long carbon chain organic silicon solution is low, the effect is not obvious. When the concentration is too high, there is limited room for improvement and waste of materials.

Further, the time of the grafting reaction is optimized, the grafting reaction time is short, the silicone segment cannot be well grafted on the polyurethane foam, and when the grafting reaction time is long, the silicone segment will Hydrolytic condensation seriously affects the preparation effect of polyurethane foam.

The invention also discloses a hydrophobic polyurethane foam modified by an organosilicon compound, which is prepared based on the above method. The water contact angle of the hydrophobic polyurethane foam modified by an organosilicon compound ranges from 138° to 148°. Compared with the existing unmodified polyurethane foam, the water contact angle is significantly increased, indicating that the hydrophobicity is significantly enhanced. On the one hand, the strong acid etching solution makes the polyurethane surface rough and obtains a micro-nano rough structure. On the other hand, the silicone The introduction of the compound further reduced the surface energy of the polyurethane foam, which was modified with two-step silicone, resulting in improved hydrophobicity.

Description of drawings

Fig. 1 is the preparation roadmap of the hydrophobic polyurethane foam of organosilicon compound modification;

Fig. 2 is the infrared spectrogram of the polyurethane foam prepared by different proportions of hydroxyl-terminated polydimethylsiloxane modified polyurethane prepolymer (the added mass of hydroxyl-terminated polydimethylsiloxane is the isocyanate-terminated polyurethane prepolymer 0%, 5%, 10% of mass);

Fig. 3 is the infrared spectrogram of Si-PUF-10 before and after etching and impregnation hexadecyltrimethoxysilane;

Figure 4 is a scanning electron microscope image, (a) Si-PUF-0 magnified 150 times, (b) Si-PUF-0 magnified 5000 times, (c) Si-PUF-10 magnified 150 times, ( d) Si-PUF-10 magnified 5000 times;

Fig. 5 is the test result figure of water contact angle, (a) is the water contact angle without adding organosilicon compound, (b) is the water contact angle of the polyurethane foam that adds Si-PUF-10 and makes before etching, ( c) is the water contact angle of the silicone compound modified hydrophobic polyurethane foam finally prepared by adding Si-PUF-10.

Detailed ways

The present invention is described in further detail below in conjunction with accompanying drawing:

Example 1

A preparation method of a hydrophobic polyurethane foam modified by an organosilicon compound, the synthetic route is as shown in Figure 1, comprising the following steps:

Step 1: Accurately weigh 20.0g of isocyanate-terminated polyurethane prepolymer in a three-necked flask, add 1.0g (5% of the mass fraction of isocyanate-terminated polyurethane prepolymer) of hydroxyl-terminated polydimethylsiloxane, and place at 75°C Under stirring for 40min; then cooled to room temperature. During this period, acetone was added dropwise to adjust the viscosity of the system.

Step 2: Add 40.0 g of distilled water to the above reaction system, set the mechanical stirrer at a speed of 900 rpm at room temperature, and stir the mixture rapidly for 40 seconds to obtain a mixed solution. The mixed solution was quickly transferred to an evaporating dish, and foamed and solidified at room temperature for 10 minutes to obtain a polyurethane foam. Then it was cut into a size of 2×2×2 cm ³ , washed three times with distilled water and absolute ethanol respectively, and dried in an oven at 70°C.

Step 3: Immerse the dried polyurethane foam in 100g/L CrO ₃ aqueous solution for 1min, take it out, squeeze and wash it repeatedly with clean water, and put it in an oven at 70°C for drying after cleaning. Then put it in the cyclohexane solution of hexadecyltrimethoxysilane (the volume ratio of hexadecyltrimethoxysilane and cyclohexane is 3:100) for 30min, take it out, and place it in an oven at 70°C After drying, the hydrophobic polyurethane foam modified by organosilicon compound can be obtained.

The application method of the present invention: put the hydrophobic polyurethane foam modified by the organosilicon compound prepared by the present invention in a beaker mixed with kerosene and water, take it out after the adsorption is saturated, weigh the mass of the polyurethane foam before and after adsorption, and calculate the adsorption capacity.

During regeneration, the adsorbed kerosene is squeezed out and collected, and then the polyurethane foam is placed in absolute ethanol, and squeezed repeatedly to replace the residual kerosene. The cleaned polyurethane foam was dried in an oven at 70°C for the next oil-water separation experiment.

Example 2

A preparation method of a hydrophobic polyurethane foam modified by an organosilicon compound, the synthetic route is as shown in Figure 1, comprising the following steps:

Step 1: Accurately weigh 20.0g of isocyanate-terminated polyurethane prepolymer in a three-necked flask, add 2.0g (10% of the mass fraction of isocyanate-terminated polyurethane prepolymer) of hydroxyl-terminated polydimethylsiloxane, at 70°C Next, stir for 50min; then cool to room temperature. During this period, acetone was added dropwise to adjust the viscosity of the system.

Step 2: 35.0 g of distilled water was added to the above reaction system, and the mixture was stirred rapidly for 40 s at room temperature with a mechanical stirrer at a speed of 900 rpm to obtain a mixed solution. The mixed solution was quickly transferred to an evaporating dish, and foamed and solidified at room temperature for 10 minutes to obtain a polyurethane foam. Then it was cut into a size of 2×2×2 cm ³ , washed three times with distilled water and absolute ethanol respectively, and dried in an oven at 70°C.

Step 3: Submerge the dried polyurethane foam in 80g/L CrO ₃ aqueous solution for 2 minutes, take it out, squeeze and wash it repeatedly with clean water, and put it in a 70°C oven for drying after cleaning. Then put it in the cyclohexane solution of hexadecyltrimethoxysilane (the volume ratio of hexadecyltrimethoxysilane and cyclohexane is 5:100) for 30min, take it out, and place it in an oven at 70°C After drying, the hydrophobic polyurethane foam modified by organosilicon compound can be obtained.

The application method of the present invention: put the hydrophobic polyurethane foam modified by the organosilicon compound prepared by the present invention in a beaker mixed with kerosene and water, take it out after the adsorption is saturated, weigh the mass of the polyurethane foam before and after adsorption, and calculate the adsorption capacity.

During regeneration, the adsorbed kerosene is squeezed out and collected, and then the polyurethane foam is placed in absolute ethanol, and squeezed repeatedly to replace the remaining kerosene. The cleaned polyurethane foam was dried in an oven at 70°C for the next oil-water separation experiment.

Example 3

A preparation method of a hydrophobic polyurethane foam modified by an organosilicon compound, the synthetic route is as shown in Figure 1, comprising the following steps:

Step 1: Accurately weigh 20.0g of isocyanate-terminated polyurethane prepolymer in a three-necked flask, add 3.0g (15% of the mass fraction of isocyanate-terminated polyurethane prepolymer) of aminopropyl-terminated polydimethylsiloxane, and Stir at room temperature for 50 min, during which acetone is added dropwise to adjust the viscosity of the system.

Step 2: 30.0 g of distilled water was added to the above reaction system, and the mixture was rapidly stirred at room temperature at 850 rpm for 40 s to obtain a mixed solution. The mixed solution was quickly transferred to an evaporating dish, and foamed and solidified at room temperature for 10 minutes to obtain a polyurethane foam. Then it was cut into a size of 2×2×2 cm ³ , washed three times with distilled water and absolute ethanol respectively, and dried in an oven at 70°C.

Step 3: Immerse the dried polyurethane foam in 50g/L CrO ₃ aqueous solution for 3 minutes, take it out, squeeze and wash it repeatedly with clean water, and put it in an oven at 70°C for drying after cleaning. Then put it in a cyclohexane solution of octadecyltrichlorosilane (the volume ratio of octadecyltrichlorosilane and cyclohexane is 4:100) for 40min, take it out, and place it in an oven at 70°C for drying , the hydrophobic polyurethane foam modified by organosilicon compound can be obtained.

The application method of the present invention: put the hydrophobic polyurethane foam modified by the organosilicon compound prepared by the present invention in a beaker mixed with kerosene and water, take it out after the adsorption is saturated, weigh the mass of the polyurethane foam before and after adsorption, and calculate the adsorption capacity.

During regeneration, the adsorbed kerosene is squeezed out and collected, and then the polyurethane foam is placed in absolute ethanol, and squeezed repeatedly to replace the remaining kerosene. The cleaned polyurethane foam was dried in an oven at 70°C for the next oil-water separation experiment.

Example 4

A preparation method of a hydrophobic polyurethane foam modified by an organosilicon compound, the synthetic route is as shown in Figure 1, comprising the following steps:

Step 1: Accurately weigh 20.0g of isocyanate-terminated polyurethane prepolymer in a three-necked flask, add 4.0g (20% of the mass fraction of isocyanate-terminated polyurethane prepolymer) of aminopropyl-terminated polydimethylsiloxane, and Stir at room temperature for 45 min, during which acetone is added dropwise to adjust the viscosity of the system.

Step 2: Add 45.0 g of distilled water to the above reaction system, and stir the mixture rapidly for 45 s at room temperature and 900 rpm to obtain a mixed solution. The mixed solution was quickly transferred to an evaporating dish, and foamed and solidified at room temperature for 10 minutes to obtain a polyurethane foam. Then it was cut into a size of 2×2×2 cm ³ , washed three times with distilled water and absolute ethanol respectively, and dried in an oven at 70°C.

Step 3: Immerse the dried polyurethane foam in 70g/L CrO ₃ aqueous solution for 3 minutes, take it out, squeeze and wash it repeatedly with clean water, and put it in a 70°C oven for drying after cleaning. Then put it in a cyclohexane solution of octadecyltrichlorosilane (the volume ratio of octadecyltrichlorosilane and cyclohexane is 5:100) for 60min, take it out, and place it in an oven at 70°C for drying , the hydrophobic polyurethane foam modified by organosilicon compound can be obtained.

The application method of the present invention: put the hydrophobic polyurethane foam modified by the organosilicon compound prepared by the present invention in a beaker mixed with kerosene and water, take it out after the adsorption is saturated, weigh the mass of the polyurethane foam before and after adsorption, and calculate the adsorption capacity.

During regeneration, the adsorbed kerosene is squeezed out and collected, and then the polyurethane foam is placed in absolute ethanol, and squeezed repeatedly to replace the residual kerosene. The cleaned polyurethane foam was dried in an oven at 70°C for the next oil-water separation experiment.

Example 5

A preparation method of a hydrophobic polyurethane foam modified by an organosilicon compound, the synthetic route is as shown in Figure 1, comprising the following steps:

Step 1: Accurately weigh 18.0 g of isocyanate-terminated polyurethane prepolymer into a three-necked flask, add 1.0 g of hydroxyl-terminated polydimethylsiloxane, stir at 75° C. for 60 min, and then cool to room temperature. During this period, acetone was added dropwise to adjust the viscosity of the system.

Step 2: Add 45.0 g of distilled water to the above reaction system, set the mechanical stirrer at a speed of 900 rpm at room temperature, and stir the mixture rapidly for 58 seconds to obtain a mixed solution. The mixed solution was quickly transferred to an evaporating dish, and foamed and solidified at room temperature for 10 minutes to obtain a polyurethane foam. Then it was cut into a size of 2×2×2 cm ³ , washed three times with distilled water and absolute ethanol respectively, and dried in an oven at 70°C.

Step 3: Immerse the dried polyurethane foam in 95g/L CrO ₃ aqueous solution for 2.8 minutes, take it out, squeeze and wash it repeatedly with clean water, and put it in a 70°C oven for drying after cleaning. Then put it in the cyclohexane solution of hexadecyltrimethoxysilane (the volume ratio of hexadecyltrimethoxysilane and cyclohexane is 1:100) for 30min, take it out, and place it in an oven at 70°C After drying, the hydrophobic polyurethane foam modified by organosilicon compound can be obtained.

Example 6

A preparation method of a hydrophobic polyurethane foam modified by an organosilicon compound, the synthetic route is as shown in Figure 1, comprising the following steps:

Step 1: Accurately weigh 16.0 g of isocyanate-terminated polyurethane prepolymer into a three-necked flask, add 1.0 g of hydroxyl-terminated polydimethylsiloxane, stir at 75° C. for 50 min, and then cool to room temperature. During this period, acetone was added dropwise to adjust the viscosity of the system.

Step 2: Add 25.6 g of distilled water to the above reaction system, set the rotation speed of the mechanical stirrer at 900 rpm at room temperature, and stir the mixture rapidly for 57 seconds to obtain a mixed solution. The mixed solution was quickly transferred to an evaporating dish, and foamed and solidified at room temperature for 10 minutes to obtain a polyurethane foam. Then it was cut into a size of 2×2×2 cm ³ , washed three times with distilled water and absolute ethanol respectively, and dried in an oven at 70°C.

Step 3: Submerge the dried polyurethane foam in 75g/L CrO ₃ aqueous solution for 2.5 minutes, take it out, squeeze and wash it repeatedly with clean water, and put it in an oven at 70°C for drying after cleaning. Then put it in the cyclohexane solution of hexadecyltrimethoxysilane (the volume ratio of hexadecyltrimethoxysilane and cyclohexane is 2:100) for 30min, take it out, and place it in an oven at 70°C After drying, the hydrophobic polyurethane foam modified by organosilicon compound can be obtained.

Example 7

A preparation method of a hydrophobic polyurethane foam modified by an organosilicon compound, the synthetic route is as shown in Figure 1, comprising the following steps:

Step 1: Accurately weigh 15.0 g of isocyanate-terminated polyurethane prepolymer into a three-necked flask, add 1.0 g of hydroxyl-terminated polydimethylsiloxane, stir at 75° C. for 40 min, and then cool to room temperature. During this period, acetone was added dropwise to adjust the viscosity of the system.

Step 2: Add 36.0 g of distilled water to the above reaction system, set the mechanical stirrer at a speed of 900 rpm at room temperature, and stir the mixture rapidly for 45 seconds to obtain a mixed solution. The mixed solution was quickly transferred to an evaporating dish, and foamed and solidified at room temperature for 10 minutes to obtain a polyurethane foam. Then it was cut into a size of 2×2×2 cm ³ , washed three times with distilled water and absolute ethanol respectively, and dried in an oven at 70°C.

Step 3: Immerse the dried polyurethane foam in 90g/L CrO ₃ aqueous solution for 3 minutes, take it out, squeeze and wash it repeatedly with clean water, and put it in a 70°C oven for drying after cleaning. Then put it in the cyclohexane solution of hexadecyltrimethoxysilane (the volume ratio of hexadecyltrimethoxysilane and cyclohexane is 3.5:100) for 30min, take it out, and place it in an oven at 70°C After drying, the hydrophobic polyurethane foam modified by organosilicon compound can be obtained.

Example 8

A preparation method of a hydrophobic polyurethane foam modified by an organosilicon compound, the synthetic route is as shown in Figure 1, comprising the following steps:

Step 1: Accurately weigh 12.0 g of isocyanate-terminated polyurethane prepolymer into a three-necked flask, add 1.0 g of hydroxyl-terminated polydimethylsiloxane, stir at 75° C. for 40 min, and then cool to room temperature. During this period, acetone was added dropwise to adjust the viscosity of the system.

Step 2: Add 27.6 g of distilled water to the above reaction system, set the mechanical stirrer at a speed of 900 rpm at room temperature, and stir the mixture rapidly for 40 seconds to obtain a mixed solution. The mixed solution was quickly transferred to an evaporating dish, and foamed and solidified at room temperature for 10 minutes to obtain a polyurethane foam. Then it was cut into a size of 2×2×2 cm ³ , washed three times with distilled water and absolute ethanol respectively, and dried in an oven at 70°C.

Step 3: Immerse the dried polyurethane foam in 60g/L CrO ₃ aqueous solution for 2 minutes, take it out, squeeze and wash it repeatedly with clean water, and put it in a 70°C oven for drying after cleaning. Then put it in a cyclohexane solution of octadecyltrichlorosilane (the volume ratio of octadecyltrichlorosilane and cyclohexane is 2:100) for 30min, take it out, and place it in an oven at 70°C for drying , the hydrophobic polyurethane foam modified by organosilicon compound can be obtained.

Example 9

A preparation method of a hydrophobic polyurethane foam modified by an organosilicon compound, the synthetic route is as shown in Figure 1, comprising the following steps:

Step 1: Accurately weigh 8.0 g of isocyanate-terminated polyurethane prepolymer into a three-necked flask, add 1.0 g of aminopropyl-terminated polydimethylsiloxane, stir at 28° C. for 45 min, and then cool to room temperature. During this period, acetone was added dropwise to adjust the viscosity of the system.

Step 2: Add 14.4 g of distilled water to the above reaction system, set the mechanical stirrer at a speed of 900 rpm at room temperature, and stir the mixture rapidly for 40 seconds to obtain a mixed solution. The mixed solution was quickly transferred to an evaporating dish, and foamed and solidified at room temperature for 10 minutes to obtain a polyurethane foam. Then it was cut into a size of 2×2×2 cm ³ , washed three times with distilled water and absolute ethanol respectively, and dried in an oven at 70°C.

Step 3: Immerse the dried polyurethane foam in 40g/L CrO ₃ aqueous solution for 1.8min, take it out, squeeze and wash it repeatedly with clean water, and put it in a 70°C oven for drying after cleaning. Then put it in the cyclohexane solution of octadecyltrichlorosilane (the volume ratio of octadecyltrichlorosilane and cyclohexane is 1:100) for 30min, take it out, and place it in an oven at 70°C for drying , the hydrophobic polyurethane foam modified by organosilicon compound can be obtained.

Example 10

A preparation method of a hydrophobic polyurethane foam modified by an organosilicon compound, the synthetic route is as shown in Figure 1, comprising the following steps:

Step 1: Accurately weigh 6.0 g of isocyanate-terminated polyurethane prepolymer into a three-necked flask, add 1.0 g of aminopropyl-terminated polydimethylsiloxane, stir at 30° C. for 60 min, and then cool to room temperature. During this period, acetone was added dropwise to adjust the viscosity of the system.

Step 2: Add 14.7 g of distilled water to the above reaction system, set the mechanical stirrer at a speed of 900 rpm at room temperature, and stir the mixture rapidly for 60 seconds to obtain a mixed solution. The mixed solution was quickly transferred to an evaporating dish, and foamed and solidified at room temperature for 10 minutes to obtain a polyurethane foam. Then it was cut into a size of 2×2×2 cm ³ , washed three times with distilled water and absolute ethanol respectively, and dried in an oven at 70°C.

Step 3: Immerse the dried polyurethane foam in 30g/L CrO ₃ aqueous solution for 1min, take it out, squeeze and wash it repeatedly with clean water, and put it in an oven at 70°C for drying after cleaning. Then put it in the cyclohexane solution of octadecyltrichlorosilane (the volume ratio of octadecyltrichlorosilane and cyclohexane is 1.5:100) for 30min, take it out, and place it in an oven at 70°C for drying , the hydrophobic polyurethane foam modified by organosilicon compound can be obtained.

Example 11

A preparation method of a hydrophobic polyurethane foam modified by an organosilicon compound, the synthetic route is as shown in Figure 1, comprising the following steps:

Step 1: Accurately weigh 4.0 g of isocyanate-terminated polyurethane prepolymer into a three-necked flask, add 1.0 g of aminopropyl-terminated polydimethylsiloxane, stir at 35° C. for 40 min, and then cool to room temperature. During this period, acetone was added dropwise to adjust the viscosity of the system.

Step 2: Add 7.6 g of distilled water to the above reaction system, set the mechanical stirrer at a speed of 900 rpm at room temperature, and stir the mixture rapidly for 50 seconds to obtain a mixed solution. The mixed solution was quickly transferred to an evaporating dish, and foamed and solidified at room temperature for 10 minutes to obtain a polyurethane foam. Then it was cut into a size of 2×2×2 cm ³ , washed three times with distilled water and absolute ethanol respectively, and dried in an oven at 70°C.

Step 3: Immerse the dried polyurethane foam in 10g/L CrO ₃ aqueous solution for 0.5min, take it out, squeeze and wash it repeatedly with clean water, and put it in a 70°C oven for drying after cleaning. Then put it in the cyclohexane solution of cetyltrimethoxysilane (the volume ratio of cetyltrimethoxysilane and cyclohexane is 4.5:100) for 30min, take it out, and place it in an oven at 70°C After drying, the hydrophobic polyurethane foam modified by organosilicon compound can be obtained.

Example 12

A preparation method of a hydrophobic polyurethane foam modified by an organosilicon compound, the synthetic route is as shown in Figure 1, comprising the following steps:

Step 1: Accurately weigh 13.0 g of isocyanate-terminated polyurethane prepolymer into a three-necked flask, add 1.0 g of aminopropyl-terminated polydimethylsiloxane, stir at 25° C. for 50 min, and then cool to room temperature. During this period, acetone was added dropwise to adjust the viscosity of the system.

Step 2: Add 27.3 g of distilled water to the above reaction system, set the mechanical stirrer at a speed of 900 rpm at room temperature, and stir the mixture rapidly for 55 seconds to obtain a mixed solution. The mixed solution was quickly transferred to an evaporating dish, and foamed and solidified at room temperature for 10 minutes to obtain a polyurethane foam. Then it was cut into a size of 2×2×2 cm ³ , washed three times with distilled water and absolute ethanol respectively, and dried in an oven at 70°C.

Step 3: Immerse the dried polyurethane foam in 80g/L CrO ₃ aqueous solution for 1.5min, take it out, squeeze and wash it repeatedly with clean water, and put it in a 70°C oven for drying after cleaning. Then put it in the cyclohexane solution of hexadecyltrimethoxysilane (the volume ratio of hexadecyltrimethoxysilane and cyclohexane is 2.5:100) for 30min, take it out, and place it in an oven at 70°C After drying, the hydrophobic polyurethane foam modified by organosilicon compound can be obtained.

Comparative ratio

No organosilicon compound was added, and other operations were the same as in Example 1.

The polyurethane foam prepared by comparative example, embodiment 1 and embodiment 2 is characterized, and the infrared spectrogram is as shown in Figure 2. From this result, it can be known that most of the functional groups of the three foams have the same peaks, but Si-PUF-5 and Si-PUF-10 have a peak at a wavelength of 804.3cm ^-1 , and the peak intensity of Si-PUF-10 here is greater than that of Si-PUF-5. After review, it is the stretching vibration peak of the Si-O bond, indicating that The polyurethane prepolymer was successfully modified.

The modified hydrophobic polyurethane foam prepared in Example 2 is studied, that is, step 2) Si-PUF-10 polyurethane foam prepared before etching, step 3) Si-PUF-10 polyurethane foam after chromic acid etching, and The polyurethane foam after branching reaction (impregnated with cetyltrimethoxysilane) was characterized, and the infrared spectrum results are shown in Figure 3. It can be seen from Figure 3 that after impregnation, the polyurethane foam has _double peaks at the wavelengths of 2920 and 2862 cm ^-1 , which are long carbon chain -CH stretching vibration peaks, indicating that the method of the present invention can successfully modify the polyurethane foam.

The research on the surface morphology of the polyurethane foam prepared in Comparative Example and Example 2, that is, the Si-PUF-0 polyurethane foam without adding organosilicon compound, the Si-PUF-10 polyurethane foam after etching and grafting reaction SEM characterization, the result is shown in Figure 4. From the results, it can be seen that the original finger-shaped pores on the surface of the polyurethane foam are changed due to strong acid etching, and many nano-scale small spots appear on the surface of the foam under a high-magnification lens, mainly polyurethane foam. The surface is corroded, and the surface roughness of the modified polyurethane foam is improved, providing a hydrophobic interface. According to the surface wettability mechanism, the wettability is mainly affected by the microscopic structure of the chemical composition of the solid surface. The rough structure has Conducive to the water repellency of the material.

Referring to Fig. 5, measure the contact angle of Si-PUF-10 polyurethane foam before etching of comparative example, embodiment 2, the Si-PUF-10 hydrophobic polyurethane foam that grafting reaction makes after embodiment 2 etching, the result is as shown in Fig. 5, the water contact angle of (a) is 93 °, the water contact angle of (b) is 136 °, and the water contact angle of (c) is 146.2 °. From this result, it can be seen that the water contact angle of the modified polyurethane foam The contact angle increased significantly, indicating that the hydrophobicity of polyurethane foam modified by silicone was significantly enhanced. There are two main reasons for the enhanced hydrophobicity. One is that the strong acid etching solution roughens the surface of polyurethane and obtains a micro-nano rough structure. The second is that the introduction of organosilicon compounds further reduces the surface energy of the polyurethane foam, and the polyurethane foam is modified by two steps of organosilicon to improve the hydrophobicity.

The stability and reproducibility of the hydrophobic polyurethane foam modified by the organosilicon compound prepared in Example 3 of the present invention are studied, specifically as follows:

Stability: Divide the hydrophobic polyurethane foam modified by the organosilicon compound prepared in the example into three parts, soak it in 0.1M hydrochloric acid, sodium hydroxide, and sodium chloride solution for 30 minutes, dry, measure the water contact angle, and By comparison, it was found that the water contact angle did not decrease substantially, indicating that the hydrophobic polyurethane foam modified by the organosilicon compound prepared according to the method of the present invention has good stability.

Renewability: After the organosilicon compound-modified hydrophobic polyurethane foam prepared in Example 3 was subjected to 8 cycles of oil-water separation, the oil absorption ratio and water contact angle of the modified polyurethane foam were measured, and it was found that the oil absorption ratio and water contact angle None of them decreased significantly, indicating that the organosilicon compound-modified hydrophobic polyurethane foam prepared according to the method of the present invention has good reproducibility, high recycling rate and strong practicability.

To sum up, due to its unique structure, organosilicon compounds have the characteristics of low surface tension and hydrophobicity, and are widely used in waterproofing and moisture-proofing. The present invention introduces hydrophobic organosilicon chain segments into the main chain structure and surface of the polyurethane foam, so the hydrophobicity of the polyurethane foam can be greatly improved. In addition, the polyurethane foam prepared by the invention has good stability and reproducibility, and its performance remains basically unchanged after repeated use for many times.

The above content is only to illustrate the technical ideas of the present invention, and cannot limit the protection scope of the present invention. Any changes made on the basis of the technical solutions according to the technical ideas proposed in the present invention shall fall within the scope of the claims of the present invention. within the scope of protection.

Claims (5)

1. A preparation method of hydrophobic polyurethane foam modified by organosilicon compounds is characterized by comprising the following steps:

step 1) mixing the isocyanate-terminated polyurethane prepolymer with the dried organic silicon compound, and mixing and reacting to obtain an organic silicon modified polyurethane prepolymer;

step 2) mixing and stirring the organic silicon modified polyurethane prepolymer and deionized water to obtain a mixed solution, and foaming and curing the mixed solution to obtain polyurethane foam;

step 3) sequentially washing and drying the polyurethane foam, immersing the polyurethane foam into chromic acid for etching, washing and drying the polyurethane foam sequentially after etching, immersing the polyurethane foam subjected to secondary drying into a long carbon chain organic silicon compound solution for grafting reaction, and drying to obtain organic silicon compound modified hydrophobic polyurethane foam;

when the organic silicon modified polyurethane prepolymer in the step 1) is prepared, acetone is dropwise added into the mixed solution after the mixing reaction;

the feeding ratio of the acetone to the isocyanate-terminated polyurethane prepolymer is (0.18 to 0.3) ml:10g of a mixture;

in the step 1), the organic silicon compound is hydroxyl-terminated polydimethylsiloxane or aminopropyl-terminated polydimethylsiloxane;

in the step 1), the mass ratio of the isocyanate-terminated polyurethane prepolymer to the dried organic silicon compound is (4-20): 1;

in the step 2), when the organic silicon modified polyurethane prepolymer is mixed with deionized water, the mass ratio of the deionized water to the isocyanate-terminated polyurethane prepolymer is (1.5-2.5): 1;

in the step 3), the long-carbon-chain organosilicon compound is hexadecyl trimethoxy silane or octadecyl trichlorosilane;

in the step 3), the step (c),

during etching, the feeding ratio of the polyurethane foam to chromic acid is (0.8 to 1.2) g:30ml;

the concentration of chromic acid is 10-100 g/L, and the etching time is 0.5-3 min.

2. The method of producing the hydrophobic polyurethane foam modified with an organosilicon compound according to claim 1, wherein in step 1),

when the organosilicon compound is hydroxyl-terminated polydimethylsiloxane, the mixing reaction conditions are as follows: the temperature is 70-80 ℃, and the time is 40-60 min;

when the organosilicon compound is aminopropyl terminated polydimethylsiloxane, the conditions of the mixing reaction are as follows: the temperature is 20 to 35 ℃, and the time is 40 to 60min.

3. The method for producing hydrophobic polyurethane foam modified with organosilicon compound according to claim 1, wherein in step 3), the solvent in the solution of long carbon chain organosilicon compound is cyclohexane;

in the long carbon chain organosilicon compound solution, the volume ratio of the long carbon chain organosilicon compound to cyclohexane is (1 to 5): 100.

4. the method for producing hydrophobic polyurethane foam modified with organosilicon compound according to claim 1, wherein in step 1), the conditions for drying organosilicon compound are: the temperature is 110-140 ℃, and the time is 2-4 h;

in the step 2), the stirring conditions are as follows: the temperature is 20 to 35 ℃, and the time is 40 to 60s; the foaming and curing conditions are as follows: the temperature is 20 to 35 ℃, and the time is 5 to 10min;

in the step 3), washing before etching is carried out, wherein the washing is carried out for 2 to 3 times by alternately washing with deionized water and ethanol in sequence; the washing after etching is washing by using deionized water;

the drying conditions are as follows: the temperature is 60 to 80 ℃, and the time is 4 to 6 hours;

the impregnation conditions were: the temperature is 20 to 35 ℃, and the time is 30 to 60min.

5. An organosilicon compound-modified hydrophobic polyurethane foam prepared by the preparation method of the organosilicon compound-modified hydrophobic polyurethane foam according to any one of claims 1 to 4, wherein the range of the water contact angle of the organosilicon compound-modified hydrophobic polyurethane foam is 138-148 °.

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