A process for the preparation of a silicone antifoam composition, and products and uses thereof

Abstract

The application discloses a preparation method of a silicone defoaming composition, and a product and application thereof, and belongs to the technical field of defoaming agents. The method comprises the following steps: firstly, a hydroxyl MQ silicone resin and hydrophilic silicon dioxide are pretreated by being reacted under the catalysis of a catalyst tetramethylammonium hydroxide by using polydimethylsiloxane as a solvent; then, after the tetramethylammonium hydroxide is removed by being heated, a hydrogen-containing MQ silicone resin and a vinyl polyorganosiloxane are added and uniformly mixed; finally, the mixture is crosslinked under the action of a platinum catalyst to prepare the defoaming composition. The silicone defoaming composition prepared by the method has the advantages of excellent defoaming performance and easy emulsification, and is particularly suitable for defoaming treatment of pulp black liquor.

Description

Technical Field

[0001] This invention belongs to the field of fine chemicals and relates to defoaming compositions, specifically to a method for preparing an organosilicon defoaming composition, its product, and its application. Background Technology

[0002] In the pulping stage of the paper industry, the use of various cooking aids such as anthraquinone, sulfides, and sodium hydroxide, along with the high lignin content in plants, often leads to significant foam generation during production due to conveying and agitation. This foam increases production costs and energy consumption in the pulp and paper industry. Industrial production typically addresses this by adding defoamers. US3383327A describes a defoaming composition obtained by heating a mixture of polysiloxane and hydrophilic silica; US 3560401A improves the defoaming performance of the composition by adding an alkaline catalyst to polysiloxane and silica; WO2007137948 describes an organosilicon defoaming composition prepared by reacting hydrogen-containing silicone oil and vinyl silicone oil. While these methods improve the foaming problem in pulping black liquor to some extent, they still suffer from insufficient performance, poor stability, high viscosity, and difficulty in emulsification. Summary of the Invention

[0003] In view of the shortcomings of the prior art, the technical problem to be solved by the present invention is to provide a method for preparing an organosilicon defoaming composition, which has the advantages of excellent defoaming and foam-suppressing performance and easy emulsification.

[0004] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0005] A method for preparing an organosilicon defoaming composition involves first pretreating hydroxyl MQ silicone resin and hydrophilic silica by reacting them with a tetramethylammonium hydroxide catalyst using polydimethylsiloxane as a solvent. Then, after removing the tetramethylammonium hydroxide by heating, hydrogen-containing MQ silicone resin and vinyl polyorganosiloxane are added and mixed evenly. Finally, the mixture undergoes a crosslinking reaction under the action of a platinum catalyst to prepare the defoaming composition.

[0006] The preparation method of the organosilicon defoaming composition, wherein the polydimethylsiloxane has a viscosity of 10~100000 mPa.s at 25°C, preferably 100~5000 mPa.s.

[0007] The method for preparing the organosilicon defoaming composition, wherein the hydroxyl content in the hydroxyl MQ silicone resin is 1-3%.

[0008] The method for preparing the organosilicon defoaming composition uses hydrogen-containing MQ silicone resin with a hydrogen content of 0.1-0.5%.

[0009] The preparation method of the organosilicon defoaming composition, wherein the viscosity of the vinyl polyorganosiloxane at 25°C is 1000~50000 mPa·s.

[0010] The preparation method of the organosilicon defoaming composition comprises the following raw materials in parts by weight: 30-80 parts of polydimethylsiloxane, 1-10 parts of hydroxyl MQ silicone resin, 1-10 parts of hydrophilic silica, 0.1-1 parts of tetramethylammonium hydroxide, 1-10 parts of hydrogen-containing MQ silicone resin, and 10-50 parts of vinyl polyorganosiloxane; a catalytic amount of tetramethylammonium hydroxide (the amount of which is calculated based on the effective content of ammonium hydroxide and accounts for 0.1-1% of the total mass of the organosilicon defoaming composition), and a catalytic amount of platinum catalyst (calculated as platinum element and accounting for 1-50 ppm of the total mass of the organosilicon defoaming composition).

[0011] The silicone defoaming composition obtained by the preparation method of the aforementioned silicone defoaming composition.

[0012] The application of the aforementioned organosilicon defoaming composition in the preparation of defoaming emulsions.

[0013] The application of the aforementioned organosilicon defoaming composition in defoaming during pulping.

[0014] The application of the aforementioned defoaming emulsion in defoaming during pulping.

[0015] The preparation method of the aforementioned organosilicon defoaming composition involves adding polydimethylsiloxane, hydroxyl MQ silicone resin, hydrophilic silica, and tetramethylammonium hydroxide to a container, stirring, heating to 100°C, and maintaining this temperature for 3 hours. After the heating period, the material is heated to 150°C and maintained for 1 hour to remove the tetramethylammonium hydroxide. Then, hydrogen-containing MQ silicone resin and vinyl polyorganosiloxane are added and mixed evenly. The material temperature is controlled at 60°C, a platinum catalyst is added, and the temperature is further increased to 100°C and maintained for 3 hours to induce a crosslinking reaction. Finally, the material is cooled to room temperature to obtain the invented organosilicon defoaming composition.

[0016] Beneficial effects: Compared with the prior art, the organosilicon defoaming composition of the present invention uses polydimethylsiloxane as a solvent to pre-react silica with hydroxyl MQ silicone resin. The product then undergoes a cross-linking reaction with hydrogen-containing MQ silicone resin and vinyl polyorganosiloxane to obtain a defoaming composition with a complex spatial network structure. In the organosilicon defoaming composition prepared by this method, silica is not easily separated from the composition, thereby slowing down the deactivation of the defoamer. Furthermore, compared with the prior art, the composition obtained by this method is easier to emulsify and prepare emulsions. Detailed Implementation

[0017] The present invention will be further described below with reference to specific embodiments.

[0018] Example 1

[0019] Add 30 parts of polydimethylsiloxane with a viscosity of 5000 mPa·s, 10 parts of hydroxyl MQ silicone resin with a molecular weight of 1000 g / mol and a hydroxyl content of 3%, 10 parts of silica (AEROSIL 200 manufactured by Evonik, hereinafter the same), and 1 part of tetramethylammonium hydroxide to a flask. Stir and heat to 100℃ and maintain the temperature for 3 hours. Then connect the flask to a vacuum pump and maintain a pressure of -0.04 to -0.08 mPa, raising the material temperature to 150℃ and maintaining it for 1 hour. Continue adding 10 parts of hydrogen-containing MQ silicone resin with a molecular weight of 3000 g / mol and a hydrogen content of 0.1% and 39 parts of ViMe2SiO (Me2SiO) to the flask. 400 SiMe2Vi is a vinyl polyorganosiloxane with a viscosity of 1000 mPa·s (Me refers to methyl and Vi refers to vinyl, the same below). The material in the flask is kept at 60°C and stirred. A chloroplatinic acid-isopropanol solution with a final concentration of 5 ppm (calculated as platinum) is added. The temperature is raised to 100°C and kept at that temperature for 3 hours. Finally, the material temperature is lowered to room temperature to obtain the organosilicon defoaming composition S1.

[0020] Example 2

[0021] Add 80 parts of polydimethylsiloxane with a viscosity of 5000 mPa·s, 1 part of hydroxyl MQ silicone resin with a molecular weight of 5000 g / mol and a hydroxyl content of 1%, 1 part of silica, and 0.1 parts of tetramethylammonium hydroxide to a flask. Stir and heat, controlling the temperature to 100℃ and holding for 3 hours. Then connect the flask to a vacuum pump and maintain a negative pressure state to raise the material temperature to 150℃ and hold for 1 hour. Continue adding 8.9 parts of hydrogen-containing MQ silicone resin with a molecular weight of 1000 g / mol and a hydrogen content of 0.5%, and 10 parts of ViMe2SiO (Me2SiO) to the flask. 1000 SiMe2Vi, a vinyl polysiloxane with a viscosity of 50000 mPa·s, was mixed with the material in a flask at 60°C while stirring. A chloroplatinic acid-isopropanol solution with a final concentration of 50 ppm (calculated as platinum) was added, and the temperature was raised to 100°C and held for 3 hours. Finally, the material temperature was lowered to room temperature to obtain the silicone defoaming composition S2.

[0022] Example 3

[0023] Add 50 parts of polydimethylsiloxane with a viscosity of 1000 mPa·s, 5 parts of hydroxyl MQ silicone resin with a molecular weight of 2500 g / mol and a hydroxyl content of 1%, 5 parts of silica, and 0.5 parts of tetramethylammonium hydroxide to a flask. Stir and heat to 100°C and maintain this temperature for 3 hours. Then connect the flask to a vacuum pump and maintain negative pressure to raise the material temperature to 150°C and maintain this temperature for 1 hour. Next, add 1 part of hydrogen-containing MQ silicone resin with a molecular weight of 2000 g / mol and a hydrogen content of 0.1%, and 38.5 parts of ViMe2SiO (Me2SiO) to the flask. 1000 SiMe2Vi, a vinyl polyorganosiloxane with a viscosity of 50000 mPa·s, was mixed with the material in the flask at 60°C while stirring. A chloroplatinic acid-isopropanol solution with a final concentration of 10 ppm (calculated as platinum) was added, and the temperature was raised to 100°C and held for 3 hours. Finally, the material temperature was lowered to room temperature to obtain the organosilicon defoaming composition S3.

[0024] Example 4

[0025] Add 34 parts of polydimethylsiloxane with a viscosity of 1000 mPa·s, 5 parts of hydroxyl MQ silicone resin with a molecular weight of 2300 g / mol and a hydroxyl content of 1.5%, 5 parts of silica, and 1 part of tetramethylammonium hydroxide to a flask, stir and heat, controlling the temperature to 100℃ and holding for 3 hours. Then connect the flask to a vacuum pump and maintain a negative pressure state, raising the material temperature to 150℃ and holding for 1 hour. Continue adding 5 parts of hydrogen-containing MQ silicone resin with a molecular weight of 2500 g / mol and a hydrogen content of 0.1%, and 50 parts of ViMe2SiO (Me2SiO) to the flask. 840 A vinyl polysiloxane with a viscosity of 10000 mPa·s (SiMe2Vi) was added to a flask at 60°C with stirring. A chloroplatinic acid-isopropanol solution with a final concentration of 10 ppm (calculated as platinum) was added, and the temperature was raised to 100°C and held for 3 hours. Finally, the temperature of the material was lowered to room temperature to obtain the silicone defoaming composition S4.

[0026] Comparative Example 1

[0027] Add 64 parts of polydimethylsiloxane with a viscosity of 10,000 mPa·s, 20 parts of hydroxyl-terminated polydimethylsiloxane with a viscosity of 10,000 mPa·s, 5 parts of MQ silicone resin containing 2% hydroxyl groups, 10 parts of fumed silica AEROSIL 200, and 1 part of sodium hydroxide to a flask. Stir and heat to 150°C and react for 2 hours. After cooling to room temperature, defoaming composition C1 is obtained.

[0028] Comparative Example 2

[0029] The material ratio is the same as in Example 1, except that the silica AEROSIL 200 and hydroxyl MQ silicone resin are not pre-treated. Instead, 30 parts of polydimethylsiloxane with a viscosity of 5000 mPa·s, 10 parts of hydroxyl MQ silicone resin, 10 parts of AEROSIL 200 silica produced by Evonik, 1 part of tetramethylammonium hydroxide, 10 parts of hydrogen-containing MQ silicone resin with a hydrogen content of 0.1%, and 39 parts of ViMe2SiO (Me2SiO) are used. 400 A vinyl polysiloxane with a viscosity of 1000 mPa·s (SiMe2Vi) was added to a flask. The material in the flask was stirred and heated to 60°C. A chloroplatinic acid-isopropanol solution with a final concentration of 5 ppm (calculated as platinum) was added, and the temperature was further increased to 100°C and kept at that temperature for 3 hours. Finally, the material temperature was reduced to room temperature to obtain the silicone defoaming composition C2.

[0030] Comparative Example 3

[0031] Add 55 parts of vinyl polydimethylsiloxane with a viscosity of 1000 mPa·s, 10 parts of hydrogen-containing polydimethylsiloxane with a viscosity of 10 mPa·s and a hydrogen content of 0.3%, 10 parts of MQ silicone resin, and 10 parts of fumed silica AEROSIL 200 to a flask. Stir and heat to 70°C, add a chloroplatinic acid-isopropanol solution with a final concentration of 5 ppm (calculated as platinum element), continue to heat to 100°C and keep at that temperature for 3 hours, then cool to room temperature to obtain defoaming composition C3.

[0032] Example 5

[0033] 1. Preparation of emulsion samples: 30 parts of any defoaming composition prepared in the examples and comparative examples, 4 parts of LAE-4, 2 parts of LAE-9 (both LAE-4 and LAE-9 were produced by Jiangsu Haian Petrochemical Plant), 2 parts of FZ-2104, and 2 parts of FZ-2108 (produced by DowSil) were added to a container, stirred, and heated to 70°C. 50 parts of water were added in batches over 10 minutes. Finally, the material was cooled to room temperature to obtain the defoamer emulsion. The emulsification of the defoamer emulsion is shown in Table 1 below.

[0034] Table 1. Emulsification of Defoamer Emulsions

[0035]

[0036] 2. Performance testing using the shake-bottle method

[0037] The defoaming and antifoaming properties of the above emulsion samples were tested in an aqueous solution of anionic surfactant using the shake-flask method.

[0038] Add 50 mL of a 1‰ sodium dodecylbenzenesulfonate-distilled aqueous solution and 0.1 g of defoamer sample diluted to 1% solids to a 100 mL stoppered graduated cylinder. After stopping the bottle, shake it up and down 10 times, let it stand, and record the time T1 for foam elimination. The shorter the time, the better the defoamer sample's defoaming performance.

[0039] Table 2 Performance test results of the shake-bottle method

[0040]

[0041] 3. Performance testing of the cyclic bubbling method

[0042] The defoaming and foam-suppressing properties of the above emulsion samples were tested in eucalyptus pulp black liquor using a circulating bubble apparatus.

[0043] 500 mL of eucalyptus pulp black liquor was added to a graduated glass cylinder with a heat-conducting jacket, and heating was started. The liquor temperature was maintained at 80°C, and the circulation pump was turned on. When the foam height reached 1000 mL, a defoamer sample diluted to 10% solids content was added. The foam height was recorded over time until it returned to 1000 mL. A longer time (T2) from the addition of the defoamer to the end of recording indicates better defoamer performance. The test results are shown in Table 2 below.

[0044] Table 3 Performance test results of the cyclic bubbling method

[0045]

[0046] As can be seen from Tables 1, 2, and 3, the emulsion samples ES1-4 prepared using the defoaming compositions S1-4 prepared in Examples 1-4 have good defoaming and foam-suppressing properties, and the prepared emulsions have a narrow particle size distribution. The emulsion sample EC1 prepared using the defoaming composition C1 in Comparative Example 1 has good emulsion properties but poor defoaming and foam-suppressing properties. The emulsion sample EC2 prepared using the same materials as in this invention, but with silica not pre-reacted with hydroxyl MQ silicone resin, has slightly poorer properties and the prepared emulsion has a significantly larger particle size. The defoaming composition C3 in Comparative Example 3 cannot properly emulsify to prepare an emulsion due to its excessive viscosity.

Claims

1. A method for preparing an organosilicon defoaming composition, characterized in that, First, using polydimethylsiloxane as a solvent, hydroxyl MQ silicone resin and hydrophilic silica are reacted and pretreated under the catalysis of tetramethylammonium hydroxide. Then, the tetramethylammonium hydroxide is removed by heating, followed by the addition of hydrogen-containing MQ silicone resin and vinyl polyorganosiloxane, which are then mixed evenly. Finally, the mixture undergoes a cross-linking reaction under the action of a platinum catalyst to prepare an antifoaming composition. The hydroxyl MQ silicone resin has a hydroxyl content of 1-3%, and the hydrogen-containing MQ silicone resin has a hydrogen content of 0.1-0.5%.

2. The method for preparing the organosilicon defoaming composition according to claim 1, characterized in that, The polydimethylsiloxane has a viscosity of 100~5000 mPa·s.

3. The method for preparing the organosilicon defoaming composition according to claim 1, characterized in that, The viscosity of the vinyl polyorganosiloxane is 1000~50000 mPa·s.

4. The method for preparing the organosilicon defoaming composition according to claim 1, characterized in that, The weight parts of each raw material are as follows: 30-80 parts of polydimethylsiloxane, 1-10 parts of hydroxyl MQ silicone resin, 1-10 parts of hydrophilic silica, 0.1-1 parts of tetramethylammonium hydroxide, 1-10 parts of hydrogen-containing MQ silicone resin, and 10-50 parts of vinyl polyorganosiloxane; the amount of platinum catalyst is 1-50 ppm in the composition system.

5. The silicone defoaming composition obtained by the preparation method of the silicone defoaming composition according to any one of claims 1-4.

6. The use of the organosilicon defoaming composition according to claim 5 in the preparation of defoaming emulsions.

7. The application of the organosilicon defoaming composition according to claim 5 in defoaming during pulping.

8. The application of the defoaming emulsion according to claim 6 in defoaming during pulping.

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