Method for removing ammonia from high-stability hydroxyl silicone oil crude product

Abstract

The invention provides a method for removing ammonia from a high-stability hydroxyl silicone oil crude product, which comprises the following steps: adding the hydroxyl silicone oil crude product into a deamination kettle, starting stirring, adding an acid neutralizer to remove ammonia, neutralizing for 1-5 hours, heating to 20-100 DEG C, and removing water from the hydroxyl silicone oil crude product under the pressure of-0.08 to-0.1 MPa to realize an impurity removal process. By adopting the technical scheme of the invention, the hydroxyl content of the obtained hydroxyl silicone oil is 8-14%, the hydroxyl content difference change is less than 1% after the hydroxyl silicone oil is stored for 3-3 months, and the ammonia content is less than 50ppm; and the water content is within 10 ppm.

Description

Technical Field

[0001] The invention relates to a method for removing impurities from hydroxy silicone oil, in particular to a method for removing impurities from crude hydroxy silicone oil, and belongs to the technical field of organosilicon post-processing. Background Art

[0002] Hydroxyl silicone oil, also known as dimethylhydroxy silicone oil, is a linear polymer with repeated silicon-oxygen bonds as the main chain, methyl groups as side groups and hydroxyl end caps. It can be used to make silicone emulsions and used as a treatment agent for fabrics, paper, and leather. Dimethylhydroxy silicone oil is widely used as a structure control agent in silicone rubber processing. It can effectively control the structural interaction between the compound and white carbon black, improve the processing performance of silicone rubber, and extend the storage life of the rubber. Dimethylhydroxy silicone oil can also be used as an intermediate for the synthesis of various polysiloxanes. At present, the main process for producing hydroxy silicone oil is to react dimethylcyclosiloxane with acetic anhydride under acidic catalyst conditions to first synthesize acetoxy-terminated silicone oil, then use water to remove the acidic catalyst, neutralize and hydrolyze with Na2CO3 or NaHCO3 to neutrality, remove water and decolorize to obtain hydroxy silicone oil. This method has a complex operation process, low conversion rate and high cost. The preparation of hydroxy silicone oil by hydrolyzing dimethyldichlorosilane with ammonia has a high hydroxyl content, high conversion rate and low cost. When producing hydroxy silicone oil by hydrolyzing dimethyldichlorosilane, crude hydroxy silicone oil is first produced. Since crude hydroxy silicone oil contains a small amount of ammonia and water and is in a weakly alkaline environment, improper treatment can reduce the hydroxyl content.

[0003] In addition, the deamination process in this patent uses a conventional evaporator for deamination, and the ammonia removal is not sufficient, which also causes the hydroxyl content in the product to be relatively low.

[0004] Patent CN 109942820 A discloses methylphenyl hydroxy silicone oil, but the obtained hydroxyl content is only 3-5%.

[0005] In the preparation process of hydroxyl silicone oil by ammonia hydrolysis in this application, when the hydroxyl content is 8-14%, it is a crude silicone oil. At 50-100°C, due to the high activity of ammonia, the activity of hydroxyl is also relatively high, which is particularly prone to loss of hydroxyl content. Summary of the Invention

[0006] In order to solve the above technical problems, the present invention performs deamination post-treatment on the crude product obtained during the preparation of hydroxy silicone oil to achieve high-quality hydroxy silicone oil products.

[0007] The hydroxy silicone oil in the technical solution of the present invention is prepared by the following preparation method: (1) Using dimethyldichlorosilane as raw material, a hydrolysis reaction is carried out in a hydrolysis medium to obtain an oil-water mixture; (2) Separating the oil-water mixture to obtain crude hydroxy silicone oil; The hydrolysis medium in step (1) is composed of water, ammonia and ammonium salt in a certain proportion.

[0008] The concentration of ammonia water in the hydrolysis medium is 15-30%, and the concentration of ammonium salt is 10-35%.

[0009] The ammonium salt of the hydrolysis medium is at least one of ammonium chloride, ammonium sulfate, ammonium nitrate, ammonium carbonate, and ammonium bicarbonate.

[0010] In step (1), the ratio of dimethyldichlorosilane to the hydrolysis medium is 1:(5-100).

[0011] The hydrolysis reaction temperature in step (1) is 0-80°C.

[0012] In step (2), the oil-water separation temperature is 50-80°C, and the oil-water separation time is 1-24h.

[0013] The temperature of the hydrolysis reaction is controlled by using chilled water or chilled brine.

[0014] The separated oil phase can automatically overflow to the next step, which is the crude hydroxy silicone oil.

[0015] The physical and chemical properties of the crude hydroxy silicone oil are as follows: a hydroxyl content of 8-14%, more preferably a hydroxyl content of 10-14%, a viscosity of 28-40 cp, an ammonia content of 1-5%, and a water content of 0.5-3%.

[0016] The technical solution of the present invention is to purify hydroxy silicone oil products with high hydroxyl content, and the purification process is to avoid the reduction of high hydroxyl content. In the present invention, hydroxy silicone oil with high hydroxyl content refers to hydroxy silicone oil with a hydroxyl content of any one of 8%, 9%, 10%, 11%, 12%, 13%, 14%, or any value in between.

[0017] The presence of ammonia in the crude product will cause a self-condensation reaction, reduce the hydroxyl content, and increase the viscosity, thereby causing the hydroxyl content of the obtained product to be lower than 8% and the viscosity to be greater than 40cp, affecting the stability of the product.

[0018] Start stirring and add acid neutralizer to remove ammonia. After neutralization for 1-5 hours, 80-98% of the ammonia in the crude product will be removed.

[0019] The acid neutralizer is selected from any one or more of hydrochloric acid, nitric acid, sulfuric acid, oxalic acid, and acetic acid, and the acid concentration is 0.1%-10%.

[0020] The acid concentration of the present invention cannot be too high, as it will destroy the hydroxyl content in the crude hydroxy silicone oil and cause the problem of removing the hydroxyl groups. If the acid concentration is too low, it will be difficult to neutralize the ammonia content in the crude hydroxy silicone oil.

[0021] The acid neutralizer is sprayed or dropped in the form of a solution or added into the crude hydroxy silicone oil through a pipeline, and then stirred to achieve neutralization of ammonia and weak acid in the crude hydroxy silicone oil.

[0022] The acid neutralizer may also be a weakly acidic cationic resin, wherein the weakly acidic cationic resin has a pH of 5.5-6.5.

[0023] The weakly acidic cationic resin is selected from any one of a polymer resin of 2-acrylic acid and divinylbenzene, Purolite C104Plus, D113, D111S, and D152.

[0024] Similarly, the acid concentration should not be too high or too low.

[0025] In some embodiments, the weakly acidic cationic resin is the solid acid neutralizer in this case. The neutralizer is fixed on a sieve plate, mesh or partition, and the crude hydroxy silicone oil is passed through the weakly acidic cationic resin to neutralize the ammonia and weak acid in the crude hydroxy silicone oil.

[0026] In the above technical solutions, ammonia removal is achieved by contacting the hydroxyl silicone oil with a liquid or solid weak acid. This removal process requires controlling the ammonia content in the hydroxyl silicone oil to 2-20% (i.e., incomplete removal of ammonia from the hydroxyl silicone oil; 2-20% refers to 2-20% of the total ammonia content in the crude hydroxyl silicone oil). This results in 80-98% ammonia removal, with the remaining ammonia and water components removed by membrane adsorption. During this process, a certain amount of ammonia content is controlled in the hydroxyl silicone oil to maintain the acid-base balance in the acidic environment and avoid polycondensation. Adding acid during the deamination process can also cause polycondensation within the hydroxyl silicone oil itself, reducing the hydroxyl content.

[0027] After the acid neutralization treatment, the above-mentioned solution still contains 2-20% ammonia and 0.5-1% water. In this process, a membrane material adsorbent is used to adsorb ammonia and water after re-contact and then remove them. The membrane material adsorbent is a Nafion-coated modified molecular sieve adsorption.

[0028] The Nafion-coated modified molecular sieve preparation method comprises: spraying a Nafion™ perfluorinated resin solution onto the surface of a commercial molecular sieve using a coating machine; and drying and activating the Nafion-coated molecular sieve at 50-100°C for 10-30 minutes to obtain the Nafion-coated modified molecular sieve.

[0029] The mass concentration of Nafion™ perfluorinated resin solution is 1-20%; During the spraying process, the film thickness is controlled at 0.1-100μm.

[0030] The molecular sieves are commercial molecular sieves, including beta molecular sieve, titanium silicalite molecular sieve, and SBA-15.

[0031] The acid neutralizer can also be a product obtained by soaking a modified Nafion-coated molecular sieve in any one of hydrochloric acid, nitric acid, sulfuric acid, oxalic acid, and acetic acid for 12-24 hours.

[0032] The concentration of the hydrochloric acid, nitric acid, sulfuric acid, oxalic acid, and acetic acid is 0.1-5 wt %. Ammonia and water are removed from the crude hydroxy silicone oil.

[0033] That is, the crude hydroxy silicone oil is directly brought into contact with the acid-impregnated Nafion-coated modified molecular sieve to achieve the selective removal of ammonia and water.

[0034] In some embodiments of the present invention, the Nafion coated modified molecular sieve is loaded into an adsorption column to remove part of the ammonia and water after contact. The part of ammonia and water is the hydroxy silicone oil obtained after removing ammonia (including a very small amount of water) from the crude hydroxy silicone oil with an acid neutralizer.

[0035] In some embodiments of the present invention, the Nafion coated modified molecular sieve is loaded into an adsorption column to remove ammonia and water from the crude hydroxy silicone oil after contact.

[0036] By adopting the technical solution of the present invention, the hydroxyl content of the hydroxyl silicone oil obtained is 8-12%, the difference in hydroxyl content after storage for 3 months is less than 1%, the ammonia content is within 50 ppm, more preferably within 20 ppm, more preferably within 10 ppm; the water content is within 10 ppm, more preferably within 5 ppm, more preferably within 1 ppm. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 This is the infrared image of the product obtained in Example 1. DETAILED DESCRIPTION

[0038] The hydroxyl content detection conditions of the present invention are: gas measurement method, which is to use Lithium aluminum hydride The active hydrogen on the hydroxyl group is converted into hydrogen gas, and the volume of hydrogen gas is measured to calculate the amount of hydroxyl group.

[0039] The viscosity content detection conditions in the present invention are: Brookfield The measurement was carried out at 25°C using a DVNext rotary viscometer.

[0040] Example 1 A method for preparing hydroxy silicone oil comprises the following steps: (1) In a hydrolysis reactor, dimethyldichlorosilane was slowly added to a hydrolysis medium (20% ammonia water, 25% ammonium chloride) and the hydrolysis reaction was carried out at 5-10°C; the mass ratio of dimethyldichlorosilane to the hydrolysis medium was 1:50.

[0041] (2) The oil-water mixture is subjected to oil-water separation to obtain crude hydroxy silicone oil. The crude hydroxy silicone oil has a hydroxyl content of 12.8%, a viscosity of 33 cps, an ammonia content of 4.5%, and a water content of 1.3%.

[0042] (3) The crude hydroxy silicone oil is added to the deamination kettle, the deamination kettle is vacuumed, stirring is started, 2 wt% hydrochloric acid solution is added, and stirring is carried out for 2 hours. When the ammonia content of the crude hydroxy silicone oil is 0.41% and the water content is 1.0%, the crude hydroxy silicone oil is filtered and injected into the adsorption column to remove the residual ammonia and water, and ammonium chloride is recovered at the same time to obtain the hydroxy silicone oil product.

[0043] The adsorption column is filled with Nafion-coated modified molecular sieve.

[0044] The Nafion™-coated modified molecular sieve is prepared by spraying a 5% Nafion™ perfluorinated resin solution onto the surface of commercial SBA-15 molecular sieve using a coating machine, with a film thickness of 5 μm. The Nafion™-coated molecular sieve is then dried and activated at 80°C for 20 minutes to obtain the Nafion™-coated modified molecular sieve.

[0045] After obtaining the hydroxy silicone oil product, the packed column can also be desorbed and regenerated. The regeneration method is: hot air at 100-150°C is introduced into the column for displacement activation for 30 minutes to obtain a regenerated adsorption column, which can be repeatedly used for the next batch of deamination and dehydration.

[0046] The obtained hydroxy silicone oil product has a hydroxyl content of 12.6%, a viscosity of 33cp, an ammonia content of 8ppm, and a water content of 0.55ppm. After storage for 3 months, the hydroxyl content can still reach 12.3% and the viscosity is 33.2cp.

[0047] from Figure 1 It can be seen that the hydroxy silicone oil prepared in Example 1 has a -1 There is an obvious hydroxyl peak.

[0048] Example 2 A method for preparing hydroxy silicone oil comprises the following steps: (1) In a hydrolysis reactor, dimethyldichlorosilane was slowly added to a hydrolysis medium (20% ammonia water, 25% ammonium chloride) and the hydrolysis reaction was carried out at 5-10°C; the mass ratio of dimethyldichlorosilane to the hydrolysis medium was 1:50.

[0049] (2) The oil-water mixture is subjected to oil-water separation to obtain crude hydroxy silicone oil. The crude hydroxy silicone oil has a hydroxyl content of 12%, a viscosity of 33 cps, an ammonia content of 4.5%, and a water content of 1.3%.

[0050] (3) Crude hydroxy silicone oil is added to the deamination kettle, which is vacuumed and stirred. A 5 wt% acetic acid solution is added and stirred for 3 h. When the crude hydroxy silicone oil has an ammonia content of 0.57% and a water content of 1.18%, it is filtered and pumped into an adsorption column to remove residual ammonia and water. At the same time, ammonium chloride is recovered to obtain a hydroxy silicone oil product.

[0051] The adsorption column is filled with a Nafion-coated modified molecular sieve. The Nafion-coated modified molecular sieve is the same as that in Example 1, except that the membrane thickness is 10 μm.

[0052] The obtained hydroxy silicone oil product has a hydroxyl content of 12.8%, an ammonia content of 7 ppm, a viscosity of 33 cp, and a water content of 0.4 ppm. After storage for 3 months, the hydroxyl content can still reach 12.4% and the viscosity is 33.3 cp.

[0053] Example 3 A method for preparing hydroxy silicone oil comprises the following steps: (1) In a hydrolysis reactor, dimethyldichlorosilane was slowly added to a hydrolysis medium (20% ammonia water, 25% ammonium chloride) and the hydrolysis reaction was carried out at 5-10°C; the mass ratio of dimethyldichlorosilane to the hydrolysis medium was 1:50.

[0054] (2) The oil-water mixture is subjected to oil-water separation to obtain crude hydroxy silicone oil. The crude hydroxy silicone oil has a hydroxyl content of 12%, a viscosity of 33 cp, an ammonia content of 4.5%, and a water content of 1.3%.

[0055] (3) Purolite C104 Plus (pH 5.8) cationic resin with a thickness of 50 cm was respectively set at the upper and lower parts of the deamination kettle. Crude hydroxy silicone oil was added to the deamination kettle from the cationic resin at the top. Stirring was started and stirred for 5 hours. The ammonia content of the crude hydroxy silicone oil was 0.57% and the water content was 0.89%). The product is pumped into an adsorption column through a filter to remove residual ammonia and water, while ammonium chloride is recovered to obtain a hydroxy silicone oil product.

[0056] The adsorption column is filled with Nafion-coated modified molecular sieves, which are the same as the Nafion-coated modified molecular sieves in Example 1.

[0057] The obtained hydroxy silicone oil product has a hydroxyl content of 12.7%, an ammonia content of 6 ppm, a viscosity of 32.5 cp, and a water content of 1 ppm. After storage for 3 months, the hydroxyl content can still reach 12.5% ​​and the viscosity is 32.8 cp.

[0058] Example 4 A method for preparing hydroxy silicone oil comprises the following steps: (1) In a hydrolysis reactor, dimethyldichlorosilane was slowly added to a hydrolysis medium (20% ammonia water, 25% ammonium chloride) and the hydrolysis reaction was carried out at 5-10°C; the mass ratio of dimethyldichlorosilane to the hydrolysis medium was 1:50.

[0059] (2) The oil-water mixture is subjected to oil-water separation to obtain crude hydroxy silicone oil. The crude hydroxy silicone oil has a hydroxyl content of 12%, a viscosity of 33 cp, an ammonia content of 4.5%, and a water content of 1.3%.

[0060] (3) Acid-impregnated Nafion™ coated molecular sieve: A 5% Nafion™ perfluorinated resin solution was sprayed onto the surface of commercial molecular sieve SBA-15 using a coating machine, with the film thickness controlled at 5 μm. The Nafion-coated molecular sieve was then dried and activated at 80°C for 20 minutes to obtain a Nafion-coated modified molecular sieve. The Nafion-coated modified molecular sieve was then impregnated with 0.5 wt% hydrochloric acid for 20 hours to obtain an acid-impregnated Nafion-coated modified molecular sieve product.

[0061] (4) The acid-impregnated Nafion-coated modified molecular sieve obtained in step (3) is loaded into an adsorption column and pumped into the adsorption column through a filter to remove residual ammonia and water, while recovering ammonium chloride to obtain a hydroxy silicone oil product.

[0062] The obtained hydroxy silicone oil product has a hydroxyl content of 12.4%, an ammonia content of 8 ppm, a viscosity of 32.7 cp, and a water content of 9 ppm. After storage for 3 months, the hydroxyl content can still reach 11.9% and the viscosity is 32.9 cp.

[0063] Example 5 A method for preparing hydroxy silicone oil comprises the following steps: (1) In a hydrolysis reactor, dimethyldichlorosilane was slowly added to a hydrolysis medium (20% ammonia water, 25% ammonium chloride) and the hydrolysis reaction was carried out at 5-10°C; the mass ratio of dimethyldichlorosilane to the hydrolysis medium was 1:50.

[0064] (2) The oil-water mixture is subjected to oil-water separation to obtain crude hydroxy silicone oil. The crude hydroxy silicone oil has a hydroxyl content of 12%, a viscosity of 33 cp, an ammonia content of 4.5%, and a water content of 1.3%.

[0065] (3) Crude hydroxy silicone oil is added to the deamination kettle, which is vacuumed and stirred. 20 wt% hydrochloric acid solution is added dropwise and stirred for 2 h. When the ammonia content of the crude hydroxy silicone oil is 0.05% and the water content is 1.1%, the crude hydroxy silicone oil is filtered and pumped into an adsorption column to remove residual ammonia and water. At the same time, ammonium chloride is recovered to obtain a hydroxy silicone oil product.

[0066] The adsorption column is filled with Nafion-coated modified molecular sieve (same as in Example 1).

[0067] The obtained hydroxy silicone oil product has a hydroxyl content of 8.2%, an ammonia content of 10 ppm, a viscosity of 31.5 cp, and a water content of 8 ppm.

[0068] Example 6 A method for preparing hydroxy silicone oil comprises the following steps: (1) In a hydrolysis reactor, dimethyldichlorosilane was slowly added to a hydrolysis medium (20% ammonia water, 25% ammonium chloride) and the hydrolysis reaction was carried out at 5-10°C; the mass ratio of dimethyldichlorosilane to the hydrolysis medium was 1:50.

[0069] (2) The oil-water mixture is subjected to oil-water separation to obtain crude hydroxy silicone oil. The crude hydroxy silicone oil has a hydroxyl content of 12%, a viscosity of 33 cp, an ammonia content of 4.5%, and a water content of 1.3%.

[0070] (3) Crude hydroxy silicone oil is added to the deamination kettle, which is vacuumed and stirred. A 20 wt% hydrochloric acid solution is added dropwise and stirred for 2 h. The crude hydroxy silicone oil has an ammonia content of 0.05% and a water content of 1.1%. The hydroxy silicone oil product is filtered through a filter and ammonium chloride is recovered at the same time.

[0071] The obtained hydroxy silicone oil product had a hydroxyl content of 11.2%, an ammonia content of 500 ppm, a viscosity of 29.8 cp, and a water content of 1.5%. After storage for 40 days, the hydroxyl content was 6.4% and the water content was 1.8%.

Claims

1. A method for removing ammonia from crude hydroxy silicone oil with high stability, characterized in that: The method comprises the following steps: adding crude hydroxy silicone oil into a deamination kettle, starting stirring, adding an acid neutralizer to remove ammonia, neutralizing for 1-5 hours, heating to 20-100° C., and removing water from the crude hydroxy silicone oil at a pressure of -0.08-0.1 MPa to achieve the impurity removal process.

2. The method for removing ammonia from crude hydroxy silicone oil according to claim 1, wherein: The physical and chemical properties of the crude hydroxy silicone oil are as follows: hydroxyl content 8-14%, viscosity 28-40cp, ammonia content 1-5%, and water content 0.5-3%.

3. The method for removing ammonia from crude hydroxy silicone oil according to claim 1, wherein: The acid neutralizer is selected from any one or more of hydrochloric acid, nitric acid, sulfuric acid, oxalic acid, and acetic acid, and the acid concentration is 0.1%-10%.

4. The method for removing ammonia from crude hydroxy silicone oil according to claim 1, wherein: The acid neutralizer may also be a weakly acidic cationic resin, wherein the weakly acidic cationic resin has a pH of 4.5-6.

5.

5. The method for removing ammonia from crude hydroxy silicone oil according to claim 4, wherein: The weakly acidic cationic resin is selected from any one of a polymer resin of 2-acrylic acid and divinylbenzene, Purolite C104Plus, D113, D111S, and D152.

6. The method for removing ammonia from crude hydroxy silicone oil according to any one of claims 1 to 5, characterized in that: Acid neutralizer is used to neutralize 80-98% of ammonia, and the remaining ammonia and water components are removed by adsorption using Nafion-coated modified molecular sieve.

7. The method for removing ammonia from crude hydroxy silicone oil according to claim 6, wherein: The Nafion-coated modified molecular sieve preparation method comprises: spraying a Nafion™ perfluorinated resin solution onto the surface of a commercial molecular sieve using a coating machine; and drying and activating the Nafion-coated molecular sieve at 50-100°C for 10-30 minutes to obtain the Nafion-coated modified molecular sieve.

8. The method for removing ammonia from crude hydroxy silicone oil according to claim 7, wherein: The mass concentration of Nafion™ perfluorinated resin solution is 1-20%; During the spraying process, the film thickness is controlled at 0.1-100μm.

9. The method for removing ammonia from crude hydroxy silicone oil according to claim 1, 7 or 8, wherein: The acid neutralizer can also be a product obtained by soaking a modified Nafion-coated molecular sieve in any one of hydrochloric acid, nitric acid, sulfuric acid, oxalic acid, and acetic acid for 12-24 hours.

10. The method for removing ammonia from crude hydroxy silicone oil according to claim 9, wherein: The acid concentration of hydrochloric acid, nitric acid, sulfuric acid, oxalic acid, and acetic acid is 0.1-5wt%.

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