End-capped polyether modified polysiloxane and preparation method thereof

Abstract

The invention relates to terminated polyether modified polysiloxane, the molecular structure of the terminated polyether modified polysiloxane is # imgabs0 #. The invention also provides a preparation method of the terminated polyether modified polysiloxane, and the preparation method comprises the following steps: (1) preparing long-chain alkyl hydrogen-containing silicone oil; (2) preparing allyl-terminated polyether; and (3) preparing the terminated polyether modified polysiloxane. The invention aims to select an end-capping structure with a specific structure, improve the purity of the product, reduce byproducts and lower the cloud point of the product.

Description

Technical Field

[0001] The invention relates to the technical field of defoamers, and in particular to a blocked polyether-modified polysiloxane and a preparation method thereof. Background Art

[0002] Defoamer is one of the indispensable additives in many production processes. It has been widely used in various fields such as chemical industry, food, textile, coating, petroleum, papermaking and printing and dyeing. There are many types of defoamers with different properties. According to the composition, they can be divided into non-silicon type, polyether type, silicone type and silicone ether mixed type.

[0003] Non-silicone raw materials such as mineral oil are easy to obtain, but their defoaming efficiency is low; polyether type has strong antifoaming ability, but poor bubble breaking ability; silicone type has low surface tension, good thermal stability, and strong chemical stability, but its antifoaming ability is weak; silicone ether mixed type is a hydrophilic polyether introduced into the polysiloxane chain by chemical means, organically combining the advantages of silicone defoamer and polyether defoamer, and has good and lasting defoaming and antifoaming effects whether in water phase or oil phase.

[0004] At present, many studies have been conducted on organosilicon modified defoamers at home and abroad, mainly focusing on the synthesis of polyether modified polysiloxane and the compounding of polyether modified polysiloxane defoamers. The research on synthesis mainly focuses on optimizing the molecular structure of polyether, synthesis process parameters, etc., and the research on compounding mainly focuses on screening suitable additives (such as emulsifiers, thickeners, dispersants, etc.) to ensure the stable storage of defoamers. However, there are few studies on the end-capping modification of low hydrogen silicone oil and single-terminal allyl ethylene oxide and propylene oxide copolyether (referred to as terminal allyl polyether) from the molecular structure to change the structure of polyether modified polysiloxane. Based on this, the present invention proposes a capped polyether modified polysiloxane and a preparation method thereof. Summary of the invention

[0005] The purpose of the present invention is to provide a blocked polyether-modified polysiloxane and a preparation method thereof, select a blocking structure with a specific structure, improve the purity of the product, reduce by-products, and lower the cloud point of the product.

[0006] In a first aspect, the present invention provides a blocked polyether-modified polysiloxane, wherein the molecular structure of the blocked polyether-modified polysiloxane is shown in Structural Formula 1: Structural formula 1.

[0007] In a second aspect, the present invention provides a method for preparing a capped polyether-modified polysiloxane, the steps comprising: (1) Preparation of long-chain alkyl hydrogenated silicone oil: Stir the alkyl-terminated double-capped silicone oil with hydrogenated silicone oil under the catalytic condition of concentrated sulfuric acid, react for 3-5 hours at a temperature not higher than 60°C, add sodium bicarbonate to adjust the pH to neutral; vacuum filter to obtain a colorless and transparent product;

[0008] (2) Preparation of terminal allyl polyether: Propylene alcohol, propylene oxide, ethylene oxide, alkali catalyst and initiator propenyl alcohol are replaced with nitrogen in a closed environment, and bubbling dehydration is carried out at a temperature of 100-110°C, and then a portion of propylene oxide is added, and another portion of propylene oxide is added after the reaction is stable; after the reaction is complete, the temperature is lowered, ethylene oxide is added, and the reaction is kept warm for aging. After the pressure stops decreasing, bubbling degassing is carried out, and glacial acetic acid is added to neutralize when the temperature is lowered and the pressure is normal, and hydrogen peroxide is added after stirring for decolorization, and the acid value of the product is detected after n-butyl etherification, and then an antioxidant is added to stir the reaction, and the material is cooled to obtain a light yellow terminal allyl polyether; (3) Preparation of end-capped polyether-modified polysiloxane: Stir and mix hydrogen-containing silicone oil and end-allyl polyether in a closed environment, replace with nitrogen, and dehydrate by bubbling at a temperature of 100-110°C. Then, add xylene and Pt-based catalyst, and keep the temperature at 75-85°C for reaction. As the reactants gradually become transparent, the Si-H content no longer changes. After the reaction is completed, vacuum distillation is performed to remove xylene and other low-boiling substances to obtain end-capped polyether-modified polysiloxane.

[0009] Furthermore, the mass fraction of hydrogen in the hydrogen-containing silicone oil is 1.5%-1.6%.

[0010] Furthermore, the weight ratio of the alkyl-terminated double cap, hydrogen-containing silicone oil, concentrated sulfuric acid and sodium bicarbonate is (400-470): (130-150): (40-48): (70-90).

[0011] Furthermore, the Pt-based catalyst includes one of chloroplatinic acid, Speier catalyst, and Karstedt's catalyst.

[0012] Furthermore, the nitrogen replacement step includes: firstly pumping the negative pressure to below -0.095MPa, then filling with nitrogen to 0.05MPa, and repeating 2-4 times.

[0013] Furthermore, the weight ratio of the mixture of propylene alcohol, propylene oxide and ethylene oxide, the base catalyst, propylene alcohol, propylene oxide, ethylene oxide, glacial acetic acid, hydrogen peroxide and antioxidant is (90-110): (0.25-0.35): (90-96): (120-140): (74-82): (0.2-0.4): (0.4-0.6): (2.5-3.5); the weight ratio of propylene alcohol, propylene oxide and ethylene oxide is 1:1.4:1.1.

[0014] Furthermore, the antioxidant is citric acid / sodium citrate, and w(citric acid / sodium citrate)=1%.

[0015] Furthermore, the alkaline catalyst includes potassium hydroxide or sodium hydroxide.

[0016] Furthermore, the weight ratio of the hydrogen silicone oil, terminal allyl polyether, xylene and catalyst is (560-600): (280-320): (250-350): (0.2-0.4).

[0017] The present invention uses a low-hydrogen-containing end-capped silicone oil and an end-allyl polyether treated with an anti-oxidant by a citric acid / sodium citrate compound under a platinum catalyst to carry out a silylation reaction under mild experimental conditions, thereby synthesizing a new self-emulsifying defoamer with higher purity and the advantages of both a silicone defoamer and a polyether defoamer. The defoamer and the anti-foaming performance are improved to a certain extent compared with the comparative defoamer. In addition, the end-capped polyether-modified polysiloxane has no hydroxyl group, has higher chemical stability, avoids oxidation and dehydration that would occur under high temperature conditions, and the end-capped polyether-modified polysiloxane with an added structure and a well-designed structure has a wider practical application range and is more targeted.

[0018] The main active ingredient in the polyether-modified polysiloxane defoamer is silicone oil-modified polyether, which contains a hydrophobic silicone oil segment and a hydrophilic polyether segment. The synthesis route of the polyether-modified polysiloxane mainly includes the preparation of low-hydrogen silicone oil, the synthesis of single-end allyl polyether, and the steps of silylation reaction. The invention introduces a silane group into the silicone oil segment to increase the hydrophobic group, reduce water solubility, improve surface properties and dispersibility, promote solid film rupture, make the foam unstable, and enhance the defoaming effect; In the hydrosilylation reaction, polyethers containing alkenyl groups and polysiloxanes containing active hydrogen are expected to generate Si-C bonds under the action of catalysts, but polyethers containing alkenyl groups and hydroxyl groups will almost inevitably generate Si-OC bonds during the siloxane addition reaction, causing crosslinking in the copolymer and reducing the product quality. Therefore, in order to ensure the smooth progress of the addition reaction and reduce the occurrence of side reactions, it is necessary to cap the hydroxyl group at the other end of the polyether before hydrosilylation to produce a polyether with a specific structure, so that the reaction generates a relatively pure Si-C type polyether modified silicone oil.

[0019] Products using end-capped allyl polyethers have lower surface tension and foam height than those using uncapped allyl polyethers. This is because the end alkyl group has lower energy and hydrophobicity than the end hydroxyl group, and the cloud point is significantly reduced, which is more conducive to achieving low-temperature defoaming properties. DETAILED DESCRIPTION

[0020] The technical solution of the present invention is described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. Example

[0021] This embodiment provides a blocked polyether-modified polysiloxane, and the molecular structure of the blocked polyether-modified polysiloxane is shown in Structural Formula 1: Structural formula 1.

[0022] The end-capped polyether-modified polysiloxane mainly includes long-chain alkyl hydrogenated silicone oil, n-butyl etherified single-end allyl ethylene oxide and propylene oxide copolymer (taking the preparation of 1 kg of product as an example).

[0023] 1. The preparation method of long-chain alkyl hydrogen-containing silicone oil is as follows: In a 500 mL four-necked flask equipped with an electric stirrer, a thermometer, and a reflux condenser, add 435 g of alkyl-terminated double-capped and 145 g of hydrogen-containing silicone oil with a hydrogen mass fraction of 1.55, and then add 44 g of concentrated sulfuric acid as a catalyst. Start stirring to react. Ensure that the temperature in the flask is not higher than 60 °C during the whole process. After reacting for 5 h and cooling to room temperature, slowly add 80 g of sodium bicarbonate to neutralize and adjust the pH to neutral.

[0024] A vacuum pump is then used for filtration to reduce the negative pressure of the filtrate to less than -0.095 MPa, thereby removing unreacted raw materials and small molecules, and the product obtained is a colorless and transparent liquid. Among them, the mass ratio of the alkyl-terminated double head and the hydrogen-containing silicone oil is 3:1.

[0025] The formula for preparing hydrogenated silicone oil is as follows:

[0026] 2. The preparation method of the n-butyl etherified single-end allyl ethylene oxide and propylene oxide copolyether is as follows: The reaction raw material is a mixture of propylene alcohol, propylene oxide and ethylene oxide with a total weight of 100, wherein the weight ratio of propylene alcohol, propylene oxide and ethylene oxide is 1:1.4:1.1; After the reactor leak test, 0.3% of the total mass of the raw materials, sodium hydroxide (0.3 g), an alkaline catalyst, and 93 g of initiator propylene alcohol were added to the autoclave. The reactor was sealed, stirring was started, and nitrogen was replaced three times. First, the negative pressure was pumped to below -0.095 MPa, and then nitrogen was filled to 0.05 MPa. This was repeated three times. After the replacement was completed, the vacuum was pumped to below -0.095 MPa, the temperature was raised to 105 °C, and bubbling dehydration was performed for 1 hour. Specifically, nitrogen was slowly bubbled while vacuum pumping to ensure that the pressure was less than -0.095 MPa. Then, about 30 g of PO was pressed into the propylene oxide (PO) storage tank. After the reaction was stable, the remaining about 100 g of PO was slowly added dropwise, and the reaction temperature was maintained at 115 °C. After the PO reaction is complete, the temperature is lowered to 107 °C, and 78 g of ethylene oxide (EO) is added, and the reaction temperature is maintained at 115 °C; after the addition is completed, the reaction is kept warm and aged until the pressure in the kettle returns to -0.1 MPa. After the pressure stops decreasing, nitrogen bubbling is used for degassing for 10 minutes; after the degassing is completed, the temperature is lowered to below 70 °C, nitrogen is pressurized to normal pressure, and then 0.3 g of glacial acetic acid is added for neutralization. After stirring for 10 minutes, 0.5 g of hydrogen peroxide is added for decolorization. After n-butyl etherification, the acid value of the product is detected, and nitrogen is blown until the acid value of the product is less than 0.4 mgKOH / g, and the blowing is stopped; then 3 g of citric acid / sodium citrate compound is used as an antioxidant for antioxidant treatment, and the dosage is w (citric acid / sodium citrate) = 1%, and the reaction is carried out at 80 °C for 1 hour under stirring. During this process, nitrogen is kept blowing; finally, the material is cooled and discharged; the color of the terminal allyl polyether is light yellow; 3. The preparation method of the end-capped polyether-modified polysiloxane is as follows: After the leak test, 580 g of low-hydrogen silicone oil and 300 g of terminal allyl polyether were weighed, of which the polyether was in excess, and they were put into the reactor together. The reactor was sealed, stirring was started, and nitrogen was replaced three times. Specifically, the negative pressure was first pumped to below -0.095 MPa, and then nitrogen was filled to 0.05 MPa, and this was repeated three times. After the replacement was completed, the vacuum was pumped to below 0.095 MPa, the temperature was raised to 105 °C, and bubbling dehydration was performed for 1 hour. Specifically, nitrogen was slowly bubbled while vacuum pumping to ensure that the pressure was less than -0.095 MPa; then 300 g of solvent xylene was added, and after the solution in the bottle was mixed uniformly, the temperature was raised to 60 °C and 0.3 g of Speier catalyst was added. After the induction period, the reaction was exothermic and a temperature rise of about 15 °C was generated; at 80 The reaction was kept warm at ℃, and the reactants gradually became transparent as the reaction progressed; the Si-H content of the reactants was tracked and measured, and the reaction endpoint was determined when the Si-H content no longer changed; after the reaction was completed, xylene and other low-boiling substances were removed by vacuum distillation to obtain end-capped polyether-modified polysiloxane.

[0027] Performance testing method: (1) Thermal stability: Take 5 g of the defoamer sample, put it into a sealed test tube, and then place it in an oven set at 60 °C for 48 h. After taking it out, cool it to room temperature and observe whether the defoamer is stable.

[0028] (2) Centrifugal stability: Add 8 mL of the defoamer sample to a 10 mL centrifuge tube, set the centrifuge speed to 3 000 r / min, and centrifuge for 30 min to observe whether the defoamer is stable.

[0029] (3) Water dispersibility: Add 1 g of defoamer sample to a measuring cylinder containing 100 mL of water, shake and observe the dispersion effect in water. If it is difficult to disperse in water and white flocs appear, the water dispersibility is poor; if the diffusion speed in water is slow and only a small amount of white flocs appear, the water dispersibility is good; if it disperses quickly and evenly in water, the water dispersibility is excellent.

[0030] (4) Defoaming and antifoaming performance test method: The compound defoamer and commercially available silicone defoamer samples and polyether defoamer samples were tested for defoaming performance in the following high temperature, strong acid and alkaline foaming solutions: a 0.5% sodium dodecylbenzene sulfonate aqueous solution was adjusted to pH 13.0 with alkali solution and heated to 85°C as foaming solution A, and then a sodium dodecylbenzene sulfonate aqueous solution of the same volume and mass concentration was adjusted to pH 2.0 with acid and heated to 85°C as foaming solution B. The defoaming performance of the selected defoamers was tested using a Roche foam instrument. The addition amount of the three defoamers was selected to be 100*10 -6 , record the defoaming and antifoaming time.

[0031] The test results are shown in the following table: Table 1

[0032] Finally, it should be noted that the above embodiments are only used to illustrate the present invention and are not intended to limit the technical solutions described in the present invention. Those skilled in the art should understand that the present invention can still be modified or replaced by equivalents. All technical solutions and improvements that do not depart from the spirit and scope of the present invention should be included in the scope of the claims of the present invention.

Claims

1. A blocked polyether-modified polysiloxane, characterized in that: The molecular structure of the end-capped polyether-modified polysiloxane is shown in Structural Formula 1: Structural formula 1.

2. The method for preparing a blocked polyether-modified polysiloxane according to claim 1, characterized in that the steps include: (1) Preparation of long-chain alkyl hydrogenated silicone oil: Stir the alkyl-terminated double-capped silicone oil with hydrogenated silicone oil under the catalytic condition of concentrated sulfuric acid, react for 3-5 hours at a temperature not higher than 60°C, add sodium bicarbonate to adjust the pH to neutral; vacuum filter to obtain a colorless and transparent product; (2) Preparation of terminal allyl polyether: Propylene alcohol, propylene oxide, ethylene oxide, alkali catalyst and initiator propenyl alcohol are replaced with nitrogen in a closed environment, and bubbling dehydration is carried out at a temperature of 100-110°C, and then a portion of propylene oxide is added, and another portion of propylene oxide is added after the reaction is stable; after the reaction is complete, the temperature is lowered, ethylene oxide is added, and the reaction is kept warm for aging. After the pressure stops decreasing, bubbling degassing is carried out, and glacial acetic acid is added to neutralize when the temperature is lowered and the pressure is normal, and hydrogen peroxide is added after stirring for decolorization, and the acid value of the product is detected after n-butyl etherification, and then an antioxidant is added to stir the reaction, and the material is cooled to obtain a light yellow terminal allyl polyether; (3) Preparation of end-capped polyether-modified polysiloxane: Stir and mix hydrogen-containing silicone oil and end-allyl polyether in a closed environment, replace with nitrogen, and dehydrate by bubbling at a temperature of 100-110°C. Then, add xylene and Pt-based catalyst, and keep the temperature at 75-85°C for reaction. As the reactants gradually become transparent, the Si-H content no longer changes. After the reaction is completed, vacuum distillation is performed to remove xylene and other low-boiling substances to obtain end-capped polyether-modified polysiloxane.

3. The method for preparing a blocked polyether-modified polysiloxane according to claim 2, characterized in that: The mass fraction of hydrogen in the hydrogen-containing silicone oil is 1.5%-1.6%.

4. The method for preparing a blocked polyether-modified polysiloxane according to claim 2, characterized in that: The weight ratio of the alkyl-terminated double cap, hydrogen-containing silicone oil, concentrated sulfuric acid and sodium bicarbonate is (400-470): (130-150): (40-48): (70-90).

5. The method for preparing a blocked polyether-modified polysiloxane according to claim 2, characterized in that: The Pt-based catalyst includes one of a Speier catalyst and a Karstedt's catalyst.

6. The method for preparing a blocked polyether-modified polysiloxane according to claim 2, characterized in that: The nitrogen replacement step includes: firstly pumping the negative pressure to below -0.095MPa, then filling with nitrogen to 0.05MPa, and repeating 2-4 times.

7. The method for preparing a blocked polyether-modified polysiloxane according to claim 2, characterized in that: The weight ratio of the mixture of propylene alcohol, propylene oxide and ethylene oxide, the base catalyst, propylene alcohol, propylene oxide, ethylene oxide, glacial acetic acid, hydrogen peroxide and antioxidant is (90-110): (0.25-0.35): (90-96): (120-140): (74-82): (0.2-0.4): (0.4-0.6): (2.5-3.5); the weight ratio of propylene alcohol, propylene oxide and ethylene oxide is 1:1.4:1.

1.

8. The method for preparing a blocked polyether-modified polysiloxane according to claim 2, characterized in that: The antioxidant is citric acid / sodium citrate, and w(citric acid / sodium citrate)=1%.

9. The method for preparing a blocked polyether-modified polysiloxane according to claim 2, characterized in that: The base catalyst includes potassium hydroxide or sodium hydroxide.

10. The method for preparing a blocked polyether-modified polysiloxane according to claim 2, characterized in that: The weight ratio of the hydrogen silicone oil, terminal allyl polyether, xylene and catalyst is (560-600): (280-320): (250-350): (0.2-0.4).

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