Preparation method of foam inhibiting and defoaming agent for polyvinyl alcohol (PVA) aqueous solution

Abstract

The invention discloses a preparation method of a foam inhibiting and defoaming agent for a polyvinyl alcohol (PVA) aqueous solution, which comprises the following preparation steps: S1, preparing raw materials including ethylene oxide, propylene oxide, polyethylene glycol (PEG), absolute ethyl alcohol, a catalyst and silicone oil; according to the method, organic pollutants in the reactor are effectively removed, microbial cleaning not only has high selectivity and environmental protection property, but also can be carried out under mild conditions, damage of chemical cleaning agents to equipment is avoided, the organic pollutants in the reactor can be more thoroughly removed, and the method is suitable for industrial production. Residues possibly generated by a traditional chemical cleaning method are reduced, the cleaning effect is improved, the method does not depend on harmful chemicals, potential hazards to the environment and personnel are reduced, the requirement of green chemistry is met, the inner wall of the reactor is fully cleaned, residues of previous reactants or catalysts are avoided, the reaction purity can be improved, and the production cost is reduced. Generation of by-products is reduced, and the stability and quality of the final product are improved.

Description

Technical Field

[0001] The invention belongs to the technical field of defoamer preparation, and specifically relates to a method for preparing a defoamer for a polyvinyl alcohol (PVA) aqueous solution. Background Art

[0002] In the preparation or application process of polyvinyl alcohol aqueous solution, the generation of foam is reduced or eliminated by adding antifoaming agents. PVA itself forms foam due to its dissolution process, concentration adjustment or processing applications (such as coating, spinning, wet stretching, etc.), so antifoaming agents are needed to help remove or inhibit the generation of foam.

[0003] In the prior art, the foam suppressant and defoamer for polyvinyl alcohol (PVA) aqueous solution often requires the use of a large amount of chemical reagents during the preparation process by traditional cleaning methods (such as physical cleaning, chemical cleaning, etc.), which may cause some chemical cleaning agents to be corrosive or toxic, pollute the environment after use, and the residues are not easy to remove. In addition, cleaning usually requires the consumption of a large amount of cleaning agents, and the cleaning process is complicated. In addition, the traditional cleaning method may not be able to effectively remove the complex organic matter in the reactor, especially some high-molecular substances or dirt with strong adhesion. The residual pollutants in the tiny gaps or inaccessible areas on the inner wall of the reactor may participate in the reaction in the next reaction, resulting in a decrease in the purity of the reaction product, and may even generate unexpected side effects, resulting in poor use effect and reduced preparation quality. Summary of the invention

[0004] In view of the deficiencies in the prior art, the present invention provides a method for preparing a foam suppressant and defoamer for a polyvinyl alcohol (PVA) aqueous solution.

[0005] To achieve the above object, the present invention provides the following technical solution: a method for preparing a foam suppressant and defoamer for a polyvinyl alcohol (PVA) aqueous solution, comprising the following preparation steps:

[0006] S1. Raw material preparation

[0007] Including: ethylene oxide, propylene oxide, polyethylene glycol (PEG), anhydrous ethanol, catalyst and silicone oil;

[0008] S2. Reactor cleaning and preheating

[0009] The reactor was cleaned using deionized water, ethanol, and microbial cleaning methods;

[0010] Heat the reactor to 50-60°C;

[0011] S3. Polyetherification reaction

[0012] Polyethylene glycol (PEG) was added into the reactor as a starting material;

[0013] Adding an appropriate amount of heterogeneous catalyst and ethylene oxide (EO);

[0014] The reaction is heated at 150-200°C, and the reaction temperature and pressure are maintained stable, during which the epoxy compound reacts with the polyether group to generate a polyether compound;

[0015] After the reaction is completed, the molecular weight of the polyether is measured and controlled by adjusting the reaction time and the ratio of raw materials;

[0016] S4. Termination of reaction and cooling

[0017] After the reaction is completed, add an appropriate amount of terminator to terminate the reaction and reduce over-polymerization;

[0018] Fluidized bed cooling technology is used to cool the reaction system to room temperature (20-25°C);

[0019] S5. Solvent cleaning and separation

[0020] The reaction product is filtered to separate unreacted catalyst and impurities;

[0021] The reaction product is washed multiple times with anhydrous ethanol to remove impurities dissolved in the solvent;

[0022] filtering and collecting the washed polyether compound;

[0023] S6. Dissolution and dilution

[0024] Mix the polyether defoamer with an appropriate amount of solvent and dilute to the target concentration;

[0025] Stir and dissolve to form a stable defoaming solution;

[0026] S7, Final cleaning and filtration

[0027] The dissolved defoamer is filtered again to remove undissolved solid particles;

[0028] Cooling and re-filtration are performed to make the final defoamer solution clear, uniform and free of impurities.

[0029] Preferably, in S2, the selected microorganisms are esterase and lipase producing microorganisms, and the cultured microorganisms and enzymes are inoculated into the reactor, the inoculation amount is 1%-10%, the culture temperature is 30°C-40°C, the culture pH is 5.5-8.5, the culture dissolved oxygen content is 5-10 mg / L, and the time for microbial cleaning is controlled at 52-72 hours.

[0030] Preferably, in S3, the reaction pressure maintained is 0.5-1 MPa, and the reaction time is 3-5 hours.

[0031] Preferably, in S4, the terminator is an alcohol. When performing the termination operation, the terminator is gradually dripped into the reactor by a dropwise addition method. A titration device is used to slowly drip the alcohol terminator into the reaction system. Stirring is performed during the dripping process. The stirring time is 8-15 minutes and the dripping speed is 1-10 mL / min.

[0032] Preferably, in S4, the polymer after the reaction is transported to a fluidized bed system for cooling treatment, and the air flow velocity is 0.2-0.5 m / s.

[0033] Preferably, in S3, the heterogeneous catalyst is a molecular sieve catalyst, specifically one or any one of ZSM-5 and Y-type molecular sieve, the heterogeneous catalyst loading is 1%-5% of the reactants, the activation temperature of the heterogeneous catalyst is 300-500°C, and the activation time is 1-4 hours.

[0034] Preferably, the concentration of the polyether defoamer after dilution is controlled between 10% and 30%.

[0035] The beneficial effects of the present invention are as follows:

[0036] (1) The present invention adopts a microbial cleaning method and utilizes specific microorganisms (such as esterase, lipase, etc.) to degrade and remove organic pollutants in the reactor. The microorganisms can decompose complex organic matter (such as oil, fatty acid, etc.) through the action of their enzymes, thereby effectively removing organic pollutants in the reactor. Microbial cleaning not only has high selectivity and environmental protection, but also can be carried out under milder conditions, avoiding damage to equipment by chemical cleaning agents, and can more thoroughly remove organic pollutants in the reactor, reduce residues that may be generated by traditional chemical cleaning methods, improve cleaning effects, do not rely on harmful chemicals, reduce potential hazards to the environment and personnel, and meet the requirements of green chemistry. The inner wall of the reactor is fully cleaned to avoid residues of previous reactants or catalysts, which helps to improve the purity of the reaction, reduce the generation of by-products, and improve the stability and quality of the final product.

[0037] (2) The present invention adopts a heterogeneous catalyst, which is in a different phase from the reactants, and can increase the reaction rate under certain conditions to promote the polymerization reaction of ethylene oxide and polyethylene glycol. The advantages of heterogeneous catalysts are their high selectivity, recyclability and adjustability. Molecular sieve catalysts can enhance the adsorption and conversion efficiency of reactants through their unique pore structure and surface acidity. The heterogeneous catalyst significantly accelerates the rate of polyetherification reaction by providing surface active sites and reduces the reaction time (3-5 hours), thereby improving production efficiency, allowing the reaction to be carried out under milder conditions. At the same time, the molecular weight and molecular structure of the polymer can be accurately controlled by adjusting the catalyst loading and reaction conditions. The use of heterogeneous catalysts allows the catalysts to be separated and reused by simple physical methods (such as filtration and recovery), which not only saves costs but also reduces environmental pollution. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 It is a schematic diagram of the preparation process of the present invention. DETAILED DESCRIPTION

[0039] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. 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.

[0040] like Figure 1 As shown, a method for preparing a foam suppressant and defoamer for a polyvinyl alcohol (PVA) aqueous solution comprises the following preparation steps:

[0041] S1. Raw material preparation

[0042] The invention comprises: ethylene oxide, propylene oxide, polyethylene glycol (PEG), anhydrous ethanol, a catalyst and silicone oil; the two epoxy compounds are key monomers for preparing polyether compounds, and they react with polyethylene glycol (PEG) to generate a polyether chain structure, ethylene oxide is mainly used for synthesizing the basic structure of polyether, and propylene oxide is used for adjusting the properties of the final polymer, such as hydrophilicity and hydrophobicity, PEG, as a starting material, provides a polymerizing group (—OH) for the polyetherification reaction, and the molecular weight and structure of PEG directly affect the properties of the polymer (such as defoaming effect, rheological properties, etc.), anhydrous ethanol is used as a solvent or a cleaning agent, and ethanol can dissolve some impurities and by-products generated during the dissolution reaction; the catalyst (especially a heterogeneous catalyst) is used to promote the polymerization reaction of the epoxy compound and the polyethylene glycol, and the selection and dosage of the catalyst directly affect the reaction rate, efficiency and molecular structure of the final product; silicone oil, as an additive, is used to adjust the rheological properties and stability of the final defoamer and improve the defoaming effect.

[0043] S2. Reactor cleaning and preheating

[0044] The reactor was cleaned using deionized water, ethanol, and microbial cleaning methods;

[0045] Heat the reactor to 50-60°C;

[0046] Using deionized water, ethanol and microbial cleaning to clean the reactor can remove residues, impurities or pollutants in the reactor. Deionized water can remove inorganic impurities, and ethanol helps remove organic pollutants. The microbial cleaning method can effectively decompose organic pollutants and reduce residual impurities, especially grease and other insoluble substances, to ensure the purity of subsequent reactions. Heating the reactor to 50-60°C provides a suitable temperature environment for subsequent operations of the polymerization reaction. Preheating helps to reduce the viscosity of the reaction system, allowing the raw materials to be mixed more evenly and promoting the reaction.

[0047] S3. Polyetherification reaction

[0048] Polyethylene glycol (PEG) was added into the reactor as a starting material;

[0049] Adding an appropriate amount of heterogeneous catalyst and ethylene oxide (EO);

[0050] The reaction is heated at 150-200°C, and the reaction temperature and pressure are maintained stable, during which the epoxy compound reacts with the polyether group to generate a polyether compound;

[0051] After the reaction is completed, the molecular weight of the polyether is measured and controlled by adjusting the reaction time and the ratio of raw materials;

[0052] S4. Termination of reaction and cooling

[0053] After the reaction is completed, add an appropriate amount of terminator to terminate the reaction and reduce over-polymerization;

[0054] Fluidized bed cooling technology is used to cool the reaction system to room temperature (20-25°C);

[0055] S5. Solvent cleaning and separation

[0056] The reaction product is filtered to separate unreacted catalyst and impurities;

[0057] The reaction product is washed multiple times with anhydrous ethanol to remove impurities dissolved in the solvent;

[0058] filtering and collecting the washed polyether compound;

[0059] By filtering, unreacted catalysts, epoxy compounds, solvents and other impurities are separated from the reaction products, which can improve the purity of the polyether compounds and avoid the influence of catalyst residues on the subsequent defoamer performance. Anhydrous ethanol is used for multiple washings to remove impurities dissolved in the solvent, such as unreacted ethylene oxide, solvents or by-products. The washing operation can effectively purify the polyether compounds, reduce the impurity content and improve their purity. The washed polyether compounds are collected by filtration to ensure that the final product does not contain undissolved solid particles.

[0060] S6. Dissolution and dilution

[0061] Mix the polyether defoamer with an appropriate amount of solvent and dilute to the target concentration;

[0062] Stir and dissolve to form a stable defoaming solution;

[0063] Mix the polyether defoamer with an appropriate amount of solvent and dilute it to the target concentration (10%-30%) to convert the polyether defoamer into the final liquid form for easy storage and use. During the dissolution process, stirring helps promote uniform mixing, prevent the formation of lumps or precipitation, and ensure the stability of the final defoaming solution.

[0064] S7, Final cleaning and filtration

[0065] The dissolved defoamer is filtered again to remove undissolved solid particles;

[0066] Cooling and re-filtration are performed to make the final defoamer solution clear, uniform and free of impurities.

[0067] The dissolved defoamer is filtered again to remove undissolved solid particles to ensure that the final product does not contain solid impurities; the defoamer solution is made stable at room temperature through cooling operation. The filtration process can ensure the clarity and uniformity of the defoamer and ensure that its quality meets the requirements.

[0068] In S2, the selected microorganisms are those that produce esterase and lipase, and the cultured microorganisms and enzymes are inoculated into the reactor, the inoculation amount is 1%-10%, the culture temperature is 30℃-40℃, the culture pH is 5.5-8.5, the culture dissolved oxygen content is 5-10mg / L, and the time for microbial cleaning is controlled at 52-72 hours.

[0069] In S3, the reaction pressure is maintained at 0.5-1 MPa and the reaction time is 3-5 hours.

[0070] PEG provides a reactive hydroxyl group (—OH) to undergo polymerization reaction with epoxy compounds to generate a polyether structure. Heterogeneous catalysts (such as ZSM-5 or Y-type molecular sieves) can promote the reaction of ethylene oxide and polyethylene glycol and improve the polymerization efficiency. The loading amount (1%-5%) of the heterogeneous catalyst determines the catalytic activity, which can effectively accelerate the reaction rate and adjust the molecular weight distribution of the product. Ethylene oxide reacts with PEG to generate polyether compounds. The molecular weight and structure of the polyether can be controlled by adjusting the reaction temperature (150-200°C) and pressure (0.5-1MPa); the reaction time is 3-5 hours, during which time ethylene oxide and polyethylene glycol undergo polymerization reaction to generate polyether compounds. By adjusting the reaction time and the ratio of raw materials, the molecular weight of the generated polyether compound can be accurately controlled, thereby affecting the performance of the defoamer.

[0071] In S4, the terminator is an alcohol. When performing the termination operation, the terminator is gradually dripped into the reactor by a dropwise method. A titration device is used to slowly drip the alcohol terminator into the reaction system. Stirring is performed during the dripping process. The stirring time is 8-15 minutes. The dripping speed is 1-10 mL / min. The polymer after the reaction is transported to a fluidized bed system for cooling. The air flow velocity is 0.2-0.5 m / s.

[0072] Adding terminators (such as alcohols) terminates the polymerization reaction and prevents the polymer from continuing to grow excessively (excessive polymerization may lead to excessive viscosity or the formation of unstable products). During the addition of the terminator, the titration equipment can accurately control the addition rate of the terminator (1-10mL / min) to ensure the gentle termination of the reaction. The reaction system is introduced into the fluidized bed for cooling, which is an efficient heat exchange technology. The air flow rate is 0.2-0.5m / s, which can reduce the temperature of the reaction system to room temperature (20-25℃) in a short time, while ensuring that the reaction product does not crystallize or agglomerate during the cooling process, maintaining uniformity and stability.

[0073] In S3, the heterogeneous catalyst is a molecular sieve catalyst, specifically one or any one of ZSM-5 and Y-type molecular sieve, the heterogeneous catalyst loading is 1%-5% of the reactants, the activation temperature of the heterogeneous catalyst is 300-500°C, and the activation time is 1-4 hours.

[0074] The concentration of the polyether defoamer after dilution is controlled between 10% and 30%.

[0075] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a foam suppressant and defoamer for a polyvinyl alcohol (PVA) aqueous solution, characterized in that: The method comprises the following preparation steps: S1. Raw material preparation Including: ethylene oxide, propylene oxide, polyethylene glycol (PEG), anhydrous ethanol, catalyst and silicone oil; S2. Reactor cleaning and preheating The reactor was cleaned using deionized water, ethanol, and microbial cleaning methods; Heat the reactor to 50-60°C; S3. Polyetherification reaction Polyethylene glycol (PEG) was added into the reactor as a starting material; Adding an appropriate amount of heterogeneous catalyst and ethylene oxide (EO); The reaction is heated at 150-200°C, and the reaction temperature and pressure are maintained stable, during which the epoxy compound reacts with the polyether group to generate a polyether compound; After the reaction is completed, the molecular weight of the polyether is measured and controlled by adjusting the reaction time and the ratio of raw materials; S4. Termination of reaction and cooling After the reaction is completed, add an appropriate amount of terminator to terminate the reaction and reduce over-polymerization; Fluidized bed cooling technology is used to cool the reaction system to room temperature (20-25°C); S5. Solvent cleaning and separation The reaction product is filtered to separate unreacted catalyst and impurities; The reaction product is washed multiple times with anhydrous ethanol to remove impurities dissolved in the solvent; filtering and collecting the washed polyether compound; S6. Dissolution and dilution Mix the polyether defoamer with an appropriate amount of solvent and dilute to the target concentration; Stir and dissolve to form a stable defoaming solution; S7, Final cleaning and filtration The dissolved defoamer is filtered again to remove undissolved solid particles; Cooling and re-filtration are performed to make the final defoamer solution clear, uniform and free of impurities.

2. The method for preparing a foam suppressant and defoamer for a polyvinyl alcohol (PVA) aqueous solution according to claim 1, characterized in that: In S2, the selected microorganisms are esterase and lipase producing microorganisms, and the cultured microorganisms and enzymes are inoculated into the reactor, the inoculation amount is 1%-10%, the culture temperature is 30°C-40°C, the culture pH is 5.5-8.5, the culture dissolved oxygen content is 5-10 mg / L, and the time for microbial cleaning is controlled at 52-72 hours.

3. The method for preparing a foam suppressant and defoamer for polyvinyl alcohol (PVA) aqueous solution according to claim 1, characterized in that: In S3, the reaction pressure is maintained at 0.5-1 MPa and the reaction time is 3-5 hours.

4. The method for preparing a foam suppressant and defoamer for polyvinyl alcohol (PVA) aqueous solution according to claim 1, characterized in that: In S4, the terminator is an alcohol. When performing the termination operation, the terminator is gradually dripped into the reactor by a dropwise addition method. The alcohol terminator is slowly dripped into the reaction system using a titration device. Stirring is performed during the dripping process. The stirring time is 8-15 minutes and the dripping speed is 1-10 mL / min.

5. The method for preparing a foam suppressant and defoamer for polyvinyl alcohol (PVA) aqueous solution according to claim 1, characterized in that: In S4, the polymer after the reaction is transported to a fluidized bed system for cooling, and the air flow velocity is 0.2-0.5 m / s.

6. The method for preparing a foam suppressant and defoamer for polyvinyl alcohol (PVA) aqueous solution according to claim 1, characterized in that: In S3, the heterogeneous catalyst is a molecular sieve catalyst, specifically one or any one of ZSM-5 and Y-type molecular sieve, the heterogeneous catalyst loading is 1%-5% of the reactants, the activation temperature of the heterogeneous catalyst is 300-500°C, and the activation time is 1-4 hours.

7. The method for preparing a foam suppressant and defoamer for polyvinyl alcohol (PVA) aqueous solution according to claim 1, characterized in that: The concentration of the polyether defoamer after dilution is controlled between 10% and 30%.

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