Preparation method of sodium polyacrylate

Abstract

The invention discloses a preparation method of sodium polyacrylate, which belongs to the technical field of food processing, and comprises the following steps: weighing a certain amount of acrylic acid, diluting with deionized water, adding into a multi-neck flask, preparing a NaOH solution with a certain concentration, stirring, adding into the flask until a neutralization reaction is completed to obtain a sodium acrylate solution, and adding the sodium acrylate solution into a reaction kettle for reaction; taking a certain amount of activated carbon for adsorption treatment, carrying out suction filtration to obtain a sodium acrylate refined solution, and repeatedly vacuumizing for multiple times; according to the method, on the basis of a redox initiator (ammonium persulfate-sodium hydrogen sulfite), a high-efficiency chain extender dimethylaminopropionitrile is added to form a composite initiation system, and the influence of the addition amount of the composite initiator, the monomer concentration, the reaction time and the reaction temperature on the viscosity of the prepared sodium polyacrylate is discussed respectively. Then, optimal preparation process conditions are determined through an orthogonal test, and the performance of the prepared sodium polyacrylate is measured, so that the practical application effect of the whole method is greatly improved.

Description

Technical Field

[0001] The invention belongs to the technical field of food processing, and in particular relates to a preparation method of sodium polyacrylate. Background Art

[0002] As a high molecular weight vinyl polymer, sodium polyacrylate has been widely used at home and abroad in recent years and is one of the commonly used fine chemical products. Due to its different degree of polymerization, its molecular weight ranges from hundreds to tens of millions, and different molecular weights affect its properties and uses. At present, sodium polyacrylate is widely used in environmental protection, water treatment, petrochemicals, food, medicine and other fields.

[0003] In the field of food production, sodium polyacrylate can also be used as a food additive to thicken, strengthen and preserve food, with good effects. Generally speaking, the aqueous solution polymerization method is commonly used to produce sodium polyacrylate. This method uses water as the medium, acrylic acid and sodium hydroxide are neutralized, and the polymerization reaction is initiated by adding an initiator. The initiator is a key factor affecting the polymerization reaction rate and the molecular weight of the polymer. The initiator is easy to decompose into free radicals. It is weak in structure, and its dissociation energy is much lower than the CC bond energy. If it is under high heat or collision, it may cause an explosion. There are many types of initiators that can be used for free radical initiation. In the preparation process of sodium polyacrylate, the commonly used initiators are mainly peroxide initiators (thermal cracking), oxidation-reduction initiators and composite initiation systems. The free radical cracking temperature of the persulfate initiator is 70~90℃. This initiation temperature will make the polymerization reaction violent and difficult to control, and it is easy to explode. The performance of the obtained copolymer is not as good as that of the oxidation-reduction initiator. In order to solve this problem, a preparation method of sodium polyacrylate is urgently needed. Summary of the invention

[0004] The purpose of the present invention is to solve the common aqueous solution polymerization method for producing sodium polyacrylate today. This method uses water as a medium, acrylic acid is neutralized with sodium hydroxide, and the polymerization reaction is initiated by adding an initiator. The initiator is a key factor affecting the polymerization reaction rate and the molecular weight of the polymer. The initiator is easy to decompose into free radicals. It is weak in structure, and its dissociation energy is much lower than the CC bond energy. If it is under high heat or collision, it may cause an explosion. There are many types of initiators that can be used for free radical initiation. In the preparation process of sodium polyacrylate, the commonly used initiators mainly include peroxide initiators (thermal cracking), oxidation-reduction initiators and composite initiation systems. The free radical cracking temperature of the persulfate initiator is 70-90°C. This initiation temperature will make the polymerization reaction violent and difficult to control, and it is easy to explode. The performance of the obtained copolymer is not as good as that of the oxidation-reduction initiator, and a method for preparing sodium polyacrylate is proposed.

[0005] In order to achieve the above object, the present invention adopts the following technical scheme: a method for preparing sodium polyacrylate, comprising the following steps: S1. Weigh a certain amount of acrylic acid, dilute it with deionized water, and add it into a multi-necked flask; S2. Prepare a NaOH solution of a certain concentration, add it to the flask with stirring until the neutralization reaction is completed, and obtain a sodium acrylate solution; S3, taking a certain amount of activated carbon for adsorption treatment, filtering to obtain a refined sodium acrylate liquid, repeatedly evacuating the vacuum several times, filling with high-purity nitrogen for a period of time, and maintaining the system under anaerobic conditions to cause polymerization reaction; S4, adding the composite initiator along with nitrogen, and after the initiator is added, transferring the polymerization liquid to the designated area; S5, controlling the reaction temperature in the reaction tank and maintaining it for a period of time; S6. After the polymerization reaction is complete, the reactants are granulated and placed in a drying powder device, and dried and crushed at a certain temperature to obtain a sodium polyacrylate sample; S7, measuring the performance of the finished product; S8. Store and preserve the finished products.

[0006] As a further description of the above technical solution: In S1, a certain amount of acrylic acid is weighed, diluted with deionized water, and added into a four-necked flask, and a stirrer and a thermometer are arranged in the four-necked flask.

[0007] As a further description of the above technical solution: In the S2, a NaOH solution with a concentration of 30-35% is prepared and added into the flask with stirring until the neutralization reaction is completed to obtain a sodium acrylate solution.

[0008] As a further description of the above technical solution: In the S3, a certain amount of activated carbon is taken for adsorption treatment, and the purified sodium acrylate liquid is obtained by filtration, and the vacuum is repeatedly drawn for 3-5 times, and high-purity nitrogen is filled for 8-12 minutes to keep the system in anoxic conditions for polymerization reaction.

[0009] As a further description of the above technical solution: In the S4, a composite initiator is added along with nitrogen. After the initiator is added, the polymerization liquid is transferred to a plastic intestine. The composite initiator is composed of ammonium persulfate-sodium bisulfite and dimethylaminopropionitrile.

[0010] As a further description of the above technical solution: In S5, the reaction temperature in the reaction tank is controlled to 50-70° C. and maintained for 15-20 minutes.

[0011] As a further description of the above technical solution: In S6, after the polymerization reaction is complete, the reactants are granulated and placed in a drying powder device, and dried and crushed at a temperature of 100-130° C. to obtain a sodium polyacrylate sample.

[0012] As a further description of the above technical solution: In S7, the performance of the finished product is measured, and the specific steps are: dissolving a certain amount of sodium polyacrylate powder in a certain amount of deionized water to prepare a sodium polyacrylate solution with a mass fraction of 0.1-0.2%, standing for 40-45 minutes, and measuring its apparent viscosity at room temperature after the powder is completely dissolved.

[0013] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are: In this method, a reducing agent is added to the peroxide, and its free radicals can be generated in the controlled process of the oxidation-reduction reagent, thereby reducing the activation energy of the peroxide to generate free radicals, and the polymerization reaction of the initiating monomer can be carried out at a lower temperature, and the polymerization rate can be increased. The composite initiation system is often based on a redox initiator, and a high-efficiency chain extender and an initiation catalyst are added to form a more efficient initiation system, which greatly improves the redox reaction rate, reduces the initiation temperature, and increases the viscosity of the polymer. In this method, a high-efficiency chain extender dimethylaminopropionitrile is added to the redox initiator (ammonium persulfate-sodium bisulfite) to form a composite initiation system. The effects of the amount of composite initiator added, monomer concentration, reaction time, and reaction temperature on the viscosity of the prepared sodium polyacrylate are discussed respectively, and then the optimal preparation process conditions are determined by orthogonal experiments, and the performance of the prepared sodium polyacrylate is measured, which greatly improves the practical application effect of the overall method. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 The present invention is a flow chart of a method for preparing sodium polyacrylate. DETAILED DESCRIPTION

[0015] The following will be combined with 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. Example 1

[0016] See also Figure 1 The present invention provides a technical solution: a method for preparing sodium polyacrylate, comprising the following steps: S1. Weigh a certain amount of acrylic acid, dilute it with deionized water, and add it into a four-necked flask, and configure a stirrer and a thermometer in the four-necked flask; S2, prepare a 30% NaOH solution, add it to the flask with stirring until the neutralization reaction is completed, and obtain a sodium acrylate solution; S3, taking a certain amount of activated carbon for adsorption treatment, filtering to obtain a refined sodium acrylate liquid, repeatedly evacuating the vacuum for 3 times, filling with high-purity nitrogen for 8 minutes, and maintaining the system under anaerobic conditions to cause polymerization reaction; S4, adding a composite initiator along with nitrogen, and after the initiator is added, transferring the polymer solution to a plastic intestine, wherein the composite initiator is composed of ammonium persulfate-sodium bisulfite and dimethylaminopropionitrile; S5, controlling the reaction temperature in the reaction tank to 50°C and maintaining it for 15 minutes; S6. After the polymerization reaction is complete, the reactants are granulated and placed in a drying powder device, and dried and crushed at a temperature of 100° C. to obtain a sodium polyacrylate sample; S7, measuring the performance of the finished product, the specific steps of which are: dissolving a certain amount of sodium polyacrylate powder in a certain amount of deionized water to prepare a sodium polyacrylate solution with a mass fraction of 0.1%, standing for 40 minutes, and measuring its apparent viscosity at room temperature after the powder is completely dissolved; S8. Store and preserve the finished products.

[0017] In this embodiment, the method adds a reducing agent to the peroxide, and its free radicals can be generated in the controlled process of the oxidation-reduction reagent, thereby reducing the activation energy of the peroxide to generate free radicals, and the polymerization reaction of the initiating monomer can be carried out at a lower temperature and the polymerization rate can be increased. Example 2

[0018] See also Figure 1 The present invention provides a technical solution: a method for preparing sodium polyacrylate, comprising the following steps: S1. Weigh a certain amount of acrylic acid, dilute it with deionized water, and add it into a four-necked flask, and configure a stirrer and a thermometer in the four-necked flask; S2, prepare a 32% NaOH solution, add it to the flask with stirring until the neutralization reaction is completed, and obtain a sodium acrylate solution; S3, taking a certain amount of activated carbon for adsorption treatment, filtering to obtain a refined solution of sodium acrylate, repeatedly evacuating the solution 3 times, filling with high-purity nitrogen for 10 minutes, and maintaining the system under anaerobic conditions to cause polymerization reaction; S4, adding a composite initiator along with nitrogen, and after the initiator is added, transferring the polymer solution to a plastic intestine, wherein the composite initiator is composed of ammonium persulfate-sodium bisulfite and dimethylaminopropionitrile; S5, controlling the reaction temperature in the reaction tank to 60°C and maintaining it for 17 minutes; S6. After the polymerization reaction is complete, the reactants are granulated and placed in a drying powder device, and dried and crushed at a temperature of 110° C. to obtain a sodium polyacrylate sample; S7, measuring the performance of the finished product, the specific steps of which are: dissolving a certain amount of sodium polyacrylate powder in a certain amount of deionized water to prepare a sodium polyacrylate solution with a mass fraction of 0.1%, standing for 42 minutes, and measuring its apparent viscosity at room temperature after the powder is completely dissolved; S8. Store and preserve the finished products.

[0019] In this embodiment, the composite initiation system is often based on a redox initiator, and a high-efficiency chain extender and an initiation catalyst are added to form a more efficient initiation system, which greatly increases the redox reaction rate, reduces the initiation temperature, increases the polymer viscosity, etc. Example 3

[0020] See also Figure 1 The present invention provides a technical solution: a method for preparing sodium polyacrylate, comprising the following steps: S1. Weigh a certain amount of acrylic acid, dilute it with deionized water, and add it into a four-necked flask, and configure a stirrer and a thermometer in the four-necked flask; S2, prepare a 35% NaOH solution, add it to the flask with stirring until the neutralization reaction is completed, and obtain a sodium acrylate solution; S3, taking a certain amount of activated carbon for adsorption treatment, filtering to obtain a refined sodium acrylate liquid, repeatedly evacuating the vacuum for 5 times, filling with high-purity nitrogen for 12 minutes, and maintaining the system under anaerobic conditions to cause polymerization reaction; S4, adding a composite initiator along with nitrogen, and after the initiator is added, transferring the polymer solution to a plastic intestine, wherein the composite initiator is composed of ammonium persulfate-sodium bisulfite and dimethylaminopropionitrile; S5, controlling the reaction temperature in the reaction tank to 70°C and maintaining it for 20 minutes; S6. After the polymerization reaction is complete, the reactants are granulated and placed in a drying powder device, and dried and crushed at a temperature of 130° C. to obtain a sodium polyacrylate sample; S7, measuring the performance of the finished product, the specific steps of which are: dissolving a certain amount of sodium polyacrylate powder in a certain amount of deionized water to prepare a sodium polyacrylate solution with a mass fraction of 0.2%, standing for 45 minutes, and measuring its apparent viscosity at room temperature after the powder is completely dissolved; S8. Store and preserve the finished products.

[0021] In this embodiment, this method selects to add a high-efficiency chain extender dimethylaminopropionitrile to the redox initiator (ammonium persulfate-sodium bisulfite) to form a composite initiation system, and discusses the effects of the amount of composite initiator added, monomer concentration, reaction time, and reaction temperature on the viscosity of the prepared sodium polyacrylate. Then, the optimal preparation process conditions are determined through orthogonal experiments, and the performance of the prepared sodium polyacrylate is measured, which greatly improves the practical application effect of the overall method. Example 4

[0022] See also Figure 1 The present invention provides a technical solution: a method for preparing sodium polyacrylate, comprising the following steps: S1. Weigh a certain amount of acrylic acid, dilute it with deionized water, and add it into a four-necked flask, and configure a stirrer and a thermometer in the four-necked flask; S2, prepare a 33% NaOH solution, add it to the flask with stirring until the neutralization reaction is completed, and obtain a sodium acrylate solution; S3, taking a certain amount of activated carbon for adsorption treatment, filtering to obtain a refined sodium acrylate liquid, repeatedly evacuating the vacuum for 5 times, filling with high-purity nitrogen for 12 minutes, and maintaining the system under anaerobic conditions to cause polymerization reaction; S4, adding a composite initiator along with nitrogen, and after the initiator is added, transferring the polymer solution to a plastic intestine, wherein the composite initiator is composed of ammonium persulfate-sodium bisulfite and dimethylaminopropionitrile; S5, controlling the reaction temperature in the reaction tank to 68°C and maintaining it for 18 minutes; S6. After the polymerization reaction is complete, the reactants are granulated and placed in a drying powder device, and dried and crushed at a temperature of 130° C. to obtain a sodium polyacrylate sample; S7, measuring the performance of the finished product, the specific steps of which are: dissolving a certain amount of sodium polyacrylate powder in a certain amount of deionized water to prepare a sodium polyacrylate solution with a mass fraction of 0.2%, standing for 45 minutes, and measuring its apparent viscosity at room temperature after the powder is completely dissolved; S8. Store and preserve the finished products.

[0023] In this embodiment, the method adds a reducing agent to the peroxide, and its free radicals can be generated in the controlled process of the oxidation-reduction reagent, thereby reducing the activation energy of the peroxide to generate free radicals, and the polymerization reaction of the initiating monomer can be carried out at a lower temperature, and the polymerization rate can be increased. The composite initiation system is often based on a redox initiator, and a high-efficiency chain extender and an initiation catalyst are added to form a more efficient initiation system, which greatly improves the redox reaction rate, reduces the initiation temperature, increases the viscosity of the polymer, etc., and the method selects to add a high-efficiency chain extender dimethylaminopropionitrile on the basis of the redox initiator (ammonium persulfate-sodium bisulfite) to form a composite initiation system, and discusses the effects of the amount of composite initiator added, monomer concentration, reaction time, and reaction temperature on the viscosity of the prepared sodium polyacrylate, and then determines the optimal preparation process conditions through orthogonal experiments, and the prepared sodium polyacrylate is tested for performance, which greatly improves the practical application effect of the overall method.

[0024] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A method for preparing sodium polyacrylate, characterized in that: The steps include: S1. Weigh a certain amount of acrylic acid, dilute it with deionized water, and add it into a multi-necked flask; S2. Prepare a NaOH solution of a certain concentration, add it to the flask with stirring until the neutralization reaction is completed, and obtain a sodium acrylate solution; S3, taking a certain amount of activated carbon for adsorption treatment, filtering to obtain a refined sodium acrylate liquid, repeatedly evacuating the vacuum several times, filling with high-purity nitrogen for a period of time, and maintaining the system under anaerobic conditions to cause polymerization reaction; S4, adding the composite initiator along with nitrogen, and after the initiator is added, transferring the polymerization liquid to the designated area; S5, controlling the reaction temperature in the reaction tank and maintaining it for a period of time; S6. After the polymerization reaction is complete, the reactants are granulated and placed in a drying powder device, and dried and crushed at a certain temperature to obtain a sodium polyacrylate sample; S7, measuring the performance of the finished product; S8. Store and preserve the finished products.

2. The method for preparing sodium polyacrylate according to claim 1, wherein In S1, a certain amount of acrylic acid is weighed, diluted with deionized water, and added into a four-necked flask, and a stirrer and a thermometer are arranged in the four-necked flask.

3. A method for preparing sodium polyacrylate according to claim 1, characterized in that, In the S2, a NaOH solution with a concentration of 30-35% is prepared and added into the flask with stirring until the neutralization reaction is completed to obtain a sodium acrylate solution.

4. The method for preparing sodium polyacrylate according to claim 1, wherein In the S3, a certain amount of activated carbon is taken for adsorption treatment, and the purified sodium acrylate liquid is obtained by filtration, and the vacuum is repeatedly drawn for 3-5 times, and high-purity nitrogen is filled for 8-12 minutes to keep the system in anoxic conditions for polymerization reaction.

5. The method for preparing sodium polyacrylate according to claim 1, wherein In the S4, a composite initiator is added along with nitrogen. After the initiator is added, the polymerization liquid is transferred to a plastic intestine. The composite initiator is composed of ammonium persulfate-sodium bisulfite and dimethylaminopropionitrile.

6. The method for preparing sodium polyacrylate according to claim 1, characterized in that: In S5, the reaction temperature in the reaction tank is controlled to 50-70° C. and maintained for 15-20 minutes.

7. The method for preparing sodium polyacrylate according to claim 1, characterized in that: In S6, after the polymerization reaction is complete, the reactants are granulated and placed in a drying powder device, and dried and crushed at a temperature of 100-130° C. to obtain a sodium polyacrylate sample.

8. The method for preparing sodium polyacrylate according to claim 1, characterized in that: In S7, the performance of the finished product is measured, and the specific steps are: dissolving a certain amount of sodium polyacrylate powder in a certain amount of deionized water to prepare a sodium polyacrylate solution with a mass fraction of 0.1-0.2%, standing for 40-45 minutes, and measuring its apparent viscosity at room temperature after the powder is completely dissolved.

Images