Polyacrylamide aqueous dispersion as well as synthesis method and application thereof

Abstract

The invention discloses a polyacrylamide aqueous dispersion as well as a synthesis method and application thereof, and relates to the technical field of polyacrylamide synthesis. The synthesis method of the polyacrylamide aqueous dispersion comprises the following steps: carrying out a reaction I on a reaction system of acrylamide I, a cationic monomer I, an inorganic salt, a stabilizer, an easily hydrolyzable acrylate monomer and an initiator I to obtain the polyacrylamide aqueous dispersion; wherein the stabilizer is a cationic copolymer of a polyacrylamide chain segment; the prepared polyacrylamide aqueous dispersion has excellent stability, and destabilization does not occur after the polyacrylamide aqueous dispersion is placed at room temperature for more than 6 months.

Description

Technical Field

[0001] The invention relates to the technical field of polyacrylamide synthesis, and in particular to a polyacrylamide aqueous dispersion and a synthesis method and application thereof. Background Art

[0002] Polyacrylamide has good water solubility and high viscosity increasing ability, so it is widely used in many fields such as water treatment, oil recovery, papermaking, textile, etc. Aqueous phase dispersion polymerization is an important method for preparing polyacrylamide aqueous dispersion. This method obtains polyacrylamide aqueous dispersion by polymerizing acrylamide in an inorganic salt aqueous solution in the presence of a specific stabilizer.

[0003] At present, the biggest problem in preparing polyacrylamide aqueous dispersions by aqueous phase dispersion polymerization is that the apparent viscosity is high, resulting in poor stability of the aqueous dispersion. Generally speaking, conventional polyacrylamide aqueous dispersions will show stratification after being stored for several weeks to several months. Reducing the concentration of polyacrylamide or appropriately increasing the concentration of inorganic salts can increase the apparent viscosity of polyacrylamide aqueous dispersions. However, the concentration of polyacrylamide means that the content of effective substances in the dispersion is reduced; appropriately increasing the concentration of inorganic salts will often reduce the long-term storage stability of polyacrylamide aqueous dispersions.

[0004] At present, low apparent viscosity polyacrylamide aqueous dispersion is a difficulty in the synthesis of polyacrylamide aqueous dispersion. Summary of the invention

[0005] The present invention aims at the problems existing in the synthesis of aqueous polyacrylamide dispersion in the prior art, and prepares aqueous polyacrylamide dispersion with low apparent viscosity by dispersion polymerization, wherein the stabilizer of the dispersion polymerization is a cationic copolymer containing polyacrylamide chain segments; different from other methods, in the process of synthesizing the aqueous cationic polyacrylamide dispersion, the present invention introduces an acrylate monomer that is easily decomposed into anions, and obtains aqueous polyacrylamide dispersion with low apparent viscosity through the interaction of anionic polyacrylic acid formed by in-situ hydrolysis and cationic polyacrylamide.

[0006] In order to solve the above technical problems, the first aspect of the present invention provides a method for synthesizing an aqueous polyacrylamide dispersion, comprising reacting a reaction system of acrylamide I, a cationic monomer I, an inorganic salt, a stabilizer, an easily hydrolyzed acrylate monomer and an initiator I to obtain the aqueous polyacrylamide dispersion; wherein the stabilizer is a cationic copolymer of a polyacrylamide segment.

[0007] According to some embodiments of the present invention, the mass ratio of acrylamide I, cationic monomer I, inorganic salt, easily hydrolyzed acrylic ester monomer and stabilizer is 36:4.32; 10:(1-2):270, preferably 36:4.32; 10:1.5:270.

[0008] According to some embodiments of the present invention, the added amount of the initiator I is 0.1% to 0.5% of the mass of the acrylamide I.

[0009] According to some embodiments of the present invention, the cationic monomer I is selected from one or more of acryloyloxyethyl trimethyl ammonium chloride, methacryloyloxyethyl trimethyl ammonium chloride, dimethyl diallyl ammonium chloride, acryloyloxyethyl dimethyl benzyl ammonium chloride, methacryloyloxyethyl dimethyl benzyl ammonium chloride, and 2-acrylamido-2-methylpropyl trimethyl ammonium chloride.

[0010] According to some embodiments of the present invention, the inorganic salt is selected from ammonium salts; preferably, the ammonium salt is selected from at least one of ammonium sulfate and ammonium persulfate.

[0011] According to some embodiments of the present invention, the initiator I is selected from aqueous thermal initiator I and / or redox initiator I; preferably, the aqueous thermal initiator I is selected from at least one of V-50 and VA-044; the redox initiator I is selected from at least two of ammonium persulfate, sodium bisulfite, and potassium persulfate.

[0012] According to some embodiments of the present invention, the easily hydrolyzable acrylic acid ester monomer is selected from at least one of tert-butyl acrylate, tert-butyl methacrylate, phenyl acrylate and phenyl methacrylate.

[0013] According to some embodiments of the present invention, the conditions of reaction I include: temperature of 25° C. to 45° C., and time of 1 hour to 6 hours.

[0014] According to some embodiments of the present invention, the preparation of the stabilizer comprises: in the presence of an initiator II and an inactive atmosphere, mixing a cationic monomer II and acrylamide II in water to obtain a mixed solution, and performing a reaction II to obtain the stabilizer.

[0015] According to some embodiments of the present invention, the mass ratio of the cationic monomer II, acrylamide II and water is (40-90):(60-84):160, preferably 72:60:160, 48:84:160.

[0016] According to some embodiments of the present invention, the added amount of the initiator II is 0.1% to 0.5% of the mass of the cationic monomer II.

[0017] According to some embodiments of the present invention, the cationic monomer II is selected from one or more of acryloyloxyethyl trimethyl ammonium chloride, methacryloyloxyethyl trimethyl ammonium chloride, dimethyl diallyl ammonium chloride, acryloyloxyethyl dimethyl benzyl ammonium chloride, methacryloyloxyethyl dimethyl benzyl ammonium chloride, and 2-acrylamido-2-methylpropyl trimethyl ammonium chloride.

[0018] According to some embodiments of the present invention, the initiator II is selected from aqueous thermal initiator II and / or redox initiator II; preferably, the aqueous thermal initiator II is selected from at least one of V-50 and VA-044; the redox initiator II is selected from at least two of ammonium persulfate, sodium bisulfite, and potassium persulfate.

[0019] According to some embodiments of the present invention, the inactive atmosphere is selected from at least one of nitrogen and argon.

[0020] According to some embodiments of the present invention, the conditions of reaction II include: temperature of 30° C. to 80° C., and reaction time of 5 hours to 10 hours.

[0021] According to some embodiments of the present invention, the reaction II further includes dilution; preferably, the stabilizer is cooled to room temperature, and then a certain amount of water is added to dilute the stabilizer to a mass concentration of 5wt% to 10wt% to obtain an aqueous solution of the cationic copolymer containing polyacrylamide segments.

[0022] The second aspect of the present invention provides an aqueous polyacrylamide dispersion obtained by using the above method for synthesizing an aqueous polyacrylamide dispersion.

[0023] A third aspect of the present invention provides a use of the above-mentioned aqueous dispersion of polyacrylamide as a flocculant in sewage and / or wastewater treatment.

[0024] Beneficial effects:

[0025] The polyacrylamide aqueous dispersion prepared by the invention has low apparent viscosity and is therefore easy to use.

[0026] The polyacrylamide aqueous dispersion prepared by the present invention has good stability and no destabilization occurs after being placed at room temperature for 6 months.

[0027] The polyacrylamide aqueous dispersion prepared by the invention can be used as a flocculant and can be widely used in environmental protection fields such as sewage and wastewater treatment in industries such as petrochemicals, printing, steelmaking and papermaking. DETAILED DESCRIPTION

[0028] The present invention will be further described below in conjunction with the embodiments, but the present invention is not limited by these embodiments.

[0029] The three-necked flask and three-necked bottle used in the examples of the present invention are common commercially available products unless otherwise specified.

[0030] In the present invention, methacryloyloxyethyltrimethylammonium chloride, acrylamide, phenyl acrylate, tert-butyl acrylate, VA-044 initiator, ammonium sulfate, ammonium persulfate, and sodium bisulfite are all common commercially available reagents unless otherwise specified.

[0031] Unless otherwise specified, the room temperature in the embodiments of the present invention is 25°C.

[0032] Example 1

[0033] This embodiment provides a cationic copolymer.

[0034] In a three-necked flask, 90 g of an aqueous solution of methacryloyloxyethyltrimethylammonium chloride with a mass concentration of 80%, 60 g of acrylamide, 0.10 g of VA-044 initiator and 160 g of water were added in sequence, and nitrogen was introduced after degassing and deoxygenation. The mixture was reacted at a temperature of 45° C. for 7 hours, and then cooled to room temperature. 2330 g of water was added to dilute the mixture into an aqueous solution containing a cationic copolymer with a mass concentration of 5%, i.e., stabilizer A1.

[0035] Example 2

[0036] This embodiment provides a cationic copolymer.

[0037] In a three-necked flask, 60 g of an aqueous solution of methacryloyloxyethyltrimethylammonium chloride with a mass concentration of 80%, 84 g of acrylamide, 0.10 g of VA-044 initiator and 160 g of water were added in sequence, and nitrogen was introduced after degassing and deoxygenation. The mixture was reacted at a temperature of 45° C. for 7 hours, and then cooled to room temperature. 2330 g of water was added to dilute the mixture into an aqueous solution containing a cationic copolymer with a mass concentration of 5%, i.e., stabilizer A2.

[0038] Example 3

[0039] This embodiment provides an aqueous dispersion of polyacrylamide.

[0040] At room temperature, 36 g of acrylamide, 5.4 g of an aqueous solution of 80% methacryloyloxyethyltrimethylammonium chloride, 1.5 g of phenyl acrylate, 270 g of the above-mentioned stabilizer A1 (an aqueous solution containing a cationic copolymer with a mass concentration of 5%) and 10 g of ammonium sulfate were added to a three-necked flask equipped with a stirring paddle, and the mixture was stirred until all the added materials were completely dissolved. The mixture was then degassed and deoxygenated and filled with nitrogen. The temperature was raised to 45° C., 1 mL of a degassed and deoxygenated VA-044 aqueous solution (the concentration of the VA-044 aqueous solution was 40 mg / mL) was added, the reaction was continued for 6 hours, the heating source was removed, the reaction was stopped, and a polyacrylamide aqueous dispersion B1 was obtained.

[0041] Example 4

[0042] This embodiment provides an aqueous dispersion of polyacrylamide.

[0043] At room temperature, 36 g of acrylamide, 5.4 g of an aqueous solution of methacryloyloxyethyltrimethylammonium chloride with a mass concentration of 80%, 1.5 g of phenyl acrylate, 270 g of the stabilizer A1 (aqueous solution containing a cationic copolymer with a mass concentration of 5%) and 10 g of ammonium sulfate were added to a three-necked flask equipped with a stirring paddle, and the mixture was stirred until all the added materials were completely dissolved. Then, nitrogen was charged after degassing and deoxygenation, and the temperature was raised to 30° C., and 0.60 mL of a degassed and deoxygenated aqueous solution of ammonium persulfate (the concentration of the aqueous solution of ammonium persulfate was 40 mg / mL) and 0.40 mL of an aqueous solution of sodium bisulfite (the concentration of the aqueous solution of sodium bisulfite was 40 mg / mL) were added respectively, and the reaction was continued for 6 hours. The heating source was removed to stop the reaction to obtain an aqueous polyacrylamide dispersion B2.

[0044] Example 5

[0045] This embodiment provides an aqueous dispersion of polyacrylamide.

[0046] At room temperature, 36 g of acrylamide, 5.4 g of an aqueous solution of methacryloyloxyethyltrimethylammonium chloride with a mass concentration of 80%, 1.5 g of tert-butyl acrylate, 270 g of the above-mentioned stabilizer A2 (an aqueous solution containing a cationic copolymer with a mass concentration of 5%) and 10 g of ammonium sulfate were added to a three-necked flask equipped with a stirring paddle, and the mixture was stirred until all the added materials were completely dissolved. The mixture was then degassed and deoxygenated and filled with nitrogen. The temperature was raised to 45° C., 1 mL of a degassed and deoxygenated VA-044 aqueous solution (the concentration of the VA-044 aqueous solution was 40 mg / mL) was added, the reaction was continued for 6 hours, the heating source was removed, the reaction was stopped, and a polyacrylamide aqueous dispersion B3 was obtained.

[0047] Comparative Example 1

[0048] This comparative example provides an aqueous dispersion of polyacrylamide.

[0049] At room temperature, 36 g of acrylamide, 5.4 g of an aqueous solution of methacryloyloxyethyltrimethylammonium chloride with a mass concentration of 80%, 270 g of stabilizer A1 (an aqueous solution of a cationic copolymer with a mass concentration of 5%) and 10 g of ammonium sulfate were added to a three-necked flask equipped with a stirring paddle, and the mixture was stirred until all the added materials were completely dissolved. The mixture was then degassed and deoxygenated and filled with nitrogen. The temperature was raised to 45° C., 1 mL of a degassed and deoxygenated aqueous solution of VA-044 (the concentration of the aqueous solution of VA-044 was 40 mg / mL) was added, and the reaction was continued for 6 hours. The heating source was removed to stop the reaction to obtain an aqueous polyacrylamide dispersion B4.

[0050] Comparative Example 2

[0051] This comparative example provides an aqueous dispersion of polyacrylamide.

[0052] At room temperature, 36 g of acrylamide, 5.4 g of an aqueous solution of methacryloyloxyethyltrimethylammonium chloride with a mass concentration of 80%, 270 g of stabilizer A1 (an aqueous solution of a cationic copolymer with a mass concentration of 5%) and 10 g of ammonium sulfate were added to a three-necked flask equipped with a stirring paddle, and the mixture was stirred until all the added materials were completely dissolved. The mixture was then degassed and deoxygenated and filled with nitrogen. The mixture was heated to 30° C., and 0.60 mL of an aqueous solution of ammonium persulfate (the concentration of the aqueous solution of ammonium persulfate was 40 mg / mL) and 0.40 mL of an aqueous solution of sodium bisulfite (the concentration of the aqueous solution of sodium bisulfite was 40 mg / mL) were added respectively. The reaction was continued for 6 hours, and the heating source was removed to stop the reaction to obtain an aqueous polyacrylamide dispersion B5.

[0053] Test Case

[0054] (I) Stabilizer parameters

[0055] The basic parameters of stabilizers A1-A2 prepared in Examples 1-2 of the present invention are shown in Table 1.

[0056] In Table 1, the appearance, solid content, and viscosity of stabilizers A1-A2 were tested with reference to GB / T 11175-2002;

[0057] The viscosity test instrument is Brookfield viscometer DV1, and the viscosity determination method is: direct testing at a temperature of 25°C.

[0058] Table 1 Comparison of basic parameters of stabilizers prepared in Examples 1-2

[0059]

[0060] (II) Parameters of polyacrylamide aqueous dispersion

[0061] The basic parameters of the aqueous polyacrylamide dispersions prepared in Examples 3-5 of the present invention and Comparative Examples 1-2 are shown in Table 2.

[0062] The polymer concentration is measured by diluting a polyacrylamide aqueous dispersion of weight C1 with water to a concentration of 1% of the polyacrylamide aqueous dispersion, placing it in a dialysis bag (molecular weight cutoff size: 1000D) and dialyzing it in water for three days, then freeze-drying the sample to obtain a dry sample weight C2, and the polymer concentration is the percentage of the ratio of C2 to CI;

[0063] Among them, the apparent viscosity is the viscosity of the aqueous polyacrylamide dispersion prepared in Examples 3-5 and Comparative Examples 1-2 directly tested without dilution with water; the viscosity of the polymer solution with a mass concentration of 1% refers to the viscosity of the solution when the aqueous polyacrylamide dispersion is diluted with water to a mass concentration of polyacrylamide and its copolymer of 1%.

[0064] The stability of the aqueous polyacrylamide dispersions prepared in Examples 3-5 of the present invention and Comparative Examples 1-2 at room temperature is visually observed. If the dispersions do not separate into layers, they are stable, and if they separate into layers, they are unstable.

[0065] Table 2 Parameters of aqueous polyacrylamide dispersions prepared in Examples 3-5 of the present invention and Comparative Examples 1-2

[0066]

[0067] The results in Table 2 show that the polyacrylamide aqueous dispersions prepared in Examples 3-5 have lower apparent viscosity and higher viscosity of polymer solutions with a mass concentration of 1%, and the stability exceeds 6 months. The apparent viscosity of the polyacrylamide aqueous dispersions prepared in Comparative Examples 1 and 2 is higher, but the stability is poorer, only 3 months and 1 month. This shows that the polyacrylamide aqueous dispersion prepared in the present invention has a lower apparent viscosity.

[0068] It should be noted that the embodiments described above are only used to explain the present invention and do not constitute any limitation to the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory words, rather than restrictive words. The present invention may be modified as specified within the scope of the claims of the present invention, and the present invention may be revised without departing from the scope and spirit of the present invention. Although the present invention described therein relates to specific methods, materials and embodiments, it does not mean that the present invention is limited to the specific examples disclosed therein, on the contrary, the present invention can be extended to all other methods and applications with the same functions.

Claims

1. A method for synthesizing an aqueous dispersion of polyacrylamide, characterized in that: The method comprises the following steps: reacting a reaction system of acrylamide I, a cationic monomer I, an inorganic salt, a stabilizer, an easily hydrolyzed acrylic ester monomer and an initiator I to obtain the polyacrylamide aqueous dispersion; wherein the stabilizer is a cationic copolymer of a polyacrylamide segment.

2. The synthesis method according to claim 1, characterized in that The mass ratio of the acrylamide I, the cationic monomer I, the inorganic salt, the easily hydrolyzed acrylic ester monomer and the stabilizer is 36:4.32; 10: (1-2): 270, preferably 36: 4.32; 10：1.5：270； And / or, the added amount of the initiator I is 0.1% to 0.5% of the mass of the acrylamide I.

3. The synthesis method according to claim 2, characterized in that The cationic monomer I is selected from one or more of acryloyloxyethyl trimethyl ammonium chloride, methacryloyloxyethyl trimethyl ammonium chloride, dimethyl diallyl ammonium chloride, acryloyloxyethyl dimethyl benzyl ammonium chloride, methacryloyloxyethyl dimethyl benzyl ammonium chloride, and 2-acrylamido-2-methylpropyl trimethyl ammonium chloride; And / or, the inorganic salt is selected from ammonium salt; preferably, the ammonium salt is selected from at least one of ammonium sulfate and ammonium persulfate; And / or, the initiator I is selected from aqueous thermal initiator I and / or redox initiator I; preferably, the aqueous thermal initiator I is selected from at least one of V-50 and VA-044; the redox initiator I is selected from at least two of ammonium persulfate, sodium bisulfite and potassium persulfate; And / or, the easily hydrolyzable acrylic acid ester monomer is at least one selected from tert-butyl acrylate, tert-butyl methacrylate, phenyl acrylate, and phenyl methacrylate.

4. The preparation method according to any one of claims 1 to 3, characterized in that The conditions of the reaction I include: a temperature of 25° C. to 45° C. and a time of 1 hour to 6 hours.

5. The synthesis method according to any one of claims 1 to 4, characterized in that The preparation of the stabilizer comprises: mixing the cationic monomer II and acrylamide II in water under the conditions of an initiator II and an inactive atmosphere, and carrying out a reaction II to obtain the stabilizer.

6. The synthesis method according to claim 5, characterized in that The mass ratio of the cationic monomer II, acrylamide II and water is (40-90): (60-84): 160; And / or, the added amount of the initiator II is 0.1% to 0.5% of the mass of the cationic monomer II.

7. The synthesis method according to claim 5 or 6, characterized in that: The cationic monomer II is selected from one or more of acryloyloxyethyl trimethyl ammonium chloride, methacryloyloxyethyl trimethyl ammonium chloride, dimethyl diallyl ammonium chloride, acryloyloxyethyl dimethyl benzyl ammonium chloride, methacryloyloxyethyl dimethyl benzyl ammonium chloride, and 2-acrylamido-2-methylpropyl trimethyl ammonium chloride; And / or, the initiator II is selected from aqueous thermal initiator II and / or redox initiator II; preferably, the aqueous thermal initiator II is selected from at least one of V-50 and VA-044; the redox initiator II is selected from at least two of ammonium persulfate, sodium bisulfite and potassium persulfate; And / or, the inactive atmosphere is selected from at least one of nitrogen and argon.

8. The synthesis method according to any one of claims 5 to 7, characterized in that The conditions of the reaction II include: a temperature of 30°C to 80°C, and a reaction time of 5 hours to 10 hours; And / or, the reaction II further comprises dilution.

9. An aqueous dispersion of polyacrylamide obtained by the synthesis method according to any one of claims 1 to 8.

10. Use of the aqueous polyacrylamide dispersion obtained by the synthesis method according to any one of claims 1 to 8 or the aqueous polyacrylamide dispersion according to any one of claim 9 as a flocculant in sewage and / or wastewater treatment.

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