Composite initiation system, its use and polyacrylamide emulsion and process for its production

Abstract

The application relates to the field of petroleum chemical industry and discloses a composite initiation system, application of the composite initiation system and a polyacrylamide emulsion and a preparation method of the polyacrylamide emulsion. The composite initiation system comprises a compound A, a redox initiator and a first initiator; the first initiator is selected from azo initiators and / or peroxide initiators; wherein the compound A is at least one of compounds shown in formula I; in formula I, R1, R2 and R3 are independently C1-C5 linear alkylene, C3-C5 branched alkylene; R4, R5, R6, R7, R8 and R9 are independently C1-C3 alkyl; in formula I, X has a structure shown in formula I-1; in formula I-1, a, b and c are independently integers of 0-3. The composite initiation system is used for preparing the polyacrylamide emulsion, and the prepared polyacrylamide emulsion has the characteristics of high polymer molecular weight and strong salt resistance.

Description

Technical Field

[0001] This invention relates to the field of petrochemicals, specifically to a composite initiation system and its application, and a polyacrylamide emulsion and its preparation method. Background Technology

[0002] Polyacrylamide (PAM), as an important water-soluble polymer, has wide applications in petrochemical and other fields. Acrylamide polymers can achieve a tangled state between molecular chains at low concentrations, resulting in significant thickening effects. Industrial and laboratory synthesis of PAM mainly utilizes two types of initiators: redox systems and peroxide-based initiators. Redox initiators have advantages such as low decomposition activation energy and moderate polymerization rate, and are often used in the synthesis of hydrophobically associating polyacrylamide. However, when initiating acrylamide (AM) polymerization at lower temperatures, the presence of even a small amount of oxygen or trace impurities in the system can prolong the induction period of the polymerization reaction. Free radical polymerization of polyacrylamide is an exothermic reaction. However, because polyacrylamide is a high molecular weight compound with poor thermal conductivity, the internal heat of the polymer is difficult to remove in a short time, causing a sharp increase in temperature. This results in synthesized polyacrylamide products with poor water solubility and low molecular weight, and it is difficult to increase the solid mass fraction using existing methods. Aqueous solution polymerization is the most commonly used method for synthesizing polyacrylamide and is also the most important industrial synthesis method. Reverse emulsion polymerization involves dispersing water-soluble monomers in a non-polar liquid with the aid of an emulsifier. This allows the aqueous solution of polyacrylamide monomer to be dispersed in a continuous oil-phase medium, forming a water-in-oil emulsion for polymerization. Reverse emulsion polymerization offers advantages such as uniform heat dissipation, easy temperature control, and good polyacrylamide solubility. However, polyacrylamide produced by reverse emulsion polymerization still suffers from problems such as a wider particle size distribution and lower molecular weight.

[0003] With increasingly scarce water resources and stringent environmental protection requirements, shallow surface water and groundwater runoff are commonly used for solution preparation in construction projects. Due to their high mineralization, the high-mineralization water used in these solutions severely impacts the molecular structure of polyacrylamide polymers, significantly reducing the viscosity of the aqueous solution and even causing incompatibility with the high-mineralization water, making effective dispersion impossible. Consequently, conventional polyacrylamide solutions often fail to meet performance requirements under these conditions. Therefore, it is necessary to develop new polyacrylamide emulsions with higher molecular weights and better salt resistance. Summary of the Invention

[0004] The purpose of this invention is to overcome the problems of low polymer molecular weight and poor salt resistance in polyacrylamide emulsions in the prior art, and to provide a composite initiation system and its application, as well as a polyacrylamide emulsion and its preparation method. This composite initiation system is used to prepare polyacrylamide emulsions, so that the prepared polyacrylamide emulsions have the characteristics of high polymer molecular weight and strong salt resistance.

[0005] To achieve the above objectives, a first aspect of the present invention provides a composite initiation system, wherein the composite initiation system comprises compound A, a redox initiator, and a first initiator; the first initiator is selected from azo initiators and / or peroxide initiators;

[0006] Wherein, compound A is at least one of the compounds shown in Formula I;

[0007]

[0008] In Formula I, R1, R2, and R3 are each independently a C1-C5 straight-chain alkylene group and a C3-C5 branched alkylene group; R4, R5, R6, R7, R8, and R9 are each independently a C1-C3 alkyl group.

[0009] In Equation I, X has the structure shown in Equation I-1;

[0010]

[0011] In Equation I-1, a, b, and c are each an independent integer between 0 and 3.

[0012] A second aspect of the present invention provides the application of the above-mentioned composite initiation system in the preparation of polyacrylamide emulsions.

[0013] A third aspect of the present invention provides a method for preparing a polyacrylamide emulsion, wherein the method comprises:

[0014] (1) Acrylamide, optionally comonomer, chelating agent, emulsifier, base oil and solvent are mixed to obtain a mixture emulsion;

[0015] (2) The emulsion mixture is mixed with compound A and a redox initiator to carry out a second reaction;

[0016] (3) Add an azo initiator and / or a peroxide initiator to the product of step (2) to carry out a third reaction to obtain a polyacrylamide emulsion;

[0017] The compound A is at least one of the compounds shown in Formula I;

[0018]

[0019] In Formula I, R1, R2, and R3 are each independently a C1-C5 straight-chain alkylene group and a C3-C5 branched alkylene group; R4, R5, R6, R7, R8, and R9 are each independently a C1-C3 alkyl group.

[0020] In Equation I, X has the structure shown in Equation I-1;

[0021]

[0022] In Equation I-1, a, b, and c are each an independent integer between 0 and 3.

[0023] A fourth aspect of the present invention provides a polyacrylamide emulsion prepared by the above method.

[0024] Through the above technical solutions, the composite initiation system and its application, and the polyacrylamide emulsion and its preparation method provided by the present invention have the following beneficial effects.

[0025] The composite initiation system of the present invention contains compound A. Under the combined action of compound A, a redox initiator, and a first initiator (selected from azo initiators and / or peroxide initiators), the resulting polyacrylamide emulsion has a high polymer molecular weight, thus exhibiting excellent thickening properties and achieving high viscosity at a relatively low polymer concentration. At the same time, the polyacrylamide emulsion has good salt resistance and still exhibits good thickening properties in highly saline water. Detailed Implementation

[0026] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0027] The first aspect of the present invention provides a composite initiation system, wherein the composite initiation system comprises compound A, a redox initiator and a first initiator; the first initiator is selected from azo initiators and / or peroxide initiators;

[0028] Wherein, compound A is at least one of the compounds shown in Formula I;

[0029]

[0030] In Formula I, R1, R2, and R3 are each independently a C1-C5 straight-chain alkylene group and a C3-C5 branched alkylene group; R4, R5, R6, R7, R8, and R9 are each independently a C1-C3 alkyl group.

[0031] In Equation I, X has the structure shown in Equation I-1;

[0032]

[0033] In Equation I-1, a, b, and c are each an independent integer between 0 and 3.

[0034] In this invention, the composite initiation system contains compound A. Under the combined action of compound A, a redox initiator, and a first initiator (selected from azo initiators and / or peroxide initiators), the resulting polyacrylamide emulsion has a high polymer molecular weight, thus exhibiting excellent thickening properties and achieving high viscosity at a relatively low polymer concentration. At the same time, the polyacrylamide emulsion has good salt resistance and still exhibits excellent thickening properties in highly saline water.

[0035] In this invention, when compound A and the reducing agent are used to prepare polyacrylamide emulsion, the effects of small amounts of oxygen or trace impurities in the mixture emulsion can be eliminated, the induction period of acrylamide and optionally comonomer polymerization can be accelerated, the polymerization initiation temperature can be reduced, and the azo initiator and / or peroxide initiator can completely reduce the free monomer content by reacting unreacted acrylamide and optionally comonomer, thereby obtaining a polyacrylamide emulsion with high molecular weight and strong salt resistance.

[0036] Furthermore, in Formula I, R1, R2, and R3 are each independently a C1-C3 straight-chain alkylene group; R4, R5, R6, R7, R8, and R9 are each independently methyl or ethyl.

[0037] Furthermore, in Formula I, R4, R5, R6, R7, R8, and R9 are each independently a methyl group.

[0038] Furthermore, in Equation I-1, a, b, and c are each independently 0 or 1.

[0039] Furthermore, in Equation I-1, a, b, and c are all 0.

[0040] According to a preferred embodiment of the present invention, in Formula I, R1, R2, and R3 are all ethylenes, R4, R5, R6, R7, R8, and R9 are all methyl groups, and X has the structure shown in Formula I-1; wherein, in Formula I-1, a, b, and c are all 0.

[0041] According to the present invention, the redox initiator includes an oxidant and a reducing agent.

[0042] According to the present invention, in the composite initiation system, compound A is 0.001-0.1 parts by weight, the reducing agent is 0.001-0.5 parts by weight, the oxidizing agent is 0.001-0.5 parts by weight, and the first initiator is 0.001-0.5 parts by weight.

[0043] In this invention, when the content of each component in the composite initiation system meets the above-mentioned range, it is beneficial to obtain a polyacrylamide emulsion with high molecular weight and strong salt resistance when used to prepare a polyacrylamide emulsion.

[0044] Furthermore, in the composite initiation system, compound A is 0.005-0.05 parts by weight, the reducing agent is 0.01-0.2 parts by weight, the oxidizing agent is 0.01-0.2 parts by weight, and the first initiator is 0.01-0.2 parts by weight.

[0045] According to the present invention, the reducing agent is a sulfite and / or a thiosulfate.

[0046] In this invention, there is no particular limitation on the specific type of reducing agent. Preferably, the reducing agent is selected from at least one of sodium bisulfite, sodium sulfite, sodium metabisulfite, sodium dithionite, and sodium thiosulfate. When the above-mentioned reducing agents are used to prepare polyacrylamide emulsions, the influence of small amounts of oxygen or trace impurities in the emulsion mixture can be eliminated, the induction period of acrylamide and optionally comonomer polymerization can be accelerated, the polymerization initiation temperature can be reduced, and it is beneficial to obtain polyacrylamide emulsions with high molecular weight and strong salt resistance.

[0047] According to the present invention, the oxidant is selected from persulfate and / or hydrogen peroxide.

[0048] In this invention, there is no particular limitation on the specific type of oxidant. Preferably, the persulfate is selected from at least one of ammonium persulfate, potassium persulfate, and sodium persulfate. When the above-mentioned types of oxidants are used, a complex initiation system is formed with compound A and the reducing agent. The activation energy required during the reaction is lower, which is beneficial for initiating polymerization at a lower temperature and obtaining polymers with higher molecular weights.

[0049] In this invention, there is no particular limitation on the specific types of azo initiators and peroxide initiators. Preferably, the azo initiator is selected from at least one of azobisisobutyronitrile, azobisisovalerate, azobisisoheptanenitrile, 2,2'-azobis(2-amidinylpropane) dihydrochloride, 2,2'-azobis(2-imidazolylpropane) dihydrochloride, and 4,4'-azobis(4-cyanopentanoic acid), preferably 2,2'-azobis(2-amidinylpropane) dihydrochloride. Preferably, the peroxide initiator is selected from at least one of dicumyl peroxide, benzoyl peroxide, and hydrogen peroxide.

[0050] According to the present invention, the preparation method of compound A includes: reacting raw material 1 and raw material 2 in the presence of a solvent to obtain compound A;

[0051] Wherein, raw material 1 is a compound represented by formula II, and raw material 2 is a compound represented by formula III;

[0052]

[0053] Wherein, X' has the structure shown in Equation II-1;

[0054]

[0055] In Equation II-1, a', b', and c' are each an independent integer between 0 and 3;

[0056] In Equation III, R 10 It is a C1-C5 straight-chain alkylene or a C3-C5 branched alkylene; R 11 R 12 Each is an alkyl group that is independently C1-C3.

[0057] Furthermore, in Equation II-1, a', b', and c' are each independently 0 or 1.

[0058] Furthermore, in Equation II-1, a', b', and c' are all 0.

[0059] Furthermore, in Equation III, R 10 It is a C1-C3 straight-chain alkylene group; R 11 R 12 Each can be methyl or ethyl.

[0060] Furthermore, in Equation III, R 10 It is a C1-C3 straight-chain alkylene group; R 11 and R 12 It is a methyl group.

[0061] According to the present invention, the molar ratio of raw material 1 to raw material 2 is 0.5-2:1.

[0062] Furthermore, the molar ratio of raw material 1 to raw material 2 is 0.8-1.2:1.

[0063] According to the present invention, the solvent is selected from at least one of acetone, butanone, benzene, toluene and xylene.

[0064] According to the present invention, the temperature of the first reaction is 30-100°C, and the time of the first reaction is 1-10h.

[0065] Furthermore, the temperature of the first reaction is 35-60℃, and the reaction time is 3.5-5h.

[0066] According to the present invention, the product of the first reaction is post-treated to obtain compound A.

[0067] In this invention, there are no particular limitations on the post-treatment method; preferably, the post-treatment includes solvent removal, washing, and drying. Preferably, the solvent used for washing is selected from at least one of diethyl ether, ethanol, and methanol.

[0068] A second aspect of the present invention provides the application of the above-mentioned composite initiation system in the preparation of polyacrylamide emulsions.

[0069] In this invention, a composite initiation system containing specific components is used to prepare polyacrylamide emulsion. The resulting polyacrylamide emulsion has a high polymer molecular weight, thus exhibiting excellent thickening properties and achieving high viscosity at a relatively low polymer concentration. At the same time, the polyacrylamide emulsion has good salt resistance and still maintains good thickening properties in highly mineralized water.

[0070] A third aspect of the present invention provides a method for preparing a polyacrylamide emulsion, wherein the method comprises:

[0071] (1) Acrylamide, optionally comonomer, chelating agent, emulsifier, base oil and solvent are mixed to obtain a mixture emulsion;

[0072] (2) The emulsion mixture is mixed with compound A and a redox initiator to carry out a second reaction;

[0073] (3) Add an azo initiator and / or a peroxide initiator to the product of step (2) to carry out a third reaction to obtain a polyacrylamide emulsion;

[0074] The compound A is at least one of the compounds shown in Formula I;

[0075]

[0076] In Formula I, R1, R2, and R3 are each independently a C1-C5 straight-chain alkylene group and a C3-C5 branched alkylene group; R4, R5, R6, R7, R8, and R9 are each independently a C1-C3 alkyl group.

[0077] In Equation I, X has the structure shown in Equation I-1;

[0078]

[0079] In Equation I-1, a, b, and c are each an independent integer between 0 and 3.

[0080] The types of compound A, redox initiator, azo initiator, and peroxide initiator described in the third aspect of this invention are the same as those described in the first aspect of this invention, and therefore will not be repeated in the third aspect of this invention.

[0081] In this invention, there is no particular limitation on the type of comonomer, and those skilled in the art can select it according to actual needs. It will be understood by those skilled in the art that when the types and amounts of acrylamide and comonomer are the same, the polyacrylamide emulsion prepared using compound A of this invention has a higher molecular weight and higher salt resistance. Preferably, in step (1), the comonomer is selected from at least one of acrylic acid, 2-acrylamido-2-methylpropanesulfonic acid, N,N-dimethylacrylamide, N,N-diethylacrylamide, vinylpyrrolidone, diallyl dimethylammonium chloride, methacryloyloxyethyltrimethylammonium chloride, sodium styrene sulfonate, sodium vinyl sulfonate, sodium methyl vinyl sulfonate, sodium 2-acrylamido-dodecanesulfonate, sodium 2-acrylamido-tetradecanesulfonate, sodium 2-acrylamido-hexadecanesulfonate, dodecyl dimethyl allyl ammonium chloride, tetradecyl dimethyl allyl ammonium chloride, hexadecyl dimethyl allyl ammonium chloride, and octadecyl dimethyl allyl ammonium chloride.

[0082] According to a preferred embodiment of the present invention, the comonomer is sodium 2-acrylamido-2-methylpropanesulfonate.

[0083] According to the present invention, the chelating agent is selected from at least one of ethylenediaminetetraacetic acid tetrasodium, ethylenediaminetetraacetic acid disodium, sodium tripolyphosphate, and sodium citrate.

[0084] In this invention, when the above-mentioned chelating agents are used, they can form complexes with metal ions in water, thereby reducing the influence of metal ions on the polymerization reaction and making it easier to obtain polyacrylamide emulsions with high molecular weight and strong salt resistance.

[0085] According to the present invention, the HLB value of the emulsifier is 4-8.

[0086] In this invention, when multiple emulsifiers are used, the HLB value of the mixture of multiple emulsifiers only needs to meet the above-mentioned range.

[0087] According to the present invention, the emulsifier is a Span series emulsifier and / or a Tween series emulsifier.

[0088] In this invention, the Span series emulsifier can be selected from at least one of Span80, Span60, Span65, Span85 and Span20; the Tween series emulsifier can be selected from at least one of Tween80, Tween85, Tween60, Tween65, Tween40 and Tween20.

[0089] According to a preferred embodiment of the present invention, the emulsifier is a Span series emulsifier and a Tween series emulsifier; preferably, the mass ratio of the Span series emulsifier to the Tween series emulsifier is 1:0.1-0.5, more preferably 1:0.2-0.4.

[0090] According to the present invention, the base oil is selected from at least one of white oil, liquid paraffin, cyclohexane, kerosene isooctane, isoparaffin oil and coconut oil.

[0091] According to a preferred embodiment of the present invention, the base oil is white oil.

[0092] In this invention, there are no special limitations on the mixing conditions in step (1), as long as a uniformly dispersed emulsion can be obtained through emulsification. Preferably, the mixing time is 30-60 minutes.

[0093] According to a preferred embodiment of the present invention, step (1) includes: mixing acrylamide, optionally comonomer, chelating agent and solvent evenly, adjusting the pH to 6-8 to obtain an aqueous solution; mixing emulsifier and base oil evenly to obtain an oil solution; and stirring the aqueous solution and oil solution to obtain a mixed solution.

[0094] According to a preferred embodiment of the present invention, the stirring time is 30-60 min and the stirring temperature is 5-25℃.

[0095] In this invention, there is no special limitation on the stirring speed. For example, the stirring speed is 5000-50000 r / min.

[0096] According to the present invention, in step (1), the total amount of acrylamide and optionally comonomer is used as a basis, wherein the acrylamide is 5-100 wt% and the comonomer is 0-95 wt%.

[0097] Further, in step (1), the total amount of acrylamide and optionally comonomer is used as a basis, wherein the acrylamide is 20-90 wt% and the comonomer is 10-80 wt%.

[0098] According to the present invention, in step (1), the total amount of acrylamide and optionally comonomer is 100 parts by weight, the amount of chelating agent is 0.01-1 parts by weight, the amount of solvent is 50-200 parts by weight, the amount of emulsifier is 1-20 parts by weight, and the amount of base oil is 50-200 parts by weight.

[0099] In this invention, when the amounts of chelating agent, solvent, emulsifier and base oil meet the above ranges, the resulting polyacrylamide emulsion is more uniform and stable.

[0100] Further, the total amount of the acrylamide and optionally the comonomer is 100 parts by weight, the amount of the chelating agent is 0.05-0.5 parts by weight, the amount of the solvent is 80-150 parts by weight, the amount of the emulsifier is 5-20 parts by weight, and the amount of the base oil is 80-150 parts by weight.

[0101] According to the present invention, in step (2), the redox initiator includes an oxidant and a reducing agent.

[0102] According to the present invention, in step (2), the total amount of acrylamide and optionally comonomer is 100 parts by weight, the amount of compound A is 0.001-0.1 parts by weight, the amount of reducing agent is 0.001-0.5 parts by weight, the amount of peroxidizer is 0.001-0.5 parts by weight, and the total amount of azo initiator and / or peroxide initiator is 0.001-0.5 parts by weight.

[0103] Further, in step (2), the total amount of acrylamide and optionally comonomer is 100 parts by weight, the amount of compound A is 0.005-0.05 parts by weight, the amount of reducing agent is 0.01-0.2 parts by weight, the amount of peroxidant is 0.01-0.2 parts by weight, and the total amount of azo initiator and / or peroxide initiator is 0.01-0.2 parts by weight.

[0104] In this invention, the reducing agent, oxidizing agent, azo initiator, and peroxide initiator can be added to the mixture emulsion in solution form. For example, the concentrations of the reducing agent solution, oxidizing agent solution, azo initiator solution, and peroxide initiator solution can each be independently 3-8 wt%. The solvent in the reducing agent solution, oxidizing agent solution, azo initiator solution, and peroxide initiator solution can be water.

[0105] According to the present invention, in step (2), the temperature of the second reaction is less than or equal to 40°C.

[0106] In this invention, the second reaction is an exothermic reaction. There is no special limitation on the time of the second reaction. The mixing temperature can be less than or equal to 40°C by controlling the addition rate of the oxidant and the reducing agent.

[0107] Furthermore, in step (2), the temperature of the second reaction is 5-35℃.

[0108] According to the present invention, step (2) includes: adding compound A and a reducing agent to the emulsion mixture, and then adding an oxidizing agent for mixing.

[0109] In this invention, when the raw materials are added in the above order, it is beneficial to eliminate the influence of a small amount of oxygen or trace impurities in the emulsion mixture, accelerate the induction period of acrylamide and optionally comonomer polymerization, reduce the polymerization initiation temperature, and facilitate the acquisition of polyacrylamide emulsion with high molecular weight and strong salt resistance.

[0110] According to the present invention, in step (3), the temperature of the third reaction is 40-80°C and the reaction time is 0.5-6h.

[0111] Furthermore, in step (3), the temperature of the third reaction is 40-60℃, and the reaction time is 1-4h.

[0112] According to the present invention, a phase-inverting agent is added to the product after the third reaction.

[0113] In this invention, there is no particular limitation on the type of phase inversion agent, and conventional phase inversion agents in the art can be used. For example, the phase inversion agent can be at least one of nonylphenol polyoxyethylene ether, octylphenol polyoxyethylene ether, phenethylphenol polyoxyethylene ether, and fatty alcohol polyoxyethylene ether.

[0114] In this invention, there is no particular limitation on the amount of phase inversion agent, and those skilled in the art can adjust it according to the actual situation. Preferably, the total amount of acrylamide and optionally comonomer is 100 parts by weight, and the amount of phase inversion agent is 2-10 parts by weight.

[0115] A fourth aspect of the present invention provides a polyacrylamide emulsion prepared by the above method.

[0116] In this invention, the polyacrylamide emulsion contains polyacrylamide, chelating agent, emulsifier, solvent and base oil.

[0117] In this invention, the polyacrylamide emulsion comprises 100 parts by weight of polyacrylamide, 0.01-1 parts by weight of chelating agent, 50-200 parts by weight of solvent, 1-20 parts by weight of emulsifier, and 50-200 parts by weight of base oil.

[0118] Further, in the polyacrylamide emulsion, the polyacrylamide is 100 parts by weight, the chelating agent is 0.05-0.5 parts by weight, the solvent is 80-150 parts by weight, the emulsifier is 5-20 parts by weight, and the base oil is 80-150 parts by weight.

[0119] In this invention, the polyacrylamide emulsion may further contain a phase-transfer agent. In the polyacrylamide emulsion, the polyacrylamide is 100 parts by weight, and the phase-transfer agent is 2-10 parts by weight.

[0120] In this invention, the polyacrylamide in the polyacrylamide emulsion has a viscosity-average molecular weight of 15 million g / mol to 22 million g / mol at 25°C.

[0121] Furthermore, the polyacrylamide in the polyacrylamide emulsion has a viscosity-average molecular weight of 16 million g / mol to 20 million g / mol at 25°C.

[0122] In this invention, the polyacrylamide emulsion, after being prepared into a 1 wt% solution with water, has a water viscosity greater than or equal to 100 mPa·s at 25℃±0.05℃.

[0123] In this invention, the method for testing the viscosity of water includes: preparing a 1 wt% high-viscosity aqueous solution with water and polyacrylamide emulsion for 10 min, and then measuring the viscosity of the high-viscosity aqueous solution (at 100 r / min, i.e., a shear rate of 170 s) using a six-speed viscometer at a temperature of 25℃ ± 0.05℃. -1 The viscosity of water is obtained by multiplying the measured value by 3.

[0124] Furthermore, after the polyacrylamide emulsion is prepared into a 1 wt% solution with water, the viscosity of the purified water at 25℃±0.05℃ is greater than or equal to 130 mPa·s.

[0125] In this invention, the apparent viscosity of the polyacrylamide emulsion prepared into a 0.5 wt% solution with 100,000 mg / L saline solution at 25℃±0.05℃ is greater than or equal to 10 mPa·s, preferably greater than or equal to 11 mPa·s.

[0126] In this invention, the brine used is a mixed aqueous solution of calcium chloride and sodium chloride.

[0127] According to the present invention, the solid content of the polyacrylamide emulsion is 25-40 wt%.

[0128] Furthermore, the solid content of the polyacrylamide emulsion is 30-40 wt%.

[0129] In this invention, the polyacrylamide in the polyacrylamide emulsion is an acrylamide homopolymer and / or an acrylamide copolymer.

[0130] In this invention, the acrylamide content in the acrylamide copolymer is 5-100 wt%, preferably 20-90 wt%.

[0131] The present invention will be described in detail below through embodiments.

[0132] In the following embodiments,

[0133] Viscosity-average molecular weight: After the polyacrylamide emulsion was precipitated in ethanol solution and dried, the molecular weight of polyacrylamide was determined by viscosity method according to the People's Republic of China National Standard GB / T 12005.10-1992.

[0134] The viscosity of a 1 wt% solution of polyacrylamide emulsion and water at 25℃±0.05℃ was measured using a six-speed viscometer after preparing a 1 wt% high-viscosity aqueous solution of water and polyacrylamide emulsion for 10 min at 25℃±0.05℃ (at a shear rate of 170 s⁻¹). -1 The viscosity of water is obtained by multiplying the measured value by 3.

[0135] The apparent viscosity (i.e., brine viscosity) of the polyacrylamide emulsion was determined at 25℃±0.05℃ after preparing a 0.5wt% polyacrylamide solution with 100,000 mg / L brine at 25℃±0.05℃. Specifically, 9.25 g of calcium chloride and 90.75 g of sodium chloride were dissolved in distilled water in a 1000 ml volumetric flask, and water was added to the mark to make up to 1000 ml, obtaining a brine with a mineralization of 100,000 mg / L. The polyacrylamide emulsion was then prepared into a 0.5wt% solution with the brine with a mineralization of 100,000 mg / L. After 2 hours, the apparent viscosity was measured using a BROOKFIELD DV-Ⅲ viscometer (rotor speed 0: 6 rpm) at 25℃±0.05℃.

[0136] Acrylamide content: When the reaction is complete, the polyacrylamide emulsion contains no acrylamide, indicating that the acrylamide has reacted completely; that is, the acrylamide content in polyacrylamide is the mass percentage of acrylamide to acrylamide and comonomer.

[0137] All raw materials are commercially available industrial products.

[0138] In the following examples and comparative examples, 1g of raw material represents 1 part by weight.

[0139] Preparation Example 1

[0140] 367g of 4,4',4”-triphenylmethane triisocyanate (in Formula II-1, a', b', and c' are all 0), 89g of dimethylethanolamine (in Formula III, R...) 10 It is ethylene; R 11 R 12100g of acetone (all methyl) and acetone were added to a dry three-necked flask equipped with a stirrer and a thermometer. The mixture was reacted at 40°C for 4 hours. After the reaction was completed, the acetone was removed by vacuum distillation. The product was washed with diethyl ether and then dried in a vacuum oven at 25°C for 12 hours to remove the diethyl ether, thus obtaining compound A-1 (in formula I, R1, R2, and R3 are all ethylenes, R4, R5, R6, R7, R8, and R9 are all methyl groups, and X has the structure shown in formula I-1; wherein a, b, and c in formula I-1 are all 0).

[0141] Preparation Example 2

[0142] 367g of 4,4',4”-triphenylmethane triisocyanate (in Formula II-1, a', b', and c' are all 0), 89g of dipropylethanolamine (in Formula III, R...) 10 It is ethylene; R 11 It is n-propyl; R 12 100g of acetone (n-propyl) and acetone were added to a dry three-necked flask equipped with a stirrer and a thermometer. The mixture was reacted at 40°C for 4 hours. After the reaction was completed, the acetone was removed by vacuum distillation. The product was washed with diethyl ether and then dried in a vacuum oven at 25°C for 12 hours to remove the diethyl ether, thus obtaining compound A-2 (in formula I, R1, R2, and R3 are all ethylene, R4, R5, R6, R7, R8, and R9 are all n-propyl, and X has the structure shown in formula I-1; wherein a, b, and c in formula I-1 are all 0).

[0143] Preparation Example 3

[0144] 367g of 4,4',4”-triphenylmethane triisocyanate (in Formula II-1, a', b', and c' are all 0), 89g of ethanolamine (in Formula III, R...) 10 It is ethylene; R 11 For H; R 12 100g of H and acetone were added to a dry three-necked flask equipped with a stirrer and a thermometer. The mixture was reacted at 40°C for 4 hours. After the reaction was completed, the acetone was removed by vacuum distillation. The product was washed with diethyl ether and then dried in a vacuum oven at 25°C for 12 hours to remove the diethyl ether, thus obtaining compound A-3 (in formula I, R1, R2, and R3 are all ethylenes, R4, R5, R6, R7, R8, and R9 are all hydrogens, and X has the structure shown in formula I-1; wherein a, b, and c in formula I-1 are all 0).

[0145] Composite initiation system B1

[0146] The complex initiation system B1 contains: compound A-1 0.01g, sodium bisulfite 0.025g, potassium persulfate 0.05g, and 2,2'-azobis(2-amidinepropane) dihydrochloride 0.05g.

[0147] Composite initiation system B2-B8

[0148] The types and amounts of each component in the composite initiation system B2-B8 are shown in Table 1.

[0149] Composite initiation system DB1

[0150] The types and amounts of each component in the composite initiation system DB1 are shown in Table 1.

[0151] DB2 composite initiation system

[0152] Replace compound A-1 in composite initiation system B1 with A-3, and select and use the same amount of the remaining components as in composite initiation system B1.

[0153] Table 1

[0154]

[0155] Continued from Table 1

[0156]

[0157]

[0158] Example 1

[0159] Polyacrylamide emulsion was prepared using a composite initiation system B1;

[0160] (1) Mix 86g of No. 3 white oil, 10g of Span 80 and 4g of Tween 80 (Span 80 has an HLB value of 4.3, Tween 80 has an HLB value of 15.0, and the HLB value of the two emulsifiers after mixing is 7.36), stir and dissolve to obtain an oil phase solution; dissolve 80g of acrylamide and 20g of sodium 2-acrylamide-2-methylpropanesulfonate in 100g of water to obtain a mixture, then add 0.2g of disodium ethylenediaminetetraacetate to the mixture, stir evenly and adjust the pH of the mixture to 6.8 with NaOH to obtain an aqueous phase solution;

[0161] (2) Mix the aqueous solution and the oil solution and emulsify them for 30 minutes under stirring at 10000 r / min to obtain a mixture emulsion.

[0162] (3) Prepare 5wt% solutions of sodium bisulfite, potassium persulfate and 2,2'-azobis(2-amidinepropane) dihydrochloride with water respectively.

[0163] (4) Purge with nitrogen for 30 minutes to maintain the temperature of the mixture solution at 5°C. Slowly add 0.01g of compound A and sodium bisulfite aqueous solution to the mixture emulsion, followed by dropwise addition of potassium persulfate aqueous solution over 4 hours. During the dropwise addition, maintain the maximum emulsion polymerization temperature at 35°C. After the dropwise addition is complete, raise the temperature to 45°C and dropwise add 2,2'-azobis(2-amidinylpropane) dihydrochloride aqueous solution over 2 hours. Maintain the temperature at 45°C and react for 1 hour. Cool the temperature to 30°C and add 4g of nonylphenol polyoxyethylene ether as a phase inversion agent. Stir until homogeneous to obtain a polyacrylamide emulsion. The solid content and test results of the polyacrylamide emulsion are shown in Table 2.

[0164] Examples 2-8

[0165] Polyacrylamide emulsions were prepared using the composite initiation systems B2-B8 according to the preparation method in Example 1. The solid content and test results of the polyacrylamide emulsions are shown in Table 2.

[0166] Example 9

[0167] Polyacrylamide emulsion was prepared according to the method of Example 1, except that in step (1), 80g of No. 3 white oil, 12g of Span 80 and 2g of Tween 80 were mixed and stirred to dissolve to obtain an oil phase solution; 85g of acrylamide and 15g of sodium 2-acrylamide-2-methylpropanesulfonate were dissolved in 100g of water to obtain a mixture, and then 0.3g of disodium ethylenediaminetetraacetate was added to the mixture.

[0168] Example 10

[0169] Polyacrylamide emulsions were prepared according to the method in Example 1, except that in step (4), compound A, sodium bisulfite aqueous solution, and potassium persulfate aqueous solution were slowly added to the mixed emulsion over 4 hours, and the maximum polymerization temperature of the emulsion was controlled at 35°C during the addition process. The solid content and test results of the prepared polyacrylamide emulsions are shown in Table 2.

[0170] Example 11

[0171] Polyacrylamide emulsions were prepared according to the method in Example 1, except that in steps (1) and (2), 86g of No. 3 white oil, 10g of Span 80, 4g of Tween 80, 80g of acrylamide, 20g of sodium 2-acrylamide-2-methylpropanesulfonate, and 0.2g of disodium ethylenediaminetetraacetate were mixed with 100g of water and stirred at 10000r / min for 30min to obtain a mixture emulsion. The solid content and test results of the prepared polyacrylamide emulsions are shown in Table 2.

[0172] Comparative Example 1

[0173] Polyacrylamide emulsions were prepared using the composite initiation system DB1 according to the preparation method in Example 1. The solid content and test results of the polyacrylamide emulsions are shown in Table 2.

[0174] Comparative Example 2

[0175] Commercially available polyacrylamide emulsion, brand name BM300, from Shandong Baomo Biochemical Co., Ltd., was used. The solid content of the commercially available polyacrylamide emulsion was 32%. The test results are shown in Table 2.

[0176] Comparative Example 3

[0177] Polyacrylamide emulsions were prepared using the composite initiation system DB2 according to the preparation method in Example 1. The solid content and test results of the polyacrylamide emulsions are shown in Table 2.

[0178] Table 2

[0179]

[0180] Continued from Table 2

[0181]

[0182]

[0183] As can be seen from Table 2, when the types and amounts of acrylamide and comonomer are the same, the polyacrylamide emulsion prepared by the composite initiation system provided by this invention has a higher molecular weight. Furthermore, when the polyacrylamide emulsion is mixed with water to form a 1 wt% solution, its viscosity in pure water is greater than or equal to 100 mPa·s; when the polyacrylamide emulsion is mixed with 100,000 mineralized salt to form a 0.5 wt% solution, its apparent viscosity is greater than or equal to 10 mPa·s. This indicates that the polyacrylamide emulsion of this application can obtain a high viscosity at a lower polymer emulsion concentration, while also having better salt resistance and good thickening properties in high-mineralized water.

[0184] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A composite initiation system, characterized in that, The composite initiation system comprises compound A, a redox initiator, and a first initiator; the first initiator is selected from azo initiators and / or peroxide initiators. Wherein, compound A is at least one of the compounds shown in Formula I; In Formula I, R1, R2, and R3 are each independently a C1-C5 straight-chain alkylene group and a C3-C5 branched alkylene group; R4, R5, R6, R7, R8, and R9 are each independently a C1-C3 alkyl group. In Equation I, X has the structure shown in Equation I-1; In Equation I-1, a, b, and c are each an independent integer between 0 and 3.

2. The composite initiation system according to claim 1, wherein, In Formula I, R1, R2, and R3 are each independently a C1-C3 straight-chain alkylene group; R4, R5, R6, R7, R8, and R9 are each independently a methyl or ethyl group. Preferably, in Equation I-1, a, b, and c are each independently 0 or 1; Preferably, the redox initiator includes an oxidant and a reducing agent; Preferably, in the composite initiation system, compound A is 0.001-0.1 parts by weight, preferably 0.005-0.05 parts by weight; the reducing agent is 0.001-0.5 parts by weight, preferably 0.01-0.2 parts by weight; the oxidizing agent is 0.001-0.5 parts by weight, preferably 0.01-0.2 parts by weight; and the first initiator is 0.001-0.5 parts by weight, preferably 0.01-0.2 parts by weight.

3. The composite initiation system according to claim 2, wherein, The reducing agent is a sulfite and / or a thiosulfate; Preferably, the reducing agent is selected from at least one of sodium bisulfite, sodium sulfite, sodium metabisulfite, sodium dithionite, and sodium thiosulfate; Preferably, the oxidant is selected from persulfate and / or hydrogen peroxide; Preferably, the persulfate is selected from at least one of ammonium persulfate, potassium persulfate, and sodium persulfate.

4. The composite initiation system according to any one of claims 1-3, wherein, The preparation method of compound A includes: in the presence of a solvent, raw material 1 and raw material 2 undergo a first reaction to obtain compound A; Wherein, raw material 1 is a compound represented by formula II, and raw material 2 is a compound represented by formula III; Wherein, X' has the structure shown in Equation II-1; In Equation II-1, a', b', and c' are each an independent integer from 0 to 3, preferably 0 or 1; In Equation III, R 10 It is a C1-C5 straight-chain alkylene or a C3-C5 branched alkylene; R 11 R 12 Each is an alkyl group that is independently C1-C3; Preferably, in formula III, R 10 It is a C1-C3 straight-chain alkylene group; R 11 R 12 Each can be methyl or ethyl independently.

5. The composite initiation system according to claim 4, wherein, The molar ratio of raw material 1 to raw material 2 is 0.5-2:1, preferably 0.8-1.2:1; Preferably, the solvent is selected from at least one of acetone, butanone, benzene, toluene, and xylene; Preferably, the temperature of the first reaction is 30-100℃, more preferably 35-60℃; the time of the first reaction is 1-10h, more preferably 3.5-5h. Preferably, the product of the first reaction is post-processed to obtain compound A.

6. The application of the composite initiation system according to any one of claims 1-5 in the preparation of polyacrylamide emulsions.

7. A method for preparing a polyacrylamide emulsion, characterized in that, The method includes: (1) Acrylamide, optionally comonomer, chelating agent, emulsifier, base oil and solvent are mixed to obtain a mixture emulsion; (2) The emulsion mixture is mixed with compound A and a redox initiator to carry out a second reaction; (3) Add an azo initiator and / or a peroxide initiator to the product of step (2) to carry out a third reaction to obtain a polyacrylamide emulsion; The compound A is at least one of the compounds shown in Formula I; In Formula I, R1, R2, and R3 are each independently a C1-C5 straight-chain alkylene group and a C3-C5 branched alkylene group; R4, R5, R6, R7, R8, and R9 are each independently a C1-C3 alkyl group. In Equation I, X has the structure shown in Equation I-1; In Equation I-1, a, b, and c are each an independent integer between 0 and 3.

8. The method according to claim 7, wherein, In step (1), the comonomer is selected from at least one of acrylic acid, 2-acrylamido-2-methylpropanesulfonic acid, N,N-dimethylacrylamide, N,N-diethylacrylamide, vinylpyrrolidone, diallyl dimethylammonium chloride, methacryloyloxyethyltrimethylammonium chloride, sodium styrene sulfonate, sodium ethylene sulfonate, sodium methyl ethylene sulfonate, sodium 2-acrylamido-dodecane sulfonate, sodium 2-acrylamido-tetradecane sulfonate, sodium 2-acrylamido-hexadecane sulfonate, dodecyl dimethyl allyl ammonium chloride, tetradecyl dimethyl allyl ammonium chloride, hexadecyl dimethyl allyl ammonium chloride, and octadecyl dimethyl allyl ammonium chloride; Preferably, the chelating agent is selected from at least one of ethylenediaminetetraacetic acid tetrasodium, ethylenediaminetetraacetic acid disodium, sodium tripolyphosphate, and sodium citrate; Preferably, the emulsifier is a Span series emulsifier and / or a Tween series emulsifier; Preferably, the HLB value of the emulsifier is 4-8; Preferably, the base oil is selected from at least one of white oil, liquid paraffin, cyclohexane, kerosene isooctane, isoparaffin oil, and coconut oil.

9. The method according to claim 7 or 8, wherein, Step (1) includes: mixing acrylamide, optionally comonomer, chelating agent and solvent evenly, adjusting pH to 6-8 to obtain an aqueous solution; mixing emulsifier and base oil evenly to obtain an oil solution; stirring the aqueous solution and oil solution to obtain a mixed solution; Preferably, the stirring time is 30-60 minutes and the stirring temperature is 5-25°C.

10. The method according to any one of claims 7-9, wherein, In step (1), the total amount of acrylamide and optionally comonomer is used as a basis, wherein the acrylamide is 5-100 wt%, preferably 20-90 wt%; and the comonomer is 0-95 wt%, preferably 10-80 wt%. Preferably, in step (1), the total amount of acrylamide and optionally comonomer is 100 parts by weight, the amount of chelating agent is 0.01-1 parts by weight, preferably 0.05-0.5 parts by weight, the amount of solvent is 50-200 parts by weight, preferably 80-150 parts by weight, the amount of emulsifier is 1-20 parts by weight, preferably 5-20 parts by weight, and the amount of base oil is 50-200 parts by weight, preferably 80-150 parts by weight.

11. The method according to any one of claims 7-10, wherein, In step (2), the redox initiator includes an oxidant and a reducing agent; Preferably, the total amount of acrylamide and optionally comonomer is 100 parts by weight; the amount of compound A is 0.001-0.1 parts by weight, preferably 0.005-0.05 parts by weight; the amount of reducing agent is 0.001-0.5 parts by weight, preferably 0.01-0.2 parts by weight; the amount of peroxidizer is 0.001-0.5 parts by weight, preferably 0.01-0.2 parts by weight; and the total amount of azo initiator and / or peroxide initiator is 0.001-0.5 parts by weight, preferably 0.01-0.2 parts by weight. Preferably, in step (2), the temperature of the second reaction is less than or equal to 40°C, and more preferably 5-35°C; Preferably, step (2) includes: adding compound A and a reducing agent to the emulsion mixture, and then adding an oxidizing agent for mixing.

12. The method according to any one of claims 7-11, wherein, In step (3), the temperature of the third reaction is 40-80℃, preferably 40-60℃; the reaction time is 0.5-6h, preferably 1-4h. Preferably, a phase-inverting agent is added to the product after the third reaction.

13. A polyacrylamide emulsion prepared by the method according to any one of claims 7-12.

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