Inverse emulsion polymerization method, emulsion polymer and application

Abstract

The invention relates to the field of polymer synthesis, and discloses an inverse emulsion polymerization method, an emulsion polymer and application. The invention relates to an inverse emulsion polymerization method, which comprises the following steps: (1) mixing a water solution containing a water-soluble monomer, a nonionic emulsifier and an oil phase to obtain a water-in-oil mixture, the nonionic emulsifier having an HLB value of 2-8; and (2) in the presence of an organic reducing agent, the water-in-oil type mixture is subjected to an inverse emulsion polymerization reaction under the ultrasonic irradiation condition, and an initiator is not used in the inverse emulsion polymerization reaction. According to the method, inverse emulsion polymerization can be realized in the presence of ultrasonic irradiation and an organic reducing agent, an initiator does not need to be used, the residue of the initiator is avoided, the monomer conversion rate is improved, and the obtained emulsion polymer is relatively high in molecular weight and good in stability.

Description

Technical Field

[0001] The present invention relates to the field of polymer synthesis, and in particular to an inverse emulsion polymerization method, an emulsion polymer and applications. Background Art

[0002] Emulsion polymerization, one of the primary technologies for preparing polymer materials, offers advantages such as high efficiency, rapidity, and precise control. Inverse emulsion polymerization uses an aqueous monomer solution as the dispersed phase. Using surfactants, mechanical agitation, ultrasound, and other physical methods, it forms micro-units within a continuous phase, such as an oil phase, and uses these micro-units as reaction sites. Inverse emulsion polymerization can be used to produce synthetic rubber, synthetic plastics, and synthetic resin coatings. In oilfield chemistry, inverse emulsion polymers are used as chemical agents for drilling fluid filtration reduction, water plugging, and profile control, as well as fluid fracturing.

[0003] Inverse emulsion polymerization typically uses water-soluble initiators such as persulfates (e.g., ammonium persulfate, potassium persulfate, sodium persulfate), hydrogen peroxide, and azo hydrochlorides (e.g., V044, V050), as well as oil-soluble initiators such as azo compounds (e.g., AIBN) and organic peroxides (e.g., BPO). Chemical initiators have a short half-life, making it difficult to maintain a stable polymerization rate. Furthermore, residual initiator is difficult to remove, potentially causing side reactions in the product and even gelling, which can affect product stability.

[0004] Ultrasonic emulsion polymerization generates tiny bubble nuclei within the liquid through the acoustic cavitation effect. When the cavitation bubbles collapse, they generate high temperatures and pressures exceeding 5000K and 108 Pa, initiating chemical reactions that would be impossible under normal conditions. Stoffer et al. prepared polymethyl methacrylate (PMMA) by ultrasonic emulsion polymerization using sodium dodecyl sulfate (SDS) as an emulsifier and no other chemical initiators. Through free radical capture experiments, they demonstrated that free radicals generated by the decomposition of the ionic emulsifier SDS under ultrasonic irradiation can effectively initiate monomer polymerization. He Yuhui studied the emulsion polymerization of styrene and butyl acrylate under ultrasonic irradiation and found that even the presence of free radicals generated by the monomers and water was ineffective in initiating the reaction, resulting in very low monomer conversion. Polymerization could not be initiated using nonionic surfactants, while both anionic and cationic surfactants successfully initiated polymerization, achieving high monomer conversion. Zhang Jingzhi also observed similar patterns in ultrasonic styrene emulsion copolymerization. Li Xiaorui et al. used acrylamide, 2-acrylamido-2-methylpropanesulfonic acid and octadecyl acrylate as raw materials, added a certain amount of initiator, and used ultrasound as an auxiliary emulsification and auxiliary initiation method to prepare hydrophobic associating polyacrylamide through solution polymerization.

[0005] The aforementioned emulsion polymerization systems all utilize oil-soluble monomers and require the use of ionic emulsifiers, placing significant limitations on both the synthetic polymer and the emulsion system. Research on inverse emulsion polymerization using ultrasonic irradiation with water-soluble monomers is in its infancy, and initiator-free systems remain largely undeveloped. Summary of the Invention

[0006] The purpose of the present invention is to overcome the problems in the prior art that the inverse emulsion polymerization method needs to be carried out in the presence of an ionic emulsifier and an initiator, resulting in initiator residue, instability of the emulsion polymer and low monomer conversion rate. The present invention provides an inverse emulsion polymerization method, an emulsion polymer and applications. The method can realize inverse emulsion polymerization in the presence of ultrasonic irradiation and an organic reducing agent, does not require the use of an initiator during the preparation process, avoids initiator residue, improves the monomer conversion rate, and obtains an emulsion polymer with a high molecular weight and good stability.

[0007] In order to achieve the above object, the first aspect of the present invention provides an inverse emulsion polymerization method, wherein the method comprises the following steps:

[0008] (1) mixing an aqueous solution containing a water-soluble monomer, a nonionic emulsifier, and an oil phase to obtain a water-in-oil mixture, wherein the nonionic emulsifier has an HLB value of 2-8;

[0009] (2) In the presence of an organic reducing agent, the water-in-oil mixture is subjected to an inverse emulsion polymerization reaction under ultrasonic irradiation conditions, and the inverse emulsion polymerization reaction does not use an initiator.

[0010] The second aspect of the present invention provides an emulsion polymer prepared by the inverse emulsion polymerization method described in the first aspect.

[0011] The third aspect of the present invention provides a use of the emulsion polymer described in the second aspect in oilfield chemicals and / or paint products.

[0012] The method provided by the present invention can prepare an emulsion polymer with good stability by ultrasonically irradiating a water-in-oil mixture using a non-ionic emulsifier in the presence of ultrasonic irradiation and an organic reducing agent. Furthermore, the method does not use an initiator, thereby avoiding the adverse effects of multiple factors such as pH value and complex emulsion system components on the initiation system screening efficiency, greatly simplifying function-oriented polymer design, and at the same time avoiding gel instability caused by initiator residue, thereby improving the monomer conversion rate and obtaining an ultra-stable emulsion polymer.

[0013] The method provided by the present invention selects an organic reducing agent and utilizes the mild reducing property of the organic reducing agent to improve the monomer conversion rate of the inverse emulsion polymerization reaction.

[0014] The emulsion polymer provided by the invention has good stability. DETAILED DESCRIPTION

[0015] The endpoints of the ranges and any values ​​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 endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

[0016] A first aspect of the present invention provides an inverse emulsion polymerization method, wherein the method comprises the following steps:

[0017] (1) mixing an aqueous solution containing a water-soluble monomer, a nonionic emulsifier, and an oil phase to obtain a water-in-oil mixture, wherein the HLB value of the nonionic emulsifier is 2-8, for example, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, and values ​​between any two groups;

[0018] (2) In the presence of an organic reducing agent, the water-in-oil mixture is subjected to an inverse emulsion polymerization reaction under ultrasonic irradiation conditions, and the inverse emulsion polymerization reaction does not use an initiator.

[0019] The method provided by the present invention can prepare an emulsion polymer with good stability by ultrasonically irradiating a water-in-oil mixture using a non-ionic emulsifier in the presence of ultrasonic irradiation and an organic reducing agent. Furthermore, the method does not use an initiator, thereby avoiding the adverse effects of multiple factors such as pH value and complex emulsion system components on the initiation system screening efficiency, greatly simplifying the function-oriented monomer component design, and avoiding gel instability caused by initiator residue, thereby improving the monomer conversion rate and obtaining an ultra-stable emulsion polymer.

[0020] The method provided by the present invention selects an organic reducing agent and utilizes the mild reducing property of the organic reducing agent to improve the monomer conversion rate of the inverse emulsion polymerization reaction.

[0021] In the present invention, the HLB value of the nonionic emulsifier is calculated by weighting the mass fraction of each emulsifier component in the total amount of emulsifier used. It should be noted that when the reaction system contains only one water-soluble monomer, the HLB value is the HLB value of the water-soluble monomer; when the reaction system contains two or more water-soluble monomers, the HLB value is calculated according to the above method. For example, when two nonionic emulsifiers are selected, the HLB value of the nonionic emulsifier is calculated as follows: HLB value = x*A+(1-x)*B, where A and B are the HLB values ​​of the two nonionic emulsifiers, respectively, and x and 1-x are the mass fractions of the two nonionic emulsifiers, respectively.

[0022] In the present invention, there is no particular limitation on the order of mixing the components in step (1). According to a preferred embodiment of the present invention, step (1) comprises:

[0023] dissolving a water-soluble monomer in water to obtain an aqueous solution containing the water-soluble monomer;

[0024] Mixing a nonionic emulsifier and an oil phase to obtain a mixture I containing a nonionic emulsifier and an oil phase, wherein the HLB value of the nonionic emulsifier is 2-8;

[0025] The aqueous solution containing the water-soluble monomer is added dropwise to the mixture I containing the nonionic emulsifier and the oil phase to obtain a water-in-oil mixture. In the present invention, there is no particular limitation on the rate of addition. Preferably, the rate of addition is 1-10 drops / s.

[0026] Compared with the prior art method of mixing water-soluble monomers, nonionic emulsifiers, water and oil phases together, the method provided by the present invention has the advantage of adopting this mixing order to make the dispersed phase particle size more uniform, avoid premature Ostwald ripening effect, and maintain system stability.

[0027] In the present invention, there is no particular limitation on the specific operation mode of mixing in each step of step (1). Preferably, the mixing in step (1) is independently carried out under stirring conditions, and preferably the stirring conditions include: a stirring rate of 200-1200 rad / min and a temperature of room temperature. In the present invention, the room temperature refers to 25±5°C. In the present invention, the stirring rates in each mixing process of step (1) can be the same or different, preferably the same, and those skilled in the art can adjust according to actual needs.

[0028] In the present invention, an aqueous solution containing a water-soluble monomer is used as the dispersed phase, and an oil phase is used as the continuous phase to synthesize an emulsion polymer by inverse emulsion polymerization. The source of the aqueous solution containing the water-soluble monomer is not particularly limited in the present invention, as long as an aqueous solution containing the water-soluble monomer can be obtained. Preferably, in step (1), the aqueous solution containing the water-soluble monomer is prepared by dissolving the water-soluble monomer in water.

[0029] In the present invention, different water-soluble monomers have different solubilities. The present invention does not particularly limit the amounts of water-soluble monomers and water. Those skilled in the art can make adaptive adjustments according to actual needs. Preferably, the mass ratio of the water-soluble monomer to water is 0.001-2:1.

[0030] In the present invention, there is no particular limitation on the type of water-soluble monomer. Any water-soluble monomer conventionally defined in the art as suitable for inverse emulsion polymerization is applicable to the present invention. Preferably, the water-soluble monomer is selected from at least one of a nonionic monomer, an anionic monomer, and a cationic monomer, and more preferably a nonionic monomer and / or an anionic monomer.

[0031] In the present invention, there is no particular limitation on the type of water-soluble nonionic monomer. Any water-soluble nonionic monomer conventionally defined in the art as suitable for inverse emulsion polymerization is applicable to the present invention. Preferably, the nonionic monomer is selected from at least one of acrylamide, methacrylamide, N-isopropylacrylamide, N-hydroxyethylacrylamide, N,N-dimethylacrylamide, N,N-diethylacrylamide, and N-vinyl-2-pyrrolidone.

[0032] In the present invention, there is no particular limitation on the type of water-soluble anionic monomer. Any water-soluble anionic monomer conventionally defined in the art as suitable for inverse emulsion polymerization is applicable to the present invention. Preferably, the anionic monomer is selected from at least one of acrylic acid, sodium acrylate, itaconic acid, methacrylic acid, 2-acrylamido-2-methylpropanesulfonic acid, 2-acryloyloxy-2-methylpropanesulfonic acid, sodium methacrylic acid, and sodium p-styrenesulfonate.

[0033] In the present invention, there is no particular limitation on the type of water-soluble cationic monomer. Any water-soluble cationic monomer conventionally defined in the art as suitable for inverse emulsion polymerization is applicable to the present invention. Preferably, the cationic monomer is selected from at least one of dimethyldiallylammonium chloride, acryloyloxyethyltrimethylammonium chloride, and methacryloyloxyethyltrimethylammonium chloride.

[0034] According to a preferred embodiment of the present invention, the water-soluble monomer is selected from at least one of acrylamide, N-isopropylacrylamide, N-hydroxyethylacrylamide, N,N-dimethylacrylamide, acrylic acid, sodium acrylate, itaconic acid, 2-acrylamido-2-methylpropanesulfonic acid, and sodium methacrylic acid. This preferred embodiment has the advantages of high conversion rate, readily available monomers, and suitability for industrial production.

[0035] In the present invention, the inverse emulsion polymerization system is a water-in-oil reaction system, and the inverse emulsion polymerization of the water-soluble monomer is achieved by controlling the amount of the water-soluble monomer and the oil phase. Preferably, the mass ratio of the water-soluble monomer to the oil phase is 0.05-1.5:1, more preferably 0.1-1.5:1, for example, it can be 0.1:1, 0.2:1, 0.3:1, 0.4:1, 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1, 1:1, 1.1:1.2, 1.3:1, 1.4:1, 1.5:1, and values ​​between any two groups.

[0036] In the present invention, preferably, the mass ratio of the water phase to the oil phase is 0.5-2:1, more preferably 0.5-1.5:1.

[0037] In the present invention, the inverse emulsion polymerization reaction is controlled by controlling the pH value of the aqueous solution containing the water-soluble monomer. Preferably, step (1) further comprises optionally introducing an acid-base regulator into the aqueous solution containing the water-soluble monomer.

[0038] In the present invention, there is no particular limitation on the type of acid-base regulator, as long as it meets the pH value requirement, and those skilled in the art can select it according to actual needs. Preferably, the acid-base regulator is a basic compound and / or an acidic compound.

[0039] In the present invention, there is no particular limitation on the type of the alkaline compound. Preferably, the alkaline compound is at least one selected from sodium hydroxide, potassium hydroxide, ammonia water, sodium carbonate, sodium bicarbonate and potassium carbonate.

[0040] In the present invention, there is no particular limitation on the type of the acidic compound. Preferably, the acidic compound is at least one selected from hydrochloric acid, sulfuric acid, and phosphoric acid.

[0041] In the present invention, there is no particular limitation on the amount of the acid-base regulator, as long as it can meet the pH requirement. Preferably, the amount of the acid-base regulator is such that the pH value of the aqueous solution containing the water-soluble monomer is 4-10.

[0042] In the present invention, there is no particular limitation on the type of nonionic emulsifier, and all nonionic emulsifiers conventionally defined in the art are applicable to the present invention. Preferably, in step (1), the nonionic emulsifier is a lipophilic emulsifier and optionally a hydrophilic emulsifier, more preferably a lipophilic emulsifier and a hydrophilic emulsifier.

[0043] In the present invention, there is no particular limitation on the type of lipophilic emulsifier, and any nonionic emulsifier conventionally defined in the art is applicable to the present invention. Preferably, the lipophilic emulsifier is selected from the Span series emulsifiers and / or amphiphilic block copolymer emulsifiers, such as Span 40, Span 60, Span 80, Span 83, and Span 85.

[0044] In the present invention, there is no particular limitation on the type of hydrophilic emulsifier, and any nonionic emulsifier conventionally defined in the art is applicable to the present invention. Preferably, the hydrophilic emulsifier is a Tween series emulsifier and / or an OP series emulsifier. For example, the Tween series emulsifier may be Tween 40, Tween 60, or Tween 80, and the OP series emulsifier may be OP-4, OP-5, OP-6, OP-7, OP-8, OP-10, or OP-15.

[0045] In the present invention, there is no particular limitation on the amount of the nonionic emulsifier used. Preferably, the mass ratio of the nonionic emulsifier to the oil phase is 0.01-0.5:1, more preferably 0.1-0.4:1.

[0046] In the present invention, there is no particular limitation on the amount of the lipophilic emulsifier and the hydrophilic emulsifier, as long as the HLB value of the nonionic emulsifier is within the aforementioned range. Preferably, the mass ratio of the lipophilic emulsifier to the hydrophilic emulsifier is 1:0-0.35.

[0047] In the present invention, the oil phase serves as the continuous phase in the inverse emulsion polymerization system, and the type of the oil phase is not particularly limited. Preferably, in step (1), the oil phase is selected from at least one of alkanes, liquid paraffin, α-olefin synthetic base oils, mineral oils, aromatic hydrocarbons, and linear polysiloxanes, and more preferably liquid paraffin and / or mineral oil. The advantages of using an oil phase within the above preferred range as the oil continuous phase are that it is conducive to improving the dispersibility of the monomers, is easy to obtain, and is suitable for industrial production.

[0048] In the present invention, there is no particular limitation on the specific type of alkane. Preferably, the alkane is selected from C5-C14 alkanes, and more preferably is selected from at least one of pentane, hexane, cyclohexane and heptane.

[0049] In the present invention, there is no particular limitation on the specific type of α-olefin synthetic base oil. Preferably, the α-olefin synthetic base oil is a C6-C24 α-olefin synthetic base oil, more preferably a C12-C18 α-olefin synthetic base oil.

[0050] In the present invention, there is no particular limitation on the specific type of mineral oil. For example, the mineral oil may be at least one of No. 3 mineral white oil, No. 5 mineral white oil, No. 7 mineral white oil, No. 10 mineral white oil, No. 15 mineral white oil, No. 26 mineral white oil, and No. 32 mineral white oil.

[0051] In the present invention, there is no particular limitation on the specific type of aromatic hydrocarbons. Preferably, the aromatic hydrocarbons are selected from C5-C10 aromatic hydrocarbons, more preferably toluene and / or xylene.

[0052] In the present invention, there is no particular limitation on the specific type of linear polysiloxane. Preferably, the linear polysiloxane is methyl silicone oil and / or dimethyl silicone oil.

[0053] In the present invention, an organic reducing agent is used to cooperate with other components in the inverse emulsion polymerization system to achieve polymerization of the water-in-oil inverse emulsion polymerization system. Preferably, in step (2), the organic reducing agent is selected from at least one of ascorbic acid, sodium ascorbate, ethylenediamine, ethylenediaminetetraacetic acid, disodium ethylenediaminetetraacetate, N,N,N',N'-tetramethylethylenediamine, N,N,N',N'-tetraethylethylenediamine, N,N,N',N'-tetraacetylethylenediamine, formaldehyde, acetaldehyde, thiourea and calcium hydroxybenzenesulfonate, preferably at least one of ascorbic acid, sodium ascorbate, N,N,N',N'-tetramethylethylenediamine, N,N,N',N'-tetraethylethylenediamine, ethylenediaminetetraacetic acid and disodium ethylenediaminetetraacetate. The advantages of using this preferred embodiment are good water solubility, strong reducibility, simplicity and ease of acquisition, and suitability for industrial production.

[0054] In the present invention, preferably, the organic reducing agent is provided by an aqueous solution containing the organic reducing agent, and preferably the mass concentration of the aqueous solution containing the organic reducing agent is 0.5-40%.

[0055] In the present invention, there is no particular limitation on the amount of the organic reducing agent used. Preferably, in step (2), the mass ratio of the organic reducing agent to the oil phase is 0.0005-0.01:1, more preferably 0.0005-0.001:1, for example, 0.0006:1, 0.0007:1, 0.0008:1, 0.0009:1, 0.001:1, and any value between two groups. It should be noted that the mass of the organic reducing agent herein refers to the mass of the organic reducing agent in the aqueous solution containing the organic reducing agent.

[0056] In the present invention, preferably, the method further comprises: introducing an inert gas in step (2) and performing the emulsion inverse emulsion polymerization reaction in the presence of the inert gas.

[0057] In the present invention, there is no particular limitation on the type of inert gas. Preferably, in step (2), the inert gas is selected from at least one of nitrogen, argon, helium and neon.

[0058] In the present invention, there is no particular limitation on the rate of introduction of the inert gas, and those skilled in the art can adjust it according to actual needs.

[0059] In the present invention, inverse emulsion polymerization is achieved by ultrasonic irradiation of an oil-in-water polymerization system. The present invention does not particularly limit the conditions of ultrasonic irradiation. Preferably, in step (2), the conditions of ultrasonic irradiation include: an ultrasonic frequency of 35-105kHz, an ultrasonic power of 50-500W, a reaction temperature of 20-80°C, and a reaction time of 0.5-6h; further preferably, in step (2), the conditions of ultrasonic irradiation include: an ultrasonic frequency of 35-70kHz, an ultrasonic power of 60-200W, a reaction temperature of 40-65°C, and a reaction time of 3-5h. The advantage of adopting this preferred embodiment is that a higher monomer conversion rate can be obtained in the initiator-free inverse emulsion polymerization system provided by the present invention.

[0060] According to a specific embodiment of the present invention, the inverse emulsion polymerization method comprises the following steps:

[0061] (1) dissolving a water-soluble monomer in water to obtain an aqueous solution containing the water-soluble monomer, and then optionally introducing an acid-base regulator into the aqueous solution containing the water-soluble monomer to adjust the pH to 4-10;

[0062] Mixing a nonionic emulsifier and an oil phase to obtain a mixture I containing a nonionic emulsifier and an oil phase, wherein the nonionic emulsifier has an HLB value of 2-8;

[0063] The aqueous solution containing the water-soluble monomer is added dropwise to the mixture I containing the nonionic emulsifier and the oil phase at a rate of 1-10 drops / s under stirring at a speed of 200-1200 rad / min and room temperature to obtain a water-in-oil mixture;

[0064] (2) introducing an inert gas into the water-in-oil mixture of step (1), maintaining the inert gas atmosphere and heating to the ultrasonic irradiation reaction temperature, then adding an organic reducing agent to carry out an inverse emulsion polymerization reaction under ultrasonic irradiation conditions, wherein the inverse emulsion polymerization reaction does not use an initiator, and the ultrasonic irradiation conditions include: an ultrasonic frequency of 35-70 kHz, an ultrasonic power of 60-200 W, a reaction temperature of 40-65° C., and a reaction time of 3-5 h.

[0065] The second aspect of the present invention provides an emulsion polymer prepared by the reactive emulsion polymerization method described in the first aspect.

[0066] The third aspect of the present invention provides a use of the emulsion polymer described in the second aspect in oilfield chemicals and / or paint products.

[0067] The present invention will be described in detail below through examples. In the following examples, all products are commercially available unless otherwise specified.

[0068] All raw materials used in the examples were purchased from MacLean reagent and were of analytical grade.

[0069] The HLB value of span80 is 4.3, and the HLB value of Tween60 is 14.9.

[0070] The HLB value of Tween80 is 15.0, and the HLB value of span60 is 4.7.

[0071] The HLB value of OP-10 is 14.5, and the HLB value of span85 is 1.8.

[0072] The HLB value of Tween40 is 15.6, and the HLB value of span40 is 6.7.

[0073] The HLB value of OP-4 is 8.3, and the HLB value of span83 is 3.7.

[0074] The HLB value of OP-15 is 15, and the HLB value of OP-7 is 12.

[0075] In the present invention, the conversion rate of the monomer is obtained by the following method: the total mass fraction of all added water-soluble monomers in the reaction system is recorded as Z. Two drops of hydroquinone (inhibitor) are first added to ethanol, and then the mass of the emulsion polymer product is recorded as m0. After magnetic stirring for 6 hours, it is allowed to settle for 24 hours. The filter paper is dried in an oven at 105°C to constant weight, and the mass of the precipitate is recorded as m1. After the precipitate is filtered with filter paper, it is washed three times with a mixed solvent prepared by ethanol and acetone in a mass ratio of 1:1, and vacuum dried at 60°C to constant weight, and the mass is recorded as m2. The conversion rate Y is calculated according to the following formula:

[0076] Conversion rate Y = (m2-m1) / (m0×Z)×100%.

[0077] In the present invention, the apparent viscosity is obtained by the following method: the dried precipitate is crushed to a fineness of 100 mesh or finer, and according to the practice of the petroleum industry, a 1% mass concentration solution is prepared with deionized water, and the solution is stirred for 4 hours until uniform. The reading R at 600 r / min is measured using a 35SA six-speed viscometer from Fann Company, USA, according to the method of GB / T 16783.1-2014. The apparent viscosity AV (unit: mPa·s) is calculated according to the following formula:

[0078] Apparent viscosity AV = 1 / 2 × R.

[0079] In the present invention, the stability of the emulsion polymer is measured by visually observing the emulsion polymer after it has been allowed to stand.

[0080] Example 1

[0081] In a four-necked flask, 100.0 g of No. 3 mineral white oil (Jingmen Petrochemical), 27.0 g of span80, and 5.0 g of Tween60 (HLB value of 6.0) were added and stirred evenly to form the oil phase. 100.0 g of acrylamide was weighed and dissolved in 100.0 g of deionized water with an initial pH of about 7. Under a mechanical stirring speed of 650 rad / min, the oil phase was added dropwise at a rate of 1-2 drops / s using a dropping funnel at room temperature. After the addition was complete, high-purity nitrogen was introduced for 20 minutes and the nitrogen atmosphere was maintained. The system was heated to 50°C and refluxed under condensation. 8.0 g of ascorbic acid aqueous solution (solution mass concentration of 1.0%) was added. After stirring for 2 minutes, the mixture was irradiated using an ultrasonic cleaner with a frequency of 35 kHz and a power of 150 W, and the reaction was maintained at 50°C for 5.0 hours.

[0082] Example 2

[0083] To a four-necked flask, add 100.0g of No. 5 mineral white oil (Jingmen Petrochemical), 20.0g of Span 80, and 5.0g of Tween 80 (HLB value of 6.4) and stir thoroughly to form the oil phase. Weigh 2.0g of N,N-dimethylacrylamide and 18.0g of acrylic acid and dissolve them in 50.0g of deionized water. Adjust the pH to 6 with sodium hydroxide. Add the oil phase dropwise at a rate of 1-2 drops / s using a dropping funnel with mechanical stirring at 450 rad / min at room temperature. After the addition is complete, introduce high-purity nitrogen for 20 minutes and maintain the nitrogen atmosphere. Raise the temperature to 40°C, maintain reflux, and add 2.0g of a 0.5% sodium ascorbate aqueous solution. After stirring for 2 minutes, irradiate the mixture with an ultrasonic cell disruptor at a frequency of 45kHz and a power of 100W. Maintain the reaction at 40°C for 4.5 hours.

[0084] Example 3

[0085] To a four-necked flask, add 100.0 g of liquid paraffin (McLean, reagent, analytical grade), 38.8 g of Span 60, and 1.2 g of OP-10 (HLB value of 5.0) and stir thoroughly to form the oil phase. Weigh 30.0 g of methacrylamide and 30.0 g of 2-acrylamido-2-methylpropanesulfonic acid, adjust the pH to 8 with sodium carbonate, and dissolve them in 150.0 g of deionized water. With mechanical stirring at 500 rad / min, add the oil phase dropwise at a rate of 1-2 drops / s using a dropping funnel at room temperature. After the addition was completed, high-purity nitrogen was introduced for 20 minutes and the nitrogen atmosphere was maintained. The system was heated to 65°C and 1.0 g of N,N,N',N'-tetramethylethylenediamine aqueous solution (solution mass concentration 10%) was added. After stirring for 2 minutes, the mixture was irradiated with an ultrasonic cleaner with a frequency of 55 kHz and a power of 200 W, and refluxed at 65°C for 4.0 hours.

[0086] Example 4

[0087] To a four-necked flask, add 100.0g of cyclohexane (Aladdin, reagent, analytical grade) and 35.0g of Span 80 (HLB value 4.3) and stir thoroughly to form the oil phase. Weigh 30.0g of N-isopropylacrylamide and 20.0g of dimethyldiallylammonium chloride and dissolve them in 200.0g of deionized water. With mechanical stirring at 700 rad / min, add the oil phase dropwise using a dropping funnel at a rate of 1-2 drops / s at room temperature. After the addition is complete, introduce high-purity argon gas for 20 minutes, maintaining reflux under condensation. Maintaining the argon atmosphere, raise the temperature to 55°C, add 6.25g of an 8% aqueous solution of disodium ethylenediaminetetraacetic acid, and stir for 2 minutes. Then, irradiate the mixture using an ultrasonic cell disruptor at a frequency of 70kHz and a power of 60W, maintaining the reaction at 55°C for 3.0 hours.

[0088] Example 5

[0089] To a four-necked flask, add 100.0g of dimethyl silicone oil (Aladdin, reagent, analytical grade), 24.0g of Span 85, and 1.0g of Tween 80 (HLB value 2.3) and stir thoroughly to form the oil phase. Weigh 40.0g of acrylamide and 10.0g of sodium p-styrene sulfonate and dissolve them in 80.0g of deionized water. Adjust the pH to 4 with hydrochloric acid. Add the oil phase dropwise using a dropping funnel at room temperature with mechanical stirring at 600 rad / min. After the addition is complete, introduce high-purity argon for 20 minutes and maintain the argon atmosphere. The system is heated to 80°C, and 2.0g of an aqueous solution of ethylenediamine (5% by mass) is added. After stirring for 2 minutes, the mixture is irradiated using an ultrasonic cell disruptor at 80 kHz and 600 W. The reaction is maintained at 80°C for 6 hours.

[0090] Example 6

[0091] To a four-necked flask, add 100.0 g of Saraline 185 (a Shell alpha-olefin synthetic base oil), 14.4 g of Span 40, and 0.6 g of Tween 40 (HLB value 7.1) and stir thoroughly to form the oil phase. Weigh 20.0 g of N-vinyl-2-pyrrolidone and 15.0 g of 2-acryloyloxy-2-methylpropanesulfonic acid and dissolve them in 60.0 g of deionized water. Adjust the pH to 10 with aqueous ammonia. Add the oil phase dropwise at a rate of 1-2 drops / s using a dropping funnel at room temperature with mechanical stirring at 750 rad / min. After the addition is completed, high-purity nitrogen is introduced for 20 minutes, the condensation reflux is maintained, and the nitrogen atmosphere is maintained. The system is heated to 70°C, the condensation reflux is maintained, 3.0 g of calcium hydroxybenzenesulfonate aqueous solution (solution mass concentration is 2%) is added, and after stirring for 2 minutes, it is irradiated with an ultrasonic cleaning machine with a frequency of 90 kHz and a power of 300 W, and the reaction is maintained at 70°C for 2.0 hours.

[0092] Example 7

[0093] To a four-necked flask, add 100.0g of toluene (Aladdin, reagent, analytical grade), 18.0g of Span 60, and 6.0g of OP-4 (HLB value of 5.6) and stir thoroughly to form the oil phase. Weigh 20.0g of sodium p-styrenesulfonate and 20.0g of acryloyloxyethyltrimethylammonium chloride and dissolve them in 100.0g of deionized water. Adjust the pH to 5 with phosphoric acid. Add the oil phase dropwise at a rate of 1-2 drops / s using a dropping funnel at room temperature with mechanical stirring at 600 rad / min. After the addition is completed, high-purity nitrogen is introduced for 20 minutes, the condensation reflux is maintained, and the nitrogen atmosphere is maintained. The system is heated to 75°C, 2.0 g of N,N,N',N'-tetramethylethylenediamine aqueous solution (solution mass concentration is 5%) is added, and after stirring for 2 minutes, it is irradiated with an ultrasonic cleaning machine with a frequency of 105 kHz and a power of 450 W, and the reaction is maintained at 75°C for 0.5 h.

[0094] Example 8

[0095] To a four-necked flask, add 100.0g of pentane (Aladdin, reagent, analytical grade), 39.0g of Span 83, and 1.0g of OP-15 (HLB value 4.0) and stir thoroughly to form the oil phase. Weigh 5.0g of N,N-diethylacrylamide, 60.0g of acrylic acid, and 5.0g of methacryloyloxyethyltrimethylammonium chloride and dissolve them in 200.0g of deionized water. Adjust the pH to 9 with potassium hydroxide. With mechanical stirring at 550 rad / min, the oil phase is added dropwise at a rate of 1-2 drops / s using a dropping funnel at room temperature. After the addition is complete, high-purity argon is introduced for 20 minutes and maintained. The system is then temperatureed to 20°C, and 0.25g of aqueous formaldehyde solution (40% by mass) is added. After stirring for 2 minutes, the mixture is irradiated using an ultrasonic cell disruptor at a frequency of 100 kHz and a power of 50 W. The reaction is maintained at 20°C for 1.5 hours.

[0096] Example 9

[0097] To a four-necked flask, add 100.0 g of hexane (Aladdin, reagent, analytical grade), 13.0 g of Span 85, and 12.0 g of OP-7 (HLB value of 6.7) and stir thoroughly to form the oil phase. Weigh 5.0 g of N-hydroxyethyl acrylamide, 60.0 g of acrylic acid, and 5.0 g of 2-acrylamido-2-methylpropanesulfonic acid and dissolve them in 100.0 g of deionized water. Adjust the pH to 10 with sodium hydroxide. Add the oil phase dropwise at a rate of 1-2 drops / s using a dropping funnel at room temperature with mechanical stirring at 400 rad / min. After the addition was completed, high-purity argon was introduced for 20 minutes and the argon atmosphere was maintained. The system was heated to 60°C and 1.0 g of thiourea aqueous solution (solution mass concentration was 10%) was added. After stirring for 2 minutes, the system was irradiated with an ultrasonic cell disruptor with a frequency of 60 kHz and a power of 80 W, and the reaction was maintained at 30°C for 6.0 hours.

[0098] Example 10

[0099] The method of Example 1 was followed, except that ascorbic acid was replaced with an equal mass of thiourea.

[0100] Comparative Example 1

[0101] In a four-necked flask, add 100.0g of No. 3 mineral white oil (Jingmen Petrochemical), 27.0g of span80, and 5.0g of Tween60 with an HLB value of 6.0, and stir evenly to form the oil phase. Weigh 100.0g of acrylamide and dissolve it in 100.0g of deionized water with an initial pH of around 7. Under a mechanical stirring speed of 650rad / min, add the oil phase dropwise at a rate of 1-2 drops / s using a dropping funnel at room temperature. After the addition is complete, introduce high-purity nitrogen for 20 minutes and maintain the nitrogen atmosphere. Heat the system to 50°C, maintain condensation reflux, stir for 2 minutes, and then irradiate with an ultrasonic cleaner with a frequency of 35kHz and a power of 150W. Maintain the reaction at 50°C for 5.0 hours.

[0102] Comparative Example 2

[0103] To a four-necked flask, add 100.0g of No. 5 mineral white oil (Jingmen Petrochemical), 20.0g of Span80, and 5.0g of Tween80 (HLB value of 6.4) and stir evenly to form the oil phase. Weigh 2.0g of N,N-dimethylacrylamide and 18.0g of acrylic acid, dissolve them in 50.0g of deionized water, adjust the pH to 6 with sodium hydroxide, and add the oil phase dropwise using a dropping funnel at a rate of 1-2 drops / s at room temperature under mechanical stirring at 450rad / min. After the addition is complete, introduce high-purity nitrogen for 20 minutes and maintain the nitrogen atmosphere. Raise the temperature to 40°C, maintain condensation reflux, stir for 2 minutes, and then irradiate with an ultrasonic cell disruptor at a frequency of 45KHz and a power of 100W. Maintain the reaction at 40°C for 4.5 hours.

[0104] Comparative Example 3

[0105] To a four-necked flask, add 100.0g of liquid paraffin (McLean, reagent, analytical grade), 38.8g of Span 60, and 1.2g of OP-10 (HLB value of 5.0) and stir thoroughly to form the oil phase. Weigh 30.0g of methacrylamide and 30.0g of 2-acrylamido-2-methylpropanesulfonic acid, adjust the pH to 8 with sodium carbonate, and dissolve them in 150.0g of deionized water. With mechanical stirring at 500 rad / min, add the oil phase dropwise using a dropping funnel at a rate of 1-2 drops / s at room temperature. After the addition is complete, introduce high-purity nitrogen for 20 minutes and maintain the nitrogen atmosphere. Heat the system to 65°C and stir for 2 minutes. Then, irradiate the system with an ultrasonic cleaner at a frequency of 55kHz and a power of 200W. Reflux at 65°C for 4 hours.

[0106] Comparative Example 4

[0107] In a four-necked flask, 100.0 g of No. 3 mineral white oil (Jingmen Petrochemical), 30.0 g of span80 and 5.0 g of Tween80 (HLB value of 5.8), 2.0 g of N,N-dimethylacrylamide and 18.0 g of acrylic acid and 100.0 g of deionized water were added. The mechanical stirring speed was maintained at 650 rad / min. High-purity nitrogen was introduced for 20 minutes, and the nitrogen atmosphere was maintained. The system was heated to 50°C and reflux was maintained. 8.0 g of ascorbic acid aqueous solution (solution mass concentration of 1.0%) was added. After stirring for 2 minutes, the mixture was irradiated with an ultrasonic cleaner with a frequency of 35 kHz and a power of 150 W, and the reaction was maintained at 50°C for 5.0 hours.

[0108] The monomer conversion rates during the reaction of the above examples and comparative examples and the property parameters of the obtained emulsion polymers are listed in Table 1.

[0109] Table 1

[0110]

[0111]

[0112] In Table 1, “ / ” indicates that when the monomer conversion rate is 0 in the reaction system of Comparative Examples 1-3, the apparent viscosity of the product cannot be measured; “*” indicates that inverse emulsion polymerization cannot be initiated in the reaction system of Comparative Example 4, and the product of Comparative Example 4 forms a gel, and the monomer conversion rate cannot be measured.

[0113] The data in the table above demonstrate that the method provided by the present invention can achieve inverse emulsion polymerization of water-soluble monomers to produce emulsion polymers, without the use of an initiator, using a nonionic emulsifier under ultrasonic irradiation and in the presence of an organic reducing agent. Compared to the comparative example, the examples provided by the present invention significantly improved monomer conversion and polymerization stability. Furthermore, the product molecular weight was qualitatively higher, as determined by the apparent viscosity of a 1% aqueous solution. In contrast, the comparative example, relying solely on a nonionic emulsifier and ultrasonic irradiation without the addition of an organic reducing agent, was unable to initiate inverse emulsion polymerization of water-soluble monomers to produce an emulsion polymer.

[0114] Application Examples

[0115] The emulsion polymers prepared in the above examples and comparative examples were used in drilling fluids and evaluated for fluid loss reduction performance in a composite brine slurry. Medium-pressure fluid loss was determined according to the method in GB / T 16783.1-2014. The test procedure was as follows:

[0116] Preparation of composite salt water slurry: 350 mL of distilled water was measured and placed in a high-speed stirring cup, 15.75 g of sodium chloride, 1.75 g of anhydrous calcium chloride, and 4.60 g of magnesium chloride were added, and stirred at a high speed of 11000 rad / min for 5 minutes. After they were dissolved, 52.50 g of bentonite for slurry preparation and 3.15 g of anhydrous sodium carbonate were added under stirring, and stirred at a high speed of 11000 rad / min for 20 minutes, stopping at least twice to scrape off the bentonite adhering to the wall of the container, and then sealed and cured at 25℃±3℃ for 24 hours to prepare the composite salt water base slurry.

[0117] To the composite brine-based slurry prepared according to the above method, 7.00 g of the emulsion polymer samples prepared in the above examples and comparative examples were added while stirring to ensure uniform dispersion. The slurry was then stirred at 11,000 rad / min for 20 minutes. The medium-pressure filtration loss was measured according to the method in GB / T 16783.1-2014. The test results are shown in Table 2.

[0118] Table 2

[0119]

[0120]

[0121] It can be seen from the data in the above table that the emulsion polymer prepared by the method provided by the present invention is used in the preparation of drilling fluid, so that the prepared drilling fluid has good rate loss reduction performance.

[0122] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, various simple variations of the technical solution of the present invention may be made, including combining the various technical features in any other appropriate manner. These simple variations and combinations should also be regarded as disclosed in the present invention and fall within the scope of protection of the present invention.

Claims

1. A method for inverse emulsion polymerization, wherein: The method comprises the following steps: (1) mixing an aqueous solution containing a water-soluble monomer, a nonionic emulsifier, and an oil phase to obtain a water-in-oil mixture, wherein the nonionic emulsifier has an HLB value of 2-8; (2) In the presence of an organic reducing agent, the water-in-oil mixture is subjected to an inverse emulsion polymerization reaction under ultrasonic irradiation conditions, and the inverse emulsion polymerization reaction does not use an initiator.

2. The method according to claim 1, wherein In step (1), the water-soluble monomer is selected from at least one of a nonionic monomer, an anionic monomer and a cationic monomer; Preferably, the nonionic monomer is selected from at least one of acrylamide, methacrylamide, N-isopropylacrylamide, N-hydroxyethylacrylamide, N,N-dimethylacrylamide, N,N-diethylacrylamide and N-vinyl-2-pyrrolidone; Preferably, the anionic monomer is selected from at least one of acrylic acid, sodium acrylate, itaconic acid, methacrylic acid, 2-acrylamido-2-methylpropanesulfonic acid, 2-acryloyloxy-2-methylpropanesulfonic acid, sodium methacrylic acid and sodium p-styrenesulfonate; Preferably, the cationic monomer is selected from at least one of dimethyldiallylammonium chloride, acryloyloxyethyltrimethylammonium chloride and methacryloyloxyethyltrimethylammonium chloride.

3. The method according to claim 1 or 2, wherein: The mass ratio of the water-soluble monomer to the oil phase is 0.05-2:1, preferably 0.1-1.5:1; Preferably, the mass ratio of the water phase to the oil phase is 0.2-2:1, more preferably 0.5-1.5:

1.

4. The method according to any one of claims 1 to 3, wherein: Step (1) further comprises optionally introducing an acid-base modifier into the aqueous solution containing the water-soluble monomer; Preferably, the acid-base regulator is a basic compound and / or an acidic compound; Preferably, the alkaline compound is selected from at least one of sodium hydroxide, potassium hydroxide, aqueous ammonia, sodium carbonate, sodium bicarbonate and potassium carbonate; Preferably, the acidic compound is selected from at least one of hydrochloric acid, sulfuric acid and phosphoric acid; Preferably, the amount of the acid-base regulator is such that the pH value of the aqueous solution containing the water-soluble monomer is 4-10.

5. The method according to any one of claims 1 to 4, wherein: In step (1), the nonionic emulsifier is a lipophilic emulsifier and optionally a hydrophilic emulsifier; Preferably, the lipophilic emulsifier is selected from the group consisting of Span series emulsifiers and / or amphiphilic block copolymer emulsifiers; Preferably, the hydrophilic emulsifier is a Tween series emulsifier and / or an OP series emulsifier; Preferably, the mass ratio of the nonionic emulsifier to the oil phase is 0.01-0.5:1, more preferably 0.1-0.4:

1.

6. The method according to any one of claims 1 to 5, wherein: In step (1), the oil phase is selected from at least one of alkanes, liquid paraffin, α-olefin synthetic base oil, mineral oil, aromatic hydrocarbons and linear polysiloxanes, preferably liquid paraffin and / or mineral oil; Preferably, the alkane is selected from C5-C14 alkanes, and further preferably is selected from at least one of pentane, hexane, cyclohexane, heptane and dodecane; Preferably, the α-olefin synthetic base oil is a C6-C24 α-olefin synthetic base oil, more preferably a C12-C18 α-olefin synthetic base oil; Preferably, the aromatic hydrocarbon is selected from C5-C10 aromatic hydrocarbons, more preferably toluene and / or xylene; Preferably, the linear polysiloxane is methyl silicone oil and / or dimethyl silicone oil.

7. The method according to any one of claims 1 to 6, wherein: In step (2), the organic reducing agent is selected from at least one of ascorbic acid, sodium ascorbate, ethylenediamine, ethylenediaminetetraacetic acid, disodium ethylenediaminetetraacetate, N,N,N',N'-tetramethylethylenediamine, N,N,N',N'-tetraethylethylenediamine, N,N,N',N'-tetraacetylethylenediamine, formaldehyde, acetaldehyde, thiourea and calcium dobesilate, preferably selected from at least one of ascorbic acid, sodium ascorbate, N,N,N',N'-tetramethylethylenediamine, N,N,N',N'-tetraethylethylenediamine, ethylenediaminetetraacetic acid and disodium ethylenediaminetetraacetate; Preferably, in step (2), the mass ratio of the organic reducing agent to the oil phase is 0.0005-0.01:1, more preferably 0.0005-0.001:

1.

8. The method according to any one of claims 1 to 7, wherein: In step (2), the conditions of the ultrasonic irradiation include: ultrasonic frequency of 35-105 kHz, ultrasonic power of 50-500 W, reaction temperature of 20-80° C., and reaction time of 0.5-6 h; Preferably, in step (2), the conditions of the ultrasonic irradiation include: ultrasonic frequency of 35-70 kHz, ultrasonic power of 60-200 W, reaction temperature of 40-65° C., and reaction time of 3-5 h.

9. An emulsion polymer obtained by the reactive emulsion polymerization method according to any one of claims 1 to 8.

10. Use of the emulsion polymer according to claim 9 in oilfield chemicals and / or paint products.

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