Hydrophobically modified lignin, compound emulsifier, acrylamide polymer emulsion and preparation method and application thereof

Abstract

The invention discloses hydrophobically modified lignin, a compound emulsifier, an acrylamide polymer emulsion and a preparation method and application thereof. The hydrophobic modified lignin is obtained by performing long-chain alkyl hydrophobic modification on phenolated lignin. The compound emulsifier comprises Tween and hydrophobic modified lignin. The acrylamide polymer emulsion disclosed by the invention is prepared by carrying out inverse emulsion synthesis by adopting a compound emulsifier containing hydrophobic modified lignin. The emulsion product obtained by the invention has the characteristics of low gel content, higher molecular weight, better long-term storage stability, lower residual monomer content and higher dissolution rate. According to the emulsification system, the production cost of the acrylamide polymer emulsion is reduced, the performance and economical efficiency requirements of site construction can be met, and the practicability is relatively high.

Description

Technical Field

[0001] The present invention relates to the technical field of emulsifiers. Further, it relates to hydrophobically modified lignin, composite emulsifiers, acrylamide polymer emulsions, and their preparation methods and applications. Background Art

[0002] The polyacrylamide structural unit contains an amide group, which is prone to forming intramolecular and intermolecular hydrogen bonds, endowing it with good thickening, flocculation, and drag reduction effects. Therefore, it has a wide range of applications in the fields of oil exploitation, water treatment, papermaking, etc. Currently, there are various methods for synthesizing polyacrylamide, such as aqueous solution polymerization, bulk polymerization, suspension polymerization, etc. Among them, the inverse emulsion polymerization method has the advantages of high polymerization rate, high molecular weight of the product, and rapid dissolution, becoming a research hotspot.

[0003] Inverse emulsion polymerization refers to a process in which an aqueous monomer solution and an organic oil phase form a water-in-oil emulsion under the emulsification of a surfactant and synthesize a water-in-oil polymer under the action of an initiator. Among them, emulsifiers belong to surfactants, which are substances that can form micelles and play an important role in emulsion polymerization. The type and dosage of emulsifiers and the selection of the emulsion system directly affect the stability of the inverse emulsion and are necessary conditions for successful polymerization reactions.

[0004] Lignin has the second largest reserve in nature after cellulose and is the second largest natural organic matter. Industrial lignin is rich in sources and low in price and can be used as a raw material for producing oilfield chemicals. With the rising price of petrochemical raw materials and the increasing environmental protection requirements, green chemicals using low-cost natural renewable resources such as lignin as raw materials have become an international hot research and development direction. Natural lignin is a natural polyaromatic macromolecular compound composed of hydrophobic non-polar groups with a phenylpropane skeleton and hydrophilic polar groups such as phenolic groups. The main connection methods between the structural main bodies of lignin are ether bonds and carbon-carbon bonds. These two types of bonds have low molecular polarity and high bond energy, making them difficult to react. Moreover, the methoxy content is high, the hydroxyl content is low, and there is a large steric hindrance on the benzene ring, resulting in significantly insufficient reactivity. For commercially available industrial by-product lignin, due to the condensation reaction after chemical treatment, its reaction sites are even fewer. Therefore, although lignin has certain surface activity, its use directly as an emulsifier has unsatisfactory effects due to its poor performance, and its application market is greatly restricted. Summary of the Invention

[0005] To solve the problems in the existing technology, the present invention provides a hydrophobically modified lignin, a composite emulsifier, an acrylamide polymer emulsion, and their preparation methods and applications. In the present invention, lignin is first modified to obtain a hydrophobically modified lignin. Among them, the hydrophobically modified lignin is obtained by first phenolizing lignin and then hydrophobically modifying it with a long-chain alkyl group. Then, the hydrophobically modified lignin and a Tween series surfactant are combined to form a composite emulsifier. This composite emulsifier can be applied to the inverse emulsion synthesis process of acrylamide polymers and can well emulsify and stabilize the polymerization reaction system. This emulsification system expands the raw material sources of surfactants. They all belong to natural surfactants, have high safety, and are biodegradable. When the composite emulsifier containing hydrophobically modified lignin is used in the process of inverse emulsion synthesis of acrylamide polymers, the obtained emulsion product has the characteristics of low gel content, higher molecular weight, better long-term storage stability, lower residual monomer content, and faster dissolution rate. This emulsification system reduces the production cost of acrylamide polymer emulsions, can meet the performance and economic requirements of on-site construction, and has high practicability. And after the acrylamide polymer is injected underground, the phenylpropane structure of lignin can well emulsify crude oil, which is beneficial to the emulsification and production of crude oil.

[0006] One of the purposes of the present invention is to provide a hydrophobically modified lignin, which is obtained by reacting raw materials including phenolated lignin and a long-chain acid; the phenolated lignin is selected from alkali-catalyzed modified phenolated lignin.

[0007] Another purpose of the present invention is to provide a preparation method of a hydrophobically modified lignin, including the following steps:

[0008] Under the action of an alkylation catalyst, raw materials including phenolated lignin and a long-chain acid are added to water for sealed heating reaction to obtain a hydrophobically modified lignin; the phenolated lignin is selected from alkali-catalyzed modified phenolated lignin;

[0009] Preferably, it is used for the preparation of the hydrophobically modified lignin according to any one of the purposes of the present invention.

[0010] In the preparation method of the hydrophobically modified lignin of the present invention, preferably,

[0011] The alkylation catalyst is selected from solid superacids; preferably, the alkylation catalyst is selected from at least one of SO4 2- / ZrO2, WO3 / ZrO2; and / or,

[0012] The long-chain acid is selected from C12-C18 long-chain acids; preferably, the long-chain acid is selected from at least one of oleic acid, stearic acid, palmitic acid, and lauric acid; and / or,

[0013] Based on the total mass of the alkylation catalyst, phenolic lignin, long-chain acid, and water added in this step being 100%,

[0014] the addition amount of the alkylation catalyst is 1 - 3 wt%;

[0015] the addition amount of the long-chain acid is 0.5 - 2.5 wt%;

[0016] the addition amount of the phenolic lignin is 15 - 30 wt%; and / or,

[0017] the balance is water;

[0018] In the present invention, there are no specific limitations on the conditions of the heating reaction, as long as the long-chain alkyl modification of lignin can be achieved. The inventors found in their research that the effect of the long-chain alkyl modification reaction is the best when the temperature is 150 - 200 °C and the time is 4 - 8 h.

[0019] In the method for preparing the hydrophobic modified lignin described in the present invention, preferably,

[0020] the method for preparing the alkali-catalyzed modified phenolic lignin is as follows:

[0021] Under closed conditions, the raw materials including lignin, phenolic modifier, and alkaline catalyst are subjected to a contact reaction in water, and then the pH is optionally adjusted to obtain phenolic lignin.

[0022] In the method for preparing the hydrophobic modified lignin described in the present invention, more preferably,

[0023] the lignin is selected from at least one of alkali lignin and enzymatically hydrolyzed lignin; and / or,

[0024] the phenolic modifier is selected from at least one of phenol and hydroquinone; and / or,

[0025] the alkaline catalyst is selected from at least one of sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium carbonate, sodium bicarbonate, and ammonia water; and / or,

[0026] Based on the total mass of the lignin, phenolic modifier, alkaline catalyst, and water added in this step being 100%,

[0027] the addition amount of the lignin is 10 - 15 wt%;

[0028] the mass ratio of the added phenolic modifier to the lignin is 0.2 - 0.4:1;

[0029] the mass ratio of the added alkaline catalyst to the lignin is 0.12 - 0.3:1; and / or,

[0030] the balance is water;

[0031] Adjust the pH to 2 - 3; and / or,

[0032] In the present invention, there are no particular limitations on the conditions for the contact reaction, as long as the phenolation of lignin can be achieved. The inventors found in their research that higher - activity lignin obtained under phenolation conditions of a temperature of 70 - 85 °C and a time of 0.5 - 2 h can achieve better results when used in the preparation process of hydrophobic - modified lignin surfactants.

[0033] In the present invention, the method for adjusting the pH is a commonly used method in the art. Preferably, the pH is adjusted by adding an acidic substance. The acidic substance can be at least one of hydrochloric acid, sulfuric acid, acetic acid, and oxalic acid.

[0034] In the present invention, the purification method can be a conventional purification method in the art, such as washing, drying, etc.

[0035] The third object of the present invention is to provide a composite emulsifier containing hydrophobic - modified lignin. The composite emulsifier includes Tween and hydrophobic - modified lignin; the hydrophobic - modified lignin is obtained by reacting raw materials including phenolated lignin and long - chain acid, and the hydrophobic - modified lignin is the hydrophobic - modified lignin according to any one of the first objects of the present invention or the hydrophobic - modified lignin prepared by the preparation method according to any one of the second objects of the present invention.

[0036] Compared with the phenolated lignin prepared by acid - catalysis, the phenolated lignin prepared by alkali - catalyzed modification in the present invention can further increase the reaction sites for hydrophobic modification, thereby increasing the number of hydrophobic alkyl groups introduced into lignin and improving the hydrophobic - modification effect of lignin.

[0037] The hydrophobic - modified lignin prepared in the present invention is a non - ionic surfactant. Compared with conventional lignin sulfonates, it has good emulsifying performance, hard - water resistance, and low foaming property. The macromolecular modified lignin and the small - molecule Tween form a spatial and activity complementarity, having a synergistic effect, which greatly improves the stability and efficiency of the emulsifying system.

[0038] In the composite emulsifier containing hydrophobic - modified lignin according to the present invention, preferably,

[0039] In the composite emulsifier,

[0040] the content of Tween is 10 - 25 wt%;

[0041] the content of hydrophobic - modified lignin is 75 - 90 wt%;

[0042] Preferably,

[0043] the content of Tween is 15 - 20 wt%;

[0044] The content of the hydrophobic modified lignin is 80 - 85 wt%.

[0045] In the composite emulsifier containing hydrophobic modified lignin according to the present invention, preferably, the Tween is selected from at least one of Tween 40, Tween 60, and Tween 80.

[0046] A fourth object of the present invention is to provide a preparation method of the composite emulsifier containing hydrophobic modified lignin according to any one of the third objects of the present invention, comprising the following steps:

[0047] Mix Tween and hydrophobic modified lignin uniformly to obtain the composite emulsifier.

[0048] In the present invention, there is no particular limitation on the mixing of the hydrophobic modified lignin surfactant and the Tween series surfactant, and it can be mixed uniformly.

[0049] A fifth object of the present invention is to provide an acrylamide polymer emulsion, which is prepared by inverse emulsion synthesis using raw materials including the composite emulsifier containing hydrophobic modified lignin, monomers, initiators, and chelating agents according to any one of the third objects of the present invention to obtain the acrylamide polymer emulsion.

[0050] A sixth object of the present invention is to provide a preparation method of an acrylamide polymer emulsion, comprising the following steps:

[0051] Form an oil solution by mixing the composite emulsifier with an organic solvent;

[0052] Mix the vinyl monomer, optionally the sulfonic acid monomer, the chelating agent, a part of the initiator, and water to form an aqueous solution;

[0053] Mix the oil solution and the aqueous solution to form a water-in-oil emulsion;

[0054] After deoxidizing the water-in-oil emulsion, add the remaining initiator to carry out a polymerization reaction to obtain the acrylamide polymer emulsion;

[0055] Preferably, the method is used to prepare the acrylamide polymer emulsion according to the fifth object of the present invention.

[0056] In the preparation method of the acrylamide polymer emulsion according to the present invention, preferably,

[0057] The organic solvent is selected from at least one of white oil and kerosene; and / or,

[0058] The mass ratio of the organic solvent to the composite emulsifier is 1:0.05 - 0.2; and / or,

[0059] The vinyl monomer is selected from at least one of acrylamide, acrylic acid, and N-isopropylacrylamide; and / or,

[0060] When containing sulfonic acid monomers, the sulfonic acid monomers are selected from at least one of 2-acrylamido-2-methylpropanesulfonic acid and 2-acryloyloxy-2-methylpropanesulfonic acid; and / or,

[0061] The chelating agent is selected from at least one of disodium ethylenediaminetetraacetate and trisodium ethylenediaminetetraacetate; and / or,

[0062] The initiator is selected from at least one of redox initiators (such as ammonium persulfate-sodium bisulfite) and azo initiators (such as VA-044); and / or,

[0063] In an aqueous solution,

[0064] The content of the vinyl monomer is 40-50 wt%;

[0065] The content of the sulfonic acid monomer is 0-50 wt%;

[0066] The content of the chelating agent is 0.01-0.1 wt%;

[0067] The content of a part of the initiator added is 0.01-0.1 wt%; the rest is water, and / or,

[0068] The mass ratio of the part of the initiator to the remaining initiator is 1-4:1; and / or,

[0069] The mass ratio of the aqueous solution to the oil solution is 1-3:1; and / or,

[0070] The temperature of the polymerization reaction does not exceed 40 °C; preferably, the temperature of the polymerization reaction does not exceed 35 °C; and / or,

[0071] The time of the polymerization reaction is 2-6 h.

[0072] The seventh object of the present invention is to provide an application of an acrylamide polymer emulsion as described in the fifth object of the present invention or an acrylamide polymer emulsion prepared by the method as described in any one of the sixth objects of the present invention in oil exploitation.

[0073] In the ranges and any values disclosed in the present invention, the endpoints and any values are not limited to the exact ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, between the endpoint values of each range, between the endpoint values of each range and a single point value, and between single point values, they can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein. In the following text, in principle, the various technical solutions can be combined with each other to obtain new technical solutions, which should also be regarded as specifically disclosed herein.

[0074] Compared with the prior art, the present invention has the following advantages:

[0075] The composite emulsifier containing hydrophobically modified lignin in this patent consists of Tween series surfactants and hydrophobically modified lignin surfactants. Among them, the hydrophobically modified lignin surfactant is obtained by first phenolicating lignin and then hydrophobically modifying it with a long-chain alkyl group. The inventors of the present invention unexpectedly found in the research that by carrying out alkaline phenolic modification on lignin, the content of phenolic hydroxyl groups in lignin can be greatly increased, the reaction activity of lignin can be significantly improved, and the conversion rate of lignin in the subsequent hydrophobic modification can be enhanced. When the hydrophobically modified lignin composite emulsion system is used in the process of inverse emulsion synthesis of acrylamide polymers, the obtained emulsion products have the characteristics of low gel content, higher molecular weight, better long-term storage stability, lower residual monomer content, and faster dissolution rate.

[0076] The present invention also discovers that there is a synergistic effect when using the composite emulsifier containing hydrophobically modified lignin and a specific Tween surfactant as an emulsifier, and it has a good emulsifying effect.

[0077] The present invention uses lignin as the raw material for preparing emulsifiers, which can turn waste into treasure and significantly reduce the cost of emulsifiers. Detailed implementation manners

[0078] The present invention will be specifically described below in conjunction with specific embodiments. It is necessary to point out here that the following embodiments are only for further illustration of the present invention and cannot be understood as limiting the protection scope of the present invention. Some non-essential improvements and adjustments made by those skilled in the art to the present invention based on the content of the present invention still fall within the protection scope of the present invention.

[0079] In addition, it should be noted that among the various specific technical features described in the following detailed implementation manners, they can be combined in any appropriate way without contradiction. To avoid unnecessary repetition, the present invention will not further explain various possible combination methods.

[0080] In addition, any combination can be made among various different implementation manners of the present invention as long as it does not violate the idea of the present invention. The technical solutions formed thereby belong to a part of the original disclosure content of this specification and also fall within the protection scope of the present invention.

[0081] Source of raw materials:

[0082] Enzymatic hydrolysis lignin was purchased from Shandong Longli Biotechnology Co., Ltd., and the effective lignin content was 94.8 wt%.

[0083] Alkali lignin was purchased from J&K Scientific Ltd.

[0084] The catalyst WO3 / ZrO2 was purchased from Beijing Innochem Science & Technology Co., Ltd.;

[0085] Catalyst SO4 2 - / ZrO2 was purchased from Beijing InnoChem Technology Co., Ltd.;

[0086] Other raw materials of the present invention are all conventional commercially available products.

[0087] Testing method:

[0088] Molecular weight test:

[0089] The intrinsic viscosity was determined according to the method for determining the intrinsic viscosity of polyacrylamide in GB 12005.1-1989, and the molecular weight was calculated based on the intrinsic viscosity.

[0090] Determination of residual monomer content:

[0091] The residual monomer content was determined according to the method for determining the residual acrylamide content in polyacrylamide in GB 12005.3-1989.

[0092] Testing method for dissolution time: The viscosity was measured every minute, and the time when the viscosity reached 80% of the final viscosity was taken as the dissolution time.

[0093] Example 1

[0094] (1) Preparation of highly active lignin: 80.2 g of water and 2.4 g of catalyst NaOH were added to a three-necked flask equipped with a stirrer and a condenser; the temperature of the system was raised to the set temperature of 80 °C, and 13.6 g of enzymatically hydrolyzed lignin and 3.8 g of phenol were successively added under stirring, and stirring was continued, heating and refluxing for 1.5 h; after the reaction was completed, hydrochloric acid was added to adjust the pH of the reaction system to 3.0 to precipitate the product, and the product highly active lignin (i.e., alkali-catalyzed modified phenolic lignin) was obtained by centrifugal separation, washing and vacuum drying.

[0095] (2) Preparation of hydrophobic modified lignin surfactant: 24.5 g of highly active lignin was added to a high-pressure reactor with polytetrafluoroethylene, and stirred evenly; 2.5 g of catalyst WO3 / ZrO2 and 2.1 g of oleic acid were added, the temperature of the system was raised to 170 °C, the reaction was stopped after 6 h, the system was cooled to room temperature, and the hydrophobic modified lignin surfactant was obtained by separation and purification.

[0096] (3) 6.52 g of the hydrophobic modified lignin surfactant and 1.48 g of Tween 80 were mixed evenly to obtain a hydrophobic modified lignin composite emulsion system.

[0097] (4) When the hydrophobic modified lignin composite emulsion system is used in the process of inverse emulsion synthesis of acrylamide polymers, specifically: 8 g of the hydrophobic modified lignin composite emulsion system and 60 g of white oil are formed into an oil solution; 80 g of acrylamide and 10 g of 2-acrylamido-2-methylpropanesulfonic acid sodium are dissolved in 80 g of water, the pH is adjusted to 6.5, then 0.02 g of disodium ethylenediaminetetraacetate, 0.015 g of VA-044 (initiator azobisisobutimidazoline hydrochloride), and 0.01 g of ammonium persulfate initiator are completely dissolved to form an aqueous solution; the oil solution and the aqueous solution are mixed and emulsified at high speed to form a water-in-oil emulsion; after the water-in-oil emulsion is deoxygenated, 1 g of 1 wt% sodium bisulfite aqueous solution is slowly dropped in to make the water-in-oil emulsion carry out a polymerization reaction, the reaction temperature is controlled not to exceed 35 °C, and the reaction is stopped when the system no longer continues to heat up; an acrylamide polymer emulsion is obtained.

[0098] The gel content of the emulsion product obtained by the above method is 0.6 wt%, the dissolution time is 2 min, it is stratified after being placed at room temperature for 195 days, the viscosity-average molecular weight of the polymer is 18.2 million, and the residual monomer content is 0.04 wt%.

[0099] Example 2

[0100] (1) Preparation of highly active lignin: 80.2 g of water and 1.8 g of catalyst KOH are added to a three-necked flask equipped with a stirrer and a condenser; the system is heated to the set temperature of 70 °C, and 15 g of alkali lignin and 3.0 g of hydroquinone are successively added under stirring, and then continue to stir, heat and reflux for 0.5 h; after the reaction is completed, hydrochloric acid is added to adjust the pH of the reaction system to 2.5 to precipitate the product, and the product highly active lignin is obtained through centrifugal separation, washing and vacuum drying.

[0101] (2) Preparation of hydrophobic modified lignin surfactant: 24.5 g of highly active lignin is added to a high-pressure reactor with polytetrafluoroethylene and 70.9 g of water, and stirred evenly; 2.5 g of catalyst WO3 / ZrO2 and 2.1 g of oleic acid are added, the system is heated to 170 °C, and the reaction is stopped after 6 h, the system is cooled to room temperature, and the hydrophobic modified lignin surfactant is obtained through separation and purification.

[0102] (3) 6.52 g of the hydrophobic modified lignin surfactant and 1.48 g of Tween 60 are mixed evenly to obtain a hydrophobic modified lignin composite emulsion system.

[0103] (4) The hydrophobic modified lignin composite emulsion system is used in the process of inverse emulsion synthesis of acrylamide polymers under the same conditions as in Example 1.

[0104] The gel content of the emulsion product obtained by the above method is 0.8 wt%, the dissolution time is 2 min, it separates into layers after being placed at room temperature for 160 days, the viscosity-average molecular weight of the polymer is 20.2 million, and the residual monomer content is 0.06 wt%.

[0105] Example 3

[0106] (1) Preparation of highly active lignin: Add 80.2 g of water and 2.4 g of catalyst NaOH into a three-necked flask equipped with a stirrer and a condenser; heat the system to the set temperature of 80 °C, and successively add 13.6 g of enzymatically hydrolyzed lignin and 3.8 g of phenol under stirring, continue stirring, heat and reflux for 1.5 h; after the reaction is completed, add hydrochloric acid to adjust the pH of the reaction system to 3.0 to precipitate the product, and obtain the product highly active lignin through centrifugal separation, washing, and vacuum drying.

[0107] (2) Preparation of hydrophobic modified lignin surfactant: Add 24.5 g of highly active lignin into a high-pressure reactor with polytetrafluoroethylene, add 70.9 g of water, and stir evenly; add 2.5 g of catalyst WO3 / ZrO2 and 2.1 g of oleic acid, heat the system to 170 °C, stop the reaction after 6 h, cool the system to room temperature, and separate and purify to obtain the hydrophobic modified lignin surfactant.

[0108] (3) Mix 6 g of the hydrophobic modified lignin surfactant and 2 g of Tween 80 evenly to obtain a hydrophobic modified lignin composite emulsion system.

[0109] (4) Use the hydrophobic modified lignin composite emulsion system in the process of inverse emulsion polymerization to synthesize acrylamide polymers under the same conditions as in Example 1.

[0110] The gel content of the emulsion product obtained by the above method is 0.9 wt%, the dissolution time is 3 min, it separates into layers after being placed at room temperature for 170 days, the viscosity-average molecular weight of the polymer is 21.8 million, and the residual monomer content is 0.05 wt%.

[0111] Example 4

[0112] It uses the same preparation method as in Example 1, except that the long-chain acid used is selected from stearic acid.

[0113] The gel content of the emulsion product obtained by the above method is 0.7 wt%, the dissolution time is 2 min, it does not separate into layers after centrifuging at 5000 rpm for 15 min, it separates into layers after being placed at room temperature for 165 days, the viscosity-average molecular weight of the polymer is 17.1 million, and the residual monomer content is 0.13 wt%.

[0114] Example 5

[0115] It uses the same preparation method as in Example 1, except that the long-chain acid used is selected from palmitic acid.

[0116] The gel content of the emulsion product obtained by the above method is 1.0 wt%, the dissolution time is 3 min, it separates into layers after being placed at room temperature for 165 days, the viscosity-average molecular weight of the polymer is 21 million, and the residual monomer content is 0.11 wt%.

[0117] Example 6

[0118] It uses the same preparation method as in Example 1, except that the long-chain acid used is selected from lauric acid.

[0119] The gel content of the emulsion product obtained by the above method is 1.2 wt%, the dissolution time is 3 min, it separates into layers after being placed at room temperature for 160 days, the viscosity-average molecular weight of the polymer is 22.2 million, and the residual monomer content is 0.14 wt%.

[0120] Comparative Example 1

[0121] The experiment was carried out according to the method of Example 1. The difference is that the enzymatically hydrolyzed lignin was replaced with sodium lignosulfonate. The gel content of the obtained emulsion product is 6.8 wt%, the dissolution time is 4 min, it separates into layers after being placed at room temperature for 20 days, the viscosity-average molecular weight of the polymer is 13.8 million, and the residual monomer content is 0.43 wt%.

[0122] Comparative Example 2

[0123] The experiment was carried out according to the method of Example 1. The difference is that 3.8 g of phenol was replaced with the same mass of water. The gel content of the obtained emulsion product is 14.7 wt%, the dissolution time is 15 min, it separates into layers after being placed at room temperature for 6 days, the viscosity-average molecular weight of the polymer is 12.9 million, and the residual monomer content is 0.32 wt%.

[0124] Comparative Example 3

[0125] The experiment was carried out according to the method of Example 1. The difference is that 6.52 g of the hydrophobic modified lignin surfactant was replaced with the same mass of Span 80.

[0126] The gel content of the obtained emulsion product is 4.9 wt%, the dissolution time is 10 min, it separates into layers after being placed at room temperature for 24 days, the viscosity-average molecular weight of the polymer is 17.1 million, and the residual monomer content is 0.13 wt%.

[0127] Comparative Example 4

[0128] The experiment was carried out according to the method of Example 1. The difference is that 6.52 g of the hydrophobic modified lignin surfactant was replaced with the same mass of Tween 80.

[0129] The gel content of the emulsion product obtained by the above method is 50.8 wt%, it cannot be dissolved, and it directly separates into layers at room temperature. The viscosity-average molecular weight of the polymer is 3.8 million, and the residual monomer content is 3.11 wt%.

[0130] Comparative Example 5

[0131] The experiment was carried out according to the method of Example 1, except that 1.48 g of Tween 80 was replaced with the same mass of the hydrophobically modified lignin surfactant prepared in Example 1.

[0132] The gel content of the emulsion product obtained by the above method is 8.9 wt%, the dissolution time is 30 min, it separates into layers after standing at room temperature for 15 days, the viscosity-average molecular weight of the polymer is 10.3 million, and the residual monomer content is 1.87 wt%.

[0133] Comparative Example 6

[0134] The experiment was carried out according to the method of Example 1, except that 6.52 g of the hydrophobically modified lignin surfactant was replaced with the base-catalyzed modified phenolic lignin prepared in step (1) of Example 1.

[0135] The gel content of the emulsion product obtained by the above method is 59.2 wt%, it cannot be dissolved, and it directly separates into layers at room temperature. The viscosity-average molecular weight of the polymer is 2.3 million, and the residual monomer content is 8.01 wt%.

[0136] The present invention has been described in detail above in combination with specific embodiments and exemplary examples, but these descriptions should not be construed as limiting the present invention. Those skilled in the art understand that without departing from the spirit and scope of the present invention, various equivalent replacements, modifications or improvements can be made to the technical solutions and implementation manners of the present invention, and these all fall within the scope of the present invention. The protection scope of the present invention is subject to the appended claims.

[0137] All publications, patent applications, patents and other references mentioned in this specification are hereby incorporated by reference. Unless otherwise defined, all technical and scientific terms used in this specification have the meanings commonly understood by those skilled in the art. In case of conflict, the definitions in this specification shall prevail.

[0138] When this specification uses prefixes such as "well-known to those skilled in the art", "prior art" or similar terms to derive materials, substances, methods, steps, devices or components, etc., the objects derived by such prefixes cover those commonly used in the art at the time when this application is filed, but also include those that are not commonly used at present but will become commonly recognized in the art as suitable for similar purposes.

[0139] In the context of this specification, any matter or thing not mentioned, other than what is expressly stated, shall directly apply those known in the art without any change.

Claims

1. A hydrophobic modified lignin, characterized in that: The hydrophobic modified lignin is obtained by reacting raw materials including phenolic lignin and long-chain acid; the phenolic lignin is selected from phenolic lignin modified by alkali catalysis.

2. A preparation method of hydrophobic modified lignin, characterized in that, It includes the following steps: Under the action of an alkylation catalyst, raw materials including phenolic lignin and long-chain acid are added to water for sealed heating reaction to obtain hydrophobic modified lignin; the phenolic lignin is selected from phenolic lignin modified by alkali catalysis; Preferably, it is used for the preparation of the hydrophobic modified lignin described in claim 1.

3. The preparation method of the hydrophobic modified lignin according to claim 2, wherein: The alkylation catalyst is selected from solid superacids; preferably, the alkylation catalyst is selected from at least one of SO4 2- / ZrO2 and WO3 / ZrO2; and / or, The long-chain acid is selected from long-chain acids of C12-C18; preferably, the long-chain acid is selected from at least one of oleic acid, stearic acid, palmitic acid, and lauric acid; and / or, Based on the total mass of the alkylation catalyst, phenolic lignin, long-chain acid, and water added in this step being 100%, The addition amount of the alkylation catalyst is 1-3 wt%; The addition amount of the long-chain acid is 0.5-2.5 wt%; The addition amount of the phenolic lignin is 15-30 wt%; and / or, The temperature of the heating reaction is 150-200 °C; and / or, The time of the heating reaction is 4-8 h.

4. The preparation method of the hydrophobic modified lignin according to claim 2, wherein: The preparation method of the phenolic lignin is: Under sealed conditions, raw materials including lignin, phenolic modifier, and alkaline catalyst are subjected to contact reaction in water, and optionally the pH is adjusted to obtain phenolic lignin.

5. The preparation method of the hydrophobic modified lignin according to claim 4, wherein: The lignin is selected from at least one of alkali lignin and enzymatically hydrolyzed lignin; and / or, The phenolic modifier is selected from at least one of phenol and hydroquinone; and / or, The alkaline catalyst is selected from at least one of sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium carbonate, sodium bicarbonate, and ammonia water; and / or, Based on the total mass of the lignin, phenolic modifier, alkaline catalyst, and water added in this step being 100%, The addition amount of the lignin is 10-15 wt%; The mass ratio of the added phenolic modifier to the lignin is 0.2-0.4:1; The mass ratio of the added alkaline catalyst to the lignin is 0.12-0.3:1; and / or, Adjust the pH = 2-3; and / or, The temperature of the contact reaction is 70-85 °C; and / or, The contact reaction time is 0.5-2 h.

6. A composite emulsifier containing hydrophobic modified lignin, wherein: The composite emulsifier includes Tween and hydrophobic modified lignin; The hydrophobic modified lignin is the hydrophobic modified lignin described in claim 1 or the hydrophobic modified lignin prepared by the preparation method described in any one of claims 2-5.

7. The composite emulsifier containing hydrophobic modified lignin according to claim 6, wherein: In the composite emulsifier, The content of Tween is 10-25 wt%; The content of hydrophobic modified lignin is 75-90 wt%; Preferably, The content of Tween is 15-20 wt%; The content of hydrophobic modified lignin is 80-85 wt%.

8. The composite emulsifier containing hydrophobically modified lignin according to claim 6, wherein the Tween is selected from at least one of Tween 40, Tween 60, and Tween 80.

9. A preparation method of a composite emulsifier containing hydrophobically modified lignin as described in any one of claims 6-8, characterized in that, It includes the following steps: Mix Tween and hydrophobically modified lignin evenly to obtain the composite emulsifier.

10. An acrylamide polymer emulsion, characterized in that, Use raw materials including the composite emulsifier containing hydrophobically modified lignin according to any one of claims 6-8, monomers, initiators, and chelating agents to carry out inverse emulsion synthesis to obtain an acrylamide polymer emulsion.

11. A method for preparing an acrylamide polymer emulsion, characterized in that: Form an oil solution by mixing the composite emulsifier with an organic solvent; the composite emulsifier is selected from the composite emulsifier containing hydrophobically modified lignin according to any one of claims 6-8; Mix vinyl monomers, optionally sulfonic acid monomers, chelating agents, a part of the initiator, and water to form an aqueous solution; Mix the oil solution and the aqueous solution to form a water-in-oil emulsion; After deoxygenating the water-in-oil emulsion, add the remaining initiator to carry out a polymerization reaction to obtain an acrylamide polymer emulsion; Preferably, the method is used to prepare the acrylamide polymer emulsion according to claim 10.

12. According to the method for preparing an acrylamide polymer emulsion according to claim 11, characterized in that: The organic solvent is selected from at least one of white oil and kerosene; and / or, The mass ratio of the organic solvent to the composite emulsifier is 1:0.05-0.2; and / or, The vinyl monomer is selected from at least one of acrylamide, acrylic acid, and N-isopropylacrylamide; and / or, When sulfonic acid monomers are contained, the sulfonic acid monomers are selected from at least one of 2-acrylamido-2-methylpropanesulfonic acid and 2-acryloyloxy-2-methylpropanesulfonic acid; and / or, The chelating agent is selected from at least one of disodium ethylenediaminetetraacetate and trisodium ethylenediaminetetraacetate; and / or, The initiator is selected from at least one of redox initiators and azo initiators; and / or, In the aqueous solution, the content of the vinyl monomer is 40-50 wt%; the content of the sulfonic acid monomer is 0-50 wt%; the content of the chelating agent is 0.01-0.1 wt%; the content of the part of the initiator added is 0.01-0.1 wt%; and / or, the mass ratio of the part of the initiator to the remaining initiator is 1-4:1; and / or, the mass ratio of the aqueous solution to the oil solution is 1-3:1; and / or, the temperature of the polymerization reaction does not exceed 40 °C; preferably, the temperature of the polymerization reaction does not exceed 35 °C; and / or, the time of the polymerization reaction is 2-6 h.

13. Application of the acrylamide polymer emulsion according to claim 10 or the acrylamide polymer emulsion prepared by the method according to any one of claims 11-12 in oil exploitation.