Calcium-magnesium-ion-resistant polyacrylamide and preparation method thereof

文档序号:2682 发布日期:2021-09-17 浏览:51次 中文

1. A preparation method of calcium and magnesium ion resistant polyacrylamide is characterized by comprising the following steps:

(1) carrying out esterification reaction on bisphenol A type epoxy resin and acrylic acid to obtain epoxy acrylate monoester;

(2) carrying out ring-opening polymerization reaction on epoxy acrylate monoester and polyethylene glycol to obtain modified bisphenol A resin;

(3) uniformly mixing modified bisphenol A resin, acrylamide, sodium acrylate, 2-acrylamide-2-methylpropanesulfonic acid and a surfactant by using water to obtain a mixed solution, and then carrying out copolymerization reaction on the mixed solution under the action of an initiator and a chain transfer agent to obtain the calcium-magnesium ion resistant polyacrylamide.

2. The preparation method according to claim 1, wherein after the step (3), the method further comprises the step of sequentially drying and grinding the prepared calcium-magnesium ion resistant polyacrylamide.

3. The method of claim 1, wherein:

in the step (1), the mass ratio of the bisphenol a type epoxy resin to the acrylic acid is 1: (0.1 to 1.25); and/or

In the step (2), the mass ratio of the epoxy acrylate monoester to the polyethylene glycol is 1: (0.25 to 1.5).

4. The method of claim 1, wherein:

in the step (1), the temperature of the esterification reaction is 50-120 ℃, and the time of the esterification reaction is 1-5 h; and/or

In the step (2), the temperature of the ring-opening polymerization reaction is 50-100 ℃, and the time of the ring-opening polymerization reaction is 0.5-3 h.

5. The method of claim 1, wherein:

the polyethylene glycol is one or more of polyethylene glycol with molecular weight of 500-1500.

6. The production method according to any one of claims 1 to 5, wherein in step (3), acrylamide, sodium acrylate, 2-acrylamido-2-methylpropanesulfonic acid, water, a surfactant, a modified bisphenol A type resin, a chain transfer agent, and an initiator are used in the following amounts:

50-80 parts of acrylamide, 80-100 parts of sodium acrylate, 20-80 parts of 2-acrylamide-2-methylpropanesulfonic acid, 300-800 parts of water, 1-15 parts of surfactant, 5-50 parts of modified bisphenol A type resin, 0.001-1 part of chain transfer agent and 0.01-1 part of initiator.

7. The method of claim 1, wherein:

the mass ratio of the sum of the usage amounts of the acrylamide, the sodium acrylate and the 2-acrylamide-2-methylpropanesulfonic acid to the usage amount of the modified bisphenol A type resin is (10-300): 1.

8. the production method according to any one of claims 1 to 5, characterized in that:

the surfactant is dodecyl dimethyl betaine and/or sodium dodecyl sulfate;

the chain transfer agent is formate; and/or

The initiator is persulfate.

9. The production method according to any one of claims 1 to 5, characterized in that:

in the step (3), the initiation temperature of the copolymerization reaction is 0-2 ℃, and/or the time of the copolymerization reaction is 2-4 h; and/or

And (3) introducing nitrogen into the mixed solution to remove oxygen, and then sequentially adding the initiator and the chain transfer agent into the mixed solution under the protection of the nitrogen so as to enable the mixed solution to carry out copolymerization reaction under the action of the initiator and the chain transfer agent.

10. The calcium-magnesium ion resistant polyacrylamide prepared by the preparation method of any one of claims 1 to 9.

Background

As the oil field exploitation technology gradually enters a tertiary oil recovery stage, the viscosity requirement of polyacrylamide under a special environment is higher and higher, and the long-time temperature resistance and salt tolerance gradually become important indexes of the polyacrylamide. Hypersalinity brines contain large amounts of divalent salt metal ions, and divalent salts such as calcium and magnesium ions have a greater effect on polyacrylamide viscosity. At present, the post-hydrolysis polyacrylamide process is a main process for preparing high-viscosity polyacrylamide in tertiary oil recovery, but the post-hydrolysis polyacrylamide prepared by the process also has the problems of poor solubility, low viscosity retention rate under high temperature and high mineralization degree and the like in practical application.

Chinese patent application CN109705264A discloses a preparation method of temperature-resistant and salt-resistant polyacrylamide for oil displacement, wherein functional monomers, high-temperature stabilizers and cosolvents are added to improve the salt resistance and solubility of the product, and a high-temperature dynamic hydrolysis process is adopted to improve the traditional hydrolysis process, thereby solving the problems of slow temperature rise, high material temperature when adding a hydrolytic agent, uneven size of colloidal particles and the like in the traditional process. However, the product prepared by the patent application is unstable in performance, needs a large amount of time for heat preservation during hydrolysis, and is not beneficial to continuous production.

Chinese patent application CN111349193A proposes a preparation method of quaternary copolymerization temperature-resistant and salt-resistant polyacrylamide, which adopts a plurality of temperature-resistant and salt-resistant monomers such as sodium allylsulfonate, sodium methallylsulfonate, sodium vinylsulfonate, methacryloyloxyethyl dimethyl benzyl ammonium chloride, vinyl pyrrolidone and the like to prepare the quaternary copolymerization temperature-resistant and salt-resistant polyacrylamide, the apparent viscosity of the quaternary copolymerization temperature-resistant and salt-resistant polyacrylamide in 26 ten thousand salinity saline water at 140 ℃ in Xinjiang can reach about 40 mPa.s, but the dosage of the temperature-resistant and salt-resistant monomers adopted by the quaternary copolymerization temperature-resistant and salt-resistant polyacrylamide is too large, the molecular weight of the polyacrylamide is influenced, the price of the monomers is very high, and the quaternary copolymerization temperature-resistant and salt-resistant polyacrylamide is difficult to be widely applied in the market due to higher cost requirement in industrial production.

Therefore, it is very necessary to provide a calcium and magnesium ion resistant polyacrylamide which is little affected by calcium and magnesium ions, has high viscosity retention rate and is suitable for application in tertiary oil recovery, and a preparation method thereof.

Disclosure of Invention

In order to solve the technical problems in the prior art, the invention provides calcium-magnesium ion resistant polyacrylamide and a preparation method thereof. The calcium-magnesium ion resistant polyacrylamide prepared by the invention is slightly influenced by calcium and magnesium ions, has good viscosity in 10wt% calcium chloride and 10wt% magnesium chloride salt water, and has high viscosity retention rate.

The invention provides a preparation method of calcium-magnesium ion resistant polyacrylamide in a first aspect, which comprises the following steps:

(1) carrying out esterification reaction on bisphenol A type epoxy resin and acrylic acid to obtain epoxy acrylate monoester;

(2) carrying out ring-opening polymerization reaction on epoxy acrylate monoester and polyethylene glycol to obtain modified bisphenol A resin;

(3) uniformly mixing modified bisphenol A resin, acrylamide, sodium acrylate, 2-acrylamide-2-methylpropanesulfonic acid and a surfactant by using water to obtain a mixed solution, and then carrying out copolymerization reaction on the mixed solution under the action of an initiator and a chain transfer agent to obtain the calcium-magnesium ion resistant polyacrylamide.

Preferably, after the step (3), the method further comprises the step of drying and grinding the prepared calcium-magnesium ion resistant polyacrylamide in sequence.

Preferably, in the step (1), the mass ratio of the bisphenol a type epoxy resin to the acrylic acid is 1: (0.1 to 1.25); and/or in the step (2), the mass ratio of the epoxy acrylate monoester to the polyethylene glycol is 1: (0.25 to 1.5).

Preferably, in the step (1), the temperature of the esterification reaction is 50-120 ℃, and the time of the esterification reaction is 1-5 h; and/or in the step (2), the temperature of the ring-opening polymerization reaction is 50-100 ℃, and the time of the ring-opening polymerization reaction is 0.5-3 h.

Preferably, the polyethylene glycol is one or more of polyethylene glycols having a molecular weight of 500 to 1500.

Preferably, in step (3), acrylamide, sodium acrylate, 2-acrylamido-2-methylpropanesulfonic acid, water, a surfactant, a modified bisphenol a-type resin, a chain transfer agent, and an initiator are used in the following amounts: 50-80 parts of acrylamide, 80-100 parts of sodium acrylate, 20-80 parts of 2-acrylamide-2-methylpropanesulfonic acid, 300-800 parts of water, 1-15 parts of surfactant, 5-50 parts of modified bisphenol A type resin, 0.001-1 part of chain transfer agent and 0.01-1 part of initiator.

Preferably, the mass ratio of the sum of the usage amounts of the acrylamide, the sodium acrylate and the 2-acrylamide-2-methylpropanesulfonic acid to the usage amount of the modified bisphenol A type resin is (10-300): 1.

preferably, the surfactant is dodecyl dimethyl betaine and/or sodium dodecyl sulfate; the chain transfer agent is formate; and/or the initiator is a persulfate.

Preferably, in the step (3), the initiation temperature of the copolymerization reaction is 0-2 ℃, and/or the time of the copolymerization reaction is 2-4 h; and/or in the step (3), introducing nitrogen into the mixed solution to remove oxygen, and then sequentially adding the initiator and the chain transfer agent into the mixed solution under the protection of the nitrogen so as to enable the mixed solution to carry out copolymerization reaction under the action of the initiator and the chain transfer agent.

In a second aspect, the invention provides calcium and magnesium ion resistant polyacrylamide prepared by the preparation method of the first aspect.

Compared with the prior art, the invention at least has the following beneficial effects:

(1) the calcium and magnesium ion resistant polyacrylamide is obtained by reacting bisphenol A epoxy resin with acrylic acid to obtain epoxy acrylate monoester, then reacting the epoxy acrylate monoester with polyethylene glycol to obtain modified bisphenol A resin, and finally copolymerizing the modified bisphenol A resin with acrylamide, sodium acrylate and 2-acrylamide-2-methylpropanesulfonic acid. The invention adopts the modified bisphenol A type resin prepared by the specific method of the invention to modify polyacrylamide for the first time, and the invention discovers that the calcium magnesium ion resistant polyacrylamide obtained by modification has better viscosity and higher viscosity retention rate in calcium magnesium ion salt water compared with common polyacrylamide.

(2) Common polyacrylamide has certain defects, for example, the common polyacrylamide is easy to degrade when being placed at a higher temperature for a long time, so that the temperature resistance stability of the polyacrylamide is influenced; the viscosity of the ordinary polyacrylamide is influenced because the molecular chain of the ordinary polyacrylamide is difficult to curl and fully stretch in the high-calcium magnesium ion salt water; the invention discloses a method for preparing polyacrylamide, which is characterized in that a modified bisphenol A type resin is added to ensure that a polyacrylamide molecular chain has a large number of hydroxyl groups and benzene rings.

(3) The preparation process is simple and suitable for continuous production, the raw materials for synthesizing the modified bisphenol A type resin are wide in source and low in price, the consumption of the modified bisphenol A type resin is small, the modified bisphenol A type resin has a good modified tackifying effect on polyacrylamide in high calcium magnesium ion saline water (high salinity condition) under the condition of small consumption, and the production cost is greatly reduced.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. It is to be understood that the embodiments described are only a few embodiments of the present invention, and not all embodiments. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.

The invention provides a preparation method of calcium-magnesium ion resistant polyacrylamide in a first aspect, which comprises the following steps:

(1) carrying out esterification reaction on bisphenol A type epoxy resin and acrylic acid to obtain epoxy acrylate monoester; the bisphenol A type epoxy resin adopted by the invention is bisphenol A type epoxy resin with an epoxy value of 0.45-0.55, and can be directly purchased from the market; in the present invention, the esterification reaction of bisphenol a epoxy resin with acrylic acid to obtain epoxy acrylate monoester has the following reaction formula:

(2) carrying out ring-opening polymerization reaction on epoxy acrylate monoester and polyethylene glycol to obtain modified bisphenol A resin; in the present invention, the ring-opening polymerization reaction of epoxy acrylate monoester and polyethylene glycol to obtain modified bisphenol A type resin has the following reaction formula:

wherein:

R1、R2wherein n is determined by the molecular weight of selected bisphenol A epoxy resin and polyethylene glycol; in the present invention, the molecular weight of the polyethylene glycol is preferably 500, 1000 or 1500; the molecular weight of the bisphenol A type epoxy resin is preferably 3000-5000;

(3) uniformly mixing modified bisphenol A resin, acrylamide, sodium acrylate, 2-acrylamide-2-methylpropanesulfonic acid and a surfactant by using water to obtain a mixed solution, and then carrying out copolymerization reaction on the mixed solution under the action of an initiator and a chain transfer agent to obtain calcium-magnesium ion resistant polyacrylamide; the calcium-magnesium-ion-resistant polyacrylamide prepared by the invention is a modified bisphenol A type resin modified polyacrylamide with stable properties.

The calcium and magnesium ion resistant polyacrylamide is obtained by reacting bisphenol A epoxy resin with acrylic acid to obtain epoxy acrylate monoester, then reacting the epoxy acrylate monoester with polyethylene glycol to obtain modified bisphenol A resin, and finally copolymerizing the modified bisphenol A resin with acrylamide, sodium acrylate and 2-acrylamide-2-methylpropanesulfonic acid. The invention adopts the modified bisphenol A type resin prepared by the specific method to modify polyacrylamide for the first time, and the invention discovers that the calcium-magnesium ion resistant polyacrylamide obtained by modification has better viscosity and higher viscosity retention rate in calcium-magnesium ion salt water compared with common polyacrylamide; common polyacrylamide has certain defects, for example, the common polyacrylamide is easy to degrade when being placed at a higher temperature for a long time, so that the temperature resistance stability of the polyacrylamide is influenced; the viscosity of the ordinary polyacrylamide is influenced because the molecular chain of the ordinary polyacrylamide is difficult to curl and fully stretch in the high-calcium magnesium ion salt water; the invention discloses a method for preparing polyacrylamide, which is characterized in that a modified bisphenol A type resin is added to ensure that a polyacrylamide molecular chain has a large number of hydroxyl groups and benzene rings.

According to some preferred embodiments, after the step (3), the method further comprises the steps of drying and grinding the prepared calcium-magnesium ion resistant polyacrylamide in sequence; the invention has no special requirements on the conditions of drying and grinding, and the calcium-magnesium ion resistant polyacrylamide prepared in the step (3) is dried and ground to obtain calcium-magnesium ion resistant polyacrylamide fine powder; in some preferred embodiments, the drying is performed at 70 ℃; in some preferred embodiments, the fine powder of the calcium-magnesium resistant ionic polyacrylamide with the particle size of 60 meshes is obtained by grinding.

According to some preferred embodiments, the anti-calcium-magnesium ionic polyacrylamide is prepared with one or more of the following characteristics:

dissolving in water for no more than 30 min;

the apparent viscosity of the solution in 10wt% of magnesium chloride salt solution is more than 50 mPa.s, and the viscosity retention rate of the solution in 10wt% of magnesium chloride salt solution after 5 hours is more than 95%;

③ the apparent viscosity in 10wt% calcium chloride salt water is more than 40 mPa.s, and the viscosity retention rate in 10wt% calcium chloride salt water after 5h is more than 92%.

According to some preferred embodiments, in step (1), the mass ratio of the bisphenol a type epoxy resin to the acrylic acid is 1: (0.1 to 1.25) (e.g., 1:0.1, 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, 1:1.2, or 1: 1.25), and more preferably, in the step (1), the mass ratio of the bisphenol A-type epoxy resin to the acrylic acid is 1: (0.65-1.25); and/or in the step (2), the mass ratio of the epoxy acrylate monoester to the polyethylene glycol is 1: (0.25 to 1.5) (e.g., 1:0.25, 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, 1:1.2, 1:1.3, 1:1.4, or 1: 1.5), and more preferably, in the step (2), the mass ratio of the epoxy acrylate monoester to the polyethylene glycol is 1: (0.28 to 0.67); the present inventors have found that, in step (1), it is more preferable that the mass ratio of the bisphenol a type epoxy resin to the acrylic acid is 1: (0.65 to 1.25), and in the step (2), it is more preferable that the mass ratio of the epoxy acrylate monoester to the polyethylene glycol is 1: (0.28-0.67), so that more target products of modified bisphenol A type resin can be obtained.

According to some preferred embodiments, in step (1), the temperature of the esterification reaction is 50 to 120 ℃ (e.g., 50 ℃, 55 ℃, 60 ℃, 65 ℃, 70 ℃, 75 ℃, 80 ℃, 85 ℃, 90 ℃, 95 ℃, 100 ℃, 105 ℃, 110 ℃, 115 ℃ or 120 ℃), and the time of the esterification reaction is 1 to 5 hours (e.g., 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5 or 5 hours); and/or in the step (2), the temperature of the ring-opening polymerization reaction is 50-100 ℃ (for example, 50 ℃, 55 ℃, 60 ℃, 65 ℃, 70 ℃, 75 ℃, 80 ℃, 85 ℃, 90 ℃, 95 ℃ or 100 ℃), and the time of the ring-opening polymerization reaction is 0.5-3 h (for example, 0.5, 1, 1.5, 2, 2.5 or 3 h).

According to some specific embodiments, the modified bisphenol a type resin is prepared by: adding bisphenol A epoxy resin and acrylic acid into a three-neck flask provided with a stirrer, a reflux condenser and a thermometer, and reacting at 50-120 ℃ for 1-5 h to obtain epoxy acrylate monoester; and then reacting the epoxy acrylate monoester with polyethylene glycol at 50-100 ℃ for 0.5-3 h to obtain the modified bisphenol A epoxy resin.

The molecular weight of the polyethylene glycol used in the invention is not particularly required, preferably, the polyethylene glycol used is one or more of polyethylene glycol with the molecular weight of 500 to 1500, preferably, the polyethylene glycol is one or more of polyethylene glycol with the molecular weight of 500, polyethylene glycol with the molecular weight of 1000 and polyethylene glycol with the molecular weight of 1500; the polyethylene glycol with the molecular weight of 500, the polyethylene glycol with the molecular weight of 1000 and the polyethylene glycol with the molecular weight of 1500 in the invention can be directly purchased from the market.

According to some preferred embodiments, in step (3), acrylamide, sodium acrylate, 2-acrylamido-2-methylpropanesulfonic acid, water, a surfactant, a modified bisphenol a type resin, a chain transfer agent, and an initiator are used in the following amounts:

50 to 80 parts by weight (e.g., 50, 55, 60, 65, 70, 75 or 80 parts by weight) of acrylamide, 80 to 100 parts by weight (e.g., 80, 85, 90, 95 or 100 parts by weight) of sodium acrylate, 20 to 80 parts by weight (e.g., 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75 or 80 parts by weight) of 2-acrylamido-2-methylpropanesulfonic acid, 300 to 800 parts by weight (e.g., 300, 350, 400, 450, 500, 550, 600, 650, 700, 750 or 800 parts by weight) of water, 1 to 15 parts by weight (e.g., 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, 10, 10.5, 11, 11.5, 12, 12.5, 13, 13.5, 14, 14.5 or 15 parts by weight) of a modified resin (e.5, 25 to 15 parts by weight) (e.g., 20, 25, 20, 15 parts by weight) of bisphenol A type resin, 35. 40, 45, or 50 parts by weight), 0.001 to 1 part by weight (e.g., 0.001, 0.002, 0.003, 0.004, 0.005, 0.006, 0.007, 0.008, 0.009, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, or 1 part by weight) of a chain transfer agent and 0.01 to 1 part by weight (e.g., 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, or 1 part by weight) of an initiator.

In some more preferred embodiments, 50 to 60 parts by weight of acrylamide, 80 to 100 parts by weight of sodium acrylate, 30 to 50 parts by weight of 2-acrylamido-2-methylpropanesulfonic acid, 700 to 800 parts by weight of water, 5 to 15 parts by weight of a surfactant, 5 to 20 parts by weight of a modified bisphenol A type resin, 0.002 to 0.005 part by weight of a chain transfer agent, and 0.02 to 0.06 part by weight of an initiator; the invention discovers that the viscosity of the calcium magnesium ion resistant polyacrylamide in 10wt% calcium chloride and 10wt% magnesium chloride salt water can be adjusted by adjusting the using amount of the modified bisphenol A type resin; according to the invention, through a large number of creative experiments, the optimized dosage of each raw material for preparing the calcium-magnesium-ion-resistant polyacrylamide is obtained, and the invention finds that the dosage of each raw material for preparing the calcium-magnesium-ion-resistant polyacrylamide has the proper dosage proportion, so that the stable property is ensured, the good viscosity is realized in 10wt% calcium chloride and 10wt% magnesium chloride salt water, and the viscosity retention rate is high.

According to some preferred embodiments, the mass ratio of the sum of the amounts of the acrylamide, the sodium acrylate and the 2-acrylamido-2-methylpropanesulfonic acid to the amount of the modified bisphenol a-type resin is (10 to 300): 1 (e.g., 10:1, 15:1, 20:1, 25:1, 30:1, 35:1, 40:1, 45:1, 50:1, 55:1, 60:1, 65:1, 70:1, 75:1, 80:1, 85:1, 90:1, 100:1, 110:1, 120:1, 130:1, 140:1, 150:1, 160:1, 170:1, 180:1, 190:1, 200:1, 210:1, 220:1, 230:1, 240:1, 250:1, 260:1, 270:1, 280:1, 290:1, or 300: 1), more preferably (15-45): 1; in the present invention, it is more preferable that the mass ratio of the sum of the amounts of the acrylamide, the sodium acrylate and the 2-acrylamido-2-methylpropanesulfonic acid to the amount of the modified bisphenol a-type resin is (15 to 45): under the proper proportion, the modified bisphenol A type resin does not affect the molecular weight of the calcium-magnesium ion resistant polyacrylamide, and can increase the association of the calcium-magnesium ion resistant polyacrylamide molecules in the saline water, thereby increasing the viscosity of the calcium-magnesium ion resistant polyacrylamide in the saline water, so that the viscosity of the prepared calcium-magnesium ion resistant polyacrylamide in 10wt% calcium chloride and 10wt% magnesium chloride salt water can be further improved, and the viscosity retention rate of the prepared calcium-magnesium ion resistant polyacrylamide in 10wt% calcium chloride and 10wt% magnesium chloride salt water is higher for a long time.

According to some preferred embodiments, the surfactant is dodecyl dimethyl betaine and/or sodium dodecyl sulfate; the chain transfer agent is formate, preferably, the formate is sodium formate; and/or the initiator is a persulfate salt, preferably the persulfate salt is potassium persulfate.

According to some preferred embodiments, in step (3), the initiation temperature of the copolymerization is 0 to 2 ℃ and/or the time of the copolymerization is 2 to 4 hours (e.g., 2, 2.5, 3, 3.5, or 4 hours); and/or in the step (3), introducing nitrogen into the mixed solution to remove oxygen (for example, introducing nitrogen to remove oxygen for 20-40 min), and then sequentially adding the initiator and the chain transfer agent into the mixed solution under the protection of nitrogen so as to enable the mixed solution to carry out copolymerization reaction under the action of the initiator and the chain transfer agent; in the invention, after the initiator and the chain transfer agent are added, the temperature of the copolymerization reaction is naturally raised, the peak temperature of the natural temperature rise of the copolymerization reaction is 75-80 ℃, and the time for continuously carrying out the copolymerization reaction is preferably 2-4 h.

According to some specific embodiments, the step (3) is: uniformly mixing modified bisphenol A resin, acrylamide, sodium acrylate, 2-acrylamide-2-methylpropanesulfonic acid and a surfactant with water to obtain a mixed solution, respectively adjusting the temperature and the pH of the mixed solution to 0-2 ℃ and 7.0-7.2, introducing nitrogen into the mixed solution to remove oxygen for 20-40 min, sequentially adding an initiator and a chain transfer agent into the mixed solution under the protection of nitrogen to enable the mixed solution to carry out copolymerization under the action of the initiator and the chain transfer agent, continuously blowing nitrogen into the mixed solution added with the initiator and the chain transfer agent after copolymerization is started until the mixed solution becomes viscous, and stopping blowing the nitrogen; after the copolymerization reaction is continuously carried out for 2-4 hours, finishing the copolymerization reaction to obtain calcium-magnesium-ion-resistant polyacrylamide, and sequentially drying and grinding the calcium-magnesium-ion-resistant polyacrylamide; the present invention does not require any particular kind of pH adjuster and amount of pH adjuster to be used to adjust the pH of the mixed solution to 7.0 to 7.2, provided that the pH of the mixed solution can be adjusted to a target range.

In a second aspect, the invention provides calcium and magnesium ion resistant polyacrylamide prepared by the preparation method of the first aspect.

The invention will be further illustrated by way of example, but the scope of protection is not limited to these examples.

Example 1

Preparation of modified bisphenol A resin: adding 10g of bisphenol A epoxy resin into a three-neck flask provided with a stirrer, a reflux condenser and a thermometer, slowly adding 7g of acrylic acid, and reacting at 100 ℃ for 2h to obtain epoxy acrylic acid monoester; then 17g of epoxy acrylate monoester and 10g of polyethylene glycol with the molecular weight of 500 are reacted for 2 hours at 100 ℃ to obtain the modified bisphenol A type resin.

② preparation of calcium-magnesium ion resistant polyacrylamide: adding 60g of acrylamide, 100g of sodium acrylate, 50g of 2-acrylamide-2-methylpropanesulfonic acid, 775g of deionized water, 5g of dodecyl betaine and 10g of modified bisphenol A type resin into a beaker, uniformly mixing to obtain a mixed solution, adjusting the temperature and the pH of the mixed solution to 0-2 ℃ and 7.0-7.2 respectively, pouring the mixed solution into a reaction kettle (keeping the temperature of the mixed solution in the reaction kettle to be 0-2 ℃ before initiating copolymerization reaction), introducing nitrogen into the mixed solution to remove oxygen for 30min, sequentially adding 0.05g of initiator potassium persulfate and 0.003g of chain transfer agent sodium formate into the mixed solution under the protection of nitrogen so as to carry out natural heating copolymerization reaction of the mixed solution under the action of the initiator and the chain transfer agent, continuously blowing nitrogen into the mixed solution added with the initiator and the chain transfer agent until the mixed solution becomes viscous after copolymerization reaction starts, stopping blowing the nitrogen; in this embodiment, the peak temperature of the natural temperature rise of the copolymerization reaction is 78 ℃, the copolymerization reaction is terminated after the copolymerization reaction is continued for 3 hours, so as to obtain calcium-magnesium-ion-resistant polyacrylamide, and the calcium-magnesium-ion-resistant polyacrylamide (jelly) is taken out of the reaction kettle and then is sequentially dried and ground, so as to obtain calcium-magnesium-ion-resistant polyacrylamide fine powder.

Example 2

Preparation of modified bisphenol A resin: adding 10g of bisphenol A epoxy resin into a three-neck flask provided with a stirrer, a reflux condenser and a thermometer, slowly adding 11g of acrylic acid, and reacting at 80 ℃ for 3h to obtain epoxy acrylic acid monoester; then 21g of epoxy acrylate monoester and 12g of polyethylene glycol with the molecular weight of 1000 are reacted for 1.5h at 70 ℃ to obtain the modified bisphenol A type resin.

② preparation of calcium-magnesium ion resistant polyacrylamide: adding 60g of acrylamide, 100g of sodium acrylate, 50g of 2-acrylamide-2-methylpropanesulfonic acid, 775g of deionized water, 5g of sodium dodecyl sulfate and 10g of modified bisphenol A type resin into a beaker, uniformly mixing to obtain a mixed solution, adjusting the temperature and the pH of the mixed solution to 0-2 ℃ and 7.0-7.2 respectively, pouring the mixed solution into a reaction kettle (keeping the temperature of the mixed solution in the reaction kettle to be 0-2 ℃ before initiating copolymerization reaction), introducing nitrogen into the mixed solution to remove oxygen for 30min, sequentially adding 0.05g of initiator potassium persulfate and 0.003g of chain transfer agent sodium formate into the mixed solution under the protection of nitrogen so as to carry out natural temperature rise copolymerization reaction of the mixed solution under the action of the initiator and the chain transfer agent, continuously blowing nitrogen into the mixed solution added with the initiator and the chain transfer agent until the mixed solution becomes viscous after copolymerization reaction starts, stopping blowing the nitrogen; in this embodiment, the peak temperature of the natural temperature rise of the copolymerization reaction is 76 ℃, the copolymerization reaction is terminated after the copolymerization reaction is continued for 3 hours, so as to obtain calcium-magnesium-ion-resistant polyacrylamide, and the calcium-magnesium-ion-resistant polyacrylamide (jelly) is taken out of the reaction kettle and then is sequentially dried and ground, so as to obtain calcium-magnesium-ion-resistant polyacrylamide fine powder.

Example 3

Preparation of modified bisphenol A resin: adding 8g of bisphenol A epoxy resin into a three-neck flask provided with a stirrer, a reflux condenser and a thermometer, slowly adding 10g of acrylic acid, and reacting at 60 ℃ for 3h to obtain epoxy acrylic acid monoester; then 18g of epoxy acrylate monoester and 6g of polyethylene glycol with the molecular weight of 1500 are reacted for 1 hour at 70 ℃ to obtain the modified bisphenol A type resin.

② preparation of calcium-magnesium ion resistant polyacrylamide: adding 50g of acrylamide, 100g of sodium acrylate, 40g of 2-acrylamide-2-methylpropanesulfonic acid, 790g of deionized water, 10g of sodium dodecyl sulfate and 10g of modified bisphenol A type resin into a beaker, uniformly mixing to obtain a mixed solution, adjusting the temperature and the pH of the mixed solution to 0-2 ℃ and 7.0-7.2 respectively, pouring the mixed solution into a reaction kettle (keeping the temperature of the mixed solution in the reaction kettle to be 0-2 ℃ before initiating copolymerization reaction), introducing nitrogen into the mixed solution to remove oxygen for 30min, sequentially adding 0.05g of initiator potassium persulfate and 0.003g of sodium formate into the mixed solution under the protection of nitrogen so as to enable the mixed solution to carry out natural temperature rise copolymerization reaction under the action of the initiator and the chain transfer agent, continuously blowing nitrogen into the mixed solution added with the initiator and the chain transfer agent until the mixed solution becomes viscous after copolymerization reaction starts, stopping blowing the nitrogen; in this embodiment, the peak temperature of the natural temperature rise of the copolymerization reaction is 77 ℃, the copolymerization reaction is terminated after the copolymerization reaction is continued for 3 hours, so as to obtain calcium-magnesium-ion-resistant polyacrylamide, and the calcium-magnesium-ion-resistant polyacrylamide (jelly) is taken out of the reaction kettle and then is sequentially dried and ground, so as to obtain calcium-magnesium-ion-resistant polyacrylamide fine powder.

Example 4

Preparation of modified bisphenol A resin: adding 10g of bisphenol A epoxy resin into a three-neck flask provided with a stirrer, a reflux condenser and a thermometer, slowly adding 10g of acrylic acid, and reacting at 70 ℃ for 1h to obtain epoxy acrylic acid monoester; then 20g of epoxy acrylate monoester and 6g of polyethylene glycol with the molecular weight of 500 are reacted for 1.5h at 80 ℃ to obtain the modified bisphenol A type resin.

② preparation of calcium-magnesium ion resistant polyacrylamide: adding 60g of acrylamide, 100g of sodium acrylate, 30g of 2-acrylamide-2-methylpropanesulfonic acid, 795g of deionized water, 10g of sodium dodecyl sulfate and 5g of modified bisphenol A type resin into a beaker, uniformly mixing to obtain a mixed solution, adjusting the temperature and the pH of the mixed solution to 0-2 ℃ and 7.0-7.2 respectively, pouring the mixed solution into a reaction kettle (keeping the temperature of the mixed solution in the reaction kettle to be 0-2 ℃ before initiating copolymerization reaction), introducing nitrogen into the mixed solution to remove oxygen for 30min, sequentially adding 0.05g of initiator potassium persulfate and 0.003g of chain transfer agent sodium formate into the mixed solution under the protection of nitrogen so as to carry out natural temperature rise copolymerization reaction of the mixed solution under the action of the initiator and the chain transfer agent, continuously blowing nitrogen into the mixed solution added with the initiator and the chain transfer agent until the mixed solution becomes viscous after copolymerization reaction starts, stopping blowing the nitrogen; in this embodiment, the peak temperature of the natural temperature rise of the copolymerization reaction is 80 ℃, the copolymerization reaction is terminated after the copolymerization reaction is continued for 3 hours, so as to obtain calcium-magnesium-ion-resistant polyacrylamide, and the calcium-magnesium-ion-resistant polyacrylamide (jelly) is taken out of the reaction kettle and then is sequentially dried and ground, so as to obtain calcium-magnesium-ion-resistant polyacrylamide fine powder.

Example 5

Preparation of modified bisphenol A resin: adding 10g of bisphenol A epoxy resin into a three-neck flask provided with a stirrer, a reflux condenser and a thermometer, slowly adding 10g of acrylic acid, and reacting at 85 ℃ for 1h to obtain epoxy acrylic acid monoester; then 20g of epoxy acrylate monoester and 8g of polyethylene glycol with the molecular weight of 1000 are reacted for 1 hour at 85 ℃ to obtain the modified bisphenol A type resin.

② preparation of calcium-magnesium ion resistant polyacrylamide: adding 50g of acrylamide, 100g of sodium acrylate, 40g of 2-acrylamide-2-methylpropanesulfonic acid, 785g of deionized water, 15g of sodium dodecyl sulfate and 10g of modified bisphenol A type resin into a beaker, uniformly mixing to obtain a mixed solution, adjusting the temperature and the pH of the mixed solution to 0-2 ℃ and 7.0-7.2 respectively, pouring the mixed solution into a reaction kettle (keeping the temperature of the mixed solution in the reaction kettle to be 0-2 ℃ before initiating copolymerization reaction), introducing nitrogen into the mixed solution to remove oxygen for 30min, sequentially adding 0.05g of initiator potassium persulfate and 0.003g of chain transfer agent sodium formate into the mixed solution under the protection of nitrogen so as to carry out natural temperature rise copolymerization reaction of the mixed solution under the action of the initiator and the chain transfer agent, continuously blowing nitrogen into the mixed solution added with the initiator and the chain transfer agent until the mixed solution becomes viscous after copolymerization reaction starts, stopping blowing the nitrogen; in this embodiment, the peak temperature of the natural temperature rise of the copolymerization reaction is 79 ℃, the copolymerization reaction is terminated after the copolymerization reaction is continued for 3 hours, so as to obtain calcium-magnesium-ion-resistant polyacrylamide, and the calcium-magnesium-ion-resistant polyacrylamide (jelly) is taken out of the reaction kettle and then is sequentially dried and ground, so as to obtain calcium-magnesium-ion-resistant polyacrylamide fine powder.

Example 6

Preparation of modified bisphenol A resin: adding 10g of bisphenol A epoxy resin into a three-neck flask provided with a stirrer, a reflux condenser and a thermometer, slowly adding 10g of acrylic acid, and reacting at 65 ℃ for 3h to obtain epoxy acrylic acid monoester; then 20g of epoxy acrylate monoester and 8g of polyethylene glycol with the molecular weight of 1500 are reacted for 1 hour at 85 ℃ to obtain the modified bisphenol A resin.

② preparation of calcium-magnesium ion resistant polyacrylamide: adding 50g of acrylamide, 100g of sodium acrylate, 50g of 2-acrylamide-2-methylpropanesulfonic acid, 775g of deionized water, 15g of sodium dodecyl sulfate and 10g of modified bisphenol A type resin into a beaker, uniformly mixing to obtain a mixed solution, adjusting the temperature and the pH of the mixed solution to 0-2 ℃ and 7.0-7.2 respectively, pouring the mixed solution into a reaction kettle (keeping the temperature of the mixed solution in the reaction kettle to be 0-2 ℃ before initiating copolymerization reaction), introducing nitrogen into the mixed solution to remove oxygen for 30min, sequentially adding 0.05g of initiator potassium persulfate and 0.003g of chain transfer agent sodium formate into the mixed solution under the protection of nitrogen so as to carry out natural temperature rise copolymerization reaction of the mixed solution under the action of the initiator and the chain transfer agent, continuously blowing nitrogen into the mixed solution added with the initiator and the chain transfer agent until the mixed solution becomes viscous after copolymerization reaction starts, stopping blowing the nitrogen; in this embodiment, the peak temperature of the natural temperature rise of the copolymerization reaction is 80 ℃, the copolymerization reaction is terminated after the copolymerization reaction is continued for 3 hours, so as to obtain calcium-magnesium-ion-resistant polyacrylamide, and the calcium-magnesium-ion-resistant polyacrylamide (jelly) is taken out of the reaction kettle and then is sequentially dried and ground, so as to obtain calcium-magnesium-ion-resistant polyacrylamide fine powder.

Example 7

Preparation of modified bisphenol A resin: adding 6g of bisphenol A epoxy resin into a three-neck flask provided with a stirrer, a reflux condenser and a thermometer, slowly adding 10g of acrylic acid, and reacting at 100 ℃ for 2h to obtain epoxy acrylic acid monoester; then 16g of epoxy acrylate monoester and 13g of polyethylene glycol with the molecular weight of 500 are reacted for 2 hours at 100 ℃ to obtain the modified bisphenol A type resin.

② preparation of calcium-magnesium ion resistant polyacrylamide: adding 35g of acrylamide, 55g of sodium acrylate, 30g of 2-acrylamide-2-methylpropanesulfonic acid, 775g of deionized water, 5g of dodecyl betaine and 10g of modified bisphenol A type resin into a beaker, uniformly mixing to obtain a mixed solution, adjusting the temperature and the pH of the mixed solution to 0-2 ℃ and 7.0-7.2 respectively, pouring the mixed solution into a reaction kettle (keeping the temperature of the mixed solution in the reaction kettle to be 0-2 ℃ before initiating copolymerization reaction), introducing nitrogen into the mixed solution to remove oxygen for 30min, sequentially adding 0.05g of initiator potassium persulfate and 0.003g of chain transfer agent sodium formate into the mixed solution under the protection of nitrogen so as to carry out natural heating copolymerization reaction of the mixed solution under the action of the initiator and the chain transfer agent, continuously blowing nitrogen into the mixed solution added with the initiator and the chain transfer agent until the mixed solution becomes viscous after copolymerization reaction starts, stopping blowing the nitrogen; in this embodiment, the peak temperature of the natural temperature rise of the copolymerization reaction is 77 ℃, the copolymerization reaction is terminated after the copolymerization reaction is continued for 3 hours, so as to obtain calcium-magnesium-ion-resistant polyacrylamide, and the calcium-magnesium-ion-resistant polyacrylamide (jelly) is taken out of the reaction kettle and then is sequentially dried and ground, so as to obtain calcium-magnesium-ion-resistant polyacrylamide fine powder.

Example 8

Preparation of modified bisphenol A resin: adding 20g of bisphenol A epoxy resin into a three-neck flask provided with a stirrer, a reflux condenser and a thermometer, slowly adding 10g of acrylic acid, and reacting at 100 ℃ for 2h to obtain epoxy acrylic acid monoester; then 30g of epoxy acrylate monoester and 7.5g of polyethylene glycol with the molecular weight of 500 are reacted for 2 hours at 100 ℃ to obtain the modified bisphenol A type resin.

② preparation of calcium-magnesium ion resistant polyacrylamide: adding 80g of acrylamide, 100g of sodium acrylate, 70g of 2-acrylamide-2-methylpropanesulfonic acid, 775g of deionized water, 5g of dodecyl betaine and 5g of modified bisphenol A type resin into a beaker, uniformly mixing to obtain a mixed solution, adjusting the temperature and the pH of the mixed solution to 0-2 ℃ and 7.0-7.2 respectively, pouring the mixed solution into a reaction kettle (keeping the temperature of the mixed solution in the reaction kettle to be 0-2 ℃ before initiating copolymerization reaction), introducing nitrogen into the mixed solution to remove oxygen for 30min, sequentially adding 0.05g of initiator potassium persulfate and 0.003g of chain transfer agent sodium formate into the mixed solution under the protection of nitrogen so as to carry out natural heating copolymerization reaction of the mixed solution under the action of the initiator and the chain transfer agent, continuously blowing nitrogen into the mixed solution added with the initiator and the chain transfer agent until the mixed solution becomes viscous after copolymerization reaction starts, stopping blowing the nitrogen; in this embodiment, the peak temperature of the natural temperature rise of the copolymerization reaction is 78 ℃, the copolymerization reaction is terminated after the copolymerization reaction is continued for 3 hours, so as to obtain calcium-magnesium-ion-resistant polyacrylamide, and the calcium-magnesium-ion-resistant polyacrylamide (jelly) is taken out of the reaction kettle and then is sequentially dried and ground, so as to obtain calcium-magnesium-ion-resistant polyacrylamide fine powder.

Comparative example 1

Preparing modified polyacrylamide: adding 60g of acrylamide, 100g of sodium acrylate, 50g of 2-acrylamide-2-methylpropanesulfonic acid, 775g of deionized water and 5g of dodecyl betaine into a beaker, uniformly mixing to obtain a mixed solution, adjusting the temperature and the pH of the mixed solution to 0-2 ℃ and 7.0-7.2 respectively, pouring the mixed solution into a reaction kettle (keeping the temperature of the mixed solution in the reaction kettle at 0-2 ℃ before initiating copolymerization reaction), introducing nitrogen into the mixed solution to remove oxygen for 30min, sequentially adding 0.05g of initiator potassium persulfate and 0.003g of chain transfer agent sodium formate into the mixed solution under the protection of nitrogen so as to perform natural temperature rise copolymerization reaction under the action of the initiator and the chain transfer agent, continuously blowing nitrogen into the mixed solution added with the initiator and the chain transfer agent after the copolymerization reaction is started until the mixed solution becomes viscous, stopping blowing the nitrogen; in the comparative example, the peak temperature of the natural temperature rise of the copolymerization reaction was 79 ℃, the copolymerization reaction was terminated after the copolymerization reaction was continued for 3 hours to obtain modified polyacrylamide, and the modified polyacrylamide (jelly) was taken out from the reaction kettle and then dried and ground in sequence to obtain modified polyacrylamide fine powder.

Comparative example 2

Preparation of modified bisphenol A epoxy acrylate: adding 47g of bisphenol A epoxy resin and 14g of polyethylene glycol (the molecular weight of the polyethylene glycol is 500) into a reaction container, adding 0.24g of tetrabutylammonium bromide serving as a catalyst and 0.11g of p-hydroxyanisole serving as a polymerization inhibitor, stirring, heating to the reaction temperature of 120 ℃, reacting for 2 hours, adding 18g of acrylic acid, and then preserving heat at the temperature of 120 ℃ for 4 hours to obtain the modified bisphenol A epoxy acrylate.

Preparing modified polyacrylamide (abbreviated as modified polyacrylamide) modified by modified bisphenol A epoxy acrylate: adding 60g of acrylamide, 100g of sodium acrylate, 50g of 2-acrylamide-2-methylpropanesulfonic acid, 775g of deionized water, 5g of dodecyl betaine and 10g of modified bisphenol A epoxy acrylate into a beaker, uniformly mixing to obtain a mixed solution, adjusting the temperature and the pH of the mixed solution to 0-2 ℃ and 7.0-7.2 respectively, pouring the mixed solution into a reaction kettle (keeping the temperature of the mixed solution in the reaction kettle to be 0-2 ℃ before initiating copolymerization reaction), introducing nitrogen into the mixed solution to remove oxygen for 30min, sequentially adding 0.05g of initiator potassium persulfate and 0.003g of chain transfer agent sodium formate into the mixed solution under the protection of nitrogen so as to carry out natural heating copolymerization reaction of the mixed solution under the action of the initiator and the chain transfer agent, continuously blowing nitrogen into the mixed solution added with the initiator and the chain transfer agent until the mixed solution becomes viscous after copolymerization reaction starts, stopping blowing the nitrogen; in the comparative example, the peak temperature of the natural temperature rise of the copolymerization reaction was 78 ℃, the copolymerization reaction was terminated after the copolymerization reaction was continued for 3 hours to obtain modified polyacrylamide, and the modified polyacrylamide (jelly) was taken out from the reaction kettle and then dried and ground in sequence to obtain modified polyacrylamide fine powder.

Evaluation of Performance

The polymer products prepared in examples 1 to 8 and comparative examples 1 to 2 were added to 10wt% magnesium chloride solution and 10wt% calcium chloride solution, respectively, to prepare 0.3wt% polymer solution, and after each polymer solution was allowed to stand at 30 ℃ for 1 hour and 30 ℃ for 5 hours, the polymer solution was allowed to stand at 30 ℃ and 100r/min (i.e., the corresponding shear rate was 170 s)-1) The apparent viscosity was measured under the conditions shown in Table 1. In the invention, the 10wt% magnesium chloride solution refers to a magnesium chloride aqueous solution with the mass percentage of magnesium chloride of 10%, wherein the concentration of magnesium ions is 11822 mg/L; the 10wt% calcium chloride solution refers to a 10wt% calcium chloride aqueous solution, wherein the concentration of calcium ions is 36036 mg/L.

Table 1: apparent viscosity of the polymer products obtained in examples 1 to 8 and comparative examples 1 to 2 in 10wt% magnesium chloride solution and 10wt% calcium chloride solution.

As can be seen from the data in Table 1, the calcium-magnesium ion resistant polyacrylamide prepared by the invention is slightly affected by calcium and magnesium ions, has good viscosity in 10wt% calcium chloride and 10wt% magnesium chloride salt water, and has high viscosity retention rate; the apparent viscosity of the calcium-magnesium-ion-resistant polyacrylamide prepared in the embodiments 1-6 of the invention in 10wt% of magnesium chloride salt water is more than 50mPa · s, and the viscosity retention rate after 5 hours in 10wt% of magnesium chloride salt water is more than 95%, wherein the viscosity retention rate refers to the ratio of the apparent viscosity of the calcium-magnesium-ion-resistant polyacrylamide polymer product prepared by the invention after standing in 10wt% of magnesium chloride salt water for 5 hours to the apparent viscosity after standing in 10wt% of magnesium chloride salt water for 1 hour; the apparent viscosity of the calcium-magnesium-ion-resistant polyacrylamide prepared in the embodiments 1-6 of the invention in 10wt% calcium chloride salt water is more than 40mPa · s, and the viscosity retention rate in 10wt% calcium chloride salt water after 5 hours is more than 92%, wherein the viscosity retention rate refers to the ratio of the apparent viscosity of the calcium-magnesium-ion-resistant polyacrylamide polymer product prepared in the invention after standing in 10wt% calcium chloride salt water for 5 hours to the apparent viscosity of the calcium-magnesium-ion-resistant polyacrylamide polymer product after standing in 10wt% calcium chloride salt water for 1 hour.

The invention has not been described in detail and is in part known to those of skill in the art.

Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.

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