Preparation method of quick dispersion type polymer thickening agent

Abstract

The application discloses a preparation method of a fast dispersion type polymer thickening agent, and comprises the following steps: a) adding mixed organic solvents, an alpha, beta-unsaturated monomer, an inorganic dispersant, an organic dispersant, a crosslinking agent and an initiator into a reaction container for reaction under the protection of an inert atmosphere; b) supplementing mixed organic solvents into the reaction system for dilution; c) supplementing an initiator into the diluted reaction system for continuous reaction; d) obtaining a crude product through spray drying after the reaction is completed; and e) obtaining a target particle size product after the crude product is crushed, ball milled and sieved. The polymer prepared by the method has small particle size, uniform particle size distribution and large bulk density, can be quickly dispersed in water, can be quickly thickened after being neutralized by an alkali, and the obtained hydrogel has excellent viscosity and light transmission performance.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of new material preparation and thickening agent, and particularly relates to a preparation method of a fast-dispersing polymer thickening agent. BACKGROUND

[0002] At present, the main thickening agent in the market is α, β-unsaturated carboxylic acid polymer thickening agent, especially the cross-linked polyacrylic acid or cross-linked polyacrylic acid (ester) copolymer represented by carbomer resin, which is widely used in daily chemicals, medical and health care and personal care products and other fields. Such polymer thickening agent in the market is mostly in the form of powder, which can exhibit excellent thickening property, improve the thixotropy of the coagulation system and show clear transparency after being neutralized by an alkaline neutralizing agent after being dispersed in water.

[0003] However, the chemical structure of the α, β-unsaturated carboxylic acid polymer thickening agent represented by carbomer resin generally contains a carboxylic acid group, which has strong hydrophilicity. If it is directly and continuously stirred in water, it will quickly combine with water to form a solvent protective film, which will cover the polymer in the form of a block, so that a thickening agent powder block is formed on the water surface, and the inside is difficult to be infiltrated. At this time, the dispersion speed of the thickening agent completely depends on the penetration speed of the solvent into the protective film, and the rapid dispersion of the thickening agent cannot be achieved, and even part of the thickening agent cannot be dispersed. At present, in industrial production, high-speed shearing and homogenization are often used to accelerate the dispersion rate of the thickening agent in water, but such polymer dispersion system will be damaged under the action of high shearing rate, resulting in permanent loss of viscosity.

[0004] At present, the common method for improving the dispersion rate of such polymer thickening agent in water is to introduce a hydrophobic monomer, that is, to use long-chain acrylate or long-chain alkyl acrylate monomer to participate in copolymerization, so as to introduce a long-chain alkyl hydrophobic structure on the polymer macromolecular chain, so that the polymer thickening agent cannot form a solvent film protective layer when it is dispersed in water, and rapid dispersion is achieved. As described in patent CN104861104B, a fast-wetting carboxylic acid copolymer thickening agent is disclosed, which uses a segmented feeding process, controls the rate, and adds the material in sections, so that the obtained polymer thickening agent product has high bulk density, fast dispersion ability in water, and excellent viscosity and transparency. However, the introduction of expensive monomers such as long-chain acrylate or long-chain alkyl acrylate undoubtedly increases the cost of industrial production, and more importantly, the reactivity of such long-chain hydrophobic monomer and the original hydrophilic monomer of the polymer thickening agent often differs greatly, which increases the requirements for reaction conditions and industrial equipment in actual production, and increases the production difficulty and cost.

[0005] Another method to improve the dispersion rate of such polymer thickening agent in water is to increase the bulk density of the polymer, so that it has completed sedimentation when the surface solvent film has not yet been formed during the dispersion process in water, greatly accelerating its dispersion rate and internal swelling rate. As described in patent CN114904007A, a method for increasing the bulk density of carbomer is disclosed, which forms particles from powder by using linear polyacrylic acid adhesive solution to soak the polymer thickening agent or stirring, swinging, rolling granulation, so as to realize high bulk density and fast dispersion of carbomer, and does not affect the performance of the original resin. However, the linear polyacrylic acid adhesive used in this process will also increase the cost of raw materials, and this part of the adhesive will also be mixed into the final polymer thickening agent product. SUMMARY

[0006] To solve the above problems, the present application provides a preparation method of a fast dispersion type polymer thickening agent, which has small particle size and uniform particle size distribution, high bulk density, can realize fast dispersion in water, and can quickly thicken after being neutralized by alkali, while the obtained hydrogel has excellent viscosity and light transmission performance.

[0007] The technical scheme adopted to achieve the purpose of the present application is:

[0008] A preparation method of a fast dispersion type polymer thickening agent, comprising the following steps:

[0009] a) adding mixed organic solvent A, α, β-unsaturated monomer, inorganic dispersant, organic dispersant, crosslinking agent and initiator into a reaction container under the protection of inert atmosphere and reacting;

[0010] b) adding mixed organic solvent B to the reaction system for dilution;

[0011] c) adding initiator to the diluted reaction system and continuing the reaction;

[0012] d) after the reaction is completed, obtaining a crude product by spray drying;

[0013] e) obtaining a target particle size product after crushing, ball milling and sieving of the crude product;

[0014] In the above preparation method of the fast dispersion type polymer thickening agent, the whole reaction process is carried out under the protection of inert atmosphere, and in the specific embodiment of the present application, the inert atmosphere is nitrogen.

[0015] In the above preparation method of the fast dispersion type polymer thickening agent, the whole reaction process is carried out under the protection of inert atmosphere, and in the specific embodiment of the present application, the inert atmosphere is nitrogen.

[0016] In the preparation method of the fast dispersion type polymer thickening agent, the time for adding the mixed organic solvent in step b) is when the precipitation appears in the reaction system, and at this time, the reaction rate should be relatively fast. In the process of free radical precipitation polymerization, the macromolecular chain grows to a certain extent and precipitates from the solvent. The purpose of adding the mixed organic solvent to dilute the reaction system is to reduce the monomer concentration in the reaction system and the reaction rate, so that the macromolecular chain growth rate is relatively slow, the product particle size is uniform, and the product particle size is too large due to the too fast reaction rate.

[0017] In the preparation method of the fast dispersion type polymer thickening agent, the time for adding the mixed organic solvent in step b) is when the precipitation appears in the reaction system, and at this time, the reaction rate should be relatively fast. In the process of free radical precipitation polymerization, the macromolecular chain grows to a certain extent and precipitates from the solvent. The purpose of adding the mixed organic solvent to dilute the reaction system is to reduce the monomer concentration in the reaction system and the reaction rate, so that the macromolecular chain growth rate is relatively slow, the product particle size is uniform, and the product particle size is too large due to the too fast reaction rate.

[0018] In the preparation method of the fast dispersion type polymer thickening agent, the mass of the mixed organic solvent B added in step b) is 50%-150% of the mass of the mixed organic solvent A in step a).

[0019] In the preparation method of the fast dispersion type polymer thickening agent, the mass ratio of the polar organic solvent to the non-polar organic solvent in the mixed organic solvent A and / or the mixed organic solvent B is 2:8-8:2.

[0020] Further, the polar organic solvent is one or more of acetic acid, N,N-dimethylformamide, N,N-dimethyl sulfoxide, ethyl acetate and acetone.

[0021] Further, the non-polar organic solvent is one or more of toluene, cyclohexane and dichloromethane.

[0022] In the preparation method of the fast dispersion type polymer thickening agent, the formula of the mixed organic solvent A and the mixed organic solvent B can be the same or different, and preferably the formula of the mixed organic solvent A and the mixed organic solvent B is the same. The formula of the mixed organic solvent includes the types of solvents and the ratio of the solvents. In a specific embodiment, in order to facilitate operation, the formula of the mixed organic solvent A and the mixed organic solvent B is preferably the same.

[0023] In the preparation method of the fast dispersion type polymer thickening agent, the α,β-unsaturated monomer is one or more of acrylic acid, methacrylic acid, maleic acid, N-vinyl pyrrolidone and acrylamide.

[0024] Further, the mass of the α,β-unsaturated monomer is 5%-30% of the mass of the mixed organic solvent A in step a).

[0025] In the preparation method of the fast dispersion type polymer thickening agent, the inorganic dispersant is one or more of potassium carbonate, sodium carbonate, calcium carbonate, calcium chloride, sodium chloride and potassium chloride.

[0026] Further, the mass of the inorganic dispersant is 0.1%-5% of the total mass of the α, β-unsaturated monomer.

[0027] In the preparation method of the fast dispersion type polymer thickening agent, the organic dispersant is one or more of sorbitan laurate, sorbitan monooleate, polyoxyethylene sorbitan laurate, polyoxyethylene sorbitan stearate and hydroxyethyl cellulose.

[0028] Further, the mass of the organic dispersant is 0.1%-5% of the total mass of the α, β-unsaturated monomer.

[0029] In the preparation method of the fast dispersion type polymer thickening agent, the crosslinking agent is one or more of allyl sucrose ether, ethylene glycol dimethacrylate, pentaerythritol triallyl ether and pentaerythritol triacrylate.

[0030] Further, the mass of the crosslinking agent is 0.1%-5% of the total mass of the α, β-unsaturated monomer.

[0031] In the preparation method of the fast dispersion type polymer thickening agent, the initiator of step a) or c) is one or more of dodecanoyl peroxide, benzoyl peroxide, methyl ethyl ketone peroxide, azobisisobutyronitrile, azobisisovaleronitrile and azobisisoheptonitrile.

[0032] Further, the mass of the initiator of step a) or c) is 0.1%-3% of the total mass of the α, β-unsaturated monomer.

[0033] Further, the initiator used in step a) and step c) is of the same type and has the same mass.

[0034] In the preparation method of the fast dispersion type polymer thickening agent, the reaction temperature of step a) and c) is 40-90°C.

[0035] Further, the reaction temperature of step a) and c) is the same.

[0036] In the preparation method of the fast dispersion type polymer thickening agent, the reaction time of step c) is 2-4h. In most cases, the reaction continues for about 2-4h, and the monomer in the system is basically completely reacted. The additional initiator is used to ensure that the α, β-unsaturated monomer can be as completely reacted as possible. The initiator added at the beginning may be consumed completely in the middle and later stages, and therefore, the additional initiator can improve the conversion rate of the α, β-unsaturated monomer.

[0037] In the preparation method of the fast dispersion type polymer thickening agent, the particle size distribution of the target particle size product is 0.1-10 μm.

[0038] In the preparation method of the fast dispersion type polymer thickening agent, the bulk density of the target particle size product is 0.5-0.8 g / ml.

[0039] Compared with the prior art, the present application has the following beneficial effects:

[0040] (1) The preparation method of the fast dispersion type polymer thickening agent in the present application dilutes the macromolecular chain growth rate by mixing organic solvent during polymerization, so as to reduce the product particle size and increase the bulk density.

[0041] (2) The preparation method of the fast dispersion type polymer thickening agent in the present application does not use other hydrophobic monomers or other binders for granulation, and does not introduce other materials, so as not to affect the performance of the original polymer thickening agent, save the production cost, and reduce the risk of poor process consistency.

[0042] (3) The preparation method of the fast dispersion type polymer thickening agent in the present application obtains the target product through crushing, high-speed ball milling and screening, and the obtained product has small particle size, uniform particle size distribution and large bulk density, and can realize fast dispersion in water. DETAILED DESCRIPTION

[0043] The technical solutions of the present application will be described clearly and completely in combination with specific embodiments. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0044] Unless otherwise defined, the technical terms used in the following embodiments have the same meanings as generally understood by those skilled in the art to which the present application belongs. The test reagents used in the following embodiments, unless otherwise specified, are all conventional biochemical reagents; and the experimental methods, unless otherwise specified, are all conventional methods.

[0045] Test method 1: bulk density test

[0046] The sample is loaded into a dry and clean 100 mL measuring cylinder, gently filled to the top, sealed with plastic wrap, tightly tied and weighed. The measuring cylinder is placed on the tap density tester and vibrated at a frequency of 250 times per minute for 6000 times, the volume of the sample in the measuring cylinder is read, and the bulk density of the sample is calculated according to the volume and mass of the sample.

[0047] Test method 2: particle size and particle size distribution test

[0048] Accurately weigh 1.0 g of sample into a 1000 mL beaker, add 500 g of cyclohexane, mix thoroughly using magnetic stirring at 25 °C for 30 minutes, then determine the particle size and particle size distribution of the sample using a Mettler Toledo Easy Viewer 400 online particle size analyzer, and record the particle sizes at which 10%, 50%, and 90% of the particle size distribution is below, denoted as DV10, DV50, and DV90, respectively.

[0049] Test Method 3: Dispersion Time Test at 0.5% Concentration

[0050] Accurately weigh 497.5 g of water into a 1000 mL beaker, and place it in a 25 °C constant temperature box. Under static conditions, quickly and evenly sprinkle 2.5 g of sample onto the surface of the water, and start timing. When the sample has completely settled, stop timing.

[0051] Test Method 4: Viscosity Test at 0.5% Concentration

[0052] Accurately weigh 497.5 g of water into a 1000 mL beaker, and place it in a 25 °C constant temperature box. Under static conditions, quickly and evenly sprinkle 2.5 g of sample onto the surface of the water. After the sample has completely settled, add 4-5 g of 18% mass concentration sodium hydroxide aqueous solution to the solution under stirring to neutralize the sample, and adjust the pH of the resulting hydrogel to 7.0-7.8. Then transfer the hydrogel to a centrifuge tube, and centrifuge at 5000 rpm for 30 min to defoam. After centrifugation, transfer the solution to a beaker, and determine the viscosity of the solution using a Brookfield DV2TRV rotary viscometer at 20 rpm at 25 °C.

[0053] Test Method 5: Transmittance Test at 0.5% Concentration

[0054] Take the hydrogel after centrifugation in Test Method 4, and place it in a 1 mL UV spectrophotometric cuvette. Using water as a reference, determine the transmittance of the hydrogel at 420 nm using a Shimadzu UV-1800 UV spectrophotometer at 25 °C.

[0055] Example 1

[0056] Into a four-necked flask, 200 g of acetic acid, 800 g of toluene, 50 g of methacrylic acid, 2.5 g of potassium carbonate, 2.5 g of sorbitan laurate, 1.5 g of dodecanoyl peroxide and 2.5 g of allyl sucrose ether were sequentially added, and the mixture was mechanically stirred under nitrogen protection, heated to 60°C, and reacted until the system began to become turbid. Then, 200 g of a mixed solution of acetic acid and toluene was added to the reaction system under nitrogen protection, and 1.5 g of dodecanoyl peroxide was added to the reaction system and the reaction was continued for 2 hours. The reaction temperature was maintained at 60°C. After the reaction was completed, the product was spray dried, crushed, high-speed ball milled, and sieved through a 500-1000 mesh sieve to obtain the final product. The obtained product was tested for bulk density according to Test Method 1, particle size and particle size distribution according to Test Method 2, dispersion time according to Test Method 3, viscosity and light transmittance at a concentration of 0.5% according to Test Method 4 and Test Method 5, and the results are shown in Table 1.

[0057] Example 2

[0058] Into a four-necked flask, 400 g of N,N-dimethylformamide, 600 g of cyclohexane, 300 g of acrylic acid, 0.3 g of sodium carbonate, 0.3 g of sorbitan monooleate, 0.3 g of benzoyl peroxide and 0.3 g of ethylene glycol dimethacrylate were sequentially added, and the mixture was mechanically stirred under nitrogen protection, heated to 90°C, and reacted until the system began to become turbid. Then, 400 g of a mixed solution of N,N-dimethylformamide and cyclohexane was added to the reaction system under nitrogen protection, and 0.3 g of benzoyl peroxide was added to the reaction system and the reaction was continued for 2 hours. The reaction temperature was maintained at 90°C. After the reaction was completed, the product was spray dried, crushed, high-speed ball milled, and sieved through a 500-1000 mesh sieve to obtain the final product. The obtained product was tested for bulk density according to Test Method 1, particle size and particle size distribution according to Test Method 2, dispersion time according to Test Method 3, viscosity and light transmittance at a concentration of 0.5% according to Test Method 4 and Test Method 5, and the results are shown in Table 1.

[0059] Example 3

[0060] Into a four-necked flask, 500 g of N,N-dimethyl sulfoxide, 500 g of dichloromethane, 200 g of maleic acid, 2 g of calcium carbonate, 3 g of polyoxyethylene sorbitan laurate, 2 g of azobisisoheptanenitrile, and 3 g of pentaerythritol triacrylate were sequentially added, and the mixture was mechanically stirred under nitrogen while being slowly heated to 40°C to react until the system began to become turbid. Then, 500 g of a mixed solution of N,N-dimethyl sulfoxide and dichloromethane was added to the reaction system under nitrogen, followed by the addition of 2 g of azobisisoheptanenitrile to the reaction system, and the reaction was continued for 2 hours while maintaining the reaction temperature at 40°C. After the completion of the reaction, the product was spray-dried, and the final product was obtained after pulverization, high-speed ball milling, and 500-1000 mesh sieving. The obtained product was subjected to the bulk density test according to Test Method 1, the particle size and particle size distribution test according to Test Method 2, the dispersion time test according to Test Method 3, the viscosity and light transmittance test at a concentration of 0.5% according to Test Method 4 and Test Method 5, and the results are shown in Table 1.

[0061] Example 4

[0062] Into a four-necked flask, 800 g of acetone, 200 g of dichloromethane, 200 g of methacrylic acid, 100 g of N-vinylpyrrolidone, 3 g of sodium chloride, 3 g of hydroxyethyl cellulose, 2 g of azobisisobutyronitrile, and 6 g of pentaerythritol triallyl ether were sequentially added, and the mixture was mechanically stirred under nitrogen while being slowly heated to 65°C to react until the system began to become turbid. Then, 800 g of a mixed solution of acetone and dichloromethane was added to the reaction system under nitrogen, followed by the addition of 2 g of azobisisobutyronitrile to the reaction system, and the reaction was continued for 2 hours while maintaining the reaction temperature at 65°C. After the completion of the reaction, the product was spray-dried, and the final product was obtained after pulverization, high-speed ball milling, and 500-1000 mesh sieving. The obtained product was subjected to the bulk density test according to Test Method 1, the particle size and particle size distribution test according to Test Method 2, the dispersion time test according to Test Method 3, the viscosity and light transmittance test at a concentration of 0.5% according to Test Method 4 and Test Method 5, and the results are shown in Table 1.

[0063] Example 5

[0064] A four-necked flask was charged with 700 g of ethyl acetate, 300 g of dichloromethane, 200 g of methacrylic acid, 100 g of acrylamide, 4 g of potassium chloride, 3 g of polyoxyethylene sorbitan stearate, 1 g of azobisisovaleronitrile, and 5 g of pentaerythritol triallyl ether, and the mixture was stirred mechanically under nitrogen while being heated slowly to 70°C. When the system began to become turbid, a mixed solution of 700 g of ethyl acetate and 300 g of dichloromethane was added to the reaction system under nitrogen, and then 1 g of azobisisovaleronitrile was added to the reaction system and the reaction was continued for 2 hours while maintaining the temperature at 70°C. After the reaction was completed, the product was spray-dried, pulverized, ball-milled at high speed, and sieved through a 500-1000 mesh screen to obtain the final product. The final product was subjected to the bulk density test according to Test Method 1, the particle size and particle size distribution test according to Test Method 2, the dispersion time test according to Test Method 3, the viscosity and light transmittance test at a concentration of 0.5% according to Test Method 4 and Test Method 5, and the results are shown in Table 1.

[0065] Example 6

[0066] A four-necked flask was charged with 700 g of ethyl acetate, 300 g of dichloromethane, 200 g of methacrylic acid, 100 g of acrylamide, 4 g of potassium chloride, 3 g of polyoxyethylene sorbitan stearate, 1 g of azobisisovaleronitrile, and 5 g of pentaerythritol triallyl ether, and the mixture was stirred mechanically under nitrogen while being heated slowly to 70°C. When the system began to become turbid, a mixed solution of 700 g of ethyl acetate and 300 g of dichloromethane was added to the reaction system under nitrogen, and then 1 g of azobisisovaleronitrile was added to the reaction system and the reaction was continued for 2 hours while maintaining the temperature at 70°C. After the reaction was completed, the product was spray-dried, pulverized, ball-milled at high speed, and sieved through a 500-1000 mesh screen to obtain the final product. The final product was subjected to the bulk density test according to Test Method 1, the particle size and particle size distribution test according to Test Method 2, the dispersion time test according to Test Method 3, the viscosity and light transmittance test at a concentration of 0.5% according to Test Method 4 and Test Method 5, and the results are shown in Table 1.

[0067] Example 7

[0068] A four-necked flask was charged with 400 g of acetic acid, 600 g of dichloromethane, 250 g of acrylic acid, 50 g of acrylamide, 3 g of sodium chloride, 3 g of polyoxyethylene sorbitan stearate, 3 g of methyl ethyl ketone peroxide, and 5 g of pentaerythritol triallyl ether. The mixture was mechanically stirred under nitrogen and heated to 80°C. When the system began to become turbid, a mixture of 200 g of N,N-dimethylformamide and 300 g of cyclohexane was added to the system under nitrogen. Then, 3 g of methyl ethyl ketone peroxide was added to the system, and the reaction was continued for 3 hours at 80°C. After the reaction was completed, the product was spray-dried, pulverized, high-speed ball-milled, and sieved through a 500-1000 mesh screen to obtain the final product. The final product was subjected to the bulk density test according to Test Method 1, the particle size and particle size distribution test according to Test Method 2, the dispersion time test according to Test Method 3, the viscosity and light transmittance test at a concentration of 0.5% according to Test Method 4 and Test Method 5, and the results are shown in Table 1.

[0069] Example 8

[0070] A four-necked flask was charged with 400 g of acetic acid, 600 g of dichloromethane, 250 g of acrylic acid, 50 g of acrylamide, 3 g of sodium chloride, 3 g of polyoxyethylene sorbitan stearate, 3 g of methyl ethyl ketone peroxide, and 5 g of pentaerythritol triallyl ether. The mixture was mechanically stirred under nitrogen and heated to 80°C. When the system began to become turbid, a mixture of 200 g of N,N-dimethylformamide and 300 g of cyclohexane was added to the system under nitrogen. Then, 3 g of methyl ethyl ketone peroxide was added to the system, and the reaction was continued for 3 hours at 80°C. After the reaction was completed, the product was spray-dried, pulverized, high-speed ball-milled, and sieved through a 500-1000 mesh screen to obtain the final product. The final product was subjected to the bulk density test according to Test Method 1, the particle size and particle size distribution test according to Test Method 2, the dispersion time test according to Test Method 3, the viscosity and light transmittance test at a concentration of 0.5% according to Test Method 4 and Test Method 5, and the results are shown in Table 1.

[0071] Comparative Example 1

[0072] A four-necked flask was charged with 400 g of acetic acid, 600 g of dichloromethane, 250 g of acrylic acid, 50 g of acrylamide, 3 g of sodium chloride, 3 g of polyoxyethylene sorbitan stearate, 3 g of methyl ethyl ketone peroxide, and 5 g of pentaerythritol triallyl ether. The mixture was mechanically stirred under nitrogen protection, heated to 80°C, and reacted until the system began to become turbid. Without dilution, 3 g of methyl ethyl ketone peroxide was added to the reaction system, and the reaction was continued for 2 hours at 80°C. After the reaction was completed, the product was spray dried, and the final product was obtained after crushing, high-speed ball milling, and 500-1000 mesh screening. The obtained product was tested for bulk density according to Test Method 1, particle size and particle size distribution according to Test Method 2, dispersion time according to Test Method 3, viscosity and light transmittance at a concentration of 0.5% according to Test Method 4 and Test Method 5, and the results are shown in Table 1.

[0073] Comparative Example 2

[0074] A four-necked flask was charged with 400 g of acetic acid, 600 g of dichloromethane, 250 g of acrylic acid, 50 g of acrylamide, 3 g of sodium chloride, 3 g of polyoxyethylene sorbitan stearate, 3 g of methyl ethyl ketone peroxide, and 5 g of pentaerythritol triallyl ether. The mixture was mechanically stirred under nitrogen protection, heated to 80°C, and reacted until the system began to become turbid. Without dilution, 3 g of methyl ethyl ketone peroxide was added to the reaction system, and the reaction was continued for 2 hours at 80°C. After the reaction was completed, the product was spray dried, and the final product was obtained after crushing, high-speed ball milling, and 500-1000 mesh screening. The obtained product was tested for bulk density according to Test Method 1, particle size and particle size distribution according to Test Method 2, dispersion time according to Test Method 3, viscosity and light transmittance at a concentration of 0.5% according to Test Method 4 and Test Method 5, and the results are shown in Table 1.

[0075] Comparative Example 3

[0076] Into a four-necked flask, 400 g of acetic acid, 600 g of dichloromethane, 250 g of acrylic acid, 50 g of acrylamide, 3 g of sodium chloride, 3 g of polyoxyethylene sorbitan stearate, 3 g of methyl ethyl ketone peroxide and 5 g of pentaerythritol triallyl ether were sequentially added, and mechanical stirring was performed under nitrogen protection, and the reaction was slowly heated to 80°C. When the system began to appear turbidity, 3 g of methyl ethyl ketone peroxide was directly added to the reaction system without dilution, and the reaction was continued for 2 hours. The reaction temperature was maintained at 80°C. After the reaction was completed, the product was spray dried. Subsequently, without crushing, high-speed ball milling and sieving, the final product was directly obtained. The obtained product was tested by the bulk density test of test method 1, the particle size and particle size distribution test of test method 2, the dispersion time test of test method 3, the viscosity and light transmittance test of 0.5% concentration of test method 4 and test method 5, and the results are shown in Table 1.

[0077] Table 1 Test results of products prepared under different conditions

[0078]

[0079]

[0080] According to the test results in Table 1, the fast-dispersing polymer thickener prepared in Examples 1-8 has small particle size, uniform particle size distribution, high bulk density, can realize fast dispersion in water, and after neutralization with alkali, it can quickly thicken, and the obtained hydrogel has excellent viscosity and light transmittance. In the present application, no other hydrophobic monomer or other binder is used for granulation, and no other material is introduced, which will not affect the performance of the original polymer thickener, saves the production cost, and reduces the risk of poor process consistency.

[0081] Comparing Example 6 with Comparative Example 1, it can be seen that the preparation method of the fast-dispersing polymer thickener in the present application dilutes the product by mixing organic solvents during polymerization, which slows down the growth rate of macromolecular chains, reduces the particle size of the product, increases the bulk density, and enables the polymer to realize fast dispersion in water.

[0082] Comparing Example 6 with Comparative Example 2, it can be seen that the preparation method of the fast-dispersing polymer thickener in the present application obtains the target product by crushing, high-speed ball milling and sieving, which can effectively reduce the particle size of the product, increase the bulk density, and enable the polymer to realize fast dispersion in water.

[0083] Comparing Example 6 with Comparative Example 3, it can be seen that dilution by mixing organic solvents during polymerization and crushing, high-speed ball milling and 500-1000 mesh sieving of the product after the reaction is completed can more effectively reduce the particle size of the product, increase the bulk density, and enable the polymer to realize fast dispersion in water.

[0084] The above merely describes the preferred embodiments of the present application, and it should be pointed out that, for those skilled in the art, several improvements and refinements can be made without departing from the principles of the present application, and these improvements and refinements should also be considered as falling within the protection scope of the present application.

Claims

1. A process for preparing a fast dispersing polymer thickener, characterized by, The method comprises the following steps: a) adding mixed organic solvent A, α, β-unsaturated monomer, inorganic dispersant, organic dispersant, crosslinking agent and initiator into a reaction container under the protection of inert atmosphere for reaction; b) adding mixed organic solvent B into the reaction system for dilution; c) adding initiator into the diluted reaction system for continuous reaction; d) after the reaction, the crude product is obtained by spray drying; e) the crude product is crushed, ball milled and sieved to obtain the target particle size product; In step a), the mixed organic solvent A and the mixed organic solvent B in step b) are a mixture of polar organic solvent and non-polar organic solvent; The mixed organic solvent B is added in step b) when the precipitation appears in the reaction system; the mass of the mixed organic solvent B added in step b) is 50%-150% of the mass of the mixed organic solvent A in step a); the mass ratio of the polar organic solvent to the non-polar organic solvent in the mixed organic solvent A and / or the mixed organic solvent B is 2:8-8:2; the polar organic solvent is one or more of acetic acid, N,N-dimethylformamide, N,N-dimethyl sulfoxide, ethyl acetate and acetone; the non-polar organic solvent is one or more of toluene, cyclohexane and dichloromethane; The α, β-unsaturated monomer is one or more of acrylic acid, methacrylic acid, maleic acid, N-vinyl pyrrolidone and acrylamide, and the mass of the α, β-unsaturated monomer is 5%-30% of the mass of the mixed organic solvent A in step a); The crosslinking agent is one or more of allyl sucrose ether, ethylene glycol dimethacrylate, pentaerythritol triallyl ether and pentaerythritol triacrylate, and the mass of the crosslinking agent is 0.1%-5% of the total mass of the α, β-unsaturated monomer.

2. The production method according to claim 1, characterized by, The mixed organic solvent A and the mixed organic solvent B have the same formula.

3. The preparation method according to claim 1, characterized in that The inorganic dispersant is one or more of potassium carbonate, sodium carbonate, calcium carbonate, calcium chloride, sodium chloride and potassium chloride, and the mass of the inorganic dispersant is 0.1%-5% of the total mass of the α, β-unsaturated monomer.

4. The method of claim 1, wherein, The organic dispersant is one or more of sorbitan laurate, sorbitan monooleate, polyoxyethylene sorbitan laurate, polyoxyethylene sorbitan stearate and hydroxyethyl cellulose, and the mass of the organic dispersant is 0.1%-5% of the total mass of the α, β-unsaturated monomer.

5. The preparation method according to claim 1, characterized in that The initiator in step a) or c) is one or more of dodecanoyl peroxide, benzoyl peroxide, methyl ethyl ketone peroxide, azobisdimethyl isobutyl nitrite, azobisdimethyl isopentyl nitrite and azobisdimethyl isohexyl nitrite, and the mass of the initiator in step a) or c) is 0.1%-3% of the total mass of the α, β-unsaturated monomer.

6. The method of claim 1, wherein, The initiator in step c) is the same as that in step a) in terms of type and mass.

7. The preparation method according to claim 1, characterized in that The reaction temperature in steps a) and c) is 40-90℃.

8. The method of claim 1, wherein, The continuous reaction time in step c) is 2-4h.

9. The method of any one of claims 1-8, wherein, The particle size distribution of the target particle size product is 0.1-10 μm.

10. The method of any one of claims 1-8, wherein, The bulk density of the target particle size product is 0.5-0.8 g / ml.

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