Cationic waterborne polyurethane dispersion as well as preparation method and application thereof

Abstract

The invention discloses a cationic waterborne polyurethane dispersion as well as a preparation method and application thereof, relates to the technical field of polyacrylamide waterborne dispersion synthesis, and in particular relates to a preparation method of the cationic waterborne polyurethane dispersion. Comprising the following steps: 1) in the presence of a catalyst, mixing polyoxyethylene, polyether glycol, alkylol amine and aliphatic and / or alicyclic diisocyanate, carrying out a reaction I, adding an acrylamide compound and a polymerization inhibitor, and carrying out a reaction II to obtain a cationic waterborne polyurethane prepolymer; and 2) neutralizing and diluting the cationic waterborne polyurethane prepolymer obtained in the step 1) to obtain the cationic waterborne polyurethane dispersion, the prepared cationic waterborne polyurethane dispersion is used as a stabilizer of a polyacrylamide waterborne dispersion, and the polyacrylamide waterborne dispersion can be effectively stabilized.

Description

Technical Field

[0001] The invention relates to the technical field of polyacrylamide aqueous dispersion synthesis, and in particular to a cationic aqueous polyurethane dispersion and a preparation method and application thereof. Background Art

[0002] Polyacrylamide (CPAM) has good water solubility, efficient viscosity enhancement and unique adsorption properties, and is therefore widely used in many fields such as water treatment, oil recovery, papermaking, and textiles. Aqueous phase dispersion polymerization is an important method for preparing aqueous polyacrylamide dispersions. The polyacrylamide synthesized by this method is directly dispersed in water or water / organic solvent in the form of a colloid, so this aqueous polyacrylamide dispersion can be used directly, avoiding the complex post-treatment of the polymer product. The biggest problem in preparing aqueous polyacrylamide dispersions using aqueous phase dispersion polymerization is that polyacrylamide has a large molecular weight and high viscosity, resulting in poor stability of the dispersion. The prepared aqueous polyacrylamide dispersion will show stratification after being stored for several weeks to several months.

[0003] Improving the stability of polyacrylamide aqueous dispersions and establishing a simple and efficient method for synthesizing polyacrylamide aqueous dispersions are issues that need to be urgently addressed in the current synthesis of polyacrylamide aqueous dispersions. Summary of the invention

[0004] The invention aims to solve the problems that the prior art polyacrylamide aqueous dispersion has poor stability and is easy to be stratified during storage, and provides a cationic aqueous polyurethane dispersion and a preparation method and application thereof. The invention prepares a polyacrylamide aqueous dispersion with good stability, fluidity and high molecular weight by synthesizing a cationic aqueous polyurethane dispersion terminated with acrylamide and polymerizing the cationic aqueous polyurethane dispersion.

[0005] In order to solve the above technical problems, the first aspect of the present invention provides a method for preparing a cationic waterborne polyurethane dispersion, comprising the following steps:

[0006] 1) In the presence of a catalyst, polyoxyethylene, polyether diol, olamine, aliphatic and / or alicyclic diisocyanate are mixed, and reaction I is carried out, and then acrylamide compounds and a polymerization inhibitor are added to carry out reaction II to obtain a cationic waterborne polyurethane prepolymer;

[0007] 2) The cationic waterborne polyurethane prepolymer obtained in step 1) is neutralized and diluted to obtain the cationic waterborne polyurethane dispersion.

[0008] According to some embodiments of the present invention, in step 1), the ratio of the amount of hydroxyl group in polyoxyethylene, the amount of hydroxyl group in polyether diol, the amount of hydroxyl group in alcoholamine, the amount of isocyanate contained in aliphatic and / or alicyclic diisocyanate, and the amount of hydroxyl group in acrylamide compound is (0.1-0.4):(0.1-0.4):(0.1-0.3):1:(0.2-0.4).

[0009] According to some embodiments of the present invention, in step 1), the amount of the polymerization inhibitor added is 0.1% to 1.5% of the mass of the acrylamide compound.

[0010] According to some embodiments of the present invention, in step 1), the amount of the catalyst added is 0.001% to 0.1% by mass of the aliphatic and / or alicyclic diisocyanate.

[0011] According to some embodiments of the present invention, in step 1), the molecular weight of the polyethylene oxide is 2000Da to 20000Da.

[0012] According to some embodiments of the present invention, in step 1), the polyether diol is selected from at least one of polypropylene glycol and polybutylene glycol; preferably, the molecular weight of the polypropylene glycol is 2000Da to 4000Da, preferably 2000Da.

[0013] According to some embodiments of the present invention, in step 1), the alcoholamine is selected from N-alkyldiethanolamine; preferably, the N-alkyldiethanolamine is selected from at least one of N-methyldiethanolamine, N-ethyldiethanolamine and N-phenyldiethanolamine.

[0014] According to some embodiments of the present invention, in step 1), the catalyst is an organic metal catalyst containing tin or bismuth; preferably, the catalyst is at least one of dibutyltin dilaurate, stannous octoate, bismuth laurate, and bismuth isooctanoate;

[0015] According to some embodiments of the present invention, in step 1), the aliphatic and / or alicyclic diisocyanate is selected from at least one of toluene diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, 2,4-phenylene diisocyanate, methylcyclohexyl diisocyanate, and 2,2,4-trimethylhexane diisocyanate.

[0016] According to some embodiments of the present invention, in step 1), the acrylamide compound is selected from hydroxyacrylamide; preferably, the hydroxyacrylamide is selected from at least one of N-hydroxyethylacrylamide, N-(3-hydroxypropyl)acrylamide and N-(4-hydroxybutyl)acrylamide.

[0017] According to some embodiments of the present invention, in step 1), the polymerization inhibitor is selected from at least one of hydroquinone, tert-butylcatechol, and p-hydroxyanisole.

[0018] According to some embodiments of the present invention, in step 1), the conditions of reaction I include: temperature of 45° C. to 85° C., time of 1 hour to 4 hours;

[0019] And / or, the conditions of the reaction II include: a temperature of 45° C. to 85° C. and a time of 2 hours to 4 hours.

[0020] According to some embodiments of the present invention, in step 2), the neutralization conditions include: the temperature is room temperature, and the time is 1 minute to 10 minutes; preferably, the neutralizer added during the neutralization process is selected from at least one of acetic acid and hydrochloric acid; further preferably, the amount of the neutralizer is 40% to 100% of the amount of the alcoholamine.

[0021] According to some embodiments of the present invention, in step 2), the dilution conditions include: the temperature is room temperature, and stirring is 60 minutes to 80 minutes; preferably, the diluent added during the dilution process is water; further preferably, after the dilution, the solid content of the cationic waterborne polyurethane dispersion is 20% to 30%.

[0022] The second aspect of the present invention provides a cationic waterborne polyurethane dispersion prepared by the above-mentioned preparation method, wherein the cationic waterborne polyurethane dispersion is an acrylamide-terminated cationic waterborne polyurethane dispersion.

[0023] The third aspect of the present invention provides a use of the above cationic aqueous polyurethane dispersion as a stabilizer in the synthesis of aqueous polyacrylamide dispersion.

[0024] The fourth aspect of the present invention provides a method for preparing an aqueous polyacrylamide dispersion, comprising adding acrylamide, an aqueous solution of methacryloyloxyethyl trimethylammonium chloride, water, and ammonium sulfate to a cationic aqueous polyurethane dispersion, and polymerizing in the presence of an inert atmosphere and an initiator to obtain the aqueous polyacrylamide dispersion; wherein the cationic aqueous polyurethane dispersion is the above-mentioned cationic aqueous polyurethane dispersion;

[0025] Preferably, the mass concentration of the methacryloyloxyethyltrimethylammonium chloride aqueous solution is 80%.

[0026] According to some embodiments of the present invention, the inactive atmosphere is selected from at least one of nitrogen and helium.

[0027] According to some embodiments of the present invention, the mass ratio of acrylamide, methacryloyloxyethyltrimethylammonium chloride aqueous solution, water, ammonium sulfate and cationic aqueous polyurethane dispersion is (150-450): (30-90): (1120-3360): (45-135): (100-300), preferably 300:60:2240:90:200.

[0028] According to some embodiments of the present invention, the added amount of the initiator is 0.01% to 0.1% of the mass of acrylamide; preferably, the initiator is selected from at least one of ammonium persulfate, sodium bisulfite, and VA-044 initiator.

[0029] According to some embodiments of the present invention, the polymerization conditions include: a temperature of 25° C. to 45° C., and a time of 2 hours to 6 hours.

[0030] Beneficial effects:

[0031] The cationic waterborne polyurethane dispersion prepared by the invention is used as a stabilizer for waterborne polyacrylamide dispersion, and is connected with polyacrylic acid molecular chains through covalent bonds, so as to effectively stabilize the waterborne polyacrylamide dispersion.

[0032] The cationic waterborne polyurethane dispersion prepared by the invention has an acrylamide terminal group, and can react with acrylamide to generate branched polyacrylamide, thereby increasing the molecular weight of the polyacrylamide. DETAILED DESCRIPTION

[0033] The present invention will be further described below in conjunction with the embodiments, but the present invention is not limited by these embodiments.

[0034] Unless otherwise specified, the reaction kettle, three-necked flask, and constant pressure funnel used in the examples of the present invention are all common commercially available products.

[0035] The polyoxyethylene used in the examples of the present invention was purchased from Shanghai Dongda Chemical Co., Ltd., with a model of PEG2000 and a molecular weight of 2000 Da.

[0036] The polypropylene glycol used in the examples of the present invention was purchased from Shandong Bluestar Dongda Co., Ltd., with a model of DL2000 and a molecular weight of 2000 Da.

[0037] Unless otherwise specified, the N-methyldiethanolamine, isophorone diisocyanate, N-hydroxyethyl acrylamide, N-(3-hydroxypropyl) acrylamide, p-hydroxyanisole, toluene diisocyanate, and dibutyltin dilaurate used in the embodiments of the present invention are all common commercially available reagents.

[0038] Unless otherwise specified in the present invention, the room temperature is 25°C.

[0039] Example 1

[0040] This embodiment provides a cationic waterborne polyurethane dispersion.

[0041] 3000 grams of dry polyoxyethylene (PEG2000, molecular weight 2000Da), 3000 grams of polypropylene glycol (DL2000, molecular weight 2000Da), 119 grams of N-methyldiethanolamine, 1112 grams of isophorone diisocyanate and 0.10 grams of dibutyltin dilaurate were added to a reactor, stirred evenly, heated to 75°C, and reacted at 75°C for 3 hours, then 230 grams of N-hydroxyethyl acrylamide and 0.5 grams of p-hydroxyanisole were added, the reaction was continued at 75°C for 3 hours, and the temperature was cooled to room temperature to obtain an acrylamide-terminated cationic waterborne polyurethane prepolymer;

[0042] At room temperature, 40 g of acetic acid was added to the cationic waterborne polyurethane prepolymer, stirred for 5 minutes, and then 17480 g of pure water was added and stirred for 1 hour to obtain an acrylamide-terminated cationic waterborne polyurethane dispersion A1 with a solid content of 30%.

[0043] In the above, the amount of acetic acid is 66.6% of the amount of N-methyldiethanolamine.

[0044] Example 2

[0045] This embodiment provides a cationic waterborne polyurethane dispersion.

[0046] 4000 g of dry polyoxyethylene (PEG4000, molecular weight 4000Da), 3000 g of polypropylene glycol (DL2000, molecular weight 2000Da), 178 g of N-methyldiethanolamine, 1112 g of isophorone diisocyanate and 0.10 g of dibutyltin dilaurate were added to a reactor, stirred evenly, heated to 75°C, and reacted at 75°C for 3 hours, then 230 g of N-hydroxyethyl acrylamide and 0.5 g of p-hydroxyanisole were added, the reaction was continued at 75°C for 3 hours, and the temperature was cooled to room temperature to obtain an acrylamide-terminated cationic waterborne polyurethane prepolymer;

[0047] At room temperature, 40 g of acetic acid was added to the cationic waterborne polyurethane prepolymer, stirred for 5 minutes, and then 19980 g of pure water was added and stirred for 1 hour to obtain an acrylamide-terminated cationic waterborne polyurethane dispersion A2 with a solid content of 30%.

[0048] In the above, the amount of acetic acid is 44.4% of the amount of N-methyldiethanolamine.

[0049] Example 3

[0050] This embodiment provides a cationic waterborne polyurethane dispersion.

[0051] 3000 grams of dry polyoxyethylene (PEG2000, molecular weight 2000Da), 3000 grams of polypropylene glycol (DL2000, molecular weight 2000Da), 119 grams of N-methyldiethanolamine, 348 grams of toluene diisocyanate, 669 grams of isophorone diisocyanate and 0.10 grams of dibutyltin dilaurate were added to a reactor, stirred evenly, heated to 75°C, and reacted for 3 hours at 75°C, then 230 grams of N-hydroxyethyl acrylamide and 0.5 grams of p-hydroxyanisole were added, the reaction was continued at 75°C for 3 hours, and the temperature was cooled to room temperature to obtain an acrylamide-terminated cationic waterborne polyurethane prepolymer;

[0052] At room temperature, 40 g of acetic acid was added to the cationic waterborne polyurethane prepolymer, stirred for 5 minutes, and then 16740 g of pure water was added and stirred for 1 hour to obtain an acrylamide-terminated cationic waterborne polyurethane dispersion A3 with a solid content of 30%.

[0053] In the above, the amount of acetic acid is 66.6% of the amount of N-methyldiethanolamine.

[0054] Example 4

[0055] This embodiment provides a cationic waterborne polyurethane dispersion.

[0056] 3000 grams of dry polyoxyethylene (PEG2000, molecular weight 2000Da), 3000 grams of polypropylene glycol (DL2000, molecular weight 2000Da), 119 grams of N-methyldiethanolamine, 1112 grams of isophorone diisocyanate and 0.10 grams of dibutyltin dilaurate were added to a reactor, stirred evenly, heated to 75°C, and reacted for 3 hours at 75°C, then 258 grams of N-(3-hydroxypropyl) acrylamide and 0.5 grams of p-hydroxyanisole were added, the reaction was continued at 75°C for 3 hours, and the temperature was cooled to room temperature to obtain an acrylamide-terminated cationic waterborne polyurethane prepolymer;

[0057] At room temperature, 40 g of acetic acid was added to the cationic waterborne polyurethane prepolymer, stirred for 5 minutes, and then 17570 g of pure water was added and stirred for 1 hour to obtain an acrylamide-terminated cationic waterborne polyurethane dispersion A1 with a solid content of 30%.

[0058] In the above, the amount of acetic acid is 66.6% of the amount of N-methyldiethanolamine.

[0059] Example 5

[0060] This embodiment provides a cationic waterborne polyurethane dispersion.

[0061] 4000 grams of dry polyoxyethylene (PEG2000, molecular weight 2000Da), 2000 grams of polypropylene glycol (DL2000, molecular weight 2000Da), 119 grams of N-methyldiethanolamine, 1112 grams of isophorone diisocyanate and 0.10 grams of dibutyltin dilaurate were added to a reactor, stirred evenly, heated to 75°C, and reacted at 75°C for 3 hours, then 230 grams of N-hydroxyethyl acrylamide and 0.5 grams of p-hydroxyanisole were added, the reaction was continued at 75°C for 3 hours, and the temperature was cooled to room temperature to obtain an acrylamide-terminated cationic waterborne polyurethane prepolymer;

[0062] At room temperature, 40 g of acetic acid was added to the cationic waterborne polyurethane prepolymer, stirred for 5 minutes, and then 17480 g of pure water was added and stirred for 1 hour to obtain an acrylamide-terminated cationic waterborne polyurethane dispersion A5 with a solid content of 30%.

[0063] In the above, the amount of acetic acid is 66.6% of the amount of N-methyldiethanolamine.

[0064] Example 6

[0065] This embodiment provides a cationic waterborne polyurethane dispersion.

[0066] 5000 g of dry polyoxyethylene (PEG2000, molecular weight 2000Da), 1000 g of polypropylene glycol (DL2000, molecular weight 2000Da), 119 g of N-methyldiethanolamine, 1112 g of isophorone diisocyanate and 0.10 g of dibutyltin dilaurate were added to a reactor, stirred evenly, heated to 75°C, and reacted at 75°C for 3 hours, then 230 g of N-hydroxyethyl acrylamide and 0.5 g of p-hydroxyanisole were added, the reaction was continued at 75°C for 3 hours, and the temperature was cooled to room temperature to obtain an acrylamide-terminated cationic waterborne polyurethane prepolymer;

[0067] At room temperature, 40 g of acetic acid was added to the cationic waterborne polyurethane prepolymer, stirred for 5 minutes, and then 17480 g of pure water was added and stirred for 1 hour to obtain an acrylamide-terminated cationic waterborne polyurethane dispersion A6 with a solid content of 30%.

[0068] In the above, the amount of acetic acid is 66.6% of the amount of N-methyldiethanolamine.

[0069] Preparation Example 1

[0070] This preparation example provides an aqueous dispersion of polyacrylamide.

[0071] 300 g of acrylamide, 60 g of 80% methacryloyloxyethyl trimethyl ammonium chloride aqueous solution, 2240 g of water, 90 g of ammonium sulfate, and 200 g of the cationic waterborne polyurethane dispersion A1 obtained in Example 1 of the present invention are added into a three-necked flask; 0.12 g of ammonium persulfate is dissolved in 3.0 g of water and loaded into a constant pressure funnel 1; 0.07 g of sodium bisulfite is dissolved in 3.0 g of water and loaded into a constant pressure funnel 2; two constant pressure funnels are placed on the three-necked flask, and nitrogen is passed into the three-necked flask to deoxygenate under stirring;

[0072] When the temperature of the three-necked flask was raised to 35° C., the initiators in the two constant pressure funnels were added into the three-necked flask at the same time, and the mixture was reacted for 5 hours under stirring to obtain a polyacrylamide aqueous dispersion B1.

[0073] Preparation Example 2

[0074] This preparation example provides an aqueous dispersion of polyacrylamide.

[0075] 300 g of acrylamide, 60 g of 80% aqueous solution of methacryloyloxyethyl trimethyl ammonium chloride, 2240 g of water, 90 g of ammonium sulfate, and 200 g of the cationic waterborne polyurethane dispersion A1 obtained in Example 1 of the present invention were added into a three-necked flask; 0.12 g of VA-044 initiator was dissolved in 3.0 g of water, and the mixture was put into a constant pressure funnel, and the constant pressure funnel was placed on the three-necked flask. Under stirring, nitrogen was passed into the three-necked flask to deoxygenate;

[0076] When the temperature of the three-necked flask was raised to 35° C., the initiator in the constant pressure funnel was added into the three-necked flask and reacted for 5 hours under stirring to obtain a polyacrylamide aqueous dispersion B2.

[0077] Preparation Example 3

[0078] This preparation example provides an aqueous dispersion of polyacrylamide.

[0079] 300 g of acrylamide, 60 g of 80% aqueous solution of methacryloyloxyethyl trimethyl ammonium chloride, 2240 g of water, 90 g of ammonium sulfate, and 200 g of the cationic waterborne polyurethane dispersion A2 obtained in Example 2 of the present invention were added into a three-necked flask; 0.12 g of VA-044 initiator was dissolved in 3.0 g of water, and the mixture was placed into a constant pressure funnel, and the constant pressure funnel was placed on the three-necked flask. Under stirring, nitrogen was passed into the three-necked flask to deoxygenate;

[0080] When the temperature of the three-necked flask was raised to 35° C., the initiator in the constant pressure funnel was added into the three-necked flask and reacted for 5 hours under stirring to obtain a polyacrylamide aqueous dispersion B3.

[0081] Preparation Example 4

[0082] This preparation example provides an aqueous dispersion of polyacrylamide.

[0083] 300 g of acrylamide, 60 g of 80% aqueous solution of methacryloyloxyethyl trimethyl ammonium chloride, 2240 g of water, 90 g of ammonium sulfate, and 200 g of the cationic waterborne polyurethane dispersion A5 obtained in Example 5 of the present invention were added into a three-necked flask; 0.12 g of VA-044 initiator was dissolved in 3.0 g of water, and the mixture was placed into a constant pressure funnel, and the constant pressure funnel was placed on the three-necked flask. Under stirring, nitrogen was passed into the three-necked flask to deoxygenate;

[0084] When the temperature of the three-necked flask was raised to 35° C., the initiator in the constant pressure funnel was added into the three-necked flask and reacted for 5 hours under stirring to obtain a polyacrylamide aqueous dispersion B4.

[0085] Preparation Example 5

[0086] This preparation example provides an aqueous dispersion of polyacrylamide.

[0087] 300 g of acrylamide, 60 g of 80% aqueous solution of methacryloyloxyethyl trimethyl ammonium chloride, 2240 g of water, 90 g of ammonium sulfate, and 200 g of the cationic waterborne polyurethane dispersion A6 obtained in Example 6 of the present invention were added into a three-necked flask; 0.12 g of VA-044 initiator was dissolved in 3.0 g of water, and the mixture was placed into a constant pressure funnel, and the constant pressure funnel was placed on the three-necked flask. Under stirring, nitrogen was passed into the three-necked flask to deoxygenate;

[0088] When the temperature of the three-necked flask was raised to 35° C., the initiator in the constant pressure funnel was added into the three-necked flask and reacted for 5 hours under stirring to obtain a polyacrylamide aqueous dispersion B5.

[0089] Comparative Example 1

[0090] This comparative example prepares an acrylamide-terminated anionic waterborne polyurethane dispersion.

[0091] The method described in Example 1 was followed, except that 134 g of 2,2-dimethylolpropionic acid was used instead of 119 g of N-methyldiethanolamine.

[0092] Comparative Example 2

[0093] This comparative example prepares a cationic waterborne polyurethane dispersion that does not contain acrylamide end groups.

[0094] The method described in Example 1 was followed, except that 92 g of ethanol was used instead of 230 g of N-hydroxyethyl acrylamide.

[0095] Comparative Preparation Example 1

[0096] This preparation example provides an aqueous dispersion of polyacrylamide.

[0097] The method described in Preparation Example 1 was followed, except that the acrylamide-terminated anionic aqueous polyurethane dispersion obtained in Comparative Example 1 was used instead of the cationic aqueous polyurethane dispersion A1 obtained in Example 1 of the present invention.

[0098] Comparative Preparation Example 2

[0099] This preparation example provides an aqueous dispersion of polyacrylamide.

[0100] The method described in Preparation Example 1 was followed, except that the cationic waterborne polyurethane dispersion without acrylamide end-capping obtained in Comparative Example 2 was used instead of the cationic waterborne polyurethane dispersion A1 obtained in Example 1 of the present invention.

[0101] Test Case

[0102] The basic parameters of the cationic aqueous polyurethane dispersions prepared in Examples 1-6 of the present invention and the aqueous polyurethane dispersions prepared in Comparative Examples 1-2 are shown in Table 1;

[0103] Among them, the amounts and molecular weights of polyoxyethylene and polypropylene glycol used in Examples 1-6 are different, and the aliphatic and / or alicyclic diisocyanates are also different, but all of them can obtain cationic aqueous polyurethane dispersions terminated with acrylamide; since a large number of polyurethane molecular chains contain more hydrophilic groups, the hydrodynamic radius of the aqueous polyurethane dispersion is smaller; Comparative Example 1 prepares an anionic aqueous polyurethane dispersion terminated with acrylamide, which has the opposite charge to that of Examples 1-6; Comparative Example 2 prepares a cationic aqueous polyurethane dispersion without acrylamide end groups.

[0104] The appearance, solid content, viscosity, freeze-thaw stability and centrifugal stability of the aqueous polyurethane dispersions prepared in Examples 1-6 of the present invention and Comparative Examples 1-2 were tested with reference to GB / T 11175-2002;

[0105] Freeze-thaw stability: 50 mL of waterborne polyurethane dispersion was placed in a low-temperature box at -5±2°C, taken out after 18 hours, and placed at 23±2°C for 6 hours. Repeat the operation to observe whether there is precipitation.

[0106] Among them, centrifugal stability: take 30mL of waterborne polyurethane dispersion in a centrifuge, centrifuge for 30min at a speed of 3000r / min, and test the centrifugal stability of the waterborne polyurethane dispersion.

[0107] Among them, the viscosity test instrument is Brookfield viscometer DV1, and the viscosity determination method is: direct testing at a temperature of 25°C;

[0108] The method for determining the hydrodynamic diameter is as follows: diluting the cationic waterborne polyurethane dispersion with water until the solid content (mass concentration) of the cationic waterborne polyurethane dispersion is 1%, and then measuring the hydrodynamic diameter of the cationic waterborne polyurethane dispersion with a mass concentration of 1% using Malvern Nano-ZS90;

[0109] The concentration of acrylamide end groups in the cationic waterborne polyurethane dispersion is measured by nuclear magnetic resonance spectrometer.

[0110] Table 1 Basic parameters of cationic aqueous polyurethane dispersions prepared in Examples 1-6 of the present invention and aqueous polyurethane dispersions prepared in Comparative Examples 1-2

[0111]

[0112]

[0113] The results in Table 1 show that the cationic aqueous polyurethane dispersions prepared in Examples 1-4 are all water-white transparent dispersions with a hydrodynamic diameter of 18 to 23 nm. The concentration of acrylamide end groups in the cationic aqueous polyurethane dispersions is close to or slightly lower than the theoretical value (calculated based on the feed), and the stability is good. The hydrodynamic diameters of the aqueous polyurethane dispersions prepared in Comparative Examples 1-2 are similar, wherein Comparative Example 1 prepares an anionic aqueous polyurethane dispersion, and Comparative Example 2 prepares a cationic aqueous polyurethane dispersion that does not contain acrylamide end groups, and the particle size and stability are similar to those of the aqueous polyurethane dispersion prepared in Example 1.

[0114] The basic parameters of the aqueous polyacrylamide dispersions prepared in Preparation Examples 1-5 of the present invention and Comparative Preparation Examples 1-2 are shown in Table 2.

[0115] The polymer concentration is measured by diluting a polyacrylamide aqueous dispersion of weight C1 with water to a mass concentration of 1% of the polyacrylamide aqueous dispersion, and then placing the polyacrylamide aqueous dispersion in a dialysis bag (molecular weight cutoff size: 1000 Da) and dialyzing the sample in water for three days, and then freeze-drying the sample to obtain a dry sample weight C2, and the polymer concentration is the percentage of the ratio of C2 to CI;

[0116] Among them, the apparent viscosity is the viscosity of the polyacrylamide aqueous dispersion directly tested without dilution with water; the viscosity of the polymer solution with a mass concentration of 1% refers to the viscosity of the solution when the polyacrylamide aqueous dispersion is diluted with water to a mass concentration of polyacrylamide and its copolymer of 1%;

[0117] The stability of the aqueous polyacrylamide dispersions prepared in Preparation Examples 1 to 5 of the present invention is stable when observed by eyes at room temperature if the dispersions do not separate into layers, and unstable if they separate into layers.

[0118] Table 2 Parameters of aqueous polyacrylamide dispersions prepared in Preparation Examples 1-5 of the present invention

[0119]

[0120] The results in Table 2 show that the aqueous polyacrylamide dispersions prepared in Preparation Examples 1-5 have a relatively high viscosity of a polymer solution with a mass concentration of 1%, and the stability exceeds 3 months; indicating that the cationic aqueous polyurethane dispersions prepared in Examples 1-6 of the present invention are effective stabilizers for preparing aqueous polyacrylamide dispersions; on the contrary, the aqueous polyacrylamide dispersion prepared by using the anionic aqueous polyurethane dispersion terminated with acrylamide as a stabilizer in Comparative Example 1 is unstable and stratified, and the viscosity of the polymer solution with a mass concentration of 1% is relatively high, but the stability is extremely poor; and the viscosity of the polymer solution with a mass concentration of 1% using the cationic aqueous polyurethane dispersion without acrylamide end groups in Comparative Example 2 as a stabilizer is slightly lower, and the stability is also slightly poor.

[0121] It should be noted that the embodiments described above are only used to explain the present invention and do not constitute any limitation to the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory words, rather than restrictive words. The present invention may be modified as specified within the scope of the claims of the present invention, and the present invention may be revised without departing from the scope and spirit of the present invention. Although the present invention described therein relates to specific methods, materials and embodiments, it does not mean that the present invention is limited to the specific examples disclosed therein, on the contrary, the present invention can be extended to all other methods and applications with the same functions.

Claims

1. A method for preparing a cationic waterborne polyurethane dispersion, characterized in that: The following steps are included: 1) In the presence of a catalyst, polyoxyethylene, polyether diol, olamine, aliphatic and / or alicyclic diisocyanate are mixed, and reaction I is carried out, and then acrylamide compounds and a polymerization inhibitor are added to carry out reaction II to obtain a cationic waterborne polyurethane prepolymer; 2) neutralizing and diluting the cationic waterborne polyurethane prepolymer obtained in step 1) to obtain the cationic waterborne polyurethane dispersion.

2. The preparation method according to claim 1, characterized in that: In step 1), the ratio of the amount of hydroxyl groups in polyoxyethylene, the amount of hydroxyl groups in polyether diol, the amount of hydroxyl groups in alcohol amine, the amount of isocyanate contained in aliphatic and / or alicyclic diisocyanate, and the amount of hydroxyl groups in acrylamide compounds is (0.1-0.4):(0.1-0.4):(0.1-0.3):1:(0.2-0.4); And / or, the amount of the polymerization inhibitor added is 0.1% to 1.5% of the mass of the acrylamide compound; And / or, the added amount of the catalyst is 0.001% to 0.1% of the mass of the aliphatic and / or alicyclic diisocyanate.

3. The preparation method according to claim 2, characterized in that: In step 1), the molecular weight of the polyoxyethylene is 2000Da to 20000Da; And / or, the polyether diol is selected from at least one of polypropylene glycol and polybutylene glycol; preferably, the molecular weight of the polypropylene glycol is 2000Da to 4000Da, preferably 2000Da; And / or, the alcohol amine is selected from N-alkyldiethanolamine; preferably, the N-alkyldiethanolamine is selected from at least one of N-methyldiethanolamine, N-ethyldiethanolamine and N-phenyldiethanolamine; And / or, the aliphatic and / or alicyclic diisocyanate is selected from at least one of toluene diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, 2,4-phenylene diisocyanate, methylcyclohexyl diisocyanate and 2,2,4-trimethylhexane diisocyanate; And / or, the acrylamide compound is selected from hydroxyacrylamide; preferably, the hydroxyacrylamide is selected from at least one of N-hydroxyethylacrylamide, N-(3-hydroxypropyl)acrylamide and N-(4-hydroxybutyl)acrylamide; And / or, the catalyst is an organic metal catalyst containing tin or bismuth; preferably, the catalyst is at least one of dibutyltin dilaurate, stannous octoate, bismuth laurate, and bismuth isooctanoate; And / or, the polymerization inhibitor is selected from at least one of hydroquinone, tert-butylcatechol and p-hydroxyanisole.

4. The preparation method according to any one of claims 1 to 3, characterized in that In step 1), the conditions of reaction I include: temperature of 45°C to 85°C, time of 1 hour to 4 hours; And / or, the conditions of the reaction II include: a temperature of 45° C. to 85° C. and a time of 2 hours to 4 hours.

5. The preparation method according to any one of claims 1 to 4, characterized in that: In step 2), the neutralization conditions include: room temperature, time of 1 minute to 10 minutes; preferably, the neutralizing agent added during the neutralization process is selected from at least one of acetic acid and hydrochloric acid; further preferably, the amount of the neutralizing agent is 40% to 100% of the amount of the alcoholamine.

6. The preparation method according to any one of claims 1 to 5, characterized in that: In step 2), the dilution conditions include: the temperature is room temperature, and stirring is 60 minutes to 80 minutes; preferably, the diluent added during the dilution process is water; further preferably, after the dilution, the solid content of the cationic waterborne polyurethane dispersion is 20% to 30%.

7. A cationic waterborne polyurethane dispersion prepared by the preparation method according to any one of claims 1 to 6, characterized in that: The cationic waterborne polyurethane dispersion is an acrylamide-terminated cationic waterborne polyurethane dispersion.

8. Use of the cationic aqueous polyurethane dispersion prepared by the preparation method according to any one of claims 1 to 6 or the cationic aqueous polyurethane dispersion according to claim 7 as a stabilizer in synthesizing an aqueous polyacrylamide dispersion.

9. A method for preparing an aqueous dispersion of polyacrylamide, characterized in that: The method comprises adding acrylamide, methacryloyloxyethyl trimethylammonium chloride aqueous solution, water and ammonium sulfate to a cationic waterborne polyurethane dispersion, and polymerizing in the presence of an inert atmosphere and an initiator to obtain the polyacrylamide waterborne dispersion; wherein the cationic waterborne polyurethane dispersion is the cationic waterborne polyurethane dispersion prepared by the preparation method according to any one of claims 1 to 6 or the cationic waterborne polyurethane dispersion according to claim 7; Preferably, the mass concentration of the methacryloyloxyethyltrimethylammonium chloride aqueous solution is 80%.

10. The method according to claim 9, characterized in that The inactive atmosphere is selected from at least one of nitrogen and argon; and / or, the mass ratio of acrylamide, methacryloyloxyethyltrimethylammonium chloride aqueous solution, water, ammonium sulfate and cationic aqueous polyurethane dispersion is (150-450):(30-90):(1120-3360):(45-135):(100-300), preferably 300:60:2240:90:200; And / or, the amount of the initiator added is 0.01% to 0.1% of the mass of acrylamide; preferably, the initiator is selected from at least one of ammonium persulfate, sodium bisulfite, and VA-044 initiator; And / or, the polymerization conditions include: temperature of 25° C. to 45° C., and time of 2 hours to 6 hours.

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