Water-based polymer dispersing agent as well as preparation method and application thereof

Abstract

The invention relates to a water-based polymer dispersing agent as well as a preparation method and application thereof. The water-based polymer dispersant is prepared from the following raw materials: a monomer, an initiator, amino alcohol and monoisocyanate, the monomers comprise a monomer a, a monomer b and a monomer c; the monomer a comprises a vinyl aromatic compound; the monomer b comprises olefinic unsaturated carboxylic acid anhydride; the monomer c comprises an alkenyl imidazole compound. The combination of the monomer a, the monomer b and the monomer c is selected and matched with the raw materials, namely the amino alcohol and the isocyanate, so that the dispersing agent has excellent dispersing performance, the dispersing agent is applied to a pigment color paste formula to form a coating, the stability of pigment color paste and the compatibility of the pigment color paste with a waterborne polyurethane emulsion can be improved, and the service life of the coating is prolonged. Meanwhile, a new way is provided for synthesizing a high-performance water-based polymer dispersing agent, and the progress in the field of polymer dispersing agent material production is promoted.

Description

Technical Field

[0001] The present invention relates to the technical field of dispersants, and in particular to an aqueous polymer dispersant and a preparation method and application thereof. Background Art

[0002] As a pigment dispersing aid, dispersant has the properties of reducing pigment particle size, increasing the gloss of the coating film, improving leveling, and improving the coloring and hiding power of the coating. It is an important raw material that is indispensable in the production of coatings. Traditional dispersants are usually low molecular weight surfactants with relatively simple molecular structures and fewer anchoring groups. This structure is difficult to provide stable surface adsorption capacity and steric hindrance effect on the pigment particles. After the slurry made from it is toned into paint by the waterborne polyurethane emulsion system, the molecular structure of the polyurethane emulsion contains a large number of carbamate segments, which will be affected by polar functional groups. In addition, the low molecular weight surfactant has insufficient adsorption strength on the pigment particles. On the one hand, the surfactant adsorbed on the surface of the pigment particles detaches, causing the pigment particles to aggregate and precipitate. On the other hand, the migrated surfactant will also affect the stability of the waterborne polyurethane emulsion, and then affect the stability of the paint.

[0003] Hyperdispersant is a high molecular weight dispersant with a more complex molecular structure. Through the regulation of molecular structure, the polymer molecular structure can contain multiple and various types of anchoring groups and rich solvated segments. It can provide stable surface adsorption capacity of pigment particles and corresponding spatial protection effect, form a stable protective layer, effectively prevent the agglomeration and sedimentation of pigment particles, and provide stronger protection for pigment particles in emulsion system, thus improving its application effect in polyurethane emulsion system.

[0004] Therefore, it is of great significance to design and develop a new water-based polymer dispersant with the performance of a hyperdispersant, which can improve the stability of the pigment and its compatibility with water-based polyurethane emulsion. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides an aqueous polymer dispersant and a preparation method and application thereof. The aqueous polymer dispersant is prepared from raw monomers, initiators, amino alcohols and monoisocyanates, has a high molecular weight, and contains multiple types of anchoring groups and abundant solvated segments in its molecular structure. It is applied to the pigment paste formula to form a coating, which can improve the stability of the pigment paste and its compatibility with the aqueous polyurethane emulsion. At the same time, it provides a new way to synthesize high-performance aqueous polymer dispersants, which helps to promote the progress in the field of polymer dispersant material production.

[0006] To achieve this object, the present invention adopts the following technical solutions:

[0007] In a first aspect, the present invention provides an aqueous polymer dispersant, wherein the raw materials for preparing the aqueous polymer dispersant include a monomer, an initiator, an amino alcohol and a monoisocyanate;

[0008] The monomers include monomer a, monomer b, and monomer c;

[0009] The monomer a comprises a vinyl aromatic compound; the monomer b comprises an ethylenically unsaturated carboxylic acid anhydride; and the monomer c comprises an alkenyl imidazole compound.

[0010] The aqueous polymer dispersant of the present invention selects a combination of monomer a, monomer b and monomer c, and is matched with raw materials amino alcohol and isocyanate, so that it has the characteristics of high molecular weight, multiple anchoring groups of various types and abundant solvated segments in the molecular structure, and thus has excellent dispersibility. It is applied to the pigment paste formula to form a coating. Compared with the traditional low-molecular-weight surfactant, the stability of the pigment paste can be significantly improved, so that the pigment paste does not sink to the bottom, does not agglomerate, has a long stable period, and can be stored for a long time; at the same time, it also has excellent compatibility with the aqueous polyurethane emulsion, further expanding its application range.

[0011] In the present invention, the microstructure of the water-based polymer is regulated by adjusting the ratio, type, polymerization temperature, dripping rate and other process parameters of the monomers, and the benzene ring, carbamate chain segment and imidazole functional group are blended together in the macromolecular polymer to make it have both hydrophilic and lipophilic amphiphilic functional group structures, thereby achieving the excellent ability to stabilize the pigment paste.

[0012] Preferably, the weight average molecular weight of the aqueous polymer dispersant is 10000-100000 g / mol, for example, it can be 10000 g / mol, 20000 g / mol, 30000 g / mol, 40000 g / mol, 50000 g / mol, 60000 g / mol, 70000 g / mol, 80000 g / mol, 90000 g / mol or 100000 g / mol, as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0013] Preferably, the molar ratio of monomer a, monomer b and monomer c is (2-4):(3-6):(1-3), wherein (2-4) can be, for example, 2, 2.2, 2.4, 2.6, 2.8, 3, 3.2, 3.4, 3.6, 3.8 or 4, (3-6) can be, for example, 3, 3.5, 4, 4.5, 5, 5.5 or 6, (1-3) can be, for example, 1, 1.2, 1.4, 1.6, 1.8, 2, 2.2, 2.4, 2.6, 2.8 or 3, as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the said range.

[0014] In the present invention, by compounding monomer a, monomer b and monomer c, it is beneficial to obtain an aqueous polymer dispersant with excellent dispersibility, and applying it to the pigment paste formula to form a coating can improve the stability of the pigment paste and the compatibility of the pigment paste with the polyurethane emulsion. At the same time, when the molar ratio between the three is (2-4): (3-6): (1-3), its performance is better. Further, when the molar amount of the monomer a, monomer b, and monomer c satisfies monomer c < monomer a < monomer b, the hydrophilicity and lipophilicity of the obtained polymer as a whole are balanced and controlled, making it more suitable for the dispersion, wetting and stability of the pigment, and it is beneficial to improve the compatibility of the pigment paste with the polyurethane emulsion. When the molar ratio of the three exceeds the specific molar ratio range, the polymer is difficult to achieve a balance due to hydrophilicity and lipophilicity, and it is difficult to make the obtained aqueous polymer dispersant achieve the best ability to disperse, wet and stabilize the pigment.

[0015] Preferably, the vinyl aromatic compound comprises styrene and / or methylstyrene.

[0016] Preferably, the methylstyrene includes any one of 2-methylstyrene, 3-methylstyrene, 4-methylstyrene or α-methylstyrene, or a combination of at least two thereof.

[0017] Preferably, the ethylenically unsaturated carboxylic anhydride comprises an unsaturated succinic anhydride compound.

[0018] Preferably, the unsaturated succinic anhydride compound includes maleic anhydride and / or itaconic anhydride.

[0019] Preferably, the alkenyl imidazole compound comprises a vinyl imidazole compound.

[0020] Preferably, the vinyl imidazole compound includes any one of 1-vinylimidazole, 5-vinylimidazole, 2-vinylimidazole or 2-methyl-1-vinylimidazole, or a combination of at least two thereof.

[0021] Preferably, the amount of the initiator added is 1-5% of the mass of the monomer, for example, it can be 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5% or 5%, as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0022] Preferably, the initiator comprises a peroxide initiator.

[0023] Preferably, the peroxide initiator comprises any one or a combination of at least two of benzoyl peroxide, tert-butyl benzoyl peroxide, methyl ethyl ketone peroxide, dicumyl peroxide, di-tert-butyl peroxide or 2,2-bis(tert-butyl peroxide)butane.

[0024] Preferably, the molar ratio of the amino alcohol to monomer b is 1:1.

[0025] Preferably, the amino alcohol comprises a primary amino alcohol.

[0026] Preferably, the primary amine alcohol includes any one of tris(hydroxymethyl)aminomethane, 2-amino-2-methyl-1,3-propanediol, 2-amino-2-ethyl-1,3-propanediol, 2-amino-1,3-propanediol, monoethanolamine, n-propanol, isopropanolamine, 2-amino-2-methyl-1-propanol, 1-amino-2-butanol or 2-amino-1-butanol, or a combination of at least two thereof.

[0027] Preferably, the molar ratio of the monoisocyanate to the monomer b is (1-3):1, (1-3) can be, for example, 1, 1.2, 1.4, 1.6, 1.8, 2, 2.2, 2.4, 2.6, 2.8 or 3, as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0028] Preferably, the monoisocyanate includes any one of n-butyl isocyanate, isobutyl isocyanate, tert-butyl isocyanate, n-propyl isocyanate, isopropyl isocyanate or ethyl isocyanate, or a combination of at least two thereof.

[0029] In a second aspect, the present invention provides a method for preparing the aqueous polymer dispersant as described in the first aspect, the preparation method comprising the following steps:

[0030] (1) reacting a monomer and an initiator to obtain an intermediate polymer 1;

[0031] (2) reacting the amino alcohol with the intermediate polymer 1 of step (1) to obtain an intermediate polymer 2;

[0032] (3) reacting the monoisocyanate with the intermediate polymer 2 of step (2) to obtain the aqueous polymer dispersant.

[0033] Preferably, the reaction in step (1) is carried out in a solvent.

[0034] Preferably, the solvent comprises an inert solvent.

[0035] Preferably, the inert solvent includes any one of diethylene glycol dimethyl ether, ethylene glycol dimethyl ether or triethylene glycol dimethyl ether, or a combination of at least two thereof.

[0036] Preferably, the amount of the solvent added is 2-4 times the mass of the monomer, for example, it can be 2 times, 2.2 times, 2.5 times, 2.7 times, 3 times, 3.2 times, 3.5 times, 3.8 times or 4 times, as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0037] Preferably, the reaction temperature in step (1) is 100-140°C, for example, it can be 100°C, 105°C, 110°C, 115°C, 120°C, 125°C, 130°C, 135°C or 140°C, as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0038] Preferably, the reaction time of step (1) is 1-5 h, for example, it can be 1 h, 1.5 h, 2 h, 2.5 h, 3 h, 3.5 h, 4 h, 4.5 h or 5 h, as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0039] Preferably, step (1) specifically includes the following steps:

[0040] (i) dissolving the monomer in a solvent to obtain a first mixed solution;

[0041] (ii) uniformly mixing half of the total mass of the first mixed solution in step (i) with an initiator to obtain a second mixed solution;

[0042] (iii) heating the other half of the total mass of the first mixed solution in step (i) to 100-140° C. and adding the second mixed solution in step (ii) dropwise within 1-5 hours under stirring to obtain an intermediate polymer 1.

[0043] The present invention optimizes the feeding method during the synthesis of the intermediate polymer 1 and adopts a method of mixing the monomer and the initiator in steps. Compared with a method of directly blending the monomer and the initiator, the dispersibility of the obtained water-based polymer dispersant can be significantly improved; at the same time, when it is used in a pigment paste formula to form a coating, it can not only further improve the stability of the pigment paste, so that it does not sink to the bottom, does not agglomerate, has a long stable period, and can be stored for a long time; but also can improve the compatibility of the pigment paste with the polyurethane emulsion.

[0044] Preferably, the reaction temperature in step (2) is 120-180°C, for example, it can be 120°C, 130°C, 140°C, 150°C, 160°C, 170°C or 180°C, as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0045] Preferably, the reaction time of step (2) is 2-6 h, for example, it can be 2 h, 2.5 h, 3 h, 3.5 h, 4 h, 4.5 h, 5 h, 5.5 h or 6 h, as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0046] Preferably, the reaction in step (2) is terminated by determining that the acid value is less than 2.0 mgKOH / g (for example, it may be 0.2 mgKOH / g, 0.4 mgKOH / g, 0.8 mgKOH / g, 1 mgKOH / g, 1.2 mgKOH / g, 1.4 mgKOH / g, 1.6 mgKOH / g or 1.8 mgKOH / g, etc.), thereby obtaining an intermediate polymer 2.

[0047] In the present invention, by limiting the acid value to less than 2.0 mgKOH / g, it is helpful to regulate the degree of imidization ring-closing reaction, thereby helping to improve the dispersion stability of the obtained aqueous polymer dispersant to the pigment, and the compatibility of the pigment paste with the polyurethane emulsion.

[0048] Preferably, the reaction in step (3) is carried out under the action of a catalyst.

[0049] Preferably, the amount of the catalyst added is 5-15% of the mass of the monoisocyanate, for example, it can be 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14% or 15%, as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0050] Preferably, the catalyst comprises any one of triethylamine, tri-n-propylamine, triisopropylamine, diethylenediamine or triethylenediamine, or a combination of at least two thereof.

[0051] Preferably, the reaction temperature in step (3) is 60-90°C, for example, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C or 90°C, as well as specific values ​​between the above-mentioned points. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific points included in the range.

[0052] Preferably, the reaction time of step (3) is 2-5 h, for example, it can be 2 h, 2.5 h, 3 h, 3.5 h, 4 h, 4.5 h or 5 h, as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0053] In a third aspect, the present invention provides a coating, comprising the aqueous polymer dispersant described in the first aspect.

[0054] When the aqueous polymer dispersant provided by the present invention is applied to aqueous concentrated color pastes such as carbon black, toluidine purple or toluidine red pigment to form coatings, the stability of the pigment color paste can be well improved, and the compatibility of the color paste with aqueous polyurethane emulsion resin can also be improved.

[0055] Compared with the prior art, the present invention has at least the following beneficial effects:

[0056] The aqueous polymer dispersant provided by the present invention has the characteristics of high molecular weight, multiple types of anchoring groups and abundant solvated segments in the molecular structure by selecting a combination of monomer a, monomer b and monomer c, and matching raw materials amino alcohol and isocyanate, so that it has excellent wetting, dispersing and stabilizing properties. When applied to a pigment paste formula to form a coating, the stability of the pigment paste can be significantly improved, so that the pigment paste does not sink to the bottom and does not agglomerate, has a long stable period and can be stored for a long time; and the compatibility of the pigment paste with the aqueous polyurethane emulsion can be improved, thereby further expanding the scope of application. DETAILED DESCRIPTION

[0057] For the convenience of understanding the present invention, the present invention lists the following embodiments. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0058] Example 1

[0059] This embodiment provides an aqueous polymer dispersant, and the preparation method thereof comprises the following steps:

[0060] (1) 2-Methylstyrene (236.36 g, 2 mol), maleic anhydride (270.18 g, 3 mol), and 2-methyl-1-vinylimidazole (108.14 g, 1 mol) were dissolved in diethylene glycol dimethyl ether (2.4 kg) to obtain a first mixed solution.

[0061] (2) Half of the total mass of the first mixed solution in step (1) was mixed evenly with benzoyl peroxide (20 g) to obtain a second mixed solution.

[0062] (3) Add the other half of the total mass of the first mixed solution in step (1) into a reaction flask equipped with a stirring, nitrogen, temperature measuring and drop-adding device. Raise the temperature to 120° C. and, under stirring, dropwise add the second mixed solution in step (2) within 3 hours to obtain an intermediate polymer 1.

[0063] (4) The intermediate polymer 1 described in step (3) was heated to 150° C., and then tris(hydroxymethyl)aminomethane (363.42 g, 3 mol) was added and reacted for 4 h. The acid value before and after detection was 1.5 mgKOH / g to determine that the reaction was terminated, thereby obtaining the intermediate polymer 2.

[0064] (5) The intermediate polymer 2 described in step (4) was cooled to 75°C, and n-butyl isocyanate (892.17 g, 9 mol) and triethylamine (90 g) were added in sequence, and the reaction was kept warm for 3.5 hours. The solvent was evaporated under reduced pressure to obtain the polymer dispersant. The weight average molecular weight of the polymer was 57631 g / mol.

[0065] Example 2

[0066] This embodiment provides an aqueous polymer dispersant, and the preparation method thereof comprises the following steps:

[0067] (1) α-Methylstyrene (472.72 g, 4 mol), maleic anhydride (490.3 g, 5 mol), and 1-vinylimidazole (282.33 g, 3 mol) were dissolved in ethylene glycol dimethyl ether (2.5 kg) to obtain a first mixed solution.

[0068] (2) Mix half of the total mass of the first mixed solution in step (1) with methyl ethyl ketone peroxide (13 g) to obtain a second mixed solution.

[0069] (3) Add the other half of the total mass of the first mixed solution in step (1) into a reaction flask equipped with a stirring, nitrogen, temperature measuring and dropping device. Raise the temperature to 140° C. and, under stirring, dropwise add the second mixed solution in step (2) within 1 hour to obtain an intermediate polymer 1.

[0070] (4) The intermediate polymer 1 described in step (3) was heated to 180° C., and then 2-amino-2-methyl-1,3-propanediol (525.7 g, 5 mol) was added and reacted for 2 h. The acid value was detected to be 1.3 mgKOH / g to obtain the intermediate polymer 2.

[0071] (5) The intermediate polymer 2 described in step (4) was cooled to 90°C, tert-butyl isocyanate (831.3 g, 10 mol) and triisopropylamine (51 g) were added in sequence, and the mixture was kept warm for 2 hours. The solvent was evaporated under reduced pressure to obtain the polymer dispersant. The weight average molecular weight of the polymer was 97421 g / mol.

[0072] Example 3

[0073] This embodiment provides an aqueous polymer dispersant, and the preparation method thereof comprises the following steps:

[0074] (1) Styrene (416.6 g, 4 mol), itaconic anhydride (673.08 g, 6 mol), and 5-vinylimidazole (282.33 g, 3 mol) were dissolved in triethylene glycol dimethyl ether (5.5 kg) to obtain a first mixed solution.

[0075] (2) Half of the total mass of the first mixed solution in step (1) was mixed with 2,2-bis(tert-butyl peroxide)butane (68 g) to obtain a second mixed solution.

[0076] (3) Add the other half of the total mass of the first mixed solution in step (1) into a reaction flask equipped with a stirring, nitrogen, temperature measuring and drop-adding device. Raise the temperature to 100° C. and, under stirring, dropwise add the second mixed solution in step (2) within 5 hours to obtain an intermediate polymer 1.

[0077] (4) The intermediate polymer 1 described in step (3) was heated to 120° C., and then monoethanolamine (366.48 g, 6 mol) was added and reacted for 6 h. The acid value was detected to be 1.8 mgKOH / g, thereby obtaining the intermediate polymer 2.

[0078] (5) The intermediate polymer 2 described in step (4) was cooled to 60°C, and ethyl isocyanate (426.48 g, 6 mol) and triethylenediamine (60 g) were added in sequence, and the mixture was kept warm for 5 hours. The solvent was evaporated under reduced pressure to obtain the polymer dispersant. The weight average molecular weight of the polymer was 13954 g / mol.

[0079] Example 4

[0080] This embodiment provides an aqueous polymer dispersant, which differs from Embodiment 1 in that the 2-methyl-1-vinylimidazole (108.14 g, 1 mol) in step (1) is replaced by 2-methyl-1-vinylimidazole (54.07 g, 0.5 mol), so that the molar ratio of monomer a, monomer b, and monomer c is 2:3:0.5, and other raw materials, contents, and preparation methods are the same as those in Embodiment 1.

[0081] Example 5

[0082] This embodiment provides an aqueous polymer dispersant, which differs from Embodiment 1 in that the 2-methylstyrene (236.36 g, 2 mol) in step (1) is replaced by 2-methylstyrene (590.9 g, 5 mol), and the 2-methyl-1-vinylimidazole (108.14 g, 1 mol) is replaced by 2-methyl-1-vinylimidazole (324.42 g, 3 mol), so that the molar ratio of monomer a, monomer b, and monomer c is 5:3:3, and other raw materials, contents and preparation methods are the same as those in Embodiment 1.

[0083] Example 6

[0084] This embodiment provides an aqueous polymer dispersant, which differs from Example 1 in that the 2-methyl-1-vinylimidazole (108.14 g, 1 mol) in step (1) is replaced by 2-methyl-1-vinylimidazole (270.35 g, 2.5 mol), so that the molar ratio of monomer a, monomer b, and monomer c is 2:3:2.5, and other raw materials, contents and preparation methods are the same as those in Example 1.

[0085] Example 7

[0086] This embodiment provides an aqueous polymer dispersant, and the preparation method thereof comprises the following steps:

[0087] (1) 2-Methylstyrene (236.36 g, 2 mol), maleic anhydride (270.18 g, 3 mol), and 2-methyl-1-vinylimidazole (108.14 g, 1 mol) were dissolved in diethylene glycol dimethyl ether (2.8 kg) and added to a reaction flask equipped with a stirring, nitrogen, temperature measuring, and dropping device. The temperature was raised to 120° C., and benzoyl peroxide (20 g) was added dropwise over 3 hours under stirring to obtain an intermediate polymer 1.

[0088] (2) The intermediate polymer 1 described in step (1) was heated to 150° C., and then tris(hydroxymethyl)aminomethane (363.42 g, 3 mol) was added and reacted for 4 h. The acid value was detected to be 0.9 mgKOH / g, thereby obtaining the intermediate polymer 2.

[0089] (3) The intermediate polymer 2 described in step (2) was cooled to 75°C, and n-butyl isocyanate (892.17 g, 9 mol) and triethylamine (90 g) were added in sequence, and the mixture was kept warm for 3.5 hours. The solvent was evaporated under reduced pressure to obtain the polymer dispersant. The weight average molecular weight of the polymer was 84531 g / mol.

[0090] Example 8

[0091] This embodiment provides an aqueous polymer dispersant, which differs from Embodiment 1 in that in step (4), when the acid value is detected to be 3.0 mgKOH / g, an intermediate polymer 2 is obtained, and other raw materials, contents and preparation methods are the same as those in Embodiment 1.

[0092] Comparative Example 1

[0093] This comparative example provides an aqueous polymer dispersant, which differs from Example 1 in that monomer a is not added, and its reduced content is distributed to monomers b and c in a molar ratio, and other raw materials, contents and preparation methods are the same as those in Example 1.

[0094] Comparative Example 2

[0095] This comparative example provides an aqueous polymer dispersant, which differs from Example 1 in that monomer b is not added, and its reduced content is distributed to monomers a and c in a molar ratio, and other raw materials, contents and preparation methods are the same as those in Example 1.

[0096] Comparative Example 3

[0097] This comparative example provides an aqueous polymer dispersant, which differs from Example 1 in that monomer c is not added, and its reduced content is distributed to monomers a and b in a molar ratio, and other raw materials, contents and preparation methods are the same as those in Example 1.

[0098] Comparative Example 4

[0099] This comparative example provides a commercially available product, a condensate of octylphenol and ethylene oxide (purchased from Hai'an Petrochemical Plant in Jiangsu Province, with a brand name of OP-10).

[0100] Application Examples

[0101] By laboratory sand milling, according to the total amount of slurry formula of 100g, add water-based polymer dispersant, water, and organic pigment (Pigment Red 13) in sequence; after stirring evenly, add 200g of zirconium beads with a particle size of 1.2-1.4mm, seal in a glass jar, shake for 8 hours, and filter to obtain the color paste.

[0102] The formula of the color paste is shown in Table 1.

[0103] Table 1

[0104]

[0105] The color pastes obtained in Application Examples 1-8 and Comparative Examples 1-4 were compounded with polyurethane emulsion (F0410, Shenzhen Yoshida Chemical Co., Ltd.) at a mass ratio of 1:1, and the resulting solution was subjected to a 50°C / 14-day accelerated test to detect changes in viscosity before and after to determine the compatibility between the color paste and the emulsion.

[0106] The performance test methods / standards are as follows:

[0107] (1) Viscosity: measured using NDJ-1B rotational viscometer, Shanghai Changji Geological Instrument Co., Ltd.; “-” indicates that the viscosity is too high or flocculated and cannot be measured;

[0108] (2) Particle size: tested using BT-90 laser particle size analyzer, Dandong Better Instrument Co., Ltd.; “\” means no fluidity and cannot be tested;

[0109] (3) Storage stability: Store at 50°C for 14 days, observe the state of the color paste and emulsion, and re-measure the color paste particle size and emulsion viscosity.

[0110] The test results are shown in Table 2.

[0111] Table 2

[0112]

[0113] The test results show that:

[0114] (1) It can be seen from Application Examples 1 to 3 that the present invention can obtain an aqueous polymer dispersant with excellent dispersibility by compounding a monomer of a specific structure with an initiator, amino alcohol and monoisocyanate, and applying the aqueous polymer dispersant to a pigment paste formula to form a coating can improve the stability of the pigment paste and the compatibility of the pigment paste with the polyurethane emulsion.

[0115] (2) By comparing Application Example 1 with Application Examples 4-6, it can be seen that the molar ratios of monomer a, monomer b, and monomer c in Application Examples 4 and 5 all exceed (2-4):(3-6):(1-3). After being stored at 50°C for 14 days, the viscosity values ​​of the corresponding color pastes and emulsions could not be measured, the viscosity changed greatly, and the stability of the pigment color paste and its compatibility with the polyurethane emulsion were poor. Furthermore, the molar ratios of monomer a, monomer b, and monomer c in Application Example 6 met (2-4):(3-6):(1-3), but the molar amount of monomer c was higher than that of monomer a. Its initial color paste particle size, color paste viscosity, and emulsion viscosity were significantly higher than those in Application Example 1, and its color paste particle size, color paste viscosity, and emulsion viscosity measured after being stored at 50°C for 14 days were significantly increased, that is, compared with Application Example 1, its dispersion effect and compatibility were reduced. Therefore, it is shown that the present invention can balance and control the hydrophilicity and lipophilicity of the obtained polymer as a whole by further limiting the molar ratio of monomer a, monomer b, and monomer c in the specific monomers, so that it is more suitable for the dispersion, wetting and stability of the pigment paste; further, by regulating the molar amounts of monomer a, monomer b, and monomer c to satisfy monomer c < monomer a < monomer b, the dispersion stability of the obtained aqueous polymer dispersant for the pigment, as well as the compatibility of the pigment paste with the polyurethane emulsion can be further improved.

[0116] (3) By comparing Application Example 1 with Application Example 7, it can be seen that the present invention optimizes the feeding method in the synthesis process of the intermediate polymer 1 and adopts a method of mixing the monomer and the initiator in steps. Compared with the method of directly blending the monomer and the initiator, it can significantly reduce the initial values ​​of the color paste particle size, color paste viscosity and emulsion viscosity, and has good dispersibility; and the color paste particle size, color paste viscosity and emulsion viscosity measured after storage at 50°C for 14 days change little, with less aggregated particles, excellent pigment dispersion stability, and good compatibility of the pigment paste with the polyurethane emulsion.

[0117] (4) By comparing Application Example 1 with Application Example 8, it can be seen that limiting the acid value to less than 2.0 mgKOH / g during the synthesis of the intermediate polymer 2 is beneficial to improving the dispersion stability of the obtained aqueous polymer dispersant for the pigment, as well as the compatibility of the pigment paste with the polyurethane emulsion.

[0118] (5) By comparing Application Example 1 with Comparative Application Examples 1-3, it can be seen that the pigment pastes in Comparative Application Examples 1 and 3 do not have fluidity and cannot be used. The initial pigment paste particle size, pigment paste viscosity and emulsion viscosity in Comparative Application Example 2 are significantly higher than those in Application Example 1, and the pigment dispersion effect is poor; and the pigment paste does not have fluidity after being stored at 50°C for 14 days and cannot be used. Therefore, it is shown that the present invention can obtain an aqueous polymer dispersant with excellent dispersibility by compounding monomer a, monomer b and monomer c of a specific structure, and apply it to the pigment paste formula to form a coating, which can improve the stability of the pigment paste and the compatibility of the pigment paste with the polyurethane emulsion; when any of the monomers is missing, it cannot achieve the technical effect of improving the pigment dispersibility and good compatibility with the emulsion.

[0119] (6) It can be seen from the comparison between Application Example 1 and Comparative Application Example 4 that the aqueous polymer dispersant provided by the present invention has better technical effects than the product OP-10 in the prior art.

[0120] In summary, the aqueous polymer dispersant provided by the present invention has excellent dispersing properties. When applied to the pigment paste formula to form a coating, compared with traditional low molecular weight surfactants, it can not only significantly improve the stability of the pigment, so that it does not sink to the bottom, does not agglomerate, has a long stability period, and can be stored for a long time; it can also improve the compatibility of the pigment paste with the polyurethane emulsion, further expanding its scope of application.

[0121] The applicant declares that the above is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention shall fall within the protection scope and disclosure scope of the present invention.

Claims

1. An aqueous polymer dispersant, characterized in that The raw materials for preparing the waterborne polymer dispersant include monomers, initiators, amino alcohols and monoisocyanates; The monomers include monomer a, monomer b, and monomer c; The monomer a comprises a vinyl aromatic compound; the monomer b comprises an ethylenically unsaturated carboxylic acid anhydride; and the monomer c comprises an alkenyl imidazole compound.

2. The aqueous polymer dispersant according to claim 1, characterized in that The weight average molecular weight of the aqueous polymer dispersant is 10000-100000 g / mol.

3. The aqueous polymer dispersant according to claim 1 or 2, characterized in that The molar ratio of monomer a, monomer b and monomer c is (2-4):(3-6):(1-3); Preferably, the vinyl aromatic compound comprises styrene and / or methylstyrene; Preferably, the methylstyrene includes any one of 2-methylstyrene, 3-methylstyrene, 4-methylstyrene or α-methylstyrene, or a combination of at least two thereof; Preferably, the ethylenically unsaturated carboxylic anhydride comprises an unsaturated succinic anhydride compound; Preferably, the unsaturated succinic anhydride compound comprises maleic anhydride and / or itaconic anhydride; Preferably, the alkenyl imidazole compound comprises a vinyl imidazole compound; Preferably, the vinyl imidazole compound includes any one of 1-vinylimidazole, 5-vinylimidazole, 2-vinylimidazole or 2-methyl-1-vinylimidazole, or a combination of at least two thereof.

4. The aqueous polymer dispersant according to any one of claims 1 to 3, characterized in that The amount of the initiator added is 1-5% of the monomer mass; Preferably, the initiator comprises a peroxide initiator; Preferably, the peroxide initiator comprises any one or a combination of at least two of benzoyl peroxide, tert-butyl benzoyl peroxide, methyl ethyl ketone peroxide, dicumyl peroxide, di-tert-butyl peroxide or 2,2-bis(tert-butyl peroxide)butane.

5. The aqueous polymer dispersant according to any one of claims 1 to 4, characterized in that The molar ratio of the amino alcohol to monomer b is 1:1; Preferably, the amino alcohol comprises a primary amino alcohol; Preferably, the primary amine alcohol comprises any one or a combination of at least two of tris(hydroxymethyl)aminomethane, 2-amino-2-methyl-1,3-propanediol, 2-amino-2-ethyl-1,3-propanediol, 2-amino-1,3-propanediol, monoethanolamine, n-propanol, isopropanolamine, 2-amino-2-methyl-1-propanol, 1-amino-2-butanol or 2-amino-1-butanol; Preferably, the molar ratio of the monoisocyanate to the monomer b is (1-3):1; Preferably, the monoisocyanate includes any one of n-butyl isocyanate, isobutyl isocyanate, tert-butyl isocyanate, n-propyl isocyanate, isopropyl isocyanate or ethyl isocyanate, or a combination of at least two thereof.

6. A method for preparing an aqueous polymer dispersant according to any one of claims 1 to 5, characterized in that: The preparation method comprises the following steps: (1) reacting a monomer and an initiator to obtain an intermediate polymer 1; (2) reacting the amino alcohol with the intermediate polymer 1 of step (1) to obtain an intermediate polymer 2; (3) reacting the monoisocyanate with the intermediate polymer 2 of step (2) to obtain the aqueous polymer dispersant.

7. The method for preparing an aqueous polymer dispersant according to claim 6, characterized in that: The reaction in step (1) is carried out in a solvent; Preferably, the solvent comprises an inert solvent; Preferably, the inert solvent includes any one of diethylene glycol dimethyl ether, ethylene glycol dimethyl ether or triethylene glycol dimethyl ether, or a combination of at least two thereof; Preferably, the amount of the solvent added is 2-4 times the mass of the monomer; Preferably, the reaction temperature in step (1) is 100-140°C; Preferably, the reaction time in step (1) is 1-5h; Preferably, step (1) specifically includes the following steps: (i) dissolving the monomer in a solvent to obtain a first mixed solution; (ii) uniformly mixing half of the total mass of the first mixed solution in step (i) with an initiator to obtain a second mixed solution; (iii) heating the other half of the total mass of the first mixed solution in step (i) to 100-140° C. and adding the second mixed solution in step (ii) dropwise within 1-5 hours under stirring to obtain an intermediate polymer 1.

8. The method for preparing an aqueous polymer dispersant according to claim 6 or 7, characterized in that: The reaction temperature in step (2) is 120-180°C; Preferably, the reaction time in step (2) is 2-6 hours.

9. The method for preparing an aqueous polymer dispersant according to any one of claims 6 to 8, characterized in that: The reaction in step (3) is carried out under the action of a catalyst; Preferably, the catalyst is added in an amount of 5-15% of the mass of the monoisocyanate; Preferably, the catalyst comprises any one of triethylamine, tri-n-propylamine, triisopropylamine, diethylenediamine or triethylenediamine, or a combination of at least two thereof; Preferably, the reaction temperature in step (3) is 60-90°C; Preferably, the reaction time in step (3) is 2-5 h.

10. A coating, characterized in that: The coating comprises the aqueous polymer dispersant according to any one of claims 1 to 5.

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