A nonionic water-based polyamide wax rheological additive and preparation method thereof

Abstract

The present invention relates to the technical field of rheological additives, and in particular to a nonionic water-based polyamide wax rheological additive and a preparation method thereof, comprising the following steps: S1, uniformly mixing fatty acids and polyetheramines, adding a small amount of composite catalyst, controlling the temperature reaction, and obtaining a pre-reaction product; S2, controlling the reaction conditions, adding the composite catalyst, continuing the reaction, and performing reduced pressure distillation after the reaction is completed to obtain polyamide wax; S3, adding the polyamide wax to a solvent while stirring, and stirring to obtain a polyamide wax slurry; S4, obtaining the product after activation. The preparation process of the present invention avoids the use of amine neutralizers in traditional technologies, and effectively reduces the presence of unstable factors in the coating system. While not requiring the additional addition of a heat stabilizer, the thermal stability of the coating system can be improved, the occurrence of post-thickening and gelling phenomena can be reduced, and the potential risks of the rheological additive during use can be reduced.

Description

Technical Field

[0001] The invention relates to the technical field of rheological additives, and in particular to a nonionic waterborne polyamide wax rheological additive and a preparation method thereof. Background Art

[0002] Traditional solvent-based paints contain a large amount of organic solvents, which pose a threat to the construction environment and human health, and their emissions also pollute the environment. At present, architectural coatings have basically achieved water-based, and the water-based development momentum in industrial paints and wood paints is also strong. In the formulation of water-based industrial paints, rheological additives play a vital role, which can adjust the rheological properties of the paint and ensure the stability and uniformity during the construction process. The rheological additives currently used in the market mainly include fumed silica, organic bentonite, active nano-light calcium carbonate, hydrogenated castor oil, polyamide wax, modified urea, etc. The rheological additives used in water-based industrial paints generally include polyurethane associative rheological additives, acrylic alkali thickening rheological additives, water-based clay, cellulose, polyamide wax slurry and other products. Among them, water-based polyamide wax slurry has excellent anti-settling and anti-sagging properties, especially in emulsions containing cosolvents and water-soluble systems. However, traditional polyamide wax rheological additives are mainly suitable for oily systems and solvent-free systems, which cannot meet the needs of water-based coatings. Non-ionic water-based polyamide wax rheological additive introduces hydrophilic groups into the polyamide wax molecular chain, giving it good water dispersibility and stability, retaining the original excellent properties of polyamide wax, and making it suitable for water-based coating systems, broadening the application range of polyamide wax.

[0003] In the traditional polyamide wax synthesis process, the first step is to generate low molecular weight polyamide by condensation reaction of monoacid and diamine. The acid is usually excessive, resulting in some unreacted terminal carboxyl groups in the structure; the second step is to add an amine neutralizer to the product in an aqueous system to make the product have a certain hydrophilicity, so that it swells into a colloid in a mixed solvent of aqueous and alcohol ethers. This colloid has certain thixotropic properties and can be used as a rheological additive in water-based coatings. However, the use of amine neutralizers may lead to a decrease in the stability of the coating system, especially in water-based epoxy systems, where post-thickening and gelation are prone to occur. For example, the invention patent with patent publication number CN112521795A discloses a water-based polyamide wax rheological additive with improved thermal stability and a preparation method thereof, which mainly includes a water-based polyamide wax resin, a thermal stabilizing additive and an amine neutralizer. By introducing a thermally stable additive component in the pulping process, the water-based coating is given excellent heat storage performance, so that the anti-settling and anti-sagging properties of the polyamide wax rheological additive are almost unaffected. However, the use of amine neutralizers in practical applications of this rheological additive will lead to decreased stability of the coating system, post-thickening and even gelation, especially in water-based epoxy systems. Summary of the invention

[0004] In order to solve the problems mentioned in the above background technology, the present invention provides a non-ionic water-based polyamide wax rheological additive and a preparation method thereof.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] A method for preparing a nonionic water-based polyamide wax rheological additive comprises the following steps:

[0007] S1. Evenly mix the fatty acid and the polyetheramine, add 0.1-0.3wt% of a catalyst, control the temperature to react for 1-2h, and perform a pre-reaction to reduce side reactions and improve the efficiency of subsequent condensation reactions to obtain a pre-reaction product;

[0008] S2, controlling the reaction conditions, adding 0.4-1wt% of the catalyst, continuing the condensation reaction of the pre-reaction product to ensure that the reaction is fully carried out, and after the reaction is completed, performing reduced pressure distillation for 2-4h under the conditions of a vacuum degree of 0.08-0.1MPa and a temperature of 150-200°C to remove unreacted raw materials and by-products to obtain polyamide wax;

[0009] S3, adding polyamide wax to the solvent while stirring, the stirring speed is 300-600rpm, the stirring time is 20-60min, to obtain polyamide wax slurry, the solid content of the polyamide wax slurry is 20-25%;

[0010] S4. After the polyamide wax slurry is sealed and packaged, it is placed in a constant temperature room for activation to ensure that the polyamide wax is fully swollen and stable in the mixed solvent. After the activation is completed, a non-ionic water-based polyamide wax rheological additive is obtained.

[0011] Wherein, 0.01-0.05% of dimer acid can be added to the fatty acid, and 0.01-0.05% of diamine can be added to the polyetheramine, including one or more of ethylenediamine, hexamethylenediamine, metaphenylenediamine, and metaphenylenediamine.

[0012] Furthermore, the fatty acid in step S1 is a fatty acid with a carbon chain length of C12-C36, including one or more of oleic acid, dimer acid, 12-hydroxystearic acid, and lauric acid.

[0013] Furthermore, in step S1, the mass ratio of carboxyl group to amino group is (1-1.2):1.

[0014] Furthermore, the temperature in step S1 is 140-160°C.

[0015] Furthermore, the composite catalyst in step S1 or S2 comprises the following steps:

[0016] Add 1-hydroxybenzotriazole and triethyl borate to ethanol, stir at a speed of 100-200 rpm for 10-30 minutes, then add lithium chloride, and heat to 50-60°C using a heating jacket or an oil bath, keep warm and stir at a speed of 300-400 rpm for 2-4 hours, cool to room temperature, filter, wash, and dry at 60°C to constant weight to obtain a composite catalyst.

[0017] Furthermore, the reaction condition in step S2 is heating to 180-230° C. under nitrogen protection.

[0018] Furthermore, in step S3, the solvent consists of deionized water and alcohol ether environmentally friendly solvents, and the specific components are: deionized water accounts for 50-95% of the total solvent, and the alcohol ether environmentally friendly solvent accounts for 5-50% of the total solvent, wherein the alcohol ether environmentally friendly solvent includes one or more of ethanol, isopropanol, propylene glycol monomethyl ether (PM), ethylene glycol butyl ether (BCS), diethylene glycol butyl ether (DB), and ethyl p-N,N-dimethylaminobenzoate (EDB).

[0019] Furthermore, in step S4, the activation temperature is 30-60° C., and the activation time is 24-52 hours.

[0020] Furthermore, the mass ratio of 1-hydroxybenzotriazole, triethyl borate, ethanol and lithium chloride is (0.8-1): (0.2-0.5): 2: (1.2-1.8).

[0021] According to another aspect of the present invention, a non-ionic water-based polyamide wax rheological additive prepared by the above preparation method is provided.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1. Amine neutralizers can cause post-thickening and gelling of the coating system under long-term use, especially in waterborne epoxy systems. The preparation process of the present invention avoids the use of amine neutralizers in traditional technologies, effectively reducing the presence of unstable factors in the coating system. Without the need to add additional heat stabilizers, the thermal stability of the coating system can be improved, the occurrence of post-thickening and gelling can be reduced, and the potential risks of rheological additives during use can be reduced, making the coating safer during use.

[0024] 2. The rheological additive of the present invention can maintain stable performance in more types of coating systems, especially in those coating systems that are sensitive to traditional amine neutralizers, so that the rheological additive has a wider range of applications and can meet the needs of different coating systems.

[0025] 3. Polyetheramine has a multifunctional structure, and its active hydrogen atoms can react effectively with the carboxyl groups in fatty acids, thereby improving the reaction efficiency in the pre-reaction and condensation reaction and reducing the occurrence of side reactions. Compared with the traditional condensation reaction of monobasic acid and diamine, the use of polyetheramine can avoid the problem of excessive acid, reduce the presence of unreacted terminal carboxyl groups, and thus reduce the unstable factors in the coating system.

[0026] 4. In the composite catalyst of the technical solution of the present invention, 1-hydroxybenzotriazole and triethyl borate interact through hydrogen bonds to form an organic framework, and lithium chloride is loaded on the organic framework in the form of microcrystals or ions through electrostatic action or coordination. By adding a small amount of composite catalyst in the pre-reaction stage, the amidation reaction between the fatty acid carboxyl group and the polyetheramine amino group is effectively promoted, and the occurrence of side reactions such as esterification and etherification is reduced, thereby improving the efficiency of the subsequent condensation reaction. In the condensation reaction stage, by controlling the reaction conditions and adding the remaining composite catalyst, the amidation reaction is further promoted, ensuring the full progress of the reaction and the growth of the polyamide wax molecular chain. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0028] Figure 1 It is a flow chart of the preparation method of the present invention. DETAILED DESCRIPTION

[0029] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] Unless otherwise specified, the raw materials used in the present invention are all conventional products purchased from the market, and the molecular weight of the polyetheramine is 2000.

[0031] Preparation Example 1

[0032] The composite catalyst comprises the following steps to prepare:

[0033] 0.8 kg 1-hydroxybenzotriazole and 0.2 kg triethyl borate were added to 2 kg ethanol, stirred at 100 rpm for 10 min, and then 1.2 kg lithium chloride was added. The mixture was heated to 50° C. using a heating jacket, kept warm and stirred at 300 rpm for 2 h, cooled to room temperature, filtered, washed, and dried at 60° C. to constant weight to obtain a composite catalyst.

[0034] Preparation Example 2

[0035] The composite catalyst comprises the following steps to prepare:

[0036] 0.9 kg 1-hydroxybenzotriazole and 0.35 kg triethyl borate were added to 2 kg ethanol, stirred at 150 rpm for 20 min, and then 1.5 kg lithium chloride was added. The mixture was heated to 55° C. in an oil bath, kept warm and stirred at 350 rpm for 3 h, cooled to room temperature, filtered, washed, and dried at 60° C. to constant weight to obtain a composite catalyst.

[0037] Preparation Example 3

[0038] The composite catalyst comprises the following steps to prepare:

[0039] 1 kg 1-hydroxybenzotriazole and 0.5 kg triethyl borate were added to 2 kg ethanol, stirred at 200 rpm for 30 min, and then 1.8 kg lithium chloride was added. The mixture was heated to 60° C. using a heating jacket, kept warm and stirred at 400 rpm for 4 h, cooled to room temperature, filtered, washed, and dried at 60° C. to constant weight to obtain a composite catalyst. Example 1

[0040] A method for preparing a nonionic water-based polyamide wax rheological additive comprises the following steps:

[0041] S1. Mix 1 kg of oleic acid and 1 kg of polyetheramine evenly, add 0.1 wt % of the composite catalyst prepared in Preparation Example 1, control the temperature to 140° C., react for 1 h, and obtain a pre-reaction product;

[0042] S2, heating to 180° C. under nitrogen protection, adding 0.4 wt % of the composite catalyst prepared in Preparation Example 1, continuing to subject the pre-reaction product to condensation reaction, and after the reaction, performing reduced pressure distillation for 2 h at a vacuum degree of 0.08 MPa and a temperature of 150° C. to obtain polyamide wax;

[0043] S3, adding polyamide wax to a solvent of 50% deionized water and 50% ethanol while stirring at a stirring speed of 300 rpm for 20 min to obtain a polyamide wax slurry;

[0044] S4. After the polyamide wax slurry is sealed and packaged, it is placed in a constant temperature room for activation. The activation temperature is 30° C. and the activation time is 24 hours. After the activation is completed, a non-ionic water-based polyamide wax rheological additive is obtained. Example 2

[0045] A method for preparing a nonionic water-based polyamide wax rheological additive comprises the following steps:

[0046] S1, 1.1 kg of dimer acid and 1 kg of polyetheramine were mixed evenly, 0.15 wt% of the composite catalyst prepared in Preparation Example 2 was added, the temperature was controlled to 140° C., and the reaction was performed for 1 h to obtain a pre-reaction product;

[0047] S2, heating to 190° C. under nitrogen protection, adding 0.45 wt % of the composite catalyst prepared in Preparation Example 2, continuing to subject the pre-reaction product to condensation reaction, and after the reaction, performing reduced pressure distillation for 2.5 h under the conditions of a vacuum degree of 0.08 MPa and a temperature of 155° C. to obtain polyamide wax;

[0048] S3, adding polyamide wax to a solvent of 60% deionized water and 40% isopropanol while stirring at a stirring speed of 400 rpm for 30 min to obtain a polyamide wax slurry;

[0049] S4. After the polyamide wax slurry is sealed and packaged, it is placed in a constant temperature room for activation. The activation temperature is 35° C. and the activation time is 26 hours. After the activation is completed, a non-ionic water-based polyamide wax rheological additive is obtained. Example 3

[0050] A method for preparing a nonionic water-based polyamide wax rheological additive comprises the following steps:

[0051] S1. Mix 1 kg of 12-hydroxystearic acid and 1 kg of polyetheramine evenly, add 0.2 wt % of the composite catalyst prepared in Preparation Example 3, control the temperature to 145° C., react for 1.5 h, and obtain a pre-reaction product;

[0052] S2, heating to 195° C. under nitrogen protection, adding 0.5 wt % of the composite catalyst prepared in Preparation Example 3, continuing to subject the pre-reaction product to condensation reaction, and after the reaction, performing reduced pressure distillation for 3 h under the conditions of a vacuum degree of 0.09 MPa and a temperature of 160° C. to obtain polyamide wax;

[0053] S3, adding polyamide wax to a solvent of 65% deionized water and 35% propylene glycol monomethyl ether while stirring at a stirring speed of 400 rpm for 30 min to obtain a polyamide wax slurry;

[0054] S4. After the polyamide wax slurry is sealed and packaged, it is placed in a constant temperature room for activation. The activation temperature is 40° C. and the activation time is 30 hours. After the activation is completed, a non-ionic water-based polyamide wax rheological additive is obtained. Example 4

[0055] A method for preparing a nonionic water-based polyamide wax rheological additive comprises the following steps:

[0056] S1, 1.2 kg of lauric acid and 1 kg of polyetheramine were mixed evenly, 0.25 wt % of the composite catalyst prepared in Preparation Example 1 was added, the temperature was controlled to 150° C., and the reaction was carried out for 1 h to obtain a pre-reaction product;

[0057] S2, heating to 200° C. under nitrogen protection, adding 0.6 wt % of the composite catalyst prepared in Preparation Example 1, continuing to subject the pre-reaction product to condensation reaction, and after the reaction, performing reduced pressure distillation for 3 h under the conditions of a vacuum degree of 0.1 MPa and a temperature of 180° C. to obtain polyamide wax;

[0058] S3, adding polyamide wax to a solvent of 70% deionized water and 30% propylene glycol monomethyl ether while stirring at a stirring speed of 500 rpm for 40 min to obtain a polyamide wax slurry;

[0059] S4. After the polyamide wax slurry is sealed and packaged, it is placed in a constant temperature room for activation. The activation temperature is 50° C. and the activation time is 35 hours. After the activation is completed, a non-ionic water-based polyamide wax rheological additive is obtained. Example 5

[0060] A method for preparing a nonionic water-based polyamide wax rheological additive comprises the following steps:

[0061] S1. Mix 1 kg of oleic acid and 1 kg of polyetheramine evenly, add 0.3 wt % of the composite catalyst prepared in Preparation Example 2, control the temperature to 150° C., react for 2 h, and obtain a pre-reaction product;

[0062] S2, heating to 210° C. under nitrogen protection, adding 0.7 wt % of the composite catalyst prepared in Preparation Example 2, continuing to subject the pre-reaction product to condensation reaction, and after the reaction, performing reduced pressure distillation for 4 h under the conditions of a vacuum degree of 0.1 MPa and a temperature of 180° C. to obtain polyamide wax;

[0063] S3, adding polyamide wax to a solvent of 85% deionized water and 15% ethylene glycol butyl ether while stirring at a stirring speed of 500 rpm for 50 min to obtain a polyamide wax slurry;

[0064] S4. After the polyamide wax slurry is sealed and packaged, it is placed in a constant temperature room for activation. The activation temperature is 50° C. and the activation time is 40 hours. After the activation is completed, a non-ionic water-based polyamide wax rheological additive is obtained. Example 6

[0065] A method for preparing a nonionic water-based polyamide wax rheological additive comprises the following steps:

[0066] S1, 1.2 kg of 12-hydroxystearic acid and 1 kg of polyetheramine were mixed evenly, 0.3 wt % of the composite catalyst prepared in Preparation Example 3 was added, the temperature was controlled to 160 ° C, and the reaction was carried out for 2 hours to obtain a pre-reaction product;

[0067] S2, heating to 220° C. under nitrogen protection, adding 0.8 wt % of the composite catalyst prepared in Preparation Example 3, continuing to subject the pre-reaction product to condensation reaction, and after the reaction, performing reduced pressure distillation for 4 h under the conditions of a vacuum degree of 0.1 MPa and a temperature of 200° C. to obtain polyamide wax;

[0068] S3, adding polyamide wax to a solvent of 90% deionized water and 10% diethylene glycol butyl ether while stirring, at a stirring speed of 600 rpm, stirring for 60 min to obtain polyamide wax slurry;

[0069] S4. After the polyamide wax slurry is sealed and packaged, it is placed in a constant temperature room for activation. The activation temperature is 60° C. and the activation time is 52 hours. After the activation is completed, a non-ionic water-based polyamide wax rheological additive is obtained. Example 7

[0070] A method for preparing a nonionic water-based polyamide wax rheological additive comprises the following steps:

[0071] S1. Evenly mix 1 kg of 12-hydroxystearic acid and 1 kg of polyetheramine, add 0.1 wt % of the composite catalyst prepared in Preparation Example 1, control the temperature to 160° C., react for 12 h, and obtain a pre-reaction product;

[0072] S2, heating to 230° C. under nitrogen protection, adding 1 wt % of the composite catalyst prepared in Preparation Example 1, continuing to subject the pre-reaction product to condensation reaction, and after the reaction, performing reduced pressure distillation for 4 h under the conditions of a vacuum degree of 0.1 MPa and a temperature of 200° C. to obtain polyamide wax;

[0073] S3, adding polyamide wax to a solvent of 95% deionized water and 5% ethyl p-N,N-dimethylaminobenzoate while stirring at a stirring speed of 600 rpm for 60 min to obtain a polyamide wax slurry;

[0074] S4. After the polyamide wax slurry is sealed and packaged, it is placed in a constant temperature room for activation. The activation temperature is 60° C. and the activation time is 52 hours. After the activation is completed, a non-ionic water-based polyamide wax rheological additive is obtained.

[0075] Comparative Example 1

[0076] The difference between this comparative example and Example 1 is that 1-hydroxybenzotriazole is added instead of the composite catalyst, and the remaining steps are the same as those in Example 1.

[0077] Comparative Example 2

[0078] The difference between this comparative example and Example 2 is that triethyl borate is added instead of the composite catalyst, and the remaining steps are the same as those in Example 2.

[0079] Comparative Example 3

[0080] The difference between this comparative example and Example 3 is that lithium chloride is added instead of the composite catalyst, and the remaining steps are the same as those in Example 3.

[0081] Comparative Example 4

[0082] The difference between this comparative example and Example 4 is that no catalyst is added, and the remaining steps are the same as those of Example 4.

[0083] Comparative Example 5

[0084] The difference between this comparative example and Example 5 is that ethylenediamine is used instead of polyetheramine, and the remaining steps are the same as those in Example 5.

[0085] The rheological additives prepared in Examples 1-7 and Comparative Examples 1-5 were added to the main paint formula of a two-component waterborne epoxy coating to obtain samples. The formula components are shown in Table 1. The samples were dispersed at a high speed of 1000 rpm for 30 minutes to test the rheological properties and stability of the products.

[0086] Table 1. Two-component waterborne epoxy coating main paint formula

[0087] Components Added amount (g) Barium sulfate 5.00 Dispersants 0.70 Wetting Agents 0.30 Waterborne epoxy emulsion 19.00 Solvent PM 2.30 Deionized water 68.70 Titanium dioxide 1.00 Prepared rheological additive 3.00

[0088] The initial viscosity of each sample was measured using a viscometer and the data was recorded. All samples were placed in a constant temperature storage box and stored at 55°C for 7 days for a hot storage experiment. After the storage, the samples were taken out and the viscosity was measured again using a viscometer. For each sample, the difference between the viscosity after storage and the initial viscosity was calculated, and the viscosity increase rate was calculated. Viscosity increase rate = (viscosity after storage - initial viscosity) / initial viscosity × 100%. The results are shown in Table 2:

[0089] Table 2. Thermal storage test results

[0090] serial number Initial viscosity (mPa·s) Viscosity after storage (mPa·s) Viscosity increase rate (%) Example 1 12658 13016 2.83 Example 2 12635 12989 2.80 Example 3 12388 12731 2.77 Example 4 12578 12923 2.74 Example 5 12641 13034 3.11 Example 6 12648 13101 3.58 Example 7 12615 12954 2.69 Comparative Example 1 12654 12698 3.52 Comparative Example 2 12642 13674 8.23 Comparative Example 3 12749 13348 4.76 Comparative Example 4 12691 14117 11.24 Comparative Example 5 12669 14044 10.85

[0091] With reference to GB / T 19250-2013 "Polyurethane Waterproof Coating", the two-component waterborne epoxy coatings prepared in Examples 5-7 and Comparative Examples 1-3 were scraped onto the template three times to a specified thickness of (1.5±0.2) mm. The coatings were cured for 96 h under standard conditions [temperature (23±2)°C, relative humidity (50±10)%], then demoulded, and the coatings were turned over and cured for another 72 h to obtain waterproof coatings. The basic properties were tested, and the results are shown in Table 3:

[0092] Table 3. Basic properties of Examples 5-7 and Comparative Examples 6-8

[0093] project Example 5 Example 6 Example 7 Comparative Example 1 Comparative Example 2 Comparative Example 3 Solid content / % 112.5 117.8 108.8 93.5 94.7 95.3 Surface drying time / h 10 10 11 10 10 12 Drying time / h 18 19 18 20 19 21 Leveling (20min) No obvious tooth marks No obvious tooth marks No obvious tooth marks Slight tooth marks Obvious tooth marks Obvious tooth marks Tensile strength / MPa 28.2 27.5 27.6 26.2 26.0 6.1 Elongation at break / % 263 268 256 283 287 422 Tear strength / (N / mm) 49 53 52 36 40 21 Low temperature bending (-35℃) No cracks No cracks No cracks Slight cracks Slight cracks Severe cracks Water-tightness (0.3 MPa, 120 min) impermeable impermeable impermeable permeable impermeable permeable Heating expansion / % -2.5 -3.1 0.4 1.3 -1.5 6.3 Bond strength / MPa 4.8 5.3 5.6 3.2 3.3 1.8 Water absorption / % 2.6 2.6 2.4 3.0 3.0 8.7

[0094] As shown in Table 2 and Table 3, after being stored at 55°C for 7 days, the viscosity increase rate of Examples 1-7 was between 2.69% and 3.58%. The basic performance of Examples 1-7 met the requirements of GB / T 19250-2013 "Polyurethane Waterproof Coatings" and was better than the indicators specified in the standard, indicating that the rheological additives prepared in Examples 1-7 had good thermal stability and physical properties. In Comparative Examples 1-3, no composite catalyst was added, and the viscosity increase rate increased significantly, reaching 10.57% to 13.58%. Some basic properties did not meet the requirements of the standard, which may be due to the low conversion rate and purity of polyamide wax, which affected its application in waterproof coatings, indicating that the composite catalyst may promote the formation and stability of polyamide wax. In Examples 5-7, 1-hydroxybenzotriazole (HOBt) may form an active ester intermediate with the carboxyl group, thereby reducing the activation energy of the condensation reaction and promoting the reaction.

[0095] In summary, the composite catalyst and polyetheramine play a key role in the preparation of nonionic waterborne polyamide wax rheological additives. Optimizing the reaction conditions can improve the conversion rate and purity of the product, thereby obtaining a rheological additive with excellent performance. Therefore, the obtained rheological additive can show good rheological properties and stability in two-component waterborne epoxy coatings, which helps to improve the overall performance of the coating.

[0096] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A method for preparing a nonionic water-based polyamide wax rheological additive, It is characterized in that The following steps are involved: S1. Mix the fatty acid and the polyetheramine evenly, add 0.1-0.3wt% of the composite catalyst, control the temperature to react for 1-2h, and obtain a pre-reaction product; S2, controlling the reaction conditions, adding 0.4-1wt% of the composite catalyst, and continuing to subject the pre-reaction product to a condensation reaction, and obtaining polyamide wax after the reaction is completed; S3, adding the polyamide wax to the solvent while stirring, stirring for 20-40 minutes to obtain a polyamide wax slurry; S4, after the polyamide wax slurry is sealed and packaged, it is placed in a constant temperature room at 40-55° C. for activation. After the activation is completed, a non-ionic water-based polyamide wax rheological additive is obtained; Among them, the composite catalyst The method comprises the following steps: Add 1-hydroxybenzotriazole and triethyl borate to ethanol, stir at a speed of 100-200 rpm for 10-30 minutes, then add lithium chloride, and heat to 50-60° C. using a heating jacket or an oil bath, keep warm and stir at a speed of 300-400 rpm for 2-4 hours, cool to room temperature, filter, wash, and dry at 60° C. to constant weight to obtain a composite catalyst; In step S1, the fatty acid is a fatty acid with a carbon chain length of C12-C36, including one or more of oleic acid, dimer acid, 12-hydroxystearic acid, and lauric acid, and the molecular weight of the polyetheramine is 2000; The temperature in step S1 is 140-160°C; The reaction conditions in step S2 are heating to 180-230° C. under nitrogen protection; In step S3, the solvent is composed of deionized water and alcohol ether environmentally friendly solvents, and the specific components are: deionized water accounts for 50-95% of the total solvent, and the alcohol ether environmentally friendly solvent accounts for 5-50% of the total solvent, wherein the alcohol ether environmentally friendly solvent includes one or more of ethanol, isopropanol, propylene glycol monomethyl ether, ethylene glycol butyl ether, diethylene glycol butyl ether, and ethyl p-N,N-dimethylaminobenzoate; The mass ratio of 1-hydroxybenzotriazole, triethyl borate, ethanol and lithium chloride is (0.8-1):(0.2-0.5):2:(1.2-1.8).

2. A method for preparing a nonionic water-based polyamide wax rheological additive according to claim 1, It is characterized in that The mass ratio of fatty acid to polyetheramine in step S1 is (1-1.2):

1.

3. A method for preparing a nonionic water-based polyamide wax rheological additive according to claim 1, It is characterized in that In step S4, the activation temperature is 30-60° C., and the activation time is 24-52 hours.

4. A nonionic water-based polyamide wax rheological additive prepared by the preparation method according to any one of claims 1 to 3.

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