Polyamide anti-settling agent for aqueous systems, and preparation method and application thereof

Abstract

The present application relates to the technical field of anti-sedimentation agent, and discloses a polyamide anti-sedimentation agent for water-based system, a preparation method and application thereof. The polyamide anti-sedimentation agent is obtained by subjecting 2,6-diamino (N,N-dimethyl ethylamine) hexanoic acid amide and diacid monomers to melt polycondensation reaction, and then subjecting the resultant to quaternary ammonium reaction with hydrochloric acid and alkyl glycidyl ether. The side chain of the anti-sedimentation agent is introduced with hydrophilic amide bond, hydroxyl group and quaternary ammonium salt, so that the anti-sedimentation agent has excellent water solubility and is more suitable for water-based emulsion system. The polyamide anti-sedimentation agent contains alkyl long chain, can form hydrophobic association, plays a thickening role, improves the viscosity and thixotropy of the emulsion, firmly fixes the aluminum powder in the network structure formed by the polyamide anti-sedimentation agent, effectively inhibits the aggregation and sedimentation of aluminum powder particles, and exhibits excellent anti-sedimentation effect.

Description

Technical Field

[0001] This invention relates to the field of anti-settling agents, specifically to a polyamide anti-settling agent for aqueous systems, its preparation method, and its application. Background Technology

[0002] Paints and inks typically contain inorganic pigments and fillers. These inorganic particles can settle and stratify during storage or standing, affecting the storage stability and performance of the paints and inks. Therefore, anti-settling agents need to be added to improve the leveling and thixotropy of the system and prevent settling and stratification. Anti-settling agents mainly include fumed silica, bentonite, polyamide wax, and polyethylene wax.

[0003] Polyamide anti-settling agents have good thickening and anti-settling effects, excellent compatibility with resin matrices, and minimal impact on the mechanical properties of resins, making them widely used. However, traditional polyamide waxes have poor water solubility, which hinders their practical application in water-based coatings and inks. CN114163864B discloses a high-solids-content water-based polyamide wax prepared from water-based polyamide wax resin, organic amines, and surfactants. This water-based polyamide wax exhibits good anti-sagging properties, but it does not show good thickening effects, which is detrimental to improving its anti-settling performance. Summary of the Invention

[0004] Technical problem solved: In view of the shortcomings of the prior art, the present invention provides a polyamide anti-settling agent for water-based systems, its preparation method and application, which solves the problems of poor thickening effect and anti-sagging performance of traditional polyamide wax anti-settling agents.

[0005] The technical solution of this invention: A method for preparing a polyamide anti-settling agent for aqueous systems:

[0006] (1) In an ice-water bath, (S)-2,6-di-tert-butoxycarbonylaminohexanoic acid (CAS No. 2483-46-7), N,N-dimethylethylenediamine, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, and 1-hydroxybenzotriazole were added to dichloromethane. The mixture was stirred at 20-30℃ for 12-18 h. After washing with water, the organic layer of dichloromethane was dried with anhydrous sodium sulfate. After filtration, trifluoroacetic acid was added to the filtrate, and the mixture was stirred at 20-30℃ for 4-5 h. After vacuum distillation, the product was added to a saturated sodium bicarbonate solution and extracted with dichloromethane. The organic layer was then separated by vacuum distillation and column chromatography to obtain 2,6-diamino(N,N-dimethylethylamine)hexanoic acid amide. The reaction formula is:

[0007] .

[0008] (2) Add water, 2,6-diamino(N,N-dimethylethylamine)hexanoamide, diacid monomer and antioxidant to the reactor, evacuate and introduce nitrogen gas to carry out the reaction, then depressurize and carry out the prepolymerization reaction, finally evacuate and carry out the polycondensation reaction, cool and discharge the material, wash the product with ethanol, dry it to obtain the polyamide precursor.

[0009] (3) Add polyamide precursor and hydrochloric acid solution to water, stir, then add alkyl glycidyl ether, stir to react, heat to evaporate and remove water until a large amount of precipitate is precipitated, filter, wash the product with ethanol, and dry to obtain a polyamide anti-settling agent for aqueous systems. The reaction formula is:

[0010] .

[0011] Furthermore, in (2), the ratio of (S)-2,6-di-tert-butoxycarbonylaminohexanoic acid, N,N-dimethylethylenediamine, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, and 1-hydroxybenzotriazole is 1 mol: (1-1.2) mol: (1.1-1.2) mol: (1.1-1.2) mol.

[0012] Furthermore, in (2), the ratio of 2,6-diamino(N,N-dimethylethylamine)hexanoic acid amide, diacid monomer, and antioxidant is (0.9-1.2) mol: 1 mol: (0.003-0.004) mol.

[0013] Furthermore, the structural formula of the diacid monomer in (2) is as follows: , where a is 2-6.

[0014] Furthermore, in (2), the reaction temperature is 185-200℃ and the reaction time is 2-3h.

[0015] Furthermore, in (2), the pressure is released to atmospheric pressure, the temperature during the prepolymerization reaction is 230-245℃, and the reaction time is 1-1.5h.

[0016] Furthermore, in (2), the pressure of the reactor is controlled by vacuuming at 100-200 Pa, the temperature during the polycondensation reaction is 230-245 °C, and the reaction time is 3-4 h.

[0017] Furthermore, the concentration of the hydrochloric acid solution in (3) is 3-12 mol / L.

[0018] Furthermore, in (3), the ratio of polyamide precursor to alkyl glycidyl ether is 100g: (0.1-0.3)mol.

[0019] Furthermore, (3) the structural formula of alkyl glycidyl ether is b is 12-18.

[0020] Furthermore, in (3), the reaction temperature is 65-80℃ and the reaction time is 10-16h.

[0021] Furthermore, polyamide anti-settling agents are used in water-based coatings and inks.

[0022] The beneficial technical effects of this invention are as follows: This invention involves a melt polycondensation reaction of 2,6-diamino(N,N-dimethylethylamine)hexanoamide and a diacid monomer to obtain a polyamide precursor. The tertiary amine group of the precursor reacts with hydrochloric acid to form a tertiary amine hydrochloride, which then undergoes a quaternization reaction with alkyl glycidyl ether to obtain a polyamide anti-settling agent. This anti-settling agent not only contains amide bonds in its main molecular chain, but also introduces hydrophilic amide bonds, hydroxyl groups, and quaternary ammonium salts into its side chains, giving it excellent water solubility and making it more suitable for aqueous emulsion systems. This is beneficial for thickening and preventing sedimentation in aqueous emulsions and improving thixotropy.

[0023] The polyamide anti-settling agent of this invention contains long alkyl chains, which can form hydrophobic associations, further thickening the emulsion, increasing viscosity, and improving its thixotropic properties. Simultaneously, the hydroxyl groups and quaternary ammonium salts it contains act as anchoring sites, forming physical and chemical adsorption interactions with the aluminum powder surface. This allows the aluminum powder to be more firmly fixed within the network structure formed by the polyamide anti-settling agent, effectively inhibiting the aggregation and sedimentation of aluminum powder particles, exhibiting excellent anti-settling effects. In practical applications, when the polyamide anti-settling agent is added to water-based emulsion silver paint, there is virtually no aluminum powder sedimentation. The paint film on the panel clearly shows better aluminum powder arrangement, better anti-sagging performance, stronger hiding power, and a more pronounced metallic appearance. Attached Figure Description

[0024] Figure 1 These are images showing the storage stability of water-based emulsion silver paint.

[0025] Figure 2 These are pictures of the paint film of water-based emulsion silver paint. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below. However, it should be understood that the description herein is merely illustrative and not intended to limit the scope of the invention.

[0027] Example 1

[0028] (1) In an ice-water bath, 50 mmol of (S)-2,6-di-tert-butoxycarbonylaminohexanoic acid, 50 mmol of N,N-dimethylethylenediamine, 60 mmol of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and 60 mmol of 1-hydroxybenzotriazole were added to 180 mL of dichloromethane. The mixture was stirred at 20 °C for 18 h. After washing with water, the organic layer of dichloromethane was dried with anhydrous sodium sulfate. After filtration, 60 mL of trifluoroacetic acid was added to the filtrate. The mixture was stirred at 20 °C for 5 h. After vacuum distillation, the product was added to a saturated sodium bicarbonate solution and extracted with dichloromethane. The organic layer was then separated by vacuum distillation and column chromatography to obtain 2,6-diamino(N,N-dimethylethylamine)hexanoic acid amide.

[0029] (2) Add 6 mL of water, 50 mmol of 2,6-diamino(N,N-dimethylethylamine)hexanoamide, 50 mmol of succinic acid, and 0.2 mmol of antioxidant 1010 to the reactor. Evacuate the reactor and introduce nitrogen gas. Heat to 200°C and stir for 2 h. Then depressurize to atmospheric pressure and heat to 240°C for 1.5 h of prepolymerization. Finally, evacuate the reactor and control the pressure to 200 Pa for 3 h of polycondensation. Cool and discharge the product. Wash the product with ethanol and dry to obtain the polyamide precursor.

[0030] (3) Add 150 mL of water, 20 g of polyamide precursor, and 8 mL of 3 mol / L hydrochloric acid solution to a flask equipped with a reflux condenser. Stir for 20 min, add 20 mmol of octadecyl glycidyl ether, heat to 80 °C, stir and react for 10 h, heat to evaporate and remove water until a large amount of precipitate is precipitated, filter and wash the product with ethanol, dry to obtain a polyamide anti-settling agent for aqueous systems.

[0031] Example 2

[0032] (1) In an ice-water bath, 50 mmol of (S)-2,6-di-tert-butoxycarbonylaminohexanoic acid, 60 mmol of N,N-dimethylethylenediamine, 55 mmol of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and 55 mmol of 1-hydroxybenzotriazole were added to 200 mL of dichloromethane. The mixture was stirred at 30 °C for 12 h. After washing with water, the organic layer of dichloromethane was dried with anhydrous sodium sulfate. After filtration, 70 mL of trifluoroacetic acid was added to the filtrate. The mixture was stirred at 30 °C for 4 h. After vacuum distillation, the product was added to a saturated sodium bicarbonate solution and extracted with dichloromethane. The organic layer was then separated by vacuum distillation and column chromatography to obtain 2,6-diamino(N,N-dimethylethylamine)hexanoic acid amide.

[0033] (2) Add 8 mL of water, 60 mmol of 2,6-diamino(N,N-dimethylethylamine)hexanoic acid amide, 50 mmol of 1,8-octanoic acid and 0.15 mmol of antioxidant 1010 to the reactor, evacuate and introduce nitrogen gas, heat to 195°C, stir and react for 3 h, then depressurize to atmospheric pressure, heat to 230°C and carry out prepolymerization reaction for 1 h, finally evacuate and control the reactor pressure to 100 Pa, carry out polycondensation reaction for 4 h, cool and discharge the material, wash the product with ethanol, dry and obtain polyamide precursor.

[0034] (3) Add 200 mL of water, 20 g of polyamide precursor, and 4 mL of 12 mol / L hydrochloric acid solution to a flask equipped with a reflux condenser. Stir for 30 min, add 40 mmol of dodecyl glycidyl ether, heat to 65 °C, stir and react for 16 h, heat to evaporate and remove water until a large amount of precipitate is precipitated, filter, wash the product with ethanol, dry, and obtain the polyamide anti-settling agent for aqueous systems.

[0035] Example 3

[0036] (1) Add 6 mL of water, 45 mmol of 2,6-diamino(N,N-dimethylethylamine)hexanoic acid amide (prepared from Example 1), 50 mmol of 1,6-adipic acid, and 0.15 mmol of antioxidant 1010 to the reactor. Evacuate the reactor and introduce nitrogen gas. Heat to 185°C and stir for 3 h. Then depressurize to atmospheric pressure and heat to 245°C for 1.5 h of prepolymerization. Finally, evacuate the reactor and control the pressure to 100 Pa for 3 h of polycondensation. Cool and discharge the product. Wash the product with ethanol and dry to obtain the polyamide precursor.

[0037] (2) Add 200 mL of water, 20 g of polyamide precursor, and 6 mL of 12 mol / L hydrochloric acid solution to a flask equipped with a reflux condenser. Stir for 30 min, add 60 mmol of dodecyl glycidyl ether, heat to 80 °C, stir and react for 12 h, heat to evaporate and remove water until a large amount of precipitate is precipitated, filter and wash the product with ethanol to obtain a polyamide anti-settling agent for aqueous systems.

[0038] Comparative Example 1 uses a polyamide precursor (prepared from Example 1) as an anti-settling agent.

[0039] Comparative Example 2

[0040] (1) Add 20g of polyamide precursor (prepared in Example 1) and 8mL of 3mol / L hydrochloric acid solution to 150mL of water, stir for 20min, add 20mmol of propylene oxide, heat to 80℃, stir and react for 10h, heat to evaporate water, wash the product with ethanol, dry, and obtain polyamide anti-settling agent.

[0041] Comparative Example 3

[0042] (1) Add 6 mL of water, 50 mmol of hexamethylenediamine, 50 mmol of succinic acid and 0.2 mmol of antioxidant 1010 to the reactor, evacuate and introduce nitrogen, heat to 200°C, stir and react for 2 h, then depressurize to atmospheric pressure, heat to 240°C, carry out prepolymerization reaction for 1.5 h, finally evacuate and control the reactor pressure to 200 Pa, carry out polycondensation reaction for 3 h, cool and discharge the material, wash the product with ethanol, dry, and obtain polyamide precursor.

[0043] (2) Add 150 mL of water, 20 g of polyamide precursor, and 8 mL of 3 mol / L hydrochloric acid solution to a flask equipped with a reflux condenser. Stir for 20 min, add 20 mmol of octadecyl glycidyl ether, heat to 80 °C, stir for 10 h, heat to evaporate water until a large amount of precipitate is precipitated, filter, wash the product with ethanol, and dry to obtain polyamide anti-settling agent.

[0044] Comparative Example 4 used commercially available polyamide wax 7120 (Foshan Qianyou Chemical Co., Ltd.) as an anti-settling agent.

[0045] 80g of water-based acrylic emulsion (Golden Cluster 5811), 0.5g of N,N-dimethylethanolamine, 13.1g of water, 0.2g of wetting agent Golden Cluster 127, 0.2g of leveling agent Golden Cluster 387, and 6g of water-based aluminum paste were mixed and stirred for 30 minutes to obtain a blank control of the water-based emulsion silver paint. The state of the silver paint was observed after 3 days. The silver paint was then applied to the substrate surface, dried, and cured to form a paint film, and the aluminum powder arrangement effect was observed.

[0046] 80g of waterborne acrylic emulsion (Golden Cluster 5811), 0.5g of N,N-dimethylethanolamine, 13.1g of water, 0.2g of wetting agent Golden Cluster 127, 0.2g of leveling agent Golden Cluster 387, 6g of waterborne aluminum paste, and 2g of anti-settling agent (prepared from each example and comparative example, respectively) were mixed and stirred for 30 minutes to obtain waterborne emulsion silver paint. The silver paint was left to stand for 3 days, and its state was observed. The silver paint was then applied to the surface of a substrate, dried, and cured to form a paint film. The arrangement effect of the aluminum powder was observed.

[0047] The viscosity of the water-based emulsion silver paint was tested using a rotational viscometer at a speed of 30 rpm.

[0048] Table 1. Viscosity and thickening properties test of water-based emulsion silver paint

[0049] Viscosity (mPa·s) Example 1 939 Example 2 1467 Example 3 1290 Blank control 129 Comparative Example 1 237 Comparative Example 2 386 Comparative Example 3 172 Comparative Example 4 661

[0050] 55g of water-soluble acrylic resin (model Jintuan 5207), 8g of amino resin (model Cytec 325), 30.6g of water, 0.2g of leveling agent Jintuan 387, 0.2g of wetting agent Jintuan 127, and 6g of water-based aluminum paste were stirred and dispersed to prepare a blank control of water-soluble baking silver paint.

[0051] 55g of water-soluble acrylic resin (model Jintuan 5207), 8g of amino resin (model Cytec 325), 30.6g of water, 0.2g of leveling agent Jintuan 387, 0.2g of wetting agent Jintuan 127, 6g of water-based aluminum paste, and 2g of anti-settling agent (prepared from each example and comparative example, respectively) were stirred and dispersed to prepare water-soluble baking silver paint.

[0052] The viscosity of the water-soluble baking silver paint was tested using a rotational viscometer at 30 rpm.

[0053] Table 2. Viscosity and thickening properties test of water-soluble baking silver paint

[0054] Viscosity (mPa·s) Example 1 12515 Example 2 15639 Example 3 13078 Blank control 960 Comparative Example 1 1673 Comparative Example 2 3271 Comparative Example 3 1155 Comparative Example 4 8634

[0055] As shown in Tables 1 and 2, the viscosity of water-based emulsion silver paint and water-soluble baking silver paint significantly increased after adding the polyamide anti-settling agent prepared in Examples 1-4. The thickening effect was excellent, which helped prevent aluminum powder from settling and provided good storage stability. This is mainly because the polyamide anti-settling agent not only contains amide bonds in its main molecular chain, but also introduces hydrophilic amide bonds, hydroxyl groups, and quaternary ammonium salts in its side chains. This gives the anti-settling agent excellent water solubility, making it more suitable for water-based emulsion systems. It is beneficial for thickening and preventing settling of water-based emulsions. The polyamide anti-settling agent contains long alkyl chains, which can form hydrophobic association, further thickening the agent and increasing the viscosity. At the same time, the hydroxyl groups and quaternary ammonium salts it contains act as anchoring sites, forming physical and chemical adsorption on the surface of aluminum powder. This makes the aluminum powder more firmly fixed in the network structure formed by the polyamide anti-settling agent, effectively inhibiting the aggregation and settling of aluminum powder particles.

[0056] The polyamide precursor obtained by polymerizing hexamethylenediamine and succinic acid in Comparative Example 3 does not contain tertiary amine groups, cannot generate tertiary amine hydrochloride, cannot form quaternary ammonium salts with octadecyl glycidyl ether, and does not introduce long alkyl chains, resulting in a very poor thickening effect.

[0057] Figure 1 The results showed that after 3 days of storage, the water-based emulsion silver paint blank control exhibited large-area stratification of aluminum powder and resin. However, in Example 1, which incorporated a polyamide anti-settling agent, the aluminum powder showed virtually no sedimentation, demonstrating excellent anti-settling performance.

[0058] Figure 2 As shown, after adding polyurethane anti-settling agent in Example 1, the aluminum powder arrangement is obviously better, the anti-sagging performance is better, the covering power is stronger, and the metallic feel is stronger.

[0059] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions or improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a polyamide anti-settling agent for an aqueous system, characterized in that, The preparation method includes: S1. Add water, 2,6-diamino(N,N-dimethylethylamine)hexanoamide, diacid monomer, and antioxidant to the reactor. Evacuate the reactor and introduce nitrogen gas to carry out the reaction. Then, release the pressure and carry out the prepolymerization reaction. Finally, evacuate the reactor and carry out the polycondensation reaction. Cool and discharge the product, wash the product, and dry it to obtain the polyamide precursor. S2. Add polyamide precursor and hydrochloric acid solution to water, stir, add alkyl glycidyl ether, stir to react, heat to evaporate and remove water, wash the product, dry, and obtain polyamide anti-settling agent for aqueous system.

2. The method for preparing the polyamide anti-settling agent for aqueous systems according to claim 1, characterized in that, The ratio of 2,6-diamino(N,N-dimethylethylamine)hexanoamide, diacid monomer, and antioxidant in S1 is (0.9-1.2) mol: 1 mol: (0.003-0.004) mol; the structural formula of the diacid monomer is... , where a is 2-6.

3. The method for preparing the polyamide anti-settling agent for aqueous systems according to claim 1, characterized in that, The reaction in S1 is carried out at a temperature of 185-200℃ for 2-3 hours.

4. The method for preparing the polyamide anti-settling agent for aqueous systems according to claim 1, characterized in that, In step S1, the pressure is released to atmospheric pressure, the temperature during the prepolymerization reaction is 230-245℃, and the reaction time is 1-1.5h; in step S1, the pressure of the reactor is controlled by vacuuming to 100-200Pa, the temperature during the polycondensation reaction is 230-245℃, and the reaction time is 3-4h.

5. The method for preparing the polyamide anti-settling agent for aqueous systems according to claim 1, characterized in that, The concentration of the hydrochloric acid solution in S2 is 3-12 mol / L.

6. The method for preparing the polyamide anti-settling agent for aqueous systems according to claim 1, characterized in that, The ratio of polyamide precursor to alkyl glycidyl ether in S2 is 100g:(0.1-0.3)mol; the structural formula of the alkyl glycidyl ether is... b is 12-18.

7. The method for preparing the polyamide anti-settling agent for aqueous systems according to claim 1, characterized in that, The reaction temperature in S2 is 65-80℃, and the reaction time is 10-16h.

8. The method for preparing the polyamide anti-settling agent for aqueous systems according to claim 2, characterized in that, The preparation method of the 2,6-diamino(N,N-dimethylethylamine)hexanoamide includes: adding (S)-2,6-ditert-butoxycarbonylaminohexanoic acid, N,N-dimethylethylenediamine, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, and 1-hydroxybenzotriazole to dichloromethane in an ice-water bath at a ratio of 1 mol:(1-1.2) mol:(1.1-1.2) mol:(1.1-1.2) mol, stirring and reacting at 20-30℃ for 12-18 h, washing with water, drying the organic layer, filtering, adding trifluoroacetic acid to the filtrate, stirring and reacting at 20-30℃ for 4-5 h, distilling under reduced pressure, extracting, and separating by column chromatography to obtain 2,6-diamino(N,N-dimethylethylamine)hexanoamide.

9. A polyamide anti-settling agent for an aqueous system obtained by the preparation method according to any one of claims 1-8.

10. The application of the polyamide anti-settling agent for water-based systems as described in claim 9 in water-based coatings and inks.

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