A production process of water-based polyamide wax rheological additive

Abstract

The present invention relates to the field of water-based coatings, and in particular to a production process for a water-based polyamide wax rheological additive. Specifically, the process comprises the following steps: S1: uniformly mixing a diamine, a dibasic acid, a catalyst and a modifier in a reactor, then heating the reactor for reaction, adding a neutralizing agent for adjustment after the reaction, and cooling the reactor to obtain a hydrophilic polyamide wax solid; S2: dissolving the hydrophilic polyamide wax solid in deionized water and alcohol ether to obtain the water-based polyamide wax slurry. The polyamide wax slurry prepared by the present invention has good hydrophilicity, strong anti-sagging performance, and has broad application prospects.

Description

Technical Field

[0001] The invention relates to the field of water-based coatings, and in particular to a production process of a water-based polyamide wax rheological additive. Background Art

[0002] Under environmental protection requirements, water-based coatings are imperative. At present, architectural coatings are basically water-based, and water-based coatings in fields such as industrial paints and wood paints are developing strongly.

[0003] 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 performance and good anti-settling and anti-sagging properties, especially in emulsions containing co-solvents and water-soluble systems, which is superior to other rheological additives.

[0004] Oily polyamide wax rheological additives have been widely used, but ordinary polyamide wax rheological additives can only be used in oily systems and solvent-free systems. In order to make polyamide wax hydrophilic, the current production technology of water-based polyamide wax rheological additives is as follows: A. The first step is the synthesis of polyamide wax. The main raw materials include fatty acids with carbon chain lengths of C12-C36, such as oleic acid, dimer acid, 12-hydroxystearic acid, lauric acid, etc., and monoamines, diamines, and polyamines condense to form low molecular weight polyamide. In the formula of the amidation reaction, fatty acids are generally excessive, and the molar ratio of carboxyl groups to amine groups is generally 1.2:1 to 3:1, and there are some unreacted terminal carboxyl groups in the structure. B. The second step is to add amine neutralizers to the water-based system to make the product have a certain hydrophilicity, and can swell into a colloid in a mixed solvent of water and alcohol ethers. Generally, the solid content of the colloid is about 20%. The colloid has certain thixotropic properties and can be used as a rheological additive in water-based coatings. It has excellent thickening, anti-settling, and anti-sagging properties, and also has the effect of promoting the directional arrangement of aluminum powder.

[0005] However, traditional water-based polyamide wax rheological additives have certain defects. Generally, in order to achieve the neutralization effect and maintain stability, the amine neutralizer will be slightly excessive to keep the product stable. These amine neutralizers will cause the stability of the coating system to decrease, especially in the water-based epoxy system, reacting with the water-based epoxy emulsion, resulting in post-thickening and gelation. Summary of the invention

[0006] In order to solve the above problems, the present invention provides a production process of a water-based polyamide wax rheological additive.

[0007] The technical solution of the present invention is achieved in this way:

[0008] The present invention provides a production process of a water-based polyamide wax rheological additive, which specifically comprises the following steps:

[0009] S1: mixing the diamine, dibasic acid, catalyst and amination modifier in a reactor, and then heating the reactor for reaction. After the reaction, a neutralizing agent is added for adjustment, and after cooling, a hydrophilic polyamide wax solid is obtained.

[0010] S2: dissolving the hydrophilic polyamide wax solid in deionized water and alcohol ether to obtain the water-based polyamide wax slurry;

[0011] The modifier is aminated trifluorophenylboric acid;

[0012] The preparation method of the aminated trifluorophenylboric acid is as follows: dissolving trifluorophenylboric acid in deionized water, then adding diethylenetriamine, adjusting the pH to 10-10.5, adding formaldehyde and heating to react, adding propanol to precipitate after the reaction, and drying to obtain the aminated trifluorophenylboric acid.

[0013] Polyamide wax is an anti-settling agent and thixotropic agent widely used in coatings in recent years. Polyamide wax is mainly composed of two parts, a non-polar aliphatic hydrocarbon part and a polar polyamide functional group. The oxygen atom of the polyamide group has a large electronegativity and is easy to form hydrogen bonds with the hydrogen atoms of the hydrocarbon group. When there is no external shear force or the temperature is reduced, the polyamide molecules uniformly dispersed throughout the system quickly form in situ intermolecular hydrogen bonds, thus forming a network structure. When the hydrogen bonds are subjected to shear force, the adhesion of the molecules is pulled apart, the structure is destroyed, and the viscosity will decrease. When the shear force disappears, the hydrogen bonds are re-formed and the viscosity of the system increases rapidly.

[0014] Polyamide wax is mostly supplied in the form of wax slurry, which is easy to use and does not require grinding, activation and other steps. It can be directly added to the coating and dispersed evenly. It can improve the dispersion stability of the system, has good compatibility with resin, and is smooth without affecting the gloss. It is less sensitive to temperature and has good anti-sagging and leveling effects.

[0015] Furthermore, the diamine is an organic diamine, and the organic diamine includes one or more of ethylenediamine, propylenediamine, hexamethylenediamine, and p-phenylenediamine.

[0016] Furthermore, the diamine is hexamethylenediamine; and the hexamethylenediamine is 1,6-hexamethylenediamine.

[0017] Furthermore, the dibasic acid is an organic dibasic acid, and the organic dibasic acid includes one or more of sebacic acid, undecanedioic acid, lauric acid, and octadecane dibasic acid.

[0018] Furthermore, the dibasic acid is lauric acid.

[0019] Long-chain fatty acids have more than 12 carbon atoms in their carbon chain and are not very volatile.

[0020] Furthermore, the reaction conditions are as follows: the temperature is controlled at 110° C. and the reaction time is 4 h.

[0021] Furthermore, the catalyst is o-nitrophenylboric acid.

[0022] Furthermore, the molar ratio of the diamine to the dibasic acid is (1.1-1.5):1.

[0023] The amidation reaction formula has a slight excess of amine groups, and there are some unreacted terminal amine groups after the reaction is completed.

[0024] Furthermore, the amount of the aminated trifluorophenylboric acid used is 20-40 grams per mole of dibasic acid.

[0025] Trifluorophenylboric acid has a certain hydrophilicity and is often used as an intermediate in organic synthesis. It can adjust the hydrophilicity of polyamide wax.

[0026] Furthermore, the preparation method of the aminated trifluorophenylboric acid is: dissolving trifluorophenylboric acid in deionized water, then adding diethylenetriamine, adjusting the pH to 10-10.5, adding formaldehyde and heating to react, adding propanol for precipitation after the reaction, and drying to obtain the aminated trifluorophenylboric acid.

[0027] By subjecting trifluorophenylboronic acid to an amination reaction, an amino group is introduced to increase the adsorption activity and participate in the amidation reaction.

[0028] At the same time, aminated trifluorophenylboric acid and o-nitrophenylboric acid have a synergistic catalytic effect on the amidation reaction, which can promote the reaction.

[0029] Furthermore, the neutralizing agent is a weak acid.

[0030] Furthermore, the weak acid is one or more of acetic acid, propionic acid, valeric acid, caproic acid, and lactic acid.

[0031] Furthermore, the amount of the neutralizer added is based on adjusting the pH value of the product to 6-7.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] 1. After the polyamide reaction, the temperature is lowered, and acid is added to neutralize the excess amine to generate salt, making it hydrophilic. The use of acid adjustment is safer and more environmentally friendly than the conventional use of excess amine adjustment.

[0034] 2. The introduction of aminated trifluorophenylboric acid can adjust the hydrophilicity and strength of polyamide wax by competing with diamine to participate in the reaction.

[0035] 3. During the catalytic process, o-nitrophenylboric acid can coordinate with aminated trifluorophenylboric acid to enhance the catalytic effect. DETAILED DESCRIPTION

[0036] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in combination 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.

[0037] Reagent Description:

[0038] o-Nitrophenylboric acid, trifluorophenylboric acid, diethylenetriamine, sodium hydroxide, formaldehyde, propanol, 1,6-hexanediamine, lauric acid, sulfuric acid, xylene, ethanol, isopropanol, analytical grade, Sinopharm Group Pharmaceutical Co., Ltd.

[0039] Preparation Example 1

[0040] Preparation of aminated trifluorophenylboronic acid:

[0041] 17.6 g of trifluorophenylboric acid was dissolved in 1000 mL of distilled water, and then 10.3 g of diethylenetriamine was added under stirring at room temperature. The pH of the solution mixture was adjusted to 10 using sodium hydroxide solution. Then, 10 g of formaldehyde solution (mass concentration 37%) was added dropwise at room temperature. The temperature was raised to 50 ° C and reacted for 4 hours. Finally, the solution was poured into 500 mL of propanol to precipitate the aminated trifluorophenylboric acid. After collecting the aminated trifluorophenylboric acid by filtration and washing it three times with propanol, the solid product was dried in a vacuum oven at 40 ° C. Example 1

[0042] 1.3 mol of 1,6-hexanediamine, 1 mol of lauric acid, 1.7 g of o-nitrobenzeneboric acid and 30 g of aminated trifluorophenylboric acid were mixed evenly, and then the temperature was raised to 110° C. to react for 4 hours. After the reaction was completed, acetic acid was added to adjust the pH to 6-7, and hydrophilic polyamide wax solid was obtained after cooling.

[0043] 20 g of hydrophilic polyamide wax solid was dissolved in 70 g of deionized water, and 10 g of propylene glycol ether was added and stirred at high speed to obtain water-based polyamide wax slurry. Example 2

[0044] The difference between this embodiment and embodiment 1 is that the added amount of 1,6-hexanediamine is 1.2 mol.

[0045] The other parts are exactly the same as those in Example 1. Example 3

[0046] The difference between this embodiment and embodiment 1 is that the added amount of 1,6-hexanediamine is 1.5 mol.

[0047] The other parts are exactly the same as those in Example 1. Example 4

[0048] The difference between this comparative example and Example 1 is that the amount of the aminated trifluorophenylboric acid added is 20 g.

[0049] The other parts are exactly the same as those in Example 1. Example 5

[0050] The difference between this comparative example and Example 1 is that the amount of the aminated trifluorophenylboric acid added is 40 g.

[0051] The other parts are exactly the same as those in Example 1.

[0052] Comparative Example 1

[0053] The difference between this comparative example and Example 1 is that the amount of the aminated trifluorophenylboric acid added is 0 g.

[0054] The other parts are exactly the same as those in Example 1.

[0055] Comparative Example 2

[0056] The difference between this comparative example and Example 1 is that the catalyst is sulfuric acid.

[0057] The other parts are exactly the same as those in Example 1.

[0058] Tests and Results

[0059] The epoxy coating was prepared according to 68.7 g of deionized water, 19.0 g of epoxy resin, 5.0 g of barium sulfate, 3.0 g of water-based polyamide wax slurry, 2.3 g of propylene glycol monomethyl ether, 1 g of titanium dioxide, and 0.3 g of polyoxyethylene fatty acid ester. The coating was dispersed at high speed for 30 minutes, and its initial viscosity and anti-sagging performance were tested.

[0060] After storage at 55°C for 7 days, the viscosity change was measured.

[0061] The results are shown in Table 1

[0062] Table 1

[0063] project Sagging film thickness (mm) Initial viscosity (Pa·s) 7-day viscosity (Pa·s) Example 1 350 140 149 Example 2 365 135 145 Example 3 347 141 146 Example 4 325 135 140 Example 5 355 130 145 Comparative Example 1 320 130 110 Comparative Example 2 309 100 108

[0064] It can be seen from Examples 1-3 in Table 1 that the excess amino group in the amidation reaction is neutralized with a weak acid to keep the system weakly acidic, which can improve the stability of the coating in a partially acidic epoxy system. Combined with Comparative Example 1, the diamine in the reaction is reduced, and more aminated trifluorophenylboric acid participates in the reaction, which can not only enhance the anti-sagging performance of the coating, but also improve its thermal storage stability.

[0065] It can be seen from Example 1 and Comparative Example 2 in Table 1 that when the catalyst is o-nitrobenzene boric acid, the reaction proceeds fully and the product performance is good, while the performance decreases when sulfuric acid is used as the catalyst.

[0066] 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 production process for a water-based polyamide wax rheological additive, characterized in that: The specific steps include: S1: placing a diamine, a dibasic acid, a catalyst and a modifier in a reactor and mixing them evenly, then heating them for reaction, adding a neutralizing agent for adjustment after the reaction is completed, and cooling them to obtain a hydrophilic polyamide wax solid; S2: dissolving the hydrophilic polyamide wax solid in deionized water and alcohol ether to obtain an aqueous polyamide wax slurry; The catalyst is o-nitrophenylboric acid; The modifier is aminated trifluorophenylboric acid; Preparation of aminated trifluorophenylboronic acid: 17.6 g of trifluorophenylboric acid was dissolved in 1000 mL of distilled water, and then 10.3 g of diethylenetriamine was added under stirring at room temperature, and the pH of the solution mixture was adjusted to 10 using a sodium hydroxide solution, and then 10 g of a 37% formaldehyde solution was added dropwise at room temperature, and the temperature was raised to 50° C. for reaction for 4 h, and finally, the solution was poured into 500 mL of propanol to precipitate the aminated trifluorophenylboric acid, and the aminated trifluorophenylboric acid was collected by filtration and washed three times with propanol, and then the solid product was dried in a vacuum oven at 40° C.; The reaction conditions in S1 were temperature control at 110°C and reaction time of 4 h; The molar ratio of the diamine to the dibasic acid is: (1.1-1.5):1; The amount of the aminated trifluorophenylboric acid used is 20-40 grams per mole of dibasic acid; The neutralizing agent is a weak acid, which includes one or more of acetic acid, propionic acid, valeric acid, caproic acid, and lactic acid; The amount of the neutralizer added is based on adjusting the pH value of the product to 6-7.

2. The production process of a water-based polyamide wax rheological additive according to claim 1, characterized in that: The diamine is an organic diamine, and the organic diamine includes one or more of ethylenediamine, propylenediamine, hexamethylenediamine, and p-phenylenediamine.

3. The production process of a water-based polyamide wax rheological additive according to claim 2, characterized in that: The diamine is hexamethylenediamine; the hexamethylenediamine is 1,6-hexamethylenediamine.

4. The production process of a water-based polyamide wax rheological additive according to claim 1, characterized in that: The dibasic acid is an organic dibasic acid, and the organic dibasic acid includes one or more of sebacic acid, undecanedioic acid, lauric acid, and octadecane dibasic acid.

5. The production process of a water-based polyamide wax rheological additive according to claim 4, characterized in that: The dibasic acid is lauric acid.