Water-based thickening agent and preparation method thereof

Abstract

The invention discloses a water-based thickening agent and a preparation method thereof. The preparation method comprises the following steps: heating the deionized water to 50-60 DEG C, adding the monofunctional polyether amine, and stirring until the monofunctional polyether amine is completely dissolved; the preparation method comprises the following steps: averagely dividing glycidyl ether into a plurality of parts by weight, adding the first part of glycidyl ether into a mixture of monofunctional polyether amine and water, reacting at 50-60 DEG C, adding one part of glycidyl ether every 1 hour until the last part of glycidyl ether is completely added, and continuously keeping the temperature for 4 hours; and vacuumizing at 40-60 DEG C to remove acetone to obtain the water-based associated thickening agent. The novel water-based associated thickener with more concentrated molecular weight distribution and remarkably improved thickening efficiency is obtained by avoiding the use of isocyanate monomers with high toxicity and optimizing the synthesis process. Besides, active groups such as hydroxyl and amido are ingeniously introduced into a molecular chain of the thickening agent, so that the thickening agent can actively participate in the crosslinking and curing process of a coating, and the overall performance of the coating is further improved.

Description

Technical Field

[0001] The invention relates to the field of water-based thickeners, and in particular to a water-based associative thickener and a preparation method thereof. Background Art

[0002] As environmental regulations around the world become increasingly stringent and public environmental awareness increases significantly, water-based paints are becoming more popular due to their environmentally friendly properties. Therefore, major paint manufacturers and research institutions have stepped up their efforts in the research and development of water-based paint technology. Water-based paints have a lower viscosity due to the dispersion of colloid particles in the water phase, which requires the addition of specific thickeners during the manufacturing and use process to adjust their viscosity and improve their rheological properties, thereby ensuring that the paint can achieve the desired coating effect.

[0003] In the existing thickener market, although inorganic thickeners are common, they have strong thixotropy, which leads to poor leveling performance, thus limiting the wide range of their applications. Cellulose thickeners, as ultra-large molecular water-soluble resins, have their advantages, but under high shear conditions, their viscosity will drop significantly, affecting the fullness of the coating. In addition, their thixotropy is also strong, affecting leveling, and they are prone to mold, so their application in the coating industry has gradually decreased. Acrylic acid ester alkali swelling thickener is a solvent-free product, and its hydrophilicity is mainly provided by carboxylates. However, this thickener is easily affected by ions in the system, which in turn has a negative impact on the water resistance of the coating, so its application is also limited. In contrast, polyurethane associative thickeners perform well in adjusting the rheological properties of coatings. It can adjust the rheological effect of coatings from pseudoplastic to Newtonian, and is not affected by the nature and concentration of ions in the system. This thickener has outstanding performance in comprehensive application effects and is currently an ideal choice in the coating industry. However, this type of thickener still has certain shortcomings:

[0004] (1) In the manufacturing process, highly toxic and volatile isocyanate monomers are inevitably involved. These substances may cause a certain degree of potential harm to human health during the synthesis stage;

[0005] (2) For industrial coatings that require high water resistance, the use of thickeners containing a water-soluble polyethylene glycol backbone may pose some challenges. Since such thickeners do not participate in the curing and crosslinking process of the coating system, they may weaken the water resistance of the coating to a certain extent, resulting in poor performance of the coating in humid environments;

[0006] (3) Common waterborne polyurethane associative thickeners are prepared by a step-by-step chain extension polymerization reaction between diisocyanate and low molecular weight polyethylene glycol to obtain an isocyanate-terminated polymer, which is then capped with a hydrophobic monoalcohol. However, this synthesis method often results in a relatively broad molecular weight distribution of the product, resulting in a low proportion of the ideal molecular weight component with the best thickening performance, which in turn affects the thickening efficiency of the thickener. Summary of the invention

[0007] The present invention provides a water-based thickener and a preparation method thereof in order to solve the limitations of current water-based polyurethane thickeners. The present invention avoids the use of highly toxic isocyanate monomers and optimizes the synthesis process to obtain a novel water-based associative thickener with a more concentrated molecular weight distribution and significantly improved thickening efficiency. In addition, active groups such as hydroxyl and amine groups are cleverly introduced into the molecular chain of the thickener, so that it can actively participate in the cross-linking and curing process of the coating, thereby further improving the overall performance of the coating.

[0008] In a first aspect, the present invention provides a method for preparing an aqueous thickener, which is achieved by adopting the following technical scheme.

[0009] A method for preparing an aqueous thickener comprises the following steps:

[0010] Heat the deionized water to 50-60°C, add the monofunctional polyetheramine, and stir until it is completely dissolved;

[0011] Divide the glycidyl ether into multiple portions by weight, add the first portion of the glycidyl ether to the mixture of the monofunctional polyetheramine and water, react at 50-60°C, add a portion of the glycidyl ether every 1-1.5 hours, and continue to keep warm for 3.5-4 hours until the last portion of the glycidyl ether is added;

[0012] Acetone was removed by vacuum at 40-60°C to obtain an aqueous associative thickener.

[0013] Furthermore, the glycidyl ether is bisphenol A diglycidyl ether and / or glycerol triglycidyl ether.

[0014] The structural formula of bisphenol A diglycidyl ether is as follows:

[0015]

[0016] The structural formula of glycerol triglycidyl ether is as follows:

[0017]

[0018] Furthermore, the monofunctional polyetheramine is selected from one or a mixture of the following structural formulas:

[0019]

[0020] Among them, x=16-255, y=20-175.

[0021] Specifically, the weight average molecular weight of the monofunctional polyetheramine is 6000-30000, preferably 12000-20000.

[0022] Furthermore, the ratio of the molar number of the amino group of the monofunctional polyetheramine to the molar number of the epoxy group of the glycidyl ether is (0.9-1.1):1.

[0023] Furthermore, the weight ratio of the sum of the weights of the glycidyl ether and the monofunctional polyetheramine to water is (0.2:0.8)-(0.4:0.6).

[0024] Further, the glycidyl ether is divided into 3-10 parts by weight.

[0025] In a second aspect, the present invention provides an aqueous thickener, which is achieved by adopting the following technical solution.

[0026] An aqueous thickener prepared by the above preparation method.

[0027] This application has the following beneficial effects.

[0028] The present invention utilizes the epoxy groups on the glycidyl ether molecules to react with the long carbon chain monofunctional polyetheramine to prepare a water-based thickener. The method of the present invention does not use highly toxic isocyanate monomers, the product has a narrow molecular weight distribution, high thickening efficiency, and the product molecular chain contains hydroxyl and amine active groups that can participate in the cross-linking and curing of the coating. The series of thickeners prepared by the method of the present invention can achieve a rheological effect adjusted from pseudoplastic to Newtonian in water-based coatings. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 is a comparison diagram of thickening curves of Example 1 of the present invention and Comparative Example 1 (Newtonian fluid);

[0030] Figure 2 is a comparison diagram of thickening curves of Example 4 of the present invention and Comparative Example 1 (Newtonian fluid);

[0031] Figure 3 is a comparison diagram of thickening curves of Example 2 of the present invention and Comparative Example 2 (equilibrium fluid);

[0032] Figure 4 is a comparison diagram of thickening curves of Example 5 of the present invention and Comparative Example 2 (equilibrium fluid);

[0033] Figure 5 is a comparison diagram of thickening curves of Example 3 of the present invention and Comparative Example 3 (pseudoplastic fluid);

[0034] Figure 6 It is a comparison diagram of the thickening curves of Example 6 of the present invention and Comparative Example 3 (pseudoplastic fluid). DETAILED DESCRIPTION

[0035] The present patent application is further described below in conjunction with embodiments.

[0036] Unless otherwise specified, the experimental methods used in the following preparation examples and examples are all conventional methods; the materials, reagents, etc. used in the following preparation examples and examples are all commercially available unless otherwise specified.

[0037] The formula of Examples 1-6 is as follows (the data units in the table are all g)

[0038]

[0039]

[0040] Example 1

[0041] A method for preparing an aqueous thickener comprises the following steps:

[0042] (1) Divide bisphenol A diglycidyl ether into 5 parts by weight;

[0043] (2) In a reaction vessel equipped with a stirrer, a thermometer, and a reflux device, add deionized water, raise the temperature to 55° C., add a monofunctional polyetheramine (Mw=5000), and stir until it is completely dissolved;

[0044] (3) Add the first portion of bisphenol A diglycidyl ether to the reaction container, react at 58° C., add one portion of bisphenol A diglycidyl ether every hour until the last portion of bisphenol A diglycidyl ether is added, and continue to maintain the reaction temperature for 4 hours to obtain an aqueous associative thickener.

[0045] Example 2

[0046] A method for preparing an aqueous thickener comprises the following steps:

[0047] (1) Divide glycerol triglycidyl ether into 5 parts by weight;

[0048] (2) In a reaction vessel equipped with a stirrer, a thermometer, and a reflux device, add deionized water, raise the temperature to 55° C., add a monofunctional polyetheramine (Mw=5000), and stir until it is completely dissolved;

[0049] (3) Add the first portion of bisphenol A propylene glycol triglycidyl ether to the reaction container, react at 58° C., add one portion of propylene glycol triglycidyl ether every hour until the last portion of propylene glycol triglycidyl ether is added, and continue to maintain the reaction temperature for 4 hours to obtain an aqueous associative thickener.

[0050] Example 3

[0051] A method for preparing an aqueous thickener comprises the following steps:

[0052] (1) Divide bisphenol A diglycidyl ether into 5 parts by weight;

[0053] (2) In a reaction vessel equipped with a stirrer, a thermometer, and a reflux device, add deionized water, raise the temperature to 55° C., add a monofunctional polyetheramine (Mw=10,000), and stir until it is completely dissolved;

[0054] (3) Add the first portion of bisphenol A diglycidyl ether to the reaction container, react at 58° C., add one portion of bisphenol A diglycidyl ether every hour until the last portion of bisphenol A diglycidyl ether is added, and continue to maintain the reaction temperature for 4 hours to obtain an aqueous associative thickener.

[0055] Example 4

[0056] A method for preparing an aqueous thickener comprises the following steps:

[0057] (1) Divide glycerol triglycidyl ether into 5 parts by weight;

[0058] (2) In a reaction vessel equipped with a stirrer, a thermometer, and a reflux device, add deionized water, raise the temperature to 55° C., add a monofunctional polyetheramine (Mw=10,000), and stir until it is completely dissolved;

[0059] (3) Add the first portion of bisphenol A propylene glycol triglycidyl ether to the reaction container, react at 58° C., add one portion of propylene glycol triglycidyl ether every hour until the last portion of propylene glycol triglycidyl ether is added, and continue to maintain the reaction temperature for 4 hours to obtain an aqueous associative thickener.

[0060] Example 5

[0061] A method for preparing an aqueous thickener comprises the following steps:

[0062] (1) Divide bisphenol A diglycidyl ether into 5 parts by weight;

[0063] (2) In a reaction vessel equipped with a stirrer, a thermometer, and a reflux device, add deionized water, raise the temperature to 55° C., add a monofunctional polyetheramine (Mw=20,000), and stir until it is completely dissolved;

[0064] (3) Add the first portion of bisphenol A diglycidyl ether to the reaction container, react at 58° C., add one portion of bisphenol A diglycidyl ether every hour until the last portion of bisphenol A diglycidyl ether is added, and continue to maintain the reaction temperature for 4 hours to obtain an aqueous associative thickener.

[0065] Example 6

[0066] A method for preparing an aqueous thickener comprises the following steps:

[0067] (1) Divide glycerol triglycidyl ether into 5 parts by weight;

[0068] (2) In a reaction vessel equipped with a stirrer, a thermometer, and a reflux device, add deionized water, raise the temperature to 55° C., add a monofunctional polyetheramine (Mw=20,000), and stir until it is completely dissolved;

[0069] (3) Add the first portion of bisphenol A propylene glycol triglycidyl ether to the reaction container, react at 58° C., add one portion of propylene glycol triglycidyl ether every hour until the last portion of propylene glycol triglycidyl ether is added, and continue to maintain the reaction temperature for 4 hours to obtain an aqueous associative thickener.

[0070] The formula of comparative example 1-3 is as follows (the data unit in the table is g)

[0071]

[0072]

[0073] Comparative Example 1

[0074] In a reaction vessel equipped with a stirrer, a thermometer, and a reflux device, polyethylene glycol was added, the temperature was raised to 90°C, isophorone diisocyanate was added, and the reaction was kept warm for 3 hours, n-hexanol was added, and the reaction was kept warm for 4 hours, deionized water was added and stirred evenly to obtain a water-based polyurethane associative thickener.

[0075] Comparative Example 2

[0076] In a reaction vessel equipped with a stirrer, a thermometer and a reflux device, polyethylene glycol is added, the temperature is raised to 90°C, isophorone diisocyanate is added, the reaction is kept warm for 3 hours, dodecanol is added, the reaction is kept warm for 4 hours, deionized water is added and stirred evenly to obtain a waterborne polyurethane associative thickener.

[0077] Comparative Example 3

[0078] In a reaction vessel equipped with a stirrer, a thermometer and a reflux device, polyethylene glycol was added, the temperature was raised to 90°C, isophorone diisocyanate was added, and the reaction was kept warm for 3 hours, octadecyl alcohol was added, and the reaction was kept warm for 4 hours, deionized water was added and stirred evenly to obtain a waterborne polyurethane associative thickener.

[0079] Performance Testing

[0080] The water-based thickeners obtained in Examples 1-6 and the thickeners obtained in Comparative Examples 1-3 were used in the same formula white paint. Through adjustment, three fluids with rheological properties were obtained, among which Example 1, Example 2 and Comparative Example 1 were Newtonian fluids, Example 3, Example 4 and Comparative Example 2 were balanced fluids, and Example 5, Example 6 and Comparative Example 3 were pseudoplastic fluids.

[0081] From the molecular weight analysis results of the examples and the comparative examples, it can be seen that when the weight average molecular weight is close, the molecular weight distribution of the examples is close to about 1.1, and the molecular weight distribution of the comparative examples is wider, resulting in the presence of more molecules with lower thickening efficiency, which reduces the thickening efficiency. Figure 1-6 From the thickening curves of the embodiment and the comparative example, the thickening curve of the embodiment is higher than that of the comparative example, which shows that the implementation effect of the present invention is better than that of the commonly used associative thickeners on the market.

[0082] The embodiments of this specific implementation method are all preferred embodiments of the present invention, and are not intended to limit the protection scope of the present invention. Therefore, all equivalent changes made based on the structure, shape, and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing an aqueous thickener, characterized in that: The following steps are involved: Heat the deionized water to 50-60°C, add the monofunctional polyetheramine, and stir until it is completely dissolved; Divide the glycidyl ether into multiple portions by weight, add the first portion of the glycidyl ether to the mixture of the monofunctional polyetheramine and water, react at 50-60°C, add a portion of the glycidyl ether every 1-1.5 hours, and continue to keep warm for 3.5-4 hours until the last portion of the glycidyl ether is added; Acetone was removed by vacuum at 40-60°C to obtain an aqueous associative thickener.

2. The method for preparing an aqueous thickener according to claim 1, characterized in that: The glycidyl ether is bisphenol A diglycidyl ether or glycerol triglycidyl ether.

3. The method for preparing an aqueous thickener according to claim 1, characterized in that: The monofunctional polyetheramine is selected from one or a mixture of the following structural formulas: Among them, x=16-255, y=20-175.

4. The method for preparing an aqueous thickener according to claim 1, characterized in that: The ratio of the molar number of the amino group of the monofunctional polyetheramine to the molar number of the epoxy group of the glycidyl ether is (0.9-1.1):

1.

5. The method for preparing an aqueous thickener according to claim 1, characterized in that: The weight ratio of the sum of the weights of the glycidyl ether and the monofunctional polyetheramine to water is (0.2:0.8)-(0.4:0.6).

6. The method for preparing an aqueous thickener according to claim 1, characterized in that: Glycidyl ether is divided into 3-10 parts by weight.

7. An aqueous thickener prepared by the preparation method according to any one of claims 1 to 6.

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