Development and application of universal pigment and filler dispersing agent prepared by solvent-free aqueous phase process

Abstract

The invention discloses development and application of a universal pigment and filler dispersing agent prepared by a solvent-free aqueous phase process, which comprises the following steps: heating a first monomer unsaturated block polyether to 65-83 DEG C, and respectively dropwise adding an oxidant solution and a reducing agent solution of an initiator, a second monomer styrene sulfonate aqueous solution and a third monomer unsaturated carboxylic acid aqueous solution; after material adding is completed, heat preservation is conducted for 3-6 hours at the temperature of 78-83 DEG C, and after the reaction is completed, a neutralizer polyether amine is added to adjust the pH value of a product to be 5-7; the universal pigment and filler dispersing agent prepared by the solvent-free aqueous phase process is applied to color paste and coating systems. The dispersing agent disclosed by the invention has good dispersion and viscosity reduction effects on organic and inorganic pigments and fillers, is wide in application range, high in grinding efficiency and high in storage stability, and can realize good application of dispersed color paste in a coating system.

Description

Technical Field

[0001] This invention relates to the field of coating technology, and in particular to the development and application of a solvent-free aqueous phase process for preparing general-purpose pigment and filler dispersants. Background Technology

[0002] With increasingly stringent environmental regulations, water-based coatings, inks, and adhesives are rapidly replacing traditional solvent-based systems. Water-based pigments and fillers dispersants, as core functional additives in coatings, have become crucial for achieving high-performance water-based systems by reducing the tendency for pigment and filler particles to agglomerate, thereby improving dispersion stability and processing efficiency.

[0003] Currently, most existing dispersants are designed for a single function, primarily targeting the dispersion of specific types of single organic pigments or inorganic pigments and fillers. They struggle to simultaneously meet the diverse needs of both organic and inorganic pigments and fillers. Furthermore, existing dispersant synthesis processes often involve polymerization reactions in solvents, requiring large quantities of organic solvents during production. This also raises issues regarding solvent usage and recycling, increasing costs and potentially causing environmental pollution.

[0004] CN 118930760 A discloses an aqueous polymer dispersant, its preparation method, and its application. It describes a solvent-free process, but a large number of additives are used in the synthesis process. The additives are any one or a combination of at least two of dipropylene glycol methyl ether, dipropylene glycol butyl ether, ethylene glycol butyl ether, diethylene glycol butyl ether, and dodecyl alcohol ester. They are still organic solvents and pose a VOC emission problem.

[0005] US20100099813A1 discloses the preparation of a comb-like polymer and its use as a dispersant. The process involves the solvent propylene glycol methyl ether acetate and requires preparation at a high temperature of 140°C. It also requires distillation to remove the solvent before adding pure water to convert it into an aqueous system. The steps are cumbersome, and incomplete solvent removal will still leave VOC residues.

[0006] CN 110721632 A discloses an aqueous inorganic filler dispersant and its preparation method, and introduces a dispersant synthesized by a water system process, but this dispersant is only suitable for the dispersion of inorganic fillers. Therefore, addressing the performance bottlenecks of existing dispersion technologies in organic / inorganic pigment and filler blends, and the pressure from environmental regulations, this invention provides a clear direction for technical improvement. The aim in this field is to develop an aqueous dispersant whose synthesis process requires no solvents and can achieve highly efficient and compatible dispersion of inorganic and organic pigments and fillers. Summary of the Invention Based on the shortcomings of the prior art, the technical problem solved by the present invention is to provide a solvent-free aqueous phase process for the preparation and application of a general-purpose pigment and filler dispersant. The dispersant is completely solvent-free during synthesis, does not rely on high temperature initiation, and can meet the diverse needs of simultaneous dispersion of organic and inorganic pigments and fillers in the coatings industry.

[0007] To address the aforementioned technical problems, this invention provides a solvent-free aqueous phase process for preparing a general-purpose pigment and filler dispersant. The raw materials include the following components, with the following mass fractions: 280-360 parts of a first monomer, 42-85 parts of a second monomer, 18-38 parts of a third monomer, 0.5-5 parts of oxidant and 0.5-5 parts of reductant in the initiator of the redox system, 200-600 parts of pure water, and the amount of polyetheramine required to neutralize the pH of the system to 5-7.

[0008] As a preferred embodiment of the above technical solution, the solvent-free aqueous phase process for preparing general-purpose pigment and filler dispersants provided by the present invention further includes some or all of the following technical features: As an improvement to the above technical solution, the first monomer is an alkoxy block polyether of an unsaturated fatty alcohol, with the following general structural formula: Where R is C 1-5 The alkyl group, where m is an integer between 3 and 10, and n is an integer between 5 and 22.

[0009] As an improvement to the above technical solution, the second monomer is styrene sulfonate, and more specifically, at least one of sodium styrene sulfonate, potassium styrene sulfonate, and ammonium styrene sulfonate.

[0010] As an improvement to the above technical solution, the third monomer is an unsaturated carboxylic acid containing an olefinic bond, and more specifically, at least one of acrylic acid, methacrylic acid, and maleic acid.

[0011] As an improvement to the above technical solution, the oxidant in the initiator of the redox system is at least one of potassium persulfate, ammonium persulfate, sodium persulfate, and hydrogen peroxide; the reducing agent is at least one of sodium bisulfite, potassium bisulfite, ammonium bisulfite, and ferrous sulfate.

[0012] As an improvement to the above technical solution, the oxidant in the initiator of the redox system is at least one of potassium persulfate, ammonium persulfate, sodium persulfate, and hydrogen peroxide; the reducing agent is at least one of sodium bisulfite, potassium bisulfite, ammonium bisulfite, and ferrous sulfate.

[0013] As an improvement to the above technical solution, the neutralizing agent is a monofunctional polyetheramine with a molecular weight range of 800 to 2200 and a PO / EO group ratio of 1 / 1.2 to 1 / 3.5 in the main chain.

[0014] A method for preparing a general-purpose pigment and filler dispersant using a solvent-free aqueous phase process as described above includes the following steps: heating the first monomer, unsaturated block polyether, to 65-83°C, and then adding dropwise the oxidant solution and reducing agent solution of the initiator, as well as the aqueous solution of the second monomer, styrene sulfonate, and the aqueous solution of the third monomer, unsaturated carboxylic acid; after the addition is complete, maintaining the temperature at 78-83°C for 3-6 hours, and adding the neutralizing agent, polyetheramine, to adjust the pH of the product to 5-7 after the reaction is complete.

[0015] As a preferred embodiment of the above technical solution, the method for preparing a general-purpose pigment and filler dispersant using a solvent-free aqueous phase process provided by the present invention further includes some or all of the following technical features: As an improvement to the above technical solution, the oxidant solution and reducing agent solution of the initiator are specifically as follows: the oxidant solution is a solution with a mass fraction of 5-10 wt% prepared by mixing the oxidant with deionized water; the reducing agent solution is a solution with a mass fraction of 5-10 wt% prepared by mixing the reducing agent with deionized water; the aqueous solution of the second monomer styrene sulfonate is a solution with a mass fraction of 20-40 wt% prepared by mixing the second monomer styrene sulfonate with deionized water; and the aqueous solution of the third monomer unsaturated carboxylic acid is a solution with a mass fraction of 20-40 wt% prepared by mixing the third monomer unsaturated carboxylic acid with deionized water.

[0016] This invention also discloses an application of a solvent-free aqueous phase process for preparing a general-purpose pigment and filler dispersant as described above, which is used in color pastes and coating systems.

[0017] Compared with the prior art, the technical solution of the present invention has the following beneficial effects: 1. The general-purpose pigment and filler dispersant of the present invention is prepared by a low-temperature aqueous phase initiation system. The synthesis process requires no solvent, has low energy consumption, and is environmentally friendly.

[0018] 2. The —COO in the structure of this dispersant — SO3 —The sulfonate ions (derived from the second monomer, styrene sulfonate, and the carboxyl ions, from the third monomer, unsaturated carboxylic acid) can form ionic bonds with the surface charge of inorganic pigments and fillers, firmly binding them and forming a double electron layer. This creates electrostatic repulsion between pigment and filler particles, effectively improving the stability of the inorganic pigment and filler aqueous solution system. Meanwhile, the benzene ring and amino functional groups in the dispersant structure (the benzene ring originates from styrene sulfonate, and the amino group originates from the neutralizing agent, polyetheramine) can form anchoring adsorption with the surfaces of carbon black and organic pigments through van der Waals forces and hydrogen bonds, effectively preventing desorption of the dispersant from the organic pigments. Furthermore, the EO / PO block chains in the first monomer, unsaturated block polyetheramine, and the neutralizing agent, monofunctional polyetheramine, act as solvating segments, exhibiting excellent steric hindrance, effectively preventing the re-aggregation and flocculation of tiny pigment and filler particles, thus improving the system's storage stability. Simultaneously, the EO / PO segments also provide rapid wetting of pigment and filler particles, shortening grinding time. Ultimately, by adjusting the ratio of the three reactive monomers and the amount of EO / PO in the solvated chain segment, and optimizing the dispersant structure, a good dispersion and viscosity reduction effect on both organic and inorganic pigments and fillers was achieved. This resulted in a wide range of applications, high grinding efficiency, and strong storage stability, enabling the effective application of dispersed pigments in coating systems.

[0019] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of the present invention more apparent and understandable, the following detailed description is provided in conjunction with preferred embodiments. Detailed Implementation

[0020] The following detailed description of specific embodiments of the present invention is part of this specification. The principles of the present invention are illustrated through examples, and other aspects, features and advantages of the present invention will become apparent from this detailed description.

[0021] Example 1m First, the first monomer, unsaturated block polyether m, is added. After heating to 65-70°C, the oxidant (5% sodium persulfate aqueous solution), the reducing agent (5% sodium bisulfite aqueous solution), the second monomer (20% sodium styrene sulfonate aqueous solution), and the third monomer (20% methacrylic acid aqueous solution) are added dropwise. After the addition is complete, the temperature is maintained at 78-83°C for 3 hours. After the reaction is completed, the neutralizing agent, polyetheramine, is added to adjust the pH of the product to 5-7, and the dispersant is obtained.

[0022] In this embodiment, the first monomer comprises 280 parts, the second monomer 42 parts, the third monomer 18 parts, and the initiator of the redox system comprises 0.5 parts of oxidant and 0.5 parts of reductant. In the unsaturated block polyether, R is an alkyl group with 3 carbon atoms, m is 3, and n is 7. The polyetheramine is monofunctional, with a molecular weight of approximately 800, and a PO / EO ratio of 1 / 3.5.

[0023] Example 2 First, the first monomer, unsaturated block polyether, is added. After heating to 80-83°C, the oxidant (10 wt% potassium persulfate aqueous solution), the reducing agent (10 wt% potassium bisulfite aqueous solution), the second monomer (40 wt% potassium styrene sulfonate aqueous solution), and the third monomer (40 wt% maleic acid aqueous solution) are added dropwise. After the addition is complete, the temperature is maintained at 78-83°C for 6 hours. After the reaction is complete, the neutralizing agent, polyetheramine, is added to adjust the pH of the product to 5-7, and the dispersant is obtained.

[0024] In this embodiment, the first monomer comprises 360 parts, the second monomer 85 parts, the third monomer 38 parts, and the initiator of the redox system comprises 5 parts oxidant and 5 parts reductant. In the unsaturated block polyether, R is an alkyl group with 4 carbon atoms, m is 10, and n is 22. The polyetheramine is monofunctional, with a molecular weight of approximately 1700, and a PO / EO ratio of 1 / 2.5.

[0025] Example 3 First, add the first monomer, unsaturated block polyether, and heat to 75-78°C. Then, add dropwise the oxidant (8 wt% ammonium persulfate aqueous solution), the reducing agent (8 wt% ammonium bisulfite aqueous solution), the second monomer (30 wt% ammonium styrene sulfonate aqueous solution), and the third monomer (30 wt% acrylic acid aqueous solution). After the addition is complete, maintain the temperature at 78-83°C for 4 hours. After the reaction is complete, add the neutralizing agent polyetheramine to adjust the pH of the product to 5-7 and obtain the dispersant.

[0026] In this embodiment, the first monomer comprises 320 parts, the second monomer 62 parts, the third monomer 28 parts, and the initiator of the redox system comprises 3 parts oxidant and 3 parts reductant. In the unsaturated block polyether, R is an alkyl group with 5 carbon atoms, m is 5, and n is 17. The polyetheramine is monofunctional, with a molecular weight of approximately 2200, and a PO / EO ratio of 1 / 1.2.

[0027] The aqueous dispersant samples prepared in Examples 1 to 3 and the market benchmark samples were compared under the same conditions to determine the dispersion performance of the samples in different types of organic / inorganic pigments and fillers. The aqueous pigment formulations are shown in Table 1, and the test results are shown in Table 2.

[0028] Table 1. Water-based pigment formulation

[0029] Note: The amount of dispersant* (w%) added is the percentage of its effective content relative to the pigments and fillers. Table 2. Results of pigment and filler dispersion tests on samples with different dispersants

[0030] As can be seen from the data in Tables 1 and 2, the general-purpose pigment and filler dispersant samples obtained in Examples 1 to 3 above have significantly better grinding, dispersing and viscosity-reducing effects on carbon black, organic pigment phthalocyanine blue, inorganic pigment titanium dioxide, and inorganic filler 800-mesh heavy calcium carbonate compared to market samples 1 and 2. They can also make the pigment and filler particles uniformly dispersed for a longer period of time, without flocculation and deposition, forming a stable color paste and ensuring good stability of the system.

[0031] The carboxylic acid, sulfonic acid, amino group, and benzene ring in the dispersant structure of this invention are all anchoring functional groups. Under the combined action of ionic bonds, hydrogen bonds, and van der Waals forces, they can be firmly adsorbed onto the surface of pigment and filler particles. The first monomer, unsaturated block polyether, and the neutralizing agent, monofunctional polyetheramine, both have EO / PO block chains that are solvated, and their steric hindrance effectively prevents the flocculation of pigment and filler particles. The dispersant prepared by this method has good dispersion and viscosity-reducing effects on both organic and inorganic pigments and fillers, a wide range of applications, high grinding efficiency, and strong storage stability, enabling the effective application of dispersed pigment pastes in coating systems. All the raw materials listed in this invention, as well as the upper and lower limits and ranges of the raw materials and the upper and lower limits and ranges of the process parameters (such as temperature, time, etc.), can realize this invention. Examples are not listed one by one here.

[0032] The above description is merely a preferred embodiment of the present invention, and should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A solvent-free aqueous phase process for preparing general-purpose pigment and filler dispersants, characterized in that, Its raw materials include the following components, and the mass fractions of each component are as follows: 280-360 parts of the first monomer, 42-85 parts of the second monomer, 18-38 parts of the third monomer, 0.5-5 parts of oxidant and 0.5-5 parts of reductant in the initiator of the oxidation-reduction system, 200-600 parts of pure water, and the amount of polyetheramine required to neutralize the pH of the system to 5-7.

2. The solvent-free aqueous phase process for preparing a general-purpose pigment and filler dispersant as described in claim 1, characterized in that: The first monomer is an alkoxy block polyether of an unsaturated fatty alcohol, with the following general structural formula: Where R is C 1-5 The alkyl group, where m is an integer between 3 and 10, and n is an integer between 5 and 22.

3. The solvent-free aqueous phase process for preparing general-purpose pigment and filler dispersants as described in claim 1, characterized in that: The second monomer is styrene sulfonate, and the third monomer is an unsaturated carboxylic acid containing an olefin bond.

4. The solvent-free aqueous phase process for preparing a general-purpose pigment and filler dispersant as described in claim 3, characterized in that: The styrene sulfonate is at least one of sodium styrene sulfonate, potassium styrene sulfonate, and ammonium styrene sulfonate; the unsaturated carboxylic acid containing an olefinic bond is at least one of acrylic acid, methacrylic acid, and maleic acid.

5. The solvent-free aqueous phase process for preparing a general-purpose pigment and filler dispersant as described in claim 1, characterized in that: The oxidant in the initiator of the redox system is at least one of potassium persulfate, ammonium persulfate, sodium persulfate, and hydrogen peroxide; the reducing agent is at least one of sodium bisulfite, potassium bisulfite, ammonium bisulfite, and ferrous sulfate.

6. The solvent-free aqueous phase process for preparing a general-purpose pigment and filler dispersant as described in claim 1, characterized in that: The oxidant in the initiator of the redox system is at least one of potassium persulfate, ammonium persulfate, sodium persulfate, and hydrogen peroxide; the reducing agent is at least one of sodium bisulfite, potassium bisulfite, ammonium bisulfite, and ferrous sulfate.

7. The solvent-free aqueous phase process for preparing a general-purpose pigment and filler dispersant as described in claim 1, characterized in that: The neutralizing agent is a monofunctional polyetheramine with a molecular weight range of 800 to 2200 and a PO / EO group ratio of 1 / 1.2 to 1 / 3.5 in the main chain.

8. A method for preparing a general-purpose pigment and filler dispersant using a solvent-free aqueous phase process as described in any one of claims 1-7, characterized in that, The process includes the following steps: heating the first monomer unsaturated block polyether to 65-83°C, then adding dropwise the oxidant solution and reducing agent solution of the initiator, as well as the aqueous solution of the second monomer styrene sulfonate and the aqueous solution of the third monomer unsaturated carboxylic acid; after the addition is complete, maintaining the temperature at 78-83°C for 3-6 hours, and adding the neutralizing agent polyetheramine to adjust the pH of the product to 5-7 after the reaction is complete.

9. The method for preparing a general-purpose pigment and filler dispersant using a solvent-free aqueous phase process as described in claim 8, characterized in that: The oxidant and reducing agent solutions of the initiator are specifically as follows: the oxidant solution is prepared by mixing the oxidant with deionized water to a mass fraction of 5-10 wt%; the reducing agent solution is prepared by mixing the reducing agent with deionized water to a mass fraction of 5-10 wt%; the second monomer styrene sulfonate aqueous solution is prepared by mixing the second monomer styrene sulfonate with deionized water to a mass fraction of 20-40 wt%; and the third monomer unsaturated carboxylic acid aqueous solution is prepared by mixing the third monomer unsaturated carboxylic acid with deionized water to a mass fraction of 20-40 wt%.

10. An application of a solvent-free aqueous phase process for preparing a general-purpose pigment and filler dispersant as described in any one of claims 1-9, characterized in that: The solvent-free aqueous phase process described above prepares a general-purpose pigment and filler dispersant for use in color pastes and coating systems.

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