Delustering agent as well as preparation method and application thereof

Abstract

The invention relates to a matting agent as well as a preparation method and application thereof, and belongs to the technical field of coating functional aids. The delustering agent is composed of a composite cellulose ether thickening agent, texanol and magnesium lithium silicate protection glue, the composite cellulose ether thickening agent is prepared by compounding hydroxyethyl cellulose ether or hydroxypropyl methyl cellulose ether and nano calcium carbonate according to the mass ratio of 80%: 20%, and during preparation, refining and spray drying granulation are conducted through a colloid mill. When the matting agent is applied to a water-based top-coat coating, the matting effect and stability of a coating film can be remarkably improved, the matting agent is excellent in compatibility with components such as pure acrylic emulsion and a coalescing agent, is suitable for a wide-range formula of 200-1,000 g of matting agent adding amount, and has a wide industrial application prospect.

Description

Technical Field

[0001] The invention belongs to the technical field of coating functional additives and relates to a matting agent and a preparation method and application thereof. Background Art

[0002] Traditional water-based topcoats often cause light pollution after application due to excessive surface gloss. This is particularly true for applications such as building exteriors and furniture coatings, where the addition of matting agents is necessary to reduce reflectivity. Existing matting technologies often utilize silica or wax particles, but these suffer from poor compatibility with water-based systems and unstable matting efficiency. Some technologies achieve matting by increasing the amount of filler, but this results in a sudden increase in coating viscosity and a decrease in leveling, making it difficult to achieve a balanced application performance and matting effect.

[0003] While cellulose ether thickeners can adjust the rheological properties of coatings, their film-forming strength is insufficient when used alone, and they are easily affected by ambient humidity, resulting in gloss rebound. Lithium magnesium silicate protective colloids, as layered inorganic compounds, can form a three-dimensional network structure to suppress light reflection, but their interfacial bonding with organic components is weak. Nano-calcium carbonate can improve the hardness of the system, but its uneven dispersion can easily cause precipitation. Summary of the Invention

[0004] The purpose of the present invention is to provide a matting agent and a preparation method and application thereof, which has the characteristics of good matting property.

[0005] The purpose of the present invention can be achieved through the following technical solutions: A matting agent comprising a composite cellulose ether thickener, alcohol ester lauryl and lithium magnesium silicate protective colloid; The composite cellulose ether thickener comprises a cellulose ether thickener and nano calcium carbonate, with a mass ratio of 80%:20%; The cellulose ether thickener is hydroxyethyl cellulose ether HEC or hydroxypropyl methyl cellulose ether HPMC with a particle size of 13-250 μm.

[0006] Furthermore, the preparation method of the composite cellulose ether thickener is: Nano-calcium carbonate and deionized water are mixed in a mass ratio of 1:(1.5-2), stirred at 1000-1200 rpm for 10-15 minutes, and refined by colloid grinding. Then, a cellulose ether thickener is added, the rotation speed is adjusted to 500-800 rpm, and stirring is continued for 20-30 minutes. After the stirring is completed, the composite cellulose ether thickener is obtained by spray drying and granulation.

[0007] Furthermore, the colloidal grinding parameters are as follows: the gap between the stator and the rotor is 0.1-0.2 mm, the rotation speed is 2500-3500 rpm, and the processing time is 3-5 minutes.

[0008] During the colloidal grinding process, the viscosity of the nano-calcium carbonate suspension is 200~500mPa·s, the temperature is 25~40℃, and the feed flow rate is 80~150L / h.

[0009] During the spray drying granulation, a centrifugal atomizer is used, and the rotation speed of the atomizer is 8000~12000rpm.

[0010] Furthermore, the mass ratio of the composite cellulose ether thickener to the alcohol ester dodecahydrate in the matting agent is 1:1.2; The mass ratio of the lithium magnesium silicate protective gel to the composite cellulose ether thickener is 3:1; The concentration of the lithium magnesium silicate protective colloid is 8 w / v%.

[0011] Furthermore, the specific steps of the preparation method are as follows: At room temperature, the alcohol ester dodecahydrate and the composite cellulose ether thickener were mixed according to a mass ratio, and stirred at 50-200 rpm for 5-20 minutes to obtain a mixture A; The mixture A is added to the lithium magnesium silicate protective colloid while stirring at a speed of 100 to 500 rpm. After the mixture A is completely added, stirring is continued for 0.5 to 1 hour to obtain the matting agent.

[0012] A matting agent is used in preparing a water-based topcoat. The water-based topcoat is prepared by adding 500 ml of pure acrylic emulsion to a container, slowly adding 30 g of a film-forming aid alcohol ester 12 under stirring, then adding 1.0 g of a surfactant, and then adding 4.5 g of a polyurethane thickener. After stirring for 30 minutes, 200 to 1000 g of the matting agent is added, and the mixture is stirred evenly to obtain a water-based topcoat varnish.

[0013] This invention addresses the technical issues of traditional matting agents, such as the difficulty in balancing transparency and matting efficiency, insufficient abrasion resistance, and poor anti-settling properties. By developing a matting agent based on a composite cellulose ether thickener, this agent modulates the particle surface morphology and particle size distribution to form a uniformly distributed microscopic collapsed structure during film formation. This matting agent utilizes the multi-stage light scattering effect to achieve efficient matting. It is particularly suitable for transparent varnish systems, achieving a matte effect with significantly reduced gloss at an 85° angle while imparting excellent abrasion resistance and long-term storage stability to the paint film. By carefully selecting the particle size and distribution of the cellulose ether thickener, this invention produces a paint film with a unique surface morphology and feel. Because its specific gravity is close to that of water, it exhibits excellent anti-settling properties.

[0014] The present invention incorporates a composite cellulose ether thickener, in which hydroxyethyl cellulose ether (HEC) or hydroxypropyl methyl cellulose ether (HPMC) forms a three-dimensional network structure through intermolecular hydrogen bonding. Nano-calcium carbonate, acting as a rigid filler, is evenly dispersed within this network. When the cellulose ether accounts for 80%, the intermolecular hydrogen bonding is sufficient, allowing for the rapid construction of a three-dimensional network structure and providing a uniformly dispersed framework for the nano-calcium carbonate. If the ratio is less than 70%, network defects increase, leading to an uneven matte microstructure. Above 90%, the rigidity is insufficient, preventing the formation of a stable concave surface.

[0015] During the coating film-forming process, solvent evaporation causes the cellulose ether network to shrink in a controlled manner. The embedded nano-calcium carbonate limits this shrinkage, resulting in a uniformly distributed concave microstructure on the film surface. This microscopic roughness significantly reduces the intensity of specularly reflected light through a multi-level scattering effect. At the same time, because the size of the nano-calcium carbonate matches the wavelength of light, it achieves efficient extinction while maintaining the high transmittance of the transparent varnish.

[0016] The addition of nano-calcium carbonate increases the modulus of the composite thickener. Its rigid particles form an interpenetrating network with the layered structure of the lithium magnesium silicate protective gel, enhancing the film's resistance to deformation. The alcohol ester reacts with the hydroxyl groups of the cellulose ether through its ester group, forming a hydrophobic modified layer on the particle surface. This effectively inhibits swelling and softening caused by water penetration, while also reducing the coating's surface friction coefficient. The synergistic effect of these three factors allows the paint film to disperse stress through an energy dissipation mechanism when subjected to external forces, significantly improving wear resistance.

[0017] The density of the composite thickener is precisely controlled by the mass ratio of nano-calcium carbonate to cellulose ether, approaching the density of aqueous systems. This eliminates the sedimentation driving force of traditional inorganic fillers due to density differences. The negatively charged lamellar structure of the lithium magnesium silicate protective colloid creates electrostatic repulsion with the alcohol ester-modified composite particles, while the long-chain structure of the alcohol ester provides steric hindrance. This dual stabilization mechanism ensures that the particles remain uniformly dispersed in the system, preventing precipitation during long-term storage. DETAILED DESCRIPTION

[0018] In order to further illustrate the technical means and effects adopted by the present invention to achieve the predetermined purpose of the invention, the specific implementation methods, structures, features and effects of the present invention are described in detail below in combination with the embodiments.

[0019] The water-based acrylic emulsion uses pure acrylic emulsion, the surfactant uses a water-based coating wetting agent, the film-forming aid is alcohol ester twelve, the water-based polyurethane thickener uses Dow Chemical's Yale Shun™ brand, the hydroxyethyl cellulose ether is NatrosolTM250HBR, and the lithium magnesium silicate protective glue is BYK-S482.

[0020] Example 1 The composite cellulose ether thickener comprises hydroxyethyl cellulose ether HEC and nano calcium carbonate, with the mass ratio of the two being 80%:20%; The preparation method of the composite cellulose ether thickener is: Nano calcium carbonate and deionized water were mixed in a mass ratio of 1:2, stirred at 1000 rpm for 15 minutes, and refined by colloid milling, wherein the colloid milling parameters were as follows: a gap between the stator and the rotor of 0.1 mm, a rotation speed of 2500 rpm, and a processing time of 3 minutes. 13 μm hydroxyethyl cellulose ether HEC was then added, the rotation speed was adjusted to 800 rpm, and stirring was continued for 20 minutes. After stirring, the mixture was spray-dried and granulated to obtain the composite cellulose ether thickener.

[0021] 50 g of a composite cellulose ether thickener having a particle size of less than 400 mesh was added to 60 g of a film-forming aid, alcohol ester 12, and the mixture was stirred at room temperature. 24 g of the mixture was then slowly added to 400 ml of an 8 w / v% aqueous solution of lithium magnesium silicate protective gel BYK S-482 under stirring. The mixture was stirred for 0.5 hour at 500 rpm until the cellulose ether particles fully absorbed water and swelled, thereby obtaining a matting agent.

[0022] Example 2 The composite cellulose ether thickener comprises hydroxypropyl methylcellulose ether HPMC and nano calcium carbonate, with the mass ratio of the two being 80%:20%; The preparation method of the composite cellulose ether thickener is: Nano calcium carbonate and deionized water were mixed in a mass ratio of 1:1.5, stirred at 1200 rpm for 10 minutes, and refined by colloid milling, wherein the colloid milling parameters were as follows: a gap between the stator and the rotor of 0.2 mm, a rotation speed of 3500 rpm, and a processing time of 5 minutes. 150 μm hydroxypropyl methylcellulose ether HPMC was then added, the rotation speed was adjusted to 500 rpm, and stirring was continued for 30 minutes. After stirring, the mixture was spray-dried and granulated to obtain the composite cellulose ether thickener.

[0023] 50 g of a composite cellulose ether thickener with a particle size of 100-200 mesh was added to 60 g of a film-forming aid, alcohol ester 12, and the mixture was stirred at room temperature. 24 g of the mixture was then slowly added to 400 ml of an 8 w / v% aqueous solution of lithium magnesium silicate protective gel BYK S-482 under stirring. The mixture was stirred for 1.0 hour at a stirring speed of 100 rpm until the cellulose ether particles fully absorbed water and swelled to obtain a matting agent.

[0024] Example 3 The composite cellulose ether thickener comprises hydroxyethyl cellulose ether HEC and nano calcium carbonate, with the mass ratio of the two being 80%:20%; The preparation method of the composite cellulose ether thickener is: Nano calcium carbonate and deionized water were mixed in a mass ratio of 1:2, stirred at 1200 rpm for 10 minutes, and colloidally ground. The colloidally ground parameters were as follows: a gap between the stator and the rotor of 0.2 mm, a rotation speed of 3500 rpm, and a processing time of 3 minutes. 250 μm hydroxyethyl cellulose ether HEC was then added, the rotation speed was adjusted to 800 rpm, and stirring was continued for 20 minutes. After stirring, the mixture was spray-dried and granulated to obtain the composite cellulose ether thickener.

[0025] 50 g of a composite cellulose ether thickener with a particle size of 80-100 mesh was added to 60 g of a film-forming aid, alcohol ester 12, and the mixture was stirred at room temperature. 24 g of the mixture was then slowly added to 400 ml of an 8 w / v% aqueous solution of lithium magnesium silicate protective gel BYK S-482 under stirring. The mixture was stirred for 0.5 hour at 300 rpm until the cellulose ether particles fully absorbed water and swelled to obtain a matting agent.

[0026] Comparative Example 1 In this comparative example, the composite cellulose ether thickener includes hydroxyethyl cellulose ether HEC and nano calcium carbonate, and the mass ratio of the two is 90%:10%; The remaining steps are consistent with those in Example 1.

[0027] Comparative Example 2 In this comparative example, the composite cellulose ether thickener includes hydroxyethyl cellulose ether HEC and nano calcium carbonate, and the mass ratio of the two is 70%:30%; The remaining steps are consistent with those in Example 1.

[0028] Comparative Example 3 In this comparative example, only hydroxyethyl cellulose ether HEC was used without introducing nano-calcium carbonate, and the remaining steps were the same as those in Example 1.

[0029] Application Example 1 Add 500 ml of pure acrylic emulsion to the container, slowly add 30 g of film-forming aid alcohol ester 12 under stirring, then add 1.0 g of surfactant, then add 4.5 g of polyurethane thickener, stir for 30 minutes, add 500 g of the matting agent prepared in Example 1, stir evenly to obtain a water-based topcoat varnish coating.

[0030] Application Example 2 Add 500 ml of pure acrylic emulsion to the container, slowly add 30 g of film-forming aid alcohol ester 12 under stirring, then add 1.0 g of surfactant, then add 4.5 g of polyurethane thickener, stir for 30 minutes, add 500 g of the matting agent prepared in Example 2, stir evenly to obtain a water-based topcoat varnish coating.

[0031] Application Example 3 Add 500 ml of pure acrylic emulsion to the container, slowly add 30 g of film-forming aid alcohol ester 12 while stirring, then add 1.0 g of surfactant, and then add 4.5 g of polyurethane thickener. After stirring for 30 minutes, add 500 g of the matting agent prepared in Example 3, and stir evenly to obtain a water-based topcoat varnish coating.

[0032] Application Example 4 Add 500 ml of pure acrylic emulsion to the container, slowly add 30 g of film-forming aid alcohol ester 12 under stirring, then add 1.0 g of surfactant, then add 4.5 g of polyurethane thickener, stir for 30 minutes, add 200 g of the matting agent prepared in Example 1, stir evenly to obtain a water-based topcoat varnish coating.

[0033] Application Example 5 Add 500 ml of pure acrylic emulsion to the container, slowly add 30 g of film-forming aid alcohol ester 12 under stirring, then add 1.0 g of surfactant, then add 4.5 g of polyurethane thickener, stir for 30 minutes, add 1000 g of the matting agent prepared in Example 1, stir evenly to obtain a water-based topcoat varnish coating.

[0034] Application Example 6 Add 500 ml of pure acrylic emulsion to the container, slowly add 30 grams of film-forming aid alcohol ester 12 while stirring, then add 1.0 grams of surfactant, and then add 4.5 grams of polyurethane thickener. After stirring for 30 minutes, add 1000 grams of the matting agent prepared in Comparative Example 1, and stir evenly to obtain a water-based topcoat varnish coating.

[0035] Application Example 7 Add 500 ml of pure acrylic emulsion to the container, slowly add 30 grams of film-forming aid alcohol ester 12 while stirring, then add 1.0 grams of surfactant, and then add 4.5 grams of polyurethane thickener. After stirring for 30 minutes, add 1000 grams of the matting agent prepared in Comparative Example 2, and stir evenly to obtain a water-based topcoat varnish coating.

[0036] Application Example 8 Add 500 ml of pure acrylic emulsion to the container, slowly add 30 grams of film-forming aid alcohol ester 12 while stirring, then add 1.0 grams of surfactant, and then add 4.5 grams of polyurethane thickener. After stirring for 30 minutes, add 1000 grams of the matting agent prepared in Comparative Example 3, stir evenly to obtain a water-based topcoat varnish coating.

[0037] The prepared topcoat varnish coatings of Application Examples 1 to 8 were evenly applied on a glass plate using a film former, and then dried at room temperature for 7 days.

[0038] Refer to standard GB / T 9754-2007 and test the gloss at 60° and 85° angles for cases 1 to 8. Refer to standard HG / T 5065-2016 for tests on transparency, sedimentation after 30 days of storage, and appearance for use cases 1 to 8; The polish resistance of cases 1 to 8 was tested using the rag friction test method: 1. Operation: Place the sample on the test bench and use 3M brand "Easy Clean 8-layer Durable Rag" to apply 10N friction pressure to the paint film surface. Rub repeatedly 100 times at a frequency of 30 times per minute with a stroke of 5 cm.

[0039] 2. Key Evaluation Indicator: Gloss retention at an 85-degree angle is measured. Higher gloss retention indicates better polish resistance. A gloss change of less than 5% is considered excellent, while a gloss change of 5-10% is considered good. Gloss testing is performed using a BYK-Gartner 4563 Micro Multi-Angle Glossmeter, in accordance with GB / T 9754-2007.

[0040]

[0041] The above data show that Application Examples 1-5, using the matting agents from Examples 1-3, achieved gloss values ​​ranging from 2.0 to 5.8 at 60° and 2.7 to 10.7 at 85°, demonstrating significant matting effectiveness. In contrast, Application Examples 6-8, using the matting agents from Comparative Examples 1-3, achieved gloss values ​​of 6.0 to 6.5 at 60° and 11.8 to 12.5 at 85°, significantly higher than those of the Example group. This indicates that matting performance deteriorates when the mass ratio of nano-calcium carbonate to hydroxyethyl cellulose ether (HEC) deviates from 80%:20%. In terms of appearance, Application Examples 1, 4, and 5 exhibit a more delicate texture, while Application Example 2 has a grainy texture and Application Example 3 has an orange peel-like texture. These differences are closely related to the particle size and preparation process of the composite cellulose ether thickener. Particle size and colloid milling parameters influence the uniformity of particle dispersion, leading to the differences in appearance and texture.

[0042] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed as above in terms of a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art can, without departing from the scope of the technical solution of the present invention, make some changes or modifications to equivalent embodiments using the technical contents disclosed above. However, any brief modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A matting agent, characterized in that The matting agent includes a composite cellulose ether thickener, alcohol ester lauryl and lithium magnesium silicate protective colloid; The composite cellulose ether thickener comprises a cellulose ether thickener and nano calcium carbonate, with a mass ratio of 80%:20%; The cellulose ether thickener is hydroxyethyl cellulose ether HEC or hydroxypropyl methyl cellulose ether HPMC with a particle size of 13-250 μm.

2. A matting agent according to claim 1, characterized in that: The preparation method of the composite cellulose ether thickener is: Nano-calcium carbonate and deionized water are mixed in a mass ratio of 1:(1.5-2), stirred at 1000-1200 rpm for 10-15 minutes, and refined by colloid grinding. Then, a cellulose ether thickener is added, the rotation speed is adjusted to 500-800 rpm, and stirring is continued for 20-30 minutes. After the stirring is completed, the composite cellulose ether thickener is obtained by spray drying and granulation.

3. A matting agent according to claim 2, characterized in that: The parameters of the colloidal grinding are: a gap between the stator and the rotor of 0.1-0.2 mm, a rotation speed of 2500-3500 rpm, and a processing time of 3-5 minutes.

4. A matting agent according to claim 1, characterized in that: The mass ratio of the composite cellulose ether thickener and the alcohol ester dodecahydrate in the matting agent is 1:1.2; The mass ratio of the lithium magnesium silicate protective gel to the composite cellulose ether thickener is 3:1; The concentration of the lithium magnesium silicate protective colloid is 8 w / v%.

5. A method for preparing the matting agent according to any one of claims 1 to 4, characterized in that: The specific steps of the preparation method are as follows: At room temperature, the alcohol ester dodecahydrate and the composite cellulose ether thickener were mixed according to a mass ratio, and stirred at 50-200 rpm for 5-20 minutes to obtain a mixture A; The mixture A is added to the lithium magnesium silicate protective colloid while stirring at a speed of 100 to 500 rpm. After the mixture A is completely added, stirring is continued for 0.5 to 1 hour to obtain the matting agent.

6. Use of a matting agent in the preparation of a water-based topcoat, characterized in that: The water-based topcoat comprises the matting agent according to any one of claims 1 to 4 or the matting agent prepared by the preparation method of the matting agent according to claim 5.

7. Use of a matting agent according to claim 6 in the preparation of a water-based topcoat, characterized in that: The preparation method of the water-based topcoat is as follows: 500 ml of pure acrylic emulsion is added to a container, 30 g of a film-forming aid alcohol ester 12 is slowly added under stirring, 1.0 g of a surfactant is added, and then 4.5 g of a polyurethane thickener is added. After stirring for 30 minutes, 200 to 1000 g of a matting agent is added, and the mixture is stirred evenly to obtain a water-based topcoat varnish coating.

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