Matting agent, preparation method and application thereof

Abstract

This invention relates to the field of powder coating technology, specifically to a matting agent, its preparation method, and its application. The raw materials for preparing the matting agent, by weight, include: 28-40 parts of carboxyacrylate resin; 10-17.1 parts of aluminum isooctanoate; 1.5-4.1 parts of 2-mercaptobenzothiazole zinc; and 2-5.5 parts of a polycarboxylic acid polyamine salt. The matting agent proposed in this invention comprises carboxyacrylate resin, the accelerator 2-mercaptobenzothiazole zinc, aluminum isooctanoate, and a polycarboxylic acid polyether amine salt. This matting agent can be used in outdoor polyester / TGIC system powder coatings, achieving a matting performance of up to 5% (@60°) and exhibiting good storage stability.

Description

Technical Field

[0001] This invention relates to the field of powder coating technology, specifically to a matting agent, its preparation method, and its application. Background Technology

[0002] Powder coatings, as a solvent-free and low-VOC environmentally friendly coating, are increasingly favored by the market. The market for high-quality, low-gloss thermosetting powder coatings is also developing rapidly as people's requirements for the appearance of coatings are increasing.

[0003] In outdoor polyester / TGI type C powder coatings, the gloss of the coating film can be reduced to 30-40% (@60°) by adding matting fillers. To achieve even lower gloss, matting agents are usually added to the powder coating formulation. By adding different types of matting agents, the coating gloss can be reduced to 1-30% (@60°). Typically, adding matting agents based on carboxyacrylate resins can reduce the gloss to as low as 10% (@60°). For example, patent CN110982319A uses carboxyacrylate resins to achieve a minimum gloss of 4.5-5.5% (@60°), but it does not exhibit any lower gloss. Adding gloss-reducing agents to epoxy-based acrylic resin (GMA) systems can reduce gloss to as low as 5% (@60°), or even lower. For example, in the literature [High-Flexibility Epoxy Acrylic Matte Heat Transfer Powder Coating] and [Development of Bending-Resistant Epoxy Acrylic Matte Resin for Powder Coatings], the addition of GMA resin can reduce gloss to below 5% (@60°), with a limit of approximately 1% (@60°). However, the amount of GMA resin used in the above literature is relatively high, reaching over 10% of the total powder coating formulation. Furthermore, GMA resin is more expensive than carboxylated acrylic resin, resulting in significant matting costs. In addition, the gloss adjustability of GMA resin systems is poor, making them suitable only for matte coatings with a gloss level below 5%. There is also a problem with the storage stability of the resulting powder coatings. These shortcomings greatly limit its application range. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention aims to provide a matte agent for polyester TGIC systems, its preparation method, and its application. This matte agent does not contain GMA resin components and, at a low addition amount, can maintain the gloss of the coating prepared from matte polyester / TGIC C-type powder coatings stably within 5% (@60°), with a minimum of 3% (@60°). Furthermore, the gloss can be adjusted as needed by adjusting the addition ratio of the matte agent, and the resulting powder coating has good storage stability.

[0005] A matting agent, wherein the raw materials for preparing the matting agent comprise, by weight:

[0006]

[0007] Preferably, the carboxylated acrylic resin has an acid value of 200-250, a number-average molecular weight of 5000-7000, a softening point of 130-150℃, and a particle size of 50-200μm.

[0008] Preferably, the aluminum isooctanoate has a particle size of 20-40 μm.

[0009] Preferably, the 2-mercaptobenzothiazole zinc has a particle size of 5-10 μm.

[0010] Preferably, the preparation method of the polycarboxylic acid polyamine salt is as follows: dissolve the polycarboxylic acid and polyamine in a solvent to obtain a polycarboxylic acid solution and a polyamine solution, respectively; add the polyamine solution dropwise to the polycarboxylic acid solution under stirring and reflux conditions; after the addition is completed, keep stirring and refluxing; then evaporate the solvent to obtain the polycarboxylic acid polyamine salt.

[0011] Preferably, the polycarboxylic acid is one of acetic acid, oxalic acid, citric acid, and pyromellitic acid.

[0012] Preferably, the polyamine is one of melamine, 2,4,6-triaminotoluene, amino-terminated modified polyether (such as polyetheramine T403, T5000), and tetra-(4-aminophenyl)ethylene.

[0013] Preferably, a method for preparing a matting agent includes the following steps: placing carboxyacrylate resin, aluminum isooctanoate, zinc 2-mercaptobenzothiazole and polycarboxylic acid polyamine salt in the same mixing tank and mixing at a speed of 600 r / min for 5-15 min to obtain the matting agent.

[0014] Preferably, the matting agent is used in the coatings industry.

[0015] The beneficial effects of the present invention are as follows: The matting agent proposed in this invention contains carboxylated acrylic resin, accelerator 2-mercaptobenzothiazole zinc and aluminum isooctanoate, and polyetheramine salt of polyacid. This matting agent can be used as an outdoor polyester / TGIC system powder coating, with a matting performance of up to 5% (@60°) and good storage stability. Detailed Implementation

[0016] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0017] The polyesters used in the following comparative examples and embodiments are all commercially available 93 / 7 polyester resins, and the extrusion and spraying conditions for different powder coating formulations are kept consistent. During preparation, the powder coating components are premixed, extruded through a twin-screw extruder, pressed into sheets, crushed, and then pulverized through a mill. The powder coating is then passed through an 180-mesh sieve and sprayed onto a tinplate using an electrostatic spray gun. The curing conditions are 200℃ for 10 minutes. The resulting coating thickness is controlled between 60 and 80 μm.

[0018] Example 1: Synthesis of melamine acetate. 12.6 g (0.1 mol) of melamine was weighed and dissolved in 160 mL of anhydrous methanol. 20.0 g (0.33 mol) of acetic acid was placed in a round-bottom flask and heated and stirred in a water bath at 60°C. The melamine-methanol solution was then added dropwise to the acetic acid. After the addition was complete, the reaction was continued with heating and stirring in a water bath for 30 min. The solvent was then evaporated to obtain melamine acetate, which was cooled and set aside for later use.

[0019] The formulation of matting agent A is as follows: 32.3 parts carboxyacrylate resin, 16.0 parts aluminum isooctanoate, 3.0 parts 2-mercaptobenzothiazole zinc, and 3.7 parts melamine acetate. After weighing the above raw materials, they were placed in the same mixing tank and mixed at 600 rpm for 15 minutes to obtain the desired matting agent A. Its test formulation is as follows:

[0020]

[0021]

[0022] Table 1

[0023] Example 2: Synthesis of triaminotoluene acetate. 13.7 g (0.1 mol) of triaminotoluene was weighed and dissolved in 200 mL of anhydrous ethanol. 20.0 g (0.33 mol) of acetic acid was placed in a round-bottom flask and heated and stirred in a water bath at 80 °C. The triaminotoluene ethanol solution was then added dropwise to the acetic acid. After the addition was complete, the reaction was continued with heating and stirring in a water bath for 30 min. The solvent was then evaporated to obtain triaminotoluene acetate, which was cooled and set aside for later use.

[0024] The formulation of matting agent B is as follows: 32.9 parts carboxyacrylate resin, 14.8 parts aluminum isooctanoate, 3.2 parts 2-mercaptobenzothiazole zinc, and 4.1 parts triaminotoluene acetate. After weighing the above raw materials, they were placed in the same mixing tank and mixed at 600 rpm for 15 minutes to obtain the desired matting agent B. Its test formulation is as follows:

[0025] Polyester SJ4ET GH2205 NH3307 P4600 Polyester / g 550 550 550 550 TGIC / g 45 45 45 45 Brightening agent / g 10 10 10 10 Leveling agent / g 10 10 10 10 Benzoin / g 3 3 3 3 Carbon black / g 6 6 6 6 Barium extinction / g 321 321 321 321 Matting agent B / g 55 55 55 55 Total amount / g 1000 1000 1000 1000

[0026] Table 2

[0027] Example 3: Synthesis of triaminotoluene oxalate. 13.7 g (0.1 mol) of triaminotoluene was weighed and dissolved in 200 mL of water. 15.3 g (0.17 mol) of oxalic acid was placed in a round-bottom flask and 50 mL of water was added. The mixture was heated and stirred in a water bath at 100°C to dissolve the acid. The triaminotoluene aqueous solution was then added dropwise to the oxalic acid. After the addition was complete, the mixture was heated and stirred in a water bath for 20 min. The solvent was then evaporated to obtain triaminotoluene oxalate, which was cooled and set aside for later use.

[0028] The formulation of matting agent C is as follows: 40.0 parts carboxyacrylate resin, 10.6 parts aluminum isooctanoate, 1.5 parts 2-mercaptobenzothiazole zinc, and 2.9 parts triaminotoluene oxalate. After weighing the above raw materials, they were placed in the same mixing tank and mixed at 600 rpm for 15 minutes to obtain the desired matting agent C. Its test formulation is as follows:

[0029] Polyester SJ4ET GH2205 NH3307 P4600 Polyester / g 550 550 550 550 TGIC / g 45 45 45 45 Brightening agent / g 10 10 10 10 Leveling agent / g 10 10 10 10 Benzoin / g 3 3 3 3 Carbon black / g 6 6 6 6 Barium extinction / g 321 321 321 321 Matting agent C / g 55 55 55 55 Total amount / g 1000 1000 1000 1000

[0030] Table 3

[0031] Example 4: Synthesis of triaminotoluene citrate. 13.7 g (0.1 mol) of triaminotoluene was weighed and dissolved in 200 mL of anhydrous ethanol. 23.1 g (0.11 mol) of citric acid monohydrate was placed in a round-bottom flask and 50 mL of anhydrous ethanol was added. The mixture was heated and stirred in a water bath at 80 °C to dissolve the toluene. The triaminotoluene aqueous solution was then added dropwise to oxalic acid. After the addition was complete, the mixture was heated and stirred in a water bath for 20 min. The solvent was then evaporated to obtain triaminotoluene citrate, which was cooled and set aside for later use.

[0032] The formulation of matting agent D is as follows: 32.9 parts carboxyacrylate resin, 13.9 parts aluminum isooctanoate, 2.7 parts 2-mercaptobenzothiazole zinc, and 5.5 parts triaminotoluene citrate. After weighing the above raw materials, they were placed in the same mixing tank and mixed at 600 rpm for 15 minutes to obtain the desired matting agent D. Its test formulation is as follows:

[0033]

[0034]

[0035] Table 4

[0036] Example 5: Synthesis of polyetheramine T403 salt of citric acid. 27.3 g (0.13 mol) of citric acid was weighed and dissolved in 30 mL of anhydrous ethanol. The solution was heated and stirred in a water bath at 80 °C. 40.3 g (0.1 mol) of polyetheramine T403 was added dropwise to the citric acid-ethanol solution. After the addition was complete, the solution was heated and stirred for 30 min. The solvent was then evaporated to obtain polyetheramine T403 salt of citric acid, which was cooled and set aside for later use.

[0037] The formulation of matting agent E is as follows: 34.9 parts carboxyacrylate resin, 15.7 parts aluminum isooctanoate, 1.5 parts 2-mercaptobenzothiazole zinc, and 2.9 parts citrate polyetheramine T403 salt. After weighing the above raw materials, they were placed in the same mixing tank and mixed at 600 rpm for 10 minutes to obtain the desired matting agent E. Its test formulation is as follows:

[0038] Polyester SJ4ET GH2205 NH3307 P4600 Polyester / g 550 550 550 550 TGIC / g 45 45 45 45 Brightening agent / g 10 10 10 10 Leveling agent / g 10 10 10 10 Benzoin / g 3 3 3 3 Carbon black / g 6 6 6 6 Barium extinction / g 321 321 321 321 Matting agent E / g 55 55 55 55 Total amount / g 1000 1000 1000 1000

[0039] Table 5

[0040] Example 6: Synthesis of pyromellitic acid polyetheramine T403 salt. 25.4 g (0.1 mol) of pyromellitic acid was weighed and dissolved in 30 mL of anhydrous ethanol. The solution was heated and stirred in a water bath at 80°C. 40.3 g (0.1 mol) of polyetheramine T403 was added dropwise to the pyromellitic acid ethanol solution. After the addition was complete, the solution was heated and stirred for 30 min. The solvent was then evaporated to obtain pyromellitic acid polyetheramine T403 salt, which was cooled and set aside for later use.

[0041] The formulation of matting agent F is as follows: 35.8 parts carboxyacrylate resin, 14.3 parts aluminum isooctanoate, 2.9 parts 2-mercaptobenzothiazole zinc, and 2.0 parts pyromellitic acid polyetheramine T403 salt. After weighing the above raw materials, they were placed in the same mixing tank and mixed at 600 rpm for 10 minutes to obtain the desired matting agent F. Its test formulation is as follows:

[0042] Polyester SJ4ET GH2205 NH3307 P4600 Polyester / g 550 550 550 550 TGIC / g 45 45 45 45 Brightening agent / g 10 10 10 10 Leveling agent / g 10 10 10 10 Benzoin / g 3 3 3 3 Carbon black / g 6 6 6 6 Barium extinction / g 321 321 321 321 Matting agent F / g 55 55 55 55 Total amount / g 1000 1000 1000 1000

[0043] Table 6

[0044] Example 7: Synthesis of tetra-(4-aminophenyl)ethylene acetate. 6.6 g (0.11 mol) of acetic acid was weighed and dissolved in 80 mL of anhydrous ethanol in a round-bottom flask. 39.2 g (0.1 mol) of tetra-(4-aminophenyl)ethylene was added to 320 mL of anhydrous ethanol and ultrasonically dispersed and dissolved. The tetra-(4-aminophenyl)ethylene solution was then added dropwise to the acetic acid solution, and the mixture was heated and stirred in a water bath at 80 °C for 120 min. The solvent was then evaporated to obtain tetra-(4-aminophenyl)ethylene acetate, which was cooled and set aside for later use.

[0045] The formulation of matting agent G is as follows: 28.5 parts carboxyacrylate resin, 17.1 parts aluminum isooctanoate, 4.1 parts 2-mercaptobenzothiazole zinc, and 5.3 parts tetra-(4-aminophenyl)ethylene acetate. After weighing the above raw materials, they were placed in the same mixing tank and mixed at 600 rpm for 10 minutes to obtain the desired matting agent G. Its test formulation is as follows:

[0046] Polyester SJ4ET GH2205 NH3307 P4600 Polyester / g 550 550 550 550 TGIC / g 45 45 45 45 Brightening agent / g 10 10 10 10 Leveling agent / g 10 10 10 10 Benzoin / g 3 3 3 3 Carbon black / g 6 6 6 6 Barium extinction / g 321 321 321 321 Matting agent G / g 55 55 55 55 Total amount / g 1000 1000 1000 1000

[0047] Table 7

[0048] Example 8: The synthesis of triaminotoluene citrate was the same as in Example 4.

[0049] The formulation of matting agent H is as follows: 15.1 parts carboxyacrylate resin, 10.7 parts aluminum isooctanoate, 2.1 parts 2-mercaptobenzothiazole zinc, and 2.1 parts triaminotoluene citrate. After weighing the above raw materials, they were placed in the same mixing tank and mixed at 600 rpm for 15 minutes to obtain the desired matting agent H. Its test formulation is as follows:

[0050]

[0051]

[0052] Table 8

[0053] Comparative Example 1: Matting Agent 1 used a matting agent for outdoor polyester / TGIC powder coatings from Anhui Jingcheng. This matting agent is a carboxylated acrylic polyester system, free of GMA resin and amine components. At an addition of 55 parts, this matting agent achieved a minimum gloss of 6-8% (@60°). Its test formulation is as follows:

[0054] Polyester SJ4ET GH2205 NH3307 P4600 Polyester / g 550 550 550 550 TGIC / g 45 45 45 45 Brightening agent / g 10 10 10 10 Leveling agent / g 10 10 10 10 Benzoin / g 3 3 3 3 Carbon black / g 6 6 6 6 Barium extinction / g 321 321 321 321 Matting agent 1 / g 55 55 55 55 Total amount / g 1000 1000 1000 1000

[0055] Table 9

[0056] Comparative Example 2: Matting Agent 2 was formulated with 33.3 parts carboxyacrylate resin, 15.9 parts aluminum isooctanoate, 3.2 parts 2-mercaptobenzothiazole zinc, and 2.6 parts 2,4,6-triaminotoluene. The above raw materials were weighed and placed in the same mixing tank, and mixed at 600 rpm for 10 minutes to obtain the desired matting agent 2. Its test formulation is as follows:

[0057]

[0058]

[0059] Table 10

[0060] test:

[0061] 1. Glossiness Test. The test was conducted according to GB / T9754-2007 standard. The reflectance at 60° was directly measured using a Sanon HG268 gloss meter. The table below shows the glossiness test results for the comparative and example cases:

[0062]

[0063] Table 11

[0064] Table 11 shows that Comparative Example 2 and Examples 1-7 can all achieve a gloss level of less than 5% (@60°) when the matting agent content is 5.5%. Compared to Comparative Example 1, different polyesters can all achieve a significant reduction in gloss. Furthermore, in Example 8, a matting agent content of 3% achieved the same matting performance as Comparative Example 1 with a 5.5% matting agent content. These results indicate that the matting agent containing polyamines or polyacid-modified polyamines in this invention can effectively reduce the gloss of outdoor polyester / TGIC powder coatings to a matte finish of less than 5% (@60°) and exhibits good gloss adjustability.

[0065] 2. Storage stability test. The test was conducted according to GB / T21782.8-2008 standard, with storage at 40℃±1℃, and the changes in appearance and gloss were tested after 24h, 7d, and 28d of storage. The samples used in this test were powder coatings matched with polyester P4600 in each comparative example and each embodiment. The relevant test results are shown in the table below:

[0066] Level Time 24h 7d 28d Example 1 0 1 1 Example 2 0 1 1 Example 3 0 1 1 Example 4 0 1 1 Example 5 0 1 1 Example 6 0 1 1 Example 7 0 1 1 Example 8 0 1 1 Comparative Example 1 0 1 1 Comparative Example 2 2 3 3

[0067] Table 12

[0068]

[0069]

[0070] Table 13

[0071] Table 12 shows that the powder coating of Comparative Example 2 has poor storage stability. This is because Comparative Example 2 uses triaminotoluene, which has excessively strong curing activity and is highly reactive even at room temperature, causing the powder coating to easily agglomerate. Similarly, Table 13 also shows that the gloss of the powder coating of Comparative Example 2 increases significantly, for the same reason. The agglomeration of Examples 1-8 is not significantly different from that of Comparative Example 1. The gloss changes of Examples 1-8 are also more gradual; under the same storage days, the gloss of all examples is lower than that of the comparative example. This is because the polyamine and polyacid form a salt, exhibiting latent curing characteristics, which improves the storage stability of the powder coating. Furthermore, the storage stability of Example 8 is very close to that of Comparative Example 1. The above storage stability test results indicate that polyacid-polyamine salts can ensure the storage stability of powder coatings.

[0072] As can be seen from the above embodiments, the present invention provides a matting agent. This type of matting agent contains carboxylated acrylic resin, accelerator 2-mercaptobenzothiazole zinc, aluminum isooctanoate, and poly(amino ether) salt of polyacids. It can be used as a matting agent for outdoor polyester / TGI C system powder coatings, achieving a matting performance of up to 5% (@60°) and exhibiting good storage stability. The matting effect it achieves is unattainable by general matting agents for outdoor polyester / TGI C system powder coatings.

[0073] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0074] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention.

Claims

1. An optical matting agent characterized in that, The raw materials for preparing the matting agent consist of the following components in parts by weight: 28-40 parts of carboxylated acrylic resin; Aluminum isooctanoate 10-17.1 parts; 1.5-4.1 parts of 2-mercaptobenzothiazole zinc; 2-5.5 parts of polycarboxylic acid polyamine salts.

2. The matting agent according to claim 1, characterized in that: The acid value of the carboxylated acrylic resin is 200-250, the number average molecular weight is 5000-7000, the softening point is 130-150℃, and the particle size is 50-200μm.

3. The matting agent according to claim 2, characterized in that: The aluminum isooctanoate has a particle size of 20-40 μm.

4. The matting agent according to claim 1, characterized in that: The 2-mercaptobenzothiazole zinc has a particle size of 5-10 μm.

5. The matting agent according to claim 1, characterized in that: The preparation method of the polycarboxylic acid polyamine salt is as follows: dissolve the polycarboxylic acid and polyamine separately in a solvent to obtain a polycarboxylic acid solution and a polyamine solution, and add the polyamine solution dropwise to the polycarboxylic acid solution under stirring and reflux conditions. After the addition is completed, keep stirring and refluxing. The solvent is then evaporated to obtain polycarboxylic acid polyamine salts.

6. The matting agent according to claim 1, characterized in that: The polycarboxylic acid is one of oxalic acid, citric acid, and pyromellitic acid.

7. The matting agent according to claim 1, characterized in that: The polyamine is one of melamine, 2,4,6-triaminotoluene, amino-terminated modified polyether, and tetra-(4-aminophenyl)ethylene.

8. A method for preparing a matting agent as described in any one of claims 1-7, characterized in that, The preparation method includes the following steps: placing carboxyacrylate resin, aluminum isooctanoate, zinc 2-mercaptobenzothiazole and polycarboxylic acid polyamine salt in the same mixing tank and mixing at a speed of 600 r / min for 5-15 min to obtain the matting agent.

9. The application of a matting agent as described in any one of claims 1-7 in the field of coatings.

Images