Anti-indentation powder coating as well as preparation method and application thereof

Abstract

The invention relates to the technical field of powder coatings, and particularly discloses an anti-indentation powder coating as well as a preparation method and application thereof. The indentation-resistant powder coating provided by the invention is prepared from the following components in parts by weight: 60 to 80 parts of GMA type acrylic acid powder resin, 20 to 30 parts of curing agent and 2 to 10 parts of wax powder, the GMA type acrylic powder resin is prepared from the following components in parts by weight: 80 to 100 parts of soft monomer, 400 to 600 parts of hard monomer, 0 to 10 parts of carboxyl functional monomer, 200 to 400 parts of ester functional monomer, 20 to 100 parts of hydroxyl functional monomer, 10 to 30 parts of initiator, 5 to 20 parts of chain transfer agent, 800 to 1200 parts of solvent and 1 to 10 parts of nano additive. The invention further provides a preparation method and application of the indentation-resistant powder coating. According to the indentation-resistant powder coating, the compression resistance of a film-forming coating can be remarkably improved, and indentations generated in the stacking process of a coating film on the surface of a hub are effectively reduced.

Description

Technical Field

[0001] The present application relates to the technical field of powder coatings, and in particular to an anti-indentation powder coating and a preparation method and application thereof. Background Art

[0002] Acrylic transparent powder coating for wheel hub is an important protective and decorative material. It can not only enhance the appearance of the vehicle, but also effectively protect the wheel hub from the erosion of the external environment. It is widely used in the automotive industry. In the actual production process, the wheel hub needs to be stacked and stacked in the corresponding production and transportation links due to its small size and special shape. Although foam and other materials are used to isolate the wheel hubs, the acrylic powder coating on the surface of the wheel hub will still have indentations after a long time of stacking, which makes it difficult for the wheel hub to meet the quality standards and can only be scrapped, causing huge economic losses to the company. At present, the industry mainly uses the following methods to improve the compressive performance of acrylic powder coating: First, by adjusting the molecular structure of acrylic resin to enhance its own mechanical properties; second, adding various functional additives, such as toughening agents, wear-resistant agents, etc., to improve the overall performance of the coating; third, optimizing production process parameters, such as spraying thickness, curing temperature and time, etc., to ensure the uniformity and stability of the coating. However, the above method improves the compressive performance of the coating to a certain extent, but it still cannot completely avoid the indentation problem after long-term stacking, especially under high temperature conditions in summer, the indentation phenomenon is more serious.

[0003] Therefore, how to further improve the compressive resistance of acrylic powder coatings and reduce or even eliminate the indentation phenomenon of the coating film is a technical problem that needs to be solved urgently. Summary of the invention

[0004] In order to further improve the compression resistance of acrylic powder coatings and reduce or even eliminate the indentation phenomenon of acrylic powder coatings, the present application provides an indentation-resistant powder coating and a preparation method and application thereof.

[0005] The anti-indentation powder coating provided in this application adopts the following technical solution: An anti-indentation powder coating comprises the following components in parts by weight: 60-80 parts of GMA type acrylic powder resin, 20-30 parts of curing agent, and 2-10 parts of wax powder; The GMA type acrylic powder resin comprises the following components in parts by weight: 80-100 parts of soft monomers, 400-600 parts of hard monomers, 0-10 parts of carboxyl functional monomers, 200-400 parts of ester functional monomers, 20-100 parts of hydroxyl functional monomers, 10-30 parts of initiators, 5-20 parts of chain transfer agents, 800-1200 parts of solvents, and 1-10 parts of nano additives.

[0006] The present application provides an anti-indentation powder coating, which has excellent compression resistance and can effectively reduce the surface indentations generated by the wheel hub during the stacking process. In particular, it has excellent weather resistance under high temperature conditions and is not prone to indentations. Specifically, by using GMA-type acrylic powder resin as the main component, cross-linking can occur under the action of a curing agent, and a coating with a certain hardness and compression resistance can be formed. Wax powder is mainly used as a hardener, which can enhance the hardness of the coating, making the coating surface smoother and more resistant to indentation and impact. The curing agent can ensure that the powder coating cures quickly and forms a uniform and dense coating on the surface of the substrate, which plays a good protective and glazing role on the substrate. In summary, the anti-indentation powder coating used in the present application can effectively solve the indentation problem existing in the prior art, reduce production costs, and improve the qualified rate of wheel hub products.

[0007] Optionally, the anti-indentation powder coating comprises the following components in parts by weight: 70 parts of GMA type acrylic powder resin, 10 parts of curing agent, and 5 parts of wax powder.

[0008] In the present application, the GMA type acrylic powder resin is a self-made product of the company. The GMA type acrylic powder resin has high permeability, good weather resistance, and good compression resistance, and can be used for automobile wheels to solve the indentation problem.

[0009] In a specific embodiment, the GMA type acrylic powder resin includes the following components in parts by weight: 90 parts of soft monomer (butyl acrylate), 310 parts of hard monomer (methyl methacrylate), 160 parts of hard monomer (styrene), 6 parts of carboxyl functional monomer (methacrylic acid), 100 parts of ester functional monomer (benzyl methacrylate), 200 parts of ester functional monomer (glycidyl methacrylate), 50 parts of hydroxyl functional monomer (hydroxyethyl methacrylate), 20 parts of initiator (di-tert-amyl peroxide), 10 parts of chain transfer agent (dodecyl mercaptan), 1000 parts of solvent (xylene), and 5 parts of nano additive (modified silica).

[0010] Optionally, the wax powder is selected from 301 wax powder, PA-8800, AC-629A and Crayvallac SLT.

[0011] Optionally, the wax powder is 301 wax powder and AC-629A in a weight ratio of 1:(0.65-0.85).

[0012] In this application, by adding wax powder to the anti-indentation powder coating, the wax powder particles can be filled into tiny pores and cracks during the resin curing process, and tightly combined with the resin and other components to form a strong and tight coating structure. The tight structure of the coating has good density and hardness, and can well resist the influence of external forces, reduce wear and indentation. Through experimental research, this application found that by mixing the above-mentioned types of wax powder and controlling the weight ratio of the two within the above range, the obtained powder coating has better compression resistance and impact resistance after film formation, and the indentation resistance effect after using it on the wheel hub is better.

[0013] In some embodiments, the weight ratio of the 301 wax powder to AC-629A may be 1:(0.65-0.75) or 1:(0.75-0.85).

[0014] In a specific embodiment, the weight ratio of the 301 wax powder to AC-629A can also be 1:0.65, 1:0.75, 1:0.85 or 1:1.

[0015] Optionally, the curing agent is selected from one or more of dodecanedioic acid, eicosanedioic acid, isophorone diisocyanate, 1,5-naphthalene diisocyanate and diphenylmethane diisocyanate.

[0016] Optionally, the curing agent is dodecanedioic acid, 1,5-naphthalene diisocyanate and diphenylmethane diisocyanate in a weight ratio of 1:(0.3-0.5):(0.1-0.3).

[0017] In the present application, the curing agent can undergo a cross-linking reaction with the resin in the powder coating, so that the powder coating is dried and cured in a short time, thereby forming a coating with a certain strength and hardness. The present application has found through experimental research that the powder coating prepared by using the curing agent of the above type and ratio has a good curing effect on the surface of the substrate, and the coating film formed by curing has better compression resistance and impact resistance.

[0018] In some embodiments, the weight ratio of dodecanedioic acid, 1,5-naphthalene diisocyanate and diphenylmethane diisocyanate can be 1:0.4:(0.1-0.2), 1:0.4:(0.2-0.3), 1:(0.3-0.4):0.2 or 1:(0.4-0.5):0.2.

[0019] In a specific embodiment, the weight ratio of dodecanedioic acid, 1,5-naphthalene diisocyanate and diphenylmethane diisocyanate can also be 1:0.3:0.2, 1:0.4:0.2, 1:0.5:0.2, 1:0.4:0.1 or 1:0.4:0.3.

[0020] Optionally, the anti-indentation powder coating further comprises 5-10 parts of filler, 1-2 parts of leveling agent, 0.5-1 parts of degassing agent, and 0.5-2 parts of antioxidant.

[0021] In a second aspect, the present application provides a method for preparing an indentation-resistant powder coating.

[0022] A method for preparing an anti-indentation powder coating comprises the following steps: Weigh each component by weight and mix them evenly; then pour the mixture into an extruder, melt and extrude it at 120-130°C, send it to a tablet press for tableting, a coarse grinder for crushing, a fine grinder for grinding, and sieving to obtain an anti-indentation powder coating with a particle size of 45±2μm.

[0023] In a third aspect, the present application provides an application of an anti-indentation powder coating in a wheel hub.

[0024] In summary, this application has the following beneficial effects: 1. The present application provides an anti-indentation powder coating, which has excellent compression resistance. After being sprayed into a film on the surface of the wheel hub, the anti-indentation powder coating can effectively avoid or significantly reduce the indentation problem caused during stacking and transportation.

[0025] 2. This application uses a mixture of 301 wax powder and AC-629A wax phenol in a weight ratio of 1: (0.65-0.75) to prepare an indentation-resistant powder coating. The indentation grade of the obtained coating can reach A, and the hardness can reach 2H. Under a positive impact of 50kg·cm, the coating will not crack.

[0026] 3. The present application further uses dodecanedioic acid, 1,5-naphthalene diisocyanate and diphenylmethane diisocyanate in a weight ratio of 1: (0.3-0.5): (0.1-0.3) as curing agents, and the resulting anti-indentation powder coating forms a coating film with a higher hardness, which can reach 3H. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 Schematic diagram of the indentation detection device in the performance detection test. DETAILED DESCRIPTION

[0028] The present application provides an anti-indentation powder coating, comprising the following components in parts by weight: 60-80 parts of GMA type acrylic powder resin, 20-30 parts of curing agent, 2-10 parts of wax powder, 5-10 parts of filler, 1-2 parts of leveling agent, 0.5-1 part of degassing agent, and 0.5-2 parts of antioxidant; wherein the model of the wax powder is selected from 301 wax powder, PA-8800, AC-629A and Crayvallac SLT; the curing agent is selected from one or more of dodecanedioic acid, eicosanedioc acid, isophorone diisocyanate, 1,5-naphthalene diisocyanate and diphenylmethane diisocyanate. Furthermore, the wax powder is 301 wax powder and AC-629A in a weight ratio of 1:(0.65-0.85); the curing agent is dodecanedioic acid, 1,5-naphthalene diisocyanate and diphenylmethane diisocyanate in a weight ratio of 1:(0.3-0.5):(0.1-0.3).

[0029] The preparation method of the anti-indentation powder coating provided in the present application comprises the following steps: weighing each component by weight and mixing them evenly; then pouring the mixture into an extruder, melt-extruded at 120-130°C, sending it to a tablet press for tableting, a coarse crusher for crushing, a fine grinder for grinding, and sieving, thereby obtaining an anti-indentation powder coating with a particle size of 45±2μm.

[0030] In the present application, GMA type acrylic powder resin is a self-developed product of the company. The GMA type acrylic powder resin used in the examples of the present application is prepared according to the method in Example 3 in patent CN 202311821786.9; the CAS number of dodecanedioic acid is 693-23-2; the CAS number of eicosanedioic acid is 2424-92-2; the CAS number of isophorone diisocyanate is 4098-71-9; the CAS number of 1,5-naphthalene diisocyanate is 3173-72-6; the CAS number of diphenylmethane diisocyanate is 26447-40-5; 301 wax powder was purchased from Dongguan Thyssen New Materials Co., Ltd.; AC-629A wax powder was purchased from Honeywell; PA-8800 wax powder was purchased from Fenghong; Crayvallac SLT wax powder was purchased from Arkema; ​​the filler was silica powder purchased from Jiayan Minerals; the model of the leveling agent was ZY-1099; the CAS number of the degassing agent was 1592-23-0, purchased from Guangzhou Wanhe High-tech Materials Technology Co., Ltd.; the model of the antioxidant was antioxidant 1176. The raw materials, reagents, etc. used in this application can all be obtained commercially.

[0031] The present application is further described in detail below in combination with embodiments, performance testing and accompanying drawings.

[0032] Examples 1-3 Embodiments 1-3 respectively provide an anti-indentation powder coating.

[0033] The difference between the above embodiments is that the amount of GMA type acrylic powder resin added in the anti-indentation powder coating is specifically shown in Table 1 below.

[0034] The implementation method of the anti-indentation powder coating provided in Examples 1-3 comprises the following steps: respectively weighing a GMA-type acrylic powder resin, a curing agent (dodecanedioic acid) 20 g, a wax powder (301 wax powder) 5 g, a leveling agent 2 g, a degassing agent 1 g, and an antioxidant 2 g and mixing them evenly; then pouring the mixture into an extruder, melt-extruded at 130° C., sending it to a tablet press for tableting, a coarse crusher for crushing, a fine grinder for grinding, and sieving, thereby obtaining an anti-indentation powder coating with a particle size of 45±2 μm; wherein the raw material formula of the GMA-type acrylic powder resin is as follows: 90 g of butyl acrylate, 310 g of methyl methacrylate, 160 g of styrene, 6 g of methacrylic acid, 100 g of benzyl methacrylate, 200 g of glycidyl methacrylate, 50 g of hydroxyethyl methacrylate, 20 g of di-tert-amyl peroxide, 10 g of dodecyl mercaptan, 1000 g of xylene, and 5 g of modified silica.

[0035] Table 1 Addition amount of GMA type acrylic powder resin in Examples 1-3 Embodiment 4-9 Examples 4-9 each provide an anti-indentation powder coating.

[0036] The difference between the above embodiment and embodiment 2 is that the type and proportion of the wax powder in the anti-indentation powder coating are specifically shown in Table 2 below.

[0037] Table 2 Model and ratio of wax powder in Example 2, Example 4-9 Examples 10-17 Examples 10-17 each provide an anti-indentation powder coating.

[0038] The difference between the above embodiment and embodiment 7 is that the type and ratio of the curing agent in the anti-indentation powder coating are specifically shown in Table 3 below.

[0039] Table 3 Types and ratios of curing agents in Example 7 and Examples 10-17 Comparative Example 1 Comparative Example 1 provides an anti-indentation powder coating.

[0040] The difference between the comparative example and Example 2 is that the added amount of GMA type acrylic powder resin (self-developed) is 90g.

[0041] Comparative Example 2 Comparative Example 2 provides an anti-indentation powder coating.

[0042] The difference between the comparative example and Example 2 is that the GMA type acrylic powder resin (self-developed) is replaced by GMA acrylic powder resin (Mitsui Chemicals).

[0043] Comparative Example 3 Comparative Example 3 provides an anti-indentation powder coating.

[0044] The difference between the comparative example and Example 2 is that the GMA type acrylic powder resin (self-developed) is replaced by acrylic resin Neocryl B-811 (DSM).

[0045] Performance testing The anti-indentation powder coatings provided in Examples 1-17 and Comparative Examples 1-3 were used to prepare test samples, and then the indentation resistance, hardness and impact resistance of the test samples were tested. The results are shown in Table 4 below.

[0046] Sample preparation: Spray black primer, black paint and the anti-indentation powder coating prepared in this application onto the surface of the sample substrate (aluminum plate material, 10cm×10cm) in sequence, cure and dry to form a coating on the surface of the sample substrate to obtain the sample to be tested; the state of the unpressed part is used as the comparison standard.

[0047] 1. The test method for the indentation resistance test is as follows: (1) Before the test, place the weight and the small metal cube in a temperature test chamber at 55±2℃ for 1.5h; (2) Place packaging foam (purchased from Deka) on the surface of the sample to be tested, then place a small metal cube (volume 1 cm × 1 cm × 0.3 cm, bottom surface 1 cm × 1 cm) on the surface of the packaging foam, and then place a weight (2 kg ± 50 g) on ​​top of the small metal cube to form a Figure 1 The indentation detection device shown in the figure is placed in a constant temperature test box at 55±2℃ and maintained for 16h; (3) After the test, observe the indentation of the coating on the surface of the sample to evaluate the indentation resistance of the powder coating. The severity of the indentation is divided into no indentation A, slight indentation B, light indentation C, heavy indentation D, and severe indentation E.

[0048] 2. Hardness: Pencil hardness is tested according to standard GB / T6739-2006.

[0049] 3. Impact resistance: The impact resistance is tested according to the standard GB / T1732-1993.

[0050] Table 4 Performance test results of the anti-indentation powder coatings provided by Examples 1-17 and Comparative Examples 1-3 According to the test results in Table 4, the anti-indentation powder coatings provided in Examples 1-17 of the present application have an indentation grade of AB after the indentation resistance test, and the hardness of the formed coating film is H-3H. Under a positive impact of 50kg·cm, the coating film shows no cracks or slight cracks; while the anti-indentation powder coatings provided in Comparative Examples 1-3 have an indentation grade of CD after the indentation resistance test, and the hardness of the formed coating film is HB-H. Under a positive impact of 50kg·cm, the coating film cracks significantly or completely. Therefore, it is shown that the anti-indentation powder coating provided in the present application has good compression resistance and impact resistance, and can effectively avoid or significantly reduce the indentation problem caused during stacking and transportation after being used for spraying and filming on the wheel hub surface.

[0051] Although the present invention has been described in detail above with general descriptions and specific embodiments, it is obvious to those skilled in the art that some modifications or improvements may be made thereto based on the present invention. Therefore, these modifications or improvements made without departing from the spirit of the present invention all fall within the scope of protection claimed by the present invention.

Claims

1. An anti-indentation powder coating, characterized in that: The method comprises the following components in parts by weight: 60-80 parts of GMA type acrylic powder resin, 20-30 parts of curing agent, and 2-10 parts of wax powder; The GMA type acrylic powder resin comprises the following components in parts by weight: 80-100 parts of soft monomers, 400-600 parts of hard monomers, 0-10 parts of carboxyl functional monomers, 200-400 parts of ester functional monomers, 20-100 parts of hydroxyl functional monomers, 10-30 parts of initiators, 5-20 parts of chain transfer agents, 800-1200 parts of solvents, and 1-10 parts of nano additives.

2. The anti-indentation powder coating according to claim 1, characterized in that: The anti-indentation powder coating comprises the following components in parts by weight: 70 parts of GMA type acrylic powder resin, 10 parts of curing agent, and 5 parts of wax powder.

3. The anti-indentation powder coating according to claim 1, characterized in that: The wax powder is selected from 301 wax powder, 1778, PA-8800, AC-629A and Crayvallac SLT.

4. The anti-indentation powder coating according to claim 3, characterized in that: The wax powder is 301 wax powder and AC-629A in a weight ratio of 1: (0.65-0.85).

5. The anti-indentation powder coating according to claim 1, characterized in that: The curing agent is selected from one or more of dodecanedioic acid, eicosanedioic acid, isophorone diisocyanate, 1,5-naphthalene diisocyanate and diphenylmethane diisocyanate.

6. The anti-indentation powder coating according to claim 5, characterized in that: The curing agent is dodecanedioic acid, 1,5-naphthalene diisocyanate and diphenylmethane diisocyanate in a weight ratio of 1: (0.3-0.5): (0.1-0.3).

7. The anti-indentation powder coating according to claim 1, characterized in that: The anti-indentation powder coating further comprises 5-10 parts of filler, 1-2 parts of leveling agent, 0.5-1 parts of degassing agent and 0.5-2 parts of antioxidant.

8. The method for preparing the anti-indentation powder coating according to any one of claims 1 to 7, characterized in that: The method comprises the following steps: weighing each component by weight and mixing them evenly; then pouring the mixture into an extruder, melting and extruding at 100-130° C., sending the mixture into a tablet press for tableting, crushing with a coarse grinder, grinding with a fine grinder, and sieving, thereby obtaining an anti-indentation powder coating with a particle size of 45±2 μm.

9. Use of the anti-indentation powder coating according to any one of claims 1 to 8 in a wheel hub.

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