A wear-resistant powder coating and its preparation method

Abstract

The present invention relates to the field of coating technology and provides a wear-resistant powder coating and a preparation method thereof. The wear-resistant powder coating comprises the following components in parts by weight: 15-25 parts of polyester resin A, 10-15 parts of polyester resin A curing agent, 20-30 parts of polyester resin B, 1-5 parts of polyester resin B curing agent, 1-2 parts of hardening wax powder, 50-60 parts of ceramic powder, and 1-2 parts of leveling agent. The acid value of polyester resin A is lower than that of polyester resin B, and polyester resin B is composed of a first polyester resin and a second polyester resin, the first polyester resin and the second polyester resin having the same acid value, and the viscosity of the first polyester resin being lower than that of the second polyester resin. This technical solution solves the problem of poor wear resistance of powder coatings in related technologies.

Description

Technical Field

[0001] The present invention relates to the technical field of coatings, and in particular to a wear-resistant powder coating and a preparation method thereof. Background Art

[0002] Powder coating is a new type of solvent-free, solid powder coating that is environmentally friendly, highly effective, and durable. During its preparation, various ingredients are mixed, melted, extruded, and crushed into fine powder particles. Unlike traditional solvent-based and water-based coatings, powder coatings do not require solvent dilution during application. Instead, powder particles are applied to the surface of the substrate through electrostatic spraying or fluidized bed dipping. The coating then melts, flows, and solidifies, forming a uniform, continuous film. Powder coating is widely used in the construction, automotive, furniture, and home appliance sectors.

[0003] However, with the increasing demands for product performance across various industries, the performance of conventional powder coatings has gradually become insufficient to meet the needs of certain specific applications, especially in terms of wear resistance. For example, outdoor amusement facilities in parks and playgrounds, such as slides and climbing frames, are subjected to heavy daily use and friction from children. Under the dual effects of this high-frequency friction and harsh outdoor environments (such as UV radiation and rain erosion), conventional powder coatings quickly lose their protective effects. Once the coating wears away, the metal structures of the amusement facilities are prone to rust, and wooden parts may also decay due to the loss of protection. This not only affects the service life of the facilities but also poses a threat to children's safety. For another example, bicycle components such as frames, handlebars, and chains are subject to various friction and impacts during riding. Conventional powder coatings often perform poorly in these conditions and are prone to scratches and wear. For cyclists who frequently go mountain biking or long-distance cycling, the coating on the frame surface will wear out more quickly, which not only affects the appearance of the bicycle but also may corrode the metal parts of the frame, reducing the safety and service life of the bicycle.

[0004] Therefore, it is necessary to develop a powder coating with high wear resistance. Summary of the Invention

[0005] The present invention provides a wear-resistant powder coating and a preparation method thereof, which solves the problem of poor wear resistance of the powder coating in the related art.

[0006] The technical solution of the present invention is as follows: The present invention proposes a wear-resistant powder coating, comprising the following component raw materials in parts by weight: 15-25 parts of polyester resin A, 10-15 parts of polyester resin A curing agent, 20-30 parts of polyester resin B, 1-5 parts of polyester resin B curing agent, 1-2 parts of hardening wax powder, 50-60 parts of ceramic powder, and 1-2 parts of leveling agent; the acid value of the polyester resin A is less than the acid value of the polyester resin B, and the polyester resin B is composed of a first polyester resin and a second polyester resin, the acid value of the first polyester resin and the second polyester resin are the same and the viscosity of the first polyester resin is lower than the viscosity of the second polyester resin.

[0007] As a further technical solution, the acid value of the first polyester resin is 48~55mgKOH / g and the viscosity is 3500~4500mPa·s; the acid value of the second polyester resin is 48~55mgKOH / g and the viscosity is 6000~9000mPa·s.

[0008] In the present invention, the acid values of the first polyester resin and the second polyester resin are both controlled within a range of 48 to 55 mgKOH / g. When the acid value is too high, it means that the resin molecular chain contains a large amount of carboxyl groups, and the reaction rate with the curing agent is too fast, which may cause local overheating, sudden polymerization, and the formation of an uneven cross-linked structure. In addition, when the acid value is too high, the polarity of the resin is enhanced, which will reduce the compatibility with non-polar or weakly polar components (such as hardening wax powder and ceramic powder), resulting in uneven dispersion of these components in the system, agglomeration, and other problems, affecting the performance of the coating. However, when the acid value is too low, the number of carboxyl groups on the resin molecular chain is small, the reaction with the curing agent is insufficient, the cross-linking density is low, the hardness and wear resistance of the coating are greatly reduced, and it cannot effectively resist external friction. In addition, when the polarity is weak, it will also affect the compatibility with additives such as leveling agents. Therefore, keeping the acid value within an appropriate range helps to further improve the wear resistance of the powder coating.

[0009] In the present invention, the low-viscosity first polyester resin has good fluidity and can diffuse rapidly in the coating system. When preparing wear-resistant powder coatings, this fluidity enables it to more fully wrap and infiltrate wear-resistant fillers such as hardening wax powder and ceramic powder, and evenly disperse the fillers in the coating system; while the high-viscosity second polyester resin plays a stabilizing role after the fillers are dispersed, preventing the fillers from settling or agglomerating during subsequent processing and storage. The two resins with different viscosities cooperate with each other to ensure that the wear-resistant fillers are evenly distributed in the coating, so that the fillers can more effectively play their role in enhancing the wear resistance, further improving the overall wear resistance of the coating.

[0010] As a further technical solution, the mass ratio of the first polyester resin to the second polyester resin is 1-5:2; for example, it can be 1:2, 1:1, 3:2, 2:1, 5:2, preferably 1-1.5:1.

[0011] In the present invention, by adjusting the mass ratio of the first polyester resin to the second polyester resin, the synergistic effect of the two is brought into play, which promotes the formation of a more complete and uniform cross-linked structure, makes the microstructure of the coating denser, effectively reduces the stress concentration caused by structural defects, enhances the hardness and integrity of the coating, makes it less likely to be damaged or fall off when subjected to friction, and further effectively improves the wear resistance.

[0012] As a further technical solution, the polyester resin A has a hydroxyl value of 75-85 mgKOH / g, a viscosity of 3000-6000 mPa·s, and an acid value of ≤5 mgKOH / g.

[0013] In the present invention, the hydroxyl value of the polyester resin A is 75-85 mgKOH / g. The appropriate hydroxyl value enables the polyester resin A and the polyester resin B to be bonded to each other through chemical bonds or intermolecular forces to form a stable blending system, avoid phase separation, and ensure the stability of the coating system. In addition, the appropriate viscosity is conducive to uniform mixing of the polyester resin A with fillers such as hardening wax powder and ceramic powder, so that the fillers can be fully dispersed in the resin matrix, enhancing the interfacial bonding force between the filler and the resin, thereby synergistically improving the wear resistance of the coating.

[0014] As a further technical solution, the polyester resin A curing agent includes one or more of toluene diisocyanate, diphenylmethane diisocyanate, and hexamethylene diisocyanate, preferably diphenylmethane diisocyanate.

[0015] In the present invention, the polyester resin A curing agent contains highly active isocyanate groups, which can react quickly and fully with the hydroxyl groups in the polyester resin A to form carbamate bonds, thereby promoting rapid cross-linking and curing of the coating, forming a relatively complex and dense three-dimensional network structure, giving the coating excellent hardness and strength, enabling the coating to effectively resist external friction, scratches and wear, and significantly improving wear resistance. At the same time, the rapid curing reaction is also conducive to improving production efficiency and shortening the processing cycle.

[0016] As a further technical solution, the polyester resin B curing agent is curing agent TGIC (triglycidyl isocyanurate).

[0017] In the present invention, the curing agent TGIC can react with the carboxyl group in the polyester resin B to form a stable chemical bond, thereby curing the coating and forming a highly cross-linked network structure in the polyester resin B, thereby improving the hardness and strength of the coating.

[0018] As a further technical solution, the ceramic powder includes one or more of aluminum oxide, silicon carbide, silicon nitride, titanium dioxide, and barium titanate, preferably aluminum oxide.

[0019] As a further technical solution, the leveling agent includes one or more of BYK-333, BYK-377, and BYK-381.

[0020] In the present invention, the addition of the leveling agent can not only effectively reduce the surface tension of the coating, so that the coating can be spread more evenly on the surface of the coated object during the coating process, reducing the occurrence of surface defects such as flow marks, shrinkage holes, and orange peel, thereby forming a flat and smooth coating, but the leveling agent can also promote the uniform distribution of the various components of the coating during the curing process, making the curing reaction more sufficient and uniform, avoiding the occurrence of local incomplete curing or over-curing. The uniform curing process helps to form a dense and stable coating structure, and improves the hardness, strength and wear resistance of the coating.

[0021] The present invention also provides a method for preparing a wear-resistant powder coating, which is used to prepare the wear-resistant powder coating, comprising the following steps:

[0022] S1, mixing the raw materials to obtain a mixed powder;

[0023] S2. The mixed powder is extruded and ground to obtain a wear-resistant powder coating.

[0024] As a further technical solution, in step S1, the mixing time is 5 to 8 minutes.

[0025] As a further technical solution, in step S2, the temperature of the first extrusion zone is 90°C, and the temperature of the second extrusion zone is 120°C.

[0026] As a further technical solution, the wear-resistant powder coating has a D10 of 13 μm, a D50 of 40 μm, and a D90 of 85 μm.

[0027] The working principle and beneficial effects of the present invention are:

[0028] 1. In the present invention, a combination of polyester resin A and polyester resin A curing agent, and polyester resin B and polyester resin B curing agent is adopted, so that the coating can form a denser and more stable cross-linked structure during the curing process. The hardening wax powder can effectively reduce the friction coefficient of the coating surface, give the coating good slipperiness, and reduce the damage to the coating caused by external friction. The ceramic powder has extremely high hardness and wear resistance. After being added to the coating system, it greatly enhances the wear resistance of the coating.

[0029] 2. In the present invention, a first polyester resin and a second polyester resin with the same acid value but different viscosities are used in combination. Due to the same acid value, the reaction activities of the two polyester resins with the polyester resin B curing agent are basically the same, and the cross-linking reaction can occur more evenly during the curing process. Compared with a single polyester resin, this combination can form a higher and more uniform cross-linking density; the first polyester resin and the second polyester resin with different viscosities cooperate with each other to form a more complex and ordered microstructure during the coating curing process. The reason is that: the low-viscosity high-acid polyester resin has good fluidity and can diffuse rapidly in the system to fill the gaps inside the coating, while the high-viscosity high-acid polyester resin can provide strong cohesion and support, making the coating structure tighter. This structure helps to disperse and buffer external friction stress, reduce coating wear caused by local stress concentration, and thus effectively improve the wear resistance of the coating. DETAILED DESCRIPTION

[0030] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0031] In the following examples and comparative examples:

[0032] Polyester resin A: hydroxyl value is 75-85 mgKOH / g, viscosity is 3000-6000 mPa·s, model is Hypomer PE9624;

[0033] The first polyester resin has an acid value of 48-55 mgKOH / g and a viscosity of 3500-4500 mPa·s; the model is YC8000A, and was purchased from Anhui Yongchang New Materials Technology Co., Ltd.

[0034] The second polyester resin has an acid value of 48-55 mgKOH / g, a viscosity of 6000-9000 mPa·s, a model number of YC8510, and was purchased from Anhui Yongchang New Materials Technology Co., Ltd.;

[0035] Enhanced wax powder: model LANCO TF1788;

[0036] Alumina: average particle size is 500 mesh.

[0037] Example 1

[0038] A method for preparing a wear-resistant powder coating comprises the following steps:

[0039] S1. Mix 15 parts of polyester resin A, 10 parts of diphenylmethane diisocyanate, 20 parts of polyester resin B, 1 part of curing agent TGIC, 1 part of hardening wax powder, 50 parts of aluminum oxide, and 1 part of BYK-333 for 5 minutes to obtain a mixed powder, wherein polyester resin B is composed of a first polyester resin YC8000A and a second polyester resin YC8510 in a mass ratio of 1:1;

[0040] S2. The mixed powder is extruded through a screw extruder with the temperature of zone 1 being 90°C and the temperature of zone 2 being 120°C. The mixed powder is ground to a D10 of 13 μm, a D50 of 40 μm, and a D90 of 85 μm to obtain a wear-resistant powder coating.

[0041] Example 2

[0042] A method for preparing a wear-resistant powder coating comprises the following steps:

[0043] S1. Mix 20 parts of polyester resin A, 12 parts of diphenylmethane diisocyanate, 25 parts of polyester resin B, 3 parts of curing agent TGIC, 1.5 parts of hardening wax powder, 55 parts of aluminum oxide, and 1.5 parts of BYK-377 for 6 minutes to obtain a mixed powder, wherein polyester resin B is composed of a first polyester resin YC8000A and a second polyester resin YC8510 in a mass ratio of 1:1;

[0044] S2. The mixed powder is extruded through a screw extruder with the temperature of zone 1 being 90°C and the temperature of zone 2 being 120°C. The mixed powder is ground to a D10 of 13 μm, a D50 of 40 μm, and a D90 of 85 μm to obtain a wear-resistant powder coating.

[0045] Example 3

[0046] A method for preparing a wear-resistant powder coating comprises the following steps:

[0047] S1. Mix 25 parts of polyester resin A, 15 parts of diphenylmethane diisocyanate, 30 parts of polyester resin B, 5 parts of curing agent TGIC, 2 parts of hardening wax powder, 60 parts of aluminum oxide, and 2 parts of BYK-381 for 8 minutes to obtain a mixed powder, wherein polyester resin B is composed of a first polyester resin YC8000A and a second polyester resin YC8510 in a mass ratio of 1:1;

[0048] S2. The mixed powder is extruded through a screw extruder with the temperature of zone 1 being 90°C and the temperature of zone 2 being 120°C. The mixed powder is ground to a D10 of 13 μm, a D50 of 40 μm, and a D90 of 85 μm to obtain a wear-resistant powder coating.

[0049] Example 4

[0050] Compared with Example 1, Example 4 is different in that the polyester resin B is composed of the first polyester resin YC8000A and the second polyester resin YC8510 in a mass ratio of 3:2.

[0051] Comparative Example 1

[0052] Compared with Example 1, Comparative Example 1 is different in that the polyester resin B is only the first polyester resin YC8000A.

[0053] Comparative Example 2

[0054] Compared with Example 1, Comparative Example 2 is different in that the polyester resin B is only the second polyester resin YC8510.

[0055] Comparative Example 3

[0056] Compared with Example 1, the difference of Comparative Example 3 is that the second polyester resin is replaced by a polyester resin with a model number of YC8600, an acid value of 33-38 mgKOH / g, and a viscosity of 6000-8000 mPa·s, which is purchased from Anhui Yongchang New Materials Technology Co., Ltd.

[0057] Comparative Example 4

[0058] Compared with Example 1, the difference of Comparative Example 4 is that the polyester resin B is only a polyester resin with a model number of YC8502, an acid value of 48-53 mgKOH / g, and a viscosity of 4000-5500 mPa·s, which is purchased from Anhui Yongchang New Materials Technology Co., Ltd.

[0059] Experimental Example 1

[0060] The wear-resistant powder coatings prepared in Examples 1 to 4 and Comparative Examples 1 to 4 were tested for hardness according to the test method specified in GB / T 6739-2022 "Determination of film hardness of paints and varnishes by pencil method". The wear-resistant powder coatings prepared in Examples 1 to 4 and Comparative Examples 1 to 4 were applied to 0.8 mm thick rust-removed and oil-removed cold-rolled steel plates by electrostatic spraying. The curing temperature was 230 ° C, the curing time was 20 min, the coating thickness was 70 μm, and the coating was tested.

[0061] The test results are shown in Table 1:

[0062] Table 1 Performance test results of wear-resistant powder coatings prepared in Examples 1 to 4 and Comparative Examples 1 to 4

[0063]

[0064] It can be seen from Table 1 that when the polyester resin B consists of the first polyester resin and the second polyester, the wear resistance of the powder coating can be improved.

[0065] Experimental Example 2

[0066] 1. Impact resistance: The wear-resistant powder coating prepared in Example 1 was tested for impact resistance according to the test method specified in GB / T 1732-2020 “Determination of impact resistance of paint films”. The wear-resistant powder coating prepared in Example 1 was applied to a 0.8 mm thick rust-removed and degreased cold-rolled steel plate by electrostatic spraying. The curing temperature was 230°C, the curing time was 20 min, and the coating thickness was 70 μm. The coating was tested.

[0067] 2. Adhesion (cross-cut method) level: Test the adhesion of the sample according to the test method specified in ISO 2409, with a cutting interval of 2mm.

[0068] 3. Scratch resistance: Test the scratch resistance of the sample according to the test method specified in DIN 68861-4.

[0069] 4. Lightfastness: Test the lightfastness of the sample according to the test method specified in prEN 15187.

[0070] The test results are shown in Table 2:

[0071] Table 2 Performance test results of the wear-resistant powder coating prepared in Example 1

[0072]

[0073] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A wear-resistant powder coating, characterized in that: The invention comprises the following raw materials in parts by weight: 15-25 parts of polyester resin A, 10-15 parts of polyester resin A curing agent, 20-30 parts of polyester resin B, 1-5 parts of polyester resin B curing agent, 1-2 parts of hardening wax powder, 50-60 parts of ceramic powder, and 1-2 parts of leveling agent; the acid value of the polyester resin A is lower than that of the polyester resin B; the polyester resin B is composed of a first polyester resin and a second polyester resin; the first polyester resin and the second polyester resin have the same acid value, and the viscosity of the first polyester resin is lower than that of the second polyester resin; The polyester resin A has a hydroxyl value of 75-85 mgKOH / g, a viscosity of 3000-6000 mPa·s, and an acid value of ≤5 mgKOH / g; The acid value of the first polyester resin is 48-55 mgKOH / g, and the viscosity is 3500-4500 mPa·s; the acid value of the second polyester resin is 48-55 mgKOH / g, and the viscosity is 6000-9000 mPa·s; The mass ratio of the first polyester resin to the second polyester resin is 1-5:

2.

2. A wear-resistant powder coating according to claim 1, characterized in that: The polyester resin A curing agent includes one or more of toluene diisocyanate, diphenylmethane diisocyanate, and hexamethylene diisocyanate.

3. A wear-resistant powder coating according to claim 1, characterized in that: The polyester resin B curing agent is curing agent TGIC.

4. A wear-resistant powder coating according to claim 1, characterized in that: The leveling agent includes one or more of BYK-333, BYK-377, and BYK-381.

5. A method for preparing a wear-resistant powder coating, for preparing a wear-resistant powder coating according to any one of claims 1 to 4, characterized in that: The following steps are involved: S1, mixing the raw materials to obtain a mixed powder; S2. The mixed powder is extruded and ground to obtain a wear-resistant powder coating.

6. The method for preparing a wear-resistant powder coating according to claim 5, characterized in that: In step S2, the temperature of the first extrusion zone is 90°C, and the temperature of the second extrusion zone is 120°C.

7. The method for preparing a wear-resistant powder coating according to claim 5, characterized in that: The wear-resistant powder coating has a D10 of 13 μm, a D50 of 40 μm, and a D90 of 85 μm.

Images