Preparation method of scratch-resistant and wear-resistant coating for hardware products

Abstract

The invention discloses a preparation method of a scratch-resistant and wear-resistant coating for hardware products, and relates to the technical field of metal coatings. The method comprises the five steps of preparing a wear-resistant coating formula, preparing paint, pretreating the surface of the hardware product, coating and curing. The formula of the coating comprises high-wear-resistance polyurethane resin, an isocyanate hardener, an elastomer flexibilizer, an organic silicon lubricant and a scratch-resistant auxiliary agent according to a specific ratio. Through the synergistic effect of the two-component isocyanate system, the polyether type or polyester type polyurethane resin and the auxiliaries, the prepared coating has excellent scratch resistance and good toughness and adhesive force, and is suitable for the complex use environment of hardware products. The coating prepared by the method is controllable in thickness, simple in process and suitable for large-scale industrial production.

Description

Technical Field

[0001] This invention relates to the field of metal coating technology, and in particular to a method for preparing a scratch-resistant coating for hardware products. Background Technology

[0002] Hardware products come in a wide variety, and in the automotive industry, car hooks are widely used components for in-vehicle storage and suspension systems. Because they must withstand friction, impacts, and external forces over long periods, high demands are placed on the scratch resistance and durability of their surface coatings. Traditional coating materials, such as ordinary epoxy resin and acrylic resin, while offering some protection, often suffer from insufficient wear resistance and are prone to scratches or peeling, failing to meet the high requirements of automotive interior parts applications.

[0003] Chinese Patent: Preparation and Application of a Highly Elongated Waterborne Polyurethane Composite Coating (Patent Publication No.: CN117005213A) A lower layer of waterborne polyurethane slurry is coated onto the surface of a target object, dried and cured to form a lower layer of waterborne polyurethane coating. Then, a middle layer of waterborne polyurethane slurry is coated onto the lower layer, dried and cured to form a middle layer of waterborne polyurethane coating. Next, an upper layer of waterborne polyurethane slurry is coated onto the middle layer, dried and cured to form an upper layer of waterborne polyurethane coating. Finally, after standing, a highly ductile waterborne polyurethane composite coating is obtained.

[0004] Currently, most scratch-resistant coatings on the market use polyurethane coatings. However, general polyurethane coatings have a certain balance between hardness and toughness; increasing the coating hardness often leads to increased brittleness, affecting the overall performance of the coating. Furthermore, the adhesion between the coating and the substrate directly affects its service life and reliability. To solve these problems, there is an urgent need for a method for preparing scratch-resistant coatings that can balance hardness, toughness, and adhesion, suitable for the industrial production of hardware products.

[0005] This invention addresses the shortcomings of existing technologies by proposing a method for preparing a scratch-resistant coating for hardware products. By optimizing the coating formulation, improving the coating process and curing process, a coating with excellent scratch resistance, wear resistance and adhesion is prepared to meet the usage requirements of hardware products. Summary of the Invention

[0006] This invention addresses the technical problems mentioned in the background section by providing a method for preparing a scratch-resistant coating for hardware products. The coating obtained by this method exhibits excellent scratch resistance, wear resistance, and adhesion, making it suitable for the industrial production of hardware products.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A method for preparing a scratch-resistant coating for hardware products includes the following steps: A: Prepare the coating formula: 80-120 parts of high wear-resistant polyurethane resin, 15-25 parts of isocyanate hardener, 8-15 parts of elastomer toughening agent, 3-7 parts of silicone lubricant, and 1-3 parts of anti-scratch additive. B: To prepare the coating, mix all components evenly and adjust the viscosity to between 3000-5000 mPa·s, suitable for the coating process; C: Pre-treat the surface of the hardware products by grinding the surface of the hardware products until the surface roughness reaches Ra 0.8-1.2μm, then cleaning with isopropanol and drying at 50-60℃ for 30-45 minutes to improve surface adhesion; D: Coating, which involves applying the prepared coating evenly to the surface of the product using spraying, dipping, or brushing methods; E: Curing, curing at a temperature range of 100℃ to 150℃ for 30-60 minutes to allow the coating to cross-link and form scratch-resistant properties.

[0008] Furthermore, the polyurethane resin is selected from polyether-type or polyester-type polyurethane resins.

[0009] Furthermore, the polyether-type polyurethane resin is selected from one or a combination of several of Desmopan 385S, Desmopan 386S, Elastollan 1185A, Elastollan 1190A, and WANNATE 7910.

[0010] Furthermore, the polyester-type polyurethane resin is selected from one or more combinations of polybutylene adipate (PBA)-based polyurethane, polyhexylene adipate (PHA)-based polyurethane, poly(1,4-cyclohexanediol adipate) (PCHDA)-based polyurethane, polybutylene terephthalate (PBT)-based polyurethane, and polyethylene terephthalate (PET)-based polyurethane.

[0011] Furthermore, the isocyanate curing agent is a two-component isocyanate system.

[0012] Furthermore, the two-component isocyanate system is selected from one or more combinations of Desmodur N3300A, Desmodur N3200A, Desmodur N3400A, Bayhydur 3100, Desmodur L 75, and Desmodur L 67.

[0013] Furthermore, the elastomer toughening agent is one or a combination of polybutadiene rubber and ethylene-propylene-diene (EPDM) rubber.

[0014] Furthermore, the organosilicon lubricant is one or a combination of polydimethylsiloxane, polytrifluoropropylmethylsiloxane, and polymethylvinylsiloxane.

[0015] Furthermore, the method for preparing the anti-scratch additive is as follows: T1: Prepare raw materials: Weigh the following raw materials according to the following weight proportions: 4-8 parts allyl (cyclopentadienyl) nickel (CAS: 12107-46-9), 16-32 parts disodium mercaptododecyl salt, 1000-1600 parts toluene and 3-6 parts ethylenediamine; T2: Preliminary mixing and heating: Add the weighed allyl (cyclopentadienyl) nickel, disodium mercaptododecyl borane (CAS: 12294-22-3), ethylenediamine and toluene to the reaction vessel, heat the reaction vessel to 70-80℃ and maintain this temperature, and stir the reaction for 30-70 minutes. T3: Add oleamide and continue the reaction: At a temperature of 70-80℃, add 100-140 parts of oleamide to the reaction system and continue stirring for 50-100 minutes to ensure that the oleamide reacts fully with the other components; T4: Vacuum distillation: After the reaction is complete, the toluene solvent is removed by vacuum distillation to obtain the final anti-scratch additive product.

[0016] Furthermore, the coating process involves two spraying processes, with each spraying producing a coating thickness of 30-50 micrometers, resulting in a final coating thickness of 80-100 micrometers.

[0017] The reaction mechanism of anti-scratch additives is as follows: 1. Reaction Mechanism The reaction of allyl (cyclopentadienyl) nickel with disodium mercaptododecanoate: The carbon-carbon double bond in the allyl group acts as an electrophilic center, attacked by the thiol group in disodium mercaptododecanoate, resulting in a thiol-olefin addition reaction. This reaction forms a cyclic intermediate containing a sulfur atom. The reaction of oleamide with disodium mercaptododecanoate: The double bond in oleamide undergoes a thiol-olefin addition reaction with the thiol group in disodium mercaptododecanoate. This reaction generates a compound containing an amide group and boron atoms, further enhancing the scratch resistance of the coating.

[0018] 2. Technical Effects Improved scratch resistance: The anti-scratch additives obtained through the above reactions can form a robust protective layer in polyurethane / elastomer coatings. These anti-scratch additive molecules contain multiple functional groups, such as borane and amide groups, which can form strong interactions with other molecules in the coating material, thereby enhancing the overall performance of the coating. The introduction of cyclopentadienyl nickel increases the rigidity of the molecules, further improving scratch resistance. The introduction of the cyclic structure makes the molecules more stable and less susceptible to damage from external forces.

[0019] In summary, anti-scratch agents with excellent scratch resistance can be introduced into polyurethane / elastomer coatings through the thiol-olefin addition reaction between allyl (cyclopentadienyl)nickel and disodium mercaptododecanoate, and the thiol-olefin addition reaction between oleamide and disodium mercaptododecanoate. These anti-scratch agents significantly improve the scratch resistance of the coating by forming strong interactions with other molecules in the coating material.

[0020] The coating for hardware products prepared by the preparation method provided by this invention has the following significant technical effects: 1. The coating has excellent scratch resistance and can effectively resist scratches and wear during daily use; 2. The coating has strong adhesion, bonds firmly to the substrate, and is not easily peeled off; 3. The coating has good toughness and impact resistance, making it suitable for the complex usage environment of hardware products; 4. The production process is simple and suitable for large-scale industrial production. Detailed Implementation

[0021] The present invention will be further described below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims. Example 1

[0022] A method for preparing a scratch-resistant coating for hardware products includes the following steps: A: Prepare the coating formula: 80g of high wear-resistant polyurethane resin, 15g of isocyanate hardener, 8g of elastomer toughening agent, 3g of silicone lubricant, and 1g of anti-scratch additive. B: Prepare the coating by mixing all components evenly and adjusting the viscosity to 3000 mPa·s, which is suitable for the coating process; C: Pre-treat the surface of the hardware products by grinding the surface of the hardware products until the surface roughness reaches Ra 0.8 μm, then cleaning with isopropanol and drying at 50°C for 30 minutes to improve surface adhesion. D: Coating, using a spraying method to evenly coat the prepared coating onto the surface of the product; E: Curing, curing at 100℃ for 60 minutes to allow the coating to cross-link and form scratch-resistant properties.

[0023] The polyurethane resin is selected from Desmopan 385S.

[0024] The isocyanate hardener is a two-component isocyanate system.

[0025] The two-component isocyanate system is selected from Desmodur N3300A.

[0026] The elastomer toughening agent is polybutadiene rubber.

[0027] The organosilicon lubricant is polydimethylsiloxane. The method for preparing the anti-scratch additive is as follows: T1: Prepare raw materials: 4g allyl (cyclopentadienyl) nickel (CAS: 12107-46-9), 16g disodium mercaptododecyl salt, 1000g toluene and 3g ethylenediamine; T2: Preliminary mixing and heating: Add the weighed allyl (cyclopentadienyl) nickel, disodium mercaptododecyl borane (CAS: 12294-22-3), ethylenediamine and toluene to the reaction vessel, heat the reaction vessel to 70°C and maintain this temperature, and stir the reaction for 30 minutes; T3: Add oleamide and continue the reaction: Add 100g of oleamide to the reaction system at 70℃ and continue stirring for 50 minutes to ensure that the oleamide reacts fully with the other components; T4: Vacuum distillation: After the reaction is complete, the toluene solvent is removed by vacuum distillation to obtain the final anti-scratch additive product.

[0028] The coating process involves two sprayings, with each spraying producing a coating thickness of 45 micrometers, resulting in a final coating thickness of 90 micrometers. Example 2

[0029] A method for preparing a scratch-resistant coating for hardware products includes the following steps: A: Prepare the coating formula: 100g of high wear-resistant polyurethane resin, 20g of isocyanate hardener, 10g of elastomer toughening agent, 5g of silicone lubricant, and 2g of anti-scratch additive. B: Prepare the coating by mixing all components evenly and adjusting the viscosity to between 4000 mPa·s, which is suitable for the coating process; C: Pre-treat the surface of the hardware products by grinding the surface of the hardware products until the surface roughness reaches Ra1.0μm, then cleaning with isopropanol and drying at 55℃ for 35 minutes to improve surface adhesion. D: Coating, using a spraying method to evenly coat the prepared coating onto the surface of the product; E: Curing, curing at 120℃ for 50 minutes to allow the coating to cross-link and form scratch-resistant properties.

[0030] The polyurethane resin is selected from Desmopan 386S.

[0031] The isocyanate hardener is a two-component isocyanate system.

[0032] The two-component isocyanate system is selected from Desmodur N3200A.

[0033] The elastomer toughening agent is ethylene-propylene-diene (EPDM) rubber.

[0034] The organosilicon lubricant is polytrifluoropropylmethylsiloxane.

[0035] The method for preparing the anti-scratch additive is as follows: T1: Prepare raw materials: 6g allyl (cyclopentadienyl) nickel (CAS: 12107-46-9), 24g disodium mercaptododecyl salt, 1200g toluene and 4g ethylenediamine; T2: Preliminary mixing and heating: Add the weighed allyl (cyclopentadienyl) nickel, disodium mercaptododecyl borane (CAS: 12294-22-3), ethylenediamine and toluene to the reaction vessel, heat the reaction vessel to 75°C and maintain this temperature, and stir the reaction for 40 minutes. T3: Add oleamide and continue the reaction: Add 115g of oleamide to the reaction system at 75℃ and continue stirring for 75 minutes to ensure that the oleamide reacts fully with the other components; T4: Vacuum distillation: After the reaction is complete, the toluene solvent is removed by vacuum distillation to obtain the final anti-scratch additive product.

[0036] The coating process involves two sprayings, with each spraying producing a coating thickness of 45 micrometers, resulting in a final coating thickness of 90 micrometers. Example 3

[0037] A method for preparing a scratch-resistant coating for hardware products includes the following steps: A: Prepare the coating formula: 100g of high wear-resistant polyurethane resin, 20g of isocyanate hardener, 13g of elastomer toughening agent, 5g of silicone lubricant, and 2g of anti-scratch additive. B: Prepare the coating by mixing all components evenly and adjusting the viscosity to between 4000 mPa·s, which is suitable for the coating process; C: Pre-treat the surface of the hardware products by grinding the surface roughness to Ra1.0μm, then cleaning with isopropanol and drying at 55℃ for 40 minutes to improve surface adhesion. D: Coating, using a spraying method to evenly coat the prepared coating onto the surface of the product; E: Curing, curing at 140℃ for 40 minutes to allow the coating to cross-link and form scratch-resistant properties.

[0038] The polyurethane resin is selected from polybutylene adipate (PBA) based polyurethane.

[0039] The isocyanate hardener is a two-component isocyanate system.

[0040] The two-component isocyanate system is selected from Desmodur N3400A.

[0041] The elastomer toughening agent is polybutadiene rubber.

[0042] The organosilicon lubricant is polydimethylsiloxane.

[0043] The method for preparing the anti-scratch additive is as follows: T1: Prepare raw materials: 6g allyl (cyclopentadienyl) nickel (CAS: 12107-46-9), 28g disodium mercaptododecyl borane, 1450g toluene and 5g ethylenediamine; T2: Preliminary mixing and heating: Add the weighed allyl (cyclopentadienyl) nickel, disodium mercaptododecyl borane (CAS: 12294-22-3), ethylenediamine and toluene to the reaction vessel, heat the reaction vessel to 85°C and maintain this temperature, and stir the reaction for 50 minutes; T3: Add oleamide and continue the reaction: Add 130g of oleamide to the reaction system at 75℃ and continue stirring for 75 minutes to ensure that the oleamide reacts fully with the other components; T4: Vacuum distillation: After the reaction is complete, the toluene solvent is removed by vacuum distillation to obtain the final anti-scratch additive product.

[0044] The coating process involves two sprayings, with each spraying producing a coating thickness of 45 micrometers, resulting in a final coating thickness of 90 micrometers. Example 4

[0045] A method for preparing a scratch-resistant coating for hardware products includes the following steps: A: Prepare the coating formula: 120g of high wear-resistant polyurethane resin, 25g of isocyanate hardener, 15g of elastomer toughening agent, 7g of silicone lubricant, and 3g of anti-scratch additive. B: Prepare the coating by mixing all components evenly and adjusting the viscosity to between 5000 mPa·s, which is suitable for the coating process; C: Pre-treat the surface of the hardware products by grinding the surface of the hardware products until the surface roughness reaches Ra 1.2 μm, then cleaning with isopropanol and drying at 60°C for 45 minutes to improve surface adhesion; D: Coating, using a spraying method to evenly coat the prepared coating onto the surface of the product; E: Curing, curing at 150℃ for 30 minutes to allow the coating to cross-link and form scratch-resistant properties.

[0046] The polyurethane resin is selected from poly(1,4-cyclohexanediol adipate) (PCHDA) based polyurethane.

[0047] The isocyanate hardener is a two-component isocyanate system.

[0048] The two-component isocyanate system is selected from Bayhydur 3100.

[0049] The elastomer toughening agent is ethylene-propylene-diene (EPDM) rubber.

[0050] The organosilicon lubricant is polymethylvinylsiloxane.

[0051] The method for preparing the anti-scratch additive is as follows: T1: Prepare raw materials: 8g allyl (cyclopentadienyl) nickel (CAS: 12107-46-9), 32g disodium mercaptododecyl salt, 1600g toluene and 6g ethylenediamine; T2: Preliminary mixing and heating: Add the weighed allyl (cyclopentadienyl) nickel, disodium mercaptododecyl borane (CAS: 12294-22-3), ethylenediamine and toluene to the reaction vessel, heat the reaction vessel to 80°C and maintain this temperature, and stir the reaction for 70 minutes; T3: Add oleamide and continue the reaction: At a temperature of 80°C, add 140g of oleamide to the reaction system and continue stirring for 100 minutes to ensure that the oleamide reacts fully with the other components; T4: Vacuum distillation: After the reaction is complete, the toluene solvent is removed by vacuum distillation to obtain the final anti-scratch additive product.

[0052] The coating process involves two sprayings, with each spraying producing a coating thickness of 45 micrometers, resulting in a final coating thickness of 90 micrometers.

[0053] Comparative Example 1 The difference from Example 1 is that no anti-scratch additive is added in step A.

[0054] Comparative Example 2 The difference from Example 1 is that allyl (cyclopentadienyl) nickel is not added during the preparation of the anti-scratch additive.

[0055] Comparative Example 3 The difference from Example 1 is that disodium mercaptododecyl salt is not added during the preparation of the anti-scratch agent.

[0056] Test method for scratch-resistant coatings for hardware products prepared by the above specific implementation method: 1) Scratch resistance test: Pencil hardness test, conforming to ASTM D3363 standard, higher hardness indicates better scratch resistance.

[0057] 2) Adhesion test: Adhesion is tested using the cross-cut adhesion test, which conforms to ASTM D3359 standard and is graded from 5B to 1B, with 5B indicating no peeling.

[0058] 3) Impact resistance test: The impact resistance is tested using the steel ball impact method to check whether the coating peels or cracks under high-intensity impact. The test height is 50cm and the steel ball mass is 1kg.

[0059] Test results: Table 1 Test Results of Examples and Comparative Examples hardness Adhesion Impact resistance Example 1 H 5B No peeling or cracking Example 2 2H 5B No peeling or cracking Example 3 2H 5B No peeling or cracking Example 4 2H 5B No peeling or cracking Comparative Example 1 B 3B slight peeling Comparative Example 2 HB 4B No peeling or breakage Comparative Example 3 HB 4B No peeling or breakage As can be seen from the above specific implementation scheme and test results, the coating prepared by this method has excellent scratch resistance, good toughness and adhesion.

[0060] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a scratch-resistant coating for hardware products, comprising the following steps: A: Prepare the coating formula: 80-120 parts of high wear-resistant polyurethane resin, 15-25 parts of isocyanate hardener, 8-15 parts of elastomer toughening agent, 3-7 parts of silicone lubricant, and 1-3 parts of anti-scratch additive. B: To prepare the coating, mix all components evenly and adjust the viscosity to between 3000-5000 mPa·s, suitable for the coating process; C: Pre-treat the surface of the hardware products. Grind the surface of the hardware products until the surface roughness Ra reaches 0.8-1.2 μm, then clean with isopropanol and dry at 50-60℃ for 30-45 minutes to improve surface adhesion. D: Coating, which involves applying the prepared coating evenly to the surface of the product using spraying, dipping, or brushing methods; E: Curing, curing at a temperature range of 100℃ to 150℃ for 30-60 minutes to allow the coating to cross-link and form scratch-resistant properties; The anti-scratch additive is prepared by reacting allyl (cyclopentadienyl) nickel, disodium mercaptododecyl ether, and oleamide.

2. The method for preparing a scratch-resistant coating for hardware products according to claim 1, characterized in that: The polyurethane resin is selected from polyether-type or polyester-type polyurethane resins.

3. The method for preparing a scratch-resistant coating for hardware products according to claim 2, characterized in that: The polyether-type polyurethane resin is selected from one or a combination of several of Desmopan 385S, Desmopan 386S, Elastollan 1185A, Elastollan 1190A, and WANNATE 7910.

4. The method for preparing a scratch-resistant coating for hardware products according to claim 2, characterized in that: The polyester-type polyurethane resin is selected from one or a combination of polybutylene adipate (PBA)-based polyurethane, polyhexylene adipate (PHA)-based polyurethane, poly(1,4-cyclohexanediol adipate) (PCHDA)-based polyurethane, polybutylene terephthalate (PBT)-based polyurethane, and polyethylene terephthalate (PET)-based polyurethane.

5. The method for preparing a scratch-resistant coating for hardware products according to claim 1, characterized in that: The isocyanate hardener is a two-component isocyanate system.

6. The method for preparing a scratch-resistant coating for hardware products according to claim 5, characterized in that: The two-component isocyanate system is selected from one or more combinations of Desmodur N3300A, Desmodur N3200A, Desmodur N3400A, Bayhydur 3100, Desmodur L 75, and Desmodur L 67.

7. The method for preparing a scratch-resistant coating for hardware products according to claim 1, characterized in that: The elastomer toughening agent is one or a combination of polybutadiene rubber and ethylene-propylene-diene (EPDM) rubber.

8. The method for preparing a scratch-resistant coating for hardware products according to claim 1, characterized in that: The organosilicon lubricant is one or a combination of polydimethylsiloxane, polytrifluoropropylmethylsiloxane, and polymethylvinylsiloxane.

9. The method for preparing a scratch-resistant coating for hardware products according to claim 1, characterized in that: The method for preparing the anti-scratch additive is as follows: T1: Prepare raw materials: Weigh the following raw materials according to the specified weight proportions: 4-8 parts allyl (cyclopentadienyl) nickel, 16-32 parts disodium mercaptododecyl salt, 1000-1600 parts toluene and 3-6 parts ethylenediamine; T2: Preliminary mixing and heating: Add the weighed allyl (cyclopentadienyl) nickel, disodium mercaptododecyl borane, ethylenediamine and toluene to the reaction vessel, heat the reaction vessel to 70-80℃ and maintain this temperature, and stir the reaction for 30-70 minutes. T3: Add oleamide and continue the reaction: At a temperature of 70-80℃, add 100-140 parts of oleamide to the reaction system and continue stirring for 50-100 minutes to ensure that the oleamide reacts fully with the other components; T4: Vacuum distillation: After the reaction is complete, the toluene solvent is removed by vacuum distillation to obtain the final anti-scratch additive product.

10. The method for preparing a scratch-resistant coating for hardware products according to claim 1, characterized in that: The coating process involves two sprayings, with each spraying producing a coating thickness of 30-50 micrometers, resulting in a final coating thickness of 80-100 micrometers.