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] The invention relates to the technical field of metal coatings, in particular to a method for preparing a scratch-resistant coating for hardware products. Background Art

[0002] Hardware encompasses a wide range of products. In the automotive industry, car hooks, as critical in-vehicle storage and suspension components, are subject to extremely demanding operating conditions, constantly enduring friction, collisions, and external forces. Consequently, they place extremely high demands on the scratch resistance and durability of their surface coatings. While traditional coating materials, such as common epoxy and acrylic resins, offer some protection, they suffer from significant wear resistance limitations, easily scratching or peeling during use, making them inadequate for the high-quality demands placed on automotive interior components.

[0003] Chinese patent CN116547332A discloses an epoxy-polysiloxane polymer coating composition suitable for coating surfaces, which provides excellent chemical resistance, corrosion resistance, or weather resistance. The epoxy-polysiloxane polymer coating composition comprises a polysiloxane and a non-aromatic epoxy resin and a curing system, wherein the combined composition reacts to form a cross-linked epoxy-polysiloxane polymer structure. The curing system may comprise at least one blend of a metal or organic catalyst and an alkoxy-functional aminosilane, and may further comprise a polyurethane, such as a silane-terminated polyurethane. The metal catalyst may be coordinated with or in close proximity to the polyurethane, thereby providing excellent hardening results at very low metal concentrations.

[0004] Currently, the most widely used scratch-resistant coatings on the market are polyurethane coatings. However, these coatings often struggle to achieve an ideal balance between hardness and toughness. Increased hardness often comes with increased brittleness, impacting the coating's overall performance. Furthermore, adhesion between the coating and the hardware substrate is a key factor in determining its lifespan and reliability. Given these challenges, the industry urgently needs a scratch-resistant coating preparation technology that balances hardness, toughness, and adhesion to meet the demands of industrialized hardware production.

[0005] To address the limitations of existing technologies, this paper proposes a method for preparing a scratch-resistant coating for hardware products. By optimizing the coating formulation and improving the coating and curing processes, this method successfully produces a coating with excellent scratch and wear resistance and strong adhesion, meeting the stringent requirements of hardware applications. Summary of the Invention

[0006] The present invention addresses the technical problems mentioned in the background art and provides a method for preparing a scratch-resistant coating for hardware products. The preparation method of the present invention produces a coating with excellent scratch resistance, wear resistance, and adhesion, and is suitable for the industrial production of hardware products.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is as follows: A method for preparing a scratch-resistant coating for hardware products comprises 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 agent; B: Prepare the coating, mix all ingredients 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 them to a surface roughness of Ra 0.8-1.2μm, then clean them with isopropyl alcohol and dry them at 50-60℃ for 30-45 minutes to improve surface adhesion; D: Coating: Use spraying, dipping or brushing to evenly apply the prepared coating on the surface of the product; E: Curing: Curing at a temperature range of 100°C to 150°C for 30-60 minutes to crosslink the coating and form scratch resistance.

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

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

[0010] Furthermore, the polyester polyurethane resin is selected from one or a combination of polybutylene adipate (PBA)-based polyurethane, polyhexanediol adipate (PHA)-based polyurethane, poly-1,4-cyclohexanedimethanol adipate (PCHDA)-based polyurethane, polybutylene terephthalate (PBT)-based polyurethane, and polyethylene terephthalate (PET)-based polyurethane.

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

[0012] Furthermore, the two-component isocyanate system is selected from one or a combination 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 organic silicone lubricant is one or a combination of polydimethylsiloxane, polytrifluoropropylmethylsiloxane, and polymethylvinylsiloxane.

[0015] Furthermore, the preparation method of the anti-scratch agent is: T1: Prepare the raw materials: Weigh the following raw materials by weight: 4-8 parts of allyl(cyclopentadienyl)nickel (CAS: 12107-46-9), 16-32 parts of disodium mercaptododecaborane, 1000-1600 parts of toluene, and 3-6 parts of ethylenediamine; T2: Preliminary mixing and heating: Add weighed allyl(cyclopentadienyl)nickel, disodium mercaptododecaborane (CAS: 12294-22-3), ethylenediamine, and toluene to a reaction kettle. Heat the kettle to 70-80°C and maintain this temperature. Stir and react for 30-70 minutes. T3: Add oleamide and continue reaction: Add 100-140 parts of oleamide to the reaction system at a temperature of 70-80°C and continue stirring for 50-100 minutes to ensure that oleamide fully reacts with other components; T4: vacuum distillation: After the reaction is completed, the toluene solvent is removed by vacuum distillation to obtain the final anti-scratch additive product.

[0016] Furthermore, the coating process is two spraying steps, the coating thickness after each spraying step is 30-50 microns, and the final coating thickness is 80-100 microns.

[0017] The reaction mechanism of anti-scratch additive is: 1. Reaction Mechanism Allyl(cyclopentadienyl)nickel reacts with disodium mercaptododecaborane to form a thiol-olefin addition reaction. This reaction forms a cyclic intermediate containing a sulfur atom. Oleamide reacts with disodium mercaptododecaborane: The double bond in oleamide reacts with the thiol group in disodium mercaptododecaborane to form a thiol-olefin addition reaction. This reaction produces a compound containing an amide group and a boron atom, further enhancing the coating's scratch resistance.

[0018] 2. Technical Effect Improving Scratch Resistance: The anti-scratch additives produced through the aforementioned reaction can form a strong protective layer within the polyurethane / elastomer coating. These anti-scratch additive molecules contain multiple functional groups, such as borane and amide groups, which 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 molecular rigidity, further enhancing scratch resistance. The ring structure makes the molecule more stable and less susceptible to damage by external forces.

[0019] In summary, the thiol-olefin addition reaction between allyl(cyclopentadienyl)nickel and disodium mercaptododecaborane, and the thiol-olefin addition reaction between oleamide and disodium mercaptododecaborane, can be used to introduce anti-scratch agents with excellent scratch resistance into polyurethane / elastomer coatings. These anti-scratch agents significantly enhance the coating's scratch resistance by forming strong interactions with other molecules in the coating material.

[0020] The coating for hardware products prepared by the preparation method provided by the present 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 and is firmly bonded to the product substrate, making it difficult to peel off; 3. The coating has good toughness and impact resistance, and is suitable for the complex use environment of hardware products; 4. The production process is simple and suitable for large-scale industrial production. DETAILED DESCRIPTION

[0021] Below in conjunction with specific embodiment, further set forth the present invention.Should be understood that these embodiments are only used to illustrate the present invention and are not used in limiting the scope of the present invention.In addition, should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall equally within the scope limited by the appended claims of the application.

[0022] Example 1 A method for preparing a scratch-resistant coating for hardware products comprises the following steps: A: Prepare the coating formula: 80g high-wear-resistant polyurethane resin, 15g isocyanate hardener, 8g elastomer toughening agent, 3g silicone lubricant, and 1g anti-scratch agent; B: Prepare the coating, mix all ingredients evenly, and adjust the viscosity to 3000 mPa·s, suitable for the coating process; C: Pre-treat the surface of the hardware products by grinding them to a surface roughness of Ra 0.8 μm, then clean them with isopropyl alcohol and dry them at 50°C for 30 minutes to improve surface adhesion; D: Coating, using spraying method to evenly apply the prepared coating on the surface of the product; E: Curing: Curing at 100°C for 60 minutes to crosslink the coating and form scratch resistance.

[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 preparation method of the anti-scratch auxiliary agent is: T1: Prepare the following raw materials: 4 g allyl(cyclopentadienyl)nickel (CAS: 12107-46-9), 16 g disodium mercaptododecaborane, 1000 g toluene, and 3 g ethylenediamine; T2: Preliminary mixing and heating: Add weighed allyl(cyclopentadienyl)nickel, disodium mercaptododecaborane (CAS: 12294-22-3), ethylenediamine, and toluene to a reactor. Heat the reactor to 70°C and maintain this temperature with stirring for 30 minutes. T3: Add oleamide and continue reaction: Add 100 g of oleamide to the reaction system at 70°C and continue stirring for 50 minutes to ensure that oleamide and other components react fully. T4: vacuum distillation: After the reaction is completed, the toluene solvent is removed by vacuum distillation to obtain the final anti-scratch additive product.

[0028] The coating process is two spraying processes, the coating thickness after each spraying is 45 microns, and the final coating thickness is 90 microns.

[0029] Example 2 A method for preparing a scratch-resistant coating for hardware products comprises the following steps: A: Prepare the coating formula: 100g high-wear-resistant polyurethane resin, 20g isocyanate hardener, 10g elastomer toughening agent, 5g silicone lubricant, and 2g anti-scratch agent; B: Prepare the coating, mix all ingredients evenly, and adjust the viscosity to between 4000 mPa·s, suitable for the coating process; C: Pre-treat the surface of the hardware products by grinding them to a surface roughness of Ra 1.0 μm, then clean them with isopropyl alcohol and dry them at 55°C for 35 minutes to improve surface adhesion; D: Coating, using spraying method to evenly apply the prepared coating on the surface of the product; E: Curing: Curing at 120°C for 50 minutes to crosslink the coating and form scratch resistance.

[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 organic silicon lubricant is polytrifluoropropylmethylsiloxane.

[0035] The preparation method of the anti-scratch auxiliary agent is: T1: Prepare the following raw materials: 6 g allyl(cyclopentadienyl)nickel (CAS: 12107-46-9), 24 g disodium mercaptododecaborane, 1200 g toluene, and 4 g ethylenediamine; T2: Preliminary mixing and heating: Add weighed allyl(cyclopentadienyl)nickel, disodium mercaptododecaborane (CAS: 12294-22-3), ethylenediamine, and toluene to a reactor. Heat the reactor to 75°C and maintain this temperature with stirring for 40 minutes. T3: Add oleamide and continue reaction: At 75°C, add 115 g of oleamide to the reaction system and continue stirring for 75 minutes to ensure that oleamide reacts fully with other components; T4: vacuum distillation: After the reaction is completed, the toluene solvent is removed by vacuum distillation to obtain the final anti-scratch additive product.

[0036] The coating process is two spraying processes, the coating thickness after each spraying is 45 microns, and the final coating thickness is 90 microns.

[0037] Example 3 A method for preparing a scratch-resistant coating for hardware products comprises the following steps: A: Prepare the coating formula: 100g high-wear-resistant polyurethane resin, 20g isocyanate hardener, 13g elastomer toughening agent, 5g silicone lubricant, and 2g anti-scratch agent; B: Prepare the coating, mix all ingredients evenly, and adjust the viscosity to between 4000 mPa·s, suitable for the coating process; C: Pre-treat the surface of the hardware products by grinding them to a surface roughness of Ra 1.0 μm, then clean them with isopropyl alcohol and dry them at 55°C for 40 minutes to improve surface adhesion; D: Coating, using spraying method to evenly apply the prepared coating on the surface of the product; E: Curing: Curing at 140°C for 40 minutes to crosslink the coating and form scratch resistance.

[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 organic silicone lubricant is polydimethylsiloxane.

[0043] The preparation method of the anti-scratch auxiliary agent is: T1: Prepare the following raw materials: 6 g allyl(cyclopentadienyl)nickel (CAS: 12107-46-9), 28 g disodium mercaptododecaborane, 1450 g toluene, and 5 g ethylenediamine; T2: Preliminary mixing and heating: Add weighed allyl(cyclopentadienyl)nickel, disodium mercaptododecaborane (CAS: 12294-22-3), ethylenediamine, and toluene to a reactor. Heat the reactor to 85°C and maintain this temperature with stirring for 50 minutes. T3: Add oleamide and continue reaction: At 75°C, add 130 g of oleamide to the reaction system and continue stirring for 75 minutes to ensure that oleamide reacts fully with other components; T4: vacuum distillation: After the reaction is completed, the toluene solvent is removed by vacuum distillation to obtain the final anti-scratch additive product.

[0044] The coating process is two spraying processes, the coating thickness after each spraying is 45 microns, and the final coating thickness is 90 microns.

[0045] Example 4 A method for preparing a scratch-resistant coating for hardware products comprises the following steps: A: Prepare the coating formula: 120g high-wear-resistant polyurethane resin, 25g isocyanate hardener, 15g elastomer toughening agent, 7g silicone lubricant, and 3g anti-scratch agent; B: Prepare the coating, mix all ingredients evenly, and adjust the viscosity to between 5000 mPa·s, suitable for the coating process; C: Pre-treat the surface of the hardware products by grinding them to a surface roughness of Ra 1.2 μm, then clean them with isopropyl alcohol and dry them at 60°C for 45 minutes to improve surface adhesion; D: Coating, using spraying method to evenly apply the prepared coating on the surface of the product; E: Curing: Curing at 150°C for 30 minutes to crosslink the coating and form scratch resistance.

[0046] The polyurethane resin is selected from poly(1,4-cyclohexanedimethanol 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 organic silicon lubricant is polymethylvinylsiloxane.

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

[0052] The coating process is two spraying processes, the coating thickness after each spraying is 45 microns, and the final coating thickness is 90 microns.

[0053] Comparative Example 1 The difference from Example 1 is that no anti-scratch agent 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 agent.

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

[0056] Testing method for the scratch-resistant coating for hardware products prepared by the above specific implementation method: 1) Scratch resistance test: Pencil hardness method is used in accordance with ASTM D3363. Higher hardness indicates better scratch resistance.

[0057] 2) Adhesion test: Adhesion is tested using the 100-grid method in accordance with ASTM D3359, with a grading range of 5B to 1B, where 5B indicates no peeling.

[0058] 3) Impact resistance test: The steel ball impact method is used to test the impact resistance of the coating to see if it 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 breaking Comparative Example 3 HB 4B No peeling or breaking It can be seen from the above specific implementation plans and test results that the coating prepared by this method has excellent scratch resistance, good toughness and adhesion.

[0060] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as 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 agent; B: Prepare the coating, mix all ingredients 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 them to a surface roughness of Ra 0.8-1.2 μm, then clean them with isopropyl alcohol and dry them at 50-60°C for 30-45 minutes to improve surface adhesion; D: Coating: Use spraying, dipping or brushing to evenly apply the prepared coating on the surface of the product; E: Curing, curing at a temperature range of 100°C to 150°C for 30-60 minutes to crosslink the coating and form scratch resistance; The anti-scratch auxiliary agent is prepared by reacting allyl (cyclopentadienyl) nickel, disodium mercaptododecaborane 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 or polyester polyurethane resin.

3. The method for preparing a scratch-resistant coating for hardware products according to claim 2, characterized in that: The polyether polyurethane resin is selected from one or a combination 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 polyurethane resin is selected from one or a combination of polybutylene adipate (PBA)-based polyurethane, polyhexanediol adipate (PHA)-based polyurethane, poly-1,4-cyclohexanedimethanol 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 a combination 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 organic silicon 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 preparation method of the anti-scratch auxiliary agent is: T1: Prepare the raw materials: Weigh the following raw materials in parts by weight: 4-8 parts of allyl(cyclopentadienyl)nickel, 16-32 parts of disodium mercaptododecaborane, 1000-1600 parts of toluene and 3-6 parts of ethylenediamine; T2: Preliminary mixing and heating: Add weighed allyl(cyclopentadienyl)nickel, disodium mercaptododecaborane, ethylenediamine, and toluene into a reaction kettle, heat the kettle to 70-80°C and maintain this temperature, stirring and reacting for 30-70 minutes; T3: Add oleamide and continue reaction: Add 100-140 parts of oleamide to the reaction system at a temperature of 70-80°C and continue stirring for 50-100 minutes to ensure that oleamide fully reacts with other components; T4: vacuum distillation: After the reaction is completed, 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 is two spraying steps, the coating thickness after each spraying step is 30-50 microns, and the final coating thickness is 80-100 microns.