Micro-nano structure heat-aging resistant PP-based coating and preparation method thereof
By using micro-nano structured coatings made from modified chlorinated polypropylene resin and Al2O3-GO composite materials, the problems of insufficient adhesion and heat aging resistance of PP substrates were solved, and PP-based coatings with high adhesion and durability were achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- GUANGZHOU ZHEMING INK COATING CO LTD
- Filing Date
- 2026-04-23
- Publication Date
- 2026-06-09
AI Technical Summary
PP substrates have poor adhesion to coatings and insufficient heat aging resistance. Existing technologies such as CPP resin are easily degraded under heat and light, leading to coating aging.
A micro-nano structure coating is formed by using modified chlorinated polypropylene resin as the matrix, combined with silicone-modified acrylic resin and Al2O3-GO composite material. The heat resistance is improved by organosilicon segments, and the Al2O3-GO composite material forms a multi-level reinforcing structure on the coating film surface. Alumina and graphene oxide work together to play a role in heat resistance and heat dissipation.
It improves the adhesion and heat aging resistance of PP substrate, forming a micro-nano structure coating with high hardness and good wear resistance, which can effectively inhibit crack propagation and prevent external heat from entering, thus improving the durability of the coating.
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Abstract
Description
Technical Field
[0001] This application relates to the technical field of coatings, and in particular to a micro / nano structure heat-resistant aging PP-based coating and its preparation method. Background Technology
[0002] Polypropylene (PP), a non-polar crystalline polymer, is widely used in automotive parts, appliance housings, and packaging materials due to its excellent mechanical properties, low density, low cost, and good chemical stability. However, PP's low surface energy, high crystallinity, and lack of active functional groups result in extremely poor adhesion to most coatings, which is the primary technical bottleneck for surface decoration and protection of PP products.
[0003] To overcome this challenge, the industry generally adopts two main strategies: one is to modify the surface of the PP substrate by flame treatment, corona treatment, or the use of adhesion-promoting primers; the other is to directly use resins with inherent affinity for PP as the main film-forming agent in the coating formulation. Among them, chlorinated polypropylene and its modified products, due to their similar molecular structure to PP, can achieve physical anchoring through the penetration and entanglement of molecular chains, and have become the mainstream and key resin system for solving the adhesion of PP coatings.
[0004] However, although CPP resin has largely solved the adhesion problem, its CPP molecular chain contains unstable C-Cl bonds, which are prone to dehydrochlorination reaction under the action of heat and light, leading to resin degradation, yellowing, and the release of acidic substances, thereby accelerating the aging of the substrate and coating as a whole. Summary of the Invention
[0005] To improve the heat aging resistance of PP-based coatings, this application provides a micro / nano structure heat-resistant PP-based coating and its preparation method.
[0006] In the first aspect, this application provides a micro / nano structured heat-resistant aging-resistant PP-based coating, employing the following technical solution: A micro / nano-structured heat-resistant aging PP-based coating comprises the following raw materials in parts by weight: 50-60 parts modified chlorinated polypropylene resin, 14-24 parts silicone-modified acrylic resin, 4-8 parts Al2O3-GO composite material, 3-7 parts nano-alumina, 10-15 parts color paste, 0.8-1.2 parts fumed silica, 0.2-0.6 parts leveling agent, 0.1-0.3 parts wetting agent, 1-1.5 parts adhesion promoter, 0.3-0.6 parts light stabilizer, and 75-85 parts solvent; The particle size of the Al2O3-GO composite material is in the micrometer range; the solvent is a mixture of xylene and small molecule alcohol.
[0007] By adopting the above technical solution, this application ensures adhesion to PP substrate by using modified chlorinated polypropylene resin as the main matrix resin, while the introduction of silicone modified acrylic resin (14-24 parts) improves the heat resistance and weather resistance of the system through organosilicon segments. The two work together to solve the fundamental contradiction that it is difficult to balance the adhesion and durability of PP coatings.
[0008] Building upon this foundation, the innovative introduction of Al2O3-GO composite material as the core functional material further enhances its heat aging resistance. This composite material, working in conjunction with nano-sized alumina and other inorganic fillers in the formulation, forms a multi-level "micron-nano" reinforcing structure on the paint film surface. This effectively improves coating hardness, wear resistance, and inhibits crack propagation. Furthermore, alumina and graphene oxide possess extremely high heat resistance and thermal conductivity; their micro-nano structure acts as a barrier layer on the paint film surface, preventing external heat from penetrating the film and also providing heat dissipation. Structurally, the Al2O3-GO composite material improves the dispersion of graphene oxide and precisely integrates it into the paint film surface, enhancing both heat resistance and heat dissipation. The synergistic effect of the alumina and graphene oxide composite is achieved through mutual reinforcement.
[0009] Preferably, the Al2O3-GO composite material is prepared by modifying micron-sized alumina with an aminosilane coupling agent and then loading it with graphene oxide.
[0010] By adopting the above technical solution, alumina is first modified with an aminosilane coupling agent to make its surface have amino groups, and then it is firmly combined with graphene oxide through chemical reaction, hydrogen bonding, strong electrostatic interaction, etc., which can effectively coat the surface of alumina with graphene oxide and achieve high-efficiency composite.
[0011] Preferably, the average particle size of the micron-sized alumina is 1-10 μm.
[0012] By adopting the above technical solution, the particle size of alumina is limited to the micron level of 1-10 μm. This avoids the problem of nanoparticles being easy to agglomerate and difficult to disperse, reducing the difficulty of the production process. On the other hand, the micron-sized particles, as "carriers", make the loading and dispersion of GO easier, and they can provide effective volume filling and physical reinforcement in the coating. They are not prone to sedimentation and can form a paint film structure with a micro-nano structure on the surface together with other fillers.
[0013] Preferably, the aminosilane coupling agent is one or more of γ-aminopropyltriethoxysilane, N-aminoethyl-γ-aminopropyltrimethoxysilane, N-(β-aminoethyl)-γ-aminopropylmethyldimethoxysilane, 3-aminopropyltrimethoxysilane, and anilinemethyltriethoxysilane.
[0014] Preferably, the average sheet diameter of the graphene oxide is 1-5 μm, and the average sheet diameter of the graphene oxide is ≤ the average particle size of micron-sized alumina.
[0015] By adopting the above technical solution, the GO flake size is limited to 1-5 μm and not larger than the alumina particle size. This "scale matching" principle is crucial: a smaller GO flake size facilitates the formation of a more uniform and dense coating layer on the alumina surface, fully leveraging its flake barrier effect; simultaneously, the GO flake size not exceeding the carrier particle size ensures that GO effectively adheres to the carrier surface rather than randomly accumulating, thereby maximizing its specific surface area and functional utilization. These limitations collectively guarantee that the Al2O3-GO composite material, as a "functional unit," can be stably and uniformly dispersed in the coating and efficiently perform its core functions of heat resistance and barrier properties.
[0016] Preferably, the mass ratio of xylene to small molecule alcohol in the solvent is 9:(4-5).
[0017] By adopting the above technical solution, xylene, as a solvent, has strong dissolving power and fast evaporation rate, which is conducive to the rapid initial setting of the paint film; small molecule alcohols (such as n-butanol), as co-solvents and diluents, have moderate evaporation rates and can adjust the dissolution state and surface tension of the resin; and the addition of small molecule alcohols is conducive to the formation of hydrogen bonds with hydroxyl, carbonyl, and carboxyl groups on the graphene oxide in the Al2O3-GO composite material, which is conducive to the uniform dispersion of the Al2O3-GO composite material in the matrix, making it less prone to sedimentation, thereby affecting the formation of micro-nano structures on the surface of the paint film.
[0018] Preferably, the small molecule alcohol is one or more of n-butanol, isopropanol, n-propanol, ethanol, butanol, and butanediol.
[0019] Secondly, this application provides a method for preparing a micro / nano structured heat-resistant aging-resistant PP-based coating, employing the following technical solution: A method for preparing a micro / nano-structured heat-resistant aging-resistant PP-based coating includes the following steps: S1. After mixing the modified chlorinated polypropylene resin and the silicone-modified acrylic resin, add all the raw materials except the solvent and continue to stir until uniform to obtain the resin base material. S2. Premix the resin base and solvent in proportion, shear at 1000-1500 rpm for 15 min, and grind to control the fineness to ≤15μm to obtain a micro-nano structure heat-resistant aging PP base coating.
[0020] By adopting the above technical solution, a two-step method is used: S1 first, the main resin matrix is premixed uniformly with various functional solid components (fillers, additives) to form a high-viscosity resin base. This step ensures that solid particles, especially key fillers such as Al2O3-GO composite materials and nano-alumina, can be initially impregnated and encapsulated by the resin, laying the foundation for subsequent deep dispersion. S2 then the resin base is premixed with solvent in a certain proportion and subjected to high-speed shearing and grinding. High-speed shearing provides strong hydrodynamic forces, which can effectively break up soft agglomerates of fillers; the grinding process forcibly reduces the particle size and disperses it uniformly, controlling the fineness to ≤15μm.
[0021] In summary, this application includes at least one of the following beneficial technical effects: 1. This application ensures adhesion to PP substrate by using modified chlorinated polypropylene resin as the main matrix resin, while the introduction of silicone modified acrylic resin (14-24 parts) improves the heat resistance and weather resistance of the system through organosilicon segments. The two work together to solve the fundamental contradiction that it is difficult to balance the adhesion and durability of PP coatings.
[0022] 2. The innovative introduction of Al2O3-GO composite material as the core functional material further enhances the performance of heat aging resistance. This composite material, together with nano-sized alumina and other inorganic fillers in the formulation, forms a multi-level "micron-nano" reinforcing structure on the paint film surface, effectively improving coating hardness, wear resistance, and inhibiting crack propagation. Furthermore, alumina and graphene oxide possess extremely high heat resistance and thermal conductivity; their micro-nano structure acts as a barrier layer on the paint film surface, preventing external heat from penetrating the film and also providing heat dissipation. Structurally, the Al2O3-GO composite material improves the dispersion of graphene oxide and precisely integrates it into the paint film surface, contributing to both heat resistance and heat dissipation. The combination of alumina and graphene oxide achieves a synergistic effect.
[0023] 3. Xylene, as a solvent, has strong dissolving power and fast evaporation rate, which is conducive to the rapid initial setting of the paint film; small molecule alcohols (such as n-butanol), as co-solvents and diluents, have moderate evaporation rates and can adjust the dissolution state and surface tension of the resin; in addition, the addition of small molecule alcohols is conducive to the formation of hydrogen bonds with hydroxyl, carbonyl, and carboxyl groups on the graphene oxide in Al2O3-GO composite materials, which is conducive to the uniform dispersion of Al2O3-GO composite materials in the matrix and is not prone to sedimentation, thereby affecting the formation of micro and nano structures on the surface of the paint film. Detailed Implementation
[0024] The following provides a more detailed description of this application in conjunction with specific details.
[0025] raw material The raw materials used in the preparation examples and embodiments of this application are all commercially available products. Specifically, the modified chlorinated polypropylene resin, Superchlon 822S, was purchased from NIPPON PAPER; the silicone-modified acrylic resin was purchased from Allnex; the carbon black paste pigment contained ≥30% carbon black; the fumed silica, BET 200±20m² / g, was purchased from Evonik; the polyether-modified siloxane leveling agent, BYK-333, was purchased from BYK Chemical; the fluorocarbon surfactant, TEGO Wet270, was purchased from Evonik; the phosphate ester adhesion promoter, BYK-1100, was purchased from BYK Chemical; and the benzotriazole UV absorber, Tinuvin 384-2, was purchased from BASF.
[0026] Preparation Example Preparation Example 1 An Al2O3-GO composite material is prepared by the following method: S1. Add 50g of γ-Al2O3 microspheres with an average particle size of 5μm to 300mL of ethanol / water mixed solvent. After ultrasonic dispersion, add 1.5g of aminosilane coupling agent (KH-550), heat to 80℃, stir and react for 5h to introduce amino groups onto the surface of alumina. Filter, wash with ethanol and deionized water three times each, and dry to obtain silane coupling agent modified alumina. S2. Take an aqueous dispersion of graphene oxide with a solid content of 2.0 wt%. The graphene oxide sheet diameter is about 1 μm and the monolayer rate is >90%. Take the aqueous dispersion of graphene oxide at a mass ratio of 1:100 to alumina. Then add deionized water to make up to 300 mL. After dispersing evenly, add the silane coupling agent modified alumina obtained in S1. Stir and react for 3 hours. Let it settle naturally. It can be observed that the color of the upper dispersion becomes lighter. Then filter, wash with deionized water, and dry to obtain Al2O3-GO composite material.
[0027] The product was observed to contain characteristic peaks of graphene oxide under infrared light, and the difference between the electron microscopy images of the micron-sized alumina microspheres before and after loading with graphene oxide also confirmed that graphene oxide was successfully coated on the surface of the alumina microspheres. Example
[0028] Examples 1-3 A micro / nano-structured heat-resistant aging-resistant PP-based coating, the raw materials and their amounts are shown in Table 1, and its preparation method is as follows: S1. After mixing the modified chlorinated polypropylene resin and the silicone-modified acrylic resin, add all the raw materials except the solvent and continue to stir until uniform to obtain the resin base material. S2. Premix the resin base and solvent according to the proportions in Table 1, shear the mixture for 15 minutes using a high-speed disperser at a shearing speed of 1200 rpm, and then grind it three times using a three-roll mill until the final fineness is controlled to ≤15μm, thus obtaining a micro-nano structure heat-resistant aging PP base coating.
[0029] The Al2O3-GO composite material was prepared by Preparation Example 1; the mass ratio of xylene to n-butanol in the solvent was 9:5.
[0030] Table 1. Raw materials and dosage (kg) for Examples 1-3
[0031] Example 4 A micro / nano structure heat-resistant aging PP-based coating differs from Example 2 in that the amount of Al2O3-GO composite material added is 4 kg, while the remaining steps are the same as in Example 2.
[0032] Example 5 A micro / nano structure heat-resistant aging PP-based coating differs from Example 2 in that the amount of Al2O3-GO composite material added is 8 kg, while the remaining steps are the same as in Example 2.
[0033] Example 6 A micro / nano structure heat-resistant aging PP-based coating differs from Example 2 in that the Al2O3-GO composite material has an average Al2O3 particle size of 1 μm during preparation, while the remaining steps are the same as in Example 2.
[0034] Example 7 A micro / nano structure heat-resistant aging PP-based coating differs from Example 2 in that the Al2O3-GO composite material has an average Al2O3 particle size of 10 μm during preparation, while the remaining steps are the same as in Example 2.
[0035] Example 8 A micro / nano-structured heat-resistant aging PP-based coating differs from Example 2 in that the average sheet diameter of the graphene oxide in the preparation of its Al2O3-GO composite material is 5 μm, while the remaining steps are the same as in Example 2.
[0036] Example 9 A micro / nano structure heat-resistant aging PP-based coating differs from Example 2 in that the mass ratio of xylene to n-butanol in its solvent is 9:4, while the remaining steps are the same as in Example 2.
[0037] Comparative Example Comparative Example 1 A micro / nano structure heat-resistant aging PP-based coating differs from Example 2 in that the Al2O3-GO composite material is replaced with an equal mass of alumina with an average particle size of 5μm, while the remaining steps are the same as in Example 2.
[0038] Comparative Example 2 A micro / nano structure heat-resistant aging PP-based coating differs from Example 2 in that the Al2O3-GO composite material is replaced with an equal mass of alumina with an average particle size of 5μm, and 10g of graphene oxide is added (the concentration difference of the graphene oxide dispersion before and after the reaction is approximately calculated in Preparation Example S2). The remaining steps are the same as in Example 2.
[0039] Comparative Example 3 A micro / nano structure heat-resistant aging PP-based coating differs from Example 2 in that the mass ratio of xylene to n-butanol in its solvent is 9:2, while the remaining steps are the same as in Example 2.
[0040] Performance testing Detection methods / test methods PP-based coatings were prepared according to the preparation methods of Examples 1-9 and Comparative Examples 1-3, and then tested according to the following testing methods. The test results are shown in Table 2.
[0041] The curing degree of the PP-based coating after spraying in this application is as follows: Phase 1: 80℃ × 20 min (solvent evaporation) Second stage: 120℃×15min (crosslinking reaction) Third stage: 160℃×30min (complete curing).
[0042] The testing standards are as follows: Adhesion test: Tested according to the cross-cut adhesion test method of GB / T 9286-2021 standard; Temperature resistance test: The test shall be conducted in accordance with the test method in GB / T 11186.3-2022. The test conditions are 180℃ and placed in a constant temperature chamber for 500h, and the ΔE value shall be measured.
[0043] Hardness: Tested according to the test method in GB / T6739.
[0044] Table 2 Test Results
[0045] As can be seen from the test data in Table 2, the PP-based coatings prepared in this application can achieve an adhesion level of 0 on PP substrates, and under a temperature resistance test at 180℃ for 500h, the ΔE value can reach 0.9 or below, with the lowest reaching 0.4. At the same time, their hardness can reach 3-4H. This indicates that the PP-based coatings prepared in this application have excellent adhesion, heat aging resistance and mechanical properties.
[0046] As can be seen from Examples 2 and 9 and Comparative Examples 1-3, the formation of high-hardness micro / nano structures on the paint film surface in this application requires the interaction between the Al2O3-GO composite material and the small-molecule alcohol solvent in the solvent. Here, the small-molecule alcohol solvent facilitates the formation of hydrogen bonds with the hydroxyl, carbonyl, and carboxyl groups on the graphene oxide in the Al2O3-GO composite material, which is beneficial for the uniform dispersion of the Al2O3-GO composite material in the matrix and prevents sedimentation, thus affecting the formation of the micro / nano structures on the paint film surface. Therefore, the amount of small-molecule alcohol solvent added needs to reach a certain proportion to achieve this effect.
[0047] Combining Examples 2 and 4-5, when the Al2O3-GO composite material is added at a rate of 4-8 kg, it can be uniformly dispersed in the system, does not easily settle, and produces a coating film with superior overall performance.
[0048] In conjunction with Examples 2 and 6-7, an average particle size of Al2O3 of 10 μm is acceptable. In conjunction with Example 8, the sheet diameter of graphene oxide should not be too large, otherwise its coating effect will be affected.
[0049] This specific embodiment is merely an explanation of the present invention and is not intended to limit the invention. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they are within the scope of the claims of the present invention.
Claims
1. A micro / nano-structured heat-resistant aging-resistant PP-based coating, characterized in that: It comprises the following raw materials in parts by weight: 50-60 parts modified chlorinated polypropylene resin, 14-24 parts silicone modified acrylic resin, 4-8 parts Al2O3-GO composite material, 3-7 parts nano alumina, 10-15 parts color paste, 0.8-1.2 parts fumed silica, 0.2-0.6 parts leveling agent, 0.1-0.3 parts wetting agent, 1-1.5 parts adhesion promoter, 0.3-0.6 parts light stabilizer, and 75-85 parts solvent; The particle size of the Al2O3-GO composite material is in the micrometer range; the solvent is a mixture of xylene and small molecule alcohol.
2. The micro / nano structure heat-resistant aging-resistant PP-based coating according to claim 1, characterized in that: The Al2O3-GO composite material is prepared by modifying micron-sized alumina with an aminosilane coupling agent and then loading it with graphene oxide.
3. The micro / nano structure heat-resistant aging-resistant PP-based coating according to claim 2, characterized in that: The average particle size of the micron-sized alumina is 1-10 μm.
4. The micro / nano structure heat-resistant aging-resistant PP-based coating according to claim 2, characterized in that: The aminosilane coupling agent is one or more of γ-aminopropyltriethoxysilane, N-aminoethyl-γ-aminopropyltrimethoxysilane, N-(β-aminoethyl)-γ-aminopropylmethyldimethoxysilane, 3-aminopropyltrimethoxysilane, and anilinemethyltriethoxysilane.
5. The micro / nano structure heat-resistant aging-resistant PP-based coating according to claim 2, characterized in that: The average sheet diameter of the graphene oxide is 1-5 μm, and the average sheet diameter of the graphene oxide is ≤ the average particle size of micron-sized alumina.
6. The micro / nano structure heat-resistant aging-resistant PP-based coating according to claim 1, characterized in that: In the solvent, the mass ratio of xylene to small molecule alcohol is 9:(4-5).
7. The micro / nano structure heat-resistant aging-resistant PP-based coating according to claim 1, characterized in that: The small molecule alcohol is one or more of n-butanol, isopropanol, n-propanol, ethanol, butanol, and butanediol.
8. A method for preparing a micro / nano-structured heat-resistant aging-resistant PP-based coating according to any one of claims 1-7, characterized in that: It includes the following steps: S1. After mixing the modified chlorinated polypropylene resin and the silicone-modified acrylic resin, add all the raw materials except the solvent and continue to stir until uniform to obtain the resin base material. S2. Premix the resin base and solvent in proportion, shear at 1000-1500 rpm for 15 min, and grind to control the fineness to ≤15μm to obtain a micro-nano structure heat-resistant aging PP base coating.