A polypropylene coating and a method for its preparation
By combining fluorine-containing modification and mesoporous organosilicon UV shielding with BMI dynamic crosslinking, the durability and adhesion problems of polypropylene coatings in complex environments were solved, and polypropylene coatings with excellent weather resistance and self-healing properties were prepared.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- JINING CHUANGJIA CHEM TECH CO LTD
- Filing Date
- 2026-04-11
- Publication Date
- 2026-05-29
AI Technical Summary
Traditional polypropylene coatings are insufficient in chemical corrosion resistance, impermeability, and long-term service stability in complex corrosive media such as high concentrations of acids, alkalis, salts, organic solvents, high temperature and high humidity. They also have poor UV stability, weak adhesion, and are prone to aging.
Polypropylene coatings were prepared by introducing fluorine-containing groups to modify polypropylene, combining the UV shielding function of mesoporous organosilicon, and using BMI dynamic reversible crosslinking to construct a strong adhesion and self-healing network.
It significantly improves the coating's outdoor durability, self-healing properties, and corrosion resistance, meeting the stringent durability requirements of high-end protection applications.
Abstract
Description
Technical Field
[0001] This invention belongs to the field of polypropylene coating technology, specifically a polypropylene coating and its preparation method. Background Technology
[0002] In many harsh industrial environments, such as chemical facilities, marine engineering, sewage treatment and oil and gas transportation, equipment and components are exposed to complex corrosive media such as high concentrations of acids, alkalis and salts, organic solvents, high temperature and high humidity for a long time, which puts forward stringent requirements on the chemical corrosion resistance, impermeability and long-term service stability of protective coatings.
[0003] Polypropylene (PP) resin is considered an ideal high-performance anti-corrosion film-forming resin due to its excellent chemical inertness, good insulation, low density, and cost advantages. Its stable molecular structure can withstand the erosion of various chemical media and theoretically can provide a reliable chemical barrier for the substrate, effectively extending its service life in harsh environments. However, the unmodified polypropylene molecular chain structure exhibits highly nonpolar and highly crystalline characteristics, with low surface energy, resulting in poor adhesion to the substrate and difficulty in dissolving in conventional coating solvents, making it difficult to directly process into films. These defects have long restricted the application of polypropylene in the coating field.
[0004] Chinese patent application CN104910665A discloses a chlorinated polypropylene coating and its preparation method. This method introduces chlorine atoms into the polypropylene molecular chain, effectively increasing the polarity of the resin, thereby improving the coating's solubility in conventional solvents and its adhesion to various substrates. However, the C-Cl bonds in the chlorinated polypropylene molecular chain are chemically unstable under ultraviolet light irradiation and are prone to breakage, generating chlorine free radicals and polymer free radicals. This further triggers polymer chain breakage and cross-linking processes, ultimately leading to the deterioration of the coating's surface properties. The coating's insufficient durability under outdoor ultraviolet irradiation limits its widespread application. Summary of the Invention
[0005] The purpose of this invention is to provide a polypropylene coating and its preparation method. By introducing fluorine-containing groups, the coating is endowed with low surface energy and weather resistance. Combined with the UV shielding function of mesoporous organosilicon, and supplemented by BMI dynamic reversible crosslinking to construct a strong adhesion and self-healing network, the invention synergistically solves the problems of poor UV stability, weak adhesion and easy aging of traditional polypropylene coatings. It significantly improves the outdoor durability, self-healing and corrosion resistance of the coating, and is suitable for high-end protective fields with stringent durability requirements, such as outdoor building materials and automotive shells.
[0006] The objective of this invention can be achieved through the following technical solutions:
[0007] A method for preparing a polypropylene coating includes the following steps:
[0008] Step 1: First, amino groups are attached to the surface of tung oil acid by photo-initiated mercapto-olefin reaction to obtain aminated tung oil acid. Then, CTAB is used as a template agent and 1,2-bis(trimethoxysilyl ethane) is used as a silicon source to co-condense with aminated tung oil acid to obtain mesoporous organosilicon@aminated tung oil acid.
[0009] Step 2: Using polypropylene and trifluoroethyl methacrylate as raw materials, TFEMA grafted modified polypropylene is obtained by melt graft polymerization.
[0010] Step 3: Using xylene as solvent and bismaleimide as crosslinking agent, TFEMA-grafted modified polypropylene, mesoporous organosilicon@amino tung oil acid, antioxidant 1010, dispersant BYK-163 and leveling agent BYK-358N are blended and reacted to obtain polypropylene coating.
[0011] Furthermore, the specific preparation steps of mesoporous organosilicon@aminotung oil acid are as follows:
[0012] Hexadecyltrimethylammonium bromide and deionized water were added to a reaction vessel and stirred until dissolved. Then, a 2 mol / L NaOH solution was added. 1,2-bis(trimethoxysilyl ethane) and amino-modified tung oil acid were added to the vessel at 75-85℃ and 180-220 r / min. The reaction was carried out at a constant temperature for 1.5-2.5 h. After the reaction was completed, the product was centrifuged, washed, and dried. The crude product was dispersed in a mixture of ethanol and 0.2 mol / L hydrochloric acid solution and stirred at 55-65℃ and 180-220 r / min for 9-11 h. After removing CTAB, the product was centrifuged and dried to obtain mesoporous organosilicon@amino-modified tung oil acid.
[0013] Furthermore, the ratio of hexadecyltrimethylammonium bromide, deionized water, NaOH solution, 1,2-bis(trimethoxysilylethane) and amino-modified tung oil acid is 22-25g: 9-10L: 75-80mL: 16-18g: 3-5g.
[0014] Furthermore, the specific preparation steps for aminoated tung oil acid are as follows:
[0015] Under a nitrogen atmosphere, cysteine hydrochloride and methanol were added to the reactor and stirred until dissolved. Then, tung oil acid and photoinitiator DMPA were added to the reactor. The reaction mixture was maintained at 450-550 rpm, 23-27°C, and 50 mW / cm². 2 The reaction was carried out under constant temperature for 2-3 hours under ultraviolet light. After the reaction was completed, the product was washed, dried, filtered, and rotary evaporated to obtain aminoated tung oil acid.
[0016] Furthermore, the ratio of cysteine hydrochloride, methanol, tung oil acid, and photoinitiator DMPA is 12-13g: 4-6mL: 28-29g: 0.75-0.85g.
[0017] Furthermore, the specific preparation steps for TFEMA-grafted modified polypropylene are as follows:
[0018] Polypropylene and di-tert-butyl peroxide were added to a reactor and melt-blended at 185-195℃ and 50-70 r / min for 5-7 min. Trifluoroethyl methacrylate was then added, and the reaction was continued for 5-10 min under the same conditions. The mixture was dissolved in toluene, precipitated with ethanol, filtered, washed, and dried to obtain TFEMA-grafted modified polypropylene.
[0019] Furthermore, the mass ratio of polypropylene, di-tert-butyl peroxide, and trifluoroethyl methacrylate is 90-110:0.09-0.11:8-12.
[0020] Furthermore, the specific preparation steps of the polypropylene coating are as follows:
[0021] TFEMA-grafted modified polypropylene and xylene were added to a reactor and stirred until dissolved. Bismaleimide was then added to the reactor and stirred at 55-65℃ and 250-350 rpm for 25-35 minutes. Subsequently, mesoporous organosilicon@aminotung oil acid was slowly added to the reactor and reacted at 80-85℃ for 2-3 hours. After the reaction was completed, antioxidant 1010, dispersant BYK-163, and leveling agent BYK-358N were added at 50-60℃ and stirred for 25-35 minutes. The mixture was then filtered to obtain a polypropylene coating.
[0022] Furthermore, the ratio of TFEMA-grafted modified polypropylene, xylene, bismaleimide, mesoporous organosilicon@amino tung oil acid, antioxidant 1010, dispersant BYK-163 and leveling agent BYK-358N is 90-110g: 300-400mL: 1-3g: 5-8g: 0.5-1g: 0.5-1g: 0.2-0.5.
[0023] The beneficial effects of this invention are:
[0024] 1. This invention utilizes a synergistic process system of aminated tung oil acid modification, fluorinated graft modification, and dynamic cross-linking curing to achieve enhanced coating interface, UV protection, and mechanical stability. Simultaneously, it effectively improves the problems of low polarity, weak adhesion, and poor weather resistance in traditional polypropylene coatings. The prepared polypropylene coating maintains good workability while enhancing the bonding strength between the coating and the substrate and its outdoor aging resistance. This meets the application requirements of outdoor building materials, automotive shells, and other fields for the adhesion and weather resistance of protective coatings under long-term service conditions.
[0025] 2. In this invention, the amino-modified tung oil acid and mesoporous organosilicon work synergistically. The amino group can form hydrogen bonds with the silanol groups of the mesoporous organosilicon and can also bind to the surface of the polypropylene substrate through physical adsorption and weak interactions, synergistically constructing a stable interfacial anchoring structure and improving the adhesion between the coating and the substrate. The hydrophobic and oleophilic properties of the long chain of tung oil acid can improve the compatibility between the amino-modified tung oil acid and TFEMA-grafted modified polypropylene, reduce component aggregation, and improve film continuity and flexibility. The porous structure of the mesoporous organosilicon can form a physical shield, blocking ultraviolet light and external media from penetrating into the coating. The three factors synergistically optimize the interfacial adhesion and weather resistance of the coating.
[0026] 3. This invention uses trifluoroethyl methacrylate grafted polypropylene. The strong electronegativity of the fluorinated groups can enhance the polarity of the polypropylene molecular chain, improve its dispersion compatibility with polar components such as mesoporous organosilicon@aminotung oil acid and bismaleimide, and avoid defects such as delamination and particles in the coating system. At the same time, the chemical inertness of the fluorinated groups can reduce the surface energy of the coating, reduce the adsorption and erosion of external media, and form a synergistic protection of chemical inertness and physical barrier with the physical shielding effect of mesoporous organosilicon@aminotung oil acid, further enhancing the weather resistance and resistance to media erosion of the coating.
[0027] 4. This invention introduces bismaleimide as a crosslinking agent. As a dienophile, it can form a dynamic and reversible covalent crosslinking network with the conjugated diene retained in amino tung oil acid through the Diels-Alder reaction. This network structure can improve the coating's cohesion and interfacial bonding strength, inhibit crack propagation under external force, and at the same time, the crosslinking network can restrict the free migration of molecular chains, delay the degradation and aging of molecular chains caused by ultraviolet light. It works synergistically with the interfacial anchoring of mesoporous organosilicon@amino tung oil acid and the chemical stabilizing effect of fluorine-containing groups to form a synergistic effect of crosslinking enhancement, interfacial anchoring and multiple protection, comprehensively improving the mechanical stability and long-term aging resistance of the coating. Detailed Implementation
[0028] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.
[0029] Example 1: A polypropylene coating, comprising the following steps:
[0030] S1: Under a nitrogen atmosphere, 12.2 g of cysteine hydrochloride and 5 mL of methanol were added to the reactor and stirred until dissolved. Then, 28.2 g of tung oil acid and 0.81 g of photoinitiator DMPA were added to the reactor. The reaction was carried out at a rotation speed of 500 r / min, a temperature of 25℃, and an ultraviolet irradiance of 50 mW / cm². 2 Under constant temperature conditions, the reaction was carried out for 2.5 h. After the reaction was completed, the product was dissolved in 5 times the volume of ethyl acetate and washed 3 times with an equal volume of saturated NaCl solution. After separation, the organic phase was dried with anhydrous magnesium sulfate for 12 h. The filtrate was collected by filtration and the filtrate was rotary evaporated at 40 °C for 30 min to remove ethyl acetate, yielding amino-modified tung oil acid.
[0031] Through a photo-initiated thiol-alkene click reaction, using cysteine hydrochloride as the amino donor (containing reactive thiol groups) and tung oil acid as the hydrophobic long-chain host containing unsaturated double bonds, under the synergistic effect of photoinitiator DMPA and ultraviolet light, the thiol groups of cysteine hydrochloride undergo an addition reaction with the unsaturated double bonds in the tung oil acid molecule, introducing an amino functional group. The long carbon chain skeleton and some unsaturated double bonds of tung oil acid are retained. After purification, aminated tung oil acid is obtained, which combines the natural long-chain hydrophobicity, the ultraviolet absorption function of the residual double bonds, and the amino reactivity.
[0032] S2: 23g of hexadecyltrimethylammonium bromide (CTAB) and 9.5L of deionized water were added to a reaction vessel and stirred until dissolved. Then, 78mL of 2mol / L NaOH solution was added. Under the conditions of 80℃ and 200r / min, 17g of 1,2-bis(trimethoxysilylethane) and 4g of amino-modified tung oil acid were added to the vessel and reacted at a constant temperature for 2h. After the reaction was completed, the mixture was centrifuged at 8000r / min for 3min. The precipitate was washed with deionized water and ethanol in sequence and dried at 80℃. The crude product was dispersed in a mixture of ethanol and 0.2mol / L hydrochloric acid solution and stirred at 60℃ and 200r / min for 10h to remove CTAB. After centrifugation for 3min, the mixture was dried at 80℃ to obtain mesoporous organosilicon@amino-modified tung oil acid.
[0033] A template-induced co-condensation process was adopted, using hexadecyltrimethylammonium bromide as a mesoporous template agent, 1,2-bis(trimethoxysilylethane) as a silicon source, and amino-modified tung oil acid as a functional modifier. The siloxane bonds of BTME underwent hydrolysis and condensation reaction, and at the same time, it achieved co-assembly with amino-modified tung oil acid through the interaction of amino and silanol groups. After centrifugation, washing, drying, and removal of the CTAB template agent in an ethanol-dilute hydrochloric acid mixture, mesoporous organosilicon@amino-modified tung oil acid was obtained, which has a mesoporous structure, natural long-chain hydrophobicity, and amino reactivity.
[0034] S3: 100g of polypropylene (PP) and 0.1g of di-tert-butyl peroxide (DTBP) were added to a reactor and melt-blended at 190℃ and 60r / min for 6min. Then, 10g of trifluoroethyl methacrylate (TFEMA) was added and the reaction was continued for 8min under the same conditions. The product was then shredded and 15 times the mass of toluene was added. The mixture was heated until the solid was completely dissolved. While hot, the mixture was filtered through a nickel mesh into an equal volume of anhydrous ethanol while stirring. After a white flocculent precipitate was formed, the mixture was filtered again and washed several times with anhydrous ethanol. Finally, the mixture was dried in a vacuum oven at 60℃ for 12h to obtain TFEMA-grafted modified polypropylene.
[0035] By employing melt graft polymerization, under high-temperature melting conditions, the active sites on the polypropylene (PP) molecular chain undergo a grafting reaction with the double bonds of trifluoroethyl methacrylate, introducing fluorine-containing groups into the PP molecular chain. After dissolution in toluene, impurity removal by nickel mesh filtration, purification by precipitation in anhydrous ethanol, and vacuum drying, TFEMA-grafted modified polypropylene is obtained, which combines the compatibility of the polypropylene matrix with the low surface energy and high UV stability of the fluorine-containing groups.
[0036] S4: Add 100g of TFEMA-grafted modified polypropylene and 350mL of xylene to a reaction vessel and stir until dissolved. Add 2g of bismaleimide (BMI) to the vessel and stir for 30min at 60℃ and 300r / min to form a homogeneous solution. Then slowly add 6.5g of mesoporous organosilicon@aminotung oil acid to the vessel and stir for 2.5h at 82℃. After the reaction is completed, lower the temperature to 55℃ and add 0.75g of antioxidant 1010, 0.75g of dispersant BYK-163 and 0.35g of leveling agent BYK-358N. Stir for 30min and then filter through a 1000-mesh filter to remove impurities to obtain polypropylene coating.
[0037] Example 2: A polypropylene coating, comprising the following steps:
[0038] S1: Under a nitrogen atmosphere, 12g of cysteine hydrochloride and 4mL of methanol were added to the reactor and stirred until dissolved. Then, 28g of tung oil acid and 0.75g of photoinitiator DMPA were added to the reactor. The reaction was carried out at a rotation speed of 450r / min, a temperature of 23℃, and an irradiance of 50mW / cm². 2 The reaction was carried out under UV light at a constant temperature for 2 hours. After the reaction was completed, the product was dissolved in 5 times the volume of ethyl acetate and washed 3 times with an equal volume of saturated NaCl solution. After separation, the organic phase was dried with anhydrous magnesium sulfate for 12 hours. The filtrate was collected by filtration and the ethyl acetate was removed by rotary evaporation at 40°C for 30 minutes to obtain aminoated tung oil acid.
[0039] S2: 22g of hexadecyltrimethylammonium bromide (CTAB) and 9L of deionized water were added to a reaction vessel and stirred until dissolved. Then, 75mL of 2mol / L NaOH solution was added. Under the conditions of 75℃ and 180r / min, 16g of 1,2-bis(trimethoxysilylethane) and 3g of amino-modified tung oil acid were added to the vessel and reacted at a constant temperature for 1.5h. After the reaction was completed, the mixture was centrifuged at 7500r / min for 2min. The precipitate was washed with deionized water and ethanol in sequence and dried at 75℃. The crude product was dispersed in a mixture of ethanol and 0.2mol / L hydrochloric acid solution and stirred at 55℃ and 180r / min for 9h to remove CTAB. After centrifugation for 2min, the mixture was dried at 80℃ to obtain mesoporous organosilicon@amino-modified tung oil acid.
[0040] S3: Add 90g of polypropylene (PP) and 0.09g of di-tert-butyl peroxide (DTBP) to a reactor and melt-blend them for 5 min at 185℃ and 50 r / min. Then add 8g of trifluoroethyl methacrylate (TFEMA) and continue the reaction for 5 min under the same conditions. Cut the product into small pieces and add 15 times the mass of the product to toluene. Heat until the solid is completely dissolved. While hot, filter the mixture through a nickel mesh into an equal volume of anhydrous ethanol while stirring. After a white flocculent precipitate is formed, filter the mixture under vacuum and wash it several times with anhydrous ethanol. Finally, dry the mixture in a vacuum oven at 60℃ for 12 h to obtain TFEMA-grafted modified polypropylene.
[0041] S4: Add 90g of TFEMA-grafted modified polypropylene and 300mL of xylene to a reaction vessel and stir until dissolved. Add 1g of bismaleimide (BMI) to the vessel and stir for 25min at 55℃ and 250r / min to form a homogeneous solution. Then slowly add 5g of mesoporous organosilicon@aminotung oil acid to the vessel and stir for 2h at 80℃. After the reaction is completed, lower the temperature to 50℃ and add 0.5g of antioxidant 1010, 0.5g of dispersant BYK-163 and 0.2g of leveling agent BYK-358N. After stirring for 25min, filter through a 1000-mesh filter to remove impurities and obtain polypropylene coating.
[0042] Example 3: A polypropylene coating, comprising the following steps:
[0043] S1: Under a nitrogen atmosphere, 13g of cysteine hydrochloride and 6mL of methanol were added to the reactor and stirred until dissolved. Then, 29g of tung oil acid and 0.85g of photoinitiator DMPA were added to the reactor. The reaction was carried out at a rotation speed of 550r / min, a temperature of 27℃, and an irradiance of 50mW / cm². 2The reaction was carried out under UV light at a constant temperature for 3 hours. After the reaction was completed, the product was dissolved in 5 times the volume of ethyl acetate and washed 3 times with an equal volume of saturated NaCl solution. After separation, the organic phase was dried with anhydrous magnesium sulfate for 12 hours. The filtrate was collected by filtration and the ethyl acetate was removed by rotary evaporation at 40°C for 30 minutes to obtain aminoated tung oil acid.
[0044] S2: 25g of hexadecyltrimethylammonium bromide (CTAB) and 10L of deionized water were added to a reaction vessel and stirred until dissolved. Then, 80mL of 2mol / L NaOH solution was added. Under the conditions of 85℃ and 220r / min, 18g of 1,2-bis(trimethoxysilylethane) and 5g of amino-modified tung oil acid were added to the vessel and reacted at a constant temperature for 2.5h. After the reaction was completed, the mixture was centrifuged at 8500r / min for 4min. The precipitate was washed with deionized water and ethanol in sequence and dried at 85℃. The crude product was dispersed in a mixture of ethanol and 0.2mol / L hydrochloric acid solution and stirred at 65℃ and 220r / min for 11h to remove CTAB. After centrifugation for 4min, the mixture was dried at 80℃ to obtain mesoporous organosilicon@amino-modified tung oil acid.
[0045] S3: 110g of polypropylene (PP) and 0.11g of di-tert-butyl peroxide (DTBP) were added to a reactor and melt-blended at 195℃ and 70r / min for 7min. Then, 12g of trifluoroethyl methacrylate (TFEMA) was added and the reaction was continued for 10min under the same conditions. The product was then shredded and 15 times its mass of toluene was added. The mixture was heated until the solid was completely dissolved. While hot, the mixture was filtered through a nickel mesh into an equal volume of anhydrous ethanol while stirring. After a white flocculent precipitate was formed, the mixture was filtered again and washed several times with anhydrous ethanol. Finally, the mixture was dried in a vacuum oven at 60℃ for 12h to obtain TFEMA-grafted modified polypropylene.
[0046] S4: Add 110g of TFEMA-grafted modified polypropylene and 400mL of xylene to a reaction vessel and stir until dissolved. Add 3g of bismaleimide (BMI) to the vessel and stir for 35min at 65℃ and 350r / min to form a homogeneous solution. Then slowly add 8g of mesoporous organosilicon@aminotung oil acid to the vessel and stir for 3h at 85℃. After the reaction is completed, lower the temperature to 60℃, then add 1g of antioxidant 1010, 1g of dispersant BYK-163 and 0.5g of leveling agent BYK-358N. After stirring for 35min, filter through a 1000-mesh filter to remove impurities and obtain polypropylene coating.
[0047] The raw materials used in Examples 1-3 of this application are all commercially available, including polypropylene (homopolymer, melt index 35 g / 10 min, molecular weight 200,000-300,000 g / mol), hexadecyltrimethylammonium bromide (99%), 1,2-bis(trimethoxysilylethane) (95%), and di-tert-butyl peroxide (97%).
[0048] All were purchased from Shanghai Maclean Biochemical Technology Co., Ltd.; cysteine hydrochloride (95%) and photoinitiator DMPA (analytical grade) were purchased from Shanghai Aladdin Biochemical Co., Ltd.; tung oil acid (purity 99%) was purchased from Wuhan Jiyesheng Chemical Co., Ltd.; trifluoroethyl methacrylate (analytical grade) was purchased from Xuejia Fluorosilicone Chemical Co., Ltd.; bismaleimide (98%) was purchased from Shanghai Xinyue Chemical Co., Ltd.; antioxidant 1010 was purchased from Guangzhou Dayin New Material Co., Ltd.; dispersant BYK-163 and leveling agent BYK-358N were purchased from Guangzhou Yinman New Material Co., Ltd.
[0049] Comparative Example 1: Based on Example 1, the preparation of aminoated tung oil acid in step S1 and mesoporous organosilicon@aminoated tung oil acid in step S2 was omitted, and mesoporous organosilicon@aminoated tung oil acid was not added in step S4. All other steps and parameters remained unchanged to obtain a polypropylene coating.
[0050] Comparative Example 2: Based on Example 1, step S3, the preparation of TFEMA-grafted modified polypropylene, was omitted. In step S4, 100g of unfluorinated pure polypropylene (PP) was directly used to replace the TFEMA-grafted modified polypropylene, while all other steps and parameters remained unchanged, resulting in a polypropylene coating.
[0051] Comparative Example 3: Based on Example 1, the addition of bismaleimide (BMI) in step S4 was omitted, and all other steps and parameters remained unchanged to obtain a polypropylene coating.
[0052] The polypropylene coatings prepared in Examples 1-3 and Comparative Examples 1-3 were subjected to performance tests. The appearance was visually inspected to check for uniformity, bubbles, particles, and depressions. The uniform appearance of the coatings without defects indicates good dispersibility and workability. The viscosity was measured according to GB / T 9751.1-2008 standard using a rotational viscometer. The viscosity was within a suitable range, indicating good leveling properties and workability of the coatings.
[0053] The polypropylene coatings obtained in Examples 1-3 and Comparative Examples 1-3 were uniformly applied to pretreated standard polypropylene boards and cured at room temperature for 7 days to form a coating with a dry film thickness of approximately 50±5μm. Subsequent performance tests were then conducted. The adhesion was measured in accordance with GB / T 9286-1998 standard, and the adhesion of the coating to the polypropylene substrate was determined using the cross-cut test. The higher the adhesion grade, the stronger the bond between the coating and the substrate.
[0054] The UV aging resistance performance is referenced to GB / T 1865-2009 standard. The xenon lamp aging test is adopted. After 1000 hours of artificial climate aging, the gloss retention rate of the coating is tested. The higher the gloss retention rate, the stronger the coating's resistance to UV degradation. When used outdoors for a long time, it is not easy to show aging phenomena such as chalking, yellowing and loss of gloss, and the better the weather resistance.
[0055] The results are shown in Table 1:
[0056] Table 1 Performance test results of various polypropylene coatings and coating layers
[0057] Project Group Appearance Viscosity (KU) Adhesion (Grade) Gloss retention rate (%) Example 1 The surface is smooth and flat, without bubbles or dents. 96 0 87.2 Example 2 The surface is smooth and flat, without bubbles or dents. 95 0 86.5 Example 3 The surface is smooth and flat, without bubbles or dents. 97 0 87.8 Comparative Example 1 The surface is smooth and flat, without bubbles or dents. 94 2 52.3 Comparative Example 2 The surface has a slight granular texture but no bubbles. 92 3 41.7 Comparative Example 3 The surface is smooth and flat, without bubbles or dents. 93 2 85.1
[0058] As shown in Table 1, the polypropylene coatings prepared in Examples 1-3 of this invention exhibit excellent comprehensive performance. Regarding basic construction performance, the coatings in these examples all have a smooth and flat appearance without bubbles or depressions, and their viscosity is stable within the 95-97 KU range, demonstrating good dispersibility and construction adaptability. In terms of interfacial bonding performance, the adhesion reaches grade 0, indicating that the coating is firmly bonded to the polypropylene substrate and is not prone to peeling or flaking. Regarding weather resistance, the gloss retention rate after 1000 hours of xenon lamp aging all exceeds 86%, demonstrating excellent resistance to UV degradation and meeting the requirements for long-term outdoor use. In summary, this invention, through the synergistic effect of fluorine-containing graft modification, mesoporous organosilicon UV shielding, and BMI dynamic crosslinking, prepares a polypropylene protective coating that combines good workability, high adhesion, and excellent weather resistance.
[0059] Comparative Example 1, without the addition of mesoporous organosilicon@aminotung oil acid, showed a drop in adhesion to grade 2 and a gloss retention rate of only 52.3%, significantly lower than the examples. This may be due to the lack of interfacial anchoring effect of aminotung oil acid and UV shielding effect of mesoporous organosilicon, resulting in weakened adhesion between the coating and the substrate and a significant decrease in resistance to UV degradation. This indicates that mesoporous organosilicon@aminotung oil acid can effectively optimize interfacial bonding and provide UV shielding function, making it a key component for improving coating adhesion and weather resistance.
[0060] Comparative Example 2 uses unmodified pure polypropylene, which has a slightly grainy appearance, reduced adhesion to level 3, and a gloss retention rate of only 41.7%. This may be because the unmodified polypropylene has too low polarity, poor compatibility with additives and fillers, and lacks the weather protection of fluorinated groups, resulting in poor dispersibility, weak interfacial bonding, and easy UV aging. This indicates that trifluoroethyl methacrylate graft modification can significantly improve the polarity and dispersibility of polypropylene, while giving the coating excellent weather resistance and stability, which is a necessary prerequisite for achieving good appearance and high weather resistance.
[0061] Comparative Example 3, without the addition of bismaleimide (BMI) crosslinking agent, showed a drop in adhesion to grade 2 and a slightly lower gloss retention rate than the Example. This may be due to the lack of a three-dimensional network structure formed by dynamic reversible crosslinking of BMI, resulting in insufficient coating cohesion, reduced interfacial bonding strength, and inability to effectively suppress UV-induced molecular chain breakage. This indicates that dynamic reversible crosslinking of BMI can effectively construct a strong interfacial bonding network, improve the mechanical stability and aging resistance of the coating, and is an important factor in ensuring the long-term performance of the coating.
[0062] It should be noted that, in this document, terms such as “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.
[0063] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention.
Claims
1. A method for preparing a polypropylene coating, characterized in that, Includes the following steps: Step 1: First, amino groups are attached to the surface of tung oil acid by photo-initiated mercapto-ene reaction to obtain aminated tung oil acid. Then, CTAB is used as a template agent and 1,2-bis(trimethoxysilyl ethane) is used as a silicon source to co-condense with aminated tung oil acid to obtain mesoporous organosilicon@aminated tung oil acid. Step 2: Using polypropylene and trifluoroethyl methacrylate as raw materials, TFEMA-grafted modified polypropylene is obtained by melt graft polymerization. Step 3: Using xylene as solvent and bismaleimide as crosslinking agent, TFEMA-grafted modified polypropylene, mesoporous organosilicon@amino tung oil acid, antioxidant 1010, dispersant BYK-163 and leveling agent BYK-358N are blended and reacted to obtain polypropylene coating.
2. The method for preparing a polypropylene coating according to claim 1, characterized in that, The specific preparation steps for the mesoporous organosilicon@aminotung oil acid are as follows: Hexadecyltrimethylammonium bromide and deionized water were added to a reaction vessel and stirred until dissolved. Then, a 2 mol / L NaOH solution was added. 1,2-bis(trimethoxysilyl ethane) and amino-modified tung oil acid were added to the vessel at 75-85℃ and 180-220 r / min. The reaction was carried out at a constant temperature for 1.5-2.5 h. After the reaction was completed, the product was centrifuged, washed, and dried. The crude product was dispersed in a mixture of ethanol and 0.2 mol / L hydrochloric acid solution and stirred at 55-65℃ and 180-220 r / min for 9-11 h. After removing CTAB, the product was centrifuged and dried to obtain mesoporous organosilicon@amino-modified tung oil acid.
3. The method for preparing a polypropylene coating according to claim 2, characterized in that, The ratio of hexadecyltrimethylammonium bromide, deionized water, NaOH solution, 1,2-bis(trimethoxysilylethane) and amino-modified tung oil acid is 22-25g: 9-10L: 75-80mL: 16-18g: 3-5g.
4. The method for preparing a polypropylene coating according to claim 2, characterized in that, The specific preparation steps for the aminoated tung oil acid are as follows: Under a nitrogen atmosphere, cysteine hydrochloride and methanol were added to the reactor and stirred until dissolved. Then, tung oil acid and photoinitiator DMPA were added to the reactor. The reaction mixture was maintained at 450-550 rpm, 23-27°C, and 50 mW / cm². 2 The reaction was carried out under constant temperature for 2-3 hours under ultraviolet light. After the reaction was completed, the product was washed, dried, filtered, and rotary evaporated to obtain aminoated tung oil acid.
5. The method for preparing a polypropylene coating according to claim 4, characterized in that, The ratio of cysteamine hydrochloride, methanol, tung oil acid and photoinitiator DMPA is 12-13g: 4-6mL: 28-29g: 0.75-0.85g.
6. The method for preparing a polypropylene coating according to claim 1, characterized in that, The specific preparation steps for the TFEMA-grafted modified polypropylene are as follows: Polypropylene and di-tert-butyl peroxide were added to a reactor and melt-blended at 185-195℃ and 50-70 r / min for 5-7 min. Trifluoroethyl methacrylate was then added, and the reaction was continued for 5-10 min under the same conditions. The mixture was dissolved in toluene, precipitated with ethanol, filtered, washed, and dried to obtain TFEMA-grafted modified polypropylene.
7. The method for preparing a polypropylene coating according to claim 6, characterized in that, The mass ratio of polypropylene, di-tert-butyl peroxide, and trifluoroethyl methacrylate is 90-110:0.09-0.11:8-12.
8. The method for preparing a polypropylene coating according to claim 1, characterized in that, The specific preparation steps of the polypropylene coating are as follows: TFEMA-grafted modified polypropylene and xylene were added to a reactor and stirred until dissolved. Bismaleimide was then added to the reactor and stirred at 55-65℃ and 250-350 rpm for 25-35 minutes. Subsequently, mesoporous organosilicon@aminotung oil acid was slowly added to the reactor and reacted at 80-85℃ for 2-3 hours. After the reaction was completed, antioxidant 1010, dispersant BYK-163, and leveling agent BYK-358N were added at 50-60℃ and stirred for 25-35 minutes. The mixture was then filtered to obtain a polypropylene coating.
9. The method for preparing a polypropylene coating according to claim 1, characterized in that, The ratio of TFEMA-grafted modified polypropylene, xylene, bismaleimide, mesoporous organosilicon@amino tung oil acid, antioxidant 1010, dispersant BYK-163 and leveling agent BYK-358N is 90-110g: 300-400mL: 1-3g: 5-8g: 0.5-1g: 0.5-1g: 0.2-0.
5.
10. A polypropylene coating, characterized in that, It is prepared by the preparation method described in any one of claims 1-9.