Corrosion-resistant unsaturated polyester resin composite material and preparation method thereof

Abstract

The invention discloses a corrosion-resistant unsaturated polyester resin composite material and a preparation method thereof, and relates to the technical field of resin materials. The method comprises the following steps: firstly, treating carbon fiber cloth through polyamine functionalized graphene interface modification liquid to prepare polyamine graphene modified oxidized carbon fiber cloth; mixing unsaturated polyester resin with styrene, the modified corrosion-resistant cross-linking agent, isopropyl phenyl phosphate and fumed silica, and adding cobalt iso-octoate to prepare modified reinforced unsaturated polyester resin; and finally, the target composite material is prepared through layer laying compounding, stepped pressurization curing, post-heat treatment and surface hole sealing treatment. By means of interface synergistic modification, polyfunctional group cross-linking agent customization and whole-process technology optimization, the problems that a traditional material is weak in interface bonding, insufficient in corrosion resistance and difficult to consider performance are solved, mechanical performance and corrosion resistance are synergistically improved, and the material can be widely applied to severe working conditions such as chemical engineering and ocean engineering.

Description

Technical Field

[0001] This invention relates to the field of resin materials technology, specifically to a corrosion-resistant unsaturated polyester resin composite material and its preparation method. Background Technology

[0002] Unsaturated polyester resin composites are widely used in construction, chemical engineering, and marine engineering due to their cost-effectiveness and good processability. While fiber reinforcement enhances their mechanical properties, meeting the requirements of most structural components, their long-term service stability in complex corrosive environments remains a challenge. Corrosion failure in these materials often begins with internal structural defects or interface problems, gradually affecting overall performance and becoming a key factor limiting their widespread adoption under harsh operating conditions.

[0003] Carbon fiber, as a commonly used reinforcement, has a strong surface chemical inertness, resulting in insufficient interfacial bonding with the unsaturated polyester resin matrix and a tendency to form microscopic gaps. These gaps become natural channels for corrosive media to penetrate, leading to problems such as interfacial delamination and fiber degradation, which in turn cause a rapid decline in the material's mechanical properties. Traditional interfacial modification methods mostly rely on surface treatment of single components, making it difficult to simultaneously achieve the dual effects of interfacial adhesion enhancement and corrosion barrier, and thus failing to fundamentally solve the problem of interfacial failure.

[0004] Traditional unsaturated polyester resins have limited resistance to acids, alkalis, and salt spray, and commonly used crosslinking agents are mostly single-functional, making it difficult to simultaneously achieve high crosslinking density in the matrix and improved corrosion resistance. Furthermore, microcracks and pinholes are prone to occur on the surface of composite materials during molding, and the lack of effective sealing measures further exacerbates the penetration of corrosive media. Existing technologies either focus on strengthening mechanical properties while neglecting corrosion resistance, or simply improve the corrosion resistance of the matrix without addressing interfacial bonding and surface defect issues, resulting in materials whose overall performance fails to meet the requirements of complex corrosive environments. Summary of the Invention

[0005] In view of this, the purpose of this invention is to provide a corrosion-resistant unsaturated polyester resin composite material, its preparation method and application, which effectively solves the problems of weak fiber-resin interface bonding, insufficient corrosion resistance of resin matrix, and easy penetration of corrosive media by surface micro-defects in existing unsaturated polyester resin composite materials, making it difficult to achieve both mechanical properties and corrosion resistance, and realizes the synergistic improvement of material mechanical properties and corrosion resistance.

[0006] The objective of this invention can be achieved through the following technical solutions: In a first aspect, the present invention provides a method for preparing a corrosion-resistant unsaturated polyester resin composite material, comprising the following preparation steps: S1: Carbon fiber cloth is oxidized in air in a muffle furnace to obtain oxidized carbon fiber cloth. The oxidized carbon fiber cloth is immersed in polyamine functionalized graphene interface modification liquid for ultrasonic impregnation. After removal, it is pre-cured to obtain polyamine graphene modified oxidized carbon fiber cloth. S2: Mix unsaturated polyester resin and styrene, add modified corrosion-resistant crosslinking agent, add triisopropylphenyl phosphate and fumed silica, disperse at high speed and degas under vacuum, add cobalt isooctanoate, stir evenly to obtain modified and reinforced unsaturated polyester resin. S3: Modified and reinforced unsaturated polyester resin and polyamine graphene modified carbon fiber cloth are laminated to obtain a polyester resin composite material. The polyester resin composite material is then subjected to step-by-step pressure curing, post-heat treatment and surface sealing treatment to prepare a corrosion-resistant unsaturated polyester resin composite material.

[0007] Furthermore, the air oxidation conditions for the carbon fiber cloth in S1 are: holding at 320℃-380℃ in a muffle furnace for 1.2h-1.8h; the ultrasonic impregnation conditions are: ultrasonic treatment at 350W-450W power for 35min-55min; and the pre-curing conditions are: holding at 85℃-95℃ for 1.1h-1.4h.

[0008] Furthermore, the preparation method of the polyamine-functionalized graphene interface modification liquid is as follows: Graphene oxide was dispersed in deionized water and sonicated to obtain a graphene oxide dispersion. Polyethyleneimine and γ-glycidyl etheroxypropyltrimethoxysilane were added, and the mixture was heated under nitrogen protection. After the reaction was completed, the temperature was lowered, dibutyltin dilaurate was added, and stirring was continued. After stirring was completed, a polyamine-functionalized graphene interface-modified solution was obtained.

[0009] Furthermore, in the preparation of the polyamine-functionalized graphene interface modification liquid, the ultrasonic treatment conditions are: ultrasonication at 350W-450W power for 35min-55min; the heating reaction conditions under nitrogen protection are: heating to 65℃-75℃ and holding the reaction for 2.2h-2.8h; the temperature after cooling is 32℃-38℃; and the stirring time is 35min-55min.

[0010] Furthermore, the raw materials in the polyamine-functionalized graphene interface modification solution are as follows by weight: 1-3 parts graphene oxide, 60-80 parts deionized water, 0.5-1.5 parts polyethyleneimine, 0.5-3 parts γ-glycidyl etheroxypropyltrimethoxysilane, and 0.01-0.03 parts dibutyltin dilaurate.

[0011] Furthermore, the preparation method of the modified corrosion-resistant crosslinking agent is as follows: Triethylenetetramine was added to anhydrous ethanol, and after heating, methyl acrylate was added dropwise. After the addition was complete, the reaction was maintained at the specified temperature. After the reaction was completed, a precursor was obtained. γ-aminopropyltriethoxysilane and toluene were added, and the mixture was heated and refluxed. After the reaction was completed, the mixture was distilled to obtain an intermediate. The intermediate was added to ethyl acetate, glycidyl methacrylate and perfluorooctyl ethyl acrylate were added, and triethanolamine was added. The mixture was heated and reacted to obtain a modified corrosion-resistant crosslinking agent.

[0012] Furthermore, in the preparation of the modified corrosion-resistant crosslinking agent, the heating temperature after adding triethylenetetramine to anhydrous ethanol is 42℃-48℃; the dropping rate of methyl acrylate is 1.2 drops / second-1.8 drops / second, and the dropping time is 35min-40min; the heat preservation reaction conditions are 42℃-48℃ for 2.2h-2.8h; the reflux reaction temperature is 85℃-95℃, and the heat preservation time is 4.5h-5.5h; the distillation conditions are: vacuum degree 0.085MPa-0.09MPa, distillation at 65℃-75℃ for 1.1h-1.4h; and the final heating reaction temperature is 52℃-58℃, and the heat preservation time is 3.2-3.8h.

[0013] Further, the raw materials in the modified corrosion-resistant crosslinking agent are as follows by weight: 10-15 parts triethylenetetramine, 45-60 parts anhydrous ethanol, 20-30 parts methyl acrylate, 25-35 parts γ-aminopropyltriethoxysilane, 30-45 parts toluene, 40-60 parts ethyl acetate, 12-20 parts glycidyl methacrylate, 18-28 parts perfluorooctyl ethyl acrylate, and 0.8-1.5 parts triethanolamine.

[0014] Further, the raw materials in S2 are as follows by weight: 100 parts unsaturated polyester resin, 20-30 parts styrene, 8-15 parts modified corrosion-resistant crosslinking agent, 3-6 parts triisopropylphenyl phosphate, 1-3 parts fumed silica, and 0.5-1.5 parts cobalt isooctanoate.

[0015] Further, the layering process in step S3 is as follows: during layering, a layer of modified and reinforced unsaturated polyester resin obtained in S2 with a thickness of 0.1-0.2 mm is first coated, followed by a layer of polyamine graphene-modified carbon fiber cloth obtained in S1, and then a layer of modified and reinforced unsaturated polyester resin of the same thickness is covered on the surface of the carbon fiber cloth, and a second layer of polyamine graphene-modified carbon fiber cloth is laid to obtain a polyester resin composite material.

[0016] Furthermore, the stepped pressure curing in step S3 is as follows: In the first stage, the temperature is raised to 35℃-42℃, a low-pressure contact pressure of 0.5MPa-1.0MPa is applied, and the temperature is maintained for 0.8h-1.2h; in the second stage, the temperature is raised to 55℃-65℃, the pressure is increased to 4.8MPa-5.2MPa, and the temperature is maintained for 1.5h-2.0h; in the third stage, the temperature is raised to 85℃-95℃, the pressure is maintained at 4.8MPa-5.5MPa, and the temperature is maintained for 0.8h-1.2h before curing. After curing, the system cools naturally to room temperature.

[0017] Further, the post-heat treatment mentioned in step S3 is as follows: the polyester resin composite material after step-pressure curing is heat-treated at 70℃-85℃ for 3.5h-4.5h; The surface sealing treatment in step S3 is as follows: the surface of the heat-treated polyester resin composite material is coated with a modified corrosion-resistant crosslinking agent sealing liquid, and then dried and cured to obtain a corrosion-resistant unsaturated polyester resin composite material.

[0018] Furthermore, in the surface sealing treatment, the modified corrosion-resistant crosslinking agent sealing liquid is prepared by diluting the modified corrosion-resistant crosslinking agent with ethanol to a solid content of 10%-15% to obtain the modified corrosion-resistant crosslinking agent sealing liquid; the coating method is scraping coating, and the coating thickness is 0.06mm-0.09mm; the drying and curing conditions are: heat preservation at 26℃-29℃ for 26h-34h.

[0019] On the other hand, the present invention provides a corrosion-resistant unsaturated polyester resin composite material obtained by the above-mentioned method for preparing corrosion-resistant unsaturated polyester resin composite material.

[0020] The beneficial effects of this invention are: 1. This invention treats carbon fiber cloth with a polyamine-functionalized graphene interface modification liquid, achieving a synergistic effect of the physical barrier effect of graphene oxide, the strong adhesion effect of polyethyleneimine, and the bridging effect of silane coupling agents. This effectively strengthens the interfacial bonding between the carbon fiber cloth and the resin matrix and reduces the generation of interfacial micro-gaps. This synergistic modification constructs a dense interfacial barrier that can prevent corrosive media from penetrating along the interface, while improving the mechanical load-bearing capacity of the composite material, avoiding performance degradation caused by interfacial delamination, and significantly enhancing the integrity and stability of the material structure.

[0021] 2. The customized modified corrosion-resistant crosslinking agent of this invention integrates multiple functional groups such as siloxane, fluoroalkyl, and epoxy groups. When working synergistically with unsaturated polyester resin, it not only significantly increases the crosslinking density of the resin matrix, forming a dense three-dimensional network structure, but also enhances the matrix's acid and alkali resistance and salt spray resistance by leveraging the high chemical inertness of fluorine and the environmental stability of silicon. Simultaneously, the addition of triisopropylphenyl phosphate and fumed silica improves the material's corrosion resistance while also ensuring flame retardancy and rigidity, achieving synergistic optimization of mechanical and corrosion resistance properties, thus solving the problem of traditional materials struggling to meet multiple performance requirements simultaneously.

[0022] 3. This invention forms a comprehensive protective system through a coherent process design involving layer-by-layer composite, stepped pressure curing, post-heat treatment, and surface sealing. Stepped pressure curing gradually promotes the interfacial reaction between the resin and fiber, reducing microcracks and pores generated during molding; post-heat treatment further improves the resin crosslinking network and enhances structural density; surface sealing utilizes a modified corrosion-resistant crosslinking agent to fill surface defects, forming a robust corrosion-resistant protective layer. The entire process works in tandem, comprehensively blocking the intrusion path of corrosive media from internal structure to surface protection, enabling the composite material to maintain excellent performance in complex corrosive environments for extended periods, thus broadening its application scenarios in harsh conditions such as chemical engineering and marine engineering. Detailed Implementation

[0023] The technical solutions in the embodiments of the present invention will be clearly and completely described below. 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 skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] In the examples below, the carbon fiber cloth is 3K 200g plain weave carbon cloth, purchased from Yixing Qianyu Materials Technology Co., Ltd.

[0025] In the following examples, the unsaturated polyester resin is a vinyl unsaturated polyester resin, purchased from Langfang Liqin New Materials Co., Ltd.

[0026] In the examples below, the fumed silica is fumed silica A200, which was purchased from Jinan Zhongbei Fine Chemical Co., Ltd.

[0027] Example 1 A method for preparing a corrosion-resistant unsaturated polyester resin composite material includes the following preparation steps: Preparation of polyamine-functionalized graphene interface modification solution: By weight, take 1 part graphene oxide, 60 parts deionized water, 0.5 parts polyethyleneimine, 0.5 parts γ-glycidyl etheroxypropyltrimethoxysilane, and 0.01 parts dibutyltin dilaurate; disperse the graphene oxide in deionized water and sonicate it at 350W for 35 min to obtain a graphene oxide dispersion; add polyethyleneimine and γ-glycidyl etheroxypropyltrimethoxysilane to the dispersion; under nitrogen protection, heat to 65℃ and keep the temperature for 2.2 h; after the reaction is completed, cool the system to 32℃, add dibutyltin dilaurate, and continue stirring for 35 min; after stirring is completed, the polyamine functionalized graphene interface modified solution is obtained. Preparation of modified corrosion-resistant crosslinking agent: By weight, take 10 parts of triethylenetetramine, 45 parts of anhydrous ethanol, 20 parts of methyl acrylate, 25 parts of γ-aminopropyltriethoxysilane, 30 parts of toluene, 40 parts of ethyl acetate, 12 parts of glycidyl methacrylate, 18 parts of perfluorooctyl ethyl acrylate, and 0.8 parts of triethanolamine. Triethylenetetramine was added to anhydrous ethanol and heated to 42°C. Methyl acrylate was then slowly added dropwise at a rate of 1.2 drops / second over a period of 35 minutes. After the addition was complete, the mixture was kept at 42°C for 2.2 hours. After the reaction was complete, a precursor was obtained. γ-aminopropyltriethoxysilane and toluene were added to the precursor, and the mixture was refluxed at 85°C for 4.5 hours. After the reaction was complete, the mixture was distilled at 65°C under a vacuum of 0.085 MPa for 1.1 hours to obtain an intermediate. This intermediate was added to ethyl acetate, followed by glycidyl methacrylate, perfluorooctyl ethyl acrylate, and triethanolamine. The mixture was heated to 52°C and reacted for 3.2 hours. After the reaction was complete, the modified corrosion-resistant crosslinking agent was obtained. S1: Preparation of polyamine graphene-modified carbon fiber oxide cloth Carbon fibers were arranged in a muffle furnace and air-oxidized at 320℃ for 1.2h to obtain oxidized carbon fiber cloth. The oxidized carbon fiber cloth was immersed in polyamine functionalized graphene interface modification liquid and ultrasonically impregnated at 350W power for 35min. After being removed, it was pre-cured at 85℃ for 1.1h to obtain polyamine graphene modified oxidized carbon fiber cloth. S2: Preparation of Modified Reinforced Unsaturated Polyester Resin By weight, take 100 parts of unsaturated polyester resin, 20 parts of styrene, 8 parts of modified corrosion-resistant crosslinking agent, 3 parts of triisopropylphenyl phosphate, 1 part of fumed silica, and 0.5 parts of cobalt isooctanoate; mix the unsaturated polyester resin and styrene, stir evenly, add the modified corrosion-resistant crosslinking agent, triisopropylphenyl phosphate and fumed silica in sequence, place in a high-speed disperser, disperse at 1000 rpm for 20 min, then degas the mixture under vacuum at -0.095 MPa for 15 min, finally add cobalt isooctanoate, stir evenly, and obtain the modified reinforced unsaturated polyester resin; S3: Lamination and Post-Cure Treatment Layered composite: On a clean mold surface, a layer of modified and reinforced unsaturated polyester resin with a thickness of 0.1 mm is uniformly coated using a scraper. Then, a layer of polyamine graphene modified carbon fiber oxidized cloth is laid on top. A layer of modified and reinforced unsaturated polyester resin of the same thickness (0.1 mm) is then covered on the surface of the carbon fiber cloth, and a second layer of polyamine graphene modified carbon fiber oxidized cloth is laid on top to obtain a polyester resin composite preform. Step-by-step pressure curing: The preform is placed in the hot press mold of a flat vulcanizing machine for step-by-step curing. First stage: Heat to 35℃, apply a contact pressure of 0.5MPa, and hold for 0.8h; Second stage: Heat to 55℃, increase pressure to 4.8MPa, and hold for 1.5 hours; Third stage: Heat to 85℃, maintain pressure at 4.8MPa, and hold for 0.8h; After curing is complete, turn off the heat source and allow the mold to cool naturally to room temperature along with the equipment; Post-heat treatment: The cured and cooled polyester resin composite preform is removed from the mold and placed in a forced-air drying oven for heat treatment at 70°C for 3.5 hours; Surface sealing treatment: The modified corrosion-resistant crosslinking agent was diluted with anhydrous ethanol to a solid content of 10% to prepare a modified corrosion-resistant crosslinking agent sealing liquid. The modified corrosion-resistant crosslinking agent sealing liquid was uniformly coated on all outer surfaces of the heat-treated composite material using a scraping method, with the film thickness controlled at 0.06 mm. The coated material was then placed in an environment of 26°C and cured for 26 hours to finally obtain the corrosion-resistant unsaturated polyester resin composite material.

[0028] Example 2 A method for preparing a corrosion-resistant unsaturated polyester resin composite material includes the following preparation steps: Preparation of polyamine-functionalized graphene interface modification solution: By weight, take 2 parts of graphene oxide, 70 parts of deionized water, 1.0 part of polyethyleneimine, 1.8 parts of γ-glycidyl etheroxypropyltrimethoxysilane, and 0.02 parts of dibutyltin dilaurate. Graphene oxide was dispersed in deionized water and ultrasonically treated at 400W for 45 min to obtain a graphene oxide dispersion. Polyethyleneimine and γ-glycidyl etheroxypropyltrimethoxysilane were added to the dispersion. Under nitrogen protection, the temperature was raised to 70℃ and maintained for 2.5 h. After the reaction was completed, the system was cooled to 35℃, dibutyltin dilaurate was added, and stirring was continued for 45 min. After stirring was completed, the polyamine functionalized graphene interface modified solution was obtained. Preparation of modified corrosion-resistant crosslinking agent: By weight, take 12 parts of triethylenetetramine, 52 parts of anhydrous ethanol, 25 parts of methyl acrylate, 30 parts of γ-aminopropyltriethoxysilane, 38 parts of toluene, 50 parts of ethyl acetate, 16 parts of glycidyl methacrylate, 23 parts of perfluorooctyl ethyl acrylate, and 1.2 parts of triethanolamine. Triethylenetetramine was added to anhydrous ethanol and heated to 45°C. Methyl acrylate was then slowly added dropwise at a rate of 1.5 drops / second over a period of 37 minutes. After the addition was complete, the mixture was kept at 45°C for 2.5 hours. After the reaction was complete, a precursor was obtained. γ-aminopropyltriethoxysilane and toluene were added to the precursor, and the mixture was refluxed at 90°C for 5.0 hours. After the reaction was complete, the mixture was distilled at 70°C under a vacuum of 0.0875 MPa for 1.25 hours to obtain an intermediate. This intermediate was added to ethyl acetate, followed by glycidyl methacrylate, perfluorooctyl ethyl acrylate, and triethanolamine. The mixture was heated to 55°C and reacted for 3.5 hours. After the reaction was complete, the modified corrosion-resistant crosslinking agent was obtained. S1: Preparation of polyamine graphene-modified carbon fiber oxide cloth Carbon fibers were arranged in a muffle furnace and air-oxidized at 350℃ for 1.5h to obtain oxidized carbon fiber cloth. The oxidized carbon fiber cloth was immersed in polyamine functionalized graphene interface modification liquid and ultrasonically impregnated at 400W power for 45min. After being removed, it was pre-cured at 90℃ for 1.25h to obtain polyamine graphene modified oxidized carbon fiber cloth. S2: Preparation of Modified Reinforced Unsaturated Polyester Resin By weight, take 100 parts of unsaturated polyester resin, 25 parts of styrene, 12 parts of modified corrosion-resistant crosslinking agent, 4.5 parts of triisopropylphenyl phosphate, 2 parts of fumed silica, and 1.0 part of cobalt isooctanoate. Unsaturated polyester resin was mixed with styrene and stirred evenly. Modified corrosion-resistant crosslinking agent, triisopropylphenyl phosphate and fumed silica were added in sequence. The mixture was placed in a high-speed disperser and dispersed at 1500 rpm for 30 min. The mixture was then degassed under vacuum at -0.097 MPa for 22 min. Finally, cobalt isooctanoate was added and stirred evenly to obtain the modified reinforced unsaturated polyester resin. S3: Lamination and Post-Cure Treatment Layered composite: On a clean mold surface, a layer of modified and reinforced unsaturated polyester resin with a thickness of 0.15 mm is uniformly coated using a scraper. Then, a layer of polyamine graphene modified carbon fiber oxidized cloth is laid on top. A layer of modified and reinforced unsaturated polyester resin of the same thickness (0.15 mm) is then covered on the surface of the carbon fiber cloth, and a second layer of polyamine graphene modified carbon fiber oxidized cloth is laid on top to obtain a polyester resin composite preform. Step-by-step pressure curing: The preform is placed in the hot press mold of a flat vulcanizing machine for step-by-step curing. First stage: Heat to 38℃, apply a contact pressure of 0.75MPa, and hold for 1.0h; Second stage: Heat to 60℃, increase pressure to 5.0MPa, and hold for 1.75 hours; Third stage: Heat to 90℃, maintain pressure at 5.0MPa, and hold for 1.0h; After curing is complete, turn off the heat source and allow the mold to cool naturally to room temperature along with the equipment; Post-heat treatment: The cured and cooled polyester resin composite preform was removed from the mold and placed in a forced-air drying oven for heat treatment at 78°C for 4.0 h; Surface sealing treatment: The modified corrosion-resistant crosslinking agent was diluted with anhydrous ethanol to a solid content of 12% to prepare a modified corrosion-resistant crosslinking agent sealing liquid. The modified corrosion-resistant crosslinking agent sealing liquid was uniformly coated on all outer surfaces of the heat-treated composite material using a scraping method, with the film thickness controlled at 0.075 mm. The coated material was then placed in an environment of 27°C and cured for 30 h to finally obtain the corrosion-resistant unsaturated polyester resin composite material.

[0029] Example 3 A method for preparing a corrosion-resistant unsaturated polyester resin composite material includes the following preparation steps: Preparation of polyamine-functionalized graphene interface modification solution: By weight, take 3 parts graphene oxide, 80 parts deionized water, 1.5 parts polyethyleneimine, 3 parts γ-glycidyl etheroxypropyltrimethoxysilane, and 0.03 parts dibutyltin dilaurate. Graphene oxide was dispersed in deionized water and ultrasonically treated at 450W for 55 min to obtain a graphene oxide dispersion. Polyethyleneimine and γ-glycidyl etheroxypropyltrimethoxysilane were added to the dispersion. Under nitrogen protection, the temperature was raised to 75℃ and maintained for 2.8 h. After the reaction was completed, the system was cooled to 38℃, dibutyltin dilaurate was added, and stirring was continued for 55 min. After stirring was completed, the polyamine functionalized graphene interface modified solution was obtained. Preparation of modified corrosion-resistant crosslinking agent: By weight, take 15 parts of triethylenetetramine, 60 parts of anhydrous ethanol, 30 parts of methyl acrylate, 35 parts of γ-aminopropyltriethoxysilane, 45 parts of toluene, 60 parts of ethyl acetate, 20 parts of glycidyl methacrylate, 28 parts of perfluorooctyl ethyl acrylate, and 1.5 parts of triethanolamine. Triethylenetetramine was added to anhydrous ethanol and heated to 48°C. Methyl acrylate was then slowly added dropwise at a rate of 1.8 drops / second over a period of 40 minutes. After the addition was complete, the mixture was kept at 48°C for 2.8 hours. After the reaction was complete, a precursor was obtained. γ-aminopropyltriethoxysilane and toluene were added to the precursor, and the mixture was refluxed at 95°C for 5.5 hours. After the reaction was complete, the mixture was distilled at 75°C under a vacuum of 0.09 MPa for 1.4 hours to obtain an intermediate. This intermediate was added to ethyl acetate, followed by glycidyl methacrylate, perfluorooctyl ethyl acrylate, and triethanolamine. The mixture was heated to 58°C and reacted for 3.8 hours. After the reaction was complete, the modified corrosion-resistant crosslinking agent was obtained. S1: Preparation of polyamine graphene-modified carbon fiber oxide cloth Carbon fibers were arranged in a muffle furnace and air-oxidized at 380℃ for 1.8h to obtain oxidized carbon fiber cloth. The oxidized carbon fiber cloth was immersed in polyamine functionalized graphene interface modification liquid and ultrasonically impregnated at 450W power for 55min. After being removed, it was pre-cured at 95℃ for 1.4h to obtain polyamine graphene modified oxidized carbon fiber cloth. S2: Preparation of Modified Reinforced Unsaturated Polyester Resin By weight, take 100 parts of unsaturated polyester resin, 30 parts of styrene, 15 parts of modified corrosion-resistant crosslinking agent, 6 parts of triisopropylphenyl phosphate, 3 parts of fumed silica, and 1.5 parts of cobalt isooctanoate. Unsaturated polyester resin was mixed with styrene and stirred evenly. Modified corrosion-resistant crosslinking agent, triisopropylphenyl phosphate and fumed silica were added in sequence. The mixture was placed in a high-speed disperser and dispersed at 2000 rpm for 40 min. The mixture was then degassed under vacuum at -0.098 MPa for 30 min. Finally, cobalt isooctanoate was added and stirred evenly to obtain the modified reinforced unsaturated polyester resin. S3: Lamination and Post-Cure Treatment Layered composite: On a clean mold surface, a layer of modified and reinforced unsaturated polyester resin with a thickness of 0.2 mm is uniformly coated using a scraper. Then, a layer of polyamine graphene modified carbon fiber oxidized cloth is laid on top. A layer of modified and reinforced unsaturated polyester resin of the same thickness (0.2 mm) is then covered on the surface of the carbon fiber cloth, and a second layer of polyamine graphene modified carbon fiber oxidized cloth is laid on top to obtain a polyester resin composite preform. Step-by-step pressure curing: The preform is placed in the hot press mold of a flat vulcanizing machine for step-by-step curing. First stage: Heat to 42℃, apply a contact pressure of 1.0MPa, and hold for 1.2h; Second stage: Heat to 65℃, increase pressure to 5.2MPa, and hold for 2.0h; Third stage: Heat to 95℃, maintain pressure at 5.2MPa, and hold for 1.2 hours; After curing is complete, turn off the heat source and allow the mold to cool naturally to room temperature along with the equipment; Post-heat treatment: The cured and cooled polyester resin composite preform is removed from the mold and placed in a forced-air drying oven for heat treatment at 85°C for 4.5 hours; Surface sealing treatment: The modified corrosion-resistant crosslinking agent was diluted with anhydrous ethanol to a solid content of 15% to prepare a modified corrosion-resistant crosslinking agent sealing liquid. The modified corrosion-resistant crosslinking agent sealing liquid was uniformly coated on all outer surfaces of the heat-treated composite material using a scraping method, with the film thickness controlled at 0.09 mm. The coated material was then placed in an environment of 29°C and cured for 34 h to finally obtain the corrosion-resistant unsaturated polyester resin composite material.

[0030] Comparative Example 1 Compared with Example 1, this comparative example replaces the "polyamine functionalized graphene interface modification liquid" with an equal mass of "graphene oxide dispersion". All other steps and parameters are the same, and will not be repeated in this comparative example. Finally, a corrosion-resistant unsaturated polyester resin composite material is obtained.

[0031] Comparative Example 2 Compared with Example 1, the "polyamine functionalized graphene interface modification liquid" in this comparative example is replaced with an equal mass of "polyethyleneimine aqueous solution (containing only 0.5 parts of polyethyleneimine and 60 parts of deionized water, polyethyleneimine is dissolved in deionized water to obtain a polyethyleneimine aqueous solution)". All other steps and parameters are the same, and will not be repeated in this comparative example. Finally, a corrosion-resistant unsaturated polyester resin composite material is obtained.

[0032] Comparative Example 3 Compared with Example 1, this comparative example replaces the "modified corrosion-resistant crosslinking agent" with an equal mass of "precursor". All other steps and parameters are the same, and will not be repeated in this comparative example. Finally, a corrosion-resistant unsaturated polyester resin composite material is obtained.

[0033] Comparative Example 4 Compared with Example 1, this comparative example replaces the "modified corrosion-resistant crosslinking agent" with an equal mass of "intermediate". All other steps and parameters are the same, and will not be repeated in this comparative example. Finally, a corrosion-resistant unsaturated polyester resin composite material is obtained.

[0034] Comparative Example 5 Compared with Example 1, this comparative example replaces the "modified corrosion-resistant crosslinking agent sealing liquid" with an equal mass of "anhydrous ethanol". All other steps and parameters are the same, and will not be repeated in this comparative example. Finally, a corrosion-resistant unsaturated polyester resin composite material is obtained.

[0035] The corrosion-resistant unsaturated polyester resin composites prepared in Examples 1-3 and Comparative Examples 1-5 were tested, and the results are recorded in Table 1.

[0036] Test methods for corrosion-resistant unsaturated polyester resin composites: Tensile strength test: Referring to GB / T 1447-2005, standard tensile specimens with a size of 150mm×15mm were prepared from the corrosion-resistant unsaturated polyester resin composite materials prepared in Examples 1-3 and Comparative Examples 1-5. The tensile test was conducted using a universal testing machine with a tensile rate of 2mm / min at room temperature (25±2℃). Five parallel specimens were tested for each sample, and the arithmetic mean of the test results was taken as the final tensile strength.

[0037] Bending strength test: Referring to GB / T 1449-2005, standard bending specimens with a size of 80mm×10mm were prepared from the corrosion-resistant unsaturated polyester resin composite materials prepared in Examples 1-3 and Comparative Examples 1-5. A universal testing machine was used, with a span of 40mm and a loading rate of 2mm / min. Three-point bending tests were conducted at room temperature (25±2℃). Five parallel specimens were tested for each sample, and the arithmetic mean was taken as the final bending strength.

[0038] Salt spray corrosion test: Referring to GB / T 10125-2021, a neutral salt spray test system was adopted. A 5% (w / w) NaCl aqueous solution was prepared, and the test temperature was controlled at 35℃. The corrosion-resistant unsaturated polyester resin composite materials prepared in Examples 1-3 and Comparative Examples 1-5 were used as samples for continuous spraying for 1000 hours. After the test, the samples were taken out, rinsed with deionized water, and air-dried naturally. The surface corrosion morphology was observed, and the corrosion area ratio was calculated using image analysis.

[0039] Acid-base immersion corrosion test: A 5% (w / w) acidic H₂SO₄ solution and a 5% (w / w) alkaline NaOH solution were prepared. The corrosion-resistant unsaturated polyester resin composite materials prepared in Examples 1-3 and Comparative Examples 1-5 were completely immersed in both solutions and statically soaked at room temperature (°C) for 500 hours. After immersion, the samples were removed, the residual solution on the surface was wiped off, and the samples were dried to constant weight. The change in sample mass was measured to calculate the water absorption rate. The formula for the absorption rate is: .

[0040] Table 1. Experimental test data of corrosion-resistant unsaturated polyester resin composite materials According to the data in Table 1, the corrosion-resistant unsaturated polyester resin composite materials prepared in Examples 1-3 have excellent mechanical properties and outstanding corrosion resistance. Moreover, with the optimization and increase of the amount of each raw material (Examples 1→3), the performance shows a gradual improvement trend, which reflects the controllability and superiority of this technical solution.

[0041] Comparing Example 1 with Comparative Example 1, it can be seen that: Comparative Example 1, which only used "graphene oxide dispersion" instead of "polyamine-functionalized graphene interface modification liquid," experienced a decrease in tensile strength and flexural strength of approximately 13.1% and 22.6%, respectively; an increase in salt spray corrosion area ratio of approximately 6 times; and an increase in water absorption rates of approximately 4.7 times and 4.0 times, respectively, after acid and alkali immersion. Data shows that while pure graphene oxide has certain barrier properties, it lacks the strong interfacial adhesion provided by the polyamine groups of polyethyleneimine and the coupling bridging effect of γ-glycidyl etheroxypropyltrimethoxysilane. This results in weak bonding between the fiber and resin interface, allowing corrosive media to easily penetrate along the interface, leading to a significant deterioration in overall performance. This demonstrates the necessity of polyamine and silane synergistic functionalization modification of graphene for constructing strong, tough, and dense interfacial barriers.

[0042] A comparison of Example 1 and Comparative Example 2 shows that Comparative Example 2, treated only with "polyethyleneimine aqueous solution," exhibits similar mechanical properties to Comparative Example 1, but significantly worse corrosion resistance. In particular, its salt spray corrosion area ratio and acid / alkali water absorption rate are the highest among all comparative examples (except for Comparative Example 5, which lacks sealing). Data indicates that while polyethyleneimine alone can improve interfacial wetting and adhesion, it completely lacks the sheet-like physical barrier effect of graphene and the chemical bonding effect of silane. The short diffusion path and rapid penetration of the corrosive medium lead to a sharp decline in the material's environmental corrosion resistance, demonstrating the indispensable synergistic effect of the physical barrier of graphene oxide and the chemical bonding of silane in interfacial modification.

[0043] A comparison of Example 1 and Comparative Example 3 shows that Comparative Example 3, which uses a "precursor" without grafted silane and fluorinated segments instead of a complete "modified corrosion-resistant crosslinking agent," exhibits a comprehensive decrease in mechanical properties and corrosion resistance, although it is slightly better than Comparative Examples 1 and 2. Data indicates that the precursor only possesses a basic amine ester structure, lacking the chemical bonding ability with inorganic fillers and fiber surfaces provided by γ-aminopropyltriethoxysilane, as well as the hydrophobic and oleophobic properties imparted by perfluorooctyl ethyl acrylate and the highly reactive crosslinking points with the resin matrix provided by glycidyl methacrylate. This results in insufficient density of the resin matrix crosslinking network, weak bonding with the reinforcing phase interface, and poor intrinsic chemical resistance, demonstrating the crucial role of multifunctional customized crosslinking agent molecular design in improving the overall performance of the matrix.

[0044] A comparison of Example 1 and Comparative Example 4 shows that Comparative Example 4, which uses an "intermediate" grafted with silane but without introducing fluorinated segments and active double bonds instead of a "modified corrosion-resistant crosslinking agent," exhibits better performance than Comparative Example 3 but significantly worse performance than Example 1. Data explanation: Although the intermediate improves compatibility with the filler through silane, it lacks the low surface energy and high chemical inertness provided by fluorinated segments, as well as the additional crosslinking points provided by glycidyl methacrylate. This results in insufficient resistance to harsh chemical media (especially strong acids and alkalis) and a high water absorption rate, demonstrating the synergistic effect of fluorinated monomers and active epoxy groups in constructing a high crosslinking density and high corrosion-resistant resin network.

[0045] A comparison of Example 1 and Comparative Example 5 shows that Comparative Example 5, which used only anhydrous ethanol instead of the modified corrosion-resistant crosslinking agent sealing liquid for surface treatment in the final step, exhibited mechanical properties similar to Example 1. However, its corrosion resistance, especially the salt spray corrosion area ratio and acid / alkali water absorption rate, showed a catastrophic decrease, being the worst among all samples. Data explanation: The lack of effective surface sealing treatment resulted in the direct exposure of microscopic defects (such as pinholes and microcracks) formed on the surface of the composite material during curing to the corrosive environment, becoming channels for rapid media intrusion. The sealing treatment of this invention utilizes the excellent film-forming properties and reactivity of the modified corrosion-resistant crosslinking agent to form a dense, robust protective layer with high corrosion resistance, fundamentally blocking the corrosion initiation point.

[0046] The above description is merely an example and illustration of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described or use similar methods to replace them, as long as they do not deviate from the inventive concept or exceed the scope defined in the claims, they should all fall within the protection scope of the present invention.

Claims

1. A method for preparing a corrosion-resistant unsaturated polyester resin composite material, characterized in that, The preparation steps include the following: S1: Carbon fiber cloth is oxidized in air in a muffle furnace to obtain oxidized carbon fiber cloth. The oxidized carbon fiber cloth is immersed in polyamine functionalized graphene interface modification liquid for ultrasonic impregnation. After removal, it is pre-cured to obtain polyamine graphene modified oxidized carbon fiber cloth. S2: Mix unsaturated polyester resin and styrene, add modified corrosion-resistant crosslinking agent, add triisopropylphenyl phosphate and fumed silica, disperse at high speed and degas under vacuum, add cobalt isooctanoate, stir evenly to obtain modified and reinforced unsaturated polyester resin. S3: Modified and reinforced unsaturated polyester resin and polyamine graphene modified carbon fiber cloth are laminated to obtain a polyester resin composite material. The polyester resin composite material is then subjected to step-by-step pressure curing, post-heat treatment and surface sealing treatment to prepare a corrosion-resistant unsaturated polyester resin composite material.

2. The method for preparing a corrosion-resistant unsaturated polyester resin composite material according to claim 1, characterized in that, The preparation method of the polyamine-functionalized graphene interface-modified liquid is as follows: Graphene oxide was dispersed in deionized water and sonicated to obtain a graphene oxide dispersion. Polyethyleneimine and γ-glycidyl etheroxypropyltrimethoxysilane were added, and the mixture was heated under nitrogen protection. After the reaction was completed, the temperature was lowered, dibutyltin dilaurate was added, and stirring was continued. After stirring was completed, a polyamine-functionalized graphene interface-modified solution was obtained.

3. The method for preparing a corrosion-resistant unsaturated polyester resin composite material according to claim 2, characterized in that, The raw materials in the polyamine-functionalized graphene interface modification solution are as follows by weight: 1-3 parts graphene oxide, 60-80 parts deionized water, 0.5-1.5 parts polyethyleneimine, 0.5-3 parts γ-glycidyl etheroxypropyltrimethoxysilane, and 0.01-0.03 parts dibutyltin dilaurate.

4. The method for preparing a corrosion-resistant unsaturated polyester resin composite material according to claim 1, characterized in that, The modified corrosion-resistant crosslinking agent is prepared as follows: Triethylenetetramine was added to anhydrous ethanol, and after heating, methyl acrylate was added dropwise. After the addition was complete, the reaction was maintained at the specified temperature. After the reaction was completed, a precursor was obtained. γ-aminopropyltriethoxysilane and toluene were added, and the mixture was heated and refluxed. After the reaction was completed, the mixture was distilled to obtain an intermediate. The intermediate was added to ethyl acetate, glycidyl methacrylate and perfluorooctyl ethyl acrylate were added, and triethanolamine was added. The mixture was heated and reacted to obtain a modified corrosion-resistant crosslinking agent.

5. The method for preparing a corrosion-resistant unsaturated polyester resin composite material according to claim 4, characterized in that, The modified corrosion-resistant crosslinking agent comprises the following raw materials in parts by weight: 10-15 parts triethylenetetramine, 45-60 parts anhydrous ethanol, 20-30 parts methyl acrylate, 25-35 parts γ-aminopropyltriethoxysilane, 30-45 parts toluene, 40-60 parts ethyl acetate, 12-20 parts glycidyl methacrylate, 18-28 parts perfluorooctyl ethyl acrylate, and 0.8-1.5 parts triethanolamine.

6. The method for preparing a corrosion-resistant unsaturated polyester resin composite material according to claim 1, characterized in that, The raw materials in S2 are as follows by weight: 100 parts unsaturated polyester resin, 20-30 parts styrene, 8-15 parts modified corrosion-resistant crosslinking agent, 3-6 parts triisopropylphenyl phosphate, 1-3 parts fumed silica, and 0.5-1.5 parts cobalt isooctanoate.

7. The method for preparing a corrosion-resistant unsaturated polyester resin composite material according to claim 1, characterized in that, In step S3, the layering process is as follows: First, a layer of modified and reinforced unsaturated polyester resin obtained from S2 with a thickness of 0.1-0.2 mm is coated. Then, a layer of polyamine graphene-modified carbon fiber cloth obtained from S1 is laid. Next, a layer of modified and reinforced unsaturated polyester resin of the same thickness is covered on the surface of the carbon fiber cloth, and a second layer of polyamine graphene-modified carbon fiber cloth is laid to obtain a polyester resin composite material.

8. The method for preparing a corrosion-resistant unsaturated polyester resin composite material according to claim 1, characterized in that, The stepped pressure curing in step S3 is as follows: In the first stage, the temperature is raised to 35℃-42℃, a low contact pressure of 0.5MPa-1.0MPa is applied, and the temperature is maintained for 0.8h-1.2h; in the second stage, the temperature is raised to 55℃-65℃, the pressure is increased to 4.8MPa-5.2MPa, and the temperature is maintained for 1.5h-2.0h; in the third stage, the temperature is raised to 85℃-95℃, the pressure is maintained at 4.8MPa-5.5MPa, and the temperature is maintained for 0.8h-1.2h before curing. After curing, the system cools naturally to room temperature.

9. The method for preparing a corrosion-resistant unsaturated polyester resin composite material according to claim 1, characterized in that, The post-heat treatment mentioned in step S3 is as follows: heat-treating the polyester resin composite material after step-pressure curing at 70℃-85℃ for 3.5h-4.5h. The surface sealing treatment in step S3 is as follows: the surface of the heat-treated polyester resin composite material is coated with a modified corrosion-resistant crosslinking agent sealing liquid, and then dried and cured to obtain a corrosion-resistant unsaturated polyester resin composite material.

10. A corrosion-resistant unsaturated polyester resin composite material prepared by the method of any one of claims 1-9.

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