A heavy-duty anti-corrosion powder coating based on waste polyester fiber and its preparation method

Abstract

The present invention discloses a preparation method of a heavy-duty anti-corrosion powder coating based on waste polyester fibers, which comprises the following steps: S1 Classify and process the waste polyester fibers, and then add them to a pretreatment solution for partial alcoholysis reaction to obtain a short-cut polyester fiber alcoholysis product; S2 Grind it into a powder form, and then add it to a modifier containing an isocyanate group compound for a multifunctional graft modification reaction of disulfide bonds and trimethoxysilane functional groups to obtain a modified polyester fiber powder; S3 Compound and mix it with E51 epoxy resin, E20 epoxy resin, composite filler, curing agent and additives to obtain a heavy-duty anti-corrosion powder coating. The preparation method of the heavy-duty anti-corrosion powder coating of the present invention not only realizes the high-value utilization of waste polyester fibers, but also significantly improves the anti-corrosion performance and mechanical properties of the coating through innovative modification, ensuring the long-term durability and environmental adaptability of the coating, and meeting the anti-corrosion requirements in harsh environments such as chemical industry and ocean.

Description

Technical Field

[0001] The present invention relates to the technical field of anticorrosive coatings, and particularly to a heavy-duty anticorrosive powder coating based on waste polyester fibers and a preparation method thereof. Background Art

[0002] As an important protective material in the industrial field, anticorrosive coatings are widely used in multiple industries such as chemical engineering, marine, and infrastructure to protect metal structures from corrosion. Traditional anticorrosive coatings mostly use solvent-based coatings. However, with the increasing awareness of environmental protection and the strictness of regulations, solvent-based coatings are gradually restricted due to the problem of volatile organic compound (VOC) emissions. Therefore, the development of environmentally friendly and high-performance anticorrosive coatings has become a research hotspot.

[0003] As an environmentally friendly coating, powder coatings are favored for their advantages such as solvent-free, low VOC emissions, and high utilization rate. However, the existing powder coatings still have limitations in anticorrosive performance. Especially under harsh chemical and environmental conditions, such as chemical facilities and offshore platforms, their durability and stability still need to be improved. In addition, the raw materials of powder coatings usually come from petrochemical products, with high costs, and their impact on the environment cannot be ignored.

[0004] As a renewable resource, the recycling of waste polyester fibers has made certain progress in fields such as textiles and packaging. However, in the field of coatings, especially in the preparation of heavy-duty anticorrosive powder coatings, the high-value application of waste polyester fibers has not been fully developed. In the existing technology, the recycling of waste polyester fibers mostly uses physical methods such as mechanical crushing and melt regeneration, and these methods are difficult to achieve the high-performance application of waste polyester fibers in coatings. Therefore, exploring the application of waste polyester fibers in heavy-duty anticorrosive powder coatings can not only realize the recycling of resources but also improve the environmental performance and application scope of coatings, which has important practical significance and market prospects. Summary of the Invention

[0005] In view of the above deficiencies of the prior art, the present invention provides a preparation method of a heavy-duty anticorrosive powder coating based on waste polyester fibers to solve the technical problems in the prior art that waste polyester fibers are difficult to be effectively recycled, the performance of heavy-duty anticorrosive powder coatings is insufficient, and it is difficult to meet the long-term durability and stability requirements under harsh environments such as chemical engineering, marine, and infrastructure. Through the preparation method of the present invention, not only the high-value conversion of waste polyester fibers is realized, but also the prepared heavy-duty anticorrosive powder coating has excellent anticorrosive performance and environmental adaptability, while ensuring the long-term durability and stability of the coating, meeting the application requirements under harsh chemical and environmental conditions.

[0006] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0007] A preparation method of a heavy-duty anti-corrosion powder coating based on waste polyester fiber, the preparation method comprising the following steps:

[0008] S1: After sorting waste polyester fiber with a PET content greater than 70% by color, it is ultrasonically cleaned, dried, crushed, and then added to a pretreatment solution for partial alcoholysis reaction to obtain a short-cut polyester fiber alcoholysis product;

[0009] S2: Grind the short-cut polyester fiber alcoholysis product obtained in step S1 into a powder, and then add it to a modifier containing an isocyanate group compound for a multi-functional graft modification reaction of disulfide bonds and trimethoxysilane functional groups to obtain a modified polyester fiber powder. In step S2 of the present application, by pulverizing the short-cut polyester fiber alcoholysis product, the specific surface area of the material is significantly increased, thereby enhancing its dispersibility in the coating formulation and providing a more active surface for subsequent chemical modification. The pulverized polyester fiber reacts with the modifier containing an isocyanate group compound, realizing the introduction of disulfide bonds and trimethoxysilane functional groups. These modifications not only enhance the compatibility between the fiber and the resin matrix, but also significantly improve the mechanical properties and chemical stability of the coating. The introduction of disulfide bonds provides the coating with self-healing ability, while the trimethoxysilane functional groups further improve the chemical resistance and temperature resistance of the coating through cross-linking reaction with epoxy resin. In addition, the modified coating exhibits better thermal stability, wear resistance and scratch resistance. At the same time, the enhanced adhesion ensures the application stability of the coating on different substrates. Generally speaking, the technical effect of step S2 brings excellent comprehensive performance to the prepared heavy-duty anti-corrosion powder coating, meeting the anti-corrosion requirements for long-term durability under harsh chemical and environmental conditions.

[0010] S3: Mix the modified polyester fiber powder obtained in step S2 with E51 epoxy resin, E20 epoxy resin, composite filler, curing agent and additives, and after melt extrusion, pressing, air cooling, grinding and screening, the heavy-duty anti-corrosion powder coating is obtained.

[0011] As a preferred technical solution, the pretreatment solution is a mixed solution of zinc acetate and alcohol compounds.

[0012] As a preferred technical solution, in step S1, the reaction conditions of the alcoholysis reaction are: the reaction time is 0.5 - 1 h, and the reaction temperature is controlled at 60 - 80 °C.

[0013] As a preferred technical solution, in step S2, after the short-cut polyester fiber alcoholysis product is ground into a powder, the obtained fineness is 30 - 70 mesh.

[0014] As a preferred technical solution, the modifier is a mixture of a reaction product of dithioglycol and a diisocyanate and 3-isocyanatopropyltrimethoxysilane.

[0015] As a preferred technical solution, the dithioglycol is at least one of ethylene-2,2'-bis(dithio)di(ethanol), 2,2'-(1,3-propanediyldithio)diethanol, 2,2'-dithiobis-ethanol, 4,4'-dithiobutan-1-ol.

[0016] As a preferred technical solution, the diisocyanate is at least one of hexamethylene diisocyanate, isophorone diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate.

[0017] As a preferred technical solution, the composite filler is a mixture of mica powder, quartz powder and talc powder, wherein the dosage of mica powder is 20-30% of the total filler mass, the dosage of quartz powder is 40-50% of the total filler mass, and the dosage of talc powder is 20-30% of the total filler mass.

[0018] As a preferred technical solution, the curing agent is at least one of ethylenediamine, diethylenetriamine, triethylenetetramine.

[0019] As a preferred technical solution, the auxiliary agent is at least one of a leveling agent, a dispersant, an anti-settling agent, an anti-ultraviolet agent.

[0020] Another aspect of the present invention is to provide a heavy-duty anti-corrosion powder coating based on waste polyester fibers, and the heavy-duty anti-corrosion powder coating is prepared by the preparation method of the heavy-duty anti-corrosion powder coating based on waste polyester fibers as described above.

[0021] Advantages of the present invention:

[0022] The preparation method of the heavy-duty anti-corrosion powder coating of the present invention effectively converts waste polyester fibers into high-value anti-corrosion coatings, achieving the dual goals of resource recycling and environmental protection. Through this innovative process, the coating not only exhibits excellent anti-corrosion performance but also has other significant advantages.

[0023] The preparation method of the heavy-duty anti-corrosion powder coating based on waste polyester fiber of the present invention turns waste into treasure. By recycling waste polyester fiber, there is no need to additionally add pigments, and at the same time, the powder coating has excellent anti-corrosion performance. Specifically, by innovatively introducing a modifier containing isocyanate group compounds, multifunctional graft modification of disulfide bonds and trimethoxysilane functional groups is carried out, so that the powder coating has excellent mechanical properties and chemical medium corrosion resistance. Further compounding with E51 epoxy resin, E20 epoxy resin, composite filler, etc., not only enhances the cohesion and adhesion of the coating, but also significantly improves the heat resistance, weather resistance and long-term stability of the coating.

[0024] Generally speaking, the heavy-duty anti-corrosion powder coating based on waste polyester fiber prepared by the present invention has strong overall comprehensive performance. It not only has excellent anti-corrosion performance and environmental adaptability, but also ensures the long-term durability and stability of the coating, and can meet the long-term durability and stability requirements in harsh environments such as chemical industry, ocean, and infrastructure. Specific embodiments

[0025] The following description is used to disclose the present invention so that those skilled in the art can implement the present invention. The preferred embodiments in the following description are only examples, and those skilled in the art can think of other obvious variants.

[0026] Example 1

[0027] The preparation method of the heavy-duty anti-corrosion powder coating based on waste polyester fiber in this example includes the following steps:

[0028] S1: After sorting waste polyester fiber with PET content greater than 70% by color, it is ultrasonically cleaned, dried and then crushed, and then added to the pretreatment solution for partial alcoholysis reaction to obtain a short-cut polyester fiber alcoholysis product. The waste polyester fiber accounts for 15% of the total mass of the pretreatment solution, and the pretreatment solution is a mixed solution of zinc acetate and ethylene glycol with a mass ratio of 1:20. The reaction conditions of the alcoholysis reaction are: the reaction time is 0.5 h, and the reaction temperature is controlled at 60 °C.

[0029] S2: Grind 30 g of the short-cut polyester fiber alcoholysis product obtained in step S1 into a powder form with a fineness of 40 mesh, disperse it into 100 mL of toluene solvent, and then, under the protection of an inert atmosphere of nitrogen, add 5 g of a modifier containing an isocyanate group compound for a multi-functional graft modification reaction of disulfide bonds and trimethoxysilane functional groups. React at a constant water bath temperature of 50 °C for 2 h to obtain modified polyester fiber powder. The modifier is a mixture of the reaction product of 2,2'-dithiobisethanol and isophorone diisocyanate and 3-isocyanatopropyltrimethoxysilane. The reaction product is obtained by the reaction of an excessive amount of isophorone diisocyanate. Specifically, the molar ratio of 2,2'-dithiobisethanol to isophorone diisocyanate in the reaction is 1:2, and the end group of the obtained reaction product is an isocyanate group. Further, the molar ratio of the reaction product to 3-isocyanatopropyltrimethoxysilane is 3:2.

[0030] S3: By weight, mix 20 parts of the modified polyester fiber powder obtained in step S2 with 25 parts of E51 epoxy resin, 15 parts of E20 epoxy resin, 10 parts of composite filler, 4 parts of ethylenediamine, and 1 part of an auxiliary agent. After melt extrusion, tablet pressing, air cooling, grinding, and screening treatments, the heavy-duty anti-corrosion powder coating is obtained. The composite filler is a mixture of mica powder, quartz powder, and talc powder, wherein the dosage of mica powder is 20% of the total filler mass, the dosage of quartz powder is 50% of the total filler mass, and the dosage of talc powder is 30% of the total filler mass. The curing agent is ethylenediamine. The auxiliary agent is composed of a leveling agent BYK-333, a dispersant Hydropalat 3204, an anti-settling agent organobentonite, and an anti-ultraviolet agent Tinuvin 328 with a mass ratio of 5:15:3:3.

[0031] Example 2

[0032] The preparation method of the heavy-duty anti-corrosion powder coating based on waste polyester fibers in this example includes the following steps:

[0033] S1: After sorting the waste polyester fibers with a PET content greater than 70% by color, perform ultrasonic cleaning, drying, and then crushing treatment, and then add them to a pretreatment solution for a partial alcoholysis reaction to obtain a short-cut polyester fiber alcoholysis product. The waste polyester fibers account for 15% of the total mass of the pretreatment solution, and the pretreatment solution is a mixed solution of zinc acetate and ethylene glycol with a mass ratio of 1:20. The reaction conditions for the alcoholysis reaction are: the reaction time is 1 h, and the reaction temperature is controlled at 70 °C.

[0034] S2: Grind 30 g of the short-cut polyester fiber alcoholysis product obtained in step S1 into a powder form with a fineness of 50 mesh, disperse it into 100 mL of toluene solvent, and then, under the protection of an inert atmosphere of nitrogen, add 5 g of a modifier containing an isocyanate group compound for a multi-functional graft modification reaction of disulfide bonds and trimethoxysilane functional groups. React at a constant water bath temperature of 50 °C for 2 h to obtain modified polyester fiber powder. The modifier is a mixture of the reaction product of ethylene-2,2'-bis(dithio)di(ethanol) and hexamethylene diisocyanate and 3-isocyanatopropyltrimethoxysilane. The reaction product is obtained by the reaction of excessive hexamethylene diisocyanate. Specifically, the molar ratio of ethylene-2,2'-bis(dithio)di(ethanol) to hexamethylene diisocyanate in the reaction is 1:1, and the end group of the obtained reaction product is an isocyanate group. Further, the molar ratio of the reaction product to 3-isocyanatopropyltrimethoxysilane is 3:2.

[0035] S3: By weight, mix 25 parts of the modified polyester fiber powder obtained in step S2 with 20 parts of E51 epoxy resin, 20 parts of E20 epoxy resin, 12 parts of composite filler, 5 parts of diethylenetriamine, and 1.5 parts of additives. After melt extrusion, tablet pressing, air cooling, grinding, and screening treatments, the heavy-duty anti-corrosion powder coating is obtained. The composite filler is a mixture of mica powder, quartz powder, and talc powder, wherein the dosage of mica powder is 30% of the total filler mass, the dosage of quartz powder is 45% of the total filler mass, and the dosage of talc powder is 25% of the total filler mass. The curing agent is ethylenediamine. The additives are composed of a leveling agent BYK-333, a dispersant Hydropalat 3204, an anti-settling agent organic bentonite, and an anti-ultraviolet agent Tinuvin 328 with a mass ratio of 6:12:3:2.

[0036] Example 3

[0037] The preparation method of the heavy-duty anti-corrosion powder coating based on waste polyester fiber in this example includes the following steps:

[0038] S1: After sorting waste polyester fiber with a PET content greater than 70% by color, perform ultrasonic cleaning, drying, and then crushing treatment, and then add it to a pretreatment solution for partial alcoholysis reaction to obtain a short-cut polyester fiber alcoholysis product. The waste polyester fiber accounts for 15% of the total mass of the pretreatment solution, and the pretreatment solution is a mixed solution of zinc acetate and ethylene glycol with a mass ratio of 1:20. The reaction conditions for the alcoholysis reaction are: the reaction time is 1 h, and the reaction temperature is controlled at 60 °C.

[0039] S2: Grind 30 g of the short-cut polyester fiber alcoholysis product obtained in step S1 into powder form with a fineness of 60 mesh, disperse it into 100 mL of toluene solvent, and then, under the protection of an inert atmosphere of nitrogen, add 5 g of a modifier containing an isocyanate group compound for a multifunctional graft modification reaction of disulfide bonds and trimethoxysilane functional groups. React at a constant water bath temperature of 50 °C for 2 h to obtain modified polyester fiber powder. The modifier is a mixture of the reaction product of 2,2'-(1,3-propanediyldithio)diethanol and 2,4-toluene diisocyanate and 3-isocyanatopropyltrimethoxysilane. The reaction product is obtained by the reaction of excessive 2,4-toluene diisocyanate. Specifically, the molar ratio of 2,2'-(1,3-propanediyldithio)diethanol to 2,4-toluene diisocyanate in the reaction is 1:2, and the end group of the obtained reaction product is an isocyanate group. Further, the molar ratio of the reaction product to 3-isocyanatopropyltrimethoxysilane is 2:3.

[0040] S3: By weight, mix 30 parts of the modified polyester fiber powder obtained in step S2 with 15 parts of E51 epoxy resin, 25 parts of E20 epoxy resin, 15 parts of composite filler, 6 parts of triethylenetetramine, and 2 parts of additives, and after melt extrusion, tablet pressing, air cooling, grinding, and sieving treatments, obtain the heavy-duty anti-corrosion powder coating. The composite filler is a mixture of mica powder, quartz powder, and talc powder, where the dosage of mica powder is 25% of the total filler mass, the dosage of quartz powder is 50% of the total filler mass, and the dosage of talc powder is 25% of the total filler mass. The curing agent is ethylenediamine. The additives are composed of a leveling agent BYK-333, a dispersant Hydropalat 3204, an anti-settling agent organobentonite, and an anti-ultraviolet agent Tinuvin 328 with a mass ratio of 7:13:4:3.

[0041] Comparative Example 1

[0042] The preparation method of the heavy-duty anti-corrosion powder coating based on waste polyester fiber in this comparative example is basically the same as that in Example 1 in terms of raw material composition and preparation steps. The difference is that in the preparation method of this comparative example, the modifier is only the reaction product of 2,2'-dithiobis-ethanol and isophorone diisocyanate.

[0043] Comparative Example 2

[0044] The preparation method of the heavy-duty anti-corrosion powder coating based on waste polyester fiber in this comparative example is basically the same as that in Example 1 in terms of raw material composition and preparation steps. The difference is that in the preparation method of this comparative example, the modifier is only 3-isocyanatopropyltrimethoxysilane.

[0045] The heavy-duty anti-corrosion powder coatings prepared in Examples 1 to 3 and Comparative Examples 1 to 2 were subjected to performance tests, and the performance results are shown in Table 1: Specifically, the powder coating samples were sprayed on the test steel by an electrostatic spraying process.

[0046] Among them, the cathodic disbonding resistance: It was carried out with reference to SY / T 0413-2002. The test was carried out under high-temperature conditions of 65 °C for 48 consecutive hours. During the test, the metal substrate of the coating would be connected to a cathodic protection system to simulate the cathodic protection environment in actual use; by applying current, the metal substrate became the cathode, and the coating was exposed to the electrochemical reaction caused by cathodic protection. The adhesion and anti-corrosion performance of the coating under cathodic protection conditions were evaluated by the degree of coating peeling.

[0047] Impact strength: It was tested with reference to the national standard GB / T 1732. The sample was tested under an impact energy of 5 joules.

[0048] Hardness: It was tested with reference to the national standard GB / T 6739.

[0049] Salt spray resistance: It was tested in a salt spray chamber with reference to the national standard GB / T 1771. The test temperature was set at 35 °C, 5% salt solution, and the test duration was 1000 hours, and it was evaluated according to the degree of corrosion.

[0050] Weather resistance: It was tested by xenon lamp exposure with reference to ISO 11507. The test light intensity was set at 0.75 W / m 2 (340 nm) ultraviolet B band, the experimental temperature was 50 °C, and the test time was 1000 h, and it was evaluated according to the degree of corrosion.

[0051] Damp heat resistance: It was tested with reference to the national standard GB / T 1740. The test conditions were set at 50 °C, 95% relative humidity, and the duration was 1000 hours, and it was evaluated according to the degree of corrosion.

[0052] Table 1

[0053]

[0054]

[0055] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art of this industry should understand that the present invention is not limited by the above embodiments. What is described in the above embodiments and the specification is only the principle of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed.

Claims

1. A method for preparing a heavy-duty anticorrosive powder coating based on waste polyester fibers, characterized in that: The preparation method comprises the following steps: S1: sorting the waste polyester fibers with a PET content greater than 70% by color, performing ultrasonic cleaning, drying, crushing, and then adding them to a pretreatment solution for partial alcoholysis reaction to obtain alcoholysis products of short-cut polyester fibers; the pretreatment solution is a mixed solution of zinc acetate and an alcohol compound; S2: grinding the short-cut polyester fiber alcoholysis product obtained in step S1 into powder, and then adding it to a modifier containing an isocyanate compound to carry out a multifunctional grafting modification reaction of disulfide bonds and trimethoxysilane functional groups to obtain modified polyester fiber powder; the modifier is a mixture of a reaction product of 2,2'-dithiodiethanol and isophorone diisocyanate and 3-isocyanatepropyltrimethoxysilane in a molar ratio of 1:2, or the modifier is a mixture of a reaction product of 2,2'-(1,3-propanediyldisulfanediyl)diethanol and 2,4-toluene diisocyanate and 3-isocyanatepropyltrimethoxysilane in a molar ratio of 1:2; S3: The modified polyester fiber powder obtained in step S2 is mixed with E51 epoxy resin, E20 epoxy resin, composite filler, curing agent and auxiliary agent, and the heavy-duty anti-corrosion powder coating is obtained through melt extrusion, tableting, air cooling, grinding and screening.

2. The method for preparing a heavy-duty anticorrosive powder coating based on waste polyester fibers as claimed in claim 1, characterized in that: In step S1, the reaction conditions of the alcoholysis reaction are: the reaction time is 0.5 to 1 h, and the reaction temperature is controlled at 60 to 80°C.

3. The method for preparing a heavy-duty anticorrosive powder coating based on waste polyester fibers as claimed in claim 1, characterized in that: In step S2, the alcoholysis product of the short-cut polyester fiber is ground into powder to obtain a fineness of 30 to 70 meshes.

4. The method for preparing a heavy-duty anticorrosive powder coating based on waste polyester fibers as claimed in claim 1, characterized in that: The composite filler is a mixture of mica powder, quartz powder and talcum powder, wherein the amount of mica powder is 20-30% of the total filler mass, the amount of quartz powder is 40-50% of the total filler mass, and the amount of talcum powder is 20-30% of the total filler mass.

5. The method for preparing a heavy-duty anticorrosive powder coating based on waste polyester fibers as claimed in claim 1, characterized in that: The curing agent is at least one of ethylenediamine, diethylenetriamine and triethylenetetramine.

6. A heavy-duty anticorrosive powder coating based on waste polyester fibers, characterized in that: The heavy-duty anti-corrosion powder coating is prepared by the method for preparing a heavy-duty anti-corrosion powder coating based on waste polyester fibers as described in any one of claims 1 to 5.

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