Antifouling slow-release tablet, preparation method and application

Abstract

The application provides an antifouling slow-release tablet, a preparation method and application. The antifouling slow-release tablet comprises 3-6 parts of a temperature-sensitive polymer, 2-4 parts of a water-soluble resin, 12-22 parts of a hydratable slow-release resin and 55-70 parts of an antifouling functional filler. The antifouling slow-release tablet can realize controllable release of the antifouling agent in a seawater environment with temperature alternation, especially in seawater with high temperature and normal temperature alternation, thereby effectively improving the service life while ensuring the antifouling effect.

Description

Technical Field

[0001] This invention relates to the field of antifouling technology, and more specifically, to an antifouling slow-release tablet, its preparation method, and its application. Background Technology

[0002] During the development and utilization of the ocean, marine biofouling poses a significant threat to ships, such as increased drag, weight, fuel consumption, accelerated corrosion, and frequent dry-docking repairs. Waste heat exchangers are crucial heat exchange devices in marine equipment, primarily used for waste heat discharge or emergency heat dissipation. Their operating environment is a seawater environment with fluctuating temperatures: if the highest seawater temperature inside the chamber reaches above 60°C during heat exchange, most fouling organisms cannot survive, demonstrating the device's excellent anti-fouling capabilities; however, if the chamber is at room temperature after heat exchange is suspended, fouling organisms easily attach to and grow on the heat exchange tubes. As these organisms continue to grow and accumulate inside the device, their heat exchange efficiency and lifespan are severely reduced.

[0003] Currently, relevant antifouling measures include antifouling coatings, heat transfer protective coatings, electrolytic chlorination, and electrolytic copper antifouling technologies. Antifouling methods using coatings reduce heat exchanger efficiency, with temperature delays exceeding 5°C, making them unsuitable for heat exchanger antifouling designs. Electrolytic chlorination and electrolytic copper antifouling technologies generate hydrogen gas, which can easily cause hydrogen embrittlement in titanium alloy substrates, posing a significant threat to the lifespan and operational safety of the equipment.

[0004] In view of this, the present invention is hereby proposed. Summary of the Invention

[0005] The problem solved by this invention is that the heat exchange efficiency of existing marine heat exchange equipment is severely affected after fouling organisms adhere to it.

[0006] The present invention provides an antifouling slow-release tablet comprising 3-6 parts of a thermosensitive polymer, 2-4 parts of a water-soluble resin, 12-22 parts of a hydrated slow-release resin, and 55-70 parts of an antifouling functional filler.

[0007] Thermosensitive polymers are polymers with low critical dissolution temperatures. Specifically, when the temperature is below the phase transition temperature, the polymer is soluble in water to form a free-flowing liquid. When the temperature rises above the phase transition temperature, the aqueous solution of the polymer undergoes a phase transition, forming a non-chemically cross-linked gel. The gel formation process is reversible, and the gel solution can transform back to its original state when the temperature decreases. The low critical dissolution temperature can be adjusted by controlling the ratio of different chain segments in the polymer. By introducing thermosensitive polymers with different low critical dissolution temperatures into antifouling slow-release tablets, the release rate of the antifouling agent in temperature-changing environments can be better achieved, thus extending the service life of the antifouling slow-release tablets.

[0008] Preferably, the temperature-sensitive polymer is selected from at least one of poly(glycolic acid) lactide, poly(hexyl lactide-polyethylene glycol-poly(glycolic acid) lactide), and poly(hexyl lactide-polyethylene glycol-poly(glycolic acid) lactide. Preferably, the temperature-sensitive polymer is composed of poly(glycolic acid) lactide and poly(hexyl lactide-polyethylene glycol-poly(glycolic acid) lactide in a ratio of 1:0.5-2, and the poly(glycolic acid) lactide and poly(hexyl lactide-polyethylene glycol-poly(glycolic acid) lactide are purchased from Guangzhou Carbon Water Technology Co., Ltd.

[0009] Preferably, the water-soluble resin is selected from one or more substances selected from the group consisting of polyvinyl alcohol, polyvinylpyrrolidone, polyacrylic acid, polyethyleneimine, polyethylene oxide, polyvinylamine, polyallylamine and their derivatives.

[0010] Preferably, the water-soluble resin is either polyvinyl alcohol 1792 or polyvinyl alcohol 1788.

[0011] Preferably, the hydrated slow-release resin is selected from at least one of zinc acrylate resin, silicone acrylate resin, and acrylate resin.

[0012] Preferably, the antifouling filler comprises 35-40 parts cuprous oxide, 10-15 parts zinc oxide, and 10-15 parts organic antifouling agent.

[0013] Preferably, the organic antifouling agent is any one or more of bromopyrrolidone, copper pyridinethione, zinc pyridinethione, zineb, and isothiazolinone. Preferably, the organic antifouling agent comprises 2-5 parts copper pyridinethione, 3-5 parts zineb, and 3-4 parts isothiazolinone. Preferably, the organic antifouling agent further comprises 1-3 parts bromopyrrolidone.

[0014] This invention also provides a method for preparing antifouling sustained-release tablets, comprising:

[0015] S1. Weigh out the resin base and antifouling filler according to the specified amount, add the antifouling filler to the resin, and mix them using a high-speed disperser to prepare a slurry.

[0016] S2. Cut the fiber cotton according to the mold structure size of the antifouling slow-release tablet, soak it in slurry for 48-72 hours, and then transfer the fiber cotton into the mold. The bottom of the mold is pre-placed with a polytetrafluoroethylene film as a substrate.

[0017] S3. Place it in an oven at 38-45℃ and bake for 48-72 hours. After drying, remove the polytetrafluoroethylene film at the bottom to form a dirt-resistant slow-release tablet.

[0018] Preferably, the length, width, and height of the fiber cotton are 80-150mm, 50-100mm, and 5-15mm, respectively.

[0019] The above-mentioned antifouling slow-release tablets are used in marine equipment, specifically titanium alloy heat exchangers.

[0020] Compared with the prior art, the antifouling slow-release tablet and its preparation method of the present invention have the following beneficial effects: As the temperature of the seawater in the waste heat exchanger cavity changes, when the temperature is low, the temperature-sensitive polymer remains in a swollen state, the water absorption of the water-soluble resin remains at a low level, and the antifouling agent in the antifouling slow-release tablet leachates out stably; when the temperature increases, the temperature-sensitive polymer transforms into a shrinking state, the water absorption rate decreases, and the leachation rate of the antifouling agent in the antifouling slow-release tablet decreases, achieving controlled release of the antifouling agent and extending the service life of the antifouling slow-release tablet. Attached Figure Description

[0021] Figure 1 This is a graph showing the change in antifouling agent concentration over time in the test examples of this invention;

[0022] Figure 2 The image shows the appearance of the antifouling sustained-release tablets prepared in Example 1 after immersion in artificial seawater at 60°C;

[0023] Figure 3 The image shows the appearance of the antifouling slow-release tablets in Comparative Example 1 after immersion in artificial seawater at 60°C. Detailed Implementation

[0024] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be noted that the technical features in the various embodiments of the present invention can be combined with each other.

[0025] Waste heat exchangers are crucial heat exchange devices in marine equipment, primarily used for waste heat discharge or emergency heat removal. However, once marine fouling organisms adhere to the surface of the heat exchanger, its heat exchange efficiency will decrease. While titanium alloys are widely used as the design base material in new waste heat exchangers due to their excellent corrosion resistance, titanium alloys also have a natural biocompatibility, making it easier for marine organisms to adhere to their surface. This can seriously affect the safety of equipment operation.

[0026] To ensure the surface heat transfer efficiency of heat exchangers, typical antifouling measures mainly include electrolytic chlorine production and electrolytic copper antifouling technologies. However, existing technologies all use external power sources connected through the tank to control the potential of the metal electrodes to achieve chlorine production or copper electrolysis. The electrolysis process is accompanied by a series of hydrogen production problems, which can easily cause hydrogen embrittlement of the titanium alloy substrate, posing a significant threat to the safe operation of the equipment. Therefore, a marine antifouling measure that can be used for titanium alloy waste heat exchangers and has high safety is still lacking, which will hinder the promotion and use of titanium alloy waste heat exchangers.

[0027] In its previous research, the applicant provided a seawater temperature-responsive resin composition for antifouling coatings (Publication No.: CN109651914A), comprising an ion exchange resin capable of hydrolyzing in water to release an antifouling agent, and a temperature-sensitive copolymer mixed with the ion exchange resin. This temperature-sensitive copolymer is formed by polymerizing temperature-sensitive monomers and hydrophobic monomers with additives. It shrinks its molecular chains as temperature increases, creating pores in the resin composition for seawater intrusion and antifouling agent exudation, and expands its molecular chains as temperature decreases to block these pores. However, the above solution releases the antifouling agent rapidly in the heat exchanger operating environment, significantly reducing its performance. Therefore, the applicant proposes the following technical solution:

[0028] Example 1

[0029] An antifouling sustained-release tablet comprises the following components:

[0030]

[0031] Prepared using the following method:

[0032] S1. Weigh the resin base and antifouling filler according to the specified amount, add the antifouling filler to the resin, and mix them using a high-speed disperser to prepare a slurry. The critical dissolution temperature of poly(glycolic acid) lactide is 60±2℃.

[0033] S2. Cut the polyester fiber cotton to a size of 110mm*80mm*10mm according to the structure and size of the antifouling slow-release tablet mold, and soak it in the slurry for about 58 hours to allow the fiber cotton to absorb a large amount of slurry. Then transfer the fiber cotton to the slow-release tablet mold with a mold size of 110mm*80mm*10mm. Before placing it, a layer of polytetrafluoroethylene film should be added to the bottom as a substrate for demolding.

[0034] S3. Place it in a 40℃ oven and bake for 48 hours. After drying, remove the polytetrafluoroethylene film at the bottom to form an anti-fouling slow-release tablet.

[0035] Example 2:

[0036] An antifouling sustained-release tablet comprises the following components:

[0037]

[0038] Prepared using the following method:

[0039] S1. Weigh the resin base and antifouling filler according to the specified amount, add the antifouling filler to the resin, and mix them with a high-speed disperser to prepare a slurry. The critical dissolution temperatures of poly(glycolic acid) lactide and poly(hexyl lactide-polyethylene glycol-poly(hexyl lactide)) lactide are 60±2℃ and 40±2℃, respectively.

[0040] S2. Cut the polyester fiber cotton to a size of 110mm*80mm*10mm according to the structure and size of the anti-fouling slow-release tablet mold, and soak it in the slurry for about 50 hours to allow the fiber cotton to absorb a large amount of slurry. Then transfer the fiber cotton to the slow-release tablet mold with a size of 110mm*80mm*10mm. Before placing it, a layer of polytetrafluoroethylene film should be added to the bottom as a substrate to facilitate demolding.

[0041] S3. Place it in a 40℃ oven and bake for 60 hours. After drying, remove the polytetrafluoroethylene film at the bottom to form an anti-fouling slow-release tablet.

[0042] Example 3

[0043] An antifouling sustained-release tablet comprises the following components:

[0044]

[0045] Prepared using the following method:

[0046] S1. Weigh the resin base and antifouling filler according to the specified amount, add the antifouling filler to the resin, and mix them with a high-speed disperser to prepare a slurry. The critical dissolution temperatures of poly(glycolic acid) lactide and poly(hexyl lactide-polyethylene glycol-poly(hexyl lactide)) lactide are 60±2℃ and 40±2℃, respectively.

[0047] S2. Cut the polyester fiber cotton to a size of 110mm*80mm*10mm according to the structure and size of the anti-fouling slow-release tablet mold, and soak it in the slurry for about 50 hours to allow the fiber cotton to absorb a large amount of slurry. Then transfer the fiber cotton to the slow-release tablet mold with a size of 110mm*80mm*10mm. Before placing it, a layer of polytetrafluoroethylene film should be added to the bottom as a substrate to facilitate demolding.

[0048] S3. Place it in a 40℃ oven and bake for 60 hours. After drying, remove the polytetrafluoroethylene film at the bottom to form an anti-fouling slow-release tablet.

[0049] Example 4:

[0050] An antifouling sustained-release tablet comprises the following components:

[0051]

[0052] Prepared using the following method:

[0053] Prepared using the following method:

[0054] S1. Weigh the resin base and antifouling filler according to the specified amount, add the antifouling filler to the resin, and mix them using a high-speed disperser to prepare a slurry. The critical dissolution temperature of poly(hexyl lactide)-polyethylene glycol-poly(hexyl lactide) is 40±2℃.

[0055] S2. Cut the polyester fiber cotton to a size of 110mm*80mm*10mm according to the structure and size of the anti-fouling slow-release tablet mold, and soak it in the slurry for about 50 hours to allow the fiber cotton to absorb a large amount of slurry. Then transfer the fiber cotton to the slow-release tablet mold with a size of 110mm*80mm*10mm. Before placing it, a layer of polytetrafluoroethylene film should be added to the bottom as a substrate to facilitate demolding.

[0056] S3. Place it in a 40℃ oven and bake for 60 hours. After drying, remove the polytetrafluoroethylene film at the bottom to form an anti-fouling slow-release tablet.

[0057] Comparative Example 1

[0058] Antifouling sustained-release tablets were prepared using the same preparation method as in Example 1, with the only difference being that no temperature-sensitive polymer was added, while the amounts of the other components remained unchanged.

[0059] Test Results

[0060] The antifouling slow-release tablets prepared in Example 1 and Comparative Example 1 were placed in 2L of artificial seawater at 60°C and soaked for 2 hours (samples were taken every 1 hour, for a total of 2 times). Then, they were transferred to 2L of artificial seawater at room temperature and soaked for 2 days (samples were taken after 24 hours of soaking and the seawater was replaced, for a total of 2 days). This process constituted one cycle, and a total of 4 cycles were conducted. The concentration change of the antifouling agent in the artificial seawater was measured, and the results are shown in […]. Figure 1 The origin and the square represent Example 1 and Comparative Example 1, respectively.

[0061] The antifouling slow-release tablets prepared in Example 1 maintained a relatively constant release rate of the antifouling agent throughout the entire experimental period, remained in good condition, and did not exhibit water absorption and swelling. Figure 2 In contrast, the antifouling slow-release tablets prepared in Comparative Example 1, lacking the addition of temperature-sensitive polymers, exhibited a significantly accelerated antifouling agent release rate in high-temperature artificial seawater, followed by a significantly reduced release rate in room-temperature artificial seawater. After four cycles, significant expansion occurred, with some antifouling material overflowing from the titanium alloy packaging box. Figure 3 The release rate of the antifouling agent also increased significantly as the antifouling slow-release tablets expanded.

[0062] The thermosensitive polymer exhibits temperature-responsiveness. Below its critical dissolution temperature, it remains swollen in seawater, maintaining the normal antifouling agent release rate of the antifouling slow-release tablet. Above the critical dissolution temperature, the thermosensitive polymer transitions from a swollen to a contracted state, reducing the water absorption and antifouling agent leakage rate of the antifouling slow-release tablet. However, while the high-temperature seawater environment is no longer suitable for the growth of marine fouling organisms, good antifouling performance can still be achieved within the heat exchanger cavity. As the heat exchanger ceases operation and the internal temperature decreases, gradually approaching the natural seawater temperature, the thermosensitive polymer re-enters a swollen state, increasing the antifouling agent release concentration and ensuring continued good antifouling performance within the heat exchanger cavity. This preparation method not only achieves controlled release of the antifouling agent from the antifouling slow-release tablet but also effectively extends its service life.

[0063] While the present invention has been disclosed above, it is not limited thereto. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of the invention; therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. The application of an antifouling slow-release tablet in marine equipment, characterized in that, The antifouling slow-release tablet comprises 3-6 parts of a thermosensitive polymer, 2-4 parts of a water-soluble resin, 12-22 parts of a hydrated slow-release resin, and 55-70 parts of an antifouling functional filler; the thermosensitive polymer is poly(hexyl lactide)-polyethylene glycol-poly(hexyl lactide). The marine equipment is a titanium alloy heat exchanger; The method for preparing the antifouling sustained-release tablet includes: S1. Weigh out the resin base and antifouling filler according to the specified amount, add the antifouling filler to the resin, and mix them using a high-speed disperser to prepare a slurry. S2. Cut the fiber cotton according to the mold structure size of the antifouling slow-release tablet, soak it in slurry for 48-72 hours, and then transfer the fiber cotton into the mold. The bottom of the mold is pre-placed with a polytetrafluoroethylene film as a substrate. S3. Place it in an oven at 38-45℃ and bake for 48-72 hours. After drying, remove the polytetrafluoroethylene film at the bottom to form an anti-fouling slow-release tablet. The hydrating slow-release resin is selected from at least one of zinc acrylate resin, silicone acrylate resin, and acrylate resin.

2. The application according to claim 1, characterized in that, The water-soluble resin is selected from one or more substances in the group consisting of polyvinyl alcohol, polyvinylpyrrolidone, polyacrylic acid, polyethyleneimine, polyethylene oxide, polyvinylamine, and polyallylamine.

3. The application according to claim 2, characterized in that, The water-soluble resin is either polyvinyl alcohol 1792 or polyvinyl alcohol 1788.

4. The application according to claim 1, characterized in that, The antifouling filler comprises 35-40 parts cuprous oxide, 10-15 parts zinc oxide, and 10-15 parts organic antifouling agent.

5. The application according to claim 4, characterized in that, The organic antifouling agent is any one or more of bromopyrrolidone, copper pyridinethione, zinc pyridinethione, zineb, and isothiazolinone.

6. The application according to claim 1, characterized in that, The length, width, and height of the fiber cotton are 80-150mm, 50-100mm, and 5-15mm, respectively.

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