Corrosion-resistant thermal insulation material for ocean thermal insulation

Abstract

Belonging to the technical field of thermal insulation material preparation, the invention relates to a corrosion resistant thermal insulation material for marine thermal insulation, which is prepared by the following steps: carrying out acidolysis treatment on plants, then filtering, and pulping the filtered product to obtain a fiber acidolysis solution and a fiber acidolysis product. And then modifying the fiber acidolysis solution and the fiber acidolysis product by using dopamine hydrochloride and a silane coupling agent respectively. The modified cellulose has a good fusion effect in a polyurethane system due to the fact that the modified cellulose contains an amide group, and can be stably adhered to the surface of a metal pipeline for energy transportation in the ocean. Si-O-Si bonds formed by the modified plant fibers can improve the structural stability of the fibers, so that the weather resistance, tensile strength, impact strength and other mechanical properties are improved. The prepared thermal insulation material has the characteristics of good mechanical property and high stability.

Description

Technical Field

[0001] The invention relates to the technical field of thermal insulation material preparation, in particular to a corrosion-resistant thermal insulation material for marine thermal insulation. Background Art

[0002] As my country's oil and gas development continues to move towards deep water, deep-sea areas have become one of the important new areas for increasing oil and gas reserves and production in my country. Marine pipelines, including submarine pipelines and risers, are the core of marine oil and gas fields.

[0003] It is an important part of the development and the main means of oil and gas transportation. However, the temperature of oil and gas will drop when transported in marine pipelines. Especially for crude oil with high viscosity, if no insulation measures are taken during the pipeline transportation, wax components will be precipitated one after another when the oil temperature drops, and the viscosity of crude oil will increase, resulting in poor fluidity. Or under the condition of high-pressure and long-distance natural gas transportation, natural gas hydrates will precipitate in a solid form similar to loose ice, which may lead to pipeline blockage and other production accidents in serious cases.

[0004] Polyurethane insulation material is a commonly used marine insulation material with the characteristics of easy quality control and low equipment investment. However, due to the limitation of the installation capacity of ships, the double-layer steel pipe insulation structure maturely used in shallow waters will be difficult to apply in deep waters. The insulation structure of pipelines in deep waters mainly adopts single steel pipe wet insulation that does not require an outer protective layer, which requires the insulation material to have good mechanical properties, stable adhesion on the surface of the pipeline, and hydrolysis resistance.

[0005] Therefore, a high-performance thermal insulation material for marine thermal insulation is needed to ensure the normal operation of the pipeline. Summary of the invention

[0006] The object of the present invention is to provide a corrosion-resistant thermal insulation material for marine thermal insulation to solve the problems raised in the background technology. The plant is subjected to an acid hydrolysis treatment, followed by filtration, and the filtrate is subjected to a pulping treatment to obtain a fiber acid hydrolyzate and a fiber acid hydrolyzate. Subsequently, dopamine hydrochloride and a silane coupling agent are used to modify the fiber acid hydrolyzate and the fiber acid hydrolyzate, respectively. The modified cellulose has a good fusion effect in a polyurethane system because it contains an amide group, and can be firmly bonded to the surface of a metal pipeline used for energy transportation in the ocean. The Si-O-Si bond formed by the modified plant fiber can improve the structural stability of the fiber, thereby improving the weather resistance and mechanical properties such as tensile strength and impact strength.

[0007] To achieve the above object, the present invention provides the following technical solutions:

[0008] A corrosion-resistant thermal insulation material for marine thermal insulation comprises the following steps:

[0009] S1. Acid hydrolysis of agricultural waste is performed, followed by filtration, and the filtrate is pulped to obtain a fiber acid hydrolyzate and a fiber acid hydrolyzate. The specific operation steps are as follows:

[0010] The plant waste is washed with deionized water, then naturally air-dried, then chopped into 1-8 cm fragments, then added to an acid solution for acid treatment, the pH value of the system is adjusted to 5-6, the system temperature is increased to 70°C-90°C, and the acid treatment time is 4-6 hours to obtain a fiber acid hydrolysis system, the fiber acid hydrolysis system is filtered, the filtrate is collected, and rotary evaporated to obtain a fiber acid hydrolyzate; the collected filtrate is washed with deionized water until the pH value of the washing liquid is neutral, then placed in a pulper for pulping, then filtered, and the filtrate is collected to obtain a fiber acid hydrolyzate;

[0011] In the above reaction process, acid is used to treat plant waste to decompose cellulose, lignin and other substances therein, so that part of the cellulose is dissolved in the acid. The remaining lignin cellulose and other substances are then pulped to change their original form and structure, increase their specific surface area, weaken the degree of polymerization and crystallinity of cellulose, reduce the particle length, and loosen the structure.

[0012] S2. Modifying the fiber acid hydrolyzate using dopamine hydrochloride to obtain modified cellulose, the specific operation is as follows:

[0013] (A1) 0.585 g of 0.1 mol / L 2-morpholineethanesulfonic acid and 0.0876 g of 0.05 mol / L NaCl were added to 30 mL of sterile deionized water, and the pH value of the system was adjusted to 5.1 with NaOH solution to obtain 2-morpholineethanesulfonic acid buffer for later use;

[0014] (A2) The fiber acid hydrolyzate obtained in step S1, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, N-hydroxysuccinimide and dopamine hydrochloride are dissolved in 2-morpholineethanesulfonic acid buffer and stirred for 24 hours at room temperature under an inert gas atmosphere to obtain modified cellulose.

[0015] In the above reaction process, the amino group in dopamine hydrochloride reacts with the carboxyl group on cellulose to form an amide bond through the 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride / N-hydroxysuccinimide system, thereby grafting the catechol group on the cellulose.

[0016] S3, modifying the fiber acid hydrolyzate obtained in step S1 using a silane coupling agent and organosilicon to obtain modified plant fiber, the specific operation is as follows:

[0017] Anhydrous ethanol and deionized water are mixed uniformly in a mass ratio of 3:4 to obtain an ethanol solution; the ethanol solution is then mixed with 30 g / L of a silane coupling agent to obtain a silane coupling agent solution; the fiber acid hydrolysate obtained in step S1 is washed with deionized water until the washing liquid is neutral, then immersed in a silane coupling agent, and then subjected to microwave treatment, with the microwave treatment power set to 200 W and the treatment time set to 30 minutes, and the organosilicon is dissolved in a tetrahydrofuran solution and stirred uniformly to obtain an organosilicon solution; the organosilicon solution and the fiber acid hydrolysate after microwave treatment are then stirred uniformly at room temperature, allowed to stand for 12 hours, precooled at -20°C for 2 hours, and then freeze-dried to obtain the modified plant fiber.

[0018] In the above reaction process, the silane coupling agent is hydrolyzed in the ethanol system, and then covalently bonds with the hydroxyl groups on the surface of the plant fiber to complete the modification of the plant fiber. At the same time, the silane coupling agent reacts with the silanol groups in the silicone to form siloxane bonds, so that the system forms a cross-linked network, which is then dried using a microwave method to prepare an aerogel.

[0019] S4. Evenly mix diphenylmethane diisocyanate, small molecule alcohol, trimethyl phenylphosphonate and phenylchloroformyl to prepare a prepolymer component A; then mix polymer polyol, polytetramethylene ether glycol, 1,4-butanediol and the modified cellulose prepared in step S2 to obtain component B; mix component A and component B and stir them using a high-speed electronic stirrer at a stirring speed of 2000 rpm and a stirring temperature of 30-40°C to obtain a polyurethane material.

[0020] S5. After the polyurethane obtained in step S4 and the modified fiber obtained in step S3 are uniformly stirred at room temperature, a high-pressure injection machine connected to the discharge structure of the high-speed stirring kettle is used to inject the system into the cavity of the mold, and the mold is closed by a press to allow the polyurethane to fully foam on the outer layer of the steel pipe. The waiting time is 0.5-2 hours, and the mold is cooled by a condenser to cool the mold to room temperature. The continuous cooling time is 10-20 minutes, and a corrosion-resistant thermal insulation material for marine thermal insulation is obtained.

[0021] Furthermore, the conditions for the pulping treatment are: a pulping time of 10-20 minutes, a pulping speed of 300-600 rpm, and a pulping temperature of 40-60°C.

[0022] Furthermore, in step A2, the volume mass ratio of the fiber acid hydrolysate to dopamine hydrochloride is (5-10) mL: (0.1-1.0) g.

[0023] Furthermore, in step S4, the mass ratio of diphenylmethane diisocyanate MDI-1, small molecule alcohol, trimethyl phenylphosphonate and phenylchloroformyl is (60-90):(2-10):(0.01-0.5):(0.01-0.5).

[0024] Furthermore, in step S4, the mass ratio of polymer polyol, polytetramethylene ether glycol, 1,4-butanediol and modified cellulose is (20-30):(5-10):(5-10):(20-30).

[0025] Furthermore, the organosilicon includes ethyl silicate, tetramethoxysilane, and cage-type polysilsesquioxane.

[0026] Furthermore, the silane coupling agent includes KH-550, KH-570, KH-566, and KH-567.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] In the technical solution of the present invention, the plant is subjected to an acid hydrolysis treatment, then filtered, and the filtrate is subjected to a pulping treatment to obtain a fiber acid hydrolyzate and a fiber acid hydrolyzate. The fiber acid hydrolyzate contains hydrolyzed cellulose, lignin and polyol compounds including sugar alcohols, glucose, etc., which can react with isocyanate groups in the subsequent preparation process to generate polyurethane, reduce the amount of polymer polyol used, and reduce the preparation cost. The pulping treatment can change the original morphology and structure of the plant fiber, increase its specific surface area, weaken the degree of polymerization and crystallinity of the cellulose, reduce the particle length, and loosen the structure, making it easier to be infiltrated by the solvent in the system, improving its dispersibility and allowing for better combination with the silane coupling agent in the subsequent process.

[0029] Subsequently, dopamine hydrochloride and silane coupling agent are used to modify the fiber acid hydrolyzate and the fiber acid hydrolyzate. By using the amino group in dopamine hydrochloride and the carboxyl group on the cellulose, an amide bond is generated by the reaction of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride / N-hydroxysuccinimide system, thereby grafting a catechol group on the cellulose. The modified cellulose has a good fusion effect in the polyurethane system due to the presence of an amide group, and in the process of polyurethane foaming, it can be firmly bonded to the surface of a metal pipeline for energy transportation in the ocean, and is combined in the form of a metal ion coordination bond on the pipeline surface to increase the bonding effect of the insulation layer and the pipeline. At the same time, the content of hydroxyl groups in the system is reduced, the hydrophobic effect of the material is improved, and the overall water absorption is reduced, which is conducive to the application of the obtained thermal insulation material in the ocean.

[0030] In the process of modifying the fiber acid hydrolysate, the silane coupling agent is hydrolyzed and combined with the hydroxyl groups on the surface of the plant fiber through covalent bonds to complete the modification of the plant fiber. After modification, the plant fiber no longer has a hydrophilic effect, and the formed Si-O-Si bond can improve the structural stability of the fiber, thereby improving the weather resistance and mechanical properties such as tensile strength and impact strength. After mixing with silicone, the silane coupling agent can react with the silicon hydroxyl groups in the aerogel matrix to form siloxane bonds, bridge the plant fiber and silicone, form a flexible gel skeleton, and improve the corrosion resistance, tensile strength, bending strength, fracture toughness, etc. of the composite material.

[0031] The Si-O-Si skeleton contained in the modified plant fiber can improve the flexibility of the aerogel. After the SiO2 aerogel containing natural fibers is mixed with the polyurethane system, the mechanical properties of the polyurethane matrix can be improved, and its skeleton strength can be improved, so that it can adapt to a wider range of drying conditions after foaming. At the same time, the cations in the polyurethane can electrostatically adsorb with the anions on the surface of the plant fiber, and the silane coupling agent can lubricate the fiber surface, thereby preventing fiber aggregation and helping the plant fiber to be evenly dispersed in the system. DETAILED DESCRIPTION

[0032] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0033] Example 1

[0034] The fiber acid hydrolysate and the fiber acid hydrolysate are prepared by the following steps:

[0035] The discarded leaves and stems of the vegetables are washed with deionized water, then naturally dried in the sun, and then chopped into 1-8 cm fragments, and then added with hydrochloric acid solution for acid treatment, the pH value of the system is adjusted to 5, the system temperature is increased to 70°C, and the acid treatment time is 4 hours to obtain a fiber acid hydrolysis system, the fiber acid hydrolysis system is filtered, the filtrate is collected, and rotary evaporated to obtain a fiber acid hydrolyzate; the collected filtrate is washed with deionized water until the pH value of the washing liquid is neutral, and then placed in a pulper for pulping treatment, the pulping time is 10 minutes, the pulping speed is 300 rpm, and the pulping temperature is 40°C, and then filtered, the filtrate is collected to obtain a fiber acid hydrolyzate.

[0036] Example 2

[0037] The difference between this embodiment and embodiment 1 is that the pH value of the acid treatment is 5.5, the treatment temperature is 80°C, and the treatment time is 5 hours. During the pulping treatment, the pulping time is 15 minutes, the pulping speed is 450 rpm, and the pulping temperature is 50°C.

[0038] Example 3

[0039] The difference between this embodiment and embodiment 1 is that the pH value of the acid treatment is 6, the treatment temperature is 90°C, and the treatment time is 6 hours. During the pulping treatment, the pulping time is 20 minutes, the pulping speed is 600 rpm, and the pulping temperature is 60°C.

[0040] Example 4

[0041] Modified cellulose is prepared by the following steps:

[0042] A1, add 0.585g 0.1mol / L 2-morpholineethanesulfonic acid and 0.0876g 0.05mol / L NaCl to 30mL sterile deionized water, use NaOH solution to adjust the pH value of the system to 5.1, and obtain 2-morpholineethanesulfonic acid buffer for standby use;

[0043] A2. Dissolve 5 mL of the fiber acid hydrolyzate in Example 1, 0.192 g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, 0.115 g of N-hydroxysuccinimide and 0.1 g of dopamine hydrochloride in 10 mL of 2-morpholineethanesulfonic acid buffer, and stir the mixture at room temperature under N2 gas atmosphere for 24 hours to obtain modified cellulose.

[0044] Example 5

[0045] The difference between this embodiment and embodiment 4 is that in step A2, the fiber acid hydrolysate prepared in embodiment 2 is used in an amount of 8 mL, and the amount of dopamine hydrochloride used is 0.5 g.

[0046] Example 6

[0047] The difference between this embodiment and embodiment 4 is that in step A2, the fiber acid hydrolysate prepared in embodiment 3 is used in an amount of 10 mL, and the amount of dopamine hydrochloride used is 1.0 g.

[0048] Example 7

[0049] The modified plant fiber is prepared by the following steps:

[0050] Anhydrous ethanol and deionized water were mixed in a mass ratio of 3:4 to obtain an ethanol solution; then 10 mL of the ethanol solution was mixed with 10 mL of 30 g / L KH-550 silane coupling agent to obtain a silane coupling agent solution; the fiber acid hydrolyzate prepared in Example 1 was washed with deionized water until the washing liquid was neutral, and then immersed in a silane coupling agent according to a bath ratio of 1 g: 10 mL, and then subjected to microwave treatment, with the microwave treatment power set to 200 W and the treatment time set to 30 minutes; 1 g of organosilicon was dissolved in 10 mL of tetrahydrofuran solution, and stirred at 30 rpm at room temperature to obtain an organosilicon solution; then 20 mL of ethyl silicate and 1 g of the fiber acid hydrolyzate after microwave treatment were stirred at room temperature, left to stand for 12 hours, precooled at -20°C for 2 hours, and then freeze-dried to obtain modified plant fiber.

[0051] Example 8

[0052] The difference between this embodiment and embodiment 7 is that the fiber acid hydrolyzate is prepared in embodiment 2, the silane coupling agent used is KH-570, and the organic silicon used is tetramethoxysilane.

[0053] Example 9

[0054] The difference between this embodiment and embodiment 7 is that the fiber acid hydrolyzate is prepared in embodiment 3, and the silane coupling agent used is KH-566.

[0055] Example 10

[0056] A corrosion-resistant thermal insulation material for marine thermal insulation is prepared by the following steps:

[0057] S1. Diphenylmethane diisocyanate MDI-1, ethanol, trimethyl phenylphosphonate and phenylchloroformyl are uniformly mixed in a mass ratio of 60:2:0.01:0.01 to prepare a prepolymer component A; then polypropylene glycol, polytetramethylene ether glycol, 1,4-butanediol and the modified cellulose prepared in Example 4 are mixed in a ratio of 20:5:5:20 to obtain component B; component A and component B are mixed and stirred using a high-speed electronic stirrer at a stirring speed of 2000 rpm and a stirring temperature of 30°C to obtain a polyurethane material.

[0058] S2. After the polyurethane obtained in step S1 and the modified fiber obtained in Example 7 are uniformly stirred at room temperature, a high-pressure injection machine connected to the discharge structure of the high-speed stirring kettle is used to inject the system into the mold cavity, and the mold is closed by a press to allow the polyurethane to fully foam on the outer layer of the steel pipe. The foaming time is 0.5 hours, and the mold is cooled by a condenser to cool the mold to room temperature. The continuous cooling time is 10 minutes, and a corrosion-resistant thermal insulation material for marine thermal insulation is obtained.

[0059] Embodiment 11

[0060] The difference between this embodiment and embodiment 10 is that in step S1, the mass ratio of diphenylmethane diisocyanate MDI-1, ethanol, trimethyl phenylphosphonate and phenylchloroformyl is 75:6:0.25:0.25; the mass ratio of polypropylene glycol, polytetramethylene ether glycol, 1,4-butanediol and the modified cellulose prepared in embodiment 4 is 25:7:8:25, and the stirring temperature is 35° C. In step S2, the modified fiber is prepared in embodiment 8, the foaming time is 1.5 hours, and the cooling time is 15 minutes.

[0061] Example 12

[0062] The difference between this embodiment and embodiment 10 is that in step S1, the mass ratio of diphenylmethane diisocyanate MDI-1, ethanol, trimethyl phenylphosphonate and phenylchloroformyl is 90:10:0.5:0.5; the mass ratio of polypropylene glycol, polytetramethylene ether glycol, 1,4-butanediol and the modified cellulose prepared in embodiment 4 is 30:10:10:30, and the stirring temperature is 40° C. In step S2, the modified fiber is prepared in embodiment 9, the foaming time is 2 hours, and the cooling time is 20 minutes.

[0063] Comparative Example 1

[0064] The difference between this comparative example and Example 11 is that the fiber acid hydrolyzate is not modified.

[0065] Comparative Example 2

[0066] The difference between this comparative example and Example 11 is that the fiber acid hydrolysate is not modified.

[0067] Comparative Example 3

[0068] The difference between this comparative example and Example 11 is that no silicone is added.

[0069] Comparative Example 4

[0070] The difference between this comparative example and Example 11 is that no plant waste raw materials are used to strengthen the material.

[0071] The thermal insulation effect of the thermal insulation materials prepared in Examples 10-12 and Comparative Examples 1-4 was tested. The thermal conductivity of the thermal insulation materials was measured at room temperature by the transient plane heat source method to determine the thermal insulation effect of the materials. Five readings were obtained for each sample and the average value was taken. The test results are shown in Table 1 below.

[0072] Table 1 Thermal insulation effect test of thermal insulation materials prepared in Examples 10-12 and Comparative Examples 1-4

[0073] project Thermal conductivity (W / m / K) Example 10 0.0211 Embodiment 11 0.0201 Example 12 0.0214 Comparative Example 1 0.0220 Comparative Example 2 0.0241 Comparative Example 3 0.0259 Comparative Example 4 0.0341

[0074] From the results in Table 1, it can be seen that the thermal insulation material prepared in Example 11 has the lowest thermal conductivity and theoretically has the best thermal insulation effect. From the results in Comparative Example 1, it can be seen that the modified fiber acid hydrolyzate can have a uniform dispersion effect on the components in the system, so that the system can achieve a better thermal insulation effect. From the results in Comparative Examples 2-4, it can be seen that after the plant fiber is modified by the silane coupling agent, the strength of the SiO2 aerogel skeleton can be increased, and the flexibility of the aerogel can be increased, so that the aerogel pores are evenly distributed, and the thermal insulation effect of the material is increased.

[0075] The moisture absorption rate of the thermal insulation materials prepared in Examples 10-12 and Comparative Examples 1-4 is now tested. The moisture absorption rate is tested according to the method in "GB / T 8110-2005 Determination of water absorption rate of rigid foam plastics", and five readings are obtained for each sample and the average value is taken. The test results are shown in Table 2 below.

[0076] Table 2 Moisture absorption test of thermal insulation materials prepared in Examples 10-12 and Comparative Examples 1-4

[0077] project Moisture absorption rate (%) Example 10 0.107 Embodiment 11 0.091 Example 12 0.111 Comparative Example 1 0.184 Comparative Example 2 0.365 Comparative Example 3 0.319 Comparative Example 4 0.175

[0078] From the results in Table 2, it can be seen that the modified thermal insulation material has lower water absorption than the single polyurethane material. The use of silane coupling agent and silicone can reduce the water absorption of plant fibers, making the material more hydrophobic, which is conducive to its use in the ocean.

[0079] The mechanical properties of the thermal insulation materials prepared in Examples 10-12 and Comparative Examples 1-4 were tested. The compressive strength and tensile strength of the thermal insulation material samples were tested according to the methods in GB / T 8813-2008 Determination of Compression Properties of Rigid Foam Plastics and ASTM-D638-2010 Plastic Tensile Test. Five readings were obtained for each sample and the average value was taken. The test results are shown in Table 3 below.

[0080] Table 3 Tests on mechanical properties of thermal insulation materials prepared in Examples 10-12 and Comparative Examples 1-4

[0081]

[0082]

[0083] From the results in Table 3, it can be seen that the thermal insulation material sample prepared in Example 11 has the highest compressive strength and tensile strength. Flexible silicon-based aerogel can improve the mechanical strength of polyurethane thermal insulation materials, which is manifested as increased compressive strength and tensile strength, and is beneficial to improving the corrosion resistance of the material. Silane coupling agent modified plant fiber can increase the content of Si-O-Si in the system, improve the toughness of the material, and thus improve the compressive strength of the material.

[0084] In the description of the specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0085] The above contents are merely examples and explanations of the present invention. Those skilled in the art may make various modifications or additions to the specific embodiments described or replace them in a similar manner. As long as they do not deviate from the invention or exceed the scope defined by the claims, they shall all fall within the protection scope of the present invention.

Claims

1. A corrosion-resistant thermal insulation material for marine thermal insulation, characterized in that: The following steps are involved: S1. Acid hydrolyzing the agricultural waste, filtering it, and beating the filtered product to obtain a fiber acid hydrolyzate and a fiber acid hydrolyzate; S2, modifying the fiber acid hydrolyzate using dopamine hydrochloride to obtain modified cellulose; S3, modifying the fiber acid hydrolyzate obtained in step S1 using a silane coupling agent and organosilicon to obtain modified plant fiber; S4, uniformly mixing diphenylmethane diisocyanate, small molecule alcohol, trimethyl phenylphosphonate and phenylchloroformyl to prepare a prepolymer component A; then mixing polymer polyol, polytetramethylene ether glycol, 1,4-butanediol and the modified cellulose prepared in step S2 to obtain component B; mixing component A and component B and stirring them with a high-speed electronic stirrer at a stirring speed of 2000 rpm and a stirring temperature of 30-40° C. to obtain a polyurethane material; S5. The polyurethane obtained in step S4 and the modified fiber obtained in step S3 are uniformly stirred at room temperature, and then injected into a mold. The mold is closed by a press to allow the polyurethane to foam. The waiting time is 0.5-2 hours. The mold is cooled by a condenser to allow the mold to cool to room temperature. The continuous cooling time is 10-20 minutes, thereby obtaining a corrosion-resistant thermal insulation material for marine thermal insulation.

2. The corrosion-resistant thermal insulation material for marine thermal insulation according to claim 1, characterized in that: The fiber acid hydrolyzate and the fiber acid hydrolyzate are specifically prepared by the following steps: The plant waste is washed with deionized water, dried, and then chopped, and then added into an acid solution for acid treatment, the pH value of the system is adjusted to 5-6, the system temperature is increased to 70°C-90°C, and the acid treatment time is 4-6 hours to obtain a fiber acid hydrolysis system, the fiber acid hydrolysis system is filtered, the filtrate is collected, and the fiber acid hydrolysis solution is obtained by rotary evaporation; The filtrate is collected and washed until the pH value of the washing liquid is neutral, and then pulped and filtered to collect the filtrate to obtain a fiber acid hydrolyzate.

3. The corrosion-resistant thermal insulation material for marine thermal insulation according to claim 2, characterized in that: The conditions for the pulping treatment are: the pulping time is 10-20 minutes, the pulping speed is 300-600rpm, and the pulping temperature is 40-60°C.

4. The corrosion-resistant thermal insulation material for marine thermal insulation according to claim 1, characterized in that: In step S2, the modified cellulose is prepared by the following steps: A1, 2-morpholineethanesulfonic acid and NaCl were added to sterile deionized water, and the pH value of the system was adjusted to 5.1 using NaOH solution to obtain 2-morpholineethanesulfonic acid buffer for standby use; A2. Dissolve the fiber acid hydrolyzate in step S1, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, N-hydroxysuccinimide and dopamine hydrochloride in 2-morpholineethanesulfonic acid buffer, and stir well for 24 hours at room temperature under an inert gas atmosphere to obtain modified cellulose.

5. The corrosion-resistant thermal insulation material for marine thermal insulation according to claim 4, characterized in that: In step A2, the volume mass ratio of the fiber acid hydrolysate and dopamine hydrochloride is (5-10) mL: (0.1-1.0)g。 6. The corrosion-resistant thermal insulation material for marine thermal insulation according to claim 1, characterized in that: In step S3, the modified plant fiber is prepared by the following steps: Anhydrous ethanol and deionized water are mixed evenly to obtain an ethanol solution; the ethanol solution is then mixed with a silane coupling agent to obtain a silane coupling agent solution; the fiber acid hydrolysate obtained in step S1 is washed until the washing liquid is neutral, then immersed in a silane coupling agent, and then subjected to microwave treatment, with the microwave treatment power set to 200 W and the treatment time set to 30 minutes, and the organosilicon is dissolved in a tetrahydrofuran solution and stirred evenly to obtain an organosilicon solution; the organosilicon solution and the fiber acid hydrolysate after microwave treatment are then stirred evenly at room temperature, left to stand for 12 hours, pre-cooled at -20°C for 2 hours, and then freeze-dried to obtain the modified plant fiber.

7. The corrosion-resistant thermal insulation material for marine thermal insulation according to claim 6, characterized in that: The organic silicon includes ethyl silicate, tetramethoxysilane and cage-type polysilsesquioxane.

8. The corrosion-resistant thermal insulation material for marine thermal insulation according to claim 6, characterized in that: The silane coupling agents include KH-550, KH-570, KH-566 and KH-567.

9. The corrosion-resistant thermal insulation material for marine thermal insulation according to claim 1, characterized in that: In step S4, the mass ratio of diphenylmethane diisocyanate MDI-1, small molecule alcohol, trimethyl phenylphosphonate and phenylchloroformyl is (60-90):(2-10):(0.01-0.5):(0.01-0.5).

10. The corrosion-resistant thermal insulation material for marine thermal insulation according to claim 1, characterized in that: In step S4, the mass ratio of polymer polyol, polytetramethylene ether glycol, 1,4-butanediol and modified cellulose is (20-30):(5-10):(5-10):(20-30).

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