Non-metallic composite thermal insulation material for LNG storage tank and preparation method thereof

Abstract

The application discloses a kind of non-metal composite thermal insulation materials for LNG storage tank and preparation method thereof in the field of thermal insulation materials, comprising the following components by weight: polyisocyanate, polyether polyol, pentaerythritol hydroxymethyl phosphate, SiO2 Composite aerogel, silicone oil, blowing agent, catalyst.The polyurethane structure formed by the crosslinking reaction of polyisocyanate and polyether polyol, which has a certain carbonization capacity, can form a carbon layer at high temperature, play an oxygen isolation role, thereby delaying combustion, the introduction of pentaerythritol hydroxymethyl phosphate, this component contains phosphate group, can be decomposed to generate non-combustible gas at high temperature, and promote the formation of porous carbon layer, further enhance the flame retardant performance of the material.

Description

Technical Field

[0001] This invention belongs to the field of thermal insulation materials technology, specifically referring to a non-metallic composite thermal insulation material for LNG storage tanks and its preparation method. Background Technology

[0002] Liquefied natural gas (LNG) is natural gas that has been converted into a liquid state at low temperatures. LNG storage tanks typically need to store natural gas at temperatures as low as -162°C, which places extremely high demands on the thermal insulation performance of the tank materials. Common thermal insulation materials include: Polyurethane foam: a closed-cell foam made from polyether polyols and polyisocyanates, it has good thermal insulation properties and a low density; Foamed glass: mainly composed of silicate glass, it is made by blowing with a foaming agent at high temperatures. It is a completely non-combustible thermal insulation material and is compatible with most chemicals; Perlite insulation material: perlite is a natural mineral that expands when heated to form a lightweight... Porous materials possess excellent thermal insulation properties; Aerogel composites: Aerogel is the lowest density solid known to date, composed of a network of nanoparticles. Although pure aerogel is extremely fragile, combining it with reinforcing fibers maintains good thermal insulation properties while improving mechanical strength; Glass fiber reinforced plastics: Made by combining glass fiber as a reinforcing material with a polymer matrix, these composites exhibit good chemical corrosion resistance and high mechanical strength; Aramid fiber composites: Aramid fiber is a high-performance synthetic fiber with excellent heat resistance and strength. Composites made based on this fiber perform well at low temperatures.

[0003] Current technologies mainly suffer from the following problems: Polyurethane foam: Prolonged exposure to extremely low temperatures may lead to a decline in the material's mechanical properties, such as embrittlement and cracking. In a fire, it can burn and produce toxic fumes, potentially affecting the environment and personnel safety. Some foam materials may absorb moisture, leading to a decrease in thermal insulation performance. Foam glass: The high-temperature foaming process and its raw materials result in high production costs. Its weight increases construction difficulty and transportation costs. Foam glass is prone to breakage under mechanical impact. Perlite insulation materials: The natural mineral structure may lead to water absorption, thus affecting thermal insulation performance. Under high pressure, the structure may be compressed, leading to a decrease in performance. Aerogel composites: Due to the complex manufacturing process and expensive raw materials, aerogels are costly. Pure aerogels are very fragile and easily break due to mechanical stress, requiring composites with reinforcing materials for application. Glass fiber reinforced plastics: The manufacturing process of composite materials is complex, requiring precise process control to ensure consistent performance. High-quality glass fibers and their processing technology result in high costs. Some resin matrices may cause environmental problems during preparation and disposal. Aramid fiber composites: The material itself and processing costs are high, which limits large-scale applications. They are prone to absorbing moisture in humid environments, which may affect their thermal insulation performance. Due to the strong fiber properties, processing and handling are difficult and require specialized equipment. Summary of the Invention

[0004] To address the above issues and overcome the shortcomings of existing technologies, this invention provides a non-metallic composite insulation material for LNG storage tanks and its preparation method. The non-metallic composite insulation material of this invention utilizes a cross-linking reaction between polyisocyanate and polyether polyol. The polyurethane structure formed by this cross-linking reaction possesses a certain carbonization capability, allowing it to form a carbon layer at high temperatures, thus acting as an oxygen barrier and delaying combustion. The introduction of pentaerythritol hydroxymethyl phosphate, a component containing phosphate groups, decomposes at high temperatures to generate non-flammable gases and promotes the formation of a porous carbonized layer, further enhancing the flame-retardant properties of the material. This is because phosphates can form an effective flame-retardant barrier during combustion. Furthermore, the SiO2 composite aerogel contains siloxanes, which also form a barrier layer during combustion, providing a flame-retardant effect.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: The present invention proposes a non-metallic composite thermal insulation material for LNG storage tanks, wherein the non-metallic composite thermal insulation material comprises the following components in parts by weight: 30-50 parts of polyisocyanate (PAPI), 20-30 parts of polyether polyol, 5-15 parts of pentaerythritol hydroxymethyl phosphate, 5-10 parts of SiO2 composite aerogel, 1.5-3.5 parts of silicone oil, 1-5 parts of foaming agent, and 0.5-2 parts of catalyst;

[0006] Preferably, the catalyst comprises at least one selected from dibutyltin dilaurate, pentamethyldiethylenetriamine, dimethylcyclohexylamine, and triethylenediamine;

[0007] Preferably, the foaming agent includes at least one of pentafluorobutane and pentafluoropropane;

[0008] Preferably, the preparation method of the SiO2 composite aerogel specifically includes the following steps:

[0009] A1. After mixing ethylene glycol and dichloroethane, add boron trifluoride diethyl ether solution and stir at room temperature. After mixing evenly, add epichlorohydrin dropwise to the reaction system. After the addition is complete, raise the reaction temperature to carry out the polymerization reaction. After the reaction is completed, wait for the reaction system to cool to room temperature, wash with saturated sodium bicarbonate solution and deionized water until neutral, and distill under reduced pressure to obtain polyepoxychlorohydrin.

[0010] Preferably, in step A1, the volume ratio of ethylene glycol, boron trifluoride diethyl ether solution and dichloroethane is 5-10:5-10:70-90;

[0011] Preferably, in step A1, the volume ratio between epichlorohydrin and ethylene glycol is 20-50:5-10;

[0012] Preferably, in step A1, the polymerization reaction temperature is 40-60℃ and the polymerization reaction time is 8-12h;

[0013] A2. Dissolve the polyepoxychloropropane prepared in step A1 in anhydrous toluene, introduce flowing nitrogen gas, add triethylamine, mix well, add (3-aminopropyl)triethoxysilane, raise the reaction temperature to 60-80℃, react for 9-15 hours, and after the reaction system is cooled to room temperature, wash, concentrate under reduced pressure to obtain siloxane-modified polyepoxychloropropane.

[0014] Preferably, in step A2, the volume of triethylamine added is 3%-8% of the volume of anhydrous toluene;

[0015] Preferably, in step A2, the volume ratio between (3-aminopropyl)triethoxysilane and epichlorohydrin in step A1 is 1-3:4-10;

[0016] A3. Dissolve the siloxane-modified polyepoxychloropropane prepared in step A2 in DMF, add isocyanate compounds, raise the reaction temperature to 70-100℃, add dibutyltin dilaurate, and react for 12-18 hours. After the reaction is completed, wait for the reaction system to cool to room temperature, wash, concentrate under reduced pressure, and obtain polyurethane siloxane prepolymer.

[0017] Preferably, in step A3, the isocyanate compound includes at least one of cyclohexyl isocyanate, hexyl isocyanate, pentyl isocyanate, propyl isocyanate, tert-butyl isocyanate, n-butyl isocyanate, and cyclopentyl isocyanate.

[0018] Preferably, in step A3, the volume fraction of the isocyanate compound in the DMF is 7%-14%;

[0019] Preferably, in step A3, the mass-to-volume ratio of the dibutyltin dilaurate to the isocyanate compound is 10.5-20 mg: 7-14 mL;

[0020] A4. Dissolve methyltrimethoxysilane in an aqueous methanol solution, add oxalic acid to adjust the pH to 2-4, raise the reaction temperature to 50-70℃, and react for 4-6 hours. Then, add the polyurethane siloxane prepolymer prepared in step A3 to the reaction system, maintain the reaction temperature and continue the reaction for 6-8 hours. After the reaction system cools to room temperature, add an aqueous ammonia solution to the reaction system, adjust the pH of the reaction system to 7.5-8.0, age at 60℃ for 6-12 hours, and then prepare SiO2 composite aerogel by spray drying.

[0021] Preferably, in step A4, the volume ratio of methyltrimethoxysilane, methanol and deionized water is 1-3:3-10:1-4;

[0022] This invention also provides a method for preparing a non-metallic composite thermal insulation material for LNG storage tanks, specifically including the following steps:

[0023] S1. Dissolve diethyl hydroxymethyl phosphate in deionized water, add dilute hydrochloric acid aqueous solution to adjust the pH to 1, raise the reaction temperature to carry out the hydrolysis reaction. After the reaction is completed, let the reaction system cool to room temperature, add sodium hydroxide aqueous solution to neutralize the reaction system, dry it to obtain hydroxymethyl phosphate, dissolve it in deionized water to obtain hydroxymethyl phosphate solution, store at 4℃ for later use.

[0024] Preferably, in step S1, the mass concentration of the diethyl hydroxymethyl phosphate in deionized water is 0.1-0.168 g / mL;

[0025] Preferably, in step S1, the hydrolysis reaction temperature is 50-70℃ and the hydrolysis reaction time is 2-4h;

[0026] S2. Dissolve pentaerythritol in 1,4-dioxane, add Lewis acid catalyst, mix well, raise the reaction temperature and add the hydroxymethyl phosphate solution prepared in step S1 dropwise. After the addition is complete, carry out the first-order reaction. After the reaction is completed, continue to raise the temperature to carry out the second-order reaction. After the reaction is completed, filter, collect the reaction product, wash with 1,4-dioxane, dry and obtain pentaerythritol hydroxymethyl phosphate.

[0027] Preferably, the raw materials for preparing pentaerythritol hydroxymethyl phosphate are diethyl hydroxymethyl phosphate and pentaerythritol, and the mass ratio between diethyl hydroxymethyl phosphate and pentaerythritol is 1:0.32-0.4.

[0028] Preferably, in step S2, the mass of the Lewis acid catalyst added is 0.4%-0.6% of the mass of pentaerythritol;

[0029] Preferably, in step S2, the reaction temperature of the first-order reaction is 40-60℃, and the reaction time of the first-order reaction is 9-18h;

[0030] Preferably, in step S2, the reaction temperature of the second-order reaction is 80-90℃, and the reaction time of the second-order reaction is 4-8h;

[0031] S3. After mixing polyether polyol and pentaerythritol hydroxymethyl phosphate evenly, add catalyst, deionized water and foam stabilizer, mix evenly, add SiO2 composite aerogel, add polyisocyanate to the reaction system, mix at high speed, transfer to mold for foaming, and after curing, obtain non-metallic composite thermal insulation material.

[0032] The beneficial effects achieved by this invention are as follows:

[0033] This invention provides a non-metallic composite insulation material for LNG storage tanks and its preparation method. The non-metallic composite insulation material of this invention utilizes a cross-linking reaction of polyisocyanate and polyether polyol. The polyurethane structure formed by the cross-linking reaction of these two components has a certain carbonization ability, allowing it to form a carbon layer at high temperatures, acting as an oxygen barrier and thus delaying combustion. The introduction of pentaerythritol hydroxymethyl phosphate, a component containing phosphate groups, can decompose at high temperatures to generate non-flammable gases and promote the formation of a porous carbonized layer, further enhancing the flame-retardant properties of the material. This is because phosphates can form an effective flame-retardant barrier during combustion. The SiO2 composite aerogel contains siloxanes, which also form a barrier layer during combustion, playing a flame-retardant role. SiO2 composite aerogel is known for its extremely low density and thermal conductivity, significantly reducing the overall thermal conductivity of the material. Its porous structure can effectively trap air, thereby reducing heat conduction and convection. The porous structure of the composite material, through the foaming process in the reaction system, helps create microscopic pores in the material. These pores are filled with gas, forming thermal resistance. Therefore, this structural design not only increases the volume of the material but also effectively blocks the heat transfer path. The synergistic effect of the multi-component system, achieved through optimized chemical formulation, allows the components to complement each other, contributing to improved overall thermal resistance and physical-mechanical properties of the material. Attached Figure Description

[0034] Figure 1 The graphs show the thermal insulation performance results of the non-metallic composite thermal insulation materials prepared in Examples 1-3 and Comparative Examples 1-2 of this invention.

[0035] Figure 2 Thermogravimetric analysis results of the non-metallic composite thermal insulation materials prepared in Examples 1-3 and Comparative Examples 1-2 of this invention are shown in the figure.

[0036] Figure 3 The figures show the flame retardant performance results of the non-metallic composite thermal insulation materials prepared in Examples 1-3 and Comparative Examples 1-2 of this invention.

[0037] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the embodiments of the invention to explain the invention and do not constitute a limitation thereof. Detailed Implementation

[0038] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0039] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those familiar to those skilled in the art. Furthermore, any methods and materials similar to or equivalent to those described herein may be applied to this invention. The preferred embodiments and materials described herein are for illustrative purposes only and do not limit the scope of this application.

[0040] Unless otherwise specified, the experimental methods used in the following examples are conventional methods; unless otherwise specified, the experimental materials and test strains used in the following examples were purchased from commercial channels.

[0041] Example 1

[0042] This embodiment provides a non-metallic composite thermal insulation material for LNG storage tanks. The non-metallic composite thermal insulation material comprises the following components in parts by weight: 50 parts of phenylmethylene polyisocyanate (PM200), 30 parts of polyether polyol (330N), 10 parts of pentaerythritol hydroxymethyl phosphate, 10 parts of SiO2 composite aerogel, 3.5 parts of silicone oil, 3 parts of pentafluorobutane, and 1 part of dibutyltin dilaurate.

[0043] The preparation method of SiO2 composite aerogel specifically includes the following steps:

[0044] A1. Mix 10 mL of ethylene glycol and 80 mL of dichloroethane in a flask. Add 10 mL of boron trifluoride diethyl ether solution and stir at 300 rpm at room temperature. After mixing, add 50 mL of epichlorohydrin dropwise to the reaction system at 1 mL / min. After the addition is complete, raise the reaction temperature to 50 °C to carry out the polymerization reaction. After reacting for 10 h, let the reaction system cool to room temperature and transfer the reaction system to a separatory funnel. Add saturated sodium bicarbonate aqueous solution and shake. After standing and separating the layers, drain the aqueous phase. Repeat the washing with saturated sodium bicarbonate aqueous solution three times. Wash with deionized water according to the above method. After washing, collect the organic phase and add anhydrous magnesium sulfate to dry the organic phase to remove water. Filter to remove anhydrous magnesium sulfate from the organic phase. Distill the organic phase under reduced pressure and dry to obtain polyepoxychloropropane.

[0045] A2. Dissolve the polyepoxychloropropane prepared in step A1 in 100 mL of anhydrous toluene. After passing through flowing nitrogen gas, add 5 mL of triethylamine and stir at 200 rpm until homogeneous. Then add 15 mL of (3-aminopropyl)triethoxysilane and raise the reaction temperature to 80 °C. Continue stirring for 15 h. After the reaction cools to room temperature, transfer the reaction system to a separatory funnel and add 0.1 M dilute hydrochloric acid solution. Shake and allow to stand for separation. Discard the aqueous phase and wash three times with 0.1 M dilute hydrochloric acid solution. Wash with deionized water until neutral. After washing, collect the organic phase and add anhydrous magnesium sulfate to dry the organic phase. Filter to remove the anhydrous magnesium sulfate from the organic phase. Concentrate the organic phase under reduced pressure to obtain siloxane-modified polyepoxychloropropane.

[0046] A3. Dissolve the siloxane-modified polyepoxychloropropane prepared in A2 in 100 mL of DMF, add 14 mL of cyclohexyl isocyanate, stir and mix at 300 rpm, raise the reaction temperature to 100 °C, add 14 mg of dibutyltin dilaurate, and continue the reaction for 12 h. After the reaction system cools to room temperature, transfer the reaction system to a separatory funnel, add 0.1 M dilute hydrochloric acid aqueous solution and shake. After standing and separating the layers, drain the aqueous phase, wash three times with 0.1 M dilute hydrochloric acid aqueous solution, and wash with deionized water according to the above method until neutral. After washing, collect the organic phase, add anhydrous magnesium sulfate to dry the organic phase to remove water, filter to remove anhydrous magnesium sulfate from the organic phase, concentrate the organic phase under reduced pressure, and dry to obtain polyurethane siloxane prepolymer.

[0047] A4. Dissolve 15 mL of methyltrimethoxysilane in a methanol aqueous solution (50 mL of methanol and 20 mL of deionized water), add oxalic acid to adjust the pH to 2, raise the reaction temperature to 60°C, and react for 5 h. Then, add the polyurethane siloxane prepolymer prepared in step A3 to the reaction system, maintain the reaction temperature and continue the reaction for 8 h. After the reaction system cools to room temperature, add ammonia aqueous solution to the reaction system, adjust the pH of the reaction system to 8.0, age at 60°C for 6 h, and then prepare SiO2 composite aerogel by spray drying.

[0048] This embodiment provides a method for preparing a non-metallic composite thermal insulation material for LNG storage tanks, specifically including the following steps:

[0049] S1. Dissolve 5.0 g of diethyl hydroxymethyl phosphate in 50 mL of deionized water, add 0.1 M dilute hydrochloric acid solution to adjust the pH to 1, raise the reaction temperature to 60 °C to carry out the hydrolysis reaction, and after the reaction is carried out for 3 h, wait for the reaction system to cool to room temperature, add 0.1 M sodium hydroxide solution while stirring, continuously monitor the pH of the reaction system with a pH meter, and stop adding 0.1 M sodium hydroxide solution when the pH of the reaction system is 7. After freeze drying, hydroxymethyl phosphate is obtained, dissolved in 10 mL of deionized water to obtain hydroxymethyl phosphate solution, and stored at 4 °C for later use;

[0050] S2. Dissolve 2.0 g of pentaerythritol in 50 mL of 1,4-dioxane, add 12 mg of magnesium chloride hexahydrate as a Lewis acid catalyst, mix evenly at 500 rpm, raise the reaction temperature to 50 °C, and add the hydroxymethyl phosphate solution prepared in step S1 dropwise to the reaction system at 0.5 mL / min. Continue stirring to carry out the first-order reaction for 12 h. After the reaction is completed, continue to raise the reaction temperature to 85 °C to carry out the second-order reaction for 6 h. After the reaction is completed, filter, collect the reaction product, wash with 1,4-dioxane, and dry under reduced pressure to obtain pentaerythritol hydroxymethyl phosphate.

[0051] S3. Take 30 parts of polyether polyol 330N and 10 parts of pentaerythritol hydroxymethyl phosphate according to the weight, mix them evenly, add 1 part of dibutyltin dilaurate, 3 parts of pentafluorobutane and 3.5 parts of silicone oil, mix evenly at 2000 rpm, add 10 parts of SiO2 composite aerogel according to the weight, add 50 parts of polyisocyanate PM200 according to the weight, continue mixing at 2000 rpm for 10 seconds, transfer to a mold for foaming, and cure at 70℃ for 24 hours to obtain a non-metallic composite thermal insulation material.

[0052] Example 2

[0053] This embodiment provides a non-metallic composite thermal insulation material for LNG storage tanks. The non-metallic composite thermal insulation material comprises the following components in parts by weight: 30 parts of phenylmethylene polyisocyanate (PM200), 20 parts of polyether polyol (330N), 5 parts of pentaerythritol hydroxymethyl phosphate, 5 parts of SiO2 composite aerogel, 1.5 parts of silicone oil, 1 part of pentafluoropropane, and 2 parts of pentamethyldiethylenetriamine.

[0054] The preparation method of SiO2 composite aerogel specifically includes the following steps:

[0055] A1. Mix 5 mL of ethylene glycol and 90 mL of dichloroethane in a flask. Add 5 mL of boron trifluoride diethyl ether solution and stir at 300 rpm at room temperature. After mixing, add 35 mL of epichlorohydrin dropwise to the reaction system at 1 mL / min. After the addition is complete, raise the reaction temperature to 40 °C to carry out the polymerization reaction. After reacting for 12 h, let the reaction system cool to room temperature and transfer the reaction system to a separatory funnel. Add saturated sodium bicarbonate aqueous solution and shake. After standing and separating the layers, drain the aqueous phase. Repeat the washing with saturated sodium bicarbonate aqueous solution three times. Wash with deionized water according to the above method. After washing, collect the organic phase and add anhydrous magnesium sulfate to dry the organic phase to remove water. Filter to remove anhydrous magnesium sulfate from the organic phase. Distill the organic phase under reduced pressure and dry to obtain polyepoxychloropropane.

[0056] A2. Dissolve the polyepoxychloropropane prepared in step A1 in 100 mL of anhydrous toluene. After passing through flowing nitrogen gas, add 8 mL of triethylamine and stir at 200 rpm until homogeneous. Then add 10 mL of (3-aminopropyl)triethoxysilane and raise the reaction temperature to 80 °C. Continue stirring for 15 h. After the reaction cools to room temperature, transfer the reaction system to a separatory funnel and add 0.1 M dilute hydrochloric acid solution. Shake and allow to stand for separation. Discard the aqueous phase and wash three times with 0.1 M dilute hydrochloric acid solution. Wash with deionized water until neutral. After washing, collect the organic phase and add anhydrous magnesium sulfate to dry the organic phase. Filter to remove the anhydrous magnesium sulfate from the organic phase. Concentrate the organic phase under reduced pressure to obtain siloxane-modified polyepoxychloropropane.

[0057] A3. Dissolve the siloxane-modified polyepoxychloropropane prepared in A2 in 100 mL of DMF, add 10 mL of cyclopentyl isocyanate, stir and mix at 300 rpm, raise the reaction temperature to 100 °C, add 20 mg of dibutyltin dilaurate, and continue the reaction for 12 h. After the reaction system cools to room temperature, transfer the reaction system to a separatory funnel, add 0.1 M dilute hydrochloric acid aqueous solution and shake. After standing and separating the layers, drain the aqueous phase, wash three times with 0.1 M dilute hydrochloric acid aqueous solution, and then wash with deionized water according to the above method until neutral. After washing, collect the organic phase, add anhydrous magnesium sulfate to dry the organic phase to remove water, filter to remove anhydrous magnesium sulfate from the organic phase, concentrate the organic phase under reduced pressure, and dry to obtain polyurethane siloxane prepolymer.

[0058] A4. Dissolve 15 mL of methyltrimethoxysilane in a methanol aqueous solution (45 mL of methanol and 15 mL of deionized water), add oxalic acid to adjust the pH to 3, raise the reaction temperature to 70°C, and react for 4 h. Then, add the polyurethane siloxane prepolymer prepared in step A3 to the reaction system, maintain the reaction temperature and continue the reaction for 6 h. After the reaction system cools to room temperature, add ammonia aqueous solution to the reaction system, adjust the pH of the reaction system to 8.5, age at 60°C for 9 h, and then prepare SiO2 composite aerogel by spray drying.

[0059] This embodiment provides a method for preparing a non-metallic composite thermal insulation material for LNG storage tanks, specifically including the following steps:

[0060] S1. Dissolve 6.7g of diethyl hydroxymethyl phosphate in 50mL of deionized water, add 0.1M dilute hydrochloric acid solution to adjust the pH to 1, raise the reaction temperature to 50℃ to carry out the hydrolysis reaction, and after reacting for 4 hours, wait for the reaction system to cool to room temperature, add 0.1M sodium hydroxide solution while stirring, continuously monitor the pH of the reaction system with a pH meter, and stop adding 0.1M sodium hydroxide solution when the pH of the reaction system reaches 7. After freeze drying, hydroxymethyl phosphate is obtained, dissolved in 10mL of deionized water to obtain hydroxymethyl phosphate solution, stored at 4℃ for later use;

[0061] S2. Dissolve 2.45 g of pentaerythritol in 50 mL of 1,4-dioxane, add 10 mg of magnesium chloride hexahydrate as a Lewis acid catalyst, mix evenly at 500 rpm, raise the reaction temperature to 60 °C, and add the hydroxymethyl phosphate solution prepared in step S1 dropwise to the reaction system at 0.5 mL / min. Continue stirring to carry out the first-order reaction for 9 h. After the reaction is completed, continue to raise the reaction temperature to 80 °C to carry out the second-order reaction for 8 h. After the reaction is completed, filter, collect the reaction product, wash with 1,4-dioxane, and dry under reduced pressure to obtain pentaerythritol hydroxymethyl phosphate.

[0062] S3. Take 20 parts of polyether polyol 330N and 5 parts of pentaerythritol hydroxymethyl phosphate according to the weight, mix them evenly, add 2 parts of pentamethyldiethylenetriamine, 1 part of pentafluoropropane and 1.5 parts of silicone oil, mix evenly at 2000 rpm, add 5 parts of SiO2 composite aerogel according to the weight, add 30 parts of polyisocyanate PM200 according to the weight to the reaction system, continue mixing at 2000 rpm for 10 seconds, transfer to a mold for foaming, and cure at 70℃ for 24 hours to obtain a non-metallic composite thermal insulation material.

[0063] Example 3

[0064] This embodiment provides a non-metallic composite thermal insulation material for LNG storage tanks. The non-metallic composite thermal insulation material comprises the following components in parts by weight: 40 parts of phenylmethylene polyisocyanate (PM200), 25 parts of polyether polyol (330N), 8 parts of pentaerythritol hydroxymethyl phosphate, 15 parts of SiO2 composite aerogel, 2.5 parts of silicone oil, 5 parts of pentafluorobutane, and 0.5 parts of dimethylcyclohexylamine.

[0065] The preparation method of SiO2 composite aerogel specifically includes the following steps:

[0066] A1. Mix 5 mL of ethylene glycol and 70 mL of dichloroethane in a flask. Add 5 mL of boron trifluoride diethyl ether solution and stir at 300 rpm at room temperature until homogeneous. Add 20 mL of epichlorohydrin dropwise at 1 mL / min to the reaction system. After the addition is complete, raise the reaction temperature to 60 °C to carry out the polymerization reaction. After 8 hours of reaction, let the reaction system cool to room temperature and transfer the reaction system to a separatory funnel. Add saturated sodium bicarbonate aqueous solution and shake. After standing and separating the layers, drain the aqueous phase. Repeat the washing with saturated sodium bicarbonate aqueous solution three times. Wash with deionized water according to the above method. After washing, collect the organic phase and add anhydrous magnesium sulfate to dry the organic phase to remove water. Filter to remove anhydrous magnesium sulfate from the organic phase. Distill the organic phase under reduced pressure and dry to obtain polyepoxychlorohydrin.

[0067] A2. Dissolve the polyepoxychloropropane prepared in step A1 in 100 mL of anhydrous toluene. After passing flowing nitrogen gas through the solution, add 3 mL of triethylamine and stir at 200 rpm until homogeneous. Then add 5 mL of (3-aminopropyl)triethoxysilane and raise the reaction temperature to 80 °C. Continue stirring for 15 h. After the reaction has cooled to room temperature, transfer the reaction system to a separatory funnel and add 0.1 M dilute hydrochloric acid solution. Shake the mixture and allow it to stand for separation. Discard the aqueous phase and wash three times with 0.1 M dilute hydrochloric acid solution. Wash with deionized water until neutral. After washing, collect the organic phase and dry it with anhydrous magnesium sulfate. Filter the mixture to remove the anhydrous magnesium sulfate from the organic phase. Concentrate the organic phase under reduced pressure to obtain siloxane-modified polyepoxychloropropane.

[0068] A3. Dissolve the siloxane-modified polyepoxychloropropane prepared in A2 in 100 mL of DMF, add 7 mL of tert-butyl isocyanate, stir and mix at 300 rpm, raise the reaction temperature to 100 °C, add 10.5 mg of dibutyltin dilaurate, and continue the reaction for 12 h. After the reaction system cools to room temperature, transfer the reaction system to a separatory funnel, add 0.1 M dilute hydrochloric acid aqueous solution and shake. After standing and separating the layers, drain the aqueous phase, wash three times with 0.1 M dilute hydrochloric acid aqueous solution, and then wash with deionized water according to the above method until neutral. After washing, collect the organic phase, add anhydrous magnesium sulfate to dry the organic phase to remove water, filter to remove anhydrous magnesium sulfate from the organic phase, concentrate the organic phase under reduced pressure, and dry to obtain polyurethane siloxane prepolymer.

[0069] A4. Dissolve 15 mL of methyltrimethoxysilane in a methanol aqueous solution (35 mL of methanol and 10 mL of deionized water), add oxalic acid to adjust the pH to 4, raise the reaction temperature to 50°C, and react for 6 h. Then, add the polyurethane siloxane prepolymer prepared in step A3 to the reaction system, maintain the reaction temperature and continue the reaction for 7 h. After the reaction system cools to room temperature, add ammonia aqueous solution to the reaction system, adjust the pH of the reaction system to 7.5, age at 60°C for 12 h, and then prepare SiO2 composite aerogel by spray drying.

[0070] This embodiment provides a method for preparing a non-metallic composite thermal insulation material for LNG storage tanks, specifically including the following steps:

[0071] S1. Dissolve 8.4g of diethyl hydroxymethyl phosphate in 50mL of deionized water, add 0.1M dilute hydrochloric acid solution to adjust the pH to 1, raise the reaction temperature to 70℃ to carry out the hydrolysis reaction, and after the reaction is carried out for 2 hours, wait for the reaction system to cool to room temperature, add 0.1M sodium hydroxide solution while stirring, and continuously monitor the pH of the reaction system with a pH meter. When the pH of the reaction system reaches 7, stop adding 0.1M sodium hydroxide solution. After freeze drying, hydroxymethyl phosphate is obtained, dissolved in 10mL of deionized water to obtain hydroxymethyl phosphate solution, and stored at 4℃ for later use.

[0072] S2. Dissolve 2.7g of pentaerythritol in 50mL of 1,4-dioxane, add 15mg of magnesium chloride hexahydrate as a Lewis acid catalyst, mix evenly at 500rpm, raise the reaction temperature to 40℃, and add the hydroxymethyl phosphate solution prepared in step S1 dropwise to the reaction system at 0.5mL / min. Continue stirring to carry out the first-order reaction for 18h. After the reaction is completed, continue to raise the reaction temperature to 90℃ to carry out the second-order reaction for 4h. After the reaction is completed, filter, collect the reaction product, wash with 1,4-dioxane, and dry under reduced pressure to obtain pentaerythritol hydroxymethyl phosphate.

[0073] S3. Take 25 parts of polyether polyol 330N and 8 parts of pentaerythritol hydroxymethyl phosphate according to the weight, mix them evenly, add 0.5 parts of dimethylcyclohexylamine, 5 parts of pentafluorobutane and 2.5 parts of silicone oil, mix evenly at 2000 rpm, add 15 parts of SiO2 composite aerogel according to the weight, add 40 parts of polyisocyanate PM200 according to the weight to the reaction system, continue mixing at 2000 rpm for 10 seconds, transfer to a mold for foaming, and cure at 70℃ for 24 hours to obtain a non-metallic composite thermal insulation material.

[0074] Comparative Example 1

[0075] This comparative example provides a non-metallic composite thermal insulation material and its preparation method. The only difference between this material and Example 1 is that the SiO2 composite aerogel is replaced with the same weight of commercially available SiO2 aerogel (KNF-W50, analytical grade, Shanghai McLean Biochemical Technology Co., Ltd.). The remaining components and component contents are the same as in Example 1.

[0076] Comparative Example 2

[0077] This comparative example provides a non-metallic composite thermal insulation material and its preparation method. The only difference between this material and Example 1 is that the pentaerythritol hydroxymethyl phosphate is replaced with the same weight parts of DOPO (9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide) in the composition of the non-metallic composite thermal insulation material. The remaining components and their contents are the same as in Example 1.

[0078] Experimental Example 1

[0079] This experiment tested the thermal insulation performance of the non-metallic composite thermal insulation materials prepared in Examples 1-3 and Comparative Examples 1-2. The thermal insulation performance was characterized by the thermal conductivity. A 2200 thermal conductivity meter and a 5501 probe were used with a power of 6mW and a time of 80 seconds.

[0080] Figure 1The figures show the thermal insulation performance results of the non-metallic composite thermal insulation materials prepared in Examples 1-3 and Comparative Examples 1-2 of this invention. As shown in the figures, the thermal conductivity of the non-metallic composite thermal insulation materials prepared in Examples 1-3 is significantly lower than that of the thermal insulation materials prepared in Comparative Examples 1 and 2. In the non-metallic composite thermal insulation materials prepared in Examples 1-3, after grafting siloxane with hydroxyl-terminated polyepoxychloropropane, a polyurethane prepolymer material is formed with isocyanate. After acid hydrolysis with MTMS (methyltrimethoxysilane), a SiO2 aerogel with a cross-linked structure is prepared, which can improve its dispersibility in the polyurethane substrate and form a uniform porous structure. By forming air gaps to block heat flow, the material has excellent thermal insulation performance.

[0081] Experiment Example 2

[0082] This experiment tested the flame retardant properties of the non-metallic composite insulation materials prepared in Examples 1-3 and Comparative Examples 1-2. The flame retardant properties were characterized by thermogravimetric analysis (TGA) and limiting oxygen index (LOI) determination. TGA was performed using a NETZSCH209F1 thermogravimetric analyzer under a nitrogen atmosphere. The test temperature ranged from 30 to 750°C, with a heating rate of 10°C / min. The non-metallic composite insulation materials prepared in Examples 1-3 and Comparative Examples 1-2 were fabricated into 100×10×10mm diameter sheets. 3 For the samples, the LOI was tested using an M606B digital oxygen index analyzer, in accordance with GB / T2406-93.

[0083] Figure 2 The figures show the thermogravimetric analysis results of the non-metallic composite thermal insulation materials prepared in Examples 1-3 and Comparative Examples 1-2 of the present invention. As shown in the figures, the non-metallic composite thermal insulation material prepared in Example 1 of the present invention has a slower rate of thermogravimetric loss in the early stage of heating and a lower amount of thermogravimetric loss in the later stage. In contrast, the thermal insulation material prepared in Comparative Example 1 has a higher rate of thermogravimetric loss, especially Comparative Example 1, which shows a significantly increased rate of heat loss in the early stage of heating.

[0084] Figure 3 The figures show the flame retardant performance results of the non-metallic composite thermal insulation materials prepared in Examples 1-3 and Comparative Examples 1-2 of this invention. As shown in the figures, the limiting oxygen index of the non-metallic composite thermal insulation materials prepared in Examples 1-3 of this invention is 26.58%, 27.21%, and 26.44%, respectively, which is significantly higher than that of the non-metallic composite thermal insulation materials prepared in Comparative Examples 1 and 2. This indicates that due to the increased phosphorus content in the non-metallic composite thermal insulation materials prepared in this invention, combustible components such as H· and ·OH can be removed from the air during combustion. The continuously dispersed SiO2 aerogel in the matrix can effectively block the diffusion of combustible substances and improve the flame retardant performance.

[0085] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention.

[0086] The present invention and its embodiments have been described above. This description is not restrictive, and the accompanying drawings are only one embodiment of the present invention. The actual application is not limited to this. In conclusion, if those skilled in the art are inspired by this description and design similar methods and embodiments without departing from the spirit of the present invention, they should all fall within the protection scope of the present invention.

Claims

1. A non-metallic composite thermal insulation material for LNG storage tanks, characterized by: The non-metal composite thermal insulation material comprises the following components in parts by weight: 30-50 parts of polyisocyanate, 20-30 parts of polyether polyol, 5-15 parts of pentaerythritol hydroxymethyl phosphate, 5-10 parts of SiO2 composite aerogel, 1.5-3.5 parts of silicone oil, 1-5 parts of foaming agent, and 0.5-2 parts of catalyst; The catalyst comprises at least one of dibutyltin dilaurate, pentamethyldiethylene triamine, dimethylcyclohexylamine, and triethylene diamine; The foaming agent comprises at least one of pentafluorobutane, pentafluoropropane, and monofluorodichloroethane; The preparation method of the SiO2 composite aerogel specifically comprises the following steps: A1, mixing ethylene glycol and dichloroethane, adding boron trifluoride ether solution, stirring at room temperature, adding epoxy chloropropane drop by drop into the reaction solvent, increasing the reaction temperature after the addition is completed, and performing polymerization reaction, cooling the reaction system to room temperature after the reaction is completed, washing with saturated sodium bicarbonate solution and deionized water until neutral, and performing reduced pressure distillation to obtain polyepoxy chloropropane; A2, dissolving the polyepoxy chloropropane prepared in step A1 in anhydrous toluene, introducing flowing nitrogen, adding triethylamine, mixing, adding (3-aminopropyl) triethoxysilane, increasing the reaction temperature to 60-80℃, and reacting for 9-15h, then cooling the reaction system to room temperature, washing, and performing reduced pressure concentration to obtain siloxane modified polyepoxy chloropropane; A3, dissolving the siloxane modified polyepoxy chloropropane prepared in step A2 in DMF, adding an isocyanate compound, increasing the reaction temperature to 70-100℃, adding dibutyltin dilaurate, and reacting for 12-18h, then cooling the reaction system to room temperature after the reaction is completed, washing, and performing reduced pressure concentration to obtain a polyurethane siloxane prepolymer; A4, dissolving methyltrimethoxysilane in a methanol aqueous solution, adding oxalic acid to adjust the pH to 2-4, increasing the reaction temperature to 50-70℃, reacting for 4-6h, then adding the polyurethane siloxane prepolymer prepared in step A3 into the reaction system, continuously reacting for 6-8h while maintaining the reaction temperature, then cooling the reaction system to room temperature, adding an ammonia solution into the reaction system to adjust the pH of the reaction system to 7.5-8.0, and aging at 60℃ for 6-12h, and then preparing SiO2 composite aerogel by a spray drying method.

2. The nonmetallic composite thermal insulation material for LNG storage tank according to claim 1, characterized in that: In step A1, the volume ratio among the ethylene glycol, the boron trifluoride ether solution, and the dichloroethane is 5-15:5-10:70-90; and the volume ratio between the epoxy chloropropane and the ethylene glycol is 20-50:5-10.

3. The nonmetallic composite thermal insulation material for LNG storage tank according to claim 2, characterized in that: In step A1, the reaction temperature of the polymerization reaction is 40-60℃, and the reaction time of the polymerization reaction is 8-12h.

4. The nonmetallic composite thermal insulation material for LNG storage tank according to claim 3, characterized in that: In step A2, the addition volume of the triethylamine is 3%-8% of the volume of the anhydrous toluene; and the volume ratio between the (3-aminopropyl) triethoxysilane and the epoxy chloropropane in step A1 is 1-3:4-10.

5. The nonmetallic composite thermal insulation material for LNG storage tanks according to claim 4, characterized by: In step A3, the isocyanate compound includes at least one of cyclohexyl isocyanate, hexyl isocyanate, pentyl isocyanate, propyl isocyanate, tert-butyl isocyanate, n-butyl isocyanate, and cyclopentyl isocyanate; the volume fraction of the isocyanate compound in DMF is 7%-14%; and the mass-volume ratio between the dibutyltin dilaurate and the isocyanate compound is 10.5-20 mg:7-14 mL.

6. The nonmetallic composite thermal insulation material for LNG storage tanks according to claim 5, characterized by: In step A4, the volume ratio among the methyl trimethoxysilane, methanol and deionized water is 1-3:3-10:1-4.

7. A method of producing a non-metallic composite thermal insulation material for LNG storage tanks according to claim 6, characterized in that: Specifically comprising the following steps: S1, dissolve hydroxymethyl phosphonic acid diethyl ester in deionized water, add dilute hydrochloric acid aqueous solution, adjust the pH to 1, increase the reaction temperature to carry out hydrolysis reaction, after the reaction is completed, after the reaction system is cooled to room temperature, add sodium hydroxide aqueous solution, neutralize the reaction system, dry to obtain hydroxymethyl phosphonic acid, dissolve in deionized water to obtain hydroxymethyl phosphonic acid solution, store at 4℃ for standby use; S2, dissolve pentaerythritol in 1,4-dioxane, add Lewis acid catalyst, mix uniformly, then add the hydroxymethyl phosphonic acid solution prepared in step S1 dropwise, after the dropwise addition is completed, carry out first-order reaction, after the reaction is completed, continue to increase the temperature to carry out second-order reaction, after the reaction is completed, filter, collect the reaction product, wash with 1,4-dioxane, dry to obtain pentaerythritol hydroxymethyl phosphonate; S3, mix polyether polyol and pentaerythritol hydroxymethyl phosphonate uniformly, then add catalyst, deionized water and foam stabilizer, mix uniformly, then add SiO2 composite aerogel, add polyisocyanate, mix at high speed, transfer to a mold to carry out foaming, after curing, obtain a non-metal composite thermal insulation material.

8. The method of claim 7, wherein the method further comprises: In step S1, the mass concentration of the hydroxymethyl phosphonic acid diethyl ester in deionized water is 0.1-0.168 g / mL; the reaction temperature of the hydrolysis reaction is 50-70℃, and the reaction time of the hydrolysis reaction is 2-4 h. ​ 9. A method for preparing a non-metallic composite thermal insulation material for LNG storage tanks according to claim 8, characterized in that: The preparation raw material of the pentaerythritol hydroxymethyl phosphonate is hydroxymethyl phosphonic acid diethyl ester and pentaerythritol, and the mass ratio between the hydroxymethyl phosphonic acid diethyl ester and the pentaerythritol is 1:0.32-0.4; in step S2, the added mass of the Lewis acid catalyst is 0.4%-0.6% of the mass of the pentaerythritol; the reaction temperature of the first-order reaction is 40-60℃, and the reaction time of the first-order reaction is 9-18 h; the reaction temperature of the second-order reaction is 80-90℃, and the reaction time of the second-order reaction is 4-8 h.

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