Modified expanded perlite thermal insulation material for LNG storage tank and preparation method thereof

Abstract

This invention discloses a modified expanded perlite insulation material for LNG storage tanks and its preparation method. The raw materials of the modified expanded perlite insulation material include expanded perlite and functional components in a mass ratio of 1.2-1.9. The functional components include the following components in mass percentage: 15-25% hydrophobic modifier, 5-10% thermal insulation enhancer, 20-30% binder, 35-50% solvent, and 1-5% dispersant. The modified expanded perlite insulation material provided by this invention has low thermal conductivity at both 0℃ and -162℃, exhibiting excellent thermal insulation performance and meeting the requirements for use in LNG storage tanks.

Description

Technical Field

[0001] This invention relates to the field of thermal insulation materials for LNG storage tanks. More specifically, this invention relates to a modified expanded perlite thermal insulation material for LNG storage tanks and its preparation method. Background Technology

[0002] Liquefied natural gas (LNG) is stored at temperatures as low as -162°C, placing extremely high demands on the thermal insulation and cold preservation performance of storage tanks. Currently, large LNG storage tanks generally adopt a prestressed concrete full-containment tank structure, and the insulation layer of its inner tank wall mainly uses the following material systems: 1. Expanded perlite particle filling system: Loose expanded perlite particles are filled between the inner and outer tank walls, and a vacuum is drawn to form an insulating space. This system is complex to construct, the particles are prone to settling, maintaining a high vacuum level over a long period is difficult, and it requires an extremely thick filling layer (usually exceeding 1 meter), occupying a large amount of space. 2. Polyurethane / polyisocyanurate (PUR / PIR) foam boards: Multiple layers are bonded together with adhesives. This type of material is prone to shrinkage and aging at low temperatures, posing a flammability risk, and the rigid boards have many seams, easily forming thermal bridges, and have poor adaptability to complex curved surfaces. 3. Glass wool / rock wool: Used in non-core low-temperature areas, it has strong moisture absorption, and its insulation performance drops sharply once it becomes damp.

[0003] The existing technology has the following main defects: (1) The materials are heavy or the construction is complicated, and they occupy a lot of space; (2) There are many joints in the rigid plates, the thermal performance is uneven, and thermal bridges are easily formed; (3) Organic materials have aging and flammability hazards; (4) Inorganic materials are easy to absorb moisture and their performance degrades at low temperatures; (5) The fit to the curved surface of the storage tank, especially the dome and irregular parts, is not good.

[0004] Therefore, there is an urgent need to develop a new type of high-performance LNG storage tank insulation material that is lightweight, flexible, can be tightly bonded, hydrophobic, and suitable for construction on complex curved surfaces. Summary of the Invention

[0005] One object of the present invention is to solve at least the above-mentioned problems and to provide at least the advantages that will be described later.

[0006] To achieve these objectives and other advantages according to the present invention, a modified expanded perlite insulation material for LNG storage tanks is provided, the raw materials of which include expanded perlite and functional components in a mass ratio of 1.2-1.9; the functional components include the following components in mass percentage: 15-25% hydrophobic modifier, 5-10% insulation enhancer, 20-30% binder, 35-50% solvent, and 1-5% dispersant.

[0007] Preferably, the expanded perlite has a particle size of 200-400 mesh, a porosity of ≥85%, and a thermal conductivity of ≤0.05W / (m•k).

[0008] Preferably, the hydrophobic modifier is isobutyltriethoxysilane, the heat insulation enhancer is silicon dioxide, the adhesive is polyurethane emulsion, the solvent is ethanol, and the dispersant is ethylene glycol.

[0009] Another object of the present invention is to provide a method for preparing a modified expanded perlite insulation material for LNG storage tanks, comprising the following steps: S1. Preparation of functional ink: The expanded perlite, the hydrophobic modifier, the heat insulation enhancer, the solvent, and the dispersant are mixed and dispersed by ball milling or high-speed shearing for 1-2 hours to form a uniform slurry; the binder is slowly added to the slurry under low-speed stirring and stirring is continued for more than 30 minutes to obtain a functional ink with a viscosity of 1000-3000 mPa·s. S2. Screen printing film formation: Select an 80-150 mesh screen and coat it with a thick photosensitive emulsion to make a screen; place the functional ink on the screen and use a polyurethane squeegee with a hardness of 60-75° to squeegee at a speed of 0.4-0.6 m / s and a screen distance of 1.0-2.0 mm to form a wet film on the substrate. S3. Drying and curing: Place the substrate with the wet film printed on it in a drying oven, dry it and cool it to room temperature; S4. Post-processing: Remove the printing substrate to obtain the heat insulation material, coat one side of the heat insulation material with adhesive, cover with a protective film, and roll it up for later use.

[0010] Preferably, step S1 further includes pretreatment of the expanded perlite: first, the expanded perlite is sieved to obtain 200-400 mesh fine powder; then, it is dried at 100°C for 10-30 minutes.

[0011] Preferably, step S1 specifically includes: S11. One-time mixing: The expanded perlite, the hydrophobic modifier, the dispersant and the solvent are mixed and dispersed for 30-60 minutes; S12. Secondary mixing: Add the heat insulation enhancer to the slurry after the first mixing, and continue mixing and dispersing for 30-60 minutes; S13. Viscosity adjustment: Under low-speed stirring, the binder is slowly added to the slurry after secondary mixing, and stirring is continued for more than 30 minutes to obtain a functional ink with a viscosity of 1000-3000 mPa·s.

[0012] Preferably, a ball mill or a high-speed shear disperser is used for mixing in steps S11 and S12.

[0013] Preferably, in step S2, the printing substrate is a PET release film or release paper.

[0014] Preferably, in step S5, the substrate with the wet film printed on it is dried in a drying oven in three steps, specifically including: S51. Allow the surface to stand for 5-15 minutes at 25-40℃ and wind speed <1m / s to dry. S52. Dry at 50-70℃ for 20-40 minutes; S53, cure at 80-100℃ for 10-20 minutes.

[0015] The present invention has at least the following beneficial effects: 1. The modified expanded perlite insulation material for LNG storage tanks and its preparation method provided by the present invention can be prepared into a thin film insulation material with a thickness of 0.1-0.5 mm by screen printing. It has low thermal conductivity at 0℃ and -162℃ and has excellent thermal insulation performance.

[0016] 2. The modified expanded perlite insulation material for LNG storage tanks and its preparation method provided by this invention utilize a stepwise mixing process in the preparation of the functional ink. In the first mixing, a hydrophobic modifier and expanded perlite are first mixed in the presence of a solvent and a dispersant, providing sufficient time and medium conditions for silane molecules to fully wet, adsorb, and initially react on the large porous surface of the perlite. In the second mixing, a heat insulation enhancer is added, which helps to uniformly disperse the heat insulation enhancer in the slurry system and maximize its heat insulation enhancement effect. Finally, the viscosity is adjusted by a binder, resulting in a functional ink with good stability.

[0017] 3. The modified expanded perlite insulation material for LNG storage tanks and its preparation method provided by this invention employ a stepped drying and curing process. The first stage involves surface drying to gently remove solvents and prevent surface defects. The second stage involves drying at 50-70℃ to deeply remove solvents and eliminate internal stress. The third stage involves curing at 80-100℃, which effectively activates the reactive groups of polyurethane molecules, promoting a full chemical cross-linking reaction and forming a three-dimensional network structure. Simultaneously, the high temperature provides energy for the hydrophobic modifier's hydrolysis and condensation reaction with the hydroxyl groups on the expanded perlite surface, ensuring that silanes are firmly grafted in the form of chemical bonds, achieving a durable and efficient hydrophobic effect.

[0018] 4. The modified expanded perlite insulation material for LNG storage tanks and its preparation method provided by the present invention can accurately and flexibly construct insulation layers of arbitrary design thickness from millimeters to centimeters by bonding multiple layers on the tank wall surface, and can completely fit the curved surface of the tank wall, avoiding the limitations of using a single thick plate, and greatly optimizing the material usage and insulation design.

[0019] Other advantages, objectives and features of the present invention will become apparent in part from the following description, and in part from those skilled in the art through study and practice of the invention. Detailed Implementation

[0020] The present invention will be further described in detail below with reference to embodiments, so that those skilled in the art can implement it based on the description.

[0021] It should be noted that, unless otherwise specified, the experimental methods described in the following implementation plan are all conventional methods, and the reagents and materials described are all commercially available unless otherwise specified.

[0022] Example 1 This embodiment provides a modified expanded perlite insulation material C1, the specific preparation steps of which are as follows: S1. Preparation of functional inks: S1. Preparation of functional inks: Weigh the raw materials: Weigh 150g of expanded perlite, 15g of isobutyltriethoxysilane, 7g of silica, 27g of polyurethane emulsion, 48g of ethanol, and 3g of ethylene glycol. The mass ratio of expanded perlite to functional components is 1.5.

[0023] S11. First mixing: Add the weighed expanded perlite, isobutyltriethoxysilane, ethylene glycol and ethanol to a ball mill and mix at 200 rpm for 40 minutes.

[0024] S12. Secondary mixing: Add the weighed silica to the slurry after the first mixing, and continue to disperse by ball milling at 200 rpm for 40 minutes.

[0025] S13. Viscosity adjustment: Transfer the slurry to a mixing tank and slowly add polyurethane emulsion while stirring at low speed (200 rpm). After the addition is complete, continue stirring for 40 minutes to obtain a uniform paste-like functional ink. The viscosity of the ink at 25℃ and 20 rpm was measured to be 1800 mPa·s using a rotational viscometer. The slurry showed no significant sedimentation or stratification after standing for 30 minutes.

[0026] S2. Screen Printing for Film Formation: A 120-mesh screen is selected to create a screen with a dry film thickness of approximately 150 micrometers. PET release film is used as the printing substrate, and a 70° hardness polyurethane squeegee is used. The screen distance is set to 1.5 mm, and the printing speed is 0.4 m / s.

[0027] S3. Drying and curing: Place the substrate with the wet film printed on it in a drying oven and let it stand at 35°C for 10 minutes, dry at 60°C for 30 minutes, and cure at 85°C for 15 minutes.

[0028] S4. Post-processing: After cooling, peel off the substrate, coat one side with flexible epoxy adhesive and cover with a protective film, and roll up to obtain a thermal insulation material roll C1 with a thickness of about 0.28 mm.

[0029] Example 2 This embodiment provides a modified expanded perlite insulation material C2, the specific preparation steps of which are as follows: S1. Preparation of functional inks: Weigh the raw materials: Weigh 150g of expanded perlite, 20g of isobutyltriethoxysilane, 8g of silica, 25g of polyurethane emulsion, 44g of ethanol, and 3g of ethylene glycol. The mass ratio of expanded perlite to functional components is 1.5.

[0030] S11, First Mixing: Add expanded perlite, isobutyltriethoxysilane, ethylene glycol and ethanol to a high shear disperser and disperse at 1000 rpm for 30 minutes.

[0031] S12, Secondary mixing: Add silica and continue to disperse at 1200 rpm for 40 minutes.

[0032] S13. Viscosity adjustment: Reduce the rotation speed to 800 rpm, slowly add polyurethane emulsion, and continue stirring for 30 minutes after the addition is complete to obtain a uniform paste-like functional ink; the viscosity of the ink at 25℃ and 20 rpm was measured to be 2200 mPa·s using a rotational viscometer, and the slurry showed no significant sedimentation or stratification after standing for 30 minutes.

[0033] S2. Screen printing film formation: Use a 120-mesh screen to make a screen with a dry film thickness of about 150 micrometers for the photosensitive emulsion. The squeegee angle is 65°, the screen distance is 1.2mm, and the speed is 0.5 m / s.

[0034] S3. Drying and curing: Place the substrate with the wet film printed on it in a drying oven and let it stand at 30°C for 12 minutes, dry at 65°C for 25 minutes, and cure at 90°C for 12 minutes.

[0035] S4. Post-processing: After cooling, peel off the substrate, coat one side with flexible epoxy adhesive and cover with a protective film, and then roll it up to obtain thermal insulation material C2 with a thickness of about 0.32mm.

[0036] Example 3 This embodiment provides a modified expanded perlite insulation material C3, the specific preparation steps of which are as follows: S1. Preparation of functional inks: Weigh the raw materials: Weigh 130g of expanded perlite, 20g of isobutyltriethoxysilane, 8g of silica, 25g of polyurethane emulsion, 44g of ethanol, and 3g of ethylene glycol. The mass ratio of expanded perlite to functional components is 1.3.

[0037] S11, First mixing: Ball mill and mix expanded perlite, isobutyltriethoxysilane, ethylene glycol and ethanol for 50 minutes.

[0038] S12, Secondary mixing: Add silica and continue ball milling for 40 minutes.

[0039] S13. Viscosity adjustment: Transfer to a mixing tank, add polyurethane emulsion, stir for 40 minutes, and continue stirring for 30 minutes after the addition is complete to obtain a uniform paste-like functional ink; the viscosity of the ink at 25℃ and 20 rpm was measured to be 1200 mPa·s using a rotational viscometer, and the slurry showed no significant sedimentation or stratification after standing for 30 minutes.

[0040] S2. Screen printing film formation: Use a 120-mesh screen to make a screen with a dry film thickness of about 150 micrometers for the photosensitive emulsion. The squeegee angle is 65°, the screen distance is 1.2mm, and the speed is 0.5 m / s.

[0041] S3. Drying and curing: Place the substrate with the wet film printed on it in a drying oven and let it stand at 40°C for 10 minutes, dry at 55°C for 40 minutes, and cure at 95°C for 15 minutes.

[0042] S4. Post-processing: After cooling, peel off the substrate, coat one side with flexible epoxy adhesive and cover with a protective film, and then roll it up to obtain thermal insulation material C3 with a thickness of about 0.38mm.

[0043] Example 4 This embodiment provides a modified expanded perlite insulation material C4, the specific preparation steps of which are as follows: S1. Preparation of functional inks: Weigh the raw materials: Weigh 162g of expanded perlite, 18g of isobutyltriethoxysilane, 7.2g of silica, 22.5g of polyurethane emulsion, 40.5g of ethanol, and 1.8g of ethylene glycol. The mass ratio of expanded perlite to functional components is 1.8.

[0044] S11, First Mixing: Add expanded perlite, isobutyltriethoxysilane, ethylene glycol and ethanol to a high shear disperser and disperse at 1000 rpm for 40 minutes.

[0045] S12, Secondary mixing: Add silica and continue to disperse at 1200 rpm for 40 minutes.

[0046] S13. Viscosity adjustment: Reduce the rotation speed to 800 rpm, slowly add polyurethane emulsion, and continue stirring for 30 minutes after the addition is complete to obtain a uniform paste-like functional ink; the viscosity of the ink at 25℃ and 20 rpm was measured to be 1800 mPa·s using a rotational viscometer, and the slurry showed no significant sedimentation or stratification after standing for 30 minutes.

[0047] S2. Screen printing film formation: Select a 100-mesh screen to make a screen with a dry film thickness of about 150 micrometers. The squeegee angle is 60°, the screen distance is 2.0mm, and the squeegee speed is 0.3 m / s.

[0048] S3. Drying and curing: Place the substrate with the wet film printed on it in a drying oven and let it stand at 40°C for 8 minutes, dry at 55°C for 40 minutes, and cure at 95°C for 10 minutes.

[0049] S4. Post-processing: After cooling, peel off the substrate, coat one side with flexible epoxy adhesive and cover with a protective film, and then roll it up to obtain thermal insulation material C4 with a thickness of about 0.35mm.

[0050] Comparative Example 1 Traditional loosely filled expanded perlite particles (3-6mm particle size).

[0051] Comparative Example 2 Commercially available flexible rubber and plastic insulation cotton (10mm thick).

[0052] Performance tests were conducted on the above embodiments and comparative examples, and the results are shown in Table 1: Table 1 Performance Test Results Based on the performance test results above, the modified expanded perlite insulation material prepared using screen printing technology exhibits significant advantages in core indicators such as thermal conductivity (room temperature / low temperature), bulk density, water absorption rate, low-temperature cycling stability, and hydrophobic properties. Its advantages are particularly prominent in the synergy of lightweight and high strength, and low-temperature insulation stability. This product is fully suitable for the special operating conditions of LNG storage tanks, including -162℃ low temperature, high humidity, and long-term alternating hot and cold conditions. Its overall performance surpasses that of similar specialized products currently on the market, while also considering large-scale production characteristics, making it more valuable for engineering applications.

[0053] During the actual construction of LNG storage tanks, the inner tank wall is first sandblasted to remove rust to a cleanliness level of Sa2.5, ensuring the surface is dry and free of oil. Construction begins at the bottom of the tank. The protective film on the back of the insulation material of this invention is peeled off, and the side coated with adhesive is tightly adhered to the tank wall. Immediately, a hard rubber roller is used to evenly roll the material from the center outwards, thoroughly expelling air between layers and ensuring 100% adhesion. When applying the second layer, all longitudinal and transverse seams must be staggered from the seams of the first layer by at least 100mm. Following this staggered seam principle, layers are applied upwards until the designed total insulation thickness is achieved. Finally, an anti-aging, moisture-proof sealing protective layer (such as an aluminum foil composite layer or a special coating) can be applied to the outermost side of the entire insulation layer to complete the construction of the entire cold insulation system.

[0054] Although embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for the present invention. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details and embodiments shown and described herein.

Claims

1. A modified expanded perlite insulation material for LNG storage tanks, characterized in that, The raw materials of the thermal insulation material include expanded perlite and functional components, with a mass ratio of 1.2-1.

9. The functional components include the following components by mass percentage: 15-25% hydrophobic modifier, 5-10% thermal insulation enhancer, 20-30% binder, 35-50% solvent, and 1-5% dispersant.

2. The modified expanded perlite insulation material for LNG storage tanks as described in claim 1, characterized in that, The expanded perlite has a particle size of 200-400 mesh, a porosity of ≥85%, and a thermal conductivity of ≤0.05W / (m•k).

3. The modified expanded perlite insulation material for LNG storage tanks as described in claim 1, characterized in that, The hydrophobic modifier is isobutyltriethoxysilane, the heat insulation enhancer is silicon dioxide, the adhesive is polyurethane emulsion, the solvent is ethanol, and the dispersant is ethylene glycol.

4. A method for preparing the modified expanded perlite insulation material for LNG storage tanks as described in claim 1, characterized in that, Includes the following steps: S1. Preparation of functional ink: The expanded perlite, the hydrophobic modifier, the heat insulation enhancer, the solvent, and the dispersant are mixed and dispersed by ball milling or high-speed shearing for 1-2 hours to form a uniform slurry; the binder is slowly added to the slurry under low-speed stirring and stirring is continued for more than 30 minutes to obtain a functional ink with a viscosity of 1000-3000 mPa·s. S2. Screen printing film formation: Select an 80-150 mesh screen and coat it with a thick photosensitive emulsion to make a screen; place the functional ink on the screen and use a polyurethane squeegee with a hardness of 60-75° to squeegee at a speed of 0.4-0.6 m / s and a screen distance of 1.0-2.0 mm to form a wet film on the substrate. S3. Drying and curing: Place the substrate with the wet film printed on it in a drying oven, dry it and cool it to room temperature; S4. Post-processing: Remove the printing substrate to obtain the heat insulation material, coat one side of the heat insulation material with adhesive, cover with a protective film, and roll it up for later use.

5. The material for preparing the modified expanded perlite insulation material for LNG storage tanks as described in claim 4, characterized in that, Step S1 also includes pretreatment of the expanded perlite: first, the expanded perlite is sieved to obtain 200-400 mesh fine powder; then, it is dried at 100℃ for 10-30 minutes.

6. The modified expanded perlite insulation material for LNG storage tanks as described in claim 4, characterized in that, Step S1 specifically includes: S11. One-time mixing: The expanded perlite, the hydrophobic modifier, the dispersant and the solvent are mixed and dispersed for 30-60 minutes; S12. Secondary mixing: Add the heat insulation enhancer to the slurry after the first mixing, and continue mixing and dispersing for 30-60 minutes; S13. Viscosity adjustment: Under low-speed stirring, the binder is slowly added to the slurry after secondary mixing, and stirring is continued for more than 30 minutes to obtain a functional ink with a viscosity of 1000-3000 mPa·s.

7. The modified expanded perlite insulation material for LNG storage tanks as described in claim 6, characterized in that, In steps S11 and S12, a ball mill or a high-speed shear disperser is used for mixing.

8. The modified expanded perlite insulation material for LNG storage tanks as described in claim 4, characterized in that, In step S2, the printing substrate is a PET release film or release paper.

9. The modified expanded perlite insulation material for LNG storage tanks as described in claim 4, characterized in that, In step S5, the substrate with the wet film printed on it is dried in a drying oven in three steps, specifically including: S51. Allow the surface to stand for 5-15 minutes at 25-40℃ and wind speed <1m / s to dry. S52. Dry at 50-70℃ for 20-40 minutes; S53, cure at 80-100℃ for 10-20 minutes.

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