Thermal insulation material of box special for pathogenic microorganism sample transportation and preparation method of thermal insulation material

Abstract

The invention provides a thermal insulation material of a box special for pathogenic microorganism sample transportation and a preparation method of the thermal insulation material, and relates to the technical field of thermal insulation materials. The thermal insulation material comprises 100 to 105 parts of isocyanate, 15 to 20 parts of modified sunflower seed oil polyol, 40 to 45 parts of castor oil polyol, 10 to 15 parts of polyether polyol, 6 to 8 parts of modified rock wool fiber, 4 to 6 parts of surface grafting type chopped aramid fiber, 3 to 5 parts of a flame retardant, 1 to 2 parts of polysilsesquioxane, 2 to 3 parts of a chain extender, 1.5 to 2 parts of an organosilicon surfactant and 3 to 5 parts of a foaming agent. 0.8 to 1.2 parts of a hydrolysis-resistant agent and 0.1 to 0.3 part of fumed silica. The thermal insulation material can simultaneously realize ultralow heat conductivity coefficient, excellent impact resistance and compression strength and excellent environmental stability.

Description

Technical Field

[0001] This invention relates to the field of thermal insulation materials technology, specifically to a thermal insulation material for a special box for transporting pathogenic microorganism samples and its preparation method. Background Technology

[0002] The viability and integrity of biological samples are highly dependent on temperature stability during transport. These samples typically require transport in a specific constant-temperature environment of 2-8°C or lower. Any temperature fluctuations or instability can lead to sample degradation, inactivation, or mutation, posing a significant risk to medical diagnostics, vaccine delivery, and biological research. Therefore, the insulation material of the transport container is a key component ensuring its core function. It must not only possess excellent passive thermal insulation performance to extend the cold-keeping time, but also meet the mechanical integrity, durability, and surface sterilizability necessary as a primary biosafety barrier.

[0003] Currently, the insulation layer of commercial biosample transport boxes generally uses rigid foam materials such as polyurethane (PU) or polystyrene (EPS). Although these traditional materials have a low initial thermal conductivity (approximately 0.02-0.04 W / (m·K)), their inherent defects are becoming increasingly apparent under harsh transportation scenarios: First, in pursuit of even lower thermal conductivity, it is usually necessary to further increase the porosity of the material or reduce its density, which directly leads to a sharp decline in the material's strength and impact resistance. The box is highly susceptible to brittle cracking or permanent compression deformation during handling, stacking, or dropping, which not only causes insulation failure but may also trigger biosafety leaks. Second, the existing materials have insufficient resistance to environmental aging. Under repeated temperature and humidity cycles, they are prone to hydrolysis and pulverization, leading to accelerated degradation of insulation performance.

[0004] To address these issues, existing technologies have explored various approaches. For example, adding inorganic fibers such as glass fiber and rock wool can enhance the mechanical strength of the foam. However, simple physical blending often leads to fiber agglomeration, severely disrupting the uniformity of the foam cells and deteriorating the overall insulation performance. Furthermore, the weak interfacial bonding between the fibers and the polymer matrix easily becomes stress concentration points, failing to fundamentally solve the toughness and brittleness problems. Other studies have attempted to introduce nanofillers (such as silica and clay) or use bio-based raw materials to improve performance and environmental friendliness, but these improvements often focus on single performance indicators (such as flame retardancy and static insulation), failing to systematically and comprehensively resolve the multiple performance contradictions of "high insulation and high strength and toughness," especially for the specific application of transporting biological samples.

[0005] Patent publication number CN120699419A discloses a bio-based polyurethane material and its preparation method, comprising, by weight, 60-80 parts of bio-based polyol, 5-10 parts of flame retardant, 2-6 parts of chain extender, 0.5-2 parts of surfactant, 1-5 parts of foaming agent, 5-15 parts of modified rock wool fiber, 0.1-1 parts of catalyst, and 100-110 parts of isocyanate. The bio-based polyurethane material provided by this invention, through the combination of bio-based polyol, flame retardant, chain extender, and modified rock wool fiber and modified sunflower seed oil polyol, solves the technical problem of the difficulty in simultaneously achieving mechanical and thermal insulation properties in existing bio-based polyurethane materials. This material utilizes bio-based resources to replace petroleum-based raw materials, and while maintaining good flame retardant properties, achieves a significant improvement in both mechanical and thermal insulation properties through the synergistic effect of fiber reinforcement and fillers. This patent describes a general-purpose bio-based polyurethane material for building insulation. Its primary goal is to balance mechanical and thermal insulation properties while enhancing flame retardancy, making it suitable for conventional insulation applications such as building exterior walls, roofs, and cold storage. However, for pathogenic microorganism sample transport boxes, comprehensive properties such as ultra-low thermal conductivity, high impact resistance, hydrolysis resistance, and resistance to temperature and humidity cycling are required. This patent's thermal conductivity is insufficient, failing to meet the stringent temperature control requirements of cold chain transportation. Sample temperature fluctuations may lead to sample inactivation or distorted test results. Furthermore, polyurethane may become brittle at low temperatures. In cold chain environments of 2–8°C or even lower, insufficient material flexibility can lead to brittle cracking.

[0006] Therefore, developing a new type of thermal insulation material that can simultaneously achieve ultra-low thermal conductivity, excellent impact and compressive strength, and superior environmental stability has become a technological bottleneck that urgently needs to be overcome in the field of biological sample transportation equipment. Summary of the Invention

[0007] To address the aforementioned problems, the first aspect of this invention provides an insulation material for a special box for transporting pathogenic microorganism samples. By weight, the insulation material comprises 100-105 parts isocyanate, 15-20 parts modified sunflower seed oil polyol, 40-45 parts castor oil polyol, 10-15 parts polyether polyol, 6-8 parts modified rock wool fiber, 4-6 parts surface-grafted chopped aramid fiber, 3-5 parts flame retardant, 1-2 parts polysilsesquioxane, 2-3 parts chain extender, 1.5-2 parts organosilicon surfactant, 3-5 parts foaming agent, 0.8-1.2 parts hydrolysis resistant agent, and 0.1-0.3 parts fumed silica.

[0008] In this invention's thermal insulation material, modified rock wool fibers, surface-grafted chopped aramid fibers, and polysilsesquioxane work synergistically to construct a reinforcing network. This network stabilizes the high-porosity foam structure, resulting in a material with numerous air chambers (low thermal conductivity) while maintaining an exceptionally strong and tough skeleton, thus achieving high strength and high compressive strength. The synergistic effect of organosilicon surfactants and fumed silica stabilizes the liquid film during foaming, promoting the formation of a fine, uniform, and highly closed-cell structure. The closed-cell structure maximally suppresses air convection, while uniformity ensures uniform heat flow blocking, avoiding localized thermal bridging. The uniformly distributed fiber network physically blocks and stabilizes the merging and growth of bubbles during foaming, contributing to a finer and more stable cell structure. This results in an extremely low overall thermal conductivity and a more thermally and mechanically stable structure. The introduction of polyether polyols provides longer flexible segments to the polyurethane matrix, significantly improving the material's low-temperature flexibility and resilience. The hydrolysis-resistant agent actively captures and neutralizes the carboxylic acids produced by the hydrolysis of polyurethane under humid and hot conditions, chemically terminating the hydrolysis chain reaction and protecting the molecular chains and fiber-matrix interface from damage, ensuring long-term reliability. This allows the material to maintain good toughness even in environmental conditions (such as 2-8°C or even lower) and withstand the unavoidable temperature and humidity cycles during transportation, greatly extending its service life.

[0009] Optionally, the insulation material includes 103-105 parts of isocyanate, 17-19 parts of modified sunflower seed oil polyol, 42-44 parts of castor oil polyol, 12-14 parts of polyether polyol, 7-8 parts of modified rock wool fiber, 5-6 parts of surface-grafted chopped aramid fiber, 4-5 parts of flame retardant, 1.5-2 parts of polysilsesquioxane, 2.5-3 parts of chain extender, 1.8-2 parts of organosilicon surfactant, 3-5 parts of foaming agent, 1.0-1.2 parts of hydrolysis resistant agent, and 0.2-0.3 parts of fumed silica.

[0010] Optionally, the preparation method of surface-grafted chopped aramid fibers includes the following steps: (1) The dried chopped aramid fibers were surface treated with oxygen plasma; The polyether polyol and the catalyst were mixed, and isocyanate was added dropwise at a temperature of 70-80℃. Anhydrous xylene was then added to obtain a polyurethane prepolymer solution. (2) The surface-treated chopped aramid fibers are immersed in a polyurethane prepolymer solution, pre-cured at 80-100℃, and then post-cured at 110-120℃ to obtain surface-grafted chopped aramid fibers.

[0011] Furthermore, the short-cut aramid fibers treated with polyurethane prepolymer coating have -NCO or -OH groups on their surface, which form chemical bonds with the matrix during the foaming process, greatly improving the efficiency of interfacial stress transfer and avoiding brittle damage caused by interfacial debonding.

[0012] Optionally, the length of the chopped aramid fiber is 3-6 mm.

[0013] Optionally, in step (1), the surface treatment power is 100-200W, the oxygen flow rate is 20-50sccm, the treatment pressure is 10-30Pa, and the treatment time is 2-5min.

[0014] Optionally, the isocyanate is toluene diisocyanate or isophorone diisocyanate, and the isocyanate accounts for 25-35% of the mass of the polyether polyol.

[0015] Optionally, the preparation method of modified sunflower seed oil polyol includes the following steps: (1) Mix diethanolamine and sodium hydroxide, heat to 70-75℃ under nitrogen protection, then slowly add sunflower seed oil, control the reaction temperature to 75-80℃, react for 3-4 hours, then cool, wash, dry and filter in sequence to obtain aminohydrolyzed sunflower seed oil; (2) Dissolve hexadecyltrimethylammonium bromide in a mixed solution of water and anhydrous ethanol, add ammonia water, and slowly add tetraethyl orthosilicate; then add (3-mercaptopropyl)trimethoxysilane, heat to 55-65℃, and continue the reaction for 24-30h. Then, centrifuge, wash and dry in sequence to obtain mercapto-modified hollow nano silica. (3) The mercapto-modified hollow nano silica was dispersed in tetrahydrofuran and ultrasonically dispersed to obtain a suspension. The suspension, aminohydrolyzed sunflower seed oil, tetrahydrofuran, and azobisisobutyronitrile were mixed and heated to 70-75℃ under nitrogen protection for 4-6 hours to obtain modified sunflower seed oil polyol.

[0016] Optionally, diethanolamine may comprise 30-40% of the sunflower seed oil by weight.

[0017] Optionally, (3-mercaptopropyl)trimethoxysilane comprises 8%-20% of the mass of tetraethyl orthosilicate.

[0018] Optionally, the thiolized hollow nano-silica accounts for 2-8% of the mass of the aminohydrolyzed sunflower seed oil.

[0019] Optionally, the preparation method of modified rock wool fiber includes the following steps: (1) Rock wool fibers were added to a mixed solution of ethanol / water and ultrasonically dispersed. (2) Add γ-aminopropyltriethoxysilane, heat to 40-50℃, wash, dry, and obtain aminated rock wool fiber; (3) Vanillic acid, 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride and N-hydroxysuccinimide are dissolved in an acetic acid solution with a pH of 5.5-6.0 to obtain a mixed solution; aminated rock wool fibers are dispersed in the mixed solution and reacted at 55-60℃ in the dark for 4-6 hours. After washing and drying, vanillic acid grafted rock wool fibers are obtained. (4) Disperse vanillic acid-grafted rock wool fibers in anhydrous ethanol, ultrasonically disperse them, add 3-mercaptopropyltrimethoxysilane solution, and heat to 35-45℃ to obtain modified rock wool fibers.

[0020] In the modified rock wool fiber of this application, a flexible organosilane layer rich in mercapto groups is introduced around the vanillic acid grafted layer. This flexible outer layer can act as a micro-stress buffer layer in the interface region, and can absorb and dissipate impact energy through deformation, passivate crack tips, thereby improving the impact toughness and fatigue resistance of the thermal insulation material.

[0021] Optionally, the number average molecular weight of the polyether polyol is 2000-6000 g / mol and the degree of unsaturation is ≤0.05 mmol / g.

[0022] Optionally, the rock wool fiber length is 0.5-1.5mm and the diameter is 5-10μm.

[0023] Optionally, γ-aminopropyltriethoxysilane accounts for 5-8% of the rock wool fiber mass.

[0024] Optionally, vanillic acid accounts for 5-10% of the mass of the aminated rock wool fiber.

[0025] Optionally, 3-mercaptopropyltrimethoxysilane accounts for 0.5-2% of the vanillic acid-grafted rock wool fiber mass.

[0026] Optionally, the isocyanate is modified MDI.

[0027] Optionally, the preparation method of modified MDI includes the following steps: adding triethylphosphine to dehydrated 4,4'-diphenylmethane diisocyanate at a temperature of 180-200℃, reacting for 1-3 hours, cooling to below 80℃, adding phosphoric acid and 4-toluenesulfonyl isocyanate, and cooling, filtering and drying under nitrogen protection to obtain modified MDI.

[0028] Optionally, the flame retardant is a phosphorus-based flame retardant.

[0029] Optionally, the chain extender is 1,4-butanediol.

[0030] Optionally, the silicone surfactant is a polysiloxane-polyether copolymer.

[0031] Optionally, the foaming agent is a mixture of water and hydrofluoroolefin, with a mass ratio of water to hydrofluoroolefin of 1:(1-1.5).

[0032] Optionally, the hydrolysis resistant agent is a carbodiimide.

[0033] A second aspect of the present invention provides a method for preparing an insulation material for a special box for transporting pathogenic microorganism samples, the method comprising the following steps: S1: Dehydrated modified sunflower seed oil polyol, castor oil polyol, and polyether polyol are mixed. Flame retardant, polysilsesquioxane, and hydrolysis resistant agent are added and mixed evenly. Then, modified rock wool fiber, surface-grafted short-cut aramid fiber, and fumed silica are added and mixed evenly. The shearing speed is 1000-1500 rpm, and the mixture is stirred at 40-50℃ for 60-90 min. The temperature is then lowered to 25-30℃, and chain extender, organosilicon surfactant, and foaming agent are added. The shearing temperature is raised to above 2000 rpm, and the mixture is homogenized under vacuum for 60-120 min. Finally, a catalyst is added to obtain component A. Isocyanate is component B; S2: Mix and inject components A and B under high pressure, then cure to obtain the thermal insulation material.

[0034] Optionally, the injection pressure is 14-18MPa and the mold temperature is 50-60℃.

[0035] In addition, in order to improve the biocompatibility of thermal insulation materials, an antibacterial coating can be sprayed on the surface of the thermal insulation materials. However, the antibacterial coating is not within the scope of this invention. Those skilled in the art can combine it with existing antibacterial coatings for spraying, and this application will not elaborate on it.

[0036] Compared with the prior art, the present invention achieves at least one of the following beneficial effects: (1) The present invention provides a thermal insulation material for a special box for transporting pathogenic microorganism samples. The thermal insulation material can simultaneously achieve ultra-low thermal conductivity, excellent impact and compressive strength, and excellent environmental stability.

[0037] (2) The short-cut aramid fibers of the present invention are coated with polyurethane prepolymer, so that their surface has -NCO or -OH groups, which form chemical bonds with the matrix during the foaming process, greatly improving the efficiency of stress transfer at the interface and avoiding brittle damage caused by interface debonding.

[0038] (3) In the modified rock wool fiber of the present invention, a flexible organosilane layer rich in mercapto groups is introduced around the vanillic acid graft layer. This flexible outer layer can serve as a micro-stress buffer layer in the interface region, and can absorb and dissipate impact energy through deformation, thereby blunting the crack tip and improving the impact toughness and fatigue resistance of the thermal insulation material. Detailed Implementation

[0039] The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.

[0040] Unless otherwise specified, the raw materials used in the embodiments and comparative examples of this application were all purchased commercially.

[0041] Unless otherwise specified, the methods used in the embodiments and comparative examples of this application are conventional methods in the prior art.

[0042] Example 1 In an exemplary embodiment of the present invention, the insulation material of the special box for transporting pathogenic microorganism samples comprises, by weight, 100 parts modified MDI, 15 parts modified sunflower seed oil polyol, 40 parts castor oil polyol, 10 parts polyether polyol (Mn=2000, functionality 2), 6 parts modified rock wool fiber, 4 parts surface-grafted chopped aramid fiber, 3 parts microencapsulated red phosphorus, 1 part cage-type polysilsesquioxane, 2 parts 1,4-butanediol, 1.5 parts polysiloxane-polyether copolymer, 3 parts foaming agent (water to hydrofluoroolefin mass ratio of 1:1), 0.8 parts carbodiimide, and 0.1 parts fumed silica.

[0043] The preparation method of surface-grafted chopped aramid fibers includes the following steps: (1) Dry chopped aramid fibers (3 mm in length) were surface treated with oxygen plasma at a power of 100 W, an oxygen flow rate of 20 sccm, a treatment pressure of 10 Pa, and a treatment time of 3 min. Polyether polyol and dibutyltin dilaurate were mixed, and at a temperature of 70°C, 25 wt% isophorone diisocyanate was added dropwise. Anhydrous xylene was added, and the solid content of the final solution was adjusted to 15 wt% to obtain a polyurethane prepolymer solution. (2) The surface-treated chopped aramid fibers are immersed in a polyurethane prepolymer solution, pre-cured at 80°C, and then post-cured at 110°C to obtain surface-grafted chopped aramid fibers.

[0044] The preparation method of modified sunflower seed oil polyol includes the following steps: (1) Mix 30g of diethanolamine and 1.3g of sodium hydroxide, heat to 70°C under nitrogen protection, then slowly add 100g of sunflower seed oil, control the reaction temperature at 75°C, react for 3h, and then cool, wash, dry and filter in sequence to obtain aminohydrolyzed sunflower seed oil. (2) Dissolve 2g of hexadecyltrimethylammonium bromide in a mixed solution of water and anhydrous ethanol, add 8ml of 28wt% ammonia water, and slowly add 20g of tetraethyl orthosilicate; then add 2g of (3-mercaptopropyl)trimethoxysilane, heat to 55℃, and continue the reaction for 24h. Then, centrifuge, wash and dry in sequence to obtain mercapto-modified hollow nano silica. (3) Disperse 3g of mercapto-modified hollow nano silica in tetrahydrofuran and perform ultrasonic dispersion to obtain a suspension. Mix the suspension, 100g of aminohydrolyzed sunflower seed oil, tetrahydrofuran, and 0.5g of azobisisobutyronitrile. Under nitrogen protection, heat to 70°C and react for 4h to obtain modified sunflower seed oil polyol.

[0045] The preparation method of modified rock wool fiber includes the following steps: (1) Add 10g of rock wool fiber to 200ml of ethanol / water mixed solution and disperse it by ultrasonication; (2) Add 0.6g of γ-aminopropyltriethoxysilane, heat to 40℃, wash, and dry to obtain aminated rock wool fiber; (3) Dissolve 1.0g vanillic acid, 0.5g 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride and 0.3g N-hydroxysuccinimide in 200ml acetic acid solution with pH 5.5 to obtain a mixed solution. Disperse 10g aminated rock wool fiber in the mixed solution and react at 55℃ in the dark for 4h. After washing and drying, vanillic acid grafted rock wool fiber is obtained. (4) Disperse 10g of vanillic acid grafted rock wool fiber in 200ml of anhydrous ethanol and ultrasonically disperse it; mix 0.2g of 3-mercaptopropyltrimethoxysilane with a small amount of deionized water, add 3-mercaptopropyltrimethoxysilane solution dropwise, heat to 35℃, wash, dry, and obtain modified rock wool fiber.

[0046] The preparation method of thermal insulation material includes the following steps: S1: Dehydrated modified sunflower seed oil polyol, castor oil polyol, and polyether polyol are mixed. Flame retardant, polysilsesquioxane, and hydrolysis resistant agent are added and mixed evenly. Then, modified rock wool fiber, surface-grafted short-cut aramid fiber, and fumed silica are added and mixed evenly. The shearing speed is 1000 rpm, and the mixture is stirred at 40°C for 60 min. The temperature is then reduced to 25°C, and chain extender, organosilicon surfactant, and foaming agent are added. The shearing temperature is raised to 2500 rpm, and the mixture is homogenized under vacuum for 60 min. Then, dibutyltin dilaurate is added to obtain component A. The modified MDI is component B; S2: Mix and inject components A and B under high pressure at a pressure of 14 MPa and a mold temperature of 50°C to obtain the thermal insulation material.

[0047] Example 2 In an exemplary embodiment of the present invention, the insulation material of the special box for transporting pathogenic microorganism samples, by weight, comprises 105 parts modified MDI, 20 parts modified sunflower seed oil polyol, 45 parts castor oil polyol, 15 parts polyether polyol (Mn=3000, functionality 2), 8 parts modified rock wool fiber, 6 parts surface-grafted chopped aramid fiber, 5 parts microencapsulated red phosphorus, 2 parts cage-type polysilsesquioxane, 3 parts 1,4-butanediol, 2 parts polysiloxane-polyether copolymer, 5 parts foaming agent (water to hydrofluoroolefin mass ratio of 1:1), 1.2 parts carbodiimide, and 0.3 parts fumed silica.

[0048] The preparation method of surface-grafted chopped aramid fibers includes the following steps: (1) Dry chopped aramid fibers (6 mm in length) were surface treated with oxygen plasma at a power of 200 W, an oxygen flow rate of 50 sccm, a treatment pressure of 30 Pa, and a treatment time of 3 min. Polyether polyol and dibutyltin dilaurate were mixed, and at a temperature of 80°C, 35 wt% isophorone diisocyanate was added dropwise. Anhydrous xylene was added, and the solid content of the final solution was adjusted to 20 wt% to obtain a polyurethane prepolymer solution. (2) The surface-treated chopped aramid fibers are immersed in a polyurethane prepolymer solution, pre-cured at 100°C, and then post-cured at 120°C to obtain surface-grafted chopped aramid fibers.

[0049] The preparation method of modified sunflower seed oil polyol includes the following steps: (1) Mix 40g of diethanolamine and 2.0g of sodium hydroxide, heat to 75°C under nitrogen protection, then slowly add 100g of sunflower seed oil, control the reaction temperature to 80°C, react for 4h, and then cool, wash, dry and filter in sequence to obtain aminohydrolyzed sunflower seed oil. (2) Dissolve 3g of hexadecyltrimethylammonium bromide in a mixed solution of water and anhydrous ethanol, add 12ml of 28wt% ammonia water, and slowly add 25g of tetraethyl orthosilicate; then add 4g of (3-mercaptopropyl)trimethoxysilane, heat to 65℃, and continue the reaction for 30h. Then, centrifuge, wash and dry in sequence to obtain mercapto-modified hollow nano silica. (3) Disperse 7g of mercapto-modified hollow nano silica in tetrahydrofuran and perform ultrasonic dispersion to obtain a suspension. Mix the suspension, 100g of aminohydrolyzed sunflower seed oil, tetrahydrofuran, and 0.5g of azobisisobutyronitrile. Under nitrogen protection, heat to 75℃ and react for 4h to obtain modified sunflower seed oil polyol.

[0050] The preparation method of modified rock wool fiber includes the following steps: (1) Add 10g of rock wool fiber to 200ml of ethanol / water mixed solution and disperse it by ultrasonication; (2) Add 0.8g of γ-aminopropyltriethoxysilane, heat to 50℃, wash, and dry to obtain aminated rock wool fiber; (3) Dissolve 1.0g vanillic acid, 0.5g 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride and 0.3g N-hydroxysuccinimide in 200ml acetic acid solution with pH 6.0 to obtain a mixed solution. Disperse 10g aminated rock wool fiber in the mixed solution and react at 60℃ in the dark for 4h. After washing and drying, vanillic acid grafted rock wool fiber is obtained. (4) Disperse 10g of vanillic acid grafted rock wool fiber in 200ml of anhydrous ethanol and ultrasonically disperse it; mix 0.2g of 3-mercaptopropyltrimethoxysilane with a small amount of deionized water, add 3-mercaptopropyltrimethoxysilane solution dropwise, heat to 45℃, wash, dry, and obtain modified rock wool fiber.

[0051] The preparation method of thermal insulation material includes the following steps: S1: Dehydrated modified sunflower seed oil polyol, castor oil polyol, and polyether polyol are mixed. Flame retardant, polysilsesquioxane, and hydrolysis resistant agent are added and mixed evenly. Then, modified rock wool fiber, surface-grafted short-cut aramid fiber, and fumed silica are added and mixed evenly. The shearing speed is 1500 rpm, and the mixture is stirred at 50°C for 90 min. The temperature is then reduced to 30°C, and chain extender, organosilicon surfactant, and foaming agent are added. The shearing temperature is raised to 2500 rpm, and the mixture is homogenized under vacuum for 100 min. Then, dibutyltin dilaurate is added to obtain component A. The modified MDI is component B; S2: Mix and inject components A and B under high pressure at a pressure of 18 MPa and a mold temperature of 60°C to obtain the thermal insulation material.

[0052] Example 3 In an exemplary embodiment of the present invention, the insulation material of the special box for transporting pathogenic microorganism samples, by weight, comprises 103 parts modified MDI, 17 parts modified sunflower seed oil polyol, 42 parts castor oil polyol, 12 parts polyether polyol (Mn=3000, functionality 2), 8 parts modified rock wool fiber, 5 parts surface-grafted chopped aramid fiber, 5 parts microencapsulated red phosphorus, 2 parts cage-type polysilsesquioxane, 2.5 parts 1,4-butanediol, 2 parts polysiloxane-polyether copolymer, 4 parts foaming agent (water to hydrofluoroolefin mass ratio of 1:1), 1.0 part carbodiimide, and 0.2 parts fumed silica.

[0053] The preparation method of surface-grafted chopped aramid fibers includes the following steps: (1) Dry chopped aramid fibers (4 mm in length) were surface treated with oxygen plasma at a power of 150 W, an oxygen flow rate of 30 sccm, a treatment pressure of 20 Pa, and a treatment time of 3 min. Polyether polyol and dibutyltin dilaurate were mixed, and at a temperature of 80°C, 30 wt% isophorone diisocyanate was added dropwise. Anhydrous xylene was added, and the solid content of the final solution was adjusted to 18 wt% to obtain a polyurethane prepolymer solution. (2) The surface-treated chopped aramid fibers are immersed in a polyurethane prepolymer solution, pre-cured at 90°C, and then post-cured at 115°C to obtain surface-grafted chopped aramid fibers.

[0054] The preparation method of modified sunflower seed oil polyol includes the following steps: (1) Mix 35g of diethanolamine and 1.5g of sodium hydroxide, heat to 73°C under nitrogen protection, then slowly add 100g of sunflower seed oil, control the reaction temperature to 78°C, react for 4 hours, and then cool, wash, dry and filter in sequence to obtain aminohydrolyzed sunflower seed oil. (2) Dissolve 2.5g of hexadecyltrimethylammonium bromide in a mixed solution of water and anhydrous ethanol, add 10ml of 28wt% ammonia water, and slowly add 23g of tetraethyl orthosilicate; then add 3g of (3-mercaptopropyl)trimethoxysilane, heat to 60℃, continue the reaction for 30h, and then centrifuge, wash and dry in sequence to obtain mercapto-modified hollow nano silica. (3) 5g of mercapto-modified hollow nano silica was dispersed in tetrahydrofuran and ultrasonically dispersed to obtain a suspension. The suspension, 100g of aminohydrolyzed sunflower seed oil, tetrahydrofuran, and 0.5g of azobisisobutyronitrile were mixed and heated to 73°C under nitrogen protection for 5h to obtain modified sunflower seed oil polyol.

[0055] The preparation method of modified rock wool fiber includes the following steps: (1) Add 10g of rock wool fiber to 200ml of ethanol / water mixed solution and disperse it by ultrasonication; (2) Add 0.6g of γ-aminopropyltriethoxysilane, heat to 45℃, wash, and dry to obtain aminated rock wool fiber; (3) Dissolve 1.0g vanillic acid, 0.5g 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride and 0.3g N-hydroxysuccinimide in 200ml acetic acid solution with pH 6.0 to obtain a mixed solution. Disperse 10g aminated rock wool fiber in the mixed solution and react at 58℃ in the dark for 4h. After washing and drying, vanillic acid grafted rock wool fiber is obtained. (4) Disperse 10g of vanillic acid grafted rock wool fiber in 200ml of anhydrous ethanol and ultrasonically disperse it; mix 0.2g of 3-mercaptopropyltrimethoxysilane with a small amount of deionized water, add 3-mercaptopropyltrimethoxysilane solution dropwise, heat to 40℃, wash, dry, and obtain modified rock wool fiber.

[0056] The preparation method of thermal insulation material includes the following steps: S1: Dehydrated modified sunflower seed oil polyol, castor oil polyol, and polyether polyol are mixed. Flame retardant, polysilsesquioxane, and hydrolysis resistant agent are added and mixed evenly. Then, modified rock wool fiber, surface-grafted short-cut aramid fiber, and fumed silica are added and mixed evenly. The shearing speed is 1300 rpm, and the mixture is stirred at 45°C for 70 min. The temperature is then reduced to 28°C, and chain extender, organosilicon surfactant, and foaming agent are added. The shearing temperature is raised to 2500 rpm, and the mixture is homogenized under vacuum for 100 min. Then, dibutyltin dilaurate is added to obtain component A. The modified MDI is component B; S2: Mix and inject components A and B under high pressure at a pressure of 16 MPa and a mold temperature of 55°C to obtain the thermal insulation material.

[0057] Example 4 Based on Example 3, the main difference is that the preparation method of modified rock wool fiber includes the following steps: (1) Add 10g of rock wool fiber to 200ml of ethanol / water mixed solution and disperse it by ultrasonication; (2) Add 0.6g of γ-aminopropyltriethoxysilane, heat to 45℃, wash, and dry to obtain aminated rock wool fiber; (3) Dissolve 1.0 g vanillic acid, 0.5 g 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride, and 0.3 g N-hydroxysuccinimide in 200 ml of acetic acid solution with pH 6.0 to obtain a mixed solution. Disperse 10 g of aminated rock wool fiber in the mixed solution and react at 58 °C in the dark for 4 h. After washing and drying, modified rock wool fiber is obtained. Other steps are the same as in Example 3.

[0058] Example 5 Based on Example 3, the main difference lies in the preparation method of the modified sunflower seed oil polyol, which includes the following steps: (1) Mix 35g of diethanolamine and 1.5g of sodium hydroxide, heat to 73°C under nitrogen protection, then slowly add 100g of sunflower seed oil, control the reaction temperature to 78°C, react for 4 hours, and then cool, wash, dry and filter in sequence to obtain aminohydrolyzed sunflower seed oil. (2) Amine-hydrolyzed sunflower seed oil and fumed silica are directly and physically mixed into the amino-hydrolyzed sunflower seed oil to obtain modified sunflower seed oil polyol.

[0059] Comparative Example 1 The main difference from Example 1 is that no surface-grafted chopped aramid fibers are added.

[0060] Comparative Example 2 The main difference from Example 1 is that no modified rock wool fiber is added.

[0061] Comparative Example 3 The main difference from Example 1 is that the sunflower seed oil polyol was not modified.

[0062] Comparative Example 4 The main difference from Example 1 is that the chopped aramid fibers were not subjected to surface grafting treatment.

[0063] Comparative Example 5 The main difference from Example 1 is that the rock wool fibers were not modified.

[0064] Comparative Example 6 Based on Example 1, the main difference is that the modified sunflower seed oil polyol is replaced with an equal amount of castor oil polyol.

[0065] Test case The performance of the thermal insulation materials prepared in the examples and comparative examples was tested, as shown in Table 1.

[0066] Compression strength retention rate: The compression strength retention rate is tested after 28 days of aging at 70℃ and 95% humidity. Compression strength retention rate = (compression strength after 20 days of aging / initial compression strength) × 100%.

[0067] Table 1

[0068] Referring to Table 1, the thermal conductivity of the insulation material prepared by this invention is not higher than 0.028 W / (m·K), the compressive strength is not lower than 400 kPa, the elongation at break is 12-18%, the tear strength is 0.44-0.71 N / mm, and the compressive strength retention rate after 28 days of aging is not lower than 80%.

[0069] Furthermore, when the thermal insulation material prepared in this application is placed in a temperature and humidity environment of -20°C for 8 hours to 40°C for 8 hours and 90%RH for 30 cycles, the change rate of thermal conductivity is less than 5%, preferably less than 3%, demonstrating excellent environmental stability.

[0070] In Comparative Example 1, no surface-grafted chopped aramid fibers were added, resulting in high elongation and high tear strength. This made the insulation material more flexible, but at the expense of rigidity.

[0071] In Comparative Example 4, the short-cut aramid fibers were not surface grafted, resulting in a decrease in toughness and tear strength.

[0072] The above description is merely an embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principle of the present invention should be included within the scope of the claims of the present invention.

Claims

1. A heat-insulating material for a pathogenic microorganism sample transport special case, characterized by, The thermal insulation material comprises, by weight, 100-105 parts of isocyanate, 15-20 parts of modified sunflower seed oil polyol, 40-45 parts of castor oil polyol, 10-15 parts of polyether polyol, 6-8 parts of modified rock wool fiber, 4-6 parts of surface grafted short aramid fiber, 3-5 parts of flame retardant, 1-2 parts of polysilsesquioxane, 2-3 parts of chain extender, 1.5-2 parts of silicone surfactant, 3-5 parts of foaming agent, 0.8-1.2 parts of hydrolysis resistant agent, and 0.1-0.3 parts of fumed silica.

2. The thermal insulation material according to claim 1, characterized in that The preparation method of the surface grafted short aramid fiber comprises the following steps: (1) dry short aramid fiber is subjected to surface treatment by oxygen plasma; polyether polyol and catalyst are mixed, isocyanate is added dropwise at a temperature of 70-80℃, and anhydrous xylene is added to obtain a polyurethane prepolymer solution; (2) the surface-treated short aramid fiber is immersed in the polyurethane prepolymer solution, pre-cured at a temperature of 80-100℃, and then post-cured at a temperature of 110-120℃ to obtain the surface grafted short aramid fiber.

3. The thermal insulation material according to claim 2, characterized in that The length of the short aramid fiber is 3-6mm; and / or the power for surface treatment in step (1) is 100-200W, the oxygen flow is 20-50sccm, the treatment pressure is 10-30Pa, and the treatment time is 2-5min; and / or the isocyanate is toluene diisocyanate or isophorone diisocyanate.

4. The thermal insulation material according to claim 1, characterized in that The preparation method of the modified sunflower seed oil polyol comprises the following steps: (1) diethanolamine and sodium hydroxide are mixed, heated to 70-75℃ under nitrogen protection, then sunflower seed oil is slowly added dropwise, the reaction temperature is controlled at 75-80℃, and the reaction is carried out for 3-4h, then the amine sunflower seed oil is obtained after cooling, washing, drying and filtering in sequence; (2) cetyltrimethylammonium bromide is dissolved in a mixed solution of water and anhydrous ethanol, ammonia water is added, and tetraethyl orthosilicate is slowly added dropwise; then (3-mercaptopropyl) trimethoxysilane is added, heated to 55-65℃, and the reaction is continued for 24-30h, then the mercapto hollow nanosilica is obtained after centrifugation, washing and drying in sequence; (3) the mercapto hollow nanosilica is dispersed in tetrahydrofuran to obtain a suspension, and the suspension, amine sunflower seed oil, tetrahydrofuran and azobisisobutyronitrile are mixed, heated to 70-75℃ under nitrogen protection, and reacted for 4-6h to obtain the modified sunflower seed oil polyol.

5. The thermal insulation material according to claim 4, characterized in that The diethanolamine accounts for 30-40% of the mass of the sunflower seed oil; and / or the (3-mercaptopropyl) trimethoxysilane accounts for 8%-20% of the mass of the tetraethyl orthosilicate; and / or the mercapto hollow nanosilica accounts for 2-8% of the mass of the amine sunflower seed oil.

6. The thermal insulation material according to claim 1, characterized in that The preparation method of the modified rock wool fiber comprises the following steps: (1) the rock wool fiber is added into a mixed solution of ethanol and water, and ultrasonic dispersion is carried out; (2) γ-aminopropyltriethoxysilane is added, heated to 40-50℃, washed, and dried to obtain the aminated rock wool fiber; (3) vanillic acid, 1-ethyl-(3-dimethylaminopropyl) carbodiimide hydrochloride, N-hydroxysuccinimide are dissolved in acetic acid solution with pH of 5.5-6.0 to obtain a mixed solution; the amino rock wool fibers are dispersed in the mixed solution, and reacted at 55-60℃ in dark for 4-6h, and then washed and dried to obtain vanillic acid grafted rock wool fibers; (4) the vanillic acid grafted rock wool fibers are dispersed in anhydrous ethanol, ultrasonic dispersed, and then 3-mercaptopropyl trimethoxysilane solution is added dropwise, and the temperature is raised to 35-45℃ to obtain modified rock wool fibers.

7. The thermal insulation material according to claim 6, characterized in that The length of the rock wool fibers is 0.5-1.5mm, and the diameter is 5-10μm.

8. The thermal insulation material according to claim 6, characterized in that The γ-aminopropyl triethoxysilane accounts for 5-8% of the mass of the rock wool fibers; and / or the vanillic acid accounts for 5-10% of the mass of the amino rock wool fibers; and / or the 3-mercaptopropyl trimethoxysilane accounts for 0.5-2% of the mass of the vanillic acid grafted rock wool fibers.

9. The thermal insulation material according to claim 1, characterized in that The isocyanate is MDI; and / or the flame retardant is a phosphorus-based flame retardant; and / or the chain extender is 1,4-butanediol; and / or the silicone surfactant is a polysiloxane-polyether copolymer; and / or the foaming agent is a compound of water and hydrofluoroolefin; and / or the hydrolysis-resistant agent is a carbodiimide.

10. A method for preparing a heat insulating material for a pathogen sample transport case according to any one of claims 1 to 9, characterized by, The preparation method comprises the following steps: S1: the dehydrated modified sunflower seed oil polyol, castor oil polyol and polyether polyol are mixed, the flame retardant, polysilsesquioxane and hydrolysis-resistant agent are added and uniformly mixed, then the modified rock wool fibers, surface grafted short aramid fibers and fumed silica are added and uniformly mixed, the shearing speed is 1000-1500rpm, the temperature is 40-50℃, the stirring time is 60-90min, the temperature is lowered to 25-30℃, the chain extender, silicone surfactant and foaming agent are added, the shearing temperature is raised to more than 2000rpm, and the homogenization is performed under vacuum for 60-120min, then the catalyst is added to obtain component A; the isocyanate is component B; S2: component A and component B are mixed and injected under high pressure, and cured to obtain the thermal insulation material.

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