A polyurethane flame-retardant thermal insulation material, a thermal insulation aluminum alloy and a preparation method thereof
By adding modified plant fibers to polyurethane flame-retardant thermal insulation materials to form a three-dimensional network structure, the problem of poor material mechanical properties is solved, and the flame retardancy, thermal insulation and mechanical properties are improved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-08-01
- Publication Date
- 2026-03-31
AI Technical Summary
Existing polyurethane flame-retardant thermal insulation materials are prone to defects such as perforation and cracks in their cells, resulting in poor mechanical properties.
Modified plant fibers are added to polyurethane flame-retardant and heat-insulating materials. By combining hydrophobically modified reed fibers and flame-retardant cellulose aerogel layers, a three-dimensional network structure is formed, which improves the flame-retardant and heat-insulating properties of the material, while also enhancing its mechanical properties.
It improves the mechanical properties of the material, enhances its flame retardant and thermal insulation properties, and reduces the risk of fire.
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Abstract
Description
Technical Field
[0001] This invention relates to the field of building materials technology, and in particular to a polyurethane flame-retardant heat-insulating material, a heat-insulating aluminum alloy, and a method for preparing the same. Background Technology
[0002] Polyurethane (PU) is a class of polymeric materials containing urethane characteristic units in its main chain. It exhibits better stability, chemical resistance, resilience, and mechanical properties than PVC foam, and has lower compression set. This polymeric material is widely used in industrial fields such as adhesives, coatings, low-speed tires, gaskets, and car mats. In everyday life, polyurethane is used to manufacture various foams and plastic sponges. Due to its very low thermal conductivity, new wall insulation materials based on polyurethane have been well-developed and are now widely used in homes, construction, transportation, and home appliances. However, like other polymeric materials such as plastics, rubber, and fibers, most of these materials are flammable, thus often requiring the addition of functional additives such as flame retardants.
[0003] The related technology discloses a polyurethane flame-retardant and heat-insulating material, the raw materials of which include the following components in parts by weight: 10-20 parts of polyether polyol; 5-15 parts of flame retardant; 1-3 parts of foam stabilizer; 0.2-0.8 parts of foaming agent; 0.01-0.04 parts of catalyst; 0.5-1.5 parts of surfactant; and 20-30 parts of isocyanate.
[0004] The aforementioned polyurethane flame-retardant and heat-insulating materials contain many air bubbles. The materials are mainly supported by cells, which are prone to defects such as perforation and cracks, resulting in poor mechanical properties. Summary of the Invention
[0005] In order to improve the mechanical properties of polyurethane materials while ensuring their flame retardant and heat insulation properties, this application provides a polyurethane flame retardant and heat insulation material, a heat insulation aluminum alloy, and a method for preparing the same.
[0006] In a first aspect, this application provides a polyurethane flame-retardant and heat-insulating material, which adopts the following technical solution:
[0007] A polyurethane flame-retardant and heat-insulating material, the raw materials of which include the following components in parts by weight:
[0008] 10-20 parts of polyether polyol;
[0009] 5-15 parts flame retardant;
[0010] 1-3 parts foam stabilizer;
[0011] Foaming agent 0.2-0.8 parts;
[0012] Catalyst 0.01-0.04 parts;
[0013] Surfactant 0.5-1.5 parts;
[0014] 20-30 parts isocyanate;
[0015] 5-10 parts of modified plant fiber;
[0016] The modified plant fiber includes hydrophobically modified reed fiber and a flame-retardant cellulose aerogel layer coated on the surface of the hydrophobically modified reed fiber.
[0017] By adopting the above technical solutions, cellulose aerogel is the third generation of aerogel after inorganic aerogel and organic aerogel. It has many advantages of natural polymer materials and nanoporous materials. It is not only biocompatible, easy to degrade and low in cost, but also has high porosity and specific surface area, and is now widely used. Although cellulose aerogels possess many excellent properties, they also have some drawbacks. For example, while their high porosity gives them good adsorption and thermal insulation properties, it also results in poor mechanical properties. Reed fiber, as a fiber reinforcement material, has good mechanical properties but poor heat resistance and is prone to moisture absorption and flammability. Hydrophobic modification can reduce the moisture absorption rate of reed fiber and improve its compatibility with the flame-retardant cellulose aerogel layer. Coating the surface of hydrophobically modified reed fiber with a flame-retardant cellulose aerogel layer can block external heat and improve the heat resistance of the hydrophobically modified reed fiber. Furthermore, the hydrophobically modified reed fiber can also improve the mechanical properties of the flame-retardant cellulose aerogel layer. Therefore, adding modified plant fibers to polyurethane flame-retardant thermal insulation materials, where the modified plant fibers themselves possess flame-retardant and thermal insulation properties and form a three-dimensional network structure within the material, can ensure the material's flame-retardant and thermal insulation properties while also improving its mechanical properties.
[0018] Optionally, the method for preparing the hydrophobically modified reed fiber includes the following steps:
[0019] Crushing process: After drying the reed stalks, they are cut and crushed to obtain reed fibers;
[0020] Pretreatment: Mix reed fiber with water evenly, let stand, sonicate, separate solid and liquid, wash with water, and dry to obtain pretreated fiber;
[0021] Hydrophobic modification: The pretreated fiber was added to glacial acetic acid solution, mixed evenly, microwaved, removed and cooled to room temperature, acetic anhydride and concentrated sulfuric acid were added, mixed evenly, and esterification reaction was carried out under microwave conditions. After the reaction was completed, the solid and liquid were separated, washed with water until neutral, and dried to obtain hydrophobic modified reed fiber.
[0022] By adopting the above technical solution, the reed fiber has good hydrophilicity before modification, is easy to absorb moisture, and has poor compatibility with the flame-retardant cellulose aerogel layer. Acetic anhydride undergoes esterification reaction with the hydroxyl groups on the surface of cellulose, lignin and hemicellulose in the reed fiber, which improves the hydrophobicity of the reed fiber, improves the interfacial compatibility between the reed fiber and the flame-retardant cellulose aerogel layer, and improves the thermal stability of the reed fiber.
[0023] Optionally, the frequency of the ultrasonic treatment is 50-60 kHz and the duration is 5-10 min.
[0024] By adopting the above technical solution, short-term ultrasonic treatment can improve the specific surface area and reactivity of reed fibers, which is beneficial to promoting esterification reaction and increasing the degree of esterification.
[0025] Optionally, the microwave processing power is 380-420W and the microwave processing time is 4-8min; the microwave power during the esterification reaction is 300-340W and the time is 1-2min.
[0026] By adopting the above technical solution, under the above microwave conditions, it is beneficial to promote the esterification reaction and increase the degree of esterification.
[0027] Optionally, in the hydrophobic modification, the solid-liquid ratio of the pretreated fiber to acetic anhydride is 0.1-0.2 g / mL.
[0028] By adopting the above technical solution, if the amount of acetic anhydride is too small, there will be too few acetyl groups grafted onto the reed fiber; if the amount of acetic anhydride is too large, the acetyl groups grafted onto the reed fiber will be saturated, resulting in waste of raw materials. Therefore, the preferred solid-liquid ratio of pretreated fiber to acetic anhydride is 0.1-0.2 g / mL.
[0029] Optionally, the method for preparing the modified plant fiber includes the following steps:
[0030] Preparation of the first suspension: Cellulose nanofibers were mixed with water until homogeneous to obtain the first suspension;
[0031] Preparation of the second suspension: Montmorillonite and water are mixed evenly to obtain the second suspension;
[0032] Preparation of the mixture: The first suspension and the second suspension are mixed evenly to obtain the mixture;
[0033] Modification treatment: Melamine-formaldehyde resin is mixed evenly with the mixture to obtain a composite solution. The hydrophobically modified reed fiber is immersed in the composite solution, taken out and placed in a container, frozen in a liquid nitrogen / ethanol bath, taken out and freeze-dried under vacuum conditions to obtain modified plant fiber.
[0034] The above-mentioned technical solutions show that cellulose aerogel is flammable and has poor mechanical properties. Therefore, this application uses montmorillonite and melamine-formaldehyde resin to enhance the mechanical properties and thermal stability of cellulose aerogel, thereby enabling cellulose aerogel to have flame-retardant properties. The modified plant fiber prepared improves the mechanical properties of the material while ensuring the flame-retardant and heat-insulating properties of the polyurethane material.
[0035] Optionally, the mass ratio of the cellulose nanofibers, melamine-formaldehyde resin and montmorillonite is 1:1:(0.8-1).
[0036] By adopting the above technical solution, if too little montmorillonite is added, the flame retardant performance will be only slightly improved; if too much montmorillonite is added, the thermal insulation performance of cellulose aerogel will be reduced. Therefore, when the ratio of the three raw materials is within the above range, the overall performance of cellulose aerogel is better.
[0037] Optionally, the freeze-drying temperature is -55 to -60°C, and the freeze-drying time is 70-80 hours.
[0038] By adopting the above technical solution and performing freeze-drying under the above conditions, a flame-retardant cellulose aerogel layer with more uniform pore and skeleton structure can be obtained.
[0039] Secondly, this application provides a method for preparing a polyurethane flame-retardant thermal insulation material, employing the following technical solution:
[0040] A method for preparing a polyurethane flame-retardant thermal insulation material includes the following steps:
[0041] Step 1: Mix polyether polyol, flame retardant, foam stabilizer, foaming agent, catalyst, surfactant and modified plant fiber evenly to obtain a mixture;
[0042] Step 2: Add isocyanate to the mixture, mix well, let stand, and heat to react to obtain polyurethane flame retardant and heat insulation material.
[0043] By adopting the above technical solution, modified plant fibers with flame-retardant and heat-insulating properties are added to form a three-dimensional network structure in the material, which can not only ensure the flame-retardant and heat-insulating properties of the material, but also improve the mechanical properties of the material.
[0044] Thirdly, this application provides a heat-insulating aluminum alloy, which adopts the following technical solution:
[0045] A heat-insulating aluminum alloy includes a heat-insulating layer and aluminum alloy profiles located on both sides of the heat-insulating layer, wherein the heat-insulating layer is made of the aforementioned polyurethane flame-retardant heat-insulating material.
[0046] By adopting the above technical solution, the heat insulation layer is prepared using the polyurethane flame-retardant heat insulation material in this application. It has low thermal conductivity, good mechanical properties, and good flame-retardant properties, which improves the heat insulation performance of the heat-insulating aluminum alloy and reduces the fire hazard.
[0047] In summary, this application has the following beneficial effects:
[0048] 1. Since the modified plant fiber is added to the polyurethane flame retardant and heat insulation material in this application, the modified plant fiber itself has flame retardant and heat insulation properties, and forms a three-dimensional network structure in the material, which can not only ensure the flame retardant and heat insulation performance of the material, but also improve the mechanical properties of the material.
[0049] 2. This application modifies the reed fiber to improve its hydrophobicity, improves the interfacial compatibility between the reed fiber and the flame-retardant cellulose aerogel layer, and improves the thermal stability of the reed fiber.
[0050] 3. This application uses montmorillonite and melamine-formaldehyde resin to enhance the mechanical properties and thermal stability of cellulose aerogel, thereby giving the cellulose aerogel flame-retardant properties. Detailed Implementation
[0051] The present application will be further described in detail below with reference to the embodiments.
[0052] The cellulose nanofibers used in the following examples were purchased from Guilin Qihong Technology Co., Ltd., with a diameter of 3-10 nm and a length of 1000-3000 nm.
[0053] Preparation example of hydrophobically modified reed fiber
[0054] Example 1: Preparation of hydrophobically modified reed fiber
[0055] The preparation method of hydrophobically modified reed fiber includes the following steps:
[0056] Crushing process: After the reed stalks are dried, they are cut and crushed to obtain reed fibers with an average length of 1.5mm;
[0057] Pretreatment: Mix reed fiber and water at a volume ratio of 1:30, let stand for 40 minutes, sonicate for 10 minutes at a frequency of 50 kHz, filter, wash with water, and dry to obtain pretreated fiber.
[0058] Hydrophobic modification: 1 kg of pretreated fiber was added to 8 L of glacial acetic acid solution, mixed evenly, and microwaved for 8 min at a power of 380 W. After cooling to room temperature, acetic anhydride and 50 mL of concentrated sulfuric acid were added. The solid-liquid ratio of pretreated fiber to acetic anhydride was 0.1 g / mL. The mixture was mixed evenly and esterification was carried out under microwave conditions at a power of 300 W for 2 min. After the reaction was completed, the mixture was filtered, washed with water until neutral, and dried to obtain hydrophobic modified reed fiber.
[0059] Example 2: Preparation of hydrophobically modified reed fiber
[0060] The preparation method of hydrophobically modified reed fiber includes the following steps:
[0061] Crushing process: After the reed stalks are dried, they are cut and crushed to obtain reed fibers with an average length of 2mm;
[0062] Pretreatment: Mix reed fiber and water at a volume ratio of 1:30, let stand for 40 minutes, sonicate for 8 minutes at a frequency of 55 kHz, filter, wash with water, and dry to obtain pretreated fiber.
[0063] Hydrophobic modification: 1 kg of pretreated fiber was added to 8 L of glacial acetic acid solution, mixed evenly, and microwaved for 6 min at a power of 400 W. After cooling to room temperature, acetic anhydride and 50 mL of concentrated sulfuric acid were added. The solid-liquid ratio of pretreated fiber to acetic anhydride was 0.1 g / mL. The mixture was mixed evenly and esterification was carried out under microwave conditions at a power of 320 W for 1.5 min. After the reaction was completed, the mixture was filtered, washed with water until neutral, and dried to obtain hydrophobic modified reed fiber.
[0064] Example 3: Preparation of hydrophobically modified reed fiber
[0065] The preparation method of hydrophobically modified reed fiber includes the following steps:
[0066] Crushing process: After the reed stalks are dried, they are cut and crushed to obtain reed fibers with an average length of 2.5mm;
[0067] Pretreatment: Mix reed fiber and water at a volume ratio of 1:30, let stand for 40 minutes, sonicate for 5 minutes at a frequency of 60 kHz, filter, wash with water, and dry to obtain pretreated fiber.
[0068] Hydrophobic modification: 1 kg of pretreated fiber was added to 8 L of glacial acetic acid solution, mixed evenly, and microwaved for 4 min at a power of 420 W. After cooling to room temperature, acetic anhydride and 50 mL of concentrated sulfuric acid were added. The solid-liquid ratio of pretreated fiber to acetic anhydride was 0.1 g / mL. The mixture was mixed evenly and esterification was carried out under microwave conditions at a power of 340 W for 1 min. After the reaction was completed, the mixture was filtered, washed with water until neutral, and dried to obtain hydrophobic modified reed fiber.
[0069] Example 4: Preparation of hydrophobically modified reed fiber
[0070] The difference from Example 2, which describes the preparation of hydrophobically modified reed fiber, is that in the hydrophobic modification, the solid-liquid ratio of the pretreated fiber to acetic anhydride is 0.05 g / mL.
[0071] Example 5: Preparation of hydrophobically modified reed fiber
[0072] The difference from Example 2, which describes the preparation of hydrophobically modified reed fiber, is that in the hydrophobic modification, the solid-liquid ratio of the pretreated fiber to acetic anhydride is 0.15 g / mL.
[0073] Preparation Example 6 of Hydrophobic Modified Reed Fiber
[0074] The difference from Example 2, which describes the preparation of hydrophobically modified reed fiber, is that in the hydrophobic modification, the solid-liquid ratio of the pretreated fiber to acetic anhydride is 0.2 g / mL.
[0075] Preparation Example 7 of Hydrophobic Modified Reed Fiber
[0076] The difference from Example 2, which describes the preparation of hydrophobically modified reed fiber, is that in the hydrophobic modification, the solid-liquid ratio of the pretreated fiber to acetic anhydride is 0.4 g / mL.
[0077] Comparative Preparation Example 1 of Hydrophobic Modified Reed Fiber
[0078] The preparation method of reed fiber includes the following steps:
[0079] Crushing process: After the reed stalks are dried, they are cut and crushed to obtain reed fibers with an average length of 1.5mm.
[0080] Comparative Preparation Example 2 of Hydrophobic Modified Reed Fiber
[0081] The preparation method of hydrophobically modified reed fiber includes the following steps:
[0082] Crushing process: After the reed stalks are dried, they are cut and crushed to obtain reed fibers with an average length of 2mm;
[0083] Hydrophobic modification: 1 kg of reed fiber was added to 8 L of glacial acetic acid solution, mixed evenly, and microwaved for 6 min at a power of 400 W. After cooling to room temperature, acetic anhydride and 50 mL of concentrated sulfuric acid were added. The solid-liquid ratio of reed fiber to acetic anhydride was 0.1 g / mL. The mixture was mixed evenly and esterification was carried out under microwave conditions at a power of 320 W for 1.5 min. After the reaction was completed, the mixture was filtered, washed with water until neutral, and dried to obtain hydrophobic modified reed fiber.
[0084] Performance testing method for hydrophobically modified reed fiber: Preparation examples 1-7 and comparative preparation examples 1-2 of hydrophobically modified reed fiber were used as test samples. A NETZSCH DSC 204F1 differential calorimeter was used. 5 mg to -10 mg (accurate to 0.001 g) of dried sample was weighed and placed in an aluminum crucible, which was punctured. A reference sample support was then placed inside. The measurement range was 20℃ to 400℃. The test process used a programmed temperature rise method: the sample was heated from 20℃ to 100℃ at a rate of 10℃ / min, held at that temperature for 10 min, then cooled to 20℃ at a rate of 4℃ / min, and then heated from 20℃ to 400℃ at a rate of 10℃ / min. The nitrogen protective gas flow rate was 20 mL / min, and the nitrogen purging gas flow rate was 60 mL / min. Air was used as the reference. After the test, the initial decomposition temperature / ℃ was calculated and recorded. The results are shown in Table 1.
[0085] Table 1. Performance test results of hydrophobic modified reed fiber
[0086] Preparation Example No. Initial decomposition temperature / °C Example 1: Preparation of hydrophobically modified reed fiber 264.5 Example 2: Preparation of hydrophobically modified reed fiber 265.3 Example 3: Preparation of hydrophobically modified reed fiber 264.9 Example 4: Preparation of hydrophobically modified reed fiber 266.6 Example 5: Preparation of hydrophobically modified reed fiber 266.5 Preparation Example 6 of Hydrophobic Modified Reed Fiber 266.2 Preparation Example 7 of Hydrophobic Modified Reed Fiber 253.4 Comparative Preparation Example 1 of Hydrophobic Modified Reed Fiber 230.2 Comparative Preparation Example 2 of Hydrophobic Modified Reed Fiber 251.3
[0087] Combining the preparation examples 1-7 of hydrophobically modified reed fibers and the comparative preparation examples 1-2 of hydrophobically modified reed fibers, and referring to Table 1, it can be seen that the ordinary reed fiber in comparative preparation example 1 has the lowest initial decomposition temperature and poor heat resistance. Comparative preparation example 2, based on comparative preparation example 1, underwent hydrophobic modification, resulting in a significant increase in the initial decomposition temperature, indicating that acetic anhydride grafted onto the surface of the reed fiber improved the thermal stability of the reed fiber. Preparation examples 1-3, based on comparative preparation example 2, added ultrasonic treatment, further increasing the initial decomposition temperature. Among them, the initial decomposition temperature of preparation example 2 was relatively high, possibly because ultrasonic treatment is beneficial to promoting the esterification reaction, increasing the degree of esterification, and thus improving the thermal stability of the reed fiber. Preparation example 4 used a large amount of acetic anhydride, which slightly increased the initial decomposition temperature, but it also resulted in waste of raw materials. Preparation examples 5-7 successively reduced the amount of acetic anhydride, and the initial decomposition temperature gradually decreased. Taking all factors into consideration, the preferred solid-liquid ratio of pretreated fiber to acetic anhydride is 0.1-0.2 g / mL.
[0088] Preparation example of flame-retardant cellulose aerogel
[0089] Preparation Example 1 of Flame-Retardant Cellulose Aerogel
[0090] Flame-retardant cellulose aerogel, the preparation method of which includes the following steps:
[0091] Preparation of the first suspension: cellulose nanofibers were mixed with water and stirred at 1200 rpm for 5 h to obtain a first suspension with a solid content of 2% wt.
[0092] Preparation of the second suspension: Montmorillonite was mixed with water and stirred at 1200 rpm for 5 h to obtain a second suspension with a solid content of 1% wt.
[0093] Preparation of the mixture: The first suspension and the second suspension are mixed evenly to obtain the mixture;
[0094] Modification treatment: Melamine-formaldehyde resin and the mixture were mixed evenly. The mass ratio of cellulose nanofibers, melamine-formaldehyde resin and montmorillonite was 1:1:0.8 to obtain a composite liquid. The composite liquid was placed in a container and frozen in a liquid nitrogen / ethanol bath (-116℃) for 30 min. After being taken out, it was freeze-dried for 72 h under a vacuum of 1 Pa and a cold trap temperature of -55℃ to obtain flame-retardant cellulose aerogel.
[0095] Example 2 of the preparation of flame-retardant cellulose aerogel
[0096] The difference from Example 1, which prepared flame-retardant cellulose aerogel, is that the mass ratio of cellulose nanofibers, melamine-formaldehyde resin and montmorillonite is 1:1:0.5.
[0097] Example 3: Preparation of flame-retardant cellulose aerogel
[0098] The difference from Example 1, which prepared flame-retardant cellulose aerogel, is that the mass ratio of cellulose nanofibers, melamine-formaldehyde resin and montmorillonite is 1:1:0.9.
[0099] Example 4: Preparation of flame-retardant cellulose aerogel
[0100] The difference from Example 1 of the preparation of flame-retardant cellulose aerogel is that the mass ratio of cellulose nanofibers, melamine-formaldehyde resin and montmorillonite is 1:1:1.
[0101] Example 5: Preparation of flame-retardant cellulose aerogel
[0102] The difference from Example 1, which prepared flame-retardant cellulose aerogel, is that the mass ratio of cellulose nanofibers, melamine-formaldehyde resin and montmorillonite is 1:1:1.5.
[0103] Comparative Preparation Example 1 of Flame-Retardant Cellulose Aerogel
[0104] Cellulose aerogel, the preparation method of which includes the following steps:
[0105] Cellulose nanofibers were mixed with water and stirred at 1200 rpm for 5 h to obtain a first suspension with a solid content of 2% wt. The first suspension was placed in a container and frozen in a liquid nitrogen / ethanol bath (-116℃) for 30 min. After being removed, it was freeze-dried under a vacuum of 1 Pa and a cold trap temperature of -55℃ for 72 h to obtain cellulose aerogel.
[0106] Comparative Preparation Example 2 of Flame-Retardant Cellulose Aerogel
[0107] Flame-retardant cellulose aerogel, the preparation method of which includes the following steps:
[0108] Preparation of the first suspension: cellulose nanofibers were mixed with water and stirred at 1200 rpm for 5 h to obtain a first suspension with a solid content of 2% wt.
[0109] Preparation of the second suspension: Montmorillonite was mixed with water and stirred at 1200 rpm for 5 h to obtain a second suspension with a solid content of 1% wt.
[0110] Preparation of the mixture: The first suspension and the second suspension were mixed evenly, and the mass ratio of cellulose nanofibers and montmorillonite was 1:1.8 to obtain the mixture. The mixture was placed in a container and frozen in a liquid nitrogen / ethanol bath (-116℃) for 30 min. After being taken out, it was freeze-dried for 72 h under a vacuum of 1 Pa and a cold trap temperature of -55℃ to obtain flame-retardant cellulose aerogel.
[0111] Comparative Preparation Example 3 of Flame-Retardant Cellulose Aerogel
[0112] Flame-retardant cellulose aerogel, the preparation method of which includes the following steps:
[0113] Preparation of the first suspension: cellulose nanofibers were mixed with water and stirred at 1200 rpm for 5 h to obtain a first suspension with a solid content of 2% wt.
[0114] Modification treatment: Melamine-formaldehyde resin was mixed evenly with the first suspension, and the mass ratio of cellulose nanofibers to melamine-formaldehyde resin was 1:1.8 to obtain a composite liquid. The composite liquid was placed in a container and frozen in a liquid nitrogen / ethanol bath (-116℃) for 30 min. After being taken out, it was freeze-dried for 72 h under a vacuum of 1 Pa and a cold trap temperature of -55℃ to obtain flame-retardant cellulose aerogel.
[0115] Performance testing method for flame-retardant cellulose aerogel: Preparation examples 1-5 and comparative preparation examples 1-3 of flame-retardant cellulose aerogel were used as test samples. The thermal stability of the flame-retardant cellulose aerogel was analyzed using a STA449F3 thermogravimetric analyzer (TGA) from Netzsch GmbH, Germany. Nitrogen was used as the protective atmosphere during the test. The temperature was raised from room temperature to 800℃ at a heating rate of 10℃ / min. Thermogravimetric analysis curves and derivative thermogravimetric analysis curves were plotted. The maximum decomposition temperature and residual amount were recorded. The results are shown in Table 2.
[0116] Table 2. Performance test results of flame-retardant cellulose aerogel
[0117]
[0118]
[0119] Combining the preparation examples 1-5 of flame-retardant cellulose aerogels with the comparative preparation examples 1-3 of flame-retardant cellulose aerogels and referring to Table 2, it can be seen that comparative preparation example 1 yielded ordinary cellulose aerogels, with the lowest maximum decomposition temperature and residual amount, indicating that ordinary cellulose aerogels have poor heat resistance; comparative preparation example 2, based on comparative preparation example 1, added montmorillonite, resulting in a slight decrease in the maximum decomposition temperature but a significant increase in the residual amount, indicating that montmorillonite can improve the heat resistance of cellulose aerogels; comparative preparation example 3, based on comparative preparation example 1, added melamine-formaldehyde resin, resulting in a decrease in the maximum decomposition temperature and residual amount. The significant increase in residual amount indicates that melamine-formaldehyde resin can improve the heat resistance of cellulose aerogel. In Preparation Example 1, montmorillonite and melamine-formaldehyde resin were added simultaneously to Preparation Example 1, and the maximum decomposition temperature and residual amount were further increased, indicating that the combination of montmorillonite and melamine-formaldehyde resin can improve the heat resistance of cellulose aerogel. In Preparation Examples 2-5, the amount of montmorillonite was increased in sequence, and the maximum decomposition temperature first increased and then decreased, while the residual amount gradually increased. Therefore, the preferred mass ratio of cellulose nanofibers, melamine-formaldehyde resin and montmorillonite is 1:1:(0.8-1).
[0120] Preparation example of modified plant fiber
[0121] Example 1: Preparation of modified plant fibers
[0122] The modified plant fiber is prepared by the following steps:
[0123] Preparation of the first suspension: cellulose nanofibers were mixed with water and stirred at 1200 rpm for 5 h to obtain a first suspension with a solid content of 2% wt.
[0124] Preparation of the second suspension: Montmorillonite was mixed with water and stirred at 1200 rpm for 5 h to obtain a second suspension with a solid content of 1% wt.
[0125] Preparation of the mixture: The first suspension and the second suspension are mixed evenly to obtain the mixture;
[0126] Modification treatment: Melamine-formaldehyde resin and the mixed solution were mixed evenly. The mass ratio of cellulose nanofibers, melamine-formaldehyde resin and montmorillonite was 1:1:0.8 to obtain a composite solution. The hydrophobically modified reed fiber was soaked in the composite solution for 10 min. The hydrophobically modified reed fiber was prepared by Example 2 of preparation of hydrophobically modified reed fiber. After being taken out, it was placed in a container and frozen in a liquid nitrogen / ethanol bath (-116℃) for 30 min. After being taken out, it was freeze-dried for 72 h under a vacuum of 1 Pa and a cold trap temperature of -55℃ to obtain modified plant fiber.
[0127] Example 2 of the preparation of modified plant fibers
[0128] The difference from Example 1 of the preparation of modified plant fiber is that the hydrophobic modified reed fiber was prepared by Example 5 of the preparation of hydrophobic modified reed fiber.
[0129] Example 3: Preparation of modified plant fibers
[0130] The difference from Example 2, which describes the preparation of modified plant fibers, is that the mass ratio of cellulose nanofibers, melamine-formaldehyde resin and montmorillonite is 1:1:0.9.
[0131] Comparative Preparation Example 1 of Modified Plant Fibers
[0132] The modified plant fiber is prepared by the following steps:
[0133] Cellulose nanofibers were mixed with water and stirred at 1200 rpm for 5 h to obtain a first suspension with a solid content of 2% wt. Hydrophobic modified reed fibers were soaked in the first suspension for 10 min. The hydrophobic modified reed fibers were prepared by Comparative Preparation Example 1 of hydrophobic modified reed fibers. After being removed, the fibers were placed in a container and frozen in a liquid nitrogen / ethanol bath (-116℃) for 30 min. After being removed, the fibers were freeze-dried for 72 h under a vacuum of 1 Pa and a cold trap temperature of -55℃ to obtain modified plant fibers.
[0134] Comparative Preparation Example 2 of Modified Plant Fibers
[0135] The modified plant fiber is prepared by the following steps:
[0136] Preparation of the first suspension: cellulose nanofibers were mixed with water and stirred at 1200 rpm for 5 h to obtain a first suspension with a solid content of 2% wt.
[0137] Preparation of the second suspension: Montmorillonite was mixed with water and stirred at 1200 rpm for 5 h to obtain a second suspension with a solid content of 1% wt.
[0138] Preparation of the mixture: The first suspension and the second suspension were mixed evenly, and the mass ratio of cellulose nanofibers and montmorillonite was 1:1.8 to obtain the mixture. The hydrophobically modified reed fiber was soaked in the mixture for 10 min. The hydrophobically modified reed fiber was prepared by Comparative Preparation Example 1 of hydrophobically modified reed fiber. After being taken out, it was placed in a container and frozen in a liquid nitrogen / ethanol bath (-116℃) for 30 min. After being taken out, it was freeze-dried for 72 h under a vacuum of 1 Pa and a cold trap temperature of -55℃ to obtain the modified plant fiber.
[0139] Comparative Preparation Example 3 of Modified Plant Fibers
[0140] The modified plant fiber is prepared by the following steps:
[0141] Preparation of the first suspension: cellulose nanofibers were mixed with water and stirred at 1200 rpm for 5 h to obtain a first suspension with a solid content of 2% wt.
[0142] Modification treatment: Melamine-formaldehyde resin and the first suspension were mixed evenly. The mass ratio of cellulose nanofibers to melamine-formaldehyde resin was 1:1.8 to obtain a composite solution. The hydrophobically modified reed fiber was soaked in the composite solution for 10 min. The hydrophobically modified reed fiber was prepared by Comparative Preparation Example 1 of hydrophobically modified reed fiber. After being taken out, it was placed in a container and frozen in a liquid nitrogen / ethanol bath (-116℃) for 30 min. After being taken out, it was freeze-dried for 72 h under a vacuum of 1 Pa and a cold trap temperature of -55℃ to obtain modified plant fiber.
[0143] Performance test method of modified plant fiber: The preparation examples 1-3 and the comparative preparation examples 1-3 of modified plant fiber were used as test samples. The thermal stability of flame-retardant cellulose aerogel was analyzed using a STA449F3 thermogravimetric analyzer (TGA) from Netzsch GmbH, Germany. Nitrogen was used as the protective atmosphere during the test. The temperature was raised from room temperature to 800℃ at a heating rate of 10℃ / min. Thermogravimetric analysis curves and derivative thermogravimetric analysis curves were plotted, and the maximum decomposition temperature was recorded. The results are shown in Table 3.
[0144] Table 3. Performance test results of modified plant fibers
[0145] Preparation Example No. Maximum decomposition temperature / °C Example 1: Preparation of modified plant fibers 323.4 Example 2 of the preparation of modified plant fibers 324.7 Example 3: Preparation of modified plant fibers 325.9 Comparative Preparation Example 1 of Modified Plant Fibers 288.0 Comparative Preparation Example 2 of Modified Plant Fibers 294.5 Comparative Preparation Example 3 of Modified Plant Fibers 313.4
[0146] Combining the preparation examples 1-3 of modified plant fibers with the comparative preparation examples 1-3 of modified plant fibers and referring to Table 3, it can be seen that: Comparative preparation example 1, which uses ordinary cellulose aerogel to encapsulate ordinary reed fibers, has the lowest maximum decomposition temperature; Comparative preparation example 2, which uses montmorillonite-modified cellulose aerogel to encapsulate ordinary reed fibers, has a slightly higher maximum decomposition temperature, indicating that the combination of montmorillonite-modified cellulose aerogel and reed fibers improves heat resistance; Comparative preparation example 3, which uses melamine-formaldehyde resin-modified cellulose aerogel to encapsulate ordinary reed fibers, has a slightly higher maximum decomposition temperature, indicating that the combination of melamine-formaldehyde resin-modified cellulose aerogel and reed fibers improves heat resistance; Preparation examples 1-3 all use flame-retardant cellulose aerogel to encapsulate hydrophobically modified reed fibers, further increasing the maximum decomposition temperature, indicating that the combination of flame-retardant cellulose aerogel and hydrophobically modified reed fibers improves heat resistance.
[0147] Example
[0148] Example 1
[0149] A polyurethane flame-retardant and heat-insulating material, the raw materials of which include the following components in parts by weight:
[0150] 10 kg of polyether polyol, which is polyethylene glycol with a hydroxyl value of 535 mg KOH / g;
[0151] 5 kg of flame retardant, the flame retardant is aluminum hydroxide;
[0152] 1 kg of foam stabilizer, which is dimethyl silicone oil;
[0153] 0.2 kg of foaming agent, which is water;
[0154] 0.01 kg of catalyst, the catalyst being triethylenediamine;
[0155] 0.5 kg of surfactant, the surfactant being sodium dodecyl sulfate;
[0156] 20 kg of isocyanate, the isocyanate being 4,4'-diphenylmethane diisocyanate;
[0157] 5 kg of modified plant fiber, which was prepared by Example 1 of the preparation of modified plant fiber.
[0158] A method for preparing polyurethane flame-retardant thermal insulation material includes the following steps:
[0159] Step 1: Mix polyether polyol, flame retardant, foam stabilizer, foaming agent, catalyst, surfactant and modified plant fiber evenly to obtain a mixture;
[0160] Step 2: Add isocyanate to the mixture, mix well, let stand for 1 hour, heat to 60℃ and react for 12 hours to obtain polyurethane flame retardant and heat insulation material.
[0161] Example 2
[0162] The difference from Example 1 is that its raw materials include the following components in parts by weight:
[0163] 15 kg of polyether polyol;
[0164] 10 kg of flame retardant;
[0165] 2 kg of foam stabilizer;
[0166] 0.5 kg of foaming agent;
[0167] Catalyst 0.025 kg;
[0168] 1 kg of surfactant;
[0169] 25 kg of isocyanate;
[0170] 5 kg of modified plant fiber.
[0171] Example 3
[0172] The difference from Example 1 is that its raw materials include the following components in parts by weight:
[0173] 20 kg of polyether polyol;
[0174] 15 kg of flame retardant;
[0175] 3 kg of foam stabilizer;
[0176] 0.8 kg of foaming agent;
[0177] Catalyst 0.04 kg;
[0178] 1.5 kg of surfactant;
[0179] 30 kg of isocyanate;
[0180] 5 kg of modified plant fiber.
[0181] Examples 4-5
[0182] The difference from Example 2 is that the modified plant fiber was prepared sequentially from the preparation examples 2-3 of the modified plant fiber.
[0183] Example 6
[0184] The difference from Example 5 is that the mass of the modified plant fiber is 8 kg.
[0185] Example 7
[0186] The difference from Example 5 is that the mass of the modified plant fiber is 10 kg.
[0187] Comparative Example
[0188] Comparative Example 1
[0189] The difference from Example 1 is that no modified plant fiber was added.
[0190] Comparative Examples 2-4
[0191] The difference from Example 1 is that the modified plant fiber was prepared sequentially from the comparative preparation examples 1-3 of the modified plant fiber.
[0192] Application Example 1
[0193] A heat-insulating aluminum alloy includes a heat-insulating layer and aluminum alloy profiles located on both sides of the heat-insulating layer. The heat-insulating layer is made of polyurethane flame-retardant heat-insulating material as described in Example 1.
[0194] Performance testing
[0195] Test methods
[0196] Test samples: The polyurethane flame-retardant thermal insulation materials from Examples 1-7 and Comparative Examples 1-4 were used as samples.
[0197] (1) The compressive strength of the sample was tested according to the method specified in GB / T 8813-2020 "Determination of compressive properties of rigid foamed plastics".
[0198] (2) The tensile strength of the sample shall be tested in accordance with the method specified in GB 9641-88 "Test Method for Tensile Properties of Rigid Foamed Plastics".
[0199] (3) Test the oxygen index of the sample according to the method specified in GB T2406-93 "Test Method for Burning Performance of Plastics - Oxygen Index Method".
[0200] (4) Test the thermal conductivity of the sample according to the method specified in ASTM C518, "Standard Test Method for Determining Steady-State Heat Transfer Properties with a Heat Flow Meter Apparatus".
[0201] The test results are shown in Table 4.
[0202] Table 4 Performance test results of polyurethane flame-retardant thermal insulation materials
[0203]
[0204]
[0205] Combining Examples 1-7 and Comparative Examples 1-4 with Table 4, it can be seen that the thermal conductivity of Examples 1-7 and Comparative Examples 1-4 is between 0.02-0.03 W / (m·K), indicating good thermal insulation performance. This shows that the addition of modified plant fibers does not significantly affect the thermal insulation performance of polyurethane flame-retardant insulation materials. In Comparative Example 1, without the addition of modified plant fibers, the compressive strength, tensile strength, and oxygen index are the lowest. In Comparative Example 2, after adding ordinary reed fibers wrapped in ordinary cellulose aerogel, the compressive strength and tensile strength are significantly improved, while the oxygen index remains relatively unchanged. This indicates that modified plant fibers can improve the mechanical properties of polyurethane flame-retardant insulation materials, but the flame-retardant performance needs further improvement. In Comparative Example 3, montmorillonite was added to the cellulose aerogel, resulting in a significant increase in compressive strength, tensile strength, and oxygen index. This indicates that modified plant fibers with added montmorillonite can improve the mechanical and flame-retardant properties of polyurethane flame-retardant insulation materials. In Example 4, melamine-formaldehyde resin was added to cellulose aerogel, resulting in a significant increase in compressive strength, tensile strength, and oxygen index. This indicates that the modified plant fiber with added melamine-formaldehyde resin can improve the mechanical and flame-retardant properties of polyurethane flame-retardant insulation materials. Examples 1-3 used raw materials with different proportions to prepare polyurethane flame-retardant insulation materials. Among them, Example 2 had higher compressive strength, tensile strength, and oxygen index. Examples 4-5 used modified plant fibers prepared by different methods, and the compressive strength, tensile strength, and oxygen index all changed. This indicates that the preparation method of modified plant fibers affects the performance of modified plant fibers, and thus affects the mechanical and flame-retardant properties of polyurethane flame-retardant insulation materials. In Examples 6-7, the amount of modified plant fiber was gradually increased, and the compressive strength, tensile strength, and oxygen index gradually increased. However, the increase in Example 7 was smaller. Therefore, Example 6 had better overall performance.
[0206] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.
Claims
1. A polyurethane fire-retardant insulating material, characterized in that: The raw materials include the following components by weight: Polyether polyol 10-20 parts; Flame retardant 5-15 parts; Foam stabilizer 1-3 parts; Foaming agent 0.2-0.8 parts; Catalyst 0.01-0.04 parts; Surfactant 0.5-1.5 parts; Isocyanate 20-30 parts; Modified plant fiber 5-10 parts; The modified plant fiber comprises hydrophobically modified reed fiber and a flame-retardant cellulose aerogel layer coated on the surface of the hydrophobically modified reed fiber; The preparation method of the hydrophobically modified reed fiber comprises the following steps: Crushing treatment: after the reed rod is dried, it is subjected to shearing crushing to obtain reed fiber; Pretreatment: the reed fiber is uniformly mixed with water, left to stand, subjected to ultrasonic treatment, subjected to solid-liquid separation, washed with water, and dried to obtain pretreated fiber; Hydrophobic modification: the pretreated fiber is added into an ice acetic acid solution, uniformly mixed, subjected to microwave treatment, taken out and cooled to room temperature, added with acetic anhydride and concentrated sulfuric acid, uniformly mixed, subjected to esterification reaction under microwave conditions, subjected to solid-liquid separation after the reaction is completed, washed with water until neutral, and dried to obtain hydrophobically modified reed fiber; The preparation method of the modified plant fiber comprises the following steps: Preparation of a first suspension: cellulose nanofiber is uniformly mixed with water to obtain a first suspension; Preparation of a second suspension: montmorillonite is uniformly mixed with water to obtain a second suspension; Preparation of a mixed solution: the first suspension and the second suspension are uniformly mixed to obtain a mixed solution; Modification treatment: melamine formaldehyde resin is uniformly mixed with the mixed solution to obtain a composite solution, the hydrophobically modified reed fiber is soaked in the composite solution, taken out and placed in a container, frozen in a liquid nitrogen / ethanol bath, taken out and subjected to freeze drying under vacuum conditions to obtain modified plant fiber.
2. A polyurethane fire-retardant insulating material according to claim 1, characterised in that: The ultrasonic treatment has a frequency of 50-60 kHz and a time of 5-10 min.
3. A polyurethane fire-retardant insulating material according to claim 1, characterized in that: The microwave treatment has a power of 380-420 W and a time of 4-8 min; the esterification reaction has a microwave power of 300-340 W and a time of 1-2 min.
4. The polyurethane fire barrier insulation material of claim 1, wherein: In the hydrophobic modification, the solid-liquid ratio of the pretreated fiber to acetic anhydride is 0.1-0.2 g / mL.
5. The polyurethane fire barrier insulation material of claim 1, wherein: The mass ratio of the cellulose nanofiber, the melamine formaldehyde resin and the montmorillonite is 1:1: (0.8-1).
6. A polyurethane fire-retardant insulating material according to claim 1, characterized in that: The freeze drying is performed at a temperature of -55 ~ -60 ℃ for 70-80 h.
7. Process for the production of the polyurethane flame- retardant thermal insulation material according to any one of claims 1 to 6, characterized in that: The method comprises the following steps: Step one: polyether polyol, flame retardant, foam stabilizer, foaming agent, catalyst, surfactant and modified plant fiber are uniformly mixed to obtain a mixture; Step two: isocyanate is added to the mixture, uniformly mixed, left to stand, subjected to heating reaction, and polyurethane flame-retardant thermal insulation material is obtained.
8. A thermally insulated aluminum alloy comprising a thermally insulating layer and aluminum alloy profiles on both sides of the thermally insulating layer, characterized in that: The thermal insulation layer is made of the polyurethane flame-retardant thermal insulation material according to any one of claims 1-6.
Citation Information
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