Multifunctional bio-based polyurethane foams and methods for making the same

Abstract

The present application relates to a kind of multifunctional bio-based polyurethane foam, including polyurethane foam matrix and composite coating loaded on the surface of polyurethane foam matrix;Polyurethane foam matrix is prepared by foaming reaction of A component and B component, A component includes palm oil-based polyol, polyether polyol, chain extender, catalyst, foam stabilizer and foaming agent, and B component is polyisocyanate;Composite coating is composed of flame-retardant coating, radiation cooling coating and super-hydrophobic protective layer, flame-retardant coating includes phosphite chitosan and nano zinc oxide, radiation cooling coating includes nano silicon dioxide and nano zinc oxide, and super-hydrophobic protective layer is polydimethylsiloxane coating.The multifunctional bio-based polyurethane foam in the present application is endowed with shape memory performance by palm oil-based polyol formula regulation, and is endowed with flame-retardant, super-hydrophobic and radiation cooling function on the surface of foam after layering coating post-processing, realizes the multifunctional synergy of material intrinsic and surface.

Description

Technical Field

[0001] This invention relates to the field of polyurethane foam, and particularly to a multifunctional bio-based polyurethane foam, as well as a method for preparing the aforementioned multifunctional bio-based polyurethane foam. Background Technology

[0002] Polyurethane foam is widely used in furniture, transportation, and packaging due to its lightweight, excellent cushioning properties, and ease of processing. Soft polyurethane foam, in particular, is a core material for mattresses and cushions. Viscoelastic polyurethane foam, often called shape memory foam, has a slower recovery rate after compression, providing effective support and high fatigue strength. It can adaptively adjust to changes in body temperature and posture, making it a promising candidate for high-end bedding.

[0003] However, existing polyurethane foam materials still face the following technical bottlenecks: First, their raw materials mainly rely on increasingly depleted petroleum resources, and the finished products are difficult to degrade after disposal, causing an environmental burden. Although researchers have tried to use vegetable oil-based polyols, such as castor oil and palm oil, to replace petroleum-based raw materials, purely bio-based foams often lack sufficient mechanical strength and have limited functionality, making it difficult to meet the needs of high-end applications. Second, the porous structure of polyurethane foam makes it highly flammable, and its rapid combustion releases large amounts of heat and toxic fumes, posing a serious threat to life and property safety. While traditional additive flame retardants can improve flame retardancy, they often deteriorate the mechanical properties and resilience of the foam. Finally, traditional mattresses are difficult to adaptively adjust to ambient temperature, especially in hot summers, easily causing stuffiness and discomfort, affecting sleep quality.

[0004] Surface coating technology has attracted widespread attention due to its minimal impact on the intrinsic structure of foam and its simple processing. Studies have shown that coatings using phosphorylated chitosan and nano-zinc oxide can effectively improve the flame retardant properties of polyurethane foam. Furthermore, constructing micro-nano rough structures using nanoparticle coatings, combined with low surface energy materials, can achieve superhydrophobic self-cleaning surfaces; while nano-silica and zinc oxide coatings of specific particle sizes exhibit high reflectivity to sunlight and high emissivity in the mid-infrared band, enabling passive radiative cooling for temperature regulation.

[0005] However, to date, no technology has been able to efficiently integrate the four major functions of bio-based shape memory, high-efficiency flame retardancy, superhydrophobic self-cleaning, and temperature regulation into a single foam material. Existing technologies either have limited functionality or their functions are mutually antagonistic, making it difficult to meet the diverse needs of modern high-end mattresses for safety, environmental protection, health, comfort, and intelligence. Therefore, developing a green and environmentally friendly bio-based polyurethane foam material that combines the above functions has significant research value and broad market prospects. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a multifunctional bio-based polyurethane foam that integrates flame retardancy, superhydrophobicity, temperature adjustability and shape memory functions, as well as a method for preparing the above-mentioned multifunctional bio-based polyurethane foam.

[0007] To solve the above-mentioned technical problems, the technical solution of the present invention is: a multifunctional bio-based polyurethane foam, the innovation of which is: including a polyurethane foam matrix and a composite coating loaded on the surface of the polyurethane foam matrix. The polyurethane foam matrix is ​​prepared by a foaming reaction of component A and component B. Component A includes palm oil-based polyol, polyether polyol, chain extender, catalyst, foam stabilizer and foaming agent, and component B is polyisocyanate. The composite coating is composed of a flame-retardant coating, a radiation-cooling coating, and a superhydrophobic protective layer distributed sequentially from the inside out. The flame-retardant coating is a composite layer of phosphorylated chitosan and nano zinc oxide, and forms a phosphorus-nitrogen synergistic carbonization structure when heated. The radiation-cooling coating is a composite layer of nano silica and nano zinc oxide, and forms a micro-nano composite scattering structure. The superhydrophobic protective layer is a polydimethylsiloxane coating that covers the surface of the micro-nano composite scattering structure to form a low surface energy layer.

[0008] Furthermore, the apparent density of the polyurethane foam matrix is ​​85-115 kg / m³. 3 The shape fixation rate is ≥95%, the shape recovery rate is ≥94%, the total weight gain of the polyurethane foam matrix after three-layer coating treatment is 10-20%, the limiting oxygen index is ≥25%, it can pass the UL-94 V-0 vertical burning test, the water contact angle is ≥150°, the solar reflectivity is ≥92%, the infrared emissivity is ≥94%, and the outdoor cooling effect is ≥10℃.

[0009] Furthermore, the palm oil-based polyol has a hydroxyl value of 300-400 mg KOH / g and a viscosity of 80-120 mPa·s at 50°C. The catalyst is a composite catalyst of stannous octoate and triethylenediamine. The foaming agent is deionized water. The foam stabilizer is a polyether-modified silicone surfactant. The polyisocyanate is toluene diisocyanate, and the isocyanate index R value is 0.90-1.20.

[0010] Furthermore, component A comprises 30-70 parts of palm oil-based polyol, 0-60 parts of polyether polyol, 0-2.0 parts of chain extender, 0.3-0.8 parts of catalyst, 1.0-2.0 parts of foam stabilizer and 2.0-5.0 parts of blowing agent, and component B comprises 35.0-55.0 parts of polyisocyanate.

[0011] Furthermore, in the flame-retardant coating, the mass ratio of phosphorylated chitosan to nano-zinc oxide is 8:1 to 4:1, the particle size of the nano-zinc oxide is ≤100 nm, and the flame-retardant coating forms a primary rough structure on the surface of the polyurethane foam matrix with a surface roughness of 1-10 μm; in the radiation-cooling coating, the mass ratio of nano-silica to nano-zinc oxide is 3:1 to 2:1, the particle size of nano-silica is 20-50 nm, the particle size of nano-zinc oxide is 100-500 nm, and the radiation-cooling coating is partially embedded in the flame-retardant coating to form an interfacial interpenetrating structure; the mass concentration of polydimethylsiloxane in the superhydrophobic protective layer is 0.5-3.0 wt%.

[0012] An innovative method for preparing multifunctional bio-based polyurethane foam includes the following steps: Preparation of S1 palm oil-based polyol: Palm oil and triethanolamine were mixed in a molar ratio of 1:3 and reacted at 170°C under zinc acetate catalysis for 2 hours to obtain palm oil-based polyol. Preparation of S2 foam matrix: Palm oil-based polyol, polyether polyol, chain extender, catalyst, foam stabilizer and blowing agent are mixed evenly to obtain component A. After adding polyisocyanate of component B and stirring at high speed, the mixture is injected into a mold for foaming and curing to obtain polyurethane foam matrix. Preparation of S3 phosphorylated chitosan: Chitosan powder was prepared into a 1.0 wt% aqueous suspension, stirred at 50°C, and phosphorous acid was gradually added during stirring until the solution became clear and transparent. After cooling, a phosphorylated chitosan solution was obtained. S4 Flame retardant coating: Add nano zinc oxide to the phosphorylated chitosan solution in step S3 and stir to mix to obtain the first coating liquid. Immerse the foam matrix obtained in step S2 into the first coating liquid, extrude and dry to cure to obtain foam with a coating layer. S5 Radiation Cooling Coating: The foam with one layer of coating obtained in step S4 is immersed in a second coating liquid containing nano-silica, nano-zinc oxide and polymer binder. After immersion, it is squeezed, dried and cured to obtain foam with two layers of coating. S6 Superhydrophobic protective layer coating: Immerse the foam with two coating layers obtained in step S5 into a third coating liquid containing polydimethylsiloxane, briefly wet it, and then squeeze, dry and cure it to obtain the desired multifunctional bio-based polyurethane foam.

[0013] Furthermore, in steps S4-S6, the weight gain rate of the coating in each step is controlled at 3-8%, and the total weight gain rate is controlled at 10-20%; in step S4, the drying and curing conditions are drying at 80℃ for 2 hours; in step S5, the drying and curing conditions are drying at 60-80℃ for 2-3 hours; and in step S6, the drying and curing conditions are drying at 80-100℃ for 1-2 hours.

[0014] Furthermore, in step S4, the solid content of the phosphorylated chitosan solution in the first coating liquid is 0.5-1.0 wt%, and the amount of nano zinc oxide added makes the mass ratio of phosphorylated chitosan to nano zinc oxide 8:1 to 4:1. In step S5, the second coating liquid contains 1.0-4.0 parts by mass of nano-silica, 0.5-2.0 parts by mass of nano-zinc oxide, 0.5-2.0 parts by mass of polymer binder, and acetone as the solvent. In step S6, the mass concentration of polydimethylsiloxane prepolymer and its curing agent in the third coating liquid is 0.5-3.0 wt%, and the solvent is ethyl acetate.

[0015] Furthermore, in step S2, the catalyst is a composite catalyst of stannous octoate and triethylenediamine, the foaming agent is deionized water, the foam stabilizer is a polyether-modified organosilicon surfactant, the polyisocyanate is toluene diisocyanate, and the isocyanate index R value is 0.90-1.20.

[0016] The beneficial effects of the present invention are as follows: The multifunctional bio-based polyurethane foam of the present invention uses palm oil-based polyols to provide flexible soft segments and isocyanates to form hard segment structures, constructing a soft and hard segment phase separation system to achieve its shape memory effect. The shape fixation rate and recovery rate of the foam can reach more than 95%, and it has a sensitive response to temperature, can adapt to the human body curve, and provide durable support.

[0017] Significantly improved flame retardant performance: The phosphorylated chitosan / nano zinc oxide coating forms a dense char layer on the foam surface, effectively inhibiting heat and oxygen transfer. The limiting oxygen index can reach more than 25%, and it can pass the UL-94 V-0 vertical burning test. The peak heat release rate is reduced by more than 59%.

[0018] Superhydrophobic and self-cleaning surface: The three-layer coating works synergistically. The outermost layer of polydimethylsiloxane provides low surface energy, while the inner layer of nanoparticles constructs a micro-nano rough structure, making the water contact angle of the foam surface greater than 150°, achieving superhydrophobicity. It can effectively resist the intrusion of sweat, water stains, urine stains, etc., inhibit bacterial growth, and is easy to clean.

[0019] Passive radiative cooling and temperature regulation: The nano-SiO2 and ZnO in the radiative cooling layer have high reflectivity to sunlight, with an average reflectivity of up to 94.5%, and high emissivity in the mid-infrared band, up to 96.8%. In hot weather, the foam can effectively reflect sunlight and dissipate its own heat to outer space through infrared radiation, achieving passive cooling. The daytime temperature reduction can reach 12.4℃, improving user comfort.

[0020] Green, environmentally friendly and sustainable: Palm oil-based polyols are used to replace some petroleum-based raw materials, and the flame-retardant coating uses bio-based chitosan. The overall bio-based content of the material is high, which is in line with the concept of sustainable development.

[0021] This invention, through material design and process innovation, successfully integrates flame retardancy, superhydrophobicity, temperature regulation, and shape memory functions into bio-based polyurethane foam, providing a high-performance, environmentally friendly new material solution for the field of smart and healthy bedding. It can be applied to fields such as smart mattresses, meeting the diverse needs of modern bedding for green environmental protection, health and comfort, and intelligent temperature control. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the multifunctional bio-based polyurethane foam of the present invention.

[0023] Figure 2 This is a comparison diagram of the flame retardant effects of the multifunctional bio-based polyurethane foam of the present invention.

[0024] Figure 3 This is a comparison diagram of the superhydrophobic effect of the multifunctional bio-based polyurethane foam of the present invention.

[0025] Figure 4 This is a comparison diagram of the shape memory properties of the multifunctional bio-based polyurethane foam of the present invention.

[0026] Figure 5 This is a comparison chart showing the temperature regulation effect of the multifunctional bio-based polyurethane foam of the present invention. Detailed Implementation

[0027] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with the accompanying drawings and preferred embodiments, is provided below.

[0028] like Figure 1 The invention illustrates a multifunctional bio-based polyurethane foam, comprising a polyurethane foam matrix 1 and a composite coating loaded on the surface of the polyurethane foam matrix.

[0029] The polyurethane foam matrix 1 is prepared by a foaming reaction of component A and component B. Component A includes palm oil-based polyol, polyether polyol, chain extender, catalyst, foam stabilizer and foaming agent, and component B is polyisocyanate.

[0030] The composite coating consists of a flame-retardant coating 2, a radiation-cooling coating 3, and a superhydrophobic protective layer 4, which are distributed sequentially from the inside out. The flame-retardant coating 2 is a composite layer of phosphorylated chitosan and nano zinc oxide, and the flame-retardant coating forms a phosphorus-nitrogen synergistic carbonization structure when heated. The radiation-cooling coating 3 is a composite layer of nano silica and nano zinc oxide, and the radiation-cooling coating 3 forms a micro-nano composite scattering structure. The superhydrophobic protective layer 4 is a polydimethylsiloxane coating that covers the surface of the micro-nano composite scattering structure to form a low surface energy layer.

[0031] The apparent density of polyurethane foam matrix 1 is 85-115 kg / m³. 3 Shape fixation rate ≥95%, shape recovery rate ≥94%, polyurethane foam matrix 1 after three-layer coating treatment, total weight gain rate 10-20%, limiting oxygen index ≥25%, can pass UL-94 V-0 level vertical burning test, water contact angle ≥150°, solar reflectivity ≥92%, infrared emissivity ≥94%, outdoor cooling effect ≥10℃.

[0032] The palm oil-based polyol has a hydroxyl value of 300-400 mg KOH / g and a viscosity of 80-120 mPa·s at 50℃. The catalyst is a composite catalyst of stannous octoate and triethylenediamine. The foaming agent is deionized water. The foam stabilizer is a polyether-modified silicone surfactant. The polyisocyanate is toluene diisocyanate, and the isocyanate index R value is 0.90-1.20.

[0033] Component A consists of 30-70 parts of palm oil-based polyol, 0-60 parts of polyether polyol, 0-2.0 parts of chain extender, 0.3-0.8 parts of catalyst, 1.0-2.0 parts of foam stabilizer and 2.0-5.0 parts of blowing agent, and Component B consists of 35.0-55.0 parts of polyisocyanate.

[0034] In the flame-retardant coating 2, the mass ratio of phosphorylated chitosan to nano zinc oxide is 8:1 to 4:1, and the particle size of nano zinc oxide is ≤100 nm. The flame-retardant coating 2 forms a primary rough structure on the surface of the polyurethane foam matrix 1, with a surface roughness of 1-10 μm. In the radiation-cooling coating 3, the mass ratio of nano silica to nano zinc oxide is 3:1 to 2:1, the particle size of nano silica is 20-50 nm, and the particle size of nano zinc oxide is 100-500 nm. The radiation-cooling coating 3 is partially embedded in the flame-retardant coating to form an interfacial interpenetrating structure. In the superhydrophobic protective layer 4, the mass concentration of polydimethylsiloxane is 0.5-3.0 wt%.

[0035] The above-mentioned multifunctional bio-based polyurethane foam is prepared through the following steps: Example 1

[0036] Preparation of S1 palm oil-based polyol: Palm oil and triethanolamine are mixed at a molar ratio of 1:3, and 0.3% zinc acetate by weight of palm oil is added as a catalyst. The mixture is stirred at 170℃ for 2-3 hours. Palm oil-based polyol is obtained by transesterification. The hydroxyl value of the obtained palm oil-based polyol is 300-400 mg KOH / g, the viscosity at 50℃ is 80-120 mPa·s, and the functionality is 2.5-3.5.

[0037] Preparation of S2 foam matrix: Palm oil-based polyol, polyether polyol, chain extender, catalyst, foam stabilizer and blowing agent are added to the reaction vessel according to the formula. The mixture is stirred and mixed evenly at 1000-2000 rpm at 25-40℃ to obtain component A. The measured amount of component B is added to component A and immediately stirred at high speed at 2500-3500 rpm for 10-20 seconds. When the system turns white and begins to foam, it is quickly poured into a mold preheated to 30-50℃. The mold is closed and foaming is carried out. The foam is demolded after curing at room temperature for 24-48 hours to obtain polyurethane foam matrix 1.

[0038] In the above steps, component A contains: 30.0-70.0 parts of palm oil-based polyol prepared in step S1; 0-60.0 parts of polyether polyol with a hydroxyl value of 56 mg KOH / g and a molecular weight of 3000 g / mol, used to adjust the basic physical properties of the foam, purchased from Jiangsu Luyuan New Materials Co., Ltd.; 0-2.0 parts of chain extender, which is diethylene glycol; 0.3-0.8 parts of catalyst, which is a composite catalyst of stannous octoate and triethylenediamine; 1.0-2.0 parts of foam stabilizer, which is a polyether-modified organosilicon surfactant; and 2.0-5.0 parts of deionized water as a chemical foaming agent.

[0039] Component B is toluene diisocyanate: 35.0 to 55.0 parts, with an NCO content of 30-32%. The amount of isocyanate used should be such that the isocyanate index (R value, i.e., the molar ratio of NCO to total OH) is 0.90 to 1.20.

[0040] Preparation of S3 phosphorylated chitosan: Chitosan powder was prepared into a 1.0 wt% aqueous suspension, stirred at 50°C, and phosphorous acid was gradually added during stirring until the solution became clear and transparent. After cooling, a phosphorylated chitosan solution was obtained. The chitosan (degree of deacetylation 95%) and phosphorous acid were purchased from Sinopharm Chemical Reagent Co., Ltd.

[0041] S4 Flame-retardant coating: Add nano zinc oxide to the phosphorylated chitosan solution in step S3 and stir to obtain the first coating liquid. Immerse the foam matrix obtained in step S2 into the first coating liquid. By repeatedly squeezing, the coating liquid is fully inserted into the interior of the polyurethane foam matrix 1. After taking it out, use a roller to squeeze out excess liquid and dry and cure at 80°C for 2 hours to form a flame-retardant functional layer on the foam skeleton, thus obtaining a foam with a coating layer.

[0042] In the first coating solution, there are 1.0 to 5.0 parts of phosphorylated chitosan, 0.1 to 2.0 parts of nano zinc oxide, and 93.0 to 98.9 parts of deionized water. The phosphorylated chitosan is prepared in step S3. The nano zinc oxide has a particle size ≤100 nm and a particle size of 100-500 nm. It was purchased from Aladdin Reagent Company.

[0043] S5 Radiation Cooling Coating: The foam with one layer of coating obtained in step S4 is immersed in a second layer coating liquid containing nano-silica, nano-zinc oxide and polymer binder. After immersion for 2-5 minutes, it is taken out and excess liquid is removed by squeezing. It is then dried and cured at 60-80℃ for 2-4 hours to form a radiation cooling functional layer on the surface of the flame retardant layer, resulting in a foam with two layers of coating.

[0044] The second coating liquid consists of 1.0–4.0 parts of nano-silica, 0.5–2.0 parts of nano-zinc oxide, 0.5–2.0 parts of polymer binder, and 92.0–98.0 parts of solvent. The nano-silica has a particle size of 20–50 nm and was purchased from Aladdin Reagent Company. The nano-zinc oxide has a particle size of 100–500 nm. The polymer binder is polyvinylidene fluoride-hexafluoropropylene copolymer, and the solvent is acetone.

[0045] During the second coating process, some of the liquid penetrates into the pores and rough gaps of the flame-retardant coating, forming a partially embedded interpenetrating structure. This coating contains nano-silica and nano-zinc oxide, which construct a micro-nano rough structure on the surface of the foam skeleton. The micro-nano structure not only enhances light scattering but also improves infrared radiation heat dissipation efficiency by reducing the solid contact area and the interfacial thermal conduction path.

[0046] S6 Superhydrophobic protective layer coating: Immerse the foam with two coating layers obtained in step S5 into a third coating liquid containing polydimethylsiloxane. After a brief immersion (10-30 seconds), remove the foam and remove excess liquid by squeezing or centrifugation. Cure at 80-100℃ for 1-2 hours to form an extremely thin superhydrophobic protective layer on the outermost layer, thus obtaining the desired multifunctional bio-based polyurethane foam.

[0047] In the third coating liquid, there are 0.5 to 3.0 parts of polydimethylsiloxane prepolymer and its curing agent, with a mass ratio of curing agent of 10:1, and 97.0 to 99.5 parts of ethyl acetate organic solvent. The polydimethylsiloxane prepolymer and its curing agent were purchased from Dow Corning. The third coating liquid forms an extremely thin polydimethylsiloxane protective layer on the outermost layer, giving the foam superhydrophobic properties. Since the polydimethylsiloxane protective layer is discontinuously distributed on the surface of the foam skeleton and its thickness is controlled at the micrometer level, its influence on mid-infrared radiation is limited, thereby ensuring that the heat dissipation efficiency of the lower radiative cooling layer is not affected.

[0048] In steps S4-S6, the weight gain rate of the coating in each step is controlled at 3-8%, and the total weight gain rate is controlled at 10-20%.

[0049] Unless otherwise specified, all raw materials used in this invention are commercially available in the field.

[0050] Example 2 (High Palm Oil-Based Polyol Content) The difference from Example 1 is that the amount of palm oil-based polyol in the preparation of the foam matrix is ​​increased to 70 parts and the amount of polyether polyol is reduced to 10 parts, while the remaining steps are the same as in Example 1.

[0051] Example 3 (High Flame Retardant Content) The difference from Example 1 is that the mass ratio of phosphorylated chitosan to nano zinc oxide in the first coating solution is adjusted to 4:1, while the remaining steps are the same as in Example 1.

[0052] Example 4 (High-radiation cooling effect) The difference from Example 1 is that the mass ratio of nano-silica to nano-zinc oxide in the second coating liquid is adjusted to 3:1, that is, 3.0 parts of nano-silica and 1.0 parts of nano-zinc oxide. The remaining steps are the same as in Example 1.

[0053] Example 5 (Low PDMS Concentration) The difference from Example 1 is that the concentration of polydimethylsiloxane in the third coating liquid is reduced to 0.8 wt%, while the rest of the steps are the same as in Example 1.

[0054] Example 6 (without flame retardant layer) The difference from Example 1 is that step S3, flame retardant layer coating, is skipped, and the polyurethane foam matrix 1 is directly coated with the coating process of steps S4 and S5.

[0055] Example 7 (Radiation-free cooling layer) The difference from Example 1 is that the radiation cooling layer coating in step S4 is skipped, and only the polyurethane foam matrix 1 is coated in steps S3 and S5.

[0056] Example 8 (without superhydrophobic layer) The difference from Example 1 is that step S5, superhydrophobic layer coating, is skipped, and only the polyurethane foam substrate 1 is coated with the coatings of steps S3 and S5.

[0057] Comparative Example 1 (Pure Petroleum-Based Foam) The difference from Example 1 is that the palm oil-based polyol is replaced with an equal amount of polyether polyol in the preparation of the foam matrix, while the rest of the steps are the same as in Example 1.

[0058] Comparative Example 2 (without flame-retardant coating) The difference from Example 1 is that no coating post-treatment is performed, and only polyurethane foam matrix 1 is used.

[0059] Comparative Example 3 (Single-layer flame-retardant coating) The difference from Example 1 is that only the flame retardant layer is coated in step S3, and the radiation cooling layer and superhydrophobic layer are not coated.

[0060] Comparative Example 4 (Single-layer radiation cooling coating) The difference from Example 1 is that only step S4, the radiation cooling layer coating, is performed, and the flame retardant layer and the superhydrophobic layer coating are not performed.

[0061] Comparative Example 5 (Low Palm Oil-Based Polyol Content) The difference from Example 1 is that the amount of palm oil-based polyol in the preparation of the foam matrix is ​​reduced to 20 parts and the amount of polyether polyol is increased to 60 parts, while the remaining steps are the same as in Example 1.

[0062] Comparative Example 6 (without nano zinc oxide flame retardant coating) The difference from Example 1 is that no nano zinc oxide is added to the first coating solution, only phosphorylated chitosan solution is added, and the rest of the steps are the same as in Example 1.

[0063] Comparative Example 7 (without nano-silica radiation cooling layer) The difference from Example 1 is that no nano-silica is added to the second coating liquid, only nano-zinc oxide and binder are added, and the rest of the steps are the same as in Example 1.

[0064] The foams prepared in the above embodiments and comparative examples were subjected to the following performance tests: Physical properties: Apparent density: tested according to GB / T 6343-2009.

[0065] The specific steps are as follows: First, weigh the sample mass (m); measure the sample length, width, and height with calipers, measuring at least 3 different locations for each dimension and taking the median value. Calculate the sample volume (V) using the formula: Length × Width × Height. Calculate the apparent density using the formula: ρ = m / V × 10⁻⁶ 6 (kg / m 3 The results are expressed as the arithmetic mean of the five samples, with three significant figures retained.

[0066] Flame retardant properties: Limiting Oxygen Index (LOI): Tested according to GB / T 2406.2-2009.

[0067] Cut the sample into small pieces of 150mm×10mm×10mm. Mark a line 50mm away from the ignition end of the sample. Install the sample vertically on the sample clamp in the center of the combustion cylinder. Adjust the oxygen and nitrogen flow rates, set the initial oxygen concentration, and adjust the airflow speed to 40±2mm / s. Ignite the top of the sample with an igniter. The ignition time should not exceed 30 seconds. Observe and record the combustion behavior: if the sample combustion time exceeds 180 seconds or the combustion length exceeds 50 mm, reduce the oxygen concentration; if the sample extinguishes within 180 seconds or the combustion length is less than 50 mm, increase the oxygen concentration. Use the "top and bottom method" to conduct the test and obtain the critical oxygen concentration. The LOI is calculated according to the formula: LOI=[O2] / ([O2]+[N2])×100%.

[0068] Vertical burning test (UL-94): Test according to GB / T 8333-2008, and record the extinguishing time, presence of molten droplets, and flammability rating.

[0069] Cut the sample into small pieces of 250 mm × 20 mm × 20 mm and weigh the initial mass of the sample. Fix the sample vertically on the sample fixture, adjust the height of the Bunsen burner flame to 20 ± 1 mm, align the center of the flame with the center of the lower end of the sample, ignite for 10 seconds, and record the following parameters: the burning time after the first ignition (t1), and the second ignition for 10 seconds immediately after the flame goes out, and record the second burning time (t2). Observe whether there are molten droplets igniting the degreased cotton below, and measure the maximum flame height. Weigh the residual mass of the sample after combustion.

[0070] Flammability rating criteria: V-0: Each burning time ≤ 10 seconds, total time ≤ 50 seconds, no molten dripping.

[0071] V-1: Each burning time ≤ 30 seconds, total time ≤ 250 seconds, no molten dripping.

[0072] V-2: Each burning time ≤30 seconds, total time ≤250 seconds, with molten dripping.

[0073] Superhydrophobic properties: Static water contact angle: Cut the sample into small pieces of 20 mm × 20 mm, use a contact angle measuring instrument, take 5 μL of deionized water droplets on the foam surface, measure the contact angle, and take the average value of 5 points for each sample.

[0074] Shape memory performance: The bending test method was used. The sample was cut into small pieces of 50 mm × 10 mm × 5 mm, heated to the deformation temperature (Ttrans, about 60℃), bent into a U shape, and cooled to room temperature under external force to fix it. The initial angle θi was recorded. The fixed sample was heated to Ttrans again and the final recovery angle θf was recorded. The shape fixation rate (Rf) was calculated according to the formula: shape fixation rate (Rf) = θi / 180° × 100%; shape recovery rate (Rr) = (180° - θf) / 180° × 100%. The test was carried out for 3 complete deformation-fixation-recovery cycles. The data of the 3rd cycle was used for calculation. 5 parallel samples were tested for each type of sample, and the average value of the results was taken.

[0075] Radiative cooling performance: Solar reflectance: The sample was cut into 30 mm × 30 mm pieces, and the reflectance of the foam in the 300-2500 nm wavelength band was measured using a UV-Vis-NIR spectrophotometer (equipped with an integrating sphere). The weighted average reflectance of the solar light across the entire wavelength band (Rsolar) was calculated according to the formula. Each sample was tested 3 times and the average value was taken.

[0076] Infrared emissivity: The sample was cut into small pieces of 20 mm × 20 mm, and the emissivity of the foam in the 8-13 μm band was measured using a Fourier transform infrared spectrometer. Each sample was tested 3 times and the average value was taken.

[0077] Outdoor cooling test: The foam sample was placed in the sunlight outdoors, and the surface temperature of the sample and the ambient temperature were recorded using thermocouples and infrared thermal imagers. The cooling effect was calculated according to the formula: ΔT = Te-Ts, where Te is the ambient temperature and Ts is the sample surface temperature. The test was conducted at noon in summer on a sunny day.

[0078] The test results are shown in Table 1:

[0079] Table 1 Based on the data in Table 1 and Figures 2-5 It can be seen that: The LOI of Examples 1-5 is greater than 25%, achieving the UL-94 V-0 rating.

[0080] Example 3 achieved an LOI of 27.3%, demonstrating the best flame retardant effect.

[0081] The LOI of Examples 6 and Comparative Example 2 was less than 20% and had no UL-94 rating, demonstrating the necessity of the flame-retardant coating.

[0082] The LOI of Comparative Example 6 was 22.4%, only reaching the V-1 level, indicating that the synergistic effect of nano zinc oxide and phosphorylated chitosan is crucial to the flame retardant effect.

[0083] The water contact angles of Examples 1-4 are all greater than 150°, achieving superhydrophobicity.

[0084] In Example 5, the contact angle decreased to 148.6°, and the hydrophobicity decreased slightly, but the lower polydimethylsiloxane concentration helped maintain air permeability.

[0085] The contact angles of Examples 8 and Comparative Examples 2-4 were all less than 120°, demonstrating that the outermost polydimethylsiloxane coating plays a crucial role in achieving superhydrophobicity.

[0086] R in Examples 1-8 f All greater than 95%, R r All values ​​are greater than 94%, demonstrating excellent shape memory performance.

[0087] R in Comparative Examples 1 and 5 f and R r The significant decrease demonstrates that the long-chain structure of palm oil-based polyols plays a crucial role in achieving shape memory function.

[0088] Example 4 achieved the best results with a solar reflectance of 94.8%, an infrared emissivity of 96.2%, and an outdoor temperature reduction of 12.1°C.

[0089] The reflectivity and emissivity of Example 7 were significantly reduced, with a cooling effect of only 2.5°C.

[0090] The solar reflectance of Comparative Example 7 decreased to 78.5%, with a cooling effect of 5.8℃, proving that silica plays an important role in improving solar reflectance.

[0091] Example 1 simultaneously possesses excellent flame retardancy, superhydrophobicity, shape memory, and radiative cooling properties.

[0092] Examples 6, 7, and 8 show that the absence of a certain functional layer resulted in a significant decrease in the corresponding function, demonstrating the synergistic effect and irreplaceability of the three-layer coating.

[0093] The results show that, compared with single-layer or double-layer coatings, the three-layer structure exhibits nonlinear improvements in flame retardancy, hydrophobicity, and radiative cooling performance, indicating that there is a synergistic effect between the layers rather than a simple superposition.

[0094] This invention successfully prepared a bio-based polyurethane foam integrating shape memory, flame retardancy, superhydrophobicity, and radiative cooling functions. The foam's excellent shape memory properties are achieved through a palm oil-based polyol formulation. The synergistic effect of three functional coatings—a flame-retardant layer, a radiative cooling layer, and a superhydrophobic layer—enables the foam to achieve a LOI > 25%, a UL-94V-0 rating, and a contact angle > 150°. Under solar irradiation, the sample surface temperature is 8-12°C lower than the ambient temperature, demonstrating excellent flame retardancy, superhydrophobicity, shape memory, and temperature regulation. The three-layer structure, through the construction of a multi-scale rough structure and interface control, achieves synergistic optimization of optical scattering, surface wettability, and heat transfer, ultimately yielding a high-performance, environmentally friendly smart foam material with broad application prospects in high-end mattresses, cushions, and other smart home products.

[0095] When the bio-based polyurethane foam of the present invention is applied in mattresses or pillows, the mattresses or pillows utilize the shape memory function of the foam to achieve adaptive support, utilize the flame retardant function to improve the safety of use, utilize the superhydrophobic function to achieve surface self-cleaning and anti-fouling, and utilize the radiative cooling function to achieve passive cooling and temperature regulation.

[0096] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A multifunctional bio-based polyurethane foam, characterized in that: Includes a polyurethane foam matrix and a composite coating loaded on the surface of the polyurethane foam matrix; The polyurethane foam matrix is ​​prepared by a foaming reaction of component A and component B. Component A includes palm oil-based polyol, polyether polyol, chain extender, catalyst, foam stabilizer and foaming agent, and component B is polyisocyanate. The composite coating is composed of a flame-retardant coating, a radiation-cooling coating, and a superhydrophobic protective layer distributed sequentially from the inside out. The flame-retardant coating is a composite layer of phosphorylated chitosan and nano zinc oxide, and the flame-retardant coating forms a phosphorus-nitrogen synergistic carbonization structure when heated. The radiation-cooling coating is a composite layer of nano silica and nano zinc oxide, and the radiation-cooling coating forms a micro-nano composite scattering structure. The superhydrophobic protective layer is a polydimethylsiloxane coating, which covers the surface of the micro-nano composite scattering structure to form a low surface energy layer. The flame-retardant coating contains phosphorylated chitosan to nano-zinc oxide in a mass ratio of 8:1 to 4:1, with the nano-zinc oxide having a particle size ≤100 nm. The flame-retardant coating forms a primary rough structure on the surface of the polyurethane foam matrix, with a surface roughness of 1-10 μm. The radiation-cooling coating contains nano-silica to nano-zinc oxide in a mass ratio of 3:1 to 2:1, with nano-silica having a particle size of 20-50 nm and nano-zinc oxide having a particle size of 100-500 nm. The radiation-cooling coating is partially embedded in the flame-retardant coating to form an interfacial interpenetrating structure. The superhydrophobic protective layer contains polydimethylsiloxane at a mass concentration of 0.5-3.0 wt%.

2. The multifunctional bio-based polyurethane foam according to claim 1, characterized in that: The apparent density of the polyurethane foam matrix is ​​85-115 kg / m³. 3 The shape fixation rate is ≥95%, the shape recovery rate is ≥94%, the total weight gain of the polyurethane foam matrix after three-layer coating treatment is 10-20%, the limiting oxygen index is ≥25%, it can pass the UL-94 V-0 vertical burning test, the water contact angle is ≥150°, the solar reflectivity is ≥92%, the infrared emissivity is ≥94%, and the outdoor cooling effect is ≥10℃.

3. The multifunctional bio-based polyurethane foam according to claim 1, characterized in that: The palm oil-based polyol has a hydroxyl value of 300-400 mg KOH / g and a viscosity of 80-120 mPa·s at 50°C. The catalyst is a composite catalyst of stannous octoate and triethylenediamine. The foaming agent is deionized water. The foam stabilizer is a polyether-modified silicone surfactant. The polyisocyanate is toluene diisocyanate, and the isocyanate index R value is 0.90-1.

20.

4. The multifunctional bio-based polyurethane foam according to claim 1, characterized in that: Component A comprises 30-70 parts of palm oil-based polyol, 0-60 parts of polyether polyol, 0-2.0 parts of chain extender, 0.3-0.8 parts of catalyst, 1.0-2.0 parts of foam stabilizer and 2.0-5.0 parts of blowing agent, and Component B comprises 35.0-55.0 parts of polyisocyanate.

5. A method for preparing the multifunctional bio-based polyurethane foam according to claim 1, characterized in that: Includes the following steps: Preparation of S1 palm oil-based polyol: Palm oil and triethanolamine were mixed in a molar ratio of 1:3 and reacted at 170°C under zinc acetate catalysis for 2 hours to obtain palm oil-based polyol. Preparation of S2 foam matrix: Palm oil-based polyol, polyether polyol, chain extender, catalyst, foam stabilizer and blowing agent are mixed evenly to obtain component A. After adding polyisocyanate of component B and stirring at high speed, the mixture is injected into a mold for foaming and curing to obtain polyurethane foam matrix. Preparation of S3 phosphorylated chitosan: Chitosan powder was prepared into a 1.0 wt% aqueous suspension, stirred at 50°C, and phosphorous acid was gradually added during stirring until the solution became clear and transparent. After cooling, a phosphorylated chitosan solution was obtained. S4 Flame retardant coating: Add nano zinc oxide to the phosphorylated chitosan solution in step S3 and stir to mix to obtain the first coating liquid. Immerse the foam matrix obtained in step S2 into the first coating liquid, extrude and dry to cure to obtain foam with a coating layer. S5 Radiation Cooling Coating: The foam with one layer of coating obtained in step S4 is immersed in a second coating liquid containing nano-silica, nano-zinc oxide and polymer binder. After immersion, it is squeezed, dried and cured to obtain foam with two layers of coating. S6 Superhydrophobic protective layer coating: Immerse the foam with two coating layers obtained in step S5 into a third coating liquid containing polydimethylsiloxane, briefly wet it, and then squeeze, dry and cure it to obtain the desired multifunctional bio-based polyurethane foam.

6. The method for preparing multifunctional bio-based polyurethane foam according to claim 5, characterized in that: In steps S4-S6, the weight gain rate of the coating in each step is controlled at 3-8%, and the total weight gain rate is controlled at 10-20%. In step S4, the drying and curing conditions are drying at 80℃ for 2 hours; in step S5, the drying and curing conditions are drying at 60-80℃ for 2-3 hours; and in step S6, the drying and curing conditions are drying at 80-100℃ for 1-2 hours.

7. The method for preparing multifunctional bio-based polyurethane foam according to claim 5, characterized in that: In step S4, the solid content of the phosphorylated chitosan solution in the first coating liquid is 0.5-1.0 wt%, and the amount of nano zinc oxide added makes the mass ratio of phosphorylated chitosan to nano zinc oxide 8:1 to 4:

1. In step S5, the second coating liquid contains 1.0-4.0 parts by mass of nano-silica, 0.5-2.0 parts by mass of nano-zinc oxide, 0.5-2.0 parts by mass of polymer binder, and acetone as the solvent. In step S6, the mass concentration of polydimethylsiloxane prepolymer and its curing agent in the third coating liquid is 0.5-3.0 wt%, and the solvent is ethyl acetate.

8. The method for preparing multifunctional bio-based polyurethane foam according to claim 5, characterized in that: In step S2, the catalyst is a composite catalyst of stannous octoate and triethylenediamine, the foaming agent is deionized water, the foam stabilizer is a polyether-modified organosilicon surfactant, the polyisocyanate is toluene diisocyanate, and the isocyanate index R value is 0.90-1.20.

Images