Preparation method and application of environment-friendly bio-based shape memory polyurethane foam
The preparation method of polyurethane foam reinforced with bio-based polyols and nanocellulose solves the mechanical properties and environmental problems of traditional polyurethane foam, achieving high shape memory performance, enhanced strength and breathability, making it suitable for high-quality mattresses and pillows.
Patent Information
- Application Number
- CN202511947331.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-23
- Publication Date
- 2026-02-24
AI Technical Summary
Traditional polyurethane foam has poor mechanical properties and durability, poor air permeability, may have odors during production, and its petroleum-based raw materials are not environmentally friendly, failing to meet the requirements of sustainable development.
A method for preparing polyurethane foam reinforced with bio-based polyols and nanocellulose was adopted. Castor oil and polyethylene glycol were melted and mixed, and then reacted with a catalyst, a foaming agent and a foam stabilizer to form a nanocellulose-polyol dispersion. Isocyanate was added to foam and cure the foam, and post-treatment was performed to form a multilayer structure.
It improves the shape memory and mechanical properties of foam, with a shape fixation rate and recovery rate of over 95%, and increases compressive strength by 18 times. It also has excellent thermal stability and breathability, meeting green and environmentally friendly requirements.
Smart Images
Figure CN121554696A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of polymer materials technology, specifically to a method for preparing and applying a green and environmentally friendly bio-based shape memory polyurethane foam. Background Technology
[0002] Polyurethane (PU) foam is one of the most common polymer foams, widely used in automobiles, furniture, and packaging due to its high adsorption rate, low density, and ease of processing. Polyols are a key raw material in PU production, primarily derived from petroleum. However, due to the dwindling fossil oil resources, environmental issues, and economic instability, the demand for sustainable alternatives to petroleum-based polyols is growing.
[0003] Polyurethane foam has poor mechanical properties and durability. It typically lacks sufficient support and is prone to structural fatigue and permanent collapse after prolonged use, unable to rebound. Its open-cell structure also results in poor air permeability, and residual odors may remain from the production process, affecting user comfort. Viscoelastic polyurethane foam (PUVF), often called shape memory foam, offers effective support despite its slower recovery after compression, and boasts high fatigue strength, allowing for repeated use. PUVF is an open-cell type of flexible polyurethane foam with excellent air permeability.
[0004] In the field of high-quality mattresses and pillows, although polyurethane foam has broad application prospects and market demand, some key technical issues still need to be addressed, and its performance needs to be improved and pollution reduced through process improvements. Summary of the Invention
[0005] The purpose of this invention is to provide a method for preparing and applying a green and environmentally friendly bio-based shape memory polyurethane foam, so as to improve the overall performance of polyurethane foam and reduce pollution.
[0006] To solve the above-mentioned technical problems, the technical solution of the present invention includes the following steps: S1. Melt castor oil, polyethylene glycol, and nanocellulose in an oil bath, and mix them thoroughly with catalyst, foaming agent, and foam stabilizer, then mechanically stir to form a uniform premix. S2. Add isocyanate to the premixed liquid, stir at high speed to initiate the reaction, and then inject it into the mold for free foaming to make it expand. S3. Place the foam prepared in the mold into an oven and let it sit for a week for post-curing to obtain a bio-based shape memory polyurethane foam with good shape memory effect.
[0007] As a preferred embodiment of the present invention, the nanocellulose is cellulose nanofiber or cellulose nanocrystal, and its addition amount is 0.1% to 3% of the total mass of castor oil and polyethylene glycol, and the solid content of the cellulose nanofiber is 1.5 wt%.
[0008] As a preferred embodiment of the present invention, in the premix preparation step, a bio-based polyol system containing castor oil and polyethylene glycol is first prepared, and then the nanocellulose is uniformly dispersed in a portion of the bio-based polyol by ultrasonic dispersion, pre-treatment to form a nanocellulose-polyol dispersion, and then mixed with other components. The ultrasonic dispersion conditions are ice-water bath ultrasonication for 2-3 hours.
[0009] In a preferred embodiment of the present invention, the average molecular weight of the polyethylene glycol is 4000 g / mol; the mass ratio of castor oil to polyethylene glycol is 20:80 to 30:70.
[0010] In a preferred embodiment of the present invention, the isocyanate is diphenylmethane diisocyanate or a polymer thereof, and the NCO / OH index of the reaction system is controlled to be 1.1~1.2.
[0011] In a preferred embodiment of the present invention, the foaming agent is water; the catalyst is a composite catalyst formed by an amine catalyst and a tin catalyst; the foam stabilizer is a silicone-based surfactant L580K; and the curing conditions are: first, curing at 70-90°C for 2-4 hours, followed by continued curing at room temperature for 3-7 days.
[0012] In a preferred embodiment of the present invention, after the foaming and curing steps, the following post-processing steps are further included: The cured polyurethane foam is sliced, and multiple layers of foam sheets are stacked and hot-pressed at a temperature of 100-120℃ and a pressure of 1-2MPa for 3-5 minutes to form a composite foam material with a multi-layer structure.
[0013] A nanocellulose-reinforced bio-based shape memory polyurethane foam, prepared using a green and environmentally friendly bio-based shape memory polyurethane foam preparation method, has an apparent density of 110-220 kg / m³. 3 Its shape fixation rate in compression mode is ≥95%, and its shape recovery rate is ≥94%; its reversible shape memory strain is ≥3%; its glass transition temperature is ≥40℃; and the compressive strength of the foam is up to 18 times higher than that of similar foams without added nanocellulose.
[0014] As a preferred embodiment of the present invention, the prepared bio-based shape memory polyurethane foam is used to prepare infant head shaping pillows, pillows that adjust size using shape memory function, and pillows that dynamically adjust softness and hardness using shape memory function.
[0015] The advantages of this invention are: the bio-based shape memory polyurethane foam prepared by this invention overcomes the shortcomings of traditional petroleum-based shape memory foam, and has a significant improvement in comprehensive performance. The foam has excellent shape memory properties and a shape fixation rate (R... f The shape recovery rate is as high as 95% or more, and the shape recovery rate (R) is also high. r With a strength of over 95%, and capable of achieving up to 12% reversible shape memory strain, foam is endowed with intelligent driving and adaptive deformation capabilities. The castor oil, polyethylene glycol polyols, and nanocellulose used are all bio-based or renewable raw materials, which are green and environmentally friendly and meet the requirements of sustainable development. They can effectively reduce dependence on petroleum resources. The introduction of nanocellulose not only significantly improves the mechanical properties of the foam as a reinforcing phase, increasing its compressive strength by up to 18 times, but also acts as a physical crosslinking point, improving the crosslinking density and thermal stability of the foam. By adjusting the ratio of polyols, the phase transition temperature of the foam can be easily adjusted, thereby customizing its shape memory trigger temperature and broadening its application temperature range. The bio-based foam prepared by this invention, which combines lightweight, high strength, reversible shape memory, and excellent thermal stability, has great application value in the high-quality mattress and pillow market. Attached Figure Description
[0016] Figure 1 This is a schematic diagram illustrating the preparation of the foam composite material used in pillows according to the present invention; Figure 2 This is a diagram illustrating the shape memory properties of the polyurethane foam composite material of the present invention. Detailed Implementation
[0017] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. The following embodiments will enable those skilled in the art to more fully understand this invention, but do not limit the invention to the scope of the described embodiments.
[0018] This specific embodiment adopts the following technical solution: a method for preparing green and environmentally friendly bio-based shape memory polyurethane foam, comprising the following steps: S1. Melt castor oil, polyethylene glycol, and nanocellulose in an oil bath, and mix them thoroughly with catalyst, foaming agent, and foam stabilizer, then mechanically stir to form a uniform premix. Nanocellulose is cellulose nanofibers or cellulose nanocrystals, and its addition amount is 0.1% to 3% of the total mass of castor oil and polyethylene glycol, and the solid content of cellulose nanofibers is 1.5 wt%.
[0019] The average molecular weight of polyethylene glycol is 4000 g / mol; the mass ratio of castor oil to polyethylene glycol is 20:80~30:70.
[0020] In the premix preparation step, a bio-based polyol system containing castor oil and polyethylene glycol is first prepared. Then, nanocellulose is uniformly dispersed in a portion of the bio-based polyol by ultrasonic dispersion. The pretreatment forms a nanocellulose-polyol dispersion, which is then mixed with other components. The ultrasonic dispersion conditions are ice-water bath ultrasonication for 2-3 hours.
[0021] The foaming agent is water; the catalyst is a composite catalyst formed by amine catalyst and tin catalyst; the foam stabilizer is silicone-based surfactant L580K; the curing conditions are: first cure at 70-90℃ for 2-4 hours, then continue to cure at room temperature for 3-7 days.
[0022] S2. Add isocyanate to the premixed liquid, stir at high speed to initiate the reaction, and then inject it into the mold for free foaming to allow it to expand; the isocyanate is diphenylmethane diisocyanate or its polymer, and the NCO / OH index of the reaction system is controlled to be 1.1~1.2.
[0023] S3. Place the foam prepared in the mold into an oven and let it sit for a week for post-curing to obtain a bio-based shape memory polyurethane foam with good shape memory effect.
[0024] After the foaming and curing steps, the following post-processing steps are also included: the cured polyurethane foam is sliced, the multi-layer foam sheets are stacked, and hot-pressed at a temperature of 100-120℃ and a pressure of 1~2 MPa for 3~5 minutes to form a composite foam material with a multi-layer structure.
[0025] A nanocellulose-reinforced bio-based shape memory polyurethane foam, prepared using a green and environmentally friendly bio-based shape memory polyurethane foam preparation method, has an apparent density of 110-220 kg / m³. 3 Its shape fixation rate under compression mode is ≥95%, and its shape recovery rate is ≥94%; its reversible shape memory strain is ≥3%; its glass transition temperature is ≥40℃; and its compressive strength is up to 18 times higher than that of similar foams without added nanocellulose.
[0026] The raw materials used in this invention were sourced as follows: Polyethylene glycol (PEG-4000, Mn=4000 g / mol) was purchased from Sigma-Aldrich. Castor oil (CO, industrial grade) and diphenylmethane diisocyanate (MDI, brand name Lupranate M20S, NCO=30-32%) were purchased from China National Pharmaceutical Group Chemical Reagent Co., Ltd. Aqueous dispersion of cellulose nanofibers (CNF, solid content 1.5wt%) was provided by a biomaterials company in Jiangsu Province. Amine catalyst (Dabco® BLV), tin catalyst (Dabco® T-9), and silicone-based surfactant (L580K) were provided by Momentive Polymer Materials Co., Ltd. All raw materials, except CNF, were vacuum-dried at 40°C before use.
[0027] The instruments used in this embodiment of the invention are as follows: a field emission scanning electron microscope (FE-SEM, Sigma 300, Carl Zeiss Co., Germany) for observing foam morphology; a differential scanning calorimeter (DSC, Q200, TA Instruments, USA) for analyzing thermal transformation behavior; a thermogravimetric analyzer (TGA, Pyris 1, PerkinElmer, USA) for evaluating thermal stability; a universal testing machine (UTM2203, Sanshi Zongheng Technology Co., Ltd., China) for testing compression performance; and a dynamic mechanical analyzer (DMA, Q800, TA Instruments, USA) for determining shape memory performance.
[0028] Example 1: A method for preparing green and environmentally friendly bio-based shape memory polyurethane foam includes the following steps: (1) Place 10.0 g castor oil (CO) and 40.0 g polyethylene glycol PEG-4000 (Mn = 4000 g / mol) into a beaker and melt-mix them in an oil bath at 70°C to prepare a bio-based polyol mixture; (2) Mix 50 g of polyol mixture from step (1) with 50.0 g of cellulose nanofiber (CNF) aqueous dispersion (equivalent to 0.75 g dry weight CNF, accounting for 1.5% of the total mass of polyol), and sonicate in an ice bath for 2.5 h to obtain a uniform CNF / polyol dispersion. (3) The CNF / polyol dispersion prepared in step (2) was mixed with 0.6 g of amine catalyst triethylenediamine Dabco BLV, 0.75 g of tin catalyst stannous octoate Dabco T-9, 2.0 g of silicone surfactant L580K and 1.6 g of deionized water (as a chemical foaming agent), and mechanically stirred at 1500 rpm for 5 min at room temperature to form a uniform premix. The catalyst system can effectively ensure the reaction proceeds and control the opening of the foam. The silicone surfactant L580K can effectively improve surface activity and reduce tension.
[0029] (4) Add 48.5 g of diphenylmethane diisocyanate (MDI, preheated to 70°C) quickly to the premix in step (3), stir at 2500 rpm for 20 s, and after observing that the mixture begins to foam, quickly pour it into a mold with dimensions of 200 mm × 200 mm × 100 mm for free foaming; (5) Place the mold filled with foam in an 80°C oven and cure for 3 h. Then demold and let the foam mature at room temperature for 5 days to obtain nanocellulose-reinforced bio-based shape memory polyurethane foam, denoted as CO / PEG-CNF1.5.
[0030] Example 2: The difference between Example 2 and Example 1 is that the amount of CNF aqueous dispersion added in step (2) is replaced with 100.0g (equivalent to 1.5g of dry CNF, accounting for 3% of the total mass of polyol). The remaining steps are the same as in Example 1, and bio-based shape memory polyurethane foam is prepared, which is denoted as CO / PEG-CNF3.0.
[0031] Example 3: The difference between Example 3 and Example 1 is that the polyol ratio in step (1) is replaced with 15.0 g castor oil (CO) and 35.0 g polyethylene glycol PEG-4000, the CNF addition in step (2) is the same as in Example 1, and the remaining steps are the same as in Example 1. Bio-based shape memory polyurethane foam is obtained and is denoted as CO / PEG-CNF1.5-HCO.
[0032] Example 4: The difference between Example 4 and Example 1 is that a hot-pressing composite process was added after the foam preparation was completed. One support layer foam (obtained in Example 2), one comfort layer foam (obtained in Example 1), and another support layer foam (obtained in Example 2) were stacked in a "sandwich" structure (total theoretical thickness 35mm). They were then hot-pressed at 120°C and 2MPa for 5 minutes, and after restoring at room temperature for 24 hours, a composite foam material, denoted as COMPOSITE, was obtained. A schematic diagram of the preparation of the foam composite material for pillows is shown below. Figure 1 As shown.
[0033] The properties of the bio-based shape memory polyurethane foams prepared in Examples 1-4 were tested, and the results are as follows: Shape memory performance: The shape memory performance of the foam was evaluated using a dynamic mechanical analyzer (DMA) via thermomechanical cycling tests. Foam samples were compressed to 50% strain at 55°C (Thigh), cooled to 0°C (Tlow) while maintaining the strain, and then unloaded. The shape retention rate (R0) was measured. f The sample was then heated to Thigh under no-load conditions, and its shape recovery rate (R0) was recorded. r ).
[0034] R of the foams prepared in Examples 1-4 f All are above 95%, R r All were above 94%. Among them, the foam of Example 1 (CO / PEG-CNF1.5) showed R in the third cycle. f It is 96.5%, and Rr is 95.8%. For example... Figure 2 The figure shown is a diagram illustrating the shape memory properties of foam composite materials.
[0035] Compression performance: The foam samples were compressed using a universal testing machine at a compression rate of 2 mm / min.
[0036] Example 1 (CO / PEG-CNF1.5) foam has a stress value of 0.15 MPa at 50% compressive strain; Example 2 (CO / PEG-CNF3.0) foam has a stress value of 0.22 MPa at the same strain, showing the significant reinforcing effect of nanocellulose.
[0037] Thermal stability: The thermal decomposition behavior of the foam was tested under nitrogen atmosphere using a thermogravimetric analyzer (TGA).
[0038] The initial decomposition temperature (Td, 5%, the temperature at which 5% weight loss occurs) of the foam in Example 1 was 278°C, while the Td, 5% of the foam in Example 2 increased to 285°C, indicating that adding more CNF helps to improve the thermal stability of the foam.
[0039] Comparative Example 1: The difference between Comparative Example 1 and Example 1 is that nanocellulose was not added; all other steps were the same as in Example 1, and the resulting foam was designated CO / PEG-Neat. Test results showed that its shape retention rate was 92.3%, its shape recovery rate was 90.5%, the stress value at 50% compressive strain was only 0.08 MPa, and the initial decomposition temperature was 270℃. Compared with Example 1, all properties decreased significantly, demonstrating the performance-enhancing effect of nanocellulose.
[0040] This invention develops a novel nanocellulose-reinforced bio-based shape memory polyurethane foam, providing an innovative solution for the pillow industry. The material uses castor oil and polyethylene glycol polyol as its bio-based matrix, and incorporates nanocellulose to construct a three-dimensional reinforcing network, exhibiting both environmentally friendly properties and excellent mechanical-intelligent response balance. Based on its unique temperature-responsive shape memory mechanism, this foam can achieve the following three major application characteristics in pillows: 1. Adjust pillow size using shape memory function The foam can shrink and recover in a controlled manner according to changes in ambient temperature. Users can easily adjust the pillow height or size by heating the area locally to adapt to different sleeping habits and bed types, making the pillow multi-functional.
[0041] 2. Utilize shape memory function to dynamically adjust hardness. The built-in polyethylene glycol phase change unit in the material allows it to sense the temperature of the head and neck in real time. When it comes into contact with the human body, it softens appropriately and conforms precisely to the curves. After it is removed, it returns to its supporting state as the temperature drops, thus automatically providing just the right amount of support in different sleeping positions and achieving a personalized "zero pressure" experience.
[0042] 3. Suitable for infants and young children's head shaping pillow With its gentle temperature response and excellent breathable structure, this foam can intelligently conform to the shape of an infant's head, evenly distributing pressure while avoiding localized overheating. It helps to naturally guide head shape development during sleep, providing safe and breathable shaping support for the baby.
[0043] The reinforcing effect of nanocellulose in the foam ensures that it maintains structural stability during long-term use. The introduction of nanocellulose not only significantly improves the mechanical properties of the foam as a reinforcing phase, increasing its compressive strength by up to 18 times, but also serves as a physical crosslinking point, improving the crosslinking density and thermal stability of the foam. The open-cell design further enhances air permeability, while the bio-based raw materials and water foaming process ensure the health and environmental protection attributes of the product.
[0044] The bio-based shape memory polyurethane foam prepared by this invention overcomes the shortcomings of traditional petroleum-based shape memory foams, and has a significant improvement in comprehensive performance. The foam exhibits excellent shape memory properties and a high shape fixation rate (Ri). f The shape recovery rate is as high as 95% or more, and the shape recovery rate (R) is also high. r With a content of over 95% and the ability to achieve up to 12% reversible shape memory strain, this material endows the foam with intelligent driving and adaptive deformation capabilities. This material not only redefines the functional dimensions of smart pillows but also provides a new generation of material options for the bedding industry to move towards intelligence and health.
[0045] The foregoing has shown and described the basic principles and main features of the present invention, as well as its advantages. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.
Claims
1. A method for preparing green and environmentally friendly bio-based shape memory polyurethane foam, characterized in that: Includes the following steps: S1. Melt castor oil, polyethylene glycol, and nanocellulose in an oil bath, and mix them thoroughly with catalyst, foaming agent, and foam stabilizer, then mechanically stir to form a uniform premix. S2. Add isocyanate to the premixed liquid, stir at high speed to initiate the reaction, and then inject it into the mold for free foaming to make it expand. S3. Place the foam prepared in the mold into an oven and let it sit for a week for post-curing to obtain a bio-based shape memory polyurethane foam with good shape memory effect.
2. The method for preparing a green and environmentally friendly bio-based shape memory polyurethane foam according to claim 1, characterized in that: The nanocellulose is cellulose nanofiber or cellulose nanocrystal, and its addition amount is 0.1% to 3% of the total mass of castor oil and polyethylene glycol. The solid content of the cellulose nanofiber is 1.5 wt%.
3. The method for preparing a green and environmentally friendly bio-based shape memory polyurethane foam according to claim 1, characterized in that: In the premix preparation step, a bio-based polyol system containing castor oil and polyethylene glycol is first prepared. Then, the nanocellulose is uniformly dispersed in a portion of the bio-based polyol by ultrasonic dispersion. The pretreatment forms a nanocellulose-polyol dispersion, which is then mixed with other components. The ultrasonic dispersion conditions are ice-water bath ultrasonication for 2-3 hours.
4. The method for preparing a green and environmentally friendly bio-based shape memory polyurethane foam according to claim 1, characterized in that: The average molecular weight of the polyethylene glycol is 4000 g / mol; the mass ratio of castor oil to polyethylene glycol is 20:80~30:
70.
5. The method for preparing a green and environmentally friendly bio-based shape memory polyurethane foam according to claim 1, characterized in that: The isocyanate is diphenylmethane diisocyanate or its polymer, and the NCO / OH index of the reaction system is controlled to be 1.1~1.
2.
6. The method for preparing a green and environmentally friendly bio-based shape memory polyurethane foam according to claim 1, characterized in that: The foaming agent is water; the catalyst is a composite catalyst formed by an amine catalyst and a tin catalyst; the foam stabilizer is a silicone-based surfactant L580K; the curing conditions are: first, cure at 70-90℃ for 2-4 hours, and then continue to cure at room temperature for 3-7 days.
7. A method for preparing a green and environmentally friendly bio-based shape memory polyurethane foam according to any one of claims 1-6, characterized in that: Following the foaming and curing steps, the following post-processing steps are also included: The cured polyurethane foam is sliced, and the multi-layer foam sheets are stacked and hot-pressed at a temperature of 100-120℃ and a pressure of 1-2 MPa for 3-5 minutes to form a composite foam material with a multi-layer structure.
8. A green and environmentally friendly bio-based shape memory polyurethane foam, characterized in that: Nanocellulose-reinforced bio-based shape memory polyurethane foam prepared by the method of preparing green and environmentally friendly bio-based shape memory polyurethane foam according to any one of claims 1-6.
9. The green and environmentally friendly bio-based shape memory polyurethane foam according to claim 8, characterized in that: The apparent density of the polyurethane foam is 110-220 kg / m³. 3 Its shape fixation rate in compression mode is ≥95%, and its shape recovery rate is ≥94%; its reversible shape memory strain is ≥3%; and its glass transition temperature is ≥40℃.
10. An application of a green and environmentally friendly bio-based shape memory polyurethane foam, characterized in that: The application includes using the bio-based shape memory polyurethane foam obtained in any one of claims 1-6 and claim 9 to prepare infant head-shaping pillows, pillows that adjust size using shape memory function, and pillows that dynamically adjust softness and hardness using shape memory function.