Castor oil-based thermoplastic polyurethane and preparation method thereof
The one-pot reaction process for preparing castor oil-based thermoplastic polyurethane solves the problems of complex preparation and low castor oil usage in existing technologies, enabling the efficient application of bio-based materials. It possesses excellent mechanical strength and water resistance, promoting its application in multiple industrial fields.
Patent Information
- Application Number
- CN202410581440.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-05-10
- Publication Date
- 2026-02-06
AI Technical Summary
There is a lack of simple and feasible methods for preparing castor oil-based thermoplastic polyurethanes in the existing technology. Furthermore, traditional methods suffer from problems such as complex processes, low castor oil usage, and complex product composition, making it difficult to achieve the widespread application of bio-based materials.
A one-pot reaction process was adopted to prepare a linear polymeric castor oil-based thermoplastic polyurethane by controlling the ratio and addition order of castor oil and monoisocyanate, combined with catalysts and diluents. This improved the application rate of biomass-based materials and gave them good mechanical strength and water resistance.
A simple and feasible preparation of castor oil-based thermoplastic polyurethane has been achieved, which increases the proportion of biomass-based materials used. It has excellent mechanical strength, plasticity and water resistance, meets environmental protection requirements, and is suitable for multiple industrial applications.
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Figure CN121471483A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of polyurethane preparation technology, specifically relating to a castor oil-based thermoplastic polyurethane and its preparation method. Background Technology
[0002] Thermoplastic polyurethane (TPU), also known as polyurethane rubber, is a special synthetic linear polymer that can be thermoplasticized and dissolved in certain solvents. Generally, thermosetting polyurethane cannot be reprocessed after heating and is difficult to recycle. In contrast, thermoplastic polyurethane can be reprocessed by heating and can be recycled, exhibiting better sustainability. Given its processing methods and recyclability, thermoplastic polyurethane has broad application prospects in fields such as defense technology (aircraft fuel tanks, cable sheathing materials, sound insulation materials, etc.), medicine and healthcare (surgical gowns and caps, etc.), clothing and footwear materials (hiking boots, raincoats, etc.), and the automotive industry (dust covers, airbag covers, etc.).
[0003] In traditional polyurethane synthesis, petrochemical products are typically used as raw materials. While these materials offer excellent performance, their production and use impose a significant environmental burden. With increasing global awareness of sustainable development and environmental protection, bio-based materials have gained widespread attention due to their renewable and biodegradable properties. Castor oil, as an abundant vegetable oil resource, is an ideal raw material for polyurethane synthesis due to its high content of hydroxyl and ester functional groups. Because of its green and environmentally friendly characteristics and high biocompatibility, thermoplastic polyurethane prepared from castor oil is a bio-based polymer material with significant industrial application value. Therefore, the research and development of castor oil-based thermoplastic polyurethane aims to replace traditional petroleum-based raw materials with renewable resources, reducing environmental impact while maintaining or improving the material's functionality.
[0004] In existing technologies, the synthesis of castor oil-based polyurethane typically involves the reaction of castor oil with polyols and isocyanates. Most of the synthesized castor oil polyurethane products are thermosetting polyurethanes, and their synthesis methods often suffer from complex preparation processes, low castor oil usage and low biomaterial substitution rates (castor oil content is typically 20%–30%), and complex polyurethane product compositions. In contrast, the thermoplastic properties of castor oil-based thermoplastic polyurethanes enable them to be repeatedly processed and recycled, which is significant for reducing material waste and lowering production costs. Furthermore, due to their unique properties, castor oil-based thermoplastic polyurethanes are widely used in various industries. However, a simple and feasible process for the successful preparation of castor oil-based thermoplastic polyurethanes is currently lacking.
[0005] Therefore, developing a simple and feasible method for preparing castor oil-based thermoplastic polyurethane is of great significance for promoting the sustainable development of bio-based polyurethane in materials science and industrial applications. Summary of the Invention
[0006] To address the aforementioned problems, the present invention aims to provide a method for preparing castor oil-based thermoplastic polyurethane, which uses castor oil as the main raw material. The preparation process is simple and suitable for industrial production. Furthermore, the prepared castor oil-based thermoplastic polyurethane exhibits excellent mechanical strength and plasticity, as well as water resistance and biodegradability, thus meeting the sustainable development needs of thermoplastic polyurethane.
[0007] The present invention also aims to provide a castor oil-based thermoplastic polyurethane prepared by the above preparation method, which has excellent mechanical strength and plasticity, as well as good water resistance and biodegradability, and is suitable for use as a polyurethane elastomer.
[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows:
[0009] A method for preparing castor oil-based thermoplastic polyurethane includes the following steps:
[0010] Under a protective atmosphere, monoisocyanate was first added to castor oil, then a catalyst was added, and the mixture was stirred at 60–80°C for 80–300 min. After the stirring reaction was completed, diisocyanate was added to the reaction system, and the mixture was reacted again at 60–80°C. During the reaction, a diluent was added to adjust the viscosity. After the reaction was completed, the diluent was removed to obtain the castor oil-based thermoplastic polyurethane.
[0011] The monoisocyanate is one or more of cyclohexyl isocyanate, isopropyl isocyanate, m-toluene isocyanate, and furan methyl isocyanate; the diisocyanate is one or more of isoflurane diisocyanate, hexamethylene diisocyanate, toluene diisocyanate, and diphenylmethane diisocyanate; and the amounts of the monoisocyanate, castor oil, and diisocyanate, by mass, are 0.6-1.0 parts, 6.5-7.5 parts, and 0.8-2 parts, respectively.
[0012] In this invention, the monoisocyanate is preferably a low-activity, large-molecule isocyanate, which is beneficial for controlling the degree of reaction and thus regulating the spatial structure of the product molecules, thereby improving the performance of thermoplastic polyurethane. As a preferred embodiment, the monoisocyanate is cyclohexyl isocyanate or isopropyl isocyanate.
[0013] As a preferred embodiment, the castor oil contains more than 80% ricinoleic acid.
[0014] This invention determines the amount and type of catalyst used based on the activity of the monoisocyanate. By introducing a catalyst, the reaction rate between the monoisocyanate and the active hydrogen on the hydroxyl groups of castor oil can be increased, thereby improving production efficiency and reducing energy consumption. Preferably, the catalyst is one or more of dibutyltin dilaurate, triethanolamine, and stannous octoate; for every 0.6 to 1.0 parts of monoisocyanate, the corresponding amount of catalyst is 0 to 0.01 parts. More preferably, the catalyst is dibutyltin dilaurate or triethanolamine.
[0015] Furthermore, in the reaction of monoisocyanate with castor oil, by controlling the ratio of monoisocyanate to castor oil to 0.6-1.0 parts and 6.5-7.5 parts, the present invention can change the trihydroxy functionality of castor oil to dihydroxy functionality, which is beneficial for preparing linear polyurethane and also beneficial for imparting excellent thermoplasticity to polyurethane.
[0016] As a preferred embodiment, the diisocyanate is isophorone diisocyanate or hexamethylene diisocyanate. In this invention, the diisocyanate is preferably a highly reactive aliphatic isocyanate. Compared with aromatic isocyanates, aliphatic diisocyanates are more conducive to controlling the polymerization rate, thereby avoiding the formation of rigid structures and facilitating the obtaining of linear polyurethane structures, thus improving the plasticity of the material.
[0017] As a preferred embodiment, the castor oil, catalyst, and diluent are pre-treated to remove water before use.
[0018] As a preferred embodiment, the re-reaction time is 80–300 min.
[0019] This invention incorporates a diluent into the re-reaction system, which adjusts the viscosity of castor oil-based thermoplastic polyurethane, thereby ensuring successful material preparation. Preferably, the diluent is one or more of tetrahydrofuran, N,N-dimethylformamide, methyl ethyl ketone, dichloromethane, and cyclohexanone.
[0020] During the reaction, the amount of diluent to be used needs to be determined based on the reaction conditions. As a preferred option, for every 0.6 to 1.0 parts by weight of monoisocyanate, the corresponding amount of diluent is 0.8 to 3 parts.
[0021] A castor oil-based thermoplastic polyurethane prepared by the above-described method for preparing castor oil-based thermoplastic polyurethane.
[0022] The beneficial effects of the technical solution of this invention are as follows:
[0023] I. The method for preparing castor oil-based thermoplastic polyurethane provided by this invention, by controlling the ratio and addition order of ricinoleic acid and monoisocyanate, enables effective reaction between castor oil and isocyanate, rationally consuming the active hydrogen in castor oil, and transforming castor oil from trihydroxy functional to dihydroxy functional to obtain castor oil-monoisocyanate linear segments. Further addition of diisocyanate to the reacted system for grafting reaction yields the predetermined linear polymer polyurethane structure.
[0024] The above-described preparation method of this invention employs a one-pot reaction involving two reaction steps, enabling the successful preparation of castor oil thermoplastic polyurethane. The preparation process and principle are simple and easily industrialized. Furthermore, in the polyurethane preparation, the amount of castor oil used in this invention reaches over 60%, effectively increasing the application rate of biomass-based materials. The resulting polyurethane product has a linear structure, simple composition, and easy reaction control, allowing for mass production. Compared to existing castor oil-based polyurethane preparation processes, this invention offers significant technical advantages.
[0025] II. The castor oil-based thermoplastic polyurethane provided by this invention, prepared using the above-described preparation strategy, uses renewable biomass-based castor oil as its main raw material. It contains no VOCs and will not cause environmental pollution, meeting environmental protection requirements. Its successful preparation not only helps reduce dependence on petroleum resources but also provides performance comparable to or even superior to traditional petroleum-based polyurethanes. Experiments have confirmed that the castor oil-based thermoplastic polyurethane prepared by this invention possesses good water resistance and biodegradability, while also exhibiting good mechanical strength and plasticity. Furthermore, it maintains high elasticity over a wide hardness range, showing broad application prospects in the field of polyurethane elastomers and contributing to the development of castor oil-based thermoplastic polyurethanes in materials science and industrial applications. Attached Figure Description
[0026] Figure 1 This is a photograph of the castor oil-based thermoplastic polyurethane prepared in Example 1 of the present invention.
[0027] Figure 2 This is a photograph of the castor oil-based polyurethane material prepared in Comparative Example 1.
[0028] Figure 3 Infrared curves of the raw materials and products used in the preparation of castor oil-based thermoplastic polyurethane in Example 1 of the present invention.
[0029] Figure 4 This is a DSC curve of the castor oil-based thermoplastic polyurethane prepared in Example 1 of the present invention;
[0030] Figure 5 This is a bar chart showing the water absorption rate of the castor oil-based thermoplastic polyurethane prepared in Example 1 of this invention at room temperature.
[0031] Figure 6 This is a line graph showing the mass change of the castor oil-based thermoplastic polyurethane prepared in Example 1 of the present invention at different temperatures. Detailed Implementation
[0032] The technical solution of the present invention will be further described below with reference to specific embodiments, but these should not be construed as limiting the scope of protection of the present invention. Unless otherwise specified, the raw materials used in the following embodiments are all conventional materials in the art. In particular, the castor oil involved in the following embodiments has a purity greater than 98%, and the fatty acid composition of the castor oil contains more than 80% ricinoleic acid.
[0033] The method for preparing castor oil-based thermoplastic polyurethane provided by the present invention includes the following steps:
[0034] Under a protective atmosphere, monoisocyanate was first added to castor oil, then a catalyst was added, and the mixture was stirred at 60–80°C for 80–300 min. After the stirring reaction was completed, diisocyanate was added to the reaction system, and the mixture was reacted again at 60–80°C. During the reaction, a diluent was added to adjust the viscosity. After the reaction was completed, the diluent was removed to obtain the castor oil-based thermoplastic polyurethane.
[0035] The monoisocyanate is one or more of cyclohexyl isocyanate, isopropyl isocyanate, m-toluene isocyanate, and furan methyl isocyanate; the diisocyanate is one or more of isoflurane diisocyanate, hexamethylene diisocyanate, toluene diisocyanate, and diphenylmethane diisocyanate; and the amounts of the monoisocyanate, castor oil, and diisocyanate, by mass, are 0.6-1.0 parts, 6.5-7.5 parts, and 0.8-2 parts, respectively.
[0036] In this invention, there are no particular limitations on the protective atmosphere; any conventional protective gas in the art, such as nitrogen, helium, or argon, may be used.
[0037] In this invention, the monoisocyanate is preferably a low-activity, large-molecule isocyanate, which is beneficial for controlling the degree of reaction and thus regulating the spatial structure of the product molecules, thereby improving the performance of thermoplastic polyurethane. As a preferred embodiment, the monoisocyanate is cyclohexyl isocyanate or isopropyl isocyanate.
[0038] As a preferred embodiment, the castor oil contains more than 80% ricinoleic acid.
[0039] This invention determines the amount and type of catalyst used based on the activity of the monoisocyanate. By introducing a catalyst, the reaction rate between the monoisocyanate and the active hydrogen on the hydroxyl groups of castor oil can be increased, thereby improving production efficiency and reducing energy consumption. Preferably, the catalyst is one or more of dibutyltin dilaurate, triethanolamine, and stannous octoate; for every 0.6 to 1.0 parts of monoisocyanate, the corresponding amount of catalyst is 0 to 0.01 parts. More preferably, the catalyst is dibutyltin dilaurate or triethanolamine.
[0040] Furthermore, by controlling the ratio and type of monoisocyanate to castor oil during the reaction of monoisocyanate and castor oil, this invention can change the trihydroxy functionality of castor oil to dihydroxy functionality, which is beneficial for preparing linear polyurethane and also for imparting excellent thermoplasticity to the polyurethane.
[0041] As a preferred embodiment, the diisocyanate is isophorone diisocyanate or hexamethylene diisocyanate. In this invention, the diisocyanate is preferably a highly reactive aliphatic isocyanate. Compared with aromatic isocyanates, aliphatic diisocyanates are more conducive to controlling the polymerization rate, thereby obtaining a polyurethane structure with linear segments, which is more conducive to improving the plasticity of the material.
[0042] As a preferred embodiment, the castor oil, catalyst, and diluent are pre-treated to remove water before use. This invention does not impose particular limitations on the water removal treatment; it employs conventional water removal methods in the art, as long as the purpose of water removal is achieved. For example, 4A molecular sieves can be used for water removal.
[0043] As a preferred embodiment, the re-reaction time is 80–300 min.
[0044] This invention incorporates a diluent into the re-reaction system, which adjusts the viscosity of castor oil-based thermoplastic polyurethane, thereby ensuring successful material preparation. Preferably, the diluent is one or more of tetrahydrofuran, N,N-dimethylformamide, methyl ethyl ketone, dichloromethane, and cyclohexanone.
[0045] This invention does not impose any special limitations on the timing or amount of diluent addition, as long as the reaction proceeds normally. During the reaction, the amount of diluent used can be determined based on the reaction conditions. As a preferred embodiment, for every 0.6 to 1.0 parts by weight of monoisocyanate, the corresponding amount of diluent is 0.8 to 3 parts.
[0046] After the reaction is complete, the present invention preferably cools the product first, and then removes the diluent. The present invention does not have a specific limitation on the cooling method; specifically, natural cooling to room temperature is acceptable. After cooling, the present invention does not have a specific limitation on the method of removing the diluent; specifically, methods such as distillation, vacuum distillation, and extraction can be used to remove the diluent.
[0047] Example 1
[0048] This embodiment provides a castor oil-based thermoplastic polyurethane, the preparation method of which specifically includes the following steps:
[0049] Castor oil, catalyst, and diluent were dehydrated using 4A molecular sieves and then kept on standby.
[0050] Under dry nitrogen protection, 6.6 parts by weight of castor oil were placed in a dry reflux condenser, and then 0.89 parts by weight of cyclohexyl isocyanate (C7H) were added. 11 NO) was added dropwise to castor oil, followed by 0.0001 parts of catalyst (dibutyltin dilaurate) to the reactor. The mixture was stirred until homogeneous, and the reactor temperature was raised to 75°C. Stirring, maintaining the temperature, and refluxing were continued for 150 minutes. Then, 1.58 parts of isoflurane diisocyanate (C) were added. 12 H 18 N2O2) was added to the reactor for further reaction. During the reaction, 0.91 parts of diluent (tetrahydrofuran) were added to adjust the viscosity. The reaction time was 150 min. After the reaction was completed, the mixture was poured into a mold, cooled, and finally vacuum heated to remove the diluent, thus obtaining castor oil-based thermoplastic polyurethane.
[0051] Example 2
[0052] This embodiment provides a castor oil-based thermoplastic polyurethane, which uses the same raw materials and preparation steps as in Example 1. The only difference from Example 1 is that the amount of isoflurane diisocyanate added is 1.6 parts.
[0053] Example 3
[0054] This embodiment provides a castor oil-based thermoplastic polyurethane, which uses the same raw materials and preparation steps as in Example 1. The only difference from Example 1 is that the amount of isoflurane diisocyanate added is 1.5 parts.
[0055] Example 4
[0056] This embodiment provides a castor oil-based thermoplastic polyurethane, which uses the same raw materials and preparation steps as in Example 1. The only difference from Example 1 is that the amount of isoflurane diisocyanate added is 1.4 parts.
[0057] Example 5
[0058] This embodiment provides a castor oil-based thermoplastic polyurethane, which uses the same raw materials and preparation steps as in Example 1. The only difference from Example 1 is that the amount of isoflurane diisocyanate added is 1.8 parts.
[0059] Example 6
[0060] This embodiment provides a castor oil-based thermoplastic polyurethane, the preparation method of which specifically includes the following steps:
[0061] Castor oil, catalyst, and diluent were dehydrated using 4A molecular sieves and then kept on standby.
[0062] Under dry nitrogen protection, 6.92 parts by weight of castor oil were placed in a dry reflux reactor. Then, 0.93 parts of cyclohexyl isocyanate were added dropwise to the castor oil, followed by 0.0001 parts of catalyst (dibutyltin dilaurate). The mixture was stirred until homogeneous, and the reactor temperature was raised to 80°C. The mixture was continuously stirred, kept warm, and refluxed for 90 minutes. Then, 1.25 parts of hexamethylene diisocyanate were added to the reactor for further reaction. During the reaction, 0.91 parts of diluent (tetrahydrofuran) were added to adjust the viscosity. The reaction time was 90 minutes. After the reaction was completed, the mixture was poured into a mold, cooled, and finally vacuum heated to remove the diluent, thus obtaining castor oil-based thermoplastic polyurethane.
[0063] Example 7
[0064] This embodiment provides a castor oil-based thermoplastic polyurethane, the preparation method of which specifically includes the following steps:
[0065] Castor oil, catalyst, and diluent were dehydrated using 4A molecular sieves and then kept on standby.
[0066] Under dry nitrogen protection, 7.15 parts by weight of castor oil were placed in a dry reflux reactor. Then, 0.65 parts of isopropyl isocyanate were added dropwise to the castor oil, followed by 0.0001 parts of catalyst (dibutyltin dilaurate). The mixture was stirred until homogeneous, and the reactor temperature was raised to 75°C. The mixture was continuously stirred, kept warm, and refluxed for 150 minutes. Then, 0.91 parts of hexamethylene diisocyanate were added to the reactor for further reaction. During the reaction, 0.91 parts of diluent (tetrahydrofuran) were added to adjust the viscosity. The reaction time was 150 minutes. After the reaction was completed, the mixture was poured into a mold, cooled, and finally vacuum heated to remove the diluent, thus obtaining castor oil-based thermoplastic polyurethane.
[0067] Example 8
[0068] Castor oil, catalyst, and diluent were dehydrated using 4A molecular sieves and then kept on standby.
[0069] Under dry nitrogen protection, 7.15 parts by weight of castor oil were placed in a dry reflux reactor. Then, 0.65 parts of isopropyl isocyanate were added dropwise to the castor oil, followed by 0.0001 parts of catalyst (dibutyltin dilaurate). The mixture was stirred until homogeneous, and the reactor temperature was raised to 75°C. The mixture was continuously stirred, kept warm, and refluxed for 150 minutes. Then, 0.91 parts of hexamethylene diisocyanate were added to the reactor for further reaction. During the reaction, 0.91 parts of diluent (N,N-dimethylformamide) were added to adjust the viscosity. The reaction time was 150 minutes. After the reaction was completed, the mixture was poured into a mold, cooled, and finally vacuum heated to remove the diluent, thus obtaining castor oil-based thermoplastic polyurethane.
[0070] Example 9
[0071] This embodiment provides a castor oil-based thermoplastic polyurethane, the preparation method of which specifically includes the following steps:
[0072] Castor oil, catalyst, and diluent were dehydrated using 4A molecular sieves and then kept on standby.
[0073] Under dry nitrogen protection, 7.15 parts by weight of castor oil were placed in a dry reflux reactor. Then, 0.65 parts of isopropyl isocyanate were added dropwise to the castor oil, followed by 0.0001 parts of catalyst (triethanolamine). The mixture was stirred until homogeneous, and the reactor temperature was raised to 75°C. The mixture was continuously stirred, kept warm, and refluxed for 150 minutes. Then, 0.91 parts of hexamethylene diisocyanate were added to the reactor for further reaction. During the reaction, 0.91 parts of diluent (N,N-dimethylformamide) were added to adjust the viscosity. The reaction time was 150 minutes. After the reaction was completed, the mixture was poured into a mold, cooled, and finally vacuum heated to remove the diluent, thus obtaining castor oil-based thermoplastic polyurethane.
[0074] Example 10
[0075] This embodiment provides a castor oil-based thermoplastic polyurethane, the preparation method of which specifically includes the following steps:
[0076] Castor oil, catalyst, and diluent were dehydrated using 4A molecular sieves and then kept on standby.
[0077] Under dry nitrogen protection, 6.69 parts by weight of castor oil were placed in a dry reflux reactor. Then, 0.61 parts of isopropyl isocyanate were added dropwise to the castor oil and stirred until homogeneous. The reactor temperature was raised to 60°C, and stirring and reflux were maintained continuously for 270 minutes. Then, 1.79 parts of diphenylmethane diisocyanate were added to the reactor for further reaction. During the reaction, 0.91 parts of diluent (NN-dimethylformamide) were added to adjust the viscosity. The reaction time was 270 minutes. After the reaction was completed, the mixture was poured into a mold, cooled, and finally vacuum heated to remove the diluent, thus obtaining castor oil-based thermoplastic polyurethane.
[0078] Comparative Example 1
[0079] This comparative example provides a polyurethane material, the preparation method of which specifically includes the following steps:
[0080] Castor oil, catalyst, and diluent were dehydrated using 4A molecular sieves and then kept on standby.
[0081] Under dry nitrogen protection, 0.89 parts by weight of cyclohexyl isocyanate were placed in a dry reflux reactor. Then, 6.6 parts of castor oil were added dropwise to the 0.89 parts of cyclohexyl isocyanate. Next, 0.0001 parts of catalyst (dibutyltin dilaurate) were added to the reactor and stirred until homogeneous. The reactor temperature was raised to 75°C, and stirring, heat preservation, and reflux were continued for 150 min. Then, 1.58 parts of isoflurane diisocyanate were added to the reactor for further reaction. During the reaction, 0.91 parts of diluent (tetrahydrofuran) were added to adjust the viscosity. The reaction time was 150 min. After the reaction was completed, the mixture was poured into a mold, cooled, and finally vacuum heated to remove the diluent, thus obtaining the polyurethane material.
[0082] Comparative Example 2
[0083] This comparative example provides a polyurethane material, the preparation method of which specifically includes the following steps:
[0084] Under dry nitrogen protection, 6.6 parts by weight of castor oil were placed in a dry reflux reactor, and then 0.44 parts by weight of cyclohexyl isocyanate (C7H) were added. 11 NO) was added dropwise to castor oil, followed by 0.0001 parts of catalyst (dibutyltin dilaurate) to the reactor. The mixture was stirred until homogeneous, and the reactor temperature was raised to 75°C. Stirring, maintaining the temperature, and refluxing were continued for 150 minutes. Then, 1.58 parts of isoflurane diisocyanate (C) were added. 12 H 18N₂O₂ was added to the reactor for further reaction. During the reaction, 0.91 parts of diluent (tetrahydrofuran) were added to adjust the viscosity. After 30 minutes of reaction, a gel-like structure was observed in the reactor solution, indicating that the preparation of thermoplastic polyurethane had failed. The reason for this failure was that the amount of monoisocyanate used was insufficient, resulting in the castor oil's hydroxyl groups not being consumed to the dihydroxyl functionality level (at which point the average number of hydroxyl groups in castor oil is greater than 2), thus preventing it from reacting with diisocyanate to form a network gel structure.
[0085] Comparative Example 3
[0086] This comparative example provides a polyurethane material, the preparation method of which specifically includes the following steps:
[0087] Castor oil, catalyst, and diluent were dehydrated using 4A molecular sieves and then kept on standby.
[0088] Under dry nitrogen protection, 6.6 parts by weight of castor oil were placed in a dry reflux reactor, and then 1.80 parts by weight of cyclohexyl isocyanate (C7H) were added. 11 NO) was added dropwise to castor oil, followed by 0.0001 parts of catalyst (dibutyltin dilaurate) to the reactor. The mixture was stirred until homogeneous, and the reactor temperature was raised to 75°C. Stirring, maintaining the temperature, and refluxing were continued for 150 minutes. Then, 1.58 parts of isoflurane diisocyanate (C) were added. 12 H 18 N₂O₂ was added to the reactor for further reaction. During the reaction, 0.91 parts of diluent (tetrahydrofuran) were added to adjust the viscosity. The reaction time was 500 minutes. After the reaction, the mixture was poured into a mold, cooled, and finally removed by vacuum heating. An oily substance was found, leading to the failure of thermoplastic polyurethane preparation. The reason was that too much monoisocyanate was used, resulting in an excessive consumption of the hydroxyl groups in castor oil (at this point, the average number of hydroxyl groups in castor oil was less than 2). This caused the castor oil to react with diisocyanate to form low-molecular-weight compounds, making it impossible to prepare thermoplastic polyurethane.
[0089] The technical effects of the castor oil-based thermoplastic polyurethane and its preparation method of the present invention will be described in detail below.
[0090] Experimental Example 1
[0091] This experimental example combines specific experiments to characterize the appearance of the castor oil-based thermoplastic polyurethane prepared in Example 1, as well as perform infrared and differential scanning calorimetry analysis, and test its water resistance and biodegradability.
[0092] Figure 1 This is a photograph of the castor oil-based thermoplastic polyurethane prepared in Example 1 of the present invention. Figure 1It is known that the castor oil-based biomass-based polyurethane prepared by this invention is a transparent body, conforming to the conventional morphology of thermoplastic polyurethane, and can be prepared in large quantities.
[0093] Further characterization was performed on the physical image of the polyurethane material prepared in Comparative Example 1. Figure 2 This is a photograph of the castor oil-based polyurethane material prepared in Comparative Example 1. Figure 2 It can be seen that this comparative ratio cannot achieve the successful preparation of thermoplastic polyurethane. After preparation, a gel is produced, resulting in a thermosetting isocyanate.
[0094] Figure 3 Infrared spectroscopy curves of the raw materials and products used in the preparation of castor oil-based thermoplastic polyurethane in Example 1 of this invention. Figure 3 It can be seen that by comparing the Fourier transform infrared spectral curves of the raw materials (castor oil, monoisocyanate) and the castor oil-based thermoplastic polyurethane prepared in this invention, it can be determined that the castor oil-based thermoplastic polyurethane prepared in this invention has the predetermined chemical structure.
[0095] Figure 4 This is a DSC curve of the castor oil-based thermoplastic polyurethane prepared in Example 1 of this invention. Figure 4 It can be seen that the castor oil-based polyurethane prepared by this invention has a low glass transition temperature and a certain degree of softness at room temperature. Therefore, the low glass transition temperature in the above DSC diagram effectively confirms that the castor oil-based polyurethane designed in this invention is a thermoplastic polyurethane.
[0096] Figure 5 This is a bar chart showing the water absorption rate of the castor oil-based thermoplastic polyurethane prepared in Example 1 of this invention at room temperature (test time 24h). Figure 5 It can be seen that the castor oil-based thermoplastic polyurethane prepared by the present invention has a low water absorption rate, with an average water absorption rate of only 0.64% for the three samples, and has good water resistance stability.
[0097] Figure 6 This is a line graph showing the mass change of the castor oil-based thermoplastic polyurethane prepared in Example 1 of this invention at different temperatures (40–100°C, pH = 10). Figure 6 It can be seen that the castor oil-based thermoplastic polyurethane prepared by the present invention loses mass to varying degrees with increasing temperature under alkaline accelerated degradation conditions (4h), but the overall loss is small, with a loss rate of less than 2%, indicating that the polyurethane material prepared by the present invention has good degradability under special conditions.
[0098] Experimental Example 2
[0099] This experimental example combines specific tests to test the mechanical properties (tensile strength, elongation at break, and Shore hardness) of the castor oil-based thermoplastic polyurethanes prepared in Examples 1-10 of this invention. Table 1 shows the test results of the mechanical properties of the castor oil-based thermoplastic polyurethanes prepared in different embodiments of this invention.
[0100] Table 1
[0101] experimental group Tensile strength (MPa) Elongation at break (%) Shore hardness (HA) Example 1 4.50 125 30 Example 2 4.45 110 25 Example 3 4.38 106 23 Example 4 4.26 101 20 Example 5 4.47 111 26 Example 6 4.48 123 31 Example 7 4.47 124 30 Example 8 4.48 120 31 Example 9 4.55 126 29 Example 10 4.60 98 33
[0102] As shown in Table 1, the castor oil-based thermoplastic polyurethane prepared by this invention has excellent plasticity and mechanical strength, and these properties can be effectively adjusted according to changes in reaction conditions.
[0103] In summary, the castor oil-based thermoplastic polyurethane provided by this invention uses renewable biomass-based castor oil as one of its main raw materials, contains no VOCs, and will not cause environmental pollution, meeting environmental protection requirements and enabling mass production. In particular, the castor oil-based thermoplastic polyurethane prepared by this invention possesses good water resistance and biodegradability, while also exhibiting good mechanical strength and plasticity, maintaining high elasticity over a wide hardness range. It has broad application prospects in the field of polyurethane elastomers and is conducive to promoting the development of castor oil-based thermoplastic polyurethane in materials science and industrial applications.
[0104] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.
Claims
1. A process for the preparation of castor oil based thermoplastic polyurethane characterized in that, The method comprises the following steps: The monoisocyanate is added into the castor oil under a protective atmosphere, and then the catalyst is added, and the reaction is stirred at a temperature of 60-80 ℃ for 80-300 min; after the stirring reaction is completed, the diisocyanate is added into the system after the reaction, and the re-reaction is carried out at a temperature of 60-80 ℃; the diluent is added during the re-reaction to adjust the viscosity; after the re-reaction is completed, the diluent is removed, and the castor oil-based thermoplastic polyurethane is obtained; The monoisocyanate is one or more of cyclohexyl isocyanate, isopropyl isocyanate, m-toluene isocyanate and furanmethyl isocyanate; the diisocyanate is one or more of isophorone diisocyanate, hexamethylene diisocyanate, toluene diisocyanate and diphenylmethane diisocyanate; the monoisocyanate, the castor oil and the diisocyanate are used in an amount of 0.6-1.0 parts, 6.5-7.5 parts and 0.8-2 parts, respectively.
2. The process for the preparation of castor oil based thermoplastic polyurethane as claimed in claim 1, wherein, The monoisocyanate is cyclohexyl isocyanate or isopropyl isocyanate.
3. The process for the preparation of castor oil based thermoplastic polyurethane as claimed in claim 1, wherein, The content of ricinoleic acid contained in the castor oil is greater than 80%.
4. The process for the preparation of castor oil based thermoplastic polyurethane as claimed in claim 1, wherein, The catalyst is one or more of dibutyltin dilaurate, triethanolamine and stannous octoate; the amount of the catalyst corresponding to 0.6-1.0 parts of the monoisocyanate is 0-0.01 parts.
5. The process for the preparation of castor oil based thermoplastic polyurethane as claimed in claim 1, wherein, The diisocyanate is isophorone diisocyanate or hexamethylene diisocyanate.
6. The process for the preparation of castor oil based thermoplastic polyurethane according to any one of claims 1 to 5, characterized in that, The castor oil, the catalyst and the diluent are subjected to water removal treatment in advance before use.
7. The process for the preparation of castor oil based thermoplastic polyurethane according to any one of claims 1 to 5, characterized in that, The re-reaction time is 80-300 min.
8. The process for the preparation of castor oil based thermoplastic polyurethane according to any one of claims 1 to 5, characterized in that, The diluent is one or more of tetrahydrofuran, N,N-dimethylformamide, methyl ethyl ketone, dichloromethane and cyclohexanone.
9. The process for the preparation of castor oil based thermoplastic polyurethane according to any one of claims 1 to 5, characterized in that, The amount of the diluent corresponding to 0.6-1.0 parts of the monoisocyanate is 0.8-3 parts.
10. A castor oil-based thermoplastic polyurethane prepared by the method according to any one of claims 1-9.