A vegetable oil-based recyclable thermosetting resin and its preparation method and application

Abstract

The present invention belongs to the technical field of bio-based polymer materials, and in particular to a kind of vegetable oil-based recyclable thermosetting resin and its preparation method and application. The present invention adopts the click reaction under ultraviolet light of the thiol-olefin of polythiol ester thiol and vegetable oil unsaturated carbon-carbon double bond, and carries out high-activity multi-reaction site modification to vegetable oil, thereby solving the difficult problem that vegetable oil is difficult to high-value utilization. Further, by polymerizing the vegetable oil-based monomer (thiol vegetable oil) modified by polythiol ester thiol with isocyanate monomer or isocyanate-terminated prepolymer, directly prepare a thermosetting polymer containing thermally reversible dynamic thiol carbamate bond, thereby solving the difficult problem that vegetable oil thermosetting resin cannot be recycled and processed.

Description

Technical Field

[0001] The present invention belongs to the technical field of bio-based polymer materials, and in particular relates to a plant oil-based recyclable thermosetting resin and a preparation method and application thereof. Background Art

[0002] China boasts abundant plant oil resources and numerous unique advantages, making them one of the world's most important biomass resources. Plant oils are not only widely used in the food industry but also hold enormous potential in the bioenergy sector as an alternative to traditional energy sources. Furthermore, their low cost, biodegradability, and tunable properties make them an ideal renewable biomass resource with promising development prospects. In the context of increasingly severe global environmental challenges and the depletion of petroleum resources, plant oils hold significant strategic importance as an environmentally friendly alternative. However, the current comprehensive utilization rate of plant oils in China remains low, and the development of high-value-added products lags behind, hindering the full realization of their economic benefits. While plant oils hold immense potential as an important renewable resource, their practical application is often limited to traditional, low-value-added sectors, such as edible oils and oil fertilizers, lacking advanced processing and high-value products. Therefore, enhancing the high-value utilization of plant oils and developing higher-value-added products remains a pressing technical challenge. The conversion and high-value utilization of plant oils is plagued by scarcity, low quality, and extensive development. Most vegetable oils and fats are still in the simple physical or chemical processing stage, and the conversion process lacks refinement and efficiency, failing to fully realize their potential.

[0003] Plant oil-based thermosetting resins are a prime example of the high-value transformation of vegetable oils. These resins are chemically modified from vegetable oils (such as soybean oil, rapeseed oil, palm oil, and castor oil) as the primary raw material. These resins exhibit thermosetting properties, meaning that under heating or the presence of a catalyst, they crosslink and solidify, forming an insoluble, infusible three-dimensional network structure that imparts excellent mechanical properties, heat resistance, and chemical stability.

[0004] However, thermosetting resins usually have a cross-linked structure and form a three-dimensional network structure once cured, which makes it difficult to reheat, mold and recycle like thermoplastics. Most traditional thermosetting resins are discarded after use and cannot be reused, so there is a great problem of resource waste. Introducing dynamic reversible chemical bonds to achieve recyclability is the most convenient recycling strategy. Specifically, by introducing dynamic reversible ester bonds, large hindered urea bonds, oxime bonds, etc. into vegetable oil-based thermosetting resins, these bonds can be broken under heating or catalytic conditions, so that the resin can be re-crosslinked or reprocessed under certain conditions. Therefore, introducing reversible reactions or detachable chemical bonds (such as hydrogen bonds, dynamic covalent bonds, etc.) into resin molecules can achieve resin recovery and reuse.

[0005] In particular, compared to traditional petroleum-based thermosetting resins (such as epoxy resins and phenolic resins), plant oil-based thermosetting resins are significantly more environmentally friendly, reducing the consumption of petroleum resources and the emission of harmful substances. Furthermore, plant oils are widely available, inexpensive, and renewable, making them ideal raw materials for the preparation of recyclable thermosetting resins. Through chemical modification of plant oils (such as epoxidation, chlorination, and esterification), the properties of the resins can be precisely controlled, resulting in excellent mechanical strength, heat resistance, antioxidant properties, and UV resistance, meeting the needs of various applications.

[0006] However, plant oils and fats often have limited double bond content and are often highly inert, making modification of their highly active, multi-reactive sites challenging. Furthermore, combining them with dynamic reversible bonds to increase their value and transform them into recyclable thermosetting resins presents technical challenges (e.g., cumbersome synthesis methods, mechanical properties that struggle to match those of conventional polymers, and low recycling efficiency).

[0007] Therefore, seeking a simple and efficient method to achieve high-activity multi-reaction site modification of vegetable oils while maintaining the triglyceride structure, in order to convert the high-value vegetable oils into recyclable thermosetting resins has become a technical problem that technicians in this field urgently need to solve. Summary of the Invention

[0008] In view of this, the purpose of the present invention is to address the existing technical problems and provide a simple and efficient method for achieving high-activity multi-reaction site modification of vegetable oils while maintaining the triglyceride structure, as well as a vegetable oil-based recyclable thermosetting resin prepared by using this method and its application.

[0009] In order to achieve the above objectives, the first object of the present invention is to provide a method for preparing a vegetable oil-based recyclable thermosetting resin, which adopts the following technical solution:

[0010] A method for preparing a vegetable oil-based recyclable thermosetting resin comprises modifying the multiple reaction sites of the vegetable oil through an ultraviolet light click reaction between polythiol ester thiols and vegetable oil; the resulting modified vegetable oil is then reacted with an isocyanate monomer to obtain a first type of vegetable oil-based recyclable thermosetting resin, or polymerized with an isocyanate-terminated prepolymer to obtain a second type of vegetable oil-based recyclable thermosetting resin.

[0011] It is worth noting that the double bond content in vegetable oils (such as linoleic acid and oleic acid) is limited and has a certain degree of chemical inertness, especially under relatively mild conditions. This is because most double bonds in vegetable oils are directly connected to alkyl chains and are affected by steric hindrance, making them less likely to react with other reagents. Therefore, direct modification of vegetable oils with multiple reactive sites often faces challenges such as poor reaction selectivity, low efficiency, and harsh reaction conditions. However, through the UV-light click reaction of polythiol ester thiols with vegetable oils, multi-reactive site modification of vegetable oils can be effectively achieved under mild conditions. The UV-light excitation reaction significantly enhances the reactivity of the double bonds, enabling selective click reactions with polythiol ester thiols. This method not only has mild reaction conditions, high selectivity, high efficiency, and conforms to atom economy, but also can simultaneously introduce multiple reactive sites on the unsaturated fatty acid esters while maintaining the original structure of vegetable oil triglycerides, greatly enhancing the potential for high-value conversion of vegetable oils.

[0012] Furthermore, first, under ultraviolet light, vegetable oil is added dropwise to the polythiol ester thiol, and after the addition is completed, the ultraviolet light is turned off to obtain thiolated vegetable oil;

[0013] Then, an organic solvent is added to dissolve the thiolated vegetable oil, and a diisocyanate monomer and a catalyst are added to the mixed solution, and the mixture is cured at 20 to 80° C. to obtain the first type of vegetable oil-based recyclable thermosetting resin; or,

[0014] After adding an organic solvent to dissolve the thiolated vegetable oil, adding an isocyanate-terminated prepolymer and a catalyst to the mixed solution, and curing at 35-65° C. to obtain the second type of vegetable oil-based recyclable thermosetting resin.

[0015] It is worth noting that the preparation method of the present invention is simple and efficient, and solves the difficult problems of high-value utilization of vegetable oils and non-recyclable thermosetting resins. The prepared vegetable oil-based recyclable thermosetting resin not only meets the performance requirements of thermosetting resins, but also has controllable performance. During the preparation process, on the basis of the first type of vegetable oil-based recyclable thermosetting resin, after the isocyanate-terminated prepolymer is introduced into the structure, the elongation at break and the tensile strength are greatly improved, and the mechanical properties of the second type of vegetable oil-based recyclable thermosetting resin prepared using different types of diisocyanate drugs are different. In addition, the mechanical properties of the vegetable oil-based recyclable thermosetting resin prepared using different types of polythiol ester thiol drugs will also be different. The present invention can prepare vegetable oil-based recyclable thermosetting resins with different mechanical properties according to different scenarios of actual use.

[0016] Furthermore, the preparation method of the isocyanate-terminated prepolymer is:

[0017] At 40-100°C, convert the diol or diammonium polymer from a solid state to a liquid state. Under a nitrogen atmosphere, add polytetrahydrofuran to a three-necked flask with mechanical stirring, raise the temperature to 100-120°C and maintain for 2-3 hours, then cool to 45-90°C, add diisocyanate monomer and dibutyltin dilaurate, mechanically stir at 40-100°C for 2-6 hours, cool to 35-65°C, and add an organic solvent.

[0018] Furthermore, the diol or diammonium polymer includes polytetramethylene glycol (PTMEG), polyetheramine (PEA) or polycaprolactone diol (PCL).

[0019] Furthermore, the polythiol ester thiol is one of pentaerythritol tetrakis(thioglycolate) ester PETMA, pentaerythritol tetrakis(3-mercaptopropionate) ester PETMP, trimethylolpropane tris(thioglycolate) TMPMA, trimethylolpropane tris(3-mercaptopropionate) TMPMP, and dipentaerythritol hexa(3-mercaptopropionate) ester DI-PETMP; the vegetable oil includes soybean oil, olive oil, linseed oil, castor oil, cottonseed oil, tung oil, peanut oil, corn oil, rapeseed oil or palm oil; the catalyst includes N,N-diisopropylethylamine DIPEA, 4-dimethylaminopyridine DMAP, 1,8-diazabicyclo[5.4.0]undec-7-ene DBU, triethylamine TEA or dibutyltin dilaurate DBTDL; and the organic solvent includes one or more of methanol, ethanol, propanol, acetone, dioxane, tetrahydrofuran, methyl ethyl ketone, n-butanol, and ethyl acetate.

[0020] It is worth noting that the structural formula of the polythiol ester thiol is:

[0021]

[0022] The structural formula of the catalyst is:

[0023]

[0024] Furthermore, the diisocyanate monomer includes 4,4'-dicyclohexylmethane diisocyanate HMDI, tetramethyl-m-xylylene diisocyanate TMXDI, isophorone diisocyanate IPDI, hexamethylene diisocyanate HDI, diphenylmethane diisocyanate MDI, toluene diisocyanate TDI, meta-xylylene diisocyanate XDI or hexamethylene diisocyanate isocyanurate trimer tri-HDI, and the structural formula of the diisocyanate monomer is:

[0025]

[0026] In some embodiments, the preparation path of the first type of vegetable oil-based recyclable thermosetting resin disclosed in the present invention is:

[0027]

[0028] First, under ultraviolet light, vegetable oil 1 is added dropwise to polythiol ester thiol 2. After the addition is completed, the ultraviolet light is turned off to obtain thiolated vegetable oil 3. Then, an organic solvent is added to dissolve the thiolated vegetable oil. Then, diisocyanate monomer 4 and dibutyltin diisocyanate DBTDL 5 are added to the mixed solution, and the mixture is cured at 20-80°C to obtain a first type of vegetable oil-based recyclable thermosetting resin 6.

[0029] And, in some embodiments, the preparation path of the second type of vegetable oil-based recyclable thermosetting resin disclosed in the present invention is:

[0030]

[0031] First, prepare the isocyanate-terminated prepolymer 9: Polytetrahydrofuran 7 is converted from a solid state to a liquid state at 40-100°C. Under a nitrogen atmosphere, the polytetrahydrofuran is added to a three-necked flask with mechanical stirring and heated to 100-120°C for 2-3 hours. The temperature is then lowered to 45-90°C, followed by the addition of diisocyanate monomer 4 and dibutyltin dilaurate (DBTDL). The mixture is mechanically stirred at 40-100°C for 2-6 hours, cooled to 35-65°C, and an organic solvent is added. Under UV light, vegetable oil 1 is added dropwise to the polythiol ester thiol 2. After the addition is complete, the UV light is turned off to produce thiolated vegetable oil 3. Then, an organic solvent is added to dissolve the thiolated vegetable oil 3. Once dissolved, the isocyanate-terminated prepolymer 9, dibutyltin dilaurate (DIPEA) 5, and a catalyst are added to the mixed solution. The resin is cured at 35-65° C. to obtain the second type of vegetable oil-based recyclable thermosetting resin 10.

[0032] Therefore, the plant oil-based recyclable thermosetting resin disclosed in the present invention contains characteristic dynamically reversible thiocarbamate bond units, which endow the plant oil-based polymer material with thermoreversible self-repairing and recyclable properties. Plant oil contains double bonds, but double bonds are inert and difficult to convert into high-value products. The present invention achieves the modification of highly active multi-reaction sites of plant oils while maintaining the original structure, and converts them into recyclable thermosetting resins with high value, thereby enhancing the material's stability in use and extending its service life.

[0033] The second object of the present invention is to provide a vegetable oil-based recyclable thermosetting resin prepared by the preparation method described above.

[0034] The invention discloses a vegetable oil-based recyclable thermosetting resin, which is composed of polythiol ester mercaptan, vegetable oil, diisocyanate monomer or isocyanate-terminated prepolymer, and a catalyst.

[0035] Furthermore, the first type of vegetable oil-based recyclable thermosetting resin is composed of the following components in parts by weight: 2.5 to 8.0 parts of polythiol ester mercaptan, 0.3 to 4.5 parts of vegetable oil, 2.1 to 7.4 parts of diisocyanate monomer and 0.2 to 0.7 parts of catalyst;

[0036] The second type of vegetable oil-based recyclable thermosetting resin is composed of the following components in parts by weight: 0.4 to 5.3 parts of polythiol ester mercaptan, 0.3 to 7.4 parts of vegetable oil, 4.3 to 79.9 parts of isocyanate-terminated prepolymer and 0.2 to 0.7 parts of catalyst.

[0037] The isocyanate-terminated prepolymer is composed of the following components in parts by weight: 2.3 to 12.9 parts of polytetramethylene glycol (PTMEG) or polyetheramine (PEA) or polycaprolactone diol (PCL), 0.7 to 2.6 parts of diisocyanate monomer and 0.2 to 0.7 parts of dibutyltin dilaurate.

[0038] It is worth noting that the first type of resin disclosed in the present invention usually behaves like a hard plastic in a room temperature environment. It is obtained by polymerizing rigid small molecule raw materials, namely, polythioester thiols, vegetable oils, and diisocyanate monomers under the action of a catalyst. The molecular chain structure is relatively rigid, so it has high strength, rigidity and heat resistance, and is suitable for manufacturing structural parts, automotive parts, electronic equipment casings and other occasions requiring high strength and stability. The second type of resin usually behaves like an elastic rubber in a room temperature environment. It is obtained by polymerizing rigid small molecule raw materials, polythioester thiols, vegetable oils, and diisocyanate monomers with flexible diol or diamine-terminated polymer molecular chains (such as polytetrahydrofuran). The molecular chain has a large degree of freedom and flexibility, so it has excellent elasticity, flexibility and impact resistance, and can be used in seals, shock absorbers, tires and other scenes requiring high elasticity, wear resistance and aging resistance.

[0039] The third object of the present invention is to provide the use of the vegetable oil-based recyclable thermosetting resin as described above.

[0040] Application of the vegetable oil-based recyclable thermosetting resin in thermoreversible self-healing materials.

[0041] Furthermore, the plant oil-based recyclable thermosetting resin is used in the preparation of packaging materials, biomedical devices, 3D printing materials, automotive parts, coatings and adhesive materials.

[0042] Compared with the prior art, the present invention has the following beneficial technical effects:

[0043] (1) Achieving efficient conversion of vegetable oils and fats using a simple synthetic process: The present invention utilizes a click reaction under ultraviolet light between polythiol ester thiols and thiol-olefins in the unsaturated carbon-carbon double bonds of vegetable oils to modify vegetable oils with highly active multi-reactive sites. This method not only maintains the original structure of the oils and fats but also enables precise control at the molecular level. Furthermore, by polymerizing commercially available vegetable oil-based monomers with isocyanate raw materials, thermosetting polymers containing thermally reversible dynamic thiolcarbamate bonds are directly prepared, simplifying the synthetic process and improving synthetic efficiency.

[0044] (2) Mechanisms for regulating the structure and properties of plant oil-based thermosetting resins: The readily available polythiol ester thiols with diverse molecular structures and plant oil raw materials can lead to breakthroughs in polymer structure design and control. By regulating and optimizing the soft and hard phase separation and various intermolecular interactions within polymer molecules, the development of high-performance thermosetting resins has been achieved, providing new ideas for replacing traditional polymer materials.

[0045] (3) Technology for the repeated processing and recycling of plant oil-based thermosetting resins: The solid-state recycling and recycling of resins are achieved by utilizing the thermally reversible dynamic chemistry of thiocarbamate bonds, thereby realizing the recycling and resource utilization of biomass-based polymer materials. This environmentally friendly recycling technology provides a new solution to the environmental and energy problems brought about by petroleum-based polymer materials. The present invention solves the problem of the non-biodegradability of plant oil-based thermosetting resins and does not modify the ester structure of the plant oil. The thiocarbamate bonds are introduced through a simple method, solving the problem of reprocessing and reuse of thermosetting materials.

[0046] (4) Plant oil-based recyclable thermosetting resins are not only environmentally friendly, low-cost, and recyclable, but also exhibit unique advantages in terms of recyclability. Through structural regulation and innovation in recycling technology, plant oil-based thermosetting resins are expected to become the core of future green materials, driving the development of materials science towards a more sustainable and environmentally friendly direction.

[0047] Therefore, the present invention aims to solve the problem of the difficulty in high-value utilization of vegetable oils and the non-recyclability of thermosetting resins. The present invention uses a click reaction under ultraviolet light between polythiol ester thiols and thiol-olefins with unsaturated carbon-carbon double bonds in vegetable oils to modify vegetable oils with high activity and multiple reaction sites, thereby solving the problem of the difficulty in high-value utilization of vegetable oils. The present invention directly prepares thermosetting polymers containing thermally reversible dynamic thiolcarbamate bonds by polymerizing commercial vegetable oil-based monomers with isocyanate raw materials, thereby solving the problem of non-recyclability of vegetable oil thermosetting resins. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0049] Figure 1 FT-IR spectra of Examples 1, 7 and 8 of the present invention.

[0050] Figure 2 Schematic diagram of differential scanning calorimetry (DSC) curves of Examples 1, 7, and 8 of the present invention.

[0051] Figure 3 Schematic diagram of the glass transition temperature of Examples 1, 7, and 8 of the present invention. DETAILED DESCRIPTION

[0052] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0053] The term "embodiment" is used herein specifically to describe any embodiment as "exemplary," and should not be construed as superior or preferable to other embodiments. Performance indicators in the embodiments of this application were tested using conventional testing methods in the art, unless otherwise specified. It should be understood that the terms used in this application are intended solely to describe specific implementations and are not intended to limit the disclosure herein.

[0054] Unless otherwise specified, the technical and scientific terms used herein have the same meanings as commonly understood by ordinary technicians in the technical field to which this application belongs; other experimental methods and technical means not specifically specified in this application refer to experimental methods and technical means commonly used by ordinary technicians in this field.

[0055] In order to better illustrate the content of this application, numerous specific details are provided in the specific examples below. It should be understood by those skilled in the art that this application can be implemented without certain specific details. In the examples, some methods, means, instruments, equipment, etc. well known to those skilled in the art are not described in detail in order to highlight the main purpose of this application.

[0056] Under the premise of no conflict, the technical features disclosed in the embodiments of this application can be combined arbitrarily, and the resulting technical solutions belong to the contents disclosed in the embodiments of this application.

[0057] The present invention belongs to the technical field of bio-based polymer materials, and specifically relates to a plant oil-based recyclable thermosetting resin, its preparation method and application. The present invention adopts a click reaction under ultraviolet light between polythioester thiols and thiol-olefins of unsaturated carbon-carbon double bonds of plant oils to modify plant oils with high activity and multiple reaction sites, thereby solving the problem that plant oils are difficult to utilize in a high-value manner. Furthermore, by polymerizing plant oil-based monomers (thiolated plant oils) modified with polythioester thiols with isocyanate monomers or isocyanate-terminated prepolymers, a thermosetting polymer containing a thermally reversible dynamic thiocarbamate bond is directly prepared, thereby solving the problem that plant oil thermosetting resins cannot be recycled and reprocessed.

[0058] In order to better understand the present invention, the present invention is further specifically described through the following examples, but it should not be understood as limiting the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the above invention content are also considered to fall within the scope of protection of the present invention.

[0059] Example 1: Soybean Oil

[0060] 1. Synthesis of the first type of soybean oil-based recyclable thermosetting resin: At room temperature, 2.5 to 8.0 parts of pentaerythritol tetrakis(thioglycolate) are added to a round-bottom flask with mechanical stirring. Under irradiation with a 365 to 400 nm ultraviolet lamp, 0.3 to 4.5 parts of soybean oil are added dropwise. This process lasts for 0.3 to 1.5 hours. After the addition is completed, the ultraviolet lamp is turned off, and 15.0 to 50.0 parts of THF are added. After the solute is completely dissolved, 2.1 to 7.4 parts of dicyclohexylmethane-4,4'-diisocyanate are added. After stirring evenly, 0.2 to 0.7 parts of N,N-diisopropylethylamine are added dropwise. The mixture is then quickly poured into a mold and cured at 20 to 80°C for 6 to 16 hours to obtain the first type of soybean oil-based recyclable thermosetting resin.

[0061] 2. Synthesis of the second type of soybean oil-based recyclable thermosetting resin: Convert polytetrahydrofuran from a solid state to a liquid state at 40-100°C. Under a nitrogen atmosphere, add 2.3-6.9 parts of polytetrahydrofuran to a 250 mL three-necked flask with mechanical stirring. Raise the temperature to 100-120°C for 2-3 hours, then cool to 45-90°C. Add 0.7-2.6 parts of dicyclohexylmethane-4,4'-diisocyanate and 0.2-0.7 parts of dibutyltin dilaurate. Mechanically stir at 40-100°C for 2-6 hours, cool to 35-65°C, and add 15.0-50.0 parts of THF solvent. At room temperature, 0.4 to 2.3 parts of pentaerythritol tetrakis(thioglycolate) ester are added to a round-bottom flask with mechanical stirring, and 0.3 to 1.4 parts of soybean oil are added dropwise under irradiation of a 365 to 400 nm ultraviolet lamp. This process lasts for 0.3 to 1.5 hours. After the addition is completed, the ultraviolet lamp is turned off, and 10.0 to 50.0 parts of THF solvent are added. After the solute is completely dissolved, it is added to a three-necked flask with mechanical stirring. After stirring evenly, 0.2 to 0.7 parts of N, N-diisopropylethylamine is added dropwise, and then it is quickly poured into a mold and continued to cure at 35 to 65°C for 6 to 16 hours to obtain a second type of soybean oil-based recyclable thermosetting resin.

[0062] Example 2: Olive oil

[0063] 1. Synthesis of the first type of olive oil-based recyclable thermosetting resin: At room temperature, 2.5 to 8.0 parts of pentaerythritol tetrakis(thioglycolate) are added to a round-bottom flask with mechanical stirring. Under irradiation with a 365 to 400 nm ultraviolet lamp, 0.3 to 4.5 parts of olive oil are added dropwise. This process lasts for 0.3 to 1.5 hours. After the addition is completed, the ultraviolet lamp is turned off, and 15.0 to 50.0 parts of THF solvent are added. After the solute is completely dissolved, 2.1 to 7.4 parts of dicyclohexylmethane-4,4'-diisocyanate are added. After stirring evenly, 0.2 to 0.7 parts of N,N-diisopropylethylamine are added dropwise. Then, the mixture is quickly poured into a mold and cured at 20 to 80°C for 6 to 16 hours to obtain the first type of olive oil-based recyclable thermosetting resin.

[0064] 2. Synthesis of the second type of olive oil-based recyclable thermosetting resin: Convert polytetrahydrofuran from a solid state to a liquid state at 40-100°C. Under a nitrogen atmosphere, add 2.3-6.9 parts of polytetrahydrofuran to a 250 mL three-necked flask with mechanical stirring, raise the temperature to 100-120°C and maintain for 2-3 hours, then cool to 45-90°C, add 0.7-2.6 parts of dicyclohexylmethane-4,4'-diisocyanate and 0.2-0.7 parts of dibutyltin dilaurate, mechanically stir at 40-100°C for 2-6 hours, cool to 35-65°C, and add 15.0-50.0 parts of THF solvent. At room temperature, 0.4 to 2.3 parts of pentaerythritol tetrakis(thioglycolate) ester are added to a round-bottom flask with mechanical stirring. Under irradiation with a 365 to 400 nm ultraviolet lamp, 0.3 to 1.4 parts of olive oil are added dropwise at the same time. This process lasts for 0.3 to 1.5 hours. After the addition is completed, the ultraviolet lamp is turned off, and 10.0 to 50.0 parts of THF solvent are added. After the solute is completely dissolved, it is added to a 250 ml three-necked flask with mechanical stirring. After stirring evenly, 0.2 to 0.7 parts of N, N-diisopropylethylamine is added dropwise, and then it is quickly poured into a mold and continued to cure at 35 to 65 ° C for 6 to 16 hours to obtain a second type of olive oil-based recyclable thermosetting resin.

[0065] Example 3: Linseed Oil

[0066] 1. Synthesis of a first-class linseed oil-based recyclable thermosetting resin: 2.5-8.0 parts of pentaerythritol tetrakis(thioglycolate) are added to a round-bottom flask with mechanical stirring at room temperature. 0.3-4.5 parts of linseed oil are simultaneously added dropwise under irradiation with a 365-400 nm ultraviolet lamp. This process is continued for 0.3-1.5 hours. After the addition is completed, the ultraviolet lamp is turned off, and 15.0-50.0 parts of THF solvent are added. After the solute is completely dissolved, 2.1-7.4 parts of dicyclohexylmethane-4,4'-diisocyanate are added. After stirring, 0.2-0.7 parts of N,N-diisopropylethylamine are added dropwise. The mixture is then rapidly poured into a mold and cured at 20-80° C. for 6-16 hours to obtain the first-class linseed oil-based recyclable thermosetting resin.

[0067] 2. Synthesis of the second type of linseed oil-based recyclable thermosetting resin: Convert polytetrahydrofuran from a solid state to a liquid state at 40-100°C. Under a nitrogen atmosphere, add 2.3-6.9 parts of polytetrahydrofuran to a 250 mL three-necked flask with mechanical stirring. Raise the temperature to 100-120°C for 2-3 hours, then cool to 45-90°C. Add 0.7-2.6 parts of dicyclohexylmethane-4,4'-diisocyanate and 0.2-0.7 parts of dibutyltin dilaurate. Mechanically stir at 40-100°C for 2-6 hours, cool to 35-65°C, and add 15.0-50.0 parts of THF solvent. At room temperature, 0.4 to 2.3 parts of pentaerythritol tetrakis(thioglycolate) are added to a round-bottom flask with a mechanical stirrer. Under irradiation with a 365-400 nm ultraviolet lamp, 0.3 to 1.4 parts of linseed oil are simultaneously added dropwise. This process lasts for 0.3 to 1.5 hours. After the addition is completed, the ultraviolet lamp is turned off, and 10.0 to 50.0 parts of THF solvent are added. After the solute is completely dissolved, the solvent is added to a 250 ml three-necked flask with a mechanical stirrer. After stirring evenly, 0.2 to 0.7 parts of N,N-diisopropylethylamine is added dropwise. The resin is then quickly poured into a mold and cured at 35 to 65° C. for 6 to 16 hours to obtain a second type of linseed oil-based recyclable thermosetting resin.

[0068] Example 4: Cottonseed Oil

[0069] 1. Synthesis of the first type of cottonseed oil-based recyclable thermosetting resin: At room temperature, 2.5 to 8.0 parts of pentaerythritol tetrakis(thioglycolate) are added to a round-bottom flask with mechanical stirring. Under irradiation with a 365 to 400 nm ultraviolet lamp, 0.3 to 4.5 parts of cottonseed oil are added dropwise. This process lasts for 0.3 to 1.5 hours. After the addition is completed, the ultraviolet lamp is turned off, and 15.0 to 50.0 parts of THF solvent are added. After the solute is completely dissolved, 2.1 to 7.4 parts of dicyclohexylmethane-4,4'-diisocyanate are added. After stirring evenly, 0.2 to 0.7 parts of N,N-diisopropylethylamine are added dropwise. The resin is then quickly poured into a mold and cured at 20 to 80°C for 6 to 16 hours to obtain the first type of cottonseed oil-based recyclable thermosetting resin.

[0070] 2. Synthesis of the second type of cottonseed oil-based recyclable thermosetting resin: Polytetrahydrofuran is converted from a solid state to a liquid state at 40-100°C. Under a nitrogen atmosphere, 2.3-6.9 parts of polytetrahydrofuran are added to a 250 mL three-necked flask with mechanical stirring. The temperature is raised to 100-120°C and maintained for 2-3 hours. The temperature is then lowered to 45-90°C. 0.7-2.6 parts of dicyclohexylmethane-4,4'-diisocyanate and 0.2-0.7 parts of dibutyltin dilaurate are added. The mixture is mechanically stirred at 40-100°C for 2-6 hours, cooled to 35-65°C, and 15.0-50.0 parts of THF solvent are added. At room temperature, 0.4 to 2.3 parts of pentaerythritol tetrakis(thioglycolate) ester are added to a round-bottom flask with mechanical stirring, and 0.3 to 1.4 parts of cottonseed oil are added dropwise under irradiation of a 365 to 400 nm ultraviolet lamp. This process lasts for 0.3 to 1.5 hours. After the addition is completed, the ultraviolet lamp is turned off, and 10.0 to 50.0 parts of THF solvent are added. After the solute is completely dissolved, it is added to a 250 ml three-necked flask with mechanical stirring. After stirring evenly, 0.2 to 0.7 parts of N, N-diisopropylethylamine is added dropwise, and then it is quickly poured into a mold and continued to cure at 35 to 65 ° C for 6 to 16 hours to obtain a second type of cottonseed oil-based recyclable thermosetting resin.

[0071] Example 5: Corn Oil

[0072] 1. Synthesis of the first type of corn oil-based recyclable thermosetting resin: At room temperature, 2.5 to 8.0 parts of pentaerythritol tetrakis(thioglycolate) are added to a round-bottom flask with mechanical stirring. Under irradiation with a 365 to 400 nm ultraviolet lamp, 0.3 to 4.5 parts of corn oil are added dropwise. This process lasts for 0.3 to 1.5 hours. After the addition is completed, the ultraviolet lamp is turned off, and 15.0 to 50.0 parts of THF solvent are added. After the solute is completely dissolved, 2.1 to 7.4 parts of dicyclohexylmethane-4,4'-diisocyanate are added. After stirring evenly, 0.2 to 0.7 parts of N,N-diisopropylethylamine are added dropwise. Then, the mixture is quickly poured into a mold and continued to cure at 20 to 80°C for 6 to 16 hours to obtain the first type of corn oil-based recyclable thermosetting resin.

[0073] 2. Synthesis of the second type of corn oil-based recyclable thermosetting resin: Convert polytetrahydrofuran from a solid state to a liquid state at 40-100°C. Under a nitrogen atmosphere, add 2.3-6.9 parts of polytetrahydrofuran to a 250 mL three-necked flask with mechanical stirring. Raise the temperature to 100-120°C for 2-3 hours, then cool to 45-90°C. Add 0.7-2.6 parts of dicyclohexylmethane-4,4'-diisocyanate and 0.2-0.7 parts of dibutyltin dilaurate. Mechanically stir at 40-100°C for 2-6 hours, cool to 35-65°C, and add 15.0-50.0 parts of THF solvent. At room temperature, 0.4 to 2.3 parts of pentaerythritol tetrakis(thioglycolate) ester are added to a round-bottom flask with mechanical stirring. Under irradiation with a 365 to 400 nm ultraviolet lamp, 0.3 to 1.4 parts of corn oil are added dropwise at the same time. This process lasts for 0.3 to 1.5 hours. After the addition is completed, the ultraviolet lamp is turned off, and 10.0 to 50.0 parts of THF solvent are added. After the solute is completely dissolved, it is added to a 250 ml three-necked flask with mechanical stirring. After stirring evenly, 0.2 to 0.7 parts of N, N-diisopropylethylamine is added dropwise, and then it is quickly poured into a mold and continued to cure at 35 to 65 ° C for 6 to 16 hours to obtain a second type of corn oil-based recyclable thermosetting resin.

[0074] Example 6: Tung Oil

[0075] 1. Synthesis of the first type of tung oil-based recyclable thermosetting resin: At room temperature, 2.5 to 8.0 parts of pentaerythritol tetrakis(thioglycolate) are added to a round-bottom flask with mechanical stirring. Under irradiation with a 365-400 nm ultraviolet lamp, 0.3 to 4.5 parts of tung oil are added dropwise. This process lasts for 0.3 to 1.5 hours. After the addition is completed, the ultraviolet lamp is turned off, and 15.0 to 50.0 parts of THF solvent are added. After the solute is completely dissolved, 2.1 to 7.4 parts of dicyclohexylmethane-4,4'-diisocyanate are added. After stirring evenly, 0.2 to 0.7 parts of N,N-diisopropylethylamine are added dropwise. The mixture is then quickly poured into a mold and cured at 20 to 40 to 100° C. for 6 to 16 hours to obtain the first type of tung oil-based recyclable thermosetting resin.

[0076] 2. Synthesis of the second type of tung oil-based recyclable thermosetting resin: Convert polytetrahydrofuran (PTHF) from a solid state to a liquid state at 40-100°C. Under a nitrogen atmosphere, add 2.3-6.9 parts of PTHF to a 250mL three-necked flask with mechanical stirring. Raise the temperature to 100-120°C for 2-3 hours, then cool to 45-90°C. Add 0.7-2.6 parts of dicyclohexylmethane-4,4'-diisocyanate and 0.2-0.7 parts of dibutyltin dilaurate. Mechanically stir at 40-100°C for 2-6 hours, cool to 35-65°C, and add 15.0-50.0 parts of THF solvent. At room temperature, 0.4 to 2.3 parts of pentaerythritol tetrakis(thioglycolate) ester are added to a round-bottom flask with mechanical stirring. Under irradiation with a 365 to 400 nm ultraviolet lamp, 0.3 to 1.4 parts of tung oil are added dropwise at the same time. This process lasts for 0.3 to 1.5 hours. After the addition is completed, the ultraviolet lamp is turned off, and 10.0 to 50.0 parts of THF solvent are added. After the solute is completely dissolved, it is added to a 250 ml three-necked flask with mechanical stirring. After stirring evenly, 0.2 to 0.7 parts of N, N-diisopropylethylamine is added dropwise, and then it is quickly poured into a mold and continued to cure at 35 to 65 ° C for 6 to 16 hours to obtain a second type of tung oil-based recyclable thermosetting resin.

[0077] Example 7:

[0078] The solid state of polytetrahydrofuran is converted into a liquid state at 40-100°C. Under a nitrogen atmosphere, 2.3-6.9 parts of polytetrahydrofuran are added to a 250 mL three-necked flask with mechanical stirring, the temperature is raised to 100-120°C and maintained for 2 hours, then the temperature is lowered to 40-100°C, 0.7-2.6 parts of TXMDI tetramethyl-m-xylylene diisocyanate and 0.2-0.7 parts of dibutyltin dilaurate are added, the mixture is mechanically stirred at 40-100°C for 2-6 hours, the temperature is lowered to 35-65°C, and 15.0-50.0 parts of THF solvent are added. At room temperature, 0.4 to 2.3 parts of pentaerythritol tetrakis(thioglycolate) ester are added to a round-bottom flask with mechanical stirring, and 0.3 to 1.4 parts of soybean oil are added dropwise under irradiation of a 365 to 400 nm ultraviolet lamp. This process lasts for 0.3 to 1.5 hours. After the addition is completed, the ultraviolet lamp is turned off, and 10.0 to 50.0 parts of THF solvent are added. After the solute is completely dissolved, it is added to a 250 ml three-necked flask with mechanical stirring. After stirring evenly, 0.2 to 0.7 parts of N, N-diisopropylethylamine is added dropwise, and then it is quickly poured into a mold and continued to cure at 35 to 65 ° C for 6 to 16 hours to obtain a second type of soybean oil-based recyclable thermosetting resin.

[0079] Example 8:

[0080] At 40-100°C, polytetrahydrofuran is converted from a solid state to a liquid state. Under a nitrogen atmosphere, 2.3-6.9 parts of polytetrahydrofuran are added to a 250 mL three-necked flask with mechanical stirring, the temperature is raised to 100-120°C and maintained for 2 hours, then the temperature is lowered to 40-100°C, 0.7-2.6 parts of IPDI isophorone diisocyanate and 0.2-0.7 parts of dibutyltin dilaurate are added, the mixture is mechanically stirred at 40-100°C for 2-6 hours, the temperature is lowered to 35-65°C, and 15.0-50.0 parts of THF solvent are added. At room temperature, 0.4 to 2.3 parts of pentaerythritol tetrakis(thioglycolate) ester are added to a round-bottom flask with mechanical stirring, and 0.3 to 1.4 parts of soybean oil are added dropwise under irradiation of a 365 to 400 nm ultraviolet lamp. This process lasts for 0.3 to 1.5 hours. After the addition is completed, the ultraviolet lamp is turned off, and 10.0 to 50.0 parts of THF solvent are added. After the solute is completely dissolved, it is added to a 250 ml three-necked flask with mechanical stirring. After stirring evenly, 0.2 to 0.7 parts of N, N-diisopropylethylamine is added dropwise, and then it is quickly poured into a mold and continued to cure at 35 to 65 ° C for 6 to 16 hours to obtain a second type of soybean oil-based recyclable thermosetting resin.

[0081] Example 9:

[0082] At 40-100°C, polytetrahydrofuran is converted from a solid state to a liquid state. Under a nitrogen atmosphere, 2.3-6.9 parts of polytetrahydrofuran are added to a 250 mL three-necked flask with mechanical stirring, the temperature is raised to 100-120°C and maintained for 2 hours, then the temperature is lowered to 40-100°C, 0.7-2.6 parts of tri-HDI hexamethylene diisocyanate isocyanate trimer and 0.2-0.7 parts of dibutyltin dilaurate are added, the mixture is mechanically stirred at 40-100°C for 2-6 hours, the temperature is lowered to 35-65°C, and 15.0-50.0 parts of THF solvent are added. At room temperature, 0.4 to 2.3 parts of pentaerythritol tetrakis(thioglycolate) ester are added to a round-bottom flask with mechanical stirring, and 0.3 to 1.4 parts of soybean oil are added dropwise under irradiation of a 365 to 400 nm ultraviolet lamp. This process lasts for 0.3 to 1.5 hours. After the addition is completed, the ultraviolet lamp is turned off, and 10.0 to 50.0 parts of THF solvent are added. After the solute is completely dissolved, it is added to a 250 ml three-necked flask with mechanical stirring. After stirring evenly, 0.2 to 0.7 parts of N, N-diisopropylethylamine is added dropwise, and then it is quickly poured into a mold and continued to cure at 35 to 65 ° C for 6 to 16 hours to obtain a second type of soybean oil-based recyclable thermosetting resin.

[0083] Example 10:

[0084] At 40-100°C, polytetrahydrofuran is converted from a solid state to a liquid state. Under a nitrogen atmosphere, 2.3-6.9 parts of polytetrahydrofuran are added to a 250 mL three-necked flask with mechanical stirring, the temperature is raised to 100-120°C and maintained for 2 hours, then the temperature is lowered to 40-100°C, 0.7-2.6 parts of hexamethylene diisocyanate (HDI) and 0.2-0.7 parts of dibutyltin dilaurate are added, the mixture is mechanically stirred at 40-100°C for 2-6 hours, the temperature is lowered to 35-65°C, and 15.0-50.0 parts of THF solvent are added. At room temperature, 0.4 to 2.3 parts of pentaerythritol tetrakis(thioglycolate) ester are added to a round-bottom flask with mechanical stirring, and 0.3 to 1.4 parts of soybean oil are added dropwise under irradiation of a 365 to 400 nm ultraviolet lamp. This process lasts for 0.3 to 1.5 hours. After the addition is completed, the ultraviolet lamp is turned off, and 10.0 to 50.0 parts of THF solvent are added. After the solute is completely dissolved, it is added to a 250 ml three-necked flask with mechanical stirring. After stirring evenly, 0.2 to 0.7 parts of N, N-diisopropylethylamine is added dropwise, and then it is quickly poured into a mold and continued to cure at 35 to 65 ° C for 6 to 16 hours to obtain a second type of soybean oil-based recyclable thermosetting resin.

[0085] In order to further demonstrate the beneficial effects of the present invention and to better understand the present invention, the properties and application performance of the plant oil-based recyclable thermosetting resin and the preparation method thereof disclosed in the present invention are further illustrated by the following tests, but they should not be understood as limiting the present invention. The properties of the methods obtained by other measurement experiments conducted by those skilled in the art based on the above-mentioned invention content and the applications based on the above-mentioned properties are also considered to fall within the scope of protection of the present invention.

[0086] Test 1: Mechanical properties test

[0087] The polymer splines prepared in Examples 1-10 were made into dumbbell-shaped splines (l = 25 mm; b = 2 mm; h = 0.2 mm) for mechanical property testing. The tensile strength was calculated as follows:

[0088] σ=F / (b·l)

[0089] Where: F, the maximum load of the specimen in tensile failure; b, the width of the specimen butt joint surface; l, the length of the specimen butt joint surface.

[0090] The results are shown in Table 1-2. It can be seen that the breaking strength, elongation at break and elastic modulus of both the first type of vegetable oil-based recyclable thermosetting resin and the second type of vegetable oil-based recyclable thermosetting resin have met the performance requirements of thermosetting resins. It is worth noting that the second type of vegetable oil-based recyclable thermosetting resin exceeds the performance requirements of thermosetting resins.

[0091] Test 2: Recycling performance test

[0092] The polymers prepared in Examples 1-10 were cut into pieces and re-hot-pressed at 40-100° C. and 5 MPa for 0.3-1.5 h, and the polymers were re-molded.

[0093] The recovery efficiency is defined as the ratio of the tensile strength, elongation at break, or elastic modulus of the repaired specimen to that of the original specimen:

[0094] η=σ recycled / σ virgin Or η=ε recycled / ε virgin Or η=E recycled / E virgin

[0095] Where:

[0096] The test results are shown in Table 1-2. It can be seen that the polymers containing thiocarbamate bond structures (Examples 1 to 10) can be reshaped by shearing and hot pressing, and the mechanical strength is comparable to that of the original material, and the recycling efficiency is high.

[0097] Table 1 Mechanical properties and recyclability of the first type of vegetable oil-based thermosetting resin

[0098]

[0099] Table 2 Mechanical properties and recyclability of the second type of vegetable oil-based thermosetting resin

[0100]

[0101]

[0102] Test 3

[0103] The structures of the second type of soybean oil-based recyclable thermosetting resins obtained in Examples 1, 7, and 8 were characterized. Figure 1 The Fourier transform infrared spectrum FT-IR shows the stretching vibration peak of the isocyanate group (2260-2280 cm -1 ) disappears, indicating that the raw materials have reacted completely and the material has been successfully synthesized.

[0104] The performance of the second type of soybean oil-based recyclable thermosetting resin obtained in Examples 1, 7, and 8 was tested. Figure 2 Schematic diagram of differential scanning calorimetry (DSC) curve. It can be seen that the glass transition temperature is -35°C, indicating that the product has a good high elastic state at room temperature. Figure 3 Schematic diagram of glass transition temperature. It can be seen that the mass of the product changes at 300°C, indicating that the product has good thermodynamic stability.

[0105] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing a vegetable oil-based recyclable thermosetting resin, characterized in that: The multi-reaction site modification of vegetable oils is achieved by a UV-light click reaction of polythiol ester thiols with vegetable oils; the resulting modified vegetable oil is then reacted with an isocyanate monomer to obtain a first type of vegetable oil-based recyclable thermosetting resin, or is polymerized with an isocyanate-terminated prepolymer to obtain a second type of vegetable oil-based recyclable thermosetting resin; Specifically, first, under ultraviolet light, vegetable oil is added dropwise to the polythiol ester thiol, and after the addition is completed, the ultraviolet light is turned off to obtain thiolated vegetable oil; Then, an organic solvent is added to dissolve the thiolated vegetable oil, and a diisocyanate monomer and a catalyst are added to the mixed solution, and the mixture is cured at 20-80° C. to obtain the first type of vegetable oil-based recyclable thermosetting resin; or, After adding an organic solvent to dissolve the thiolated vegetable oil, an isocyanate-terminated prepolymer and a catalyst are added to the mixed solution, and the mixture is cured at 35-65°C to obtain the second type of vegetable oil-based recyclable thermosetting resin.

2. The preparation method according to claim 1, characterized in that The preparation method of the isocyanate-terminated prepolymer comprises: converting a diol or diamine polymer from a solid state to a liquid state at 40-100°C; adding the diol or diamine polymer to a three-necked flask with mechanical stirring under a nitrogen atmosphere, heating the flask to 100-120°C for 2-3 hours, then cooling the flask to 45-90°C, adding a diisocyanate monomer and dibutyltin dilaurate, mechanically stirring the flask at 40-100°C for 2-6 hours, cooling the flask to 35-65°C, and adding an organic solvent.

3. The preparation method according to claim 2, characterized in that The diol or diamine polymer includes polytetramethylene glycol, polyetheramine or polycaprolactone diol.

4. The preparation method according to claim 1, characterized in that The polythiol ester thiol is one of pentaerythritol tetrakis(thioglycolate) ester PETMA, pentaerythritol tetrakis(3-mercaptopropionate) ester PETMP, trimethylolpropane tris(2-mercaptoacetate) TMPMA, trimethylolpropane tris(3-mercaptopropionate) TMPMP, and dipentaerythritol hexa(3-mercaptopropionate) ester DI-PETMP; the vegetable oil includes soybean oil, olive oil, linseed oil, castor oil, cottonseed oil, tung oil, peanut oil, corn oil, rapeseed oil or palm oil; the catalyst includes N,N-diisopropylethylamine DIPEA, 4-dimethylaminopyridine DMAP, 1,8-diazabicyclo[5.4.0]undec-7-ene DBU, triethylamine TEA or dibutyltin dilaurate DBTDL; and the organic solvent includes one or more of methanol, ethanol, propanol, acetone, dioxane, tetrahydrofuran, methyl ethyl ketone, n-butanol, and ethyl acetate.

5. The preparation method according to claim 1, characterized in that The diisocyanate monomer includes 4,4'-dicyclohexylmethane diisocyanate HMDI, tetramethyl-m-xylylene diisocyanate TMXDI, isophorone diisocyanate IPDI, hexamethylene diisocyanate HDI, diphenylmethane diisocyanate MDI, toluene diisocyanate TDI or m-xylylene diisocyanate XDI.

6. The vegetable oil-based recyclable thermosetting resin prepared by the preparation method according to claim 1.

7. The vegetable oil-based recyclable thermosetting resin according to claim 6, characterized in that The first type of vegetable oil-based recyclable thermosetting resin comprises 2.5 to 8.0 parts of polythiol ester mercaptan, 0.3 to 4.5 parts of vegetable oil, 2.1 to 7.4 parts of diisocyanate monomer, and 0.2 to 0.7 parts of catalyst; The second type of vegetable oil-based recyclable thermosetting resin comprises raw materials of 0.4-5.3 parts of polythiol ester mercaptan, 0.3-7.4 parts of vegetable oil, 4.3-79.9 parts of isocyanate-terminated prepolymer and 0.2-0.7 parts of catalyst.

8. The use of the vegetable oil-based recyclable thermosetting resin according to claim 6, wherein: Application of the vegetable oil-based recyclable thermosetting resin in thermoreversible self-healing materials.

9. The use according to claim 8, characterized in that The plant oil-based recyclable thermosetting resin is used in the preparation of packaging materials, biomedical devices, 3D printing materials, automotive parts, coatings and adhesive materials.

Images