Furyl polyurethane material containing Diels-Alder structure as well as preparation method and application of furyl polyurethane material

Abstract

The invention provides a preparation method of a furyl polyurethane material containing a Diels-Alder structure, the furyl polyurethane material and application of the furyl polyurethane material in 3D printing. The preparation method comprises the following steps: carrying out amidation reaction on furanmethyl ester and diethanol amine to generate a furyl polyamide monomer; the furyl polyamide monomer and a polyisocyanate compound are subjected to an amine-alcohol reaction to generate a furyl polyurethane monomer; and the furyl polyurethane monomer and a bismaleimide compound are subjected to a Diels-Alder addition reaction, such that the furyl polyurethane material containing the Diels-Alder structure is obtained.

Description

Technical Field

[0001] This application relates to the development and preparation technology of 3D printing materials, and particularly to a furanyl polyurethane material containing a Diels-Alder structure, its preparation method and its application. Background Art

[0002] In the current 3D printing field, especially in the Fused Filament Fabrication / Fused Deposition Modeling (FFF / FDM) printing technology, poor interlayer adhesion is an important problem. The FFF / FDM technology is a 3D printing process that uses a continuous thermoplastic material wire. The wire is fed from a spool through a moving heated printer extruder head and deposited on the growing workpiece. The print head moves under computer control to define the printed shape; the head moves in two dimensions, depositing one horizontal plane or layer at a time; then the workpiece or the print head is moved vertically a small amount to start printing a new layer. In this technology, the surface tension between layers can affect the appearance and strength of the printed object, and poor interfacial diffusion results in less interlayer chain entanglement and poor interlayer adhesion. When the thermoplastic material is heated and extruded onto the modeling platform, each layer cools and solidifies quickly. This rapid cooling causes an increase in the surface tension between layers, which in turn leads to poor adhesion or cracks between layers. Two effective methods to improve the interlayer bonding strength of 3D printing materials include reducing the temperature gradient between the deposition layer interfaces (promoting the mutual diffusion and re-entanglement of polymer chains at the interface) and introducing chemical bonds between the deposition layer interfaces.

[0003] Currently, the most common means to improve the interlayer bonding force of printed parts is to promote the polymer healing between layers by controlling the printing process, such as optimizing printing parameters, local heating of printed parts, surface treatment (annealing) of printed parts, adding inorganic fillers, organic additives that reduce melt viscosity, and alternating printing of materials. However, these means usually result in a significant increase in equipment and process costs, and the improvement of the Z-axis interlayer strength is also relatively limited. Summary of the Invention

[0004] This application designs a series of polymers with a controllable Diels-Alder structure. After being compounded with 3D printing wires, it solves the technical problem of poor interlayer bonding strength of FFF / FDM printed parts and expands the application scope of this technology.

[0005] This application provides a preparation method of a furanyl polyurethane material with a Diels-Alder structure, this furanyl polyurethane material and its application in 3D printing.

[0006] Therefore, the embodiments of this application adopt the following technical solutions.

[0007] In a first aspect, an embodiment of the present application provides a method for preparing a furanyl polyurethane material containing a Diels-Alder structure, characterized in that an amideification reaction is carried out between a furan methyl ester raw material and a diethanolamine raw material to generate a furanyl polyamide monomer; an amino-alcohol reaction is carried out between the furanyl polyamide monomer and a polyisocyanate compound raw material to generate a furanyl polyurethane monomer; and a Diels-Alder addition reaction is carried out between the furanyl polyurethane monomer and a bismaleimide compound raw material to obtain the furanyl polyurethane material containing a Diels-Alder structure.

[0008] In some embodiments, using the furan methyl ester, the diethanolamine, and the polyisocyanate compound as raw materials in the same container, the amideification reaction and the amino-alcohol reaction are carried out in sequence to obtain the furanyl polyurethane monomer.

[0009] In some embodiments, the amideification reaction is carried out under vacuum conditions and in the presence of a catalyst.

[0010] In some embodiments, the amino-alcohol reaction is carried out under an inert gas atmosphere and in the presence of a catalyst.

[0011] In some embodiments, the Diels-Alder addition reaction is carried out during a wire extrusion process.

[0012] In some embodiments, in the amideification reaction, the molar ratio of the furan methyl ester raw material to the diethanolamine raw material is 0.5 - 2.

[0013] In some embodiments, the catalyst includes at least one of sodium hydroxide, potassium hydroxide, or triethanolamine.

[0014] In some embodiments, the reaction temperature of the amideification reaction is 30 - 150 °C, and its reaction time is 0.5 - 24 h.

[0015] In some embodiments, the reaction temperature of the amideification reaction is 60 - 120 °C.

[0016] In some embodiments, the polyisocyanate compound includes at least one of naphthalene diisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate, hexamethylene diisocyanate, hexamethylene diisocyanate, o-tolidine diisocyanate, xylene diisocyanate, isophorone diisocyanate, trimethylhexane diisocyanate, m-xylylene diisocyanate, toluene 2,6-diisocyanate, triphenylmethane triisocyanate, or triisocyanate (methyl)silane.

[0017] In some embodiments, the molar ratio of the hydroxyl groups contained in the furanyl polyamide monomer to the isocyanate groups in the polyisocyanate compound is 0.5 - 2.

[0018] In some embodiments, the inert gas atmosphere includes at least one of nitrogen, helium, or argon.

[0019] In some embodiments, the catalyst includes at least one of dimethyltin stannate, dibutyltin stannate, or butyllithium.

[0020] In some embodiments, the reaction temperature of the amine - alcohol reaction is 30 - 80 °C, and the reaction time is 2 - 12 h.

[0021] In some embodiments, the bismaleimide compounds include at least one of bismaleimide, diphenyl ether bismaleimide, bismaleimide - methyl ether, bismaleimide - hexapolyethylene glycol, N,N-(1,4 - phenylene) bismaleimide, N-(4 - methyl - 1,3 - phenylene) bismaleimide, 1,10 - bis(maleimide) decane, 1,2 - bis(maleimide) ethane, or N - hydroxysuccinimide 3 - maleimide propionate.

[0022] In some embodiments, in the Diels - Alder addition reaction, the mass ratio of the furanyl polyurethane monomer to the bismaleimide compound is 0.5 - 1.5.

[0023] In some embodiments, in the wire extrusion process, the furanyl polyurethane monomer, the bismaleimide compound, and at least one additive are used, where the additive includes a compatibilizer, a plasticizer, or any combination thereof, and the furanyl polyurethane monomer and the bismaleimide compound account for a mass ratio of 5 - 25%.

[0024] In some embodiments, the wire extrusion process includes at least one of a single - screw processing process or a twin - screw processing process, the processing temperature is 160 - 250 °C, and the processing time is 10 - 60 min.

[0025] In a second aspect, embodiments of the present application provide a furanyl polyurethane material containing a Diels - Alder structure, characterized in that the furanyl polyurethane material is prepared according to the first aspect.

[0026] In some embodiments, the furanyl polyurethane material contains a furanyl polyurethane monomer having a structure of chemical formula (I):

[0027]

[0028] wherein R is any one of the following groups, or its derivative structure:

[0029]

[0030] R1 is any one of the following groups, or its derivative structure:

[0031]

[0032] In a third aspect, the embodiments of the present application provide a use of a furyl polyurethane material containing a Diels - Alder structure in the field of extrusion 3D printing, characterized in that the furyl polyurethane material is prepared according to the first aspect, and the furyl polyurethane material is used to be added to 3D printing filaments to improve the interlayer strength.

[0033] The present application uses furfuryl methyl ester, diethanolamine and polyisocyanate compounds as the main raw materials, based on a "one - pot" reaction system, to synthesize a furyl polyurethane monomer, and then performs a "Diels - Alder addition reaction" with bismaleimide compounds to synthesize a bio - based polyurethane material, and uses it in the field of 3D printing filaments. In addition, the present application uses dynamic covalent chemistry functions to solve the problem of long - filament adhesion of 3D printing filaments at the molecular level. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the technical solutions in the embodiments of this specification, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of this specification. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0035] Figure 1 It is the infrared spectrum of the furyl polyurethane monomer provided by some embodiments of the present application;

[0036] Figure 2 It is the flow chart of the preparation method of the furyl polyurethane material containing a Diels - Alder structure provided by some embodiments of the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0037] The following description provides specific application scenarios and requirements of this specification, aiming to enable those skilled in the art to manufacture and use the content in this specification. For those skilled in the art, various partial modifications to the disclosed embodiments are obvious, and the general principles defined here can be applied to other embodiments and applications without departing from the spirit and scope of this specification. Therefore, this specification is not limited to the disclosed embodiments, but has the broadest scope consistent with the claims.

[0038] The terms used herein are for the purpose of describing particular example embodiments only and are not limiting. For example, unless the context clearly dictates otherwise, as used herein, the singular forms "a", "an" and "the" may also include the plural forms. When used in this specification, the terms "comprising", "including" and / or "containing" mean that the associated integers, steps, operations, elements and / or components are present, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups in the system / method.

[0039] In this application, the expression "X includes at least one of A, B, or C" means that X includes at least A, or X includes at least B, or X includes at least C. That is, X can include only any combination of A, B, and C, or can include any combination of A, B, and C as well as other possible contents / elements at the same time. Any combination of A, B, and C can be A, B, C, AB, AC, BC, or ABC.

[0040] In this application, unless otherwise clearly stated, the associated relationship generated between structures can be a direct associated relationship or an indirect associated relationship. For example, when describing "A is connected to B", unless it is clearly stated that A is directly connected to B, it should be understood that A can be directly connected to B or can be indirectly connected to B; for another example, when describing "A is above B", unless it is clearly stated that A is directly above B (A and B are adjacent and A is above B), it should be understood that A can be directly above B or A can be indirectly above B (there are other elements between A and B and A is above B). And so on.

[0041] In view of the following description, these features and other features of this specification, as well as the operations and functions of the related elements of the structure, and the combination and manufacturing economy of the components can be significantly improved. The description also includes all the graphics and text in all the reference drawings in this specification, and all of these form a part of this specification. However, it should be clearly understood that the drawings are only for the purpose of illustration and description and are not intended to limit the scope of this specification. It should also be understood that the drawings are not drawn to scale.

[0042] Polyurethane can be used as a surfactant to reduce the surface tension of the fluid, improve the wettability and spreadability of the liquid, and can also form physical crosslinks or chemical crosslinks between the layers of the printed part, thereby enhancing the interlayer bonding.

[0043] On the other hand, using renewable resources to replace traditional non-renewable petrochemical resources as raw materials for preparing polymer materials has gradually become a research hotspot in many fields including 3D printing technology. The carbon sources or precursors of furan-based compounds can come from biomass or biological raw materials. These compounds have bio-renewability and environmental friendliness, and thus have attracted much attention in the fields of sustainable development and green chemistry. Based on the chemical derivatization of renewable resources, self-healing properties, the preparation of polymers containing reversible dynamic covalent bonds and their application in new fields can integrate some advantages of thermoplastic and thermosetting resins, and conform to the principles of sustainable development, interdisciplinary industry intersection and high-value utilization of materials.

[0044] In view of this, the present application relates to a development and preparation technology of a material containing a Diels-Alder structure (reversible dynamic covalent bond), specifically to a preparation method of a polyurethane material with "self-healing performance" and its use in 3D printing materials, belonging to the technical field of polymer synthesis and functional application.

[0045] In the present application, by designing a series of polymers with a controllable Diels-Alder structure and compounding them with 3D printing filaments, the technical problem of poor interlayer bonding strength of FFF / FDM printed parts is solved, and the application scope of this technology is expanded. Specifically, the present application provides a preparation method of a furan-based polyurethane material with a Diels-Alder structure, this furan-based polyurethane material and its application in 3D printing.

[0046] Specifically, to solve the above problems in 3D printing, especially in the FFF / FDM process, the adhesion problem of filaments can be solved at the molecular level by using dynamic covalent chemistry functions (enhancing the interlayer through chemical reactions). Dynamic covalent chemistry uses reversible covalent bonds to form complex but thermodynamically stable network systems, that is, introducing (weak) covalent chemical bonds as an additional source of interlayer strength. According to the present application, the interlayer strength can be increased by 50 - 200% without losing other properties of the material, removing the limitation of the generally weak interlayer bonding force of FFF / FDM printed parts on the practical application of this technology.

[0047] The present application provides a preparation method of a furan-based polyurethane material containing a Diels-Alder structure. In the present application, furan methyl ester, diethanolamine and polyisocyanate compounds are used as main raw materials, and based on a "one-pot" reaction system, a polyurethane material is synthesized by successively adopting "amidation reaction", "amine-alcohol reaction" and "Diels-Alder addition reaction". Specifically, in the preparation method of the present application, first, the furan methyl ester raw material and the diethanolamine raw material are subjected to an amidation reaction to generate a furan-based polyamide monomer.

[0048] Furan (oxole) is a heterocyclic organic compound, and its five-membered aromatic ring has four carbon atoms and one oxygen atom. Compounds with a furan ring (such as methyl furoate) are its homologues. Methyl furoate, with the chemical formula C5H4O2, is an organic compound belonging to the ester class. Its molecular structure contains a furan ring (a five-membered heterocyclic ring containing one oxygen atom) and a formyl group (-COOCH3). That is, it is formed by replacing a hydrogen atom on the furan ring with a formyl group. Methyl furoate is a colorless liquid. Methyl furoate is selected as the main raw material for this preparation method. An important reason is that the carbon source or precursor of furan-based compounds can come from biomass or biological raw materials, and these compounds have biological renewability and environmental friendliness.

[0049] The furan-based compounds such as methyl furoate in this application can be obtained by biological materials / biological methods, have the advantage of biodegradation, and are environmentally friendly. There are mainly two ways to obtain furan-based compounds by biological methods: 1) Microbial synthesis. Microorganisms have the ability to synthesize various furan-based compounds. A variety of microorganisms can synthesize furan rings, including fungi, bacteria, actinomycetes, etc. These microorganisms can synthesize furan-based compounds through various pathways, including: Synthesis from monosaccharides: Microorganisms can use monosaccharides as carbon sources and synthesize furan rings through enzymatic reactions. Synthesis from amino acids: Microorganisms can use amino acids as carbon sources and synthesize furan rings through enzymatic reactions. Synthesis from fatty acids: Microorganisms can use fatty acids as carbon sources and synthesize furan rings through enzymatic reactions. 2) Enzyme-catalyzed synthesis. Enzyme-catalyzed synthesis is an efficient and green method. In recent years, various reaction systems for enzyme-catalyzed synthesis of furan-based compounds have been developed. For example, a reaction system for catalyzing the oxidation of aldehydes to synthesize furan rings using aldehyde oxidase. In addition to being environmentally friendly, obtaining furan-based compounds by biological methods also has many advantages, such as wide raw material sources: Microorganisms can use a variety of carbon sources as raw materials, including monosaccharides, amino acids, fatty acids, etc. Mild reaction conditions: Biosynthesis reactions are usually carried out at normal temperature and pressure without the use of toxic and harmful chemical reagents. The raw materials such as methyl furoate used in this application have the above-mentioned many advantages.

[0050] It should be noted that the methyl furoate raw material used in this application can be a methyl furoate compound, or a substance or raw material containing methyl furoate, and the methyl furoate therein is suitable as a raw material for this amidation reaction to obtain furan-based polyamide monomers. That is to say, the methyl furoate raw material may contain some other components or impurities, as long as their presence does not affect the upcoming amidation reaction and can obtain usable furan-based polyamide monomers.

[0051] Specifically, the furan methyl ester raw material can be at least one of methyl 2-furoate, butyl furan-2-carboxylate, methyl 3-furoate, methyl 3-furanacetate, propyl 2-furoate, methyl 2-furoylacetate, methyl 2-(furan-3-yl)acetate, methyl N-(2-furyl)glycinate, methyl 3-methyl-2-furoate, methyl 5-methyl-3-furoate, methyl 5-methyl-2-furoate, methyl 5-phenylfuran-2-carboxylate, or methyl 2-amino-2-furoacetate. The above are only some examples of the furan methyl ester raw materials. Those skilled in the art should know that any combination thereof or a combination with other substances can also be used in this application.

[0052] Another reactant for the amidation reaction is the diethanolamine raw material. Diethanolamine, with the chemical formula HN(CH2CH2OH)2, is a secondary amine and a diol. As a secondary amine and a diol, diethanolamine has many uses in organic synthesis. Similar to other amine compounds, diethanolamine is weakly basic. Diethanolamine can be used in the production of polyurethanes.

[0053] Similarly, it should be noted that the diethanolamine raw material used in this application can be a diethanolamine compound, or a substance or raw material containing diethanolamine, and the diethanolamine therein is suitable as a raw material for this amidation reaction to obtain furan-based polyamide monomers. That is to say, the diethanolamine raw material may also have some other components or impurities, as long as their presence does not affect the upcoming amidation reaction and can obtain usable furan-based polyamide monomers.

[0054] This application can use diethanolamine as a reaction raw material. In some cases, diethanolamine analogs can also be used as raw materials for this application. Diethanolamine analogs refer to compounds with similar structures or properties to diethanolamine. For example, N-methylethanolamine, N-ethylethanolamine, N-isopropylethanolamine, triethanolamine, etc.

[0055] In order to obtain the desired furan-based polyamide monomer product, in many cases, the amidation reaction needs to be carried out under certain reaction conditions. First, in order to enable the reaction to proceed smoothly and obtain a furan-based polyamide monomer product that meets the quality requirements, the furan methyl ester (raw material) and diethanolamine (raw material) need to meet a certain proportional relationship. The addition ratio (molar ratio) of furan methyl ester to diethanolamine can be 0.5 - 2 (0.5 - 2:1). For example, the molar ratio of furan methyl ester to diethanolamine can be 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1, 1:1, 1.1:1, 1.2:1, 1.3:1, 1.4:1, 1.5:1, 1.6:1, 1.7:1, 1.8:1, 1.9:1, 2:1, etc., or any range between the above ratios.

[0056] In addition, in many cases, the amidation reaction needs to be carried out in the presence of a catalyst and under vacuum conditions. The catalyst can be at least one of sodium hydroxide, potassium hydroxide, and triethanolamine. In this reaction, in addition to the above examples, the catalyst can also be other suitable inorganic bases or organic bases. In the amidation reaction, a base (such as sodium hydroxide) can deprotonate the carboxyl group or acyl group in the substrate to generate a carboxylate or acyl anion, thereby increasing the reactivity of the substrate. In the amidation reaction, sodium hydroxide and the like are used as catalysts to accelerate the reaction rate and improve the reaction yield. Specifically, sodium hydroxide can deprotonate the carboxyl group or acyl group in the substrate to generate a carboxylate or acyl anion: the carboxylate or acyl anion reacts with an amine to form an amide; after the reaction, sodium hydroxide can react with the carboxylate or acyl anion to generate water and a salt. In addition, certain organic amines, such as triethanolamine, dimethylamine, etc., can also be used as catalysts. Organic amines have good solubility in the substrate, and their basicity is moderate.

[0057] The amidation reaction is generally carried out under vacuum conditions. The vacuum conditions here refer to conditions where the gas pressure is very low. Vacuum is relative, and there is no absolute vacuum. Usually, a state where the absolute pressure is less than 1 Pa is called a vacuum condition. When the amidation reaction is carried out at atmospheric pressure, a large amount of water vapor is generated. The water vapor will react with the acyl anion to form an amide salt, thereby reducing the reaction yield. When the amidation reaction is carried out under vacuum conditions, the water vapor can be effectively removed, thereby increasing the reaction yield. In addition, the vacuum conditions can also prevent the amide salt generated by the amidation reaction from decomposing to form by-products. Therefore, in this application, the amidation reaction can generally be carried out under vacuum conditions. One advantage of the vacuum conditions is to prevent the formation of by-products. The amide salt generated by the amidation reaction is an unstable compound and is prone to decomposition to form by-products. When the amidation reaction is carried out under vacuum conditions, the decomposition of the amide salt to form by-products can be prevented. Therefore, the vacuum conditions are an important condition for promoting the "one-pot" reaction system (see below) of this application. In addition, the vacuum conditions can also reduce the reaction temperature. When the amidation reaction is carried out at atmospheric pressure, a relatively high reaction temperature is required to proceed; while when the amidation reaction is carried out under vacuum conditions, the reaction temperature can be reduced, and the corrosion of the equipment can also be reduced. This is also beneficial to the use of the "one-pot" reaction system.

[0058] In addition, the reaction temperature of the amidation reaction can be 30 - 150°C, and the reaction time can be 0.5 - 24 h. For example, the reaction temperature of the amidation reaction can be 30°C, 40°C, 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, or a range between any of the above temperatures. In some cases, the reaction temperature of the amidation reaction can be 60 - 120°C; or any other suitable temperature. Similarly, depending on the specific circumstances, the reaction time of the amidation reaction can be 0.5 h, 1 h, 2 h, 3 h, 4 h, 5 h, 6 h, 7 h, 8 h, 9 h, 10 h, 11 h, 12 h, 13 h, 14 h, 15 h, 16 h, 17 h, 18 h, 19 h, 20 h, 21 h, 22 h, 23 h, 24 h, or a range between any of the above times.

[0059] After the amidation reaction, an amino alcohol reaction can be carried out. Specifically, the furanyl polyamide monomer and the polyisocyanate compound raw material are subjected to an amino alcohol reaction to generate a furanyl polyurethane monomer. In the present application, based on the "one-pot" reaction system, the amidation reaction and the amino alcohol reaction are successively used to synthesize the furanyl polyurethane monomer. The "one-pot" reaction system refers to a chemical reaction strategy in which reactants are continuously subjected to multiple steps of reaction in a single reactor to improve the reaction efficiency. This method can avoid the lengthy separation process and the purification process of intermediate compounds in the post-treatment process, thereby saving time and resources and increasing the yield. The one-pot reaction system usually contains multiple catalysts, substrates, and solvents, and through appropriate reaction conditions, multiple steps are organically integrated together. Based on the "one-pot" reaction system, by performing multiple steps in the same reaction vessel, the separation and purification steps between substrates can be reduced, and the overall efficiency of the reaction can be improved. The use of solvents, energy, and waste is reduced, which conforms to the principles of green chemistry. The "one-pot" method can also shorten the synthesis cycle, reduce the required time, and increase the yield. At the same time, because the intermediate steps do not require separation and purification, the possibility of synthesis failure is reduced. It can also reduce the reaction cost. On the other hand, a specific one-pot reaction requires the selection of suitable catalysts, reaction conditions, and substrates to ensure that each reaction step can be carried out in the same system and conditions without interfering with each other. For example, the amidation reaction mentioned above is carried out under vacuum conditions.

[0060] In the amine-alcohol reaction, the raw materials are the furanyl polyamide monomer obtained from the amidation reaction and the polyisocyanate compound. The amine-alcohol reaction between the polyamide and the polyisocyanate is a reaction in which the polyamide and the polyisocyanate react under the action of a catalyst to form polyurethane. The amine-alcohol reaction between the polyamide and the polyisocyanate can be a multi-step reaction. The amino group in the polyamide reacts with the isocyanate group in the polyisocyanate to form a urethane group; the carboxyl group in the urethane group reacts with the isocyanate group in the polyisocyanate to form a urea group; the reaction continues until polyurethane, that is, the furanyl polyurethane monomer of the present application, is finally formed.

[0061] The raw material in this reaction is the polyisocyanate compound. Polyisocyanates are a class of compounds that contain multiple isocyanate groups (-N=C=O) in their molecules. According to the number of isocyanate groups, polyisocyanates can be divided into diisocyanates, triisocyanates, tetraisocyanates, etc. They have reactive isocyanate groups, and the isocyanate groups have strong nucleophilicity and can react with various functional groups, such as alcohols, amines, carboxylic acids, etc. They also have relatively high reactivity. The reactivity of polyisocyanates is related to the number of isocyanate groups. The more isocyanate groups, the higher the reactivity. Such compounds play an important role in the preparation of polyurethane polymers because they can react with polyols such as polyether polyols or polyester polyols to form polyurethanes.

[0062] It should also be noted that the polyisocyanate compound raw material used in the present application can be a polyisocyanate compound, or a substance or raw material containing polyisocyanate, and the polyisocyanate therein is suitable as the raw material for this amidation reaction to obtain the furanyl polyamide monomer. That is to say, the polyisocyanate compound raw material may also contain some other components or impurities, as long as their presence does not affect the upcoming amidation reaction and can obtain a usable furanyl polyamide monomer.

[0063] Specifically, the polyisocyanate compound raw material can be, but is not limited to, naphthalene diisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate, hexamethylene diisocyanate, o-tolidine diisocyanate, xylene diisocyanate, isophorone diisocyanate, trimethylhexamethylene diisocyanate, m-xylylene diisocyanate, toluene 2,6-diisocyanate, triphenylmethane triisocyanate, tris(isocyanato-methyl)silane. The above are only some examples of the polyisocyanate compound raw material, and any combination thereof or combination with other substances can also be used in the present application.

[0064] In the amine-alcohol reaction, the mixing ratio of the furyl polyamide monomer and the polyisocyanate compound should be controlled within a certain range, such as 0.5 - 2. Specifically, the molar ratio of the hydroxyl groups contained in the furyl polyamide monomer to the isocyanate groups in the polyisocyanate compound is 0.5 - 2 (0.5 - 2:1). For example, the molar ratio can be 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1, 1:1, 1.1:1, 1.2:1, 1.3:1, 1.4:1, 1.5:1, 1.6:1, 1.7:1, 1.8:1, 1.9:1, 2:1, etc., or any range between the above ratios.

[0065] The amine-alcohol reaction also needs to be carried out under certain reaction conditions. Specifically, the amine-alcohol reaction is carried out in an inert gas atmosphere and in the presence of a catalyst. The inert gas atmosphere includes at least one of nitrogen, helium, or argon. The main reason for carrying out the amine-alcohol reaction in an inert gas atmosphere is to prevent oxidation and the adverse effects of other gases. By replacing the air with an inert gas in the reaction system, the oxidation reaction can be prevented. In the amine-alcohol reaction, both amines and alcohols are substances that are prone to oxidation. If the reaction is carried out in the presence of oxygen, an oxidation reaction will occur, generating by-products and reducing the reaction yield. Carrying out the reaction in an inert gas atmosphere can prevent the occurrence of the oxidation reaction. The inert gas atmosphere can also prevent hydrolysis reactions. In the amine-alcohol reaction, water is also a substance that can undergo hydrolysis reactions. If the reaction is carried out in the presence of water, by-products will be generated and the reaction yield will be reduced. Carrying out the reaction in an inert gas atmosphere can prevent the occurrence of hydrolysis reactions. In addition, polymerization reactions can also be prevented. In the amine-alcohol reaction, the generated polyurethane molecules have strong reactivity. If the reaction is carried out in air, a polymerization reaction will occur, generating overly long polyurethane molecules and affecting the performance of the polyurethane. Carrying out the reaction in an inert gas atmosphere can prevent the occurrence of unnecessary polymerization reactions.

[0066] The catalyst for the aminoalcohol reaction can be at least one of dimethyltin stannate, dibutyltin stannate, or butyllithium. Organometallic compounds such as dimethyltin stannate, dibutyltin stannate, and butyllithium can be used as catalysts for the aminoalcohol reaction. It can provide an active center for the reaction. The metal atoms in the organometallic compound have strong electrophilicity and can undergo nucleophilic addition reactions with the carbonyl group in the isocyanate molecule to form a metal-isocyanate complex. This complex has high reactivity and can promote the progress of the reaction. It can also promote the dissociation of the isocyanate molecule. The metal atoms in the organometallic compound can coordinate with the nitrogen atom in the isocyanate molecule, thereby promoting the dissociation of the isocyanate molecule to generate a highly reactive isocyanate group. At the same time, it can inhibit the polymerization reaction. The metal atoms in the organometallic compound can coordinate with the nitrogen atom in the polyurethane molecule, thereby inhibiting the polymerization reaction of the polyurethane molecule. Specifically, dimethyltin stannate is a commonly used catalyst for the aminoalcohol reaction and has high catalytic activity. It can enable the reaction to proceed at a lower temperature, increase the reaction yield, and reduce the generation of by-products. Dibutyltin stannate is a catalyst for the aminoalcohol reaction with excellent performance and has strong heat resistance and stability. It can be used in the production of high-performance polyurethanes. Butyllithium is a strongly basic organometallic compound and has strong catalytic activity. It can complete the reaction in a shorter time and increase the reaction yield. Which catalyst to specifically select needs to be determined according to the reaction conditions and the properties of the desired product.

[0067] Dimethyltin stannate, dibutyltin stannate, butyllithium, or a combination thereof are only some examples of the catalysts for the aminoalcohol reaction of the present application. Any other organometallic compound with similar catalytic activity can also be used as a catalyst for the aminoalcohol reaction.

[0068] The reaction temperature of the aminoalcohol reaction can be 30 - 80 °C, and the reaction time can be 2 - 12 h. For example, the reaction temperature of the aminoalcohol reaction can be 30 °C, 40 °C, 50 °C, 60 °C, 70 °C, 80 °C, or a range between any of the above temperatures. Similarly, depending on the specific situation, the reaction time of the amidation reaction can be 2 h, 3 h, 4 h, 5 h, 6 h, 7 h, 8 h, 9 h, 10 h, 11 h, 12 h, or a range between any of the above times.

[0069] Therefore, through the selection and adjustment of the factors for the amidation reaction and the amino-alcohol reaction described above (including the type and ratio of reaction raw materials, the type of catalyst, the reaction environment (vacuum condition or inert atmosphere), the reaction temperature and time, etc.), the amidation reaction and the amino-alcohol reaction of the present application can be realized in the same reactor based on the "one-pot" reaction system. The reaction conditions of these reactions are mild, the reactions proceed completely, the reactant residues are few, and the product content is high. All these enable the present invention to be successfully completed in the "one-pot" reaction system, and finally obtain a furan-based polyurethane material that can meet the requirements of 3D printing materials. For example, as Figure 1 shown, in the infrared spectrum of the furan-based polyurethane monomer, the infrared characteristic diffraction peaks near 1143 cm -1 , 1616 cm -1 , and 3324 cm -1 respectively represent the C-O-C bond of the furan ring, the amide bond, and the hydroxyl group; the peak at 1701 cm -1 represents the C=O stretching vibration peak; the peaks near 1534 cm -1 and 3324 cm -1 respectively represent the N-H bending vibration and stretching vibration peaks in the urethane group. In addition, the characteristic infrared absorption peak of isocyanate is between 2260 - 2280 cm -1 , which is not observed in this figure, indicating that the isocyanate group is completely reacted during the preparation process. It can be concluded that the preparation route of the furan-based polyurethane is feasible and has the potential for scale-up experiments.

[0070] As Figure 2 shown, the obtained furan-based polyurethane monomer is further subjected to a Diels-Alder addition reaction with a bismaleimide compound raw material to obtain the furan-based polyurethane material containing a Diels-Alder structure. Bismaleimide has an olefin structure. Bismaleimide is a class of compounds containing two maleimide groups, which are formed by the condensation of two maleic anhydride molecules. Each maleimide group contains an olefin structure. Therefore, the bismaleimide molecule as a whole contains two olefin structures. Bismaleimide has two olefin bonds, which are respectively located between the carbonyl groups in the two maleic anhydride molecules. The olefin bonds of bismaleimide can react with other compounds, such as undergoing a Diels-Alder reaction with a polyurethane monomer to generate a polyurethane material with good properties.

[0071] The Diels-Alder addition reaction is a cyclization reaction. This reaction is an addition reaction between an alkene and an enediene, usually carried out under thermodynamic and kinetic conditions. The Diels-Alder reaction can efficiently construct cyclic structures. The Diels-Alder reaction is an important organic reaction involving a [4+2] cycloaddition between two molecules. The first molecule is a conjugated diene, which has two π bonds. The second molecule is a dienophile, which has one π bond. The reaction product is a six-membered ring in which the two π bonds of the diene and the π bond of the dienophile are both converted into σ bonds. First, the two π bonds in the conjugated diene molecule form a four-membered ring transition state. Then, the π bond of the dienophile forms a bond with the carbon atoms in the transition state to form a six-membered ring product. The reaction conditions of the Diels-Alder reaction are mild, and the reaction is usually carried out at room temperature or slightly higher temperature. The reaction yield is high and the reaction specificity is good.

[0072] Specifically, in the Diels-Alder addition reaction between a furyl polyurethane monomer and a bismaleimide compound raw material, the functional group containing a diene structure in the polyurethane monomer reacts with the alkene structure in the bismaleimide to form a cyclic product, where the diene part acts as a 4π electron system and the alkene part acts as a 2π electron system. Under suitable reaction conditions, a [4+2] addition reaction occurs between them to generate a fused-ring product.

[0073] In this application, selecting the Diels-Alder addition reaction can have the following characteristics and advantages. The Diels-Alder reaction is an enthalpy-favorable forward cycloaddition reaction that occurs at low temperatures, while the reverse ring reduction reaction occurs at medium to high temperatures. The Diels-Alder reaction belongs to the category of "click chemistry", with simple reaction conditions, high yields, good selectivity, and a large number of chemical raw materials available for the design of advanced structure Diels-Alder systems. The polymerization process of the Diels-Alder reaction is an exothermic reaction, which can play a role in local heating during the FFF / FDM cooling and forming process. The temperature range of the polymerization / depolymerization process of the polymer containing the Diels-Alder structure is within the temperature range of most FFF / FDM processes, having little impact on the printing process.

[0074] According to the present application, the above Diels-Alder addition reaction can be carried out during the wire extrusion process for forming a wire product. This extrusion process is a simple, non-catalytic melt extrusion process. The wire extrusion process is a process of melting raw materials into a melt and then extruding the melt through the nozzle of an extruder into a wire. The wire extrusion process can include, for example, a single-screw processing technology, a twin-screw processing technology, etc. By adding a furyl polyurethane monomer and a bismaleimide compound during the preparation process of 3D printing wire, a furyl polyurethane material containing a Diels-Alder structure can be obtained through an on-line extrusion processing process.

[0075] In the above Diels-Alder addition reaction, the bismaleimide compound is one of bismaleimide, diphenyl ether bismaleimide, bismaleimide methyl ether, bismaleimide-hexapolyethylene glycol, N,N-(1,4-phenylene) bismaleimide, N-(4-methyl-1,3-phenylene) bismaleimide, 1,10-bis(maleimide) decane, 1,2-bis(maleimide) ethane, N-hydroxysuccinimide 3-maleimide propionate, etc.

[0076] In the above Diels-Alder addition reaction, the addition ratio of the furyl polyurethane monomer and the bismaleimide compound can be 0.5 - 1.5 (mass ratio). For example, this mass ratio can be 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1, 1:1, 1.1:1, 1.2:1, 1.3:1, 1.4:1, 1.5:1, etc., or a range between any of the above ratios.

[0077] As mentioned above, the Diels-Alder addition reaction can be carried out during the wire extrusion process for forming a wire product. During this process, the total addition proportion of the furyl polyurethane monomer and the bismaleimide compound can be 5 - 25% (mass ratio). For example, the total addition proportion of these two can be 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, etc., or a range between any of the above values.

[0078] During the wire extrusion process, in addition to the furyl polyurethane monomer and the bismaleimide compound, other additives can also be added, such as a compatibilizer, a plasticizer, etc.

[0079] During this process, the processing temperature can be 160 - 250 °C, and the processing time can be 10 - 60 min. For example, the reaction temperature of the amine-alcohol reaction can be 160 °C, 170 °C, 180 °C, 190 °C, 200 °C, 210 °C, 220 °C, 230 °C, 240 °C, 250 °C, or a range between any of the above temperatures. Similarly, depending on the specific situation, the reaction time of the amidation reaction can be 10 min, 15 min, 20 min, 25 min, 30 min, 35 min, 40 min, 45 min, 50 min, 55 min, 60 min, or a range between any of the above times.

[0080] After the above reaction process, the prepared polyurethane product, namely the furanyl polyurethane material containing the Diels - Alder structure, is finally obtained. The Diels - Alder structure refers to a specific cyclic structure formed through the Diels - Alder reaction. Specifically, the characteristic of the Diels - Alder structure is having a six - membered ring, which contains a ureido group or an alcohol group. This ring is usually formed through a [4 + 2] cycloaddition reaction between a diene containing a 4π electron system and an alkene containing a 2π electron system. The characteristics of this structure are having two π - bonds, one from the diene and the other from the dienophile. The Diels - Alder structure can have reversible dynamic covalent bonds. The two π - bonds in this structure can be broken by heating or other external stimuli and then reformed upon cooling or other external stimuli. This reversibility enables the Diels - Alder structure to have various potential applications, such as self - healing materials, material regulation, degradation, etc. The Diels - Alder structure can be used to prepare self - healing materials, which can automatically repair after being damaged by heating or other external stimuli. The properties of the Diels - Alder structure can be changed by adjusting the temperature or other external stimuli, which can be used to prepare materials with tunable properties. The Diels - Alder structure can also be used to prepare degradable materials, which can degrade by heating or other external stimuli under specific environments. The reversibility of the Diels - Alder structure can be enhanced by designing special dienes and dienophiles. The reversibility of the Diels - Alder structure can also be regulated by introducing other chemical groups. For example, the polyurethane material prepared in this application can be used as an additive. After being compounded with 3D printing filaments, it can exhibit the "self - healing" characteristic of the layer - to - layer interface of the printed parts through a simple, non - catalytic melt extrusion process, and good non - covalent bond interactions and new covalent bonds can be formed at the contact interface.

[0081] The furanyl polyurethane material containing a Diels - Alder structure in this application is a polymeric material formed by units of furanyl polyurethane monomers containing a Diels - Alder structure. The furanyl polyurethane monomer containing a Diels - Alder structure has the following structure:

[0082]

[0083] Wherein R is any one of the following groups, or its derivative structure:

[0084]

[0085] R1 is any one of the following groups, or its derivative structure:

[0086]

[0087] It should be noted that in formula (I), the R and R1 groups can be any suitable groups, which are determined by the selected relevant reaction raw materials, rather than being limited to these examples mentioned here. For example, it can also be the structures, their derivatives, analogs, etc. mentioned in any of the above reaction introductions.

[0088] The furanyl polyurethane material obtained in this application contains a Diels - Alder structure and reversible dynamic covalent bonds. Therefore, it is a polyurethane material with "self - healing properties". This material can be applied in many different fields. For example, this furanyl polyurethane material can be used in the field of 3D printing. The polyurethane material prepared in the present invention can be used as an additive. After being compounded with 3D printing filaments, through a simple, non - catalytic melt extrusion process, it can exhibit the "autonomous repair" characteristic of the interlayer interface of the printed parts, and good non - covalent bond interactions and new covalent bonds can be formed at the contact interface. In this way, the dynamic covalent chemistry function is used to solve the filament adhesion problem at the molecular level and enhance the interlayer through chemical reactions. Dynamic covalent chemistry uses reversible covalent bonds to form a complex but thermodynamically stable network system, that is, introducing (weak) covalent chemical bonds as an additional source of interlayer strength. The interlayer strength is improved without sacrificing other material properties.

[0089] The following is a specific description in combination with specific examples. Unless otherwise specified in the following examples, other components are not included except for inevitable impurities. The reagents and instruments used in the examples are all conventional selections in the art unless otherwise specified. The experimental methods without specific conditions noted in the examples are carried out under conventional conditions, such as the conditions described in the literature, books, or the methods recommended by the manufacturers.

[0090] Example 1

[0091] (1) Add furan methyl ester and diethanolamine into a single-neck flask under the condition that the molar ratio is 0.5:1; (2) After stirring evenly mechanically, add KOH catalyst, and the dosage of KOH is 0.5% of the total mass of the reaction system; (3) Carry out amidation reaction for 24 h under vacuum condition, the reaction temperature is 60 °C, and the furan-based polyamide monomer can be obtained after the reaction is completed; (4) Transfer the above-mentioned furan-based polyamide monomer to a 250 ml three-neck flask with a condensing reflux device under nitrogen atmosphere, and add 100 g ethyl acetate solvent and dibutyltin dilaurate catalyst into the system, and the dosage of dibutyltin dilaurate is 0.1% of the total mass of the reaction system; (5) Accurately weigh hexamethylene diisocyanate and place it in an ordinary pressure burette funnel with a glass stopper, and the molar ratio of hydroxyl group to isocyanate group in the reaction system is 1:1; (6) After heating the reaction system to 30 °C, add hexamethylene diisocyanate dropwise into the three-neck flask at a speed of 1 drop per second, continuously stir during the dropping process, and carry out amine-alcohol reaction for 10 h at 30 °C after the dropping is completed; (7) After the reaction is completed, rotary evaporate under vacuum to remove the solvent ethyl acetate to obtain the furan-based polyurethane monomer; (8) Add the furan-based polyurethane monomer and bismaleimide into the 3D printing wire at a mass ratio of 0.5:1, and the sum of the masses of the furan-based polyurethane monomer and bismaleimide accounts for 5% of the total mass of the system; (9) Subsequently, through an on-line extrusion processing process, including a twin-screw processing process and a single-screw processing process, wherein the processing temperature is between 160 - 250 °C, and at the same time, some solubilizers and plasticizers need to be added; (10) After the processing is completed, a furan-based polyurethane composite containing Diels-Alder structure can be obtained and used in the field of extrusion 3D printing; (11) Use internal standard testing and record its final results, as shown in Table 1 for details.

[0092] The above-mentioned internal standard testing is specifically as follows:

[0093] 3D model printing and specimen mechanical testing

[0094] 1. Select Raise E2 printer for standard testing

[0095] 2. Place the qualified materials in an effective drying box (relative humidity less than 10%) for at least 6 h

[0096] 3. Printing conditions

[0097] · Nozzle diameter: 0.4 mm

[0098] · Extrusion line width: 100%

[0099] · Layer height: 0.2 mm

[0100] · Number of solid layers on the top layer and the bottom layer: 0

[0101] · Number of outer layer and inner layer: 1

[0102] · Use Brim, 0 mm away from the spline, print 5 circles, height is 1 layer

[0103] · Fill rate: 0%

[0104] · Model and size: Hollow cube, 100*100*100 mm 3

[0105] · Printing temperature: 220 °C

[0106] · Printing speed: 60 mm / min

[0107] · Fan: 100%

[0108] 4. Making specimens with a rubber and plastic punching machine

[0109] · Instrument: Model ZB-702 of Jiangsu Zhengrui Taibang Electronic Technology Co., Ltd.

[0110] · Ensure that more than 10 specimens can be made for each group

[0111] 5. Interlaminar strength test

[0112] · Instrument: Microcomputer controlled electronic universal testing machine E44.304 of MEST Industrial Systems (China) Co., Ltd.

[0113] · Method: GB / T 1040.1-2018 / ISO 527-1 2012

[0114] · Ambient temperature: 23 ± 2 °C

[0115] · Test speed: 2 mm / min

[0116] Example 2

[0117] (1) Add furfuryl formate and diethanolamine into a single-neck flask under the condition that the molar ratio is 0.5:1; (2) After stirring evenly mechanically, add NaOH catalyst, and the dosage of NaOH is 0.5% of the total mass of the reaction system; (3) Carry out amidation reaction for 12 h under vacuum condition, the reaction temperature is 60 °C, and the furan-based polyamide monomer can be obtained after the reaction is completed; (4) Transfer the above-mentioned furan-based polyamide monomer to a 250 ml three-neck flask with a condensing reflux device under nitrogen atmosphere, and add 100 g of ethyl acetate solvent and dibutyltin dilaurate catalyst into the system, and the dosage of dibutyltin dilaurate is 0.1% of the total mass of the reaction system; (5) Accurately weigh m-phenylene diisocyanate and place it in an ordinary pressure burette funnel with a glass stopper, and the molar ratio of hydroxyl group to isocyanate group in the reaction system is 1:1; (6) After heating the reaction system to 30 °C, add m-phenylene diisocyanate dropwise into the three-neck flask at a speed of 1 drop per second, continuously stir during the dropping process, and carry out amine-alcohol reaction for 8 h at 30 °C after the dropping is completed; (7) After the reaction is completed, rotary evaporate under vacuum to remove the solvent ethyl acetate to obtain the furan-based polyurethane monomer; (8) Add the furan-based polyurethane monomer and bismaleimide into the 3D printing wire at a mass ratio of 0.5:1, and the sum of the masses of the furan-based polyurethane monomer and bismaleimide accounts for 5% of the total mass of the system; (9) Subsequently, through an on-line extrusion processing process, including a twin-screw processing process and a single-screw processing process, wherein the processing temperature is between 160-250 °C, and at the same time, some solubilizers and plasticizers need to be added; (10) After the processing is completed, a furan-based polyurethane composite containing Diels-Alder structure can be obtained and used in the field of extrusion 3D printing; (11) Use internal standard to test and record its final results, as shown in Table 1 for details.

[0118] Example 3

[0119] (1) Add furan methyl ester and diethanolamine into a single-necked flask under the condition that the molar ratio is 1:1; (2) After mechanically stirring evenly, add NaOH catalyst, and the dosage of NaOH is 0.5% of the total mass of the reaction system; (3) Carry out amidation reaction for 12 h under vacuum condition, the reaction temperature is 80 °C, and the furan-based polyamide monomer can be obtained after the reaction is completed; (4) Transfer the above-mentioned furan-based polyamide monomer to a 250 ml three-necked flask with a condensing reflux device under nitrogen atmosphere, and add 100 g of ethyl acetate solvent and dibutyltin dilaurate catalyst into the system, and the dosage of dibutyltin dilaurate is 0.1% of the total mass of the reaction system; (5) Accurately weigh hexamethylene diisocyanate and place it in an atmospheric titration funnel with a glass stopper, and the molar ratio of hydroxyl group to isocyanate group in the reaction system is 1:1; (6) After heating the reaction system to 40 °C, add hexamethylene diisocyanate dropwise into the three-necked flask at a speed of 1 drop per second, continuously stir during the dropping process, and carry out amine-alcohol reaction for 8 h at 40 °C after the dropping is completed; (7) After the reaction is completed, rotary evaporate under vacuum to remove the solvent ethyl acetate to obtain the furan-based polyurethane monomer; (8) Add the furan-based polyurethane monomer and bismaleimide into the 3D printing wire at a mass ratio of 0.5:1, and the sum of the masses of the furan-based polyurethane monomer and bismaleimide accounts for 5% of the total mass of the system; (9) Subsequently, through an on-line extrusion process, including a twin-screw processing process and a single-screw processing process, wherein the processing temperature is between 160-250 °C, and at the same time, some solubilizers and plasticizers need to be added; (10) After processing, a furan-based polyurethane composite containing Diels-Alder structure can be obtained and used in the field of extrusion 3D printing; (11) Use internal standard testing and record its final results, as shown in Table 1 for details.

[0120] Example 4

[0121] (1) Add furfuryl formate and diethanolamine into a single-neck flask under the condition that the molar ratio is 1:1; (2) After stirring evenly mechanically, add triethanolamine catalyst, and the dosage of triethanolamine is 0.5% of the total mass of the reaction system; (3) Carry out amidation reaction for 6 h under vacuum condition, the reaction temperature is 80 °C, and the furan-based polyamide monomer can be obtained after the reaction is completed; (4) Transfer the above-mentioned furan-based polyamide monomer to a 250 ml three-neck flask with a condensation reflux device under a nitrogen atmosphere, and add 100 g of ethyl acetate solvent and dibutyltin dilaurate catalyst to the system, and the dosage of dibutyltin dilaurate is 0.1% of the total mass of the reaction system; (5) Accurately weigh hexamethylene diisocyanate and place it in an ordinary pressure burette funnel with a glass stopper, and the molar ratio of hydroxyl group to isocyanate group in the reaction system is 0.5:1; (6) After heating the reaction system to 50 °C, add hexamethylene diisocyanate dropwise to the three-neck flask at a speed of 1 drop per second, continuously stir during the dropping process, and carry out amine-alcohol reaction for 6 h at 50 °C after the dropping is completed; (7) After the reaction is completed, rotary evaporate under vacuum to remove the solvent ethyl acetate to obtain the furan-based polyurethane monomer; (8) Add the furan-based polyurethane monomer and diphenyl ether bismaleimide into the 3D printing wire at a mass ratio of 1:1, and the sum of the masses of the furan-based polyurethane monomer and diphenyl ether bismaleimide accounts for 10% of the total mass of the system; (9) Subsequently, through an on-line extrusion process, including a twin-screw processing process and a single-screw processing process, wherein the processing temperature is between 160-250 °C, and at the same time, some solubilizers and plasticizers need to be added; (10) After the processing is completed, a furan-based polyurethane composite material containing a Diels-Alder structure can be obtained and used in the field of extrusion 3D printing; (11) Use internal standard tests and record the final results, as shown in Table 1 for details.

[0122] Example 5

[0123] (1) Add furan methyl ester and diethanolamine into a single-neck flask under the condition that the molar ratio is 1:1; (2) After stirring evenly mechanically, add KOH catalyst, and the dosage of KOH is 0.5% of the total mass of the reaction system; (3) Carry out amidation reaction for 4 h under vacuum condition, the reaction temperature is 100 °C, and the furan-based polyamide monomer can be obtained after the reaction is completed; (4) Transfer the above-mentioned furan-based polyamide monomer to a 250 ml three-neck flask with a condensing reflux device under nitrogen atmosphere, and add 100 g of ethyl acetate solvent and butyl lithium catalyst to the system, and the dosage of butyl lithium is 0.1% of the total mass of the reaction system; (5) Accurately weigh p-phenylene diisocyanate and place it in an atmospheric titration funnel with a glass stopper, and the molar ratio of hydroxyl group to isocyanate group in the reaction system is 0.5:1; (6) After heating the reaction system to 50 °C, add p-phenylene diisocyanate dropwise to the three-neck flask at a speed of 1 drop per second, continuously stir during the dropping process, and carry out amine-alcohol reaction for 6 h at 50 °C after the dropping is completed; (7) After the reaction is completed, rotary evaporate under vacuum to remove the solvent ethyl acetate to obtain the furan-based polyurethane monomer; (8) Add the furan-based polyurethane monomer and bismaleimide into the 3D printing wire at a mass ratio of 1:1, and the sum of the masses of the furan-based polyurethane monomer and bismaleimide accounts for 10% of the total mass of the system; (9) Subsequently, through an on-line extrusion process, including a twin-screw processing technology and a single-screw processing technology, wherein, the processing temperature is between 160-250 °C, and at the same time, some solubilizers and plasticizers need to be added; (10) After processing, a furan-based polyurethane composite material containing a Diels-Alder structure can be obtained and used in the field of extrusion 3D printing; (11) Use internal standard to test and record its final results, as shown in Table 1 for details.

[0124] Example 6

[0125] (1) Add furan methyl ester and diethanolamine into a single-neck flask under the condition that the molar ratio is 2:1; (2) After mechanically stirring evenly, add NaOH catalyst, and the dosage of NaOH is 0.5% of the total mass of the reaction system; (3) Carry out amidation reaction for 2 h under vacuum condition, the reaction temperature is 100 °C, and the furan-based polyamide monomer can be obtained after the reaction is completed; (4) Transfer the above-mentioned furan-based polyamide monomer to a 250 ml three-neck flask with a condensation reflux device under a nitrogen atmosphere, and add 100 g of ethyl acetate solvent and butyl lithium catalyst to the system, and the dosage of butyl lithium is 0.1% of the total mass of the reaction system; (5) Accurately weigh p-phenylene diisocyanate and place it in an ordinary pressure burette funnel with a glass stopper, and the molar ratio of hydroxyl group to isocyanate group in the reaction system is 0.5:1; (6) After heating the reaction system to 60 °C, add p-phenylene diisocyanate dropwise to the three-neck flask at a speed of 1 drop per second, continuously stir during the dropping process, and carry out amine-alcohol reaction for 4 h at 60 °C after the dropping is completed; (7) After the reaction is completed, rotary evaporate under vacuum to remove the solvent ethyl acetate to obtain the furan-based polyurethane monomer; (8) Add the furan-based polyurethane monomer and bismaleimide into the 3D printing wire at a mass ratio of 1:1, and the sum of the masses of the furan-based polyurethane monomer and bismaleimide accounts for 15% of the total mass of the system; (9) Subsequently, through an on-line extrusion process, including a twin-screw processing technology and a single-screw processing technology, wherein, the processing temperature is between 160-250 °C, and at the same time, some solubilizers and plasticizers need to be added; (10) After processing, a furan-based polyurethane composite material containing a Diels-Alder structure can be obtained and used in the field of extrusion 3D printing; (11) Use internal standard testing and record its final results, as shown in Table 1 for details.

[0126] Example 7

[0127] (1) Add furan methyl ester and diethanolamine into a single-necked flask under the condition that the molar ratio is 2:1; (2) After mechanically stirring evenly, add KOH catalyst, and the dosage of KOH is 0.5% of the total mass of the reaction system; (3) Carry out amidation reaction for 1 h under vacuum condition, the reaction temperature is 120 °C, and the furan-based polyamide monomer can be obtained after the reaction is completed; (4) Transfer the above-mentioned furan-based polyamide monomer to a 250 ml three-necked flask with a condensation reflux device under a nitrogen atmosphere, and add 100 g of ethyl acetate solvent and dibutyltin dilaurate catalyst to the system, and the dosage of dibutyltin dilaurate is 0.1% of the total mass of the reaction system; (5) Accurately weigh hexamethylene diisocyanate and place it in an ordinary pressure burette funnel with a glass stopper, and the molar ratio of hydroxyl group to isocyanate group in the reaction system is 2:1; (6) After heating the reaction system to 70 °C, add hexamethylene diisocyanate dropwise to the three-necked flask at a speed of 1 drop per second, continuously stir during the dropping process, and carry out amine-alcohol reaction for 4 h at 70 °C after the dropping is completed; (7) After the reaction is completed, rotary evaporate under vacuum to remove the solvent ethyl acetate to obtain the furan-based polyurethane monomer; (8) Add the furan-based polyurethane monomer and bismaleimide into the 3D printing wire at a mass ratio of 2:1, and the sum of the masses of the furan-based polyurethane monomer and bismaleimide accounts for 20% of the total mass of the system; (9) Subsequently, through an on-line extrusion process, including a twin-screw processing process and a single-screw processing process, wherein the processing temperature is between 160-250 °C, and at the same time, some solubilizers and plasticizers need to be added; (10) After processing, a furan-based polyurethane composite containing a Diels-Alder structure can be obtained and used in the field of extrusion 3D printing; (11) Use internal standard testing and record its final results, as shown in Table 1 for details.

[0128] Example 8

[0129] (1) Add furan methyl ester and diethanolamine into a single-neck flask under the condition that the molar ratio is 2:1; (2) After mechanically stirring evenly, add triethanolamine catalyst, and the dosage of triethanolamine is 0.5% of the total mass of the reaction system; (3) Carry out amidation reaction for 0.5 h under vacuum condition, the reaction temperature is 120 °C, and the furan-based polyamide monomer can be obtained after the reaction is completed; (4) Transfer the above-mentioned furan-based polyamide monomer to a 250 ml three-neck flask equipped with a condensing reflux device under a nitrogen atmosphere, and add 100 g of ethyl acetate solvent and dibutyltin dilaurate catalyst to the system, and the dosage of dibutyltin dilaurate is 0.1% of the total mass of the reaction system; (5) Accurately weigh isophorone diisocyanate and place it in an atmospheric titration funnel with a glass stopper, and the molar ratio of hydroxyl group to isocyanate group in the reaction system is 2:1; (6) After heating the reaction system to 80 °C, drop isophorone diisocyanate into the three-neck flask at a speed of 1 drop per second, continuously stir during the dropping process, and carry out amine-alcohol reaction for 2 h at 80 °C after the dropping is completed; (7) After the reaction is completed, rotary evaporate under vacuum to remove the solvent ethyl acetate to obtain the furan-based polyurethane monomer; (8) Add the furan-based polyurethane monomer and bismaleimide into the 3D printing wire at a mass ratio of 2:1, and the sum of the masses of the furan-based polyurethane monomer and bismaleimide accounts for 25% of the total mass of the system; (9) Subsequently, through an on-line extrusion process, including a twin-screw processing process and a single-screw processing process, wherein the processing temperature is between 160-250 °C, and at the same time, some solubilizers and plasticizers need to be added; (10) After processing, a furan-based polyurethane composite material containing a Diels-Alder structure can be obtained and used in the field of extrusion 3D printing; (11) Use internal standard testing and record its final results, as shown in Table 1.

[0130] Table 1. Interlayer bonding strength of furan-based polyurethane composite material containing Diels-Alder structure

[0131]

[0132] As can be seen from Table 1, the furan-based polyurethane composite material containing a Diels-Alder structure obtained according to this application has an interlayer strength improvement rate of at least about 50%. The improvement rate in Table 1 was measured with the corresponding pure wire matrix without D-A structure as the comparative sample 2. It can be seen that by adjusting different reaction conditions, the Z-axis interlayer strength of the 3D printed part can be increased by about 200%, such as Example 8.

[0133] In summary, the preparation method of a furanyl polyurethane material containing a Diels-Alder structure and its application in the field of 3D printing according to the present application have the following advantages: 1) The preparation method of the target product is simple and efficient. It is prepared by the "one-pot method", and there is no need for purification during the preparation process, saving a large amount of cost-effectiveness; 2) The furanyl polyurethane polymer prepared in this patent has excellent thermal stability and biodegradability, has a wide range of uses and is environmentally friendly; 3) The furanyl polyurethane material containing a Diels-Alder structure prepared in this patent is a general-purpose material, which can be added to any 3D printing wire, and while not losing other properties of the material, it can increase its interlayer strength by 50-200%.

[0134] Therefore, according to the present invention, using furan methyl ester, diethanolamine and polyisocyanate compounds as the main raw materials, based on the "one-pot method" reaction system, a furanyl polyurethane monomer is synthesized, and then a "Diels-Alder addition reaction" is carried out with a bismaleimide compound to synthesize a bio-based polyurethane material, and it is used in the field of 3D printing wire. At the same time, the problem of filament adhesion of 3D printing wire is solved at the molecular level by using dynamic covalent chemistry function.

[0135] The specific embodiments of this specification have been described above. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps recited in the claims can be performed in a different order than in the embodiments and still achieve the desired results. Additionally, the processes depicted in the figures do not necessarily require a particular order or a sequential order to achieve the desired results. In certain embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0136] In summary, after reading this detailed disclosure, those skilled in the art can understand that the foregoing detailed disclosure may be presented only by way of example and may not be restrictive. Although not explicitly stated herein, those skilled in the art can understand that this specification is intended to encompass various reasonable changes, improvements, and modifications to the embodiments. These changes, improvements, and modifications are intended to be proposed by this specification and are within the spirit and scope of the exemplary embodiments of this specification.

[0137] In addition, certain terms in this specification have been used to describe the embodiments of this specification. For example, "one embodiment", "embodiment" and / or "some embodiments" mean that the specific features, structures or characteristics described in connection with the embodiment may be included in at least one embodiment of this specification. Therefore, it should be emphasized and understood that the two or more references to "embodiment" or "one embodiment" or "alternative embodiment" in various parts of this specification do not necessarily all refer to the same embodiment. Additionally, the specific features, structures or characteristics may be appropriately combined in one or more embodiments of this specification.

[0138] It should be understood that in the foregoing description of the embodiments of this specification, for the purpose of helping to understand a feature and for the purpose of simplifying this specification, this specification combines various features in a single embodiment, drawing, or its description. However, this does not mean that the combination of these features is necessary. When those skilled in the art read this specification, it is entirely possible to extract some of these features as separate embodiments for understanding. That is to say, the embodiments in this specification can also be understood as the integration of multiple sub - embodiments. And it also holds when the content of each sub - embodiment is less than all the features of a single foregoing disclosed embodiment.

[0139] Each patent, patent application, published patent application, and other materials cited herein, such as articles, books, specifications, publications, documents, items, etc., may be incorporated herein by reference. The entire content for all purposes, except for any prosecution file history associated therewith, any identical that may be inconsistent or in conflict with this document, or any identical prosecution file history that may have a limiting effect on the broadest scope of the claims. Now or hereafter associated with this document. For example, if there is any inconsistency or conflict between the description, definition, and / or use of terms associated with any of the included materials and the terms, descriptions, definitions, and / or of this document, the terms of this document shall prevail.

[0140] Finally, it should be understood that the embodiments of the application disclosed herein are illustrative of the principles of the embodiments of this specification. Other modified embodiments are also within the scope of this specification. Therefore, the embodiments disclosed in this specification are merely examples and not limitations. Those skilled in the art can adopt alternative configurations according to the embodiments in this specification to implement the application in this specification. Therefore, the embodiments of this specification are not limited to the embodiments precisely described in the application.

Claims

1. A preparation method of a furyl polyurethane material containing a Diels-Alder structure, characterized in that , including: Performing amidation reaction on furan methyl ester raw material and diethanolamine raw material to generate furan-based polyamide monomer; Performing amine-alcohol reaction on the furan-based polyamide monomer and polyisocyanate compound raw material to generate furan-based polyurethane monomer; and Performing Diels-Alder addition reaction on the furan-based polyurethane monomer and bismaleimide compound raw material to obtain the furan-based polyurethane material containing Diels-Alder structure.

2. The preparation method according to claim 1, wherein The amidation reaction and the amine-alcohol reaction include: Using the furan methyl ester, the diethanolamine and the polyisocyanate compound as raw materials in the same container, and sequentially performing the amidation reaction and the amine-alcohol reaction to obtain the furan-based polyurethane monomer.

3. The preparation method according to claim 1, wherein, The amidation reaction is carried out under vacuum conditions and in the presence of a catalyst.

4. The preparation method according to claim 1, wherein The amine-alcohol reaction is carried out under an inert gas atmosphere and in the presence of a catalyst.

5. The preparation method according to claim 1, characterized in that, The Diels-Alder addition reaction is carried out during the wire extrusion process.

6. The preparation method according to claim 1, wherein , in the amidation reaction, the molar ratio of the furan methyl ester raw material to the diethanolamine raw material is 0.5 - 2.

7. The preparation method according to claim 1, characterized in that , in the amidation reaction, the catalyst includes at least one of sodium hydroxide, potassium hydroxide or triethanolamine.

8. The preparation method according to claim 1, wherein , the reaction temperature of the amidation reaction is 30 - 150 °C, and its reaction time is 0.5 - 24 h.

9. The preparation method according to claim 8, characterized in that , the reaction temperature of the amidation reaction is 60 - 120 °C.

10. The preparation method according to claim 1, wherein , the polyisocyanate compound includes at least one of naphthalene diisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate, hexamethylene diisocyanate, hexamethylene diisocyanate, o-tolidine diisocyanate, xylylene diisocyanate, isophorone diisocyanate, trimethylhexane diisocyanate, m-xylylene diisocyanate, toluene 2,6-diisocyanate, triphenylmethane triisocyanate or trisocyanate (methyl)silane.

11. The preparation method according to claim 1, characterized in that , in the amine-alcohol reaction, the molar ratio of the hydroxyl group contained in the furan-based polyamide monomer to the isocyanate group in the polyisocyanate compound is 0.5 - 2.

12. The preparation method according to claim 4, wherein , the inert gas atmosphere includes at least one of nitrogen, helium or argon.

13. The preparation method according to claim 4, characterized in that , the catalyst includes at least one of dimethyltin stannate, dibutyltin stannate or butyllithium.

14. The preparation method according to claim 1, wherein , the reaction temperature of the amine-alcohol reaction is 30 - 80 °C, and its reaction time is 2 - 12 h.

15. The preparation method according to claim 1, wherein The bismaleimide compound includes at least one of bismaleimide, diphenyl ether bismaleimide, bismaleimide methyl ether, bismaleimide-hexaethylene glycol, N,N-(1,4-phenylene)bismaleimide, N-(4-methyl-1,3-phenylene)bismaleimide, 1,10-bis(maleimide)decane, 1,2-bis(maleimide)ethane or N-hydroxysuccinimide 3-maleimide propionate.

16. The preparation method according to claim 1, characterized in that, In the Diels-Alder addition reaction, the mass ratio of the furan-based polyurethane monomer to the bismaleimide compound is 0.5 - 1.

5.

17. The preparation method according to claim 5, characterized in that, The wire extrusion process uses the furanyl polyurethane monomer, the bismaleimide compound, and at least one additive. Wherein the additive includes a compatibilizer, a plasticizer, or any combination thereof. The mass ratio of the furanyl polyurethane monomer and the bismaleimide compound is 5-25%.

18. The preparation method according to claim 5, characterized in that, The wire extrusion process includes at least one of a single-screw processing process or a twin-screw processing process, with a processing temperature of 160-250°C and a processing time of 10-60 min.

19. A furyl polyurethane material containing a Diels-Alder structure, characterized in that, The furanyl polyurethane material is prepared according to any one of claims 1-18.

20. The furanyl polyurethane material according to claim 19, wherein The furanyl polyurethane material contains a furanyl polyurethane monomer having a structure of chemical formula (I): Wherein R is any one of the following groups, or its derivative structure: R1 is any one of the following groups, or its derivative structure:

21. Use of a furanyl polyurethane material containing a Diels - Alder structure in the field of extrusion - type 3D printing, characterized in that, The furanyl polyurethane material is prepared according to any one of claims 1-18, and the furanyl polyurethane material is used to be added to 3D printing wire to improve the interlayer strength.

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