Recyclable bio-based 3D printing resin composition and application thereof

Abstract

The invention provides a recyclable bio-based 3D printing resin composition and application thereof. The recyclable bio-based 3D printing resin composition is prepared from the following components in parts by weight: 60 to 75 parts of bio-based polyurethane resin, 15 to 40 parts of bio-based UV (Ultraviolet) reactive diluent, 5 to 15 parts of thiol compound and 0.3 to 5 parts of photoinitiator, the bio-based polyurethane resin comprises a polymer obtained by reaction of bio-based polyol, a polyisocyanate compound and a plant-based phenolic compound. On the basis of the special bio-based polyurethane resin, the bio-based UV reactive diluent, the thiol compound and the photoinitiator are matched, and meanwhile, the dosage of each bio-based component is controlled, so that all the components can be synergistically matched, and green synthesis of the 3D printing resin composition is realized. The obtained 3D printing resin composition not only can be rapidly cured depending on a thiol-ene reaction, but also can realize green recovery after curing.

Description

Technical Field

[0001] This invention relates to the field of 3D printing materials, and more specifically, to a recyclable bio-based 3D printing resin composition and its applications. Background Technology

[0002] UV curing technology, as a "green" manufacturing technology, achieves high precision and efficiency in the 3D printing process by initiating a rapid polymerization reaction of resin through light. The core of UV curing technology lies in photosensitive resin, which, under irradiation with ultraviolet light of a specific wavelength, rapidly transforms from a liquid to a solid state through a free radical polymerization reaction, forming complex three-dimensional structures. This technology is particularly suitable for manufacturing parts requiring high precision and for rapid prototyping. However, currently used UV-curing resins are mainly based on fossil fuel-derived polymers, such as polyesters, polyethers, and epoxy resins. The non-biodegradable and non-renewable nature of these polymers raises long-term environmental concerns.

[0003] Meanwhile, traditional 3D printing using photopolymer resins not only consumes non-renewable fossil resources, but also increases energy consumption if the resulting waste is disposed of. Discarded 3D-printed parts degrade slowly in the natural environment, leading to resource waste and environmental pollution. The accumulation of plastic waste, especially polymers that are difficult to recycle and degrade, exacerbates the global plastic pollution crisis. It is estimated that less than 10% of the plastic waste generated globally each year is recycled, with the majority ending up in the ocean or landfills, posing a serious threat to ecosystems and human health.

[0004] Furthermore, with continuous technological advancements, market demand for 3D printing materials is growing rapidly. Users not only require materials to possess high precision, rapid curing, and good mechanical properties, but also expect them to be low in toxicity, recyclable, and biodegradable. Particularly in the fields of green building and sustainable consumer goods manufacturing, the call for environmentally friendly materials is growing louder. This not only reflects society's pursuit of sustainable development but also sets higher standards for the future applications of 3D printing technology.

[0005] Therefore, how to provide a special printing resin composition that can achieve efficient and green recycling while meeting the requirements of rapid curing is one of the important technical problems that need to be solved in this field. Summary of the Invention

[0006] The main objective of this invention is to provide a recyclable bio-based 3D printing resin composition and its application, in order to solve the problem that existing photocurable 3D printing resin compositions cannot simultaneously achieve rapid printing and green recycling.

[0007] To achieve the above objectives, a first aspect of the present invention provides a recyclable bio-based 3D printing resin composition, comprising, by weight: 60-75 parts of bio-based polyurethane resin, 15-40 parts of bio-based UV reactive diluent, 5-15 parts of thiol compound, and 0.3-5 parts of photoinitiator; the bio-based polyurethane resin comprises a polymer obtained by reacting bio-based polyols, polyisocyanates, and plant-based phenolic compounds.

[0008] Furthermore, by weight, the recyclable bio-based 3D printing resin composition comprises: 60-65 parts of bio-based polyurethane resin, 15-35 parts of bio-based UV reactive diluent, 5-10 parts of thiol compound, and 1-3 parts of photoinitiator.

[0009] Furthermore, the thiol compound carries a thiol functional group, and the bio-based polyurethane resin carries a double bond functional group; wherein, the molar ratio of the thiol functional group to the double bond functional group is 1:(1.0~1.2).

[0010] Furthermore, the bio-based UV reactive diluent includes at least one of bio-based lauryl acrylate, isobornyl acrylate, and bio-based ethyl acrylate; and / or, the thiol compound includes at least one of pentaerythritol bis(3-mercaptopropionic acid), pentaerythritol tetra(3-mercaptopropionic acid), trimethylolpropane tris(mercaptoacetic acid), trimethylolpropane tris(3-mercaptopropionate), and dipentaerythritol hexa(3-mercaptopropionic acid); and / or, the photoinitiator includes 1-hydroxycyclohexylphenyl ketone, 2,4,6-trimethylbenzoyl At least one of the following: ethyl phosphonate, 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylphenylacetone, phenyl bis(2,4,6-trimethylbenzoyl)phosphine oxide, 1,1'-(methylenedi-4,1-phenylene)bis[2-hydroxy-2-methyl-1-propanone], 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, 2-methyl-1-(4-methylthiophenyl)-2-morpholino-1-propanone, 2-isopropylthioxanthone, and 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butanone.

[0011] Furthermore, the molar ratio of the hydroxyl groups carried by the bio-based polyol to the molar ratio of the polyisocyanate compound is (0.8–1.2):1; and / or, the molar ratio of the polyisocyanate compound to the molar ratio of the plant-based phenolic compound is 1:(0.8–1.2).

[0012] Furthermore, the polyisocyanate compounds include one or more of isophorone diisocyanate, hexamethylene diisocyanate, dimer fatty acid diisocyanate, toluene diisocyanate, diphenylmethane diisocyanate, dicyclohexylmethane diisocyanate, 3,3'-'-dimethyl-4,4'-biphenyl diisocyanate, and trimers of hexamethylene diisocyanate; and / or, the plant-based phenolic compounds include at least one of eugenol and cashew nut shellol; and / or, the bio-based polyols are synthesized from bio-based raw materials, and the bio-based raw materials include vegetable oils, animal fats, wood, pine... The oil comprises at least one of aromatic, sugary, cellulose-based agricultural by-products, and starchy crops; preferably, the vegetable oil is extracted from plants, and the plants include at least one of plant fruits, plant seeds, and plant germs; more preferably, the vegetable oil includes at least one of castor oil, rapeseed oil, palm oil, olive oil, soybean oil, and peanut oil; even more preferably, the bio-based polyol includes at least one of polylactic acid polyol, soybean oil polyol, castor oil polyol, palm oil polyol, olive oil polyol, rosin ester polyol, lignin polyol, and starch polyether polyol.

[0013] Furthermore, the preparation method of bio-based polyurethane resin includes: step S1, in which a polyisocyanate compound, a bio-based polyol and a catalyst undergo a first reaction to obtain an NCO-terminated prepolymer; step S2, in which the NCO-terminated prepolymer and a plant-based phenolic compound undergo a second reaction to obtain a bio-based polyurethane resin.

[0014] Further, in step S1, the reaction temperature of the first reaction is 60℃~70℃, and the reaction time is 3h~6h; and / or, in step S2, the reaction temperature of the second reaction is 50℃~60℃, and the reaction time is 1h~2h.

[0015] Furthermore, the catalyst includes at least one of triphenylbismuth, tris(ethoxyphenyl)bismuth, iron acetylacetonate, dibutyltin dilaurate, and triphenyltin chloride; and / or, based on the total weight of the polyisocyanate compound and the bio-based polyol, the amount of catalyst is 0.01% to 0.02%.

[0016] A second aspect of the present invention provides a method for preparing a three-dimensional object, comprising: irradiating the above-mentioned recyclable bio-based 3D printing resin composition with an ultraviolet light source in the wavelength range of 365nm to 425nm to form a three-dimensional object.

[0017] Furthermore, the method for preparing a three-dimensional object further includes: step (1), providing a light source module capable of emitting light, and simultaneously providing a molding module having a molding platform and an optically transparent component, the optically transparent component having a construction surface, the molding platform and the construction surface defining a construction area, the molding platform being used to support the three-dimensional object; step (2), filling the construction area with a recyclable bio-based 3D printing resin composition; step (3), controlling the molding platform to move to a designated position in the construction area; step (4), using the light source module to emit light, and causing the light to pass through the optically transparent component to irradiate the construction area, so as to cure at least a portion of the recyclable bio-based 3D printing resin composition; step (5), controlling the molding platform to move away from the construction surface; step (6), repeating steps (2) to (5) to form a three-dimensional object.

[0018] A third aspect of the present invention provides a product prepared according to the above-described method for preparing a three-dimensional object, the product including any one of the following: footwear, sports protective gear, toys, and equipment parts.

[0019] By applying the technical solution of this invention, based on a special bio-based polyurethane resin, combined with a bio-based UV-active diluent, thiol compounds, and a photoinitiator, and by controlling the amount of each bio-based component, the components can work synergistically to achieve the green synthesis of a 3D printing resin composition. The resulting 3D printing resin composition can not only be rapidly cured through a thiol-olefin reaction, but can also be greenly recycled after curing. Attached Figure Description

[0020] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0021] Figure 1 This is a schematic diagram of the structure of a device for forming a three-dimensional object, provided in an embodiment of the present invention.

[0022] The above figures include the following reference numerals:

[0023] 11. Molding platform; 12. Optically transparent component; 13. Light source module; 14. Three-dimensional object; 121. Construction surface; 122. Photocurable material. Detailed Implementation

[0024] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the embodiments.

[0025] As described in the background section, existing photopolymer 3D printing resin compositions suffer from the inability to simultaneously achieve rapid printing and green recycling. To address this technical problem, a first aspect of the present invention provides a recyclable bio-based 3D printing resin composition, comprising, by weight: 60-75 parts of bio-based polyurethane resin, 15-40 parts of bio-based UV reactive diluent, 5-15 parts of thiol compound, and 0.3-5 parts of photoinitiator; the bio-based polyurethane resin comprises a polymer obtained by reacting bio-based polyols, polyisocyanates, and plant-based phenolic compounds.

[0026] This invention is based on a special bio-based polyurethane resin, combined with a bio-based UV-active diluent, thiol compounds and photoinitiators. By controlling the amount of each bio-based component, a high-performance recyclable bio-based 3D printing resin composition (hereinafter referred to as the resin composition) is obtained.

[0027] To avoid ambiguity, it should be stated in advance that the polyisocyanate compounds used in this invention are essentially isocyanate compounds with a functionality of ≥2.

[0028] In the resulting recyclable bio-based 3D printing resin composition, the key role of the bio-based polyurethane resin lies in the introduction of plant oil-based polyols and plant-based phenolic end-capping agents, both derived from renewable biomass, enhancing the material's sustainability. The reaction of the polyol with isocyanate forms the polyurethane backbone, while the presence of the phenolic end-capping agent imparts additional functionality to the material, improving its photocuring efficiency and recyclability. The bio-based UV reactive diluent plays a role in reducing viscosity, increasing flowability, and accelerating the photocuring reaction rate, ensuring smooth 3D printing and rapid prototyping of the printed object. The introduction of thiol compounds forms a thiol-ene reaction system with the unsaturated double bonds in the bio-based polyurethane resin. This reaction pathway not only avoids the oxygen inhibition problem commonly found in traditional photocuring but also promotes rapid curing and reduces deformation during printing.

[0029] The resulting 3D printing resin composition can be rapidly cured by relying on the thiol-olefin reaction, while significantly reducing dependence on fossil resources and enabling green recycling after curing.

[0030] To further optimize the printing performance and economy of the obtained resin composition, and to improve its curing speed while taking into account cost and environmental benefits, the recyclable bio-based 3D printing resin composition preferably includes, by weight, 60-65 parts of bio-based polyurethane resin, 15-35 parts of bio-based UV reactive diluent, 5-10 parts of thiol compound and 1-3 parts of photoinitiator.

[0031] In the recyclable bio-based 3D printing resin composition provided by this invention, the thiol compound carries a thiol functional group, and the bio-based polyurethane resin carries a double bond functional group. To better achieve high efficiency of the thiol-olefin reaction system during subsequent curing, eliminate the oxygen inhibition effect, accelerate the curing rate, improve the structural integrity of the material, and reduce the increase in brittleness caused by excessive crosslinking, the preferred molar ratio of thiol functional groups to double bond functional groups is 1:(1.0~1.2).

[0032] In several preferred embodiments, the bio-based UV reactive diluent includes at least one of bio-based lauryl acrylate, isobornyl acrylate, and bio-based ethyl acrylate; and / or, the thiol compound includes at least one of pentaerythritol bis(3-mercaptopropionic acid), pentaerythritol tetra(3-mercaptopropionic acid), trimethylolpropane tris(mercaptoacetic acid), trimethylolpropane tris(3-mercaptopropionate), and dipentaerythritol hexa(3-mercaptopropionic acid); and / or, the photoinitiator includes 1-hydroxycyclohexylphenyl ketone and 2,4,6-trimethylbenzene. At least one of the following: ethyl formylphosphonate, 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylphenylacetone, phenyl bis(2,4,6-trimethylbenzoyl)phosphine oxide, 1,1'-(methylenedi-4,1-phenylene)bis[2-hydroxy-2-methyl-1-propanone], 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, 2-methyl-1-(4-methylthiophenyl)-2-morpholino-1-propanone, 2-isopropylthioxanthone, and 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butanone. The preferred bio-based UV diluent described above can more effectively reduce the viscosity of the composition and improve its flowability during the printing process; the preferred thiol compound further enhances the toughness of the cured resin material product, improves its impact resistance, and allows the printed parts to better maintain their good physical state in complex usage environments.

[0033] Regarding the aforementioned bio-based UV reactive diluents, in practical applications, bio-based lauryl acrylate can be used as an example of IGMresins. 4812; bio-based ethyl acrylate can be BASF BMBISCC Plus; isoborneol acrylate can be Zhanxin. IBOA, in which the bio-based source is: the isoborneol group is synthesized from bio-based raw materials (such as α-pinene) such as turpentine oil, and the bio-based content can reach 77%. In addition, the bio-based UV reactive diluent can also be selected from GMEC monomer produced by Osaka Organic Chemical Industry Co., Ltd., namely methyl 2-oxo-1,3-dioxolane-4-yl)isobutylenoate (CAS: 13818-44-5, which contains more than 30% bio-based components.

[0034] Furthermore, in order to promote a more complete and balanced synthesis reaction of bio-based polyurethane resin, reduce potential side reactions, and improve reaction yield, product purity, curing rate, and stability of the cured parts, the preferred ratio of the molar amount of hydroxyl groups carried by the bio-based polyol to the molar amount of the polyisocyanate compound is (0.8-1.2):1 during its preparation.

[0035] To make the reaction more controllable, reduce the problems of excessive resin stiffness due to excessive isocyanate or insufficient curing due to excessive phenolic end-capping agent, improve the efficiency of the urethane bond formation process, thereby enhancing the overall performance of the obtained bio-based polyurethane resin and giving it better recyclability, the molar ratio of polyisocyanate compounds to plant-based phenolic compounds is preferably 1:(0.8-1.2). If the amount of plant-based phenolic compounds used as end-capping agents is too low, the retained NCO groups are prone to react with water in the air. Therefore, to improve the storage stability of the obtained resin composition, the molar ratio of polyisocyanate compounds to plant-based phenolic compounds is further preferably 1:(0.9-1.1).

[0036] In several preferred embodiments, the polyisocyanate compounds include one or more of isophorone diisocyanate, hexamethylene diisocyanate, dimer fatty acid diisocyanate, toluene diisocyanate, diphenylmethane diisocyanate, dicyclohexylmethane diisocyanate, 3,3'-'-dimethyl-4,4'-biphenyl diisocyanate, and a trimer of hexamethylene diisocyanate (CAS No. 3779-63-3). Isophorone diisocyanate and hexamethylene diisocyanate, in particular, exhibit superior reactivity and functionality during urethane bond formation due to their unique chemical structures, significantly improving the curing efficiency of the resulting bio-based resin. For bio-based polyols, it is preferred that they are synthesized from biological raw materials, and the biological raw materials include at least one of the following: vegetable oil, animal fat, wood, rosin, sugar crops (which can provide fermentation sugar sources, such as sugarcane and sugar beets), cellulosic agricultural by-products (i.e., non-grain biomass resources, such as corn stalks), and starch crops (such as corn, cassava, and wheat); and preferably, the vegetable oil is extracted from plants, and the plants include at least one of the following: plant fruits, plant seeds, and plant germs.

[0037] Specifically, the bio-based polyols synthesized from biological raw materials used in this invention essentially have their synthetic raw materials derived from biological sources. More specifically, the bio-based polyols preferably include at least one of polylactic acid polyol (derived from corn stalks), soybean oil polyol (derived from soybean oil), castor oil polyol (derived from castor oil), palm oil polyol (derived from palm oil), olive oil polyol (derived from olive oil), rosin ester polyol (derived from rosin), lignin polyol (derived from lignin), and starch polyether polyol (derived from starchy crops), in order to significantly improve the biodegradability, flexibility, and antioxidant properties of the resulting bio-based polyurethane resin. Further, the plant-based phenolic compounds preferably include at least one of eugenol and cashew phenol. Due to their natural environmental friendliness and the presence of phenolic hydroxyl groups, these plant-based phenolic compounds not only contribute to the formation of dynamic urethane bonds but also significantly improve the weather resistance and recyclability of the resulting bio-based polyurethane resin.

[0038] In practical applications, the synthesis steps for starch polyether polyols include: starch saccharification followed by fermentation to prepare methyl glucoside or other liquefied products, and then ring-opening polymerization with propylene oxide / ethane in the presence of a catalyst to synthesize starch polyether polyols. The selection of starch-based agricultural crops is very diverse, including most crops such as corn, cassava, and wheat.

[0039] Furthermore, the preferred method for preparing the bio-based polyurethane resin includes: step S1, where a polyisocyanate compound, a bio-based polyol, and a catalyst undergo a first reaction to obtain an NCO-terminated prepolymer; step S2, where the NCO-terminated prepolymer and a plant-based phenolic compound undergo a second reaction to obtain the bio-based polyurethane resin. In this preparation process, the reaction between the isocyanate and the bio-based polyol forms the basic bio-based polyurethane framework, while the introduction of plant-based phenols as end-capping agents increases the recyclability of the resin. The reaction route in the above preparation process is shown below (using the plant-based phenolic compound cashew nut shell as an example).

[0040]

[0041] In the preparation of bio-based polyurethane resin, for the first reaction in step S1, the preferred reaction temperature is 60℃~70℃ and the reaction time is 3h~6h, thereby more effectively promoting the binding between isocyanate and polyol, forming a more stable prepolymer skeleton. In step S2, the preferred reaction temperature for the second reaction is 50℃~60℃ and the reaction time is 1h~2h, so as to promote a more complete reaction of the phenolic end-capping agent, further improving the recyclability, processability, and stability of the obtained bio-based polyurethane resin after curing.

[0042] In several preferred embodiments, in order to better balance the reaction rate and the properties of the resulting bio-based polyurethane resin and reduce side reactions, the catalyst preferably includes at least one of triphenylbismuth, tris(ethoxyphenyl)bismuth, iron acetylacetone, dibutyltin dilaurate, and triphenyltin chloride; and / or, based on the total weight of the polyisocyanate compound and the bio-based polyol as 100%, the amount of catalyst is 0.01% to 0.02%.

[0043] In several particularly preferred embodiments, the recyclable bio-based 3D printing resin composition comprises, by weight, 60 parts of bio-based polyurethane resin, 31 parts of isoborneol acrylate, 8 parts of pentaerythritol tetrakis(3-mercaptobutyrate) ester, and 2 parts of photoinitiator. The bio-based polyurethane resin comprises a polymer obtained by reacting polylactic acid polyol, isophorone diisocyanate, and cashew nut phenol, wherein the molar ratio of the hydroxyl groups carried by the polylactic acid polyol, the molar amount of isophorone diisocyanate, and the molar amount of cashew nut phenol is 1:1. 1; or, by weight, the recyclable bio-based 3D printing resin composition comprises: 60 parts of bio-based polyurethane resin, 28.6 parts of bio-based lauryl acrylate, 9.4 parts of dipentaerythritol hexa(3-mercaptopropionic acid) ester, and 2 parts of photoinitiator. The bio-based polyurethane resin comprises a polymer obtained by reacting soybean oil polyol, hexamethylene diisocyanate, and eugenol, wherein the molar ratio of the hydroxyl groups carried by the soybean oil polyol, the molar ratio of the hexamethylene diisocyanate, and the molar ratio of the eugenol is 1:1:1. Based on the above, the inventors, through extensive experiments, have optimized the specific formulations of these two recyclable bio-based 3D printing resin compositions. In the resulting resin compositions, the synergistic effect between the components can be better exerted, thereby significantly improving the curing efficiency of the resin composition. Furthermore, because the components possess better environmental friendliness and compatibility, better green recycling can be achieved after the above two resin compositions are cured.

[0044] A second aspect of this invention provides a method for preparing a three-dimensional object, comprising: irradiating the aforementioned recyclable bio-based 3D printing resin composition with an ultraviolet light source in the wavelength range of 365 nm to 425 nm to form a three-dimensional object. Because the resin composition of this invention uses raw materials with high bio-based content, such as bio-based polyols and plant-based phenolic end-capping agents containing unsaturated groups, these components exhibit excellent performance during photocuring. Furthermore, the introduction of phenolic hydroxyl groups into the phenolic end-capping agent further enhances the stability and durability of the resulting cured product. More importantly, the bio-based nature of the resin composition means that the three-dimensional object formed after curing has good recyclability, thanks to the reversible urethane bonds in the composite material. When recycling is required, the urethane bonds can be decomposed through an appropriate chemical process (such as adding a specific end-capping agent and heating at a certain temperature) to restore the original resin composition (the reaction route of this process is shown below, taking the plant-based phenolic compound cashew nut shell as an example), without consuming large amounts of organic solvents or complex refining processes, achieving efficient and environmentally friendly recycling.

[0045]

[0046] In several typical implementations, the method for preparing a three-dimensional object further includes: step (1), providing a light source module capable of emitting light, and simultaneously providing a molding module with a molding platform and an optically transparent component, the optically transparent component having a construction surface, defining a construction area between the molding platform and the construction surface, the molding platform being used to support the three-dimensional object; step (2), filling the construction area with a recyclable bio-based 3D printing resin composition; step (3), controlling the molding platform to move to a designated position in the construction area; step (4), using the light source module to emit light, and allowing the light to pass through the optically transparent component to irradiate the construction area, so as to cure at least a portion of the recyclable bio-based 3D printing resin composition; step (5), controlling the molding platform to move away from the construction surface; step (6), repeating steps (2) to (5) to form a three-dimensional object. The above more specific preparation process, through a refined operating procedure, combined with the characteristics of bio-based recyclable resin, significantly improves the quality and preparation efficiency of the printed product, while also further reducing energy consumption and the complexity of subsequent processing.

[0047] A third aspect of the present invention provides a product prepared according to the above-described method for preparing three-dimensional objects, the product including any one of the following: footwear, sports protective gear, toys, and equipment parts. Because the above-described recyclable bio-based 3D printing resin composition obtained by the present invention has a high bio-based content and good recyclability, the printed products not only meet diverse needs but also possess both environmental and economic advantages.

[0048] The present application will be further described in detail below with reference to specific embodiments, which should not be construed as limiting the scope of protection claimed in the present application.

[0049] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.

[0050] Example 1

[0051] 1. A recyclable bio-based 3D printing resin composition:

[0052] Preparation of bio-based polyurethane resin:

[0053] (1) Polylactic acid polyol (i.e., bio-based polyol, the raw material of which comes from corn stalks and is produced by Fengyuan Group), isophorone diisocyanate (i.e., polyisocyanate compound), and dibutyltin dilaurate (i.e., catalyst) are added to the reactor. The molar ratio of the hydroxyl groups carried by the polylactic acid polyol to the molar ratio of the isophorone diisocyanate is 1:1; the amount of dibutyltin dilaurate catalyst added is 0.01% of the total weight of polylactic acid polyol and isophorone diisocyanate. After the three are mechanically stirred evenly, the mixture is heated to 70°C and reacted for 5 hours. The NCO% is titrated and tested. Once the theoretical value is reached, the NCO-terminated prepolymer is obtained.

[0054] (2) Cashew nut shellac (i.e., plant-based phenolic compound) was added to the reactor as a capping agent, with a molar ratio of 1:1 to isophorone diisocyanate. The reaction was continued at 50°C for 2 hours. After the reaction was completed, a highly bio-based polyurethane resin containing dynamic urethane bonds was obtained.

[0055] A recyclable bio-based 3D printing resin composition was prepared by mixing the following ingredients: 60g of the highly bio-based polyurethane resin containing dynamic bonds prepared above, 8g of pentaerythritol tetrakis(3-mercaptobutyrate), 31g of isobornyl acrylate (IBOA), and 1g of photoinitiator TPO were mixed evenly to obtain the recyclable bio-based 3D printing resin composition. In the obtained recyclable bio-based 3D printing resin composition, the molar ratio of the mercapto functional groups carried by the thiol compound to the molar ratio of the double bond functional groups carried by the bio-based polyurethane resin was 1:1.

[0056] 2. Preparation of three-dimensional resin samples:

[0057] Adopting such Figure 1 The printing device shown (specifically, the UltraCraft A2D HD model) is used to print standard test strips. The specific steps are as follows:

[0058] Step (1): A light source module capable of emitting light is provided, and a molding module is provided with a molding platform and an optically transparent component having a construction surface. The optically transparent component has a construction surface, and a construction area is defined between the molding platform and the construction surface. The molding platform is configured to support a three-dimensional object. The light is ultraviolet light with a wavelength of 365-425nm. The optically transparent component is a release film.

[0059] Step (2): Fill the construction area with the obtained photosensitive resin composition;

[0060] Step (3): Control the molding platform to move to the specified position in the building area;

[0061] Step (4): Use the light emitted by the light source module and let the light pass through the optically transparent component to illuminate the construction area to cure at least a portion of the resin composition;

[0062] Step (5): Control the molding platform away from the build surface;

[0063] Step (6): Repeat steps (2) to (5) to form the initial three-dimensional object;

[0064] Step (7): After cleaning, standard test strips are obtained.

[0065] Example 2

[0066] 1. A recyclable bio-based 3D printing resin composition:

[0067] Preparation of bio-based polyurethane resin:

[0068] (1) Soybean oil polyol (i.e., bio-based polyol, raw material from soybean oil, Shanghai Gaowei Co., Ltd., model SD-100), hexamethylene diisocyanate (i.e., polyisocyanate compound), and dibutyltin dilaurate (i.e., catalyst) were added to the reactor. The molar ratio of the hydroxyl groups carried by the soybean oil polyol to the molar ratio of hexamethylene diisocyanate was 1:1; the amount of dibutyltin dilaurate catalyst added was 0.01% of the total weight of polylactic acid polyol and isophorone diisocyanate. After mechanically stirring the three together, the mixture was heated to 60°C and reacted for 4 hours. The NCO% was titrated and tested. Once the theoretical value was reached, the NCO-terminated prepolymer was obtained.

[0069] (2) Eugenol (i.e., a plant-based phenolic compound) was added to the reactor as a capping agent, with a molar ratio of eugenol to hexamethylene diisocyanate of 1:1. The reaction was continued at 60°C for 2 hours. After the reaction was completed, a highly bio-based polyurethane resin containing dynamic urethane bonds was obtained.

[0070] The ingredients were prepared and mixed to obtain a recyclable bio-based 3D printing resin composition: 60g of the above-prepared highly bio-based polyurethane resin containing dynamic bonds, 9.4g of dipentaerythritol hexa(3-mercaptopropionic acid) ester, and bio-based lauryl acrylate (IGMResins) were mixed. 28.6g of 4812 and 2g of photoinitiator TPO were mixed evenly to obtain a recyclable bio-based 3D printing resin composition. In the obtained recyclable bio-based 3D printing resin composition, the molar ratio of the mercapto functional group carried by the thiol compound to the molar ratio of the double bond functional group carried by the bio-based polyurethane resin was 1:1.

[0071] 2. Preparation of three-dimensional resin samples: consistent with that in Example 1.

[0072] Example 3

[0073] 1. A recyclable bio-based 3D printing resin composition:

[0074] The only difference between this embodiment and Embodiment 1 is that:

[0075] In the process of preparing and mixing the ingredients to obtain the recyclable bio-based 3D printing resin composition, the amount of each component was changed to: 75g of bio-based polyurethane resin, 15g of isoborneol acrylate, 9g of pentaerythritol tetrakis(3-mercaptobutyric acid) ester and 1g of photoinitiator TPO.

[0076] 2. Preparation of three-dimensional resin samples: consistent with that in Example 1.

[0077] Example 4

[0078] 1. A recyclable bio-based 3D printing resin composition:

[0079] The only difference between this embodiment and Embodiment 1 is that:

[0080] In step (1) of preparing bio-based polyurethane resin, the molar ratio of the hydroxyl groups carried by the bio-based polyol to the molar ratio of the polyisocyanate compound is 0.5:1.

[0081] 2. Preparation of three-dimensional resin samples: consistent with that in Example 1.

[0082] Example 5

[0083] 1. A recyclable bio-based 3D printing resin composition:

[0084] The only difference between this embodiment and Embodiment 1 is that:

[0085] In step (1) of preparing bio-based polyurethane resin, the molar ratio of the hydroxyl groups carried by the bio-based polyol to the molar ratio of the polyisocyanate compound is 2:1.

[0086] 2. Preparation of three-dimensional resin samples: consistent with that in Example 1.

[0087] Example 6

[0088] 1. A recyclable bio-based 3D printing resin composition:

[0089] The only difference between this embodiment and Embodiment 1 is that:

[0090] In step (1) of preparing bio-based polyurethane resin, the reaction temperature was changed to 50°C and the reaction time was changed to 8h.

[0091] 2. Preparation of three-dimensional resin samples: consistent with that in Example 1.

[0092] Example 7

[0093] 1. A recyclable bio-based 3D printing resin composition:

[0094] The only difference between this embodiment and Embodiment 1 is that:

[0095] In step (1) of preparing bio-based polyurethane resin, the reaction temperature was changed to 80°C and the reaction time was changed to 2h.

[0096] 2. Preparation of three-dimensional resin samples: consistent with that in Example 1.

[0097] Example 8

[0098] 1. A recyclable bio-based 3D printing resin composition:

[0099] The only difference between this embodiment and Embodiment 1 is that:

[0100] In step (2) of preparing bio-based polyurethane resin, the molar ratio of the polyisocyanate compound to the plant-based phenolic compound is 1:0.5.

[0101] 2. Preparation of three-dimensional resin samples: consistent with that in Example 1.

[0102] Example 9

[0103] 1. A recyclable bio-based 3D printing resin composition:

[0104] The only difference between this embodiment and Embodiment 1 is that:

[0105] In step (2) of preparing bio-based polyurethane resin, the molar ratio of the polyisocyanate compound to the plant-based phenolic compound is 1:2.

[0106] 2. Preparation of three-dimensional resin samples: consistent with that in Example 1.

[0107] Example 10

[0108] 1. A recyclable bio-based 3D printing resin composition:

[0109] The only difference between this embodiment and Embodiment 1 is that:

[0110] In step (2) of preparing bio-based polyurethane resin, the reaction temperature was changed to 40°C and the reaction time was changed to 3h.

[0111] 2. Preparation of three-dimensional resin samples: consistent with that in Example 1.

[0112] Comparative Example 1

[0113] 1. A recyclable bio-based 3D printing resin composition:

[0114] The only difference between this comparative example and Example 2 is that:

[0115] In the preparation of bio-based polyurethane resin, an equal weight of polyoxypropylene polyol (PPG) is used instead of polylactic acid polyol.

[0116] That is, this comparative ratio did not use plant-based polyols.

[0117] 2. Preparation of three-dimensional resin samples: consistent with that in Example 2.

[0118] Comparative Example 2

[0119] 1. A recyclable bio-based 3D printing resin composition:

[0120] The only difference between this comparative example and Example 2 is that:

[0121] In the preparation of the bio-based polyurethane resin, an equal weight of 4-vinylphenol was used instead of eugenol. That is, no plant-based phenolic compounds were used in this comparative example.

[0122] 2. Preparation of three-dimensional resin samples: consistent with that in Example 1.

[0123] Comparative Example 3

[0124] 1. A recyclable bio-based 3D printing resin composition:

[0125] The only difference between this comparative example and Example 1 is that:

[0126] In the process of preparing and mixing the ingredients to obtain the recyclable bio-based 3D printing resin composition, the amount of each component was changed to: 80 parts of bio-based polyurethane resin, 10 parts of isoborneol acrylate, 3 parts of pentaerythritol tetrakis(3-mercaptobutyric acid) ester and 0.1 parts of photoinitiator TPO.

[0127] 2. Preparation of three-dimensional resin samples: consistent with that in Example 1.

[0128] Comparative Example 4

[0129] 1. A recyclable bio-based 3D printing resin composition:

[0130] The only difference between this comparative example and Example 1 is that:

[0131] In the process of preparing and mixing the ingredients to obtain the recyclable bio-based 3D printing resin composition, the amount of each component was changed to: 50 parts of bio-based polyurethane resin, 50 parts of isoborneol acrylate, 20 parts of pentaerythritol tetrakis(3-mercaptobutyric acid) ester, and 5 parts of photoinitiator TPO.

[0132] 2. Preparation of three-dimensional resin samples: consistent with that in Example 1.

[0133] Curing speed test:

[0134] The light intensity is 21 W / m 2 Under the given conditions, the printing times used in the 3D printing process of the resin compositions obtained in the above comparative examples and embodiments when the printing layer thickness was 0.100 mm, 0.120 mm, 0.150 mm and 0.180 mm, respectively, are shown in Table 1.

[0135] Table 1

[0136]

[0137] Recyclability performance test:

[0138] The printed products obtained from the above embodiments are pulverized and added to a certain mass of end-capping agent, then heated and stirred at 90°C for 5 hours. During the heating process, the dynamic bonds formed during curing break and recombine, yielding the recycled photosensitive composition. Compared to conventional material recycling methods that require large amounts of organic solvents and cumbersome steps of dissolution, re-distillation, and purification, this recycling method is simpler and more environmentally friendly and energy-efficient.

[0139] Taking the photocurable product of the eugenol bio-based resin composition in Example 2 as an example, the printed product was pulverized and ball-milled into powder, and eugenol, the end-capping agent, was added. The weight ratio of the added eugenol to the sample powder was 1:1. To increase solubility, an additional eugenol bio-based resin composition before curing could be added, with a mass three times the total weight of the eugenol and sample powder. After stirring and mixing evenly, the temperature was raised to 90°C, and stirring was continued for 5 hours to obtain the recovered eugenol bio-based resin composition. The recovered bio-based resin composition, when used under the same printing conditions, can still produce photocurable products of good quality.

[0140] As can be seen from the above description, compared with the comparative examples, the embodiments of the present invention achieve the preparation of a resin composition with superior performance. The obtained 3D printing resin composition can not only be rapidly cured by the thiol-ene reaction, but also achieve green recycling after curing.

[0141] Compared to comparative examples or existing technologies, the obtained resin compositions in each embodiment not only achieve rapid curing but also enable full green recycling after curing. Furthermore, in each embodiment, Examples 1 to 3 represent preferred conditions obtained under the current conditions, exhibiting faster curing rates and superior performance of the resulting parts. Specifically, in Example 4, the molar amount of the polyisocyanate compound was slightly higher; although the printing time did not change significantly, the storage stability and recyclability of the resulting resin composition showed a decreasing trend. In Example 5, the molar amount of hydroxyl groups carried by the bio-based polyol was slightly higher, resulting in excess end-capping agents with polymerization inhibitory effects, thus slightly increasing the printing time. Therefore, by comparing Examples 4 and 5 with Example 1, it can be seen that the preferred ratio of the molar amount of hydroxyl groups carried by the bio-based polyol to the molar amount of the polyisocyanate compound better promotes a more complete and balanced synthesis reaction of the bio-based polyurethane resin, reduces potential side reactions, and improves reaction yield, product purity, curing rate, and resin composition stability.

[0142] The curing time of the resin composition obtained in Example 6 increased slightly; although the curing time of the resin composition obtained in Example 7 decreased, the viscosity actually increased. Therefore, it can be seen that the preferred temperature and time of the first reaction in step S1 can more effectively promote the effective combination between isocyanate and polyol, forming a more stable prepolymer skeleton, and ultimately improving the processability of the obtained resin composition.

[0143] Examples 8 and 9 respectively reduced and increased the amount of plant-based phenolic compounds, resulting in a slight increase in the curing rate of the resin compositions obtained in both examples. Meanwhile, the storage stability of the resin composition obtained in Example 8 decreased slightly, and the mechanical properties of the parts obtained in Example 9 also decreased slightly compared to Example 1, but they still meet the requirements for various applications and are superior to existing technologies. Therefore, it can be seen that optimizing the molar ratio of polyisocyanate compounds to plant-based phenolic compounds allows for more controllable reactions, improves the efficiency of the urethane bond formation process, thereby enhancing the overall performance of the obtained bio-based polyurethane resin and also giving it better recyclability.

[0144] The printing time of the resin composition obtained in Example 10 was also slightly longer, while the storage stability of the resin composition was slightly affected. This change may be due to a decrease in the end-capping rate in the second reaction. Therefore, it is known that a reaction temperature of 50°C to 60°C in the second reaction can promote a more complete reaction of the phenolic end-capping agent, further improving the recyclability, processability, and stability of the cured bio-based polyurethane resin composition.

[0145] Regarding the comparative examples: Comparative Example 1 used PPG instead of bio-based polyols. Although the printing and curing rate of the resulting resin composition was almost unaffected, the environmental properties were significantly reduced due to the substantial decrease in the bio-based raw material content. Comparative Example 2 used 4-vinylphenol instead of eugenol. Although the printing time of the resulting resin composition was basically the same as in Example 2, 4-vinylphenol, as a hindered phenol, has a weaker steric hindrance effect than eugenol. Although it can still form dynamic bonds, the recycling efficiency is significantly reduced, and the resulting parts cannot be effectively recycled. In Comparative Example 3, the proportions of each component were changed, especially the initiator content, which was too low, resulting in a significant decrease in the curing rate, making it almost unusable. In Comparative Example 4, an excessive amount of photoinitiator was added, which was unsuitable for the resulting resin composition system, producing a light-shielding effect. The printing time also increased, making it difficult to apply in practice.

[0146] It should be noted that the terms "first," "second," etc., used in the specification and claims of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such terms can be used interchangeably where appropriate so that the embodiments of this application described herein can be implemented, for example, in a sequence other than those described herein.

[0147] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A recyclable bio-based 3D printing resin composition, characterized in that, The recyclable bio-based 3D printing resin composition comprises, by weight, 60-75 parts of bio-based polyurethane resin, 15-40 parts of bio-based UV reactive diluent, 5-15 parts of thiol compound, and 0.3-5 parts of photoinitiator. The bio-based polyurethane resin includes polymers obtained by reacting bio-based polyols, polyisocyanates, and plant-based phenolic compounds.

2. The recyclable bio-based 3D printing resin composition according to claim 1, characterized in that, The recyclable bio-based 3D printing resin composition comprises, by weight, 60-65 parts of the bio-based polyurethane resin, 15-35 parts of the bio-based UV-active diluent, 5-10 parts of the thiol compound, and 1-3 parts of the photoinitiator.

3. The recyclable bio-based 3D printing resin composition according to claim 1 or 2, characterized in that, The thiol compound carries a thiol functional group, and the bio-based polyurethane resin carries a double bond functional group. The molar ratio of the mercapto functional group to the molar ratio of the double bond functional group is 1:(1.0 to 1.2).

4. The recyclable bio-based 3D printing resin composition according to any one of claims 1 to 3, characterized in that, The bio-based UV reactive diluent includes at least one of bio-based lauryl acrylate, isoborneol acrylate, and bio-based ethyl acrylate; and / or, The thiol compound includes at least one selected from pentaerythritol bis(3-mercaptopropionic acid), pentaerythritol tetra(3-mercaptopropionic acid), trimethylolpropane tris(mercaptoacetic acid), trimethylolpropane tris(3-mercaptopropionate), and dipentaerythritol hexa(3-mercaptopropionic acid); and / or, The photoinitiator includes at least one selected from 1-hydroxycyclohexylphenyl ketone, ethyl 2,4,6-trimethylbenzoylphosphonate, 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylphenylacetone, phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, 1,1'-(methylenedi-4,1-phenylene)bis[2-hydroxy-2-methyl-1-propanone], 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, 2-methyl-1-(4-methylthiophenyl)-2-morpholino-1-propanone, 2-isopropylthioxanthraphenone, and 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butanone.

5. The recyclable bio-based 3D printing resin composition according to any one of claims 1 to 4, characterized in that, The molar ratio of the hydroxyl groups carried by the bio-based polyol to the molar ratio of the polyisocyanate compound is (0.8–1.2):1; and / or, The molar ratio of the polyisocyanate compound to the plant-based phenolic compound is 1: (0.8～1.2)。 6. The recyclable bio-based 3D printing resin composition according to any one of claims 1 to 5, characterized in that, The polyisocyanate compounds include one or more of the following: isophorone diisocyanate, hexamethylene diisocyanate, dimer fatty acid diisocyanate, toluene diisocyanate, diphenylmethane diisocyanate, dicyclohexylmethane diisocyanate, 3,3'-'-dimethyl-4,4'-biphenyl diisocyanate, and trimers of hexamethylene diisocyanate; and / or, The plant-based phenolic compounds include at least one of eugenol and cashew phenol; and / or, The bio-based polyol is synthesized from biological raw materials, and the biological raw materials include at least one of vegetable oil, animal fat, wood, rosin, sugar crops, cellulosic agricultural by-products, and starch crops. Preferably, the vegetable oil is extracted from plants, and the plants include at least one of plant fruits, plant seeds, and plant embryos; More preferably, the vegetable oil includes at least one of castor oil, rapeseed oil, palm oil, olive oil, soybean oil, and peanut oil; More preferably, the bio-based polyol includes at least one of polylactic acid polyol, soybean oil polyol, castor oil polyol, palm oil polyol, olive oil polyol, rosin ester polyol, lignin polyol, and starch polyether polyol.

7. The recyclable bio-based 3D printing resin composition according to any one of claims 1 to 6, characterized in that, The preparation method of the bio-based polyurethane resin includes: Step S1: The polyisocyanate compound, the bio-based polyol, and the catalyst undergo a first reaction to obtain an NCO-terminated prepolymer. In step S2, the NCO-terminated prepolymer and the plant-based phenolic compound undergo a second reaction to obtain the bio-based polyurethane resin.

8. The recyclable bio-based 3D printing resin composition according to claim 7, characterized in that, In step S1, the reaction temperature of the first reaction is 60℃~70℃, and the reaction time is 3h~6h; and / or, In step S2, the reaction temperature of the second reaction is 50℃~60℃, and the reaction time is 1h~2h.

9. The recyclable bio-based 3D printing resin composition according to claim 7 or 8, characterized in that, The catalyst comprises at least one of triphenylbismuth, tris(ethoxyphenyl)bismuth, iron acetylacetonate, dibutyltin dilaurate, and triphenyltin chloride; and / or, The amount of catalyst used is 0.01% to 0.02% based on the total weight of the polyisocyanate compound and the bio-based polyol, which is 100%.

10. A method for preparing a three-dimensional object, characterized in that, include: The three-dimensional object is formed by irradiating the recyclable bio-based 3D printing resin composition of any one of claims 1 to 9 with an ultraviolet light source in the wavelength range of 365nm to 425nm.

11. The method for preparing a three-dimensional object according to claim 10, characterized in that, The method for preparing the three-dimensional object further includes: Step (1): Provide a light source module capable of emitting light, and provide a molding module with a molding platform and an optically transparent component. The optically transparent component has a construction surface, and a construction area is defined between the molding platform and the construction surface. The molding platform is used to support a three-dimensional object. Step (2): Fill the build area with the recyclable bio-based 3D printing resin composition; Step (3): Control the molding platform to move to a designated position in the building area; Step (4): Use the light source module to emit light and allow the light to pass through the optically transparent component to irradiate the construction area to cure at least a portion of the recyclable bio-based 3D printing resin composition; Step (5): Control the molding platform away from the building surface; Step (6) is to repeat steps (2) through (5) to form the three-dimensional object.

12. A product prepared by the method of preparing a three-dimensional object according to claim 10 or 11, the product comprising any one of the following: footwear, sports protective gear, toys, and equipment parts.

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