3D printing biodegradable high-toughness polycaprolactone photosensitive resin and preparation method thereof

Abstract

The invention discloses biodegradable high-toughness polycaprolactone photosensitive resin for 3D printing and a preparation method of the biodegradable high-toughness polycaprolactone photosensitive resin. The photosensitive resin is prepared by mixing the following raw materials in percentage by mass: 45-60% of a polycaprolactone acrylate prepolymer, 40-55% of a reactive diluent and 1-3% of a free radical photoinitiator. The molecular weight of the acrylate prepolymer is 500-3000, and the preparation method of the prepolymer comprises the following steps: adding raw materials including polycaprolactone and isocyanate into a reaction kettle, slowly dropwise adding a catalyst in the presence of nitrogen, adding a chain extender into the system when the concentration of an NCO group stops decreasing, reacting until the NCO group completely disappears, and adding acrylic acid for blocking. The photocuring 3D printing resin based on the polycaprolactone is constructed by preparing the polycaprolactone oligomer PCA containing unsaturated double bonds and optimizing a photosensitive resin formula system. The 3D printing material has relatively high tensile strength and elongation at break due to interaction of a skeleton formed by combining soft and hard segments of the prepolymer and covalent crosslinking, hydrogen bonds and the like among the copolymers.

Description

Technical Field

[0001] The invention belongs to the field of biodegradable light-cured high-toughness polycaprolactone materials, and relates to a light-cured 3D-printed high-strength and toughness polycaprolactone resin applicable to medical protective gear and a preparation method thereof. Background Art

[0002] In the modern medical field, medical braces play a vital role in the rehabilitation treatment of patients. Traditional materials for making medical braces, such as plaster, metal, leather, and natural fiber fabrics, have many limitations. For example, they are heavy in texture and poor in air permeability, which can easily cause skin allergies and discomfort in patients, and they are difficult to adjust after their shape is fixed. The application of polymer materials such as low-temperature thermoplastic plates makes the manufacturing process of braces products more scientific and more in line with the requirements of human anatomy and kinematics. However, most of these materials cannot have both high mechanical strength and high toughness, and traditional manufacturing processes cannot meet the needs of complex structures and personalized customization. In addition, polymer materials cannot achieve automatic degradation, and landfill or incineration cannot avoid the pollution problem of polymer materials.

[0003] With the increasing awareness of environmental protection and the in-depth pursuit of sustainable development, biodegradable materials have become a research hotspot in the field of materials science. Polycaprolactone, as a biodegradable polyester polymer material, has good biocompatibility, low toxicity and processability, and shows great application potential in the field of biomedical engineering, such as tissue engineering scaffolds and drug sustained-release carriers. However, traditional polycaprolactone materials have certain limitations in mechanical properties, and their strength and toughness often cannot meet the requirements of some complex structures and high-performance application scenarios. This has prompted researchers to devote themselves to the development of new polycaprolactone-based materials to improve their mechanical properties while retaining their biodegradable properties.

[0004] The emergence of photocuring 3D printing technology has provided a new opportunity for the modification and high performance of polycaprolactone materials. The preparation of materials that can use photocuring 3D printing technology to achieve rapid customized manufacturing of complex structures and surpass traditional polymer materials in mechanical properties will open up a new path for the cross-integration of biomedical engineering and 3D printing materials, and promote the development of related fields in a greener, more efficient and high-performance direction. Summary of the invention

[0005] In view of the problems that traditional medical protective gear materials cannot have both high mechanical strength and high toughness, are non-degradable, and cannot meet the needs of complex structures and personalized customization. In order to overcome the technical defects in the prior art, the present invention is based on the most widely used degradable linear aliphatic polyester, and its molecular structure is modified to synthesize polycaprolactone prepolymer. By compounding polycaprolactone with specific photosensitizers, monomers and other additives, a biodegradable light-cured 3D printing polycaprolactone resin and a preparation method thereof are provided.

[0006] In order to achieve the above-mentioned invention object, this application provides the following technical solutions:

[0007] First aspect:

[0008] A biodegradable high-strength polycaprolactone resin that can be used in light-curing 3D printing technology, which is composed of a mixture of the following raw materials in percentage by mass: 45-60% of a polycaprolactone prepolymer, 40-55% of a reactive diluent, and 1-3% of a free radical photoinitiator;

[0009] The molecular weight of the polycaprolactone prepolymer is 800-3000, and the structural formula of the polycaprolactone prepolymer is:

[0010]

[0011] Wherein, the number of n is 5 to 20,

[0012] R 1 The structure includes One or more of

[0013] R 2 The structure includes One or more of R 3 The structure includes One or more of .

[0014] Preferably, the preparation method of the polycaprolactone prepolymer is:

[0015] (1) uniformly mixing polycaprolactone and isocyanate, adding a catalyst, and heating to a reaction temperature;

[0016] (2) measuring the isocyanate content, waiting until the concentration no longer decreases, and lowering the temperature;

[0017] (3) adding a chain extender dropwise and continuing to raise the temperature until the isocyanate groups are completely reacted;

[0018] (4) adding a solvent, mixing the polymerization inhibitor and the end-capping agent, and refluxing to separate the water;

[0019] (5) washing and extracting, removing the solvent, and obtaining the reaction product.

[0020] The raw materials for preparing the polycaprolactone prepolymer include, by mass percentage, 0.1-0.5wt% of a catalyst, 0.1-1wt% of a polymerization inhibitor, 30-50wt% of a solvent, and the remainder being polycaprolactone, isocyanic acid, a small molecule polyol, and acrylic acid; wherein the molar ratio of polycaprolactone, isocyanic acid, polyol, and acrylic acid is 1:2:2:(3-5).

[0021] Preferably, the raw materials for preparing the polycaprolactone prepolymer include, by mass percentage: 0.1wt% catalyst, 0.3wt% inhibitor, and the remainder polycaprolactone, isocyanic acid, polyol and acrylic acid, wherein the molar ratio of polycaprolactone, isocyanic acid, polyol and acrylic acid is 1:2:2:3.

[0022] The catalyst is 0.3wt%, the inhibitor is 0.2wt%, and the balance is polycaprolactone, isocyanic acid, polyol and acrylic acid, wherein the molar ratio of polycaprolactone, isocyanic acid, polyol and acrylic acid is 1:2:2:4.

[0023] Preferably, the catalyst is one or more of dimethyltin dichloride, dibutyltin dilaurate mercaptan, dibutyltin dilaurate, dibutyltin diacetate, and dibutyltin maleate;

[0024] The isocyanic acid is one of isophorone diisocyanate (IPDI), toluene diisocyanate (TDI), and hexamethylene diisocyanate (HDI);

[0025] The chain extender is one of glycerol, trimethylolpropane (TMP) and pentaerythritol;

[0026] The polymerization inhibitor is one or both of p-hydroxyanisole and hydroquinone;

[0027] Preferably, the reaction temperature in step (1) is controlled at 60-80° C., and the reaction time is 2-4 h;

[0028] The temperature of the system in steps (2) and (3) is reduced to 45-50°C, preferably 50°C, and the reaction time is 1-2h. During the process, the reaction is monitored based on the isocyanate content;

[0029] The temperature of the system in step (4) is 70-90° C., the reaction time is 4-6 hours, and the reaction is monitored based on the acid value of the system.

[0030] Preferably, the free radical photoinitiator is diphenyl-(2,4,6-trimethylbenzoyl)phosphine oxide, Irgacure 819 or phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide XBPO.

[0031] Preferably, the active diluent is one or a combination of 2-hydroxyhexyl acrylate HEA, N-vinyl pyrrolidone NVP, isobornyl acrylate IBOA, 1,6-hexanediol diacrylate (HDDA), 2-phenoxyethyl acrylate 2-PEA, 3,3,5-trimethylcyclohexanol acrylate TMCHA, trimethylolpropane formal acrylate CTFA and acryloyl morpholine ACMO.

[0032] Preferably, the preparation method of the 3D printing biodegradable high-toughness polycaprolactone photosensitive resin comprises the following steps:

[0033] 1) preparing a polycaprolactone acrylate prepolymer having an unsaturated double bond;

[0034] 2) Weighing the raw material components constituting the 3D printing light-curable resin material according to the weight ratio; pre-dispersing the free radical photoinitiator and the active diluent in a light-proof plane at the same time, and then adding the remaining materials and stirring to obtain a homogeneous liquid, which is the 3D printing light-curable resin material.

[0035] Preferably, the preparation method of the polycaprolactone acrylate prepolymer having unsaturated double bonds described in step 1) comprises the following steps:

[0036] 1.1) Add polycaprolactone and isocyanate into a four-necked round-bottom flask equipped with a mechanical stirrer, a thermometer and a dropping funnel at room temperature and stir at 200 r / min;

[0037] 1.2) Slowly drop the catalyst into the flask under nitrogen atmosphere. After the dropwise addition, the temperature rises to 70°C and the reaction is continued for 2 to 4 hours.

[0038] 1.3) Continuously monitor the NCO group composition of the reactants using Fourier transform infrared spectroscopy (FT-IR);

[0039] 1.4) When the absorption peak of the NCO group stops decreasing, the reaction temperature is reduced to 50°C, and a chain extender small molecule polyol is added dropwise to the reactants to continue the reaction for 1 to 2 hours;

[0040] 1.5) After the NCO absorption peak disappears, acrylic acid is added for end-capping, and 0.1% of inhibitor MEHQ is added to prevent the double bond polymerization in the oligomer. The temperature is raised to 90°C and the reaction is continued for 5 hours;

[0041] 1.6) When the acid value in the system no longer decreases, the reaction is terminated, and the extracted product is washed and dried to obtain a transparent viscous liquid PCA oligomer.

[0042] Second aspect:

[0043] With polycaprolactone and isocyanate as the soft segment and hard segment in the molecular structure, acrylate end-capping is used to prepare the light-curable polycaprolactone prepolymer. The synthesis process is as follows:

[0044]

[0045] Compared with the prior art, the present invention has the following beneficial effects:

[0046] Based on this oligomer, the present invention obtains a photosensitive resin with both high strength and toughness by combining it with a series of biosafe diluents. Due to the synergistic effect of the highly cross-linked polymer network, the rigidity of the isocyanate and the flexible long chain of polycaprolactone, the 3D printing material exhibits expected mechanical properties, with a tensile strength of more than 45MPa, an elongation at break greater than 100%, and a flexural strength of more than 35MPa and a flexural modulus of more than 1000MPa. The photosensitive resin is suitable for DLP and SLA 3D printers, and samples can be printed under 365nm and 405nm ultraviolet rays. The photocurable material exhibits low cytotoxicity to (L929) cells and has no skin irritation to animals.

[0047] The medical brace designed and successfully printed by the present invention exhibits high printing accuracy, and has the advantages of being non-toxic, non-irritating, light, having good memory, being easy to shape, being breathable, light and comfortable, similar to low-temperature thermoplastic plates, and having comprehensive mechanical properties far exceeding those of low-temperature thermoplastic plates. The excellent mechanical properties and biocompatibility of the material will provide more options for the development of customized medical brace materials, while improving wearing comfort and extending its service life. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0049] Figure 1 It is made of polycaprolactone 1 H NMR spectrum;

[0050] Figure 2 The prepared polycaprolactone prepolymer 1 H NMR spectrum;

[0051] Figure 3 It is the infrared spectrum of the raw material and the synthesized prepolymer;

[0052] Figure 4 It is the GPC characterization spectrum of the prepared prepolymer;

[0053] Figure 5 It is the tensile and bending strain curves of the 3D printed specimen;

[0054] Figure 6 It is the thermogravimetric and DMA curves of the 3D printed sample;

[0055] Figure 7 It is the cell activity graph of different extracts;

[0056] Figure 8 It is a schematic diagram of cell fluorescence staining;

[0057] Fig. 9 It is the fracture surface morphology of the sample under the scanning electron microscope. DETAILED DESCRIPTION

[0058] The present application is further described below in conjunction with specific embodiments. The following are only a few embodiments of the present application, and are not intended to limit the present application in any form. Although the present application discloses the following preferred embodiments, they are not intended to limit the present application. Any technician familiar with the profession, without departing from the scope of the technical solution of the present application, using the above disclosed technical content to make some changes or modifications are equivalent to equivalent implementation cases and are within the scope of the technical solution.

[0059] Unless otherwise specified, the raw materials in the examples of the present application were purchased from commercial sources and used directly without any special treatment.

[0060] Unless otherwise specified, the analysis methods in the examples all adopt conventional settings and conventional analysis methods of instruments or equipment.

[0061] Mechanical property test: The prepared acrylate prepolymer is added with active diluent to form a light-curable resin, which is cured into dumbbell-shaped splines using a DLP light engine. The mechanical properties of the samples are tested using a universal testing machine (UT-2080). The test is carried out in accordance with GB / T528-2009, with a fixture spacing of 25mm, a spline width of 5mm, a thickness of 2±0.2mm, and a tensile rate of 10mm / min. The bending strength and bending modulus of the material are tested in accordance with GB / T9341-2008, with a spline width of 10mm, a thickness of 4mm, a span of 64mm, and a bending rate of 5mm / min.

[0062] Example 1

[0063] 166g of isophorone diisocyanate IPDI, 0.73g of catalyst DBTDL and 80ml of solvent cyclohexane were added to a four-necked round-bottom flask equipped with a mechanical stirrer, a thermometer, and a constant pressure dropping funnel. After that, 300g of polycaprolactone diol (Mn=830) was slowly added to the flask under nitrogen protection and stirred at 200r / min. After the addition was completed, the temperature was raised to 70°C for 2 hours. Fourier transform infrared spectroscopy (FT-IR) was used to continuously monitor the NCO group composition of the reactants. When 2266cm -1 When the absorption peak intensity of the NCO group stops decreasing, the reaction temperature is lowered to room temperature, and 102g of pentaerythritol is added to the reactants. After reacting at 50°C for 1 hour, the NCO absorption peak is detected by FT-IR. After the NCO absorption peak disappears, 112.5g of acrylic acid is added for end-capping, and 3.62g of inhibitor MEHQ is added to prevent the double bond polymerization in the oligomer. The reaction is terminated when the acid value of the system no longer decreases, and the solvent is removed by a rotary evaporator at 45°C to obtain a transparent viscous liquid PCA oligomer. The polycaprolactone raw material ( Figure 1 ) and the product ( Figure 2 ) was characterized, and the chemical shifts of the methylene in polycaprolactone were 1.29ppm, 1.68ppm and 2.25ppm, and the peak at 7.39ppm was -NH. In addition, the peaks at 5.80ppm, 6.05ppm and 6.45ppm were attributed to -CH=CH of acrylate. 2 This indicates that the isocyanate group and double bond have been successfully introduced into the molecular structure of polycaprolactone.

[0064] Example 2

[0065] Compared with Example 1, the only difference is that the molecular weight of polycaprolactone is changed, and other conditions are the same as those in Example 1. The specific operation is as follows:

[0066] At room temperature, 500 g of raw material polycaprolactone (Mn=2000) and 0.8 g of DBTDL were added to a four-necked round-bottom flask equipped with a mechanical stirrer, a thermometer and a dropping funnel. After that, 111 g of IPDI was slowly added to the flask under nitrogen protection and stirred at 200 r / min. After the IPDI was added, the temperature was raised to 70°C and stirred for 2 hours. The isocyanate groups in the system were titrated according to standard HG / T 2409-92. When the amount of NCO groups stopped decreasing, the reaction temperature was reduced to 50°C and 68 g of PET was added to the reactants. After 1 hour of reaction, the NCO absorption peak was detected using FT-IR. After the NCO absorption peak disappeared, 108 g of AA was added for end-capping, and 6.24 g of inhibitor MEHQ was added to prevent double bond polymerization. Reflux and separate the water until the acid value of the system no longer decreases, extract, wash and dry the product, and vacuum degassing to obtain a white paste-like liquid PCA oligomer.

[0067] GPC test results are as follows Figure 4 As shown, the number average molar mass (Mn) and weight average molar mass (Mw) of PCA-2000 oligomer are 2531 kg / mol and 2988 kg / mol, respectively. The value of (Mw / Mn) is 1.18, and polymerization does not occur during the reaction, and the molecular weight distribution is narrow.

[0068] Example 3

[0069] The method is the same as in Example 1, except that the functionality of the end-capping agent is different. Other conditions are the same as in Example 1. The specific operation is as follows:

[0070] At room temperature, 111 g of isophorone diisocyanate IPDI and 0.8 g of DBTDL were added to a four-necked round-bottom flask equipped with a mechanical stirrer, a thermometer and a dropping funnel. After that, polycaprolactone (Mn=2000) was slowly added to the flask under a nitrogen atmosphere and stirred at 200 r / min. After the addition, the temperature was raised to 70°C and stirred for 2 hours. The isocyanate groups in the system were titrated according to standard HG / T 2409-92. When the amount of NCO groups stopped decreasing, the reaction temperature was reduced to 50°C, and 46 g of chain extender glycerol was added to the reactants. After reacting for 1 hour, the NCO absorption peak was detected using FT-IR. After the NCO absorption peak disappeared, 80 g of AA and 0.7 g of MEHQ were added, and the water was separated by reflux at 90°C until the acid value of the system was no longer reduced, the reaction was terminated, the product was extracted, washed and dried, and vacuum degassed to obtain a white viscous liquid PCA oligomer. The obtained product was characterized by infrared spectroscopy ( Figure 3 ), 1727cm in the spectrum -1 The absorption peak of C=O represents the characteristic peak of ester group. -1 The C=C stretching vibration peak at 2266cm -1 There is no characteristic peak of NCO group, indicating that -NCO and -OH have reacted completely.

[0071] Product Example 4

[0072] A light-curable high-strength polycaprolactone resin material comprises the following raw materials in percentage by mass: 50% prepolymer, 15% 2-phenoxyethyl acrylate, 33% N-vinyl pyrrolidone, 1.5% free radical photoinitiator, 0.2% fluorescent brightener and 0.3% antioxidant.

[0073] The prepolymer is the polycaprolactone PCA prepared in Example 1.

[0074] The free radical photoinitiator is Irgacure 819.

[0075] The fluorescent whitening agent is KCB.

[0076] The antioxidant is 1010.

[0077] Weigh the raw materials according to the weight ratio of each raw material component, pre-disperse the solid free radical photoinitiator powder and the active diluent in the dark for 15 minutes, then add the other raw materials and stir them together at 30°C to obtain a homogeneous liquid.

[0078] Product Example 5

[0079] Compared with product embodiment 4, the only difference is that the composition ratio is different, and other conditions are the same as those of product embodiment 4. The specific operation is as follows:

[0080] A photocurable 3D printing high-strength and tough polycaprolactone resin material comprises the following raw materials in percentage by weight: 55% prepolymer, 42% acryloylmorpholine, 2.5% free radical photoinitiator, and 0.5% auxiliary agent.

[0081] The prepolymer is a mixture of the polycaprolactone prepared in Example 1 and the polycaprolactone prepared in Example 2 in a mass ratio of 3:1.

[0082] The free radical photoinitiator is TPO-L.

[0083] The auxiliary agent is antioxidant 168.

[0084] Weigh the raw materials according to the weight ratio of each raw material component, pre-disperse the solid free radical photoinitiator powder and the active diluent in the dark for 15 minutes, then add the other raw materials and stir them together at 60°C to obtain a homogeneous liquid.

[0085] Product Example 6

[0086] A formulation of a high-strength and tough polycaprolactone resin for photocuring 3D printing: 45wt% of active diluent and 2wt% of TPO-L are added to a brown light-proof plate at the same time, stirred by magnetic force for 15 minutes, and then 53wt% of the product in Example 3 is added, stirred for 30 minutes, and bubbles are removed by ultrasonic wave to obtain a photocurable resin. The obtained photocurable resin is cured by a DLP photocuring engine, and the mechanical properties of the cured specimens are measured.

[0087] Table 1 Material mechanical properties test results

[0088]

[0089] In order to evaluate the mechanical strength and toughness, the mechanical properties of the materials were measured and the results are shown in Figure 5As shown in Table 1. The polycaprolactone material provided by the present invention has excellent toughness, tensile properties and fatigue resistance. Because it has a unique skeleton structure of alternating HS and SS segments and microphase separation, the mechanical properties of the photopolymer are improved, including high strength and excellent tensile properties. The resin components form an interpenetrating network during the photocuring process, which makes it have both strength and toughness.

[0090] like Figure 6 The thermal performance results show that it will not soften or deform over a wide temperature range. Biocompatibility testing is a key step in evaluating the toxicity of materials in biomedical applications. Good biocompatibility is also an essential condition for wearable devices.

[0091] like Figure 7 As shown in the figure, the samples were extracted with the widely used DMEM high-glucose medium and the highly soluble DMSO, and the results showed that even at a high concentration of 10 mg / mL, the cell viability was still higher than 80%. Figure 8 It can be seen that most cells survived in the high-concentration samples and showed a similar proliferation trend compared with the control group.

[0092] like Fig. 9 As shown, electron microscopy observation of the impact surface of the 3D printed sample showed a ductile fracture trend, proving that the resin material has both strength and impact toughness. Based on the high biocompatibility of the 3D printing material, its potential application in the medical field can be foreseen.

[0093] The above are only a few embodiments of the present application and do not constitute any form of limitation to the present application. Although the present application is disclosed as above with preferred embodiments, it is not intended to limit the present application. Any technician familiar with the profession, without departing from the scope of the technical solution of the present application, using the technical content disclosed above to make slight changes or modifications are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A 3D printing biodegradable high-toughness polycaprolactone photosensitive resin, characterized in that: According to mass percentage, it is prepared from the following raw materials: Polycaprolactone prepolymer 45-60%; Active diluent 40-55%; Free radical photoinitiator 1-3%; The molecular weight of the polycaprolactone prepolymer is 500-3000, and the structural formula of the polycaprolactone prepolymer is: Wherein, the number of n is 5 to 20, The structure of R1 includes One or more of; The structure of R2 includes One or more of; The structure of R3 includes One or more of .

2. A 3D printing biodegradable high-toughness polycaprolactone photosensitive resin according to claim 1, characterized in that: The preparation method of the polycaprolactone prepolymer is: (1) uniformly mixing polycaprolactone and isocyanate, adding a catalyst, and heating to a reaction temperature; (2) measuring the isocyanate content, waiting until the concentration no longer decreases, and lowering the temperature; (3) adding a chain extender dropwise and continuing to raise the temperature until the isocyanate groups are completely reacted; (4) adding a solvent, mixing the polymerization inhibitor and the end-capping agent, and refluxing to separate the water; (5) washing and extracting to remove the solvent to obtain a reaction product; The raw materials for preparing the polycaprolactone prepolymer include, by mass percentage: Catalyst 0.1-0.5wt%; Inhibitor 0.1-1wt%; Solvent 30-50wt%; The balance is polycaprolactone, isocyanic acid, small molecule polyol and acrylic acid; wherein the molar ratio of polycaprolactone, isocyanic acid, small molecule polyol and acrylic acid is 1:2:2:(3-5).

3. A 3D printing biodegradable high-toughness polycaprolactone photosensitive resin prepolymer according to claim 2, characterized in that: Calculated by mass percentage, the raw materials for preparing the polycaprolactone prepolymer include: 0.1wt% of catalyst, 0.3wt% of inhibitor, and the remainder is polycaprolactone, isocyanic acid, small molecule polyol and acrylic acid, wherein the molar ratio of polycaprolactone, isocyanic acid, polyol and acrylic acid is 1:2:2:

3.

4. A 3D printing biodegradable high-toughness polycaprolactone photosensitive resin prepolymer according to claim 2, characterized in that: Calculated by mass percentage, the raw materials for preparing the polycaprolactone prepolymer include: 0.3wt% of catalyst, 0.2wt% of inhibitor, and the balance is polycaprolactone, isocyanic acid, polyol and acrylic acid, wherein the molar ratio of polycaprolactone, isocyanic acid, polyol and acrylic acid is 1:2:2:

4.

5. The 3D printing biodegradable high-toughness polycaprolactone photosensitive resin prepolymer according to any one of claims 2 to 4, characterized in that: The catalyst is one or more of dimethyltin dichloride, dibutyltin dilaurate mercaptan, dibutyltin dilaurate, dibutyltin diacetate, and dibutyltin maleate; The isocyanic acid is one of isophorone diisocyanate (IPDI), toluene diisocyanate (TDI), and hexamethylene diisocyanate (HDI); The chain extender is one of glycerol, trimethylolpropane (TMP) and pentaerythritol; the polymerization inhibitor is one or both of p-hydroxyanisole and hydroquinone.

6. The 3D printing biodegradable high-toughness polycaprolactone photosensitive resin prepolymer according to claim 2, characterized in that: In step (1), the reaction temperature is controlled at 60-80° C. and the reaction time is 2-4 h; In steps (2) and (3), the temperature of the system is reduced to 45-50° C., and the reaction time is 1-2 h; In step (4), the temperature of the system is 70-90° C., the reaction time is 4-6 hours, and the reaction is monitored based on the acid value of the system.

7. The 3D printing biodegradable high-toughness polycaprolactone photosensitive resin according to claim 1, characterized in that: The free radical photoinitiator is (2,4,6-trimethylbenzoyl) diphenylphosphine oxide TPO-L, Irgacure LAP or phenyl bis (2,4,6-trimethylbenzoyl) phosphine oxide XBPO.

8. The 3D printing biodegradable high-toughness polycaprolactone photosensitive resin according to claim 1, characterized in that: The active diluent is one or a combination of 2-hydroxyhexyl acrylate HEA, N-vinyl pyrrolidone NVP, isobornyl acrylate IBOA, 1,6-hexanediol diacrylate (HDDA), 2-phenoxyethyl acrylate 2-PEA, 3,3,5-trimethylcyclohexanol acrylate TMCHA, trimethylolpropane formal acrylate CTFA and acryloyl morpholine ACMO.

9. A method for preparing the 3D printing biodegradable high-toughness polycaprolactone photosensitive resin according to claim 1, characterized in that The steps include: 1) preparing a polycaprolactone acrylate prepolymer having an unsaturated double bond; 2) Weighing the raw material components constituting the 3D printing light-curable resin material according to the weight ratio; pre-dispersing the free radical photoinitiator and the active diluent in a light-proof bottle at the same time, and then adding the remaining materials and stirring to obtain a homogeneous liquid, which is the 3D printing light-curable resin material.

10. The method for preparing 3D printing biodegradable high-toughness polycaprolactone photosensitive resin according to claim 9, characterized in that: The preparation method of the polycaprolactone acrylate prepolymer having unsaturated double bonds described in step 1) comprises the following steps: 1.1) Add polycaprolactone and isocyanate into a four-necked round-bottom flask equipped with a mechanical stirrer, a thermometer and a dropping funnel at room temperature and stir at 200 r / min; 1.2) Slowly add the catalyst to the flask under nitrogen atmosphere. After the addition, the temperature rises to 70°C and reacts for 2 to 4 hours; 1.3) Continuously monitor the NCO group composition of the reactants using Fourier transform infrared spectroscopy (FT-IR); 1.4) When the absorption peak of the NCO group stops decreasing, the reaction temperature is reduced to 50°C, and a chain extender small molecule polyol is added dropwise to the reactants to continue the reaction for 1 to 2 hours; 1.5) After the NCO absorption peak disappears, acrylic acid is added for end-capping, and 0.1% of inhibitor MEHQ is added to prevent the double bond polymerization in the oligomer. The temperature is raised to 90°C and the reaction is continued for 5 hours; 1.6) When the acid value in the system no longer decreases, the reaction is terminated, and the extracted product is washed and dried to obtain a transparent viscous liquid PCA oligomer.

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