Modified polylactic acid composite photosensitive resin for photocuring 3D printing and preparation method thereof

Abstract

The invention discloses a modified polylactic acid composite photosensitive resin for photocuring 3D printing and a preparation method thereof.The modified polylactic acid composite photosensitive resin comprises, by mass, 65-75% of photosensitive telechelic oligomeric lactic acid, 0.5-5% of a photoinitiator and 20-30% of a diluent, the photosensitive telechelic oligomeric lactic acid takes L-lactic acid as a main body, the L-lactic acid and chelating center molecules are subjected to dehydration polymerization, and then the photoinitiator and the diluent are added into the photosensitive telechelic oligomeric lactic acid to obtain the modified polylactic acid composite photosensitive resin for photocuring 3D printing. And grafting vinyl grafted molecules to the end group. The chelating center molecule is one of succinic acid, trimesic acid and ethylenediaminetetraacetic acid, uniformly mixing, and storing in a dark place. The modified PLA composite photosensitive resin has good photosensitivity, can be effectively applied to a DLP photocuring 3D printing technology, keeps excellent biocompatibility and degradability of PLA, is superior to a PLA product printed by traditional FDM in the aspects of printing precision, surface smoothness and mechanical performance, and is good in mechanical performance and thermal stability.

Description

Technical Field

[0001] The present invention belongs to the technical field of biodegradable materials, and in particular relates to a modified polylactic acid composite photosensitive resin for photocurable 3D printing and a preparation method thereof. Background Art

[0002] Polylactic acid (PLA) is a biodegradable polymer widely used in the packaging and medical industries. Due to its excellent biocompatibility and degradability, it has great potential in bio-scaffolds and drug delivery systems. However, traditional manufacturing methods and high costs limit its application, resulting in most bio-scaffold products being standardized, and customized products being rare and expensive. Given the diversity of patient needs, personalized stent products are more in line with their specific needs.

[0003] With the advancement of 3D printing technology, it is increasingly possible to achieve low-cost customized products. In particular, personalized customization of PLA through 3D printing technology has attracted widespread attention. At present, fused deposition modeling (FDM) is the main 3D printing technology for processing PLA. It heats PLA filaments to the melting point and then builds objects layer by layer. However, the products printed by FDM have a rough surface, low precision, slow printing speed, and low efficiency, which is not ideal in the field of biological scaffolds.

[0004] In contrast, digital light processing (DLP) printing technology is known for its high precision and high efficiency, and can print products with smooth surfaces and rich details, effectively overcoming the shortcomings of FDM technology. However, due to the lack of photoactive groups in the PLA molecular structure, it cannot be directly used in the photocuring process.

[0005] At present, in order to improve the photosensitivity of PLA, the methods of introducing photoinitiators or adding other photosensitive resins are usually adopted. However, these methods often lead to the degradation of the mechanical properties of the material or the generation of toxicity, which limits its application in the biomedical field.

[0006] Therefore, developing a new modified polylactic acid composite photosensitive resin for photocurable 3D printing with good photosensitivity while maintaining the excellent properties of PLA is of great significance for promoting the application of 3D printing technology in the biomedical field. Summary of the invention

[0007] In view of this, the object of the present invention is to provide a modified polylactic acid composite photosensitive resin for photocuring 3D printing and a preparation method thereof. The prepared modified polylactic acid composite photosensitive resin has good photosensitivity, maintains the excellent biocompatibility and degradability of PLA, and the product has good mechanical properties and good thermal stability.

[0008] In order to achieve the above object, the present invention provides the following technical solutions:

[0009] A modified polylactic acid composite photosensitive resin for photocuring 3D printing, comprising the following components by mass fraction:

[0010] Photosensitive telechelic oligolactic acid 65-75%;

[0011] Photoinitiator 0.5-5%;

[0012] Diluent 20-30%;

[0013] The photosensitive telechelic oligolactic acid is mainly composed of L-lactic acid, which is dehydrated and polymerized with a chelating center molecule and then end-grafted with a vinyl grafted molecule; the chelating center molecule is one of succinic acid (DBP), trimesic acid (BTC), and ethylenediaminetetraacetic acid (EDTA).

[0014] Preferably, the photoinitiator is one of IRGACURE819, diphenyl-(2,4,6-trimethylbenzoyl)phosphine oxide (TPO) and camphorquinone.

[0015] Preferably, the diluent is one of N-vinyl pyrrolidone, monofunctional styrene (St), vinyl pyrrolidone (NVP), vinyl acetate (VA), butyl acrylate (BA), isooctyl acrylate (EHA), hydroxy (meth)acrylate (HEA, HEMA, HPA), difunctional 1,6-hexanediol diacrylate (HDDA), tripropylene glycol diacrylate (TPGDA), neopentyl glycol diacrylate (NPGDA), and multifunctional trimethylolpropane triacrylate (TMPTA).

[0016] Preferably, the vinyl grafted molecule is one of glycidyl methacrylate or acrylic anhydride.

[0017] Preferably, the molar ratio of the L-lactic acid, the chelating core molecule and the vinyl grafted molecule is 1:40:5.

[0018] Preferably, the preparation process of the photosensitive telechelic oligomeric lactic acid is as follows: L-lactic acid and a chelating center molecule are added into a reactor, and then toluene with water is added, and the mixture is reacted at 90°C and 100°C for 1 hour respectively, and then the catalyst stannous octoate is added. After the reactor is evacuated to a vacuum, the mixture is reacted at 120°C and 140°C for 2 hours respectively, and then the mixture is heated to 160°C for 20 hours, and finally the mixture is cooled to 120°C, and a vinyl grafted molecule is added and reacted for 4 hours to obtain photosensitive telechelic oligomeric lactic acid.

[0019] The present invention also provides a method for preparing the modified polylactic acid composite photosensitive resin for light-curing 3D printing, which comprises mixing the components evenly and storing them away from light.

[0020] The advantages of the present invention are:

[0021] The modified PLA composite photosensitive resin of the present invention has good photosensitivity and can be effectively applied to DLP light-curing 3D printing technology. At the same time, it maintains the excellent biocompatibility and degradability of PLA. It is superior to traditional FDM printed PLA products in printing accuracy, surface smoothness and mechanical properties. The product has good mechanical properties and good thermal stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 The DSC curves of the photosensitive oligomeric lactic acid prepared in Example 2, Example 3 and Comparative Example 1 are shown. DETAILED DESCRIPTION

[0023] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0024] Example 1

[0025] A modified polylactic acid composite photosensitive resin for photocurable 3D printing: the mass fraction of photosensitive telechelic oligolactic acid is 72.5%; the mass fraction of photoinitiator is 1.0%; the mass fraction of diluent is 26.5%. Among them, the chelating center molecule is succinic acid (SA), the vinyl grafted molecule is glycidyl methacrylate, the diluent is N-vinyl pyrrolidone (NVP), and the photoinitiator is IRGACURE 819.

[0026] 1. A method for preparing a photosensitive telechelic oligolactic acid, comprising the following steps:

[0027] First, the chelating center molecule and L-lactic acid were added to a three-necked round-bottom flask at a molar ratio of 1:40, and toluene with water was added. The reaction was carried out at 90°C and 100°C for 1 hour each, and then the catalyst stannous octoate was added. After the circulating water vacuum pump was turned on and evacuated to vacuum, the reaction was carried out at 120°C and 140°C for 2 hours each, and then the temperature was raised to 160°C for 20 hours, and then the temperature was lowered to 120°C, and the vinyl grafted molecule (L-lactic acid: vinyl grafted molecule = 1:5) was added and the reaction was continued for 4 hours to finally obtain photosensitive telechelic oligomeric lactic acid.

[0028] 2. A method for preparing a modified polylactic acid composite photosensitive resin for photocurable 3D printing, comprising uniformly mixing photosensitive telechelic oligolactic acid, a photoinitiator and a diluent according to a formula ratio for 20 minutes and storing the mixture away from light to obtain a modified polylactic acid composite photosensitive resin for photocurable 3D printing.

[0029] 3. 3D printing process: put the modified polylactic acid composite photosensitive resin for light-curing 3D printing into the 3D printer for 3D printing, wherein the 3D printer is a Magic Cube Precision DLP-3D printer, the light source of the 3D printer is an ultraviolet light source: the wavelength is 540nm, the printing speed of the 3D printer is 1mm / s, the printing accuracy of the 3D printer is 0.01mm, the printing layer thickness of the 3D printer is 0.073mm, and the printing temperature of the 3D printer is room temperature.

[0030] Example 2

[0031] A modified polylactic acid composite photosensitive resin for photocurable 3D printing: the mass fraction of photosensitive telechelic oligolactic acid is 72.5%; the mass fraction of photoinitiator is 1.0%; the mass fraction of diluent is 26.5%. Among them, the chelating center molecule is trimesic acid (H3TBC), the vinyl grafted molecule is glycidyl methacrylate, the diluent is N-vinyl pyrrolidone (NVP), and the photoinitiator is IRGACURE 819.

[0032] 1. A method for preparing a photosensitive telechelic oligolactic acid, comprising the following steps:

[0033] First, the chelating center molecule and L-lactic acid were added to a three-necked round-bottom flask at a molar ratio of 1:40, and toluene with water was added. The reaction was carried out at 90°C and 100°C for 1 hour each, and then the catalyst stannous octoate was added. After the circulating water vacuum pump was turned on and evacuated to vacuum, the reaction was carried out at 120°C and 140°C for 2 hours each, and then the temperature was raised to 160°C for 20 hours, and then the temperature was lowered to 120°C, and the vinyl grafted molecule (L-lactic acid: vinyl grafted molecule = 1:5) was added and the reaction was continued for 4 hours to finally obtain photosensitive telechelic oligomeric lactic acid.

[0034] 2. A method for preparing a modified polylactic acid composite photosensitive resin for photocurable 3D printing, comprising uniformly mixing photosensitive telechelic oligolactic acid, a photoinitiator and a diluent according to a formula ratio for 20 minutes and storing the mixture away from light to obtain a modified polylactic acid composite photosensitive resin for photocurable 3D printing.

[0035] 3. 3D printing process: put the modified polylactic acid composite photosensitive resin for light-curing 3D printing into the 3D printer for 3D printing, wherein the 3D printer is a Magic Cube Precision DLP-3D printer, the light source of the 3D printer is an ultraviolet light source: the wavelength is 540nm, the printing speed of the 3D printer is 1mm / s, the printing accuracy of the 3D printer is 0.01mm, the printing layer thickness of the 3D printer is 0.073mm, and the printing temperature of the 3D printer is room temperature.

[0036] Example 3

[0037] A modified polylactic acid composite photosensitive resin for photocurable 3D printing: the mass fraction of photosensitive telechelic oligolactic acid is 72.5%; the mass fraction of photoinitiator is 1.0%; the mass fraction of diluent is 26.5%. Among them, the chelating center molecule is ethylenediaminetetraacetic acid (EDTA), the vinyl grafted molecule is glycidyl methacrylate, the diluent is N-vinyl pyrrolidone (NVP), and the photoinitiator is IRGACURE 819.

[0038] 1. A method for preparing a photosensitive telechelic oligolactic acid, comprising the following steps:

[0039] First, the chelating center molecule and L-lactic acid were added to a three-necked round-bottom flask at a molar ratio of 1:40, and toluene with water was added. The reaction was carried out at 90°C and 100°C for 1 hour each, and then the catalyst stannous octoate was added. After the circulating water vacuum pump was turned on and evacuated to vacuum, the reaction was carried out at 120°C and 140°C for 2 hours each, and then the temperature was raised to 160°C for 20 hours, and then the temperature was lowered to 120°C, and the vinyl grafted molecule (L-lactic acid: vinyl grafted molecule = 1:5) was added and the reaction was continued for 4 hours to finally obtain photosensitive telechelic oligomeric lactic acid.

[0040] 2. A method for preparing a modified polylactic acid composite photosensitive resin for photocurable 3D printing, comprising uniformly mixing photosensitive telechelic oligolactic acid, a photoinitiator and a diluent according to a formula ratio for 20 minutes and storing the mixture away from light to obtain a modified polylactic acid composite photosensitive resin for photocurable 3D printing.

[0041] 3. 3D printing process: put the modified polylactic acid composite photosensitive resin for light-curing 3D printing into the 3D printer for 3D printing, wherein the 3D printer is a Magic Cube Precision DLP-3D printer, the light source of the 3D printer is an ultraviolet light source: the wavelength is 540nm, the printing speed of the 3D printer is 1mm / s, the printing accuracy of the 3D printer is 0.01mm, the printing layer thickness of the 3D printer is 0.073mm, and the printing temperature of the 3D printer is room temperature.

[0042] Example 4

[0043] A modified polylactic acid composite photosensitive resin for photocurable 3D printing: the mass fraction of photosensitive telechelic oligolactic acid is 72.5%; the mass fraction of photoinitiator is 1.0%; the mass fraction of diluent is 26.5%. Among them, the chelating center molecule is ethylenediaminetetraacetic acid (EDTA), the vinyl grafted molecule is glycidyl methacrylate, the diluent is vinyl acetate (VA), and the photoinitiator is camphorquinone.

[0044] 1. A method for preparing a photosensitive telechelic oligolactic acid, comprising the following steps:

[0045] First, the chelating center molecule and L-lactic acid were added to a three-necked round-bottom flask at a molar ratio of 1:40, and toluene with water was added. The reaction was carried out at 90°C and 100°C for 1 hour each, and then the catalyst stannous octoate was added. After the circulating water vacuum pump was turned on and evacuated to vacuum, the reaction was carried out at 120°C and 140°C for 2 hours each, and then the temperature was raised to 160°C for 20 hours, and then the temperature was lowered to 120°C, and the vinyl grafted molecule (L-lactic acid: vinyl grafted molecule = 1:5) was added and the reaction was continued for 4 hours to finally obtain photosensitive telechelic oligomeric lactic acid.

[0046] 2. A method for preparing a modified polylactic acid composite photosensitive resin for photocurable 3D printing, comprising uniformly mixing photosensitive telechelic oligolactic acid, a photoinitiator and a diluent according to a formula ratio for 20 minutes and storing the mixture away from light to obtain a modified polylactic acid composite photosensitive resin for photocurable 3D printing.

[0047] 3. 3D printing process: put the modified polylactic acid composite photosensitive resin for light-curing 3D printing into the 3D printer for 3D printing, wherein the 3D printer is a Magic Cube Precision DLP-3D printer, the light source of the 3D printer is an ultraviolet light source: the wavelength is 540nm, the printing speed of the 3D printer is 1mm / s, the printing accuracy of the 3D printer is 0.01mm, the printing layer thickness of the 3D printer is 0.073mm, and the printing temperature of the 3D printer is room temperature.

[0048] Comparative Example 1

[0049] A modified polylactic acid composite photosensitive resin for photocurable 3D printing: the mass fraction of photosensitive telechelic oligolactic acid is 72.5%; the mass fraction of photoinitiator is 1.0%; the mass fraction of diluent is 26.5%. Among them, the chelating center molecule is glycerol (GL), the vinyl grafted molecule is glycidyl methacrylate, the diluent is N-vinyl pyrrolidone (NVP), and the photoinitiator is IRGACURE 819.

[0050] 1. A method for preparing a photosensitive telechelic oligolactic acid, comprising the following steps:

[0051] First, the chelating center molecule and L-lactic acid were added to a three-necked round-bottom flask at a molar ratio of 1:40, and toluene with water was added. The reaction was carried out at 90°C and 100°C for 1 hour each, and then the catalyst stannous octoate was added. After the circulating water vacuum pump was turned on and evacuated to vacuum, the reaction was carried out at 120°C and 140°C for 2 hours each, and then the temperature was raised to 160°C for 20 hours, and then the temperature was lowered to 120°C, and the vinyl grafted molecule (L-lactic acid: vinyl grafted molecule = 1:5) was added and the reaction was continued for 4 hours to finally obtain photosensitive telechelic oligomeric lactic acid.

[0052] 2. A method for preparing a modified polylactic acid composite photosensitive resin for photocurable 3D printing, comprising uniformly mixing photosensitive telechelic oligolactic acid, a photoinitiator and a diluent according to a formula ratio for 20 minutes and storing the mixture away from light to obtain a modified polylactic acid composite photosensitive resin for photocurable 3D printing.

[0053] 3. 3D printing process: put the modified polylactic acid composite photosensitive resin for light-curing 3D printing into the 3D printer for 3D printing, wherein the 3D printer is a Magic Cube Precision DLP-3D printer, the light source of the 3D printer is an ultraviolet light source: the wavelength is 540nm, the printing speed of the 3D printer is 1mm / s, the printing accuracy of the 3D printer is 0.01mm, the printing layer thickness of the 3D printer is 0.073mm, and the printing temperature of the 3D printer is room temperature.

[0054] The photosensitive resin samples prepared in Examples 1-4 were prepared into strips with a length of 3 cm, a width of 1 cm, and a thickness of 0.73 mm. The tensile strength and elongation at break were tested using a Shenzhen Sansi Electronic Universal Testing Machine according to ASTM D638. The results are shown in Table 1:

[0055] Table 1 Experimental results of samples obtained from Examples 1-4

[0056] performance Chelating central molecule <![CDATA[M w / PDI]]> Thinner Tensile strength(MPa) Elongation at break (%) Example 1 SA 8384 / 2.32 NVP 5.98 37 Example 2 H3BTC 8444 / 2.11 NVP 9.71 42 Example 3 EDTA 9511 / 1.98 NVP 11.55 55 Example 4 EDTA 9511 / 1.78 VA 8.78 49

[0057] It can be seen from Table 1 that the photosensitive resins prepared in Examples 1-4 have high tensile strength, good toughness, are easy to shape, and are conducive to high-precision processing by DLP printing technology.

[0058] The thermal performance of Example 2, Example 3 and Comparative Example 1 was investigated. Figure 1 As shown, the photosensitive teleoligomeric lactic acid obtained from Example 2 (trimethylenediaminetetraacetic acid) and Example 3 (ethylenediaminetetraacetic acid) with acid as the central chelating molecule has a higher melting temperature and melting enthalpy, indicating that the material has good stability and is not easy to deform, while the photosensitive teleoligomeric lactic acid obtained from Comparative Example 1 (propylene glycol) with alcohol as the central chelating molecule has poor structural stability.

Claims

1. A modified polylactic acid composite photosensitive resin for photocuring 3D printing, characterized in that: By mass fraction, it includes the following components: Photosensitive telechelic oligolactic acid 65-75%; Photoinitiator 0.5-5%; Diluent 20-30%; The photosensitive telechelic oligomeric lactic acid is mainly composed of L-lactic acid, which is dehydrated and polymerized with a chelating central molecule, and then end-grafted with a vinyl grafted molecule; the chelating central molecule is one of succinic acid, trimesic acid, and ethylenediaminetetraacetic acid.

2. The modified polylactic acid composite photosensitive resin for photocurable 3D printing according to claim 1, characterized in that: The photoinitiator is one of IRGACURE 819, diphenyl-(2,4,6-trimethylbenzoyl)phosphine oxide and camphorquinone.

3. The modified polylactic acid composite photosensitive resin for photocurable 3D printing according to claim 1, characterized in that: The diluent is one of N-vinyl pyrrolidone, styrene, vinyl pyrrolidone, vinyl acetate, butyl acrylate, isooctyl acrylate, (methyl) hydroxy acrylate, 1,6-hexanediol diacrylate, tripropylene glycol diacrylate, neopentyl glycol diacrylate, and trimethylolpropane triacrylate.

4. The modified polylactic acid composite photosensitive resin for photocurable 3D printing according to claim 1, characterized in that: The vinyl grafted molecule is one of glycidyl methacrylate or acrylic anhydride.

5. The modified polylactic acid composite photosensitive resin for photocurable 3D printing according to claim 1, characterized in that: The molar ratio of the L-lactic acid, the chelating central molecule and the vinyl grafted molecule is 1:40:

5.

6. The modified polylactic acid composite photosensitive resin for photocurable 3D printing according to claim 1, 4 or 5, characterized in that: The preparation process of the photosensitive telechelic oligomeric lactic acid is as follows: L-lactic acid and a chelating center molecule are added into a reactor, and then toluene with water is added, and the reaction is carried out at 90° C. and 100° C. for 1 hour respectively, and then a catalyst stannous octoate is added. After the reactor is evacuated to a vacuum, the reaction is carried out at 120° C. and 140° C. for 2 hours respectively, and then the temperature is raised to 160° C. for 20 hours, and finally the temperature is lowered to 120° C., and a vinyl grafted molecule is added and the reaction is carried out for 4 hours to obtain the photosensitive telechelic oligomeric lactic acid.

7. The method for preparing the modified polylactic acid composite photosensitive resin for photocurable 3D printing according to any one of claims 1 to 6, characterized in that: Mix all components evenly and store away from light.

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