A method for preparing a thermoplastic ductile reinforcing material, the material and applications thereof

Abstract

The application provides a preparation method of a ductile reinforcing material for 3D printing of permanent crowns, which comprises the following steps: S1, adding a thermosetting material and an active dilution monomer into a reactor, and stirring to form a transparent liquid at room temperature; S2, adding a thermoplastic material and a photoinitiator into the transparent liquid of S1, and continuing to stir until a transparent and uniform liquid mixture appears at room temperature; and S3, using light to realize photocuring of the uniform liquid mixture of S2. The application aims to increase the ductility of the material, and is suitable for 3D printing of ductile permanent crowns, abutments and other dental restoration materials and dental products by using digital technology.

Description

Technical Field

[0001] This invention relates to the field of resin-based composite materials technology, specifically to a method for preparing a thermoplastic toughness-enhancing material, the material itself, and its applications. Background Technology

[0002] The dental field demands high precision, and each model design is unique and non-repeating. Therefore, traditional techniques relying on manual operation by skilled workers are difficult and inefficient. The emergence and maturation of 3D printing technology, and its perfect integration with the dental field, have solved the problems of high difficulty and low efficiency associated with traditional manual techniques.

[0003] Currently, 3D printing technology is rapidly developing in the production of dental orthodontic auxiliary tools such as invisible aligners, fixed dentures, implant surgical guides, denture bases, and personalized restoration fusion molds, as well as in the fields of dental implants, prosthodontics, orthodontics, and internal medicine.

[0004] However, 3D printing has lagged behind in the field of dental implantology, mainly due to the stringent safety and mechanical performance requirements of the printing materials for implants. For example, printing with metal powder still faces issues such as substandard mechanical properties, excessive heavy metal release, and failure to pass cytotoxicity tests. Furthermore, the recently developed ceramic printing technology is hampered by the large shrinkage ratio of the material and the high-temperature sintering requirements, making commercialization difficult.

[0005] Typical bisphenol A glyceride composites have a fracture strength in the range of 80-100 MPa, which cannot meet the high compressive strength requirements of dental restorative materials. Furthermore, materials with lower fracture strength require the printing of thicker crowns, necessitating the removal of a significant amount of bone from the original tooth. Therefore, only materials with high fracture strength enable minimally invasive dental restorations.

[0006] Furthermore, adding nanoparticle fillers appears to easily transfer external pressure to the surrounding environment, thereby improving material toughness by dispersing energy at the tip of the main crack through microcracks. However, nanoparticles are highly prone to agglomeration during photocuring, which significantly reduces the mechanical properties of the material.

[0007] Therefore, this application starts from material design and utilizes the thermoplastic nanostructure generated in situ in thermosetting materials to greatly enhance the toughness of the materials, thereby providing a novel 3D printing material for permanent dental crowns, which can be used to prepare digital permanent crowns and related products. Summary of the Invention

[0008] The purpose of this invention is to provide a method for utilizing thermoplastic toughness-enhancing materials generated in situ from thermosetting materials, thereby solving the problem of poor toughness in materials used for 3D printing permanent dental crowns.

[0009] A method for preparing a toughening reinforcement material for 3D printing permanent crowns, the method comprising:

[0010] Step S1: Add thermosetting material and active diluent monomer to the reactor and stir at room temperature to form a transparent liquid;

[0011] Step S2: Add thermoplastic material and photoinitiator to the transparent liquid from step S1, and continue stirring at room temperature until a transparent, homogeneous liquid mixture appears.

[0012] Step S3: Apply light to the homogeneous liquid mixture from step S2 to achieve photocuring.

[0013] Preferably, the thermosetting material is a thermosetting monomer material, and the thermoplastic material is a thermoplastic monomer material.

[0014] Preferably, the thermosetting material is a thermosetting oligomer material, and the thermoplastic material is a thermoplastic oligomer material.

[0015] Preferably, the thermoplastic material is a material that is photocured in a thermosetting resin and has a different polarity than the thermosetting material.

[0016] Preferably, the thermoplastic material is photocured in a thermosetting resin, which can produce significant phase separation during the polymerization of the thermosetting material.

[0017] Preferably, the photocuring time is 0.5-10 seconds.

[0018] The material prepared by the method described in any one of the above methods comprises the following components in parts by weight: 30-50 parts of polyurethane acrylate oligomer, 15-35 parts of 2-hydroxyethyl acrylate, 10-20 parts of reactive diluent monomer, and 0.5-5 parts of photoinitiator.

[0019] Preferably, the mass ratio of the polyurethane acrylate oligomer to the 2-hydroxyethyl acrylate is 1:1 to 2:1.

[0020] Preferably, the reactive diluent monomer is acrylate.

[0021] Preferably, the photoinitiator is IRGACURE819.

[0022] This invention achieves the following significant effects:

[0023] (1) Photocurable thermoplastic materials are used. During the photocuring process, the thermoplastic materials form fibrous or other microstructures in situ in the thermosetting resin, which increases the toughness of the material.

[0024] (2) The material is suitable for making tough permanent crowns, abutments and other dental restorative materials and products, especially for 3D printing dental products using digital technology. Attached Figure Description

[0025] Figure 1 This involves the in-situ formation of fibrous granular structures in thermoplastic materials within thermosetting resins.

[0026] Figure 2 Thermoplastic nanofibers in a polymer matrix;

[0027] Figure 3 This is a diagram showing the result of in-situ formation of fibrous particulate material from thermoplastic material in thermosetting resin. Detailed Implementation

[0028] To more clearly illustrate the technical features of this solution, the following detailed implementation method will be used to explain the solution.

[0029] The purpose of this invention is to provide a method for utilizing thermoplastic toughness-enhancing materials generated in situ from thermosetting materials, thereby solving the problem of poor toughness in materials used for 3D printing permanent dental crowns.

[0030] A method for preparing a toughening reinforcement material for 3D printing permanent crowns, the method comprising:

[0031] Step S1: Add thermosetting material and active diluent monomer to the reactor and stir at room temperature to form a transparent liquid;

[0032] Step S2: Add thermoplastic material and photoinitiator to the transparent liquid from step S1, and continue stirring at room temperature until a transparent, homogeneous liquid mixture appears.

[0033] Step S3: Apply light to the homogeneous liquid mixture from step S2 to achieve photocuring.

[0034] The photocuring time is 0.5-10 seconds.

[0035] The thermosetting material is a thermosetting monomer or oligomer material, and the thermoplastic material is a thermoplastic monomer or oligomer material.

[0036] A photocurable polymer component, comprising at least one thermoplastic monomer and at least one thermosetting monomer or oligomer.

[0037] Thermoplastic materials are photocured to form fibrous or other microstructures in situ within thermosetting resins, achieving the dispersion and assembly of thermoplastic micromaterials at the molecular level. When a sample is subjected to impact, microcracks develop in the thermosetting material. At this point, thermoplastic particles span both sides of the crack; for the crack to propagate, the thermoplastic particles need to be stretched. During the deformation process of the thermoplastic material, a significant amount of energy is absorbed, thereby increasing the impact strength of the printed material.

[0038] The fibrous microstructure arises because, during photocuring, some thermoplastic monomers exhibit higher reactivity than thermosetting monomers. Therefore, these thermoplastic monomers preferentially polymerize. As polymerization progresses, the molecular weight of the resulting thermoplastic oligomers gradually increases, thus widening the polarity difference between the thermosetting and thermoplastic components. This polarity change causes the thermoplastic oligomers to undergo phase separation and self-assemble into nanofiber structures. The resulting microstructures range in size from 10 nanometers to 500 micrometers.

[0039] Different proportions of thermoplastic and thermosetting resins can lead to different assembly behaviors, resulting in different microstructures, such as nanospheres and nanorods.

[0040] The thermoplastic monomer or oligomer material is a material that is photocured in a thermosetting resin and has a different polarity than the thermosetting monomer or oligomer material.

[0041] The thermoplastic is photocured in a thermosetting resin, which can produce significant phase separation during the polymerization of thermosetting materials.

[0042] Thermoplastic monomers or oligomers must meet the following two conditions: they can be photocured in thermosetting resins, and they have different polarities from thermosetting monomers or oligomers, enabling them to produce significant phase separation during the polymerization of thermosetting materials.

[0043] Examples of thermoplastic monomers include methacrylates, ethyl acrylates, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, vinyl ethyl ether, benzyl acrylate, acrylic acid, acrylamide, 2-hydroxyethyl methacrylate, 2-hydroxyethyl acrylate, butyl acrylate, isobutyl acrylate, tert-butyl acrylate, butyl glycidyl ether, 2-ethyl cyanoacrylate, glyceryl monomethacrylate, cyclohexyl acrylate, isobutyl acrylate, isobutyl vinyl ether, isopropyl acrylate, 2-methoxyethyl acrylate, methyl glycidyl ether, methyl vinyl ether, and dimethyl methacrylate. Dodecyl acrylate, dodecyl methacrylate, dodecyl vinyl ether, 2-ethoxyethyl acrylate, vinyl malonate, 2-ethylhexyl vinyl ether, ethyl vinyl ether, hexadecyl methacrylate, hexyl acrylate, hexyl methacrylate, propyl vinyl ether, trifluoroethyl acrylate, vinyl propionate, butyl glycidyl ether, glycidyl phenyl ether, glycidyl-2-methylphenyl ether, benzyl glycidyl ether, glycidyl benzyl ether, glycidyl methyl ether, 3,4-epoxy-2-phenyl-1,1,1-trifluoro-2-butanol, etc.

[0044] To achieve better results, the thermoplastic monomer should have significant hydrophilic or hydrophobic properties with the corresponding thermosetting material. Furthermore, the side chains of the polymerized thermoplastic material should have the ability to self-assemble within the thermosetting material.

[0045] The thermosetting materials used in this invention can be selected from the following monomers or oligomers. The thermosetting monomers used must have two or more polymerizable sites. The solid precursors used must include bisphenol A dimethacrylate, bisphenol A diglycidyl ether methacrylate, ethoxylated bisphenol A dimethacrylate, tricyclo[5.2.1.02,6]decanedimethyl diacrylate, bisphenol A glycerol diacrylate, bisphenol A ethoxylated diacrylate, bisphenol A ethoxylated dimethacrylate, bisphenol F ethoxylated diacrylate, bis(4-hydroxyphenyl)dimethylmethane diglycidyl ether, polyisocyanate acrylate, polyurethane acrylate oligomer, branched hexafunctional aliphatic polyurethane acrylate, 1,3,5-triacryloylhexahydro-1,3,5-triazine hexahydro-1,3,5-tris(1-oxo-2-propenyl)-1,3,5-triazine, bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, bis(tri... (Hydroxymethylpropane) tetraacrylate, pentaerythritol triacrylate, trimethylolpropane propoxylated triacrylate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, di(trimethylolpropane) tetraacrylate, pentaerythritol tetraacrylate, vinyl T-structure polymer, methacryloyloxypropyl T-structure siloxane, methacrylic polysilsesquioxane cage mixture, methacryloylethyl polysilsesquioxane, trimethylolpropane triglycidyl ether, tri(4-hydroxyphenyl)methane triglycidyl ether, tri(epoxypropoxypropyldimethylsiloxy)phenylsilane), epoxycyclohexyl-cage polysilsesquioxane, triglycidyl isobutyl polysilsesquioxane, glycidyl polysilsesquioxane cage, etc.

[0046] The curing conditions can be UV- or laser-initiated polymerization, or thermally excited free radical polymerization. For ease of photopolymerization-based 3D printing applications, this invention favors photo-initiated free radical polymerization. Usable free radicals include: acetophenone, anisole, anthraquinone, triarylsulfonium hexafluorophosphate, triarylsulfonium hexafluoroantimonate, 3-methylbenzophenone, 4-hydroxybenzophenone, dibenzosuccinone, 2,2-diethoxyacetophenone, 4-benzoylbiphenyl, 2-benzyl-2-(dimethylamino)-4'-morpholinobutyroylbenzene, benzoyl, benzoin, benzoin ether, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide (IRGACURE819), and 2,4,6-trimethylbenzoyl diphenylphosphine (TPO). 2-Hydroxy-2-methyl-1-phenyl-1-propane (DAROCUR1173), benzophenone (BP), etc., or the following thermal initiators including 4,4-azobis(4-cyanopentanoic acid), 1,1'-azobis(cyclohexaneformonitrile), 2,2'-azobisisobutyronitrile (AIBN), benzoyl peroxide, 1,1-bis(tert-butylperoxy)cyclohexane, tert-butyl hydroperoxide, tert-butyl peracetate, tert-butyl peroxide, cumene hydroperoxide, cyclohexanone peroxide, 2,4-pentanedione peroxide, ammonium persulfate, potassium persulfate, etc. The dosage range of the photoinitiator is 0.5-5 wt%.

[0047] The material prepared according to the above method includes at least one thermoplastic monomer and at least one thermosetting monomer or oligomer, and contains the following components in parts by weight: 30-50 parts of polyurethane acrylate oligomer, 15-35 parts of 2-hydroxyethyl acrylate, 10-20 parts of reactive diluent monomer, and 0.5-5 parts of photoinitiator.

[0048] The mass ratio of the polyurethane acrylate oligomer to the 2-hydroxyethyl acrylate is 1:1 to 2:1.

[0049] The photoinitiator is IRGACURE819.

[0050] Preparation of Resin 1:

[0051] Add 40 g of polyurethane acrylate oligomer, 30 g of 2-hydroxyethyl acrylate, and 20 g of amine acrylic acid to a flask. After obtaining a clear solution by stirring, add 0.9 g of IRGACURE 819 to the resulting mixture. Continue stirring at room temperature for 2 hours until a translucent or clear solution is obtained.

[0052] As mentioned earlier, in this reaction example, acrylamide preferentially polymerizes, forming a polar component separate from the overall system, and self-assembles into a nanofiber-like structure. Specific reaction formula:

[0053]

[0054] R1 = H or CH3

[0055] R2 can be one of the following polar groups:

[0056] NH2,OOH,ONa,OCH2CH2NH2,OCH2CH2COOH,N(CH3)2,OCH(OH)CH2CH2OH,OCH2CH2OH

[0057] R2 can also be a neutral or nonpolar group with the general formula OR3.

[0058] R3 will be a straight-chain or branched alkyl group. For example:

[0059] OOCH3, OCH2CH2OCH3, OCH2CH2CF3, OC(CH3)3, OCF2CF2, etc.

[0060] Preparation of Resin 2 (Control Resin)

[0061] Add 40 g of polyurethane acrylate oligomer and 50 g of 2-hydroxyethyl acrylate to a flask. After obtaining a clear solution by stirring, add 0.9 g of IRGACURE 819 to the resulting mixture. Continue stirring at room temperature for another 2 hours until a clear solution is obtained.

[0062] To evaluate their printability and mechanical strength, Young's modulus test samples were printed on a DLP printer (LittleRP, build volume 60mm (X) 40mm (Y) 100mm (Z)) using a 1024x768 resolution DLP projector (brand and model: Acer P128) as the light source and CreationWorkshop as the control software. Printing was performed at a slice thickness of 50 micrometers. The exposure time for each layer was 3 seconds. After printing, the samples were thoroughly cleaned with isopropyl alcohol, air-dried, and then placed in a UV oven for further curing.

[0063] The mechanical constants of the materials were measured using the mechanical tensile method. Young's modulus and flexural strength were measured according to the general ASTM D638-03 standard. At least five printed samples of each resin were tested using an INSTRON universal testing machine at a loading rate of 1 mm / s. The results are the average of at least five samples.

[0064] The test results of the result sample (resin 1) and the control sample (resin 2) are compared in Table 1.

[0065] Table 1. Comparison of Mechanical Properties of Materials

[0066]

[0067] The results clearly show that, compared with the control sample, the material prepared using this patented method has significantly improved modulus and flexural strength. Simultaneously, the elongation increased by approximately two times.

[0068] To confirm the formation of the thermoplastic nanostructure, the resin mixture of Resin 1 was added to a glass petri dish and then irradiated from the bottom at a distance of 10 cm with a UV LED lamp at room temperature for 1 minute for photocuring (UV: 360 nm, 15 W). The unreacted liquid resin was poured off, and the resulting polymer film was washed three times with IPA, then dried under vacuum for 8 hours, followed by SEM analysis. Figure 2 It is clearly visible that the resulting polymer matrix contains many thermoplastic nanofibers with diameters of tens of nanometers.

[0069] To evaluate the potential applications of Resin 1 in dental product development, as described in Resin 1, hydroxyapatite nanoparticles with a size of 60-80 nm were added to the resin. Crowns and abutments were then printed on a DLP printer. Printing was performed at a slice thickness of 50 micrometers. The exposure time for each layer was 3 seconds. After printing, the printed portions were thoroughly cleaned with isopropanol, air-dried, and then cured in a UV oven for 10 minutes. Figure 3 It is clear from the images that both the crown and abutment can be printed accurately with a smooth surface finish. Furthermore, we can see that the abutment was printed with a precision of less than 0.2 millimeters.

[0070] This invention achieves the following significant effects:

[0071] (1) Photocurable thermoplastic materials are used. During the photocuring process, the thermoplastic materials form fibrous or other microstructures in situ in the thermosetting resin, which increases the toughness of the material.

[0072] (2) The material is suitable for making tough permanent crowns, abutments and other dental restorative materials and products, especially for 3D printing dental products using digital technology.

[0073] The technical features of this invention not described can be implemented by or using existing technology, and will not be repeated here. Of course, the above description is not a limitation of this invention, and this invention is not limited to the examples above. Any changes, modifications, additions or substitutions made by those skilled in the art within the scope of this invention should also be within the protection scope of this invention.

Claims

1. A method for preparing a toughening reinforcing material for 3D printing permanent crowns, characterized in that, The method includes: Step S1: Add thermosetting material and reactive diluent monomer to the reactor and stir at room temperature to form a transparent liquid; wherein, the thermosetting material is a thermosetting monomer material or a thermosetting oligomer material, and the reactive diluent monomer is amine acrylate; Step S2: Add thermoplastic material and photoinitiator to the transparent liquid from step S1, and continue stirring at room temperature for 2 hours until a transparent, homogeneous liquid mixture appears; wherein, the thermoplastic material is a thermoplastic monomer material or a thermoplastic oligomer material. Step S3: The homogeneous liquid mixture from step S2 is photocured using light for 0.5-10 seconds. The thermoplastic material is photocured in the thermosetting resin, which can produce phase separation during the polymerization of the thermosetting material.

2. The method according to claim 1, characterized in that, The thermoplastic material has a different polarity than the thermosetting material.

3. The material prepared by the method according to any one of claims 1-2, characterized in that, It contains the following components in parts by weight: 30-50 parts of polyurethane acrylate oligomer, 15-35 parts of 2-hydroxyethyl acrylate, 10-20 parts of reactive diluent monomer, and 0.5-5 parts of photoinitiator.

4. The material according to claim 3, characterized in that, The mass ratio of the polyurethane acrylate oligomer to the 2-hydroxyethyl acrylate is 1:1 to 2:

1.

5. The material according to claim 4, characterized in that, The photoinitiator is IRGACURE819.

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