Post-curing method for 3D printout using photo-curable composition and transparent orthodontic appliance manufactured thereby

Abstract

The present invention relates to a post-curing method for a 3D printout using a photo-curable composition and a transparent orthodontic appliance manufactured thereby, and the present invention aims to provide a post-curing process for a 3D printout, wherein the removal of the residual resin from an output, which is obtained using a photo-curable composition for 3D printing that can maintain a 3D-printable viscosity and exhibits properties suitable for use as a dental material, prevents the release of residual resin even during long-term use in the oral cavity, and the curing time is shortened due to an increase in curing rate by the post-curing process, enabling the production of a printout with enhanced strength and improved transparency. Also, the present invention aims to provide a transparent orthodontic appliance, which, when provided, can be free of residual resin and unreacted monomers of an output, show superb aesthetic impression through excellent transparency, exhibit enhanced strength, and offer excellent orthodontic effects and improved convenience of use due to shape memory properties during orthodontic treatment.

Description

Post-curing method for 3D printed output using photocurable composition and transparent orthodontic device manufactured by the method

[0001] The present invention relates to a post-curing method for a 3D printed output using a photocurable composition and a transparent orthodontic device manufactured by the method, and more particularly, to a post-curing method capable of improving the quality of a product by post-curing an output printed through 3D printing using a photocurable composition capable of manufacturing a dental product such as a transparent orthodontic device, and a transparent orthodontic device manufactured by the method.

[0002] In general, to produce a molded product with a three-dimensional shape, there are two methods: a mock-up production method that relies on drawings and is done manually, and a numerically controlled automatic production method using a CNC machine tool.

[0003] However, the mock-up manufacturing method is manual, so it is difficult to process precise shapes and takes a lot of time, and the manufacturing method using CNC machine tools allows for precise numerical control, but there are limitations on the shapes that can be processed due to tool interference.

[0004] Recently, 3D printers have emerged that create three-dimensional molded products using a computer that stores 3D design drawing data designed by a product designer or designer using a 3D modeling tool.

[0005] Using the above 3D printer has the advantage of significantly reducing production costs and manufacturing time, enabling customized manufacturing, and easily manufacturing complex three-dimensional shapes.

[0006] The above-mentioned 3D printers include the SLA (Stereo Lithography Apparatus) method, which injects a laser into a photocurable resin to harden the injected portion; the DLP (Digital Light Processing) method, which hardens the photocurable resin by irradiating light to the bottom of a storage tank; the LCD method, which laminates a resin molded product on the top of a build plate using a UV light source and an LCD panel; the SLS (Selective Laser Sintering) method, which sinters functional polymers or metal powders; the FDM (Fused Deposition Modeling) method, which models by extruding molten resin; the DMT (Laser-aid Direct Metal Tooling) method, which directly shapes metal with a high-power laser beam; and the LOM (Laminated Object Manufacturing) method, which is a mechanical bonding modeling method.

[0007] Among these, in SLA, DLP, and LCD methods that use photocurable resins, after manufacturing the molded product, it must be washed and then go through a separate curing process to obtain the desired strength and color.

[0008] The device used in the above-mentioned post-curing process is generally called a 'post-curing machine', and post-curing machines include UV (Ultra Violet) post-curing machines and UV LED (Light Emitting Diode) post-curing machines.

[0009] If the output is cured in a natural state without using a post-curing machine, the size of the output may be deformed or the strength may be reduced.

[0010] Additionally, when curing output using only the printer's light source in a 3D printer, many problems may occur, such as the output being deformed in size, its strength being reduced, and stickiness due to unreacted light-cured resin after washing.

[0011] To prevent these problems, a post-curing device is used, but when only simple UV curing is performed, there is a problem in that the strength and transparency of the output are not improved.

[0012] In addition, in order to proceed with the post-curing process, there was the inconvenience of having to remove any remaining cleaning materials from the output before using the post-curing machine.

[0013] Development of a post-process is needed to prevent these problems.

[0014] [Prior Art Literature]

[0015] [Patent Document]

[0016] (Patent Document 1) KR 10-2019-0054856 A1

[0017] The purpose of the present invention is to provide a post-curing method for a 3D printed output using a photocurable composition and a transparent orthodontic device manufactured by the method.

[0018] Another object of the present invention is to provide a post-curing process for a 3D printed output that can remove residual resin from an output using a photocurable composition for 3D printing that can maintain a viscosity that allows 3D printing and exhibits properties that can be used as a dental material, so that residual resin is not released even when used in the oral cavity for a long time, and the curing time is shortened due to an improvement in the curing speed by the post-curing process, and an output with improved strength and increased transparency can be manufactured.

[0019] Another object of the present invention is to provide a transparent orthodontic device which, when provided as a transparent orthodontic device, can remove residual resin and unreacted monomers of the output, exhibits excellent transparency to provide excellent aesthetics, has improved strength, and has shape memory properties to provide excellent orthodontic effects and enhance convenience of use during orthodontic treatment.

[0020] In order to achieve the above object, the present invention provides a method for post-curing a 3D print output using a photocurable composition, the method comprising: manufacturing an output using a 3D printer using a photocurable composition including a photocurable oligomer, a monomer, a photoinitiator, and a stabilizer represented by the following chemical formula 1; placing the output in a rotating body and washing it to remove protrusions and residual resin remaining on the surface of the output; performing a first post-curing on the washed output in an inert gas environment; immersing the first post-cured output in oil and performing a second post-curing; and treating the second post-cured output with hot water:

[0021] [Chemical Formula 1]

[0022]

[0023] [Chemical Formula 2]

[0024]

[0025] [Chemical Formula 3]

[0026]

[0027] [Chemical Formula 4]

[0028]

[0029] [Chemical Formula 5]

[0030]

[0031] [Chemical Formula 6]

[0032]

[0033] Here,

[0034] n is an integer from 1 to 100,

[0035] m is an integer from 1 to 50,

[0036] A, B, C and D are the same or different from each other and are repeating units each independently selected from the group consisting of compounds represented by chemical formulas 2 to 6,

[0037] a, b, c and d are the same or different and are each independently an integer from 1 to 30,

[0038] R1 and R2 are the same or different, and can each be independently selected from the group consisting of hydrogen, deuterium, a substituted or unsubstituted alkyl group having 1 to 30 carbon atoms, a substituted or unsubstituted alkenyl group having 2 to 30 carbon atoms, a substituted or unsubstituted alkynyl group having 2 to 30 carbon atoms, a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, and a substituted or unsubstituted heteroaryl group having 1 to 30 carbon atoms.

[0039] A, B and D of the photocurable oligomer represented by the above chemical formula 1 are the same as or different from each other, and are repeating units independently selected from compounds represented by chemical formula 2 or 3, and C may be a repeating unit selected from the group consisting of compounds represented by chemical formulas 4 to 6.

[0040] The above photocurable oligomer may have a number average molecular weight (Mn) of 1,500 to 6,000.

[0041] The above photocurable oligomer may have a weight average molecular weight (Mw) of 2,500 to 9,000.

[0042] The above photocurable oligomer may have a viscosity of 2,000 mPa·s to 3,500 mPa·s.

[0043] The above 3D printer may be of DLP or SLA type.

[0044] The above inert gas may be selected from the group consisting of nitrogen, argon, helium, krypton, neon and mixtures thereof.

[0045] The above oils may be selected from the group consisting of glycerol, edible oil, castor oil, non-reactive silicone oil and mixtures thereof.

[0046] The above hot water may be hot water of 80°C to 100°C.

[0047] A transparent orthodontic device according to another embodiment of the present invention is manufactured by a post-curing method of the 3D printed output, and has an excellent orthodontic effect due to its shape memory properties.

[0048] In the present invention, “hydrogen” is hydrogen, light hydrogen, deuterium or tritium, unless specifically limited.

[0049] In the present invention, “alkyl” refers to a monovalent substituent derived from a straight or branched saturated hydrocarbon having 1 to 40 carbon atoms. Examples thereof include, but are not limited to, methyl, ethyl, propyl, isobutyl, sec-butyl, pentyl, iso-amyl, and hexyl.

[0050] In the present invention, “alkenyl” refers to a monovalent substituent derived from a straight or branched unsaturated hydrocarbon having 2 to 40 carbon atoms and at least one carbon-carbon double bond. Examples thereof include, but are not limited to, vinyl, allyl, isopropenyl, and 2-butenyl.

[0051] In the present invention, “alkynyl” refers to a monovalent substituent derived from an unsaturated hydrocarbon having 2 to 40 carbon atoms and a straight or branched chain having at least one carbon-carbon triple bond. Examples thereof include, but are not limited to, ethynyl and 2-propynyl.

[0052] In the present invention, “aryl” refers to a monovalent substituent derived from an aromatic hydrocarbon having 6 to 60 carbon atoms, which is a single ring or a combination of two or more rings. In addition, it may also include a form in which two or more rings are simply attached to each other (pendant) or condensed, and specifically, it may be a naphthyl group, anthracenyl group, phenanthryl group, triphenyl group, pyrenyl group, phenalenyl group, perylenyl group, chrysenyl group, fluorenyl group, etc., but is not limited thereto. The fluorenyl group may be substituted, and adjacent groups may be bonded to each other to form a ring.

[0053] In the present invention, “heteroaryl” refers to a monovalent substituent derived from a monoheterocyclic or polyheterocyclic aromatic hydrocarbon having 6 to 30 carbon atoms. At this time, at least one carbon atom in the ring, preferably 1 to 3 carbon atom(s), is substituted with a heteroatom such as N, O, S, or Se. In addition, a form in which two or more rings are simply attached to each other (pendant) or condensed may be included, and a form condensed with an aryl group may also be included. Examples of such heteroaryls include, but are not limited to, 6-membered monocyclic rings such as pyridyl, pyrazinyl, pyrimidinyl, pyridazinyl, and triazinyl; polycyclic rings such as phenoxathienyl, indolizinyl, indolyl, purinyl, quinolyl, benzothiazole, and carbazolyl; and 2-furanyl, N-imidazolyl, 2-isoxazolyl, 2-pyridinyl, and 2-pyrimidinyl.

[0054] In the present invention, "substitution" means that a hydrogen atom bonded to a carbon atom of a compound is replaced with another substituent, and the position of substitution is not limited as long as it is a position where a hydrogen atom is replaced, i.e., a position where a substituent can be substituted, and when two or more are substituted, the two or more substituents may be the same or different from each other. The above substituent is hydrogen, a cyano group, a nitro group, a halogen group, a hydroxy group, an alkyl group having 1 to 30 carbon atoms, an alkenyl group having 2 to 30 carbon atoms, an alkynyl group having 2 to 24 carbon atoms, a heteroalkyl group having 2 to 30 carbon atoms, an aralkyl group having 6 to 30 carbon atoms, an aryl group having 5 to 30 carbon atoms, a heteroaryl group having 2 to 30 carbon atoms, a heteroarylalkyl group having 3 to 30 carbon atoms, an alkoxy group having 1 to 30 carbon atoms, an alkylamino group having 1 to 30 carbon atoms, an arylamino group having 6 to 30 carbon atoms, an aralkylamino group having 6 to 30 carbon atoms, a heteroarylamino group having 2 to 24 carbon atoms, a substituted or unsubstituted alkylsilyl group having 1 to 30 carbon atoms, a substituted or unsubstituted alkyl group having 6 to It may be substituted with one or more substituents selected from the group consisting of 30 arylsilyl groups and substituted or unsubstituted aryloxy groups having 6 to 30 carbon atoms, but is not limited to the above examples.

[0055] In the present invention, “halogen group” is fluorine, chlorine, bromine or iodine.

[0056] In the present invention, “alkylthio” means the above-described alkyl group bonded via a sulfur linkage (-S-).

[0057] In the present invention, “aryloxy” is a monovalent substituent represented by RO-, wherein R represents aryl having 6 to 60 carbon atoms. Examples of such aryloxy include, but are not limited to, phenyloxy, naphthyloxy, and diphenyloxy.

[0058] In the present invention, “alkyloxy” is a monovalent substituent represented by R'O-, wherein R' means alkyl having 1 to 40 carbon atoms, and may include a linear, branched, or cyclic structure. Examples of alkyloxy include, but are not limited to, methoxy, ethoxy, n-propoxy, 1-propoxy, t-butoxy, n-butoxy, and pentoxy.

[0059] In the present invention, “alkoxy” may be straight chain, branched chain, or cyclic chain. The carbon number of the alkoxy is not particularly limited, but is preferably 1 to 20 carbon atoms. Specifically, it may be methoxy, ethoxy, n-propoxy, isopropoxy, i-propyloxy, n-butoxy, isobutoxy, tert-butoxy, sec-butoxy, n-pentyloxy, neopentyloxy, isopentyloxy, n-hexyloxy, 3,3-dimethylbutyloxy, 2-ethylbutyloxy, n-octyloxy, n-nonyloxy, n-decyloxy, benzyloxy, p-methylbenzyloxy, etc., but is not limited thereto.

[0060] As used herein, "aralkyl" refers to an aryl-alkyl group, where aryl and alkyl are as defined above. Preferred aralkyl groups include lower alkyl groups. Non-limiting examples of suitable aralkyl groups include benzyl, 2-phenethyl, and naphthalenylmethyl. Bonding to the parent moiety is via the alkyl group.

[0061] In the present invention, “arylamino group” means an amine substituted with an aryl group having 6 to 30 carbon atoms.

[0062] In the present invention, “alkylamino group” means an amine substituted with an alkyl group having 1 to 30 carbon atoms.

[0063] In the present invention, “aralkylamino group” means an amine substituted with an aryl-alkyl group having 6 to 30 carbon atoms.

[0064] In the present invention, “heteroarylamino group” means an amine group substituted with an aryl group and a heterocyclic group having 6 to 30 carbon atoms.

[0065] In the present invention, “heteroaralkyl group” means an aryl-alkyl group substituted with a heterocyclic group.

[0066] In the present invention, “cycloalkyl” refers to a monovalent substituent derived from a monocyclic or polycyclic non-aromatic hydrocarbon having 3 to 40 carbon atoms. Examples of such cycloalkyl include, but are not limited to, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, norbornyl, and adamantine.

[0067] In the present invention, “heterocycloalkyl” means a monovalent substituent derived from a non-aromatic hydrocarbon having 3 to 40 carbon atoms, wherein at least one carbon atom in the ring, preferably 1 to 3 carbon atom(s), is substituted with a heteroatom such as N, O, S or Se. Examples of such heterocycloalkyl include, but are not limited to, morpholine and piperazine.

[0068] In the present invention, “alkylsilyl” means silyl substituted with alkyl having 1 to 40 carbon atoms, and “arylsilyl” means silyl substituted with aryl having 6 to 60 carbon atoms.

[0069] The present invention removes residual resin from an output using a photocurable composition for 3D printing that can maintain a viscosity that allows 3D printing and exhibits properties that enable it to be used as a dental material, so that residual resin is not released even when used in the oral cavity for a long period of time, and the curing time is shortened due to the improvement of the curing speed by the post-curing process, and the output can be manufactured with improved strength and increased transparency.

[0070] In addition, when provided as a transparent orthodontic device, it can remove residual resin and unreacted monomers of the output, exhibit excellent transparency, have excellent aesthetics, improve strength, and have shape memory properties, so that it can provide excellent orthodontic effects and enhance convenience of use during orthodontic treatment.

[0071] Figure 1 is a flowchart illustrating a process for manufacturing a photocurable oligomer according to one embodiment of the present invention.

[0072] Figure 2 shows the GPC measurement results for a photocurable oligomer according to one embodiment of the present invention.

[0073] Figure 3 shows the NMR measurement results for a photocurable oligomer according to one embodiment of the present invention.

[0074] Figure 4 shows the GPC measurement results for a photocurable oligomer according to one embodiment of the present invention.

[0075] Figure 5 shows the NMR measurement results for a photocurable oligomer according to one embodiment of the present invention.

[0076] Figure 6 shows the GPC measurement results for a photocurable oligomer according to one embodiment of the present invention.

[0077] Figure 7 shows the NMR measurement results for a photocurable oligomer according to one embodiment of the present invention.

[0078] Figure 8 shows the GPC measurement results for a photocurable oligomer according to one embodiment of the present invention.

[0079] Figure 9 shows the NMR measurement results for a photocurable oligomer according to one embodiment of the present invention.

[0080] Figure 10 shows the GPC measurement results for a photocurable oligomer according to one embodiment of the present invention.

[0081] Figure 11 shows the NMR measurement results for a photocurable oligomer according to one embodiment of the present invention.

[0082] Figure 12 shows the results of a transparency comparison experiment for a transparent orthodontic device according to one embodiment of the present invention.

[0083] The present invention relates to a method for post-curing a 3D printed output using a photo-curable composition comprising a photo-curable oligomer, a monomer, a photoinitiator, and a stabilizer represented by the following chemical formula 1, which produces an output using a 3D printer, places the output in a rotating body and washes it to remove protrusions and residual resin remaining on the surface of the output, performs a first post-curing on the washed output in an inert gas environment, immerses the first post-cured output in oil, performs a second post-curing on the output, and treats the second post-cured output with hot water.

[0084] [Chemical Formula 1]

[0085]

[0086] [Chemical Formula 2]

[0087]

[0088] [Chemical Formula 3]

[0089]

[0090] [Chemical Formula 4]

[0091]

[0092] [Chemical Formula 5]

[0093]

[0094] [Chemical Formula 6]

[0095]

[0096] Here,

[0097] n is an integer from 1 to 100,

[0098] m is an integer from 1 to 50,

[0099] A, B, C and D are the same or different from each other and are repeating units each independently selected from the group consisting of compounds represented by chemical formulas 2 to 6,

[0100] a, b, c and d are the same or different and are each independently an integer from 1 to 30,

[0101] R1 and R2 are the same or different, and can each be independently selected from the group consisting of hydrogen, deuterium, a substituted or unsubstituted alkyl group having 1 to 30 carbon atoms, a substituted or unsubstituted alkenyl group having 2 to 30 carbon atoms, a substituted or unsubstituted alkynyl group having 2 to 30 carbon atoms, a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, and a substituted or unsubstituted heteroaryl group having 1 to 30 carbon atoms.

[0102] Hereinafter, embodiments of the present invention will be described in detail so that those skilled in the art can easily implement them. However, the present invention may be implemented in various different forms and is not limited to the embodiments described herein.

[0103] The DLP (Digital Light Processing) method of the present invention utilizes the principle of irradiating light to the lower part of a storage tank where photocurable resin is stored, thereby curing only the portion irradiated with light, and the SLA (Stereo Lithography Apparatus) method utilizes the principle of injecting laser light into photocurable resin, thereby curing the portion irradiated with light.

[0104] In the case of the above DLP method and SLA method, light is irradiated onto a photocurable polymer, and the photocurable polymer resin is cured by the light irradiation, thereby producing an output.

[0105] When a 3D printer is used to manufacture an output by hardening a photocurable polymer resin, resin remains on the exterior of the output, and protrusions remain on the surface, requiring an additional post-process to keep the surface smooth and clean.

[0106] In the past, for these post-processing steps, users would directly remove the protruding surface using a tool and simultaneously remove the resin using a solvent.

[0107] This process itself is not only cumbersome because the user has to do the work himself, but also has the problem of making it difficult to do it perfectly.

[0108] Additionally, printed products cured with photocurable polymer resins often contain unreacted polymer resin that is not fully cured during the manufacturing process, resulting in deteriorated physical properties and reduced transparency. To address these issues, a post-curing process is essential.

[0109] Previous post-curing methods were limited to users using tools to remove protruding surfaces or using solvents to remove resin.

[0110] That is, no separate post-curing method was introduced to enhance the physical properties of the output or improve transparency.

[0111] A method for post-curing a 3D print output using a photocurable composition according to one embodiment of the present invention may include manufacturing an output using a 3D printer using a photocurable composition including a photocurable oligomer, a monomer, a photoinitiator, and a stabilizer represented by the following chemical formula 1, placing the output in a rotating body and washing it to remove protrusions and residual resin remaining on the surface of the output, performing a first post-curing on the washed output in an inert gas environment, immersing the first post-cured output in oil, performing a second post-curing, and treating the second post-cured output with hot water.

[0112] [Chemical Formula 1]

[0113]

[0114] [Chemical Formula 2]

[0115]

[0116] [Chemical Formula 3]

[0117]

[0118] [Chemical Formula 4]

[0119]

[0120] [Chemical Formula 5]

[0121]

[0122] [Chemical Formula 6]

[0123]

[0124] Here,

[0125] n is an integer from 1 to 100,

[0126] m is an integer from 1 to 50,

[0127] A, B, C and D are the same or different from each other and are repeating units each independently selected from the group consisting of compounds represented by chemical formulas 2 to 6,

[0128] a, b, c and d are the same or different and are each independently an integer from 1 to 30,

[0129] R1 and R2 are the same or different, and can each be independently selected from the group consisting of hydrogen, deuterium, a substituted or unsubstituted alkyl group having 1 to 30 carbon atoms, a substituted or unsubstituted alkenyl group having 2 to 30 carbon atoms, a substituted or unsubstituted alkynyl group having 2 to 30 carbon atoms, a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, and a substituted or unsubstituted heteroaryl group having 1 to 30 carbon atoms.

[0130] A post-curing method according to one embodiment of the present invention firstly involves placing the output product in a rotating body and washing it to remove any protrusions and residual resin remaining on the surface of the output product.

[0131] Specifically, the output is placed in a cylindrical rotating body and a process for removing any remaining resin is performed. The cylindrical rotating body is more specifically a dehydrator, but is not limited to the above example, and any device capable of removing any remaining resin from the output by means of rotational force can be used.

[0132] When the cleaning process is performed using the above device, not only is the resin easily removed, but the protrusions formed on the surface can also be easily removed.

[0133] A dehydrator is a device that includes a cylindrical dehydrating unit. When the dehydrating unit rotates in a certain direction, the output contained inside is subjected to centrifugal force caused by the rotation of the dehydrating unit, enabling the removal of resin.

[0134] The above resin can be easily removed as a residual polymer on the surface, and even in the case of protruding surfaces, it can be easily removed through friction with the dehydrating part. This process enables easy resin removal and surface processing.

[0135] After the above washing step, a post-curing process is performed. Unlike a general post-curing process, the first post-curing and second post-curing processes can be performed sequentially by distinguishing between them.

[0136] Specifically, the first post-curing in the above inert gas environment is a post-curing process that irradiates UV to the 3D print output to promote curing, prevent deformation of the output, and improve strength to prevent damage caused by external force.

[0137] As in the present invention, when the curing process is carried out in an inert gas environment, not only is the curing speed of the 3D printed output improved, but the strength is also improved, so that deformation does not easily occur even with a higher level of impact.

[0138] In other words, when the curing process is performed by irradiating UV within an inert gas environment, the curing speed is accelerated by the inert gas, and the strength of the output can be improved, compared to when the curing process is performed by simply irradiating UV. Furthermore, when the post-curing process is performed within an inert gas environment, the transparency of transparent output is further improved.

[0139] When a 3D printer using the DLP or SLA method is used to manufacture an output, and a photocurable polymer resin that does not contain dye is used, a transparent output is obtained.

[0140] As previously explained, when a DLP or SLA 3D printer is used to manufacture an output, unreacted polymer resin remains within the output. This unreacted polymer resin requires additional curing, and a post-curing process is performed. However, during the post-curing process, if the output is exposed to the air, the photoinitiator within the output comes into contact with oxygen, generating radicals. This radical scavenging inhibits the photocuring behavior.

[0141] That is, it is necessary to prevent the output from coming into contact with oxygen, and for this purpose, when performing the first post-curing process in the present invention, post-curing is performed by irradiating UV in an inert gas environment, thereby blocking contact with oxygen.

[0142] The above transparent output will have a slightly yellow tint when it goes through the post-curing process, so it will be difficult to manufacture a completely transparent output.

[0143] In particular, in the case of orthodontic devices that are attached to the teeth, such as transparent aligners, they must have excellent transparency so that they do not have a significant impact on appearance.

[0144] When the above transparent orthodontic device is manufactured as a personalized output using 3D printing and used as an orthodontic device, if the transparency is not excellent and there is even a slight yellow tint, there is a risk of the user mistaking it for a poor dental condition, which could have a negative impact on the user's appearance.

[0145] To avoid these problems, the 3D printed object itself must be able to exhibit a degree of complete transparency.

[0146] When a conventional DLP or SLA printer is used to produce an output and then a product is manufactured through a post-curing process, some differences may occur depending on the type of photocurable polymer resin, but it usually has a yellowish tint, making it impossible to provide a completely transparent orthodontic device.

[0147] On the other hand, in the case of the present invention, when UV is irradiated in an inactive environment during the post-curing process, the curing speed is improved, the strength is improved, and the transparency of the output is improved due to the UV irradiation.

[0148] That is, by utilizing the post-curing process of the present invention, it is possible to provide a completely transparent orthodontic device.

[0149] When a post-curing process is performed using UV in an inert gas environment, the curing speed is improved, which improves the production speed of the final product, and the strength is excellent, making it less susceptible to deformation due to external force.

[0150] In addition, as described below, when using a specific photocurable oligomer, the mechanical properties are excellent, so that when used as an orthodontic device, not only can the corrective force be increased, but when used as a patient-tailored orthodontic device, the convenience of the user can be increased.

[0151] The above inert gas is selected from the group consisting of nitrogen, argon, helium, krypton, neon and mixtures thereof, preferably nitrogen, but is not limited to the above examples, and any gas capable of blocking contact of the output with oxygen as an inert gas can be used without limitation.

[0152] The present invention is characterized in that a second post-curing process is performed after the first post-curing process.

[0153] Specifically, the second post-curing process is to completely immerse the output product that has undergone the first post-curing process in oil and then irradiate it with UV light to perform post-curing.

[0154] Even if the first post-curing process is repeatedly performed without performing the second post-curing process, the shape memory characteristics of the output are not expressed, as in the present invention.

[0155] As described below, when a printed product is manufactured using the photocurable composition of the present invention and a post-curing process is performed according to the above steps, the printed product exhibits a shape memory characteristic in which the printed product is restored to its initial printed shape when heat of 60°C or higher is supplied.

[0156] However, these shape memory characteristics are expressed by the post-curing process of the present invention, and even if the order is changed to a method in which only the first post-curing process is performed without performing the second post-curing process, or the second post-curing process is performed first and then the first post-curing process is performed, the characteristics of the output are not expressed.

[0157] The second post-curing process of the present invention is to completely immerse the output product that has undergone the first post-curing process in oil and perform the post-curing process by irradiating it with UV.

[0158] As described above, by immersing the output in oil and irradiating it with UV, a high curing density and sufficient heat energy can be supplied to the output through the post-curing process.

[0159] That is, by immersing the material in oil, oxygen is blocked, and the oil absorbs heat energy from UV rays and transmits it evenly to the printed material. Due to this characteristic, the printed material is transmitted at a uniform temperature during the second post-curing process, and the printed material exhibits fluidity characteristics.

[0160] The order of the first and second post-curing processes described above is critical. If the order is changed, the oil can cause bubbles to form on the surface of the output, resulting in curing defects. To prevent this problem, it is preferable to perform the post-curing processes of the present invention in the correct order.

[0161] The above oils are selected from the group consisting of glycerol, edible oil, castor oil, non-reactive silicone oil, and mixtures thereof, preferably glycerol, but are not limited to the above examples, and any oil that is non-reactive with the output, blocks contact with oxygen, and can absorb heat and uniformly transfer it to the output can be used without limitation.

[0162] After the above post-curing process, a hot water treatment process is performed. The hot water treatment is performed with hot water at 80 to 100°C, and the hot water treatment can remove any unreacted monomers remaining in the output.

[0163] A transparent orthodontic device according to another embodiment of the present invention is manufactured by a post-curing method of the 3D print output.

[0164] The above transparent orthodontic device is used to correct the teeth to the desired position while being fitted to the patient's teeth.

[0165] The transparent orthodontic device of the present invention is manufactured by the post-curing method described above, and has excellent transparency, excellent physical properties, and can exhibit shape memory properties that restore it to its initially output shape by heat.

[0166] The above transparent orthodontic device is printed using a 3D printer using the photocurable composition described below, and manufactured through a post-curing process.

[0167] A photocurable composition for a 3D printer according to one embodiment of the present invention may include a photocurable oligomer, a monomer, a photoinitiator, and a stabilizer represented by the following chemical formula 1:

[0168] [Chemical Formula 1]

[0169]

[0170] [Chemical Formula 2]

[0171]

[0172] [Chemical Formula 3]

[0173]

[0174] [Chemical Formula 4]

[0175]

[0176] [Chemical Formula 5]

[0177]

[0178] [Chemical Formula 6]

[0179]

[0180] Here,

[0181] n is an integer from 1 to 100,

[0182] m is an integer from 1 to 50,

[0183] A, B, C and D are the same or different from each other and are repeating units each independently selected from the group consisting of compounds represented by chemical formulas 2 to 6,

[0184] a, b, c and d are the same or different and are each independently an integer from 1 to 30,

[0185] R1 and R2 are the same or different, and can each be independently selected from the group consisting of hydrogen, deuterium, a substituted or unsubstituted alkyl group having 1 to 30 carbon atoms, a substituted or unsubstituted alkenyl group having 2 to 30 carbon atoms, a substituted or unsubstituted alkynyl group having 2 to 30 carbon atoms, a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, and a substituted or unsubstituted heteroaryl group having 1 to 30 carbon atoms.

[0186] The photocurable composition of the present invention refers to a polymer that is crosslinked and polymerized into a polymer network structure, and is a material that is cured by light irradiation. While the present specification focuses on UV light, the present invention is not limited to UV light and can be applied to other types of light.

[0187] The above photocurable oligomer is characterized by including a urethane acrylate structure as a main chain, a photocurable functional group bonded to the urethane structure, and including a soft functional group and a hard functional group in the compound.

[0188] The output exhibits flexible properties due to the soft functional group included in the photocurable composition, and can also exhibit heat resistance due to the hard functional group.

[0189] That is, by combining a photocurable functional group with a photocurable oligomer and utilizing a soft functional group and a hard functional group, a flexible effect can be exhibited by utilizing a carbon skeleton having a soft property at room temperature, and a heat-resistant property can also be exhibited by utilizing a carbon skeleton having a hard property at room temperature.

[0190] Since the above photocurable oligomer includes a carbon skeleton having hard properties, it can produce a 3D printing output that has excellent physical properties such as thermal properties, strength, elastic modulus, and tensile elongation, and can be restored to its original shape by heat.

[0191] In addition, since the photocurable oligomer contains a carbon skeleton with soft properties, its shape can be deformed by an external force after heat is provided.

[0192] In general, a composition for a 3D printer may include a photocurable oligomer for 3D printing; a monomer; a photoinitiator; and a stabilizer, as described below. The oligomer, monomer, photoinitiator, and stabilizer included in the composition all affect the physical properties of the output, but the oligomer has the greatest effect. Accordingly, in general, in order to improve the physical properties of a 3D output, only a carbon skeleton having a hard property is included, which can improve the physical properties of the output, but conversely, if the shape is deformed due to use, the shape cannot be restored, which is a problem in that it cannot be used multiple times.

[0193] The composition for a 3D printer of the present invention includes a carbon skeleton having a hard property and a carbon skeleton having a soft property, so that not only is it excellent in physical properties such as thermal properties, strength, elasticity, and tensile elongation, but also the flexible property of the soft functional group can be utilized together, so that when the shape is deformed by an external force in a state where heat is provided, it can be fixed in the deformed shape, and when heat is provided again, it can be restored to the original shape.

[0194] The above A, B and D are the same or different from each other, and may be repeating units independently selected from compounds represented by chemical formula 2 or 3.

[0195] The above C may be a repeating unit selected from the group consisting of compounds represented by chemical formulas 4 to 6.

[0196] Specifically, the photocurable oligomer represented by the above chemical formula 1 can be manufactured by a method for synthesizing a urethane acrylate series. Basically, it proceeds through a stepwise polymerization reaction of a diol and a diisocyanate, and in order to prevent gelation of the material due to an increase in molecular weight during the polymerization process of the material, an acrylic monomer without a reaction site is used as a suspension. The monomer used in the synthesis of the oligomer of the present invention as an available acrylic monomer may be Isobornyl acrylate, Cyclic Trimethylolpropane Formal Acrylate, Lauryl acrylate, Lauryl methacrylate, 3,5,3-trimethelhexyl acrylate, Tetrahydrofurfuryl acrylate, Tetrahydrofurfuryl methacrylate, Benzyl methacrylate, etc.

[0197] More specifically, diol was pre-introduced into the monomer base used as the primary monomer to stabilize it, and then diisocyanate was added. As the urethane reaction progressed, heat of reaction was generated, the urethane chain lengthened, and the molecular weight increased.

[0198] As the molecular weight increases, the viscosity of the material may also increase. If the above-mentioned increase in molecular weight proceeds rapidly, the temperature rises rapidly, which also causes the urethane reaction to proceed more quickly, and as a result, the oligomer gels before reaching a sufficient molecular weight, making it unusable as a material. Therefore, in the present invention, in order to prevent this reaction, a solvent selected from the group consisting of Isobornyl acrylate, Cyclic Trimethylolpropane Formal Acrylate, Lauryl acrylate, Lauryl methacrylate, 3,5,3-trimethelhexyl acrylate, Tetrahydrofurfuryl acrylate, Tetrahydrofurfuryl methacrylate, Benzyl methacrylate, and mixtures thereof is used as a solvent for introducing the diol. The solvent does not participate in the reaction, and is used to control the reaction speed of the material and prevent a rapid increase in viscosity due to an increase in molecular weight. Additionally, the monomers used to synthesize the oligomer of the present invention must be free of functional groups capable of reactive urethane reactions, such as hydroxyl groups or urethane groups. Under the above conditions, the present invention can produce oligomers with excellent mass production and process stability.

[0199] In addition, the equivalent ratio of diol and diisocyanate was set to a state where the equivalent of diisocyanate was higher than that of diol, so that the oligomer terminal exists as an isocyanate group. A reaction catalyst including a Zn-based catalyst can be used during the reaction process. The catalyst may or may not be included. The catalyst is included to proceed the reaction more quickly, and the reaction can proceed even if it is not necessarily included, but even if it is included, the reaction can proceed with a very small amount added.

[0200] After the temperature increase was stopped due to the completion of the urethane reaction, 2-hydroxy acrylate and 2-hydroxy methacrylate were added dropwise to end-cap the ends of the oligomers.

[0201] The diols used for the preparation of the above oligomers are as follows:

[0202]

[0203] In addition, the diisocyanate for reacting with the above diol is as follows:

[0204]

[0205] Additionally, monomers that may be included to terminate the urethane reaction or increase the molecular weight are as follows:

[0206]

[0207]

[0208] The compound represented by the above chemical formula 1 manufactured by the above manufacturing method can be selected from the group consisting of the following compounds:

[0209]

[0210]

[0211]

[0212]

[0213]

[0214] The photocurable oligomer may have a number average molecular weight (Mn) of 1,500 to 6,000, 1,500 to 5,500, or 1,600 to 5,000. The photocurable oligomer may have a weight average molecular weight (Mw) of 2,500 to 9,000, 3,000 to 8,500, or 3,500 to 8,000.

[0215] When a photocurable composition for 3D printing, described below, is manufactured using an oligomer having a number average molecular weight and a weight average molecular weight within the above range, and a transparent orthodontic device is manufactured using the same, the transparent orthodontic device can be printed in a manner customized to the patient's oral structure, and the orthodontic force can be increased using the same. In addition, when the transparent orthodontic device is immersed in water at 50 to 100°C and then deformed, the shape changes to the deformed shape, but when used while fitted on a tooth, the orthodontic device, which has been deformed by body temperature, gradually returns to its original shape, thereby exhibiting orthodontic force.

[0216] That is, conventional transparent orthodontic devices are manufactured from transparent plastic materials and can transmit sufficient force for correcting teeth. However, as described above, the transparent orthodontic devices are printed in accordance with the gradual movement state of the teeth, and are different from the current tooth structure of the patient. Therefore, they are not easy to wear when fitted to the teeth and can cause great pain even after wearing them.

[0217] On the other hand, when using the photocurable composition for 3D printing of the present invention, if the printed transparent orthodontic device is immersed in water at 50 to 100°C before use and then positioned on the patient's teeth to change its shape to fit the current, the shape of the orthodontic device gradually changes due to body temperature, so that it can exert a large orthodontic force without the patient feeling great pain.

[0218] In addition, by utilizing these characteristics, it can be used in various dental products such as orthodontic retainers and arch expanders.

[0219] As described above, when various oligomers are selected according to the physical properties required for each product, such as tensile strength, flexural strength, flexural elasticity, and flexural strength, and a photocurable composition for 3D printing is manufactured using the same, it is possible to manufacture excellent dental products.

[0220] The above photocurable oligomer may have a viscosity of 2,000 psi to 3,500 psi, 2,100 psi to 3,200 psi, or 2,200 psi to 3,000 psi. When a photocurable composition is manufactured using an oligomer having a viscosity within the above range, it can be provided with a viscosity suitable for use in a 3D printer.

[0221] A photocurable composition for a 3D printer according to one embodiment of the present invention may include the photocurable oligomer for D printing; a monomer; a photoinitiator; and a stabilizer.

[0222] The above monomer is a reactive monomer, and may specifically be an acrylate monomer.

[0223] More specifically, the acrylate monomer may be selected from the group consisting of a compound represented by the following chemical formula 7, a compound represented by the following chemical formula 8, and a mixture thereof:

[0224] [Chemical Formula 7]

[0225]

[0226] [Chemical Formula 8]

[0227]

[0228] The photoinitiator may be BP, TPO, DCP, BPO, DPPO, etc., and preferably DPPO (2-hydroxy-2-methylpropiophenone) may be used. However, the present invention is not limited to the above examples, and any photoinitiator capable of producing a photocurable composition may be used without limitation.

[0229] The above stabilizer may be selected from the group consisting of tertiary amines such as diethylethanolamine and trihexylamine, hindered amines, organic phosphates, and hindered phenols, but is not limited to the above examples, and any stabilizer capable of producing a photocurable composition may be used without limitation.

[0230] In addition to the above photoinitiator and stabilizer, other additives may be additionally included.

[0231] The above additives may include conventional additives such as leveling agents, slip agents or stabilizers to improve thermal and oxidation stability, storage stability, surface properties, flow properties and process properties.

[0232] A photocurable composition according to one embodiment of the present invention may contain 1 part by weight of a photoinitiator per 100 parts by weight of a UV resin. The UV resin may include a photocurable oligomer of the present invention and a monomer, and more specifically, may contain a compound represented by the following chemical formula 1, a compound represented by the following chemical formula 7, and a compound represented by the following chemical formula 8 in a weight ratio of 1:1:1 to 2:1:1.

[0233]

[0234] Manufacturing Example 1

[0235] Manufacturing of photocurable oligomers for 3D printing

[0236] Isobornyl acrylate was used as a solvent, and polypropylene glycol, cyclohexanedimethanol, and BHT were added, and stirred at 10 to 200 rpm at 10 to 50°C. Isophorone diisocyanate was added, and stirring was performed under the same temperature conditions while changing the stirring speed from 50 to 200 rpm. Afterwards, HEMA was added, and stirring was performed at 150 to 500 rpm at 50 to 250°C to produce an oligomer.

[0237] The intermediate compounds produced by the above reaction are as follows:

[0238]

[0239] The oligomer finally produced by reacting the above intermediate compounds is as follows:

[0240]

[0241] The sequence of the manufacturing method of the above Manufacturing Example 1 is as shown in Fig. 1.

[0242] The GPC analysis results for the oligomer of the above manufacturing example 1 are as shown in Fig. 2. In addition, the NMR analysis results are as shown in Fig. 3.

[0243]

[0244] Manufacturing Example 2

[0245] An oligomer was prepared using the same method as in Manufacturing Example 1, but the monomers used during the reaction were different. The prepared oligomers are as follows:

[0246]

[0247] The GPC analysis results for the oligomer of the above manufacturing example 2 are as shown in Fig. 4. In addition, the NMR analysis results are as shown in Fig. 5.

[0248]

[0249] Manufacturing Example 3

[0250] An oligomer was prepared using the same method as in Manufacturing Example 1, but the monomers used during the reaction were different. The prepared oligomers are as follows:

[0251]

[0252] The GPC analysis results for the oligomer of the above Manufacturing Example 2 are as shown in Fig. 6. In addition, the NMR analysis results are as shown in Fig. 7.

[0253]

[0254] Manufacturing Example 4

[0255] An oligomer was prepared using the same method as in Manufacturing Example 1, but the monomers used during the reaction were different. The prepared oligomers are as follows:

[0256]

[0257] The GPC analysis results for the oligomer of the above Manufacturing Example 2 are as shown in Fig. 8. In addition, the NMR analysis results are as shown in Fig. 9.

[0258]

[0259] Manufacturing Example 5

[0260] An oligomer was prepared using the same method as in Manufacturing Example 1, but the monomers used during the reaction were different. The prepared oligomers are as follows:

[0261]

[0262] The GPC analysis results for the oligomer of the above manufacturing example 2 are as shown in Fig. 10. In addition, the NMR analysis results are as shown in Fig. 11.

[0263]

[0264] The results of the analysis of the oligomers of the above manufacturing examples 1 to 5 are summarized in Table 1 below:

[0265] Manufacturing Example 1 Manufacturing Example 2 Manufacturing Example 3 Manufacturing Example 4 Manufacturing Example 5 GPCMn41794102166347672691Mw69446763785575913703PDI1.681.651.681.591.38NMRA(6.44)OOOOOB(5.89)OOOOOC(5.61)O(39.0)O(39.3)O(9.3)O(22.1)XD(4.91)O(87.9)O(89.6)O(77.6)O(86.4)O(61.0)E(6.48)XXO(16.1)XO(22.3)F(6.49)XXOXOG(3.41)OOOOO

[0266] Experimental Example 1

[0267] Check physical properties

[0268] The viscosity of the oligomers of the above manufacturing examples 1 to 5 was measured, and the mechanical properties were measured after 3D printing.

[0269] In order to measure the mechanical properties, the oligomers of the above Preparation Examples 1 to 5, the compound represented by the following Chemical Formula 7, and the compound represented by the following Chemical Formula 8 were mixed in a weight ratio of 1:1:1, and 1 part by weight of DPPO was mixed with 100 parts by weight of the mixture to prepare a polymer composition (Examples 1 to 5), which was then placed in a 3D printer and prepared into a specimen:

[0270] [Chemical Formula 7]

[0271]

[0272] [Chemical Formula 8]

[0273]

[0274] Specifically, flexural strength was measured according to ISO 20795-2 and ISO 10477, and tensile strength was measured according to ASTM D638.

[0275] Example 1 Example 2 Example 3 Example 4 Example 5 Batch Size 50L 50L 50L 50L 50L Mechanical Properties after Blending and 3D Printing Flexural Strength (20795-2 Specimen, MPa) 171 162 155 163 150 Flexural Elasticity (20795-2 Specimen, MPa) 39 39 380 7 380 0 36 55 359 4 Flexural Strength (10477 Specimen, MPa) 146 122 162 158 143 Tensile Strength (D 638, MPa) 109 102 115 113 108 Elongation (D 638, %) 3.9 3.0 7.6 6.5 7.7 Viscosity (psi) 28 80 295 0 222 0 238 0 2380

[0276] It was confirmed that the specimens manufactured using the oligomers of the above manufacturing examples 1 to 5 exhibited excellent mechanical properties, and it was confirmed that printing using a 3D printer was possible through appropriate viscosity.

[0277]

[0278] Experimental Example 2

[0279] Manufacturing of transparent orthodontic devices

[0280] The photocurable compositions of Examples 1 to 5, manufactured in Experimental Example 1, were placed in each DLP-type 3D printer and printed using a transparent orthodontic device. The manufactured transparent orthodontic device underwent a post-curing process. Specifically, the same process of washing using a dehydrator was performed to remove any remaining resin and protruding surfaces.

[0281] Afterwards, the orthodontic device was placed in a box, completely oxygen-blocking under a nitrogen atmosphere, and UV irradiated for 25 minutes. The orthodontic device was immersed in a bath containing glycerol and UV irradiated for 25 minutes to perform a secondary post-curing process. The secondary post-cured orthodontic device was treated with hot water at 80 to 100°C to complete the post-curing process.

[0282] Comparative Example 1

[0283] Using the photocurable composition of Example 1, a transparent orthodontic device was printed using a DLP-type 3D printer, the transparent orthodontic device was washed using a dehydrator, and the washed transparent orthodontic device was exposed to room temperature (20 to 25°C) for 50 minutes, except that the same process as Experimental Example 2 was performed.

[0284] Comparative Example 2

[0285] Using the photocurable composition of Example 1, a transparent orthodontic device was printed using a DLP-type 3D printer, and the transparent orthodontic device was washed using a dehydrator. The washed transparent orthodontic device was first UV-irradiated in a nitrogen environment for 25 minutes, and then UV-irradiated again for 25 minutes under the same conditions, except that the device was manufactured in the same manner as in Experimental Example 2.

[0286] Comparative Example 3

[0287] A photocurable composition was prepared in the same manner as in Example 1, except that a compound represented by the following chemical formula 9 was used as the photocurable oligomer, and a transparent orthodontic device was prepared in the same manner as in Experimental Example 2, and the post-curing process was completed. The photocurable oligomer is a compound represented by the following chemical formula 1, and includes both a compound in which A is selected by the chemical formula 10 and a compound in which A is selected by the chemical formula 11, and includes the compound selected by the chemical formula 10 and the compound selected by the chemical formula 11 in a weight ratio of 1:1.5.

[0288] [Chemical Formula 9]

[0289]

[0290] [Chemical Formula 10]

[0291]

[0292] [Chemical Formula 11]

[0293]

[0294] Here,

[0295] n is an integer from 1 to 1,000,

[0296] * indicates the part to be combined,

[0297] R1 to R6 are methyl groups.

[0298]

[0299] Transparency check

[0300] For the transparent orthodontic devices manufactured in Example 1, Comparative Example 1 and Comparative Example 2, in order to create conditions similar to the usage environment in the oral cavity, they were immersed in a water tank containing water at 37°C for 24 hours, and then the degree of transparency was visually confirmed.

[0301] The results are as shown in Fig. 12. Fig. 12 (a) is the transparent orthodontic device of Comparative Example 1, (b) is the transparent orthodontic device of Example 1, and (c) is the transparent orthodontic device of Comparative Example 2.

[0302] As shown in Fig. 12, it can be confirmed that (b) appears remarkably transparent.

[0303] Specifically, photocuring behavior in air-exposed environments is inhibited by oxygen radical scavenging. As shown in Fig. 12, the orthodontic device cured in an air environment exhibits a decrease in transparency after immersion for 24 hours. This result suggests that the surface forms a relatively low crosslinking density, making it sensitive to moisture, which leads to a decrease in transparency.

[0304] In addition, in the case of Comparative Example 2, two post-curing processes were performed without immersion in glycerol, which resulted in a high curing density and improved transparency as glycerol was used and glycerol absorbed heat energy by UV irradiation and uniformly transferred it into the transparent orthodontic device.

[0305] Whether or not surface bubbles occur

[0306] It was confirmed that the transparent orthodontic device of Example 1 was first cured in a nitrogen atmosphere and then immersed in glycerol to undergo a second curing process, and that no bubbles were generated.

[0307] Stress relaxation and creep evaluation results

[0308] In order to conduct stress relaxation and creep evaluation, the photocurable composition of Example 1 was printed into a specimen with a width of 5 mm, a length of 40 mm, and a thickness of 0.4 mm, and a post-curing process was performed in the same manner as in Experimental Example 2 of the present invention.

[0309] PETG was used as a control group, and PETG was also processed into specimens with a width of 5 mm, a length of 40 mm, and a thickness of 0.4 mm.

[0310] Comparative Example 3 used a different photocurable composition from Example 1, printed as a specimen measuring 5 mm in width, 40 mm in length, and 0.4 mm in thickness, and performed a post-curing process in the same manner as Experimental Example 2 of the present invention.

[0311] With regard to stress relaxation and creep behavior, when a load was applied for 60 minutes at 37℃, the specimen of the present invention initially showed rapid stress relaxation. A residual static force of 1.0 N was observed after 13 repeated loading cycles. Stress relaxation also occurred in the PETG specimen, but the amount of relaxation was smaller than that of the specimen of the present invention, and the residual static force after 13 repeated loading cycles was 11.39 N. In the case of Comparative Example 2, stress relaxation also occurred, but the amount of relaxation was smaller than that of the specimen of the present invention, and the residual static force after 13 repeated loading cycles was 0.5 N, confirming that it did not exert sufficient force required for tooth movement.

[0312] In general, in clinical orthodontic practice, it is known that a force of 0.098 to 1.18 N is required for tooth movement. Excessive orthodontic force can cause adverse effects, such as root resorption, in the teeth and surrounding tissues. Furthermore, applying force that exceeds the patient's pain threshold can cause discomfort. The static force demonstrated by the specimen of the present invention at 37°C corresponds to the appropriate orthodontic force required for orthodontic devices.

[0313] Detection of unreacted organic matter

[0314] The transparent orthodontic device of Example 1 was washed by treating it with hot water at 80 to 100°C for 5 minutes to remove unreacted monomers. An experiment was conducted based on ISO 20798-2 using a gas chromatography tandem mass spectrometer.

[0315] In all of the transparent orthodontic devices of Examples 1 to 5 manufactured in Experimental Example 2, no MMA (methyl methacrylate) elution was found as the unreacted monomer was removed by the post-curing process of the present invention.

[0316] Although the preferred embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements made by those skilled in the art using the basic concept of the present invention defined in the following claims also fall within the scope of the present invention.

[0317] The present invention relates to a post-curing method for a 3D printed output using a photocurable composition and a transparent orthodontic device manufactured by the method, and more particularly, to a post-curing method capable of improving the quality of a product by post-curing an output printed through 3D printing using a photocurable composition capable of manufacturing a dental product such as a transparent orthodontic device, and a transparent orthodontic device manufactured by the method.

Claims

1. A photocurable composition comprising a photocurable oligomer, monomer, photoinitiator and stabilizer represented by the following chemical formula 1 is used to manufacture an output using a 3D printer. To remove the protrusions and residual resin remaining on the surface of the above output, place it in a rotating body and wash it. The above washed output is subjected to a first post-curing process in an inert gas environment, The first post-cured output is immersed in oil and subjected to a second post-curing process. Treating the above second post-cured output with hot water Post-curing method for 3D printed output using photocurable composition: [Chemical Formula 1] [Chemical Formula 2] [Chemical Formula 3] [Chemical Formula 4] [Chemical Formula 5] [Chemical Formula 6] Here, n is an integer from 1 to 100, m is an integer from 1 to 50, A, B, C and D are the same or different from each other and are repeating units each independently selected from the group consisting of compounds represented by chemical formulas 2 to 6, a, b, c and d are the same or different and are each independently an integer from 1 to 30, R1 and R2 are the same or different, and can each be independently selected from the group consisting of hydrogen, deuterium, a substituted or unsubstituted alkyl group having 1 to 30 carbon atoms, a substituted or unsubstituted alkenyl group having 2 to 30 carbon atoms, a substituted or unsubstituted alkynyl group having 2 to 30 carbon atoms, a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, and a substituted or unsubstituted heteroaryl group having 1 to 30 carbon atoms.

2. In paragraph 1, A, B and D of the photocurable oligomer represented by the above chemical formula 1 are the same or different from each other, and are repeating units independently selected from compounds represented by chemical formula 2 or 3. The above C is a repeating unit selected from the group consisting of compounds represented by chemical formulas 4 to 6. A post-curing method for 3D printed output using a photocurable composition.

3. In paragraph 1, The above photocurable oligomer has a number average molecular weight (Mn) of 1,500 to 6,000. A post-curing method for 3D printed output using a photocurable composition.

4. In paragraph 1, The above photocurable oligomer has a weight average molecular weight (Mw) of 2,500 to 9,000. A post-curing method for 3D printed output using a photocurable composition.

5. In paragraph 1, The above photocurable oligomer has a viscosity of 2,000 mPa·s to 3,500 mPa·s. A post-curing method for 3D printed output using a photocurable composition.

6. In paragraph 1, The above 3D printer is either DLP or SLA type. A post-curing method for 3D printed output using a photocurable composition.

7. In paragraph 1, The above inert gas is selected from the group consisting of nitrogen, argon, helium, krypton, neon and mixtures thereof. A post-curing method for 3D printed output using a photocurable composition.

8. In paragraph 1, The above oils are selected from the group consisting of glycerol, edible oil, castor oil, non-reactive silicone oil and mixtures thereof. A post-curing method for 3D printed output using a photocurable composition.

9. In paragraph 1, The above hot water is hot water of 80℃ to 100℃. A post-curing method for 3D printed output using a photocurable composition.

10. Manufactured by a post-curing method of a 3D print output according to any one of clauses 1 to 6, Excellent orthodontic effect due to shape memory properties Clear orthodontic devices.

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