Resin composition for 3D printing, method for preparing same, and transparent aligner comprising same

Abstract

The present invention relates to a 3D printing resin composition for a transparent aligner, a method for preparing same, and a transparent aligner formed by 3D printing using same, the composition comprising 5-20 wt% UDMA (urethane dimethacrylate), 40-70 wt% BIS-GMA (bisphenol A-glycidyl methacrylate), 8-30 wt% BIS-EMA (ethoxylated bisphenol A dimethacrylate), 2-5 wt% TEGDMA (triethylene glycol dimethacrylate), 8-9 wt% modified PVA powder, 5-9 wt% of a filler, 0.72-3.7 wt% of a curing agent, and 0.1-1.0 wt% of an additive, wherein the transparent aligner can be modified to have a structure optimized for the oral cavities of individual users, and thus can maximize the aligning effect.

Description

Resin composition for 3D printing, method for manufacturing the same, and clear orthodontic device including the same

[0001] The present invention relates to a resin composition for 3D printing, a method for manufacturing the same, and a clear orthodontic device including the same. More specifically, the invention relates to a resin composition for 3D printing that includes PVA and can be transformed into a structure optimized for the individual user's oral cavity after wearing the clear orthodontic device to maximize the orthodontic effect, a method for manufacturing the same, and a clear orthodontic device including the same.

[0002] [Project ID] S3366980

[0003] [Ministry Name] Ministry of SMEs and Startups

[0004] [Name of Project Management (Specialized) Agency] Korea Technology Information Promotion Agency for SMEs

[0005] [Research Project Name] Regional Specialized Industry Development+(R&D)

[0006] [Research Project Title] Development of Domestic Materials for Transparent Orthodontic Devices Using Fluorine and Natural Polymers to Prevent Orthodontic Caries

[0007] [Name of Project Performing Organization] Healings

[0008] [Research Period] April 1, 2023 – December 31, 2024

[0009] Generally, malocclusion, characterized by uneven teeth alignment or disharmony between the upper and lower jaws, can be caused by genetics, bad habits affecting teeth, or developmental abnormalities. While this may simply detract from external beauty, it can also lead to reduced chewing function due to an uneven oral structure and increase the risk of tooth decay; therefore, orthodontic procedures are widely performed to balance the upper and lower jaws and align teeth into uniform and even arrangements.

[0010] Orthodontics is a procedure that involves attaching brackets to the teeth, securing orthodontic wires and rubber bands to the brackets to move the teeth to a desired position, and maintaining this position for an extended period to realign the teeth. Since the brackets and wires used are generally made of metal, they have the disadvantage of being highly visible. Because this directly impacts appearance, clear aligners, which are worn on the teeth to correct alignment, have recently been proposed.

[0011] Transparent orthodontics is a method of realigning teeth by replacing transparent braces manufactured using 3D printing in stages. It has the advantage of not significantly affecting the user's daily social life because it is inconspicuous and removable.

[0012] However, since these clear aligners are made of hard materials for the purpose of correcting teeth, they cause significant pain when worn. Additionally, errors occurring during scanning or device fabrication lead to inaccurate correction, resulting in increased time and cost consumption as devices must be remade and the direction of correction readjusted.

[0013] The present invention aims to provide a resin composition for 3D printing that can be transformed into a structure optimized for the individual user's oral cavity after wearing a clear orthodontic device to maximize the orthodontic effect, a method for manufacturing the same, and a clear orthodontic device including the same.

[0014] A 3D printing resin composition for a clear orthodontic device according to one embodiment of the present invention for achieving the purpose described above comprises UDMA (urethane dimethacrylate), BIS-GMA (bisphenol A-glycidyl methacrylate), BIS-EMA (ethoxylated bisphenol A dimethacrylate), TEGDMA (triethylene glycol dimethacrylate), modified PVA powder, a filler, a curing agent, and an additive.

[0015] More specifically, the 3D printing resin composition for the clear orthodontic device may comprise 5-20 wt% of UDMA (urethane dimethacrylate), 40-70 wt% of BIS-GMA (bisphenol A-glycidyl methacrylate), 8-30 wt% of BIS-EMA (ethoxylated bisphenol A dimethacrylate), 2-5 wt% of TEGDMA (triethylene glycol dimethacrylate), 8-9 wt% of modified PVA powder, 5-9 wt% of filler, 0.72-3.7 wt% of curing agent, and 0.1-1.0 wt% of additive.

[0016] Another embodiment of the present invention may be a method for preparing a 3D printing resin composition for a clear orthodontic device, comprising: a first step of preparing a polymer mixture by mixing UDMA (urethane dimethacrylate), BIS-GMA (bisphenol A-glycidyl methacrylate), BIS-EMA (ethoxylated bisphenol A dimethacrylate), and TEGDMA (triethylene glycol dimethacrylate); a second step of preparing a base composition by mixing the polymer mixture with a curing agent and an additive; and a third step of preparing a 3D printing resin composition by mixing the base composition with modified PVA powder and a filler.

[0017] The 3D printing resin composition prepared through the above third step preferably comprises 5-20 wt% UDMA (urethane dimethacrylate), 40-70 wt% BIS-GMA (bisphenol A-glycidyl methacrylate), 8-30 wt% BIS-EMA (ethoxylated bisphenol A dimethacrylate), 2-5 wt% TEGDMA (triethylene glycol dimethacrylate), 8-9 wt% modified PVA powder, 5-9 wt% filler, 0.72-3.7 wt% curing agent, and 0.1-1.0 wt% additive.

[0018] The modified PVA powder used in the present invention is preferably modified through a first modification step of uniformly mixing PVA powder and isopropyl alcohol and storing at a low temperature of 4°C or lower; and a second modification step of uniformly mixing the mixture obtained through the first modification step with polymethyl methacrylate and storing at a low temperature of 0°C or lower.

[0019] In addition, the curing agent may include at least one selected from the group consisting of a photoinitiator, a photoinitiation aid, and an accelerator.

[0020] Another embodiment of the present invention may be a clear orthodontic device manufactured by 3D printing a 3D printing resin composition for a clear orthodontic device or a 3D printing resin composition manufactured by the method for manufacturing a 3D printing resin composition for a clear orthodontic device.

[0021] The resin composition for 3D printing of the present invention has the advantage of enabling more effective and efficient correction by being able to maximize the orthodontic effect by being deformed into a structure optimized for the individual user's oral cavity after wearing a clear aligner.

[0022] Before describing the preferred embodiments of the present invention in detail below, it should be noted that the terms and words used in this specification and claims should not be interpreted as being limited to their ordinary or dictionary meanings, but should be interpreted in a meaning and concept consistent with the technical spirit of the present invention.

[0023] Throughout this specification, when a part is described as “comprising” a certain component, it means that, unless specifically stated otherwise, it does not exclude other components but may include additional components.

[0024] Throughout this specification, “%” used to indicate the concentration of a specific substance means (weight / weight)% for solid / solid, (weight / volume)% for solid / liquid, and (volume / volume)% for liquid / liquid, unless otherwise noted.

[0025] In each step, identification codes are used for convenience of explanation and do not describe the order of the steps; unless the context clearly indicates a specific order, the steps may be performed differently from the specified order. That is, the steps may be performed in the same order as specified, substantially simultaneously, or in the reverse order.

[0026] Hereinafter, embodiments of the present invention are examined. However, the scope of the present invention is not limited to the following preferred embodiments, and a person skilled in the art to which the present invention pertains may implement various modified forms from the contents described in the specification.

[0027] The present invention relates to a 3D printing resin composition for a clear aligner, a method for manufacturing the same, and a clear aligner comprising the same. By applying a 3D printing method, it is possible to provide a user-customized orthodontic device, and the invention has the advantage of enabling rapid treatment due to the short production time of the orthodontic device.

[0028] Furthermore, after the user wears these clear aligners, their structure modulates more precisely to match the user's oral structure, ensuring a secure fit against the teeth and maximizing the orthodontic effect. In addition, the transparent appearance of the aligners allows for a more precise assessment of the user's oral condition, and the ability to immediately verify the realigned teeth after treatment enhances patient satisfaction.

[0029] One embodiment of the present invention relates to a 3D printing resin composition for a clear orthodontic device, wherein the 3D printing resin composition according to this embodiment may comprise 5 to 20 wt% of UDMA (urethane dimethacrylate), 40 to 70 wt% of BIS-GMA (bisphenol A-glycidyl methacrylate), 8 to 30 wt% of BIS-EMA (ethoxylated bisphenol A dimethacrylate), 2 to 5 wt% of TEGDMA (triethylene glycol dimethacrylate), 8 to 9 wt% of modified PVA powder, 5 to 9 wt% of a filler, 0.72 to 3.7 wt% of a curing agent, and 0.1 to 1.0 wt% of an additive.

[0030] The above UDMA, BIS-GMA, BIS-EMA, and TEGDMA are polymeric materials that form the basic structure of a clear orthodontic device manufactured using a 3D printing resin composition, modified PVA powder is a material added for precise structural modification of the clear orthodontic device, a curing agent is a material that initiates the photocuring of these polymers, and fillers and additives are added to improve the physical and chemical properties of the clear orthodontic device manufactured using a 3D printing resin composition.

[0031] The above UDMA (urethane dimethacrylate) is added to reduce polymerization shrinkage and improve elasticity and toughness, and may be included in the 3D printing resin composition at 5 to 20 wt%. If the content of UDMA is below the above range, it is difficult to obtain the effects described above, and if the content of UDMA exceeds the above range, the content of BIS-GMA is relatively reduced, making it difficult to secure sufficient flexural strength; therefore, it is preferable to include it within the above weight range.

[0032] The above BIS-GMA (bisphenol A-glycidyl methacrylate) contains two hydrophobic methacrylate groups and is suitable as a matrix resin due to its low volatility and polymerization shrinkage, fast curing, large molecular weight, and high stability. However, because it is difficult to mix uniformly with other components due to its high viscosity and poor workability, it is used together with BIS-EMA to lower the viscosity.

[0033] The above BIS-GMA may be pure BIS-GMA, modified BIS-GMA, or a mixture comprising both, wherein the modified BIS-GMA may include at least one of DMBIS-GMA (2,2-bis[3-methyl, 4-(2-hydroxy-3-methacryloyloxy propoxy) phenyl] propan) and TMBIS-GMA (2,2-bis[3-methyl, 4-(2-hydroxy-3-methacryloyloxy propoxy) phenyl] propan).

[0034] BIS-GMA may be included in the entire composition at 40 to 70 wt%. If included in an amount less than the above weight range, it is difficult to secure sufficient strength, and if included in an amount exceeding the above weight range, it is difficult to perform a uniform stirring process due to excessively high viscosity, so it is preferable to include it within the above weight range.

[0035] The above BIS-EMA (ethoxylated bisphenol A dimethacrylate) is added to lower the viscosity resulting from the use of BIS-GMA and may be included in the 3D printing resin composition in an amount of 8 to 30 wt%. If included in an amount less than the above weight range, sufficient viscosity reduction for uniform stirring is not achieved, and if included in an amount exceeding the above weight range, it is difficult to secure sufficient strength after curing and the formulation may become difficult to apply to 3D printing due to excessive viscosity reduction; therefore, it is preferable to include it within the weight range described above.

[0036] The above TEGDMA (triethylene glycol dimethacrylate) is added as a viscosity modifier for application in 3D printing and may be included in the total composition at 2 to 5 wt%. If TEGDMA is included in an amount less than the above weight range, the viscosity characteristics required for 3D printing are not satisfied, and if it is included in an amount exceeding the above weight range, there is a possibility of defects occurring due to excessive polymerization shrinkage; therefore, it is preferable to include it within the above weight range.

[0037] The above modified PVA (poly vinyl alcohol) powder is a water-soluble polymer and is included in a clear aligner formed by 3D printing a 3D printing resin composition. It performs the function of improving the adhesion of the clear aligner and enhancing the corrective force by the clear aligner by precisely deforming the clear aligner to fit the user's oral structure after wearing the clear aligner. Specifically, the modified PVA powder reacts with a liquid such as saliva in the oral cavity at a normal oral temperature (36~37.5℃) and dissolves, thereby naturally increasing the elasticity of the clear aligner. Due to this increase in elasticity, the clear aligner adheres to the user's oral structure, thus enhancing the corrective force by the clear aligner.

[0038] In addition, while general PVA powder is off-white, the present invention modifies the PVA powder to be transparent so as not to impair the appearance of the clear orthodontic device. Through this modification process, not only is the color simply changed, but foreign substances on the surface of the PVA powder are removed and the surface is cleaned, so that the adhesion effect of the modified PVA powder can be further enhanced when wearing the clear orthodontic device.

[0039] This modified PVA powder may be included in the 3D printing resin composition at 8 to 9 wt%. If it falls outside this range, problems such as the elongation of the clear aligner becoming excessively low, making it difficult to wear, or the elongation becoming excessively high, resulting in reduced orthodontic effect, or the occurrence of dimensional errors in the output obtained by 3D printing the 3D printing resin composition may arise. Therefore, it is desirable to include it within the weight range described above.

[0040] The above modified PVA powder may be modified through a first modification step of uniformly mixing PVA powder and isopropyl alcohol and storing at a low temperature of 4°C or lower; and a second modification step of uniformly mixing the mixture obtained through the first modification step with polymethyl methacrylate and storing at a low temperature of 0°C or lower.

[0041] The above first modification step is a step of uniformly mixing PVA powder and isopropyl alcohol and then storing at a low temperature of 4°C or lower.

[0042] In this step, the first step involves mixing 85 to 120 parts by weight of isopropyl alcohol with 100 parts by weight of PVA powder. At this time, mixing can be performed under conditions of a temperature of 30 to 40 ℃ and a stirring speed of 3 to 10 rpm, and stirring can be performed under reduced pressure conditions with a vacuum gauge pressure of 0.05 to 0.2 MPa to prevent bubbles. Stirring can be performed for 6 to 20 hours. Through this stirring process, the PVA powder and isopropyl alcohol are uniformly mixed, removing foreign substances from the surface of the PVA powder and making the surface clean and dry. Consequently, the reaction or dissolution of PVA by liquids such as saliva in the oral cavity after wearing a clear aligner can be more effectively induced.

[0043] After stirring, the mixture of PVA powder and isopropyl alcohol can be stored at a low temperature of 4°C or lower. Through this low-temperature storage process, surface shrinkage of the PVA powder occurs, optimizing the refraction and reflection of light to produce a transparent effect.

[0044] The above second modification step is a step of uniformly mixing the mixture obtained through the above first modification step with polymethyl methacrylate and then storing it at a low temperature of 0°C or lower.

[0045] Since the mixture obtained through the first modification step is stored at a low temperature and is slightly solidified, the second modification step can be performed after imparting plasticity by stirring at room temperature for 1 to 5 hours before performing the second modification step.

[0046] In the second modification step, 91–95 wt% of the mixture obtained through the first modification step and 5–9 wt% of polymethyl methacrylate are first mixed, and the raw materials can be uniformly mixed by stirring for 6–12 hours at 3–10 rpm at 45–60°C under reduced pressure conditions with a vacuum gauge pressure of 0.05–0.2 MPa. During this process, polymethyl methacrylate can form a fine transparent layer on the surface of the PVA powder.

[0047] Subsequently, a mixture of PVA powder, isopropyl alcohol, and polymethyl methacrylate can be stored at a low temperature of 0°C or lower for 9 to 20 hours. Through this low-temperature storage process, surface shrinkage of the PVA powder occurs, and polymethyl methacrylate can be effectively adsorbed onto the surface of the PVA powder. This allows the light transmittance of the PVA powder to be significantly improved, and a transparently modified PVA powder can be obtained.

[0048] Afterwards, a drying step may be performed to remove isopropyl alcohol, which is the solvent used in the modification process, and the drying may be performed at room temperature. If necessary, the modified PVA powder may be physically filtered through a filtration device and then dried, and a drying process may be performed for 20 to 40 hours at room temperature of 20 to 30 ℃.

[0049] This modified PVA powder can effectively adhere the clear aligner to the user's oral structure after wearing without compromising the appearance of the clear aligner.

[0050] The above-mentioned filler is added to improve the physical strength and wear resistance of a clear orthodontic device obtained by 3D printing a resin composition for 3D printing, and to maintain a transparent appearance, and may be included in the total composition in a weight range of 5 to 9 wt%. In order to obtain improved strength, durability, and aesthetic effects through the filler, while preventing problems such as filler detachment or reduced bonding strength due to an increase in the amount of filler, it is preferable that the filler be included within the weight range described above.

[0051] Examples of such fillers may include silica, strontium aluminum silicate, barium aluminum silicate, barium glass, kaolin, talc, radiopaque glass powder, and zirconia compounds, but the types of fillers that can be applied to this embodiment are not limited thereto.

[0052] The above curing agent is a substance added to initiate the photocuring reaction of a polymer material and to cure the resin composition during 3D printing upon light irradiation. The curing agent may include at least one selected from the group consisting of photoinitiators, photoinitiation aids, and accelerators, and preferably all of them may be included.

[0053] This curing agent may be included in the total 3D printing resin composition in an amount of 0.72 to 3.7 wt%. If the amount falls outside the weight range described above, problems such as insufficient curing or uneven curing may occur, which may result in the inability to mold the clear aligner into a desired shape or, even if molded into a desired shape, uneven physical properties may appear overall. Therefore, it is preferable to include it within the weight range described above.

[0054] The above photoinitiator is a material characterized by being activated by light irradiation to form radicals, and the radicals thus formed can initiate the photopolymerization reaction of BIS-GMA, BIS-EMA, UDMA, and TEGDMA, thereby causing the curing reaction of the 3D printing resin composition. It is preferable that the photoinitiator be included in the total composition at 0.5 to 2.5 wt% to induce a sufficient photocuring reaction.

[0055] For example, curing agents for dental curing materials such as camphoquinone and TPO (2,4,6-trimethyl benzoyl-diphenylphosphine oxide) may be used as such photoinitiators, and any photoinitiator applicable to curing materials for dental equipment or materials may be applied to the present invention without being limited to the types listed above. In particular, to ensure desirable curing characteristics and safety, one or more of camphoquinone or TPO may be used, and more preferably, a mixture of these may be used.

[0056] The above photoinitiation aid is added to assist photoinitiation by the photoinitiator, and for example, DIFP (diphenyliodonium hexafluorophosphate) may be used, but is not limited thereto, and may be included in the total composition at 0.02 to 0.2 wt%.

[0057] The above-mentioned promoter may be added to promote photoinitiation by increasing the radical generation efficiency of the photoinitiator by light irradiation. For example, at least one selected from the group consisting of EDMAB (ethyl (4-dimethylamino) benzoate), DMABA (4-(dimethylamino)benzoic acid), DMABZR (4-(dimethylamino)benzaldehyde), DMAEMA (2-(dimethylamino)ethyl methacrylate), DMAEA (2-(dimethylamino)ethyl acrylate), DEAEMA (2-(diethylamino)ethyl methacrylate), and DEAEA (2-(diethylamino)ethyl acrylate) may be used as such a promoter, but is not limited thereto. The promoter may be included in the total composition at 0.2 to 1 wt%.

[0058] The above additive is a substance added to manufacture a resin composition for 3D printing, to improve characteristics such as workability and physical properties when using the same, or to improve the physical properties of a clear orthodontic device obtained by curing the same. The additive may include antioxidants or anti-discoloration agents, and may be used as long as it is an additive that can be used in dental curable materials, without being limited thereto. The additive may be included in the resin composition for 3D printing at 0.1 to 1.0 wt%.

[0059] The above antioxidant is added to prevent degradation of the resin composition for 3D printing or clear aligner due to oxidation, and may include butylated hydroxy toluene (BHT) or commercial products such as Irganox, but is not limited thereto, and may be included in the total composition at 0.05 to 0.5 wt%.

[0060] The above anti-discoloration agent is added to prevent discoloration caused by ultraviolet rays in a 3D printing resin composition or a clear aligner formed by 3D printing the same, and the product name is Tinuvin ® , Tinopal ® A discoloration inhibitor such as the one described above may be used. It is preferable that the above discoloration inhibitor be included in the resin composition for 3D printing at a concentration of 0.05 to 0.5 wt% to obtain a discoloration prevention effect while preventing the deterioration of the physical properties of the resin composition for 3D printing.

[0061] Another embodiment of the present invention relates to a method for manufacturing a 3D printing resin composition for a clear aligner, and since the 3D printing resin composition according to one embodiment of the present invention described above can be manufactured according to this embodiment, some overlapping descriptions are omitted.

[0062] A method for preparing a 3D printing resin composition for a clear orthodontic device according to the present embodiment comprises: a first step of preparing a polymer mixture by mixing UDMA (urethane dimethacrylate), BIS-GMA (bisphenol A-glycidyl methacrylate), BIS-EMA (ethoxylated bisphenol A dimethacrylate), and TEGDMA (triethylene glycol dimethacrylate); a second step of preparing a base composition by mixing the polymer mixture with a curing agent and an additive; and a third step of preparing a 3D printing resin composition by mixing the base composition with modified PVA powder and a filler.

[0063] The first step above is to prepare a polymer mixture by mixing UDMA (urethane dimethacrylate), BIS-GMA (bisphenol A-glycidyl methacrylate), BIS-EMA (ethoxylated bisphenol A dimethacrylate), and TEGDMA (triethylene glycol dimethacrylate).

[0064] This step involves mixing 5 to 20 wt% of UDMA (urethane dimethacrylate), 40 to 70 wt% of BIS-GMA (bisphenol A-glycidyl methacrylate), 8 to 30 wt% of BIS-EMA (ethoxylated bisphenol A dimethacrylate), and 2 to 5 wt% of TEGDMA (triethylene glycol dimethacrylate), wherein the composition ratio refers to the weight ratio within the final 3D printing resin composition. In this step, stirring may be performed for 30 to 100 minutes, and the stirring time may vary depending on the season; within the above stirring time range, stirring may be performed for a short time during the summer and for a long time during the winter.

[0065] At this stage, stirring can be performed at a stirring speed of 5 to 10 rpm at a temperature of 25 to 60°C, and stirring can be performed under vacuum to prevent bubbles. The vacuum can be, for example, a condition of gauge pressure of 0.05 to 0.2 MPa.

[0066] In addition, the first step described above may be performed under light irradiation, wherein the wavelength of the light source is 330 to 510 nm, which may vary depending on the absorption wavelength of the photoinitiator. For example, when camphoquinone is used as the photoinitiator, light of 450 to 480 nm may be irradiated, and when TPO is used, light of 350 to 430 nm may be irradiated. Furthermore, as previously explained, since a vacuum is applied during the stirring process, bubble formation is prevented, thereby reducing light distortion caused by bubbles and consequently increasing the exposure area of ​​the raw material mixture to the light source, allowing for more efficient and effective light irradiation.

[0067] As the first step is performed under light irradiation conditions on a polymer mixture that does not contain a photoinitiator in this manner, the polymer mixture is photoreactively modified, and since the activation of the polymer to light occurs more rapidly and effectively during subsequent photocuring, the quality of the cured body can be improved.

[0068] The second step above is a step of preparing a base composition by mixing the polymer mixture with a curing agent and an additive. These components are the same as those described above in one embodiment of the present invention, and each raw material may be mixed in this step so that the curing agent is included in the final 3D printing resin composition in an amount of 0.72 to 3.7 wt% and the additive in an amount of 0.1 to 1.0 wt%.

[0069] The stirring conditions at this stage may be a temperature of 25 to 60°C and a stirring speed of 5 to 15 rpm, and if stirring is performed under vacuum conditions to remove bubbles, a vacuum of 0.05 to 0.2 MPa vacuum gauge pressure may be applied.

[0070] The third step above is a step of preparing a 3D printing resin composition by mixing the base composition, modified PVA powder, and a filler, wherein the modified PVA powder and the filler are the same as those described above in one embodiment of the present invention.

[0071] Specifically, this step may involve uniformly mixing the base composition, modified PVA powder, and filler under temperature conditions of 25 to 60°C, and then aging the mixture at 25 to 35°C for at least 36 hours. During mixing, the stirring speed may be 5 to 10 rpm, and a vacuum may be applied to prevent bubbles; in this case, the vacuum gauge pressure may be 0.05 to 0.2 MPa. The aging process may be performed to stabilize the properties of the 3D printing resin composition by stabilizing the surface of the activated filler, partially recovering the basic properties of the polymer damaged during the stirring process, and strengthening cross-linking between the polymer and the filler.

[0072] The 3D printing resin composition produced through this step may comprise 5-20 wt% of UDMA (urethane dimethacrylate), 40-70 wt% of BIS-GMA (bisphenol A-glycidyl methacrylate), 8-30 wt% of BIS-EMA (ethoxylated bisphenol A dimethacrylate), 2-5 wt% of TEGDMA (triethylene glycol dimethacrylate), 8-9 wt% of modified PVA powder, 5-9 wt% of filler, 0.72-3.7 wt% of curing agent, and 0.1-1.0 wt% of additive. The 3D printing resin composition produced through this process may be a 3D printing resin composition according to one embodiment of the present invention.

[0073] Another embodiment of the present invention relates to a clear orthodontic device comprising a resin composition for 3D printing according to one embodiment of the present invention, or a resin composition for 3D printing manufactured according to a method for manufacturing a resin composition for 3D printing according to another embodiment of the present invention. The present invention includes a clear orthodontic device formed by 3D printing the resin composition for 3D printing described above.

[0074] Hereinafter, the specific operation and effects of the present invention will be explained through an embodiment of the present invention. However, this is presented as a preferred example of the present invention, and the scope of the rights of the present invention is not limited according to the embodiment.

[0075]

[0076] [Preparation Example]

[0077] First, UDMA, BIS-GMA, BIS-EMA, and TEGDMA were placed in a vacuum mixer and stirred at 45°C at 10 rpm and a vacuum gauge pressure of 0.07 MPa to prepare a polymer mixture. At this time, stirring was carried out under light irradiation with a wavelength of 480 nm. A photoinitiator (camphoquinone), a photoinitiation aid (DIFP), an accelerator (EDMAB), an antioxidant (BHT), and a discoloration inhibitor (Tinuvin) were added to the polymer mixture, and a base composition was prepared by stirring at the same temperature, stirring speed, and vacuum. Subsequently, modified PVA powder and fillers, silica and barium glass, were added to the vacuum mixer containing the base composition and stirred under the same conditions to prepare a homogeneous composition, after which the mixture was aged at 31°C for 40 hours to prepare a 3D printing resin composition. The composition of the 3D printing resin composition prepared in this way is listed in Table 1.

[0078] The modified PVA powder used above was obtained through first and second modification steps. The first modification step was performed by mixing PVA powder and isopropyl alcohol in a weight ratio of 1:1, stirring at 4 rpm for 8 hours under vacuum and 35°C conditions, and then storing at 2°C for 12 hours. Subsequently, plasticity was secured by stirring the mixture at 2 rpm for 2 hours at room temperature. Polymethyl methacrylate was added at 7 wt% relative to the total weight of the mixture, stirred under vacuum at 4 rpm at 50°C for 8 hours, and then stored at 0°C for 12 hours to complete the second modification step. Afterward, the modified PVA powder was separated using a filter and dried at 28°C for 24 hours to obtain the modified PVA powder.

[0079] Raw Material Content (wt%) UDMA 7.4 BIS-GMA 5 2.3 BIS-EMA 19.5 TEGDMA 3.4 Camphorquinone 1.3 DIP 0.1 EDMA B 0.6 BHT 0.2 Tinuvin 0.2 Modified PVA 8 Silica 3 Barium Glass 4

[0080] [Experimental Example 1]

[0081] 3D printing resin compositions were prepared by varying the content of modified PVA powder included in the 3D printing resin composition prepared in the preparation example, and the elongation of the printed object obtained by 3D printing each 3D printing resin composition was measured, and the results are listed in Table 2. Five samples (#1 to #5) were prepared for each 3D printing resin composition and the elongation was measured. Depending on the increase or decrease in the amount of modified PVA powder, the ratio of the remaining raw materials excluding the modified PVA powder was maintained, and the total content was adjusted to offset the change in the content of the modified PVA powder.

[0082] Modified PVA Content (wt%) Elongation (%) #1 #2 #3 #4 #5 3 1.2 1.5 0.9 1.1 1.6 5 2.1 1.5 1.7 2.3 2.1 7 2.8 3.1 3.3 2.9 3.1 8 3.4 3.5 4.0 3.8 3.6 9 3.6 4.1 4.2 4.0 3.8 10 4.5 4.7 5.0 4.8 5.1 11 5.2 5.0 5.2 5.1 5.3 13 5.9 6.0 6.2 5.5 6.7

[0083] Generally, it is known that the elongation of clear aligners worn on teeth is most suitable when it is approximately 3.5–4%. If the elongation is too low, it is difficult to wear and causes discomfort, whereas if it is too high, it is known that orthodontic performance deteriorates. Looking at the experimental results, it was confirmed that the elongation was too low when the modified PVA content was less than 8 wt%, and excessively high when it exceeded 9 wt%. In other words, when the modified PVA content is less than 8 wt%, there are problems such as difficulty wearing and discomfort caused by low elongation, and when it exceeds 9 wt%, there is a concern that orthodontic performance may deteriorate. Therefore, through this experiment, it was confirmed that a modified PVA content of 8–9 wt% is desirable.

[0084] [Experimental Example 2]

[0085] 3D printing resin compositions with varying amounts of modified PVA powder were prepared in the same manner as in Experimental Example 1, and after 3D printing in a square shape of 10×10×10 mm, the error rate between the design area and the printed area was calculated using [Equation 1], and the results are listed in Table 3. Five samples were made for each 3D printing resin composition to calculate the error rate, and the mean and standard deviation of the five samples were calculated and listed in Table 3. The area used for calculating the error rate was based on the upper surface area.

[0086] [Formula 1]

[0087] Modified PVA Content (wt%) Error Rate (%) #1 #2 #3 #4 #5 Mean Standard Deviation 3 2.4 2.1 2.4 2.2 2.6 2.3 0.19 5 2.6 3.0 2.8 2.9 2.5 2.8 0.21 7 3.3 2.7 2.9 3.0 3.1 3.0 22 8 3.1 3.5 3.3 3.0 3.2 3.2 0.19 9 3.3 3.6 3.5 3.3 3.4 3.4 0.13 10 4.9 5.5 3.8 4.2 5.1 4.7 0.69 1 1 5.4 6.7 5.8 5.2 4.8 5.6 0.72 1 3 6.1 5.2 6.3 7.1 5.5 6.00.74

[0088] As a result of the experiment, it was found that when the PVA content was 3 to 9 wt%, the error rate between the design and the printed object was generally low, and the standard deviation between samples was also low. On the other hand, when the PVA content exceeded 9 wt%, the overall error rate was high, but there was a problem with reduced quality stability of the printed object due to the large standard deviation between samples. Therefore, through the results of this experiment, it was confirmed that it is desirable for the modified PVA powder included in the 3D printing resin composition for clear aligners to be included at 9 wt% or less.

[0089] The 3D printing resin composition for a clear orthodontic device according to the present invention comprises 5-20 wt% of UDMA (urethane dimethacrylate), 40-70 wt% of BIS-GMA (bisphenol A-glycidyl methacrylate), 8-30 wt% of BIS-EMA (ethoxylated bisphenol A dimethacrylate), 2-5 wt% of TEGDMA (triethylene glycol dimethacrylate), 8-9 wt% of modified PVA powder, 5-9 wt% of a filler, 0.72-3.7 wt% of a curing agent, and 0.1-1.0 wt% of an additive. By manufacturing a clear orthodontic device by 3D printing this, the structure can be modified to be optimized for the individual user's oral cavity, thereby maximizing the orthodontic effect and thus having industrial applicability.

Claims

1. In a 3D printing resin composition, It comprises UDMA (urethane dimethacrylate), BIS-GMA (bisphenol A-glycidyl methacrylate), BIS-EMA (ethoxylated bisphenol A dimethacrylate), TEGDMA (triethylene glycol dimethacrylate), modified PVA powder, fillers, curing agents, and additives, The above modified PVA powder is, A first modification step of uniformly mixing PVA powder and isopropyl alcohol and storing at a low temperature of 4°C or lower; and A 3D printing resin composition for a clear orthodontic device, characterized by being modified through a second modification step in which a mixture obtained through a first modification step is uniformly mixed with polymethyl methacrylate and then stored at a low temperature of 0°C or lower.

2. In Paragraph 1, The above 3D printing resin composition for a clear orthodontic device comprises 5~20 wt% UDMA (urethane dimethacrylate), 40~70 wt% BIS-GMA (bisphenol A-glycidyl methacrylate), 8~30 wt% BIS-EMA (ethoxylated bisphenol A dimethacrylate), 2~5 wt% TEGDMA (triethylene glycol dimethacrylate), 8~9 wt% modified PVA powder, 5~9 wt% filler, 0.72~3.7 wt% curing agent, and 0.1~1.0 wt% additive.

3. In Paragraph 1, A 3D printing resin composition for a clear orthodontic device, characterized in that the curing agent comprises at least one selected from the group consisting of a photoinitiator, a photoinitiation aid, and an accelerator.

4. A clear orthodontic device manufactured by 3D printing a 3D printing resin composition for a clear orthodontic device described in any one of paragraphs 1 to 3.

5. A method for manufacturing a 3D printing resin composition, A first step of preparing a polymer mixture by mixing UDMA (urethane dimethacrylate), BIS-GMA (bisphenol A-glycidyl methacrylate), BIS-EMA (ethoxylated bisphenol A dimethacrylate), and TEGDMA (triethylene glycol dimethacrylate); A second step of preparing a base composition by mixing the above polymer mixture with a curing agent and an additive; and A third step of preparing a 3D printing resin composition by mixing the above base composition with modified PVA powder and a filler; comprising The above modified PVA powder is, A first modification step of uniformly mixing PVA powder and isopropyl alcohol and storing at a low temperature of 4°C or lower; and A method for manufacturing a 3D printing resin composition for a clear orthodontic device, characterized by being modified through a second modification step in which a mixture obtained through a first modification step is uniformly mixed with polymethyl methacrylate and then stored at a low temperature of 0°C or lower.

6. In Paragraph 5, A method for manufacturing a 3D printing resin composition for a clear orthodontic device, wherein the 3D printing resin composition manufactured through the above third step comprises 5~20 wt% UDMA (urethane dimethacrylate), 40~70 wt% BIS-GMA (bisphenol A-glycidyl methacrylate), 8~30 wt% BIS-EMA (ethoxylated bisphenol A dimethacrylate), 2~5 wt% TEGDMA (triethylene glycol dimethacrylate), 8~9 wt% modified PVA powder, 5~9 wt% filler, 0.72~3.7 wt% curing agent, and 0.1~1.0 wt% additive.

7. In Paragraph 5, A method for manufacturing a 3D printing resin composition for a clear orthodontic device, wherein the curing agent comprises at least one selected from the group consisting of a photoinitiator, a photoinitiation aid, and an accelerator.

8. A clear orthodontic device manufactured by 3D printing a 3D printing resin composition for a clear orthodontic device manufactured by the method described in any one of paragraphs 5 to 7.

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