KR20240039661A - Post-curing method of 3D printed output using photocurable composition and transparent orthodontic device manufactured by same method - Google Patents

Abstract

The present invention relates to a method of post-curing a 3D printed product using a photocurable composition and a transparent orthodontic device manufactured by this method, which can maintain a viscosity suitable for 3D printing and exhibits physical properties that can be used as a dental material. By removing residual resin from prints using a photocurable composition for 3D printing, residual resin is not released even when used in the mouth for a long time, and the curing time is shortened and strength is improved by improving the curing speed through the post-curing process. It provides a post-curing process for 3D printed output that allows the production of output with increased transparency.
Another object of the present invention is that when provided as a transparent orthodontic device, the remaining resin and unreacted monomers of the printed product can be removed, excellent transparency is exhibited, excellent aesthetics, strength is improved, and shape memory properties allow for orthodontic treatment. , To provide a transparent orthodontic device that can provide excellent orthodontic effect and increase convenience of use.

Description

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

The present invention relates to a post-curing method of a 3D printed output using a photocurable composition and a transparent orthodontic device manufactured by the method. Specifically, the present invention relates to a photocurable composition that can produce dental products such as a transparent orthodontic device. It relates to a post-curing method that can improve the quality of the product by post-curing the output printed through 3D printing and a transparent orthodontic device manufactured by this method.

In general, in order to manufacture molded products with a three-dimensional shape, there are two methods: a mock-up manufacturing method performed manually based on drawings, and a numerically controlled automatic manufacturing method using CNC machine tools.

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 sophisticated numerical control, but there are restrictions on the shapes that can be processed due to tool interference. there is.

Accordingly, 3D printers have recently emerged that produce molded products with a three-dimensional shape using a computer that stores 3D design drawing data designed by a product designer or designer through a three-dimensional modeling tool.

Using the 3D printer has the advantage that manufacturing costs and manufacturing times can be significantly reduced, personalized manufacturing is possible, and complex three-dimensional shapes can be easily manufactured.

The above-mentioned 3D printer uses the SLA (Stereo Lithography Apparatus) method, which injects a laser into the photocurable resin to harden the scanned area, and the DLP (Digital Light Processing) method, which irradiates light to the lower part of the reservoir where the photocurable resin is stored and hardens it. LCD method, which uses a UV light source and an LCD panel to laminate resin molded products on the top of the build plate; SLS (Selective Laser Sintering) method, which sinteres using functional polymers or metal powder; and FDM, which molds by extruding molten resin. There are the Fused Deposition Modeling (Fused Deposition Modeling) method, the DMT (Laser-aid Direct Metal Tooling) method, which directly forms metal with a high-power laser beam, and the LOM (Laminated Object Manufacturing) method, which is a mechanical joint forming method.

Among these, in the SLA, DLP, and LCD methods that use photocurable resin, the desired strength and color can be obtained only after manufacturing the molded product, cleaning it, and then going through a separate curing process.

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

If the printed product is cured in natural conditions without using a post-curing machine, the size of the printed product may be deformed or its strength may be lowered.

In addition, when a 3D printer cures the output using only the printer's light source, many problems may occur, such as the size of the output being deformed, its strength being lowered, and stickiness due to unreaction of the photocuring resin after washing.

To prevent this problem, a post-curing machine is used, but when only simple UV curing is performed, there is a problem in that the strength and transparency of the output cannot be improved.

In addition, in order to proceed with the post-curing process, there was the inconvenience of requiring the user to manually remove the cleaning material remaining on the output before using the post-curing machine.

Development of post-processes is necessary to prevent these problems.

KR 10-2019-0054856 A1

The purpose of the present invention is to provide a method of post-curing a 3D printed product using a photocurable composition and a transparent orthodontic device manufactured by this method.

Another object of the present invention is to remove residual resin from a print using a photocurable composition for 3D printing, which can maintain a viscosity suitable for 3D printing and exhibits physical properties that can be used as a dental material, so that the remaining resin is removed even when used in the oral cavity for a long time. The aim is to provide a post-curing process for 3D printed output that is not released and allows the production of output with improved strength, increased transparency, shortened curing time by improving the curing speed through the post-curing process.

Another object of the present invention is that when provided as a transparent orthodontic device, the remaining resin and unreacted monomers of the printed product can be removed, excellent transparency is exhibited, excellent aesthetics, strength is improved, and shape memory properties allow for orthodontic treatment. , To provide a transparent orthodontic device that can provide excellent orthodontic effect and increase convenience of use.

In order to achieve the above object, the present invention provides a post-curing method for 3D printed output using a photocurable composition, which involves using a 3D printer using a photocurable composition containing a photocurable oligomer, monomer, photoinitiator, and stabilizer represented by the following formula (1): A printed product is manufactured, and in order to remove the protruding surface and residual resin remaining on the surface of the printed product, the printed product is placed in a rotating body and washed, and the cleaned printed product is subjected to a first post-cure in an inert gas environment, and the first post-cure is performed. The printed output can be immersed in oil, subjected to second post-curing, and the second post-cured output can be treated with boiling water:

[Formula 1]

[Formula 2]

[Formula 3]

[Formula 4]

[Formula 5]

[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 each independently a repeating unit selected from the group consisting of compounds represented by Formulas 2 to 6,

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

R ₁ and R ₂ are the same or different from each other, and each independently represents hydrogen, deuterium, a substituted or unsubstituted alkyl group with 1 to 30 carbon atoms, a substituted or unsubstituted alkenyl group with 2 to 30 carbon atoms, or a substituted or unsubstituted carbon number. It may be selected from the group consisting of an 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.

A, B and D of the photocurable oligomer represented by Formula 1 are the same or different from each other and are each independently repeating units selected from compounds represented by Formula 2 or 3, and C is represented by Formulas 4 to 6 It may be a repeating unit selected from the group consisting of compounds.

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

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

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

The 3D printer may be a DLP method or an SLA method.

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

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

The boiling water may be hot water of 80°C to 100°C.

The transparent orthodontic device according to another embodiment of the present invention is manufactured by a post-curing method of the 3D printed product, and has excellent orthodontic effect due to shape memory characteristics.

In the present invention, “hydrogen” refers to hydrogen, light hydrogen, deuterium, or tritium, unless otherwise specified.

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

In the present invention, “alkenyl” refers to a monovalent substituent derived from a straight-chain or branched-chain unsaturated hydrocarbon having 2 to 40 carbon atoms and having one or more carbon-carbon double bonds. Examples thereof include vinyl, allyl, isopropenyl, 2-butenyl, etc., but are not limited thereto.

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

In the present invention, “aryl” refers to a monovalent substituent derived from an aromatic hydrocarbon having 6 to 60 carbon atoms, either a single ring or a combination of two or more rings. In addition, forms in which two or more rings are simply pendant or condensed with each other may also be included, specifically naphthyl group, anthracenyl group, phenanthryl group, triphenyl group, pyrenyl group, phenalenyl group, perylenyl group, cryo group. It may be a cenyl group, a fluorenyl group, etc., but is not limited thereto. The fluorenyl group may be substituted, and adjacent groups may combine with each other to form a ring.

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, preferably 1 to 3 carbons, of the ring is replaced with a heteroatom such as N, O, S or Se. In addition, a form in which two or more rings are simply pendant or condensed with each other may be included, and a condensed form with an aryl group may also be included. Examples of such heteroaryls include 6-membered monocyclic rings such as pyridyl, pyrazinyl, pyrimidinyl, pyridazinyl, and triazinyl, phenoxathienyl, indolizinyl, and indolyl ( Polycyclic rings such as indolyl, purinyl, quinolyl, benzothiazole, carbazolyl, and 2-furanyl, N-imidazolyl, 2-isoxazolyl , 2-pyridinyl, 2-pyrimidinyl, etc., but are not limited thereto.

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

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

In the present invention, “alkylthio” refers to the alkyl group described above bonded through a sulfur linkage (-S-).

In the present invention, “aryloxy” is a monovalent substituent represented by RO-, where R refers to aryl having 6 to 60 carbon atoms. Examples of such aryloxy include phenyloxy, naphthyloxy, diphenyloxy, etc., but are not limited thereto.

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

In the present invention, “alkoxy” may be straight chain, branched chain, or ring chain. The number of carbon atoms of alkoxy is not particularly limited, but is preferably 1 to 20 carbon atoms. Specifically, 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. It may be possible, but it is not limited to this.

As used herein, “aralkyl” refers to an aryl-alkyl group where aryl and alkyl are defined above. Preferred aralkyl contains 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.

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

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

In the present invention, “aralkyl amino group” refers to an amine substituted with an aryl-alkyl group having 6 to 30 carbon atoms.

In the present invention, “heteroarylamino group” refers to an amine group substituted with an aryl group or heterocyclic group having 6 to 30 carbon atoms.

In the present invention, “heteroaralkyl group” refers to an aryl-alkyl group substituted with a heterocyclic group.

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.

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

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

The present invention removes residual resin from prints using a photocurable composition for 3D printing that can maintain a viscosity suitable for 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. By improving the curing speed through the post-curing process, the curing time is shortened, and it is possible to produce output with improved strength and increased transparency.

In addition, when provided as a transparent orthodontic device, the remaining resin and unreacted monomers of the printed product can be removed, excellent transparency is provided for aesthetics, strength is improved, and shape memory properties provide excellent orthodontic properties during orthodontic treatment. Effectiveness and convenience of use can be improved.

Figure 1 relates to a procedure for producing a photocurable oligomer according to an embodiment of the present invention.
Figure 2 shows GPC measurement results for a photocurable oligomer according to an embodiment of the present invention.
Figure 3 shows NMR measurement results for a photocurable oligomer according to an embodiment of the present invention.
Figure 4 shows GPC measurement results for a photocurable oligomer according to an embodiment of the present invention.
Figure 5 shows NMR measurement results for a photocurable oligomer according to an embodiment of the present invention.
Figure 6 shows GPC measurement results for a photocurable oligomer according to an embodiment of the present invention.
Figure 7 shows NMR measurement results for a photocurable oligomer according to an embodiment of the present invention.
Figure 8 shows GPC measurement results for a photocurable oligomer according to an embodiment of the present invention.
Figure 9 shows NMR measurement results for a photocurable oligomer according to an embodiment of the present invention.
Figure 10 shows GPC measurement results for a photocurable oligomer according to an embodiment of the present invention.
Figure 11 shows NMR measurement results for a photocurable oligomer according to an embodiment of the present invention.
Figure 12 shows the results of a transparency comparison experiment for a transparent orthodontic device according to an embodiment of the present invention.

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

The DLP method (Digital Light Processing) of the present invention uses the principle of irradiating light to the lower part of the storage tank where the photocurable resin is stored and curing only the part irradiated with light, and the SLA method (Stereo Lithography Apparatus) uses a laser on the photocurable resin. It uses the principle that light is scanned and the scanned area is hardened.

In the case of the DLP method and the SLA method, light is irradiated to a photocurable polymer, and the photocurable polymer resin is cured by light irradiation to produce a printout.

As the output is manufactured by curing the photocurable polymer resin, when the output is manufactured using a 3D printer, resin remains on the exterior of the output and protrusions remain on the surface, so post-processing to keep the surface smooth and clean is required. This addition is needed.

Conventionally, in order to proceed with this post-process, the user directly removed the protruding surface using a tool and simultaneously removed the resin using a solvent.

This process itself is not only cumbersome as the user performs the work himself, but also difficult to achieve perfection.

In addition, the output obtained by curing the photocurable polymer resin contains unreacted polymer resin that is not completely cured during the manufacturing process, which causes problems such as deterioration in physical properties or low transparency. In order to improve the above problems, a post-curing process is essentially performed.

Previously, the post-curing method was limited to the user using a tool to remove the protruding surface of the surface or using a solvent to remove the resin.

In other words, no separate post-curing method was introduced to strengthen the physical characteristics of the output or improve transparency.

The post-curing method of a 3D printed output using a photocurable composition according to an embodiment of the present invention involves printing a printout using a 3D printer using a photocurable composition containing a photocurable oligomer, monomer, photoinitiator, and stabilizer represented by the following formula (1): In order to remove the protruding surface and residual resin remaining on the surface of the output, the output is placed in a rotating body and washed, and the cleaned output is first post-cured in an inert gas environment, and the first post-cured output is produced. may be immersed in oil, subjected to second post-curing, and the second post-cured output may be treated with boiling water.

[Formula 1]

[Formula 2]

[Formula 3]

[Formula 4]

[Formula 5]

[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 each independently repeating units selected from the group consisting of compounds represented by formulas 2 to 6,

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

R ₁ and R ₂ are the same or different from each other, and each independently represents hydrogen, deuterium, a substituted or unsubstituted alkyl group with 1 to 30 carbon atoms, a substituted or unsubstituted alkenyl group with 2 to 30 carbon atoms, or a substituted or unsubstituted carbon number. It may be selected from the group consisting of an 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.

The post-curing method according to an embodiment of the present invention is to first place the printed object in a rotating body and wash it to remove the protruding surface and residual resin remaining on the surface.

Specifically, the output is placed in a cylindrical rotating body and a process of removing remaining resin is performed. More specifically, the cylindrical rotating body is a dehydrator, but it is not limited to the above example, and any device capable of removing the resin remaining in the output by rotating force can be used.

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

A dehydrator is a device that includes a cylindrical dehydration unit. When the dehydration unit rotates in a certain direction, centrifugal force due to the rotation of the dehydration unit is applied to the output contained therein, enabling resin removal.

The resin can be easily removed due to residual polymers on the surface, and even in the case of protruding surfaces, it can be easily removed by friction with the dehydration unit. Through this process, it is possible to easily remove the resin and process the surface.

After the washing step, a post-curing process is performed. Unlike a general post-curing process, the first post-curing process and the second post-curing process can be separated and performed sequentially.

Specifically, the first post-curing in the inert gas environment is a post-curing process for irradiating UV to the 3D printed output, promoting curing to prevent deformation of the output, and improving strength to prevent damage from external force. am.

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

In other words, when the curing process is performed by irradiating UV in an inert gas environment rather than simply irradiating UV to proceed with the curing process, the curing speed can be accelerated by the inert gas and the strength of the output can be improved. Additionally, if the post-curing process is performed in an inert gas environment, transparency is further improved in the case of transparent output.

If the output is manufactured using a DLP or SLA 3D printer and a photocurable polymer resin that does not contain dye is used, a transparent output is obtained.

As described above, when a print is manufactured using a DLP or SLA type 3D printer, unreacted polymer resin remains in the print. The unreacted polymer resin requires additional curing and undergoes a post-curing process. However, during the post-curing process, when the printed product is exposed to the air, the photoinitiator in the printed product comes into contact with oxygen and generates radicals, and the photocuring behavior is suppressed by scavenging the generated radicals.

In other words, it is necessary to prevent the output from coming into contact with oxygen. To this end, when performing the first post-curing process in the present invention, post-curing is performed by irradiating UV in an inert gas environment to block contact with oxygen. do.

When the transparent output proceeds to the post-curing process, it takes on a slightly yellow color, making it difficult to manufacture a completely transparent output.

In particular, in the case of orthodontic devices that are used by inserting them into teeth, such as transparent orthodontic devices, transparency must be excellent so as not to significantly affect the appearance.

When the transparent orthodontic device is manufactured as a personalized print using 3D printing and used as an orthodontic device, if the transparency is not excellent and the slightest yellowish tint appears, there is a possibility that it may be mistaken for poor teeth condition. , may have a negative impact on the user's aesthetics.

To prevent these problems, the 3D printed output itself must be completely transparent.

When output is manufactured using a conventional DLP or SLA printer and the 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 yellow color. , it is not possible to provide a completely transparent correction device.

On the other hand, in the case of the present invention, when UV is irradiated in an inert environment during the post-curing process, the curing speed is improved, the strength is improved, and the transparency of the output is improved by UV irradiation.

In other words, using the post-curing process of the present invention makes it possible to provide a completely transparent transparent correction device.

This means that when a post-curing process is used using UV in an inert gas environment, the production speed of the final product is improved as the curing speed is improved, and the strength is excellent so that deformation due to external force does not easily occur.

In addition, as described later, when using a specific photocurable oligomer, the mechanical properties are excellent, which not only improves orthodontic power when used as an orthodontic device, but also improves user convenience when used as a patient-tailored orthodontic device. It can be raised.

The inert gas is selected from the group consisting of nitrogen, argon, helium, krypton, neon, and mixtures thereof, and is preferably nitrogen. However, the inert gas is not limited to the above example, and the inert gas is a gas that can block contact with oxygen of the output. All can be used without restrictions.

The present invention is characterized in that a second post-cure process is performed after the first post-cure process.

Specifically, in the second post-curing process, the output that has undergone the first post-curing process is completely immersed in oil and then post-cured by irradiating UV.

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

As described later, when a print is manufactured using the photocurable composition of the present invention and the post-curing process is performed according to the above steps, when heat of 60°C or higher is supplied, the print is restored to its initial printed shape. It is characterized by exhibiting shape memory characteristics.

However, this shape memory characteristic is expressed by the post-curing process of the present invention, and only the first post-curing process is performed without proceeding with the second post-curing process, or the second post-curing process is performed first and the first post-curing process is performed first. Even if the order of the post-curing process is changed, the characteristics of the output are not expressed.

The second post-curing process of the present invention involves completely immersing the output that has undergone the first post-curing process in oil and performing the post-curing process by irradiating UV.

When the output is immersed in oil and irradiated with UV light as described above, high curing density and sufficient heat energy can be supplied to the output through the post-curing process.

In other words, by immersing in oil, oxygen is blocked, and at the same time, the oil absorbs heat energy from UV and transfers it evenly to the output. Due to the above characteristics, a uniform temperature is delivered to the printed product in the second post-curing process, and the printed product can exhibit fluidity characteristics.

The order of the first post-curing process and the second post-curing process is important, and if the order is changed, there is a problem that oils cause bubbles to form on the surface of the printed product, causing curing defects. In order to prevent the above problems, it is preferable to proceed in the order of the post-curing process of the present invention.

The oils are selected from the group consisting of glycerol, edible oil, castor oil, non-reactive silicone oil, and mixtures thereof, and are preferably glycerol, but are not limited to the above example and are non-reactive with the output and oxygen. Any oil that blocks contact, absorbs heat, and transfers it evenly to the printed object can be used without restrictions.

After the post-curing process, a boiling water treatment process is performed. The boiling water treatment is treatment with hot water at 80 to 100°C, and unreacted monomers remaining in the output can be removed through hot water treatment.

A transparent orthodontic device according to another embodiment of the present invention is manufactured by a post-curing method of the 3D printed product.

The transparent orthodontic device is used to correct the desired tooth position while being fitted on the patient's teeth.

The transparent orthodontic device of the present invention is manufactured by the post-curing method described above, has excellent transparency, excellent physical properties, and can exhibit shape memory characteristics that restore the original printed shape by heat.

The transparent orthodontic device is printed with a 3D printer using a photocurable composition, which will be described later, and manufactured through a post-curing process.

The photocurable composition for a 3D printer according to an embodiment of the present invention may include a photocurable oligomer, monomer, photoinitiator, and stabilizer represented by the following Chemical Formula 1:

[Formula 1]

[Formula 2]

[Formula 3]

[Formula 4]

[Formula 5]

[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 each independently a repeating unit selected from the group consisting of compounds represented by Formulas 2 to 6,

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

R ₁ and R ₂ are the same or different from each other, and each independently represents hydrogen, deuterium, a substituted or unsubstituted alkyl group with 1 to 30 carbon atoms, a substituted or unsubstituted alkenyl group with 2 to 30 carbon atoms, or a substituted or unsubstituted carbon number. It may be selected from the group consisting of an 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.

The photocurable composition of the present invention is a material that is cured by light irradiation and refers to a polymer that is crosslinked and polymerized into a polymer network structure. In this specification, the description focuses on UV light, but it is not limited to UV light and can be applied to other lights as well.

The photocurable oligomer includes a urethane acrylate structure as a main chain, a photocurable functional group is bonded to the urethane structure, and the compound is characterized by including soft functional groups and hard functional groups.

The printed product exhibits flexible properties due to the soft functional groups included in the photocurable composition, and can also exhibit heat resistance due to the hard functional groups.

In other words, by combining a photocurable functional group with a photocurable oligomer and using a soft functional group and a hard functional group, not only can a flexible effect be achieved by using a carbon skeleton that has soft properties at room temperature, but also hard properties can be achieved at room temperature. By using the carbon skeleton it has, it can exhibit heat-resistant properties.

As the photocurable oligomer contains a carbon skeleton with hard properties, it has excellent physical properties such as thermal properties, strength, elastic modulus, and tensile elongation, and can produce 3D printing outputs that can be restored to their original shape by heat. there is.

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

Generally, a composition for a 3D printer includes, as described below, a photocurable oligomer for 3D printing; monomer; photoinitiator; and a stabilizer. Oligomers, monomers, photoinitiators, and stabilizers included in the composition all affect the physical properties of the output, but oligomers have the greatest influence. Accordingly, in general, in order to increase the physical properties of 3D printed products, only carbon skeletons with hard properties are included, which can increase the physical properties of the printed product, but on the contrary, when the shape is deformed by use, the shape is restored. Since this is not possible, there is a problem in that it cannot be used multiple times.

The composition for a 3D printer in the present invention contains a carbon skeleton with hard properties and a carbon skeleton with soft properties, so it not only has excellent physical properties such as thermal properties, strength, elastic modulus, and tensile elongation, but also has a soft functional group. The flexible nature of can be used together, so if the shape is changed by an external force while heat is provided, the deformed shape can be fixed, and then when heat is provided again, it can be restored to the original shape.

A, B, and D may be the same or different from each other, and may each independently be a repeating unit selected from a compound represented by Formula 2 or 3.

The C may be a repeating unit selected from the group consisting of compounds represented by Formulas 4 to 6.

Specifically, the photocurable oligomer represented by Formula 1 may be produced by a method of synthesizing urethane acrylate series. Basically, it proceeds through a stepwise polymerization reaction of diol and diisocyanate, and to prevent gelation of the material as the molecular weight increases during the polymerization process, an acrylic monomer without a reaction site was used as a suspension. The monomers used in the synthesis of the oligomer of the present invention as usable acrylic monomers may be Isobornyl acrylate, Cyclic Trimethylolpropane Formal Acrylate, Lauryl acrylate, Lauryl methacrylate, 3,5,3-trimethelhexyl acrylate, Tetrahydrofurfuryl acrylate, Tetrahydrofurfuryl methacrylate, Benzyl methacrylate, etc. .

More specifically, diol was pre-added to the monomer base used as a monomer to stabilize it, and then diisocyanate was added. As the urethane reaction progressed, reaction heat was generated, the urethane chain became longer, and the molecular weight increased.

As molecular weight increases, the viscosity of the material may also increase. When the above molecular weight increase occurs rapidly, the temperature rises rapidly, which causes the urethane reaction to also proceed more rapidly. As a result, the oligomer gels before reaching a sufficient molecular weight, making it impossible to use as a material. The sun sets. Therefore, in the present invention, in order to prevent this reaction, as a solvent for adding diol, Isobornyl acrylate, Cyclic Trimethylolpropane Formal Acrylate, Lauryl acrylate, Lauryl methacrylate, 3,5,3-trimethelhexyl acrylate, Tetrahydrofurfuryl acrylate, Tetrahydrofurfuryl methacrylate, Benzyl A methacrylate selected from the group consisting of methacrylate and a mixture thereof was used. The solvent does not participate in the reaction and is used to control the reaction rate of the material and prevent a rapid increase in viscosity due to an increase in molecular weight. In addition, monomers for synthesizing the oligomer of the present invention must not have functional groups capable of urethane reaction, such as hydroxyl groups or urethane groups. Through the above conditions, the present invention will enable the production of oligomers with excellent mass production and process stability.

In addition, the equivalence ratio between diol and diisocyanate was set to a state where the equivalent weight of diisocyanate was higher than that of diol, so that the oligomer terminal was induced to exist as an isocyanate group. During the reaction process, a reaction catalyst including a Zn-based catalyst can be used. The catalyst may or may not be included. The catalyst is included to make the reaction proceed more quickly, and the reaction can proceed even if it is not necessarily included. However, even if it is included, the reaction can proceed with a very small amount.

After the temperature increase was stopped due to the completion of the urethane reaction, 2-hydroxy acrylate and 2-hydroxy methacrylate were added through a drop method to end cap the ends of the oligomer.

The diols used for the preparation of the oligomers are as follows:

Additionally, the diisocyanate for reaction with the diol is as follows:

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

The compound represented by Formula 1 prepared by the above production method may be selected from the group consisting of the following compounds:

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.

When manufacturing a photocurable composition for 3D printing, which will be described later, using an oligomer having a number average molecular weight and a weight average molecular weight within the above range, and manufacturing a transparent orthodontic device using the same, the transparent orthodontic device is customized to the patient's oral structure. You can print out a correction device and use it to increase correction power. In addition, when the transparent orthodontic device is immersed in water at 50 to 100°C and then deformed, its shape changes to a deformed shape. However, when it is used while being placed on a tooth, the orthodontic device whose shape has changed due to body temperature gradually changes. It can be restored to its original shape and show corrective power.

That is, the conventional transparent orthodontic device is made of a transparent plastic material and can transmit sufficient force for correction of teeth. However, as described above, the transparent orthodontic device is printed in accordance with the step-by-step movement state of the teeth. Because it is different from the current patient's tooth structure, it cannot be worn easily even when inserted into the teeth, and can cause great pain even after wearing it.

On the other hand, when using the photocurable composition for 3D printing of the present invention, before use, the printed transparent orthodontic device is immersed in water at 50 to 100°C and placed on the patient's teeth to change its shape to suit the current temperature. As a result, the shape of the orthodontic device is gradually changed, allowing the patient to exert great orthodontic power without feeling much pain.

Additionally, using these characteristics, it can be used in a variety of dental products such as orthodontic retainers and arch expansion devices.

As described above, when various oligomers are selected according to the physical properties such as tensile strength, flexural strength, flexural elasticity, and flexural strength required for each product and used to manufacture a photocurable composition for 3D printing, excellent dental products can be manufactured. makes possible.

The 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 manufacturing a photocurable composition using an oligomer having a viscosity in the above range, it can be provided at a viscosity suitable for use in a 3D printer.

A photocurable composition for a 3D printer according to an embodiment of the present invention includes the photocurable oligomer for D printing; monomer; photoinitiator; and a stabilizer.

The monomer is a reactive monomer, and may specifically be an acrylate-based monomer.

More specifically, the acrylate-based monomer may be selected from the group consisting of a compound represented by Formula 7 below, a compound represented by Formula 8 below, and a mixture thereof:

[Formula 7]

[Formula 8]

The photoinitiator may be BP, TPO, DCP, BPO, DPPO, etc., but is preferably DPPO (2-hydroxy-2-methylpropiophenone). However, it is not limited to the above example, and a photocurable composition can be prepared. All photoinitiators available can be used without restrictions.

The 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 can be used to prepare a photocurable composition. Any stabilizer that can be used can be used without restrictions.

In addition to the photoinitiator and stabilizer, other additives may be additionally included.

The 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.

The photocurable composition according to an embodiment of the present invention may include 1 part by weight of a photoinitiator based on 100 parts by weight of UV resin. The UV resin is a photocurable oligomer of the present invention; and monomers, and more specifically, a compound represented by Formula 1 below, a compound represented by Formula 7 below, and a compound represented by Formula 8 below at a weight ratio of 1:1:1 to 2:1:1. can do.

Manufacturing Example 1

Manufacturing of photocurable oligomers for 3D printing

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

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

The oligomer finally produced by reacting the intermediate compounds is as follows:

The procedure for the manufacturing method of Preparation Example 1 is shown in FIG. 1.

The GPC analysis results for the oligomer of Preparation Example 1 are shown in Figure 2. Additionally, the NMR analysis results are shown in Figure 3.

Production example 2

Oligomers were prepared in the same manner as in Preparation Example 1, but the monomers used were different during the reaction. The oligomers prepared were as follows:

The GPC analysis results for the oligomer of Preparation Example 2 are shown in Figure 4. Additionally, the NMR analysis results are shown in Figure 5.

Production example 3

Oligomers were prepared in the same manner as in Preparation Example 1, but the monomers used were different during the reaction. The oligomers prepared were as follows:

The GPC analysis results for the oligomer of Preparation Example 2 are shown in Figure 6. Additionally, the NMR analysis results are shown in Figure 7.

Production example 4

Oligomers were prepared in the same manner as in Preparation Example 1, but the monomers used were different during the reaction. The oligomers prepared were as follows:

The GPC analysis results for the oligomer of Preparation Example 2 are shown in Figure 8. Additionally, the NMR analysis results are shown in Figure 9.

Production example 5

Oligomers were prepared in the same manner as in Preparation Example 1, but the monomers used were different during the reaction. The oligomers prepared were as follows:

The GPC analysis results for the oligomer of Preparation Example 2 are shown in Figure 10. Additionally, the NMR analysis results are shown in Figure 11.

The results of the analysis of the oligomers of Preparation Examples 1 to 5 are summarized in Table 1 below:

Manufacturing Example 1 Production example 2 Production example 3 Production example 4 Production example 5 GPC Mn 4179 4102 1663 4767 2691 Mw 6944 6763 7855 7591 3703 PDI 1.68 1.65 1.68 1.59 1.38 NMR A
(6.44) O O O O O B
(5.89) O O O O O C
(5.61) O
(39.0) O
(39.3) O
(9.3) O
(22.1) X D
(4.91) O
(87.9) O
(89.6) O
(77.6) O
(86.4) O
(61.0) E
(6.48) X X O
(16.1) X O
(22.3) F(6.49) X X O X O G(3.41) O O O O O

Experimental Example 1

Check physical properties

The viscosity of the oligomers of Preparation Examples 1 to 5 was measured, and the mechanical properties were measured after 3D printing.

In order to measure mechanical properties, the oligomers of Preparation Examples 1 to 5, the compound represented by Formula 7 below, and the compound represented by Formula 8 below were mixed at a weight ratio of 1:1:1, and 100 parts by weight of the mixture was added. 1 part by weight of DPPO was mixed to prepare a polymer composition (Examples 1 to 5), which was placed in a 3D printer and prepared as a specimen:

[Formula 7]

[Formula 8]

Specifically, flexural strength was conducted according to ISO 20795-2 and ISO 10477 standards, and tensile strength was conducted according to ASTM D638.

Example 1 Example 2 Example 3 Example 4 Example 5 Batch Size 50L 50L 50L 50L 50L blending and
3D
printing output
After mechanical properties Flexural strength
(20795-2 specimen, MPa) 171 162 155 163 150 Flexural elasticity
(20795-2 specimen, MPa) 3939 3807 3800 3655 3594 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) 2880 2950 2220 2380 2380

It was confirmed that the specimens prepared using the oligomers of Preparation Examples 1 to 5 showed excellent mechanical properties, and that they could be printed using a 3D printer through appropriate viscosity.

Experimental Example 2

Manufacturing of transparent orthodontic appliances

The photocurable compositions of Examples 1 to 5 prepared in Experimental Example 1 were put into each DLP 3D printer and printed out using a transparent calibration device. The manufactured transparent correction device underwent a post-curing process. Specifically, the same washing process using a dehydrator was performed to remove the remaining resin and the protruding surface.

Afterwards, the calibration device was placed in the box, oxygen was completely blocked under a nitrogen atmosphere, and then UV irradiated for 25 minutes. The correction device was immersed in a bath containing glycerol, and a secondary post-curing process was performed by UV irradiation for 25 minutes. The secondary post-cured correction device was treated with boiling water at 80 to 100°C to complete the post-cure process.

Comparative Example 1

Using the photocurable composition of Example 1, a transparent orthodontic device was printed on a DLP-type 3D printer, the transparent orthodontic device was washed using a dehydrator, and the cleaned transparent orthodontic device was stored at room temperature (20 degrees Celsius) for 50 minutes. to 25°C) and was prepared in the same manner as in Experimental Example 2.

Comparative Example 2

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

Comparative Example 3

A photocurable composition was prepared in the same manner as in Example 1, except that a compound represented by the following formula (9) was used as the photocurable oligomer, 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 formula (1), and includes both a compound where A is selected by formula (10) and a compound where A is selected by formula (11), and a compound selected by formula (10) and a compound selected by formula (11) Included in a weight ratio of 1:1.5.

[Formula 9]

[Formula 10]

[Formula 11]

here,

n is an integer from 1 to 1,000,

* refers to the part that is combined,

R ₁ to R ₆ are methyl groups.

Check transparency

The transparent orthodontic appliances manufactured in Example 1, Comparative Example 1, and Comparative Example 2 were immersed in a water tank containing water at 37°C for 24 hours to create conditions similar to the use environment in the oral cavity, and then the transparent orthodontic devices were The degree was confirmed visually.

The results are as shown in Figure 12. 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.

As shown in Figure 12, it can be seen that (b) appears remarkably transparent.

Specifically, photocuring behavior in an atmosphere exposed to air is inhibited by radical scavenging of oxygen. As shown in Figure 12, it can be seen that the transparency of the correction device cured in an atmospheric environment decreases after being immersed for 24 hours. As a result, the surface forms a relatively low crosslinking density and reacts sensitively to moisture, resulting in a problem of decreased transparency.

In addition, in the case of Comparative Example 2, two post-curing processes were performed without immersion in glycerol, which means that as glycerol is used, glycerol absorbs heat energy by UV irradiation and transfers it evenly into the transparent orthodontic device. Accordingly, high curing density could be achieved and transparency was improved.

Whether surface bubbles occur

The transparent orthodontic device of Example 1 was first cured in a nitrogen atmosphere and then immersed in glycerol to undergo secondary curing, confirming that no bubbles were generated.

Stress relaxation and creep evaluation results

In order to evaluate stress relaxation and creep, 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.

PETG was used as a control, and PETG was similarly processed to 5 mm in width, 40 mm in length, and 0.4 mm in thickness to prepare a specimen.

Comparative Example 3 differs from Example 1 in the photocurable composition, was printed as a specimen with a width of 5 mm, a length of 40 mm, and a thickness of 0.4 mm, and the post-curing process was performed in the same manner as in Experiment Example 2 of the present invention.

Regarding stress relaxation and creep behavior, the specimens of the present invention initially showed rapid stress relaxation when loaded at 37°C for 60 minutes. A residual static force of 1.0N was observed after 13 repeated loadings. 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 loads was 11.39N. In the case of Comparative Example 2, stress relaxation 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 loads was 0.5N, confirming that sufficient force required for tooth movement was not exerted.

In general, in clinical practice for orthodontic treatment, it is known that a force of 0.098 to 1.18 N is required to move teeth. Excessive orthodontic force may have side effects such as tooth root absorption in the teeth and surrounding tissues, and applying orthodontic force beyond the patient's pain threshold may cause discomfort. The static force exhibited by the specimen of the present invention at 37°C would correspond to the appropriate orthodontic force required for an orthodontic device.

Detection of unreacted organic matter

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, using a gas chromatography tandem mass spectrometer, based on ISO 20798-2. An experiment was conducted.

In all of the transparent orthodontic devices of Examples 1 to 5 manufactured in Experimental Example 2, unreacted monomers were removed through the post-curing process of the present invention, and MMA (methyl methacrylate) elution was not found.

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 are also possible. falls within the scope of rights.

Claims (10)

Prints are manufactured with a 3D printer using a photocurable composition containing a photocurable oligomer, monomer, photoinitiator, and stabilizer represented by the following formula (1),
In order to remove the protruding surfaces and residual resin remaining on the surface of the printed product, it is placed in a rotating body and washed.
The cleaned output is first post-cured in an inert gas environment,
The first post-cured output is immersed in oil and subjected to a second post-cure,
Processing the second post-cured output with boiling water
Post-curing method of 3D printed output using a photocurable composition:
[Formula 1]

[Formula 2]

[Formula 3]

[Formula 4]

[Formula 5]

[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 each independently repeating units selected from the group consisting of compounds represented by formulas 2 to 6,
a, b, c and d are the same or different from each other and are each independently an integer from 1 to 30,
R ₁ and R ₂ are the same or different from each other, and each independently represents 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, or a substituted or unsubstituted carbon number. It may be selected from the group consisting of an alkynyl group of 2 to 30 carbon atoms, a substituted or unsubstituted aryl group of 6 to 30 carbon atoms, and a substituted or unsubstituted heteroaryl group of 1 to 30 carbon atoms. According to paragraph 1,
A, B, and D of the photocurable oligomer represented by Formula 1 are the same or different from each other, and each independently is a repeating unit selected from a compound represented by Formula 2 or 3,
Wherein C is a repeating unit selected from the group consisting of compounds represented by formulas 4 to 6.
Post-curing method of 3D printed output using a photocurable composition. According to paragraph 1,
The photocurable oligomer has a number average molecular weight (Mn) of 1,500 to 6,000.
Post-curing method of 3D printed output using a photocurable composition. According to paragraph 1,
The photocurable oligomer has a weight average molecular weight (Mw) of 2,500 to 9,000.
Post-curing method of 3D printed output using a photocurable composition. According to paragraph 1,
The photocurable oligomer has a viscosity of 2,000 mPa·s to 3,500 mPa·s.
Post-curing method of 3D printed output using a photocurable composition. According to paragraph 1,
The 3D printer is a DLP method or SLA method.
Post-curing method of 3D printed output using a photocurable composition. According to paragraph 1,
The inert gas is selected from the group consisting of nitrogen, argon, helium, krypton, neon, and mixtures thereof.
Post-curing method of 3D printed output using a photocurable composition. According to paragraph 1,
The oils are selected from the group consisting of glycerol, edible oil, castor oil, non-reactive silicone oil, and mixtures thereof.
Post-curing method of 3D printed output using a photocurable composition. According to paragraph 1,
The boiling water is hot water of 80°C to 100°C.
Post-curing method of 3D printed output using a photocurable composition. Manufactured by the post-curing method of the 3D printed output according to any one of claims 1 to 6,
Excellent orthodontic effect due to shape memory properties
Transparent teeth straightening device.