Photocurable composition for additive manufacturing of articles having excellent mechanical strength and thermal stability

Abstract

Disclosed are: a photocurable 3D printing composition, which is applied to a 3D printer to output a three-dimensional molded product; and a method for manufacturing a molded product with improved thermal stability by using same. According to an aspect of the present invention, provided is a photocurable 3D printing composition for additive manufacturing, which has improved heat resistance performance by comprising at least one acrylate monomer, a photo-initiator, and an inorganic filler.

Description

Photocurable composition for laminated manufacturing of articles with excellent mechanical strength and thermal stability

[0001] The present invention relates to a photocurable composition for manufacturing a three-dimensional article by means of an additive manufacturing technique, and to a composition for a three-dimensional printer capable of manufacturing an article having excellent mechanical strength and thermal stability.

[0002] The content described in this section merely provides background information for the present embodiment and does not constitute prior art.

[0003] Additive manufacturing, or 3D printing, can quickly and precisely produce three-dimensional structures of various structures, and the range of possible applications is continuously expanding as the technology rapidly develops.

[0004] Accordingly, the applicable materials for 3D printing are expanding from synthetic resins to metals, wood, rubber, and bio, and the application fields are also expanding to architecture, engineering, civil engineering, and medicine.

[0005] In particular, 3D printing technology enables prototype production without molds or castings, reducing the cost and time required for prototyping. It also enables small-batch, multi-variety production and the creation of customized and complex shapes. Furthermore, the simplified manufacturing process for finished products offers significant advantages, reducing labor and assembly costs. Consequently, the automotive industry, which frequently requires prototype production, is rapidly adopting 3D printing technology.

[0006] Meanwhile, in addition to automobile prototypes, 3D printing is also actively being used to produce automotive parts, interior materials, molds, jigs, and fixtures. Compared to conventional CNC machining, 3D printing technology significantly shortens the manufacturing time for molds, jigs, and fixtures. It also enables the production of molds, jigs, and fixtures with a high level of dimensional accuracy and precision, thereby improving productivity and worker convenience in manufacturing settings.

[0007] Jigs and fixtures require engineering-grade mechanical strength and superior heat resistance. A widely used 3D printing method is Fused Deposition Modeling (FDM), which involves melting a plastic filament with heat, extruding it, and then layering it to form a 3D object. However, FDM creates each layer one by one and utilizes a nozzle, making it slower and offering lower resolution than other printing methods.

[0008] Unlike the FDM method, the Stereo Lithography Apparatus (SLA) method and the Digital Light Processing (DLP) method scan a tank containing a liquid photocurable material with a laser beam to solidify only the necessary parts, which has the advantage of being able to produce outputs with precision and high output speed. In order for 3D printing to be possible using the SLA method and DLP method, the photocurable printing composition must be a liquid material with low viscosity and must be able to harden quickly.

[0009] Meanwhile, products with a certain level of mechanical strength and heat resistance, such as jigs, fixtures, or molds, are manufactured through 3D printing using compositions containing inorganic fillers. However, as the inorganic filler content increases, the viscosity of the 3D printing composition may increase. Therefore, the filler content must be adjusted to ensure sufficient UV light penetration into the polymer matrix for sufficient layer solidification.

[0010] Therefore, there is a need for a composition for 3D printing that can perform 3D printing at a faster speed and with higher accuracy than the conventional FDM method, while also securing sufficient mechanical strength and heat resistance that can be applied to jigs, fixtures, molds, etc.

[0011] One embodiment of the present invention aims to provide a photocurable composition for additive manufacturing that can manufacture an article with improved mechanical properties and thermal stability from an acrylate-based photocurable composition used in 3D printing using the DLP or SLA method.

[0012] In addition, the present invention aims to provide a photocurable composition for a mold, jig, or fixture that can exhibit excellent heat resistance and high strength by applying at least one acrylate monomer, an inorganic filler, and a photoinitiator as components of the photocurable composition.

[0013] According to one aspect of the present invention, a photocurable printing composition for laminated manufacturing is provided, which comprises at least one acrylate monomer, a photoinitiator, and an inorganic filler, and has improved heat resistance.

[0014] According to one aspect of the present invention, the at least one acrylate monomer includes a first acrylate monomer and a second acrylate monomer, and the first acrylate monomer is characterized in that it is a bifunctional acrylate monomer.

[0015] According to one aspect of the present invention, the inorganic filler is characterized by being any one selected from SiO2, CaCO3, Al2O3, TiO2, ZnO2, or carbon black or a combination thereof.

[0016] According to one aspect of the present invention, the at least one acrylate monomer and the inorganic filler are included in a weight ratio of 7:3 to 5:5.

[0017] According to one aspect of the present invention, the first acrylate monomer has a weight average molecular weight of 200 to 400 g / mol and a glass transition temperature (T g ) is characterized by a temperature of at least 80℃ or higher.

[0018] According to one aspect of the present invention, the photoinitiator is characterized by being any one of diphenyl-(2,4,6-trimethylbenzoyl)-phosphine oxide, ethyl-(2,4,6-trimethylbenzoyl)phenyl-phosphinate, and phenyl-bis-(2,4,6-trimethylbenzoyl)-phosphine oxide.

[0019] According to one aspect of the present invention, the inorganic filler is SiO2, nano-sized silica particles having an average particle diameter of 10-15 nm, and is characterized by being surface-treated with methacrylate.

[0020] According to one aspect of the present invention, a method for manufacturing a three-dimensional molded article is provided, comprising the steps of manufacturing the photocurable 3D printing composition described above, curing the photocurable 3D printing composition layer by layer with an ultraviolet laser to output a molded article in a form in which the cured layers are laminated, and post-processing the output three-dimensional molded article.

[0021] According to one aspect of the present invention, the step of post-processing the output three-dimensional molded product is characterized by including a post-baking step.

[0022] According to one aspect of the present invention, the three-dimensional molded product is characterized in that it has a Shore hardness of at least 90D or more and a tensile modulus of 25 GPa or more measured according to ASTM D638.

[0023] According to one aspect of the present invention, there is provided an article manufactured by 3D printing using the photocurable composition described above, wherein the article has a Shore hardness of at least 90D or more and an elastic modulus of at least 25 GPa as measured according to ASTM D638.

[0024] According to one aspect of the present invention, the article is characterized in that it has a heat distortion temperature (HDT) of at least 170°C or more when tested according to ASTM D648 (0.46 MPa), and an impact strength (Notched Izod impact strength) of at least 25 J / m or more when tested according to ASTM D256.

[0025] As described above, according to one aspect of the present invention, there is provided a composition that can be applied to 3D printing using the DLP or SLA method by mixing at least one acrylate monomer and an inorganic filler, thereby having the advantage of being able to manufacture articles requiring high heat resistance and high rigidity, such as jigs, fixtures, or molds, with high accuracy.

[0026] FIG. 1 is a flowchart illustrating a method for manufacturing a molded article using a photocurable 3D printing composition according to one embodiment of the present invention.

[0027] The present invention is susceptible to various modifications and embodiments. Specific embodiments are illustrated and described in detail in the drawings. However, this is not intended to limit the present invention to specific embodiments, but rather to encompass all modifications, equivalents, and alternatives falling within the spirit and technical scope of the present invention. Throughout the description of each drawing, similar reference numerals have been used to designate similar components.

[0028] Terms such as first, second, A, and B may be used to describe various components, but these components should not be limited by these terms. These terms are used solely to distinguish one component from another. For example, without departing from the scope of the present invention, a first component may be referred to as a second component, and similarly, a second component may also be referred to as a first component. The term "and / or" includes a combination of multiple related items described herein or any of multiple related items described herein.

[0029] When a component is referred to as being "connected" or "connected" to another component, it should be understood that it may be directly connected or connected to that other component, but that there may be other components intervening. Conversely, when a component is referred to as being "directly connected" or "connected" to another component, it should be understood that there are no other components intervening.

[0030] The terminology used in this application is solely for the purpose of describing specific embodiments and is not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly dictates otherwise. It should be understood that terms such as "comprise" or "have" in this application do not preclude the presence or possibility of addition of features, numbers, steps, operations, components, parts, or combinations thereof described in the specification.

[0031] Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs.

[0032] Terms defined in commonly used dictionaries should be interpreted to have a meaning consistent with their meaning in the context of the relevant technology, and will not be interpreted in an idealized or overly formal sense unless expressly defined in this application.

[0033] In addition, each configuration, process, procedure or method included in each embodiment of the present invention may be shared within a scope that is not technically inconsistent with each other.

[0034] Jigs and fixtures are essential components in the manufacturing process to ensure the reproducible and accurate production of each part. Jigs support and secure the workpiece in place, while also guiding and controlling the machining tools. Fixtures also securely hold the machined part in place.

[0035] Because such jigs and fixtures must closely match the geometry of the parts they are designed to work with and require frequent design changes, 3D printing is highly advantageous for machining them, as it can easily produce molded parts in a short period of time while maintaining a high level of accuracy and precision.

[0036] Jigs and fixtures have generally been made of metal, but with the introduction of additive manufacturing, or 3D printing technology, the materials used for jigs and fixtures are diversifying to include high-performance resins, rubber, etc.

[0037] In particular, curable compositions usable as jigs and fixtures must have high mechanical strength and excellent heat resistance to ensure optimal performance even at high temperatures.

[0038] 3D printing using DLP or SLA methods can be used to manufacture items in a shorter timeframe and with greater accuracy than traditional thermosetting composite materials. Acrylate polymers are typically used for this purpose. However, acrylate polymers have relatively low mechanical strength, so inorganic fillers can be used to improve mechanical strength.

[0039] The present invention provides a photocurable 3D printing composition capable of manufacturing articles with superior mechanical strength and thermal stability, including an inorganic filler. More specifically, the photocurable composition of the present invention comprises an acrylate monomer and an inorganic filler and can be applied to SLA or DLP 3D printing. Furthermore, the molded article ultimately output therefrom possesses excellent mechanical properties and thermal stability suitable for use as the aforementioned jigs and fixtures.

[0040] A photocurable 3D printing composition according to one embodiment of the present invention comprises at least one acrylate monomer, an inorganic filler, and a photoinitiator.

[0041] The acrylate monomer according to the present invention serves as a base resin for a photocurable composition, and contains a reactive site with an acrylate functional group that reacts with UV light, thereby reacting with UV light. The acrylate monomer may be selected in consideration of the viscosity of the composition, shrinkage during the reaction, and mechanical strength after the reaction.

[0042] The acrylate monomer may be any one or more of monofunctional, difunctional, and polyfunctional monomers, and there is no particular limitation on the monomers used in the art. However, the acrylate monomer may be any one or more selected from acrylate monomers such as aromatic acrylate, acrylate acid, methacrylate, epoxy acrylate, urethane acrylate, polyester acrylate, and mixtures thereof.

[0043] At least one acrylate monomer included in the photocurable 3D printing composition according to one embodiment of the present invention may include a first acrylate monomer and a second acrylate monomer.

[0044] The first acrylate monomer may be a bifunctional acrylate monomer.

[0045] More specifically, the difunctional acrylate monomers include 1,12-dodecane diol diacrylate, 1,3-butylene glycol diacrylate, 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, cyclohexane dimethanol diacrylate, diethylene glycol diacrylate, ethoxylated (4) bisphenol A diacrylate, and propoxylated (2) neopentyl glycol diacrylate. Any one of the monomers may be used, such as tricyclodecane dimethanol diacrylate, tripropylene glycol diacrylate, ethoxy(4) bisphenol A dimethacrylate, hydroxyl pivalic acid neopentyl glycol diacrylate, or similar monomers.

[0046] The first acrylate monomer may have a weight average molecular weight (Mw) of 200 to 800 g / mol, more preferably 200 to 400 g / mol. In addition, the first acrylate monomer may have a glass transition temperature (T) of at least 80°C or higher. g ) is preferred, and has a glass transition temperature (T g) is more preferably an acrylate monomer having a glass transition temperature (T ) in the range of 100 to 250°C. g ) Acrylate monomer having a temperature of 80℃ or higher can improve the mechanical strength and thermal stability of the molded product.

[0047] The second acrylate monomer may be any one of a monofunctional acrylate monomer, a difunctional acrylate monomer, and a polyfunctional acrylate monomer.

[0048] Monofunctional acrylate monomers can act as diluents to increase the strength of the composition and reduce its viscosity.

[0049] Any one of cyclic trimethylolpropane formal acrylate, ethylene glycol methyl ether methacrylate, ethoxylated nonyl phenol acrylate, isobornyl acrylate, isodecyl acrylate, isooctyl acrylate, lauryl acrylate, and 4-acryolyl morpholine may be used as the monofunctional acrylate monomer.

[0050] As for the bifunctional acrylate monomer, any one of the bifunctional acrylates can be used, similar to the first acrylate monomer, and as the multifunctional acrylate monomer, polyester acrylate can be used.

[0051] In the present invention, at least one acrylate monomer may be included in an amount of 70 to 50 parts by weight relative to 30 to 50 parts by weight of the inorganic filler.

[0052] When at least one acrylate monomer comprises a first acrylate monomer and a second acrylate monomer, 70 to 50 parts by weight of the acrylate monomer may comprise 30 to 45 parts by weight of the first acrylate monomer and 5 to 40 parts by weight of the second acrylate monomer.

[0053] A photocurable 3D composition according to one embodiment of the present invention can improve mechanical properties such as hardness and wear resistance of a molded body formed from the composition by including an inorganic filler.

[0054] The inorganic filler may include inorganic particles of submicron size. For example, the inorganic particles may be selected from the group consisting of SiO2, CaCO3, Al2O3, TiO2, ZnO2, carbon black, or a combination thereof, with silica (SiO2) particles being more preferred.

[0055] The average diameter of the inorganic filler particles may be less than 1 micron, preferably less than 500 nm, and it is more preferable to use nanoparticles having an average diameter of less than 100 nm, more preferably in the range of 10 to 30 nm.

[0056] For example, when using silica particles as an inorganic filler, the silica particles may be a colloidal solution in which nano-sized silica particles are dispersed. The silica particles dispersed in the colloidal solution may be nanoparticles having an average diameter in the range of 10 to 15 nm.

[0057] In order to mix nano silica particles in a colloidal solution state into a photocurable 3D composition, it is preferable to remove the solvent of the colloidal solution and then redisperse the particles in an acrylate monomer to be included in the composition.

[0058] Furthermore, silica nanoparticles are hydrophilic and therefore have poor compatibility with hydrophobic acrylate monomers, making it difficult to maintain a uniform dispersion by mixing them with acrylate monomers in a composition. Therefore, nano-silica particles can be improved to have compatibility with acrylates by including a separate binder component or by surface-treating the silica particles.

[0059] For example, in the present invention, the surface of nano silica particles may be modified using a (meth)acrylate compound.

[0060] The photocurable 3D composition of the present invention may include at least one acrylate monomer and an inorganic filler in a weight ratio of 7:3 to 5:5.

[0061] If the inorganic filler content is less than 30% of the total weight of the acrylate monomer and inorganic filler, the mechanical strength of the composition is reduced, making it difficult to secure the level of strength required for molded objects such as jigs or fixtures. Furthermore, if the content of the inorganic filler exceeds 50% of the total weight of the acrylate monomer and filler, the viscosity of the composition excessively increases, and light cannot sufficiently penetrate during the 3D printing process using the DLP method, which hinders the curing of the layer, and thus the output quality of the 3D printing may be reduced.

[0062] The photocurable 3D printing composition of the present invention may further include a photoinitiator. The photoinitiator initiates a photopolymerization reaction of the photocurable composition by generating radicals or cations upon being excited by ultraviolet (UV) light or visible light.

[0063] The photoinitiator is not particularly limited as long as it is a photoinitiator that absorbs light in the wavelength range of 350 to 420 nm and is used in the art, but a phosphine oxide-based photoinitiator is preferred.

[0064] Examples may include diphenyl-(2,4,6-trimethylbenzoyl)-phosphine oxide, ethyl-(2,4,6-trimethylbenzoyl)phenyl-phosphinate, and phenyl-bis-(2,4,6-trimethylbenzoyl)-phosphine oxide.

[0065] In the present invention, the photoinitiator may be included in the range of 0.1 wt% to 5 wt% in the entire photocurable composition, and preferably may be included in the range of 0.5 wt% to 2 wt%.

[0066] When the photoinitiator content is less than 0.1 wt%, internal curing of the photocurable composition is difficult, resulting in collapse or under-curing during the laminated formation of the molded article, thereby deteriorating the mechanical properties of the molded article. On the other hand, when the photoinitiator content exceeds 5 wt%, over-curing may occur, which may cause cracks in the molded article and severe yellowing of the molded article.

[0067] Below, a method for manufacturing a molded body using the above photocurable 3D composition is described.

[0068] FIG. 1 is a flowchart illustrating a method for manufacturing a molded article using a photocurable 3D printing composition according to one embodiment of the present invention.

[0069] Prepare raw materials for a photocurable 3D printing composition (S110).

[0070] The photocurable composition for 3D printing using the stereolithography apparatus (SLA) or digital light processing (DLP) method must be prepared in a homogeneous liquid form at ambient temperature before curing, and it is desirable to have a relatively low viscosity and a fast curing speed.

[0071] The 3D printing composition of the present invention comprises at least one acrylate monomer, an inorganic filler, and a photoinitiator as described above.

[0072] As described above, the inorganic filler may be nano-silica particles whose surface is hydrophobically treated to ensure compatibility with the acrylate monomer. A colloidal solution of nano-silica particles is prepared by removing the solvent and redispersing the nano-silica particles in at least one type of acrylate monomer.

[0073] The raw materials of the prepared photocurable 3D printing composition are mixed at a preset ratio to form a photocurable composition (S120).

[0074] As described above, the photocurable 3D printing composition of the present invention may include at least one acrylate monomer and an inorganic filler in a weight ratio of 7:3 to 5:5. The photoinitiator is included in a weight ratio of 0.5 wt% to 2 wt% based on the total weight of the composition.

[0075] Additionally, at least one acrylate monomer may be composed of a first acrylate monomer and a second acrylate monomer, and in this case, a bifunctional acrylate monomer may be used as the first acrylate monomer.

[0076] The composition for 3D printing is formed in a liquid state, and each raw material is mixed and stirred at 50°C or higher for more than 1 hour. The stirring process is performed until each material is completely dissolved and formed in a uniformly dispersed state.

[0077] The photocurable 3D printing composition according to the present invention has a viscosity of 5,000 cps or less, or 4,000 cps or less, at room temperature (25°C). In addition, the viscosity at room temperature is generally 100 cps or more.

[0078] A three-dimensional structured molded product is printed using the prepared photocurable 3D printing composition (S130).

[0079] As described above, the output of the 3D printing composition of the present invention can be performed by a 3D printer of the SLA method or the DLP method.

[0080] The SLA and DLP methods output a molded product layer by layer by pouring a liquid photocurable composition into a tank and curing it with an ultraviolet laser while moving it up or down in the vertical direction (Z-axis).

[0081] The 3D printer output using the photocurable 3D printer composition of the present invention can cure the output by irradiating it with ultraviolet rays having a wavelength of 385 nm or 405 nm.

[0082] Meanwhile, before printing using a 3D printer, the design for the output of an object intended for use as a jig or fixture is first performed. Then, slicing is performed, inputting the conditions for printing the designed molded object (such as printing speed, layer height, thickness, temperature, and nozzle size) into the printer. 3D printing is then performed according to the input printing conditions.

[0083] Post-processing of the molded product printed from the 3D printer is performed (S140).

[0084] Once 3D printing is complete, the print is removed from the printer, and the supports are removed. Since traces of the supports may remain on the print, the surface of the print can be polished as needed.

[0085] Meanwhile, 3D printing using SLA or DLP methods may leave some photocurable composition remaining on the surface of the molded product, requiring a cleaning process to remove the remaining composition. Therefore, cleaning can be performed on the output from which the supporter has been separated to remove any remaining foreign matter and composition.

[0086] Additionally, the output after cleaning can undergo additional secondary curing. In 3D printing, solidification and shape maintenance are achieved through secondary curing.

[0087] At this time, secondary curing can be performed by UV curing and / or post-baking. Post-baking is a post-thermosetting step performed to complete polymerization and cross-linking of the thermosetting resin within the matrix constituting the molded body.

[0088] UV curing is primarily performed for the purpose of maintaining shape, while the subsequent post-baking process hardens the resin and forms crosslinks throughout the mold. In other words, post-baking can improve the strength of the entire molded article.

[0089] For example, when post-baking is performed, a convection oven may be used, and baking may be performed while maintaining a temperature of about 170°C for about 2 to 4 hours.

[0090] As above, secondary curing is performed on the molded product, and the production of the molded product is finally completed.

[0091] The output formed by the photocurable 3D printing composition according to the present invention has a Shore D hardness of 90 or higher.

[0092] The output formed by the photocurable 3D printing composition according to the present invention can exhibit excellent thermal stability and mechanical strength for application as a jig or fixture. Thermal stability is evaluated by the heat deflection temperature (HDT), and the output formed by the photocurable 3D printing composition according to the present invention can have a heat deflection temperature (HDT) of at least 160°C or higher, 170°C or higher, and more preferably 180°C or higher, when measured according to ASTM D648 at 0.46 MPa.

[0093] In addition, the output formed by the photocurable 3D printing composition according to the present invention can achieve a tensile modulus of at least 25 GPa, and more preferably, an elastic modulus of at least 35 GPa is more preferable for use as a jig or fixture.

[0094] Below, the operation and effect of the invention will be examined in more detail through specific examples of the invention.

[0095] The compounds used in the following examples and comparative examples are as shown in Table 1.

[0096]

[0097] (Example 1)

[0098] Tricyclodecane dimethanol diacrylate (TCDDA) was used as the first acrylate monomer, and bisphenol A dimethacrylate (Bisphenol A(EO)4 dimethacrylate, BPA(EO)4DMA), a bifunctional acrylate monomer, was used as the second acrylate monomer. In addition, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide was used as the photoinitiator.

[0099] The first acrylate monomer, tricyclodecane dimethanol diacrylate (TCDDA), is an acrylate monomer having an alicyclic structure, which has excellent heat resistance and chemical resistance and provides excellent ductility, enabling the formation of a network structure in a molded article, which is advantageous for improving mechanical strength.

[0100] Nano-silica particles were used as the inorganic filler. The average diameter of the nano-silica particles ranged from 10 to 15 nm, and nano-silica particles surface-treated with methacrylate were used. After removing the solvent from the nano-silica colloidal solution, it was redispersed in the first acrylate monomer, tricyclodecane dimethanol diacrylate (TCDDA) and applied.

[0101] 45 parts by weight of tricyclodecane dimethanol diacrylate (TCDDA), 10 parts by weight of bisphenol A dimethacrylate (BPA(EO)4DMA), 45 parts by weight of nano silica particles, and phenyl-bis-(2,4,6-trimethylbenzoyl)-phosphine oxide as a photoinitiator were mixed so that 1.77 wt% (1.8 parts by weight) of the total composition was included, and the mixture was stirred at 50°C or higher for 1 hour or longer to prepare a photocurable 3D printing composition.

[0102] The process of printing a molded body using a 3D printing composition was performed by the steps S110 to S140 described above.

[0103] In the second curing stage, additional post-baking was performed, and the post-baking was performed at 170°C for 3 hours.

[0104] (Examples 2 and 3)

[0105] A composition was prepared using tricyclodecane dimethanol diacrylate (TCDDA), bisphenol A dimethacrylate (BPA(EO)4DMA), nano silica particles, and phenyl-bis-(2,4,6-trimethylbenzoyl)-phosphine oxide as a photoinitiator, in the same manner as in Example 1, except that the content of each component was different from that of Example 1.

[0106] (Examples 4 to 6)

[0107] The first acrylate monomer was tricyclodecane dimethanol diacrylate (TCDDA), the same as in Example 1. However, in Examples 4 to 6, the type of the second acrylate monomer was different: polyester acrylate, a multifunctional acrylate monomer (Example 4), and 4-acryolyl morpholine, a monofunctional acrylate monomer (Examples 5 and 6), and the photoinitiator was applied in the same manner as in Example 1.

[0108] The process of manufacturing a molded body by 3D printing using the composition was also applied in the same manner as in Example 1.

[0109] (Comparative examples 1 to 3)

[0110] The first acrylate monomer, inorganic filler, and photoinitiator were included in the same manner as in the examples, and a molded body was manufactured through the same process as in the examples, except that the type of the second acrylate monomer and the content of each component were different.

[0111] (Comparative examples 4 to 7)

[0112] Comparative examples 4 to 7 consisted of compositions for a photocurable 3D printer that did not contain an inorganic filler.

[0113] In order to secure mechanical strength and thermal stability in a 3D printing composition that does not contain an inorganic filler, tris(2-hydroxyethyl)isocyanurate triacrylate (THEICTA) was used as the first acrylate monomer in Comparative Examples 4 to 7.

[0114] Tris(2-hydroxyethyl)isocyanurate triacrylate (THEICTA) is an acrylate monomer with three functional groups. It has a high photocuring speed and a relatively low shrinkage rate during curing, which is advantageous for shape retention, so it is often used in DLP methods.

[0115] In addition, tris(2-hydroxyethyl)isocyanurate triacrylate (THEICTA) is an acrylate that provides excellent mechanical strength and rigidity after curing and has excellent heat and chemical resistance. However, it exists in a solid state at room temperature and has a relatively high glass transition temperature (T g ) makes it difficult to use.

[0116] In Comparative Examples 4 to 7, since no inorganic filler was used, 4-acryolyl morpholine was included as a diluent in addition to tris(2-hydroxyethyl)isocyanurate triacrylate (THEICTA).

[0117] Additionally, it was made to further include bisphenol A dimethacrylate (BPA(EO)4DMA) or hydroxyl pivalic acid neopentyl glycol diacrylate (HPNDA).

[0118] Table 2 below shows the ingredient contents of the 3D printing compositions of the examples and comparative examples.

[0119]

[0120] (How to make and evaluate a psalm)

[0121] The photocurable compositions manufactured in the above examples and comparative examples were printed as test specimens through 3D printing to evaluate their physical properties. The specimens of the examples and comparative examples were evaluated for Shore D hardness, tensile strength, impact strength, and heat distortion temperature before and after post-baking.

[0122] Tensile strength was evaluated by measuring tensile modulus, tensile strength, and tensile elongation at break according to ASTM D638. Impact strength was measured by notched Izod impact strength according to ASTM D256.

[0123] Additionally, the thermal stability of each specimen was evaluated by measuring the heat distortion temperature (HDT) at 0.46 MPa according to ASTM D648.

[0124] Table 3 shows the results of property evaluation of test specimens manufactured using the compositions of Examples 4 to 7 including an inorganic filler and Comparative Examples 4 to 7 not including an inorganic filler.

[0125] Examples 1 to 6 using inorganic fillers all exhibited a heat distortion temperature (HDT) of 170°C or higher at 0.46 MPa, indicating that excellent heat resistance performance can be secured by using inorganic fillers.

[0126] It is reported that rigid cured products manufactured by 3D printing using a conventional photocuring method exhibit a heat distortion temperature (HDT) in the range of 30°C to 80°C and have an impact strength of 20 to 25 J / m. In addition, it is reported that the higher the heat distortion temperature (HDT) of a curable molded article manufactured by an additive manufacturing method, the lower the impact strength. However, the molded article manufactured using the photocurable 3D composition of the present invention shown in Table 3 exhibited a heat distortion temperature (HDT) of 170°C or higher even without performing post-baking.

[0127]

[0128] In addition, the examples show that the composition of the present invention has a Shore D of 90 or more and an impact strength of 25 J / m or more even before performing post-baking, so that it can be seen that the composition of the present invention can produce a molded article having sufficient heat resistance performance and impact resistance.

[0129] In addition, all examples after the post-baking process exhibited a heat deflection temperature (HDT) of 180°C or higher. Examples 1 to 3, which used tricyclodecane dimethanol diacrylate (TCDDA) as the first acrylate monomer and bisphenol A dimethacrylate (BPA(EO)4DMA) as the second acrylate monomer, showed increased impact strength and elastic modulus after the post-baking process.

[0130] In particular, the compositions of Examples 1 and 2, which include 45 parts by weight of tricyclodecane dimethanol diacrylate (TCDDA), 10 parts by weight of bisphenol A dimethacrylate (BPA(EO)4DMA), and 45 parts by weight of nano silica particles, exhibit an elastic modulus of 50 GPa after post-baking, and it can be seen that sufficient properties can be implemented for application as a jig or fixture when considering the heat distortion temperature (HDT).

[0131] Meanwhile, looking at the results of the specimens of Comparative Examples 4 to 7 that did not include an inorganic filler, it was shown that it was possible to manufacture a molded article having a heat distortion temperature of 100°C or higher by applying tris(2-hydroxyethyl)isocyanurate triacrylate (THEICTA) as the first acrylate monomer. However, unlike the examples that applied an inorganic filler, the comparative examples that did not use an inorganic filler showed relatively high tensile strength and tensile elongation at break, and the elastic modulus was actually lower than that of the examples.

[0132] The 3D printing composition of the present invention, including an inorganic filler, exhibits a relatively high modulus of elasticity and a high heat distortion temperature, enabling the production of highly rigid molded articles. While the elongation at tensile fracture is somewhat low, these properties do not pose a significant problem when used as jigs or fixtures formed into relatively thick structures. In other words, molded articles possessing a high modulus of elasticity, impact strength, hardness, and excellent heat distortion temperature are highly suitable for use in structures such as jigs and fixtures.

[0133] Table 4 shows the results of property evaluation of test specimens manufactured by the compositions of Examples 1 to 3 including inorganic fillers.

[0134] When examining the results of property measurements of Examples 1 to 3 and Comparative Examples 1 in which the first acrylate monomer and the inorganic filler were applied in the same manner, it can be confirmed that there is no significant difference in impact strength and heat distortion temperature between Examples and Comparative Examples.

[0135] However, it can be confirmed that the elastic modulus of the molded body significantly differs due to the difference in the second acrylate monomer. In addition, it can be confirmed that the elastic modulus of the compositions of Comparative Examples 1 to 3 does not substantially improve even when post-baking is performed on the molded body. This can be interpreted as a result due to the difference in the content of the first acrylate monomer and the type of the second acrylate monomer.

[0136] The photocurable 3D composition of the present invention can improve the heat distortion temperature (HDT), elastic modulus, hardness, and impact strength of the molded article compared to conventional acrylate-based photocurable compositions. In particular, the composition of the present invention can achieve mechanical strength and heat resistance sufficient for application as jigs and fixtures by using inorganic fillers and acrylate monomers.

[0137] Furthermore, a molded article having high hardness, elastic modulus, and heat distortion temperature produced from the composition of the present invention is sufficient to be applied as a mold.

[0138]

[0139] Although each process is described as being executed sequentially in FIG. 1, this is merely an illustrative description of the technical idea of ​​one embodiment of the present invention. In other words, a person of ordinary skill in the art to which one embodiment of the present invention pertains may modify and apply various modifications and variations, such as changing the order of the processes described in each drawing and executing them or executing one or more of the processes in parallel, without departing from the essential characteristics of one embodiment of the present invention. Therefore, FIG. 1 is not limited to a chronological order.

[0140] The above description is merely an example of the technical idea of ​​the present embodiment, and those skilled in the art will appreciate that various modifications and variations can be made without departing from the essential characteristics of the present embodiment. Therefore, the present embodiments are not intended to limit the technical idea of ​​the present embodiment, but rather to explain it, and the scope of the technical idea of ​​the present embodiment is not limited by these embodiments. The scope of protection of the present embodiment should be interpreted by the claims below, and all technical ideas within a scope equivalent thereto should be interpreted as being included in the scope of rights of the present embodiment.

[0141] Meanwhile, the processes illustrated in FIG. 1 can be implemented as computer-readable code on a computer-readable recording medium. A computer-readable recording medium includes all types of recording devices that store data that can be read by a computer system. That is, a computer-readable recording medium includes storage media such as magnetic storage media (e.g., ROM, floppy disks, hard disks, etc.), optical reading media (e.g., CD-ROMs, DVDs, etc.), and carrier waves (e.g., transmitted via the Internet). In addition, a computer-readable recording medium can be distributed across network-connected computer systems, so that the computer-readable code can be stored and executed in a distributed manner.

[0142] This patent is the result of research conducted with the support of the Korea Institute of Industrial Technology Planning and Evaluation with funding from the Korean government (Ministry of Trade, Industry and Energy) from 2022 to 2024 (Project Unique Number: 1415185693, Sub-Project Number: 20021943, Project Name: Development of Convergence Production Technology for Purpose-Built Vehicle (PBV) Internal Components through Establishment of Automated Equipment for Semi-Mass Production 3D Printing Technology).

[0143]

[0144] CROSS-REFERENCE TO RELATED APPLICATION

[0145]

[0146] *This patent application claims priority under 35 USC § 119(a) of Korean Patent Application No. 10-2023-0194986, filed in Korea on December 28, 2023, the entire contents of which are incorporated by reference herein. Furthermore, if this patent application claims priority in countries other than the United States for the same reasons, the entire contents of which are incorporated by reference herein.

Claims

1. A photocurable composition for laminated manufacturing, At least one acrylate monomer; Photoinitiator; and Weapon Filler A photocurable 3D printing composition having improved heat resistance, including:

2. In paragraph 1, At least one of the above acrylate monomers, Containing a first acrylate monomer and a second acrylate monomer, A photocurable 3D printing composition with improved heat resistance, characterized in that the first acrylate monomer is a difunctional acrylate monomer.

3. In paragraph 1, The above weapon filler is, A photocurable 3D printing composition with improved heat resistance, wherein the composition comprises at least one selected from the group consisting of SiO2, CaCO3, Al2O3, TiO2, ZnO2, carbon black, or a combination thereof.

4. In paragraph 1, A photocurable 3D printing composition with improved heat resistance, characterized in that the at least one acrylate monomer and the inorganic filler are contained in a weight ratio of 7:3 to 5:

5.

5. In paragraph 2, The above first acrylate monomer, The weight average molecular weight is 200 to 400 g / mol and the glass transition temperature (T g ) is at least 80℃ or higher. A photocurable 3D printing composition having improved heat resistance.

6. In paragraph 1, The above photoinitiator is, A photocurable 3D printing composition with improved heat resistance, characterized by comprising any one of diphenyl-(2,4,6-trimethylbenzoyl)-phosphine oxide, ethyl-(2,4,6-trimethylbenzoyl)phenyl-phosphinate, and phenyl-bis-(2,4,6-trimethylbenzoyl)-phosphine oxide.

7. In paragraph 3, The above inorganic filler is SiO2, which is a nano-sized silica particle with an average particle diameter of 10-15 nm. A photocurable 3D printing composition having improved heat resistance, characterized by being surface-treated with methacrylate.

8. A step of manufacturing a photocurable 3D printing composition according to any one of claims 1 to 7; A step of curing the photocurable 3D printing composition layer by layer using an ultraviolet (UV) laser to output a molded product in the form of laminated cured layers; and Step for post-processing the printed 3D molded object A method for manufacturing a three-dimensional molded article having improved heat resistance, the method comprising:

9. In paragraph 8, The step of post-processing the above-mentioned printed 3D molded object is: A method for manufacturing a three-dimensional molded article having improved heat resistance, characterized by including a post-baking step.

10. In paragraph 8, The above three-dimensional molded product is, A method for manufacturing a three-dimensional molded article with improved heat resistance, characterized in that the article has a Shore hardness of at least 90D and a tensile modulus of at least 25 GPa as measured according to ASTM D638.

11. An article manufactured by 3D printing using a photocurable composition according to any one of claims 1 to 7, The above article is characterized in that the article has a Shore hardness of at least 90D or higher and a Tensile Modulus of 25 GPa or higher as measured according to ASTM D638.

12. In paragraph 11, The above items are, When tested according to ASTM D648 (0.46 MPa), a heat deflection temperature (HDT) of at least 170℃, An article characterized by having an impact strength (Notched Izod impact strength) of greater than 25 J / m when tested according to ASTM D256.

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