3d structure manufacturing method using a casting mold made of a water-soluble photocurable resin and water-soluble photocurable resin composition for casting mold manufacturing

Abstract

Disclosed is a method for manufacturing a 3D structure using a casting mold made of a water-soluble photocurable resin, and a water-soluble photocurable resin composition for casting mold manufacturing used in the method, wherein, in manufacturing a 3D structure using a casting mold, a water-soluble photocurable resin which is cured by light irradiation and has good solubility in a neutral to alkaline aqueous solution is used, a casting mold for manufacturing a 3D structure is manufactured by a 3D printing technology of a photocuring type, a substrate of a 3D structure to be manufactured is injected in a liquid state into the inside of the thus manufactured casting mold and is cured, and then the water-soluble photocurable resin forming the casting mold is dissolved and removed using water or an alkaline aqueous solution, so that a 3D product of more various shapes can be manufactured more quickly and precisely, and the range of selectable product materials can be effectively expanded.

Description

Technical Field

[0001] This invention relates to a method for manufacturing 3D structures using a casting mold made of a water-soluble photocurable resin, and a water-soluble photocurable resin composition used in the casting mold manufacturing process of this method. More specifically, it relates to a method for manufacturing 3D structures and a water-soluble photocurable resin composition used in the casting mold manufacturing process of this method. The method utilizes a water-soluble photocurable resin that has good solubility in water or alkaline aqueous solutions after curing to manufacture a casting mold for manufacturing 3D structures using photocuring 3D printing technology. The substrate of the 3D structure to be manufactured is injected into the casting mold in a liquid state and cured. The water-soluble photocurable resin forming the casting mold is dissolved and removed using water or an alkaline aqueous solution, thereby enabling the faster and more precise manufacture of 3D structures of various shapes. Background Technology

[0002] Despite its many advantages, 3D printing technology, which has been widely used in various fields recently, still has a relatively slow output speed. At the same time, there are many limitations on the materials available for manufacturing 3D structures. Therefore, it has always been difficult to mass-produce products and to make them widely applicable to the production of products made of various materials.

[0003] On the other hand, before the introduction of this 3D printing technology, one of the existing representative production methods for producing 3D structures was the mold casting method.

[0004] Mold casting is a 3D structure production method that involves injecting molten thermoplastic or chemically reactive liquid materials into a mold that has the shape of the product to be produced. The injected material is then solidified through cooling or chemical reaction to manufacture (cast) the product, which is then separated from the mold.

[0005] In the production of products using mold casting, high-hardness molds with rigid structures are usually used. However, in order to separate the manufactured product from the mold without damaging the product, especially when the product has a relatively complex shape or structure, a complex mold design consisting of multiple parts and a very precise manufacturing and separation process are required.

[0006] Furthermore, to overcome the limitations of high-hardness mold casting mentioned above, casting methods utilizing soft molds such as silicone have recently been introduced. Even in cases where the product structure has a cavity entrance narrower than its interior, the elasticity of the silicone forming the mold can effectively separate the silicone mold and the product to a certain extent without damaging the product. However, for deep cavities or negative cavity structures that significantly expand inward, a single mold cannot be used. As mentioned earlier, it is inevitable that a complex design consisting of multiple parts is required, with multiple molds manufactured and assembled for each part, and then disassembled again after product production. Alternatively, the product to be produced can be divided into multiple parts, cast separately, and then assembled and joined using adhesives or other bonding methods.

[0007] However, this approach ultimately leads to increased mold manufacturing costs and increased manufacturing time. This not only increases the time and cost of product production, but also requires products with severe internal cavities or negative cavity structures to be cast separately into at least two parts before assembly and bonding. Therefore, subsequent processing steps are necessary, especially for products requiring transparent physical properties, where completely removing interface marks is very difficult.

[0008] Recently, in order to overcome the limitations of this mold casting method, as disclosed in Korean Patent Publication No. 10-2337392, a manufacturing method for 3D structures using 3D printing is being actively developed. However, as briefly explained above, 3D printing technology faces many difficulties in establishing a mass production system due to the relatively long time required for the sequential printing process of 2D layer units, the removal of the support structure after printing the 3D structure, and post-processing. Furthermore, the applicable materials must meet certain physical performance requirements of each printing method, making it difficult to effectively replace the production of products based on traditional methods using various materials. Summary of the Invention

[0009] Technical issues

[0010] This invention provides a method to more effectively overcome the limitations of the prior art. The invention provides a method for manufacturing 3D structures, utilizing a water-soluble photocurable resin that exhibits good solubility in water or alkaline aqueous solutions after curing. A casting mold for manufacturing the 3D structure is created using photocuring 3D printing technology. The substrate of the 3D structure to be manufactured is injected into the casting mold in a liquid state and cured. The water-soluble photocurable resin forming the casting mold is then dissolved and removed using water or an alkaline aqueous solution. The purpose of this method is to provide an efficient, rapid, and precise method for manufacturing 3D structures composed of a wider range of product materials and complex structures, while also providing a water-soluble photocurable resin composition that can be effectively used in the casting mold manufacturing process of this method.

[0011] Problem-solving methods

[0012] To achieve the above objectives, the present invention provides a method for manufacturing 3D structures using a casting mold made of water-soluble photocurable resin. This method comprises the following steps: using water-soluble photocurable resin as the printing material, a 3D structure casting mold is manufactured using a photocurable 3D printing process; liquid casting material for forming the 3D structure is injected into the mold; air bubbles remaining inside the mold are removed using a vacuum chamber; the injected casting material is cured; and the cured casting mold is immersed in an aqueous solution to dissolve and remove the mold.

[0013] Furthermore, as a soluble casting mold manufacturing material that can be effectively used in the above-mentioned manufacturing method, a water-soluble photocurable resin composition is provided, comprising: 10-50 wt% photocurable water-soluble oligomer, which contains at least two or more epoxy or (meth)acrylate reactive groups for photocuring reaction, and includes nitrogen bonds (-N-), ether bonds (-O-), -OH, -COOH, -NH-, -NH2, -N-CO-, M-OH (M represents metal), and sodium (Na) bonds in its main chain structure. + Salt, -SO3M + (where M is H, Na, or K) or N + X - (where X is OH, Cl, or BF4) any one or more; and 50-90 wt% of a photocurable water-soluble monomer, which contains one or two epoxy or (meth)acrylate reactive groups for photocuring reaction, and contains nitrogen bond (-N-), ether bond (-O-), -OH, -COOH, -NH-, -NH2, -N-CO-, M-OH (M represents metal), sodium (Na) in its main chain structure. + Salt, -SO3M + (where M is H, Na, or K) or N + X - The product contains one or more of the following: (where X is OH, Cl or BF4), and includes a photoinitiator, the amount of which is in the range of 1 to 10 wt% relative to the total weight of the resin composition after mixing the photocurable water-soluble oligomer and the photocurable water-soluble monomer.

[0014] The effects of the invention

[0015] The method for manufacturing 3D structures using a casting mold made of a water-soluble photocurable resin according to the present invention manufactures the casting mold for manufacturing 3D structures using photocurable 3D printing technology. Therefore, it has the advantage of being able to manufacture casting molds with complex shapes or structures relatively easily. Furthermore, the photocurable resin forming the mold is configured to have good solubility in water or alkaline aqueous solutions. Thus, after the product injected into the mold has cured, the manufactured product can be easily separated from the mold without damage by immersing the mold in water or an alkaline aqueous solution to dissolve it. Furthermore, even products with significant internal cavities or negative cavity structures can be easily manufactured.

[0016] Furthermore, although the method for manufacturing 3D structures using a casting mold made of water-soluble photocurable resin according to the present invention differs in terms of mold material, mold manufacturing method, and separation method of product from mold, it is essentially a mold casting method similar to conventional methods for producing products. Therefore, it has the advantage of being able to widely utilize various existing materials, such as wax or polymer oligomers, that are traditionally used in products produced by mold casting.

[0017] Furthermore, the photocurable resin composition provided by this invention, with its low viscosity (around 100 cPs to 20,000 cPs) enabling liquid coating and rapid photocuring speed, can be widely used in SLA (Stereolithography) 3D printing using various light sources such as LCD, DLP, or Laser. It is insoluble in traditional organic solvents such as alcohol, acetone, or ketones, which are mainly used for cleaning 3D printed materials, but readily soluble in neutral or alkaline aqueous solutions. Therefore, after the product injected into the mold solidifies using a photocurable 3D printing process to form a casting mold for manufacturing 3D structures, it can be easily dissolved in an aqueous solution by simply immersing it in water or an alkaline aqueous solution for a certain period of time. This allows for easy separation of the solidified 3D structure from the mold without worrying about damaging its structure or surface, thus enabling its widespread application in manufacturing various 3D structures containing complex shapes or cavity structures.

[0018] Furthermore, since the heat deflection temperature (HDT) of the photocured resin can be controlled by adjusting the composition of the resin composition, it can be applied not only to the production of 3D structures using materials with relatively low melting points, such as wax models used in lost-wax casting, but also to the production of 3D structures using various existing mold casting materials (including polymer oligomers with high melting points above 200°C). Attached Figure Description

[0019] Figure 1 This is a flowchart that briefly summarizes the execution process of the method for manufacturing 3D structures using a casting mold made of water-soluble photocurable resin according to the present invention.

[0020] Figure 2 The accompanying drawing exemplarily illustrates a casting mold manufactured for producing buckles according to an embodiment of the present invention.

[0021] Figure 3 The accompanying drawings exemplarily illustrate the method for manufacturing 3D structures using a casting mold made of a water-soluble photocurable resin according to the present invention, and the buckle manufactured using a lost-wax material. Detailed Implementation

[0022] Hereinafter, several preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the present invention is not limited to the following embodiments without departing from its spirit.

[0023] Methods of implementing the invention

[0024] As briefly described above, in the 3D structure manufacturing method according to the present invention, a water-soluble photocurable resin is used as the base material to manufacture a casting mold for manufacturing 3D structures.

[0025] Here, the resin composition used to manufacture casting molds for 3D structure manufacturing according to the present invention is a water-soluble photocurable resin composition developed to optimize the manufacture of soluble casting molds for the present invention. It possesses the characteristics of rapid curing via photoreaction such as ultraviolet (UV) light and easy solubility in neutral to alkaline aqueous solutions. Based on these physical properties, this resin composition, through a 3D printing process utilizing a photocurable reaction, can relatively easily manufacture casting molds composed of diverse and complex shapes and structures. Furthermore, after the material injected into the mold cures into a 3D structure, it can be immersed in water or an alkaline aqueous solution along with the cured 3D structure and dissolve, thereby enabling the manufactured 3D structure to be easily and non-destructively separated from the mold.

[0026] To achieve the above-mentioned characteristics, the water-soluble photocurable resin composition for manufacturing soluble casting molds according to the present invention is characterized by using a mixture of photocurable water-soluble oligomers having epoxy or (meth)acrylate reactive groups for photocuring reactions and photocurable water-soluble monomers as the base material, and may further include: i) a photoinitiator for photocuring reactions, ii) a water-soluble resin added to improve the processability of the casting mold, iii) a water-soluble filler added to improve the solubility of the cured casting mold, iv) a pigment to improve the 3D printing accuracy during casting mold manufacturing, and v) other additives, etc. This composition has a low viscosity of less than 20,000 cPs, so that it can be effectively used for top-down or bottom-up 3D printing using DLP (Digital Light Processing), LCD (Liquid Crystal Display), or Laser, etc.

[0027] The components of a water-soluble, light-curing resin composition for manufacturing soluble casting molds

[0028] (1) Photocurable water-soluble oligomers

[0029] It is an oligomer with at least two epoxy or (meth)acrylate reactive groups for photocuring. To make it easily soluble in neutral to alkaline aqueous solutions, its main chain structure contains nitrogen bonds (-N-) or ether bonds (-O-), or other groups such as -OH, -COOH, -NH-, -NH2, -N-CO-, M-OH (M represents a metal), sodium (Na) + Salt, -SO3M + (where M is H, Na, or K) and N + X - (where X is OH, Cl or BF4), etc., with a molecular weight typically in the range of 400 g / mole to 500,000 g / mole, and a viscosity at room temperature of over 1,000 cPs or existing in solid form.

[0030] (2) Photocurable water-soluble monomers

[0031] It is a monomer with one or two epoxy or (meth)acrylate reactive groups for photocuring. To make it easily soluble in neutral to alkaline aqueous solutions, its main chain structure contains nitrogen bonds (-N-) or ether bonds (-O-), or other such as -OH, -COOH, -NH-, -NH2, -N-CO-, M-OH (M represents a metal), sodium (Na) + Salt, -SO3M + (where M is H, Na, or K) and N + X -(where X is OH, Cl or BF4), etc., and the molecular weight is usually below 400 g / mole.

[0032] (3) Photoinitiator

[0033] In the 3D printing process, the light energy transmitted by the light source is converted into chemical energy, which enables the photocurable water-soluble resin to cure. This process can be achieved by using various photoinitiators commonly used in photocuring reactions.

[0034] Photoinitiators can be broadly classified into free radical initiators and cationic initiators. Commonly used free radical initiators include benzophenone derivatives, benzyl ketones, monomeric hydroxyl ketones, polymeric hydroxyl ketones, α-amino ketones, acyl phosphine oxides, metallocenes, benzoin ethers, benzil ketals, α-hydroxyalkylphenones, and α-aminoalkylphenones. Cationic initiators include isopropyl thioxanthenones, arylsulphonium salts, and aryl iodonium salts.

[0035] The water-soluble photocurable resin composition for manufacturing soluble casting molds involved in this invention can be prepared by mixing the above-mentioned photocurable water-soluble oligomer and photocurable water-soluble monomer in proportions of approximately 10-50 wt% and 50-90 wt%, respectively. At this time, the mixing ratio can be appropriately adjusted according to the viscosity required by the 3D printer. Preferably, a mixing ratio of approximately 20-40 wt% of photocurable water-soluble oligomer and approximately 60-80 wt% of photocurable water-soluble monomer is more likely to achieve effective viscosity characteristics.

[0036] Furthermore, the content of photoinitiator added to the composition formulated with the above-mentioned photocurable water-soluble oligomer and photocurable water-soluble monomer can also be adjusted according to the type and amount of light source suitable for the 3D printer. It can be added in an amount of about 1 to 10 wt% relative to 100 wt% of the composition, preferably in the range of 2 to 5 wt%.

[0037] That is, the water-soluble photocurable resin composition for manufacturing soluble casting molds involved in this invention is made by adding a photoinitiator for photocuring reaction to a composition formulated with photocurable water-soluble oligomers and photocurable water-soluble monomers, thereby completing the basic composition of the resin composition.

[0038] Here, the photocurable water-soluble oligomer contained in the resin composition enhances the overall strength of the casting mold by increasing the physical hardness and elongation at break of the photocured 3D printed material. Various commercially available products can be used, such as SOLTECH's SU550, SU550A, SU560, SWA8048, SWA8071, SWA8083, etc., as well as other commercially available products.

[0039] In addition, the aforementioned commercially available products are usually supplied in a state of being mixed with water or other solvents. In this case, in order to more effectively ensure the structural integrity of the casting mold during the 3D printing process, it is recommended to use products with a water or solvent content of less than 10 wt%.

[0040] The photocurable water-soluble monomers contained in the resin composition, by mixing with the photocurable water-soluble oligomers having relatively high viscosity, reduce the viscosity of the entire resin composition, thereby achieving the appropriate viscosity required for 3D printing. For example, ACMO (acryloylmorpholine), DMAA (N,N-dimethylacrylamide), HEAA (N-(2-hydroxyethyl)acrylamide) containing nitrogen bonds (-N-), MAANa (sodium methacrylate) containing sodium salts, or those containing -SO3M... + Potassium 3-sulfopropyl acrylate, etc.

[0041] In the case of ACMO, its glass transition temperature (Tg) has a high value of over 145°C, making it particularly suitable for manufacturing resin compositions for soluble molds that require use at high temperatures.

[0042] In addition to the above-mentioned photocurable water-soluble oligomer, photocurable water-soluble monomer and photoinitiator, the water-soluble resin composition for manufacturing soluble casting molds according to the present invention may further contain the following components.

[0043] (4) Water-soluble resin

[0044] Water-soluble resins can be added to improve the hardness and strength of the cured resin and enhance the machinability of casting molds. To ensure easy dissolution in neutral to alkaline aqueous solutions, its main chain structure contains nitrogen bonds (-N-) or ether bonds (-O-), or other bonds such as -OH, -COOH, -NH-, -NH2, -N-CO-, M-OH (M represents a metal), sodium (Na)+ Salt, -SO3M + (where M is H, Na, or K) and N + X - (where X is OH, Cl or BF4), etc., but does not have any photoreactive group structure such as the aforementioned epoxy or (meth)acrylate reactive group.

[0045] For example, there are polyvinyl alcohol (PVA) or polyglycerol containing -OH, polyacrylamide (PAAM) containing -NH2, or PVP (polyvinylpyrrolidone) containing -N-, as well as PVH (polyvinylamine hydrochloride) containing chlorine (-Cl), polymaleic acid containing -COOH, or polystyrene sulfonic acid containing sodium salt, etc.

[0046] The water-soluble resins that do not have photoreactive groups can be added in the range of 5 to 40 wt% of the total weight of the resin composition, but preferably in the range of 5 to 15 wt%.

[0047] (5) Water-soluble fillers

[0048] It exists in water-soluble powder form, dissolving well in water, but is completely insoluble in photocurable oligomers or monomers, remaining in the photocurable resin composition as a powder mixture. During the light-curing process of the resin, it is added to inhibit resin shrinkage caused by light curing, while effectively shortening the dissolution time of the casting mold in the aqueous solution.

[0049] Examples of water-soluble fillers that can be added to the resin composition of the present invention include sugars, salts, potassium chloride (KCl), boric acid (H3BO3), potassium carbonate (KHCO3), sodium carbonate (NaHCO3), ammonium carbonate (NH4HCO3), calcium chloride (CaCl2), etc. The type of water-soluble filler added can be appropriately selected based on the physical properties of the aqueous solution used to dissolve the casting mold. In this case, the filler content is controlled according to the pH concentration, temperature, and structure of the aqueous solution used for dissolution.

[0050] Generally, water-soluble fillers can be added up to 50 wt% of the total weight of the resin composition, but are preferably added in the range of 10 to 20 wt%.

[0051] (6) Pigments

[0052] During the 3D printing process using light irradiation, it performs the following functions: suppressing the light leakage of the 2D image irradiated in each layer into the surrounding resin and solidifying the resin around the 2D image to be printed, thereby preventing burrs or holes from being generated on the output or deformation of the output printed object, thereby improving the accuracy of 3D printing.

[0053] The pigments added to the resin composition can be appropriately selected according to the type and amount of light source used in 3D printing. They are usually added in the range of 0.01 to 2.00 wt% of the total weight of the resin composition, preferably in the range of 0.02 to 0.10 wt%.

[0054] (7) Other additives

[0055] In addition, the water-soluble photocurable resin composition involved in this invention may also contain a variety of other additives, such as defoamers for defoaming, dispersants to improve the dispersing power of the added water-soluble fillers, polymerization inhibitors to prevent the resin composition from curing during storage, and silane additives to improve the heat resistance of the resin composition. These additives are typically added in the range of 0.5 to 2.0 wt% of the total weight of the resin composition.

[0056] The water-soluble photocurable resin composition used in the manufacture of soluble casting molds of the present invention achieves the following characteristic physical properties through the combination of the above-mentioned components.

[0057] ▶ Photocurability: Can be applied within a wavelength range of 200 ~ 900 nm and an energy level of 1.0 ~ 10.0 mJ / cm². 2 It is cured by irradiation with light.

[0058] ▶ Viscosity: A viscosity ranging from 100 cPs to 20,000 cPs that enables liquid coating and is effective for top-down or bottom-up 3D printing under light irradiation.

[0059] ▶ Solubility: The degree to which a 5mm cube 3D printed object can completely dissolve or swell within 3 hours when immersed in a neutral or alkaline aqueous solution with a pH above 6.0.

[0060] ▶ Cleanability: After curing, it is insoluble in common organic solvents such as alcohol, acetone or ketones, so it can be cleaned with organic solvents after printing.

[0061] ▶ Hardness after curing: After curing, the secant modulus is above 500MPa and the elongation at break is above 4%.

[0062] ▶ Heat resistance: Heat deflection temperature (HDT) is above 70℃, preferably above 150℃.

[0063] Example 1: Water-soluble photocurable resin composition #1: Resin composition A

[0064] A photocurable water-soluble oligomer SWA8083 containing multiple ether bonds (-O-) and multiple hydroxyl groups (-OH) was formulated by adding 30.0 wt% of SWA8083, a photocurable water-soluble monomer containing -NH and -OH, 56.0 wt% of HEAA [N-(2-Hydroxyethyl)acrylamide], a photocurable monomer containing -OH, 10.0 wt% of HEMA [2-Hydroxyethyl Methacrylate], a photocurable monomer containing -OH, 3.35 wt% of TPO [2,4,6-trimethylbenzoyldiphenyl phosphine oxide] as a photoinitiator, 0.15 wt% of BKP, a carbon black dispersion pigment from Nichizo Corporation, as other additives, and 0.5 wt% of BYK-011 as a defoamer. A water-soluble photocurable resin composition A was prepared that can be photocured for 3D printing and is readily soluble in neutral or alkaline aqueous solutions after curing.

[0065] The resin composition A prepared as described above has a viscosity of 520 cPs at room temperature. It was confirmed that a 50 μm thick film can be cured within 1.5 seconds in an LCD 3D printer irradiated with light at a dose of 0.2 mW / cm². After curing, the secant modulus (1.0% elongation) of the cured film was measured to be 1,200 MPa, and the elongation at break was 1.5%.

[0066] <Solubility test of the cured resin composition after curing>

[0067] Using the above-described resin composition A, a cube with dimensions of 5 mm x 5 mm x 5 mm was manufactured by 3D printing using an LCD 3D printer through a layer-by-layer deposition method with a thickness of 50 μm. After removing the uncured resin residue on the surface of the manufactured cube by cleaning with acetone, it was irradiated with light at a light intensity of 20 mW / cm² in a post-curing unit for 10 minutes for post-curing.

[0068] The printed cubic specimens were then immersed in NaOH aqueous solutions of different concentrations and temperatures, and the changes in solubility over time were observed. The results are summarized in [Table 1].

[0069] [Table 1]

[0070] [Solubility of cubes based on the concentration and temperature of NaOH aqueous solution]

[0071] As confirmed in [Table 1], cubic specimens printed using the water-soluble photocurable resin composition of the present invention are readily soluble in neutral to alkaline aqueous solutions. Although the higher the NaOH concentration, the faster the dissolution rate, the dissolution rate does not change significantly when the NaOH concentration exceeds 10 wt%. Furthermore, comparative examples in 10 wt% NaOH solutions show that the higher the aqueous solution temperature, the faster the dissolution rate.

[0072] Example 2: Water-soluble photocurable resin composition #2: Resin compositions B1 ~ B6

[0073] The mixture comprises 30.0 wt% of SWA8083, a photocurable water-soluble oligomer containing multiple ether bonds (-O-) and multiple hydroxyl groups (-OH); 56.0 wt% of HEAA [N-(2-Hydroxyethyl)acrylamide], a photocurable water-soluble monomer containing -NH and -OH; 5.0 wt% of HEMA [2-Hydroxyethyl Methacrylate], a photocurable monomer containing -OH; 3.35 wt% of TPO [2,4,6-trimethylbenzoyldiphenyl phosphine oxide] added as a photoinitiator; and 0.15 wt% of BKP, a carbon black dispersion pigment from Nichizo Corporation, and 0.5 wt% of defoamer BYK-011, mixed with 5.0 wt% of PVA (Polyvinyl alcohol, molecular weight 10,000), a non-reactive water-soluble resin without photoreactive groups. (g / mole) was used to prepare resin composition B1 for testing the compatibility of non-reactive water-soluble resins in resin compositions.

[0074] Next, the content of HEAA was reduced to 51.0 wt% and 41.0 wt%, respectively, while the content of PVA was increased to 10.0 wt% and 20.0 wt% respectively, to prepare resin compositions B2 and B3.

[0075] Meanwhile, under the same conditions, PVA was replaced with another non-reactive water-soluble resin, polyglycerin (PG, molecular weight 2,000 g / mole), and resin compositions B4 to B6 with PG contents of 5.0 wt%, 10.0 wt%, and 20.0 wt% were prepared.

[0076] After thoroughly stirring the resin compositions B1 to B6 mixed according to the above proportions in a water tank, confirm at room temperature whether the non-reactive water-soluble resin separates and precipitates.

[0077] [Table 2]

[0078] [Based on compatibility test of non-reactive water-soluble resin content (unit: wt%)]

[0079] As shown in [Table 2], the non-reactive water-soluble resins PVA and PG were well dissolved in the resin composition at ratios of 5.0 wt% and 10.0 wt%, respectively. However, when the content increased to 20.0 wt%, it was confirmed that some of them were not mixed into the resin composition and precipitated out. Repeated experiments with varying amounts of water-soluble resin showed that no separation or precipitation of PVA and PG occurred within the range of 5.0 to 15.0 wt%.

[0080] <Testing of Physical Properties and Curing Speed ​​of Cured Resin Compositions>

[0081] Using B1, B2, B4, and B5 of the aforementioned resin compositions B1 to B6, whose water-soluble resin compatibility was confirmed, as printing materials, the time required for complete curing of a 50 μm thick film was measured in an LCD 3D printer with a light output of 0.2 mW / cm². Subsequently, the secant modulus and elongation at break of the fully cured film were measured.

[0082] [Table 3]

[0083] [Physical property testing of resin compositions containing non-reactive water-soluble resins and their outputs]

[0084] As confirmed in [Table 3], resin composition B1 containing 5.0 wt% non-reactive water-soluble resin has a curing time of 1.5 seconds, showing almost the same curing speed as resin composition A without non-reactive water-soluble resin described in Example 1 above. However, resin composition B2 containing 10.0 wt% non-reactive water-soluble resin has a curing time that increases to 2.2 seconds, indicating that with the increase of non-reactive water-soluble resin content, the curing speed slows down, more light energy is required, and therefore the 3D printing process time required for the printed output increases.

[0085] Observing the physical properties of the cured film, although the secant modulus of the cured film decreased with the increase of the non-reactive water-soluble resin content, conversely, the elongation at break of the cured film increased with the increase of the non-reactive water-soluble resin content. In other words, compared with the film with an elongation at break of 1.5% made using resin composition A without non-reactive water-soluble resin in Example 1, the elongation at break of the film made using B1 to B5 containing non-reactive water-soluble resin as materials increased to 2.2% to 9.8%.

[0086] Next, using the same material, cubic prints with dimensions of 10 mm x 10 mm x 10 mm were produced. Damage was assessed by free-falling from a height of 1 m, and the occurrence of breakage or chipping during CNC surface machining was also confirmed. To pass these tests, an elongation at break of at least 4.0% was required. Resin compositions B2 and B5, containing 10.0% PVA or PG respectively, exhibited sufficient elongation at break to pass the tests.

[0087] <Solubility Test of Cured 3D Printed Output>

[0088] Using resin compositions B1, B2, B4, and B5 used in the above physical performance tests, as well as resin composition A described in Example 1, a cube with dimensions of 5 mm x 5 mm x 5 mm was manufactured by 3D printing using an LCD 3D printer in a layer-by-layer deposition manner with a thickness of 50 μm. After removing the uncured resin residue on the surface of the manufactured cube by cleaning with acetone, it was irradiated with light at a light intensity of 20 mW / cm² in a post-curing unit for 10 minutes for post-curing.

[0089] The printed cubic specimens were then immersed in a 10 wt% NaOH aqueous solution, and the change in solubility over time was observed at room temperature.

[0090] [Table 4]

[0091] [Solubility of the resin composition based on the content of non-reactive water-soluble resin]

[0092] As confirmed in [Table 4], when a non-reactive water-soluble resin is further mixed into the photocurable water-soluble resin composition of the present invention, the higher the content of the mixed non-reactive water-soluble resin, the shorter the time for the manufactured cube to completely dissolve. In particular, in the cases of B2 and B4, when about 10% of the non-reactive water-soluble resin is contained, it is shown that complete dissolution can be achieved within 3 hours.

[0093] Furthermore, while resin compositions containing PG with a relatively smaller molecular weight of 2,000 g / mole exhibit a relatively faster dissolution rate compared to resin compositions containing PVA with a molecular weight of 10,000 g / mole, on the other hand, as shown in the aforementioned physical property comparison, the smaller the molecular weight of the added non-reactive water-soluble resin, the relatively weaker some physical properties of the printed material (such as secant modulus) will be. Therefore, it is preferable to selectively apply an appropriate type of non-reactive water-soluble resin according to the intended use and characteristics of the casting mold to be manufactured.

[0094] Example 3: Water-soluble photocurable resin composition #3: Resin composition C1 ~ C6

[0095] A photocurable water-soluble resin composition C1 was prepared by mixing 30.0 wt% of SWA8083, a photocurable water-soluble oligomer containing multiple ether bonds (-O-) and multiple hydroxyl groups (-OH); 46.0 wt% of HEAA [N-(2-Hydroxyethyl)acrylamide], a photocurable water-soluble monomer containing -NH and -OH; 5.0 wt% of HEMA [2-Hydroxyethyl Methacrylate], a photocurable monomer containing -OH; 3.35 wt% of TPO [2,4,6-trimethylbenzoyldiphenyl phosphine oxide], added as a photoinitiator; 10.0 wt% of non-reactive water-soluble resin PVA; and 0.15 wt% of BKP, a carbon black dispersion type black pigment from Nichizo Corporation, as other additives, and 0.5 wt% of BYK-011, as an antifoaming agent.

[0096] Next, the content of HEAA was reduced to 41.0 wt% and 36.0 wt%, respectively, while the content of sugar was increased to 10.0 wt% and 15.0 wt%, respectively, to prepare resin compositions C2 and C3.

[0097] Meanwhile, under the same conditions, by replacing the 5μm powdered sugar used as a water-soluble filler with 5μm powdered calcium chloride, resin compositions C4 to C6 with calcium chloride contents of 5.0 wt%, 10.0 wt%, and 15.0 wt% were prepared.

[0098] At this point, the water-soluble filler used in this invention has the characteristic of being easily soluble in water but completely insoluble in light-curable water-soluble resin compositions. Therefore, it is necessary to pay attention to the selection of the powder size of the water-soluble filler to be mixed.

[0099] In this embodiment, both sugar and calcium chloride were powders with an average particle size (d50) of 5 μm and a maximum particle size (d90) of less than 8 μm. After the resin compositions C1 to C6 mixed in the above mixing ratio were placed in a water tank and stirred thoroughly, it was confirmed at room temperature whether the water-soluble filler powder separated from the resin composition and precipitated to the bottom.

[0100] [Table 5]

[0101] [Test for filler separation in resin compositions with added water-soluble fillers (unit: wt%)]

[0102] As confirmed in [Table 5], no separation from the resin composition was observed for the water-soluble filler with an average particle size of 5 μm, even after 24 hours of mixing. However, in similar tests, when using a water-soluble filler with an average particle size of 10 μm, it was confirmed that a significant amount of filler separated from the resin composition and precipitated at the bottom of the container within approximately 30 minutes. Therefore, it can be confirmed that when mixing water-soluble fillers into the photocurable water-soluble resin composition of the present invention, it is preferable to use powders with an average particle size of at least 5 μm.

[0103] <Test of physical properties and curing speed of the cured resin composition>

[0104] Using the aforementioned resin compositions C1 to C6 as printing materials, the time required for complete curing of a 50 μm thick film was measured in an LCD 3D printer with a light intensity of 0.2 mW / cm². Subsequently, the secant modulus and elongation at break of the fully cured film were measured.

[0105] [Table 6]

[0106] [Physical property testing of resin compositions containing water-soluble fillers and their outputs]

[0107] As confirmed in [Table 6], as the content of water-soluble fillers mixed in the resin composition increases, the curing resin composition requires more light energy, and therefore the 3D printing process time required for the printed output increases slightly.

[0108] The physical properties of the cured film were observed. Although the secant modulus of the cured film increased with the increase of the water-soluble filler content, the elongation at break decreased slightly. However, it still showed an excellent elongation at break of more than 7.9%, thus confirming that it maintained a high elongation at break sufficient to pass the drop test and CNC processability test, regardless of whether it broke in free fall.

[0109] <Solubility Test of Cured 3D Printed Output>

[0110] Using resin compositions C1 to C6 used in the above physical performance tests, and resin composition B2 described in Example 2 (without water-soluble filler), a cube with dimensions of 5 mm x 5 mm x 5 mm was manufactured by 3D printing using an LCD 3D printer in a layer-by-layer deposition manner with a thickness of 50 μm. After removing the uncured resin residue on the surface of the manufactured cube by cleaning with acetone, it was irradiated with light at a light intensity of 20 mW / cm² in a post-curing unit for 10 minutes for post-curing.

[0111] The printed cubic specimens were then immersed in a 10 wt% NaOH aqueous solution, and the change in solubility over time was observed at room temperature.

[0112] [Table 7]

[0113] [Solubility of the resin composition based on the content of water-soluble filler]

[0114] As confirmed in [Table 7], when water-soluble fillers are further mixed into the photocurable water-soluble resin composition of the present invention, the higher the content of the mixed water-soluble filler, the shorter the time for the manufactured cubes to completely dissolve. In particular, when calcium chloride is used as a filler, a relatively faster dissolution rate is observed compared to when sugar is used. It can be inferred that not only the solubility of the water-soluble filler contained in the resin composition in water, but also the crystal structure of the filler powder affects the solubility of the resin composition.

[0115] As described above, the water-soluble photocurable resin composition according to the present invention, with its low viscosity and rapid photocuring speed enabling liquid coating, can be widely used in SLA 3D printing using various light sources, while also exhibiting easy solubility in neutral or alkaline aqueous solutions. Therefore, by forming a casting mold for manufacturing 3D structures through a photocurable 3D printing process, and after the product injected into the mold has cured, it can be easily dissolved in the aqueous solution by simply immersing it in water or an alkaline aqueous solution for a certain period of time. This allows for easy separation of the cured 3D structure from the mold without concern for damage to its structure or surface, thus enabling its widespread application in manufacturing various 3D structures containing complex shapes or concave structures.

[0116] Hereinafter, with reference to the accompanying drawings, the method for manufacturing 3D structures according to the present invention, which uses a soluble casting mold made from the above-described water-soluble photocurable resin composition as a material, will be described in more detail.

[0117] Figure 1 This is a flowchart that briefly summarizes the execution process of a method for manufacturing 3D structures using a casting mold made of a water-soluble photocurable resin according to the present invention. Figure 1 As shown, in this invention, a water-soluble photocurable resin that meets the aforementioned physical performance requirements is used as the printing material. Through a 3D printing process using photocuring, a casting mold for manufacturing 3D structures for casting the final 3D product is first manufactured (S100).

[0118] At this time, representative 3D printing methods used to manufacture casting molds for the 3D structures of the present invention include SLA (Stereolithography), which can use various light sources such as LCD, DLP or Laser.

[0119] The SLA-based 3D printing technology described above is a well-known and commonly used technology in the field, and its detailed description will be omitted in this specification. In the 3D structure manufacturing method according to the present invention, by applying the photopolymerization 3D printing technology as described above, even casting molds with relatively complex shapes or structures do not require complex pre-preparation, such as individual design or separate manufacturing and assembly of parts. The casting mold of the required structure can be easily manufactured through a simple 3D printing process, thereby effectively shortening the existing mold manufacturing process for 3D product production and significantly reducing mold manufacturing costs.

[0120] At this point, as described above, when manufacturing casting molds for casting target 3D products using 3D printing that utilizes the photocuring properties of resin compositions, such as Figure 2 As shown, a gate (runner, 10) for injecting casting material is formed on one side of the mold to be manufactured, while an outlet (riser, 20) for venting air from the mold is formed on the other side of the mold.

[0121] Figure 2 The accompanying drawing exemplarily illustrates a casting mold manufactured for producing buckles according to an embodiment of the present invention. Figure 2 As shown, an injection port (10) for injecting casting material is formed on one side of the upper part of the casting mold, and an outlet port (20) for discharging air from the mold is formed on the other side.

[0122] Furthermore, when manufacturing casting molds using the aforementioned photopolymerization method via 3D printing, the thickness of the mold wall should not exceed the necessary thickness.

[0123] As will be explained again below, in this invention, after the casting material injected into the mold has solidified, the mold is dissolved by immersing it in water or an alkaline aqueous solution, thereby separating the produced product from the mold. Therefore, the thicker the casting mold, the longer it takes to dissolve, thus reducing production efficiency.

[0124] Therefore, the thickness of the casting mold manufactured according to the present invention only needs to be sufficient to maintain structural stability before the casting material injected into the mold solidifies. It is preferable to set an appropriate thickness taking into account the weight, temperature and / or pressure of the casting material injected into the mold.

[0125] Next, after manufacturing the casting mold according to the above process, liquid casting material is injected into the mold through the injection port (10) formed in the mold (S200), and the air bubbles remaining in the mold are removed through the outlet (20) using the vacuum chamber (S300).

[0126] Next, the step of solidifying the casting material injected into the mold through the above process is performed (S400). At this time, the applicable solidification process can be appropriately selected according to the characteristics of the casting material injected into the mold.

[0127] That is, for thermoplastic resins such as acrylic resins or lost-wax casting, the molten casting material is injected into a mold preheated to a certain temperature by injection and then cooled at room temperature; or for materials that are cured by chemical reaction, such as polyurethane resins or epoxy resins, the liquid resin mixed with the main component and the curing agent is injected into the mold, and after the air bubbles in the liquid resin are removed by a vacuum chamber, the material injected into the mold can be completely cured by mutual reaction in a chamber where a high-pressure environment has been formed to suppress the generation of additional air bubbles.

[0128] After the material injected into the mold has completely solidified, the casting mold containing the solidified material is immersed in water or an alkaline aqueous solution to dissolve and remove the mold (S500). Then, the product production is completed through the cleaning and drying steps (S600).

[0129] Here, the solution used to dissolve the mold can be neutral water directly, but using an alkaline aqueous solution can further increase the dissolution rate of the mold. It is preferred to use a neutral to alkaline aqueous solution in the pH range of 6 to 12.

[0130] At this point, the higher the temperature of the neutral to alkaline aqueous solution used in the mold dissolution process, the faster the dissolution rate. However, excessively high temperatures will not only affect the mold but also the product contained within it. Therefore, the appropriate temperature should be selected by comprehensively considering both the mold material and the material of the product contained within the mold, and it is generally preferred to control the temperature within the range of 20°C to 60°C.

[0131] In addition, the dissolution rate can be further increased by stirring the aqueous solution containing the mold to create flow.

[0132] The 3D structures manufactured by soluble casting molds and mold casting using the aforementioned methods, as briefly explained above, can be used not only for acrylic PMMA resin products, which are the most widely used materials in the existing mold casting method for manufacturing 3D structures, but also for epoxy and / or polyurethane resin products that are cured by chemical reaction, or for the manufacture of silicone structures using reactive silicone, etc.

[0133] In particular, the 3D structure manufacturing method using a casting mold made of water-soluble photocurable resin involved in this invention can be used very effectively to manufacture wax structures for lost-wax casting. The temperature of the wax melt injected into the mold for casting is usually about 120°C, which is not very high. At the same time, no additional high pressure is required during the casting process. Therefore, the thickness of the casting mold made of water-soluble resin composition material for casting wax structures can be reduced to about 3 mm, thereby significantly shortening the manufacturing time of the casting mold. At the same time, due to the reduction in the volume of the casting mold, the time required to dissolve and encapsulate the casting mold after the wax structure has solidified can also be significantly shortened. Therefore, it has the advantage of greatly improving the overall manufacturing efficiency of wax structures.

[0134] Figure 3 The accompanying drawings exemplarily illustrate the manufacturing method of a 3D structure using a casting mold made of a water-soluble photocurable resin according to the present invention, and the resulting product of a complex snap-fit ​​structure that is difficult to manufacture by conventional injection molding methods using a lost-wax material.

[0135] As can be confirmed in the figure, Figure 3 The buckle shown, due to its complex structure including cavities and recesses, requires complex preparation processes such as mold separation and assembly when manufactured using traditional injection molding methods. Moreover, it is not easy to separate the product from the mold after casting. To solve this problem, the product is divided into multiple parts for casting and then assembled, which increases the time and cost of the manufacturing process. At the same time, the final assembled part of the product will not look neat, which has limitations. However, by applying the 3D structure manufacturing method of the present invention using a casting mold made of water-soluble light-curing resin, it can be confirmed that complex buckle products can be accurately realized and manufactured in a single simple casting process.

[0136] The present invention has been described above through representative embodiments. However, these illustrative embodiments are merely examples of preferred embodiments of the invention, and the invention is not limited thereto. The scope of protection of the invention is defined by the claims. Furthermore, it is natural that those skilled in the art can make various modifications while maintaining the spirit of the invention as claimed in the claims. Therefore, such modifications or improvements, as long as their scope falls within the obvious range to those skilled in the art, should be considered to fall within the scope of protection of the invention.

[0137] Industrial applicability

[0138] The water-soluble photocurable resin composition proposed in this invention, with its low viscosity and rapid photocuring speed enabling liquid coating, can be widely used in SLA 3D printing using various light sources. It also exhibits easy solubility in neutral or alkaline aqueous solutions. Therefore, by forming a casting mold for manufacturing 3D structures using a photocurable 3D printing process, and after the product injected into the mold cures, it can be easily dissolved in water or an alkaline aqueous solution by simply immersing it for a certain period. This allows for easy separation of the cured 3D structure from the mold without damage to its structure or surface, thus enabling its widespread application in manufacturing various 3D structures containing complex shapes or cavities.

[0139] Furthermore, the 3D structure manufacturing method of the present invention, utilizing a casting mold made of water-soluble photocurable resin, manufactures the casting mold for producing 3D structures using photocurable 3D printing technology. Therefore, it not only makes it relatively easy to manufacture casting molds with complex shapes or structures, but also allows for the easy and non-destructive separation of the manufactured product from the mold through a simple process of immersing the mold in a neutral to alkaline aqueous solution to dissolve it. Simultaneously, the product manufacturing method, which primarily employs a mold casting approach, allows for the widespread use of various existing materials, such as waxes or polymer oligomers, already used in conventional mold casting methods.

Claims

1. A method for manufacturing a 3D structure using a casting mold made of water-soluble photocurable resin, comprising the following steps: Using water-soluble photocurable resin as the printing material, a casting mold for casting 3D structures is manufactured through a photocurable 3D printing process. Liquid casting material used to form 3D structures is injected into the mold. Use a vacuum chamber to remove air bubbles remaining inside the mold; To solidify the casting material injected into the mold; and The casting mold, in which the injected material has solidified, is immersed in an aqueous solution to dissolve and remove the mold.

2. The method for manufacturing 3D structures using a casting mold made of water-soluble photocurable resin according to claim 1, characterized in that, After the steps of immersing the casting mold in an aqueous solution to dissolve it and then removing the mold, The next step is to clean and dry the 3D structure separated from the mold.

3. The method for manufacturing 3D structures using a casting mold made of water-soluble photocurable resin according to claim 1, characterized in that, The water-soluble photocurable resin includes: i) It has at least two epoxy or acrylate reactive groups, and contains nitrogen (N) in its main chain structure, or contains -OH, -COOH, -NH-, -NH2, -N-CO-, M-OH (M represents a metal), or sodium (Na) + Salt, -SO3M + (where M is H, Na, or K) and N + X - (where X is an oligomer of at least one of OH, Cl or BF4); ii) Having at least one epoxy group or acrylate reactive group, and containing nitrogen (N) in its structural composition, or containing -OH, -COOH, -NH-, -NH2, -N-CO-, M-OH (M represents a metal), or sodium (Na) + Salt, -SO3M + (where M is H, Na, or K) and N + X - (where X is at least one monomer selected from OH, Cl, or BF4); and iii) Photoinitiators used in photocuring reactions.

4. The method for manufacturing 3D structures using a casting mold made of water-soluble photocurable resin according to claim 3, characterized in that, The water-soluble photocurable resin further comprises 5 wt% to 15 wt% of a water-soluble resin that does not have any photocurable reactive groups.

5. The method for manufacturing a 3D structure using a casting mold made of water-soluble photocurable resin according to claim 3, characterized in that, The water-soluble photocurable resin contains at least one functional additive.

6. The method for manufacturing a 3D structure using a casting mold made of water-soluble photocurable resin according to claim 5, characterized in that, The functional additives include functional pigments for improving the accuracy of 3D printing, or carbon nanotubes or inorganic additives for improving the heat transfer coefficient of the printed casting mold.

7. The method for manufacturing a 3D structure using a casting mold made of water-soluble photocurable resin according to claim 3, characterized in that, The water-soluble photocurable resin has a viscosity in the range of 100 cPs to 20,000 cPs.

8. The method for manufacturing a 3D structure using a casting mold made of water-soluble photocurable resin according to claim 6, characterized in that, The water-soluble photocurable resin is configured such that, after curing, the heat deflection temperature (HDT) of the photocurable resin reaches at least 70°C.

9. The method for manufacturing a 3D structure using a casting mold made of water-soluble photocurable resin according to claim 1, characterized in that, In the step of manufacturing casting molds for 3D structures using the aforementioned photopolymerization 3D printing process, A 3D printing method using stereolithography (SLA).

10. The method for manufacturing a 3D structure using a casting mold made of water-soluble photocurable resin according to claim 1, characterized in that, In the step of manufacturing casting molds for 3D structures using the aforementioned photopolymerization 3D printing process, An injection port for injecting casting material is formed on one side of the casting mold to be manufactured, and an exhaust port for venting air from the mold is formed on the other side of the mold.

11. The method for manufacturing a 3D structure using a casting mold made of water-soluble photocurable resin according to claim 1, characterized in that, In the step of manufacturing casting molds for 3D structures using the aforementioned photopolymerization 3D printing process, The thickness of the casting mold to be manufactured is determined by considering the weight, temperature, and pressure of the casting material injected into the casting mold.

12. The method for manufacturing a 3D structure using a casting mold made of water-soluble photocurable resin according to claim 1, characterized in that, The step of solidifying the casting material injected into the casting mold. It is performed in a chamber that creates a normal temperature environment or a high pressure environment.

13. The method for manufacturing a 3D structure using a casting mold made of water-soluble photocurable resin according to claim 1, characterized in that, The aqueous solution used in the step of dissolving and removing the casting mold is a neutral or alkaline aqueous solution in the pH range of 6 to 12.

14. The method for manufacturing a 3D structure using a casting mold made of water-soluble photocurable resin according to claim 13, characterized in that, The temperature of the aqueous solution is maintained in the range of 20℃ to 60℃.

15. The method for manufacturing a 3D structure using a casting mold made of water-soluble photocurable resin according to claim 1, characterized in that, In the step of immersing the casting mold in an aqueous solution to dissolve and remove the mold, Flow occurs in the aqueous solution in which the casting mold is immersed.

16. A water-soluble, light-curable resin composition comprising: The photocurable water-soluble oligomer contains 10–50 wt% of at least two epoxy or (meth)acrylate reactive groups for photocuring, and its main chain structure includes nitrogen bonds (-N-), ether bonds (-O-), -OH, -COOH, -NH-, -NH2, -N-CO-, M-OH (M represents a metal), and sodium (Na) bonds. + Salt, -SO3M + (where M is H, Na, or K) or N + X - (where X is any one or more of OH, Cl, or BF4); and The photocurable water-soluble monomer comprises 50–90 wt%, containing one or two epoxy or (meth)acrylate reactive groups for photocuring, and its main chain structure includes nitrogen bonds (-N-), ether bonds (-O-), -OH, -COOH, -NH-, -NH2, -N-CO-, M-OH (M represents a metal), and sodium (Na) bonds. + Salt, -SO3M + (where M is H, Na, or K) or N + X - (where X is any one or more of OH, Cl, or BF4) It also contains a photoinitiator, the amount of which is in the range of 1 to 10 wt% relative to the total weight of the resin composition after mixing the photocurable water-soluble oligomer and the photocurable water-soluble monomer.

17. The water-soluble photocurable resin composition according to claim 16, characterized in that, The photocurable water-soluble monomer is any one or a combination of two or more of ACMO (Acryloyl morpholine), DMAA (N,N-Dimethylacrylamide), HEAA (N-(2-Hydroxyethyl)acrylamide), MAANa (Sodium Methacrylate), or 3-Sulfopropyl acrylate potassium salt.

18. The water-soluble photocurable resin composition according to claim 16, characterized in that, The photoinitiator includes: Benzophenone derivatives, benzylketones, monomeric hydroxyl ketones, polymeric hydroxyl ketones, α-amino ketones, acyl phosphine oxides, metallocenes, benzoin ethers, benzilketals, α-hydroxyalkylphenones, and α-aminoalkylphenones are all examples of free radical initiators. Isopropyl thioxanthenones, arylsulphonium salts, and aryl iodonium salts are used as cationic initiators. At least one of them.

19. The water-soluble photocurable resin composition according to claim 16, characterized in that, It also includes water-soluble resins, whose main chain structure contains nitrogen bonds (-N-), ether bonds (-O-), -OH, -COOH, -NH-, -NH2, -N-CO-, M-OH (M represents metal), and sodium (Na) bonds. + Salt, -SO3M + (where M is H, Na, or K) or N + X - The resin composition contains one or more of the following: (where X is OH, Cl or BF4), but does not contain any photoreactive groups including epoxy or (meth)acrylate reactive groups, and is added in an amount ranging from 5 to 15 wt% relative to the total weight of the resin composition.

20. The water-soluble photocurable resin composition according to claim 19, characterized in that, The water-soluble resin is any one or a combination of two or more of polyvinyl alcohol (PVA), polyglycerin (PG), polyacrylamide (PAAM), polyvinylpyrrolidone (PVP), polyvinylamine hydrochloride (PVH), polymaleic acid, or polystyrene sulfonic acid.

21. The water-soluble photocurable resin composition according to claim 19, characterized in that, It also includes water-soluble fillers, which are in the form of water-soluble powders and have the physical property of being well soluble in water but completely insoluble in photocurable oligomers or monomers. The amount added is in the range of 10 to 20 wt% relative to the total weight of the resin composition.

22. The water-soluble photocurable resin composition according to claim 21, characterized in that, The water-soluble filler is any one or a combination of two or more of the following: sugar, salt, potassium chloride (KCl), boric acid (H3BO3), potassium carbonate (KHCO3), sodium carbonate (NaHCO3), ammonium carbonate (NH4HCO3), and calcium chloride (CaCl2).

23. The water-soluble photocurable resin composition according to claim 21, characterized in that, The water-soluble filler is contained in the resin composition in the form of a powder with an average particle size of less than 5 μm.

24. The water-soluble photocurable resin composition according to claim 16, characterized in that, The resin composition also includes other additives, which consist of one or more of pigments, defoamers, dispersants, polymerization inhibitors and silane additives, and the amount added is in the range of 0.5 to 2.0 wt% relative to the total weight of the resin composition.

25. The water-soluble photocurable resin composition according to claim 24, characterized in that, The pigment is black carbon.

26. The water-soluble photocurable resin composition according to claim 16, characterized in that, The water-soluble photocurable resin composition has a viscosity in the range of 100 to 20,000 cPs.

27. The water-soluble photocurable resin composition according to claim 16, characterized in that, The water-soluble photocurable resin composition has a secant modulus of 500 MPa or more after photocuring.

28. The water-soluble photocurable resin composition according to claim 16, characterized in that, The water-soluble photocurable resin composition has an elongation at break of more than 4% after photocuring.

29. The water-soluble photocurable resin composition according to claim 16, characterized in that, The water-soluble photocurable resin composition has a heat deflection temperature (HDT) of 70°C or higher after photocuring.

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