Curable composition for three-dimensional stereolithography, method for producing same, method for producing three-dimensional stereolithographic model, and method for producing dental restoration

Abstract

The present invention provides a curable composition for three-dimensional stereolithography, the curable composition being used in a vat photopolymerization method and containing 100 parts by mass of a polymerizable monomer component (A), 40 parts by mass to 400 parts by mass of an inorganic filler (B) that is composed of a single kind or plural kinds of inorganic particulate matter, and 0.01 part by mass to 5 parts by mass of a photopolymerization initiator (C), wherein: 80% or more of all primary particles that constitute the inorganic filler (B) have a particle diameter of 0.05 µm to 5.0 µm; and a sample, which is formed of this curable composition for three-dimensional stereolithography and has a thickness of 0.5 mm, has a transmittance of 1.00% to 50.00% with respect to activation light. The present invention also provides a method for producing this curable composition for three-dimensional stereolithography. The present invention also provides a method for producing a three-dimensional stereolithographic model and a method for producing a dental restoration, each using this curable composition for three-dimensional stereolithography.

Description

CURABLE COMPOSITION FOR 3D PHOTO-PRODUCTION AND ITS PRODUCTION METHOD, METHOD FOR PRODUCING 3D PHOTO-PRODUCED OBJECT, AND METHOD FOR PRODUCING DENTAL RESTORATION

[0001] The present disclosure relates to a curable composition for three-dimensional stereolithography and a method for producing the same, a method for producing a three-dimensional stereolithography object, and a method for producing a dental restoration.

[0002] The technology of forming a three-dimensional object by irradiating a photocurable composition (also called a photocurable resin or a photocurable resin composition) containing a polymerizable monomer and a photopolymerization initiator with light that activates the photopolymerization initiator (activating light) to harden the composition is known as a stereolithography method. There are several stereolithography methods, and among them, the liquid vat photopolymerization method is widely used because the equipment is relatively inexpensive and it can produce objects with smooth surfaces with high precision.

[0003] In the liquid vat photopolymerization method, a three-dimensional object is typically obtained as follows. First, the height direction of the three-dimensional object is digitized and ranked from three-dimensional shape data representing the shape of the three-dimensional object, and two-dimensional shape data representing the cross-sectional shape of the three-dimensional object at each ranked height is generated. Next, activating light is applied to a liquid photocurable composition held in a vat at a predetermined position determined based on the two-dimensional shape data, selectively curing the liquid photocurable composition present at that position to form a modeling layer having the cross-sectional shape. Furthermore, modeling layers having the cross-sectional shapes at each height are sequentially formed and stacked in the ranked order to obtain a laminate having a shape corresponding to the shape of the three-dimensional object. The laminate is then washed with an organic solvent, if necessary, and then subjected to secondary curing to obtain the desired object.

[0004] In the field of dentistry, dental restorations such as dentures and crown prostheses must be manufactured with high precision in unique shapes tailored to the oral conditions of individual patients. For this reason, the manufacture of dental restorations by stereolithography using liquid vat photopolymerization based on CAD (Computer Aided Design) data designed using digital data obtained by intraoral scanning, etc., is being considered.

[0005] Dental prostheses used in the oral cavity require not only high dimensional (shape) accuracy as described above, but also high mechanical strength sufficient to withstand the loads imposed by mastication. In this regard, when an inorganic filler is incorporated into a photocurable composition, polymerization shrinkage, which is one of the causes of reduced accuracy, can be reduced, and the mechanical strength and surface hardness of the cured product can be improved. For this reason, liquid vat photopolymerization using a photocurable composition containing an inorganic filler is considered suitable for stereolithography of dental prostheses, and curable compositions for three-dimensional stereolithography containing such inorganic fillers have also been proposed.

[0006] For example, Patent Document 1 discloses a composition for optical 3D modeling that exhibits excellent molding accuracy, mechanical properties, and transparency, and is particularly suitable for dental materials. The composition contains a polymerizable monomer (a), ultraviolet-absorbing inorganic particles (b), and a photopolymerization initiator (c). Patent Document 2 discloses a resin composition capable of producing a cured product (3D object) with excellent designability, the composition containing a light-transmitting resin and two or more types of light-transmitting particles with different refractive indices and Abbe numbers. Patent Document 3 discloses a resin composition for optical 3D modeling that can produce a 3D object with high strength, high elasticity, and excellent abrasion resistance. The composition contains a urethane-modified (meth)acrylic compound (a), a (meth)acrylamide compound (b), a photopolymerization initiator (c), and spherical inorganic particles (d) having an average particle size of 0.75 to 10 μm, the content of the spherical inorganic particles (d) being 50 to 400 parts by mass per 100 parts by mass of the total amount of the polymerizable monomers.

[0007] International Publication No. 2018 / 074380 JP 2020-180171 A JP 2022-41276 A Japanese Patent No. 3917204 A

[0008] Patent Documents 1 to 3 use compositions containing polymerizable monomers and inorganic fillers, which allows for the production of molded objects with excellent mechanical strength, elastic modulus, and abrasion resistance. However, the optical 3D modeling composition described in Patent Document 1 has low fluidity, which may limit the shape of the object that can be manufactured. Furthermore, the resin composition described in Patent Document 2 may experience sedimentation of the translucent particles (e.g., glass filler) contained in the composition when left stationary for a long period of time. Furthermore, it has been revealed that the stereolithography resin composition described in Patent Document 3 often causes fine cracks on the surface of the molded object that are difficult to detect visually (see FIG. 4). When a molded object having such fine cracks is used as a dental prosthesis, it may become a starting point for fracture of the dental prosthesis in the oral cavity, which is problematic.

[0009] Therefore, an object of the present disclosure is to provide a technology that enables the production of high-precision, high-strength three-dimensional objects without generating cracks on the surface when producing three-dimensional objects by photolithography using a liquid vat photopolymerization method using a curable composition for three-dimensional photolithography that contains a certain amount of inorganic filler to increase strength.

[0010] A first aspect of the present disclosure relates to a liquid tank photopolymerization method for producing a three-dimensional optically shaped object by irradiating a predetermined position of a liquid photocurable composition held in a tank with activating light (hereinafter also referred to as "specific activating light") containing light of a specific wavelength λ (nm) in the ultraviolet or visible light region to selectively cure the liquid photocurable composition present at that position, the method comprising: providing a curable composition for three-dimensional optical shaping used as the liquid photocurable composition, the curable composition comprising: 100 parts by mass of a polymerizable monomer component (A); 40 to 400 parts by mass of an inorganic filler (B) composed of one or more types of inorganic powder or particles; and 0.01 to 5 parts by mass of a photopolymerization initiator (C) having a function of initiating photopolymerization upon irradiation with the specific activating light; and in a particle size distribution of the inorganic filler (B) measured by a microscopy method using a scanning microscope, 80% or more of all primary particles constituting the inorganic filler (B) are particles with a particle diameter of 0.05 to 5.0 μm. The curable composition for three-dimensional stereolithography has a transmittance of 1.00 to 50.00 (%) to specific activating light, as measured on a 0.5 mm thick sample made of the curable composition for three-dimensional stereolithography.

[0011] The curable composition for three-dimensional optical shaping of the present disclosure contains 0.01 to 2.5 parts by mass of an activating light absorber (D) that has a function of absorbing specific activating light but does not have photopolymerization initiation ability, and the polymerizable monomer component (A) and the inorganic filler (B) are composed only of the polymerizable monomer component (A) and the inorganic filler (B), and the compositional ratio of these components is the same as that of the curable composition for three-dimensional optical shaping of the present disclosure. When a base composition is used, a measurement light beam containing light of the specific wavelength λ (nm), mainly composed of light within a range of λ±50 (nm) and exhibiting the maximum intensity within the range is measured using a goniophotometer, and the measurement light beam is measured based on the intensity of transmitted light in a specific emission angle direction, as determined by the following formula: Sc={(I ７０ +I ７５ +I ８０ ) / (I ０ ×3)}×100 (wherein, I ０ , I ７０ , I ７５ , and I ８０indicate the intensity of transmitted light in each direction at an emission angle of 0°, 70°, 75°, and 80°, respectively.) It is preferable that the light scattering index: Sc (%) determined by the above formula is 10 (%) or less (hereinafter, this form will also be referred to as the "specific blending form").

[0012] Furthermore, in the curable composition for three-dimensional optical fabrication according to the present disclosure, when the particle diameter of each particle constituting the inorganic filler (B) is x (nm) and pi is π, it is preferable that the total number of particles having a particle diameter x (nm) in the range of 0.7λ / π to 4λ / π (nm) in the particle size distribution of the inorganic filler (B) measured by a microscopy method using a scanning microscope accounts for 40% or more of the total number of particles constituting the inorganic filler (B).

[0013] In the specific blending mode, when the inorganic powder particles constituting the inorganic filler (B) are those consisting of an aggregate of a single type of inorganic particles having a refractive index at 25°C to the D line within the range of 1.500 to 1.550 as the specific inorganic powder particles (b1) and those consisting of an aggregate of a single type of inorganic particles having a refractive index outside the above range as the non-specific inorganic powder particles (b2), the inorganic filler (B) is either: (1) composed of a single type of specific inorganic powder particles (b1), or (2) composed of multiple types of specific inorganic powder particles (b1), and at least one of the multiple types of specific inorganic powder particles (b1) accounts for 10 mass% or more of the total mass of the inorganic filler (B), or (3) A filler (B) comprising a single or multiple specific inorganic powder or particles (b1): 90% by mass or more and less than 100% by mass, and a single or multiple non-specific inorganic powder or particles (b2): more than 0% by mass and less than 10% by mass, wherein at least one of the single or multiple specific inorganic powder or particles (b1) accounts for 10% by mass or more of the total mass of the inorganic filler (B), and the refractive index of the polymerizable monomer component (A) at 25°C with respect to the D line: n Ｍ is 1.490 to 1.550, and the refractive index of at least one specific inorganic powder or particle (b1) that accounts for 10% by mass or more of the inorganic filler (B) is Ｍ The refractive index where the difference between Ｆ When Ｆ and Ｍ Absolute value of the difference with: |nＦ -n Ｍ is preferably 0.035 or less.

[0014] A second aspect of the present disclosure is a method for producing a curable composition for three-dimensional optical modeling, comprising a mixing step of mixing 100 parts by mass of a polymerizable monomer component (A), 40 to 400 parts by mass of an inorganic filler (B) composed of a single type or multiple types of inorganic powder or particles, 0.01 to 5 parts by mass of a photopolymerization initiator (C) having a function of initiating photopolymerization upon irradiation with specific activating light, and 0.01 to 2.5 parts by mass of an activating light absorber (D) having a function of absorbing the specific activating light but not having photopolymerization initiation ability, wherein in the mixing step, the polymerizable monomer component (A) and the inorganic filler (B) satisfy the following conditions 1 to 4: Condition 1: When the particle diameter of each particle constituting the inorganic filler (B) is x (nm) and pi is π, in the particle size distribution of the inorganic filler (B) measured by a microscopy method using a scanning microscope, the total number of particles having a particle diameter x (nm) in the range of 0.7λ / π to 4λ / π (nm) is 40% or more of the total number of particles constituting the inorganic filler (B); Condition 2: Regarding the inorganic powder particles constituting the inorganic filler (B), when inorganic powder particles consisting of an aggregate of a single type of inorganic particles having a refractive index to the D line at 25°C in the range of 1.500 to 1.550 are defined as specific inorganic powder particles (b1) and inorganic powder particles consisting of an aggregate of a single type of inorganic particles having a refractive index outside the above range are defined as non-specific inorganic powder particles (b2), the inorganic filler (B) is either: (1) constituted by a single type of specific inorganic powder particles (b1), (2) Consisting of a plurality of types of specific inorganic powder and granules (b1), and at least one of the plurality of types of specific inorganic powder and granules (b1) accounts for 10 mass% or more of the total mass of the inorganic filler (B), or (3) Consisting of a single type or a plurality of types of specific inorganic powder and granules (b1): 90 mass% or more and less than 100 mass% and a single type or a plurality of types of non-specific inorganic powder and granules (b2): more than 0 mass% and less than 10 mass%, and at least one of the single type or a plurality of types of specific inorganic powder and granules (b1) accounts for 10 mass% or more of the total mass of the inorganic filler (B); Condition 3: Refractive index of the polymerizable monomer component (A) at 25°C to the D line: n Ｍis 1.490 to 1.550; Condition 4: Among the refractive indices of at least one specific inorganic powder or particle (b1) that accounts for 10% by mass or more of the inorganic filler (B), n Ｍ The refractive index where the difference between Ｆ When Ｆ and Ｍ Absolute value of the difference with: |n Ｆ -n Ｍ | is 0.035 or less.

[0015] In the method for producing a curable composition for three-dimensional stereolithography according to the present disclosure, a base composition consisting solely of the polymerizable monomer component (A) and the inorganic filler (B) that satisfy the above conditions 1 to 4 is separately prepared, the base composition consisting of a composition in which the compositional ratio of these components is the same as that of the curable composition for three-dimensional stereolithography that is the target of production; a measurement is performed using a goniophotometer that vertically irradiates a sample of the base composition with measurement light that contains light of the above specific wavelength: λ (nm), is mainly composed of light within a range of λ±50 (nm), and exhibits the maximum intensity within said range; and a measurement value is calculated based on the intensity of the transmitted light in a specific output angle direction obtained by the measurement using the following formula: Sc={(I ７０ +I ７５ +I ８０ ) / (I ０ ×3)}×100 (wherein, I ０ , I ７０ , I ７５ , and I ８０ indicates the intensity of transmitted light in each direction at an emission angle of 0°, 70°, 75°, and 80°, respectively.) It is preferable to use in the mixing step a polymerizable monomer component (A) and an inorganic filler (B) for which it has been confirmed that the light-scattering index: Sc (%) determined by

[0016] A third aspect of the present disclosure is a method for producing a three-dimensional optically shaped object by irradiating a predetermined position of a liquid photocurable composition held in a tank with specific activating light to selectively cure the liquid photocurable composition present at that position, the method comprising: a molding step of: digitizing and ranking the height direction of the three-dimensional object from three-dimensional shape data representing the shape of the three-dimensional object and generating two-dimensional shape data representing the cross-sectional shape of the three-dimensional object at each ranked height; irradiating the liquid photocurable composition held in the tank with specific activating light at a predetermined position determined based on the two-dimensional shape data to selectively and primarily cure the liquid photocurable composition present at that position to form a modeling layer having the cross-sectional shape; and sequentially forming and stacking modeling layers having the cross-sectional shapes at each height in accordance with the ranked order to obtain a laminate having a shape corresponding to the shape of the three-dimensional object; a cleaning step of washing the laminate obtained in the molding step with an organic solvent; and a secondary curing step of secondary curing the laminate washed in the washing step by additionally irradiating the laminate with activating light, subjecting it to heat treatment, or both; The method for producing a three-dimensional optically shaped object includes the steps of:

[0017] A fourth aspect of the present disclosure is a method for manufacturing a dental restoration, including manufacturing a dental restoration by the method for manufacturing a three-dimensional optically shaped object of the present disclosure.

[0018] The curable composition for three-dimensional optical modeling according to the present disclosure makes it possible to produce a three-dimensional optically modeled object that has excellent mechanical strength and good modeling accuracy, while suppressing a decrease in fluidity and sedimentation of inorganic fillers and preventing cracks from occurring on the surface of the cured object.

[0019] 1 is a diagram showing the state of the surface of the three-dimensional stereolithography object obtained in Example 7, observed with an optical microscope (magnification 50x); FIG. 2 is a diagram showing the state of the surface of the three-dimensional stereolithography object obtained in Example 11, observed with an optical microscope (magnification 50x); FIG. 3 is a diagram showing the state of the surface of the three-dimensional stereolithography object obtained in Comparative Example 1, observed with an optical microscope (magnification 50x); FIG. 4 is a diagram showing the state of the surface of the three-dimensional stereolithography object obtained in Comparative Example 9, observed with an optical microscope (magnification 50x); FIG. 5 is a graph showing the wavelength distribution (relative spectral distribution) of measurement light used when measuring the light scattering index Sc in the examples and comparative examples.

[0020] As described above, photocurable compositions containing a certain amount of inorganic filler to improve the mechanical strength and surface hardness of the cured product can suffer from problems such as reduced fluidity and particle settling during storage. Furthermore, when a model is produced by a liquid tank photopolymerization method using the stereolithography resin composition described in Patent Document 3, fine cracks that are difficult to detect visually often occur on the surface of the model (although this is not recognized in Patent Document 3).

[0021] The present inventors have discovered that these problems can be solved by controlling the particle size of the particles constituting the inorganic filler to be blended and by setting the transmittance of activating light in the composition before curing to a specific range, and have completed the invention of the present disclosure.

[0022] The following describes the presently disclosed curable composition for three-dimensional stereolithography (hereinafter also simply referred to as the "curable composition for stereolithography") and its manufacturing method, a method for manufacturing a three-dimensional stereolithography object, and a method for manufacturing a dental restoration. Unless otherwise specified, the expression "x to y" using the numerical values ​​x and y means "x or more and y or less." In such expressions, when a unit is assigned only to the numerical value y, the unit also applies to the numerical value x. Furthermore, in this specification, the term "(meth)acrylic" refers to both "acrylic" and "methacrylic." Similarly, the term "(meth)acrylate" refers to both "acrylate" and "methacrylate," and the term "(meth)acryloyl" refers to both "acryloyl" and "methacryloyl."

[0023] 1. Curable Composition for Stereolithography The curable composition for stereolithography disclosed herein is a composition used as a liquid photocurable composition when producing a three-dimensional stereolithography object using a liquid vat photopolymerization method, i.e., a curable composition for three-dimensional stereolithography using a liquid vat photopolymerization method.

[0024] Here, the liquid vat photopolymerization method refers to a process that includes the steps of: digitizing and ranking the height direction of a three-dimensional object from three-dimensional shape data representing the shape of the three-dimensional object; generating two-dimensional shape data representing the cross-sectional shape of the three-dimensional object at each ranked height; irradiating a liquid photocurable composition held in a vat with activating light at predetermined positions determined based on the two-dimensional shape data, thereby selectively (primarily) curing the liquid photocurable composition present at that position to form a modeling layer having the cross-sectional shape; and sequentially forming and stacking modeling layers having the cross-sectional shapes at each height in accordance with the ranking order to obtain a laminate having a shape corresponding to the shape of the three-dimensional object (hereinafter also referred to as the "molding process"). If necessary, a cleaning process using an organic solvent (hereinafter also referred to as the "cleaning process") or a secondary curing process (hereinafter also referred to as the "secondary curing process") is performed to obtain a three-dimensional photo-fabricated object having a shape corresponding to the shape of the three-dimensional object.

[0025] The curable composition for stereolithography disclosed herein contains 100 parts by mass of a polymerizable monomer component (A), 40 to 400 parts by mass of an inorganic filler (B) composed of one or more types of inorganic powder or particles, and 0.01 to 5 parts by mass of a photopolymerization initiator (C) having the function of initiating photopolymerization upon irradiation with specific activating light, wherein, in the particle size distribution of the inorganic filler (B) measured by a microscopy method using a scanning microscope, 80% or more of all particles constituting the inorganic filler (B) have a particle diameter of 0.05 to 5.0 μm, and the transmittance to the specific activating light measured on a 0.5 mm thick sample made of the curable composition for stereolithography is 1.00 to 50.00 (%).

[0026] By containing the polymerizable monomer component (A) and the inorganic filler (B) in the above-mentioned ratio, it is possible to increase the strength and surface hardness of the cured body that will become the three-dimensional optically shaped object that is the target of production. Furthermore, by having the particles constituting the inorganic filler (B) satisfy the above-mentioned particle size conditions, it is possible to suppress an increase in viscosity of the composition and the risk of particle settling during storage.

[0027] Here, the fact that 80% or more of all primary particles constituting the inorganic filler (B) have a particle diameter of 0.05 to 5.0 μm can be confirmed by the particle size distribution of the inorganic filler (B) measured by microscopy using a scanning electron microscope. That is, the inorganic filler (B) used to prepare the curable composition for stereolithography of the present disclosure is photographed with a scanning electron microscope, and the number of all primary particles (50 or more) observed within a unit field of view of the photograph: n (numbers) is counted, and the primary particle diameter (maximum diameter): X of each particle is measured. ｉ By measuring the particle size distribution of all primary particles, the particle size distribution can be determined. ｉ where i is a natural number from 1 to n and represents the number of each measured primary particle. The average (primary) particle diameter: X (nm) is the sum of the particle diameters of all measured primary particles (primary particles with i = 1 to n): ΣX ｉ Using the formula: X = ΣX ｉ / n.

[0028] The inorganic filler (B) may be contained as aggregated particles formed by aggregation of primary particles. The particle size distribution of the aggregated particles is not particularly limited as long as the particle size distribution of the primary particles satisfies the above-described conditions. However, in order to suppress sedimentation of the inorganic filler (B), it is preferable that the number of aggregated particles of the inorganic filler (B) contained in the curable composition for stereolithography of the present disclosure be small. The average particle size of the inorganic filler (B) including aggregated particles of primary particles measured by a laser diffraction / scattering method is typically 0.05 to 100 μm, preferably 0.05 to 50 μm, and more preferably 0.05 to 30 μm.

[0029] Furthermore, in the curable composition for stereolithography according to the present disclosure, the transmittance of a specific activating light measured on a 0.5 mm thick sample made of the curable composition for stereolithography is 1.00 to 50.00 (%), which makes it possible to reduce the risk of cracks occurring on the surface of the cured product.

[0030] Although the reason for the occurrence of cracks on the surface of a cured body is generally unclear, the present inventors have confirmed that cracks occur when an uncured curable composition attached to the surface of a laminate obtained using a stereolithography device is washed with an organic solvent after the laminate is obtained. Furthermore, since the inorganic filler contained in the stereolithography curable composition contains many particles having a particle size that causes scattering (specifically, Mie scattering or Reyleigh scattering) when irradiated with activating light, weak activating light (sideward scattered light) is generated that is scattered off the optical axis of the irradiation spot, resulting in an extremely shallow curing depth and the formation of regions with relatively low crosslink density between the layers of the laminate (hereinafter also referred to as "interlayer low crosslink density regions"). This is thought to be one of the causes of crack occurrence. Specifically, when an organic solvent penetrates into the interlayer low crosslink density regions during washing, the regions swell, widening the molecular distances between the polymer chains constituting the molded body and temporarily reducing its strength. It is thought that this is due to internal stress remaining in the molded body during the molding process, which destroys the weakened portions, resulting in cracks in the regions.

[0031] It is unclear why cracks on the surface of the cured product are not recognized in Patent Document 3, but when the present inventors conducted a follow-up experiment on the stereolithography resin composition described in Patent Document 3, the stereolithography resin composition in which cracks were observed on the surface of the cured product had low transmittance of activating light. From this, it is believed that the occurrence of cracks was probably overlooked in Patent Document 3.

[0032] In the curable composition for stereolithography disclosed herein, the transmittance for specific activating light is set within the above-mentioned range, thereby reducing the effects of scattering and the risk of cracking on the surface of the cured product. To more reliably prevent cracking and enable the production of three-dimensional stereolithography objects with high precision, the curable composition for stereolithography disclosed herein preferably has the above-mentioned specific blending configuration. This specific blending configuration is characterized by containing a polymerizable monomer component, an inorganic filler with a particle size that reduces the risk of viscosity increase and sedimentation, a photopolymerization initiator, and an activating light absorber, each in a predetermined ratio, and by using a combination of the polymerizable monomer component and the inorganic filler that results in a light scattering index Sc within a specific range. This specific blending configuration suppresses light scattering by the inorganic filler in directions off the optical axis and sets the transmittance for specific activating light (before curing) within a specific range, thereby preventing cracking and, in some cases, further improving modeling accuracy.

[0033] That is, the specific blending embodiment is a homogeneous composition containing 100 parts by mass of a polymerizable monomer component (A), 40 to 400 parts by mass of an inorganic filler (B) composed of a single type or multiple types of inorganic powder and granules, 0.01 to 5 parts by mass of a photopolymerization initiator (C) having the function of initiating photopolymerization upon irradiation with specific activating light, and 0.01 to 2.5 parts by mass of an activating light absorber (D) having the function of absorbing the specific activating light but not having photopolymerization initiation ability, and by satisfying the following conditions [I] and [II], the effects of increased strength, prevention of cracking, and increased precision are obtained.

[0034] [I] The transmittance of a 0.5 mm thick sample made of the curable composition for stereolithography to specific activating light is 1.00 to 50.00 (%).

[0035] [II] When a composition consisting of only a polymerizable monomer component (A) and an inorganic filler (B), in which the composition ratio of these components is the same as that of a curable composition for stereolithography, is used as a base composition, a measurement light beam containing a specific wavelength: λ (nm), containing light having a main component within a range of λ±50 (nm) and exhibiting the maximum intensity within said range is irradiated perpendicularly to a 0.5 mm-thick sample of the base composition. The measurement light beam is measured using a goniophotometer, and the measurement light beam is calculated based on the intensity of transmitted light in a specific emission angle direction, using the formula: Sc={(I ７０ +I ７５ +I ８０ ) / (I ０ × 3) × 100, the light scattering index: Sc (%) is 10 (%) or less. ０ , I ７０ , I ７５ , and I ８０ and indicate the intensity of transmitted light in the directions where the emission angles are 0°, 70°, 75°, and 80°, respectively.

[0036] If a curable composition for stereolithography with a specific formulation does not satisfy the above-mentioned conditions regarding the components and their blending ratios, and does not satisfy the condition regarding the transmittance to the specific activating light, it becomes difficult to produce a high-strength three-dimensional object with high precision. If condition [I] is not satisfied, for example, if the transmittance is less than 1%, sufficient cure depth cannot be obtained, resulting in the formation of many interlayer low-crosslink density regions and significant cracking. On the other hand, with a composition containing an inorganic filler (B) and an activating light absorber (D), it is extremely difficult to achieve a system with the transmittance exceeding 50% while maintaining high modeling precision.

[0037] These conditions define the conditions that must be satisfied by the polymerizable monomer component (A), inorganic filler (B), photopolymerization initiator (C), and activating light absorber (D) that constitute the specific formulation. The transmittance defined by condition [I] corresponds to the "transmittance of the specific activating light in the curable composition for stereolithography of the specific formulation before photocuring" and serves as an indicator of the depth of cure when the curable composition for stereolithography of the present disclosure is irradiated with the specific activating light. The Sc defined by condition [II] serves as an indicator of the "scattering state of light when the curable composition for stereolithography of the present disclosure is irradiated with the specific activating light," specifically, the state of side-scattered light, and ultimately the extent of the interlayer low crosslink density region formed thereby. These cure depths and the state of side-scattered light are important for the manifestation of the effects of the curable composition for stereolithography of the present disclosure and are determined by the combination of the components used. However, because the physical properties of each component affect the transmittance defined by condition [I] and the Sc defined by condition [II] in a wide variety of ways, it is virtually impossible to directly define a specific combination of substances that satisfies these conditions. Therefore, in the specific formulation, components (A), (B), (C), and (D) are defined as satisfying conditions [I] and [II] simultaneously, and in the case of a curable composition for stereolithography that does not contain component (D), components (A), (B), and (C) are defined as satisfying conditions [I] and [II] simultaneously. The curable composition for stereolithography of the present disclosure includes a composition obtained by the method for producing a curable composition for stereolithography of the present disclosure, which will be described later.

[0038] As described above, satisfying conditions [I] and [II] is extremely important from the viewpoint of preventing cracks. Therefore, these conditions will be explained first, and then the components and their compounding ratios of the curable composition for stereolithography of the present disclosure will be explained.

[0039] 1-1. Regarding Condition [I]: The curable composition for stereolithography of the present disclosure contains a photopolymerization initiator, regardless of whether it has a specific formulation, and therefore there is a concern that curing may proceed due to light irradiation during measurement. In this regard, by using a transmittance measurement method using a color difference meter as described below, it is possible to measure the transmittance of the specific activating light before curing proceeds.

[0040] The transmittance of the curable composition for stereolithography of the present disclosure to a specific activating light can be measured as follows. First, a resin mold (25 mm x 25 mm x 0.5 mm thick) is filled with the curable composition for stereolithography of the present disclosure, and then a 0.5 mm-thick measurement sample is prepared by pressing the top and bottom surfaces of the mold with glass slides to reduce the thickness to 0.5 mm and then removing the glass slide. Next, this measurement sample is placed in a color difference meter (e.g., a spectrophotometer SE7700 manufactured by Nippon Denshoku Industries Co., Ltd.), and the transmittance of the activating light (e.g., 405 nm wavelength light or 385 nm wavelength light) is measured by transmission measurement using a halogen lamp (measurement wavelength: 380 to 780 nm).

[0041] As mentioned above, if the transmittance measured in this manner is lower than the lower limit of 1.00%, sufficient curing depth cannot be achieved, making stereolithography difficult. Even if stereolithography is possible, cracks are likely to occur in the molded object. Furthermore, in systems containing 40 parts by mass or more of inorganic filler per 100 parts by mass of polymerizable monomer components and a photopolymerization initiator in an amount that allows curing by stereolithography, it is difficult to achieve a transmittance significantly exceeding the upper limit of 50.00%. Even within the achievable transmittance range, excessive irradiation with specific activating light can cause excessive curing reactions, resulting in molded objects with shapes completely different from those represented by CAD data. From the perspective of preventing cracking and maintaining the shape of the molded object, the transmittance is preferably 2.00 to 30.00%, and more preferably 5.00 to 20.00%.

[0042] The transmittance tends to be higher as the light transmittance of the polymerizable monomer component and the inorganic filler themselves is higher, and as the difference in refractive index between them is smaller, and when the light transmittances of the two are different, it is affected by the blending ratio of the two. Since the transmittance of the polymerizable monomer component is generally much higher than 5.00%, as long as the blending amount of the inorganic filler is within the specified range, by using an inorganic filler that has light transmittance and reducing the difference in refractive index between the two, it is not only possible to make the transmittance 1.00% or more, but also possible to make it 5.00% or more.

[0043] 1-2. Regarding Condition [II] It is generally known that when light strikes fine particles with a particle size suitable for a curable composition for stereolithography, i.e., fine particles with a particle size of 0.05 to 5.0 μm, phenomena such as light blocking, diffraction, Mie scattering, and Rayleigh scattering occur. Among these, when Mie scattering and / or Rayleigh scattering occurs, the scattered light spreads not only forward but also to the sides and rear. Furthermore, the scattered light that spreads to the sides (sideward scattered light) is thought to reduce the transmittance of the specific activating light in Condition [I], causing cracks and further reducing the molding accuracy of the molded body.

[0044] The spread and intensity of side-scattered light, i.e., the intensity distribution of scattered light with respect to the scattering direction (angle), are affected not only by the particle size of the particles but also by the refractive index of the particles and the polymerizable monomer component (which serves as a dispersion medium) surrounding the particles. However, in a dispersion system in which particles are dispersed in a polymerizable monomer component as a powder with a particle size distribution, particularly in a dispersion system composed of multiple types of particles with different refractive indices, it is virtually impossible to grasp the scattering behavior of each particle, and it is necessary to grasp the scattering behavior of the entire system. Furthermore, when the curable composition for stereolithography disclosed herein is used to manufacture dental prostheses, the higher the average "intensity of activation light scattered sideways" of the entire system, the lower the modeling accuracy and the further the transmittance of the specific activation light, which can lead to concerns about the occurrence of cracks due to the expansion of low-crosslink density regions between layers. For these reasons, in the present disclosure, the combination of polymerizable monomer components and inorganic fillers used in the curable composition for stereolithography of the present disclosure is indirectly defined by using the light scattering index: Sc (%) defined by the above formula in the base composition (which is a homogeneous base composition consisting only of polymerizable monomer components and inorganic fillers in a predetermined quantitative ratio) that serves as the base of the curable composition for stereolithography of the present disclosure.

[0045] Measurement of refracted light passing through a sample using a goniophotometer is used to evaluate the optical properties of materials that require light diffusion, such as lighting fixture covers and projector screens. In the dental field, as described in Patent Document 4, it is also used as an index to evaluate the optical texture of tooth filling and restorative materials, specifically, to determine the diffusion index D.

[0046] In the present disclosure, measurements using a goniophotometer to determine the light-scattering index Sc can be performed as follows. First, a portion of the base composition (for raw material) prepared during the preparation process of the curable composition for stereolithography of the present disclosure is sampled, or a base composition (for measurement) prepared by separate preparation is used to prepare a measurement sample with a thickness of 0.5 mm in the same manner as in transmittance measurements. Next, the measurement sample is placed in a three-dimensional goniophotometer (e.g., GP-200, manufactured by Murakami Color Research Laboratory Co., Ltd.), and measurement light containing light of a specific wavelength λ (nm), primarily composed of light within a range of λ±50 (nm) and exhibiting maximum intensity within that range is irradiated perpendicularly onto the measurement sample, and the intensity of the transmitted light at each emission angle is measured. If the light emitted from the light source (capable of emitting light containing light of wavelength λ) attached to the three-dimensional goniophotometer does not satisfy the above-mentioned conditions for the measurement light, an interference filter (e.g., for the GP-200, manufactured by Murakami Color Research Laboratory Co., Ltd.) can be used to generate measurement light that satisfies the above-mentioned conditions. In addition, the fact that light within the range of λ±50 (nm) is the main component means that in the spectrum showing the wavelength distribution (relative spectral distribution) of the measurement light, the integrated value of the intensity of light with wavelengths of λ±50 (nm) is 90% or more of the integrated value of the intensity of the entire measurement light.

[0047] When the light-scattering index Sc of the base composition exceeds 10%, the formation of interlayer low-crosslink density regions that cause cracking due to side-scattered light is unavoidable. From the viewpoint of preventing cracking and improving molding accuracy, the light-scattering index Sc of the base composition is preferably 5.0% or less, and more preferably 3.0% or less. The lower the light-scattering index Sc, the better, with the lower limit being 0.0%.

[0048] The light-scattering index Sc of the base composition is affected by the blending ratio of the polymerizable monomer component and the inorganic filler. When the blending ratio is constant, however, it can be controlled to some extent by adjusting the particle size distribution of the inorganic filler, the refractive index (or type) of the particles constituting the inorganic filler, and the refractive index of the entire polymerizable monomer component.

[0049] For example, regarding particle size, there is known a parameter called "particle size parameter: α" which is an index of the scattering of light caused by particles and the scattering intensity. This particle size parameter α is calculated by dividing the wavelength (nm) of incident light by λ ０ When the ratio of the circumference of a circle to its circumference is π and the particle diameter of the inorganic particles is x (nm), the formula: α=(π×x) / λ ０ When particles are transparent to incident light, diffraction occurs when the particle size parameter α exceeds 10, and Mie scattering or Reyleigh scattering occurs when the particle size parameter α is 10 or less. When a laser beam with a wavelength of 405 nm, which is the most common activation light in the liquid tank photopolymerization method, is used, x = α λ ０ From the relationship of / π, the particle diameter x at which α = 10 is 1290 nm = 1.29 μm, and when a laser beam with a wavelength of 385 nm is used, the particle diameter x at which α = 10 is 1226 nm = 1.23 μm. Since many dental inorganic fillers have particle diameters smaller than this value, the above-mentioned scattering occurs, and cracks are likely to occur.

[0050] According to the studies of the present inventors, even when Mie scattering or Reyleigh scattering occurs, the light-scattering index Sc tends to decrease as the proportion of particles whose particle size parameter α is in the range of 0.7 to 4 in the particle size distribution measured by microscopy using a scanning microscope, that is, particles satisfying the relationship x = 0.7 × (λ / π) to 4 × (λ / π) (when the wavelength of the activating light is 405 nm, x = 90 to 514 nm, and when the wavelength of the activating light is 385 nm, x = 86 to 490 nm), increases. For the reason that it becomes easier to keep the light-scattering index Sc at 10% or less, it is preferable that the inorganic filler (B) used satisfies the following condition 1:

[0051] Condition 1: When the particle diameter of each particle constituting the inorganic filler (B) is x (nm) and pi is π, in the particle size distribution of the inorganic filler (B) measured by a microscopy method using a scanning microscope, the total number of particles having a particle diameter x (nm) in the range of 0.7λ / π to 4λ / π (nm) accounts for 40% or more, preferably 60% or more, and more preferably 80% or more of the total number of particles constituting the inorganic filler (B).

[0052] Furthermore, for the reason that condition [II] is more easily satisfied, in the particle size distribution measured by a microscopy method using a scanning microscope, the proportion of particles having a particle diameter in which the particle diameter parameter α is in the range of 1.0 to 3.0 (129 to 386 nm when the wavelength of the activating light is 405 nm) in the inorganic filler (B) is preferably 50% or more, more preferably 60% or more, and the proportion of particles having a particle diameter in which the particle diameter parameter α is in the range of 1.8 to 2.8 (231 to 360 nm when the wavelength of the activating light is 405 nm) is preferably 45% or more, more preferably 50% or more.

[0053] In addition, since commonly used stereolithography devices (3D printers) use a light source with an activation light wavelength (peak wavelength) of 380 to 420 nm, in order to simultaneously satisfy conditions [I] and [II], in the particle size distribution measured by microscopy using a scanning microscope, the total number of particles having a particle diameter in the range of 85 to 535 nm is preferably 40% or more of the total number of particles constituting the inorganic filler (B), more preferably 60% or more, and even more preferably 80% or more. A more preferred particle diameter range is 121 to 400 nm, and an even more preferred particle diameter range is 218 to 375 nm. In other words, in the particle size distribution measured by microscopy using a scanning microscope, it is most preferable that the total number of particles having a particle diameter in the range of 218 to 375 nm is 80% or more of the total number of particles constituting the inorganic filler (B).

[0054] Furthermore, the smaller the difference between the refractive index of the particles and the refractive index of the polymerizable monomer component, the smaller the light scattering index Sc tends to be. Considering the refractive index of the inorganic filler and the polymerizable monomer component used in dentistry, it is preferable to adopt a combination of the inorganic filler and the polymerizable monomer component that satisfies the following conditions 2 to 4.

[0055] Condition 2: With regard to the inorganic powder particles constituting the inorganic filler (B), when inorganic powder particles consisting of an aggregate of a single type of inorganic particles having a refractive index at 25°C to the (sodium) D line within the range of 1.500 to 1.550 are defined as specific inorganic powder particles (b1), and inorganic powder particles consisting of an aggregate of a single type of inorganic particles having a refractive index outside the above range are defined as non-specific inorganic powder particles (b2), the inorganic filler (B) is either: (1) composed of a single type of specific inorganic powder particles (b1), or (2) composed of multiple types of specific inorganic powder particles (b1), and at least one of the multiple types of specific inorganic powder particles (b1) accounts for 10 mass% or more of the total mass of the inorganic filler (B), or (3) The inorganic filler (B) is composed of a single or multiple types of specific inorganic powder or particles (b1): 90% by mass or more and less than 100% by mass, and a single or multiple types of non-specific inorganic powder or particles (b2): more than 0% by mass and less than 10% by mass, and at least one of the single or multiple types of specific inorganic powder or particles (b1) accounts for 10% by mass or more of the total mass of the inorganic filler (B).

[0056] Condition 3: refractive index of polymerizable monomer component (A) at 25°C with respect to D line: n Ｍ is 1.490 to 1.550.

[0057] Condition 4: Among the refractive indices of at least one specific inorganic powder or particle (b1) that accounts for 10% by mass or more of the inorganic filler (B), n Ｍ The refractive index where the difference between Ｆ When Ｆ and Ｍ Absolute value of the difference with: |n Ｆ -n Ｍ | is less than or equal to 0.035.

[0058] Above |n Ｆ -n ＭWhen | increases, the refraction of the activating light at the interface between the inorganic particles and the polymerizable monomer increases, the intensity of the side scattered light increases, and the light scattering index Sc tends to increase, and when the proportion of particles whose particle diameter is much smaller than the wavelength of the activating light increases, Rayleigh scattering is more likely to occur and the light scattering index Sc tends to increase. Conversely, when the proportion of particles whose particle diameter is much larger than the wavelength of the activating light increases, the frequency with which the activating light collides with the inorganic particles increases significantly, and the light scattering index Sc tends to increase.

[0059] The refractive index of the inorganic powder or particle composed of a single material and the refractive index of the polymerizable monomer component at 25° C. with respect to the D line can be measured as follows.

[0060] That is, the refractive index of the polymerizable monomer component can be measured using an Abbe refractometer (for example, Digital Abbe refractometer DR-A1-PLUS manufactured by Atago Co., Ltd.) by placing the prepared monomer composition on a prism, looking into the sample through an eyepiece, and reading the value on the display when the boundary line and the cross line intersect (this value is the refractive index). The refractive index of the inorganic powder or granule can be determined by mixing toluene or ethanol with bromonaphthalene to prepare solutions with refractive indices varying in increments of 0.001, mixing each inorganic powder or granule with each solution with a different refractive index, shaking the mixture, and determining the refractive index of the solution that appears most transparent as the refractive index of the inorganic powder or granule.

[0061] 1-3. Ingredients of the curable composition for stereolithography and their blending ratios, etc. <Polymerizable monomer component> As the polymerizable monomer component, any radically polymerizable monomer (monomer) can be used without particular limitation. Among radically polymerizable monomers, it is preferable to use a (meth)acrylate monomer because it has a fast curing rate and the strength of the resulting molded object is excellent.

[0062] The (meth)acrylate monomer may be a monofunctional (meth)acrylate, a bifunctional (meth)acrylate, or a trifunctional or higher polyfunctional (meth)acrylate, but in order to produce a stronger shaped object, it is preferable that 50% by mass or more, and preferably 80% by mass or more, of the total mass of all radically polymerizable monomers be bifunctional or higher polyfunctional (meth)acrylates.The proportion of bifunctional or higher polyfunctional (meth)acrylates is more preferably 95% by mass or more.

[0063] Suitable difunctional or higher polyfunctional (meth)acrylates include (meth)acrylates containing a bisphenol A skeleton, such as 2,2'-bis{4-[3-(meth)acryloyloxy-2-hydroxypropoxy]phenyl}propane, 2,2'-bis[4-(meth)acryloyloxyphenyl]propane, and 2,2'-bis[4-(meth)acryloyloxypolyethoxyphenyl]propane; ethylene glycol (meth)acrylates, such as triethylene glycol dimethacrylate and ethylene glycol dimethacrylate; acrylates; aliphatic di(meth)acrylates such as 1,3-propanediol di(meth)acrylate and 1,9-nonanediol dimethacrylate; urethane group-containing (meth)acrylates such as 1,6-bis(methacryloyloxy-2-ethoxycarbonylamino)-2,2,4-trimethylhexane; trifunctional (meth)acrylates such as trimethylolpropane trimethacrylate; and isocyanate skeleton-containing (meth)acrylates such as tris(2-methacryloyloxyethyl)isocyanurate. Among these, 2,2'-bis[4-(meth)acryloyloxyphenyl]propane, 2,2'-bis[4-(meth)acryloyloxypolyethoxyphenyl]propane, triethylene glycol dimethacrylate, tris(2-methacryloyloxyethyl)isocyanurate, etc. are preferred because of their low viscosity and high strength.

[0064] Furthermore, examples of monofunctional (meth)acrylates suitable for use in combination with difunctional or higher polyfunctional (meth)acrylates include hydroxyethyl methacrylate, methyl (meth)acrylate, ethyl (meth)acrylate, isopropyl (meth)acrylate, hydroxyethyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, and glycidyl (meth)acrylate.

[0065] These radical polymerizable monomers may be used alone or in combination of two or more.

[0066] <Inorganic Filler> In order to increase the mechanical strength, such as rigidity, of the resulting shaped object, the curable composition for stereolithography according to the present disclosure contains 40 to 400 parts by mass of an inorganic filler composed of a single type or multiple types of inorganic powder or particles per 100 parts by mass of the polymerizable monomer component. If the content of the inorganic filler is too high, the viscosity of the composition will be too high. On the other hand, if the content of the inorganic filler is too low, the mechanical strength will be insufficient. For this reason, the content of the inorganic filler is preferably 50 to 350 parts by mass, more preferably 60 to 300 parts by mass, per 100 parts by mass of the polymerizable monomer component.

[0067] Furthermore, as described above, from the viewpoint of suppressing an increase in viscosity of the composition and suppressing sedimentation, the inorganic filler must contain 80% or more particles having a particle diameter in the range of 0.05 to 5.0 μm in the particle size distribution of the inorganic filler measured by a microscopy method using a scanning microscope, and the proportion of particles having a particle diameter in this range is preferably 90% or more, and more preferably 95% or more. Furthermore, because viscosity increase can be further suppressed, the lower limit of the particle diameter of particles accounting for 80% or more of the inorganic filler is preferably 0.08 μm, and more preferably 0.1 μm. Because sedimentation can be further suppressed, the upper limit of the particle diameter of particles accounting for 80% or more of the inorganic filler is preferably 2.0 μm, and more preferably 1.0 μm.

[0068] As the inorganic filler, inorganic powders and granules used as inorganic fillers in dental restorative materials can be used without any particular restrictions, provided that they satisfy the above-mentioned condition [I] and, in combination with the polymerizable monomer component, also satisfy the above-mentioned condition [II]. Suitable inorganic powders and granules include powders and granules made of metals (simple substances); powders and granules made of metal oxides or metal composite oxides; powders and granules made of metal salts such as metal fluorides, carbonates, sulfates, silicates, hydroxides, chlorides, sulfites, and phosphates; and mixtures of these powders and granules. Particularly suitable constituent materials of the inorganic filler include metal oxides such as amorphous silica, quartz, alumina, zirconia, barium oxide, yttrium oxide, lanthanum oxide, and ytterbium oxide; silica-based composite oxides such as silica-zirconia, silica-titania, silica-titania-barium oxide, and silica-titania-zirconia; glasses such as borosilicate glass, aluminosilicate glass, and fluoroaluminosilicate glass; metal fluorides such as barium fluoride, strontium fluoride, yttrium fluoride, lanthanum fluoride, and ytterbium fluoride; inorganic carbonates such as calcium carbonate, magnesium carbonate, strontium carbonate, and barium carbonate; and metal sulfates such as magnesium sulfate and barium sulfate. These inorganic fillers may be used in combination of multiple types of different materials, or in combination of multiple types with different particle sizes.

[0069] Among these, amorphous silica, silica-zirconia, silica-titania, silica-titania-barium oxide, silica-titania-zirconia, borosilicate glass, aluminosilicate glass, or fluoroaluminosilicate glass is preferably used because it is easy to satisfy the above condition [II]. Furthermore, from the viewpoint of the abrasion resistance of the cured body, silica-zirconia is more preferably used.

[0070] Furthermore, the inorganic filler can also be compounded as a so-called organic-inorganic composite filler.

[0071] It is desirable to treat the inorganic filler with any surface treatment agent, such as a silane coupling agent, to improve compatibility with the polymerizable monomer component and improve mechanical strength and water resistance. The surface treatment may be performed by a known method. Examples of silane coupling agents include methyl trimoxysilane, methyl triethoxysilane, methyl trichlorosilane, dimethyl dichlorosilane, trimethyl chlorosilane, vinyl trichlorosilane, vinyl triethoxysilane, vinyl tris(β-methoxyethoxy)silane, γ-methacryloyloxypropyl trimethoxysilane, methacryloxyoctyl-8-trimethoxysilane, γ-chloropropyl trimethoxysilane, γ-glycidoxypropyl methoxysilane, and hexamethyldisilazane.

[0072] When producing dental restorations, it is preferable to use particles of silica-zirconia, silica-titania, silica-titania-barium oxide, silica-titania-zirconia, etc., because they have strong X-ray contrast properties. From the viewpoint of the abrasion resistance of the cured product, it is most preferable to use silica-zirconia particles.

[0073] <Photopolymerization Initiator> The photopolymerization initiator must have the function of generating radicals and radically polymerizing the polymerizable monomer component when exposed to specific activation light, including light of a specific wavelength λ (nm) in the ultraviolet or visible light range, irradiated from a light source installed in the stereolithography device. In other words, the photopolymerization initiator must absorb light of a specific wavelength λ (nm) to generate radicals. The specific wavelength λ, as long as it is in the ultraviolet or visible light range, may be appropriately determined depending on the wavelength of the activation light used in the stereolithography device. Examples of general-purpose stereolithography devices include SLA-type stereolithography devices that irradiate semiconductor laser light as activation light, DLP-type stereolithography devices that irradiate projector light, and LCD-type stereolithography devices that irradiate liquid crystal panel light, and light sources with activation light wavelengths of approximately 405 nm or approximately 385 nm are often used. In the present disclosure, the specific wavelength λ is preferably 405 nm or 385 nm, and the optical shaping apparatus is preferably an SLA type, a DLP type, or an LCD type.

[0074] The content of the photopolymerization initiator may be 0.05 to 5.0 parts by mass relative to 100 parts by mass of the polymerizable monomer component. If the content of the photopolymerization initiator is too high, burrs and the like will appear on the resulting shaped object, resulting in poor precision. On the other hand, if the content of the photopolymerization initiator is too low, shaping will not be possible in the molding process. Therefore, the content of the photopolymerization initiator is preferably 0.3 to 4.0 parts by mass, and more preferably 0.5 to 3.0 parts by mass, relative to 100 parts by mass of the polymerizable monomer component.

[0075] The photopolymerization initiator may be appropriately selected from known photopolymerization initiators that satisfy the above conditions. The photopolymerization initiator to be selected is not particularly limited, and examples thereof include self-cleavage type photopolymerization initiators, bimolecular hydrogen abstraction type photopolymerization initiators, photoacid generators, and combinations thereof. These photopolymerization initiators may be used in combination with a photosensitizing dye, an electron-donating compound, or the like.

[0076] Suitable self-cleavage photopolymerization initiators include acylphosphine oxide compounds such as diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide and phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide; benzoketal compounds, benzyne compounds, α-aminoacetophenone compounds, α-hydroxyacetophenone compounds, titanocene compounds, and acyloxime compounds. Examples of photoacid generators include iodonium salt compounds such as p-isopropylphenyl-p-methylphenyliodonium tetrakispentafluorophenylborate salt; sulfonium salt compounds such as dimethylphenacylsulfonium hexafluoroantimonate salt; and halomethyl-substituted triazine compounds such as 2,4,6-tris(trichloromethyl)-s-triazine. Examples of photosensitizing dyes include ketone compounds, coumarin dyes, cyanine dyes, merocyanine dyes, thiazine dyes, azine dyes, acridine dyes, xanthene dyes, squarium dyes, pyrylium salt dyes, condensed polycyclic aromatic compounds (anthracene, perylene, etc.), thioxanthone compounds, etc. Examples of electron donors include 4-dimethylaminobenzoic acid esters, 4-dimethylaminotoluene, p-dimethoxybenzene, 1,2,4-trimethoxybenzene, thiophene compounds, etc.

[0077] <Activating Light Absorber> When a molded body such as a dental prosthesis is produced with high precision using the curable composition for stereolithography of the present disclosure, in order to prevent excessive transmission of the activating light irradiated from a stereolithography device, which would result in a decrease in the molding precision of the molded body, it is preferable to contain 0.01 to 2.5 parts by mass of an activating light absorber that has the function of absorbing the activating light irradiated from the stereolithography device but does not have the ability to initiate photopolymerization, per 100 parts by mass of the polymerizable monomer component.

[0078] If the content of the activating light absorber is too high, the light emitted from the light source of the stereolithography device during the molding process will not pass through the composition, and the above condition [1] will not be satisfied. Also, if the content of the activating light absorber is too low, the precision of the resulting molded object will decrease. Therefore, the content of the activating light absorber is preferably 0.04 to 2.5 parts by mass, more preferably 0.08 to 2.0 parts by mass, and even more preferably 0.25 to 1.0 parts by mass, per 100 parts by mass of the polymerizable monomer component.

[0079] The activated light absorber is not particularly limited as long as it is a compound that absorbs light irradiated from a light source mounted in the stereolithography apparatus, and examples thereof include triazole compounds such as 2-(hydroxy-5-methylphenyl)-2H-benzotriazole and 2-(3-tert-butyl-2-hydroxy-5-methylphenyl)-5-chloro-2H-benzotriazole; and benzophenone compounds such as 2,4-dihydroxybenzophenone and 2-hydroxy-4-methoxybenzophenone.

[0080] <Other Components> (Polymerization Inhibitor) In order to improve the storage stability of the curable composition for stereolithography according to the present disclosure, a polymerization inhibitor is preferably blended in the range of 0.01 to 5.0 parts by mass relative to 100 parts by mass of the polymerizable monomer component. If the content of the polymerization inhibitor is too high, the composition tends to be insufficiently cured during the molding process, while if the content of the polymerization inhibitor is too low, the storage stability and molding accuracy of the composition tend to decrease. The content of the polymerization inhibitor is preferably 0.01 to 5.0 parts by mass, more preferably 0.03 to 4.0 parts by mass, and even more preferably 0.05 to 2.5 parts by mass relative to 100 parts by mass of the polymerizable monomer component.

[0081] As the polymerization inhibitor, a compound that reacts with radicals generated in the curable composition for stereolithography to deactivate the radicals can be used, and examples thereof include di-tert-butyl-p-cresol and 4-methoxyphenol.

[0082] (Chain Transfer Agent) A chain transfer agent may be blended into the curable composition for stereolithography according to the present disclosure in an amount ranging from 0.00001 to 1.0 part by mass per 100 parts by mass of the polymerizable monomer component, for the purposes of reducing shrinkage stress during stereolithography and improving modeling accuracy. If the amount of chain transfer agent is too high, the polymerization reaction of the curable composition for stereolithography will be suppressed more than necessary, whereas if the amount of chain transfer agent is too low, the effect of adding the chain transfer agent will not be obtained.

[0083] Examples of chain transfer agents include thiol compounds such as butanethiol, thiophenol, mercaptoethanol, octylthiol, and lauryl mercaptan; α-alkylstyrene compounds such as 2,4-diphenyl-4-methyl-1-pentene (α-methylstyrene dimer) and 2-phenyl-1-propene (α-methylstyrene); and halogenated hydrocarbons substituted with at least one halogen atom such as carbon tetrachloride and ethylene bromide. Among these, it is preferable to use an α-alkylstyrene compound, particularly α-methylstyrene dimer, because of its high crack suppression effect.

[0084] (Thermal Polymerization Initiator) The curable composition for stereolithography of the present disclosure may contain a thermal polymerization initiator as a polymerization initiator for secondary curing. In this case, it is preferable to use a thermal polymerization initiator with a 10-hour half-life temperature of 50 to 130°C, from the viewpoint that it does not function during primary curing but remains effectively in the laminate. Suitable thermal polymerization initiators include organic peroxides such as tert-butyl peroxylaurate and benzoyl peroxide; azo compounds such as azobutyronitrile and azobis(dimethylvaleronitrile); and the like.

[0085] The content of the thermal polymerization initiator is usually 0.001 to 1.0 part by mass, preferably 0.005 to 0.3 part by mass, and more preferably 0.01 to 0.1 part by mass, per 100 parts by mass of the polymerizable monomer component.

[0086] (Coloring Substance) The stereolithography curable composition of the present disclosure may contain a coloring substance within a range that satisfies the above-mentioned condition [I]. For example, when the stereolithography curable composition of the present disclosure is used to produce dental restorations such as inlays, onlays, crowns, and dentures, it is preferable to contain a coloring substance to reproduce the color of tooth crowns or the color of oral mucosa. The coloring substance may be a pigment or a dye. Examples of pigments include inorganic pigments such as titanium oxide, zinc oxide, zirconium oxide, zinc sulfide, aluminum silicate, calcium silicate, carbon black, iron oxide, copper chromite black, chromium oxide green, chrome green, violet, chrome yellow, lead chromate, lead molybdate, cadmium titanate, nickel titanium yellow, ultramarine blue, cobalt blue, bismuth vanadate, cadmium yellow, and cadmium yellow; and organic pigments such as monoazo pigments, diazo pigments, diazo condensation pigments, perylene pigments, and anthraquinone pigments.

[0087] 2. Method for Producing Curable Composition for Stereolithography To produce the curable composition for stereolithography of the present disclosure, it is sufficient to use the substances exemplified in Sections 1-3 and mix the components to obtain the predetermined composition described above to form a uniform liquid composition, but it is necessary to satisfy the above conditions [I] and [II]. The method for producing the curable composition for stereolithography of the present disclosure is characterized by using a combination of polymerizable monomer components and inorganic fillers that satisfies specific conditions, and by employing this method, the curable composition for stereolithography of the present disclosure can be easily produced.

[0088] That is, the method for producing a curable composition for stereolithography disclosed herein includes a mixing step of mixing 100 parts by mass of a polymerizable monomer component (A), 40 to 400 parts by mass of an inorganic filler (B) composed of a single type or multiple types of inorganic powder or particles, 0.01 to 5 parts by mass of a photopolymerization initiator (C) having the function of initiating photopolymerization upon irradiation with specific activating light, and 0.01 to 2.5 parts by mass of an activating light absorber (D) having the function of absorbing the specific activating light but not having photopolymerization initiation ability, and the polymerizable monomer component (A) and the inorganic filler (B) used in the mixing step satisfy all of the following conditions 1 to 4:

[0089] Condition 1: When the particle diameter of each particle constituting the inorganic filler (B) is x (nm) and pi is π, in the particle size distribution of the inorganic filler (B) measured by a microscopy method using a scanning microscope, the total number of particles having a particle diameter x (nm) in the range of 0.7λ / π to 4λ / π (nm) is 40% or more of the total number of particles constituting the inorganic filler (B).

[0090] Condition 2: With regard to the inorganic powder particles constituting the inorganic filler (B), when inorganic powder particles consisting of an aggregate of a single type of inorganic particles having a refractive index at 25°C within the range of 1.500 to 1.550 are defined as specific inorganic powder (b1), and inorganic powder particles consisting of an aggregate of a single type of inorganic particles having a refractive index outside the above range are defined as non-specific inorganic powder particles (b2), the inorganic filler (B) is either: (1) composed of a single type of specific inorganic powder (b1), or (2) composed of multiple types of specific inorganic powder (b1), and at least one of the multiple types of specific inorganic powder (b1) accounts for 10 mass% or more of the total mass of the inorganic filler (B), or (3) The inorganic filler (B) is composed of a single or multiple types of specific inorganic powder or particles (b1): 90% by mass or more and less than 100% by mass, and a single or multiple types of non-specific inorganic powder or particles (b2): more than 0% by mass and less than 10% by mass, and at least one of the single or multiple types of specific inorganic powder or particles (b1) accounts for 10% by mass or more of the total mass of the inorganic filler (B).

[0091] Condition 3: refractive index of polymerizable monomer component (A) at 25°C with respect to D line: n Ｍ is 1.490 to 1.550.

[0092] Condition 4: Among the refractive indices of at least one specific inorganic powder or particle (b1) that accounts for 10% by mass or more of the inorganic filler (B), n Ｍ The refractive index where the difference between Ｆ When Ｆ and Ｍ Absolute value of the difference with: |n Ｆ -n Ｍ | is less than or equal to 0.035.

[0093] In the method for producing a curable composition for stereolithography disclosed herein, a combination that meets the above criteria is selected from the polymerizable monomer components and inorganic fillers exemplified in Sections 1-3, a photopolymerization initiator that has the function of initiating photopolymerization upon irradiation with specific activating light is selected as the photopolymerization initiator, and an activating light absorber that absorbs the specific activating light is further selected, and they are weighed out so as to obtain 100 parts by mass of the polymerizable monomer component, 40 to 400 parts by mass of the inorganic filler, 0.01 to 5 parts by mass of the photopolymerization initiator, and 0.01 to 2.5 parts by mass of the activating light absorber, and then mixed to obtain a uniform liquid composition.

[0094] For example, when the specific wavelength λ is set to 405 nm and a curable composition for stereolithography is produced for use in a general-purpose stereolithography device equipped with a light source that emits semiconductor laser light with a wavelength of 405 nm, the particle diameter range of particles accounting for 40% or more of the inorganic filler should be set to 90 to 514 nm, a photopolymerization initiator that generates radicals when irradiated with light with a wavelength of 405 nm should be selected, and an activated light absorber that absorbs light with a wavelength of 405 nm should be selected.

[0095] In addition, since commonly used stereolithography devices use a light source with an activation light wavelength (peak wavelength) of 380 to 420 nm, the particle diameter range of particles accounting for 40% or more (preferably 60% or more, more preferably 80% or more) of the inorganic filler should be 85 to 535 nm (preferably 121 to 400 nm, more preferably 218 to 375 nm), a photopolymerization initiator that generates radicals when irradiated with light having a wavelength of 380 to 420 nm should be selected, and an activation light absorber that absorbs light having a wavelength of 380 to 420 nm should be selected.

[0096] The components are preferably mixed using a stirrer under the shielding of light that activates the photopolymerization initiator, for example, under red light, at room temperature until homogeneous, and after mixing, it is preferable to perform a degassing treatment.

[0097] The liquid composition obtained in this manner usually satisfies the above conditions [I] and [II]. However, for reasons of greater certainty, it is preferable to select the polymerizable monomer component (A) and the inorganic filler (B) to be used in the mixing step as follows. That is, using the polymerizable monomer component (A) and the inorganic filler (B) that satisfy the above conditions 1 to 4, a base composition consisting only of the polymerizable monomer component (A) and the inorganic filler (B), in which the compositional ratio of these components is the same as that of the curable composition for stereolithography that is the target of production, is separately prepared; a measurement is performed using a goniophotometer in which a measurement light containing light of the above specific wavelength: λ (nm), containing light mainly within a range of λ±50 (nm) and exhibiting the maximum intensity within said range is irradiated perpendicularly onto a sample of the base composition; and based on the intensity of the transmitted light in a specific output angle direction obtained by the measurement, the following equation is calculated: Sc={(I ７０ +I ７５ +I ８０ ) / (I ０ ×3)}×100 (where, I ０ , I ７０ , I ７５ , and I ８０ indicates the intensity of transmitted light in each direction at an emission angle of 0°, 70°, 75°, and 80°, respectively.) It is preferable to use in the mixing step a polymerizable monomer component (A) and an inorganic filler (B) for which it has been confirmed that the light-scattering index: Sc (%) determined by

[0098] 3. Method for manufacturing a three-dimensional stereolithography object and a dental restoration according to the present disclosure The method for manufacturing a three-dimensional stereolithography object according to the present disclosure is a method for manufacturing a three-dimensional object by liquid vat photopolymerization, which includes the above-described molding step, washing step, and secondary curing step, and is characterized in that the curable composition for stereolithography according to the present disclosure is used as the liquid photocurable composition supplied to the tank of the liquid vat photopolymerization device. Because the method for manufacturing a three-dimensional stereolithography object according to the present disclosure uses the curable composition for stereolithography according to the present disclosure, it is possible to manufacture a three-dimensional stereolithography object that has high mechanical strength and is free of cracks on its actual surface.

[0099] In the method for producing a three-dimensional optically shaped object of the present disclosure, the molding process includes: a first step of irradiating a predetermined position of a liquid photocurable composition held in a tank with activating light based on two-dimensional shape data at a height in the initial ranking order, thereby curing the composition, and forming a modeling layer having a shape corresponding to the two-dimensional shape data, and using the "modeling layer" as a bonded layer; a second step of moving the bonded layer up or down and supplying a liquid photocurable composition immediately above or below the bonded layer in the tank; and a third step of irradiating a predetermined position of the liquid photocurable composition supplied immediately above or below the bonded layer based on two-dimensional shape data at a height next in the ranking order in the previous step with activating light, thereby curing the composition, to form a new modeling layer having a shape corresponding to the two-dimensional shape data, and bonding the new modeling layer to the bonded layer, thereby obtaining a laminate having the new modeling layer as a new bonded layer; and a fourth step of moving the laminate up or down and supplying a liquid photocurable composition directly above or below the new bonded layer in the tank; and a cycle consisting of the third step and the fourth step is repeated using the new bonded layer as the bonded layer in the third step, and in the final third step, a new modeling layer is formed based on the two-dimensional shape data at the height of the final ranking order to obtain a laminate.

[0100] Such a liquid vat photopolymerization method including a molding step can be suitably carried out using a commercially available liquid vat photopolymerization device known as a 3D printer.

[0101] In the method for manufacturing a three-dimensional optically shaped object according to the present disclosure, after the molding step, the obtained laminate is washed with an organic solvent (a washing step is performed), and then the laminate is subjected to secondary curing by additional irradiation with activating light, heat treatment, or both (a secondary curing step is performed).

[0102] Examples of organic solvents used in the washing step include alcohol-based solvents such as ethanol, methanol, and isopropyl alcohol; ketone-based solvents such as acetone and methyl ethyl ketone; ether-based solvents such as diethyl ether, diisopropyl ether, tripropylene glycol monomethyl ether, and tetrahydrofuran; amide-based solvents such as N-methylpyrrolidone and dimethylacetamide; and halogen-based solvents such as methylene chloride and chloroform. Among these, alcohol-based solvents and ether-based solvents are preferred because of their high washing effect, and alcohol-based solvents are more preferred because of their low environmental impact.

[0103] The wavelength of the additional activating light irradiation in the secondary curing step is not particularly limited as long as it is a wavelength that can be absorbed by the photopolymerization initiator remaining in the laminate to generate radicals. The irradiation intensity of the additional activating light irradiation is 5 mW / cm or less so that the photopolymerization initiator remaining in the laminate generates a sufficient amount of radicals. ２ It is preferable that the power is 10 mW / cm or more. ２ More preferably, it is 30 mW / cm or more. ２ It is more preferable that the irradiation intensity is 10,000 mW / cm or more. The irradiation time is not particularly limited, and is preferably 1 minute or more, more preferably 3 minutes or more, and even more preferably 5 minutes or more. If the irradiation intensity during the additional activation light irradiation is too strong, the molded object may be overheated, which may cause cracks in the molded object. Therefore, the irradiation intensity should be 10,000 mW / cm or more. ２ It is preferable that:

[0104] Furthermore, when the curable composition for stereolithography according to the present disclosure contains a thermal polymerization initiator, the secondary curing can be carried out by heating the composition at a temperature of preferably 45 to 120°C, more preferably 50 to 90°C, and even more preferably 55 to 80°C.

[0105] The method for manufacturing a dental restoration of the present disclosure is characterized by producing dental restorations such as inlays, onlays, crowns, and dentures using the method for manufacturing a three-dimensional stereolithography object of the present disclosure. When manufacturing such dental restorations, it is preferable to incorporate an activating light absorber into the curable composition for stereolithography of the present disclosure. Furthermore, the three-dimensional shape data representing the shape of the dental restoration (three-dimensional object) used in the molding process may be CAD data designed based on digital data obtained by scanning the intraoral shape of an individual patient or an intraoral model created for each individual patient. The method for manufacturing a dental restoration of the present disclosure allows for the production of dental restorations that have high mechanical strength and are free of cracks on their actual surfaces.

[0106] The present invention will be explained in more detail below with reference to examples, but the present invention is not limited to these examples.

[0107] The compounds used in the examples and comparative examples and their abbreviations are shown below.

[0108] (1) Polymerizable Monomer Component (A) Monomer compositions A1 to A6 were used, which were prepared by mixing the following monomer compounds as shown below. (Monomer Compounds) UDMA: urethane dimethacrylate 3G: triethylene glycol dimethacrylate D-2.6E: bisphenol A ethylene glycol (EO) adduct dimethacrylate (number of EOs added: average 2.6) ACMO: acryloylmorpholine (Monomer Compositions) Monomer composition A1: UDMA: 50 parts by mass, 3G: 20 parts by mass, D-2.6E: 30 parts by mass (refractive index n Ｍ : 1.496) - Monomer composition A2: UDMA: 36 parts by mass, 3G: 14 parts by mass, D-2.6E: 50 parts by mass (refractive index n Ｍ : 1.508) - Monomer composition A3: UDMA: 29 parts by mass, 3G: 11 parts by mass, D-2.6E: 60 parts by mass (refractive index n Ｍ : 1.515) - Monomer composition A4: UDMA: 21.5 parts by mass, 3G: 8.5 parts by mass, D-2.6E: 70 parts by mass (refractive index n Ｍ : 1.521) - Monomer composition A5: UDMA: 70 parts by mass, 3G: 30 parts by mass (refractive index nＭ Monomer composition A6: UDMA: 70 parts by mass, ACMO: 30 parts by mass (refractive index n Ｍ :1.491).

[0109] The refractive index n of each monomer composition Ｍ is the refractive index for the D line at 25°C. Ｍ was measured using a digital Abbe refractometer (DR-A1-PLUS, manufactured by Atago Co., Ltd.) by placing each prepared monomer composition on a prism, looking into the sample through an eyepiece, and reading the value on the display when the boundary line and the intersection of the cross lines were aligned.

[0110] (2) Inorganic Filler (B) The inorganic powders shown below were used as inorganic fillers B1 to B8 either alone or in combination to achieve the compositions shown in Table 1. SZ-1: Spherical silica-zirconia (surface treated with γ-methacryloyloxypropyltrimethoxysilane, average primary particle diameter: 280 nm, refractive index n Ｆ : 1.522) SZ-2: spherical silica-zirconia (surface treated with γ-methacryloyloxypropyltrimethoxysilane, average primary particle diameter: 150 nm, refractive index n Ｆ : 1.522) SZ-3: spherical silica-zirconia (surface treated with γ-methacryloyloxypropyltrimethoxysilane, average primary particle diameter: 450 nm, refractive index n Ｆ : 1.540) SZ-4: spherical silica-zirconia (surface treated with γ-methacryloyloxypropyltrimethoxysilane, average primary particle diameter: 80 μm, refractive index n Ｆ SB-1: amorphous barium glass filler (manufactured by Schott, GM27884; surface-treated with γ-methacryloyloxypropyltrimethoxysilane, average primary particle diameter: 700 nm, refractive index n Ｆ SB-2: amorphous barium glass filler (manufactured by Schott, GM27884; surface-treated with γ-methacryloyloxypropyltrimethoxysilane, average primary particle diameter: 200 nm, refractive index n Ｆ: 1.530) SO-1: spherical silica (surface treated with γ-methacryloyloxypropyltrimethoxysilane, average primary particle diameter: 1000 nm, refractive index n Ｆ : 1.450)

[0111] The average primary particle size and refractive index n Ｆ was measured by the method described in section 1-2.

[0112] In addition, the content of particles having a particle diameter of 0.05 to 5.0 μm among all primary particles constituting each inorganic filler was measured from the particle size distribution determined by microscopy using a scanning microscope (referred to as the "specific particle content" in Table 1). Furthermore, for the inorganic fillers used in each Example and Comparative Example, the content of particles having a (primary) particle diameter within a specific range for particle diameter parameter α was determined from the particle size distribution determined by microscopy using a scanning microscope (referred to as the "α-sufficient particle content" in Table 1). Specifically, the content of particles having a particle diameter parameter α within a range of 0.7 to 4: R1 (%), the content of particles having a particle diameter parameter α within a range of 1.0 to 3.0: R2 (%), and the content of particles having a particle diameter parameter α within a range of 1.8 to 2.8: R3 (%) were determined. The results are also shown in Table 1. The particle size distribution is calculated by the number of all primary particles (50 or more) observed in a unit field of view in a scanning electron microscope photograph of each inorganic filler: n (particles), and the particle diameter (maximum diameter) of all primary particles: X ｉ (nm) was measured.

[0113]

[0114] (3) Photopolymerization initiator BAPO: phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide (generates radicals upon irradiation with activating light of 405 nm) TPO: 2,4,6-trimethylbenzoyl-diphenylphosphine oxide

[0115] (4) Activated Light Absorber SS3: 2-(3-tert-butyl-2-hydroxy-5-methylphenyl)-5-chloro-2H-benzotriazole

[0116] (5) Polymerization inhibitors BHT: dibutylhydroxytoluene HQME: hydroquinone methyl ether

[0117] (6) Coloring substance Titanium oxide (average primary particle diameter: 200 μm)

[0118] Example 1 (1) Preparation of base composition for Sc evaluation and curable composition for stereolithography 150 parts by mass of SZ-1 was added as an inorganic filler to 100 parts by mass of a polymerizable monomer component consisting of monomer composition A1 (50 parts by mass of UDMA, 20 parts by mass of 3G, and 30 parts by mass of D-2.6E), and the mixture was stirred and mixed until homogeneous, followed by degassing to prepare a base composition for Sc evaluation.

[0119] Separately, a raw material base composition was prepared in the same manner, to which 1.4 parts by mass of BAPO as a photopolymerization initiator, 0.7 parts by mass of SS3 as an activation light absorber, 0.1 parts by mass of HQME as a polymerization inhibitor, and 0.1 parts by mass of BHT (all of these blending amounts are blending amounts relative to 100 parts by mass of the polymerizable monomer component) were added, and the mixture was stirred and mixed under red light until uniform, and then degassed to prepare a liquid curable composition for stereolithography.

[0120] (2) Measurement of Light Scattering Index (Sc) The base composition for Sc evaluation was filled into a fluororesin mold (25 mm x 25 mm x 0.5 mm thick). The top and bottom surfaces were pressed against each other with glass slides, and the thickness of the composition was adjusted to 0.5 mm. The glass slides were then removed to prepare an evaluation sample. This evaluation sample was set in a three-dimensional goniophotometer (GP-200, manufactured by Murakami Color Research Laboratory Co., Ltd.), and measurement light was irradiated perpendicularly onto the evaluation sample to measure the luminous intensity distribution of the transmitted light. For the measurement, an interference filter (for GP-200, manufactured by Murakami Color Research Laboratory Co., Ltd.) was placed between the light source of the three-dimensional goniophotometer and the evaluation sample, and light having the wavelength distribution (relative spectral distribution) shown in Figure 5 was used as the measurement light. Based on the obtained luminous intensity distribution, the following equation: Sc = [(I ７０ +I ７５ +I ８０ ) / I ０ × 3] × 100. As a result, the light scattering index Sc was 0.1 (%).

[0121] (3) Measurement of Activating Light Transmittance The stereolithography curable composition obtained in (1) above was filled into a fluororesin mold (25 mm x 25 mm x 0.5 mm thick). The top and bottom surfaces were pressed against glass slides, and the thickness of the composition was adjusted to 0.5 mm. The glass slides were then removed to obtain a resin composition with a thickness of 0.5 mm. The transmittance of this resin composition at a wavelength of 405 nm was measured using a color difference meter (Spectrophotometer SE7700, manufactured by Nippon Denshoku Industries Co., Ltd.). The result was a transmittance of 5.30%.

[0122] (4) Production of three-dimensional stereolithography 3D printer (DWS, DW029D; wavelength: 405 nm, irradiation intensity: 83 mW) The stereolithography curable composition obtained in (1) above was supplied to the resin tray (tank) of a 10 mm x 10 mm x 25 mm rectangular parallelepiped stereolithography data (hereinafter abbreviated as "stl data") to perform a molding process, and a molded body (composed of a cured product of the stereolithography curable composition) having a laminated structure (laminate) was produced. Next, the obtained molded body was immersed in a plastic container filled with ethanol for 15 minutes and gently shaken to perform a washing process, followed by drying, and then UV CURING UNIT UVIS-2 (manufactured by DWS) for 30 minutes. Additional light irradiation (secondary curing) was performed to produce a three-dimensional stereolithography object.

[0123] (5) Evaluation of 3D Stereolithography The 3D stereolithography obtained in (4) above was used as an evaluation sample and subjected to evaluation of molding accuracy, crack evaluation, and three-point bending fracture strength test. The evaluation methods and results are shown below.

[0124] (Evaluation of molding accuracy) The length of each side of the evaluation sample was measured to the nearest 0.01 mm, and the measured value was divided by the set value (the length of each side set in the STL data) to obtain the value (actual measurement value / STL data set value) for each side, and the average value was evaluated as the average molding accuracy. As a result, the average molding accuracy was "1.01".

[0125] (Crack Evaluation) The surface of the evaluation sample was observed with an optical microscope (50x magnification), and the same evaluation sample was also platinum coated to a thickness of 5 nm and then observed with a scanning microscope (1000x magnification). The number and width of cracks observed on one surface of a 10 mm x 25 mm area of ​​the evaluation sample were confirmed and evaluated according to the following evaluation criteria. As a result, the evaluation was "A1". - Evaluation Criteria - A0: No cracks were observed on the surface of the cured product. A1: The number of cracks observed on the surface of the cured product was 5 or less, and each crack width was 10 μm or less, which is within the acceptable range. A2: The number of cracks observed on the surface of the cured product was 10 or less, and each crack width was 10 μm or less, which is within the acceptable range. A3: The number of cracks observed on the surface of the cured product was 20 or less, and each crack width was 10 μm or less, which is within the acceptable range. B: The number of cracks observed on the surface of the cured product was 20 or less, and each crack width was 10 to 40 μm. C: 20 or more cracks with widths of 10 to 40 μm are observed on the surface of the cured body. D: A large number of cracks with widths exceeding 40 μm are observed on the surface of the cured body.

[0126] Examples 2 to 14 and Comparative Examples 1 to 8 Base compositions for Sc evaluation and curable compositions for stereolithography were prepared in the same manner as in Example 1, except that the components and amounts used when preparing the base composition for Sc evaluation and the curable composition for stereolithography in Example 1 were changed as shown in Tables 2 and 3. Each of the resulting compositions was then evaluated in the same manner as in Example 1, and three-dimensional stereolithography objects were produced and evaluated using the resulting curable compositions for stereolithography in the same manner as in Example 1. The evaluation results are shown in Tables 4 and 5. Optical microscope images (magnification: 50x) taken during crack evaluation for Example 7 (evaluation A0), Example 11 (evaluation A2), and Comparative Example 1 (evaluation D) are shown in Figures 1, 2, and 3, respectively.

[0127] Comparative Example 9 A stereolithography curable composition was prepared according to the method described in Example 1 of Patent Document 3. Specifically, the polymerizable monomer component (A) and inorganic filler (B) shown in Table 3 were used in the blending ratios shown in Table 3, and 3.0 parts by mass of TPO as a polymerization initiator and 0.05 parts by mass of BHT as a polymerization inhibitor (the blending amounts are all relative to 100 parts by mass of the polymerizable monomer component) were added to prepare a stereolithography curable composition. A three-dimensional stereolithography object was then manufactured and evaluated using the resulting stereolithography curable composition in the same manner as in Example 1. A base composition for Sc evaluation was also prepared in the same manner as in Example 1, and each composition was evaluated in the same manner as in Example 1. The evaluation results are shown in Table 5. An optical microscope image (magnification: 50x) taken during crack evaluation of Comparative Example 9 (Evaluation C) is shown in Figure 4.

[0128]

[0129]

[0130]

[0131]

[0132] As shown in Table 4, the stereolithography curable compositions of Examples 1 to 14 had a small light scattering index Sc and a high activation light transmittance, resulting in high modeling accuracy and reduced cracking. On the other hand, as shown in Table 5, the stereolithography curable compositions of Comparative Examples 1 to 3 had a large light scattering index Sc and a low activation light transmittance, resulting in low modeling accuracy and cracking. Furthermore, the stereolithography curable compositions of Comparative Examples 4 to 7 had a small light scattering index Sc but a low activation light transmittance, resulting in cracking. The stereolithography curable composition of Comparative Example 8 had a large light scattering index Sc, resulting in low modeling accuracy and cracking. The stereolithography curable composition of Comparative Example 9 was prepared according to the method described in Patent Document 3, and cracking occurred due to its low activation light transmittance.

Claims

1. A liquid tank photopolymerization method for producing a three-dimensional object by irradiating a predetermined position of a liquid photocurable composition held in a tank with activating light containing light of a specific wavelength λ (nm) in the ultraviolet or visible light region to selectively cure the liquid photocurable composition present at that position, comprising: a curable composition for three-dimensional stereolithography used as the liquid photocurable composition, The composition contains 100 parts by mass of a polymerizable monomer component (A), 40 to 400 parts by mass of an inorganic filler (B) composed of a single type or multiple types of inorganic powder or particles, 0.01 to 5 parts by mass of a photopolymerization initiator (C) having a function of initiating photopolymerization upon irradiation with the activating light, and 0.01 to 2.5 parts by mass of an activating light absorber (D) having a function of absorbing the activating light but not having photopolymerization initiation ability, In the particle size distribution of the inorganic filler (B) measured by a microscopy method using a scanning microscope, 80% or more of all primary particles constituting the inorganic filler (B) are particles having a particle diameter of 0.05 to 5.0 μm; a transmittance of the activating light measured on a 0.5 mm thick sample made of the curable composition for three-dimensional optical fabrication is 1.00 to 50.00%, The polymerizable monomer component (A) and the inorganic filler (B) are When a composition consisting of only the polymerizable monomer component (A) and the inorganic filler (B), in which the compositional ratio of these components is the same as that of the curable composition for three-dimensional optical fabrication, is used as a base composition, a sample of the base composition having a thickness of 0.5 mm is irradiated perpendicularly with measurement light containing light of the specific wavelength: λ (nm), containing light within a range of λ±50 (nm) as a main component, and exhibiting the maximum intensity within the range, and the measurement light is measured using a goniophotometer, and the following formula is calculated based on the intensity of transmitted light in a specific emission angle direction: Sc={(I ７０ +I ７５ +I ８０ ) / (I ０ ×3)}×100 (In the formula, I ０ , I ７０ , I ７５ , and I ８０ indicate the intensity of transmitted light in the directions where the emission angles are 0°, 70°, 75°, and 80°, respectively.) The curable composition for three-dimensional optical shaping has a light scattering index Sc (%) determined by the following formula: 10 (%) or less.

2. (delete)

3. When the particle diameter of each particle constituting the inorganic filler (B) is x (nm) and pi is π, the total number of particles having a particle diameter x (nm) in the range of 0.7λ / π to 4λ / π (nm) in the particle size distribution of the inorganic filler (B) measured by a microscopy method using a scanning microscope accounts for 40% or more of the total number of particles constituting the inorganic filler (B). The curable composition for three-dimensional stereolithography according to claim 1 .

4. With regard to the inorganic powder particles constituting the inorganic filler (B), when an inorganic powder particle consisting of an aggregate of a single type of inorganic particles having a refractive index at 25°C within a range of 1.500 to 1.550 is defined as a specific inorganic powder particle (b1), and an inorganic powder particle consisting of an aggregate of a single type of inorganic particles having a refractive index outside the above range is defined as a non-specific inorganic powder particle (b2), the inorganic filler (B) is (1) Consisting of a single type of specific inorganic powder or particle (b1), (2) The inorganic filler (B) is composed of a plurality of specific inorganic powders (b1), and at least one of the plurality of specific inorganic powders (b1) accounts for 10% by mass or more of the total mass of the inorganic filler (B); or (3) A filler (B) is composed of a single or multiple specific inorganic powder or particles (b1): 90% by mass or more and less than 100% by mass, and a single or multiple non-specific inorganic powder or particles (b2): more than 0% by mass and less than 10% by mass, and at least one of the single or multiple specific inorganic powder or particles (b1) accounts for 10% by mass or more of the total mass of the inorganic filler (B), The refractive index of the polymerizable monomer component (A) at 25°C with respect to the D line is: n Ｍ is 1.490 to 1.550, Among the refractive indices of the at least one specific inorganic powder or particle (b1) that accounts for 10 mass % or more of the inorganic filler (B), n Ｍ The refractive index where the difference between Ｆ When Ｆ and Ｍ Absolute value of the difference with: |n Ｆ -n Ｍ | is 0.035 or less; The curable composition for three-dimensional stereolithography according to claim 1 .

5. A method for producing a curable composition for three-dimensional optical fabrication, comprising: The method includes a mixing step of mixing 100 parts by mass of a polymerizable monomer component (A), 40 to 400 parts by mass of an inorganic filler (B) composed of a single type or multiple types of inorganic powder or particles, 0.01 to 5 parts by mass of a photopolymerization initiator (C) having a function of initiating photopolymerization upon irradiation with activating light including light of a specific wavelength λ (nm) in the ultraviolet light region or the visible light region, and 0.01 to 2.5 parts by mass of an activating light absorber (D) having a function of absorbing the activating light but not having photopolymerization initiation ability, In the mixing step, the polymerizable monomer component (A) and the inorganic filler (B) are mixed under the following conditions 1 to 4: Condition 1: When the particle diameter of each particle constituting the inorganic filler (B) is x (nm) and pi is π, in the particle size distribution of the inorganic filler (B) measured by a microscopy method using a scanning microscope, the total number of particles having a particle diameter x (nm) in the range of 0.7λ / π to 4λ / π (nm) accounts for 40% or more of the total number of particles constituting the inorganic filler (B); Condition 2: With regard to the inorganic powder particles constituting the inorganic filler (B), when inorganic powder particles consisting of an aggregate of a single type of inorganic particles having a refractive index at 25°C within a range of 1.500 to 1.550 are defined as specific inorganic powder particles (b1), and inorganic powder particles consisting of an aggregate of a single type of inorganic particles having a refractive index outside the above range are defined as non-specific inorganic powder particles (b2), the inorganic filler (B) satisfies the following conditions: (1) Consisting of a single type of specific inorganic powder or particle (b1), (2) The inorganic filler (B) is composed of a plurality of specific inorganic powders (b1), and at least one of the plurality of specific inorganic powders (b1) accounts for 10% by mass or more of the total mass of the inorganic filler (B); or (3) A filler (B) is composed of a single or multiple types of specific inorganic powder or particles (b1): 90% by mass or more and less than 100% by mass, and a single or multiple types of non-specific inorganic powder or particles (b2): more than 0% by mass and less than 10% by mass, and at least one of the single or multiple types of specific inorganic powder or particles (b1) accounts for 10% by mass or more of the total mass of the inorganic filler (B); Condition 3: refractive index of the polymerizable monomer component (A) at 25°C with respect to the D line: n Ｍ is 1.490 to 1.550; Condition 4: Among the refractive indices of the at least one specific inorganic powder or particle (b1) that accounts for 10% by mass or more of the inorganic filler (B), n Ｍ The refractive index where the difference between Ｆ When Ｆ and Ｍ Absolute value of the difference with: |n Ｆ -n Ｍ | is less than or equal to 0.035; A method for producing a curable composition for three-dimensional stereolithography using a material that satisfies all of the above.

6. Using the polymerizable monomer component (A) and the inorganic filler (B) that satisfy the conditions 1 to 4, a base composition is separately prepared, which consists of only the polymerizable monomer component (A) and the inorganic filler (B), and the composition ratio of these components is the same as that of the curable composition for three-dimensional optical fabrication that is the target of production; A measurement was performed using a goniophotometer in which a 0.5 mm thick sample made of the base composition was irradiated perpendicularly with measurement light that contained light of the specific wavelength: λ (nm), was composed mainly of light within a range of λ±50 (nm), and was composed of light that exhibited the maximum intensity within the range, and based on the intensity of the transmitted light in a specific output angle direction obtained by the measurement, the following formula: Sc={(I ７０ +I ７５ +I ８０ ) / (I ０ ×3)}×100 (In the formula, I ０ , I ７０ , I ７５ , and I ８０ indicate the intensity of transmitted light in the directions where the emission angles are 0°, 70°, 75°, and 80°, respectively.) The light scattering index determined by: Sc (%) is 10 (%) or less, The polymerizable monomer component (A) and the inorganic filler (B) which have been confirmed to have the above properties are used in the mixing step. A method for producing the curable composition for three-dimensional stereolithography according to claim 5.

7. A method for producing a three-dimensional optically shaped object, comprising: irradiating a predetermined position of a liquid photocurable composition held in a tank with activating light containing light of a specific wavelength λ (nm) in the ultraviolet or visible light region to selectively cure the liquid photocurable composition present at that position, thereby producing a three-dimensional optically shaped object; a molding process in which, from three-dimensional shape data representing the shape of a three-dimensional object, the height direction of the three-dimensional object is digitized and ranked, and two-dimensional shape data representing the cross-sectional shape of the three-dimensional object at each ranked height is generated; the liquid photocurable composition held in the tank is irradiated with the activating light at predetermined positions determined based on the two-dimensional shape data, thereby selectively and primarily curing the liquid photocurable composition present at the predetermined positions to form modeling layers having the cross-sectional shape; and the modeling layers having the cross-sectional shapes at each height are sequentially formed and stacked in the order of the ranking, thereby obtaining a laminate having a shape corresponding to the shape of the three-dimensional object; a washing step of washing the laminate obtained in the molding step with an organic solvent; and a secondary curing step of subjecting the laminate cleaned in the cleaning step to additional irradiation with activating light, heat treatment, or both, for secondary curing; Including, A method for producing a three-dimensional optically shaped object, using the curable composition for three-dimensional optical shaping according to claim 1 as the liquid photocurable composition.

8. A method for manufacturing a dental restoration, comprising manufacturing a dental restoration by the method for manufacturing a three-dimensional optically shaped object according to claim 7.