Curable composition for three-dimensional photoforming and method for producing same, method for producing three-dimensional photoforming article, and

Abstract

Provided are: a curable composition for three-dimensional photomodeling, which is used in a liquid bath photopolymerization method, and which contains 100 parts by mass of a polymerizable monomer component (A), 40-400 parts by mass of an inorganic filler (B) comprising one or more inorganic powder particles, and 0.01-5 parts by mass of a photopolymerization initiator (C); 80% or more of all the primary particles constituting the inorganic filler (B) are particles having a particle diameter of 0.05-5.0 [mu] m, and the transmittance with respect to activated light is 1.00-50.00% as measured with respect to a sample having a thickness of 0.5 mm obtained from the curable composition for three-dimensional photomodeling. Also provided are a method for producing a three-dimensionally photomolded article and a method for producing a dental restoration, each of which uses the curable composition for three-dimensional photomolding.

Description

Technical Field

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

[0002] Photopolymerization is a technique known as photopolymerization, in which a photocurable composition (also called a photocurable resin or photocurable resin composition) containing a polymerizable monomer and a photopolymerization initiator is irradiated with light (activating light) that activates the photopolymerization initiator, thereby curing the composition and forming a three-dimensional object. There are several types of photopolymerization methods, but liquid tank photopolymerization is widely used due to its relatively low equipment costs and ability to produce objects with smooth surfaces with high precision.

[0003] In the liquid tank photopolymerization method, a three-dimensional object as a manufacturing target object is usually obtained in the following manner. First, the height direction of the three-dimensional object is digitized and serialized based on the 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 sequenced height is generated. Then, the liquid photocurable composition retained in the tank is irradiated with activating light at a predetermined position predetermined based on the above-mentioned two-dimensional shape data, thereby selectively causing the liquid photocurable composition present at the position to be cured once to form a modeling layer having the above-mentioned cross-sectional shape, and in accordance with the sequenced order, modeling layers having cross-sectional shapes at each height are sequentially formed and stacked, thereby obtaining a laminate having a shape corresponding to the shape of the three-dimensional object. Then, the laminate is cleaned with an organic solvent as needed, and then subjected to secondary curing to obtain the target object.

[0004] In the dental field, dental restorations such as dentures and crowns require high-precision fabrication of unique shapes tailored to the oral conditions of each patient. Therefore, research is underway to manufacture dental restorations using liquid tank photopolymerization, using CAD (Computer Aided Design) data designed using digital data obtained through intraoral scanning.

[0005] Dental restorations used in the oral cavity require not only the aforementioned high dimensional (shape) accuracy but also high mechanical strength that can fully withstand the loads of chewing. In this regard, the addition of inorganic fillers to a photocurable composition can reduce polymerization shrinkage, which is one of the causes of reduced accuracy, and improve the mechanical strength and surface hardness of the cured product. Therefore, it is believed that liquid tank photopolymerization using a photocurable composition containing an inorganic filler is suitable for photoforming dental restorations, and curable compositions for three-dimensional photoforming containing such inorganic fillers have also been proposed.

[0006] For example, Patent Document 1 discloses a composition comprising a polymerizable monomer (a), ultraviolet-absorbing inorganic particles (b), and a photopolymerization initiator (c) as a composition for optical three-dimensional molding that exhibits excellent molding accuracy, mechanical properties, and transparency and is particularly suitable for dental materials. Furthermore, Patent Document 2 discloses a composition comprising a translucent resin and two or more translucent particles having different refractive indices and Abbe numbers as a resin composition capable of producing a cured product (three-dimensional molded object) with excellent design. Furthermore, Patent Document 3 discloses a composition comprising a urethanized (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, wherein the content of the spherical inorganic particles (d) is 50 to 400 parts by mass relative to 100 parts by mass of the total amount of the polymerizable monomers, as a resin composition capable of producing a cured product (three-dimensional molded object) with excellent design.

[0007] Prior art literature

[0008] Patent Literature

[0009] Patent Document 1: International Publication No. 2018 / 074380

[0010] Patent Document 2: Japanese Patent Application Laid-Open No. 2020-180171

[0011] Patent Document 3: Japanese Patent Application Laid-Open No. 2022-41276

[0012] Patent Document 4: Japanese Patent No. 3917204 Summary of the Invention

[0013] Problems to be solved by the invention

[0014] In Patent Documents 1 to 3, compositions in which inorganic fillers are added to polymerizable monomers are used, thereby making it possible to obtain molded objects with good mechanical strength, elastic modulus, and wear resistance. However, the fluidity of the composition for optical stereoscopic molding described in Patent Document 1 is low, so there are cases where the shapes of applicable molded objects are limited. In addition, when the resin composition described in Patent Document 2 is left to stand for a long time, there are cases where the translucent particles (glass fillers, etc.) contained in the composition settle. In addition, it is known that in the resin composition for optical molding described in Patent Document 3, fine cracks that are difficult to visually distinguish often occur on the surface of the molded object (see Figure 4 When a molded object having such fine cracks is used as a dental restoration, it may become a starting point for the dental restoration to break in the oral cavity, thus becoming a problem.

[0015] Therefore, the subject of the present disclosure is to provide the following technology, which can produce high-precision and high-strength three-dimensional objects without generating cracks on the surface when using a curable composition for three-dimensional photomolding that is formulated with a certain amount of inorganic filler for high strength and producing three-dimensional objects by photomolding based on a liquid tank photopolymerization method.

[0016] Means for solving problems

[0017] A first embodiment of the present disclosure is a curable composition for three-dimensional photomodeling, which is a liquid photocurable composition for three-dimensional photomodeling used as a liquid photocurable composition in a liquid tank photopolymerization method. The liquid tank photopolymerization method produces a three-dimensional photomodeled object by irradiating a predetermined position of the liquid photocurable composition held in a tank with activating light having a specific wavelength λ (nm) in the ultraviolet or visible light region (hereinafter also referred to as "specific activating light") to selectively cure the liquid photocurable composition at that position.

[0018] The curable composition for three-dimensional light modeling 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 or multiple inorganic powders and particles, and 0.01 to 5 parts by mass of a photopolymerization initiator (C) having a function of initiating photopolymerization by irradiation with specific activating light.

[0019] In the particle size distribution of the inorganic filler (B) measured by microscopy using a scanning microscope, 80% or more of all primary particles constituting the inorganic filler (B) are particles having a particle size of 0.05 to 5.0 μm.

[0020] The transmittance of a 0.5 mm thick sample obtained from the curable composition for three-dimensional light modeling measured with respect to specific activating light was 1.00 to 50.00 (%).

[0021] The curable composition for three-dimensional light modeling of the present disclosure preferably contains 0.01 to 2.5 parts by mass of an activating light absorber (D) having a function of absorbing specific activating light but not having photopolymerization initiation capability.

[0022] The polymerizable monomer component (A) and the inorganic filler (B) satisfy:

[0023] The light scattering index Sc (%) determined by the following formula based on the intensity of transmitted light in a specific emission angle direction obtained by measurement using a goniophotometer is 10 (%) or less (hereinafter, this method is also referred to as a "specific formulation method"). In the measurement, when a composition composed only of a polymerizable monomer component (A) and an inorganic filler (B) and having the same composition ratio as the curable composition for three-dimensional light modeling of the present disclosure is used as a base composition, a sample having a thickness of 0.5 mm formed from the base composition is irradiated vertically with measurement light, the measurement light containing light of the specific wavelength λ (nm) and having light within the range of λ±50 (nm) as a main component and consisting of light showing the maximum intensity within this range,

[0024] Sc={(I 70 +I 75 +I 80 ) / (I0×3)}×100

[0025] (Where, I0, I 70 , I 75 , and I 80 The intensities of the transmitted light in the directions with emission angles of 0°, 70°, 75°, and 80° are shown respectively).

[0026] In addition, as a curable composition for three-dimensional light shaping of the present disclosure, it is preferred that, when the particle size of each particle constituting the inorganic filler (B) is set to x (nm) and the circumference is set to 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 size x (nm) in the range of 0.7λ / π to 4λ / π (nm) is more than 40% of the total number of particles constituting the inorganic filler (B).

[0027] In a specific formulation, it is preferred that, with respect to the inorganic powder or granules constituting the inorganic filler (B), when an inorganic powder or granule composed of an aggregate of single inorganic particles having a refractive index with respect to D-line at 25° C. within a range of 1.500 to 1.550 is defined as the specific inorganic powder or granule (b1), and an inorganic powder or granule composed of an aggregate of single inorganic particles having a refractive index outside the above range is defined as the non-specific inorganic powder or granule (b2), the inorganic filler (B) satisfies the following conditions:

[0028] (1) It is composed of a single specific inorganic powder (b1); or

[0029] (2) It is composed of a plurality of specific inorganic powders and particles (b1), and at least one of the plurality of specific inorganic powders and particles (b1) accounts for 10% by mass or more of the total mass of the inorganic filler (B); or

[0030] (3) It is composed of 90% by mass or more and less than 100% by mass of a single or multiple specific inorganic powder or particles (b1) and more than 0% by mass or less than 10% by mass of a single or multiple non-specific inorganic powder or particles (b2), 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).

[0031] Refractive index of polymerizable monomer component (A) at 25°C for D line: n M 1.490~1.550,

[0032] The refractive index of at least one specific inorganic powder (b1) accounting for 10% by mass or more of the inorganic filler (B) is equal to n M The refractive index with the largest difference is set as n F When n F With n M The absolute value of the difference: |n F -n M |Below 0.035.

[0033] The second embodiment of the present disclosure is a method for producing a curable composition for three-dimensional light modeling.

[0034] The production 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 or multiple inorganic powders and particles, 0.01 to 5 parts by mass of a photopolymerization initiator (C) having a function of initiating photopolymerization by 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 specific activating light but not having the ability to initiate photopolymerization.

[0035] In the mixing step, as the polymerizable monomer component (A) and the inorganic filler (B), substances satisfying all of the following conditions 1 to 4 are used.

[0036] Condition 1: Where the particle size of each particle constituting the inorganic filler (B) is represented by x (nm) and pi is represented by π, in the particle size distribution of the inorganic filler (B) measured by microscopy using a scanning microscope, the total number of particles having a particle size x (nm) within 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);

[0037] Condition 2: With respect to the inorganic powder or granules constituting the inorganic filler (B), when an inorganic powder or granule composed of an aggregate of single inorganic particles having a refractive index with respect to the D line at 25°C within the range of 1.500 to 1.550 is defined as the specific inorganic powder or granule (b1), and an inorganic powder or granule composed of an aggregate of single inorganic particles having a refractive index outside the above range is defined as the non-specific inorganic powder or granule (b2), the inorganic filler (B) satisfies the following conditions:

[0038] (1) It is composed of a single specific inorganic powder (b1); or

[0039] (2) It is composed of a plurality of specific inorganic powders and particles (b1), and at least one of the plurality of specific inorganic powders and particles (b1) accounts for 10% by mass or more of the total mass of the inorganic filler (B); or

[0040] (3) It is composed of 90% by mass or more and less than 100% by mass of a single or multiple specific inorganic powder or particles (b1) and more than 0% by mass or less than 10% by mass of a single or multiple non-specific inorganic powder or particles (b2), 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);

[0041] Condition 3: Refractive index of polymerizable monomer component (A) for D line at 25°C: n M 1.490~1.550;

[0042] Condition 4: The refractive index of at least one specific inorganic powder (b1) accounting for 10% by mass or more of the inorganic filler (B) is equal to or greater than n. M The refractive index with the largest difference is set as n F When n F With n M The absolute value of the difference: |n F -n M |Below 0.035.

[0043] In the method for producing a curable composition for three-dimensional light modeling of the present disclosure, it is preferred that the polymerizable monomer component (A) and the inorganic filler (B) used in the mixing step be those that have been confirmed to be:

[0044] Using the polymerizable monomer component (A) and the inorganic filler (B) satisfying the above-mentioned conditions 1 to 4, a base composition is separately prepared, which comprises 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 photolithography to be produced.

[0045] Measurement using a goniophotometer is performed in which a sample having a thickness of 0.5 mm and formed from a base composition is vertically irradiated with measurement light containing light having the specific wavelength λ (nm) described above and having light within a range of λ±50 (nm) as a main component and exhibiting a maximum intensity within this range. The light scattering index Sc (%) determined by the following formula based on the intensity of the transmitted light in a specific emission angle direction obtained by the measurement is 10 (%) or less.

[0046] Sc={(I 70 +I 75 +I 80 ) / (I0×3)}×100

[0047] (Where, I0, I 70 , I 75 , and I 80 The intensity of the transmitted light in each direction at an emission angle of 0°, 70°, 75°, and 80° respectively.

[0048] A third aspect of the present disclosure is a method for producing a three-dimensional light-shaped object, wherein the three-dimensional light-shaped object is produced 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 at the position, the method comprising:

[0049] A molding step of digitizing and serializing the height direction of the three-dimensional object based on 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 sequenced height, irradiating a liquid photocurable composition held in a tank with specific activating light at a predetermined position predetermined based on the two-dimensional shape data, thereby selectively curing the liquid photocurable composition at the position to form a molding layer having the above cross-sectional shape, and sequentially forming and stacking molding layers having the cross-sectional shape at each height in the sequenced order, thereby obtaining a laminate having a shape corresponding to the shape of the three-dimensional object;

[0050] a cleaning step of cleaning the laminate obtained in the molding step using an organic solvent; and

[0051] The secondary curing step is to perform additional activating light irradiation, heat treatment, or both on the laminated body cleaned in the cleaning step, thereby performing secondary curing.

[0052] Here, as the liquid photocurable composition, the curable composition for three-dimensional photomodeling of the present disclosure is used.

[0053] A fourth aspect of the present disclosure is a method for producing a dental restoration, comprising producing the dental restoration using the method for producing a three-dimensional photostructured object of the present disclosure.

[0054] Effects of the Invention

[0055] The curable composition for three-dimensional photomodeling of the present disclosure can suppress the decrease in fluidity and the sedimentation of inorganic fillers, thereby preventing cracks from occurring on the surface of the cured product, and can produce three-dimensional photomodeling objects with excellent mechanical strength and good modeling accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] [ Figure 1 ] is a diagram showing the state of observing the surface of the three-dimensional light-shaped object obtained in Example 7 using an optical microscope (magnification 50 times).

[0057] [ Figure 2 ] is a diagram showing the state of observing the surface of the three-dimensional light-shaped object obtained in Example 11 using an optical microscope (magnification 50 times).

[0058] [ Figure 3 ] is a diagram showing the state of observing the surface of the three-dimensional light-shaped object obtained in Comparative Example 1 using an optical microscope (magnification 50 times).

[0059] [ Figure 4 ] is a diagram showing the state of observing the surface of the three-dimensional light-shaped object obtained in Comparative Example 9 using an optical microscope (magnification 50 times).

[0060] [ Figure 5 ] is a graph showing the wavelength distribution (relative spectral distribution) of the measurement light used in measuring the light scattering index Sc in the examples and comparative examples. DETAILED DESCRIPTION

[0061] As mentioned above, photocurable compositions that incorporate a certain amount of inorganic filler to enhance the mechanical strength and surface hardness of the cured product can sometimes suffer from reduced fluidity and particle sedimentation during storage. Furthermore, when using the photopolymerization resin composition described in Patent Document 3 to produce shaped objects using the liquid tank photopolymerization method (although not mentioned in Patent Document 3), fine cracks often develop on the surface of the shaped objects that are difficult to visually detect.

[0062] The inventors of the present application have discovered that the above-mentioned problems can be solved by controlling the particle size of particles constituting the blended inorganic filler and setting the activation light transmittance of the composition before curing to a specific range, thereby completing the invention of the present disclosure.

[0063] Hereinafter, the curable composition for three-dimensional photomodeling (hereinafter also referred to as "curable composition for photomodeling") of the present disclosure, its manufacturing method, the manufacturing method of a three-dimensional photomodeling object, and the manufacturing method of a dental restoration are described. It should be noted that in this specification, unless otherwise specified, expressions such as "x to y" using numerical values ​​x and y refer to "above x and below y". In the case where only the numerical value y is marked with a unit in the expression, the unit can also be applied to the numerical value x. In addition, 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".

[0064] 1. Curable composition for photomolding

[0065] The curable composition for photomodeling of the present disclosure is a composition used as a liquid photocurable composition when producing a three-dimensional photomodeled object by liquid tank photopolymerization, that is, a curable composition for three-dimensional photomodeling by liquid tank photopolymerization.

[0066] Here, the liquid tank photopolymerization method refers to the following method: it includes the following steps, namely, based on three-dimensional shape data representing the shape of the three-dimensional object, digitizing and serializing the height direction of the three-dimensional object, and generating two-dimensional shape data representing the cross-sectional shape of the three-dimensional object at each serialized height, irradiating activating light to a specified position predetermined based on the above-mentioned two-dimensional shape data for a liquid photocurable composition retained in the tank, thereby selectively curing the liquid photocurable composition present at the position (once) to form a modeling layer having the above-mentioned cross-sectional shape, and sequentially forming and stacking modeling layers having cross-sectional shapes at each height in the order of serialization, thereby obtaining a stacked body having a shape corresponding to the shape of the three-dimensional object (hereinafter also referred to as a "molding step"), performing a cleaning treatment based on an organic solvent as needed (hereinafter also referred to as a "cleaning step") and a secondary curing treatment (hereinafter also referred to as a "secondary curing step"), thereby obtaining a three-dimensional photo-shaped object having a shape corresponding to the shape of the three-dimensional object.

[0067] The curable composition for photomodeling of the present disclosure is characterized in that it 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 or multiple inorganic powders and particles, and 0.01 to 5 parts by mass of a photopolymerization initiator (C) having a function of initiating photopolymerization by 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, more than 80% of all particles constituting the inorganic filler (B) are particles with a particle size of 0.05 to 5.0 μm, and the transmittance with respect to the specific activating light measured for a sample with a thickness of 0.5 mm obtained from the curable composition for photomodeling is 1.00 to 50.00 (%).

[0068] By including the polymerizable monomer component (A) and the inorganic filler (B) in the aforementioned quantitative ratio, the strength and surface hardness of the cured product, the target three-dimensional optically shaped object, can be improved. Furthermore, by ensuring that the particles constituting the inorganic filler (B) meet the aforementioned particle size requirements, an increase in the viscosity of the composition and the risk of particle sedimentation during storage can be suppressed.

[0069] Here, the fact that 80% or more of all primary particles constituting the inorganic filler (B) are particles having a particle size of 0.05 to 5.0 μm can be confirmed by measuring the particle size distribution of the inorganic filler (B), which is measured by a microscopic method using a scanning microscope. Specifically, the inorganic filler (B) used to prepare the curable composition for photomolding of the present disclosure is photographed using a scanning electron microscope, and the number of all primary particles (50 or more) observed within a unit field of view of the photograph is counted: n (pieces), and the primary particle size (maximum diameter) of each particle of all primary particles is measured: X i (nm), from which the particle size distribution can be known. i Where i is a natural number from 1 to n, indicating the number of each primary particle measured. Average (primary) particle size: X (nm) The sum of the particle sizes of all measured primary particles (i = 1 to n) can be used: ΣX i , using the formula: X = ΣX i / nCalculate.

[0070] It should be noted that the inorganic filler (B) is sometimes contained in the form of aggregated particles formed by the aggregation of primary particles. If the particle size distribution of the primary particles meets the above conditions, the particle size distribution of the aggregated particles is not particularly limited. In order to suppress the sedimentation of the inorganic filler (B), the fewer aggregated particles of the inorganic filler (B) contained in the curable composition for photomodeling of the present disclosure, the better. The average particle size of the inorganic filler (B), including the aggregated particles of the primary particles, measured by the laser diffraction and scattering method, is generally 0.05 to 100 μm, preferably 0.05 to 50 μm, and more preferably 0.05 to 30 μm.

[0071] In addition, in the curable composition for photomolding of the present disclosure, the risk of cracking on the surface of the cured body can be reduced by measuring the transmittance of a sample with a thickness of 0.5 mm obtained from the curable composition for photomolding to a specific activating light of 1.00 to 50.00 (%).

[0072] Generally, the cause of cracks on the surface of a cured body is unclear, but the inventors of this application have confirmed that cracks are generated when an uncured curable composition attached to the surface of a laminate is cleaned with an organic solvent after a laminate is obtained using a light shaping device. In addition, the inorganic filler contained in the light shaping curable composition contains a large number of particles with a particle size that causes scattering (specifically, Mie scattering or Reyleigh scattering) when irradiated with activating light. Therefore, weak activating light (side scattered light) that is offset from the optical axis and scattered is generated at the irradiation spot, thereby causing the curing depth to become extremely shallow, and forming a region with a low cross-linking density between the layers of the laminate (hereinafter also referred to as "interlayer low cross-linking density region."), which is considered to be one of the causes of cracks. That is, during cleaning, the organic solvent penetrates into the interlayer low cross-linking density region, thereby swelling the region, expanding the molecular distance between the polymer chains constituting the molded body, and temporarily reducing the strength. At this time, due to the internal stress remaining in the molded body during the molding process, the portion with reduced strength is destroyed, and it is therefore believed that cracks may occur in this region.

[0073] It should be noted that while Patent Document 3 does not mention the cause of cracks on the surface of the cured product, the inventors of the present application conducted additional experiments on the photomodeling resin composition described in Patent Document 3 and found that the transmittance of activating light was low for the photomodeling resin composition in which cracks were observed on the surface of the cured product. This is believed to be the reason why the occurrence of cracks was overlooked in Patent Document 3.

[0074] In the curable composition for light shaping of the present disclosure, by making the transmittance relative to the specific activating light within the above-mentioned range, the influence of scattering is reduced, and the risk of cracks on the surface of the cured body is reduced. In order to be able to more reliably prevent the occurrence of cracks and to manufacture three-dimensional light-shaped objects with high precision, the curable composition for light shaping of the present disclosure is preferably the above-mentioned specific formulation. As a specific formulation, it has the following characteristics: it contains a polymerizable monomer component, an inorganic filler with a particle size that suppresses the risk of viscosity increase and sedimentation, a photopolymerization initiator, and an activating light absorber in a specified amount ratio, and as a combination of the polymerizable monomer component and the inorganic filler, a combination with a light scattering index Sc within a specific range is adopted. In the specific formulation, by suppressing the scattering of light in the direction of deviation from the optical axis caused by the inorganic filler, the transmittance relative to the specific activating light (in the state before curing) is within a specific range, thereby preventing the occurrence of cracks, and depending on the circumstances, the shaping accuracy can be further improved.

[0075] That is, the specific formulation is a uniform 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 or multiple inorganic powders and particles, 0.01 to 5 parts by mass of a photopolymerization initiator (C) having the function of initiating photopolymerization by 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 specific activating light but not having the ability to initiate photopolymerization, and satisfying the following conditions [I] and [II], thereby achieving the effects of high strength, prevention of cracking, and high precision.

[0076] [I] The transmittance of a sample having a thickness of 0.5 mm formed of a curable composition for photomodeling with respect to specific activating light is 1.00 to 50.00 (%).

[0077] [II] Based on the intensity of the transmitted light in a specific emission angle direction obtained by measurement using a goniophotometer, the formula: Sc = {(I 70 +I 75 +I 80 ) / (I0×3)}×100, the light scattering index: Sc(%) value is 10(%) or less. In the above-mentioned measurement, when a composition consisting of only a polymerizable monomer component (A) and an inorganic filler (B) and having the same composition ratio as that of a curable composition for photomolding is used as a base composition, a sample having a thickness of 0.5 mm formed from the base composition is vertically irradiated with measurement light, which contains light of a specific wavelength: λ(nm) and has light within the range of λ±50(nm) as a main component and is composed of light showing the maximum intensity within this range. Wherein, I0, I 70 , I 75 , and I 80The intensities of the transmitted light in the directions with emission angles of 0°, 70°, 75°, and 80° are shown respectively.

[0078] If a curable composition for photomolding in a specific formulation does not meet the aforementioned conditions regarding the ingredients and their ratios, as well as the transmittance requirements for specific activating light, it is difficult to produce high-strength, three-dimensional objects with high precision. If condition [I] is not met, for example, if the transmittance is less than 1%, sufficient curing depth cannot be achieved, resulting in the formation of numerous interlayer regions with low crosslinking density and significant cracking. On the other hand, for compositions containing an inorganic filler (B) and an activating light absorber (D), achieving a system with a transmittance exceeding 50% while maintaining high molding precision is extremely difficult.

[0079] It should be noted that these conditions define the conditions that must be met by the polymerizable monomer component (A), inorganic filler (B), photopolymerization initiator (C), and activating light absorber (D), which are components of a specific formulation. The transmittance specified in condition [I] corresponds to the "transmittance of the photocurable composition for photomodeling of the specific formulation in the state before photocuring with respect to a specific activating light" and serves as an indicator of the depth of cure when the photocurable composition for photomodeling of the present disclosure is irradiated with the specific activating light. The Sc specified in condition [II] is an indicator of the "light scattering state when the photocurable composition for photomodeling of the present disclosure is irradiated with the specific activating light," specifically, the state of side-scattered light, and thus, the extent of the resulting low crosslink density region between layers. These cure depth and side-scattered light states are important for achieving the effects of the photocurable composition for photomodeling of the present disclosure and are determined by the combination of the components used. However, the physical properties of the components that influence the transmittance specified in condition [I] and the Sc specified in condition [II] are diverse, making it virtually impossible to directly define a specific combination of substances that meet these conditions. Therefore, in a specific formulation, components (A), (B), (C), and (D) are required to simultaneously satisfy conditions [I] and [II]. In a curable composition for photomodeling that does not contain component (D), components (A), (B), and (C) are required to simultaneously satisfy conditions [I] and [II]. It should be noted that the curable composition for photomodeling of the present disclosure includes a composition obtained by the method for producing a curable composition for photomodeling of the present disclosure described below.

[0080] Thus, from the viewpoint of preventing cracking, it is extremely important to satisfy the conditions [I] and [II]. First, these conditions will be described, and then the ingredients, their mixing ratios, etc. of the curable composition for photomodeling of the present disclosure will be described.

[0081] 1-1. About conditions [I]

[0082] Regardless of whether or not the curable composition for photomolding of the present disclosure uses a specific formulation, it contains a photopolymerization initiator. Therefore, there is a concern that curing may proceed due to light irradiation during measurement. Regarding this, the transmittance measurement method using a colorimeter, described below, allows measurement of the transmittance of specific activating light before curing proceeds.

[0083] The transmittance of the curable composition for photomodeling of the present disclosure with respect to a specific activating light can be measured in the following manner. First, the curable composition for photomodeling of the present disclosure is filled in a resin mold (25 mm × 25 mm × thickness 0.5 mm), and then the upper and lower surfaces are pressed together with a glass slide to make a thickness of 0.5 mm. The glass slide is then removed, and a measurement sample with a thickness of 0.5 mm is prepared using this method. Next, the measurement sample is placed in a colorimeter (for example, spectrophotometer SE7700 manufactured by Nippon Denshoku Industries Co., Ltd.), and the transmittance of the activating light (for example, 405 nm wavelength light, 385 nm wavelength light) is measured by a transmittance measurement using a halogen lamp (measurement wavelength: 380 to 780 nm).

[0084] As mentioned above, if the transmittance measured in this manner is less than the lower limit of 1.00%, sufficient curing depth cannot be achieved, making photomolding difficult. Even if photomolding is possible, cracks are likely to form in the molded object. Furthermore, in systems containing 40 parts by mass or more of inorganic filler per 100 parts by mass of the polymerizable monomer component and an amount of photopolymerization initiator capable of curing by photomolding, achieving a transmittance significantly exceeding the upper limit of 50.00% is difficult. Furthermore, even within the achievable transmittance range, excessive exposure to specific activating light can lead to excessive curing reactions, resulting in a molded object with a shape completely different from the CAD data. From the perspective of preventing cracking and maintaining the desired shape of the molded object, the transmittance is preferably between 2.00 and 30.00%, and more preferably between 5.00 and 20.00%.

[0085] It should be noted that the transmittance described above tends to increase with increasing light transmittance of the polymerizable monomer component and inorganic filler and decreasing the refractive index difference between the two. If the transmittances differ, this is affected by the mixing ratio of the two. Typically, the transmittance of the polymerizable monomer component is significantly higher than 5.00%. Therefore, if the inorganic filler content is within the specified range, using a light-transmitting filler as the inorganic filler and minimizing the refractive index difference between the two can naturally achieve a transmittance of 1.00% or above, and can even achieve a sufficient transmittance of 5.00% or above.

[0086] 1-2. Regarding Conditions [II]

[0087] It is generally known that when light irradiates fine particles of a particle size suitable for photomolding curable compositions, 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 occur, the scattered light diffuses not only forward but also to the sides and rearward. Furthermore, the scattered light that diffuses laterally (side scattered light) is believed to reduce the transmittance of the specific activating light in condition [I], causing cracks and further reducing the molding accuracy of the molded article.

[0088] The diffusion and intensity of the side scattered light, that is, the intensity distribution of the scattered light relative to the scattering direction (angle), is affected not only by the particle size, but also by the refractive index of the particles and the polymerizable monomer components present around the particles (which become the dispersion medium). However, in a dispersion system in which particles are dispersed in the form of a powder with a particle size distribution in a polymerizable monomer component, especially a dispersion system composed of a plurality of particles with different refractive indices, it is essentially impossible to grasp the scattering behavior of each particle, and the scattering behavior of the system as a whole has to be grasped. In addition, in the case where the curable composition for light shaping of the present disclosure is used for the manufacture of dental restorations, etc., the greater the average "activating light intensity scattered to the side" of the system as a whole, the lower the shaping accuracy, and thus the lower the transmittance of the specific activating light, and there is a concern that cracks will be generated due to the increase in the low cross-linking density area between the layers. For such reasons, in the present disclosure, the light scattering index defined by the above formula: Sc (%) of the base composition (formed only by polymerizable monomer components and inorganic fillers and uniformly containing them in a specified amount ratio) that serves as the basis of the photo-curable composition is used to indirectly specify the combination of the polymerizable monomer components and inorganic fillers used in the photo-curable composition of the present disclosure.

[0089] It should be noted that the measurement of refracted light passing through a sample using a goniophotometer (goniophotometer) is used, for example, to evaluate the optical properties of materials that require light diffusion, such as lampshades of lighting fixtures and projector screens. In the dental field, as described in Patent Document 4, it is also used to determine indicators for evaluating the optical texture of tooth filling and restorative materials, specifically, to determine the diffusion degree D.

[0090] In the present disclosure, the measurement using a goniophotometer for determining the light scattering index Sc can be performed in the following manner. First, a (measurement) base composition obtained by sampling a portion of the (raw material) base composition prepared in the preparation process of the curable composition for light shaping in the present disclosure, or a (measurement) base composition prepared by separate preparation, is used to prepare a measurement sample with a thickness of 0.5 mm in the same manner as the transmittance measurement. Next, the measurement sample is placed in a three-dimensional goniophotometer (for example, GP-200 manufactured by Murakami Color Research Laboratory Co., Ltd.), and the measurement sample is vertically irradiated with "measurement light comprising light of a specific wavelength: λ (nm), and light within the range of λ±50 (nm) as the main component, and consisting of light showing the maximum intensity within this range" to measure the intensity of the transmitted light in each emission angle direction. If the light emitted from the light source (capable of emitting light including wavelength λ) included with the three-dimensional goniophotometer does not meet the aforementioned conditions for measurement light, an interference filter (e.g., GP-200 manufactured by Murakami Color Research Laboratory Co., Ltd.) may be used to create measurement light that meets the aforementioned conditions. The phrase "light within the range of λ ± 50 (nm) is the primary component" means that, in the spectrum representing the wavelength distribution (relative spectral distribution) of the measurement light, the integrated value of the intensity of light within the range of λ ± 50 (nm) is 90% or greater of the integrated value of the intensity of the entire measurement light.

[0091] If the light scattering index (Sc) of the base composition exceeds 10%, the formation of low-crosslink density regions between layers, which can cause cracks due to side-scattered light, is unavoidable. To prevent cracking and improve 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, and its lower limit is 0.0%.

[0092] The light scattering index Sc of the basic composition is affected by the mixing ratio of the polymerizable monomer component and the inorganic filler. When this ratio is constant, it can be controlled to a certain 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.

[0093] For example, regarding particle size, a parameter known as the "particle size parameter: α" is known. It is an indicator of light scattering and scattering intensity caused by particles. When the wavelength (nm) of the incident light is represented by λ0, the circumference of the circle is represented by π, and the particle size of the inorganic particle is represented by x (nm), the particle size parameter α is defined by the formula: α = (π × x) / λ0. When the particles are transparent to the incident light, it is believed that 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 using a 405nm wavelength laser, the most common activating light used in liquid tank photopolymerization, based on the relationship x = α·λ0 / π, the particle size x when α = 10 is 1290nm = 1.29μm. When using a 385nm wavelength laser, the particle size x when α = 10 is 1226nm = 1.23μm. Since most dental inorganic fillers have a particle size smaller than this value in many cases, it can be said that the above-mentioned scattering occurs and cracks are likely to occur.

[0094] According to research conducted by the inventors of the present application, even when Mie scattering or Reyleigh scattering occurs, in the particle size distribution measured by microscopy using a scanning microscope, as the proportion of particles having a particle size parameter α within the range of 0.7 to 4, that is, particles satisfying the relationship x = 0.7 × (λ / π) to 4 × (λ / π) (x = 90 to 514 nm when the wavelength of activating light is 405 nm, and x = 86 to 490 nm when the wavelength of activating light is 385 nm), increases, the light scattering index Sc tends to decrease. In order to facilitate achieving a light scattering index Sc of 10% or less, the inorganic filler (B) used preferably satisfies the following condition 1.

[0095] Condition 1: When the particle size of each particle constituting the inorganic filler (B) is set to x (nm) and the circumference is set to 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 size x (nm) in the range of 0.7λ / π to 4λ / π (nm) is more than 40% of the total number of particles constituting the inorganic filler (B), preferably more than 60%, and more preferably more than 80%.

[0096] In addition, from the perspective of making it easier to satisfy condition [II], in the particle size distribution measured by a microscopy method using a scanning microscope, the proportion of particles with a particle size parameter α 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 with a particle size parameter α 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.

[0097] It should be noted that commonly used optical shaping devices (3D printers) use a light source with an activating light wavelength (peak wavelength) of 380 to 420 nm. Therefore, in order to simultaneously meet conditions [I] and [II], in the particle size distribution measured by microscopy using a scanning microscope, the total number of particles with a particle size 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 size range is 121 to 400 nm, and an even more preferred particle size range is 218 to 375 nm. That is, in the particle size distribution measured by microscopy using a scanning microscope, the total number of particles with a particle size range of 218 to 375 nm is most preferably 80% or more of the total number of particles constituting the inorganic filler (B).

[0098] 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 used in dental applications and the refractive index of the polymerizable monomer component, it is preferred that the combination of the inorganic filler and the polymerizable monomer component satisfy the following conditions 2 to 4.

[0099] Condition 2: With respect to the inorganic powder or granules constituting the inorganic filler (B), when an inorganic powder or granule composed of an aggregate of single inorganic particles having a refractive index with respect to (sodium) D-rays at 25° C. in the range of 1.500 to 1.550 is defined as the specific inorganic powder or granule (b1), and an inorganic powder or granule composed of an aggregate of single inorganic particles having a refractive index outside the above range is defined as the non-specific inorganic powder or granule (b2), the inorganic filler (B) satisfies the following conditions:

[0100] (1) It is composed of a single specific inorganic powder (b1); or

[0101] (2) It is composed of a plurality of specific inorganic powders and particles (b1), and at least one of the plurality of specific inorganic powders and particles (b1) accounts for 10% by mass or more of the total mass of the inorganic filler (B); or

[0102] (3) It is composed of a single or multiple specific inorganic powders and particles (b1): 90% by mass or more and less than 100% by mass, and a single or multiple non-specific inorganic powders and particles (b2): greater than 0% by mass and less than 10% by mass, and at least one of the single or multiple specific inorganic powders and particles (b1) accounts for more than 10% by mass of the total mass of the inorganic filler (B).

[0103] Condition 3: Refractive index of polymerizable monomer component (A) for D line at 25°C: n M It is 1.490~1.550.

[0104] Condition 4: The refractive index of at least one specific inorganic powder (b1) accounting for 10% by mass or more of the inorganic filler (B) is equal to or greater than n. M The refractive index with the largest difference is set as n F When n F With n M The absolute value of the difference: |n F -n M |Below 0.035.

[0105] If the above|n F -n M | 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. If the proportion of particles with a particle size much smaller than the wavelength of the activating light increases, Rayleigh scattering tends to occur, and the light scattering index Sc tends to increase. Conversely, if the proportion of particles with a particle size much larger than the wavelength of the activating light increases, the frequency of collisions between the activating light and the inorganic particles increases significantly, and the light scattering index Sc tends to increase.

[0106] The refractive index of the inorganic powder and granular material composed of a single material and the refractive index of the polymerizable monomer component with respect to the D line at 25° C. can each be measured as follows.

[0107] That is, the refractive index of the polymerizable monomer component can be measured by placing the prepared monomer composition on a prism using an Abbe refractometer (e.g., Atago Co., Ltd., Digital Abbe Refractometer DR-A1-PLUS), observing the sample through an eyepiece, and reading the value of the display when the boundary line and the crosshairs intersect (this value becomes the refractive index). Alternatively, the refractive index of an inorganic powder or particle can be determined by mixing toluene or ethanol with bromonaphthalene to prepare solutions having a refractive index that differs by 0.001, then mixing each inorganic powder or particle in each solution having a different refractive index and oscillating the mixture, and using the refractive index of the most transparent solution as the refractive index of the inorganic powder or particle.

[0108] 1-3. Components and their proportions of the curable composition for photolithography

[0109] <Polymerizable Monomer Component>

[0110] As the polymerizable monomer component, a radical polymerizable monomer can be used without particular limitation. Among the radical polymerizable monomers, (meth)acrylate monomers are preferably used because of their fast curing speed and excellent strength of the obtained shaped object.

[0111] As the (meth)acrylate monomer, any of monofunctional (meth)acrylates, bifunctional (meth)acrylates, and trifunctional or higher-functional (meth)acrylates can be used. To produce a stronger shaped object, it is preferred that bifunctional or higher-functional (meth)acrylates account for 50% by mass or more, preferably 80% by mass or more, of the total weight of all radically polymerizable monomers. More preferably, the proportion of bifunctional or higher-functional (meth)acrylates is 95% by mass or more.

[0112] Examples of preferably usable polyfunctional (meth)acrylates having two or more functional groups 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; and ethylene glycol (meth)acrylates, such as triethylene glycol dimethacrylate and ethylene glycol dimethacrylate. Aliphatic di(meth)acrylates such as 1,3-propylene glycol di(meth)acrylate and 1,9-nonanediol dimethacrylate; urethane group-containing (meth)acrylates such as 1,6-bis(methacryloyloxy-2-ethoxycarbonylaminophenyl)-2,2,4-trimethylhexane; trifunctional (meth)acrylates such as trimethylolpropane trimethacrylate; and isocyanate-backbone-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, and tris(2-methacryloyloxyethyl)isocyanurate are preferred due to their low viscosity and high strength.

[0113] Examples of monofunctional (meth)acrylates suitable for use in combination with bifunctional or higher-functional (meth)acrylates include hydroxyethyl methacrylate, methyl (meth)acrylate, ethyl (meth)acrylate, isopropyl (meth)acrylate, hydroxyethyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, and glycidyl (meth)acrylate.

[0114] In addition, these radical polymerizable monomers may be used alone or in combination of two or more.

[0115] <Inorganic filler>

[0116] To enhance the mechanical strength, such as rigidity, of the resulting shaped object, the curable composition for photomolding of the present disclosure contains 40 to 400 parts by mass of an inorganic filler composed of a single or multiple inorganic powders and particles, relative to 100 parts by mass of the polymerizable monomer component. Excessive amounts of the inorganic filler can result in excessively high viscosity. On the other hand, insufficient amounts of the inorganic filler can lead to insufficient mechanical strength. Therefore, the content of the inorganic filler is preferably 50 to 350 parts by mass, and more preferably 60 to 300 parts by mass, relative to 100 parts by mass of the polymerizable monomer component.

[0117] Furthermore, as described above, from the perspective of suppressing viscosity increases and sedimentation of the composition, the inorganic filler must contain at least 80% of particles having a particle size within the range of 0.05 to 5.0 μm in the particle size distribution of the inorganic filler as measured by microscopy using a scanning microscope. The proportion of particles having a particle size within this range is preferably at least 90%, more preferably at least 95%. Furthermore, from the perspective of further suppressing viscosity increases, the lower limit of the particle size of the particles comprising at least 80% of the inorganic filler is preferably 0.08 μm, more preferably 0.1 μm. From the perspective of further suppressing sedimentation, the upper limit of the particle size of the particles comprising at least 80% of the inorganic filler is preferably 2.0 μm, more preferably 1.0 μm.

[0118] As the inorganic filler, provided that the above-mentioned condition [I] is satisfied and the combination with the polymerizable monomer component also satisfies the above-mentioned condition [II], for example, inorganic powders and granules used as inorganic fillers in tooth restoration materials can be used without particular limitation. Preferred examples of the inorganic powders and granules include powders and granules formed from metals (elementary substances); powders and granules formed from metal oxides or metal composite oxides; powders and granules formed from metal salts such as metal fluorides, carbonates, sulfates, silicates, hydroxides, chlorides, sulfites, and phosphates; and mixtures of these powders and granules. Particularly suitable materials constituting the inorganic filler include metal oxides such as amorphous silica, quartz, alumina, zirconia, barium oxide, yttrium oxide, lanthanum oxide, and ytterbium oxide; silica-zirconia composite oxides such as silica-titania, 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 materials or multiple materials having different particle sizes.

[0119] Among these, amorphous silica, silica-zirconia, silica-titania, silica-titania-baria, silica-titania-zirconia, borosilicate glass, aluminosilicate glass, or fluoroaluminosilicate glass are preferably used because they easily satisfy the above-mentioned condition [II]. In addition, silica-zirconia is more preferably used because of the wear resistance of the cured product.

[0120] Furthermore, the inorganic filler can also be blended as a so-called organic-inorganic composite filler.

[0121] It should be noted that, from the aspect of good compatibility with polymerizable monomer component, improving mechanical strength, water resistance, it is preferred to process the above-mentioned inorganic filler with any surface treatment agent represented by a silane coupling agent. The surface treatment method utilizes known methods to carry out. As the silane coupling agent, methyltrimethoxysilane, methyltriethoxysilane, methyltrichlorosilane, dimethyldichlorosilane, trimethylchlorosilane, vinyltrichlorosilane, vinyltriethoxysilane, vinyltris(β-methoxyethoxy)silane, γ-methacryloyloxypropyltrimethoxysilane, methacryloyloxyoctyl-8-trimethoxysilane, γ-chloropropyltrimethoxysilane, γ-glycidoxypropylmethoxysilane, hexamethyldisilazane etc. can be enumerated.

[0122] When manufacturing dental restorations, silica-zirconia, silica-titania, silica-titania-baria, silica-titania-zirconia, and other particles are suitable due to their strong X-ray contrast properties. From the perspective of wear resistance of the cured product, silica-zirconia particles are most preferred.

[0123] <Photopolymerization Initiator>

[0124] Photopolymerization initiators must have the following function: they generate free radicals by emitting specific activating light, including light of a specific wavelength λ (nm) in the ultraviolet or visible region, from a light source mounted on a light shaping device, thereby causing free radical polymerization of the polymerizable monomer components. In other words, the photopolymerization initiator must absorb light of the specific wavelength λ (nm) to generate free radicals. The specific wavelength λ can be appropriately determined based on the wavelength of the activating light used in the light shaping device, as long as it is a wavelength in the ultraviolet or visible region. Common light shaping devices include SLA-type light shaping devices that irradiate semiconductor lasers as activating light, DLP-type light shaping devices that irradiate projector light, and LCD-type light shaping devices that irradiate liquid crystal panel light. Most light sources use activating light with a wavelength of approximately 405 nm or approximately 385 nm. In the present disclosure, it is preferred that the specific wavelength λ be 405 nm or 385 nm, and the light shaping device be of the SLA, DLP, or LCD type.

[0125] The photopolymerization initiator content can be 0.05 to 5.0 parts by mass per 100 parts by mass of the polymerizable monomer component. Excessive amounts of photopolymerization initiator can cause burrs and other defects in the resulting shaped object, resulting in reduced precision. On the other hand, too little photopolymerization initiator content can prevent the object from being molded during the molding process. Therefore, the photopolymerization initiator content is preferably 0.3 to 4.0 parts by mass, and more preferably 0.5 to 3.0 parts by mass, per 100 parts by mass of the polymerizable monomer component.

[0126] As a photopolymerization initiator, any one that satisfies the above-mentioned conditions may be appropriately selected from known photopolymerization initiators and used. The photopolymerization initiator to be selected is not particularly limited, and examples thereof include cleavage-type photopolymerization initiators, two-molecule hydrogen abstraction-type photopolymerization initiators, photoacid generators, and combinations thereof. These photopolymerization initiators may be used in combination with photosensitizers, electron-donating compounds, and the like.

[0127] Examples of suitably usable self-cleavable 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 tetrakis(pentafluorophenyl)borate; sulfonium salt compounds such as dimethylphenacylsulfonium hexafluoroantimonate; and halomethyl-substituted triazine compounds such as 2,4,6-tris(trichloromethyl)-s-triazine. Examples of photosensitizing pigments include ketone compounds, coumarin-based pigments, cyanine-based pigments, merocyanine-based pigments, thiazine-based pigments, azine-based pigments, acridine-based pigments, xanthene-based pigments, squarylium-based pigments, pyrylium salt-based pigments, condensed polycyclic aromatic compounds (anthracene, perylene, etc.), and thioxanthone-based compounds. Examples of electron donors include 4-dimethylaminobenzoate, 4-dimethylaminotoluene, p-dimethoxybenzene, 1,2,4-trimethoxybenzene, and thiophene compounds.

[0128] <Activated Light Absorber>

[0129] When using the curable composition for photomolding of the present disclosure to manufacture a molded body such as a dental restoration with high precision, in order to prevent excessive transmission of activating light irradiated from a photomolding device and thereby reduce the molding accuracy of the molded body, it is preferred that 0.01 to 2.5 parts by mass of an activating light absorber having the function of absorbing activating light irradiated from a photomolding device but not having the ability to initiate photopolymerization is contained relative to 100 parts by mass of the polymerizable monomer component.

[0130] If the content of the activating light absorber is too high, the light generated from the light source of the light shaping device during the molding process does not pass through the composition, and the above-mentioned conditions cannot be met [1]. On the other hand, if the content of the activating light absorber is too low, the precision of the resulting molded object decreases. 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, relative to 100 parts by mass of the polymerizable monomer component.

[0131] As an activating light absorber, there is no particular limitation as long as it is a compound that absorbs light irradiated from a light source mounted on a light shaping device. Examples include triazole compounds such as 2-(hydroxy-5-methylphenyl)-2H-benzotriazole and 2-(3-tert-butyl-2-hydroxy-5-methylphenyl)-5-chloro-2H-benzotriazole; benzophenone compounds such as 2,4-dihydroxybenzophenone and 2-hydroxy-4-methoxybenzophenone; and the like.

[0132] <Other ingredients>

[0133] (Polymerization Inhibitor)

[0134] In order to improve the storage stability of the curable composition for photomolding of the present disclosure, a polymerization inhibitor is preferably added in an amount ranging from 0.01 to 5.0 parts by mass per 100 parts by mass of the polymerizable monomer component. Excessive amounts of the polymerization inhibitor may result in insufficient curing of the composition during the molding process, while insufficient amounts may reduce the storage stability and molding accuracy of the composition. The amount 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 per 100 parts by mass of the polymerizable monomer component.

[0135] As the polymerization inhibitor, a compound that reacts with radicals generated in the curable composition for photomodeling to deactivate the radicals can be used, and examples thereof include di-tert-butyl-p-cresol and 4-methoxyphenol.

[0136] (Chain transfer agent)

[0137] The curable composition for photomolding of the present disclosure may contain a chain transfer agent in an amount ranging from 0.00001 to 1.0 parts by mass per 100 parts by mass of the polymerizable monomer component to reduce shrinkage stress during photomolding and improve molding accuracy. Excessive amounts of the chain transfer agent may excessively inhibit the polymerization reaction of the curable composition for photomolding, while insufficient amounts may not produce the desired effects.

[0138] Examples of chain transfer agents include thiol compounds such as butanethiol, thiophenol, mercaptoethanol, octanethiol, and dodecanethiol; 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 dibromide. Among these, α-alkylstyrene compounds, particularly α-methylstyrene dimer, are preferably used due to their high effectiveness in suppressing cracking.

[0139] (Thermal polymerization initiator)

[0140] The curable composition for photomolding of the present disclosure may contain a thermal polymerization initiator as a polymerization initiator for secondary curing. In this case, a thermal polymerization initiator with a 10-hour half-life temperature of 50-130°C is preferably used, as it does not function during primary curing and effectively remains in the laminate. Preferred thermal polymerization initiators include organic peroxides such as t-butyl peroxylaurate and benzoyl peroxide; and azo compounds such as azobisisobutyronitrile and azobis(dimethylvaleronitrile).

[0141] 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, relative to 100 parts by mass of the polymerizable monomer component.

[0142] (coloring matter)

[0143] The curable composition for photomolding of the present disclosure may contain a coloring substance within the range that satisfies the above-mentioned condition [I]. For example, when using the curable composition for photomolding of the present disclosure in the manufacture of dental restorations such as inlays, onlays, crowns, and dentures, it is preferable to contain a coloring substance in order to reproduce the color of the crowns or the 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 chromium black, chromium oxide green, chromium 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, disazo pigments, disazo condensation pigments, perylene pigments, and anthraquinone pigments; and the like.

[0144] 2. Method for producing a curable composition for photomolding

[0145] To produce the curable composition for photomodeling of the present disclosure, the materials exemplified in Items 1-3 can be used, and the components can be mixed to form a liquid, uniform composition having the above-described predetermined composition. However, the above-described conditions [I] and [II] must be satisfied. The method for producing the curable composition for photomodeling of the present disclosure is characterized by using a combination of polymerizable monomer components and inorganic fillers that satisfies specific conditions. By employing this production method, the curable composition for photomodeling of the present disclosure can be easily produced.

[0146] That is, the method for manufacturing a curable composition for photopolymerization of the present disclosure includes a mixing process 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 or multiple inorganic powders and particles, 0.01 to 5 parts by mass of a photopolymerization initiator (C) having the function of initiating photopolymerization by 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 specific activating light but not having the ability to initiate photopolymerization. In the mixing process, substances that meet all of the following conditions 1 to 4 are used as the polymerizable monomer component (A) and the inorganic filler (B).

[0147] Condition 1: When the particle size of each particle constituting the inorganic filler (B) is set to x (nm) and the circumference is set to 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 size x (nm) in the range of 0.7λ / π to 4λ / π (nm) is more than 40% of the total number of particles constituting the inorganic filler (B).

[0148] Condition 2: Regarding the inorganic powder and granules constituting the inorganic filler (B), when an inorganic powder and granules composed of aggregates of single inorganic particles having a refractive index with respect to the D line at 25°C within the range of 1.500 to 1.550 is defined as the specific inorganic powder (b1), and an inorganic powder and granules composed of aggregates of single inorganic particles having a refractive index outside the above range is defined as the non-specific inorganic powder and granules (b2), the inorganic filler (B) satisfies the following conditions:

[0149] (1) It is composed of a single specific inorganic powder (b1); or

[0150] (2) It 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

[0151] (3) It is composed of a single or multiple specific inorganic powders and particles (b1): 90% by mass or more and less than 100% by mass, and a single or multiple non-specific inorganic powders and particles (b2): greater than 0% by mass and less than 10% by mass, and at least one of the single or multiple specific inorganic powders and particles (b1) accounts for more than 10% by mass of the total mass of the inorganic filler (B).

[0152] Condition 3: Refractive index of polymerizable monomer component (A) for D line at 25°C: n M It is 1.490~1.550.

[0153] Condition 4: The refractive index of at least one specific inorganic powder (b1) accounting for 10% by mass or more of the inorganic filler (B) is equal to or greater than n. M The refractive index with the largest difference is set as nF When n F With n M The absolute value of the difference: |n F -n M |Below 0.035.

[0154] In the method for manufacturing a curable composition for photomolding of the present disclosure, a combination that meets the above criteria is selected from the polymerizable monomer components and inorganic fillers exemplified in items 1 to 3, and a photopolymerization initiator having the function of initiating photopolymerization by irradiating specific activating light is selected as the photopolymerization initiator, and an activating light absorber that absorbs the specific activating light is selected. The components are weighed 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 mixed to obtain a uniform liquid composition.

[0155] For example, in the case of manufacturing a curable composition for light shaping used in a general-purpose light shaping device equipped with a light source of a semiconductor laser having a specific wavelength λ of 405 nm and emitting a light of a wavelength of 405 nm, the particle size range of particles accounting for more than 40% of the inorganic filler is set to 90 to 514 nm, a substance that generates free radicals when irradiated with light of a wavelength of 405 nm is selected as the photopolymerization initiator, and an activated light absorber that absorbs light of a wavelength of 405 nm is selected.

[0156] It should be noted that since the commonly used light shaping devices use a light source with an activating light wavelength (peak wavelength) of 380 to 420 nm, the particle size range of particles accounting for more than 40% (preferably more than 60%, more preferably more than 80%) of the inorganic filler is 85 to 535 nm (preferably 121 to 400 nm, more preferably 218 to 375 nm), and a substance that generates free radicals when irradiated with light of a wavelength of 380 to 420 nm is selected as a photopolymerization initiator, and an activating light absorber that absorbs light of a wavelength of 380 to 420 nm is selected.

[0157] The components are preferably mixed uniformly using a stirrer at room temperature under light shielding conditions that activate the photopolymerization initiator, for example, red light, and degassing treatment is preferably performed after mixing.

[0158] The liquid composition obtained in this manner generally satisfies the above-mentioned conditions [I] and [II]. However, for reasons of higher reliability, the polymerizable monomer component (A) and the inorganic filler (B) used in the mixing step are preferably selected as follows. That is, it is preferred to use polymerizable monomer components (A) and inorganic fillers (B) that have been confirmed to have the following properties in the mixing step:

[0159] Using the polymerizable monomer component (A) and the inorganic filler (B) satisfying the above conditions 1 to 4, a base composition is separately prepared consisting of a composition consisting solely of the polymerizable monomer component (A) and the inorganic filler (B), wherein the composition ratio of these components is the same as that of the curable composition for photolithography to be produced.

[0160] Measurement using a goniophotometer is performed in which a sample having a thickness of 0.5 mm and formed from a base composition is vertically irradiated with measurement light, wherein the measurement light includes light having the specific wavelength λ (nm) described above, and is composed mainly of light within the range of λ ± 50 (nm) and exhibits a maximum intensity within this range. The light scattering index determined by the following formula based on the intensity of the transmitted light in the specific emission angle direction obtained by the measurement is: Sc (%), and the value is 10 (%) or less.

[0161] Sc={(I 70 +I 75 +I 80 ) / (I0×3)}×100

[0162] (Where, I0, I 70 , I 75 , and I 80 The intensity of the transmitted light in each direction at an emission angle of 0°, 70°, 75°, and 80° respectively.

[0163] 3. Method for manufacturing three-dimensional optically shaped objects and dental restorations of the present disclosure

[0164] The method for producing a three-dimensional optically shaped object of the present disclosure is characterized in that, in the method for producing the three-dimensional object using a liquid tank photopolymerization method comprising the aforementioned molding step, cleaning step, and secondary curing step, the curable composition for optically shaped objects of the present disclosure is used as the liquid photocurable composition supplied to the tank of the liquid tank photopolymerization apparatus. The use of the curable composition for optically shaped objects of the present disclosure in the method for producing a three-dimensional optically shaped object of the present disclosure enables the production of a three-dimensional optically shaped object having high mechanical strength and substantially no surface cracks.

[0165] In the method for manufacturing a three-dimensional optically shaped object of the present disclosure, the molding process preferably includes:

[0166] In the first step, based on the two-dimensional shape data at the height of the initial serialization order, a liquid photocurable composition held in a tank is irradiated with activating light at a predetermined position to cure the composition, thereby forming a modeling layer having a shape corresponding to the two-dimensional shape data, and the modeling layer serves as a bonded layer;

[0167] In the second step, the layer to be bonded is moved upward or downward to supply the liquid photocurable composition directly above or below the layer to be bonded in the groove;

[0168] In the third step, based on the two-dimensional shape data at the height of the next order in the serialization order in the previous step, the liquid photocurable composition supplied to the above-mentioned bonded layer is irradiated with activating light at a predetermined position to cure it, thereby forming a new modeling layer having a shape corresponding to the above-mentioned two-dimensional shape data, and bonding it to the above-mentioned bonded layer to obtain a laminate having the new modeling layer as a new bonded layer; and

[0169] In the fourth step, the stack is moved upward or downward to supply the liquid photocurable composition directly above or below the new bonded layer in the tank;

[0170] The above-mentioned new bonded layer is used as the bonded layer in the third step, and the cycle consisting of the third and fourth steps is repeated. In the final third step, a new modeling layer is formed based on the two-dimensional shape data at the height of the final serialization order to obtain a laminated body.

[0171] The liquid tank photopolymerization method including such a molding step can be suitably performed using a commercially available liquid tank photopolymerization apparatus called a so-called 3D printer.

[0172] In the method for manufacturing a three-dimensional light-molded object of the present disclosure, after the molding process, the obtained stacked body is cleaned using an organic solvent (performing a cleaning process), and then subjected to additional activating light irradiation, or heat treatment, or both, thereby causing it to undergo secondary curing (performing a secondary curing process).

[0173] Examples of the organic solvent used in the cleaning step include alcohol solvents such as ethanol, methanol, and isopropyl alcohol; ketone solvents such as acetone and methyl ethyl ketone; ether solvents such as diethyl ether, diisopropyl ether, tripropylene glycol monomethyl ether, and tetrahydrofuran; amide solvents such as N-methylpyrrolidone and dimethylacetamide; and halogenated solvents such as dichloroethane and chloroform. Among these, alcohol solvents and ether solvents are preferred due to their high cleaning effect, and alcohol solvents are more preferred due to their low environmental impact.

[0174] The wavelength of the additional activating light irradiation in the secondary curing process is not particularly limited as long as it is a wavelength at which the photopolymerization initiator remaining in the laminate absorbs and generates free radicals. In addition, the irradiation intensity of the additional activating light irradiation is preferably 5 mW / cm2 in order to generate a sufficient amount of free radicals from the photopolymerization initiator remaining in the laminate. 2 More than 10 mW / cm 2More preferably, 30 mW / cm 2 In addition, the irradiation time is not particularly limited, but is preferably 1 minute or more, more preferably 3 minutes or more, and even more preferably 5 minutes or more. It should be noted that if the irradiation intensity during the additional activating light irradiation is too strong, the shaped object will be overheated, which may cause cracks in the shaped object. Therefore, the irradiation intensity is preferably 10,000 mW / cm 2 the following.

[0175] Furthermore, when the curable composition for photomodeling of the present disclosure contains a thermal polymerization initiator, it can be used for secondary curing by heating. The heating temperature is preferably 45 to 120°C, more preferably 50 to 90°C, and even more preferably 55 to 80°C.

[0176] The method for manufacturing a dental restoration of the present disclosure is characterized in that the method for manufacturing a three-dimensional photomolded object of the present disclosure is used to manufacture dental restorations such as inlays, onlays, crowns, and dentures. In the case of manufacturing such a dental restoration, it is preferred to mix an activated light absorber with the curable composition for photomolding of the present disclosure. In addition, as the three-dimensional shape data showing the shape of the dental restoration (three-dimensional object) used in the molding process, CAD data designed based on digital data can be used, and the digital data is obtained by scanning the intraoral shape of an individual patient, an intraoral model made for an individual patient, etc. According to the method for manufacturing a dental restoration of the present disclosure, a dental restoration with high mechanical strength and no cracks on the actual surface can be manufactured.

[0177] Example

[0178] Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples.

[0179] The compounds used in Examples and Comparative Examples and their abbreviations are shown below.

[0180] (1) Polymerizable monomer component (A)

[0181] Monomer compositions A1 to A6 prepared by mixing the following monomer compounds were used.

[0182] (Monomer compound)

[0183] UDMA: urethane dimethacrylate

[0184] 3G: Triethylene glycol dimethacrylate

[0185] D-2.6E: Bisphenol A ethylene glycol (EO) adduct dimethacrylate (number of EO adducts: average 2.6)

[0186] ACMO: Acryloylmorpholine

[0187] (Monomer composition)

[0188] Monomer composition A1:

[0189] UDMA: 50 parts by mass, 3G: 20 parts by mass, D-2.6E: 30 parts by mass (refractive index n M :1.496)

[0190] Monomer composition A2:

[0191] UDMA: 36 parts by mass, 3G: 14 parts by mass, D-2.6E: 50 parts by mass (refractive index n M :1.508)

[0192] Monomer composition A3:

[0193] UDMA: 29 parts by mass, 3G: 11 parts by mass, D-2.6E: 60 parts by mass (refractive index n M :1.515)

[0194] Monomer composition A4:

[0195] 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)

[0196] Monomer composition A5: UDMA: 70 parts by mass, 3G: 30 parts by mass (refractive index n M :1.478)

[0197] Monomer composition A6: UDMA: 70 parts by mass, ACMO: 30 parts by mass (refractive index n M :1.491).

[0198] It should be noted that the refractive index n of each monomer composition is M is the refractive index for D line at 25℃. M The measurement was performed by placing each prepared monomer composition on a prism using a digital Abbe refractometer (DR-A1-PLUS, manufactured by Atago Co., Ltd.), observing the sample through an eyepiece, and reading the value of the display portion where the boundary line and the intersection of the crosshairs coincided.

[0199] (2) Inorganic filler (B)

[0200] Inorganic fillers B1 to B8 were used. The inorganic fillers B1 to B8 were obtained by using the following inorganic powders and granules as they are or by mixing two or more of these inorganic powders and granules so as to have the compositions shown in Table 1.

[0201] SZ-1: Spherical silica-zirconia (γ-methacryloyloxypropyltrimethoxysilane surface treated product, average primary particle size: 280nm, refractive index n F :1.522)

[0202] SZ-2: Spherical silica-zirconia (γ-methacryloyloxypropyltrimethoxysilane surface treated product, average primary particle size: 150nm, refractive index n F :1.522)

[0203] SZ-3: Spherical silica-zirconia (γ-methacryloyloxypropyltrimethoxysilane surface treated product, average primary particle size: 450nm, refractive index n F :1.540)

[0204] SZ-4: Spherical silica-zirconia (γ-methacryloyloxypropyltrimethoxysilane surface treated product, average primary particle size: 80 μm, refractive index n F :1.523)

[0205] SB-1: Amorphous barium glass filler (GM27884 manufactured by Shot Co., Ltd.; surface treated with γ-methacryloyloxypropyltrimethoxysilane, average primary particle size: 700 nm, refractive index: n F :1.530)

[0206] SB-2: Amorphous barium glass filler (GM27884 manufactured by Shot Co., Ltd.; surface treated with γ-methacryloyloxypropyltrimethoxysilane, average primary particle size: 200 nm, refractive index: n F :1.530)

[0207] SO-1: Spherical silica (γ-methacryloyloxypropyltrimethoxysilane surface treatment, average primary particle size: 1000nm, refractive index n F :1.450)

[0208] It should be noted that the average primary particle size and refractive index n of each inorganic filler F Measured using the method described in 1-2.

[0209] In addition, based on the particle size distribution obtained by microscopy using a scanning microscope, the content of particles with a particle size of 0.05 to 5.0 μm in all primary particles constituting each inorganic filler was measured (expressed as "specific particle content" in Table 1). Furthermore, for the inorganic fillers used in each embodiment and comparative example, based on the particle size distribution obtained by microscopy using a scanning microscope, the content of particles with a (primary) particle size with a particle size parameter α within a specific range was obtained (expressed as "α sufficient particle content" in Table 1). Specifically, the content of particles with a particle size parameter α within the range of 0.7 to 4 was obtained: R1 (%), the content of particles with a particle size parameter α within the range of 1.0 to 3.0 was obtained: R2 (%), and the content of particles with a particle size parameter α within the range of 1.8 to 2.8 was obtained: R3 (%). The results are shown in Table 1. The particle size distribution is calculated by calculating the number of all primary particles (50 or more) observed in a unit field of view of a scanning electron microscope photograph of each inorganic filler: n (particles), and the particle size (maximum diameter) of all primary particles: X i (nm) was measured and determined.

[0210] [Table 1]

[0211]

[0212] (3) Photopolymerization initiator

[0213] BAPO: Phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide (generated as free radicals by irradiation with 405 nm activating light)

[0214] TPO: 2,4,6-trimethylbenzoyl-diphenylphosphine oxide

[0215] (4) Activated light absorber

[0216] SS3: 2-(3-tert-butyl-2-hydroxy-5-methylphenyl)-5-chloro-2H-benzotriazole

[0217] (5) Inhibitor

[0218] BHT: Butylated hydroxytoluene

[0219] ·HQME:Hydroquinone methyl ether

[0220] (6) Coloring matter

[0221] Titanium oxide (average primary particle size: 200 μm)

[0222] <Example 1>

[0223] (1) Preparation of base composition for Sc evaluation and curable composition for photomolding

[0224] To 100 parts by mass of the polymerizable monomer component obtained from monomer composition A1 (50 parts by mass of UDMA, 20 parts by mass of 3G, and 30 parts by mass of D-2.6E), 150 parts by mass of SZ-1 as an inorganic filler were added, and the mixture was stirred and mixed until uniform, followed by degassing to prepare a base composition for Sc evaluation.

[0225] Separately, a base composition for raw materials was prepared in the same manner, to which were added 1.4 parts by mass of BAPO as a photopolymerization initiator, 0.7 parts by mass of SS3 as an activated light absorber, 0.1 parts by mass of HQME as a polymerization inhibitor, and 0.1 parts by mass of BHT (these amounts are relative to 100 parts by mass of the polymerizable monomer component). The mixture was stirred and mixed under red light until uniform, and then degassed to prepare a liquid curable composition for photomolding.

[0226] (2) Determination of light scattering index (Sc)

[0227] The basic composition for Sc evaluation is filled in a fluororesin mold (25mm×25mm×thickness 0.5mm). The upper and lower surfaces are pressed together with a glass slide, and after adjusting the thickness of the composition to 0.5mm, the glass slide is removed to prepare an evaluation sample. The evaluation sample is set in a three-dimensional goniophotometer (manufactured by Murakami Color Research Laboratory Co., Ltd., GP-200), and the evaluation sample is irradiated with measurement light vertically to measure the luminous distribution of the transmitted light. During the measurement, an interference filter (manufactured by Murakami Color Research Laboratory Co., Ltd., for GP-200) is set between the light source of the three-dimensional goniophotometer and the evaluation sample, and a filter with Figure 5 Light having the wavelength distribution (relative spectral distribution) shown below was used as measurement light. Based on the obtained luminous intensity distribution, the light scattering index (Sc) was calculated according to the following formula. As a result, the light scattering index Sc was 0.1 (%).

[0228] Sc=[(I 70 +I 75 +I 80 ) / I0×3]×100.

[0229] (3) Determination of activating light transmittance

[0230] The curable composition for photomolding obtained in (1) above was filled into a fluororesin mold (25 mm × 25 mm × 0.5 mm thick). The upper and lower surfaces were pressed together with a glass slide, and after adjusting the thickness of the composition to 0.5 mm, the glass slide was removed to obtain a resin composition with a thickness of 0.5 mm. The transmittance of light of 405 nm wavelength was measured using a colorimeter (Spectrophotometer SE7700 manufactured by Nippon Denshoku Industries Co., Ltd.). As a result, the transmittance was 5.30%.

[0231] (4) Manufacturing of three-dimensional light-shaped objects

[0232] The curable composition for photomolding obtained in (1) was supplied to the resin tray (tank) of a 3D printer (manufactured by DWS, DW029D; wavelength: 405 nm, irradiation intensity: 83 mW). A molding process was performed using stereolithography data (hereinafter referred to as "stl data") of a rectangular parallelepiped of 10 mm × 10 mm × 25 mm. A molded body (laminated body) having a laminated structure (obtained from a cured body of the curable composition for photomolding) was produced. The obtained molded body was then immersed in a plastic container filled with ethanol for 15 minutes, gently shaken, and washed. After drying, an additional 30 minutes of light irradiation (secondary curing) was performed using a UV CURING UNIT UVIS-2 (manufactured by DWS) to produce a three-dimensional photomolded object.

[0233] (5) Evaluation of 3D optical structures

[0234] The three-dimensional optically shaped objects obtained in (4) above were used as evaluation samples, and evaluations of molding accuracy, cracking, and three-point bending fracture strength were performed. The evaluation methods and evaluation results are shown below.

[0235] (Modeling accuracy evaluation)

[0236] The length of each side of the evaluation sample was measured in units of 0.01 mm. For each side, the measured value was divided by the set value (the length of each side set in the STL data) to obtain the value: "measured value / STL data set value." The average of these values ​​was evaluated as the average molding accuracy value. The average molding accuracy value was "1.01."

[0237] (Crack Evaluation)

[0238] The surface of the evaluation sample was observed using an optical microscope (50x magnification). After platinum coating was applied to a thickness of 5 nm, the sample was observed using a scanning microscope (1000x magnification). The number and width of cracks observed on a single surface (10 mm x 25 mm) of the evaluation sample were determined and evaluated according to the following criteria. The evaluation result was "A1."

[0239] -Evaluation Criteria-

[0240] A0: No cracks were observed on the surface of the cured product.

[0241] A1: The number of cracks observed on the surface of the cured product was 5 or less, and the crack widths were all 10 μm or less, which was within the allowable range.

[0242] A2: The number of cracks observed on the surface of the cured product was within 10, and the crack widths were all 10 μm or less, which was within the allowable range.

[0243] A3: The number of cracks observed on the surface of the cured product was within 20, and the crack widths were all 10 μm or less, which was within the allowable range.

[0244] B: The number of cracks observed on the surface of the cured product was within 20, and the crack width was 10 to 40 μm.

[0245] C: 20 or more cracks with a crack width of 10 to 40 μm were observed on the surface of the cured product.

[0246] D: Many cracks with a crack width exceeding 40 μm were observed on the surface of the cured product.

[0247] <Examples 2 to 14 and Comparative Examples 1 to 8>

[0248] The same operation as in Example 1 was carried out except that the components and the proportions used in preparing the base composition for Sc evaluation and the curable composition for photomolding in Example 1 were changed as shown in Tables 2 and 3. Thereafter, the evaluation of each composition obtained was carried out in the same manner as in Example 1, and the production and evaluation of a three-dimensional photomolded object using the obtained curable composition for photomolding was carried out in the same manner as in Example 1. The evaluation results are shown in Tables 4 and 5. In addition, the optical microscope images (magnification 50 times) taken during the observation of the crack evaluation of Example 7 (Evaluation A0), Example 11 (Evaluation A2), and Comparative Example 1 (Evaluation D) are shown in Tables 4 and 5. Figure 1 、 Figure 2 ,and Figure 3 .

[0249] <Comparative Example 9>

[0250] A curable composition for photomolding was prepared according to the method described in Example 1 of Patent Document 3. Specifically, the types of polymerizable monomer components (A) and inorganic fillers (B) shown in Table 3 were used in the mixing ratio 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 were added thereto (these mixing amounts are all mixing amounts relative to 100 parts by mass of the polymerizable monomer components). Then, a three-dimensional photomolded object using the obtained curable composition for photomolding was produced and evaluated in the same manner as in Example 1. In addition, a base composition for Sc evaluation was 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. In addition, an optical microscope image (magnification 50 times) taken during the observation of the crack evaluation of Comparative Example 9 (Evaluation C) is shown in Table 5. Figure 4 .

[0251] [Table 2]

[0252]

[0253] [Table 3]

[0254]

[0255] [Table 4]

[0256]

[0257] [Table 5]

[0258]

[0259] As shown in Table 4, the light scattering index Sc of the curable compositions for photomodeling of Examples 1 to 14 is small, and the activating light transmittance is high, so the modeling accuracy is high and the generation of cracks is suppressed. On the other hand, as shown in Table 5, the light scattering index Sc of the curable compositions for photomodeling of Comparative Examples 1 to 3 is large, and the activating light transmittance is small, so the modeling accuracy is low, and cracks are generated. In addition, although the light scattering index Sc of the curable compositions for photomodeling of Comparative Examples 4 to 7 is small, the activating light transmittance is small, so cracks are generated. The light scattering index Sc of the curable composition for photomodeling of Comparative Example 8 is large, so the modeling accuracy is low, and cracks are generated. The curable composition for photomodeling of Comparative Example 9 was prepared according to the method described in Patent Document 3, and the activating light transmittance is small, so cracks are generated.

Claims

1. A curable composition for three-dimensional photomodeling, the composition being a liquid photocurable composition for three-dimensional photomodeling used as a liquid photocurable composition in a liquid tank photopolymerization method, wherein the liquid tank photopolymerization method selectively cures the liquid photocurable composition at a predetermined position of the liquid photocurable composition held in a tank by irradiating the liquid photocurable composition at the predetermined position with activating light having a specific wavelength of λ (nm) in the ultraviolet or visible region. The curable composition for three-dimensional light modeling comprises 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 or multiple inorganic powders and particles, and 0.01 to 5 parts by mass of a photopolymerization initiator (C) having a function of initiating photopolymerization by irradiation with the activating light. In the particle size distribution of the inorganic filler (B) measured by microscopy using a scanning microscope, 80% or more of all primary particles constituting the inorganic filler (B) are particles having a particle size of 0.05 to 5.0 μm, The transmittance of a 0.5 mm thick sample obtained from the curable composition for three-dimensional light modeling measured with respect to the activating light was 1.00 to 50.00%.

2. The curable composition for three-dimensional light modeling according to claim 1, further comprising 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 a photopolymerization initiation ability. The polymerizable monomer component (A) and the inorganic filler (B) satisfy: The light scattering index Sc (%) determined by the following formula based on the intensity of transmitted light in a specific emission angle direction obtained by measurement using a goniophotometer is 10 (%) or less. In the measurement, when a composition composed solely of the polymerizable monomer component (A) and the inorganic filler (B) having the same composition ratio as the curable composition for three-dimensional light modeling is used as a base composition, a sample having a thickness of 0.5 mm formed from the base composition is irradiated perpendicularly with measurement light, the measurement light containing light of the specific wavelength: λ (nm) and having light within the range of λ±50 (nm) as a main component and consisting of light exhibiting a maximum intensity within this range, Sc={(I 70 +I 75 +I 80 ) / (I0×3)}×100 Where, I0, I 70 , I 75 , and I 80 The intensities of the transmitted light in the directions with emission angles of 0°, 70°, 75°, and 80° are shown respectively.

3. The curable composition for three-dimensional photomodeling according to claim 1 or 2, wherein: When the particle size of each particle constituting the inorganic filler (B) is set to x (nm) and the circumference is set to 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 size x (nm) in the range of 0.7λ / π to 4λ / π (nm) is more than 40% of the total number of particles constituting the inorganic filler (B).

4. The curable composition for three-dimensional light modeling according to claim 2, wherein Regarding the inorganic powder or granules constituting the inorganic filler (B), when an inorganic powder or granule composed of an aggregate of single inorganic particles having a refractive index with respect to D-line at 25° C. in the range of 1.500 to 1.550 is defined as a specific inorganic powder or granule (b1), and an inorganic powder or granule composed of an aggregate of single inorganic particles having a refractive index outside the above range is defined as a non-specific inorganic powder or granule (b2), the inorganic filler (B) satisfies the following conditions: (1) It is composed of a single specific inorganic powder (b1); or (2) It is composed of a plurality of specific inorganic powders and granules (b1), and at least one of the plurality of specific inorganic powders and granules (b1) accounts for 10% by mass or more of the total mass of the inorganic filler (B); or (3) It is composed of 90% by mass or more and less than 100% by mass of a single or multiple specific inorganic powder or particles (b1) and more than 0% by mass or less than 10% by mass of a single or multiple non-specific inorganic powder or particles (b2), 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 for D line: n M 1.490~1.550, The refractive index of at least one specific inorganic powder (b1) accounting for 10% by mass or more of the inorganic filler (B) is equal to n M The refractive index with the largest difference is set as n F When n F With n M The absolute value of the difference: |n F -n M |Below 0.

035.

5. A method for producing a curable composition for three-dimensional light 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 or multiple inorganic powders and particles, 0.01 to 5 parts by mass of a photopolymerization initiator (C) having a function of initiating photopolymerization by irradiation with activating light having a specific wavelength λ (nm) in the ultraviolet or 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 the ability to initiate photopolymerization. In the mixing step, the polymerizable monomer (A) and the inorganic filler (B) are those that satisfy all of the following conditions 1 to 4: Condition 1: Where the particle size of each particle constituting the inorganic filler (B) is denoted by x (nm) and pi is denoted by π, in the particle size distribution of the inorganic filler (B) measured by microscopy using a scanning microscope, the total number of particles having a particle size x (nm) within 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 respect to the inorganic powder and granules constituting the inorganic filler (B), when an inorganic powder and granules composed of aggregates of single inorganic particles having a refractive index with respect to D-line at 25° C. in the range of 1.500 to 1.550 is defined as a specific inorganic powder and granules (b1), and an inorganic powder and granules composed of aggregates of single inorganic particles having a refractive index outside the above range is defined as a non-specific inorganic powder and granules (b2), the inorganic filler (B) satisfies the following conditions: (1) It is composed of a single specific inorganic powder (b1); or (2) It is composed of a plurality of specific inorganic powders and granules (b1), and at least one of the plurality of specific inorganic powders and granules (b1) accounts for 10% by mass or more of the total mass of the inorganic filler (B); or (3) It is composed of 90% by mass or more and less than 100% by mass of a single or multiple specific inorganic powder or particles (b1) and more than 0% by mass or less than 10% by mass of a single or multiple non-specific inorganic powder or particles (b2), 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); Condition 3: The refractive index of the polymerizable monomer component (A) at 25°C for D line: n M 1.490~1.550; Condition 4: The refractive index of at least one specific inorganic powder (b1) accounting for 10% by mass or more of the inorganic filler (B) is equal to or greater than n. M The refractive index with the largest difference is set as n F When n F With n M The absolute value of the difference: |n F -n M |Below 0.

035.

6. The method for producing a curable composition for three-dimensional light modeling according to claim 5, wherein: In the mixing step, the polymerizable monomer component (A) and the inorganic filler (B) are used, which have been confirmed to have the following properties: Using the polymerizable monomer component (A) and the inorganic filler (B) satisfying the above conditions 1 to 4, a base composition is separately prepared, which comprises 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 photomodeling to be produced. A measurement using a goniophotometer is performed, wherein a sample having a thickness of 0.5 mm and formed from the base composition is vertically irradiated with measurement light, wherein the measurement light includes light having the specific wavelength λ (nm) and having light within a range of λ±50 (nm) as a main component and being composed of light exhibiting a maximum intensity within this range, and a light scattering index determined by the following formula based on the intensity of the transmitted light in a specific emission angle direction obtained by the measurement: Sc (%) is 10 (%) or less. Sc={(I 70 +I 75 +I 80 ) / (I0×3)}×100 Where, I0, I 70 , I 75 , and I 80 The intensities of the transmitted light in the directions with emission angles of 0°, 70°, 75°, and 80° are shown respectively.

7. A method for producing a three-dimensional optically shaped object, wherein: A three-dimensional optically shaped object is produced by irradiating a predetermined position of a liquid photocurable composition held in a tank with activating light having a specific wavelength λ (nm) in the ultraviolet or visible region to selectively cure the liquid photocurable composition at the position, the production method comprising: a molding step of digitizing and serializing the height direction of the three-dimensional object based on 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 sequenced height; irradiating the liquid photocurable composition held in the tank with the activating light at a predetermined position predetermined based on the two-dimensional shape data, thereby selectively curing the liquid photocurable composition at the position to form a molding layer having the cross-sectional shape; and sequentially forming and stacking molding layers having the cross-sectional shape at each height in the sequenced order, thereby obtaining a laminate having a shape corresponding to the shape of the three-dimensional object; a cleaning step of cleaning the laminate obtained in the molding step using an organic solvent; and A secondary curing step is performed by subjecting the laminate cleaned in the cleaning step to additional activating light irradiation, heat treatment, or both, thereby performing secondary curing. Here, as the liquid photocurable composition, the curable composition for three-dimensional photomodeling according to claim 1 is used.

8. A method for producing a dental restoration, comprising producing the dental restoration using the method for producing a three-dimensional photostructured object according to claim 7.

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