Curable composition for dental use, blank for dental cutting, method for producing silica-based complex oxide powder particles, and

Abstract

Provided is a dental cutting blank having a part to be cut, the part to be cut being formed from a mixed resin that contains spherical particles of a silica-based composite oxide and has an appearance color that does not easily change with thickness. When a starting material solution in which a condensable compound such as tetraethyl silicate or tetra (n-butoxy) zirconate is dissolved is added to an alkaline solution to precipitate silica-based composite oxide particles of a silica-based composite oxide, a radical polymerizable monomer is used in an amount of 100 parts by mass per 100 parts by mass, and the content of the radical polymerizable monomer is 100 parts by mass per 100 parts by mass per 100 parts by mass per 100 parts by mass per 100 parts by mass per 100 parts by mass per 100 parts by mass. A cured product of a dental curable composition containing 100-800 parts by mass of silica-based composite oxide particles having an average primary particle diameter of 350-600 nm is used as a portion to be cut. The silica-based composite oxide particles are composed of spherical particles of a silica-based composite oxide, which are spherical particles having a silica content of 80-92 mol% and having no silica core, and which are obtained by controlling the solvent composition of each of the solutions.

Description

Technical Field

[0001] The present invention relates to a dental curable composition, a dental cutting material, a silica-based composite oxide powder and a dental filling material. Background Art

[0002] Composite resin (hereinafter sometimes abbreviated as "CR") used for dental filling treatment is a dental curable composition that forms a cured product called hybrid resin (hereinafter sometimes abbreviated as "HR"). In addition, HR is also widely used as a material for inlays, onlays, crowns, bridges, implant superstructures, etc. used in dental repairs.

[0003] From the viewpoint of strength and the like, the dental curable composition as the raw material of HR is composed of a composition containing an inorganic filler such as silica, a polymerizable monomer such as a methacrylate resin, and a polymerization initiator. From the viewpoint of workability in cutting and polishing and high aesthetics, a powder (inorganic powder) composed of spherical inorganic oxide particles is often used as the inorganic filler (see Patent Document 1). Moreover, as the filler of the powder of spherical inorganic oxide particles, a powder composed of spherical particles of silica-based composite oxides, especially silica-zirconia oxide and other silica-titanium composite oxides, is usually used. The silica-based composite oxide is an inorganic oxide having at least one metal component selected from Groups I to IV of the periodic table and a silicon component as the main constituent components (see Patent Documents 1 to 3).

[0004] In addition, usually, the powders and granules composed of spherical particles of these silica-based composite oxides are produced by a so-called sol-gel method in which hydrolyzable (condensable) compounds such as silicon and various metal alkoxides are hydrolyzed and dehydrated and condensed in an alkaline aqueous solution. In the above-mentioned sol-gel method, after only a raw material compound of silica is added to an alkaline aqueous solution to form a silica nucleus (a seed or nucleus for particle growth), a mixture of a raw material compound of silica and a raw material compound of a metal oxide is added to grow a composite oxide layer around the above-mentioned silica nucleus, so that the particle size distribution of the obtained powder and granules can be improved (a powder and granules composed of spherical particles with uniform particle diameters are obtained) (Patent Document 3). Moreover, most of the powders and granules composed of spherical particles of silica-titanium composite oxides used as dental filling materials are also produced by such a method (for example, refer to Preparation Examples 5 and 6 of Patent Document 2).

[0005] With the development of digital technology, dental cutting blanks that have been rapidly popularized in recent years are known to have a dental cutting mixed resin blank having a cut portion composed of HR in which a silica-titanium composite oxide powder and granular body as described above is mixed (hereinafter, the dental cutting mixed resin blank is also referred to as "HR blank") (see Patent Document 4). In addition, dental cutting blanks refer to special cut bodies (also called grinding blanks) that can be installed in a cutting machine of a cutting system (CAD: Computer Aided Design) and computer-aided manufacturing (CAM: Computer Aided Manufacturing) technology (CAD / CAM system), and usually have a block-shaped cut portion of a predetermined shape made of a non-metallic material and a component for installing it in a cutting machine. Then, the cut portion is cut into a restoration shape (CAM) designed by CAD based on digital information such as the shape of the oral cavity and the shape of the model by the CAD / CAM system, thereby producing a dental restoration of the target shape with high precision.

[0006] However, when HR is used as a dental restoration material, from the perspective of aesthetics, it is necessary to use a material that is colored with a color similar to the color of natural teeth (an index consisting of a combination of mixed indicators of hue, lightness, and chroma, or an index that takes hue, lightness, and chroma into consideration. Hereinafter, the color determined by such an index will also be referred to as "shade"). There are individual differences in the color (chroma) of natural teeth, so for HR and CR products, a plurality of products colored with different specified colors (chroma) are usually prepared, and generally a product that matches the color (chroma) of the tooth to be repaired or the color (chroma) of the teeth around it is selected for use.

[0007] Such color (chromaticity) selection (usually called "colorimetry") is usually performed using a tooth color sample called a colorimetric plate. There are various colorimetric plates that are designed to facilitate color judgment by the number of color samples and the structure of the device that holds the color samples. The most popular one is the "VITA Classical" (trade name) made by VITA, which consists of 16 color samples in total and can determine the color of the restoration site by comparing the color of the restoration site and the surrounding teeth. In the VITA colorimetric plate, the colors of the A to D systems are classified according to lightness and marked with symbols. That is, they are classified into A system (reddish brown), B system (reddish yellow), C system (gray) and D system (reddish gray). If the 16 chromaticities are arranged in order of lightness (high lightness → low lightness), it is "B1→A1→B2→D2→A2→C1→C2→D4→A3→D3→B3→A3.5→B4→C3→A4→C4". When HR dental materials and CR are commercialized (productized), most of the 16 chromaticities mentioned above or several chromaticities selected from them will be available (the appearance color of HR and CR cured products will be).

[0008] Prior art literature

[0009] Patent Literature

[0010] Patent document 1: Japanese Patent Publication No. 3-10603;

[0011] Patent document 2: Japanese Patent Application Laid-Open No. 8-12305;

[0012] Patent document 3: Japanese Patent Publication No. 1-38044;

[0013] Patent document 4: Japanese Patent Application Publication No. 2017-213394. Summary of the invention

[0014] Problem that the invention aims to solve

[0015] The inventors of the present invention have conducted research and have confirmed that HR prepared by mixing silica-zirconia oxide powders of silica-zirconia oxide synthesized by a sol-gel method as described in Patent Document 2 and inorganic compositions as described in Patent Document 2 has excellent mechanical strength, wear resistance and surface smoothness. On the other hand, for the above-mentioned HR after color adjustment, it was found that the visually observed color tone sometimes differs depending on the thickness. Specifically, it was found that when the thickness of HR in the crown form is thin, the blue sense becomes stronger, and when the thickness is thick, the red sense becomes stronger. In addition, HR has a certain degree of transparency, so it is well known that the color depth of the appearance changes with thickness, but it is almost not recognized that the balance of blue and red changes according to thickness.

[0016] If the color tone changes depending on the thickness of the HR, it will cause confusion in the color comparison of HR dental materials and CR provided as products, although it depends on the degree. That is, for each product, the color tone must be determined based on the appearance color of HR (or CR cured product) with a predetermined thickness (hereinafter, also referred to as "reference thickness"), and if the thickness of the HR (or CR cured product) in actual use (processed as a repair material, filled state) is different from the reference thickness, color deviation (the degree of inconsistency in appearance color) will occur depending on the size of the difference.

[0017] For example, when the chromaticity of the HR blank having a rectangular parallelepiped portion of about 1.5 cm × 1.5 cm × 2 cm using the series of HR that causes the above-mentioned color deviation is determined based on the reference thickness of 1 mm, the apparent color of the cut portion becomes redder than the determined chromaticity. Therefore, for users who are unaware of the occurrence of the above-mentioned color deviation, not only will they misunderstand whether the chromaticity of the product is wrong, but also, when the thickness of the main part of the repaired product actually manufactured is different from the reference thickness, the desired color tone coordination cannot be obtained in theory.

[0018] Therefore, the object of the present invention is to clarify which series of HR has a balance between blue and red in the appearance color that changes depending on the thickness, to provide a dental curable composition that can form a toned HR that does not cause the above-mentioned color deviation due to thickness, and further to provide an HR blank having a cut portion composed of a toned HR that does not cause color deviation due to thickness.

[0019] Solutions for solving problems

[0020] The present invention solves the above-mentioned problems. The first mode of the present invention is a dental curable composition, which comprises: 100 parts by mass of a free radical polymerizable monomer; and 100 to 800 parts by mass of a silica-based composite oxide powder composed of spherical particles without a silica core inside, wherein the silica-based composite oxide powder is composed of a composite oxide of silicon and a metal containing at least titanium or zirconium, has a silica content of 80 to 92 mol%, and an average primary particle size of 350 to 600 nm.

[0021] In the dental curable composition of the above embodiment (hereinafter also referred to as "dental curable composition of the present invention"), the standard deviation of the average primary particle size is preferably 1.00 to 1.30.

[0022] The dental curable composition of the present invention preferably further contains a pigment.

[0023] A second aspect of the present invention is a dental cutting blank (hereinafter also referred to as "the dental cutting blank of the present invention"), characterized in that the dental cutting blank having a cut portion has a cut portion that is a cured product containing a dental curable composition.

[0024] A third aspect of the present invention is a method for producing a silica-based composite oxide powder, characterized by comprising: preparing a raw material solution by dissolving a condensable silicon compound and a condensable metal compound in a first solvent containing a first organic solvent; and

[0025] A step of adding the raw material solution to an alkaline solution containing a second solvent to hydrolyze and condense the condensable silicon compound and the condensable metal compound to precipitate a silicon dioxide-based composite oxide powder composed of spherical particles, wherein the second solvent contains a second organic solvent and water, and the spherical particles are composed of a composite oxide of silicon and a metal containing at least titanium or zirconium, and the silicon dioxide content is 80 to 92 mol%.

[0026] The first organic solvent contains 80% by mass or more of methanol.

[0027] The second organic solvent contains an alcohol having an alkyl group with 3 carbon atoms and an alcohol having an alkyl group with 4 to 5 carbon atoms in a total content of 80% by mass or more, and an alcohol having an alkyl group with 3 or less carbon atoms in a content of 5 to 50% by mass.

[0028] The raw material solution is added to the alkaline solution so that the content of the alcohol having an alkyl group with 3 to 5 carbon atoms is 65% by mass or more relative to the total mass of the first organic solvent and the second organic solvent, thereby precipitating the silica-based composite oxide powder having an average primary particle size of 350 to 600 nm and having no silica core inside the spherical particles.

[0029] In the production method of the above aspect (hereinafter also referred to as "the production method of the present invention"), the raw material solution preparation step preferably includes:

[0030] A step of mixing silicon alkoxide, methanol, water, and an acid to prepare a first composition in which a partial hydrolyzate of the silicon alkoxide and / or an oligomer obtained by condensation of the partial hydrolyzate is dissolved;

[0031] A step of mixing a metal alkoxide of the metal and a polar organic solvent that dissolves the metal alkoxide to prepare a second composition in which at least one of the metal alkoxide, a partial hydrolyzate thereof, and an oligomer obtained by condensation of the partial hydrolyzate is dissolved; and

[0032] A step of mixing the first composition and the second composition to prepare the raw material solution.

[0033] Furthermore, it is preferred that the standard deviation value of the average primary particle size be within a range of 1.00 to 1.30.

[0034] A fourth aspect of the present invention is a dental filling material, characterized in that the dental filling material is blended in a dental curable composition containing a radical polymerizable monomer.

[0035] The dental filling material is a silica-based composite oxide powder composed of spherical particles without a silica core inside. The silica-based composite oxide powder is composed of a composite oxide of silicon and a metal containing at least titanium or zirconium, has a silica content of 80 to 92 mol%, an average primary particle size of 350 to 600 nm, and a standard deviation of the average primary particle size within the range of 1.00 to 1.30.

[0036] In the dental filling material of the above embodiment (hereinafter also referred to as "the dental filling material of the present invention"), the radical polymerizable monomer is preferably a (meth)acrylic compound-based radical polymerizable monomer.

[0037] In n F The refractive index of the spherical particles at 25°C for light with a wavelength of 589 nm is expressed as n P When the refractive index of the cured product of the above radical polymerizable monomer at 25°C for light of wavelength 589 nm is represented,

[0038] Satisfy the formula: 0.01<n F -n P <0.1.

[0039] Effects of the Invention

[0040] The dental curable composition of the present invention can not only provide a cured product having good strength, easy cutting and polishing, and high aesthetics, similar to conventional dental curable compositions prepared by combining silica-based composite oxide powders and inorganic fillers, but also has the advantage that the above-mentioned color deviation caused by the thickness of the cured product is less likely to occur by using silica-based composite oxide powders (which are also the material constituting the dental filling material of the present invention) that meet specific conditions as the above-mentioned powders.

[0041] Therefore, the dental cutting blank of the present invention, which uses the cured product of the dental curable composition of the present invention as the cut part, has the advantage of not easily causing discomfort with the product, since color comparison can be performed based on the hue (chromaticity) of the appearance of the cut part, although spherical particles of silica-based composite oxide are added to the cut part.

[0042] Furthermore, according to the production method of the present invention, it is possible to efficiently produce a silica-based composite oxide powder or particulate material which is less likely to cause color deviation due to the thickness of the cured product when mixed with a dental curable composition. DETAILED DESCRIPTION

[0043] 1. Summary of the Invention

[0044] The present inventors have studied the reasons why the appearance color of HR varies depending on the thickness when a silica-zirconia oxide silica composite oxide powder or granules synthesized by a sol-gel method as described in Patent Document 2 is used for HR. As a result, the following findings were obtained: the above phenomenon is particularly significant when the spherical particles constituting the silica-zirconia oxide silica composite oxide powder or granules have a core (silicon dioxide core) consisting only of silica components, and is not easy to appear when the particles do not have such a silica core and are entirely composed of composite oxides (also referred to as coreless particles); and when it is desired to produce spherical particles of silica-titanium-based silica composite oxides such as silica-zirconia oxide without forming a silica core under conditions where the composition ratio of the titanium-based oxide is high, it is difficult to obtain a powder or granule consisting of spherical particles having a relatively large particle size such as an average primary particle size of 350 nm or more.

[0045] Therefore, further studies were conducted on conditions for producing a powder or granule having an average primary particle size of 350 nm or more and composed of spherical coreless particles of a composite oxide of silicon dioxide and a metal oxide, such as a silicon dioxide-titanium-based composite oxide. As a result, it was found that when a raw material solution obtained by dissolving a condensable silicon compound as a raw material of a silica component and a condensable metal compound as a raw material of a metal oxide component in an organic solvent (first organic solvent) is added to an alkaline aqueous solution containing ammonia water and a water-soluble organic solvent (second organic solvent) to precipitate spherical powder and particles, the above-mentioned object can be achieved in the following cases (i) to (iii), thereby completing the present invention: (i) the organic solvent (first organic solvent) contained in the above-mentioned raw material solution contains methanol as a main component, (ii) as the second organic solvent in the above-mentioned alkaline aqueous solution, an alcohol having an alkyl group having 1 to 3 carbon atoms and an alcohol having an alkyl group having 4 to 5 carbon atoms are used, and their compositions are controlled at the same time, and (iii) further, 65% by mass or more of the total mass of all organic solvents (i.e., the first and second organic solvents) in the above-mentioned alkaline solution excluding water is an alcohol having an alkyl group having 3 to 5 carbon atoms.

[0046] The spherical particles constituting the silica-based composite oxide powder obtained by the production method of the present invention do not have a silica core inside.

[0047] In addition, when using the previous silica-based composite oxide spherical powder with a silica core, the reason why the appearance color changes with the thickness of HR may not be clear, and the present invention is not bound by any theory, but the inventors think as follows. That is, it is considered that in the case of having a silica core, the silica core and the surrounding shell as a composite oxide have different refractive index differences, so the silica core is recognized as a fine particle, and in the case of thin thickness, the transmitted light causes so-called Rayleigh scattering, and the blue light in the incident light is scattered (hereinafter, the scattered light is also referred to as "blue scattered light"), so it looks bluish. In addition, in the dental curable composition comprising a silica-based composite oxide spherical powder with a silica core, in order to suppress the influence of the above-mentioned blue scattered light, the addition amount of red and yellow pigments is mostly increased. In such a case, if the thickness of the cured product becomes thicker, the color tone of the pigment will appear more strongly, and it is considered that this is one of the reasons why the color tone of the cured product looks reddish.

[0048] Here, the silica core is a particle that functions as a nucleus for particle growth and is substantially composed of only silica. The shape and size thereof are not particularly limited, but are typically spherical and have a particle diameter of 0.010 to 0.40 μm.

[0049] In addition, it is believed that the reason why large-size particles (powders with a large average primary particle size) can be obtained without silica cores by controlling the type of solvent is that the condensable silicon compound reacts with the condensable metal compound in the raw material solution to form a soluble complex (i.e., an oligomer having both silicon atoms and metal atoms in its structure), and when added to an alkaline aqueous organic solution (alkaline aqueous solution), the rate of formation of the nuclei of the particles slows down (a large number of nuclei are not formed at once), allowing the particles to grow.

[0050] As described above, it is very difficult to obtain a powder with a relatively large particle size of 350 nm or more without forming a silica core for a powder composed of spherical particles of silica-titanium composite oxides such as silica zirconia. As far as the inventors know, such a dental filling material composed of a spherical powder of large-particle silica-titanium composite oxides without a silica core is unknown. The dental curable composition of the present invention is firstly realized by the manufacturing method of the present invention that can effectively manufacture a powder of large-particle silica-titanium composite oxides without a silica core constituting such a dental filling material (i.e., the dental filling material of the present invention). Therefore, in the following "2. Details of the present invention", on the basis of explaining (1) the manufacturing method of the present invention, (2) the dental filling material of the present invention, (3) the dental curable composition of the present invention, and (4) the dental cutting blank of the present invention are described in detail.

[0051] In addition, in this specification, unless otherwise specified, an evaluation such as "x to y" using numerical values ​​x and y means "above x and below y". In this expression, when only the numerical value y has a unit, the unit also applies to the numerical value x. In addition, in this specification, a composite oxide refers to a substance formed by combining multiple oxides, and each composition thereof is a ratio of the content (molar) of a specific oxide constituting the composite oxide to the total amount (molar) of oxides constituting the composite oxide, expressed as the content rate of the specific oxide. Furthermore, the term "(meth)acrylic acid" refers to both "acrylic acid" and "methacrylic acid". Similarly, the term "(meth)acrylate" refers to both "acrylate" and "methacrylate", and the term "(meth)acryloyl" refers to both "acryloyl" and "methacryloyl".

[0052] 2. Details of the present invention

[0053] (1) Manufacturing method of the present invention

[0054] (1-1)Overview

[0055] The manufacturing method of the present invention is a method for manufacturing silica-based composite oxide powders and particles, wherein the silica-based composite oxide powders and particles are composite oxides of silicon and (one or more) metals including at least titanium or zirconium, and the content of silica (silicon oxide) is 80 to 92 (mol %), and is the same as the case of manufacturing powders and particles composed of coreless spherical particles by the so-called sol-gel method in the past, and includes the following steps of preparing the raw material solution and the step of precipitating the silica-based composite oxide powders and particles.

[0056] The silicon dioxide content, which is the silicon composition ratio, is expressed as a ratio of the silicon dioxide content (molar) to the total amount (molar) of oxides constituting the composite oxide.

[0057] Preparation step of raw material solution: a step of preparing a raw material solution by dissolving a condensable silicon compound as a raw material of a silicon dioxide component and at least one condensable metal compound as a raw material of a metal oxide component of a silicon dioxide-based composite metal oxide constituting target spherical particles in a first solvent containing a first organic solvent. Here, the first solvent may contain water. In addition, in the raw material solution, the condensable silicon compound and the condensable metal compound may react to form a soluble complex. The amount ratio of silicon atoms from the condensable silicon compound to at least one metal atom from the condensable metal compound contained in the raw material solution corresponds to the composition of the target silicon dioxide-based composite oxide. For example, in the raw material solution, condensable compounds such as tetraethyl silicate (condensable silicon compound) and tetra(n-butoxy)zirconate (condensable metal compound) are dissolved.

[0058] The precipitation process of the silica-based composite oxide powder is as follows: the raw material solution is added to an alkaline solution formed by dissolving an alkaline compound in a second solvent containing water and a second organic solvent (a water-soluble organic solvent), and the condensable silicon compound and the condensable metal compound are hydrolyzed and condensed, thereby precipitating the silica-based composite oxide powder composed of spherical particles.

[0059] The production method of the present invention is characterized in that: (i) as the organic solvent other than water in the raw material solution (first organic solvent), an organic solvent having a methanol content of 80% by mass or more is used;

[0060] (ii) as the water-soluble organic solvent (second organic solvent) in the alkaline solution, a water-soluble organic solvent is used which can contain an alcohol having a short-chain alkyl group having 1 to 5 carbon atoms, an alcohol having an alkyl group having 3 carbon atoms and an alcohol having an alkyl group having 4 to 5 carbon atoms in a total content of 80% by mass or more, and an alcohol having an alkyl group having 3 or less carbon atoms in a content of 5 to 50% by mass,

[0061] (iii) Furthermore, more than 65 mass % of the total mass of all organic solvents (the first and second organic solvents) other than water in the above-mentioned alkaline solution after adding the above-mentioned raw material solution is an alcohol having an alkyl group with 3 to 5 carbon atoms, so that in the above-mentioned precipitation step, a silica-based composite oxide powder composed of spherical particles without a silica core (a core composed only of silica) inside the particles is precipitated, and the average primary particle size of the precipitated powder is 350 to 600 nm.

[0062] In addition, when using a raw material solution with a normal concentration of a condensable silicon compound or a condensable metal compound, the concentration of organic substances such as alcohols produced by their hydrolysis is small. In addition, the influence of the organic substances is small, and it is difficult to accurately analyze the concentration of various alcohols in each solution. Therefore, the content of each alcohol specified in (i) to (iii) above is calculated based on the amount of the organic solvent used as a solvent. In addition, the average primary particle size of the silica-based composite oxide powder (inorganic powder or inorganic filler composed of spherical particles) in the present invention refers to the average primary particle size determined by image analysis based on a scanning electron microscope (SEM) image, which means the value obtained as follows: when observing the powder sample at a magnification of 5000 to 100000 times using SEM in a manner that includes 100 or more spherical particles whose overall shape can be confirmed in the field of view, based on the obtained image (or photograph), the maximum diameter (nm) of each of 30 or more particles selected at random is measured, and the sum is divided by the number: n (a natural number ≥30) to obtain the value. That is, when x is used as the value, the maximum diameter (nm) of each particle selected at random is measured based on the obtained image (or photograph). i (i is a natural number from 1 to n) represents the maximum diameter of each particle, and x AV When the average primary particle size is expressed, it is represented by x AV =(Σx i ) / n defined value. Here, when measuring the maximum diameter (nm) of each particle, commercially available image analysis software can be used. It is known that the particle size of the spherical particles obtained by the so-called sol-gel method is consistent, and there are almost no extremely large particles or extremely small particles. In the manufacturing method of the present invention, this is also the same, so it can be said that the average primary particle size determined by the above method represents the overall average primary particle size.

[0063] As mentioned above, when the conventional sol-gel method is used, it is difficult to obtain large-sized spherical particles of silica-based composite oxides without silica cores. In contrast, in the manufacturing method of the present invention, by controlling the composition of the first organic solvent in the raw material solution, the composition of the second organic solvent (the water-soluble organic solvent in the alkaline solution), the mixing ratio of the raw material solution and the alkaline solution, etc., the composition of all organic solvents (the first organic solvent and the second organic solvent) except water in the above-mentioned alkaline solution after the raw material solution is added is controlled. As a result, the nucleus formation rate and the particle growth rate can be appropriately controlled, and large-sized spherical particles of silica-based composite oxides without silica cores can be effectively obtained.

[0064] As shown in the comparative example described later, when the above-mentioned condition (i) is not satisfied and the methanol concentration in all organic solvents (first organic solvent) other than water in the above-mentioned raw material solution (hereinafter also referred to as "methanol concentration in the first organic solvent of the raw material solution") is less than 80 mass %, aggregation of particles is likely to occur, and particles with high uniformity cannot be obtained.

[0065] Furthermore, when the water-soluble organic solvent (second organic solvent) in the alkaline aqueous solution does not satisfy the above condition (ii), the particles tend to aggregate with each other, and particles with high proportion cannot be obtained, nor can the particles be grown to 350 nm or more.

[0066] Furthermore, when the above-mentioned condition (iii) is not satisfied and the concentration of alcohols having an alkyl group with 3 to 5 carbon atoms in all organic solvents (the first organic solvent and the second organic solvent) other than water in the alkaline solution after the addition of the above-mentioned raw material solution (hereinafter also referred to as "the specific alcohol concentration in the organic solvent of the alkaline solution after the addition of the raw material solution") is less than 65% by mass, the precipitation of core particles is promoted, and thus the particle size of the spherical particles of the silica-based composite oxide becomes smaller, and the particles cannot grow significantly, resulting in a powder with an average primary particle size of more than 350 nm.

[0067] From the viewpoint of effect, the methanol concentration in the first organic solvent of the raw material solution is preferably 80 to 98% by mass, and the specific alcohol concentration in the organic solvent of the alkaline solution after the addition of the raw material solution is preferably 65 to 85% by mass.

[0068] According to the production method of the present invention, for example, a powder body composed of the above-mentioned spherical particles having a narrow particle size distribution width (uniform particle size) such as a standard deviation value of the average primary particle size in the range of 1.00 to 1.30, and further in the range of 1.00 to 1.25 can be obtained. In addition, as for the shape, a powder body composed of spherical particles close to a true sphere with an average uniformity of 0.6 to 0.7, particularly 0.8 to 0.9 can be obtained.

[0069] The standard deviation of the average primary particle size is obtained by setting the standard deviation of the particle sizes of the 30 or more, preferably 100 or more spherical particles in the SEM image used to determine the average primary particle size as σ (nm). AV +σ) / x AV The average uniformity is the average value of the ratio of the short diameter to the long diameter of the spherical particles. The maximum diameter, i.e., the long diameter, of the core particles of the above n (≥30, preferably a natural number ≥100) spherical particles is defined as L. i , the diameter in the direction perpendicular to the long diameter, i.e. the short diameter, is set as B i When, according to the formula: average uniformity = {Σ(B i / L i ) / n}.

[0070] Hereinafter, each step of the production method of the present invention including the raw materials and organic solvent used will be described in detail.

[0071] (1-2) Details

[0072] (A) Raw material solution preparation process

[0073] In the raw material solution preparation step, a raw material solution is prepared by dissolving a condensable silicon compound as a raw material of a silicon (not metal) oxide, i.e., a silicon dioxide component, and at least one condensable metal compound as a raw material of a metal oxide component of a silicon dioxide-based composite metal oxide of spherical particles constituting a target powder or granule in a first solvent containing a first organic solvent. The first solvent may contain water. In the raw material solution, the condensable silicon compound and the condensable metal compound may react to form a soluble composite. In addition, the amount ratio of silicon atoms from the condensable silicon compound to at least one metal atom from the condensable metal compound contained in the raw material solution corresponds to the composition of particles constituting the target silicon dioxide-based composite oxide powder or granule.

[0074] Here, the condensable silicon compound refers to a compound that can form a silicon dioxide structure by three-dimensionally growing siloxane bonds (represented by the composition formula SiO2) through condensation, and is typically a silicon alkoxide and / or its derivatives. For example, in the first composition, the partial hydrolyzate of the silicon alkoxide formed under acidic conditions and / or the oligomer formed by condensation of the partial hydrolyzate is equivalent to the condensable silicon compound. In addition, the condensable metal compound refers to a compound that can form a structure of a stable oxide composition according to the type of metal atom by three-dimensionally growing metal atom-oxygen atom bonds through condensation, and is typically a metal alkoxide and / or its derivatives. For example, in the second composition, at least one selected from metal alkoxides, partial hydrolyzates thereof, and oligomers formed by condensation thereof is equivalent to the condensable metal compound.

[0075] In the raw material solution preparation step of the manufacturing method of the present invention, in order to effectively obtain a silica-based composite oxide powder without a silica core having an average primary particle size of 350 to 600 nm, it is necessary to make the methanol concentration in the organic solvent (first organic solvent) of the raw material solution 80 mass % or more, preferably 85 to 95 mass %.

[0076] In addition, as other organic solvents (other than methanol) accounting for 20% by mass or less, preferably 10 to 18% by mass of the total organic solvent (first organic solvent), a polar organic solvent is used, specifically, alcohols such as 2-propanol, 1-butanol, and 2-methyl-1-propanol are used. In addition, the concentration of the condensable silicon compound in the raw material solution is expressed as mol / L converted to silicon alkoxide, and is usually 1.1 to 1.9 mol / L, preferably 1.6 to 1.8 mol / L.

[0077] From the viewpoint of operability and ease of composition control, the raw material solution preparation step preferably includes: (a1) a step of mixing silicon alkoxide, methanol, water and acid to prepare a first composition (silicon dioxide component raw material composition) in which a partial hydrolyzate of silicon alkoxide and / or an oligomer (condensable silicon compound) formed by condensation of the partial hydrolyzate is dissolved (also referred to as a first composition preparation step); (a2) a step of mixing a metal alkoxide containing (one or more) metals of at least titanium or zirconium and a polar organic solvent in which the metal alkoxide is dissolved to prepare a second composition (metal oxide component raw material composition) in which at least one selected from the above metal alkoxide, its partial hydrolyzate and an oligomer (condensable metal compound) formed by condensation of the partial hydrolyzate is dissolved (also referred to as a second composition preparation step); and (a3) ​​a step of preparing the above raw material solution using the above first composition and the above second composition (also referred to as a raw material solution preparation step). The details of each of the above steps are described below.

[0078] (A1) First Composition Preparation Step

[0079] In the first composition preparation process as the raw material composition of the silica component, silicon alkoxide, methanol, water and acid are mixed to generate a condensable silicon compound in the solution. The silicon alkoxide used in this process is a compound represented by the formula Si(OR)4 (wherein R represents an alkyl group). In particular, from the viewpoint of easy control of reactivity and easy acquisition of particles with uniform particle size, it is preferred to use silicon alkoxides in which R in the formula is methyl, ethyl, isopropyl or butyl. Silicon alkoxides do not necessarily have to exist as monomers, and may also include condensates such as dimers and trimers.

[0080] The mixing method is preferably to add silicon alkoxide, water and acid to methanol maintained at 35 to 55°C in a container under stirring. At this time, the amount of methanol is preferably 2.0 to 3.0 mol / L, and particularly preferably 2.5 to 2.9 mol / L, per liter of methanol. In addition, the order of addition is not particularly limited, and silicon alkoxide may be added after adding water and acid, or water and acid may be added after adding silicon alkoxide. Water and acid may be added separately or in the form of an acid aqueous solution. As an acid, from the viewpoint of being easily available industrially, inorganic acids such as hydrochloric acid and sulfuric acid are preferred. From the viewpoint of being able to produce particles having the above-mentioned average primary particle size with high productivity, the molar ratio of water to silicon alkoxide is preferably in the range of 0.1 to 1. In addition, the amount of acid used is preferably such that the amount of protons released by the acid is 2.0×10 -5 ~1.0×10 -3Furthermore, it is preferred that stirring is continued at 35 to 55° C. for about 1 to 20 hours after the addition is completed. By reacting under such conditions, a part of the alkoxy group of the silicon alkoxide is hydrolyzed to become -OH and a part thereof is further dehydrated (or dealcoholized) and condensed to form a condensable silicon compound composed of a partial hydrolyzate and / or an oligomer formed by condensation of the partial hydrolyzate.

[0081] (A2) Second Composition Preparation Step

[0082] In the second composition preparation step as a raw material of a metal oxide component, an alkoxide of one or more metals containing at least titanium or zirconium and a polar organic solvent that dissolves the metal alkoxide are mixed. In this step, as a metal alkoxide containing titanium or zirconium, if preferred examples are given, Ti(OC3H7)4, Ti(OC4H9)4, Zr(OC4H9)4, etc. can be cited.

[0083] When a metal alkoxide other than a metal alkoxide containing titanium or zirconium (also referred to as other metal alkoxides) is used in combination, examples of other metal alkoxides preferably used include metal alkoxides of Group 2 or Group 13 of the periodic table such as Ba(OC3H7)2, Sr(OC3H7)2, Ca(OC3H7)2, Al(OC3H7)3; and alkali metal alkoxides such as sodium methoxide, sodium ethoxide, lithium methoxide, and lithium ethoxide. The amount of other metal alkoxides used in combination can be appropriately determined according to the target, and is generally 5 to 40 mol%, preferably 10 to 25 mol%, based on the total mole of the metal alkoxide containing titanium or zirconium and other metal alkoxides. It is preferred that 8 to 25 mol% of sodium methoxide be included because spherical particles of a silica-based composite oxide with few surface acid points are obtained by neutralizing the surface acid points with sodium ions.

[0084] The polar organic solvent for dissolving the metal alkoxide is not particularly limited as long as it is a polar organic solvent for dissolving the metal alkoxide actually used, but from the reason that the solubility of the metal alkoxide containing titanium or zirconium is high, it is preferred to use alcohols other than methanol such as 2-propanol, 1-butanol, 2-methyl-1-propanol. In addition, when using a variety of metal alkoxides, a variety of metal alkoxides can be dissolved in a common polar organic solvent, or solutions in polar organic solvents (different as needed) can be dissolved in advance respectively. In addition, the polar organic solvent as a solvent of the metal oxide component raw material composition can include water, but preferably does not include acid, preferably does not contain water (except water inevitably contained by impurities, etc.) and acid.

[0085] The concentration of the metal alkoxide contained in the metal oxide component raw material composition is generally 1.1 to 1.9 mol / L, preferably 1.2 to 1.8 mol / L, expressed as total mol / L of the metal alkoxide.

[0086] When other metal alkoxides are used, they do not necessarily need to be prepared as the metal oxide component raw material composition, and may be directly added to the mixture of the silica component raw material composition and the metal oxide component raw material composition obtained in the raw material solution preparation step.

[0087] (A3) Raw material solution preparation process

[0088] In the raw material solution preparation process, the first composition (silicon dioxide component raw material composition) and the second composition (metal oxide component raw material composition) are used. Specifically, the two compositions are mixed to prepare the raw material solution. The method of mixing the two compositions is not particularly limited, and preferably a method of adding the second composition to the first composition under stirring and mixing is adopted. The amount of the two compositions mixed can be determined according to the composition of the target silica-based composite oxide powder (the spherical particles constituting it), and is prepared according to the concentration of the first and second compositions (for example, the concentration of the silicon alkoxide and the metal alkoxide).

[0089] During mixing, the methanol concentration in the organic solvent (first organic solvent) of the raw material solution in the obtained raw material solution needs to be 80% by mass or more, preferably 85 to 95% by mass. It is believed that by making the above-mentioned methanol concentration 80% by mass or more, the above-mentioned condensable silicon compound (condensable silicon dioxide component raw material compound) and the above-mentioned condensable metal compound (condensable metal oxide component raw material compound) react to form a soluble complex in the raw material solution, that is, to form an oligomer having both silicon atoms and metal atoms in the structure, thereby suppressing the separation of the condensable silicon compound and the condensable metal compound during the nucleus formation in the precipitation step and the particle growth process.

[0090] In the composition of the target silica-based composite metal oxide, the silica content is 80 to 92 (mol%). Therefore, if the alkoxide concentrations in the two compositions are the same, the methanol concentration in the first organic solvent of the raw material solution is about 80% by mass or more, but based on the composition ratio, the above-mentioned methanol concentration after mixing the two compositions will be less than 80% by mass. In this case, methanol can be newly added for adjustment. The additional methanol can be added to the first composition in advance in the required amount calculated, or it can be added after mixing.

[0091] After the condensable metal compound (and other metal alkoxides directly added as needed) is added, stirring is preferably performed for about 5 to 30 minutes.

[0092] (B) Precipitation process

[0093] In the precipitation process, the raw material solution is added to an alkaline solution containing a second organic solvent miscible with water (a water-soluble organic solvent), water and an alkaline compound to carry out nucleation and particle growth, thereby precipitating spherical particles, thereby obtaining a silica-based composite oxide powder having an average primary particle size of 350 to 600 nm and composed of a silica-based composite oxide of the target composition. At this time, in order to efficiently obtain a silica-based composite oxide powder with an average primary particle size of 350 to 600 nm, as the water-soluble organic solvent (second organic solvent) in the above-mentioned alkaline solution, an alcohol having a short-chain alkyl group with 1 to 5 carbon atoms is used, and the total content of the alcohol having an alkyl group with 3 carbon atoms and the alcohol having an alkyl group with 4 to 5 carbon atoms is 80% by mass or more, preferably 85% by mass or more, and the content of the alcohol having an alkyl group with a carbon number of less than 3 is 5 to 50% by mass, preferably 6 to 40% by mass. Furthermore, after adding the above-mentioned raw material solution, more than 65% by mass of the total mass of all organic solvents (the first and second organic solvents) other than water in the above-mentioned alkaline solution is made to be an alcohol having an alkyl group with 3 to 5 carbon atoms (hereinafter also referred to as "specific alcohol").

[0094] In order to satisfy the above conditions, the water-soluble organic solvent (second organic solvent) used in the preparation of the alkaline solution needs to use an alcohol having an alkyl group with a carbon number of 3 or less and an alcohol having an alkyl group with a carbon number of 4 to 5. The water-soluble organic solvent may contain a water-soluble organic solvent other than an alcohol having an alkyl group with a carbon number of 1 to 5, typically, an alcohol having an alkyl group with a short chain of carbon atoms of 1 to 5, preferably a specific alcohol together with methanol and / or ethanol, and more preferably only consisting of a specific alcohol (that is, more preferably, the second organic solvent is a specific alcohol). As the specific alcohol, 1-propanol, 2-propanol, 1-butanol, 2-methyl-1-propanol, 1-pentanol, etc. are preferably used.

[0095] As the alkaline compound used in the alkaline solution, ammonia and sodium hydroxide are preferably used, and ammonia (water) is particularly preferred. The concentration of the alkaline component (alkaline compound) in the alkaline mixed solution is preferably in the range of 15 to 20 mol%, and the concentration of water is preferably 15 to 25 mass%.

[0096] In the precipitation process, usually no solution or solvent other than the raw material solution is added, and only the raw material solution is added to the alkaline solution. Therefore, the amount of the alkaline solution used is based on the amount of the specific alcohol in the alkaline solution, the amount of the raw material solution added, the amount and composition of the organic solvent in the raw material solution, as long as the concentration of the specific alcohol in the organic solvent of the alkaline solution after the raw material solution is added is an amount of 65 mass % or more, and it can also be used in excess, and it is preferred to calculate in advance to obtain an amount that becomes a prescribed concentration and use this amount.

[0097] There are no particular restrictions on the method of adding the raw material solution to the alkaline solution in the precipitation step. From the viewpoint of easily obtaining particles of uniform particle size, a method of continuously adding a small amount of the hydrolyzable raw material solution to the alkaline mixed solution stirred by a stirring blade, a stirrer, etc. is preferred.

[0098] In the above-mentioned precipitation process, the average primary particle size can be controlled by the temperature of the alkaline solution and the dropping time of the raw material solution. That is, from the viewpoint of improving the uniformity of the particle size, the temperature of the alkaline solution is preferably 35 to 55°C, and the higher the temperature, the smaller the particle size. There is a tendency that the longer the dropping time of the raw material solution is, the better the particle shape is. In addition, the longer the dropping time is, the larger the particle size can be. Taking the above into consideration, from the viewpoint of being able to obtain a powder with an average primary particle size of 350 to 600 nm with good productivity, it is preferred that the temperature of the reaction tank is 40 to 50°C and the dropping time is 1 to 9 hours.

[0099] After the precipitation step is completed, the precipitated powder or particles may be recovered by decantation or filtration and then dried.

[0100] (C) Other processes

[0101] In the production method of the present invention, a sintering step of sintering the powder may be performed to reduce the desolvation of the powder and the hydroxyl groups on the particle surface. In this case, the sintering temperature is preferably 700 to 1500° C. from the viewpoint of obtaining a powder having a denser crystal structure.

[0102] In addition, in order to improve the affinity of the silica-based composite oxide powder and the organic matrix of the dental curable composition, the particles can also be subjected to silane coupling treatment. As the silane coupling agent used in the silane coupling treatment, known silane coupling agents can be used without any restriction. Furthermore, in order to reduce the influence of the strong acid points on the particle surface, the surface can also be coated with silica.

[0103] (2) Dental filling material of the present invention

[0104] The silica-based composite oxide powder and granules composed of spherical particles of the silica-based composite oxide obtained by the production method of the present invention and having an average primary particle size of 350 to 600 nm are preferably used as a dental filling material (filler).

[0105] In the dental filling material of the present invention, the average primary particle size of the above-mentioned silica-based composite oxide powder (equivalent to the average particle size of the powder) is 350 to 600 nm, so the inorganic filler filling rate is improved when used in combination with inorganic particles having an average particle size of less than 100 nm, and the strength of the cured product is improved. When the above-mentioned average particle size is less than 350 nm, it is easy to cause wire drawing and stickiness when mixed with a polymerizable monomer to form a composition, and it may be difficult to mix it with the composition at a high filling rate. In addition, when the average particle size is greater than 600 nm, the polishing property may be reduced. From the viewpoint of obtaining higher strength, the average particle size is preferably 350 to 550 nm.

[0106] Each spherical particle constituting the dental filling material of the present invention only needs to be substantially spherical and does not need to be a perfect sphere. Usually, the average uniformity is 0.6 or more, preferably 0.8 or more.

[0107] The silica-based composite oxide constituting the dental filling material of the present invention can impart X-ray opacity preferred as a dental curable composition and can be adjusted to a preferred refractive index. In addition, by blending the metal oxide in the above range, the refractive index of the silica-based composite oxide powder obtained can be adjusted to a range of 1.50 to 1.58.

[0108] Furthermore, the dental filling material of the present invention is a dental curable composition containing a radical polymerizable monomer component, and is preferably a filling material for a dental curable composition in which the radical polymerizable monomer component is composed of the following (meth)acrylic compound. That is, it is preferably used as a filling material for a dental curable composition in which the radical polymerizable monomer component is composed of (only) a (meth)acrylic compound, which provides the following cured product, wherein the cured product is n F The refractive index of the spherical particles of the silica-based composite oxide constituting the silica-based composite oxide powder at 25° C. for light of a wavelength of 589 nm, expressed as n P The refractive index of the cured product of the (meth) acrylic acid compound at 25°C for light of 589 nm wavelength satisfies the formula: 0.01<n F -n P <0.1.

[0109] For such a dental curable composition, when the dental filling material of the present invention is used, even if the thickness of the cured product changes, it is not easy to cause color deviation. For example, a cured product sample A with a thickness of 1 mm and a cured product sample B with a thickness of 3 mm, which are composed of a uniform cured product of the curable composition, are prepared. The cured product of the curable composition is composed of 100 parts by mass of the above-mentioned (meth) acrylic acid compound, 200 parts by mass of the dental filling material of the present invention, and a photopolymerization initiator in an amount required for curing. When the cured product sample A and the cured product sample B are measured using a colorimeter, the spectral reflectance of the sample A at a wavelength of 450 nm is set to R A , let the spectral reflectance of sample B be R B When the formula is satisfied: 0.8≤(R B / R A )<2.0.

[0110] (3) Dental curable composition of the present invention

[0111] (3-1)Overview

[0112] The dental curable composition of the present invention is characterized in that it contains 100 parts by mass of a free radical polymerizable monomer; and 100 to 800 parts by mass of a silica-based composite oxide powder composed of spherical particles of a silica-based composite oxide, wherein the silica-based composite oxide is composed of a silica-based composite oxide of a composite oxide of silicon and (one or more) metals containing at least titanium or zirconium, and the average primary particle size of the silica-based composite oxide powder is 350 to 600 nm, and the silica content in the silica-based composite oxide is defined as the ratio of the content (molar) of silica to the total amount (molar) of oxides constituting the silica-based composite oxide, which is 80 to 92 (mol%), and the silica-based composite oxide spherical particles do not have a core (silicon dioxide core) composed only of silica inside the particle. Moreover, by satisfying such conditions, the occurrence of color deviation (change in the blue and red sense of the appearance color tone) of the cured product caused by different thicknesses can be suppressed during curing.

[0113] The powder and granules composed of the spherical particles of the above-mentioned silica-based composite oxide are produced by the production method of the present invention, and the above-mentioned silica-based composite oxide powder and granules correspond to the dental filling material of the present invention, and the details thereof are as described above. Therefore, the other components constituting the dental curable composition of the present invention are mainly described here.

[0114] (3-2) Details

[0115] (A) Radically polymerizable monomer

[0116] As the radical polymerizable monomer, (meth)acrylic acid compound-based radical polymerizable monomers such as (meth)acrylic acid compounds that can be used in dental curable compositions; cation polymerizable monomers such as epoxy and oxetane monomers, etc. can be used without limitation, and (meth)acrylic acid compounds are preferably used. If the polymerizable monomer used preferably is exemplified, methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, (meth)acrylic acid, N-(meth)acryloylglycine, N-(meth)acryloylaspartic acid, N-(meth)acryloyl-5-aminosalicylic acid, 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 2,2-bis[(3-methacryloyloxy-2-hydroxypropoxy)phenyl]propane, 2,2-bis(4-methacryloyloxyphenyl)propane, 2,2-bis(4-methacryloyloxypolyethoxyphenyl)propane, triethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, neopentyl glycol dimethacrylate, trimethylolpropane trimethacrylate, pentaerythritol tetramethacrylate, and the like can be mentioned.

[0117] As the free radical polymerizable monomer component, a plurality of free radical polymerizable monomers are usually used. At this time, from the viewpoint of reducing the light scattering caused by the refractive index difference between the organic matrix and the spherical particles of the silica-based composite oxide, thereby making the transparency of the cured product close to that of natural tooth texture, it is preferred to set the type and mixing amount of the polymerizable monomer so that the absolute value of the difference between the refractive index of the organic matrix of the cured product obtained by curing the dental curable composition of the present invention and the refractive index of the spherical particles of the silica-based composite oxide is within 0.1. Specifically, it is preferred to use a free radical polymerizable monomer composed of a (meth) acrylic acid compound that provides the following cured product, wherein the spherical particles of the silica-based composite oxide constituting the above-mentioned silica-based composite oxide powder are subjected to a temperature of 25°C and a refractive index measurement of n for light of a wavelength of 589 nm. F The refractive index of a cured product of a radical polymerizable monomer composed of a (meth)acrylic compound at 25°C for light of wavelength 589 nm is represented by n. P When expressed, the formula is satisfied: 0.01<n F -n P <0.1.

[0118] (B) Silica-based composite oxide powder composed of spherical particles

[0119] The silica-based composite oxide powder is used in the dental filling material of the present invention. The content of the silica-based composite oxide powder is preferably 100 to 800 parts by mass relative to 100 parts by mass of the radical polymerizable monomer component, and is preferably 100 to 600 parts by mass, and more preferably 200 to 500 parts by mass from the viewpoint of making the fluidity of the curable composition within an appropriate range.

[0120] (C) Polymerization initiator

[0121] As the polymerization initiator, a known polymerization initiator can be used without particular limitation, but among these, a photopolymerization initiator and a thermal polymerization initiator are preferably used.

[0122] As the photopolymerization initiator, a combination of a photosensitive compound and a tertiary amine is preferred. Among them, as the photosensitive compound, α-diketones such as camphorquinone, 9,10-phenanthrenequinone, benzil, diacetyl, acetylbenzoyl, 2,3-pentanedione, 2,3-octanedione, 4,4'-dimethoxybenzil, and acenaphthenequinone are preferred, and as the tertiary amine compound, N,N-diethyl-p-toluidine, methyl p-(N,N-dimethyl)aminobenzoate, ethyl p-(N,N-dimethyl)aminobenzoate, triethanolamine, and N-methyldiethanolamine are preferred.

[0123] In case of a thermal polymerization initiator, peroxides such as benzoyl peroxide, p-chlorobenzoyl peroxide, tert-butyl peroxy-2-ethylhexanoate, tert-butyl peroxydicarbonate, and diisopropyl peroxydicarbonate are preferred. Preferred are: azo compounds such as azobisisobutyronitrile; boron compounds such as tributylborane, tributylborane partial oxide, sodium tetraphenylborate, sodium tetra(p-fluorophenyl)borate, and triethanolamine tetraphenylborate; barbituric acids such as 5-butylbarbituric acid and 1-benzyl-5-phenylbarbituric acid; sulfinates such as sodium benzenesulfinate and sodium p-toluenesulfinate. These polymerization initiators may be used alone or in combination of two or more.

[0124] (D) Other additives

[0125] The curable composition of the present invention is preferably matched with pigments such as pigments commonly used in dental applications, and is used in a manner that the cured product becomes a specified color tone. In the case of using a silica-based composite oxide powder with a silica core, it is necessary to match the pigment component according to the thickness of the cured product during use in order to eliminate the influence of the blue scattered light from the particles, but in the curable composition of the present invention, it is not necessary to match the pigment component for such a purpose, and the desired color tone (after color matching) is not easy to change with the thickness of the cured product. The amount of pigments such as pigments is usually based on the total mass of the dental curable composition, and 800 to 8000 mass ppm is matched. In the case of using the cured product of the curable composition of the present invention as the cut portion of a dental cutting blank, it is preferred to prepare a cured product that has been toned in a manner that the color tone of the cured product is selected from the above-mentioned 16 kinds of chromaticity.

[0126] Furthermore, other additives such as a polymerization inhibitor and an ultraviolet absorber may be contained within a range not hindering the effects of the present invention.

[0127] (4) Dental cutting blank of the present invention

[0128] The dental cutting blank of the present invention has the following characteristics: the cured product of the above-mentioned dental curable composition is used as the cut part (i.e., the cut part has a cured product containing the dental curable composition of the present invention), thereby suppressing the change in the appearance color of the blank shape and the shape after cutting.

[0129] In addition to the above-mentioned features, the blank of the present invention has no special changes compared to the conventional HR blank, and may also have a retaining member such as a retaining pin for fixing to the cutting machine as required. In addition, the shape and size of the cut portion are not particularly limited, and may be a (solid) block formed into a rectangular parallelepiped or cylindrical shape, or may be a (solid) disk formed into a plate or disk shape.

[0130] The machined portion may be at least partially composed of the cured product of the dental curable composition of the present invention, and may have a so-called laminated structure in which another HR blank is laminated on the cured product of the dental curable composition of the present invention, for example.

[0131] Example

[0132] Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples.

[0133] 1. Examples, Comparative Examples, and Reference Examples Related to Production of Silica-Based Composite Oxide Powders

[0134] The abbreviations of the compounds used for producing the silica-based composite oxide powder and particulates are shown below.

[0135] <Condensable silicon compound> (also called Si oxide raw material)

[0136] ·TES: Tetraethyl silicate

[0137] <Condensation metal compound> (also called metal oxide raw material)

[0138] TBZ: Tetra(n-butoxy)zirconate

[0139] TiPT: Tetraisopropoxy titanate

[0140] ·NaOMe: sodium methoxide

[0141] <(Water-soluble) first and second organic solvents>

[0142] MeOH: methanol

[0143] Alcohols with an alkyl group having 3 carbon atoms (also called C3 alcohols)

[0144] IPA: 2-propanol

[0145] Alcohols with an alkyl group having 4 carbon atoms (also called C4 alcohols)

[0146] NBA: 1-Butanol

[0147] IBA: 2-Methyl-1-propanol

[0148] ·TBA: 2-Methyl-2-propanol

[0149] Example 1 [Production and Evaluation of Silica-Based Composite Oxide Powder F1]

[0150] (I) Production of Silica-Based Composite Oxide Powder F1

[0151] 10 g of 0.05 mass % hydrochloric acid water and 300 g of TES (manufactured by COLCOAT) as a raw material of Si oxide were dissolved in 400 g of MeOH, mixed at 40°C for 4 hours for hydrolysis, and a first composition (abbreviated as "Si raw material solution" in Table 1) was prepared. Next, 80 g of TBZ (manufactured by Nippon Soda Co., Ltd.) as a raw material of metal oxide and 50 g of C4 alcohol, i.e., IBA, as a water-soluble organic solvent were mixed to prepare a solution 1 as a second composition (abbreviated as "metal raw material solution" in Table 1). Then, the second composition was added to the first composition, stirred for 10 minutes, and 9 g of a methanol solution (solution 2) having a NaOMe concentration of 28 mass % as a second composition was further added under stirring to prepare a raw material solution.

[0152] Next, 320 g of a 25 mass % ammonia solution was added to 100 g of IPA as a C3 alcohol and 700 g of IBA as a C4 alcohol placed in a 3 L glass reaction container equipped with a stirrer to prepare an alkaline solution consisting of an ammoniacal alcohol solution.

[0153] Then, the raw material solution prepared in advance was added to the alkaline solution over 6 hours while maintaining the temperature of the reaction container at 45° C. After the addition was completed, stirring was continued for 30 minutes to obtain silica-based composite oxide powders and particles.

[0154] The powder was then collected by suction filtration and dried under reduced pressure at 80° C. to obtain a white powder. The powder was sintered at 800° C. for 4 hours to obtain a silica-based composite oxide powder F1 (hereinafter sometimes referred to as particles F1).

[0155] The conditions of the above method are summarized in Table 1. The values ​​in the raw material column in Table 1 represent the amount of each raw material used (unit: g). As shown in Table 1, the methanol content in the organic solvent (first organic solvent) in the raw material solution is 89.0% by mass, the total content of the alcohol with an alkyl group having 3 carbon atoms and the alcohol with an alkyl group having 4 to 5 carbon atoms contained in the water-soluble organic solvent (second organic solvent) in the alkaline solution is 100% by mass, the content of the alcohol with an alkyl group having 3 carbon atoms or less is 12.5% ​​by mass, and the content of the alcohol with an alkyl group having 3 to 5 carbon atoms in all organic solvents (first and second organic solvents) other than water in the alkaline solution after adding the raw material solution is 67.6% by mass. In addition, "↑" in the table means "same as above".

[0156] (II) Evaluation of Silica-Based Composite Oxide Powder F1

[0157] The average primary particle size, standard deviation of the particle size, average uniformity, and refractive index of the silica-based composite oxide powder F1 (particles F1) obtained by the above method were evaluated by the following methods.

[0158] <Method for measuring average primary particle size, standard deviation of particle size, and average uniformity of silica-based composite oxide powder>

[0159] The average primary particle size x of the silica-based composite oxide powder AV The diameter (nm) is calculated as follows: a photograph of the powder taken at a magnification of 5,000 to 100,000 times using a scanning electron microscope ("XL-30S", manufactured by Philips) is processed using image analysis software ("IP-1000PC", manufactured by Asahi Kasei Engineering Corporation), and the maximum diameter of each particle is measured for n particles (wherein n is a natural number greater than or equal to 30) randomly selected from more than 100 particles observed in a unit field of view: i (The unit is nm. i refers to a natural number from 1 to n), according to their sum Σx i The average primary particle size was calculated by the following formula.

[0160] X AV =(∑x i ) / n

[0161] In addition, the standard deviation of the average primary particle size is calculated as follows. For the 30 or more spherical particles in the SEM image used to determine the average primary particle size, the maximum diameter x of each particle is used to calculate the standard deviation of the average primary particle size. i and the average primary particle size x AV The sum of the squares of the differences (Σ(x AV -x i ) 2 ), the standard deviation of particle size σ (nm) is calculated by the following formula:

[0162] σ=〔{∑(x AV -x i ) 2} / n〕 1 / 2

[0163] The standard deviation is calculated using the following formula.

[0164] Standard deviation = {(x AV +σ) / × AV}

[0165] Furthermore, the average uniformity is calculated as follows. For each of the n (a natural number ≥ 30) spherical particles, the major diameter, which is the maximum diameter to be measured, is defined as L. i , the short diameter which is the diameter in the direction perpendicular to the long diameter is set as B i When the ratio of the two in each particle (B i / L i ) i / L i )), and the average uniformity is calculated by the following formula.

[0166] Average uniformity = {∑(B i / L i ) / n}

[0167] <Refractive index of spherical particles of silica-based composite oxide: n F Determination method>

[0168] The refractive index of the particles constituting the silica-based composite oxide powder was measured by an immersion method using an Abbe refractometer (manufactured by Ataru Co., Ltd.) (measurement wavelength: 589 nm). That is, in a constant temperature room at 25°C, 1 g of the silica-based composite oxide powder was dispersed in 50 mL of anhydrous toluene in a 100 mL sample bottle. While stirring the dispersion with a stirrer, 1-bromotoluene was added dropwise in small amounts each time, and the refractive index n of the dispersion when the dispersion became the most transparent was measured. F The obtained value is taken as the refractive index of the spherical particles of the silica-based composite oxide.

[0169] Examples 2 to 5 and 7 and Comparative Examples 1 to 4 [Production and Evaluation of Silica-Based Composite Oxide Powders F2 to F5 and F7 to F11]

[0170] The same procedure as in Example 1 was followed except that the raw materials and their amounts were changed as shown in Table 1 to obtain silica-based composite oxide powders F2 to F5 and F7 to F11 (hereinafter, sometimes also referred to as particles F7 to F11, respectively). The obtained silica-based composite oxide powders were evaluated in the same manner as in Example 1. The results are shown in Table 2.

[0171] Example 6 [Production and Evaluation of Silica-Based Composite Oxide Powder F6]

[0172] The raw materials and the amounts used were changed as shown in Table 1, and the same method as in Example 1 was used to synthesize a silica-based composite oxide powder. Next, the powder was recovered by suction filtration and dried under reduced pressure at 80°C to obtain a white powder. The powder was sintered at 700°C for 4 hours, and the obtained powder was referred to as silica-based composite oxide powder F6. The obtained silica-based composite oxide powder F6 (hereinafter sometimes referred to as particles F6) was evaluated in the same manner as in Example 1. The results are shown in Table 2.

[0173] Reference Example 1 [Production and Evaluation of Silica-Based Composite Oxide Powder F12 Having a Silica Core Structure]

[0174] 10 g of 0.05 mass % hydrochloric acid water and 270 g of TES (manufactured by COLCOAT) were dissolved in 400 g of MeOH, mixed at 40°C for 4 hours and hydrolyzed to obtain a first composition (silicon dioxide component raw material composition). Next, 80 g of TBZ (manufactured by Nippon Soda Co., Ltd.) and 50 g of IBA were mixed to obtain a second composition (metal oxide component raw material composition). Then, the second composition was added to the first composition and stirred for 10 minutes. Next, 9 g of the above-mentioned methanol solution containing 28 mass % of NaOMe as the second composition was further added to the obtained mixed solution while stirring to obtain a raw material solution.

[0175] Next, a glass reaction container with a volume of 3L with a stirrer was filled with 700g of IBA and 100g of IPA, and 320g of a 25% by mass ammonia solution was added thereto to prepare an ammoniacal alcohol solution. While keeping the temperature of the reaction container at 45°C, 30g of TES was added to the solution and stirred for 30 minutes to form silica core particles in the reaction container. While keeping the temperature of the reaction container at 45°C, it took 6 hours to add the previously prepared raw material solution thereto. After the addition was completed, stirring was continued for 30 minutes to obtain a silica-based composite oxide powder. Then, the powder was recovered by suction filtration and dried under reduced pressure at 80°C to obtain a white powder. The powder was sintered at 800°C for 4 hours, and the obtained powder was used as a silica-based composite oxide powder F12 (hereinafter sometimes referred to as particle F12). The obtained silica-based composite oxide powder F12 with a silica core was evaluated in the same manner as in Example 1. The results are shown in Table 2.

[0176] [Table 1]

[0177]

[0178] [Table 2]

[0179]

[0180] In the particles F1 to F7 manufactured by the manufacturing method of the present invention, the standard deviation value is within 1.30 and the average uniformity satisfies the substantially spherical shape, so it can be said that there is little adhesion and aggregation between the particles. In contrast, the silica-based composite oxide powders F8 and F9 manufactured under conditions that do not satisfy the conditions of the manufacturing method of the present invention have large deviations in the standard deviation values ​​and large average uniformity. It can be seen that adhesion between the particles occurred. In addition, the silica-based composite oxide powders F10 and F11 manufactured in a manner that does not satisfy the conditions of the manufacturing method of the present invention are roughly spherical, but the average primary particle size does not reach 350nm.

[0181] 2. Examples and Comparative Examples Related to Dental Curable Compositions (Non-Coloring)

[0182] The abbreviations of the compounds used for preparing the dental curable composition are shown below.

[0183] UDMA: 1,6-bis(methacryloylethyloxycarbonylamino)trimethylhexane

[0184] Bis-GMA: 2,2-Bis[(3-methacryloyloxy-2-hydroxypropoxy)phenyl]propane

[0185] ·3G: Triethylene glycol dimethacrylate

[0186] ·CQ: Camphorquinone

[0187] DMBE: ethyl p-(N,N-dimethyl)aminobenzoate

[0188] ·HQME: hydroquinone monomethyl ether.

[0189] In addition, when preparing a dental curable composition, monomer compositions (also referred to as matrices) M1 to M3 having the compositions shown in Table 3 were prepared in advance and used. In addition, the silica-based composite oxide powders F1 to F12 used in the preparation of the dental curable composition were surface treated with γ-methacryloxypropyltrimethoxysilane, and after the surface was hydrophobized, added to the matrix and mixed. In addition, the refractive index before and after curing in Table 3 was measured as follows.

[0190] <Measurement of refractive index before curing>

[0191] The measurement was performed using an Abbe refractometer (manufactured by Atok Corporation) in a constant temperature chamber at 25°C (measurement wavelength: 589 nm).

[0192] <Refractive index after curing: n P Determination of>

[0193] 0.2% by mass of camphorquinone, 0.3% by mass of ethyl p-(N,N-dimethyl)aminobenzoate, and 0.15% by mass of hydroquinone monomethyl ether were mixed and homogenized in each monomer composition and placed in a The mold with holes was pressed on both sides of the polyester film. Then, a light intensity of 500mW / cm 2 The sample was irradiated with light for 30 seconds using a halogen dental light irradiator ("Demetron LC", Sybron). After curing, the cured sample was taken out from the mold. When the sample was placed in an Abbe refractometer (manufactured by Atotron Co., Ltd.), a solvent (bromonaphthalene) that did not dissolve the sample and had a higher refractive index than the sample was added dropwise to the sample in order to prevent the sample from being in close contact with the measurement surface. The refractive index n was measured in the same manner as before curing. P Determination of.

[0194] [Table 3]

[0195]

[0196] Example 8 [Preparation and evaluation of dental curable composition CR1]

[0197] Under red light, 0.6 parts by mass of CQ, 1.0 parts by mass of DMBE, and 0.15 parts by mass of HQME were added to 100 parts by mass of the matrix M1, and mixed to prepare a uniform polymerizable monomer composition. 200 parts by mass of silica-based composite oxide powder F1 (after surface treatment) were measured in a mortar, and the above-mentioned polymerizable monomer composition was slowly added under red light, and fully kneaded with a pestle to form a uniform curable paste. The paste was further degassed to remove bubbles under reduced pressure to prepare a dental curable composition CR1. The spectral reflectance of the obtained CR1 was measured according to the evaluation method shown below. The composition and evaluation results are shown in Table 4.

[0198] <Method for measuring spectral reflectance of cured product of dental curable composition>

[0199] The prepared dental curable composition CR1 was placed in The polyester film was pressed on both sides of the mold with 1 mm and 3 mm holes. Then, the light intensity was 500 mW / cm 2The sample was irradiated with light for 30 seconds using a halogen dental light irradiator ("Demetron LC", manufactured by Sybron). After curing, it was removed from the mold and the surface was mirror-polished to prepare 1 mm thick cured sample A and 3 mm thick cured sample B. Based on the sample, a spectrophotometer (manufactured by Tokyo Denshoku, "TC-1800MKII", halogen lamp: 12V100W, measurement wavelength range 380-780nm) was used to measure the spectral reflectance using a black background color of black using a black carbon tape to obtain a spectral reflectance curve. The spectral reflectance R at a wavelength of 450nm of the spectral reflectance curve was read to determine R B / R A (The subscript R indicates the name of the cured product sample).

[0200] Examples 9, 10, 14 and Comparative Example 5

[0201] Dental curable compositions CR2, 3, 7, and 8 were produced and evaluated by the same operation as in Example 8 except that the silica-based composite oxide powder and particles described in Table 4 were used. The compositions and results are shown in Table 4. In addition, "↑" in the table means "same as above".

[0202] Examples 11 and 13

[0203] Under red light, 0.6 parts by mass of CQ, 1.0 parts by mass of DMBE, and 0.15 parts by mass of HQME were added to 100 parts by mass of the matrix M2, and mixed to prepare a uniform polymerizable monomer composition. 200 parts by mass of the silica-based composite oxide powder and granules shown in Table 4 were measured in a mortar, and the above-mentioned polymerizable monomer composition was slowly added under red light, and fully kneaded with a pestle to prepare a uniform curable paste. The paste was further degassed to remove bubbles under a reduced pressure environment to prepare dental curable compositions CR4 and CR6, which were evaluated in the same manner as in Example 8. The composition and evaluation results are shown in Table 4.

[0204] Example 12

[0205] Under red light, 0.6 parts by mass of CQ, 1.0 parts by mass of DMBE, and 0.15 parts by mass of HQME were added to 100 parts by mass of the matrix M3, and mixed to prepare a uniform polymerizable monomer composition. 200 parts by mass of the silica-based composite oxide powder F5 were measured in a mortar, and the above-mentioned polymerizable monomer composition was slowly added under red light, and fully kneaded with a pestle to prepare a uniform curable paste. The paste was further degassed to remove bubbles under a reduced pressure environment to prepare a dental curable composition CR5, which was evaluated in the same manner as in Example 8. The composition and evaluation results are shown in Table 4.

[0206] [Table 4]

[0207]

[0208] As shown in Table 4, it can be seen that CR1 to CR7 using silica-based composite oxide powders F1 to F7 without a silica core structure satisfy the spectral reflectance ratio R based on thickness. B / R A When the value is 0.8 or more and less than 2.0, the influence of blue scattered light is small. In contrast, it is found that the R of CR8 using the powder F12 having a silica core structure is B / R A Greater than 2.0, blue scattered light appears.

[0209] 3. Examples and Comparative Examples Related to Dental Cutting Blanks (HR Blanks)

[0210] The abbreviations of the polymerization initiators and pigments used in the preparation of the HR blanks are shown below.

[0211] BPO: Benzoyl peroxide

[0212] ·R: Red pigment (Pigment Red 166)

[0213] ·Y: Yellow pigment (Pigment Yellow 95)

[0214] B: Blue pigment (Pigment Blue 60)

[0215] Embodiment 15

[0216] After mixing 20 parts by mass of the matrix M1 and 1.0 parts by mass of BPO, 80 parts by mass of the silica-based composite oxide powder F1 were added and mixed with a planetary mixer until uniform, thereby gelling it. A colorant prepared by mixing 650 parts by mass of R, 1800 parts by mass of Y and 1000 parts by mass of B was added to 100 parts by mass of the above paste, and a coloring paste with a coloring of A3 chromaticity of the VITA colorimetric plate was prepared under the condition of 1 mm thickness. After vacuum degassing the coloring paste, it was filled into the above-mentioned cavity of a mold having a columnar cavity with a thickness of 14.5 mmt and a roughly rectangular cross-section of 14.5 mm×18 mm, and nitrogen pressurized at 0.4 MPa in a pressurized container, and left to stand in a heating device at 90°C. The mixture was heated for 15 hours in this state to polymerize and cure, and after cooling to room temperature at a cooling rate of 20° C. / min, it was removed from the mold to obtain a block-shaped colored HR (cured product) corresponding to the above-mentioned cavity shape.

[0217] A plate-shaped test piece with a main plane of 14.5 mm × 18 mm and a thickness of 1 mm and 3 mm was cut out from the above colored HR, and the above main plane was gloss-polished to prepare a visual evaluation test piece. The visual evaluation test piece and the VITA colorimetric plate of "A3" were arranged on a black background, and the color tone adaptability was evaluated by visual evaluation according to the following evaluation criteria. The results are shown in Table 5.

[0218] <Evaluation Criteria>

[0219] A: The color tone is in good agreement with that of the VITA color guide.

[0220] B: The color tone is similar to that of the VITA color guide.

[0221] C: The color tone is similar to that of the VITA color guide, but the adaptability is not good.

[0222] D: The color tone does not match the color tone of the VITA color guide.

[0223] Examples 16 to 21

[0224] A colored HR (cured product) was produced in the same manner as in Example 15 except that the matrix and silica-based composite oxide powders and granules used were those described in Table 5, and the same evaluations as in Example 15 were performed. The results are shown in Table 5.

[0225] Comparative Example 6

[0226] After 20 parts by mass of the matrix M1 and 1.0 parts by mass of BPO were mixed, 80 parts by mass of F12 were added and mixed until uniform using a planetary mixer to gelatinize the mixture. A colorant prepared by mixing 850 parts by mass of R, 2000 parts by mass of Y and 900 parts by mass of B was added to 100 parts by mass of the above paste, and a coloring paste having a coloring of A3 chromaticity of the VITA colorimetric plate was prepared under a thickness of 1 mm. The same operation as in Example 15 was performed for the coloring paste, polymerization was performed, a colored HR (cured product) was manufactured, and the same evaluation as in Example 15 was performed. The results are shown in Table 5.

[0227] [Table 5]

[0228]

[0229] As shown in Table 5, Examples 15 to 21 satisfying the conditions of the present invention show good color matching with the VITA colorimetric plate at both 1 mm thickness and 3 mm thickness. In contrast, in Comparative Example 6, although good color matching with the VITA colorimetric plate is shown at 1 mm thickness, the chroma appears higher (stronger color) than the VITA colorimetric plate at 3 mm thickness, and the color matching is worse than that of the Examples.

Claims

1. A dental curable composition comprising: 100 parts by mass of a radical polymerizable monomer; and 100 to 800 parts by mass of a silica-based composite oxide powder composed of spherical particles having no silica core inside, The silica-based composite oxide powder is composed of a composite oxide of silicon and a metal containing at least titanium or zirconium, has a silica content of 80 to 92 mol % and an average primary particle size of 350 to 600 nm.

2. The dental curable composition according to claim 1, wherein The standard deviation of the average primary particle size is 1.00 to 1.

30.

3. The dental curable composition according to claim 1 or 2, wherein The dental curable composition further includes a pigment. 4 . A dental cutting material having a portion to be cut comprising a cured product of the dental curable composition according to claim 1 .

5. A method for producing a silicon dioxide-based composite oxide powder, characterized in that: include: a step of preparing a raw material solution by dissolving a condensable silicon compound and a condensable metal compound in a first solvent including a first organic solvent; as well as A step of adding the raw material solution to an alkaline solution containing a second solvent to hydrolyze and condense the condensable silicon compound and the condensable metal compound, thereby precipitating a silica-based composite oxide powder composed of spherical particles, wherein the second solvent contains a second organic solvent and water, and the spherical particles are composed of a composite oxide of silicon and a metal containing at least titanium or zirconium, and the silica content is 80 to 92 mol%. The first organic solvent has a content of methanol of 80% by mass or more. The second organic solvent contains an alcohol having an alkyl group with 3 carbon atoms and an alcohol having an alkyl group with 4 to 5 carbon atoms in a total content of 80% by mass or more, and an alcohol having an alkyl group with 3 or less carbon atoms in a content of 5 to 50% by mass. The raw material solution is added to the alkaline solution so that the content of the alcohol having an alkyl group with 3 to 5 carbon atoms is 65% by mass or more relative to the total mass of the first organic solvent and the second organic solvent, thereby precipitating the silica-based composite oxide powder having an average primary particle size of 350 to 600 nm and no silica core inside the spherical particles.

6. The method for producing a silica-based composite oxide powder according to claim 5, wherein: The preparation process of the raw material solution comprises: A step of mixing silicon alkoxide, methanol, water, and an acid to prepare a first composition in which a partial hydrolyzate of the silicon alkoxide and / or an oligomer obtained by condensation of the partial hydrolyzate is dissolved; A step of mixing a metal alkoxide of the metal and a polar organic solvent that dissolves the metal alkoxide to prepare a second composition in which at least one of the metal alkoxide, a partial hydrolyzate thereof, and an oligomer obtained by condensation of the partial hydrolyzate is dissolved; and A step of mixing the first composition and the second composition to prepare the raw material solution.

7. The method for producing a spherical powder of a silica-based composite oxide according to claim 5 or 6, wherein: The standard deviation of the average primary particle size is in the range of 1.00 to 1.

30.

8. A dental filling material, which is formulated in a dental curable composition containing a radical polymerizable monomer, characterized in that: The dental filling material is a silica-based composite oxide powder composed of spherical particles without a silica core inside, the silica-based composite oxide powder is composed of a composite oxide of silicon and a metal containing at least titanium or zirconium, the silica content is 80 to 92 mol%, the average primary particle size is 350 to 600 nm, and the standard deviation of the average primary particle size is in the range of 1.00 to 1.

30.

9. The dental filling material according to claim 8, wherein The free radical polymerizable monomer is a (meth)acrylic acid compound-based free radical polymerizable monomer, In n F It represents the refractive index of the spherical particles at 25°C for light with a wavelength of 589 nm, expressed as n P When the refractive index of the cured product of the radical polymerizable monomer at 25° C. for light of 589 nm in wavelength is represented, Satisfy the formula: Formula: 0.01 <n F -n P <0.1.

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