Dental resin composition

Abstract

The present invention relates to: a dental resin composition which contains a polycarbonate (A) that comprises a carbonate unit (I) represented by formula (I), and an inorganic particulate filler (B), wherein the inorganic particulate filler (B) has an average primary particle diameter of 2.5 µm or less and an aspect ratio of 1 or more and less than 10; a method for producing the dental resin composition; and a dental molded body which contains the dental resin composition and a method for producing the dental molded body.

Description

Dental resin composition

[0001] The present invention relates to a dental resin composition and a method for producing the same, as well as a dental molded article made from the dental resin composition and a method for producing the same.

[0002] In recent years, the use of CAD / CAM systems, which allow dental prostheses such as inlays and crowns to be designed by computer and then milled using a milling machine, has been increasing. In these systems, blocks of appropriate sizes, such as rectangular parallelepipeds, cylinders, or disks, are supplied, and the blocks are then milled into restorations in the shape of a crown or arch of teeth. Various materials have been proposed for the blocks, including glass ceramics, zirconia, titanium, acrylic resins, and composites containing polymer resins and inorganic fillers.

[0003] Among these block materials, composite materials containing hardening resin and inorganic filler, known as resin blocks, are widely used because they can easily be applied with conventional dental filling and restorative material technology and are easy to adjust color tone. However, resin blocks are brittle and prone to cracking, chipping, and fissures, and because they do not melt, cutting chips cannot be reused.

[0004] In response to these challenges, attempts have been made in recent years to develop composite materials containing super engineering plastics, a type of thermoplastic resin, and inorganic fillers. For example, Patent Document 1 proposes dental block materials made of high-strength materials derived from rigid aromatic skeletons, such as polyetheretherketone (PEEK), polyetherketoneketone (PEKK), and polycarbonate (PC). Furthermore, Patent Documents 2 and 3 report examples of applying polycarbonates with an isosorbide skeleton, which are superior in strength to conventional polycarbonates, to dental molded articles.

[0005] JP 2022-119683 A JP 2014-161547 A International Publication No. 2017 / 199925

[0006] However, the dental block material made of PEEK and PEKK described in Patent Document 1 has problems in terms of moldability, since PEEK and PEKK require processing temperatures of nearly 400°C. Furthermore, PC has a problem in that its flexibility makes it prone to insufficient strength. On the other hand, the dental molded articles described in Patent Documents 2 and 3 have a problem in that the history of the flow direction during molding remains, making it easy to observe anisotropy in strength. Therefore, an object of the present invention is to provide a dental resin composition that has excellent moldability, and the resulting molded articles have excellent flexural strength and flexural modulus, and the anisotropy of the flexural strength is small.

[0007] The present inventors have conducted extensive research and found that the above-mentioned problems can be solved by providing a dental resin composition that satisfies certain requirements. That is, the present invention encompasses the following inventions: [1] A dental resin composition comprising a polycarbonate (A) containing carbonate units (I) represented by the following formula (I) and an inorganic particulate filler (B), wherein the inorganic particulate filler (B) has an average primary particle diameter of 2.5 μm or less and an aspect ratio of 1 or more and less than 10: [2] The dental resin composition according to [1], wherein the content of the unit (I) in the polycarbonate (A) is 15 to 98 mol % based on 100 mol % of all carbonate units. [3] The dental resin composition according to [1] or [2], wherein the polycarbonate (A) contains carbonate units (D) derived from at least one compound selected from the group consisting of a linear aliphatic diol compound, a branched diol compound, and an alicyclic diol compound. [4] The dental resin composition according to [3], wherein the molar ratio of the unit (I) to the unit (D) in the polycarbonate (A) [(I) / (D)] is 15 / 85 to 98 / 2. [5] The dental resin composition according to any one of [1] to [4], wherein the content of the polycarbonate (A) is 40 to 99 mass % based on 100 mass % of the dental resin composition. [6] The dental resin composition according to any one of [1] to [5], wherein the refractive index of the inorganic particulate filler (B) is 1.35 to 1.65. [7] A dental molded article comprising the dental resin composition according to any one of [1] to [6]. [8] The dental molded article according to [7], which is composed of a laminate. [9] The dental molded article according to [7] or [8], which is a dental mill blank.

[10] The dental molded article according to [7] or [9], which is for a dental crown or a denture base.

[11] The dental molded article according to [8] or [9], which is for a dental crown or a denture base.

[12] A method for producing the dental resin composition according to any one of [1] to [6], which comprises a step of melt-kneading at least the polycarbonate (A) and the inorganic particulate filler (B).

[13] A method for producing a dental resin composition according to the above

[12] , wherein the melt-kneading is carried out using a twin-screw extruder, and the L / D of the twin-screw extruder is not less than 25.

[14] A method for producing a dental resin composition according to the above

[12] or

[13] , wherein the melt-kneading temperature during the melt-kneading is not more than 360° C.

[15] A method for producing a dental molded article, comprising a step of injection-molding the dental resin composition according to any one of the above [1] to [6] to form a part or all of the dental molded article.

[16] A method for producing a dental molded article, comprising a step of press-molding the dental resin composition according to any one of [1] to [6] above to form a part or all of the dental molded article.

[17] A method for producing a dental molded article according to

[15] above, wherein the processing temperature is 360°C or less.

[18] A method for producing a dental molded article according to

[16] above, wherein the processing temperature is 360°C or less.

[19] The dental molded article according to any one of [7] to [9] above, which is for a dental crown or a denture base.

[20] A method for producing a dental molded article, comprising injection molding or press-molding the dental resin composition according to any one of [1] to [6] above to form a part of the dental molded article, and then laminating a plurality of parts of the molded articles and press-molding them to form a part or all of the dental molded article.

[0008] According to the present invention, it is possible to provide a dental resin composition which has excellent moldability, and which gives a molded article having excellent flexural strength and flexural modulus, and which has small anisotropy of the flexural strength.

[0009] The present invention will be described in detail below using examples of embodiments (hereinafter also referred to as "one aspect of the present invention"). In this specification, the upper and lower limits of numerical ranges (e.g., the content of each component, each physical property, each condition in the production method, and a value calculated from each numerical value) can be combined as appropriate. For example, in this specification, the lower and upper limits of numerical ranges described in stages can be independently combined. For example, a description of "preferably 10 to 90 mass%, more preferably 20 to 80 mass%" for the same item can be combined with the "preferable lower limit (10 mass%)" and the "more preferable upper limit (80 mass%)" to obtain "10 to 80 mass%," or with the "more preferable lower limit (20 mass%)" and the "preferable upper limit (90 mass%)" to obtain 20 to 90 mass%. Furthermore, for example, based on the above description, the upper limit value can be specified as "10% by mass or more" or "20% by mass or more" without any particular upper limit value. Similarly, the upper limit value can be specified as "90% by mass or less" or "80% by mass or less" without any particular lower limit value. Unless otherwise specified, the expression "XX to YY% by mass" as a numerical range means "XX% by mass or more and YY% by mass or less" (XX represents the lower limit, and YY represents the upper limit). For example, simply describing a numerical range as "10 to 90% by mass" indicates a range of 10% by mass or more and 90% by mass or less. Similarly, for example, from the expression "preferably 10% by mass or more, more preferably 20% by mass or more" and the expression "preferably 90% by mass or less, more preferably 80% by mass or less" for the same item, the "preferable lower limit (10% by mass or more)" and the "more preferable upper limit (80% by mass or less)" can be combined to form "10% by mass or more and 80% by mass or less." Similarly, the lower limit can be specified as "10% by mass or more" or "20% by mass or more," and the upper limit can be specified as "90% by mass or less" or "80% by mass or less." The same applies when the numerical range includes a "more preferable range" or an "even more preferable range." The same applies when the upper limit of the numerical range is "less than" or the lower limit is "more than."That is, for example, based on the description "preferably more than 10 and less than 90, more preferably 20 to 80," the upper and lower limits can be combined to form "more than 10 and less than 80" or "20 to less than 90." The above-mentioned numerical ranges are merely examples of the content in terms of mass %, and the same applies to numerical ranges such as parts by mass. As described above, the same also applies to each physical property, each condition in the manufacturing method, other numerical ranges, and values ​​calculated from each numerical value. The present invention includes various combinations of all or part of the embodiments described herein within the scope of the technical concept of the present invention, as long as the effects of the present invention are achieved. Furthermore, embodiments in which the details described herein are arbitrarily selected or arbitrarily combined are also included in the present invention. In this specification, preferred embodiments are shown, but combinations of two or more individual preferred embodiments are also preferred. Preferred specifications can be selected arbitrarily, and for example, combinations of preferred specifications can be considered more preferable.

[0010] In this specification, unless otherwise specified, "moldability" refers to the moldability of a dental resin composition according to an embodiment of the present invention, specifically a property evaluated by the method described in the Examples. In this specification, unless otherwise specified, "strength" refers to the "flexural strength" and "flexural modulus" of a dental resin composition according to an embodiment of the present invention. The "flexural strength" and "flexural modulus" are each evaluated using a molded article molded from the resin composition, specifically a property evaluated by the method described in the Examples. Excellent strength of a dental resin composition can also improve the strength of molded articles produced from the dental resin composition. In this specification, unless otherwise specified, "anisotropy" refers to the "flexural strength anisotropy" of a dental resin composition according to an embodiment of the present invention, specifically a property evaluated using a molded article molded from the resin composition, specifically a property evaluated by the method described in the Examples. Small anisotropy of a dental resin composition can also reduce the flexural strength anisotropy of molded articles produced from the dental resin composition. Furthermore, in this specification, unless otherwise specified, the terms "transparency" and "adhesion" refer to the properties of the dental resin composition of one embodiment of the present invention, and are each evaluated using a molded article molded from the resin composition, specifically, by the method described in the Examples. Excellent transparency of a dental resin composition can improve the transparency of a molded article produced from the dental resin composition. Similarly, excellent adhesion of a dental resin composition can improve the adhesion of a molded article produced from the dental resin composition.

[0011] [Dental Resin Composition] A dental resin composition (also referred to as "resin composition" herein) that is one embodiment of the present invention contains a polycarbonate (A) (also referred to as "component (A)" herein) containing carbonate units (I) represented by the following formula (I), and an inorganic particulate filler (B) (also referred to as "component (B)" herein), wherein the inorganic particulate filler (B) has an average primary particle diameter of 2.5 μm or less and an aspect ratio of 1 or more and less than 10.

[0012]

[0013] <Polycarbonate (A)> The polycarbonate (A) contains carbonate units (I) represented by the formula (I) (also abbreviated as "units (I)" in this specification). By including component (A), the resin composition has excellent moldability and strength, and furthermore, the anisotropy of bending strength is reduced. Furthermore, the resin composition has excellent transparency and affinity with dental adhesives.

[0014] (Carbonate Unit (I)) The unit (I) has a stereoselective, bulky, and rigid ring structure, which allows component (A) to exhibit strength and reduce the difference in strength with the inorganic particulate filler (B). In addition, the unit (I) has a cyclic ether structure with a fixed conformation, which is presumed to have affinity for inorganic particles and facilitate uniform mixing of component (A) and component (B). Therefore, from the viewpoint of more easily achieving the effects of the present invention, the content of the unit (I) in component (A) is preferably 15 to 98 mol%, more preferably 30 to 95 mol%, and even more preferably 50 to 90 mol%, based on 100 mol% of all carbonate units.

[0015] Examples of the formula (I) include carbonate units (I-1), (I-2), and (I-3) represented by the following formulas, which are stereoisomers (also abbreviated as "unit (I-1)," "unit (I-2)," and "unit (I-3)," respectively, in this specification.) In other words, the unit (I) represented by the formula (I) is a unit containing at least one selected from the group consisting of the unit (I-1), unit (I-2), and unit (I-3).

[0016]

[0017]

[0018]

[0019] The units (I-1), (I-2), and (I-3) are carbonate units derived from diols called isosorbide, isomannide, and isoidide, respectively. In other words, the unit (I) represented by formula (I) is a carbonate unit derived from at least one selected from the group consisting of isosorbide, isomannide, and isoidide. In this specification, the term "carbonate unit derived from ZZ" refers to a carbonate unit obtained using "ZZ" as a raw material (ZZ represents the raw material compound). In other words, it can also be called a "carbonate unit derived from ZZ." The diol from which these units are derived is preferably an ether group-containing diol derived from a carbohydrate and obtained from natural biomass. When obtained from natural biomass, it is considered a renewable resource. Isosorbide can be obtained, for example, by hydrogenating D-glucose obtained from starch and then dehydrating it. Other ether diols can also be obtained by similar reactions, except for the starting material. Among isosorbide, isomannide, and isoidide, the carbonate unit (I-1) derived from isosorbide (1,4:3,6-dianhydrosorbitol) is preferred because it is easy to produce and has excellent heat resistance, and therefore the resin is less likely to deteriorate during molding processing of polycarbonate.

[0020] The content of the unit (I-1) in the unit (I) is preferably 50 to 100 mol %, more preferably 70 to 100 mol %, even more preferably 80 to 100 mol %, and still more preferably 90 to 100 mol %, based on 100 mol % in total of the unit (I-1), the unit (I-2), and the unit (I-3).

[0021] (Carbonate Unit (D)) Component (A) preferably contains carbonate units (D) (also abbreviated as "units (D)" in this specification) derived from at least one compound selected from the group consisting of linear aliphatic diols, branched aliphatic diol compounds, and alicyclic diol compounds. The alicyclic diol compounds are diol compounds containing, in their molecular structure, one or more saturated or unsaturated carbon rings that do not have aromaticity and are formed by the bonding of carbon atoms. These compounds do not include diols containing only a ring containing a heteroatom within the ring, such as the aforementioned isosorbide, isomannide, and isoidide. In other words, the units (D) do not contain the units (I). The content of the units (D) in component (A) is preferably 2 to 85 mol %, more preferably 5 to 70 mol %, and even more preferably 10 to 50 mol %, based on 100 mol % of all carbonate units.

[0022] The number of carbon atoms in the linear aliphatic diol compound is preferably 2 to 30, more preferably 4 to 20, and even more preferably 6 to 18. Specific examples of the linear aliphatic diol compound include ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, neopentyl glycol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 2-ethyl-1,6-hexanediol, 2,2,4-trimethyl-1,6-hexanediol, 1,10-decanediol, 1,12-dodecanediol, hydrogenated dilinoleyl glycol, and hydrogenated dioleyl glycol. Of these, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, 1,9-nonanediol, and 1,10-decanediol are preferred.

[0023] The number of carbon atoms in the branched aliphatic diol compound is preferably 3 to 30, more preferably 3 to 20, and even more preferably 4 to 12. Specific examples of the branched aliphatic diol compound include 1,3-butylene glycol, 2-methyl-1,3-propanediol, neopentyl glycol, 3-methyl-1,5-pentanediol, 2-n-butyl-2-ethyl-1,3-propanediol, 2,2-diethyl-1,3-propanediol, 2,4-diethyl-1,5-pentanediol, 1,2-hexane glycol, 1,2-octyl glycol, 2-ethyl-1,3-hexanediol, 2,3-diisobutyl-1,3-propanediol, 2,2-diisoamyl-1,3-propanediol, and 2-methyl-2-propyl-1,3-propanediol. Of these, 3-methyl-1,5-pentanediol, 2-n-butyl-2-ethyl-1,3-propanediol, 2,2-diethyl-1,3-propanediol, and 2,4-diethyl-1,5-pentanediol are preferred.

[0024] The alicyclic diol compound preferably has 6 to 30 carbon atoms, more preferably 6 to 20 carbon atoms, and even more preferably 6 to 15 carbon atoms. Specific examples of the alicyclic diol compound include cyclohexanediols such as 1,2-cyclohexanediol, 1,3-cyclohexanediol, 1,4-cyclohexanediol, and 2-methyl-1,4-cyclohexanediol; cyclohexanedimethanols such as 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, and 1,4-cyclohexanedimethanol; norbornanedimethanols such as 2,3-norbornanedimethanol and 2,5-norbornanedimethanol; tricyclodecane dimethanol, pentacyclopentadecanedimethanol, 1,3-adamantanediol, 2,2-adamantanediol, 1,5-decalindimethanol, 2,3-decalindimethanol, 2,2,4,4-tetramethyl-1,3-cyclobutanediol, and 3,9-bis(2-hydroxy-1,1-dimethylethyl)-2,4,8,10-tetraoxaspiro[5.5]undecane. Of these, 1,4-cyclohexanedimethanol, tricyclodecanedimethanol, and 3,9-bis(2-hydroxy-1,1-dimethylethyl)-2,4,8,10-tetraoxaspiro[5.5]undecane are preferred.

[0025] These aliphatic diol compounds and alicyclic diol compounds may be used alone or in combination of two or more.

[0026] In one embodiment of the component (A), the component (A) may contain carbonate units derived from an aromatic diol compound, as long as the effects of the present invention are not impaired. Examples of the aromatic diol compound include 1,3-bis[2-(4-hydroxyphenyl)-2-propyl]benzene (also known as "bisphenol M"), 9,9-bis(4-hydroxy-3-methylphenyl)fluorene, 1,1-bis(4-hydroxyphenyl)cyclohexane, 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane, 4,4'-dihydroxy-3,3'-dimethyldiphenyl sulfide, 2,2'-bis(4-hydroxyphenyl)propane (also known as "bisphenol A"), 2,2-bis(4-hydroxy-3-methylphenyl)propane (also known as "bisphenol C"), 2,2-bis(4-hydroxyphenyl)-1,1,1,3,3,3-hexafluoropropane (also known as "bisphenol AF"), and 1,1-bis(4-hydroxyphenyl)decane.

[0027] However, it is preferable that component (A) is substantially free of carbonate units derived from an aromatic diol compound. Specifically, the term "substantially free of carbonate units derived from an aromatic diol compound" means that the content of carbonate units derived from the aromatic diol compound in component (A) is 0 to 5 mol%, preferably 0 to 2 mol%, more preferably 0 to 1 mol%, even more preferably 0 to 0.5 mol%, still more preferably 0 to 0.1 mol%, and even more preferably 0 to 0.01 mol%, based on 100 mol% of all carbonate units. It is even more preferable that the content of carbonate units derived from the aromatic diol compound in component (A) is 0 mol%, based on 100 mol% of all carbonate units.

[0028] In one embodiment of the present invention, it is more preferable that component (A) is substantially free of carbonate units having a bisphenol skeleton. Specifically, the term "substantially free of carbonate units having a bisphenol skeleton" means that the content of carbonate units having a bisphenol skeleton in component (A) is 0 to 5 mol%, preferably 0 to 2 mol%, more preferably 0 to 1 mol%, even more preferably 0 to 0.5 mol%, still more preferably 0 to 0.1 mol%, and even more preferably 0 to 0.01 mol%, based on 100 mol% of all carbonate units. It is even more preferable that the content of carbonate units having a bisphenol skeleton in component (A) is 0 mol%, based on 100 mol% of all carbonate units.

[0029] As described above, it is preferable that the component (A) contains the unit (I) and further contains the unit (D). The molar ratio of the unit (I) to the unit (D) [(I) / (D)] is preferably 15 / 85 to 98 / 2. The molar ratio [(I) / (D)] is more preferably 30 / 70 to 90 / 10, even more preferably 40 / 60 to 90 / 10, still more preferably 50 / 50 to 90 / 10, and even more preferably 60 / 40 to 90 / 10. When the molar ratio [(I) / (D)] is 15 / 85 or more, the heat resistance of the component (A) is likely to be enhanced. On the other hand, when the molar ratio [(I) / (D)] is 98 / 2 or less, the melt viscosity is unlikely to be high and moldability is likely to be improved, which is preferable. The content (mol %) of each carbonate unit and the molar ratio [(I) / (D)] can be determined for polycarbonate (A) using, for example, a high-resolution Fourier transform nuclear magnetic resonance spectrometer (FT-NMR) (model: JNM-AL400, manufactured by JEOL Ltd.) or a Fourier transform nuclear magnetic resonance spectrometer (FT-NMR) (model: ECX400, manufactured by JEOL Ltd.). １ It can be calculated by measuring with H-NMR. Specifically, it can be calculated by the method described in the examples.

[0030] In the component (A), the total content of the units (I) and the units (D) is preferably 70 to 100 mol%, more preferably 80 to 100 mol%, even more preferably 90 to 100 mol%, still more preferably 95 to 100 mol%, and even more preferably 98 to 100 mol%, based on 100 mol% of all carbonate units. As described above, the component (A) preferably does not contain any carbonate units having a bisphenol skeleton. In an embodiment in which the component (A) does not contain any carbonate units having a bisphenol skeleton, the total content of the units (I) and the units (D) in the component (A) may be 100 mol%.

[0031] The content of component (A) in the resin composition is preferably 40 to 99% by mass, more preferably 45 to 95% by mass, and even more preferably 50 to 90% by mass, based on 100% by mass of the resin composition. A content of component (A) of 40 to 99% by mass is preferred because it can reduce the anisotropy of bending strength and improve strength. Furthermore, a content of component (A) of 40 to 99% by mass is also preferred from the viewpoint of maintaining good transparency.

[0032] In one aspect of the present invention, the resin composition preferably contains substantially no polycarbonate having a bisphenol skeleton. Specifically, the term "substantially no polycarbonate having a bisphenol skeleton" means that the content of polycarbonate having a bisphenol skeleton in the resin composition is 0 to 5% by mass, preferably 0 to 2% by mass, more preferably 0 to 1% by mass, even more preferably 0 to 0.5% by mass, still more preferably 0 to 0.1% by mass, and even more preferably 0 to 0.01% by mass, based on 100% by mass of the resin composition. It is even more preferable that the content of polycarbonate having a bisphenol skeleton in the resin composition is 0% by mass, based on 100% by mass of the resin composition.

[0033] In one embodiment of the present invention, the MFR of the component (A) at a temperature of 230°C under a load of 21.2 N is preferably 1.0 to 25 g / 10 min, more preferably 2.5 to 20 g / 10 min, and even more preferably 5.0 to 15 g / 10 min.

[0034] Component (A) is produced by a known reaction means for producing ordinary polycarbonate resins, for example, a method of reacting a diol compound with a carbonate precursor (such as a carbonic acid diester) (transesterification). An example of a production method using transesterification is described below.

[0035] The transesterification reaction using a carbonate diester as a carbonate precursor is carried out by stirring a predetermined ratio of a diol compound with a carbonate diester under heating in an inert gas atmosphere, and distilling off the resulting alcohol or phenol. The reaction temperature varies depending on the boiling point of the resulting alcohol or phenol, but is usually in the range of 120 to 300°C. The reaction is completed by reducing the pressure from the beginning of the reaction to distill off the resulting alcohol or phenol. If necessary, a terminal capping agent, antioxidant, etc. may also be added.

[0036] Examples of the carbonate diester used in the transesterification reaction include esters of an optionally substituted aryl group having 6 to 12 carbon atoms and an optionally substituted aralkyl group having 6 to 12 carbon atoms. Specific examples include diphenyl carbonate, ditolyl carbonate, bis(chlorophenyl)carbonate, and m-cresyl carbonate. Of these, diphenyl carbonate is preferred. The amount of the carbonate diester used is preferably 0.97 to 1.10 mol, more preferably 1.00 to 1.06 mol, per mol of the total amount of the diol compounds.

[0037] The transesterification reaction can be carried out using, for example, a melt polymerization process. In the melt polymerization process, a polymerization catalyst can be used to increase the polymerization rate. Examples of such polymerization catalysts include alkali metal compounds, alkaline earth metal compounds, other metal compounds, basic boron compounds, basic phosphorus compounds, and nitrogen-containing compounds. Examples of such compounds that are preferably used include organic acid salts, inorganic salts, oxides, hydroxides, hydrides, alkoxides, and quaternary ammonium hydroxides of alkali metals or alkaline earth metals. These compounds may be used alone or in combination.

[0038] Examples of the alkali metal compounds include sodium hydroxide, potassium hydroxide, cesium hydroxide, lithium hydroxide, sodium bicarbonate, sodium carbonate, potassium carbonate, cesium carbonate, lithium carbonate, sodium acetate, potassium acetate, cesium acetate, lithium acetate, sodium stearate, potassium stearate, cesium stearate, lithium stearate, sodium borohydride, sodium benzoate, potassium benzoate, cesium benzoate, lithium benzoate, disodium hydrogen phosphate, dipotassium hydrogen phosphate, dilithium hydrogen phosphate, disodium phenylphosphate, disodium salt, dipotassium salt, dicesium salt, dilithium salt of bisphenol A, sodium salt, potassium salt, cesium salt, and lithium salt of phenol.

[0039] Examples of the alkaline earth metal compound include magnesium hydroxide, calcium hydroxide, strontium hydroxide, barium hydroxide, magnesium carbonate, calcium carbonate, strontium carbonate, barium carbonate, calcium hydrogen carbonate, barium hydrogen carbonate, magnesium hydrogen carbonate, strontium hydrogen carbonate, magnesium diacetate, calcium diacetate, strontium diacetate, and barium diacetate.

[0040] Examples of the other metal compounds include zinc aluminum compounds, germanium compounds, organotin compounds, antimony compounds, manganese compounds, titanium compounds, and zirconium compounds.

[0041] Examples of the basic boron compound include alkali metal salts or alkaline earth metal salts (sodium salt, potassium salt, lithium salt, calcium salt, barium salt, magnesium salt, or strontium salt) of tetramethyl boron, tetraethyl boron, tetrapropyl boron, tetrabutyl boron, trimethylethyl boron, trimethylbenzyl boron, trimethylphenyl boron, triethylmethyl boron, triethylbenzyl boron, triethylphenyl boron, tributylbenzyl boron, tributylphenyl boron, tetraphenyl boron, benzyltriphenyl boron, methyltriphenyl boron, and butyltriphenyl boron.

[0042] Examples of the basic phosphorus compound include triethylphosphine, tri-n-propylphosphine, triisopropylphosphine, tri-n-butylphosphine, triphenylphosphine, tributylphosphine, and quaternary phosphonium salts.

[0043] Examples of the nitrogen-containing compound include quaternary ammonium hydroxides having an alkyl group or an aryl group, such as tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, and trimethylbenzylammonium hydroxide. Examples of the nitrogen-containing compound include tertiary amines, such as triethylamine, dimethylbenzylamine, and triphenylamine; and imidazoles, such as 2-methylimidazole, 2-phenylimidazole, and benzimidazole. Examples of the nitrogen-containing compound include bases or basic salts, such as ammonia, tetramethylammonium borohydride, tetrabutylammonium borohydride, tetrabutylammonium tetraphenylborate, and tetraphenylammonium tetraphenylborate.

[0044] These compounds may be used alone or in combination of two or more. The total amount of these polymerization catalysts used is preferably 1 × 10 relative to 1 mole of the total of the diol compounds. －９~1 x 10 －２ equivalent range, more preferably 1×10 －８ ~1 x 10 －２ equivalent range, more preferably 1×10 －７ ~1 x 10 －３ It is in the range of equivalents.

[0045] A catalyst deactivator can also be added in the latter stage of the polymerization reaction (at a temperature near (about Tg + 10°C) above the glass transition temperature of the polycarbonate (about 100°C to 150°C)). Known catalyst deactivators are effectively used as the catalyst deactivator, with ammonium salts of sulfonic acid, phosphonium salts of sulfonic acid, and sulfonate esters being preferred. Furthermore, salts of dodecylbenzenesulfonic acid such as tetrabutylphosphonium dodecylbenzenesulfonate; and salts of paratoluenesulfonic acid such as tetrabutylammonium paratoluenesulfonate are more preferred. Furthermore, preferred examples of the sulfonate ester include methyl benzenesulfonate, ethyl benzenesulfonate, butyl benzenesulfonate, octyl benzenesulfonate, phenyl benzenesulfonate, methyl paratoluenesulfonate, ethyl paratoluenesulfonate, butyl paratoluenesulfonate, octyl paratoluenesulfonate, and phenyl paratoluenesulfonate. Among the above catalyst deactivators, tetrabutylphosphonium dodecylbenzenesulfonate is preferably used.

[0046] When at least one polymerization catalyst selected from the group consisting of alkali metal compounds and alkaline earth metal compounds is used, the amount of the catalyst deactivator used is preferably 0.5 to 50 mol, more preferably 0.5 to 10 mol, and still more preferably 0.8 to 5 mol, per 1 mol of the polymerization catalyst.

[0047] Furthermore, commercially available products may be used as the polycarbonate (A), and examples of commercially available products include "DURABIO (registered trademark)" (manufactured by Mitsubishi Chemical Corporation).

[0048] <Inorganic Particulate Filler (B)> The inorganic particulate filler (B) has an average primary particle diameter of 2.5 μm or less and an aspect ratio of 1 or more and less than 10. By including component (B), the resin composition can obtain superior strength and a molded article with small anisotropy in bending strength. Furthermore, by including component (B) in the resin composition, it is expected that the resin composition will have the effects of imparting X-ray contrast properties and improving the cutting processability of the obtained molded article.

[0049] From the viewpoint of reducing the anisotropy of bending strength, the average primary particle diameter of component (B) must be 2.5 μm or less, preferably 1.5 μm or less, more preferably 1.0 μm or less, and even more preferably 0.70 μm or less. Furthermore, having the average primary particle diameter satisfy the above range is also preferable from the viewpoint of facilitating uniform dispersion of component (B) within the resin composition and improving the transparency and adhesiveness of the resulting molded article. Furthermore, from the viewpoint of facilitating obtaining better strength and facilitating adjustment to an appropriate fluidity and improving the moldability of the resin composition, the average primary particle diameter of component (B) is preferably 0.01 μm or more, more preferably 0.025 μm or more, even more preferably 0.05 μm or more, and even more preferably 0.10 μm or more. As described above, the preferred ranges of the average primary particle diameter of component (B) can be independently combined. For example, in one embodiment of component (B), the average primary particle diameter is preferably 0.01 to 2.5 μm, more preferably 0.025 to 1.5 μm, even more preferably 0.05 to 1.0 μm, and still more preferably 0.10 to 0.70 μm.

[0050] The average primary particle size can be determined by a laser diffraction scattering method. For example, it can be measured on a volume basis using a laser diffraction particle size distribution analyzer (such as the "SALD (registered trademark)-7500 nano" manufactured by Shimadzu Corporation) using a 0.2% aqueous solution of sodium hexametaphosphate as a dispersion medium. The value of the average primary particle size is the D50 value on a volume basis.

[0051] The aspect ratio of component (B) is at least 1 and less than 10, and from the viewpoint of making it easier to reduce the anisotropy of the resulting molded article, it is preferably 1 to 5, more preferably 1 to 2.5, and even more preferably 1 to 1.5. In this specification, the "aspect ratio" is the value obtained by dividing the major axis (μm) of a particle by the minor axis (μm).

[0052] In this specification, the aspect ratio can be determined by electron microscope observation. Specifically, it can be determined by taking a microphotograph of the particles and measuring the lengths of the major and minor axes of the particles (200 particles) observed within a unit field of view of the photograph. It can also be determined by measuring the particle diameters of the particles (200 particles) observed within a unit field of view of the microphotograph using image analysis particle size distribution measurement software (such as "Mac-View" manufactured by Mountech Co., Ltd.). In this case, the aspect ratio is determined as the arithmetic mean value of the major axis length and the arithmetic mean value of the minor axis length of the particles, and as described above, the aspect ratio is determined by dividing the arithmetic mean value of the major axis length (unit: μm) by the arithmetic mean value of the minor axis length (unit: μm).

[0053] Examples of the inorganic particulate filler (B) that can be used include various glasses (glasses containing silicon dioxide (quartz, quartz glass, silica gel, etc.) or silicon as the main component and containing at least one selected from boron and aluminum together with various heavy metals; glasses containing heavy metal elements such as zirconium, barium, titanium, lanthanum, strontium, etc.), diatomaceous earth, kaolin, clay minerals (montmorillonite, etc.), activated clay, synthetic zeolite, mica, silica, calcium fluoride, ytterbium fluoride, calcium phosphate, barium sulfate, alumina, various ceramics such as zirconium dioxide (zirconia), titanium oxide, barium titanate, hydroxyapatite, praseodymium compounds, erbium compounds, manganese compounds, and other inorganic oxides containing various heavy metal elements (zirconium, barium, titanium, lanthanum, strontium, etc.), and other conventionally known inorganic particulate fillers. In one embodiment of the present invention, the component (B) is preferably an inorganic particulate filler such as glass containing at least one element selected from boron and aluminum, ytterbium fluoride, barium glass, barium borosilicate glass, lanthanum glass, strontium boroaluminosilicate glass, fluoroaluminosilicate glass, silica, or quartz, because these fillers facilitate achieving higher transparency. The inorganic particulate filler (B) may also include an organic-inorganic composite particulate filler obtained by adding a polymerizable monomer to the inorganic particulate filler to form a paste, polymerizing and curing the paste, and pulverizing the paste. As the inorganic particulate filler (B), one of the inorganic particulate fillers or the organic-inorganic composite particulate fillers may be used alone, or two or more of them may be used in combination.

[0054] The refractive index of component (B) is not limited as long as the effects of the present invention are achieved, but from the viewpoint of improving transparency, it is preferably 1.35 to 1.65, more preferably 1.40 to 1.60, and even more preferably 1.43 to 1.57. The refractive index value is specifically a value evaluated by the method described in the examples.

[0055] Component (B) may be surface-treated with a known surface treatment agent before use, if necessary, to adjust its miscibility with component (A). Examples of the surface treatment agent include alcohols such as trimethylolethane, trimethylolpropane, and pentaerythritol; alkanolamines such as triethylamine; organosilicone compounds such as organopolysiloxane; higher fatty acids such as stearic acid (preferably higher fatty acids having 12 to 24 carbon atoms); fatty acid metal salts (fatty acid metal salts having 12 to 24 carbon atoms) such as calcium stearate and magnesium stearate; hydrocarbon lubricants such as polyethylene wax and liquid paraffin; basic amino acids such as lysine and arginine; polyglycerin and derivatives thereof; and coupling agents such as silane coupling agents, titanate coupling agents, and aluminum coupling agents. These may be used alone or in combination of two or more. Examples of the surface treatment agent include at least one selected from the group consisting of alcohols, alkanolamines, organic silicone compounds, higher fatty acids, fatty acid metal salts, hydrocarbon lubricants, basic amino acids, polyglycerin and derivatives thereof, and coupling agents.

[0056] The content of component (B) in the resin composition is not particularly limited as long as the effects of the present invention are achieved. However, from the viewpoint of improving the moldability and strength of the dental resin composition, it is preferably 1 to 60% by weight, more preferably 5 to 55% by weight, and even more preferably 10 to 50% by weight, based on 100% by weight of the resin composition. A content of inorganic particulate filler (b) of 1% by weight or more maintains good strength of the dental resin composition, while a content of 60% by weight or less maintains good moldability of the dental resin composition. Furthermore, from the viewpoint of reducing anisotropy, the content of component (B) is even more preferably 10 to 40% by weight, based on 100% by weight of the dental resin composition. Furthermore, from the viewpoint of improving strength, the content of component (B) is even more preferably 15 to 55% by weight, based on 100% by weight of the dental resin composition. Furthermore, from the viewpoint of further improving the strength and further reducing the anisotropy, the content of the component (B) is more preferably 15 to 40% by mass in 100% by mass of the dental resin composition.

[0057] The resin composition may contain a filler other than component (B) for the purpose of adjusting mechanical properties, etc., as long as the object of the present invention is not impaired. Examples of fillers other than component (B) include particulate fillers, fibrous fillers, wool-like fillers, woven fabrics, nonwoven fabrics, and plate-like fillers other than component (B). These particulate fillers, fibrous fillers, wool-like fillers, woven fabrics, nonwoven fabrics, and plate-like fillers other than component (B) may be at least one selected from organic fillers and inorganic fillers, or organic-inorganic composite fillers. The content of fillers other than component (B) is preferably 0 to 10% by mass, more preferably 0 to 5% by mass, and even more preferably 0 to 1% by mass, based on 100% by mass of the resin composition, and may even be 0% by mass.

[0058] In one aspect of the present invention, from the viewpoint of more easily achieving the effects of the present invention, the total content of components (A) and (B) in the resin composition is preferably 90 to 100 mass%, more preferably 95 to 100 mass%, even more preferably 97 to 100 mass%, still more preferably 98 to 100 mass%, and still more preferably 99 to 100 mass%, based on 100 mass% of the resin composition.

[0059] (Other Components) The resin composition may contain other components in addition to the above-described components depending on the purpose, as long as the effects of the present invention are achieved. Examples of the other components include pH adjusters, UV absorbers, antioxidants, polymerization inhibitors, colorants (pigments, dyes, fibers, etc.), antibacterial agents, X-ray contrast agents, organic solvents, thickeners, fluorescent agents, etc. In the present invention, for example, a resin composition containing a colorant can be used to obtain a transparent molded product. The other components may be used alone or in combination of two or more.

[0060] When the resin composition contains other components, there are no particular limitations on the total content of the other components as long as the effects of the present invention are achieved, and an amount that provides the required effect may be used. For example, the total content of the other components is preferably 0.000001 to 5 parts by mass, and more preferably 0.00001 to 1 part by mass, relative to 100 parts by mass of the total of components (A) and (B) contained in the resin composition.

[0061] <Method for producing dental resin composition> The method for producing the resin composition is not particularly limited as long as the effects of the present invention are achieved. For example, known mixing methods can be used, such as a solution blending method in which components such as the filler (component (B) and any filler other than component (B) that may be added if necessary) and the other components that may be added if necessary are mixed in a good solvent for component (A) and then the solvent is removed; or a method in which component (A) and the other components (component (B) and any filler other than component (B) that may be added if necessary, and the other components that may be added if necessary) are melt-kneaded in a kneader or the like.

[0062] However, as one aspect of the present invention, the melt-kneading method is preferred. That is, the method for producing the resin composition preferably includes a step of melt-kneading at least component (A) and component (B) (hereinafter also referred to as "step (1)"). In step (1), which is the melt-kneading step, as described above, at least one selected from the group consisting of a filler other than component (B) and the other components may be added and melt-kneaded, if necessary. In the melt-kneading method, a method using a kneader or the like is preferred from the viewpoint of easily mixing the inorganic particulate filler finely and uniformly. As the kneader, a multi-screw kneader is preferred, a multi-screw extruder is more preferred, and a twin-screw extruder is even more preferred. That is, the melt-kneading in step (1) is more preferably melt-extrusion kneading using a multi-screw extruder, and even more preferably melt-extrusion kneading using a twin-screw extruder. The L (shaft length) / D (shaft diameter) ratio of the twin-screw extruder is preferably 25 or more, more preferably 35 or more, and even more preferably 45 or more. The upper limit of the L / D is not particularly limited, but is preferably, for example, not more than 100. As described above, the preferred ranges of the L / D can be independently combined. For example, in one embodiment of the twin-screw extruder, the L / D is preferably 25 to 100, more preferably 35 to 100, and even more preferably 45 to 100.

[0063] The method for adding component (B), the optional filler other than component (B), and the other components to component (A) is not particularly limited. For example, before melt-kneading, component (A), component (B), the optional filler other than component (B), and the other components are all mixed in a container such as a plastic bag or a tumbler, and then charged into a kneader; or component (A) is first charged into a kneader and heated to melt, and then component (B), the optional filler other than component (B), and the other components are charged in the middle of the kneader; etc. In addition, as one embodiment of step (1), it is preferable to obtain the dental resin composition by molding it into a pellet shape.

[0064] The melt-kneading temperature during the melt-kneading is preferably 360°C or lower, more preferably 320°C or lower, and even more preferably 280°C or lower, from the viewpoint of easily preventing deterioration of component (A). The lower limit of the melt-kneading temperature is not particularly limited as long as melt-kneading is possible and the effects of the present invention are achieved. For example, the lower limit of the melt-kneading temperature during the melt-kneading is preferably 200°C, from the viewpoint of easily melt-kneading. As described above, the preferred ranges of the melt-kneading temperature can be independently combined. For example, in one embodiment of step (1), the melt-kneading temperature is preferably 200 to 360°C, more preferably 200 to 320°C, and even more preferably 200 to 280°C. The "melt-kneading temperature during melt-kneading" refers to the highest temperature among the temperatures that can be set between the component inlet and the discharge outlet in a kneader (e.g., an extruder) used for melt-kneading.

[0065] <Characteristics of Dental Resin Composition> In one aspect of the present invention, the flexural strength of the resin composition is preferably 150 MPa or more, more preferably 160 MPa or more, even more preferably 170 MPa or more, even more preferably 175 MPa or more, even more preferably 180 MPa or more, even more preferably 190 MPa or more, and even more preferably 200 MPa or more. The upper limit is not particularly limited as long as the effects of the present invention are achieved, but is preferably 300 MPa, which is preferable from the viewpoint of improving the machinability of the resulting molded article. As described above, the preferred ranges of flexural strength can be independently combined. For example, in one aspect of the resin composition, the flexural strength is preferably 150 to 300 MPa, more preferably 160 to 300 MPa, even more preferably 170 to 300 MPa, even more preferably 175 to 300 MPa, even more preferably 180 to 300 MPa, even more preferably 190 to 300 MPa, and even more preferably 200 to 300 MPa. In one embodiment of the present invention, the flexural modulus of the resin composition is preferably 5.0 GPa or more, more preferably 6.0 GPa or more, even more preferably 6.5 GPa or more, and even more preferably 7.0 GPa or more. The upper limit is not particularly limited as long as the effects of the present invention are achieved. However, from the viewpoint of easily obtaining a modulus of elasticity similar to that of tooth structure, it is preferably 20 GPa. As described above, the preferred ranges of the flexural modulus can be independently combined. For example, in one embodiment of the resin composition, the flexural modulus is preferably 5.0 to 20 GPa, more preferably 6.0 to 20 GPa, even more preferably 6.5 to 20 GPa, and even more preferably 7.0 to 20 GPa. The flexural strength and flexural modulus values ​​of the resin composition are evaluated using a molded article molded from the resin composition. Specifically, they are values ​​related to the horizontal direction of the molded article evaluated by the method described in the Examples.

[0066] In one embodiment of the present invention, the flexural strength anisotropy of the resin composition is preferably 0 to 10%, more preferably 0 to 5.0%, even more preferably 0 to 3.5%, still more preferably 0 to 3.0%, and still more preferably 0 to 2.5%. The flexural strength anisotropy value of the resin composition is evaluated using a molded article molded from the resin composition, and specifically, is calculated by the method described in the examples.

[0067] In one aspect of the present invention, from the viewpoint of ensuring higher aesthetics of the obtained molded article, the transparency (ΔL) of the resin composition is preferably 20 or more, more preferably 25 or more, and even more preferably 30 or more. The upper limit is not particularly limited as long as the effects of the present invention are achieved, but is, for example, 50 or less. In one aspect of the resin composition, the transparency (ΔL) is preferably 20 to 50, more preferably 25 to 50, and even more preferably 30 to 50. The transparency (ΔL) value of the resin composition is evaluated using a molded article molded from the resin composition, and specifically, is calculated by the method described in the examples.

[0068] In one aspect of the present invention, from the viewpoint of ensuring higher adhesiveness in the obtained molded article, the adhesive strength of the resin composition is preferably 20 MPa or more, more preferably 30 MPa or more, and even more preferably 35 MPa or more. The upper limit is not particularly limited as long as the effects of the present invention are achieved, but is, for example, 50 MPa or less. In one aspect of the resin composition, the adhesive strength is preferably 20 to 50 MPa, more preferably 30 to 50 MPa, and even more preferably 35 to 50 MPa. The adhesive strength value of the resin composition is evaluated using a molded article molded from the resin composition, and specifically, is calculated by the method described in the examples.

[0069] [Dental Molded Article] A dental molded article according to one embodiment of the present invention comprises the dental resin composition. Applications of the molded article include, for example, dental crowns (e.g., inlays and crowns), denture bases, artificial teeth, and orthodontic brackets. Dental crowns (e.g., inlays and crowns) are colored to the color of tooth tissue and are bonded to missing teeth. Denture bases are generally colored clear or gum-colored and include denture bases for complete dentures and partial dentures. They support artificial teeth and function as attachments in the oral cavity. Similarly, each of the above-mentioned applications can also be considered applications of the dental resin composition. Accordingly, one embodiment of the dental molded article includes a dental crown, denture base, artificial tooth, or orthodontic bracket containing the dental resin composition. Another preferred example of the molded article is a dental mill blank for molding the dental crown or denture base. That is, one preferred example of the molded article is a dental mill blank containing the dental resin composition. That is, a dental mill blank can also be considered an application of the dental resin composition.

[0070] Furthermore, the content of the dental resin composition in the molded body is not particularly limited as long as the effects of the present invention are achieved, but is preferably 10 to 100% by mass, more preferably 30 to 100% by mass, even more preferably 50 to 100% by mass, still more preferably 70 to 100% by mass, even more preferably 80 to 100% by mass, still more preferably 90 to 100% by mass, and may even be 100% by mass, based on 100% by mass of the total of the components constituting the molded body.

[0071] The molded article may be molded in a single layer, but from the viewpoint of aesthetics and strength, it may also be molded by laminating dental resin compositions with different color tones and strengths. That is, one embodiment of the dental molded article may be composed of a single layer or a laminate. Examples of molded articles composed of the laminate include dental mill blanks composed of laminates and dental crowns and denture bases obtained by processing the dental mill blanks.

[0072] When the molded article is a laminate, at least one of the multiple layers contains the dental resin composition. The other layer not containing the dental resin composition may be, for example, a layer formed from a dental resin composition containing component (A) but not component (B), or may be a layer formed from a resin other than component (A). When the molded article is a laminate, the content of the dental resin composition in the layer containing the dental resin composition is not particularly limited as long as the effects of the present invention are achieved. However, the content is preferably 50 to 100% by weight, more preferably 70 to 100% by weight, even more preferably 80 to 100% by weight, even more preferably 90 to 100% by weight, and even more preferably 95 to 100% by weight, based on 100% by weight of the total components constituting the layer containing the dental resin composition.

[0073] <Method for Producing Dental Molded Articles> The method for producing the dental molded articles is not particularly limited, and known production methods can be used, such as: a production method in which a molded article such as a denture base or bracket is directly obtained from pellets of the dental resin composition by injection molding; a method in which pellets of the dental resin composition are extruded and cut, injection molded, or press-molded into a block or disk shape, and then machined using a CAD / CAM system to form at least one selected from a dental crown and a denture base; or a method in which pellets of the dental resin composition are extruded into a filament shape using a 3D printing system and laminate-molded; Furthermore, the pellets of the dental resin composition that can be used in the production methods of the above-mentioned molded articles are preferably produced, for example, using step (1) described above in the section on the dental resin composition.

[0074] As described above, one embodiment of the method for producing the dental molded article includes a step of injection-molding the dental resin composition to form a part or all of the dental molded article (hereinafter also referred to as "step (2)"). Another embodiment of the method for producing the dental molded article includes a step of press-molding the dental resin composition to form a part or all of the dental molded article (hereinafter also referred to as "step (3)"). Another preferred embodiment of the method for producing the dental molded article includes a method in which the dental resin composition is molded by one molding method selected from injection molding and press molding, and then machined using a CAD / CAM system. Injection molding and press molding are selected depending on the fluidity of the dental resin composition. Alternatively, both injection molding and press molding may be combined. The molded articles obtained using these methods may be molded in a single layer, but dental resin compositions with different color tones and strengths can also be laminated from the standpoint of aesthetics and strength.In addition, when laminate molding is used, one embodiment of the method for manufacturing the dental molded article is to injection mold or press mold the dental resin composition to mold a portion of the dental molded article, and then laminate the portion of the molded article in multiple layers and press mold it to mold part or all of the dental molded article.

[0075] Therefore, one embodiment of the method for producing the dental molded article includes a step of cutting the dental resin composition to form a part or all of the dental molded article (hereinafter also referred to as "step (4)"). Furthermore, the cutting process preferably uses a dental mill blank obtained through at least one of steps (2) and (3), and the dental mill blank preferably has a block or disk shape. Furthermore, as described above, the dental mill blank may be composed of a single layer or a laminate. When the dental mill blank is a laminate, the configuration of each layer is as described above. Furthermore, the cutting process is preferably performed using, for example, a commercially available dental CAD / CAM system. Examples of such CAD / CAM systems include the CEREC (registered trademark) system from Dentsply Sirona Inc. and the Katana (registered trademark) system from Kuraray Noritake Dental Co., Ltd.

[0076] The processing temperature during production of the molded article is preferably 360°C or lower, more preferably 320°C or lower, and even more preferably 280°C or lower, from the viewpoint of easily preventing deterioration of component (A). The "processing temperature" refers to the highest temperature set for each device used during molding of the dental resin composition into the molded article. The lower limit of the processing temperature is not particularly limited as long as the desired molded article can be molded and the effects of the present invention are achieved. However, from the viewpoint of facilitating molding of the dental resin composition, the lower limit is preferably 200°C. As described above, the preferred ranges of the processing temperature can be independently combined. For example, in one embodiment of the method for producing the dental molded article, the processing temperature is preferably 200 to 360°C, more preferably 200 to 320°C, and even more preferably 200 to 280°C.

[0077] In one embodiment of the method for producing a dental molded article, the melt temperature during injection molding is preferably 360°C or lower, more preferably 320°C or lower, and even more preferably 280°C or lower, from the viewpoint of easily preventing deterioration of component (A). The lower limit of the melt temperature during injection molding is not particularly limited as long as injection molding is possible and the effects of the present invention are achieved. For example, the lower limit of the melt temperature during injection molding is preferably 200°C from the viewpoint of easy molding. As described above, the preferred ranges of the melt temperature during injection molding can be independently combined. For example, in one embodiment of the method for producing a dental molded article, the melt temperature is preferably 200 to 360°C, more preferably 200 to 320°C, and even more preferably 200 to 280°C. The "melt temperature during injection molding" refers to the highest temperature that can be set in an injection molding machine from the time the resin composition is charged until the molded article is obtained.

[0078] In one embodiment of the method for producing a dental molded article, the pressing temperature during press molding is preferably 360°C or less, more preferably 320°C or less, and even more preferably 280°C or less, from the viewpoint of easily preventing deterioration of component (A). The lower limit of the pressing temperature is not particularly limited as long as press molding is possible and the effects of the present invention are achieved. For example, the lower limit of the pressing temperature during press molding is preferably 200°C from the viewpoint of easy molding. As described above, the preferred ranges of the pressing temperature during press molding can be independently combined. For example, in one embodiment of the method for producing a dental molded article, the pressing temperature is preferably 200 to 360°C, more preferably 200 to 320°C, and even more preferably 200 to 280°C. The "pressing temperature" refers to the highest temperature set in the press machine during pressing. The pressing pressure (gauge pressure) during press molding is not particularly limited as long as a dental molded article can be produced and the effects of the present invention are achieved. However, it is preferably 0.1 to 15 MPa. The pressing time during the press molding is not particularly limited as long as the effects of the present invention are achieved, but is preferably 3 to 15 minutes from the viewpoint of avoiding deterioration and discoloration of each component and making it easier to achieve the effects of the present invention.

[0079] The present embodiment will be explained in more detail below by showing examples and comparative examples, but the present embodiment is not limited to the following examples.

[0080] The components used in the production of the dental resin compositions according to the Examples and Comparative Examples are explained below together with their abbreviations and names. The following properties of each component were measured by the following methods.

[0081] <Polymer composition ratio> Using a Fourier transform nuclear magnetic resonance (FT-NMR) spectrometer (model: ECX400, manufactured by JEOL Ltd.) １ H-NMR (measurement temperature: 25°C, internal standard: tetramethylsilane (TMS), solvent: deuterated chloroform (CDCl ３ ), sample concentration: 5 to 50 mg / 0.5 mL, number of accumulations: 8 to 64), each carbonate unit was measured, and the polymer composition ratio (molar ratio) of the polycarbonate was calculated.

[0082] <Refractive Index> The refractive index of the inorganic particulate filler and the glass fiber filler was measured by the immersion method using an Abbe refractometer (product name: DR-A1, NAR series; manufactured by Atago Co., Ltd.) in an environment of 25° C. Specifically, the inorganic particulate filler or glass fiber filler to be measured was dispersed in ethanol to form a slurry, 1-bromonaphthalene was gradually added dropwise to this slurry, and the refractive index of the dispersion liquid at which the boundary between the measurement object and the liquid could no longer be visually confirmed was taken as the refractive index of the measurement object.

[0083] <Average primary particle diameter> The average primary particle diameter of the inorganic particulate filler and the glass fiber filler was measured using a laser diffraction particle size distribution analyzer (product name "SALD (registered trademark)-7500 nano", manufactured by Shimadzu Corporation) using a 0.2% aqueous solution of sodium hexametaphosphate as a dispersion medium. The average primary particle diameter is the D50 value based on volume.

[0084] <Aspect Ratio> The aspect ratios of the inorganic particulate filler and the glass fiber filler were measured by using image analysis particle size distribution measurement software (Mac-View, manufactured by Mountec Co., Ltd.) on images taken with a scanning electron microscope (SU3500, manufactured by Hitachi High-Tech Corporation). 200 samples were subjected to image processing, and the average value was used. The aspect ratio was calculated as the arithmetic mean value (unit: μm) of the longest length (length of the major axis) of the particles divided by the arithmetic mean value (unit: μm) of the shortest length (length of the minor axis).

[0085] <MFR> The melt flow rate (MFR) of component (A) was measured under conditions of a temperature of 230°C and a load of 21.2 N.

[0086] [Polycarbonate (A) (Component (A))] <Synthesis Example 1: Production of Polycarbonate (A)-1> 375 g of isosorbide (abbreviated as "ISS"), 101 g of 1,6-hexanediol (abbreviated as "HD"), 750 g of diphenyl carbonate (abbreviated as "DPC"), and 0.8 × 10 tetramethylammonium hydroxide as a catalyst were used. －２ g and sodium hydroxide 0.6 x 10 －４ g were mixed in a reaction vessel and heated to 180°C under a nitrogen atmosphere to melt. Thereafter, the degree of vacuum was adjusted to 13.4 kPa over 30 minutes. Thereafter, the temperature was raised to 240°C at a rate of 60°C / hr, and after maintaining at 240°C for 10 minutes, the degree of vacuum was reduced to 133 Pa or less over 1 hour. The reaction was carried out for a total of 6 hours with stirring, and the mixture was discharged from the bottom of the reaction vessel under nitrogen pressure and cut with a pelletizer while being cooled in a water bath to produce pellets of polycarbonate (A)-1. The molar ratio [(I) / (D)] of carbonate units (I) derived from ISS of polycarbonate (A)-1 to carbonate units (D) derived from HD was (I) / (D) = 75 / 25. The MFR value measured at a temperature of 230°C and a load of 21.2 N was 8.4 g / 10 min.

[0087] Synthesis Example 2: Synthesis of Polycarbonate (A)-2 Pellets of polycarbonate (A)-2 were produced in exactly the same manner as in Synthesis Example 1, except that 426 g of ISS, 83 g of 2,4-diethyl-1,5-pentanediol (abbreviated as "DEP"), and 750 g of DPC were used as raw materials. The molar ratio [(I) / (D)] of carbonate units (I) derived from ISS to carbonate units (D) derived from DEP in polycarbonate (A)-2 was (I) / (D) = 85 / 15. The MFR value measured at a temperature of 230°C and a load of 21.2 N was 14 g / 10 min.

[0088] Synthesis Example 3: Synthesis of Polycarbonate (A)-3 Pellets of polycarbonate (A)-3 were produced in exactly the same manner as in Synthesis Example 1, except that 250 g of ISS, 247 g of 1,4-cyclohexanedimethanol (abbreviated as "CHDM"), and 750 g of DPC were used as raw materials. The molar ratio [(I) / (D)] of carbonate units (I) derived from ISS to carbonate units (D) derived from CHDM in polycarbonate (A)-3 was (I) / (D) = 50 / 50. The MFR value measured at a temperature of 230°C and a load of 21.2 N was 5.2 g / 10 min.

[0089] [Thermoplastic resins other than component (A)] Polycarbonate-C1: bisphenol-based polycarbonate, product name "Iupilon (registered trademark) S2000" (manufactured by Mitsubishi Engineering Plastics Corporation, carbonate unit (I) is 0 mol%) Polyether ether ketone (abbreviated as "PEEK")-C1: product name "VESTAKEEP (registered trademark)-J ZV0401" (manufactured by POLYPLASTICS EVONIK)

[0090] [Inorganic particulate filler (B) (component (B))] Inorganic particulate filler (B)-1: Barium glass 8235 UF0.4 (manufactured by SCHOTT, average primary particle size 0.4 μm, aspect ratio 1.2, refractive index 1.55, crushed, silane surface treatment) Inorganic particulate filler (B)-2: Barium glass 8235 UF2.0 (manufactured by SCHOTT, average primary particle size 2.0 μm, aspect ratio 1.4, refractive index 1.55, crushed, silane surface treatment) Inorganic particulate filler (B)-3: Fluoroaluminosilicate glass G018-090 UF0.4 (manufactured by SCHOTT, average primary particle size 0.4 μm, aspect ratio 1.3, refractive index 1.50, crushed, silane surface treatment) Inorganic particulate filler (B)-4: Product name "Admafine (registered trademark) SO-C1" (manufactured by Admatechs Co., Ltd., average primary particle diameter 0.4 μm, aspect ratio 1.0, refractive index 1.45, spherical, silane surface treatment)

[0091] [Fillers other than component (B)] Glass fiber filler 1: product name "CS chopped strand CS 3PE-455S" (manufactured by Nitto Boseki Co., Ltd., fiber length 3.0 mm, aspect ratio 230, refractive index 1.52, silane surface treatment) Glass fiber filler 2: product name "quartz glass wool fine" (manufactured by Tokyo Glass Instrument Co., Ltd., fiber length 1.0 mm, aspect ratio 500, refractive index 1.52, silane surface treatment) Inorganic particulate filler C1: barium glass 8235 K5 (manufactured by SCHOTT, average primary particle size 5 μm, aspect ratio 1.2, refractive index 1.55, crushed, silane surface treatment) Inorganic particulate filler C2: barium glass 8235 K3 (manufactured by SCHOTT, average primary particle size 10 μm, aspect ratio 1.2, refractive index 1.55, crushed, silane surface treatment)

[0092] [Antioxidant] PEP-36: 3,9-bis(2,6-di-tert-butyl-4-methylphenoxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane (manufactured by ADEKA Corporation, trade name "ADEKA STAB (registered trademark) PEP-36")

[0093] The dental resin compositions of the Examples and Comparative Examples, and dental molded articles made from the dental resin compositions, were produced and evaluated by the methods described below. The compositions and properties of each dental resin composition are shown in Tables 1 and 2 below.

[0094] [Examples 1 to 8 and Comparative Examples 1 to 9] (1) Melt-Kneading The components were premixed in the proportions (parts by mass) shown in Tables 1 and 2 below, and then all the components were fed into a twin-screw extruder (manufactured by Technovel Co., Ltd., model name "KZW15-45MG," shaft diameter φ15 mm, L / D=45), melt-kneaded at the melt-kneading temperature shown in Tables 1 and 2 below (the highest temperature among the extruder set temperatures from the raw material inlet to the discharge outlet) at a rotation speed of 240 rpm, extruded into strands, and cut with a strand cutter to produce pellets of the dental resin composition. The method for setting the melt-kneading temperature will be described in detail below in the section on evaluation of moldability.

[0095] (2) Injection molding The dental resin composition pellets obtained by the melt-kneading in (1) were used in an injection molding machine (Toshiba Machine Co., Ltd., "IS-55EPN", mold clamping pressure 55 × 10 ３ The melt temperature (the highest temperature among the temperatures set at each point in the injection molding machine) was set to the same as the melt-kneading temperature in (1) above, and injection molding was performed at a mold temperature of 100°C to produce a circular disk having a thickness of 18 mm and a diameter of 10 cm. The physical properties of the obtained molded article (disc) were measured by the methods described below.

[0096] (3) Press molding: The dental resin composition pellets obtained by melt-kneading in (1) above were press-molded using a press molding machine (Iwaki Kogyo Co., Ltd.'s "37-ton heating and cooling press molding machine") at the same press temperature as the melt-kneading temperature in (1) above, under a press pressure of 10 MPa and a press time of 5 minutes to produce a disc-shaped sheet having a thickness of 2 mm and a diameter of 10 cm. Nine of these sheets were then stacked and fused together at the same press temperature as the melt-kneading temperature in (1) above, under a press pressure of 0.5 MPa and a press time of 10 minutes to produce a disc having a thickness of 18 mm and a diameter of 10 cm. The physical properties of this molded product (disc) were measured using the methods described below.

[0097] <Evaluation of molding processability> In the melt-kneading in the above (1), the melt-kneading temperature was increased stepwise from 240°C. The temperature at which poor dispersion of the component (B) or fillers other than the component (B) was not visually observed and the resin composition could be discharged uniformly and at a rate of 500 g / hr without torque overload was taken as the melt-kneading temperature and used as an index of molding processability. The melt-kneading temperatures are shown in Tables 1 and 2 below. A melt-kneading temperature of 360°C or less is preferred because it reduces the risk of resin deterioration and provides excellent molding processability, more preferably 320°C or less, and even more preferably 280°C or less. In Table 2 below, the notation "NA" indicates that in the molding processability evaluation, even when the temperature was increased to 400°C, torque overload was likely to occur, so the discharge rate could not reach 500 g / hr, the components could not be sufficiently melt-kneaded, and pellets of the resin composition were not obtained, and therefore evaluation of the following properties was not possible (not evaluated).

[0098] <Flexural Strength and Flexural Modulus> Using a diamond cutter, test pieces measuring 1.2 mm thick x 4.0 mm wide x 14.0 mm long were cut from each disk obtained in (2) or (3) above in the horizontal direction (radial direction of the disk) and the vertical direction (thickness direction of the disk, stacking direction) relative to the surface of the disk. The obtained test pieces were evaluated by performing a flexural strength test in accordance with JADMAS 245:2017, "Resin Materials for Dental Machining of CAD / CAM Crowns." That is, a flexural test was performed at a crosshead speed of 1 mm / min using a universal testing machine (Shimadzu Corporation, "Autograph (registered trademark) AG-100kNI") (n = 10). The results are shown in Tables 1 and 2 below, respectively.

[0099] <Evaluation of Flexural Strength Anisotropy> The flexural strength anisotropy was evaluated using the following calculation formula from the values ​​of the flexural strength in the horizontal direction and the flexural strength in the vertical direction obtained in the flexural strength test. The smaller the value obtained from the formula below, the smaller the anisotropy, and a value of 0 to 10% is preferable, as it indicates a small anisotropy. The results are shown in Tables 1 and 2 below. Flexural strength anisotropy (%) = |(horizontal flexural strength (MPa) - vertical flexural strength (MPa))| / horizontal flexural strength (MPa) x 100 *In the above formula, "|(horizontal flexural strength (MPa) - vertical flexural strength (MPa))|" represents the absolute value of horizontal flexural strength (MPa) - vertical flexural strength (MPa).

[0100] <Evaluation of Transparency> Using a diamond cutter, test pieces measuring 1.2 mm thick x 10 mm x 10 mm were cut out from each of the discs obtained in the Examples and Comparative Examples. Both surfaces of the obtained test pieces were polished under dry conditions using #1500 abrasive paper, #2000 abrasive paper, and #3000 abrasive paper in that order. For the test pieces obtained, the transparency of the polished surface was measured for the color tone and transparency ΔL of the polished surface using a spectrophotometer ("CM-3610d" manufactured by Konica Minolta Japan, Inc., in accordance with JIS Z 8722:2009, condition c, D65 light source). The transparency ΔL is defined by the following formula: ΔL = L ＊ W-L ＊ b L ＊ w is the L measured on a white background ＊a ＊ b ＊ Lightness index L in the color system ＊ represents L ＊ b is the L measured on a black background ＊ a ＊ b ＊ Lightness index L in the color system ＊ The results are shown in the following Tables 1 and 2. The larger the ΔL value, the more excellent the transparency.

[0101] <Evaluation of Adhesion> Test pieces measuring 5.0 mm thick x 10 mm x 10 mm were cut from each disk obtained in the Examples and Comparative Examples. The obtained test pieces were polished with #1000 silicon carbide paper under running water. After polishing, the surface was dried by air blowing the water off. After drying, the dried surface was further sandblasted with a 50-micron alumina abrasive (manufactured by Morita Corporation) to form a treated adherend surface. A 150 μm thick adhesive tape with a 5 mm diameter circular hole was attached to the treated adherend surface to control the adhesive area. Next, the following dental adhesive 1 was applied to the circular hole in the adhesive tape and left for 1 minute to dry the solvent. After that, dental cement (Panavia (registered trademark) V5 manufactured by Kuraray Noritake Dental Co., Ltd.) was applied to one end face (circular cross section) of a stainless steel cylindrical rod (diameter 7 mm, length 2.5 cm). The stainless steel cylindrical rod was pressed vertically against the circular hole so that the center of the circular hole and the center of the stainless steel cylindrical rod were approximately aligned to adhere the rod, thereby preparing a test sample. Ten test samples were prepared. The test samples were left to stand at room temperature for 30 minutes and then immersed in distilled water. The test samples immersed in distilled water were left to stand in an incubator maintained at 37°C for 24 hours. The tensile adhesive strength was measured by fixing the test piece, passing a jig through two holes on the side of the stainless steel cylindrical rod at the end opposite to the adhesive surface, and using a universal testing machine (Shimadzu Corporation, "Autograph (registered trademark) AG-100kNI") with a crosshead speed set to 2 mm / min, pulling the jig in a direction perpendicular to the adhesive surface of the test piece to pull the stainless steel cylindrical rod. The tensile adhesive strengths in Tables 1 and 2 below are average values ​​of the measured values ​​for 10 test samples. The results are shown in Tables 1 and 2 below, respectively. (Composition of dental adhesive 1) 10-methacryloyloxydecyl dihydrogen phosphate: 5.0% by mass 3-methacryloyltrimethoxysilane: 5.0% by mass Acetone: 90% by mass

[0102]

[0103]

[0104] As shown in Tables 1 and 2, the dental resin compositions of Examples 1 to 8 were moldable at temperatures below 330°C, had little risk of thermal decomposition, exhibited excellent strength without anisotropy, and also exhibited excellent transparency and adhesion. In particular, the moldability of the dental resin compositions of Examples 1 to 8 was superior to that of the dental resin compositions of Comparative Examples 2, 4, and 9. Furthermore, the flexural strength of the dental resin compositions of Examples 1 to 8 was superior to that of the dental resin compositions of Comparative Examples 6 and 7, and exhibited less anisotropy than the dental resin compositions of Comparative Examples 1, 3, 5, 6, and 8. Furthermore, the flexural modulus of the dental resin compositions of Examples 1 to 8 was superior to that of the dental resin compositions of Comparative Examples 1, 3, and 7. Furthermore, the transparency of the dental resin compositions of Examples 1 to 8 was superior to that of the dental resin compositions of Comparative Examples 5, 6, and 8. Furthermore, the adhesion of the dental resin compositions of Examples 1 to 8 was superior to that of the dental resin compositions of Comparative Examples 5, 6, and 8.

[0105] The dental resin composition according to one aspect of the present invention has excellent moldability, and the molded articles obtained have high strength and small anisotropy of bending strength. Furthermore, the molded articles have excellent transparency and adhesiveness, and are particularly useful for dental crowns and denture bases in CAD / CAM systems.

Claims

1. A dental resin composition comprising a polycarbonate (A) containing carbonate units (I) represented by the following formula (I) and an inorganic particulate filler (B), wherein the inorganic particulate filler (B) has an average primary particle diameter of 2.5 μm or less and an aspect ratio of 1 or more and less than 10:

2. The dental resin composition according to claim 1, wherein the content of the unit (I) in the polycarbonate (A) is 15 to 98 mol % based on 100 mol % of all carbonate units.

3. The dental resin composition according to claim 1, wherein the polycarbonate (A) contains carbonate units (D) derived from at least one compound selected from the group consisting of a linear aliphatic diol compound, a branched diol compound, and an alicyclic diol compound.

4. The dental resin composition according to claim 3, wherein the molar ratio of the unit (I) to the unit (D) in the polycarbonate (A) [(I) / (D)] is 15 / 85 to 98 / 2.

5. The dental resin composition according to claim 1, wherein the content of the polycarbonate (A) is 40 to 99% by mass based on 100% by mass of the dental resin composition.

6. The dental resin composition according to claim 1, wherein the refractive index of the inorganic particulate filler (B) is 1.35 to 1.

65.

7. A dental molded article comprising the dental resin composition according to any one of claims 1 to 6.

8. The dental molded article according to claim 7, which is composed of a laminate.

9. The dental molding according to claim 7, which is a dental mill blank.

10. The dental molded article according to claim 7, which is for a dental crown or a denture base.

11. The dental molded article according to claim 8, which is for a dental crown or a denture base.

12. A method for producing a dental resin composition according to any one of claims 1 to 6, comprising a step of melt-kneading at least the polycarbonate (A) and the inorganic particulate filler (B).

13. The method for producing a dental resin composition according to claim 12, wherein the melt-kneading is carried out using a twin-screw extruder, and the L / D ratio of the twin-screw extruder is 25 or more.

14. The method for producing a dental resin composition according to claim 12, wherein the melt-kneading temperature during the melt-kneading is 360°C or lower.

15. A method for producing a dental molded article, comprising the step of injection molding a dental resin composition according to any one of claims 1 to 6 to form a part or all of the dental molded article.

16. A method for producing a dental molded article, comprising the step of press-molding the dental resin composition according to any one of claims 1 to 6 to form a part or all of the dental molded article.

17. The method for producing a dental molded article according to claim 15, wherein the processing temperature is 360°C or less.

18. The method for producing a dental molded article according to claim 16, wherein the processing temperature is 360°C or less.

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