Method for producing monomer composition, method for producing polymerizable composition, monomer composition and polymerizable composition

Abstract

To provide a method for producing a monomer composition, which enables production of a monomer composition with high homogeneity.SOLUTION: A method for producing a monomer composition is provided, comprising a step (1) of producing a monomer composition (3) by mixing a monomer composition (1) comprising a (meth)acrylate (A) having an urethane bond and two or more (meth)acryloyl groups and a monomer composition (2) comprising a (meth)acrylate (B) in a state where the viscosity of the monomer composition (1) is 3,000 mPa s or less. In the step (1), the viscosity of the monomer composition (1) at 80°C is 100 mPa s or more and the viscosity of the monomer composition (2) at 80°C is less than that of the monomer composition (1). Also there are provided a method for producing a polymerizable composition using the monomer composition produced by the method for producing a monomer composition; a monomer composition; and a polymerizable composition.SELECTED DRAWING: None

Description

Technical Field

[0001] The present disclosure relates to a method for producing a composition for monomers, a method for producing a polymerizable composition, a composition for monomers, and a polymerizable composition.

Background Art

[0002] Compositions for dental materials such as composite resins generally contain a composition for dental materials containing monomers, a polymerization initiator, and the like. As monomers for dental materials, for example, 2,2,4-trimethylhexamethylene bis(2-carbamoyloxyethyl) dimethacrylate (UDMA) is widely known, and urethane acrylates other than UDMA have also been reported (for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When used as a monomer for dental materials, if the components contained in the monomer composition are not uniformly mixed, it may affect the properties (for example, appearance, physical property values, etc.) of the cured product obtained using the monomer composition. However, depending on the type of monomer, it has sometimes been difficult to obtain uniformity. Alternatively, even a monomer composition that appears to be uniformly mixed visually may not have sufficient uniformity.

[0005] An object of one aspect of the present disclosure is to provide a method for producing a monomer composition capable of producing a monomer composition with high uniformity, a method for producing a polymerizable composition using such a monomer composition, a monomer composition with high uniformity, and a polymerizable composition. **Means for Solving the Problems**

[0006] Specific means for solving the above problems are as follows. <1> A step (1) of mixing a (meth)acrylate (A) having a urethane bond and two or more (meth)acryloyl groups or a monomer composition (1) containing the (meth)acrylate (A) with a (meth)acrylate (B) other than the (meth)acrylate (A) or a monomer composition (2) containing the (meth)acrylate (B) in a state where the viscosity of the (meth)acrylate (A) or the monomer composition (1) is 3,000 mPa·s or less to produce a monomer composition (3), wherein in this step (1), the viscosity of the (meth)acrylate (A) or the monomer composition (1) at 80°C is 100 mPa·s or more, and the viscosity of the (meth)acrylate (B) or the monomer composition (2) at 80°C is lower than that of the (meth)acrylate (A) or the monomer composition (1). A method for producing a monomer composition. <2> The method for producing a monomer composition according to <1>, wherein the (meth)acrylate (A) is a compound represented by the following formula (A1).

[0007] [Chemical Formula] (In formula (A1), R 1A and R 2A each independently represent a divalent hydrocarbon group which may have a substituent and has 2 to 20 carbon atoms, R 3A represents a divalent hydrocarbon group having 5 to 16 carbon atoms, and R 4A and R 5A each independently represent a hydrogen atom or a methyl group.)

[0008] <3> In the compound represented by the formula (A1), the R 1A , R 2A and R 3A in which at least one has a cyclic structure, the method for producing the monomer composition according to <2>. <4> In the compound represented by the formula (A1), the R 3A is a group represented by any one of the following formulas (a) to (e), the method for producing the monomer composition according to <2> or <3>.

[0009]

Chemical formula

[0010]

Chemical formula

[0011] <5> The method for producing the monomer composition according to any one of <1> to <4>, wherein the (meth)acrylate (B) does not contain a urethane bond in the molecule. <6> The method for producing the monomer composition according to any one of <1> to <5>, wherein the (meth)acrylate (B) is a compound represented by the following formula (B1) or the following formula (B2).

[0012]

Chemical formula

[0013]

Chemical formula

[0014] <7> The method for producing a monomer composition according to any one of <1> to <6>, including a synthesis step of synthesizing the (meth)acrylate (A) in a reactor before the step (1). <8> In the step (1), using the monomer composition (1), in the step (1), with the monomer composition (1) being in a state accommodated in the reactor in the synthesis step, the monomer composition (1) and the (meth)acrylate (B) or the monomer composition (2) are mixed. The method for producing a monomer composition according to <7>. <9> A method for producing a polymerizable composition, including a step of producing a monomer composition by the method for producing a monomer composition according to any one of <1> to <8>, and a step of mixing the monomer composition and a polymerization initiator to prepare a polymerizable composition. <10> A monomer composition including a (meth)acrylate (A) having a urethane bond and two or more (meth)acryloyl groups, and a (meth)acrylate (B) other than the (meth)acrylate (A), wherein the (meth)acrylate (A) has a viscosity of 100 mPa·s or more at 80°C, and the (meth)acrylate (B) has a viscosity smaller than that of the (meth)acrylate (A) at 80°C. <11> A polymerizable composition including the monomer composition according to <10> and a polymerization initiator. <12> The polymerizable composition according to <11>, which is for dental materials.

Advantages of the Invention

[0015] The present disclosure can provide a method for producing a monomer composition capable of producing a monomer composition with high uniformity, a method for producing a polymerizable composition using the monomer composition produced by the method for producing the monomer composition, and a monomer composition and a polymerizable composition with high uniformity.

Embodiments for Carrying Out the Invention

[0016] In this specification, a numerical range represented by "~" or "-" means a range including the numerical values described before and after "~" or "-" as the lower limit value and the upper limit value.

[0017] [Production method of monomer composition] The production method of the monomer composition according to the present disclosure includes a step (1) of mixing a (meth)acrylate (A) having a urethane bond and two or more (meth)acryloyl groups or a monomer composition (1) containing the (meth)acrylate (A) with a (meth)acrylate (B) other than the (meth)acrylate (A) or a monomer composition (2) containing the (meth)acrylate (B) in a state where the viscosity of the (meth)acrylate (A) or the monomer composition (1) is 3,000 mPa·s or less to produce a monomer composition (3). In this step (1), the viscosity of the (meth)acrylate (A) or the monomer composition (1) at 80°C is 100 mPa·s or more, and the viscosity of the (meth)acrylate (B) or the monomer composition (2) at 80°C is lower than that of the (meth)acrylate (A) or the monomer composition (1).

[0018] As described above, in the conventional production method of the monomer composition, the uniformity of the obtained monomer composition may not be sufficient. The production method of the monomer composition according to the present disclosure mixes the (meth)acrylate (A) or the monomer composition (1) and the (meth)acrylate (B) or the monomer composition (2) having relatively low viscosity in a low-viscosity state where the viscosity is 3,000 mPa·s or less by mixing in a state where the viscosity of the (meth)acrylate (A) or the monomer composition (1) is 3,000 mPa·s or less. By doing so, the dispersibility of each other is improved, and a monomer composition excellent in uniformity can be provided.

[0019] ((Meth)acrylate (A) and monomer composition (1)) In the step (1), the (meth)acrylate (A) or the monomer composition (1) is used. The above-mentioned (meth)acrylate (A) is a (meth)acrylate having a urethane bond and two or more (meth)acryloyl groups, and the monomer composition (A) contains the (meth)acrylate (A). In the above-mentioned step (1), from the viewpoint of simplicity, it is preferable to use the monomer composition (1). Also, in the above-mentioned step (1), the content of the (meth)acrylate (A) contained in the monomer composition (1) measured by high performance liquid chromatography (HPLC) may be appropriately adjusted according to the function required for the (meth)acrylate (A). For example, when it is desired to suppress the function required for the (meth)acrylate (A) in the monomer composition (1), its content may be low, and when it is desired to enhance the function required for the (meth)acrylate (A) in the monomer composition (1), its content may be high. For example, in the above-mentioned step (1), from the viewpoint of imparting high mechanical strength to the cured product, the content of the (meth)acrylate (A) contained in the monomer composition (1) measured by high performance liquid chromatography (HPLC) is preferably 10 area% or more, more preferably 20 area% or more, still more preferably 25 area% or more, and particularly preferably 30 area% or more (50 area% or more, 70 area% or more, 80 area% or more, 90 area% or more, etc.) based on the total amount of the monomer composition (1). In the present disclosure, the measurement conditions of high performance liquid chromatography (HPLC) for measuring the content of the (meth)acrylate (A) contained in the monomer composition (1) may be appropriately set according to the structure of the (meth)acrylate (A) and the like. For example, after dissolving the monomer composition in CH3CN, the measurement may be carried out on the monomer composition under the conditions of a flow rate of 1.00 mL / min with respect to an eluent of CH3CN / H2O = 70 / 30. Also, as the column, for example, a column (ODS column) in which a filler having an octadecylsilyl group on the surface is melted may be used.

[0020] Further, from the viewpoint of simplicity, the monomer composition (1) is preferably a reaction product obtained by synthesizing the (meth)acrylate (A), and more preferably a reaction product obtained by reacting a hydroxy(meth)acrylate compound with an iso(thio)cyanate compound. Further, from the viewpoint of simplicity, the reaction product is preferably an unpurified reaction product.

[0021] The viscosity of the (meth)acrylate (A) or the monomer composition (1) at 80°C is 100 mPa·s or more, and from the viewpoint of uniformity, it is preferably 2,000 mPa·s or less, more preferably 1,500 mPa·s or less, and particularly preferably 1,000 mPa·s or less. On the other hand, from the viewpoint of improving the mechanical strength of the cured product, the viscosity of the (meth)acrylate (A) or the monomer composition (1) at 80°C is preferably 100 mPa·s or more, more preferably 200 mPa·s or more, and particularly preferably 300 mPa·s or more. Further, from the viewpoints of uniformity and handleability, the viscosity of the (meth)acrylate (A) or the monomer composition (1) at 50°C is preferably 100,000 mPa·s or less, more preferably 70,000 mPa·s or less, and particularly preferably 240,000 mPa·s or less. On the other hand, from the viewpoints of improving the mechanical strength of the cured product, improving the adhesion performance, reducing the polymerization shrinkage, the function of adjusting the consistency of the composition, adjusting the refractive index, etc., the viscosity of the (meth)acrylate (A) or the monomer composition (1) at 50°C is preferably 1,000 mPa·s or more, more preferably 2,000 mPa·s or more, and particularly preferably 3,000 mPa·s or more.

[0022] The refractive index of the (meth)acrylate (A) or the monomer composition (1) at 25°C is preferably 1.45 or more, more preferably 1.485 or more, still more preferably 1.485 to 1.600, and particularly preferably 1.485 to 1.550 from the viewpoints of high refractive index and dental material suitability.

[0023] From the viewpoints of uniformity, curability, viscosity, high refractive index property, and dental material suitability, the (meth)acrylate (A) is preferably a compound represented by the following formula (A1).

[0024] [Chemical formula] (In formula (A1), R 1A and R 2A each independently represent a divalent hydrocarbon group which may have a substituent having 2 to 20 carbon atoms, R 3A represents a divalent hydrocarbon group having 5 to 16 carbon atoms, and R 4A and R 5A each independently represent a hydrogen atom or a methyl group.)

[0025] In formula (A1), R 1A and R 2A are each independently preferably a linear, branched or cyclic alkylene group having 2 to 6 carbon atoms (also referred to as "number of carbon atoms"), more preferably a linear or branched alkylene group having 2 to 4 carbon atoms, still more preferably an ethylene group, 1,2-propylene group, or 1,2-butylene group, and particularly preferably a 1,2-propylene group, from the viewpoints of viscosity, high refractive index property, and dental material suitability. Also, examples of the substituent that R 1A and R 2A may have include substituents such as halogen atoms such as chlorine atom and bromine atom, alkoxy group, nitro group, hydroxy group, carbonyl group, and alkyl group Furthermore, in the compound represented by the formula (A1), from the viewpoints of viscosity, high refractive index property, and dental material suitability, at least one of the above R 1A , R 2A and R 3A preferably has a cyclic structure, and it is more preferable that the above R 3A has a cyclic structure. Further, from the viewpoints of viscosity, high refractive index property, and dental material suitability, the cyclic structure is preferably an aliphatic hydrocarbon cyclic structure. In the compound represented by the formula (A1), the R 3A is preferably a group represented by any of the following formulas (a) to (e) from the viewpoints of viscosity, high refractive index property, and dental material suitability, more preferably a group represented by any of the following formulas (c) to (e), and particularly preferably a group represented by the following formula (c) or the following formula (e).

[0026] [Chemical formula]

[0027] [Chemical formula] (In the formulas (a) to (e), * indicates the bonding position.)

[0028] R in the formula (A1) 4A and R 5A are each independently preferably a methyl group from the viewpoints of viscosity, high refractive index property, and dental material suitability.

[0029] The method for synthesizing the (meth)acrylate (A) is not particularly limited, and for example, it can be easily synthesized by reacting a hydroxy(meth)acrylate compound with an iso(thio)cyanate compound.

[0030] Regarding the hydroxy(meth)acrylate compound, for example, the descriptions in paragraphs 0096 to 0101 of International Publication No. 2019 / 107323 can be appropriately referred to. Examples of the hydroxy(meth)acrylate compound include, specifically, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 1,4-cyclohexanedimethanol mono(meth)acrylate, and the like. As the hydroxy(meth)acrylate compound, one kind may be used, or two or more kinds may be combined.

[0031] Examples of the iso(thio)cyanate compound include polyisocyanate compounds such as hexamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, pentamethylene diisocyanate, m-xylylene diisocyanate, 1,3-tetramethylxylylene diisocyanate, isophorone diisocyanate, bis(isocyanatomethyl)cyclohexane, bis(isocyanatocyclohexyl)methane, 2,5-bis(isocyanatomethyl)bicyclo[2.2.1]heptane, 2,6-bis(isocyanatomethyl)bicyclo[2.2.1]heptane, tolylene diisocyanate, phenylene diisocyanate, 4,4'-diphenylmethane diisocyanate; aliphatic polyisothiocyanate compounds such as hexamethylene diisothiocyanate, lysine diisothiocyanate methyl ester, lysine triisothiocyanate, m-xylylene diisothiocyanate, a mixture of 2,5-bis(isocyanatomethyl)bicyclo[2.2.1]heptane and 2,6-bis(isocyanatomethyl)bicyclo[2.2.1]heptane, bis(isothiocyanatomethyl) sulfide, bis(isothiocyanatoethyl) sulfide, bis(isothiocyanatoethyl) disulfide; isophorone diisothiocyanate, bis(isothiocyanatomethyl)cyclohexane, dicyclohexylmethane diisothiocyanate, cyclohexane diisothiocyanate, methylcyclohexane diisothiocyanate, 2,5-bis(isothiocyanatomethyl)bicyclo[2.2.1]heptane, 2,6-bis(isothiocyanatomethyl)bicyclo[2.2.1] Alicyclic polyisothiocyanate compounds such as heptane, 3,8-bis(isothiocyanatomethyl)tricyclodecane, 3,9-bis(isothiocyanatomethyl)tricyclodecane, 4,8-bis(isothiocyanatomethyl)tricyclodecane, 4,9-bis(isothiocyanatomethyl)tricyclodecane; Aromatic polyisothiocyanate compounds such as tolylene diisothiocyanate, 4,4-diphenylmethane diisothiocyanate, diphenyl disulfide-4,4-diisothiocyanate; Sulfur-containing heterocyclic polyisothiocyanate compounds such as 2,5-diisothiocyanatothiophene, 2,5-bis(isothiocyanatomethyl)thiophene, 2,5-isothiocyanatotetrahydrothiophene, 2,5-bis(isothiocyanatomethyl)tetrahydrothiophene, 3,4-bis(isothiocyanatomethyl)tetrahydrothiophene, 2,5-diisothiocyanato-1,4-dithiane, 2,5-bis(isothiocyanatomethyl)-1,4-dithiane, 4,5-diisothiocyanato-1,3-dithiolane, 4,5-bis(isothiocyanatomethyl)-1,3-dithiolane; etc. are mentioned. As the iso(thio)cyanate compound, one kind may be used, or two or more kinds may be combined.

[0032] ((Meth)acrylate (B) and monomer composition (2)) In the said step (1), the said (meth)acrylate (B) or the said monomer composition (2) is used. The said (meth)acrylate (B) is a (meth)acrylate other than the said (meth)acrylate (A), and the said monomer composition (B) contains the said (meth)acrylate (B). In the said step (1), from the viewpoint of simplicity, it is preferable to use the said monomer composition (2). In addition, in the step (1), from the viewpoints of uniformity and curability, the content of the (meth)acrylate (B) contained in the monomer composition (2) is preferably 70% by mass or more, more preferably 80% by mass or more, still more preferably 85% by mass or more, and particularly preferably 90% by mass or more based on the mass of the entire monomer composition (2).

[0033] Further, from the viewpoint of simplicity, the monomer composition (2) may be a reaction product obtained by synthesizing the (meth)acrylate (B). For example, a commercially available product of the pre-synthesized (meth)acrylate (B) may be used, or the (meth)acrylate (B) may be synthesized separately. Further, from the viewpoint of simplicity, the reaction product is preferably an unpurified reaction product.

[0034] The viscosity of the (meth)acrylate (B) or the monomer composition (2) at 80°C is lower than the viscosity of the (meth)acrylate (A) or the monomer composition (1), and from the viewpoints of uniformity and handleability, it is preferably less than 100 mPa·s, more preferably 50 mPa·s or less, and particularly preferably 0.1 mPa·s to 25 mPa·s. In addition, from the viewpoints of uniformity and handleability, the viscosity of the (meth)acrylate (B) or the monomer composition (2) at 25°C is preferably 2,000 mPa·s or less, more preferably 1,500 mPa·s or less, and particularly preferably 1 mPa·s to 1,000 mPa·s.

[0035] From the viewpoints of high refractive index and dental material suitability, the refractive index of the (meth)acrylate (B) or the monomer composition (2) at 25°C is preferably 1.40 or more, more preferably 1.45 or more, and particularly preferably 1.45 to 1.60.

[0036] Examples of the (meth)acrylate (B) include neopentyl glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,8-octanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, 1,10-decanediol di(meth)acrylate, tricyclodecane dimethanol di(meth)acrylate, ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, tetrapropylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, 2,2-bis[4-(3-(meth)acryloyloxy-2-hydroxypropoxy)phenyl]propane, ethylene oxide-modified bisphenol A di(meth)acrylate, propylene oxide-modified bisphenol A di(meth)acrylate, 2,2,4-trimethylhexamethylene bis(2-carbamoyloxyethyl)dimethacrylate (urethane dimethacrylate: UDMA), erythritol di(meth)acrylate, sorbitol di(meth)acrylate, mannitol di(meth)acrylate, pentaerythritol di(meth)acrylate, dipentaerythritol di(meth)acrylate, glycerol di(meth)acrylate, methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, n-butyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, cyclobutyl (meth)acrylate, cyclohexyl (meth)acrylate, (tetrahydrofuran-2-yl)(meth)acrylate, etc. The (meth)acrylate (B) may be used alone or in combination of two or more kinds.

[0037] From the viewpoints of uniformity, viscosity, and curability, it is preferable that the (meth)acrylate (B) does not contain a urethane bond in the molecule, and it is more preferable that it does not contain a urethane bond and a thiourethane bond. Further, from the viewpoints of uniformity, viscosity, and curability, it is preferable that the (meth)acrylate (B) is a compound represented by the following formula (B1) or the following formula (B2), and it is more preferable that it is a compound represented by the following formula (B1).

[0038] [Chemical formula] (In formula (B1), R 1B1 represents a divalent organic group having 2 to 20 carbon atoms which may have an oxygen atom and does not have a urethane bond, and R 2B1 and R 3B1 each independently represent a hydrogen atom or a methyl group.)

[0039] [Chemical formula] (In formula (B2), R 1B2 represents a monovalent organic group having 2 to 20 carbon atoms, and R 2B2 represents a hydrogen atom or a methyl group.)

[0040] The carbon number of the R 1B1 in formula (B1) is preferably 4 to 20, and more preferably 5 to 20. Further, as the R 1B1 in formula (B1), from the viewpoints of uniformity, viscosity, and curability, it is preferably a group obtained by removing two hydroxy groups from one compound selected from the group consisting of polyethylene glycol, neopentyl glycol, dicyclopentanol tricyclodecane dimethanol, and ethoxylated bisphenol A. The R 2B1 and R 3B1 in formula (B1) are preferably methyl groups from the viewpoints of viscosity and dental material suitability.

[0041] The R in formula (B2) 1B2 preferably has 2 to 10 carbon atoms, more preferably 2 to 6 carbon atoms. Further, the R in formula (B2) 1B2 is preferably an alkyl group or a cycloalkyl group. The R in formula (B2) 2B2 is preferably a methyl group from the viewpoints of viscosity and dental material suitability.

[0042] (Step (1)) The method for producing the monomer composition according to the present disclosure includes a step (1) of producing a monomer composition (3) by mixing a (meth)acrylate (A) having a urethane bond and two or more (meth)acryloyl groups or a monomer composition (1) containing the (meth)acrylate (A) with a (meth)acrylate (B) other than the (meth)acrylate (A) or a monomer composition (2) containing the (meth)acrylate (B) in a state where the viscosity of the (meth)acrylate (A) or the monomer composition (1) is 3,000 mPa·s or less.

[0043] The usage amount of the (meth)acrylate (A) or the monomer composition (1) in the step (1) is preferably 10% by mass or more, more preferably 20% to 98% by mass, and particularly preferably 25% to 95% by mass based on the total usage amount of the (meth)acrylate (A) or the monomer composition (1) and the (meth)acrylate (B) or the monomer composition (2) from the viewpoints of uniformity, viscosity, and dental material suitability. Further, in the step (1), it is preferable that no compound other than the reaction substrate, reaction product, and catalyst (for example, solvent, etc.) is contained or the content thereof is 1% by mass or less in the synthesis step described later and the step of synthesizing the (meth)acrylate (B). More preferably, no compound other than the reaction substrate, reaction product, and catalyst (for example, solvent, etc.) is contained or the content thereof is 0.1% by mass or less. Particularly preferably, no compound other than the reaction substrate, reaction product, and catalyst (for example, solvent, etc.) is contained.

[0044] The viscosity of the (meth)acrylate (A) or the monomer composition (1) during mixing in the step (1) is 3,000 mPa·s or less, and from the viewpoint of uniformity, it is preferably 2,000 mPa·s or less, more preferably 1,500 mPa·s or less, and particularly preferably 1,000 mPa·s or less. On the other hand, from the viewpoint of improving the mechanical strength of the cured product, the viscosity of the (meth)acrylate (A) or the monomer composition (1) during mixing in the step (1) is preferably 100 mPa·s or more, more preferably 200 mPa·s or more, and particularly preferably 300 mPa·s or more.

[0045] The temperature during mixing in the step (1) may be appropriately set to adjust the viscosity of the (meth)acrylate (A) or the monomer composition (1). For example, in order to lower the viscosity, a high temperature may be used, and in order to increase the viscosity, a low temperature may be used for adjustment. For example, from the viewpoint of uniformity, it is preferably 40°C to 150°C, more preferably 50°C to 100°C, and particularly preferably 60°C to 90°C.

[0046] In addition, from the viewpoint of simplicity, the method for producing the monomer composition according to the present disclosure preferably includes a synthesis step of synthesizing the (meth)acrylate (A) in a reactor before the step (1). In the step (1), the monomer composition (1) is used, and in the step (1), it is more preferable that the monomer composition (1) and the (meth)acrylate (B) or the monomer composition (2) are mixed in a state where the monomer composition (1) is contained in the reactor in the synthesis step. The synthesis step is preferably a step of reacting a hydroxy(meth)acrylate compound with an iso(thio)cyanate compound to synthesize the (meth)acrylate (A).

[0047] In the method for producing the monomer composition according to the present disclosure, from the viewpoint of simplicity, it is preferable that the reaction product containing the (meth)acrylate (A) obtained in the synthesis step is used as it is in the step (1) and is mixed with the (meth)acrylate (B) or the monomer composition (2). Further, in the method for producing the monomer composition according to the present disclosure, it is preferable that the synthesis step and the step (1) are continuously performed using the same reactor.

[0048] Further, the method for producing the monomer composition according to the present disclosure may include a step of synthesizing the (meth)acrylate (B) before the step (1) from the viewpoint of simplicity. In the method for producing the monomer composition according to the present disclosure, from the viewpoint of simplicity, the reaction product containing the (meth)acrylate (B) obtained in the step of synthesizing the (meth)acrylate (B) may be used as it is in the step (1) and mixed with the (meth)acrylate (A) or the monomer composition (1), or the pre-synthesized (meth)acrylate (B) may be mixed with the (meth)acrylate (A) or the monomer composition (1).

[0049] [Method for producing polymerizable composition] The method for producing a polymerizable composition according to the present disclosure includes a step of producing a monomer composition by the method for producing a monomer composition according to the present disclosure, and a step of mixing the monomer composition and a polymerization initiator to prepare a polymerizable composition. The mixing method in the step of preparing the polymerizable composition is not particularly limited, and it may be mixed by a known method. Further, the polymerizable composition obtained by the method for producing a polymerizable composition according to the present disclosure can be suitably used as a polymerizable composition for dental materials.

[0050] The blending amount of the monomer composition in the step of preparing the polymerizable composition is preferably 20% by mass to 80% by mass, more preferably 20% by mass to 50% by mass, based on 100% by mass of the polymerizable composition.

[0051] (Coinitiator) As the coinitiator, general coinitiators, particularly general coinitiators used in the dental field, can be preferably used, and are selected in consideration of the polymerizability and polymerization conditions of polymerizable compounds such as (meth)acrylate (A) and (meth)acrylate (B).

[0052] When performing room temperature polymerization, as the coinitiator, for example, a redox-based coinitiator combining an oxidizing agent and a reducing agent is preferable. When using a redox-based coinitiator, the oxidizing agent and the reducing agent are in a separately packaged form, and the two may be mixed immediately before use.

[0053] The oxidizing agent is not particularly limited, and examples include organic peroxides such as diacyl peroxides, peroxy esters, dialkyl peroxides, peroxy ketals, ketone peroxides, and hydroperoxides. Examples of the above organic peroxides include diacyl peroxides such as benzoyl peroxide; peroxy esters such as t-butyl peroxybenzoate; dialkyl peroxides such as dicumyl peroxide; peroxy ketals such as 1,1-bis(t-butylperoxy)-3,3,5-trimethylcyclohexane; ketone peroxides such as methyl ethyl ketone peroxide; and hydroperoxides such as t-butyl hydroperoxide.

[0054] Also, the reducing agent is not particularly limited, and for example, a tertiary amine is used. Examples of the tertiary amine include N,N-dimethylaniline, N,N-dimethyl-p-toluidine, and N,N-dimethyl-m-toluidine.

[0055] In addition to these organic peroxide / amine systems, redox-based coinitiators such as cumene hydroperoxide / thiourea system, ascorbic acid / Cu2+ salt system, and organic peroxide / amine / sulfinic acid (or its salt) system can be used. Also, tributyl borane, organic sulfinic acid, etc. are preferably used as the coinitiator.

[0056] When performing thermal polymerization by heating, polymerization initiators such as peroxides and azo compounds are preferred. The peroxide is not particularly limited, and examples thereof include benzoyl peroxide, t-butyl hydroperoxide, cumene hydroperoxide and the like. The azo compound is not particularly limited, and examples thereof include azobisisobutyronitrile and the like.

[0057] When performing photopolymerization by visible light irradiation, redox initiators such as α-diketone / tertiary amine, α-diketone / aldehyde, α-diketone / mercaptan and the like are preferred. The photopolymerization initiator is not particularly limited, and examples thereof include α-diketone / reducing agent, ketal / reducing agent, thioxanthone / reducing agent and the like. Examples of the α-diketone include camphorquinone, benzyl, 2,3-pentanedione and the like. Examples of the ketal include benzyldimethyl ketal, benzyldiethyl ketal and the like. Examples of the thioxanthone include 2-chlorothioxanthone, 2,4-diethylthioxanthone and the like. Examples of the reducing agent include Michler's ketone and the like, tertiary amines such as 2-(dimethylamino)ethyl methacrylate, N,N-bis[(meth)acryloyloxyethyl]-N-methylamine, ethyl N,N-dimethylaminobenzoate, butyl 4-dimethylaminobenzoate, butoxyethyl 4-dimethylaminobenzoate and the like; aldehydes such as citronellal; compounds having a thiol group such as 2-mercaptobenzoxazole; and the like. Systems such as α-diketone / organic peroxide / reducing agent obtained by adding an organic peroxide to these redox systems are also preferably used.

[0058] When performing photopolymerization by ultraviolet irradiation, photopolymerization initiators such as benzoin alkyl ether and benzyldimethyl ketal are preferred. Also, photopolymerization initiators of (bis)acylphosphine oxides are preferably used.

[0059] Among (bis)acylphosphine oxides, examples of acylphosphine oxides include 2,4,6-trimethylbenzoyldiphenylphosphine oxide and the like. Examples of bisacylphosphine oxides include bis-(2,6-dichlorobenzoyl)phenylphosphine oxide and the like. These (bis)acylphosphine oxide photoinitiators may be used alone or in combination with reducing agents such as various amines, aldehydes, mercaptans, sulfinates, etc. These (bis)acylphosphine oxide photoinitiators may also be used in combination with the above visible light photoinitiators.

[0060] The polymerization initiator may be used alone or in combination of two or more. The compounding amount of the polymerization initiator is preferably 0.01% by mass to 20% by mass, more preferably 0.1% by mass to 5% by mass, based on 100% by mass of the polymerizable composition.

[0061] (Filler) The polymerizable composition obtained by the method for producing a polymerizable composition according to the present disclosure (the polymerizable composition according to the present disclosure) preferably contains a filler. As the filler, general fillers used in the dental field can be used. Fillers are generally classified into organic fillers and inorganic fillers. Examples of organic fillers include powders such as polymethyl methacrylate.

[0062] Examples of the inorganic filler include fine powders such as various glasses (mainly composed of silicon dioxide and containing oxides such as heavy metals, boron, and aluminum as required), various ceramics, diatomaceous earth, kaolin, clay minerals (such as montmorillonite), activated clay, synthetic zeolite, mica, calcium fluoride, ytterbium fluoride, calcium phosphate, barium sulfate, zirconium dioxide, titanium dioxide, and hydroxyapatite. Specific examples of such inorganic fillers include, for example, barium borosilicate glass (Kimble Raysoorb T3000, shot 8235, shot GM27884, shot GM39923, etc.), strontium borosilicate glass (Raysoorb T4000, shot G018-093, shot GM32087, etc.), lanthanum glass (shot GM31684, etc.), fluoroaluminosilicate glass (shot G018-091, shot G018-117, etc.), and borosilicate glass containing zirconium, cesium, etc. (shot G018-307, G018-308, G018-310, etc.).

[0063] Alternatively, an organic-inorganic composite filler obtained by pre-adding a polymerizable compound to an inorganic filler, making it into a paste, then polymerizing and curing it, and pulverizing it may be used.

[0064] These fillers may be surface-treated with a surface treatment agent such as a silane coupling agent according to the purpose. As the surface treatment agent, known silane coupling agents, for example, organosilicon compounds such as methacryloxyalkyltrimethoxysilane are used.

[0065] These fillers may be used alone or in combination of two or more. The blending amount of the filler may be appropriately determined in consideration of the workability (viscosity) of the dental material composition (for example, composite resin paste) and the mechanical properties of its cured product. With respect to 100 parts by mass of all components other than the filler contained in the polymerizable composition, 10 parts by mass to 2,000 parts by mass is preferable, 50 parts by mass to 1,000 parts by mass is more preferable, and 100 parts by mass to 600 parts by mass is even more preferable.

[0066] The polymerizable composition according to the present disclosure may appropriately contain, as needed, a monomer composition obtained by the method for producing a monomer composition according to the present disclosure (the monomer composition according to the present disclosure), a polymerization initiator, and components other than the filler. For example, it may contain the aforementioned polymerization inhibitor for improving storage stability. Also, in order to adjust the color tone, it may contain known pigments, dyes, and other coloring matters. Further, in order to improve the strength of the cured product, it may contain known fibers and other reinforcing materials. Also, the polymerizable composition according to the present disclosure may contain additives such as bactericides, disinfectants, stabilizers, and preservatives as needed as long as the effects in the present disclosure are exhibited.

[0067] The polymerizable composition according to the present disclosure can be cured under appropriate conditions by the polymerization method of the aforementioned polymerization initiator. For example, in the case of the polymerizable composition according to the present disclosure containing a photopolymerization initiator by visible light irradiation, after processing the polymerizable composition into a predetermined shape, a desired cured product can be obtained by irradiating visible light for a predetermined time using a known light irradiation device. Conditions such as irradiation intensity and irradiation intensity can be appropriately changed according to the curability of the polymerizable composition. Also, a cured product cured by light irradiation including visible light may be heat-treated under more appropriate conditions to improve the mechanical properties of the cured product.

[0068] The cured product of the polymerizable composition according to the present disclosure obtained as described above can be suitably used as a dental material. The method of using the polymerizable composition according to the present disclosure is not particularly limited as long as it is generally known as a method of using a dental material. For example, the polymerizable composition according to the disclosure may be used in dental treatment. For example, the dental treatment method of the present disclosure may include a step of polymerizing the curable composition in the oral cavity to obtain a cured product. In this method, a method including a step of polymerizing in the oral cavity to obtain a cured product is suitable, for example, when a kit for preparing a curable composition is used for a dental adhesive resin cement, a composite resin for filling and restoration, and the like. The dental treatment method of the present disclosure may include a step of polymerizing the curable composition of the present disclosure outside the oral cavity to obtain a cured product, and a step of applying the cured product into the oral cavity. Thus, the step of polymerizing outside the oral cavity to obtain a cured product may be a step of polymerizing the curable composition in a mold to obtain a cured product. The cured product obtained outside the oral cavity may be processed as necessary, and the processed cured product may be applied into the oral cavity. The method of polymerizing outside the oral cavity to obtain a cured product is suitable, for example, when the cured product is used for a CAD / CAM resin block, a temporary crown, an artificial tooth, etc.

[0069] The polymerizable composition and dental material according to the present disclosure can be preferably used, for example, as dental restoration materials, denture base resins, denture base liners, impression materials, luting materials (resin cements, resin-modified glass ionomer cements, etc.), dental adhesives (orthodontic adhesives, cavity coating adhesives, etc.), dental fissure sealants, CAD / CAM resin blocks, temporary crowns, artificial tooth materials, etc. Further, when classifying dental restoration materials by application range, they can be classified into composite resins for crowns, composite resins for filling dental caries cavities, composite resins for building abutments, composite resins for filling and restoration, etc. Among these, the polymerizable composition and dental material according to the present disclosure are particularly suitable for dental restoration materials such as composite resins.

[0070] 〔Monomer composition〕 The monomer composition according to the present disclosure includes a (meth)acrylate (A) having a urethane bond and two or more (meth)acryloyl groups, and a (meth)acrylate (B) other than the (meth)acrylate (A). The (meth)acrylate (A) has a viscosity of 100 mPa·s or more at 80°C, and the (meth)acrylate (B) has a viscosity at 80°C lower than that of the (meth)acrylate (A). Further, the monomer composition according to the present disclosure is preferably produced by the method for producing the monomer composition according to the present disclosure.

[0071] The preferred embodiments of the (meth)acrylate (A) and the (meth)acrylate (B) in the monomer composition according to the present disclosure are the same as the preferred embodiments of the (meth)acrylate (A) and the (meth)acrylate (B) described above in the method for producing the monomer composition according to the present disclosure.

[0072] In addition, from the viewpoints of uniformity and curability, the content of the (meth)acrylate (A) contained in the monomer composition according to the present disclosure measured by high performance liquid chromatography (HPLC) is preferably 10 area% or more, more preferably 20 area% or more, still more preferably 25 area% or more, and particularly preferably 30 area% or more (50 area% or more, 70 area% or more, 80 area% or more, 90 area% or more, etc.) with respect to the mass of the entire monomer composition. In addition, from the viewpoints of uniformity, viscosity, and dental material suitability, the content of the (meth)acrylate (A) in the monomer composition according to the present disclosure is preferably 10 mass% or more, more preferably 20 mass% to 98 mass%, and particularly preferably 25 mass% to 95 mass% with respect to the total content of the (meth)acrylate (A) and the (meth)acrylate (B). In addition, the monomer composition according to the present disclosure preferably does not contain a compound (for example, a solvent, etc.) other than the reaction substrate, reaction product, and catalyst during the synthesis of the (meth)acrylate (A) and during the synthesis of the (meth)acrylate (B), or the content thereof is 1 mass% or less, more preferably does not contain it or the content thereof is 0.1 mass% or less, and particularly preferably does not contain it.

[0073] [Polymerizable composition] The polymerizable composition according to the present disclosure includes the monomer composition according to the present disclosure and a polymerization initiator. In addition, the polymerizable composition according to the present disclosure can be suitably used as a polymerizable composition for dental materials.

[0074] The preferred embodiments of the components in the polymerizable composition according to the present disclosure are the same as the preferred embodiments of the components described above in the method for producing the polymerizable composition according to the present disclosure.

Examples

[0075] Hereinafter, the present disclosure will be described more specifically with reference to examples, but the present disclosure is not limited to the following examples. The abbreviations of the compounds used in the examples in the present disclosure are shown below. HEMA: 2-Hydroxyethyl methacrylate HPMA: Hydroxypropyl methacrylate (mixture of 2-hydroxypropyl ester and 2-hydroxy-1-methylethyl ester) 2HBMA: 2-Hydroxybutyl methacrylate (isomer mixture) NBDI: Mixture of 2,5-bis(isocyanatomethyl)bicyclo[2.2.1]heptane and 2,6-bis(isocyanatomethyl)bicyclo[2.2.1]heptane H6XDI: 1,3-Bis(isocyanatomethyl)cyclohexane IPDI: Isophorone diisocyanate DBTDL: Dibutyltin dilaurate BHT: Dibutylhydroxytoluene TEGDMA(3G): Triethylene glycol dimethacrylate NPG: Neopentyl glycol dimethacrylate DCP: Tricyclodecane dimethanol dimethacrylate 2,6E: Ethoxylated bisphenol A dimethacrylate UDMA: 2,2,4-Trimethylhexamethylene bis(2-carbamoyloxyethyl) dimethacrylate

[0076] 〔Method for measuring viscosity〕 The viscosities in the examples and comparative examples were measured using an EMS viscometer (EMS-1000S manufactured by Kyoto Electronic Industry Co., Ltd.).

[0077] 〔Method for measuring refractive index〕 The refractive indices in the examples and comparative examples were measured using an Abbe full digital refractometer (Abbemat 550 manufactured by Anton Paar). The temperature was controlled at 25°C.

[0078] 〔Uniformity evaluation〕 The methods for evaluating the uniformity in the examples and comparative examples are shown below. In the monomer compositions obtained in the examples and comparative examples, samples were collected at a depth of about 1 cm from the liquid surface in the container, and refractive index measurements were performed. Next, samples were collected at about 1 cm from the bottom of the sample, and refractive index measurements were performed. The difference in refractive indices at two points in the same sample was calculated, and the calculation results were evaluated based on the following criteria. For the operation of refractive index measurement, the measurement was performed with reference to the above-mentioned refractive index measurement method. A: 0.0001 or less B: More than 0.0001 and 0.0010 or less C: 0.0010 or more

[0079] 〔HPLC analysis〕 The content of each (meth)acrylate (A) in the monomer compositions (1A) to (1G) was subjected to HPLC analysis under the following analysis conditions according to the following procedure. - Analysis conditions - The HPLC chart spectra of the monomer compositions obtained in the examples and comparative examples were measured using an HPLC apparatus (LC-20AT manufactured by Shimadzu Corporation). In the HPLC analysis, a column YMC-Pack ODS-AM (manufactured by YMC Co., Ltd.) was used. After dissolving the monomer compositions obtained in the examples and comparative examples in CH3CN, the monomer compositions were measured with an eluent of CH3CN / H2O = 70 / 30 at a flow rate of 1.00 mL / min. - Analysis results - As a result of the HPLC analysis, the content of each (meth)acrylate (A) in the monomer compositions (1A) to (1G) described below was all 90 area% or more.

[0080] 〔Monomer compositions (2A) to (2D)〕 As shown in Table 4, as the monomer composition (2), triethylene glycol dimethacrylate (TEGDMA, monomer composition (2A)), neopentyl glycol dimethacrylate (NPG, monomer composition (2B)), ethoxylated bisphenol A dimethacrylate (2,6E, monomer composition (2C)), tricyclodecane dimethanol dimethacrylate (DCP, monomer composition (2D)) were prepared, and the viscosity at 80 °C, the viscosity at 25 °C, and the refractive index at 25 °C were measured according to the above-described viscosity measurement method and refractive index measurement method. The viscosities at 25 °C of the monomer compositions (2A) to (2D) were all 1 mPa·s to 1,000 mPa·s. The viscosity at 80 °C and the refractive index at 25 °C are shown in Table 4.

[0081] (Example 1) Into a four-necked flask equipped with a well-dried stirring blade and a thermometer, 0.05 part by mass of DBTDL, 0.05 part by mass of BHT, and 29.15 parts by mass of HPMA as a hydroxy (meth) acrylate compound were charged and dissolved to form a homogeneous solution. Then, the temperature of this solution was raised to 70 °C, and further 20.85 parts by mass of NBDI as an iso (thio) cyanate compound was added dropwise over 1 hour. Since the internal temperature rose due to the heat of reaction during the dropwise addition, the dropping amount was controlled so that the temperature would be 80 °C or lower. After the total amount of NBDI was added dropwise, the reaction temperature was maintained at 80 °C and the reaction was carried out for 5 hours. At this time, the progress of the reaction was traced by HPLC analysis to confirm the end point of the reaction, and 50 parts by mass of a monomer composition (1A) was obtained. The (meth) acrylate (A) contained in the monomer composition (1A) is shown below. The viscosities of the monomer composition (1A) at 80 °C, 50 °C, and the refractive index at 25 °C are shown in Table 3. Without taking out the monomer composition (1A) from the flask, then 5.56 parts by mass of a monomer composition (2A) as a diluent was added and stirred at 80 °C for 2 hours to obtain a monomer composition (3) as a mixture. The temperature and the viscosity at that time when the monomer composition (1A) was mixed with the monomer composition (2A) (that is, when the monomer composition (2A) was added) are shown in Table 1. The refractive indices of the upper layer and the lower layer of the obtained mixture (monomer composition (3)) were measured according to the method described in the homogeneity evaluation, and the homogeneity was evaluated. The results are shown in Table 1.

[0082] (Meth) acrylate (A) contained in the monomer composition (1A): The following compound

[0083] [Chemical formula]

[0084] (Examples 2 to 34) A monomer composition (1B) to (1G) was obtained in the same manner as in Example 1, except that the hydroxy (meth) acrylate compound and the iso (thio) cyanate compound were changed to the compounds shown in Table 2. The refractive index at 25 °C, the viscosity at 80 °C, and the viscosity at 50 °C are as shown in Table 2. The structure of each (meth) acrylate (A) is as follows. Also, a monomer composition (3) as a mixture was obtained in the same manner as in Example 1, except that the monomer composition (1A) and the monomer composition (2A) as a diluent were changed to the monomer composition (1) and the monomer composition (2) shown in Table 1, respectively, and the homogeneity evaluation was performed in the same manner as in Example 1 using each monomer composition (3). The results are shown in Table 1.

[0085] (Meth) acrylate (A) contained in monomer composition (1B): The following compound

[0086] [Chemical formula]

[0087] (Meth) acrylate (A) contained in monomer composition (1C): The following compound

[0088] [Chemical formula]

[0089] (Meth) acrylate (A) contained in monomer composition (1D): The following compound

[0090] [Chemical formula]

[0091] (Meth) acrylate (A) contained in monomer composition (1E): The following compound

[0092] [Chemical formula]

[0093] (Meth)acrylate (A) contained in the monomer composition (1F): The following compound

[0094]

Chemical formula

[0095] (Meth)acrylate (A) contained in the monomer composition (1G): The following compound

[0096]

Chemical formula

[0097] (Comparative Example 1) Into a four-necked flask equipped with a sufficiently dried stirring blade and a thermometer, 0.05 parts by mass of DBTDL, 0.05 parts by mass of BHT, and 29.15 parts by mass of HPMA were charged and dissolved to form a homogeneous solution. Then, the solution was heated to 70°C, and further 20.85 parts by mass of NBDI was added dropwise over 1 hour. Since the internal temperature increased due to the heat of reaction during the dropwise addition, the dropping amount was controlled so that the internal temperature would be 80°C or lower. After all of the HPMA was added dropwise, the reaction temperature was maintained at 80°C and the reaction was carried out for 5 hours. At this time, the progress of the reaction was traced by HPLC analysis to confirm the end point of the reaction, and 50 parts by mass of the monomer composition (1A) was obtained. The refractive index at 25°C was 1.4937. The monomer composition (1A) was taken out from the flask and allowed to stand until it reached 25°C. 5.56 parts by mass of the monomer composition (2A) was added to 50 parts by mass of the above-described monomer composition (1A), and the mixture was stirred at 50°C for 2 hours. The refractive indices of the upper layer and the lower layer of the obtained mixture were measured according to the method described in the above uniformity evaluation. The difference in the refractive indices of both was 0.0025.

[0098] (Comparative Examples 2 to 33) A monomer composition (1B) to (1G) was obtained in the same manner as in Comparative Example 1, except that the hydroxy methacrylate compound and the isocyanate compound were changed to the compounds shown in Table 3. The refractive index at 25°C and the viscosity at 80°C are as shown in Table 3. Further, a uniformity evaluation was performed in the same manner as in Comparative Example 1, except that the diluent was changed from the monomer composition (2A) to the compounds shown in Tables 2 and 4. The results are shown in Table 2.

[0099]

Table 1

[0100]

Table 2

[0101]

Table 3

[0102]

Table 4

[0103] Note that “-” in Table 3 indicates that the corresponding viscosity has not been measured.

[0104] As shown in Tables 1 and 2, the monomer compositions obtained in Examples 1 to 34 were superior in uniformity compared to the monomer compositions obtained in Comparative Examples 1 to 33.

[0105] (Examples 1A to 34A and Comparative Examples 1A to 33A) 〔Solubility Evaluation〕 The solubility evaluation of the mixture of the monomer composition (1) and the monomer composition (2) in the above Examples 1 to 34 or Comparative Examples 1 to 33 was carried out. Specifically, except that the stirring time for obtaining the monomer composition (3) by mixing the monomer composition (1) in the above Examples 1 to 34 or Comparative Examples 1 to 33 with the corresponding monomer composition (2) was changed from 2 hours to the time until the dissolution of the monomer composition (1) could be visually confirmed, the monomer composition (3) was obtained under the same conditions as in Examples 1 to 34 or Comparative Examples 1 to 33. At that time, the time until the dissolution could be visually confirmed was confirmed for each, and the solubility was evaluated. In addition, the examples and comparative examples related to the solubility evaluation corresponding to Examples 1 to 34 and Comparative Examples 1 to 33 are Examples 1A to 34A and Comparative Examples 1A to 33A, respectively. As a result of the solubility evaluation, it was confirmed that in all of Examples 1A to 34A, the monomer composition (1) was dissolved within 5 minutes from the start of stirring. On the other hand, for Comparative Examples 1A to 33A, it was confirmed that it took 4 hours or more for the monomer composition (1) to be dissolved from the start of stirring in all cases.

Claims

1. A (meth)acrylate (A) having a urethane bond and two or more (meth)acryloyl groups, or a monomer composition (1) containing the (meth)acrylate (A), and a (meth)acrylate (B) other than the (meth)acrylate (A), or a monomer composition (2) containing the (meth)acrylate (B), are mixed in a state where the viscosity of the (meth)acrylate (A) or the monomer composition (1) is 3,000 mPa·s or less to produce a monomer composition (3), including step (1). In step (1), the viscosity of the (meth)acrylate (A) or the monomer composition (1) at 80°C is 100 mPa·s or more, and the viscosity of the (meth)acrylate (B) or the monomer composition (2) at 80°C is lower than that of the (meth)acrylate (A) or the monomer composition (1). A method for producing a monomer composition.

2. The method for producing a monomer composition according to claim 1, wherein the (meth)acrylate (A) is a compound represented by the following formula (A1). 【Chemical 1】 (In formula (A1), R １Ａ and R ２Ａ each independently represents a divalent hydrocarbon group which may have a substituent having 2 to 20 carbon atoms, R ３Ａ represents a divalent hydrocarbon group having 5 to 16 carbon atoms, R ４Ａ and R ５Ａ each independently represents a hydrogen atom or a methyl group.)

3. In the compound represented by the formula (A1), the R １Ａ , R ２Ａ and R ３Ａ The method for producing a monomer composition according to claim 2, wherein at least one of them has a cyclic structure.

4. In the compound represented by the formula (A1), the R ３Ａ is a group represented by any one of the following formulas (a) to (e). The method for producing a monomer composition according to claim 2. 【Chemical 2】 [Chemical Formula 3] (In formulas (a) to (e), * indicates the bonding position.)

5. The method for producing a monomer composition according to claim 1, wherein the (meth)acrylate (B) does not contain a urethane bond in the molecule.

6. The method for producing a monomer composition according to claim 1, wherein the (meth)acrylate (B) is a compound represented by the following formula (B1) or the following formula (B2). 【Chemical Formula 4】 (In formula (B1), R １Ｂ１ represents a divalent organic group having 2 to 20 carbon atoms which may have an oxygen atom and does not have a urethane bond, R ２Ｂ１ and R ３Ｂ１ each independently represents a hydrogen atom or a methyl group.) 【Chemical Formula 5】 (In formula (B2), R １Ｂ２ represents a monovalent organic group having 2 to 20 carbon atoms, R ２Ｂ２ represents a hydrogen atom or a methyl group.)

7. The method for producing a monomer composition according to claim 1, including a synthesis step of synthesizing the (meth)acrylate (A) in a reactor before step (1).

8. In step (1), the monomer composition (1) is used, In step (1), the monomer composition (1) and the (meth)acrylate (B) or the monomer composition (2) are mixed in a state where the monomer composition (1) is accommodated in the reactor in the synthesis step. The method for producing a monomer composition according to claim 7.

9. A step of producing a monomer composition by the method for producing a monomer composition according to claim 1, and a step of mixing the monomer composition and a polymerization initiator to prepare a polymerizable composition. A method for producing a polymerizable composition.

10. A monomer composition comprising a (meth)acrylate (A) having a urethane bond and two or more (meth)acryloyl groups, and a (meth)acrylate (B) other than the (meth)acrylate (A). The (meth)acrylate (A) has a viscosity at 80°C of 100 mPa·s or more. The (meth)acrylate (B) has a viscosity at 80°C lower than that of the (meth)acrylate (A).

11. A polymerizable composition comprising the monomer composition according to claim 10 and a polymerization initiator.

12. The polymerizable composition according to claim 11, which is for dental materials.

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