Patent Description:
Conventionally, a denture base made of resin (referred to as "resin base") has been produced by a method in which a plaster mold adapted to an intraoral shape of a patient is first produced by a dental method, and then a curable resin is poured into the plaster mold, followed by curing the curable resin.

In recent years, a method has been proposed in which the intraoral shape of a patient is measured by a three-dimensional measurement and a denture base is produced based on the measured result, instead of the above described method utilizing a plaster mold, so as to reduce the number of hospital visits of patients and to allow for an efficient production of a denture base (see, for example, the following Patent Document <NUM>). Further, a method is disclosed in which a dental prosthesis is produced using a 3D printer (see, for example, the following Patent Document <NUM>).

<CIT> discloses dental compositions comprising (meth)acrylic monomer components which are difunctional aromatic acrylates or methacrylates and difunctional aliphatic acrylates or methacrylates.

<CIT> discloses three-dimensional articles made using a stereolithography process wherein the photo-curable composition comprises (meth)acrylate monomer components and a photopolymerization initiator.

One example of the method of producing a dental prosthesis, a medical device for intraoral use, or a tooth and/or jaw model (hereinafter, collectively referred to as "dental prosthesis or the like") using a 3D printer is a method referred to as "stereolithography", in which a dental prosthesis is produced by forming a photocurable composition into the shape of the dental prosthesis or the like, and then the resulting shaped product is subjected to photocuring.

In a case in which a dental prosthesis or the like (a denture base, in particular) is produced by stereolithography, it is required that the photocurable composition after being subjected to photocuring has an excellent flexural strength and flexural modulus, in view of practical use of the dental prosthesis or the like. Further, in this case, the photocurable composition after photocuring is also required to have an excellent Charpy impact strength, in view of durability of the dental prosthesis or the like.

An object of an embodiment according to the invention is to provide a photocurable composition which is used for the production by stereolithography of a dental prosthesis, a medical device for intraoral use, or a tooth and/or jaw model, and which has an excellent flexural strength, flexural modulus, and Charpy impact strength after being subjected to photocuring.

Another object of the embodiment according to the invention is to provide: a denture base which is produced using the above described photocurable composition, and which has an excellent flexural strength, flexural modulus, and Charpy impact strength; and a plate denture including the denture base.

The present inventors have found out, as a result of intensive studies, that a photocurable composition containing a combination of specific monomer species has an excellent flexural strength, flexural modulus, and Charpy impact strength after being subjected to photocuring, and that the photocurable composition is particularly suitable for the production by stereolithography of a dental prosthesis or the like (in other words, a dental prosthesis, a medical device for intraoral use, or a tooth and/or jaw model), thereby completing the present invention. In other words, specific means for solving the above described problems are as disclosed in the appended claims.

The embodiment according to the invention provides a photocurable composition which is used for the production by stereolithography of a dental prosthesis, a medical device for intraoral use, or a tooth and/or jaw model, and which has an excellent flexural strength, flexural modulus, and Charpy impact strength, after being subjected to photocuring.

Further, the embodiment according to the invention provides: a denture base which is produced by stereolithography, using the above described photocurable composition, and which has an excellent flexural strength, flexural modulus, and Charpy impact strength; and a plate denture including the denture base.

An embodiment according to the invention (hereinafter, also referred to as "present embodiment") are now described. In the present specification, any numerical range indicated using an expression "from * to" represents a range in which numerical values described before and after the "to" are included in the range as a lower limit value and an upper limit value. In the present specification, the term "ether bond" refers to a bond (a bond represented by -O-) in which two hydrocarbon groups are bound via an oxygen atom, as is commonly defined. Accordingly, "-O-" in an ester bond (-C(=O)-O-) is not included in the definition of the "ether bond". Further, in the present specification, the term "(meth)acrylate" refers to an acrylate or a methacrylate, and the term "(meth)acryloyloxy group" refers to an acryloyloxy group or a methacryloyloxy group.

The photocurable composition according to the present embodiment is according to appended claim <NUM>.

The photocurable composition according to the present embodiment has an excellent flexural strength, flexural modulus, and Charpy impact strength, after being subjected to photocuring, by including a combination of: the acrylic monomer (X); and at least one selected from the group consisting of the (meth)acrylic monomer (A), the (meth)acrylic monomer (B), and the (meth)acrylic monomer (C) (hereinafter, also referred to as "at least one of the (meth)acrylic monomers (A) to (C)").

Accordingly, a dental prosthesis or the like (a denture base, in particular) which is produced by stereolithography, using the photocurable composition according to the present embodiment, also has an excellent flexural strength, flexural modulus, and Charpy impact strength.

Further, the photocurable composition according to the present embodiment has a viscosity suitable for the production by stereolithography of a dental prosthesis or the like.

In the present embodiment, the "(meth)acrylic monomer component" refers to entire (meth)acrylic monomers included in the photocurable composition according to the present embodiment.

The "(meth)acrylic monomer component" includes, at least: the acrylic monomer (X); and at least one of the (meth)acrylic monomers (A) to (C).

The "(meth)acrylic monomer component" may include another (meth)acrylic monomer, other than the acrylic monomer (X) and the (meth)acrylic monomers (A) to (C), if necessary.

The photocurable composition according to the present embodiment encompasses the following first to third embodiments.

The first embodiment is an embodiment in which the (meth)acrylic monomer component in the present embodiment includes at least the acrylic monomer (X) and the (meth)acrylic monomer (A).

The second embodiment is an embodiment in which the (meth)acrylic monomer component in the present embodiment includes at least the acrylic monomer (X) and the (meth)acrylic monomer (B).

The third embodiment is an embodiment in which the (meth)acrylic monomer component in the present embodiment includes at least the acrylic monomer (X) and the (meth)acrylic monomer (C).

At least two of the scope of the first embodiment, the scope of the second embodiment, or the scope of the third embodiment may have some components in common. For example, an embodiment in which the (meth)acrylic monomer component includes the acrylic monomer (X), the (meth)acrylic monomer (A), the (meth)acrylic monomer (B), and the (meth)acrylic monomer (C) falls within the scope of any of the first to third embodiments.

In the photocurable composition according to the present embodiment (in other words, the first to third embodiments of the present embodiment; the same shall apply hereinafter), the Charpy impact strength after photocuring is improved due to incorporation of the acrylic monomer (X), as compared to the case in which a dimethacrylic monomer containing two aromatic rings and two methacryloyloxy groups within one molecule is included, instead of the acrylic monomer (X).

In the photocurable composition according to the present embodiment, the flexural strength and the flexural modulus after photocuring are improved due to the incorporation of the acrylic monomer (X), as compared to the case in which an acrylic monomer containing one aromatic ring and one acryloyloxy group within one molecule is included, instead of the acrylic monomer (X).

In the photocurable composition according to the present embodiment, the incorporation of the acrylic monomer (X) allows for inhibiting a phenomenon in which a crystallinity of the monomers is increased excessively, as compared to the case in which a diacrylic monomer containing one aromatic ring and two acryloyloxy groups within one molecule is included, instead of the acrylic monomer (X). As a result, the viscosity of the photocurable composition is reduced.

In the photocurable composition according to the present embodiment, the viscosity of the photocurable composition is reduced due to the incorporation of the acrylic monomer (X), as compared to the case in which an acrylic monomer containing three or more aromatic rings within one molecule is used, instead of the acrylic monomer (X).

In the photocurable composition according to the present embodiment, the Charpy impact strength after photocuring is improved due to the incorporation of the acrylic monomer (X), as compared to the case in which an acrylic monomer containing three or more acryloyloxy groups within one molecule is used, instead of the acrylic monomer (X).

Further, in the photocurable composition according to the present embodiment, the flexural strength and the flexural modulus after photocuring are improved due to the incorporation of the acrylic monomer (X), as compared to the case of using, instead of the acrylic monomer (X), an acrylic monomer which is at least one selected from diacrylic monomers containing two aromatic rings and two acryloyloxy groups within one molecule, and which has a weight average molecular weight of greater than <NUM>.

Note that the lower limit of the weight average molecular weight of the acrylic monomer (X), which is <NUM>, is a lower limit defined in view of ease of production or ease of availability of the monomer.

In addition, in the photocurable composition according to the present embodiment, the flexural strength and the flexural modulus after photocuring are further improved, due to the incorporation of at least one of the (meth)acrylic monomers (A) to (C), in addition to the acrylic monomer (X).

More specifically, the photocurable composition according to the first embodiment of the present embodiment is, as described above, a photocurable composition in which the (meth)acrylic monomer component includes at least the acrylic monomer (X) and the (meth)acrylic monomer (A).

As described above, the (meth)acrylic monomer (A) is a (meth)acrylic monomer which is at least one selected from di(meth)acrylic monomers not containing, within one molecule, an aromatic ring and containing, within one molecule, one or more ether bonds and two (meth)acryloyloxy groups, and which has a weight average molecular weight of from <NUM> to <NUM>.

According to the photocurable composition of the first embodiment, the flexural strength and the flexural modulus of the composition after photocuring are improved, as compared to those of a photocurable composition which includes, instead of the (meth)acrylic monomer (A) in the first embodiment, a (meth)acrylic monomer not containing an aromatic ring and containing one or more ether bonds and two (meth)acryloyloxy groups within one molecule, and having a weight average molecular weight of greater than <NUM>, and which composition does not fall within the scope of any of the first to third embodiments.

Note that the lower limit of the weight average molecular weight of the (meth)acrylic monomer (A), which is <NUM>, is a lower limit defined in view of the ease of production or ease of availability of the monomer.

The photocurable composition according to the second embodiment of the present embodiment is, as described above, a photocurable composition in which the (meth)acrylic monomer component includes at least the acrylic monomer (X) and the (meth)acrylic monomer (B). As described above, the (meth)acrylic monomer (B) is a (meth)acrylic monomer which is at least one selected from (meth)acrylic monomers not containing, within one molecule, an aromatic ring and containing, within one molecule, a ring structure other than an aromatic ring and one (meth)acryloyloxy group, and which has a weight average molecular weight of from <NUM> to <NUM>.

According to the photocurable composition of the second embodiment, the flexural strength and the flexural modulus of the composition after photocuring are improved, as compared to those of a photocurable composition which includes, instead of the (meth)acrylic monomer (B) in the second embodiment, a (meth)acrylic monomer containing a ring structure other than an aromatic ring and one (meth)acryloyloxy group within one molecule, and having a weight average molecular weight of greater than <NUM>, and which composition does not fall within the scope of any of the first to third embodiments.

Further, according to the photocurable composition of the second embodiment, the flexural strength and the flexural modulus of the composition after photocuring are improved, as compared to those of a photocurable composition which includes, instead of the (meth)acrylic monomer (B) in the second embodiment, a (meth)acrylic monomer containing no ring structure within one molecule, and which composition does not fall within the scope of any of the first to third embodiments.

Note that the lower limit of the weight average molecular weight of the (meth)acrylic monomer (B), which is <NUM>, is a lower limit defined in view of the ease of production or ease of availability of the monomer.

The photocurable composition according to the third embodiment of the present embodiment is, as described above, a photocurable composition in which the (meth)acrylic monomer component includes at least the acrylic monomer (X) and the (meth)acrylic monomer (C).

As described above, the (meth)acrylic monomer (C) is a (meth)acrylic monomer which is at least one selected from di(meth)acrylic monomers not containing, within one molecule, an aromatic ring nor ether bond and containing, within one molecule, a hydrocarbon skeleton and two (meth)acryloyloxy groups, and which has a weight average molecular weight of from <NUM> to <NUM>.

According to the photocurable composition of the third embodiment, the flexural strength and the flexural modulus of the composition after photocuring are improved, as compared to those of a photocurable composition which includes, instead of the (meth)acrylic monomer (C) in the third embodiment, a (meth)acrylic monomer not containing, within one molecule, an aromatic ring nor ether bond and containing, within one molecule, a hydrocarbon skeleton and two (meth)acryloyloxy groups, and having a weight average molecular weight of greater than <NUM>, and which composition does not fall within the scope of any of the first to third embodiments.

Note that the lower limit of the weight average molecular weight of the (meth)acrylic monomer (C), which is <NUM>, is a lower limit defined in view of the ease of production or ease of availability of the monomer.

The photocurable composition according to the present embodiment preferably satisfies the following flexural strength and the following flexural modulus, after being subjected to photocuring, in terms of the practical use of the resulting dental prosthesis or the like (the resulting denture base, in particular).

In other words, the photocurable composition according to the present embodiment preferably satisfies a flexural strength, as measured below, of <NUM> MPa or more, and more preferably, <NUM> MPa or more. Specifically, the measurement of the flexural strength is carried out as follows. The photocurable composition is formed into a shaped product having a size of <NUM> × <NUM> × <NUM> thickness, and the resulting formed product is subjected to UV light irradiation at <NUM> J/cm<NUM> to carry out photocuring, thereby obtaining a stereolithographed product (namely, a cured product; the same shall apply hereinafter). The resulting stereolithographed product is stored in a constant temperature water bath controlled at <NUM> ± <NUM> for <NUM> ± <NUM> hours, and the flexural strength of the stereolithographed product after storage is measured in accordance with ISO <NUM>-<NUM>: <NUM> (or JIS T <NUM>: <NUM>).

Further, the photocurable composition according to the present embodiment preferably satisfies a flexural modulus, as measured below, of <NUM>,<NUM> MPa or more, and more preferably, <NUM>,<NUM> MPa or more. Specifically, the measurement of the flexural modulus is carried out as follows. The photocurable composition is formed into a shaped product having a size of <NUM> × <NUM> × <NUM> thickness, and the resulting shaped product is subjected to UV light irradiation at <NUM> J/cm<NUM> to carry out photocuring, thereby obtaining a stereolithographed product. The resulting stereolithographed product is stored in a constant temperature water bath controlled at <NUM> ± <NUM> for <NUM> ± <NUM> hours, and the flexural modulus of the stereolithographed product after storage is measured in accordance with ISO <NUM>-<NUM>: <NUM> (or JIS T <NUM>: <NUM>).

In addition, the photocurable composition according to the present embodiment preferably satisfies the following Charpy impact strength, in terms of the durability of the resulting dental prosthesis or the like (the resulting denture base, in particular).

In other words, the photocurable composition according to the present embodiment preferably satisfies a Charpy impact strength, as measured below, of <NUM> kJ/m<NUM> or more. Specifically, the measurement of the Charpy impact strength is carried out as follows. The photocurable composition is formed into a shaped product having a size of <NUM> × <NUM> × <NUM> thickness, and the resulting formed product is subjected to UV light irradiation at <NUM> J/cm<NUM> to carry out photocuring, thereby obtaining a stereolithographed product. The resulting stereolithographed product is stored in a constant temperature water bath controlled at <NUM> ± <NUM> for <NUM> ± <NUM> hours. Then, a notch in the shape of a letter A and having a depth of <NUM> is provided at the central portion in a longitudinal direction of the stereolithographed product after storage, to obtain a test specimen with a single-notch. The Charpy impact strength of the resulting test specimen with a single-notch is measured in accordance with ISO <NUM>-<NUM>: <NUM> (or JIS K <NUM>-<NUM>: <NUM>), and under conditions of a hammer energy of <NUM> J, a swing angle of <NUM> degrees, a test temperature of <NUM>, and edgewise impact.

The photocurable composition according to the present embodiment is used for the production by stereolithography of a dental prosthesis or the like (namely, a dental prosthesis, a medical device for intraoral use, or a tooth and/or jaw model).

In the present embodiment, the dental prosthesis may be, for example, a denture base, a denture, an inlay, a crown, a bridge, a temporary crown, or a temporary bridge. Among these, a denture base is preferred.

Further, in the present embodiment, the medical device for intraoral use may be, for example, an orthodontic appliance (such as a mouthpiece, or an orthodontic appliance), a bite splint, a tray for obtaining an impression, or a guide for use in surgery. Among these, an orthodontic appliance is preferred, and a mouthpiece is more preferred.

The dental prosthesis or the like (namely, a dental prosthesis, medical device for intraoral use, or a tooth and/or jaw model) is preferably a dental prosthesis or an orthodontic appliance, more preferably a denture base or a mouthpiece, and particularly preferably a denture base.

In the present embodiment, the term "stereolithography" refers to one of the three-dimensional shaping methods utilizing a 3D printer.

Examples of stereolithography methods include an SLA (Stereo Lithography Apparatus) method, a DLP (Digital Light Processing) method, and an ink-jet method.

The photocurable composition according to the present embodiment is particularly suitable for a SLA or a DLP stereolithography method.

Examples of the SLA method include a method in which a spot-shaped UV laser beam is irradiated to a photocurable composition to obtain a three-dimensional shaped product.

In a case in which a dental prosthesis or the like is produced by the SLA method, the production thereof may be carried out, for example, as follows. Specifically, the photocurable composition according to the present embodiment is pooled in a container, and a spot-like UV laser beam is selectively irradiated to a liquid surface of the photocurable composition so as to obtain a desired pattern. In this manner, the photocurable composition is cured to form a cured layer having a desired thickness on a shaping table. Subsequently, the shaping table is lowered, so that the photocurable composition in a liquid state is supplied over the cured layer, in an amount sufficient for forming one layer, and the curing is carried out in the same manner as described above. This operation is repeated to obtain cured layers disposed one on another in layers. In this manner, a dental prosthesis or the like can be produced.

Examples of the DLP method include a method in which planar light is irradiated to a photocurable composition to obtain a three-dimensional shaped product.

As to the method of obtaining a three-dimensional shaped product by the DLP method, for example, the description in <CIT> and <CIT> can be referred to, if appropriate.

In a case in which a dental prosthesis or the like is produced by the DLP method, the production thereof may be carried out, for example, as follows. Specifically, a lamp which emits light other than a laser beam, such as a high pressure mercury lamp, an ultra-high pressure mercury lamp, or a low pressure mercury lamp, or alternatively, an LED is used as a light source. A planar drawing mask in which a plurality of digital micro mirror shutters are disposed planarly, is disposed between the light source and the surface of the photocurable composition to be shaped. Then light is irradiated to the surface of the photocurable composition to be shaped through the planar drawing mask, to form a cured layer having a predetermined pattern shape. This operation is repeated so that cured layers are formed and layered one on another, sequentially. In this manner, a dental prosthesis or the like can be produced.

Examples of the ink-jet method include a method in which droplets of a photocurable composition is continuously discharged onto a substrate through an ink-jet nozzle, and then light is irradiated to the droplets adhered to the substrate to obtain a three-dimensional shaped product.

In a case in which a dental prosthesis or the like is produced by an ink-jet method, the production thereof may be carried out, for example, as follows. Specifically, while scanning a plane with a head including an ink-jet nozzle and a light source, the photocurable composition is discharged onto a substrate through the ink-jet nozzle. At the same time, light is irradiated to the discharged photocurable composition to form a cured layer. This operation is repeated so that cured layers are formed and layered one on another, sequentially. In this manner, a dental prosthesis or the like can be produced.

The photocurable composition according to the present embodiment preferably has a viscosity at <NUM> and at <NUM> rpm, as measured using a Type E viscometer, of from <NUM> mPa·s to <NUM>,<NUM> mPa·s, in terms of suitability for the production by stereolithography of a dental prosthesis or the like. The lower limit of the viscosity is more preferably <NUM> mPa·s. The upper limit of the viscosity is more preferably <NUM>,<NUM> mPa·s, and still more preferably <NUM> mPa·s.

The viscosity at <NUM> and at <NUM> rpm of the photocurable composition according to the present embodiment may be adjusted depending on the method of the stereolithography to be used.

In a case in which a dental prosthesis or the like is produced by the SLA method, for example, the viscosity of the photocurable composition is preferably from <NUM> mPa·s to <NUM> mPa·s, and more preferably from <NUM> mPa·s to <NUM> mPa·s.

In a case in which a dental prosthesis or the like is produced by the DLP method, for example, the viscosity of the photocurable composition is preferably from <NUM> mPa·s to <NUM> mPa·s, and more preferably from <NUM> mPa·s to <NUM> mPa·s.

In a case in which a dental prosthesis or the like is produced by the ink-jet method, for example, the viscosity of the photocurable composition is preferably from <NUM> mPa·s to <NUM> mPa·s, and more preferably from <NUM> mPa·s to <NUM> mPa·s.

Components of the photocurable composition according to the present embodiment (namely, the first to third embodiments) will now be described.

The (meth)acrylic monomer component in the present embodiment includes the acrylic monomer (X) which is at least one selected from diacrylic monomers containing, within one molecule, two aromatic rings and two acryloyloxy groups, and which has a weight average molecular weight of from <NUM> to <NUM>.

The acrylic monomer (X) may consist of one type of diacrylic monomer containing, within one molecule, two aromatic rings and two acryloyloxy groups, or may be a mixture composed of two or more types of the diacrylic monomers.

It is preferable that at least one of the diacrylic monomers constituting the acrylic monomer (X) contains an ether bond within one molecule, in terms of further improving the Charpy impact strength after photocuring. Specifically, when at least one of the diacrylic monomers constituting the acrylic monomer (X) contains an ether bond within one molecule, the degree of freedom of molecular motion is increased to impart flexibility to the cured product after photocuring, thereby improving its toughness. As a result, the Charpy impact strength of the cured product (namely, the Charpy impact strength of the photocurable composition after photocuring) is improved.

It is more preferable that at least one of the diacrylic monomers contains from one to four ether bonds within one molecule.

When the number of ether bonds within one molecule, in at least one of the diacrylic monomers, is four or less, the flexural strength and the flexural modulus after photocuring are further improved.

The number of ether bonds within one molecule is still more preferably from two to four, and particularly preferably from two to three, in terms of further improving the flexural strength and the flexural modulus after photocuring.

It is still more preferable that at least one of the diacrylic monomers is a compound represented by the following Formula (x-<NUM>), in terms of reducing the viscosity of the photocurable composition, and further improving the Charpy impact strength, the flexural strength, and the flexural modulus, after photocuring.

In Formula (x-<NUM>), each of R1x and R2x independently represents a hydrogen atom or a methyl group; each of R3x and R4x independently represents a straight chain or branched chain alkylene group having from <NUM> to <NUM> carbon atoms; and each of mx and nx independently represents a number from <NUM> to <NUM>, with the proviso that mx and nx satisfy the relation: <NUM> ≤ (mx + nx) ≤ <NUM>.

In a case in which a plurality of R3xs are present in the compound represented by Formula (x-<NUM>), the plurality of R3xs may be the same as or different from each other. The same applies for R4x.

In Formula (x-<NUM>), each of R1x and R2x is preferably a methyl group.

Further, it is preferable that each of R3x and R4x independently represents an ethylene group, a trimethylene group, a tetramethylene group, a <NUM>-methylethylene group, a <NUM>-ethylethylene group or a <NUM>-methyltrimethylene group, and more preferably, an ethylene group or a <NUM>-methylethylene group.

In addition, it is preferable that both of R3x and R4x are ethylene groups, trimethylene groups, tetramethylene groups, <NUM>-methylethylene groups, or <NUM>-methyltrimethylene groups, and more preferably both are ethylene groups or <NUM>-methylethylene groups.

Although mx + nx is from <NUM> to <NUM>, it is particularly preferable that mx + nx is from <NUM> to <NUM>, in terms of further improving the flexural strength and the flexural modulus after photocuring.

It is still more preferable that at least one of the diacrylic monomers constituting the acrylic monomer (X) is a compound represented by the following Formula (x-<NUM>), in terms of reducing the viscosity of the photocurable composition, and further improving the Charpy impact strength, the flexural strength, and the flexural modulus, after photocuring.

In Formula (x-<NUM>), each of R5x, R6x, R7x, and R8x independently represents a hydrogen atom or a methyl group; and each of mx and nx independently represents a number from <NUM> to <NUM>, with the proviso that mx and nx satisfy the relation: <NUM> ≤ (mx + nx) ≤ <NUM>.

In a case in which a plurality of R5xs are present in the compound represented by Formula (x-<NUM>), the plurality of R5xs may be the same as or different from each other. The same applies for each of R6x, R7x, and R8x.

In Formula (x-<NUM>), it is preferable that one of R5x or R6x is a methyl group, and the other is a hydrogen atom. At the same time, it is preferable that one of R7x or R8x is a methyl group and the other is a hydrogen atom.

In Formula (x-<NUM>), it is particularly preferable that R5x and R8x are both methyl groups, and R6x and R7x are both hydrogen atoms.

Although mx + nx is from <NUM> to <NUM>, it is preferable that mx + nx is from <NUM> to <NUM>, in terms of further improving the flexural strength and the flexural modulus after photocuring.

Specific examples of the acrylic monomer (X) include: ethoxylated bisphenol A diacrylates (EO = <NUM> mol, <NUM> mol, <NUM> mol, <NUM> mol, and <NUM> mol), propoxylated bisphenol A diacrylates (PO = <NUM> mol, <NUM> mol, and <NUM> mol), and ethoxylated bisphenol F diacrylates (EO = <NUM> mol, <NUM> mol, <NUM> mol, <NUM> mol, and <NUM> mol).

In the photocurable composition according to the present embodiment, the content of the acrylic monomer (X) is preferably from <NUM> parts by mass to <NUM> parts by mass, more preferably from <NUM> parts by mass to <NUM> parts by mass, and still more preferably from <NUM> parts by mass to <NUM> parts by mass, with respect to <NUM>,<NUM> parts by mass of the total content of the (meth)acrylic monomer component.

The (meth)acrylic monomer component in the first embodiment of the present embodiment includes the (meth)acrylic monomer (A) which is at least one selected from di(meth)acrylic monomers not containing, within one molecule, an aromatic ring and containing, within one molecule, one or more ether bonds and two (meth)acryloyloxy groups, and which has a weight average molecular weight of from <NUM> to <NUM>.

The (meth)acrylic monomer (A) may be included in the (meth)acrylic monomer component in the second embodiment and the (meth)acrylic monomer component in the third embodiment.

The (meth)acrylic monomer (A) may consist of one type of di(meth)acrylic monomer not containing, within one molecule, an aromatic ring and containing, within one molecule, one or more ether bonds and two (meth)acryloyloxy groups, or may be a mixture composed of two or more types of the di(meth)acrylic monomers.

It is preferable that at least one of the di(meth)acrylic monomers constituting the (meth)acrylic monomer (A) contains one or two ether bonds within one molecule, in terms of further improving the Charpy impact strength after photocuring.

It is preferable that at least one of the di(meth)acrylic monomers constituting the (meth)acrylic monomer (A) is a compound represented by the following Formula (a-<NUM>), in terms of further improving the Charpy impact strength after photocuring.

In Formula (a-<NUM>), each of R1a and R2a independently represents a hydrogen atom or a methyl group; each of R3as independently represents a straight chain or branched chain alkylene group having from <NUM> to <NUM> carbon atoms; and p represents a number from <NUM> to <NUM>.

In Formula (a-<NUM>), a plurality of R3as may be the same as or different from each other. In Formula (a-<NUM>), p is preferably <NUM> or <NUM>.

In Formula (a-<NUM>), it is preferable that R1a and R2a are both hydrogen atoms or both methyl groups.

Further, it is preferable that each of R3as independently represents an ethylene group, a trimethylene group, a tetramethylene group, a <NUM>-methylethylene group, a <NUM>-ethylethylene group, a <NUM>-methyltrimethylene group, or a <NUM>,<NUM>-dimethyltrimethylene group, and more preferably an ethylene group, a <NUM>-methylethylene group or a <NUM>,<NUM>-dimethyltrimethylene group.

It is preferable that at least one of the di(meth)acrylic monomers constituting the (meth)acrylic monomer (A) is a compound represented by the following Formula (a-<NUM>).

In Formula (a-<NUM>), each of R1a, R2a, R4a, R5a, R6a and R7a independently represents a hydrogen atom or a methyl group; and each of p, q and r independently represents <NUM> or <NUM>, with the proviso that p, q and r satisfy the relation: p + q + r ≥ <NUM>.

In Formula (a-<NUM>), it is preferable that R1a and R2a are both hydrogen atoms or both methyl groups. It is preferable that R4a and R7a are both hydrogen atoms or both methyl groups, and R5a and R6a are both hydrogen atoms or both methyl groups.

Further, it is preferable that p and r are both <NUM>.

The (meth)acrylic monomer (A) has a weight average molecular weight of from <NUM> to <NUM>. The (meth)acrylic monomer (A) in the first embodiment preferably has a weight average molecular weight of from <NUM> to <NUM>.

In a case in which the (meth)acrylic monomer component in the second embodiment or the third embodiment includes the (meth)acrylic monomer (A), the (meth)acrylic monomer (A) in the second embodiment or the third embodiment preferably has a weight average molecular weight of from <NUM> to <NUM>, more preferably from <NUM> to <NUM>, and particularly preferably from <NUM> to <NUM>.

Examples of the (meth)acrylic monomer (A) include diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, and propoxylated neopentyl glycol di(meth)acrylate.

In the photocurable composition according to the present embodiment, the content of the (meth)acrylic monomer (A) is preferably from <NUM> parts by mass to <NUM> parts by mass, more preferably from <NUM> parts by mass to <NUM> parts by mass, and particularly preferably from <NUM> parts by mass to <NUM> parts by mass, with respect to <NUM>,<NUM> parts by mass of the total content of the (meth)acrylic monomer component.

In a case in which the (meth)acrylic monomer component in the first embodiment includes at least one of the (meth)acrylic monomer (B) or (meth)acrylic monomer (C), the content of the (meth)acrylic monomer (A) is preferably <NUM>% by mass or more, with respect to the total content of the (meth)acrylic monomer (A), (meth)acrylic monomer (B), and the (meth)acrylic monomer (C).

The (meth)acrylic monomer component in the second embodiment of the present embodiment includes the (meth)acrylic monomer (B) which is at least one selected from (meth)acrylic monomers not containing, within one molecule, an aromatic ring and containing, within one molecule, a ring structure other than an aromatic ring and one (meth)acryloyloxy group, and which has a weight average molecular weight of from <NUM> to <NUM>.

The (meth)acrylic monomer (B) may be included in each of the (meth)acrylic monomer component in the first embodiment or the (meth)acrylic monomer component in the third embodiment.

The (meth)acrylic monomer (B) may consist of one type of (meth)acrylic monomer containing a ring structure other than an aromatic ring and one (meth)acryloyloxy group within one molecule, or may be a mixture composed of two or more types of the (meth)acrylic monomers.

In the (meth)acrylic monomer (B), the ring structure other than an aromatic ring is preferably an alicyclic structure or a heterocyclic structure.

The ring structure other than an aromatic ring is more preferably a ring structure containing a dicyclopentenyl skeleton, a dicyclopentanyl skeleton, a cyclohexane skeleton, a tetrahydrofuran skeleton, a morpholine skeleton, an isobornyl skeleton, a norbornyl skeleton, a dioxolane skeleton, or a dioxane skeleton. The ring structure containing a skeleton as described above may be substituted by a substituent such as an alkyl group (for example, a methyl group, an ethyl group, a propyl group, or a butyl group), or the like.

In the (meth)acrylic monomer (B), the ring structure other than an aromatic ring is preferably a polycyclic structure, and more preferably a ring structure containing a dicyclopentenyl skeleton, a dicyclopentanyl skeleton, an isobornyl skeleton, or a norbornyl skeleton,in terms of further improving the flexural strength and the flexural modulus after photocuring.

Further, at least one of the (meth)acrylic monomers constituting the (meth)acrylic monomer (B) is preferably a compound which does not contain an imide structure, in terms of reducing water absorption.

At least one of the (meth)acrylic monomers constituting the (meth)acrylic monomer (B) is preferably a compound represented by the following Formula (b-<NUM>).

In Formula (b-<NUM>), R1b represents a hydrogen atom or a methyl group; R2b represents a single bond or a methylene group; and A<NUM> represents a ring structure other than an aromatic ring.

In Formula (b-<NUM>), preferred scope of the "ring structure other than an aromatic ring" represented by A<NUM> is as described above. In other words, it is more preferable that at least one of the (meth)acrylic monomers constituting the (meth)acrylic monomer (B) is a compound represented by the following Formula (b-<NUM>).

In Formula (b-<NUM>), R1b represents a hydrogen atom or a methyl group; R2b represents a single bond or a methylene group; and A<NUM> represents a ring structure containing a dicyclopentenyl skeleton, a dicyclopentanyl skeleton, a cyclohexane skeleton, a tetrahydrofuran skeleton, a morpholine skeleton, an isobornyl skeleton, a norbornyl skeleton, a dioxolane skeleton or a dioxane skeleton.

The (meth)acrylic monomer (B) has a weight average molecular weight of from <NUM> to <NUM>.

The (meth)acrylic monomer (B) in the second embodiment preferably has a weight average molecular weight of from <NUM> to <NUM>.

In a case in which the (meth)acrylic monomer component in the first embodiment or the third embodiment includes the (meth)acrylic monomer (B), the (meth)acrylic monomer (B) in the first embodiment or the third embodiment preferably has a weight average molecular weight of from <NUM> to <NUM>, and more preferably from <NUM> to <NUM>.

Examples of the (meth)acrylic monomer (B) include isobornyl (meth)acrylate, norbornyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentanyl (meth)acrylate, cyclohexyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, (meth)acryloylmorpholine, <NUM>-tert-butylcyclohexanol (meth)acrylate, cyclohexanedimethanol di(meth)acrylate, (<NUM>-methyl-<NUM>-ethyl-<NUM>,<NUM>-dioxolane-<NUM>-yl) methyl acrylate, and cyclic trimethylolpropane formal acrylate.

In the photocurable composition according to the present embodiment, the content of the (meth)acrylic monomer (B) is preferably from <NUM> parts by mass to <NUM> parts by mass, more preferably from <NUM> parts by mass to <NUM> parts by mass, and particularly preferably from <NUM> parts by mass to <NUM> parts by mass, with respect to <NUM>,<NUM> parts by mass of the total content of the (meth)acrylic monomer component.

Further, in a case in which the (meth)acrylic monomer component in the second embodiment includes at least one of the above described (meth)acrylic monomer (A) or the (meth)acrylic monomer (C), content of the (meth)acrylic monomer (B) is preferably <NUM>% by mass or more, with respect to the total content of the (meth)acrylic monomer (A), (meth)acrylic monomer (B), and the (meth)acrylic monomer (C).

The (meth)acrylic monomer component in the third embodiment of the present embodiment includes the (meth)acrylic monomer (C) which is at least one selected from di(meth)acrylic monomers not containing, within one molecule, an aromatic ring nor ether bond and containing, within one molecule, a hydrocarbon skeleton and two (meth)acryloyloxy groups, and which has a weight average molecular weight of from <NUM> to <NUM>.

The (meth)acrylic monomer (C) may be included in each of the (meth)acrylic monomer component in the first embodiment or the (meth)acrylic monomer component in the second embodiment.

The (meth)acrylic monomer (C) may consist of one type of di(meth)acrylic monomer not containing, within one molecule, an aromatic ring nor ether bond and containing, within one molecule, a hydrocarbon skeleton and two (meth)acryloyloxy groups, or may be a mixture composed of two or more types of the di(meth)acrylic monomers.

It is preferable that at least one of the di(meth)acrylic monomers constituting the (meth)acrylic monomer (C) is a compound represented by the following Formula (c-<NUM>), in terms of further improving the flexural strength and the flexural modulus after photocuring.

In Formula (c-<NUM>), each of R1c and R2c independently represents a hydrogen atom or a methyl group; and R3c represents an alkylene group having from <NUM> to <NUM> carbon atoms.

The alkylene group represented by R3c may be a straight chain alkylene group, or a branched chain alkylene group.

Further, it is more preferable that at least one of the di(meth)acrylic monomers constituting the (meth)acrylic monomer (C) is a compound represented by the following Formula (c-<NUM>), in terms of further improving the flexural strength and the flexural modulus after photocuring.

In Formula (c-<NUM>), each of R1c and R2c independently represents a hydrogen atom or a methyl group; each of R4c and R5c independently represents a hydrogen atom or a methyl group; and nc represents a number from <NUM> to <NUM>, with the proviso that an alkylene group represented by -(CR4cR5c)nc- has from <NUM> to <NUM> carbon atoms.

In a case in which a plurality of R4cs are present in the compound represented by Formula (c-<NUM>), the plurality of R4cs may be the same as or different from each other. The same applies for R5c.

Specific examples of the (meth)acrylic monomer (C) include <NUM>,<NUM>-butylene glycol diacrylate, neopentyl glycol diacrylate, <NUM>,<NUM>-butanediol diacrylate, <NUM>,<NUM>-butanediol dimethacrylate, <NUM>,<NUM>-hexandiol diacrylate, <NUM>,<NUM>-hexanediol dimethacrylate, <NUM>,<NUM>-nonanediol diacrylate, ethylene glycol dimethacrylate, and <NUM>,<NUM>-butylene glycol dimethacrylate.

In the photocurable composition according to the present embodiment, the content of the (meth)acrylic monomer (C) is preferably from <NUM> parts by mass to <NUM> parts by mass, more preferably from <NUM> parts by mass to <NUM> parts by mass, and particularly preferably from <NUM> parts by mass to <NUM> parts by mass, with respect to <NUM>,<NUM> parts by mass of the total content of the (meth)acrylic monomer component.

Further, in a case in which the (meth)acrylic monomer component in the third embodiment includes at least one of the above described (meth)acrylic monomer (A) or the (meth)acrylic monomer (B), the content of the (meth)acrylic monomer (C) is preferably <NUM>% by mass or more, with respect to the total content of the (meth)acrylic monomer (A), (meth)acrylic monomer (B), and the (meth)acrylic monomer (C).

The (meth)acrylic monomer component may include another (meth)acrylic monomer other than the acrylic monomer (X), the (meth)acrylic monomer (A), the (meth)acrylic monomer (B), and the (meth)acrylic monomer (C).

Note, however, that the total content of the acrylic monomer (X), the (meth)acrylic monomer (A), the (meth)acrylic monomer (B), and the (meth)acrylic monomer (C) in the (meth)acrylic monomer component is <NUM>% by mass or more, more preferably <NUM>% by mass or more, and still more preferably <NUM>% by mass or more, with respect to the total amount of the (meth)acrylic monomer component.

The photocurable composition according to the present embodiment includes a photopolymerization initiator.

The photopolymerization initiator is not particularly limited as long as the photopolymerization initiator is capable of generating radicals when light is irradiated thereto. However, the photopolymerization initiator is preferably one which generates radicals by light irradiation at a wavelength used in the stereolithography.

In general, the wavelength of the light used in the stereolithography may be, for example, from <NUM> to <NUM>. However, the wavelength is preferably from <NUM> to <NUM>, and more preferably from <NUM> to <NUM>, in the view point of practical use.

Examples of the photopolymerization initiator which generates radicals by light irradiation at the wavelength used in the stereolithography include: alkylphenone compounds, acylphosphine oxide compounds, titanocene compounds, oxime ester compounds, benzoin compounds, acetophenone compounds, benzophenone compounds, thioxanthone compounds, α-acyloxime ester compounds, phenylglyoxylate compounds, benzyl compounds, azo compounds, diphenylsulfide compounds, organic pigment compounds, iron-phthalocyanine compounds, benzoin ether compounds, and anthraquinone compounds.

Among these, an alkylphenone compound and an acylphosphine oxide compound are preferred, in terms of reactivity and the like.

Examples of the alkylphenone compound include <NUM>-hydroxy-cyclohexyl-phenyl-ketone (Irgacure <NUM>: manufactured by BASF Japan Ltd.

Examples of the acylphosphine oxide compound include bis(<NUM>,<NUM>,<NUM>-trimethylbenzoyl)-phenylphosphine oxide (Irgacure <NUM>: manufactured by BASF Japan Ltd. ), and <NUM>,<NUM>,<NUM>-trimethylbenzoyl-diphenyl-phosphine oxide (Irgacure TPO: manufactured by BASF Japan Ltd.

The photocurable composition according to the present embodiment may include only one type of the photopolymerization initiator, or two or more types of the photopolymerization initiators.

The content of the photopolymerization initiator (the total content, in a case in which two or more types thereof are included) in the photocurable composition according to the present embodiment is preferably from <NUM> part by mass to <NUM> parts by mass, more preferably from <NUM> parts by mass to <NUM> parts by mass, still more preferably from <NUM> parts by mass to <NUM> parts by mass, and particularly preferably from <NUM> parts by mass to <NUM> parts by mass, with respect to <NUM>,<NUM> parts by mass of the total content of the (meth)acrylic monomer component.

The photocurable composition according to the present embodiment may include at least one other component other than the above mentioned components, if necessary.

Note, however, that the total content of the (meth)acrylic monomer component and the photopolymerization initiator is from <NUM>% by mass or more, and still more preferably from <NUM>% by mass or more, with respect to the total amount of the photocurable composition.

Examples of the other components include coloring materials.

For example, in a case in which the photocurable composition according to the present embodiment is used for the production of a denture base, the photocurable composition may be colored to a color close to a gingival color by incorporating a coloring material, in terms of esthetics.

The coloring material is not limited as long as the coloring material does not interfere with the shaping of the photocurable composition by a 3D printer, and is less susceptible to discoloration. Examples thereof include pigments, dyes, and colorants. More specific examples of the coloring material include synthetic tar dyes, aluminum lakes of synthetic tar dyes, inorganic pigments, and natural pigments.

Further, examples of the other components also include other curable resins other than the above described (meth)acrylic monomer component (such as other curable monomers other than the above described (meth)acrylic monomer component).

In addition, examples of the other components also include thermal polymerization initiators.

In a case in which the photocurable composition according to the present embodiment includes a thermal polymerization initiator, it is possible to carry out both the photocuring and heat curing in combination. Examples of the thermal polymerization initiator include thermal radical generators and amine compounds.

Still further, examples of the other components include: coupling agents such as silane coupling agents (for example, <NUM>-acryloxypropyltrimethoxysilane); and additives such as rubber agents, ion-trapping agents, ion exchangers, leveling agents, plasticizers, and antifoaming agents.

The method of preparing the photocurable composition according to the present embodiment is not particularly limited. Examples thereof include a method in which the acrylic monomer (X), at least one of the (meth)acrylic monomers (A) to (C), and the photopolymerization initiator (and other component(s), if necessary) are mixed.

The means for mixing the respective components is not particularly limited. Examples thereof include: dissolution by ultrasonic wave; and mixing utilizing a twin arm mixer, a roll kneader, a twin-screw extruder, a ball mill kneader, or a planetary mixer.

The photocurable composition according to the present embodiment may be prepared by mixing the respective components, then filtering the resultant to remove impurities, and further subjecting the resultant to vacuum deaeration treatment.

A glass transition temperature (Tg) after photocuring of the photocurable composition according to the present embodiment is not particularly limited. However, the glass transition temperature (Tg) after photocuring is preferably <NUM> or higher, and more preferably <NUM> or higher, in terms of the flexural strength and the flexural modulus.

At the same time, the glass transition temperature (Tg) after photocuring is preferably <NUM> or lower, in terms of the Charpy impact strength.

The dental prosthesis or the like which is a cured product (namely, stereolithographed product) of the photocurable composition according to the present embodiment is particularly preferably a denture base. The denture base which is a cured product of the photocurable composition according to the present embodiment has an excellent flexural strength, flexural modulus and Charpy impact strength.

The denture base according to the present embodiment may be a denture base for use in a complete denture or a full denture, or alternatively, a denture base for use in a partial denture.

Further, the denture base according to the present embodiment may be a denture base for an upper jaw denture (hereinafter, also referred to as "upper jaw denture base"), or a denture base for a lower jaw denture (hereinafter, also referred to as "lower jaw denture base"), or alternatively, a set of an upper jaw denture base and a lower jaw denture base.

In addition, the denture base according to the present embodiment may be a denture base in which only a portion thereof is made of the photocurable composition according to the present embodiment, or a denture base entirely made of the photocurable composition according to the present embodiment.

Examples of the denture base in which only a portion thereof is made of the photocurable composition according to the present embodiment include: a denture base (a so-called metal base) which includes a metal portion and a resin portion, and in which at least one portion of the resin portion is made of the photocurable composition according to the present embodiment; and a denture base (a so-called resin base) which consists of a resin portion, and in which only a portion of the resin portion is made of the photocurable composition according to the present embodiment.

Examples of the denture base entirely made of the photocurable composition according to the present embodiment include a denture base consisting of a resin portion.

A plate denture according to the present embodiment includes the above described denture base according to the present embodiment and an artificial tooth fixed on the denture base.

The plate denture according to the present embodiment, the denture base has an excellent flexural strength, flexural modulus and Charpy impact strength.

The plate denture according to the present embodiment may be a partial denture or a complete denture. In other words, the number of the artificial teeth to be included in the plate denture according to the present embodiment is not particularly limited, as long as the plate denture includes one artificial tooth.

Further, the plate denture according to the present embodiment may be an upper jaw denture, or a lower jaw denture, or alternatively, a set of an upper jaw denture and a lower jaw denture.

Examples of materials for the artificial tooth include an acrylic resin.

Further, the artificial tooth may contain a filler and/or the like, in addition to the acrylic resin.

The present invention is now described more specifically, with reference to Examples. However, the invention is in no way limited to these Examples.

Examples (Examples 1A to 26A) and Comparative Examples (Comparative Examples 1A to 11A) of the first embodiment are described below.

The components shown in the following Tables <NUM> to <NUM> were mixed to obtain photocurable compositions of Examples and Comparative Examples.

The following measurements and evaluations were performed, using each of the resulting photocurable compositions. The results are shown in Tables <NUM> to <NUM>.

The viscosity of each of the photocurable compositions was measured by a Type E viscometer, under conditions of <NUM> and <NUM> rpm.

Each of the resulting photocurable compositions was formed into a size of <NUM> × <NUM> × <NUM> thickness using a 3D printer (MASTERr PLUS S <NUM>; manufactured by Carima Co. ), to obtain a formed product. The resulting formed product was subjected to irradiation of UV light having a wavelength of <NUM>, at <NUM> J/cm<NUM>, to carry out main curing, thereby obtaining a stereolithographed product.

The resulting stereolithographed product (hereinafter, referred to as "test specimen") was stored in a constant temperature water bath maintained at <NUM> ± <NUM> for <NUM> ± <NUM> hours. Then, the test specimen was retrieved from the constant temperature water bath, and the flexural strength and the flexural modulus of the retrieved test specimen were each measured in accordance with ISO <NUM>-<NUM>: <NUM>. These measurements were carried out using a tensile test apparatus (manufactured by INTESCO Co. ), at a speed of <NUM> ± <NUM> /min.

In a case in which each of the above obtained photocurable compositions is used in the production of a dental prosthesis or the like (a denture base, in particular), each stereolithographed product preferably has a flexural strength of <NUM> MPa or more, and more preferably <NUM> MPa.

Further, in this case, each photocurable composition preferably has a flexural modulus of <NUM>,<NUM> MPa or more, and more preferably <NUM>,<NUM> MPa or more.

Each of the resulting photocurable compositions was formed into a size of <NUM> × <NUM> × <NUM> thickness using a 3D printer (MASTER PLUS S2011; manufactured by Carima Co. ), to obtain a formed product. The resulting formed product was subjected to irradiation of UV light having a wavelength of <NUM>, at <NUM> J/cm<NUM>, to carry out main curing of the formed product, thereby obtaining a stereolithographed product.

The resulting stereolithographed product (hereinafter, referred to as "test specimen") was stored in a constant temperature water bath maintained at <NUM> ± <NUM> for <NUM> ± <NUM> hours.

Subsequently, the test specimen was retrieved from the constant temperature water bath, and a notch in the shape of the letter A and having a depth of <NUM> was provided at the central portion in the longitudinal direction of the retrieved test specimen, to obtain a test specimen with a single-notch. The Charpy impact strength of the resulting test specimen with a single-notch was measured in accordance with ISO <NUM>-<NUM>: <NUM> (or JIS K <NUM>-<NUM>: <NUM>). The above measurement of the Charpy impact strength was carried out under conditions of a hammer energy of <NUM> J, a swing angle of <NUM> degrees, a test temperature of <NUM>, and edgewise impact.

In a case in which each of the above obtained photocurable compositions is used in the production of a dental prosthesis or the like (a denture base, in particular), each stereolithographed product preferably has a Charpy impact strength of <NUM> kJ/m<NUM> or more, in a view of durability.

In Tables <NUM> to <NUM>, each of the amounts (numbers) of the components in each of the Examples and Comparative Examples is shown in "parts by mass";.

The same applies for Tables <NUM> to <NUM> to be described later.

The respective structures of the acrylic monomers (X) listed in Tables <NUM> to <NUM> are as shown below.

In Tables <NUM> to <NUM>, A-BPE-<NUM>, A-BPE-<NUM>, ABE-<NUM>, A-BPE-<NUM>, and A-BPP-<NUM> are acrylic monomers manufactured by Shin Nakamura Chemical Co. ; BP-4PA is an acrylic monomer manufactured by Kyoeisha Chemical Co. ; and M-<NUM> is an acrylic monomer manufactured by TOAGOSEI CO. The same applies for Tables <NUM> to <NUM> to be described later. <CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>.

The respective structures of (meth)acrylic monomers (A) listed in Tables <NUM> to <NUM> are as shown below.

In Tables <NUM> to <NUM>, 2EG is a methacrylic monomer manufactured by Kyoeisha Chemical Co. ; 3PG is a methacrylic monomer manufactured by Shin Nakamura Chemical Co. ; FA-222A is an acrylic monomer manufactured by Hitachi Chemical Co. ; 3EG-A is an acrylic monomer manufactured by Kyoeisha Chemical Co. ; APG-<NUM> and APG-<NUM> are acrylic monomers manufactured by Shin Nakamura Chemical Co. ; and SR <NUM> is an acrylic monomer manufactured by Arkema Inc. <CHM>
<CHM>
<CHM>
<CHM>.

In Tables <NUM> to <NUM>, IB-XA, which is (meth)acrylic monomer (B), is an acrylic monomer manufactured by Kyoeisha Chemical Co. ; and FA-124AS, which is (meth)acrylic monomer (C), is an acrylic monomer manufactured by Hitachi Chemical Co. The structures of these monomers are as shown below.

The structures of the other monomers listed in Table <NUM> are as shown below.

In Table <NUM>, A-BPE-<NUM>, A-BPE-<NUM>, APG-<NUM>, and 9PG are acrylic monomers manufactured by Shin Nakamura Chemical Co. ; FA-240A and FA-PTG9A are acrylic monomers manufactured by Hitachi Chemical Co. ; CD <NUM> is an acrylic monomer manufactured by Arkema Inc. ; and BP-2EM is a methacrylic monomer manufactured by Kyoeisha Chemical Co. <CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>.

In Tables <NUM> to <NUM>, the term "Initiator" denotes photopolymerization initiators.

Of the initiators (namely, the photopolymerization initiators) listed in Tables <NUM> to <NUM>, Irg <NUM> is "Irgacure <NUM>" (an acylphosphine oxide compound) manufactured by BASF Japan Ltd. ; Irg <NUM> is "Irgacure <NUM>" (an alkylphenone compound) manufactured by BASF Japan Ltd. ; and TPO is "Irgacure TPO" (an acylphosphine oxide compound) manufactured by BASF Japan Ltd. The respective structures of these photopolymerization initiators are as shown below.

As shown in Tables <NUM> to <NUM>, in each of Examples 1A to 26A, a photocurable composition was used which includes: the acrylic monomer (X) which is a diacrylic monomer containing two aromatic rings and two acryloyloxy groups within one molecule, and having a weight average molecular weight of from <NUM> to <NUM>; the (meth)acrylic monomer (A) which is a di(meth)acrylic monomer not containing, within one molecule, an aromatic ring and containing, within one molecule, one or more ether bonds and two (meth)acryloyloxy groups, and having a weight average molecular weight of from <NUM> to <NUM>; and the photopolymerization initiator(s). As a result, it was possible to obtain a stereolithographed product which satisfies all of: a flexural strength of <NUM> MPa or more, a flexural modulus of <NUM>,<NUM> MPa or more, and a Charpy impact strength of <NUM> kJ/m<NUM> or more, in each of Examples 1A to 26A. Further, the photocurable compositions of Examples 1A to 26A had a viscosity suitable for stereolithography.

The above results confirmed that each of the photocurable compositions of Examples 1A to 26A is suitable for the production by stereolithography of a dental prosthesis or the like (a denture base, in particular).

In contrast to Examples 1A to 26A, in Comparative Examples 1A and 2A, in each of which a diacrylic monomer (A-BPE-<NUM> or A-BPE-<NUM>) containing two aromatic rings and two acryloyloxy groups within one molecule and having a weight average molecular weight of greater than <NUM> was used instead of the acrylic monomer (X), the resulting stereolithographed products had an insufficient flexural strength and flexural modulus.

In Comparative Examples 3A to 5A, in each of which BP-2EM, which is a methacrylic monomer, not an acrylic monomer, containing two aromatic rings and two acryloyloxy groups within one molecule and having a weight average molecular weight of from <NUM> to <NUM> was used instead of the acrylic monomer (X), the resulting stereolithographed products had an insufficient Charpy impact strength.

In Comparative Examples 6A to 9A and 11A, in each of which a di(meth)acrylic monomer (FA-240A, APG-<NUM>, CD <NUM>, FA-PTG9A, or 9PG) not containing, within one molecule, an aromatic ring and containing, within one molecule, one or more ether bonds and two (meth)acryloyloxy groups, and having a weight average molecular weight of greater than <NUM>, was used instead of the (meth)acrylic monomer (A), the resulting stereolithographed products had an insufficient flexural strength and flexural modulus.

Further, in Comparative Example 10A in which a di(meth)acrylic monomer (DMGDA) not containing, within one molecule, an aromatic ring and containing, within one molecule, one or more ether bonds and two (meth)acryloyloxy groups, and having a weight average molecular weight of less than <NUM>, was used instead of the (meth)acrylic monomer (A), the resulting stereolithographed product had an insufficient Charpy impact strength.

Examples (Examples 1B to 26B) and Comparative Examples (Comparative Examples 1B to 12B) of the second embodiment are described below.

Using each of the resulting photocurable compositions, the following measurements and evaluations were performed, in the same manner as described in Example 1A. The results are shown in Tables <NUM> to <NUM>.

In Tables <NUM> to <NUM>, each of the acrylic monomers (X) is the same as that described in the "Description of Tables <NUM> to <NUM>" above.

Of the (meth)acrylic monomers (B) listed in Tables <NUM> to <NUM>, FA-<NUM> AS and FA-<NUM> AS are acrylic monomers manufactured by Hitachi Chemical Co. ; CHA and THFA are acrylic monomers manufactured by Osaka Organic Chemical Industry Ltd. ; SR217 is an acrylic monomer manufactured by Arkema Inc. ; and ACMO is an acrylic monomer manufactured by KJ Chemicals Corporation. The structures of these monomers are as shown below.

Of the (meth)acrylic monomers (B) listed in Tables <NUM> to <NUM>, IB-XA is the same as that described in the "Description of Tables <NUM> to <NUM>" above. <CHM>
<CHM>.

In Tables <NUM> to <NUM>, each of FA-222A, which is the (meth)acrylic monomer (A), and FA-<NUM> AS, which is the (meth)acrylic monomer (C), is the same as that described in the "Description of Tables <NUM> to <NUM>" above.

Of the other (meth)acrylic monomers listed in Tables <NUM> to <NUM>, each of A-BPE-<NUM>, A-BPE-<NUM>, and BP-2EM is the same as that described in the "Description of Tables <NUM> to <NUM>" above.

The rest of the other (meth)acrylic monomers listed in Tables <NUM> to <NUM>, other than those described above, have the structures as shown below.

SR611 is an acrylic monomer manufactured by Arkema Inc. ; M-<NUM> is an acrylic monomer manufactured by Toagosei Co. ; and AIB, NOAA and LA are acrylic monomers manufactured by Osaka Organic Chemical Industry Ltd. <CHM>
<CHM>
<CHM>.

Each of the initiators (namely, the photopolymerization initiators) listed in Tables <NUM> to <NUM> is the same as that described in the "Description of Tables <NUM> to <NUM>" above.

As shown in Tables <NUM> to <NUM>, in each of Examples 1B to 26B, a photocurable composition was used which includes: the acrylic monomer (X) which is a diacrylic monomer containing two aromatic rings and two acryloyloxy groups within one molecule, and having a weight average molecular weight of from <NUM> to <NUM>; the (meth)acrylic monomer (B) which is a (meth)acrylic monomer containing a ring structure other than an aromatic ring and one (meth)acryloyloxy group within one molecule, and having a weight average molecular weight of from <NUM> to <NUM>; and the photopolymerization initiator(s). As a result, it was possible to obtain a stereolithographed product which satisfies all of: a flexural strength of <NUM> MPa or more, a flexural modulus of <NUM>,<NUM> MPa or more, and a Charpy impact strength of <NUM> kJ/m<NUM> or more, in each of Examples 1B to 26B. Further, the photocurable compositions of Examples 1B to 26B had a viscosity suitable for stereolithography.

The above results confirmed that each of the photocurable compositions of Examples 1B to 26B is suitable for the production by stereolithography of a dental prosthesis or the like (a denture base, in particular).

In contrast to Examples 1B to 26B, in Comparative Examples 1B and 2B, in each of which a diacrylic monomer (A-BPE-<NUM> or A-BPE-<NUM>) containing two aromatic rings and two acryloyloxy groups within one molecule and having a weight average molecular weight of greater than <NUM> was used instead of the acrylic monomer (X), the resulting stereolithographed products had an insufficient flexural strength and flexural modulus.

In Comparative Examples 3B to 5B, in each of which BP-2EM, which is a methacrylic monomer, not an acrylic monomer, containing two aromatic rings and two acryloyloxy groups within one molecule and having a weight average molecular weight of from <NUM> to <NUM>, was used instead of the acrylic monomer (X), the resulting stereolithographed products had an insufficient Charpy impact strength.

In Comparative Examples 6B and 7B, in each of which a (meth)acrylic monomer (SR611 or M-<NUM>) containing a ring structure other than an aromatic ring and one (meth)acryloyloxy group within one molecule, and having a weight average molecular weight of greater than <NUM>, was used instead of the (meth)acrylic monomer (B), the resulting stereolithographed products had an insufficient flexural strength and flexural modulus.

In Comparative Examples 8B to 10B, in each of which a (meth)acrylic monomer (AIB, NOAA or LA) not containing a ring structure within one molecule was used instead of the (meth)acrylic monomer (B), the resulting stereolithographed products also had an insufficient flexural strength and flexural modulus.

Further, in Comparative Examples 11B and 12B, in each of which a (meth)acrylic monomer (CPA or CBA) containing a ring structure other than an aromatic ring and one (meth)acryloyloxy group within one molecule, and having a weight average molecular weight of less than <NUM>, was used instead of the (meth)acrylic monomer (B), the resulting stereolithographed products had an insufficient Charpy impact strength.

Examples (Examples 1C to 26C) and Comparative Examples (Comparative Examples 1C to 9C) of the third embodiment are described below.

The respective structures of the (meth)acrylic monomers (C) listed in Tables <NUM> to <NUM> are as shown below.

EG, BG and NP-A are methacrylic monomers manufactured by Kyoeisha Chemical Co. ; SR212 is an acrylic monomer manufactured by Arkema Inc. ; FA-124AS is an acrylic monomer manufactured by Hitachi Chemical Co. ; and <NUM>,6HX-A and <NUM>,9ND-A are acrylic monomers manufactured by Kyoeisha Chemical Co. <CHM>
<CHM>
<CHM>
<CHM>.

In Tables <NUM> to <NUM>, each of FA-222A, which is the (meth)acrylic monomer (A), and IB-XA, which is the (meth)acrylic monomer (B), has the same structure as that described in the "Description of Tables <NUM> to <NUM>" above.

The rest of the (meth)acrylic monomers listed in Tables <NUM> to <NUM>, other than those described above, have the structure as shown below.

<NUM>,10DD and <NUM>,10DDMA are "A-DOD-N", which is an acrylic monomer manufactured by Shin Nakamura Chemical Co. , Ltd, and "DOD-N", which is a methacrylic monomer manufactured by Shin Nakamura Chemical Co. , respectively. <CHM>
<CHM>
<CHM>
<CHM>.

As shown in Tables <NUM> to <NUM>, in each of Examples 1C to 26C, a photocurable composition was used which includes: the acrylic monomer (X) which is a diacrylic monomer containing two aromatic rings and two acryloyloxy groups within one molecule, and having a weight average molecular weight of from <NUM> to <NUM>; the (meth)acrylic monomer (C) which is a di(meth)acrylic monomer not containing an aromatic ring and containing a hydrocarbon skeleton and two (meth)acryloyloxy groups within one molecule, and having a weight average molecular weight of from <NUM> to <NUM>; and the photopolymerization initiator. As a result, it was possible to obtain a stereolithographed product which satisfies all of: a flexural strength of <NUM> MPa or more, a flexural modulus of <NUM>,<NUM> MPa or more, and a Charpy impact strength of <NUM> kJ/m<NUM> or more, in each of Examples 1C to 26C. Further, the photocurable compositions of Examples 1C to 26C had a viscosity suitable for stereolithography.

The above results confirmed that each of the photocurable compositions of Examples 1C to 26C is suitable for the production by stereolithography of a dental prosthesis or the like (a denture base, in particular).

In contrast to Examples 1C to 26C, in Comparative Examples 1C and 2C, in each of which a diacrylic monomer (A-BPE-<NUM> or A-BPE-<NUM>) containing two aromatic rings and two acryloyloxy groups within one molecule and having a weight average molecular weight of greater than <NUM> was used instead of the acrylic monomer (X), the resulting stereolithographed products had an insufficient flexural strength and flexural modulus.

In Comparative Examples 3C to 5C, in each of which BP-2EM, which is a methacrylic monomer, not an acrylic monomer, containing two aromatic rings and two methacryloyloxy groups within one molecule and having a weight average molecular weight of from <NUM> to <NUM>, was used instead of the acrylic monomer (X), the resulting stereolithographed products had an insufficient Charpy impact strength.

In Comparative Examples 6C, 8C and 9C, in each of which a di(meth)acrylic monomer (<NUM>,10DD, <NUM>,12DDDA, or <NUM>,10DDMA) not containing an aromatic ring and containing a hydrocarbon skeleton and two (meth)acryloyloxy groups within one molecule, and having a weight average molecular weight of greater than <NUM>, was used instead of the (meth)acrylic monomer (C), the flexural strength and the flexural modulus of the resulting stereolithographed products were reduced, as compared to those of Examples 1C to 26C.

In Comparative Example 9C, the Charpy impact strength of the resulting stereolithographed product was also reduced, as compared to that of Examples 1C to 26C.

Claim 1:
A photocurable composition for producing by stereolithography a dental prosthesis, a medical device for intraoral use, or a tooth and/or jaw model, the photocurable composition comprising:
a (meth)acrylic monomer component and a photopolymerization initiator;
wherein a total content of the (meth)acrylic monomer component and the photopolymerization initiator is from <NUM>% by mass or more with respect to a total amount of the photocurable composition, and
wherein the (meth)acrylic monomer component comprises:
an acrylic monomer (X) that is at least one selected from diacrylic monomers containing, within one molecule, two aromatic rings and two acryloyloxy groups, and that has a weight average molecular weight of from <NUM> to <NUM>; and
at least one selected from the group consisting of:
a (meth)acrylic monomer (A) that is at least one selected from di(meth)acrylic monomers not containing, within one molecule, an aromatic ring and containing, within one molecule, one or more ether bonds and two (meth)acryloyloxy groups, and that has a weight average molecular weight of from <NUM> to <NUM>;
a (meth)acrylic monomer (B) that is at least one selected from (meth)acrylic monomers not containing, within one molecule, an aromatic ring and containing, within one molecule, a ring structure other than an aromatic ring and one (meth)acryloyloxy group, and that has a weight average molecular weight of from <NUM> to <NUM>; and
a (meth)acrylic monomer (C) that is at least one selected from di(meth)acrylic monomers not containing, within one molecule, an aromatic ring or an ether bond and containing, within one molecule, a hydrocarbon skeleton and two (meth)acryloyloxy groups, and that has a weight average molecular weight of from <NUM> to <NUM>,
and wherein a total content of the acrylic monomer (X), the (meth)acrylic monomer (A), the (meth)acrylic monomer (B), and the (meth)acrylic monomer (C) in the (meth)acrylic monomer component is <NUM>% by mass or more.