Curable composition for photolithography and method for producing three-dimensional object

Abstract

The present invention provides a liquid curable composition for stereolithography that contains a radically polymerizable monomer component and a photopolymerization initiator, and that has excellent removability when a general-purpose cleaning solvent such as alcohol is used in a cleaning step performed after stereolithography (primary curing), and that can be used to produce a three-dimensional stereolithography object that has excellent long-term water resistance. [Solution] A radical polymerizable monomer component is used, which contains 0.1 to 20 mass% of a highly hydrophilic radical polymerizable monomer (B) having an octanol / water partition coefficient: logPow of -0.7 or less, and which is composed of a non-zwitterionic compound (b1) having 2 to 4 (meth)acrylamide groups in the molecule and / or a zwitterionic compound (b2) having a radical polymerizable group in the molecule, with the remainder being a low hydrophilic radical polymerizable monomer (A) having a logPow of substantially 0 or more.

Description

[Technical Field]

[0001] The present invention relates to a curable composition for stereolithography and a method for producing a stereolithography-modeled object using the composition. [Background technology]

[0002] In recent years, additive manufacturing (AM) has become popular for the production of prototypes and final products. AM technologies can be broadly divided into seven categories: Vat Photopolymerization, Powder Bed Fusion, Binder Jetting, Sheet Lamination, Material Extrusion, Material Jetting, and Direct Energy Deposition. Among these, 3D modeling using the Vat Photopolymerization method (hereinafter sometimes referred to as "stereolithography") involves selectively irradiating a liquid photocurable composition with light to repeatedly form cured layers one by one, thereby obtaining a three-dimensional object by layering the cured layers. This method is applied to the production of prototypes and final products.

[0003] In the liquid vat photopolymerization 3D modeling, the laminate is formed in a liquid photocurable material. The surface of the laminate (comprising a primary cured product of the photocurable composition) having the shape of the target object obtained by the light irradiation is wet with the liquid photocurable material. Therefore, a commonly used method involves removing the laminate, then cleaning it using an organic solvent or the like to remove the liquid photocurable material adhering to the surface, followed by a process called post-polymerization (to completely polymerize the primary cured product) to produce the final product. In the liquid vat photopolymerization 3D modeling, it is virtually impossible to prevent the photocurable material from adhering to the laminate. Therefore, unless the liquid photocurable composition is thoroughly removed in the cleaning process, the photocurable material adhering to the surface of the laminate will also harden due to post-polymerization, preventing the production of a 3D object (the object to be manufactured) with high accuracy.

[0004] As a technique for improving the removability of adhered liquid-type curable compositions for stereolithography during the cleaning process, Patent Document 1 (WO 2014 / 051046) proposes a method using a photopolymerizable composition for stereolithography containing a specific water-soluble radically polymerizable compound, a photopolymerization initiator, and an ionic surfactant. This method is said to enable easy removal of adhered liquid-type curable compositions for stereolithography with water. Patent Document 2 (JP 2007-076090 A) discloses a method for manufacturing a laminate, which includes a step of contacting an absorber that absorbs liquid by capillary action to absorb uncured resin liquid. This method is said to enable reliable cleaning of the laminate and the production of stereolithography objects with high shape accuracy. Furthermore, Patent Document 3 (JP 2020-522586 A) discloses a specific cleaning composition for removing uncured printing resin from 3D-printed laminates, demonstrating that the use of this cleaning composition enables time-efficient removal of uncured printing resin. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2014 / 051046 Brochure [Patent Document 2] Japanese Patent Application Laid-Open No. 2007-076090 [Patent Document 3] Special Publication No. 2020-522586 [Patent Document 4] Japanese Patent Publication No. 2022-041276 Summary of the Invention [Problem to be solved by the invention]

[0006] The photopolymerizable composition disclosed in Patent Document 1 contains a water-soluble radically polymerizable compound and a non-polymerizable ionic surfactant, and thus uncured resin adhering to the laminate can be effectively washed away. However, the water resistance of the molded object itself is not sufficient, and there are still issues when used in environments where water resistance under more severe conditions is required.

[0007] The method of cleaning and removing uncured resin by adsorption using capillary action, as shown in Patent Document 2, is effective to a certain extent for laminates with simple shapes, but it is difficult to completely remove the uncured resin. Furthermore, it is difficult to apply this method to laminates with complex shapes or small sizes, depending on the shape of the laminate, and there was a need to solve further problems.

[0008] The use of the specific cleaning composition disclosed in Patent Document 3 is less versatile than organic solvent cleaning solutions conventionally used to clean uncured resins adhering to laminates, and users are required to procure this cleaning solution separately from the cleaning solution they conventionally use, which poses challenges in terms of inventory management, etc.

[0009] Therefore, an object of the present invention is to provide a photopolymerization composition that is excellent in cleaning and removing properties of the photopolymerization composition adhering to the laminate using a general-purpose organic solvent in three-dimensional modeling using a liquid tank photopolymerization method. [Means for solving the problem]

[0010] The present invention solves the above-mentioned problems, and a first aspect of the present invention provides a liquid curable composition for stereolithography, comprising a radical polymerizable monomer component and a photopolymerization initiator, The radical polymerizable monomer component is a low hydrophilic radical polymerizable monomer (A) having a radical polymerizable group in the molecule and an octanol / water partition coefficient: log Pow of 0 or more; a highly hydrophilic radically polymerizable monomer (B) comprising a non-zwitterionic compound (b1) having 2 to 4 (meth)acrylamide groups in the molecule and having a log Pow of −0.7 or less, and / or a zwitterionic compound (b2) having a radically polymerizable group in the molecule and having a log Pow of −0.7 or less; Contains the contents of (A), (B), and the total amount of (A) and (B): (A)+(B), in the radical polymerizable monomer component are (A): 75 to 99.9 mass%, (B): 0.1 to 20 mass%, and (A)+(B): 95 to 100 mass%, respectively; The curable composition for stereolithography is characterized by the following:

[0011] In the curable composition for stereolithography of the above embodiment (hereinafter also referred to as "curable composition for stereolithography of the present invention"), the compound (b1) is a compound represented by the following general formulas (1) to (3):

[0012] [ka]

[0013] (In the formula, R 1 represents a hydrogen atom or a methyl group, l represents an integer of 2 to 4, m represents an integer of 2 to 4, a represents 0 or 1, and a plurality of R 1 and l may be different from each other.

[0014] [ka]

[0015] (In the formula, R 2represents a hydrogen atom or a methyl group, and R 3 is -CH2CH(R 2 ) represents -CH2- or -CH2CH2-, n represents an integer of 2 to 6, b represents 0 or 1, and a plurality of R 2 , R 3 and n may be different from each other.

[0016] [ka]

[0017] (In the formula, R 4 and R 5 represents a hydrogen atom or a methyl group, o represents an integer of 1 to 3, p represents 2 or 3, c represents an integer of 1 to 3, and there are multiple R 4 , R 5 , o and p may be different from each other.) and at least one compound represented by The zwitterionic compound (b2) has a compound of the formula: -N + (-CH3)(-XO - )-(wherein X is a nitrogen atom at one end: N + and at the other end is an oxygen atom: O - The divalent zwitterionic group in the zwitterionic compound (b2) preferably has a divalent zwitterionic group represented by the formula: -XO - But X´-S(=O)2O - (However, X' has a nitrogen atom at one end: N + and a divalent organic group bonded at one end to a sulfur atom: S.

[0018] Furthermore, it is preferable that the low hydrophilic radical polymerizable monomer (A) comprises a low hydrophilic radical polymerizable monomer (a1) having a viscosity of 500 mPa·s or more at 25°C and 1013 hPa and a low hydrophilic radical polymerizable monomer (a2) having a viscosity of less than 500 mPa·s at 25°C and 1013 hPa, and that the content of (a1) in the radical polymerizable monomer component is 35 mass% and is such that the viscosity of the curable composition for stereolithography at 25°C and 1013 hPa is 200 to 20,000 mPa·s.

[0019] A second aspect of the present invention is a process for producing an intermediate product, comprising: irradiating a predetermined position of a liquid photocurable composition held in a tank with light to selectively cure the liquid photocurable composition present at that position, thereby obtaining a three-dimensional shaped intermediate product made of a primary cured product of the liquid photocurable composition; a washing step of washing the intermediate product with a hydrophilic washing liquid; and a post-polymerization step of secondary curing the three-dimensional object intermediate product washed in the previous step; A method for producing a three-dimensional object comprising: the photocurable composition for stereolithography of the present invention is used as the liquid photocurable composition, and an alcohol-based cleaning liquid is used as the hydrophilic cleaning liquid; The present invention relates to a method for producing a three-dimensional object (hereinafter also referred to as the "production method of the present invention"). [Effects of the Invention]

[0020] According to the method for manufacturing a stereolithography object using the curable composition for stereolithography of the present invention, the uncured resin composition for stereolithography adhered to the laminate can be easily washed away using a general-purpose organic solvent, thereby reducing the labor required for the washing process and making it possible to manufacture a stereolithography object with excellent long-term water resistance. DETAILED DESCRIPTION OF THE INVENTION

[0021] In the cleaning process, cleaning agents consisting of alcohol-based organic solvents such as isopropyl alcohol are commonly used. Therefore, the present inventors have considered that if a radical polymerizable monomer that is soluble in alcohol and not very hydrophilic is used, the cleaning ability of the target three-dimensional object may be improved without reducing the water resistance, and have carried out investigations. As a result, it has been found that a radical polymerizable monomer having a low hydrophilicity and an octanol / water partition coefficient (logP ow The present inventors have found that when a radical polymerizable monomer having a specific structural feature among radical polymerizable monomers having a value of -0.7 or less, specifically a highly hydrophilic radical polymerizable monomer (B) consisting of a non-zwitterionic compound (b1) having 2 to 4 (meth)acrylamide groups in the molecule and / or a zwitterionic compound (b2) having a radical polymerizable group in the molecule, is blended, the cleaning ability is improved even when the blending amount is small, and the water resistance of the target article is not reduced, and this has led to the completion of the present invention.

[0022] Here, the octanol / water partition coefficient is a well-known parameter that quantitatively represents the degree of lipophilicity and hydrophilicity of a substance soluble in an organic solvent, and can be determined in accordance with JIS Z 7260-107. Specifically, a solution of a certain amount of a test substance dissolved in 1-octanol is added to two solvent phases, 1-octanol and water, and mixed thoroughly. When the two phases are separated, the concentration of the test substance in both layers is determined. In other words, the ratio of the test substance concentration in the 1-octanol layer: Co (mol / L) to the test substance concentration in the water layer: Cw (mol / L): Pow = logarithm (base 10) of (Co / Cw). 10 Pow=log 10 (Co / Cw)=log 10 Co-log 10 This is what is required as Cw.

[0023] Octanol / water partition coefficient (logP ow ) value (also referred to as "logPow value") can also be determined by calculation. In this specification, the value calculated using CambridgeSoft's ChemDraw Ultra is referred to as the logPow value.

[0024] Furthermore, a zwitterionic compound refers to a compound having a cationic moiety and an anionic moiety in the molecule, and a non-zwitterionic compound refers to a compound that does not fall under the category of a zwitterionic compound.

[0025] Although stereolithography resin compositions using radical polymerizable monomers containing non-zwitterionic compounds having two or more (meth)acrylamide groups in the molecule are known (see, for example, Patent Document 4), to the best of the inventors' knowledge, there are no stereolithography resin compositions that actually use radical polymerizable monomers with an octanol / water partition coefficient of -0.7 or less.

[0026] The reason why the above-mentioned effects are obtained is not necessarily clear, and the present invention is not bound by any logic. However, it is presumed that, since the highly hydrophilic radical polymerizable monomer (B) is highly compatible with the low hydrophilic radical polymerizable monomer (A) which is the main component and has an octanol / water partition coefficient of 0 or more, the highly hydrophilic radical polymerizable monomer (B) acts as an amphipathic solvent that binds the low hydrophilic radical polymerizable monomer (A) and the cleaning agent in the cleaning removal step, and that the cleaning performance is improved even when a relatively small amount is added.

[0027] The curable composition for stereolithography of the present invention and the method for producing a stereolithography object of the present invention are described below. In this specification, unless otherwise specified, the expression "x to y" using the numerical values ​​x and y means "greater than or equal to x and less than or equal to y." In such a notation, when a unit is assigned only to the numerical value y, the unit also applies to the numerical value x. Furthermore, in this specification, the term "(meth)acrylic" refers to both "acrylic" and "methacrylic." Similarly, the term "(meth)acrylate" refers to both "acrylate" and "methacrylate," and the term "(meth)acrylamide" refers to both "acrylamide" and "methacrylamide."

[0028] 1. Curable composition for stereolithography of the present invention The curable composition for stereolithography of the present invention is a liquid photocurable composition for three-dimensional stereolithography that is used as a liquid photocurable composition for producing a three-dimensional object by a liquid tank photopolymerization method using activating light containing light of a specific wavelength in the ultraviolet or visible light region, i.e., a curable composition for three-dimensional stereolithography by a liquid tank photopolymerization method, and is a liquid curable composition for stereolithography that contains a radically polymerizable monomer component and a photopolymerization initiator.

[0029] Here, "liquid" means that the material is in a liquid state (solution or suspension state) at room temperature and normal pressure (25°C, 1013 hPa), and the viscosity at room temperature and normal pressure (25°C, 1013 hPa) (hereinafter simply referred to as "viscosity") is preferably 200 to 20,000 mPa·s, and more preferably 500 to 10,000 mPa·s. The viscosity is measured at a temperature of 25°C, a shear stress of 1 Pa, and a measurement time of 120 seconds.

[0030] The liquid vat photopolymerization method, which is the target of the use of the photopolymerization composition for stereolithography of the present invention, includes a step of digitizing and ranking the height direction of a three-dimensional object from three-dimensional shape data representing the shape of the three-dimensional object, generating two-dimensional shape data representing the cross-sectional shape of the three-dimensional object at each ranked height, irradiating the liquid photopolymerization composition held in a vat with the activating light at predetermined positions determined based on the two-dimensional shape data to selectively (primarily) cure the liquid photopolymerization composition present at the positions to form modeling layers having the cross-sectional shape, and sequentially forming and stacking modeling layers having the cross-sectional shapes at each height in the order of the ranking, thereby obtaining a three-dimensional stereolithography intermediate product (composed of a primary cured product of the liquid photopolymerization composition) consisting of a laminate having a shape corresponding to the shape of the three-dimensional object, and then performing a washing process with an organic solvent and, if necessary, a secondary curing process to obtain a three-dimensional stereolithography intermediate product having a shape corresponding to the shape of the three-dimensional object.

[0031] The curable composition for photopolymerization of the present invention contains a radical polymerizable monomer component and a photopolymerization initiator in a predetermined quantitative ratio, similar to conventional curable compositions for photopolymerization of the present invention. However, the curable composition for photopolymerization of the present invention uses a low-hydrophilic radical polymerizable monomer (A) as the main component of the radical polymerizable monomer component, which is a liquid component, and by blending this with a certain amount of a high-hydrophilic radical polymerizable monomer (B) having the specific structure described above, it is possible to obtain a laminate that is excellent in washability with organic solvents, and the water resistance of the final molded object that is excellent for a long period of time.

[0032] That is, the curable composition for stereolithography of the present invention is a liquid curable composition for stereolithography containing a radical polymerizable monomer component and a photopolymerization initiator, and the radical polymerizable monomer component includes a low hydrophilic radical polymerizable monomer (A) having a radical polymerizable group in the molecule and having an octanol / water partition coefficient: logPow of 0 or more, a non-zwitterionic compound (b1) having 2 to 4 (meth)acrylamide groups in the molecule and having the logPow of -0.7 or less, and and / or a radically polymerizable group in the molecule, and a highly hydrophilic radically polymerizable monomer (B) comprising a zwitterionic compound (b2) having the logPow of -0.7 or less, and the contents of (A), (B), and the total amount of (A) and (B): (A) + (B) in the radically polymerizable monomer component are (A): 75 to 99.9 mass%, (B): 0.1 to 20 mass%, and (A) + (B): 95 to 100 mass%, respectively. From the viewpoint of effectiveness, the contents of (A), (B), and the total of (A) and (B): (A) + (B) in the radical polymerizable monomer components are preferably (A): 80 to 99.8 mass%, (B): 0.2 to 16 mass%, and (A) + (B): 96 to 100 mass%, respectively, and more preferably (A): 88 to 99.5 mass%, (B): 0.5 to 10 mass%, and (A) + (B): 98 to 100 mass%. If the amount of (A) is too small, i.e., if the amount of (B) is too large, the water resistance of the molded object will decrease. On the other hand, if the amount of (A) is too large, i.e., if the amount of (B) is too small, the washability of the intermediate product with an organic solvent will decrease. The components of the curable composition for stereolithography of the present invention, their blending ratios, etc., are described below.

[0033] 2. Low hydrophilic radical polymerizable monomer (A) The low hydrophilic radical polymerizable monomer (A) can be any low hydrophilic radical polymerizable monomer that has an octanol / water partition coefficient (logPow) of 0 or more and is liquid at room temperature and normal pressure, but it is preferable to use a (meth)acrylate monomer because it can be cured quickly and the strength of the stereolithography product is excellent. The upper limit of logPow is not particularly limited, but is usually 10.0, preferably 7.0.

[0034] From the viewpoints of the modeling speed and the strength of the modeled object, the low hydrophilic radical polymerizable monomer (A) preferably consists of a low hydrophilic radical polymerizable monomer (a1) having a viscosity of 500 mPa·s or more and a low hydrophilic radical polymerizable monomer (a2) having a viscosity of less than 500 mPa·s. The upper limit of the viscosity of (a1) is not particularly limited, but is usually 500,000 mPa·s. The lower limit of the viscosity of (a2) is not particularly limited, but is usually 0.1 mPa·s.

[0035] When (A) is composed of (a1) and (a2), the content of (a1) in the radically polymerizable monomer component is preferably 37.5 to 90 mass%, more preferably 42.5 to 85 mass%, and most preferably 47.5 to 80 mass%, when the content of (A) is 75 to 99.9 mass%. (The content of (a2) is the value obtained by subtracting the content of (a1) from the content of (A).) Similarly, when the content of (A) is 80 to 99.8 mass%, the content of (a1) is preferably 40 to 90 mass%, more preferably 45 to 85 mass%, and most preferably 50 to 80 mass%. Furthermore, when the content of (A) is 88 to 99.5 mass%, the content of (a1) is preferably 44 to 90 mass%, more preferably 49 to 85 mass%, and most preferably 54 to 80 mass%, on the premise that the curable composition for stereolithography is liquid at room temperature and normal pressure, preferably with a viscosity of 200 to 20,000 mPa s.

[0036] As the (a1): low hydrophilic radical polymerizable monomer having a viscosity of 500 mPa·s or more, any conventionally known monomer may be used without limitation as long as it satisfies the above requirements, and one or more of them may be used in combination. Suitable examples of usable (meth)acrylates include BPA skeleton-containing (meth)acrylates such as 2,2'-bis{4-[3-(meth)acryloyloxy-2-hydroxypropoxy]phenyl}propane (logPow=5.09, viscosity=450,000 mPa·s, abbreviation: Bis-GMA), 2,2'-bis[4-(meth)acryloyloxyphenyl]propane, and 2,2'-bis[4-(meth)acryloyloxypolyethoxyphenyl]propane (logPow=6.07, viscosity=730 mPa·s, abbreviation: D-2.6E); and urethane group-containing (meth)acrylates such as 1,6-bis(methacryloyloxy-2-ethoxycarbonylamino)-2,2,4-trimethylhexane (logPow=3.39, viscosity=5,200 mPa·s, abbreviation: UDMA). Examples include (meth)acrylates containing an isocyanate skeleton, such as tris(2-methacryloyloxyethyl)isocyanurate. Among these, it is more preferable to use Bis-GMA, D-2.6E, and UDMA because they provide a bonded layer with high strength during the molding process.

[0037] On the other hand, (a2): as the low hydrophilic radical polymerizable monomer having a viscosity of less than 500 mPa s, any conventionally known monomer that satisfies the above requirements can be used without limitation, and one or more of them may be used in combination. Examples of suitable monomers include those shown below. Note that the log Pow and viscosity values ​​in the examples below differ depending on whether the monomer is an acrylate or a methacrylate, and therefore the values ​​for methacrylate are shown in parentheses.

[0038] Methyl (meth)acrylate {logPow=0.64(0.99), viscosity=0.5(0.5)mPa·s}, ethyl (meth)acrylate {logPow=0.98(1.33), viscosity=0.5(0.5)mPa·s}, isobornyl (meth)acrylate {logPow=3.63(3.98), viscosity=8(8)mPa·s}, 2-morpholinoethyl (meth)acrylate {logPow=0.24(0.59), viscosity=3(3)mPa·s}, hydroxyethyl (meth)acrylate Monofunctional (meth)acrylates such as tetrahydrofurfuryl (meth)acrylate {logPow=0.12(0.47), viscosity=6(6)mPa·s}, glycerol mono(meth)acrylate {logPow=0.93(1.28), viscosity=150(150)mPa·s}, tetrahydrofurfuryl (meth)acrylate {logPow=0.78(1.13), viscosity=3(3)mPa·s}, and glycidyl (meth)acrylate {logPow=0.22(0.57), viscosity=2(2)mPa·s}; Examples include polyfunctional (meth)acrylates such as ethylene glycol di(meth)acrylate {logPow=1.04(1.74)}, triethylene glycol di(meth)acrylate {logPow=0.72(1.42), viscosity=6(6)mPa·s}, 1,6-hexanediol di(meth)acrylate {logPow=2.43(3.13), viscosity=6(6)mPa·s}, 1,9-nonanediol di(meth)acrylate {logPow=3.68(4.38), viscosity=8(8)mPa·s}, and trimethylolpropane tri(meth)acrylate {logPow=2.52(3.57), viscosity=50(45)mPa·s}.

[0039] Among these, it is more preferable to use hydroxyethyl (meth)acrylate, glycerol mono(meth)acrylate, triethylene glycol di(meth)acrylate, and 1,6-hexanediol di(meth)acrylate because they have low viscosity and excellent curing properties.

[0040] 3. Highly hydrophilic radical polymerizable monomer (B) The highly hydrophilic radically polymerizable monomer (B) comprises a non-zwitterionic compound (b1) having two to four (meth)acrylamide groups in the molecule, a log Pow of -0.7 or less, and a liquid at room temperature and normal pressure, and / or a zwitterionic compound (b2) having a radically polymerizable group in the molecule, a log Pow of -0.7 or less, and a liquid at room temperature and normal pressure, and functions to easily remove uncured liquid photocurable composition present on the surface of the laminate in a cleaning step. The lower limit of the log Pow is not particularly limited, but is typically -5.0, preferably -3.0.

[0041] Here, the term "(meth)acrylamide group" refers to a structure having a (meth)acryl group and an amide group. The term "zwitterionic compound" refers to a compound (inner salt) that has a positive charge and a negative charge at non-adjacent positions in the same molecule, in which the positively charged atom has no dissociable hydrogen bonded thereto (having a quaternary ammonium, sulfonium, phosphonium, or other cationic structure), and in which the molecule as a whole has no charge. The term "non-zwitterionic compound" refers to a compound that is not a zwitterionic compound.

[0042] The non-zwitterionic compound (b1) having 2 to 4 (meth)acrylamide groups in the molecule and having a logPow of −0.7 or less is preferably at least one compound represented by the following general formulas (1) to (3):

[0043] [ka]

[0044] [ka]

[0045] [ka]

[0046] In addition, R in the general formula (1) 1represents a hydrogen atom or a methyl group, l represents an integer of 2 to 4, m represents an integer of 2 to 4, and a represents 0 or 1. In addition, if there are multiple (two) R 1 and (C l H 2l The )l may be different from each other.

[0047] In addition, R in the general formula (2) 2 represents a hydrogen atom or a methyl group, and R 3 is -CH2CH(R 2 ) represents -CH2- or -CH2CH2-, n represents an integer of 2 to 6, and b represents 0 or 1. 3 Multiple R's in 2 Similarly, multiple R 3 and (C n H 2n The n's may be different from each other.

[0048] Furthermore, R in the general formula (3) 4 and R 5 each independently represents a hydrogen atom or a methyl group, o represents an integer of 1 to 3, p represents 2 or 3, and c represents an integer of 1 to 3. In addition, when a plurality of R 4 , R 5 , (C o H 2o of)o and (C p H 2p The p's may be different from each other.

[0049] An example of a suitable non-zwitterionic compound (b1) is N,N'-[oxybis(2,1-ethanediyloxy-3,1-propanediyl)]bisacrylamide (LogP ow =-0.87), N-[tris(3-acrylamidopropoxymethyl)methyl]acrylamide (LogP ow =-1.25), N,N-bis(2-acrylamidoethyl)acrylamide (LogP ow =-1.50), N,N'-1,2-ethanediylbis{N-[2-(acryloylamino)ethyl]acrylamide (LogPow =-1.97).

[0050] Among these, LogP ow N-[tris(3-acrylamidopropoxymethyl)methyl]acrylamide, N,N-bis(2-acrylamidoethyl)acrylamide, and N,N'-1,2-ethanediylbis{N-[2-(acryloylamino)ethyl]acrylamide}, which have a LogP of -1.1 or less, can be suitably used. ow N,N-bis(2-acrylamidoethyl)acrylamide and N,N'-1,2-ethanediylbis{N-[2-(acryloylamino)ethyl]acrylamide}, which have a value of -1.5 or less, can be particularly preferably used.

[0051] The zwitterionic compound (b2) has a structure represented by the formula: -N + (-CH3)(-XO - )-(wherein X is a nitrogen atom at one end: N + and at the other end is an oxygen atom: O - and a divalent organic group bonded to the divalent zwitterionic group represented by the formula: - But X´-S(=O)2O - (However, X' has a nitrogen atom at one end: N + A compound having a divalent zwitterionic group represented by the formula (LogP) is preferably used. An example of a compound having such a divalent zwitterionic group is 3-{[2-(methacryloyloxy)ethyl]dimethylammonio}propionate (LogP). ow =-0.80), 2-methacryloyloxyethyl phosphorylcholine (LogP ow =-1.00), bis{[2-(methacryloyloxy)ethyl](methyl)ammonio}propane-1-sulfonic acid (LogP ow =-1.30), N,N-dimethyl-N-(2-methacryloxyethyl)-N-(3-sulfopropyl)ammonium betaine (LogP ow =-2.23).

[0052] Among these, LogP ow Bis{[2-(methacryloyloxy)ethyl](methyl)ammonio}propane-1-sulfonic acid and N,N-dimethyl-N-(2-methacryloxyethyl)-N-(3-sulfopropyl)ammonium betaine, which have a LogP of -1.1 or less, can be suitably used. ow N,N-dimethyl-N-(2-methacryloxyethyl)-N-(3-sulfopropyl)ammonium betaine, which has a value of -1.5 or less, is particularly suitable. Furthermore, 4-[(3-methacrylamidopropyl)dimethylammonio]butane-1-sulfonic acid and 3-[(3-methacrylamidopropyl)dimethylammonio]propane-1-sulfonic acid, which have both a (meth)acrylamide structure and a betaine structure, are most suitable.

[0053] 4. Other radical polymerizable monomers (C) The radical polymerizable monomer component preferably consists of only a low-hydrophilic radical polymerizable monomer (A) and a high-hydrophilic radical polymerizable monomer (B), but other radical polymerizable monomers (liquid at room temperature) other than these may be used as long as their content is less than 5% by mass. Usable other radical polymerizable monomers (C) include acrylamide (LogPow=-0.27 ), polyethylene glycol #600 dimethacrylate (LogPow=-1.36), etc.

[0054] 5. Photopolymerization initiator The curable composition for stereolithography in the present invention must contain a photopolymerization initiator (hereinafter also referred to as photopolymerization initiator) that generates radicals by absorbing activating light, specifically ultraviolet or visible light, irradiated from a light source mounted on a stereolithography device, and has the function of radically polymerizing the radically polymerizable monomer component. Therefore, the photopolymerization initiator must be one that absorbs the activating light to generate radicals depending on the activating light used. The photopolymerization initiator may be appropriately selected from known photopolymerization initiators that satisfy the above conditions. The photopolymerization initiator to be selected is not particularly limited, and examples thereof include self-cleavage photopolymerization initiators, bimolecular hydrogen abstraction photopolymerization initiators, photoacid generators, and combinations thereof. These photopolymerization initiators may also be used in combination with photosensitizing dyes, electron-donating compounds, etc.

[0055] Examples of photopolymerization initiators, photosensitizing dyes and electron donating compounds that can be suitably used are shown below.

[0056] That is, examples of self-cleavage photopolymerization initiators that can be suitably used include acylphosphine oxide compounds such as diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide and phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, benzoketal compounds, benzyne compounds, α-aminoacetophenone compounds, α-hydroxyacetophenone compounds, titanocene compounds, and acyloxime compounds. Examples of photoacid generators include iodonium salt compounds such as p-isopropylphenyl-p-methylphenyliodonium tetrakispentafluorophenylborate salt, sulfonium salt compounds such as dimethylphenylsulfonium hexafluoroantimonate salt, and halomethyl-substituted triazine compounds such as 2,4,6-tris(trichloromethyl)-s-triazine. Examples of photosensitizing dyes that can be used include ketone compounds, coumarin dyes, cyanine dyes, merocyanine dyes, thiazine dyes, azine dyes, acridine dyes, xanthene dyes, squarium dyes, pyrylium salt dyes, condensed polycyclic aromatic compounds such as anthracene and perylene, and thioxanthone compounds. Examples of electron donors include 4-dimethylaminobenzoic acid esters, 4-dimethylaminotoluene, p-dimethoxybenzene, 1,2,4-trimethoxybenzene, and thiophene compounds.

[0057] Furthermore, taking into consideration that the wavelength of the activation light emitted from the light source in a typical stereolithography device is 350 nm to 420 nm, it is particularly preferable to use phenylbis(2,4,6-trimethylbenzoyl)-phosphine oxide.

[0058] The amount of photopolymerization initiator blended into the curable composition for stereolithography of the present invention is 0.01 to 5 parts by mass relative to 100 parts by mass of the radical polymerizable monomer components. If the amount of photopolymerization initiator blended is too high, there is a risk that the composition will be cured in areas that deviate from the desired shape during the molding process, reducing the molding precision of the molded product. On the other hand, if the amount blended is too low, there is a risk that the composition will not be cured sufficiently during the molding process, making it impossible to obtain a molded product. For these reasons, the amount of photopolymerization initiator blended is preferably 0.1 to 4.5 parts by mass, more preferably 0.2 to 4.3 parts by mass, and particularly preferably 0.3 to 4.0 parts by mass, relative to 100 parts by mass of the radical polymerizable monomer components.

[0059] 6. Other optional ingredients Thermal polymerization initiator The curable composition for stereolithography of the present invention functions as a polymerization initiator for secondary curing in a subsequent process, and from the viewpoint of remaining effective in the laminate without functioning during primary curing in the molding process, may contain a thermal polymerization initiator with a 10-hour half-life temperature of 50 to 130°C within a range that does not impair its effectiveness. Examples of such thermal polymerization initiators include organic peroxides such as tert-butyl peroxylaurate and benzoyl peroxide, and azo compounds such as azobutyronitrile and azobis(dimethylvaleronitrile). The amount of the thermal polymerization initiator used is typically within a range of 0.001 to 1 part by mass per 100 parts by mass of the radically polymerizable monomer component.

[0060] Activated light absorber that absorbs activated light The curable composition for stereolithography of the present invention may contain an activating light absorber (hereinafter also referred to as activating light absorber) that absorbs activating light, such as ultraviolet or visible light, emitted from the stereolithography device, to a degree that does not impair its effectiveness, in order to prevent excessive transmission of activating light irradiated from the stereolithography device and thereby reduce the molding accuracy of the molded body. The activating light absorber is not particularly limited as long as it is a compound that absorbs the light from the light source installed in the stereolithography device. Examples of activating light absorbers that can be used include triazole compounds such as 2-(hydroxy-5-methylphenyl)-2H-benzotriazole and 2-(3-tert-butyl-2-hydroxy-5-methylphenyl)-5-chloro-2H-benzotriazole, and benzophenone compounds such as 2,4-dihydroxybenzophenone and 2-hydroxy-4-methoxybenzophenone. The amount of activating light absorber used is typically in the range of 0.01 to 3 parts by weight per 100 parts by weight of the radically polymerizable monomer component.

[0061] Polymerization inhibitor The curable composition for stereolithography of the present invention may contain a polymerization inhibitor to the extent that its effects are not impaired, in order to improve its storage stability and to prevent excessive diffusion of radicals generated by activating light during the molding process, resulting in curing of unnecessary portions. Such a polymerization inhibitor can be any known polymerization inhibitor that reacts with radicals generated in the curable composition for stereolithography to deactivate them, such as di-tert-butyl-p-cresol or 4-methoxyphenol. The amount of the polymerization inhibitor is typically in the range of 0.001 to 5 parts by mass per 100 parts by mass of the radically polymerizable monomer component.

[0062] The curable composition for stereolithography of the present invention may contain other optional components other than those described above, such as additives such as ultraviolet absorbers, fillers, colorants, pigments, dispersants, and chain transfer agents, to the extent that the effects of these additives are not impaired.

[0063] 7. Manufacturing method of the present invention The manufacturing method of the present invention is a method for manufacturing a three-dimensional object, comprising: an intermediate product manufacturing step of irradiating a predetermined position of a liquid photocurable composition held in a tank with light to selectively cure the liquid photocurable composition present at that position, thereby obtaining a three-dimensional object intermediate product consisting of a primary cured product of the liquid photocurable composition; a cleaning step of cleaning the intermediate product with a hydrophilic cleaning liquid; and a post-polymerization step of secondary curing the three-dimensional object intermediate product cleaned in the above step, wherein the method is characterized in that the photocurable composition for stereolithography of the present invention is used as the liquid photocurable composition, and an alcohol-based cleaning liquid is used as the hydrophilic cleaning liquid.

[0064] From the viewpoints of user safety, availability, etc., ethanol or isopropyl alcohol is preferably used as the alcohol-based solvent.

[0065] As described above, stereolithography (three-dimensional modeling using a liquid vat photopolymerization method) including the intermediate product manufacturing process, cleaning process, and post-polymerization process is common, and the manufacturing method of the present invention is not particularly different from such common stereolithography except for the above-mentioned features. For example, the intermediate product manufacturing process can be carried out using a stereolithography device that uses a laser, Digital Light Processing (DLP), or Liquid Crystal Display (LCD) as an irradiation light source, and is particularly preferably carried out using a stereolithography device that uses a laser as an irradiation light source, which has high modeling accuracy.

[0066] The cleaning step can be carried out without particular limitation as long as it is a method that removes the uncured stereolithography curable composition adhering to the intermediate product using an alcohol-based solvent. Examples of cleaning methods that can be used include wipe cleaning, immersion cleaning, penetration cleaning, and ultrasonic cleaning. From the viewpoints of reliable removal and simplicity, immersion cleaning, penetration cleaning, and ultrasonic cleaning are preferred. The cleaning time is usually 3 to 30 minutes, but from the viewpoint of preventing deterioration of the physical properties of the intermediate product, a cleaning time of 5 to 15 minutes is preferred.

[0067] Furthermore, the secondary curing in the post-polymerization step can be carried out by photopolymerization and / or thermal polymerization. The wavelength of the activating light used in photopolymerization is not particularly limited as long as it is a wavelength that can be absorbed by the photopolymerization initiator remaining in the laminate to generate radicals. The irradiation intensity of the additional light irradiation is preferably 5 mW / cm or less so that the photopolymerization initiator remaining in the stereolithography object can generate a sufficient amount of radicals. 2 More than 10mW / cm is preferable. 2 More preferably, 30 mW / cm or more 2 More preferably, the irradiation time is 1 minute or more, more preferably 3 minutes or more, and even more preferably 5 minutes or more. If the irradiation intensity during the additional light irradiation is too strong, the stereolithography object may be overheated, which may cause cracks in the stereolithography object. Therefore, the irradiation intensity should be 10,000 mW / cm 2 It is preferable that:

[0068] When thermal polymerization is carried out as the secondary curing treatment, a thermal polymerization initiator may be added to the photocurable composition of the present invention, and the secondary curing may be carried out by heating. The heating temperature is usually within the range of 45 to 120°C.

[0069] Furthermore, the secondary curing treatment may involve both photopolymerization and thermal polymerization.

[0070] The curable composition for stereolithography of the present invention and the manufacturing method of the present invention can be used in a variety of applications, and are also suitable for use in dental articles. Examples of dental articles that can be suitably used include denture materials, crown restoration materials, model materials, and clinical guide materials. Cleaning efficiency is particularly advantageous when the laminate size is large, and use as denture materials, model materials, and clinical guide materials is particularly preferred. [Example]

[0071] The present invention will be explained in more detail below with reference to examples, but the present invention is not limited to these examples.

[0072] 1. Abbreviations and compounds used in the examples and comparative examples (1) Low hydrophilic radical polymerizable monomer (A) (a1) A low-hydrophilic radical polymerizable monomer having a viscosity of 500 mPa·s or more UDMA: 1,6-bis(methacryloyloxy-2-ethoxycarbonylamino)-2,2,4-trimethylhexane (logPow=3.39, viscosity=5200 mPa·s) D-2.6E: 2,2'-bis[4-methacryloyloxypolyethoxyphenyl]propane (logPow=6.07, viscosity=730 mPa·s) (a2) A low-hydrophilic radical polymerizable monomer having a viscosity of less than 500 mPa·s GLM: Glycerol monomethacrylate (logPow = 1.28, viscosity = 150 mPa·s) 3G: Triethylene glycol dimethacrylate (logPow=1.42, viscosity=6 mPa·s) (2) Highly hydrophilic radical polymerizable monomer (B) (b1) A non-zwitterionic compound having 2 to 4 (meth)acrylamide groups in the molecule b11: N,N'-1,2-ethanediylbis{N-[2-(acryloylamino)ethyl]acrylamide} (LogP ow =-1.97)

[0073] [ka]

[0074] b12: N,N-bis(2-acrylamidoethyl)acrylamide (LogP ow =-1.50)

[0075] [ka]

[0076] b13: N-[tris(3-acrylamidopropoxymethyl)methyl]acrylamide (LogP ow =-1.25)

[0077] [ka]

[0078] b14: ​​N,N'-[oxybis(2,1-ethanediyloxy-3,1-propanediyl)]bisacrylamide (LogP ow =-0.87)

[0079] [ka]

[0080] (b2) Zwitterionic compound having a radical polymerizable group in the molecule b21: N,N-dimethyl-N-(2-methacryloxyethyl)-N-(3-sulfopropyl)ammonium betaine (LogP ow =-2.23)

[0081] [ka]

[0082] b22: 4-[(3-methacrylamidopropyl)dimethylammonio]butane-1-sulfonic acid (LogP ow =-2.32)

[0083] [ka]

[0084] b23: Bis[2-(methacryloyloxy)ethyl](methyl)ammonio]propane-1-sulfonic acid (LogP ow =-1.30)

[0085] [ka]

[0086] b24: 3-[[2-(methacryloyloxy)ethyl]dimethylammonio]propionate (LogP ow =-0.80)

[0087] [ka]

[0088] (3) Other radical polymerizable monomers (C) c1: Acrylamide (LogP ow =-0.27)

[0089] [ka]

[0090] c2: Polyethylene glycol #600 dimethacrylate (LogP ow =-1.36)

[0091] [ka]

[0092] (4) Photopolymerization initiator ·d: Bisacylphosphine oxide.

[0093] (5) Activation light absorber that absorbs activation light ·e: 2-(3-tert-butyl-2-hydroxy-5-methylphenyl)-5-chloro-2H-benzotriazole.

[0094] (6) Polymerization inhibitor f1: Dibutylhydroxytoluene · f2: Hydroquinone methyl ether.

[0095] 2. Evaluation Method (1) Viscosity of the curable composition for stereolithography The viscosity of the liquid curable composition for stereolithography was measured using a CS rheometer (MCR302 manufactured by Anton Paar) at 25° C., 1013 hPa, a shear stress of 1 Pa, and a measurement time of 120 seconds.

[0096] (2) Cleaning evaluation Using the liquid photopolymerization curable composition (photopolymerization resin) prepared in each example and comparative example, a molded object was produced using a 3D printer (Formlabs: Form2) based on the shape data of an outer dimension of 16mm x 20mm x 12mm, with only the top surface open, and an inner dimension of 12mm x 16mm x 10mm. The molded object was immersed in 30ml of isopropyl alcohol for a predetermined time as the evaluation standard, and then removed from the isopropyl alcohol and left to dry at 25°C for 1 minute to obtain a washed molded object. The uncured liquid photopolymerization resin present on the surface of the washed molded object was evaluated by palpation, and a cleanability evaluation was performed. The criteria for cleanability evaluation are shown below.

[0097] ◎: No stickiness when palpated after 2 minutes of immersion 〇: No stickiness upon palpation after 4 minutes of immersion △: No stickiness when palpated after 6 minutes of immersion ×: Stickiness is felt when palpated after 6 minutes of immersion (3) Water resistance evaluation Using the liquid photopolymerization curable composition (photopolymerizable resin) prepared in each example and comparative example, ten molded objects measuring 2mm x 2mm x 25mm were produced using a 3D printer (Formlabs: Form2). The molded objects were immersed in 30ml of isopropyl alcohol and ultrasonicated for 10 minutes. The molded objects were then removed from the isopropyl alcohol and allowed to dry at 25°C for 1 minute to remove any uncured liquid photopolymerizable resin present on the surface of the molded objects. Subsequently, a dental laboratory photopolymerization device (Morita: Alpha Light V) was used to perform a secondary curing process by photopolymerization for 10 minutes to obtain molded objects. Five of the molded objects were polished with #800 waterproof abrasive paper and mounted on a universal testing machine (Shimadzu Corporation, Autograph AG5000D). The three-point bending fracture strength was measured at a support distance of 20mm and a crosshead speed of 1mm / min. The average of the five objects was recorded as the initial bending strength (σ0). The remaining five of the molded objects were immersed in water at 37°C for 30 days, after which the surfaces were smoothed with #800 waterproof abrasive paper and mounted on a universal testing machine (Shimadzu Corporation, Autograph AG5000D). The three-point bending strength was measured at a support distance of 20 mm and a crosshead speed of 1 mm / min, and the average value of the five objects was taken as the bending strength after immersion in water (σ1). Water resistance was evaluated based on the value obtained by dividing the bending strength after immersion in water (σ1) by the initial bending strength (σ0).

[0098] Example 1 To 100 g of radically polymerizable monomers containing 96 g of (A) (72 g of (a1) UDMA and 24 g of (a2) GLM) and 4 g of (B) b11, 1.4 g of photopolymerization initiator d, 0.7 g of activating light absorber e, 0.1 g of polymerization inhibitor f1, and 0.1 g of polymerization inhibitor f2 were added and stirred under red light until homogeneous, to prepare a liquid curable composition for stereolithography. This was evaluated using the methods described above. The results are shown in Table 3.

[0099] [Table 1]

[0100] [Table 2]

[0101] [Table 3]

[0102] Examples 2 to 24, Comparative Examples 1 to 5 A stereolithography curable composition was prepared in the same manner as in Example 1, except that the components and blending amounts used when preparing the stereolithography curable composition were changed as shown in Tables 1 and 2. Thereafter, a three-dimensional object was produced and evaluated using the obtained stereolithography curable composition in the same manner as in Example 1. The evaluation results are shown in Table 3.

[0103] As shown in Table 3, in the laminates formed using the stereolithography curable compositions of Examples 1 to 24, the uncured stereolithography curable composition adhering to the surface of the laminate was easily cleaned, and the water resistance of the molded objects formed by subjecting the washed laminates to a secondary curing treatment was also evaluated as being good. On the other hand, the stereolithography curable compositions of Comparative Examples 1 and 3 exhibited poor cleanability. Furthermore, the stereolithography curable composition of Comparative Example 2 exhibited good cleanability evaluation but poor water resistance. The stereolithography curable compositions of Comparative Examples 4 and 5 exhibited poor cleanability.

Claims

1. A liquid curable composition for stereolithography, comprising a radical polymerizable monomer component and a photopolymerization initiator, The radical polymerizable monomer component is a low hydrophilic radically polymerizable monomer (A) having a radically polymerizable group in the molecule and having an octanol / water partition coefficient: log Pow of 0 or more; a highly hydrophilic radically polymerizable monomer (B) comprising a non-zwitterionic compound (b1) having 2 to 4 (meth)acrylamide groups in the molecule and having a log Pow of −0.7 or less and / or a zwitterionic compound (b2) having a radically polymerizable group in the molecule and having a log Pow of −0.7 or less; Contains the contents of (A), (B), and the total amount of (A) and (B): (A) + (B), in the radical polymerizable monomer component are (A): 75 to 99.9 mass%, (B): 0.1 to 20 mass%, and (A) + (B): 95 to 100 mass%, respectively; A curable composition for stereolithography, comprising:

2. The compound (b1) is represented by the following general formulas (1) to (3): 【Chemistry 1】 (In the formula, R １ represents a hydrogen atom or a methyl group, l represents an integer of 2 to 4, m represents an integer of 2 to 4, a represents 0 or 1, and a plurality of R １ and l may be different from each other. 【Chemistry 2】 (In the formula, R ２ represents a hydrogen atom or a methyl group, R ３ Ha-CH ２ CH (R ２ ) CH ２ - or -CH ２ CH ２ -, n represents an integer of 2 to 6, b represents 0 or 1, and there are a plurality of R ２ , R ３ and n may be different from each other.) 【Transformation 3】 (In the formula, R ４ and R ５ represents a hydrogen atom or a methyl group, o represents an integer of 1 to 3, p represents 2 or 3, c represents an integer of 1 to 3, and there are a plurality of R ４ , R ５ , o and p may be different from each other. and at least one compound represented by The zwitterionic compound (b2) has a compound represented by the formula: -N ＋ (-CH ３ ) (-X-O － )-(wherein X is a nitrogen atom: N ＋ and an oxygen atom: O － and a divalent organic group bonded to the The curable composition for stereolithography according to claim 1 .

3. 3. The curable composition for stereolithography according to claim 1, wherein the low hydrophilic radical polymerizable monomer (A) comprises a low hydrophilic radical polymerizable monomer (a1) having a viscosity of 500 mPa·s or more at 25°C and 1013 hPa and a low hydrophilic radical polymerizable monomer (a2) having a viscosity of less than 500 mPa·s at 25°C and 1013 hPa, and the content of (a1) in the radical polymerizable monomer components is 37.5 to 90 mass% and is such that the viscosity of the curable composition for stereolithography at 25°C and 1013 hPa is 200 to 20,000 mPa·s.

4. an intermediate product manufacturing step of irradiating light onto a predetermined position of the liquid photocurable composition held in a tank to selectively cure the liquid photocurable composition present at that position, thereby obtaining a three-dimensional shaped intermediate product made of a primary cured product of the liquid photocurable composition; a washing step of washing the intermediate product with a hydrophilic washing liquid; and a post-polymerization step of secondary curing the three-dimensional object intermediate product washed in the above step; A method for producing a three-dimensional object comprising: The photocurable composition for stereolithography according to claim 1 is used as the liquid photocurable composition, and an alcohol-based cleaning liquid is used as the hydrophilic cleaning liquid. A method for manufacturing a three-dimensional object, comprising:

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