Manufacturing methods for three-dimensional objects

Abstract

To provide a method for manufacturing three-dimensional objects that can produce three-dimensional objects with high throughput and excellent impact resistance. [Solution] A method for manufacturing a three-dimensional object, comprising the steps of: (0) positioning a pseudoplastic fluid contained in a liquid tank between the molding surface of a three-dimensional object supported on a stage and a transparent member; (i) reducing the distance between the stage and the transparent member to form a liquid film; and (ii) irradiating light from a light source through the transparent member to harden the liquid film and form a hardened layer on the molding surface, wherein the film thickness in step (i) is 5 μm or more and 250 μm or less, the amount of change A per unit time of the distance between the molding surface and the transparent member from a position where the distance between the molding surface and the transparent member is 0.50 mm to the formation of the liquid film is 0.20 mm / sec or more and less than 25 mm / sec, the waiting time B from the formation of the liquid film 18 to the irradiation of light is 0.04 sec or more and 10 sec or less, and the relationship between A and B is 0.2 ≤ B / A ≤ 5.0.

Description

[Technical Field]

[0001] This disclosure relates to a method for manufacturing three-dimensional objects. [Background technology]

[0002] Stereolithography, which uses liquid photocurable resin, is a method of manufacturing three-dimensional objects by selectively irradiating light onto a three-dimensional model based on its three-dimensional shape, curing the resin, and repeating the process to form a cured layer, thereby integrally stacking the cured layer. Stereolithography is broadly classified into free-level and controlled-level methods, depending on the method of supplying the photocurable resin. In the free-level method, a stage is immersed in a liquid photocurable resin contained in a liquid tank, and light is shone through the free liquid surface, which is not restricted by a lid or window, to form a three-dimensional object on the stage. Once the first layer has cured, it is necessary to supply photocurable resin to form the next layer on top of the cured layer, and it is necessary to wait for the next curing light to be shone until the resin supply and the free liquid surface have been smoothed (the shaking has subsided) are complete. On the other hand, in the controlled liquid level method, a photocurable resin is contained in a liquid tank with a light-transmitting transparent material laid at the bottom, and light is irradiated through the transparent material that regulates the liquid level to form a three-dimensional object on the stage. Once the first layer has cured, it is necessary to supply photocurable resin to form the next layer, and it is necessary to wait for the next curing light to irradiate until the space created by separating the transparent material from the stage is filled with photocurable resin. However, unlike the free liquid level method, once the filling is complete, it is not necessary to wait for the free liquid level to smooth out (for the shaking to subside), which is advantageous in terms of molding speed. Furthermore, stereolithography is broadly classified into laser scanning and surface exposure methods based on the light irradiation method. The former sequentially forms hardened layers through point exposure by scanning laser light, while the latter can form hardened layers all at once through surface exposure using patterned light. Therefore, the surface exposure method is advantageous from the viewpoint of manufacturing speed, as it can shorten the time required to form one layer of hardened layer, especially when the exposure area is large, compared to the laser scanning method. In addition, the surface exposure method has the advantage of suppressing variations in physical properties within the hardened layer surface, and thus reducing the occurrence of distortion. Until now, stereolithography has primarily been applied to the creation of prototypes for shape verification (rapid prototyping) and the creation of working models and molds for functional verification (rapid tooling). However, in recent years, the applications of stereolithography have begun to expand to the creation of actual products (rapid manufacturing). Against this backdrop, there is a strong demand for methods to produce three-dimensional objects with excellent impact resistance comparable to general-purpose engineering plastics, as well as methods to achieve high throughput (high printing speed) in manufacturing. A generally known method for improving the impact resistance of three-dimensional objects is to incorporate soft particles, such as rubber particles, into a photocurable resin. For example, Patent Document 1 discloses a three-dimensional object manufactured using a photocurable resin composition containing rubber particles, urethane (meth)acrylate, a radical polymerizable compound, and a photoradical polymerization initiator, based on stereolithography. Furthermore, as mentioned above, effective methods for improving throughput in the manufacturing of three-dimensional objects include adopting the controlled liquid level method for supplying photocurable resin and the surface exposure method for light irradiation. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2004-51665 [Overview of the project] [Problems that the invention aims to solve]

[0004] However, although Patent Document 1 describes the production of three-dimensional molded objects containing rubber particles using the controlled liquid level method, the light irradiation method employs a laser scanning method, which presented challenges in achieving high throughput. Furthermore, our investigations have revealed that when a photocurable resin composition containing rubber particles similar to that in Patent Document 1 is used and a surface exposure stereolithography method based on the regulated liquid level method is applied, there is a problem of reduced impact resistance. In other words, when a photocurable resin composition containing particles is used and a surface exposure stereolithography method based on the regulated liquid level method is applied, there is a problem in achieving both high impact resistance and high throughput. This disclosure aims to provide a method for manufacturing three-dimensional objects that can be produced with high throughput and excellent impact resistance. [Means for solving the problem]

[0005] According to one aspect of this disclosure, A method for manufacturing a three-dimensional object using a surface exposure type stereolithography apparatus, comprising a liquid photocurable resin composition containing a photocurable resin and particles, The aforementioned photocurable resin composition is a pseudoplastic fluid whose viscosity decreases with the application of shear stress. The stereolithography apparatus includes a light source, a stage for forming the three-dimensional object, and a liquid tank on which a transparent member that transmits light from the light source is laid on the bottom surface. Step (0) is to position the pseudoplastic fluid contained in the liquid tank between the molded surface of the three-dimensional object supported on the stage and the transparent member, From the state of step (0) above, step (i) is performed to reduce the distance between the stage and the transparent member and to form a liquid film consisting of the pseudoplastic fluid between the molded surface of the three-dimensional object supported on the stage and the transparent member, The process includes (ii) irradiating the liquid film with light from the light source through the transparent member to harden it and form a hardened layer on the molded surface, The film thickness of the liquid film in the step (i) is 5 μm or more and 250 μm or less, In the step (i), the amount of change per unit time A of the distance between the molding surface and the transparent member from the position where the distance between the molding surface and the transparent member is 0.50 mm to the formation of the liquid film is 0.20 mm / sec or more and less than 25 mm / sec, The waiting time B from the formation of the liquid film in the step (i) to the irradiation of light in the step (ii) is 0.04 sec or more and 10 sec or less, and The relationship between A and B satisfies 0.2 ≤ B / A ≤ 5.0, This is a method for manufacturing a three-dimensional shaped object, characterized by the above.

[0006] Also, according to another aspect, A method for manufacturing a three-dimensional shaped object by a surface exposure type optical shaping apparatus using a liquid photocurable resin composition containing a photocurable resin and particles, The photocurable resin composition is a pseudoplastic fluid whose viscosity decreases with the application of shear stress, The optical shaping apparatus includes a light source, a stage for shaping the three-dimensional shaped object, and a liquid tank having a transparent member through which light from the light source is transmitted laid on the bottom surface, A step (0) of placing the pseudoplastic fluid accommodated in the liquid tank between the molding surface of the three-dimensional shaped object supported by the stage and the transparent member, From the state of the step (0), a step (i) of reducing the distance between the stage and the transparent member to form a liquid film made of the pseudoplastic fluid between the molding surface of the three-dimensional shaped object supported by the stage and the transparent member, A step (ii) of irradiating light from the light source through the transparent member to cure the liquid film and form a cured layer on the molding surface, The film thickness of the liquid film in the step (i) is 5 μm or more and 250 μm or less, In the step (i), the amount of change A per unit time of the distance between the molding surface and the transparent member from the position where the distance between the molding surface and the transparent member is 0.50 mm until the liquid film is formed is 10 mm / sec or more and 50 mm / sec or less, the standby time B from forming the liquid film in the step (i) until irradiating light in the step (ii) is 4.0 sec or more and 10.0 sec or less, which is a method for manufacturing a three-dimensional shaped object.

Advantages of the Invention

[0007] According to the present disclosure, it is possible to provide a method for manufacturing a three-dimensional shaped object capable of obtaining a three-dimensional shaped object with high throughput and excellent impact resistance.

Brief Description of the Drawings

[0008] [Figure 1] It is a schematic diagram illustrating an optical shaping apparatus and a shaping method according to an embodiment of the present disclosure. [Figure 2] It is a schematic diagram illustrating the relationship between the distance and time between the stage and the transparent member and the relationship between the viscosity of the pseudoplastic fluid sandwiched between the stage and the transparent member and time. [Figure 3] It is a schematic diagram illustrating the state change (change in the dispersion state of particles) of the pseudoplastic fluid sandwiched between the stage and the transparent member. [Figure 4] It is a schematic diagram illustrating an optical shaping apparatus and a shaping method according to an embodiment of the present disclosure.

Embodiments for Carrying Out the Invention

[0009] Hereinafter, embodiments of the present disclosure (hereinafter also referred to as "the present embodiments") will be described. Note that the embodiments described below are merely one of the present embodiments, and the present disclosure is not limited to these embodiments.

[0010] In this disclosure, descriptions of numerical ranges such as "XX or greater and YY or less" or "XX to YY" mean a numerical range that includes the lower and upper limits, unless otherwise specified. When numerical ranges are described in steps, the upper and lower limits of each numerical range can be combined in any way.

[0011] When using a photocurable resin composition containing particles and applying a surface exposure stereolithography method based on the controlled liquid level method, there were challenges in achieving both high impact resistance and high throughput. According to the inventors' research, this is because the photocurable resin composition behaves as a pseudoplastic fluid whose viscosity decreases when shear stress is applied, based on the property that particles attract each other through weak interactions (bonding). In other words, in the controlled liquid level method, especially when fabricating at high speed, a large shear stress is applied to the photocurable resin composition sandwiched between the molded surface of the three-dimensional object and the transparent material. As a result, it was found that the impact resistance of the three-dimensional object decreases because a hardened layer is formed by light irradiation with the weak bonds between particles broken.

[0012] In response to these challenges, the inventors conducted further studies and, as a result, completed the present invention.

[0013] The manufacturing method of this embodiment includes steps (0) to (ii). Steps (0) to (ii) will be described below with reference to Figures 1 to 3.

[0014] Figure 1 is a schematic diagram illustrating an embodiment of a stereolithography apparatus and a molding method according to the present disclosure. In Figure 1, the stereolithography apparatus 15 comprises a light source 10, a stage 12 for forming a three-dimensional object 11, and a liquid tank 14 on which a transparent member 13 that transmits light from the light source 10 is laid on the bottom surface.

[0015] In step (0), the pseudoplastic fluid (photocurable resin composition) 17 contained in the liquid tank 14 is positioned between the molded surface 16 of the three-dimensional object 11 supported on the stage 12 and the transparent member 13, and is brought to a stationary state (a). In Figure 1, the molded surface 16 of the three-dimensional object 11 is not immersed in the pseudoplastic fluid 17 in state (a), but the molded surface 16 of the three-dimensional object 11 may be immersed in the pseudoplastic fluid 17.

[0016] In step (i), the stage 12 is lowered, gradually reducing the distance between the stage 12 and the transparent member 13, thereby forming a liquid film 18 made of pseudoplastic fluid 17 between the molded surface 16 of the three-dimensional object 11 supported by the stage 12 and the transparent member 13 (state (b) → (c)).

[0017] Finally, in step (ii), after a predetermined waiting period has elapsed, light is irradiated from the light source 10 through the transparent member 13 to harden the liquid film 18 and form a hardened layer 19 on the molded surface 16 (state (e)).

[0018] Figure 2 is a schematic diagram illustrating the relationship between the distance between the stage 12 and the transparent member 13 and time, and the relationship between the viscosity of the pseudoplastic fluid 17 sandwiched between the stage 12 and the transparent member 13 and time, corresponding to the process diagram in Figure 1.

[0019] In Figure 2, in state (a) of process (0), the stage 12 and the transparent member 13 are stationary, so no shear stress is applied to the pseudoplastic fluid 17 sandwiched between the stage 12 and the transparent member 13.

[0020] In step (i) of Figure 2, as the stage 12 is lowered to form the liquid film 18, the distance between the stage 12 and the transparent member 13 is reduced, and shear stress is applied to the pseudoplastic fluid 17 sandwiched between the stage 12 and the transparent member 13. As a result, the viscosity of the pseudoplastic fluid 17 sandwiched between the stage 12 and the transparent member 13 gradually decreases compared to the viscosity in the state where no shear stress is applied (a) (state (b)). Note that, as illustrated in Figure 2, when the distance between the stage 12 and the transparent member 13 is reduced at a constant speed, the shear stress applied to the pseudoplastic fluid 17 increases as the distance decreases. Therefore, the reduction in the viscosity of the pseudoplastic fluid 17 sandwiched between the stage 12 and the transparent member 13 becomes more pronounced as the distance between the stage 12 and the transparent member 13 is reduced. In other words, the viscosity of the pseudoplastic fluid 17 sandwiched between the stage 12 and the transparent member 13 is lowest when the distance between the stage 12 and the transparent member 13 reaches a distance corresponding to the thickness of the liquid film 18 (state (c)).

[0021] Finally, in step (ii) of Figure 2, the stage 12 and the transparent member 13 come to rest, and the shear stress applied to the liquid film 18 is reduced, so the viscosity of the liquid film 18 gradually recovers to the same viscosity as in step (0) when no shear stress is applied. After a predetermined waiting time, the viscosity of the liquid film 18 recovers to the same viscosity as in state (a) (state (d)), and then a hardened layer 19 is formed on the molded surface 16 by curing the liquid film 18 with light (state (e)).

[0022] Furthermore, Figure 3 is a schematic diagram illustrating the state change (change in particle dispersion state) of the pseudoplastic fluid 17 sandwiched between the stage 12 and the transparent member 13, corresponding to the process diagram in Figure 1. In Figure 3, in state (a) of process (0), particles 31 dispersed in the liquid resin (photocurable resin) 30 are attracted to each other through weak interactions (bonding) within the pseudoplastic fluid 17, forming continuous or intermittent first aggregates 32. Due to the formation of these first aggregates 32, the viscosity of the pseudoplastic fluid 17 is high in the static state.

[0023] In step (i) of Figure 3, the weak bonds between the particles 31 are gradually broken by the application of shear stress to the pseudoplastic fluid 17 as the stage 12 descends, causing the first aggregate 32 to break apart (state (b)). As the stage 12 is further descended to a distance corresponding to the thickness of the liquid film 18, the shear stress applied to the pseudoplastic fluid 17 increases, so the first aggregate 32 eventually disappears and the particles 31 are dispersed individually in the liquid resin 30 (state (c)).

[0024] Finally, in step (ii) of Figure 3, when the stage 12 comes to a standstill, the shear stress applied to the pseudoplastic fluid 17 is reduced, causing the particles 31 to form aggregates again via weak bonds. After a predetermined waiting time, the liquid resin 30 is cured by irradiating it with light in state (d), where the second aggregates 33 equivalent to state (a) have been regenerated. Curing then yields a cured product 35 with excellent impact resistance, in which aggregates of particles 31 (second aggregates 33) are dispersed in the cured resin 34 (state (e)).

[0025] <Embodiment 1> The following describes in detail the manufacturing method for a three-dimensional object according to one aspect of the present disclosure (Embodiment 1). However, the manufacturing method according to the present disclosure is not limited to this embodiment.

[0026] The characteristics of the manufacturing method in Embodiment 1 are: In process (i), the change A per unit time of the distance between the molded surface 16 and the transparent member 13 from a position where the distance between the molded surface 16 and the transparent member 13 is 0.50 mm until the liquid film 18 is formed (hereinafter sometimes simply referred to as "change A") is 0.20 mm / sec or more and less than 25 mm / sec. The waiting time B (hereinafter sometimes simply referred to as "waiting time B") from the formation of the liquid film 18 in step (i) to the irradiation of light in step (ii) is 0.04 sec or more and 10 sec or less, The change A and the waiting time B satisfy the relationship 0.2 ≤ B / A ≤ 5.0. That is the case.

[0027] By keeping the change amount A low, the viscosity change of the pseudoplastic fluid 17 associated with the application of shear stress is kept small, thus shortening the time it takes for the viscosity to recover in process (ii). As a result, even if the change amount A is low to a certain extent, the waiting time B can be shortened, making it possible to achieve both excellent impact strength and high manufacturing throughput.

[0028] The change amount A is 0.20 mm / sec or more and less than 25 mm / sec, preferably 0.30 mm / sec or more and less than 20 mm / sec, and more preferably 0.40 mm / sec or more and less than 10 mm / sec. A change amount A of 0.20 mm / sec or more makes it possible to achieve both excellent impact strength and high manufacturing throughput without requiring excessive time for molding. Furthermore, a change amount A of less than 25 mm / sec prevents excessive shear stress from being applied to the pseudoplastic fluid 17, and the viscosity recovers quickly after the formation of the liquid film 18, thus maintaining excellent impact strength.

[0029] The change amount A is the amount of change per unit time in the distance between the molded surface 16 and the transparent member 13 from the position where the distance between the molded surface 16 and the transparent member 13 is 0.50 mm until the liquid film 18 is formed. For example, if the distance between the molded surface 16 and the transparent member 13 changes from the position where the distance between the molded surface 16 and the transparent member 13 is 0.50 mm to the position where the liquid film 18 has a thickness of 0.10 mm in 2.0 seconds, the change amount A is calculated to be 0.40 ÷ 2.0 = 0.20 mm / sec. In this embodiment, the change amount A can be measured using known methods such as a laser displacement meter.

[0030] The waiting time B is 0.04 sec to 10 sec, preferably 0.05 sec to 9.0 sec, and more preferably 0.10 sec to 8.0 sec. By setting the waiting time B to 0.04 sec to 10 sec, it is possible to achieve both excellent impact strength and high manufacturing throughput.

[0031] Furthermore, the change amount A and the waiting time B satisfy the relationship 0.2 ≤ B / A ≤ 5.0, preferably 0.3 ≤ B / A ≤ 5.0, and more preferably 0.5 ≤ B / A ≤ 5.0. By satisfying the relationship 0.2 ≤ B / A ≤ 5.0 in addition to the change amount A and waiting time B satisfying their respective numerical ranges, it is possible to achieve both excellent impact strength and high manufacturing throughput without requiring excessive time for molding.

[0032] <Embodiment 2> The following describes in detail another method for manufacturing a three-dimensional object according to the above-mentioned embodiment of this disclosure (Embodiment 2). However, the manufacturing method according to this disclosure is not limited to this embodiment.

[0033] The characteristics of the manufacturing method in Embodiment 2 are: The change amount A is between 10 mm / sec and 50 mm / sec. Waiting time B must be between 4.0 seconds and 10.0 seconds. That is the case.

[0034] Even when the change in A is large and the viscosity change of the pseudoplastic fluid 17 due to the application of shear stress is large, extending the waiting time B ensures sufficient time for the viscosity to recover. As a result, even if the waiting time B is somewhat long, the change in A can be made large, thus achieving both excellent impact strength and high manufacturing throughput.

[0035] The change rate A is 10 mm / sec to 50 mm / sec, preferably 15 mm / sec to 47 mm / sec, and more preferably 25 mm / sec to 45 mm / sec. A change rate A of 10 mm / sec or more allows for both excellent impact strength and high manufacturing throughput without excessive time being required for molding. Furthermore, a change rate A of 50 mm / sec or less prevents excessive load from being placed on the molding surface and the three-dimensional object during molding, thus enabling both high dimensional accuracy and excellent impact strength.

[0036] The waiting time B is 4.0 seconds or more and 10.0 seconds or less, preferably 4.5 seconds or more and 9.0 seconds or less, and more preferably 5.0 seconds or more and 8.0 seconds or less. By having a waiting time B of 4.0 seconds or more, sufficient time can be secured for the viscosity to recover after the formation of the liquid film 18, thereby enabling excellent impact strength. Furthermore, by having a waiting time B of 10.0 seconds or less, it is preferable that excellent impact strength and high manufacturing throughput can be achieved without requiring excessive time for molding.

[0037] The following describes in detail the stereolithography apparatus 15, liquid film 18, three-dimensional object 11, and photocurable resin composition (pseudoplastic fluid 17) with reference to preferred embodiments.

[0038] <Stereolithography device 15> The stereolithography apparatus 15 disclosed herein comprises a light source 10, a stage 12 for forming a three-dimensional object 11, and a liquid tank 14 on which a transparent member 13 that transmits light from the light source 10 is laid on the bottom surface.

[0039] Using Figure 4, a stereolithography apparatus and manufacturing method according to one embodiment of this model will be described. In Figure 4, the stereolithography apparatus 15 comprises a light source 10, a stage 12 for forming and supporting a three-dimensional object 11, and a liquid tank 14 on which a transparent member 13 that transmits light from the light source 10 is laid on the bottom surface. The bottom surface of the stage 12 and the molding surface 16 of the three-dimensional object 11 are arranged to be substantially parallel to the bottom surface of the liquid tank 14 and can be raised and lowered along the drive shaft 42 by a movable mechanism 41. A control unit 43 is connected to the light source 10 and the movable mechanism 41 and controls them based on the slice data of the three-dimensional object 11.

[0040] First, the control unit 43 controls the movable mechanism 41 based on the slice data of the three-dimensional object 11 and lowers the stage 12 along the drive shaft 42, thereby forming a liquid film 18 of a predetermined thickness made of pseudoplastic fluid 17 between the molded surface 16 of the three-dimensional object 11 and the transparent member 13. Next, the control unit 43 controls the light source 10 to selectively irradiate the liquid film 18 with curing light 44 based on the slice data, so that a cured layer 19 having a desired pattern can be obtained, thereby forming a cured layer 19 on the molded surface 16. Then, the control unit 43 controls the stage 12 to raise it by a predetermined distance 45 along the drive shaft 42, thereby supplying the pseudoplastic fluid 17 to the region 46 where the cured layer 19 has been formed. Note that in the lower right diagram of Figure 4, the stage 12 is raised until the molded surface 16 of the three-dimensional object 11 is completely out of the pseudoplastic fluid 17, but the stage 12 may be raised so that the molded surface 16 of the three-dimensional object 11 does not come out of the pseudoplastic fluid 17. By repeating this series of operations, a three-dimensional object 11 is formed. When the molding is complete, the stage 12 is removed from the movable mechanism 41, and the three-dimensional object 11 held on the stage 12 is separated from the stage 12. The three-dimensional object 11 separated from the stage 12 is then subjected to post-processing such as cleaning, post-curing, surface smoothing, and cutting as needed to obtain the desired article.

[0041] The light source 10 of this disclosure is a surface exposure type capable of irradiating a pseudoplastic fluid 17 with planar patterned light. For example, a projector is preferred as the light source of this disclosure from the viewpoint of simplicity. Examples of projectors include LCD (transmissive liquid crystal) type, LCoS (reflective liquid crystal) type, and DLP (registered trademark, Digital Light Processing) type. The irradiation wavelength of the light emitted from the light source can be ultraviolet light, electron beams, X-rays, radiation, etc. Among these, ultraviolet light having a wavelength of 300 nm to 450 nm is preferred from an economic viewpoint.

[0042] After the hardened layer 19 is formed, the distance 45 by which the stage 12 rises is preferably 0.50 mm or more and 100 mm or less. More preferably, it is 0.70 mm or more and 80 mm or less, and even more preferably 1.0 mm or more and 50 mm or less. A stage rise distance of 0.50 mm or more is preferable because it allows for the smooth supply of the pseudoplastic fluid 17 to the region 46 where the hardened layer 19 is formed. Furthermore, a stage rise distance 45 of 100 mm or less is preferable because it makes it possible to achieve both excellent impact strength and high manufacturing throughput without requiring excessive time for molding.

[0043] The liquid tank 14 of this disclosure is not particularly limited in terms of material, as long as it has a wider width and area than the stage 12, is capable of accommodating the stage 12, and does not interact with the pseudoplastic fluid 17 in a way that causes swelling, corrosion, or the like.

[0044] A transparent member 13 is laid on the bottom surface of the liquid tank 14 in this disclosure. Preferably, the transparent member 13 has a light transmittance of at least 80% to the irradiated light, and more preferably 90% or more.

[0045] The material of the transparent member 13 in this disclosure can be any material that transmits curing light 44, and suitable materials include glass, transparent ceramics, silicone resin, acrylic resin, and fluororesin, which are transparent to ultraviolet and visible light. From the viewpoint of facilitating the separation of the transparent member 13 and the curing layer 19 after adhesion, it is particularly preferable to use silicone resin or fluororesin. These materials may also be used in combination.

[0046] Furthermore, the transparent member 13 of this disclosure may be made of a material having oxygen permeability. The opposite side of the transparent member 13 that is in contact with the pseudoplastic fluid 17 is in contact with an oxygen-containing gas such as air, and oxygen is supplied to the pseudoplastic fluid 17 through the transparent member 13, so that a thin layer containing a lot of oxygen is formed near the transparent member 13. In this thin layer, oxygen functions as a curing inhibitor, inhibiting curing by light irradiation, so that adhesion between the cured layer 19 and the transparent member 13 can be suppressed. In other words, the process of peeling the transparent member 13 and the cured layer 19 during molding is unnecessary, which is preferable as it contributes to further increasing the throughput of manufacturing in molding. Examples of materials having oxygen permeability include fluoropolymer films such as amorphous thermoplastic fluoropolymers such as TEFLON® AF (manufactured by DuPont), perfluoropolyethers (PFPE), especially crosslinked PFPE films, crosslinked silicone polymer films, etc.

[0047] The control unit 43 of this disclosure is a computer for controlling the operation of the stereolithography apparatus 15, and internally includes a CPU, ROM, RAM, I / O ports, etc. The ROM stores the operation program for the stereolithography apparatus 15. The program for executing various processes related to the molding method of this disclosure may be stored in the ROM, like other operation programs, but may also be loaded into RAM from an external source via a network. Alternatively, it may be loaded into RAM via a recording medium readable by the computer on which the program is stored.

[0048] Furthermore, the control unit 43 of this disclosure is connected to and controls various parts such as the movable mechanism 41 that moves the stage and the light source 10. In addition, various sensors such as a liquid level sensor and liquid temperature sensor attached to the liquid tank 14 and a load sensor provided in the movable mechanism 41 are connected to the control unit 43, and information necessary for control is input from each sensor. For illustrative purposes, only some of the elements connected to the control unit 43 are shown in Figure 4.

[0049] <Liquid film 18> The thickness of the liquid film 18 in step (i) affects the accuracy of the resulting three-dimensional object 11 (reproducibility of the three-dimensional shape data of the object to be fabricated). The thickness of the liquid film 18 is preferably 5 μm or more and 250 μm or less, more preferably 10 μm or more and 225 μm or less, and even more preferably 20 μm or more and 200 μm or less.

[0050] By having a liquid film thickness of 5 μm or more, excessive time is not required for molding, thus achieving both excellent impact strength and high manufacturing throughput. Furthermore, by having a liquid film thickness of 250 μm or less, excellent impact strength can be achieved while maintaining high molding accuracy.

[0051] The thickness of the liquid film 18 is controlled by the control unit 43 controlling the amount of drive of the drive shaft 42.

[0052] <3D object 11> After the three-dimensional object 11 of this disclosure is formed using a stereolithography apparatus 15, it is preferable to clean it as necessary to remove any unreacted photocurable resin remaining on its surface. As a cleaning agent, an alcohol-based organic solvent such as isopropyl alcohol or ethyl alcohol can be used. Alternatively, a ketone-based organic solvent such as acetone, ethyl acetate, or methyl ethyl ketone, or an aliphatic organic solvent such as terpenes may be used. After cleaning with a cleaning agent, post-curing by light irradiation or heat irradiation may be performed as necessary. Post-curing can cure any unreacted photocurable resin remaining on the surface and inside the three-dimensional object, suppressing stickiness on the surface of the object and improving various mechanical properties of the object.

[0053] Furthermore, the three-dimensional object 11 of this disclosure preferably includes a portion with a wall thickness of at least 3.5 mm, more preferably 4.0 mm or more, and even more preferably 5.0 mm or more. Here, the wall thickness of the three-dimensional object 11 corresponds to the line width of the pattern light irradiated during molding, and means the thickness of the three-dimensional object 11 in the horizontal direction relative to the hardened layer 19. The wall thickness of the three-dimensional object 11 can be measured using known methods such as a micrometer or an ultrasonic thickness gauge. When the wall thickness of the three-dimensional object 11 is 3.5 mm or more, it is preferable because sufficient shear stress is applied to the pseudoplastic fluid 17 constituting the liquid film 18 when forming the liquid film 18, and the manufacturing method of this disclosure functions effectively to achieve high impact resistance.

[0054] The three-dimensional object of this disclosure has a cross-sectional structure in which particles are unevenly dispersed. The particles form aggregates through weak bonds, and as a result, the three-dimensional object can achieve excellent impact strength due to its cross-sectional structure in which particles are unevenly dispersed. The cross-sectional structure of the three-dimensional object can be observed using a scanning electron microscope or an optical microscope after the fracture surface has been treated with staining or other methods as necessary.

[0055] One method for quantifying the non-uniform dispersion state of particles in the cross-sectional structure of a three-dimensional object is to measure the inter-particle distance from an image of the cross-sectional structure that has been binarized to allow for particle identification, and then quantify the distribution of the inter-particle distance. Specifically, the centroid coordinates are calculated for each particle extracted from the image, and a Voronoi tessellation process is performed using these as generating points to calculate each Voronoi region. For adjacent Voronoi regions, line segments are calculated connecting the centroid coordinates of the generating points, and the length of these line segments is used as the inter-particle distance to create a distribution. In this way, the distribution of inter-particle distances can be quantified using indicators such as the standard deviation.

[0056] <Photocurable resin composition (pseudoplastic fluid 17)> The photocurable resin composition disclosed herein contains a photocurable resin and particles. The photocurable resin composition disclosed herein is a pseudoplastic fluid that is liquid at room temperature (25°C). Here, a pseudoplastic fluid is a liquid substance whose viscosity decreases with the application of shear stress (has thixotropic properties).

[0057] The thixotropy coefficient of the pseudoplastic fluid of this disclosure is preferably 1.5 to 8.0, more preferably 2.0 to 7.0, and even more preferably 2.5 to 6.0. The thixotropy coefficient of this embodiment can be measured by the rotational rheometer method. Specifically, at a shear rate of 1 sec -1 and 100 sec -1 The viscosity of the pseudoplastic fluid at 25°C was measured, and the ratio of the two (1 sec) was calculated. -1 viscosity / 100sec -1 The thixotropy coefficient is calculated based on the viscosity of the solution.

[0058] If the thixotropy coefficient of the pseudoplastic fluid is less than 1.5, the tendency for particles to form aggregates via weak bonds in the static photocurable resin weakens, which may cause the manufacturing method of this disclosure to become ineffective. Furthermore, if the thixotropy coefficient of the pseudoplastic fluid is greater than 8.0, the viscosity of the static photocurable resin tends to increase significantly, which may reduce the workability during the manufacturing of three-dimensional objects.

[0059] The viscosity of a pseudoplastic fluid is determined by a shear rate of 1 sec. -1 Under conditions of 25°C, the viscosity is preferably 1.0 Pa·s to 20.0 Pa·s, more preferably 2.0 Pa·s to 18.0 Pa·s, and even more preferably 3.0 Pa·s to 15.0 Pa·s. Furthermore, the viscosity of the pseudoplastic fluid is determined at a shear rate of 100 sec. -1 Under conditions of 25°C, the pressure is preferably 0.2 Pa·s to 5.0 Pa·s, more preferably 0.5 Pa·s to 4.0 Pa·s, and even more preferably 1.0 Pa·s to 4.0 Pa·s.

[0060] [particle] The photocurable resin composition disclosed herein contains particles. The particles attract each other with weak bonding forces, forming aggregates of particles that can be reversibly dissociated by the application of shear stress, thus exhibiting thixotropy, a characteristic of pseudoplastic fluids.

[0061] While the type of particles is not particularly limited, rubber particles are preferable from the viewpoint of improving impact resistance. By incorporating rubber particles, the impact resistance of the three-dimensional object can be improved.

[0062] The type of rubber particles is not particularly limited. Preferred compositions for the rubber particles include, for example, butadiene rubber, styrene / butadiene copolymer rubber, acrylonitrile / butadiene copolymer rubber, saturated rubber obtained by hydrogenating or partially hydrogenating these diene rubbers, crosslinked butadiene rubber, isoprene rubber, chloroprene rubber, natural rubber, silicone rubber, ethylene / propylene / diene monomer ternary copolymer rubber, acrylic rubber, and acrylic / silicone composite rubber. The rubber particles are preferably composed of these compositions individually or in combination of two or more. In particular, from the viewpoint of improving impact resistance and suppressing the increase in viscosity of the pseudoplastic fluid, any of butadiene rubber, crosslinked butadiene rubber, styrene / butadiene copolymer rubber, acrylic rubber, and silicone / acrylic composite rubber are preferred, and either butadiene rubber or crosslinked butadiene rubber is more preferred.

[0063] The glass transition temperature of the rubber particle composition is preferably 0°C or lower, and more preferably -20°C or lower. If the glass transition temperature is higher than 0°C, it tends to be difficult to obtain an improved impact resistance effect. The glass transition temperature of the rubber particle composition can be determined, for example, by differential scanning calorimetry (DSC) or dynamic viscoelasticity measurement (DMA).

[0064] It is more preferable that the rubber particles have a core-shell structure. Specifically, it is preferable that the rubber particles have a structure in which the rubber particle composition forms a core, and the outside is covered with a shell made of a polymer of a radically polymerizable compound. By using rubber particles with a core-shell structure, the surface wettability of the rubber particles in the pseudoplastic fluid of this disclosure can be improved. As a result, the rubber particles function effectively in the three-dimensional molded object, resulting in excellent impact resistance. Furthermore, aggregates of rubber particles that can be reversibly bonded and dissociated are more easily formed via weak bonding forces acting between the shells, and the formation of these aggregates contributes to the development of even better impact resistance.

[0065] The polymer of the radical polymerizable compound that forms the shell is preferably graft polymerized onto the surface of the core via chemical bonds, and has a form that covers part or all of the core. Rubber particles having a core-shell structure in which the shell is graft polymerized onto the core can be formed by graft polymerizing the radical polymerizable compound in the presence of the core particles using known methods. For example, they can be produced by adding the radical polymerizable compound, which is a component of the shell, to latex particles dispersed in water, which can be prepared by emulsion polymerization, miniemulsion polymerization, suspension polymerization, seed polymerization, etc., and polymerizing them.

[0066] Furthermore, if there are no or very few reactive sites, such as ethylenically unsaturated groups, on the surface of the core that can be graft-polymerized by the shell, an intermediate layer containing reactive sites may be provided on the surface of the core particle before graft-polymerizing the shell. In other words, the form of rubber particles having a core-shell structure also includes a form in which the shell is provided on the core via an intermediate layer.

[0067] The monofunctional radical polymerizable compound used to form the shell can be appropriately selected considering its compatibility with the core composition and its dispersibility in a pseudoplastic fluid. For example, one or more materials from the examples of monofunctional radical polymerizable compounds described later may be used in combination. It is preferable that the shell contains a polymer of a monofunctional radical polymerizable compound having a (meth)acryloyl group, as this tends to result in good surface wettability of the rubber particles in a pseudoplastic fluid and the development of suitable thixotropy.

[0068] Furthermore, monofunctional radical polymerizable compounds and polyfunctional radical polymerizable compounds may be used in combination as radical polymerizable compounds for forming the shell. When a shell is formed using a polyfunctional radical polymerizable compound, the viscosity of the curable resin tends to decrease, making it easier to handle. On the other hand, if the content of the polyfunctional radical polymerizable compound is excessive, it tends to become difficult to obtain the effect of improving impact resistance by adding rubber particles having a core-shell structure. For this reason, the amount of polyfunctional radical polymerizable compound used for shell formation is preferably 0 to 40 parts by mass, more preferably 0 to 30 parts by mass, and particularly preferably 0 to 25 parts by mass, per 100 parts by mass of the radical polymerizable compound used for shell formation. The polyfunctional radical polymerizable compound used for shell formation can be appropriately selected considering its compatibility with the composition constituting the core and its surface wettability in a pseudoplastic fluid. One or more materials from the examples of polyfunctional radical polymerizable compounds described later may be used in combination.

[0069] In rubber particles having a core-shell structure, the mass ratio of core to shell is preferably 1 to 200 parts by mass of shell per 100 parts by mass of core, and more preferably 2 to 180 parts by mass of shell. If the mass ratio of core to shell is within the above range, it is possible to effectively improve impact resistance by including rubber particles. If the amount of shell is less than 1 part by mass, the surface wettability of the rubber particles in the pseudoplastic fluid is insufficient, making it difficult to obtain the effect of improving impact resistance. Also, if the amount of shell is greater than 200 parts by mass, dispersibility in the curable resin is excellent, but the rubber particles are thickly covered by the shell, which tends to reduce the effect of improving impact resistance by the rubber component. Therefore, in order to obtain sufficient impact resistance, it is necessary to add a large amount of rubber particles, which tends to increase the viscosity of the curable resin and make it difficult to handle.

[0070] The rubber particles preferably have an average particle diameter of 20 nm to 10 μm, and more preferably 50 nm to 5 μm. If the average particle diameter is less than 20 nm, the viscosity of the pseudoplastic fluid increases with the addition of rubber particles, and excessive interaction between rubber particles occurs due to the increase in the specific surface area of ​​the rubber particles, which tends to cause a decrease in the heat resistance and impact resistance of the three-dimensional molded object. Furthermore, if the average particle diameter is greater than 10 μm, the rubber particles become difficult to disperse in the pseudoplastic fluid, and the effect of improving impact resistance by adding rubber particles tends to decrease.

[0071] In this embodiment, the average particle size of the rubber particles is the arithmetic (number) mean particle size, which can be measured using dynamic light scattering. For example, the rubber particles can be dispersed in a suitable organic solvent and measured using a particle size analyzer.

[0072] Furthermore, the gel fraction of the rubber particles is preferably 5% or more. If the gel fraction is less than 5%, both impact resistance and heat resistance tend to decrease. The gel fraction can be determined by the following procedure. Immerse dried rubber particles W1 [g] in a sufficient amount of toluene and leave at room temperature for 7 days. Then, remove the solids by centrifugation or the like and dry them at 100°C for 2 hours, and measure the amount of solids obtained after drying. If the mass of the solids obtained after drying is W2 [g], the gel fraction can be calculated using the following formula. Gel fraction (%) = W2 / W1 × 100

[0073] The rubber particle content in the photocurable resin of this disclosure is preferably 5 parts by mass or more and 25 parts by mass or less, and more preferably 6 parts by mass or more and 20 parts by mass or less, per 100 parts by mass of the total amount of the radical polymerizable compound. If the rubber particle content is less than 5 parts by mass, it tends to be difficult to obtain the effect of improving impact resistance by adding rubber particles. Also, if the rubber particle content is more than 25 parts by mass, the viscosity of the resulting photocurable resin tends to increase significantly, and the workability during the manufacture of three-dimensional molded objects tends to decrease.

[0074] [Photocurable resin] The photocurable resin preferably contains a radical polymerizable compound, and more preferably a radical polymerizable compound. Examples of radical polymerizable compounds include monofunctional radical polymerizable compounds and polyfunctional radical polymerizable compounds such as polyfunctional urethane (meth)acrylate oligomers. In this specification, the total amount of radical polymerizable compounds refers to the sum of the monofunctional radical polymerizable compound and the polyfunctional radical polymerizable compound. The content of the radical polymerizable compound is preferably 45 parts by mass or more and 95 parts by mass or less per 100 parts by mass of the total amount of the photocurable resin. More preferably, it is 50 parts by mass or more and 92 parts by mass or less, and even more preferably 55 parts by mass or more and 90 parts by mass or less. By having the content of the radical polymerizable compound within the above range, it is possible to achieve excellent impact resistance of the three-dimensional molded object.

[0075] [Polyfunctional urethane (meth)acrylate oligomer] The photocurable resins disclosed herein preferably contain a polyfunctional urethane (meth)acrylate oligomer having at least one (meth)acryloyl group and at least two urethane groups in the molecule. In this specification, (meth)acryloyl group means acryloyl group or methacryloyl group.

[0076] The content of the polyfunctional urethane (meth)acrylate oligomer is preferably 15 parts by mass or more and 60 parts by mass or less per 100 parts by mass of the total amount of the radical polymerizable compound. More preferably, it is 20 parts by mass or more and 55 parts by mass or less, and even more preferably 25 parts by mass or more and 50 parts by mass or less. By having the polyfunctional urethane (meth)acrylate oligomer content within the above range, it is possible to achieve excellent impact resistance of three-dimensional molded objects without excessively increasing the viscosity of the photocurable resin and causing a decrease in workability. If the content of polyfunctional urethane (meth)acrylate oligomer is less than 15 parts by mass, the impact resistance tends to decrease significantly. Also, if the content of polyfunctional urethane (meth)acrylate oligomer is more than 60 parts by mass, the viscosity of the resin composition increases significantly, making it difficult to use as a suitable molding material for stereolithography.

[0077] For example, the following compounds A) to C) can be used as polyfunctional urethane (meth)acrylate oligomers. Among these, compound C) is preferred from the viewpoint of achieving high impact resistance.

[0078] a) Compounds obtained by reacting a hydroxyl group-containing (meth)acrylate compound with a polyvalent isocyanate compound. a) Compounds obtained by reacting an isocyanate group-containing (meth)acrylate compound with a polyol compound. (c) A compound obtained by reacting a polyurethane having multiple isocyanate groups, which is formed by reacting a polyvalent isocyanate compound with a polyol compound, with a hydroxyl group-containing (meth)acrylate compound. Examples of hydroxyl group-containing (meth)acrylate compounds include hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and 6-hydroxyhexyl (meth)acrylate, 2-hydroxyethyl acryloyl phosphate, 2-(meth)acryloyloxyethyl-2-hydroxypropyl phthalate, caprolactone-modified 2-hydroxyethyl (meth)acrylate, dipropylene glycol (meth)acrylate, fatty acid-modified glycidyl (meth)acrylate, and polyethylene glycol mono(meth)acrylate. Examples include methyl acrylate, polypropylene glycol mono(meth)acrylate, 2-hydroxy-3-(meth)acryloyloxypropyl(meth)acrylate, glycerin di(meth)acrylate, 2-hydroxy-3-acryloyloxypropyl methacrylate, pentaerythritol tri(meth)acrylate, caprolactone-modified pentaerythritol tri(meth)acrylate, ethylene oxide-modified pentaerythritol tri(meth)acrylate, dipentaerythritol penta(meth)acrylate, caprolactone-modified dipentaerythritol penta(meth)acrylate, and ethylene oxide-modified dipentaerythritol penta(meth)acrylate. These hydroxyl group-containing (meth)acrylate compounds may be used individually or in combination of two or more.

[0079] Examples of polyvalent isocyanate compounds include aromatic polyisocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate, polyphenylmethane polyisocyanate, modified diphenylmethane diisocyanate, xylylene diisocyanate, tetramethylxylylene diisocyanate, phenylene diisocyanate, naphthalene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, and lysine diisocyanate. Examples include aliphatic polyisocyanates such as cyanates and lysine triisocyanate, alicyclic polyisocyanates such as hydrogenated diphenylmethane diisocyanate, hydrogenated xylylene diisocyanate, isophorone diisocyanate, norbornene diisocyanate, and 1,3-bis(isocyanatomethyl)cyclohexane, or trimer compounds or polymer compounds of these polyisocyanates, allophanate-type polyisocyanates, biuret-type polyisocyanates, and aqueous-dispersible polyisocyanates. These polyvalent isocyanate compounds may be used individually or in combination of two or more.

[0080] Examples of polyol compounds include polycarbonate polyols, polyester polyols, polyether polyols, polyolefin polyols, polybutadiene polyols, (meth)acrylic polyols, and polysiloxane polyols. Among these, polycarbonate polyols and polyester polyols are preferred, and polycarbonate polyols are more preferred, from the viewpoint of achieving both high impact resistance and high elastic modulus. These polyol compounds may be used individually or in combination of two or more types.

[0081] Examples of polycarbonate-based polyols include reaction products of polyhydric alcohols and phosgene, and ring-opening polymers of cyclic carbonate esters (such as alkylene carbonates). Note that polycarbonate-based polyols are simply compounds having a carbonate bond within the molecule and a hydroxyl group at one end; they may also have an ester bond in addition to the carbonate bond.

[0082] Examples of polyhydric alcohols include ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, trimethylene glycol, 1,4-tetramethylenediol, 1,3-tetramethylenediol, 2-methyl-1,3-trimethylenediol, 1,5-pentamethylenediol, neopentyl glycol, 1,6-hexamethylenediol, 3-methyl-1,5-pentamethylenediol, 2,4-diethyl-1,5-pentamethylenediol, glycerin, trimethylolpropane, trimethylolethane, cyclohexanediols (such as 1,4-cyclohexanediol), bisphenols (such as bisphenol A), and sugar alcohols (such as xylitol and sorbitol).

[0083] Examples of alkylene carbonates include ethylene carbonate, trimethylene carbonate, tetramethylene carbonate, and hexamethylene carbonate.

[0084] Examples of polyester polyols include condensation polymers of polyhydric alcohols and polyhydric carboxylic acids, ring-opening polymers of cyclic esters (lactones), and reaction products of three components: polyhydric alcohols, polyhydric carboxylic acids, and cyclic esters.

[0085] Examples of polyhydric alcohols include the polyhydric alcohols exemplified in the description of polycarbonate-based polyols.

[0086] Examples of polycarboxylic acids include aliphatic dicarboxylic acids such as malonic acid, maleic acid, fumaric acid, succinic acid, glutaric acid, adipic acid, suberic acid, azelaic acid, sebacic acid, and dodecanedionic acid; alicyclic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid; and aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, orthophthalic acid, 2,6-naphthalenedicarboxylic acid, paraphenylenedicarboxylic acid, and trimellitic acid.

[0087] Examples of the cyclic ester include propiolactone, β-methyl-δ-valerolactone, ε-caprolactone, and the like.

[0088] From the viewpoint of improving impact resistance, the polycarbonate polyol and the polyester polyol preferably contain structures represented by the following general formulas (i) and (ii), respectively.

[0089]

Chemical formula

[0090] In general formulas (i) and (ii), R1 and R2 are each a hydrocarbon group containing an alkylene group having 1 or more and 18 or less carbon atoms, independent of each other, and n is 2 or more and 50 or less. R1 and R2 are preferably hydrocarbon groups containing an alkylene group having 4 or more and 9 or less carbon atoms. Examples of R1 and R2 include any one selected from the group consisting of -(CH2) m -(m = 1 or more and 18 or less), -(CH2) h C(CH3)2(CH2) i -(h = 0 or more and 5 or less, i = 0 or more and 15 or less), -(CH2) j CH(CH3)(CH2) k -(j = 0 or more and 16 or less, k = 0 or more and 16 or less), or a combination of two or more thereof. Among them, those in which each of R1 and R2 contains -(CH2) m -(m = 4 or more and 9 or less) are particularly preferred. Further, R1 and R2 may contain an aromatic hydrocarbon group in addition to the alkylene group.

[0091] Examples of polyether polyols include alkylene-containing polyether polyols such as polyethylene glycol, polypropylene glycol, polytetramethylene glycol, and polyhexamethylene glycol, as well as random or block copolymers of these polyalkylene glycols. In particular, from the viewpoint of improving impact resistance, it is preferable to contain at least one selected from polypropylene glycol, polytetramethylene glycol, and polyhexamethylene glycol, and it is more preferable to contain polypropylene glycol and polytetramethylene glycol.

[0092] The weight-average molecular weight of the polyfunctional urethane (meth)acrylate oligomer is preferably 1,000 to 60,000, and more preferably 2,000 to 50,000. A weight-average molecular weight of 1,000 or more is preferable because the impact resistance of the cured product tends to increase significantly with decreasing crosslinking density. If the weight-average molecular weight is greater than 60,000, the significant increase in viscosity of the photocurable resin due to the addition tends to cause a decrease in workability during the manufacture of three-dimensional molded objects.

[0093] The weight-average molecular weight (Mw) of the polyfunctional urethane (meth)acrylate oligomer is the weight-average molecular weight converted to the standard polystyrene molecular weight, and was measured using high-performance liquid chromatography (Tosoh Corporation, high-performance GPC instrument "HLC-8220GPC") with a Shodex GPCLF-804 column (exclusion limit molecular weight: 2 × 10⁶). 6 Separation range: 300~2×10 6 The measurement is performed by using two of these in series.

[0094] Furthermore, it is preferable that the radical polymerizable functional group equivalent of the polyfunctional urethane (meth)acrylate oligomer is 400 g / eq or more. In this embodiment, the radical polymerizable functional group equivalent is a value indicating the molecular weight per radical polymerizable functional group. When the radical polymerizable functional group equivalent is less than 400 g / eq, impact resistance tends to decrease as the crosslinking density increases.

[0095] [Monofunctional radical polymerizable compounds] The photocurable resin disclosed herein preferably contains a monofunctional radical polymerizable compound, which is a compound having only one radical polymerizable functional group in its molecule.

[0096] Examples of radically polymerizable functional groups include ethylenically unsaturated groups. Specific examples of ethylenically unsaturated groups include (meth)acryloyl groups and vinyl groups. For compounds that undergo cyclization polymerization using two vinyl groups within the molecule, the two vinyl groups undergoing cyclization polymerization are considered as a single radically polymerizable functional group.

[0097] Examples of monofunctional radical polymerizable compounds having a (meth)acryloyl group include monofunctional (meth)acrylamide compounds and monofunctional (meth)acrylate compounds.

[0098] Examples of monofunctional (meth)acrylamide compounds include (meth)acrylamide, N-methyl(meth)acrylamide, N-isopropyl(meth)acrylamide, N-tert-butyl(meth)acrylamide, N-phenyl(meth)acrylamide, N-methylol(meth)acrylamide, N,N-diacetone(meth)acrylamide, N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N,N-dipropyl(meth)acrylamide, N,N-dibutyl(meth)acrylamide, N-(meth)acryloylmorpholine, N-(meth)acryloylpiperidine, and N-[3-(dimethylamino)propyl]acrylamide.

[0099] Examples of monofunctional (meth)acrylate compounds include methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, i-octyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, adamantyl (meth)acrylate, and 2-hydroxyethyl (meth)acrylate. )Acrylate, 2-Hydroxypropyl (meth)acrylate, 2-Hydroxybutyl (meth)acrylate, 4-Hydroxybutyl (meth)acrylate, Glycidyl (meth)acrylate, 3-Methyl-3-Oxetanyl-methyl (meth)acrylate, Tetrahydrofurfuryl (meth)acrylate, Phenylglycidyl (meth)acrylate, Dimethylaminomethyl (meth)acrylate, Phenylcellosolve (meth)acrylate, Dicyclopentenyl (meth)acrylate, Dicyclopentenyloxyethyl (meth)acrylate, Bife Nyl (meth)acrylate, 2-hydroxyethyl (meth)acryloyl phosphate, phenyl (meth)acrylate, phenoxyethyl (meth)acrylate, phenoxypropyl (meth)acrylate, benzyl (meth)acrylate, butoxytriethylene glycol (meth)acrylate, 2-ethylhexyl polyethylene glycol (meth)acrylate, nonylphenyl polypropylene glycol (meth)acrylate, methoxydipropylene glycol (meth)acrylate, glycidyl (meth)acrylate, glycerol (meth)acrylate )Acrylate, trifluoromethyl (meth)acrylate, trifluoroethyl (meth)acrylate, tetrafluoropropyl (meth)acrylate, octafluoropentyl acrylate, polyethylene glycol (meth)acrylate, polypropylene glycol (meth)acrylate, allyl (meth)acrylate, epichlorohydrin-modified butyl (meth)acrylate, epichlorohydrin-modified phenoxy (meth)acrylate, ethylene oxide (EO)-modified phthalate (meth)acrylate, EO-modified succinate (meth)acrylate,Examples include caprolactone-modified 2-hydroxyethyl (meth)acrylate, N,N-dimethylaminoethyl (meth)acrylate, N,N-diethylaminoethyl (meth)acrylate, morpholino (meth)acrylate, EO-modified phosphate (meth)acrylate, 2-(allyloxymethyl)methyl acrylate (product name: AO-MA, manufactured by Nippon Shokubai Co., Ltd.), monofunctional (meth)acrylates having an imide group (product name: M-140, manufactured by Toagosei Co., Ltd.), and monofunctional (meth)acrylates having a siloxane structure.

[0100] Examples of monofunctional radical polymerizable compounds having ethylenically unsaturated groups other than (meth)acryloyl groups include styrene derivatives such as styrene, vinyltoluene, α-methylstyrene, chlorostyrene, styrenesulfonic acid and its salts; maleimides such as maleimide, methylmaleimide, ethylmaleimide, propylmaleimide, butylmaleimide, hexylmaleimide, octylmaleimide, dodecylmaleimide, stearylmaleimide, phenylmaleimide, and cyclohexylmaleimide; vinyl esters such as vinyl acetate, vinyl propionate, vinyl pivalate, vinyl benzoate, and vinyl cinnamate; vinyl cyanide compounds such as (meth)acrylonitrile; and N-vinyl compounds such as N-vinylpyrrolidone, N-vinyl-ε-caprolactam, N-vinylimidazole, N-vinylmorpholine, N-vinylacetamide, and vinylmethyloxazolidinone.

[0101] These monofunctional radical polymerizable compounds may be used individually or in combination of two or more.

[0102] From the viewpoint of accelerating the curing speed, it is preferable to include at least one compound selected from the group consisting of monofunctional acrylamide compounds, monofunctional acrylate compounds, and N-vinyl compounds as the monofunctional radical polymerizable compound. In particular, it is preferable to include a monofunctional acrylamide compound or an N-vinyl compound. Furthermore, since it tends to be easier to achieve both high heat resistance and high impact resistance, monofunctional acrylamide compounds are preferably compounds having a cyclic structure such as acryloylmorpholine and phenylacrylamide. In addition, N-vinyl compounds are preferably compounds having a cyclic structure such as N-vinylpyrrolidone, N-vinyl-ε-caprolactam, N-vinylimidazole, N-vinylmorpholine, and vinylmethyloxazolidinone.

[0103] When using an N-vinyl compound as a monofunctional radical polymerizable compound, the content of N-vinyl groups is preferably 80 mol% or less, and more preferably 75 mol% or less, relative to the total amount of radical polymerizable functional groups in the photocurable resin. N-vinyl compounds are difficult to homopolymerize, and by setting the content of N-vinyl groups to 80 mol% or less relative to the total amount of radical polymerizable functional groups, curing is significantly accelerated, making it suitable for use as a molding material in stereolithography, thus making it preferable.

[0104] When using a monofunctional methacrylate compound as a monofunctional radical polymerizable compound, it is preferable that the methacrylate group content is 60 mol% or less relative to the total amount of radical polymerizable functional groups in the photocurable resin, as this tends to result in a faster curing rate. More preferably, the methacrylate group content is 40 mol% or less, and even more preferably, 20 mol% or less or 0 mol%. Here, the monofunctional methacrylate compound includes compounds having substituted methacrylate groups such as methyl 2-(allyloxymethyl)acrylate (product name: AO-MA, manufactured by Nippon Shokubai), and the methacrylate group includes a substituted methacrylate group. If the methacrylate group content is greater than 60 mol%, the curing rate tends to decrease, and the material tends to become unsuitable as a molding material for stereolithography.

[0105] The content of the monofunctional radical polymerizable compound having an alicyclic hydrocarbon group is preferably 50 parts by mass or less, more preferably 40 parts by mass or less, and even more preferably 30 parts by mass or less, based on 100 parts by mass of the total amount of radical polymerizable compounds. If the content of the monofunctional radical polymerizable compound having an alicyclic hydrocarbon group is greater than 50 parts by mass, the impact resistance tends to decrease significantly. In addition, when the particles of this disclosure are added, the viscosity of the photocurable resin tends to increase, and the workability during the manufacture of three-dimensional molded objects tends to decrease.

[0106] Examples of monofunctional radical polymerizable compounds having alicyclic hydrocarbon groups include isobornyl (meth)acrylate, dicyclopentanyl (meth)acrylate, dicyclopentenyl (meth)acrylate, cyclohexyl (meth)acrylate, 4-t-butylcyclohexyl acrylate, 3,3,5-trimethylcyclohexyl acrylate, 2-methyl-2-adamantyl (meth)acrylate, and 2-ethyl-2-adamantyl (meth)acrylate.

[0107] The glass transition temperature (Tg) of a homopolymer or copolymer of a monofunctional radical polymerizable compound is preferably 50°C or higher, and more preferably 60°C or higher. The Tg of the copolymer can be determined by the FOX formula (formula (I) below). The unit of Tg is absolute temperature. 1 / Tg = Σ(W i / Tg i )···Formula (I)

[0108] In the above equation (I), W i This represents the mass ratio of each monofunctional radical polymerizable compound in the copolymer. i The glass transition temperature (Tg) of each homopolymer of the monofunctional radical polymerizable compound is the glass transition temperature (Tg) of each homopolymer of the various radical polymerizable compounds used in the FOX formula. iFor each polymer, generally known values ​​can be used. Alternatively, the polymers can be actually fabricated, and experimental values ​​obtained by differential scanning calorimetry (DSC) or dynamic viscoelasticity measurement (DMA) can be used.

[0109] The content of the monofunctional radical polymerizable compound is preferably 30 parts by mass or more and 75 parts by mass or less, more preferably 35 parts by mass or more and 70 parts by mass or less, per 100 parts by mass of the total amount of radical polymerizable compounds. A content of 30 parts by mass or more and 75 parts by mass or less of the monofunctional radical polymerizable compound is preferred because it tends to increase impact resistance.

[0110] [Polyfunctional radical polymerizable compounds other than polyfunctional urethane (meth)acrylate oligomers] The photocurable resin of this disclosure may contain one or more polyfunctional radical polymerizable compounds having at least two radical polymerizable functional groups in the molecule, other than the polyfunctional urethane (meth)acrylate oligomer described above.

[0111] Examples of radically polymerizable functional groups include ethylenically unsaturated groups. Specific examples of ethylenically unsaturated groups include (meth)acryloyl groups and vinyl groups. For compounds that undergo cyclization polymerization using two vinyl groups within the molecule, the two vinyl groups undergoing cyclization polymerization are considered as a single radically polymerizable functional group.

[0112] Examples of polyfunctional radical polymerizable compounds included in the photocurable resin of this disclosure include polyfunctional (meth)acrylate compounds, vinyl ether group-containing (meth)acrylate compounds, polyfunctional (meth)acryloyl group-containing isocyanurate compounds, polyfunctional (meth)acrylamide compounds, polyfunctional maleimide compounds, polyfunctional vinyl ether compounds, and polyfunctional aromatic vinyl compounds. Among these, polyfunctional (meth)acryloyl group-containing isocyanurate compounds are preferred from the viewpoint of improving heat resistance while maintaining high impact resistance.

[0113] Examples of polyfunctional (meth)acrylate compounds include ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, nonaethylene glycol di(meth)acrylate, 1,3-butanediol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,5-pentanediol di(meth)acrylate, dimethylol tricyclodecane di(meth)acrylate, trimethylolpropane tri(meth)acrylate, neopentyl glycol di(meth)acrylate, and 1,6-hexa Di(meth)acrylate, neopentyl glycol di(meth)acrylate, hydroxypivalate ester, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, ditrimethylolpropane tetraacrylate, dipentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, 2-hydroxy-3-methacrylate, di(meth)acrylate of ε-caprolactone adduct of neopentyl glycol hydroxypivalate (e.g., manufactured by Nippon Kayaku Co., Ltd., KAYARAD Examples include HX-220, HX-620, etc., di(meth)acrylates of EO adducts of bisphenol A, polyfunctional (meth)acrylates having fluorine atoms, polyfunctional (meth)acrylates having a siloxane structure, polycarbonate diol di(meth)acrylate, polyester di(meth)acrylate, polyethylene glycol di(meth)acrylate, polyether-based polyfunctional urethane (meth)acrylate, polyolefin-based polyfunctional urethane (meth)acrylate, and (meth)acrylic-based polyfunctional urethane (meth)acrylate.

[0114] Examples of vinyl ether group-containing (meth)acrylate compounds include 2-vinyloxyethyl (meth)acrylate, 4-vinyloxybutyl (meth)acrylate, 4-vinyloxycyclohexyl (meth)acrylate, 2-(vinyloxyethoxy)ethyl (meth)acrylate, and 2-[2-(2-vinyloxyethoxy)ethoxy]ethyl (meth)acrylate.

[0115] Examples of polyfunctional (meth)acryloyl group-containing isocyanurate compounds include tri(acryloyloxyethyl)isocyanurate, tri(methacryloyloxyethyl)isocyanurate, and ε-caprolactone-modified tris-(2-acryloxyethyl)isocyanurate.

[0116] Examples of polyfunctional (meth)acrylamide compounds include N,N'-methylenebisacrylamide, N,N'-ethylenebisacrylamide, N,N'-(1,2-dihydroxyethylene)bisacrylamide, N,N'-methylenebismethacrylamide, and N,N',N''-triacryloyldiethylenetriamine.

[0117] Examples of polyfunctional maleimide compounds include 4,4'-diphenylmethanebismaleimide, m-phenylenebismaleimide, bisphenol A diphenyl etherbismaleimide, 3,3'-dimethyl-5,5'-diethyl-4,4'-diphenylmethanebismaleimide, 4-methyl-1,3-phenylenebismaleimide, and 1,6-bismaleimide-(2,2,4-trimethyl)hexane.

[0118] Examples of polyfunctional vinyl ether compounds include ethylene glycol divinyl ether, diethylene glycol divinyl ether, polyethylene glycol divinyl ether, propylene glycol divinyl ether, butylene glycol divinyl ether, hexanediol divinyl ether, bisphenol A alkylene oxide divinyl ether, bisphenol F alkylene oxide divinyl ether, trimethylolpropane trivinyl ether, ditrimethylolpropane tetravinyl ether, glycerin trivinyl ether, pentaerythritol tetravinyl ether, dipentaerythritol pentavinyl ether, and dipentaerythritol hexanyl ether.

[0119] Examples of polyfunctional aromatic vinyl compounds include divinylbenzene.

[0120] When the photocurable resin disclosed herein contains a polyfunctional radical polymerizable compound having a radical polymerizable functional group equivalent of less than 300 g / eq, its content is preferably 25 parts by mass or less, more preferably 20 parts by mass or less, and even more preferably 15 parts by mass or less, per 100 parts by mass of the total amount of the radical polymerizable compound. If the content of the polyfunctional radical polymerizable compound having a radical polymerizable functional group equivalent of less than 300 g / eq is greater than 25 parts by mass, the crosslinking density of the three-dimensional molded object increases, and at the same time, the crosslinking density tends to become non-uniform. As a result, when an external impact is applied, areas of stress concentration may occur, and the expected effect of improving impact resistance by particle addition may not be obtained, resulting in impact strength being similar to that of the conventional technology.

[0121] When the photocurable resin disclosed herein contains a polyfunctional radical polymerizable compound having a radical polymerizable functional group equivalent of 300 g / eq or more, its content is preferably 40 parts by mass or less, more preferably 35 parts by mass or less, per 100 parts by mass of the total amount of the radical polymerizable compound. If the content of the polyfunctional radical polymerizable compound having a radical polymerizable functional group equivalent of 300 g / eq or more is greater than 40 parts by mass, the heat resistance decreases, and at the same time, the elastic modulus of the resulting cured product tends to decrease.

[0122] [Photoradical polymerization initiator] The photocurable resin composition disclosed herein preferably contains a photoradical polymerization initiator.

[0123] Photo-radical polymerization initiators are mainly classified into intramolecular cleavage type and hydrogen abstraction type. In intramolecular cleavage type photo-radical polymerization initiators, absorption of light of a specific wavelength breaks bonds at specific sites. Radicals are then generated at the broken sites, which act as polymerization initiators, initiating the polymerization of radical polymerizable compounds such as ethylenically unsaturated compounds containing (meth)acryloyl groups. On the other hand, in the case of hydrogen abstraction type initiators, absorption of light of a specific wavelength leads to an excited state, and these excited species undergo hydrogen abstraction reactions from surrounding hydrogen donors, generating radicals that act as polymerization initiators, initiating the polymerization of radical polymerizable compounds.

[0124] Known intramolecular cleavage-type photoradical polymerization initiators include alkylphenone-based photoradical polymerization initiators, acylphosphine oxide-based photoradical polymerization initiators, and oxime ester-based photoradical polymerization initiators. These are of the type in which a bond adjacent to the carbonyl group undergoes α-cleavage to generate a radical species.

[0125] Alkylphenone-based photoradical polymerization initiators include benzylmethyl ketal-based photoradical polymerization initiators, α-hydroxyalkylphenone-based photoradical polymerization initiators, and aminoalkylphenone-based photoradical polymerization initiators. Specific compounds include, for example, the following compounds (with examples of trade names in parentheses): Examples of benzylmethyl ketal-based photoradical polymerization initiators include 2,2'-dimethoxy-1,2-diphenylethane-1-one (Irgacure® 651, manufactured by BASF), and examples of α-hydroxyalkylphenone-based photoradical polymerization initiators include 2-hydroxy-2-methyl-1-phenylpropane-1-one (Darocure 1173, manufactured by BASF), 1-hydroxycyclohexylphenyl ketone (Irgacure 184, manufactured by BASF), and 1-[4-(2-hydroxyethoxy)phenyl]-2-hydroxy-2-methyl-1-propane-1-one (Irgacure 29 Examples include 59 (manufactured by BASF), 2-hydroxy-1-{4-[4-(2-hydroxy-2-methylpropionyl)benzyl]phenyl}-2-methylpropan-1-one (Irgacure 127, manufactured by BASF), and aminoalkylphenone-based photoradical polymerization initiators include, but are not limited to, 2-methyl-1-(4-methylthiophenyl)-2-morpholinopropan-1-one (Irgacure 907, manufactured by BASF) and 2-benzylmethyl-2-dimethylamino-1-(4-morpholinophenyl)-1-butanone (Irgacure 369, manufactured by BASF).

[0126] Examples of acylphosphine oxide-based photoradical polymerization initiators include, but are not limited to, 2,4,6-trimethylbenzoyldiphenylphosphine oxide (Lucilin TPO, manufactured by BASF) and bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide (Irgacure 819, manufactured by BASF).

[0127] Examples of oxime ester-based photoradical polymerization initiators include (2E)-2-(benzoyloxyimino)-1-[4-(phenylthio)phenyl]octan-1-one (Irgacure OXE-01, manufactured by BASF), but are not limited to these.

[0128] Examples of hydrogen abstraction-type radical polymerization initiators include, but are not limited to, anthraquinone derivatives such as 2-ethyl-9,10-anthraquinone and 2-t-butyl-9,10-anthraquinone, and thioxanthone derivatives such as isopropylthioxanthone and 2,4-diethylthioxanthone.

[0129] These photoradical polymerization initiators may be used individually or in combination of two or more types. They may also be used in combination with the thermal radical polymerization initiators described later.

[0130] The amount of photoradical polymerization initiator added is preferably 0.1 parts by mass to 15 parts by mass, and more preferably 0.1 parts by mass to 10 parts by mass, per 100 parts by mass of the radical polymerizable compound in the photocurable resin. If the amount of photoradical polymerization initiator is too low, polymerization tends to be insufficient. If an excessive amount of polymerization initiator is added, the molecular weight will not increase, which may reduce heat resistance or impact resistance.

[0131] [Other ingredients] The photocurable resin compositions disclosed herein may contain other components, provided that they do not impair the purpose or effects of the disclosure.

[0132] Other components may include property modifiers, photosensitizers, polymerization initiators, polymerization inhibitors, leveling agents, wettability modifiers, surfactants, plasticizers, ultraviolet absorbers (UVA), light stabilizers (HALS), silane coupling agents, inorganic fillers, pigments, dyes, antioxidants, flame retardants, thickeners, and defoamers to impart desired properties to the cured product.

[0133] The amount of other components added is preferably 0.01 parts by mass or more and 25 parts by mass or less per 100 parts by mass of the total amount of photocurable resin. More preferably, it is 0.05 parts by mass or more and 20 parts by mass or less. Within this range, the desired physical properties can be imparted to the three-dimensional molded object or the photocurable resin without significantly reducing the impact resistance of the resulting cured product.

[0134] For example, as a property modifier to impart desired physical properties to a cured product, resins such as epoxy resin, polyurethane, polychloroprene, polyester, polysiloxane, petroleum resin, xylene resin, ketone resin, cellulose resin, or polycarbonate, modified polyphenylene ether, polyamide, polyacetal, polyethylene terephthalate, polybutylene terephthalate, ultra-high molecular weight polyethylene, polyphenylsulfone, polysulfone, polyarylate, polyetherimide, polyetheretherketone, polyphenyl Examples include engineering plastics such as polysulfides, polyethersulfones, polyamide-imides, liquid crystal polymers, polytrafluoroethylenes, polychlorotrifluoroethylenes, and polyvinylidene fluoride; fluorine-based oligomers, silicone-based oligomers, and polysulfide-based oligomers; soft metals such as gold, silver, and lead; and layered crystalline materials such as graphite, molybdenum disulfide, tungsten disulfide, boron nitride, graphite fluoride, calcium fluoride, barium fluoride, lithium fluoride, silicon nitride, and molybdenum selenide.

[0135] Furthermore, examples of photosensitizers include phenothiazines, polymerization inhibitors such as 2,6-di-t-butyl-4-methylphenol, benzoin compounds, acetophenone compounds, anthraquinone compounds, thioxanthone compounds, ketal compounds, tertiary amine compounds, and xanthone compounds. [Examples]

[0136] The embodiment will be described in detail below with reference to examples, but this embodiment is not limited to these examples.

[0137] <Materials used> The materials used in the examples and comparative examples are listed below.

[0138] [Polyfunctional urethane (meth)acrylate oligomer (A)] A-1: Polycarbonate-based urethane acrylate; "CN9001NS" (manufactured by Arkema, difunctional, radical polymerizable functional group equivalent: approximately 650, number average molecular weight / weight average molecular weight (measured value): 1.3 × 10⁻⁶) 3 / 5.4×10 3

[0139] Compound A-1 has the structure represented by formula (i), where R1 is "-(CH2) m It has -(m=6). Furthermore, the radical polymerizable functional group equivalent of compound A-1 was calculated by dividing the number average molecular weight by the number of radical polymerizable functional groups.

[0140] The number-average molecular weight and weight-average molecular weight of compound A-1 were determined using a gel permeation chromatography (GPC) apparatus (Tosoh Corporation, HLC-8220GPC) with a Shodex GPC LF-804 column (Showa Denko Corporation, exclusion limit molecular weight: 2 × 10⁶). 6 Separation range: 300~2×10 6 Two ) were placed in series, and measurements were taken at 40°C using THF as the developing solvent and an RI (Refractive Index) detector. The obtained number-average molecular weight and weight-average molecular weight are standard polystyrene equivalent values.

[0141] [Radical polymerizable compound (B)] B-1: Acryloylmorpholin; "ACMO" (manufactured by KJ Chemicals, monofunctional) B-2: Isobornyl acrylate (manufactured by Tokyo Chemical Industry Co., Ltd., monofunctional) B-3: 2-(allyloxymethyl)methyl acrylate; "AOMA" (manufactured by Nippon Shokubai Co., Ltd., monofunctional) B-4: Tris-(2-acryloxyethyl) isocyanurate; "A-9300" (manufactured by Shin-Nakamura Chemical Industry Co., Ltd., trifunctional)

[0142] [Rubber particles (C)] C-1: Kaneace M-511 (manufactured by Kaneka Corporation); rubber particles with a core-shell structure consisting of a cross-linked butadiene rubber core and a polymethyl methacrylate shell, with an average particle diameter of 0.23 μm.

[0143] [Radical polymerization initiator (D)] D-1: Photoradical polymerization initiator; "Omnirad819" (manufactured by IGM Resins BV)

[0144] [Other ingredients (E)] E-1: UV absorber (UVA); "Tinuvin 405" (manufactured by BASF) E-2: Light stabilizer (HALS); "Tinuvin 152" (manufactured by BASF). E-3: Polymerization inhibitor; 4-Hydroxy-2,2,6,6-tetramethylpiperidine 1-Oxyl Free Radical (manufactured by Tokyo Chemical Industry Co., Ltd.)

[0145] <Manufacturing of photocurable resin compositions> The respective materials were blended according to the mixing ratios shown in Tables 1 and 2, and mixed until uniform, to obtain the photocurable resin compositions of Examples 1 to 7 and Comparative Examples 1 to 6.

[0146] <Manufacturing of three-dimensional objects> A three-dimensional object was manufactured from the prepared photocurable resin composition. Using a DLP (surface exposure) stereolithography system based on a controlled liquid level method, 1270 layers of 0.05 mm cured resin were stacked in the longitudinal direction to produce a three-dimensional object with dimensions of 63.5 mm in length, 12.7 mm in width, and 6.4 mm in thickness. In addition, a support section of 3.0 mm in length was provided between the stage and the three-dimensional object in the longitudinal direction to join them (total length 66.5 mm).

[0147] The following details the conditions for creating three-dimensional objects. Curing wavelength: Peak wavelength 405nm Illuminance: 8.0mW / cm2 Irradiation time: 1.0 second per layer Temperature: 25℃ Liquid film thickness: 0.10 mm Stage elevation distance after hardened layer formation: 2.5 mm Transparent component: Oxygen-permeable fluororesin (TEFLON® AF) Other molding conditions are shown in Tables 1 and 2.

[0148] After the 3D printing was completed, the object was separated from the stage and support, washed with a mixed solvent of acetone and isopropyl alcohol, dried, and then treated with a post-curing device (formlab, product name "formcure") at 70°C for 4 hours to obtain a 3D object with a length of 63.5 mm, a width of 12.7 mm, and a thickness of 6.4 mm.

[0149] <Rating> The following describes the evaluation methods for photocurable resin compositions and three-dimensional molded objects. The results obtained are shown in Tables 1 and 2.

[0150] [Viscosity and thixotropy coefficient of photocurable resin compositions] The thixotropy coefficient of the curable resin composition was measured using a rotational rheometer. Specifically, it was measured using a viscoelasticity analyzer (Physica MCR302, manufactured by Anton Paar) as follows.

[0151] Fill the measuring device, equipped with a cone-plate type measuring jig (CP25-2, manufactured by Anton Paar; 25 mm diameter, 2°), with approximately 0.5 mL of the sample and adjust the temperature to 25°C. 1s -1 , 100s -1 Under constant shear rate conditions, measurements were taken at 6-second intervals, and the value at 120 seconds was defined as viscosity.

[0152] Also, shear rate 1s -1 , 100s -1 The viscosity at [location] was used to calculate the thixotropy coefficient using the following formula. Thixotropy coefficient = (1 sec -1viscosity) / (100sec -1 viscosity)

[0153] [Izod Impact Strength] The Izod impact strength was adopted as an indicator of impact resistance. In accordance with ASTM D256, a 2.5 mm deep, 45° notch was made in the center of the three-dimensional object using a notching machine (Toyo Seiki Seisakusho Co., Ltd., product name "Notching Tool A-4"), and the impact resistance was measured using an impact tester (Toyo Seiki Seisakusho Co., Ltd., product name "IMPACT TESTER IT"). Impact resistance was evaluated according to the following criteria. A (Very Good): Izod impact strength of 8.0 kJ / m 2 That's all. B (Good): Izod impact strength of 6.0 kJ / m 2 More than 8.0kJ / m 2 less than C (Defective): Izod impact strength is 6.0 kJ / m 2 less than

[0154] [Throughput: Printing speed] As an indicator of throughput in the manufacturing of three-dimensional objects, the printing speed (mm / h) was calculated from the printing time (h) required to print a 63.5 mm long object and a 3 mm long support section, using the formula: Printing speed (mm / h) = Length (66.5 mm) / Printing time (h). Throughput (printing speed) was evaluated according to the following criteria. A (Excellent): Printing speed of 40 mm / h or more B (Good): Printing speed between 10mm / h and 40mm / h C (Defective): Printing speed less than 10 mm / h

[0155] [Table 1]

[0156] [Table 2]

[0157] As shown in Table 1, in Examples 1 to 7, the impact resistance of the three-dimensional objects manufactured under the following conditions was high and good: the change amount A was 0.20 mm / sec or more and less than 25 mm / sec, the waiting time B was 0.04 sec or more and 10 sec or less, and the relationship 0.2 ≤ B / A ≤ 5.0 was satisfied. Furthermore, the throughput in the manufacturing of the three-dimensional objects was also good.

[0158] On the other hand, as shown in Table 2, in Comparative Examples 1 to 3, although the throughput of the three-dimensional objects manufactured under the B / A < 0.2 molding conditions was good, the impact resistance tended to be significantly lower compared to Examples 1 to 7. In Comparative Example 5, although the impact resistance of the three-dimensional objects manufactured under the molding conditions where the change amount A was small (less than 0.20 mm / sec) and B / A > 5.0 was high and good, the molding speed was extremely slow, and the manufacturing throughput tended to be significantly reduced. Furthermore, in Comparative Examples 4 and 6, the impact resistance of the three-dimensional objects manufactured using a photocurable resin that does not contain particles and does not have the properties of a pseudoplastic fluid (thixotropy coefficient = 1.0) was almost the same regardless of the molding conditions, and was extremely low.

[0159] From the results above, it has been confirmed that this disclosure provides a method for manufacturing three-dimensional objects that can be obtained with high throughput and excellent impact resistance.

[0160] ≪Included components≫ This embodiment includes the following configuration. (Composition 1) A method for manufacturing a three-dimensional object using a surface exposure type stereolithography apparatus, comprising a liquid photocurable resin composition containing a photocurable resin and particles, The aforementioned photocurable resin composition is a pseudoplastic fluid whose viscosity decreases with the application of shear stress. The stereolithography apparatus includes a light source, a stage for forming the three-dimensional object, and a liquid tank on which a transparent member that transmits light from the light source is laid on the bottom surface. Step (0) is to position the pseudoplastic fluid contained in the liquid tank between the molded surface of the three-dimensional object supported on the stage and the transparent member, From the state of step (0) above, step (i) is performed to reduce the distance between the stage and the transparent member and to form a liquid film consisting of the pseudoplastic fluid between the molded surface of the three-dimensional object supported on the stage and the transparent member, The process includes (ii) irradiating the liquid film with light from the light source through the transparent member to harden it and form a hardened layer on the molded surface, The thickness of the liquid film in step (i) is 5 μm or more and 250 μm or less. In step (i) above, the change A per unit time of the distance between the molded surface and the transparent member from a position where the distance between the molded surface and the transparent member is 0.50 mm until the liquid film is formed is 0.20 mm / sec or more and less than 25 mm / sec. The waiting time B from the formation of the liquid film in step (i) to the irradiation of light in step (ii) is 0.04 sec or more and 10 sec or less, The relationship between A and B is such that 0.2 ≤ B / A ≤ 5.0. A method for manufacturing three-dimensional objects characterized by the following.

[0161] (Configuration 2) A method for manufacturing a three-dimensional object using a surface exposure type stereolithography apparatus, comprising a liquid photocurable resin composition containing a photocurable resin and particles, The aforementioned photocurable resin composition is a pseudoplastic fluid whose viscosity decreases with the application of shear stress. The stereolithography apparatus includes a light source, a stage for forming the three-dimensional object, and a liquid tank on which a transparent member that transmits light from the light source is laid on the bottom surface. Step (0) is to position the pseudoplastic fluid contained in the liquid tank between the molded surface of the three-dimensional object supported on the stage and the transparent member, From the state of step (0) above, step (i) is performed to reduce the distance between the stage and the transparent member and to form a liquid film consisting of the pseudoplastic fluid between the molded surface of the three-dimensional object supported on the stage and the transparent member, The process includes (ii) irradiating the liquid film with light from the light source through the transparent member to harden it and form a hardened layer on the molded surface, The thickness of the liquid film in step (i) is 5 μm or more and 250 μm or less. In step (i) above, the amount of change A per unit time in the distance between the molded surface and the transparent member from the position where the distance between the molded surface and the transparent member is 0.50 mm until the liquid film is formed is 10 mm / sec or more and 50 mm / sec or less. The waiting time B from the formation of the liquid film in step (i) to the irradiation of light in step (ii) is 4.0 seconds or more and 10.0 seconds or less. A method for manufacturing three-dimensional objects characterized by the following.

[0162] (Composition 3) A method for manufacturing a three-dimensional object according to configuration 1 or 2, characterized in that the thixotropy coefficient of the pseudoplastic fluid is 1.5 or more and 8.0 or less. (Composition 4) A method for manufacturing a three-dimensional object according to any one of configurations 1 to 3, characterized in that the particles are rubber particles. (Composition 5) The method for manufacturing a three-dimensional object according to configuration 4, characterized in that the rubber particles have a core-shell structure. (Composition 6) The method for producing a three-dimensional object according to configuration 5, characterized in that the shell of the core-shell structure contains a polymer of a monofunctional radical polymerizable compound having a (meth)acryloyl group.

[0163] (Composition 7) The method for manufacturing a three-dimensional object according to configuration 4, characterized in that the photocurable resin contains a radical polymerizable compound, and the content of the rubber particles is 5 parts by mass or more and 25 parts by mass or less per 100 parts by mass of the total amount of the radical polymerizable compound. (Composition 8) A method for producing a three-dimensional molded object according to any one of configurations 1 to 7, characterized in that the photocurable resin contains a radical polymerizable compound. (Composition 9) The method for producing a three-dimensional molded object according to configuration 8, characterized in that the radical polymerizable compound contains a polyfunctional urethane (meth)acrylate oligomer. (Composition 10) The method for producing a three-dimensional object according to configuration 9, characterized in that the content of the polyfunctional urethane (meth)acrylate oligomer is 15 parts by mass or more and 60 parts by mass or less per 100 parts by mass of the total amount of the radical polymerizable compound. (Composition 11) The method for producing a three-dimensional molded object according to configuration 9, characterized in that the weight-average molecular weight of the polyfunctional urethane (meth)acrylate oligomer is 1,000 or more and 60,000 or less. (Composition 12) The method for manufacturing a three-dimensional object according to configuration 9, characterized in that the polyfunctional urethane (meth)acrylate oligomer includes a structure represented by general formula (i) or (ii).

[0164] (Composition 13) A method for manufacturing a three-dimensional object according to any one of configurations 1 to 12, characterized in that A and B satisfy the relationship 0.5 ≤ B / A ≤ 5.0. (Composition 14) A method for manufacturing a three-dimensional object according to any one of configurations 1 to 13, characterized in that the three-dimensional object includes a portion with a thickness of 3.5 mm or more. (Composition 15) Furthermore, the method for manufacturing a three-dimensional object according to any one of configurations 1 to 14, characterized by having a step of raising the stage after forming the hardened layer. [Explanation of symbols]

[0165] 10: Light source, 11: Three-dimensional object, 12: Stage, 13: Transparent component, 14: Liquid tank, 15: Stereolithography apparatus, 16: Molded surface, 17: Pseudoplastic fluid (photocurable resin composition), 18: Liquid film, 19: Cured layer, 30: Liquid resin (photocurable resin), 31: Particles, 32: First aggregate, 33: Aggregate, 34: Cured resin, 35: Cured product, 40: Stereolithography apparatus, 41: Movable mechanism, 42: Drive shaft, 43: Control unit, 44: Curing light, 45: Distance, 46: Area

Claims

1. A method for manufacturing a three-dimensional object using a surface exposure type stereolithography apparatus, comprising a liquid photocurable resin composition containing a photocurable resin and particles, The aforementioned photocurable resin composition is a pseudoplastic fluid whose viscosity decreases with the application of shear stress. The stereolithography apparatus includes a light source, a stage for forming the three-dimensional object, and a liquid tank on which a transparent member that transmits light from the light source is laid on the bottom surface. Step (0) is to position the pseudoplastic fluid contained in the liquid tank between the molded surface of the three-dimensional object supported on the stage and the transparent member, From the state of step (0) above, step (i) is performed to reduce the distance between the stage and the transparent member and to form a liquid film consisting of the pseudoplastic fluid between the molded surface of the three-dimensional object supported on the stage and the transparent member, The process includes (ii) irradiating the liquid film with light from the light source through the transparent member to harden it and form a hardened layer on the molded surface, The thickness of the liquid film in step (i) is 5 μm or more and 250 μm or less. In step (i) above, the change A per unit time in the distance between the molded surface and the transparent member from the position where the distance between the molded surface and the transparent member is 0.50 mm until the liquid film is formed is 0.20 mm / sec or more and less than 25 mm / sec. The waiting time B from the formation of the liquid film in step (i) to the irradiation of light in step (ii) is 0.04 sec or more and 10 sec or less, The relationship between A and B is such that 0.2 ≤ B / A ≤ 5.

0. A method for manufacturing three-dimensional objects characterized by the following.

2. A method for manufacturing a three-dimensional object using a surface exposure type stereolithography apparatus, comprising a liquid photocurable resin composition containing a photocurable resin and particles, The aforementioned photocurable resin composition is a pseudoplastic fluid whose viscosity decreases with the application of shear stress. The stereolithography apparatus includes a light source, a stage for forming the three-dimensional object, and a liquid tank on which a transparent member that transmits light from the light source is laid on the bottom surface. Step (0) is to position the pseudoplastic fluid contained in the liquid tank between the molded surface of the three-dimensional object supported on the stage and the transparent member, From the state of step (0) above, step (i) is performed to reduce the distance between the stage and the transparent member and to form a liquid film consisting of the pseudoplastic fluid between the molded surface of the three-dimensional object supported on the stage and the transparent member, The process includes (ii) irradiating the liquid film with light from the light source through the transparent member to harden it and form a hardened layer on the molded surface, The thickness of the liquid film in step (i) is 5 μm or more and 250 μm or less. In step (i) above, the amount of change A per unit time in the distance between the molded surface and the transparent member from the position where the distance between the molded surface and the transparent member is 0.50 mm until the liquid film is formed is 10 mm / sec or more and 50 mm / sec or less. The waiting time B from the formation of the liquid film in step (i) to the irradiation of light in step (ii) is 4.0 sec or more and 10.0 sec or less. A method for manufacturing three-dimensional objects characterized by the following.

3. The method for manufacturing a three-dimensional object according to claim 1 or 2, characterized in that the thixotropy coefficient of the pseudoplastic fluid is 1.5 or more and 8.0 or less.

4. The method for manufacturing a three-dimensional object according to claim 1 or 2, characterized in that the particles are rubber particles.

5. The method for manufacturing a three-dimensional object according to claim 4, characterized in that the rubber particles have a core-shell structure.

6. The method for producing a three-dimensional object according to claim 5, characterized in that the shell of the core-shell structure comprises a polymer of a monofunctional radical polymerizable compound having a (meth)acryloyl group.

7. The method for producing a three-dimensional object according to claim 4, characterized in that the photocurable resin contains a radical polymerizable compound, and the content of the rubber particles is 5 parts by mass or more and 25 parts by mass or less per 100 parts by mass of the total amount of the radical polymerizable compound.

8. The method for producing a three-dimensional object according to claim 1 or 2, characterized in that the photocurable resin contains a radical polymerizable compound.

9. The method for producing a three-dimensional object according to claim 8, characterized in that the radical polymerizable compound contains a polyfunctional urethane (meth)acrylate oligomer.

10. The method for producing a three-dimensional object according to claim 9, characterized in that the content of the polyfunctional urethane (meth)acrylate oligomer is 15 parts by mass or more and 60 parts by mass or less per 100 parts by mass of the total amount of the radical polymerizable compound.

11. The method for producing a three-dimensional object according to claim 9, characterized in that the weight-average molecular weight of the polyfunctional urethane (meth)acrylate oligomer is 1,000 or more and 60,000 or less.

12. The method for manufacturing a three-dimensional object according to claim 9, characterized in that the polyfunctional urethane (meth)acrylate oligomer includes a structure represented by the following general formula (i) or (ii). 【Chemistry 1】 In general formulas (i) and (ii), R 1 , R 2 Each of these is a hydrocarbon group containing an alkylene group having 1 to 18 carbon atoms, and n is between 2 and 50.

13. The method for manufacturing a three-dimensional object according to claim 1, characterized in that the relationship between A and B is 0.5 ≤ B / A ≤ 5.

0.

14. The method for manufacturing a three-dimensional object according to claim 1 or 2, characterized in that the three-dimensional object includes a portion with a thickness of 3.5 mm or more.

15. Furthermore, the method for manufacturing a three-dimensional object according to claim 1 or 2, further comprising the step of raising the stage after forming the hardened layer.

Images