Composition for stereolithography, method for producing shaped article, and shaped article

Abstract

Provided are: a composition for stereolithography, which contains a monomer component that contains a vinyl styrene compound represented by formula (1) as a main component, and a photoacid generator (in the formula (1), R1 and R2 are independently a hydrogen atom or a methyl group, and n is 0, 1, or 2); a method for producing a shaped article using the composition for stereolithography; and a shaped article which is obtained by curing the composition for stereolithography.

Description

A composition for stereolithography, a method for manufacturing a molded object, and a molded object

[0001] The present invention relates to a stereolithography composition, a method for manufacturing a molded object using the stereolithography composition, and a molded object obtained by curing the stereolithography composition. This application claims priority under Japanese Patent Application No. 2025-049681, filed in Japan on March 25, 2025, the contents of which are incorporated herein by reference.

[0002] Highly crosslinkable polymers are materials with excellent heat resistance, mechanical properties, and insulating properties. In particular, cured products obtained by polymerizing vinylstyrene, i.e., divinylbenzene (DVB), a styrene-based monomer, have been reported to have high crosslink density and excellent rigidity and heat resistance. However, because the polymerization reaction makes them insoluble in solvents, their use is limited to particle preparation methods by precipitation (Patent Document 1), thin film preparation methods using chemical vapor deposition (CVD), and thermal polymerization over several weeks in a vacuum (Non-Patent Document 1). Despite the excellent physical properties that can be expected from cured products of divinylbenzene (DVB), they have not been attempted for general molding applications.

[0003] On the other hand, stereolithography is a type of 3D printing technology and is a method that enables the creation of high-definition objects. However, the resins used for stereolithography are mainly acrylate resins, methacrylate resins, and epoxy resins (Non-Patent Literature 2).

[0004] Conventionally, divinylbenzene (DVB) has been used in some cases as a resin for photopolymerization by radical polymerization (Patent Documents 2, 3, and 4).

[0005] Japanese Patent Publication No. 2020-015853, Japanese Patent Publication No. 2022-530116, Japanese Patent Publication No. 2023-058028, Japanese Patent Publication No. 2024-501094

[0006] Xavier et al., Langmuir 2017, 33 (21), 5204-5212Bagheri et al., ACS Appl. Polym. Mater. 2019, 1, 593-611

[0007] However, no technology was known for curing and molding resins that were more than 50% vinylstyrene, i.e., divinylbenzene (DVB). In the radical polymerization reaction of divinylbenzene (DVB), the radical stability is very high, so it is deactivated by oxygen, making it difficult to mold.

[0008] The present invention has been made in view of the above circumstances, and aims to provide a stereolithography composition that can form molded objects having excellent mechanical properties, heat resistance, solvent resistance, and low dielectric properties using divinylbenzene (DVB) or the like, and a method for manufacturing such molded objects.

[0009] The present inventors, in order to solve the above problems, conducted diligent research and found that by using a photoacid generator as a photocationic polymerization initiator instead of a photoradical polymerization initiator in photopolymerization, divinylbenzene (DVB) can be suitably photocured, the cured product can be molded into a fine shape, and a fabricated product with excellent properties can be formed. The present invention provides the following means.

[0010] [1] A photopolymerization composition comprising a monomer component mainly composed of a vinylstyrene compound represented by formula (1), and a photoacid generator.

[0011] (In formula (1), R １ and R ２ (where n is independently a hydrogen atom or a methyl group, and n is 0, 1, or 2.)

[0012] [2] The photopolymerization composition according to [1], wherein the vinylstyrene compound is one or more selected from the group consisting of 1,4-divinylbenzene, 1,3-divinylbenzene, 1,2-divinylbenzene, 1,4-diisopropenylbenzene, 1,3-diisopropenylbenzene, 1,2-diisopropenylbenzene, 1-isopropenyl-4-vinylbenzene, 1-isopropenyl-3-vinylbenzene, 1-isopropenyl-2-vinylbenzene, and 4-(3-butenyl)styrene. [3] The photopolymerization composition according to [1] or [2], wherein the content ratio of the monomer component is at least 90% by mass with respect to the total mass of the photopolymerization composition. [4] The photopolymerization composition according to [1] or [2], wherein the content ratio of the vinylstyrene compound is at least 75% by mass with respect to the total mass of the monomer component. [5] The photopolymerization composition according to any one of [1] to [4], wherein the photoacid generator is one or more selected from the group consisting of triarylsulfonium salts, diaryliodonium salts, naphthalimide and arylamide.

[0013] [6] A method for manufacturing a molded object, comprising irradiating the photopolymerization composition described in [1] or [2] with energy rays to cure the photopolymerization composition. [7] The method for manufacturing a molded object according to [6], wherein the method is two-photon lithography, laser scanning photopolymerization, or digital light processing (DLP) lithography.

[0014] [8] A molded object obtained by irradiating the stereolithography composition described in any one of [1] to [5] with energy rays to cure the stereolithography composition.

[0015] According to the present invention, a stereolithography composition is provided that can form a molded object having excellent mechanical properties, heat resistance, solvent resistance, and low dielectric properties using divinylbenzene (DVB) or the like, and a method for manufacturing such a molded object is also provided.

[0016] Figure 1 is a digital photograph showing a twisted-shaped object (Example 3) fabricated by laser scanning stereolithography using the stereolithography composition of Example 2. Figure 2 is a digital photograph showing an object (Example 4) fabricated by DLP (Deep Laser Printing) using the stereolithography composition of Example 2. Figure 3 is a digital photograph showing an object (Example 5) fabricated by two-photon lithography using the stereolithography composition of Example 2. Figure 4 is a graph of the thermal loss curves showing the results of thermogravimetric analysis of the objects fabricated in Example 6 and Comparative Example 1. The upper part of Figure 5 shows SEM images of the surface of the object fabricated in Example 6 before and after immersion in hydrochloric acid or sodium hydroxide aqueous solution. The lower part of Figure 5 shows SEM images of the surface of the object fabricated in Comparative Example 1 before and after immersion in hydrochloric acid or sodium hydroxide aqueous solution. Figure 6 is a graph showing the frequency dependence of dielectric loss tangent and relative permittivity for a plate-shaped object (Example 7) fabricated by DLP molding using the stereolithography composition of Example 2. Figure 7 is a digital photograph showing a casting made by directly casting zinc alloy using the object fabricated in Example 8 as a mold. Figure 8 is a digital photograph showing an object (IC socket) fabricated by DLP molding using the stereolithography composition of Example 2. Figure 9 is a digital photograph showing an object (M2 screw) fabricated by DLP molding using the stereolithography composition of Example 2.

[0017] The stereolithography composition and the method for manufacturing the manufactured object according to this embodiment will be described in detail below.

[0018] "Stereolithography Composition" The stereolithography composition according to this embodiment contains a monomer component mainly composed of a vinylstyrene compound represented by formula (1), and a photoacid generator.

[0019] (In formula (1), R １ and R ２ (where n is independently a hydrogen atom or a methyl group, and n is 0, 1, or 2.)

[0020] (Monomer component) In the photopolymerization composition according to this embodiment, the monomer component mainly comprises a vinylstyrene compound represented by formula (1). Here, "main component" means that the content ratio of the vinylstyrene compound relative to the total mass of the monomer component is at least 50% by mass. The content ratio of the vinylstyrene compound relative to the total mass of the monomer component is at least 50% by mass, preferably at least 75% by mass, more preferably at least 90% by mass, and even more preferably at least 98% by mass.

[0021] The content ratio of the monomer component relative to the total mass of the stereolithography composition is preferably at least 90% by mass, more preferably at least 95% by mass, and even more preferably at least 98% by mass.

[0022] In this specification, a vinylstyrene compound refers to a compound represented by formula (1). Examples of vinylstyrene compounds include 1,4-divinylbenzene, 1,3-divinylbenzene, 1,2-divinylbenzene, 1,4-diisopropenylbenzene, 1,3-diisopropenylbenzene, 1,2-diisopropenylbenzene, 1-isopropenyl-4-vinylbenzene, 1-isopropenyl-3-vinylbenzene, 1-isopropenyl-2-vinylbenzene, and 4-(3-butenyl)styrene. Due to their availability, 1,4-divinylbenzene, 1,3-divinylbenzene, 1,2-divinylbenzene, 1,4-diisopropenylbenzene, 1,3-diisopropenylbenzene, or 1,2-diisopropenylbenzene are preferred as vinylstyrene compounds, and 1,4-divinylbenzene or 1,3-divinylbenzene are more preferred.

[0023] Only one vinylstyrene compound may be used, or two or more may be used in mixture form. A mixture mainly containing 1,4-divinylbenzene and 1,3-divinylbenzene is particularly preferred due to its availability. Divinylbenzene (DVB, product number: 414565) manufactured by Sigma-Aldrich is a mixture mainly containing 1,4-divinylbenzene and 1,3-divinylbenzene, and also contains small amounts of 4-ethylvinylbenzene and 3-ethylvinylbenzene.

[0024] The monomer component may optionally contain monomer components other than the vinylstyrene compound represented by formula (1) (i.e., polymerizable components). Examples of monomer components other than the vinylstyrene compound include radical polymerizable components and cationic polymerizable components.

[0025] (Photoacid Generator) In the photopolymerization composition according to this embodiment, the photoacid generator can be any agent that generates acid upon irradiation with energy rays such as light, electron beams, or X-rays, and contributes to the curing reaction of the vinylstyrene compound. Examples of the photoacid generator include triarylsulfonium salts, diaryliodonium salts, naphthalimide, and arylamide. Triarylsulfonium salts are preferred as the photoacid generator.

[0026] Commercially available products can be used as the photoacid generator, for example, CPI-100P, CPI-100B, CPI-101A, CPI-110B, CPI-200K, CPI-210S, CPI-310B, CPI-310FG, CPI-410S, CPI-410B, VC-1FG, VC-1S, IK-1, ES-1B (all manufactured by Sunapro Co., Ltd.); WPI-113, WPI-116, WPI-169 WPI-170, WPI-124 (all manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.); T4012, D5952, D6258, B6631, T4223, T4013, D5990, T4223, H1776, T2041, B6324, T1608, D2231, T2180, T2041, T3038, T4024, B6632, D6256, T42222, T4025, T160 Examples include 9, O0589, H1683, B6347, I0591, B2380, M3379, D2238, B5661, D5118, B6071, D2253, D2248, I1254, B6355, H1136, M1245, B3633, F0362, M1209, M2140, D2963, N0137, N1217, C3751 (all manufactured by Tokyo Chemical Industry Co., Ltd.).

[0027] In the photopolymerization composition according to this embodiment, one type of photoacid generator may be used, or two or more types may be used in mixture form.

[0028] The content ratio of the photoacid generator relative to the total mass of the photopolymerization composition may be 0.1% by mass or more and 10% by mass or less, 0.2% by mass or more and 5% by mass or less, or 0.5% by mass or more and 3% by mass or less.

[0029] The photopolymerization composition according to this embodiment may optionally contain other components besides the vinylstyrene compound and the photoacid generator. These other components may include, when the monomer component contains a radical polymerizable component and / or a cationic polymerizable component, a corresponding polymerization initiator, such as a cationic thermal polymerization initiator like boron trifluoride or a sulfonium ion compound. Furthermore, other components may optionally include sensitizers, stabilizers, modifiers, polyol compounds, acid proliferators, silane-based or titanate-based coupling agents, plasticizers, diluents, flexibility-imparting agents such as silicone compounds, dispersants, wetting agents, colorants, pigments, dyes, inorganic additives such as inorganic fillers, UV absorbers, light stabilizers such as hindered amine-based light stabilizers, polymerization inhibitors, antioxidants, defoaming agents, mold release agents, flow regulators, and the like.

[0030] The stereolithography composition according to this embodiment can be suitably photocured, and by using the stereolithography composition, it is possible to form molded objects having excellent mechanical properties, heat resistance, solvent resistance, and low dielectric properties.

[0031] "Method for Manufacturing a Molded Object" The method for manufacturing a molded object according to this embodiment includes curing the stereolithography composition according to the above-described embodiment by irradiating it with energy rays.

[0032] In the method for manufacturing a molded object according to this embodiment, examples of energy rays include near-infrared light, visible light, ultraviolet light, electron beams, X-rays, radiation, and high-frequency waves, with ultraviolet light, visible light, and near-infrared light being preferred from the viewpoint of balancing economy and molding accuracy. Examples of ultraviolet light sources include ultraviolet lasers, LEDs, ultraviolet fluorescent lamps, mercury lamps, xenon lasers, and metal halide lamps. Examples of visible light sources include visible light lasers such as blue lasers, LEDs, fluorescent lamps, mercury lamps, xenon lamps, and metal halide lamps. Examples of near-infrared light sources include near-infrared lasers.

[0033] The method for manufacturing a molded object according to this embodiment can be any molding method using these energy rays, and can be suitably used, for example, for high-definition molding using two-photon lithography, molding using one-photon lithography, molding using laser scanning photopolymerization, high-speed molding using digital light processing, and photopolymerization 3D printers. In addition to a method of directly molding 3D model information using a photopolymerization method, the method for manufacturing a molded object according to this embodiment can also be suitably used, for example, for a method of manufacturing a molded object such as a 2D part or 3D part by pouring the photopolymerization composition into a mold and curing it by irradiating it with energy rays using an ultraviolet lamp or the like, and for optical nanoimprinting using the photopolymerization composition as a forming material. The method for manufacturing a molded object according to this embodiment is preferably applicable to two-photon lithography, laser scanning photopolymerization, and digital light processing (hereinafter sometimes referred to as "DLP molding method").

[0034] The manufacturing method for molded objects according to this embodiment makes it possible to produce molded objects with high rigidity, high thermal stability, low dielectric loss, and high solvent resistance, and also offers a high degree of freedom in molding and processing.

[0035] "Shaped Article" The shaped article according to the present embodiment has the following aspects. "8" A shaped article obtained by irradiating the stereolithography composition according to any one of [1] to [5] with an energy ray to cure the stereolithography composition. "9" The shaped article according to "8", wherein when thermogravimetry is performed on the shaped article using a thermal analyzer under an air atmosphere at a heating rate of 5°C / min, the weight loss rate at 200°C is 1% or less. "10" The shaped article according to "8" or "9", wherein when thermogravimetry is performed on the shaped article using a thermal analyzer under an air atmosphere at a heating rate of 5°C / min, the weight loss rate at 402°C is 5% or less. "11" The shaped article according to any one of "8" to "10", wherein when contact stiffness evaluation is performed on the shaped article using a nanoindenter with a Berkovich indenter (a three-sided pyramid structure, the internal angle of the indenter is 142.35°, the angle between the center line and the surface is 65.35°, and the aspect ratio of the indenter is 1:8) under the conditions of a loading rate of 10 µm / s and a maximum load of 20 µN, the Young's modulus is 3.2 GPa or more.

[0036] As described above, the preferred embodiments of the present invention have been described in detail, but the present invention is not limited to specific embodiments, and various modifications and changes can be made within the scope of the gist of the present invention described in the claims.

[0037] Hereinafter, the present invention will be described more specifically with reference to Examples, Reference Examples and Comparative Examples. It should be noted that the present invention is not limited only to the following Examples.

[0038] The following components were used as monomer components. DVB: (divinylbenzene, product number: 414565, manufactured by Sigma-Aldrich Co.) SR399: (dipentaerythritol pentaacrylate, manufactured by Sartomer Company) SR499: (ethoxylated (6) trimethylolpropane triacrylate, manufactured by Sartomer Company)

[0039] The following compounds were used as a photoacid generator. CPI-110B: (diphenyl[4-(phenylthio)phenyl]sulfonium tetrakis(pentafluorophenyl)borate, manufactured by San-Apro Ltd., the molar extinction coefficient at i-line (365 nm) is 80 [L·mol －１ ·cm－１ level) CPI-310B: ([1,1'-biphenyl]-4-yl[4-[[1,1'-biphenyl]-4-ylthio]phenyl](phenyl)sulfonium tetrakis(perfluorophenyl)borate (including isomer mixture), manufactured by San-Apro Ltd., has a molar extinction coefficient of 600 [L・mol －１ ・cm －１ level)

[0040] The following was used as the radical photopolymerization initiator. TPO: (diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide, manufactured by Sigma-Aldrich Co. LLC)

[0041] [Examples 1 to 2, Reference Examples 1 to 7] Each compound was mixed according to the formulation shown in Table 1 to produce a stereolithography composition consisting of a monomer component (98% by mass) and a polymerization initiator (2% by mass). The obtained stereolithography composition was subjected to the following evaluations, and the results are shown in Table 1.

[0042] [Evaluation Method] A UV handy lamp (SLUV-8, 365 nm, 1407 μW / cm ２ , manufactured by As One Corporation) was used to irradiate the stereolithography composition with UV for 15 minutes or 30 minutes, and evaluation was performed according to the following criteria.

[0043] [Criteria] A: Curing was confirmed after UV irradiation. B: A gel state or only partial curing was observed after UV irradiation. C: No curing was confirmed after UV irradiation. -: Curing was already confirmed after 15 minutes of UV irradiation, so the experiment was stopped.

[0044]

[0045] As shown in Table 1, in Reference Example 1, curing could not be confirmed in the system using 100% by mass DVB as the monomer component and TPO as a radical polymerization initiator, making fabrication difficult. In Reference Examples 6 and 7, when 50% by mass DVB and 50% by mass acrylate monomer (SR399 or SR499) were used as the monomer components, curing was confirmed even in the system using TPO as a radical polymerization initiator. However, in Reference Examples 1 to 5, when 75% by mass or more DVB was used as the monomer component, complete curing could not be confirmed with irradiation of less than 15 minutes in the system using TPO as a radical polymerization initiator.

[0046] On the other hand, in the compositions of Examples 1 and 2, which used a photoacid generator (CPI-110B or CPI-310B), curing was confirmed even though 100% by mass of DVB was used as the monomer component. From this, it was confirmed that the photoacid generator is effective for energy ray curing of DVB. Next, comparing Examples 1 and 2, curing was confirmed in a shorter time in Example 2. This is thought to be because the photoacid generator used in Example 2 has a larger molar extinction coefficient at 365 nm. From the above, among the compositions examined in Examples 1-2 and Reference Examples 1-7, the composition of Example 2 is considered superior in terms of curing speed.

[0047] [Example 3] (Fabrication of a fabricated object by laser scanning stereolithography) The stereolithography composition prepared in Example 2 was fabricated using a laser scanning stereolithography apparatus developed in-house. The laser scanning stereolithography apparatus used is configured to adjust the light intensity of a 375 nm ultraviolet laser (DLD-XT 37550, LASOS Lasertechnik GmbH) using an ND filter, expand the beam diameter with a beam expander, and scan in the X and Y axes using a galvanometer mirror to fabricate one layer by hardening, then move in the Z axis and fabricate another layer, repeating the process. Under conditions of a laser output of 20 mW and a laser scanning speed of 200 μm / s, a fabricated object with a twisted shape was produced, with a bottom surface of 1000 μm × 1000 μm and a top surface of 1000 μm × 1000 μm. Figure 1 is a digital photograph showing a twisted-shaped object (Example 3) fabricated by laser scanning stereolithography using the stereolithography composition of Example 2. This confirms that the stereolithography composition of Example 2 can be used in laser scanning stereolithography.

[0048] [Example 4] (Fabrication of a fabricated object by DLP fabrication method) The photopolymerization composition prepared in Example 2 was fabricated using a DLP with a DMD (Digital Micromirror Device) chipset (PDC04-35, XIAMEN ZHISEN ELECTRO.EQUIP.CO.,LTD) and a 385 nm LED light source (maximum output: 400 mW / mm²). ２ The object was fabricated using DLP 3D printing (resolution 35 μm) with the stereolithography composition of Example 2. Figure 2 is a digital photograph showing the object (Example 4) fabricated by DLP 3D printing using the stereolithography composition of Example 2. Figure 8 is a digital photograph showing the object (IC socket) fabricated by DLP 3D printing using the stereolithography composition of Example 2. Figure 9 is a digital photograph showing the object (M2 screw) fabricated by DLP 3D printing using the stereolithography composition of Example 2. It was confirmed that the stereolithography composition of Example 2 can be used in DLP 3D printing.

[0049] [Example 5] (Fabrication of a fabricated object by two-photon fusion) The photopolymerization composition prepared in Example 2 was fabricated using the two-photon fusion method with a laser scanning type photopolymerization apparatus developed in-house. The laser scanning type photopolymerization apparatus used is configured to adjust the light intensity using an ND filter from a 730 nm phetosecond laser source (Mai Tai XF, Spectra-Physics), expand the beam diameter with a beam expander, scan in the X and Y axes using a galvano mirror to harden one layer, then move in the Z axis and fabricate another layer, and repeat this process. A fabricated object was created using the two-photon fusion method under conditions of laser output of 85 mW and laser scanning speed of 89 μm / s (measured value). Figure 3 is a digital photograph showing the fabricated object (Example 5) fabricated using the two-photon fusion method with the photopolymerization composition from Example 2. It was confirmed that the photopolymerization composition from Example 2 can be used in the two-photon fusion method. It was confirmed that the stereolithography composition of Example 2 can be used with multiple stereolithography methods, including the laser scanning stereolithography method of Example 3, the DLP method of Example 4, and the two-photon method of Example 5. It was confirmed that the stereolithography composition of the present invention is generally applicable regardless of the type of stereolithography method.

[0050] [Example 6 and Comparative Example 1] (Fabrication of fabricated objects by laser scanning stereolithography) Using the stereolithography composition prepared in Example 2, a cubic object (Example 6) measuring 1000 μm × 1000 μm × 1000 μm was fabricated by laser scanning stereolithography using a 375 nm ultraviolet laser under the conditions of laser output of 40 mW and laser scanning speed of 800 μm / s. In addition, a stereolithography composition consisting of SR499 (98 mass%) as monomer components and radical polymerization initiator TPO (2 mass%) was prepared, and a cubic object (Comparative Example 1) measuring 1000 μm × 1000 μm × 1000 μm was fabricated in the same manner as in Example 6.

[0051] (Thermogravimetric Analysis) The molded objects of Example 6 and Comparative Example 1 were subjected to thermogravimetric analysis using a Shimadzu Corporation DTG-60H thermal analyzer under airflow conditions and a heating rate of 5°C / min. Figure 4 is a graph of the thermal loss curves showing the results of thermogravimetric analysis of the molded objects of Example 6 and Comparative Example 1. The molded object of Example 6 (DVB) had a weight loss rate of 0.8% up to 200°C, and the temperature at which a 5% weight loss occurred was 402°C. The molded object of Comparative Example 1 (thermosetting acrylic resin) had a weight loss rate of 1.6% up to 200°C, and the temperature at which a 5% weight loss occurred was 235°C. The fabricated object of Example 6 exhibited high thermal stability and heat resistance, as evidenced by thermogravimetric analysis under an air atmosphere, with a weight loss rate of 5% or less up to 402°C. Furthermore, the boiling point of divinylbenzene was 195°C, and the weight loss at 200°C was 1% or less, indicating a low monomer retention rate.

[0052] (Young's modulus measurement using a nanoindenter) The fabricated objects of Example 6 and Comparative Example 1 (cubes measuring 1000 μm × 1000 μm × 1000 μm) were subjected to contact stiffness evaluation using a Bruker nanoindenter (TI Premier) at a loading speed of 10 μm / s and a maximum load of 20 μN, with a Berkovich indenter (a three-sided pyramidal structure, with an internal angle of 142.35°, an angle between the center line and the face of 65.35°, and an aspect ratio of 1:8). As a result, the Young's modulus of the fabricated object of Example 6 was 3.27 ± 0.17 GPa. The Young's modulus of the fabricated object of Comparative Example 1 was 0.405 ± 0.005 GPa. The fabricated object in Example 6 had a Young's modulus of 3.2 GPa or higher, as determined by a nanoindenter, and exhibited superior mechanical properties compared to objects obtained using SR499, a common photocurable resin. The objects obtained using the photopolymerization composition of the present invention have advantages over other common photocurable resins in that they possess high heat resistance and chemical resistance.

[0053] (Evaluation Test of Acid and Alkali Resistance) The surfaces of the molded objects from Example 6 and Comparative Example 1 (cubes measuring 1000 μm × 1000 μm × 1000 μm) were observed using a scanning microscope (SEM) before immersion in 1 mol / L hydrochloric acid or 1 mol / L sodium hydroxide aqueous solution, and after immersion for 24 hours. The upper part of Figure 5 shows the SEM images of the surface of the molded object from Example 6 before and after immersion in hydrochloric acid or sodium hydroxide aqueous solution. The lower part of Figure 5 shows the SEM images of the surface of the molded object from Comparative Example 1 before and after immersion in hydrochloric acid or sodium hydroxide aqueous solution. In the SEM image of the surface of the molded object from Example 6 (a molded object made of DVB), a pattern was observed before immersion, but no significant change in the pattern was observed after immersion. In contrast, the SEM image of the surface of the object in Comparative Example 1 (an object made of acrylate resin, a common stereolithography resin) showed a significant change in the pattern before immersion, with a rough surface observed after immersion. The object in Example 6 demonstrated excellent acid resistance and excellent alkali resistance.

[0054] [Example 7] (Fabrication of a fabricated object by DLP fabrication method and evaluation of electrical properties) Using the photopolymerization composition prepared in Example 2, a plate-shaped fabricated object (Example 7) was fabricated by DLP fabrication. The relative permittivity and dielectric loss tangent were measured at 1 MHz using an LCR meter ZM2375 manufactured by NF Circuit Design Block Co., Ltd., and, as an option, a thin film measurement jig (model: 1020) manufactured by Kuwaki Electronics Co., Ltd. The results were 1.70 ± 0.04 and 0.00306 ± 0.00007, respectively, indicating low dielectric properties. Therefore, it can be used as an excellent insulating layer with little change in electrical properties even in the high-frequency range. In addition, the frequency dependence was measured at the Electronic Technology Department of the Kanagawa Prefectural Institute of Industrial Science and Technology (KISTEC) using a Keysight Technologies N5227B vector network analyzer and, as an option, the PS-XSN-100 BCDR balanced disk resonator solution for measuring the complex dielectric constant of microwave and millimeter-wave dielectric substrates. Figure 6 is a graph showing the measurement results of the frequency dependence of dielectric loss tangent and relative permittivity for a plate-shaped object (Example 7) fabricated by DLP molding using the photopolymerization composition of Example 2. The measurement results of the frequency dependence of dielectric loss tangent and relative permittivity of the object fabricated in Example 7 show lower relative permittivity and dielectric loss tangent values, especially in the high-frequency range, compared to the relative permittivity and dielectric loss tangent values ​​of general resin materials, demonstrating excellent properties. Therefore, it is considered that this material has the potential to be provided as a low dielectric constant, low dielectric loss tangent material compatible with next-generation communications (5G, 6G).

[0055] [Example 8] (Mold preparation and casting of zinc alloy by DLP molding method) Using the stereolithography composition prepared in Example 2, a mold (Example 8) was fabricated by DLP molding. Zinc alloy was cast using this mold from Example 8. Figure 7 is a digital photograph showing the casting made by directly casting zinc alloy using the mold from Example 8. The melting point of the zinc alloy (Standard Test Piece Co., Ltd. ZDC2) is approximately 380°C, and the mold from Example 8 did not lose its shape even under such high temperature conditions, functioning as a mold and demonstrating high heat resistance that allows for direct casting of zinc alloy.

[0056] As described above, the fabricated objects obtained by energy ray curing of the stereolithography composition of the present invention exhibited properties close to those of super engineering plastics, such as high heat resistance, high solvent resistance, and high rigidity.

[0057] Applications of the photopolymerization composition of the present invention include optical materials such as eyeglasses and imaging lenses, paints, coatings, linings, inks, resists, liquid resists, adhesives, printing plates, insulating varnishes, insulating sheets, laminates, printed circuit boards, encapsulants for semiconductor devices, LED packages, liquid crystal injection ports, organic EL devices, optical elements, electrical insulation, electronic components, and separation films, molding materials, putties, glass fiber impregnating agents, sealing agents, passivation films for semiconductors and solar cells, interlayer insulating films, protective films, prism lens sheets used as backlights for liquid crystal displays, Fresnel lens sheets used as screens for projection televisions, lenticular lens sheets, and other lens sheets, or backlights using such sheets, optical lenses such as microlenses, optical elements, optical connectors, optical waveguides, and resins for optical fabrication. For example, suitable substrates for use as a coating agent include metals, wood, rubber, plastics, glass, and ceramic products.

[0058] The stereolithography composition of the present invention exhibits excellent energy ray curability, and from the viewpoint of excellent mechanical strength, heat resistance, solvent resistance, and low dielectric constant of the cured product obtained by energy ray curing, it can be suitably used as a stereolithography composition. In particular, it is useful as a material for manufacturing objects using a 3D printer (a device that directly fabricates three-dimensional objects by additive manufacturing based on CAD (Computer-Aided Design) data).

Claims

1. A photopolymerization composition comprising a monomer component mainly composed of a vinylstyrene compound represented by formula (1), and a photoacid generator. (In formula (1), R １ and R ２ (where n is independently a hydrogen atom or a methyl group, and n is 0, 1, or 2.) 2. The photopolymerization composition according to claim 1, wherein the vinylstyrene compound is one or more selected from the group consisting of 1,4-divinylbenzene, 1,3-divinylbenzene, 1,2-divinylbenzene, 1,4-diisopropenylbenzene, 1,3-diisopropenylbenzene, 1,2-diisopropenylbenzene, 1-isopropenyl-4-vinylbenzene, 1-isopropenyl-3-vinylbenzene, 1-isopropenyl-2-vinylbenzene, and 4-(3-butenyl)styrene.

3. The stereolithography composition according to claim 1 or 2, wherein the content ratio of the monomer component is at least 90% by mass with respect to the total mass of the stereolithography composition.

4. The photopolymerization composition according to claim 1 or 2, wherein the content ratio of the vinylstyrene compound is at least 75% by mass with respect to the total mass of the monomer components.

5. The photopolymerization composition according to claim 1 or 2, wherein the photoacid generator is one or more selected from the group consisting of triarylsulfonium salts, diaryliodonium salts, naphthalimides, and arylamides.

6. A method for manufacturing a molded object, comprising curing the stereolithography composition described in claim 1 or 2 by irradiating it with energy rays.

7. A method for manufacturing a fabricated object according to claim 6, wherein the method is two-photon lithography, laser scanning photolithography, or DLP lithography.

8. A molded object obtained by irradiating the stereolithography composition described in claim 1 or 2 with energy rays to cure the stereolithography composition.

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