FR3140298A1 - Thick suspension for stereolithography and process for manufacturing three-dimensional additive product - Google Patents

Abstract

A stereolithography slurry of the embodiment contains: inorganic particles; a liquid photocurable resin; and a dispersing agent. The dispersing agent includes a nonionic dispersing agent and an ionic dispersing agent. In the stereolithography slurry of the embodiment, a viscosity η0.5 when a shear rate is 0.5 s-1, a viscosity η10 when the shear rate is 10 s-1, and a viscosity η30 when the shear rate is 30 s-1 satisfy the relationships of η0.5 ≥ 0 [Pa.s], η10 ≤ 65 [Pa.s], η30 ≤ 50 [Pa.s], η0.5/η10 ≤ 11 .00, and η10/η30 ≥ 0.86.

Description

Thick suspension for stereolithography and process for manufacturing three-dimensional additive product FIELD OF INVENTION

The embodiments described herein relate generally to a slurry for stereolithography and a method of manufacturing a three-dimensional additive product.

BACKGROUND OF THE INVENTION

When manufacturing a three-dimensional additive product, for example, a stereolithography slurry containing inorganic particles (ceramic particles, or other particles) and a liquid photocurable resin is first placed in a tank, then a stage is lowered from above, and light is irradiated from a lower surface of the tank to harden the photocurable resin, thereby forming a hardened layer below the stage. Then the slurry is made to flow and brought to an area where the slurry briefly takes the place of the hardened layer by elevation of the stage. The above formation of the hardened layer is repeated on the basis of three-dimensional design data of the three-dimensional additive product, and a laminate of the hardened layers is manufactured. Then, the three-dimensional additive product is manufactured, for example, by removing the photocurable resin cured in the above method by performing a degreasing treatment, and sintering the inorganic particles by performing a sintering treatment for the laminate hardened layers.

As described above, when manufacturing the three-dimensional additive product, it is necessary to bring the stereolithography slurry in the tank to the area irradiated by light and hardened when the stage is raised. Therefore, the above stereolithography slurry should have a thixotropy exhibiting high viscosity when shear rate is low and low viscosity when shear rate is high while maintaining fluidity. Additionally, dilatancy suppression is also required since high dilatancy, which has low viscosity at low shear rate and high viscosity at high shear rate, causes the particles to settle in the slurry.

However, it is sometimes difficult to achieve thixotropy with fluidity and dilatancy suppression in a conventional stereolithography slurry. Particularly, when inorganic particles having small particle sizes are used to achieve high-definition manufacturing, aggregation of inorganic particles tends to occur in the stereolithography slurry, which increases the thixotropic property of the slurry for stereolithography and the thick suspension may not flow. Additionally, when a dispersion property is low, the dilatancy property increases and particles can settle easily. As a result of these factors, it may be difficult to produce a three-dimensional additive fabricated product having high precision and stability.

SUMMARY

A problem to be solved by the present invention is to provide a slurry for stereolithography which enables high-precision and stable manufacturing of three-dimensional additive products and a method for manufacturing the three-dimensional additive products using the slurry.

According to the present invention, a slurry for stereolithography which enables high-precision and stable manufacturing of three-dimensional additive products and a method for manufacturing the three-dimensional additive products using the slurry are provided.

There is a flowchart illustrating an overview of a process for manufacturing a three-dimensional additive product according to one embodiment.

There is a diagram schematically illustrating an overview of a hardened layer forming step (ST20) in the method of manufacturing the three-dimensional additive product according to the embodiment.

There is a diagram schematically illustrating the overview of the hardened layer forming step (ST20) in the manufacturing process of the three-dimensional additive product according to the embodiment.

There is a diagram schematically illustrating the overview of the hardened layer forming step (ST20) in the manufacturing process of the three-dimensional additive product according to the embodiment.

There is a diagram schematically illustrating the overview of the hardened layer forming step (ST20) in the manufacturing process of the three-dimensional additive product according to the embodiment.

There is a diagram illustrating a state before a degreasing step (ST30) is implemented in the process of manufacturing the three-dimensional additive product according to the embodiment.

There is a diagram illustrating a state after the degreasing step (ST30) is implemented in the manufacturing process of the three-dimensional additive product according to the embodiment.

There is a diagram illustrating a state after a sintering step (ST40) is carried out in the manufacturing method of the three-dimensional additive product according to the embodiment.

There is a graph illustrating viscosity of the stereolithography slurry in each example measured under a plurality of conditions with different shear rates.

There is a graph illustrating details from shear rate 10 s ^-1 to shear rate 30 s ^-1 on the .

DETAILED DESCRIPTION

A stereolithography slurry of this embodiment contains inorganic particles, a liquid photocurable resin, and a dispersing agent, wherein the dispersing agent comprises a nonionic dispersing agent and an ionic dispersing agent. In the thick suspension for stereolithography of this embodiment, a viscosity η0.5 when a shear rate is 0.5 s ^-1 , a viscosity η10 when the shear rate is 10 s ^-1 and a viscosity η30 when the shear speed is 30 s ^-1 satisfy the relationships of η0.5 ≥ 0 [Pa.s], η10 ≤ 65 [Pa.s], η30 ≤ 50 [Pa.s], η0.5/η10 ≤ 11.00, and η10/η30 ≥ 0.86.

Hereinafter, a slurry for stereolithography and a method for manufacturing a three-dimensional additive product of embodiments will be described with reference to the drawings. In the embodiments described below, substantially the same components are designated by the same reference signs and a description thereof may be partially omitted. The drawings are schematic, and a relationship between thickness and planar dimension, thickness ratio between components, and so on may differ from actual ones.

There is a flowchart illustrating an overview of a process for manufacturing a three-dimensional additive product according to one embodiment. As illustrated on the , the process for manufacturing the three-dimensional additive product is carried out by sequential implementation of a preparation step (ST10), a hardened layer formation step (ST20), a degreasing step (ST30), and of a sintering step (ST40). Manufacturing of the three-dimensional additive product is accomplished using a manufacturing device (e.g., model number ARM-10 manufactured by Roland DG Corporation). Each step will be described below.

[A-1] Preparation stage (ST10)

Firstly, in the preparation step (ST10), a stereolithography slurry used in the manufacturing of the three-dimensional additive product is prepared. The slurry for stereolithography is manufactured by mixing inorganic particles, a liquid photocurable resin, and a dispersing agent.

[A-1-1] Inorganic particles

Inorganic particles are ceramic particles formed of alumina, zirconia (including zirconia stabilized by yttrium oxide, or other), and so on, for example. The inorganic particles may be metallic particles formed from a metallic material.

Here, inorganic particles, whose average particle size R satisfies a relationship represented by Inequality (A) below, are preferably used. Average particle size R is a particle size at an average volume of 50% (D50 size) and is a value equivalent to a particle size whose volume integrated value is 50% in terms of particle size distribution measured based on a laser scattering diffraction method (JIS Z 8825: 2013).

0.1 μm ≤ R ≤ 5.0 μm … (A)

When the average particle size R of the inorganic particles is less than a lower limit of a range shown in Inequality (A), aggregation of the inorganic particles readily occurs in the stereolithography slurry, sometimes leading to a decrease of the fluidity of the thick suspension for stereolithography. Furthermore, when the average particle size R of the inorganic particles is greater than an upper limit of the range indicated in Inequality (A), the density of the three-dimensional additive product produced after the sintering step (ST40) may decrease .

A content of the inorganic particles in the slurry for stereolithography is preferably in a range of 30 vol%. or more and 65% by vol. or less. When the content of inorganic particles is lower than the above range, many particles in the stereolithography slurry may settle, and the density of the three-dimensional additive product produced after the sintering step (ST40) may decrease. On the other hand, when the content of the inorganic particles is greater than the above range, there may be many inorganic particles which are not in a dispersed state in the stereolithography slurry.

[A-1-2] Photocurable resin

The liquid photocurable resin contains a polymer component such as a monomer and an oligomer, for example, and a photopolymerization initiator for initiating polymerization of the polymer component when light is irradiated. The polymer component is an acrylic monomer, for example, but not limited to.

[A-1-3] Dispersing agent

The dispersing agent is added to disperse the inorganic particles in the liquid photocurable resin. A content of the dispersing agent is preferably 0.5 mass% or more and 22.0 mass% or less in 100 mass% of the inorganic particles. When the content of the dispersing agent is less than the above range, a decrease in dispersibility may occur due to a deficiency in an adhesion amount of the dispersing agent necessary for the amount of inorganic particles . When the content of the dispersing agent is greater than the above range, an increase in slurry viscosity may occur due to increased viscosity of liquids (photocurable resin, dispersing agent) other than inorganic particles , an aggregation by impoverishment, or other.

In this embodiment, a nonionic dispersing agent and an ionic dispersing agent are both used as the dispersing agent. Examples of the nonionic dispersing agent that can be used include: ether-type polyoxyethylenes and polypropylene glycols; ester-type polyhydric alcohols such as glycerins, sorbitans, and propylene glycols; polyoxyethylene sorbitans of the ester-ether type; alkanolamide type diethanolamines, and so on. Among the above examples, ester-type polyhydric alcohols are more preferable. Examples of the ionic dispersing agent that can be used include: carboxylates, sulfonates, sulfate ester salts and phosphoric esters of the anionic type; amine salts and ammonium salts of the cationic type; and the amphoteric type in which both anionic and cationic types exist in the same molecule. Among the above examples, polycarboxylic acid copolymers, which are anionic type carboxylates, are more preferable.

In the stereolithography slurry of this embodiment, the use of both the nonionic dispersing agent and the ionic dispersing agent can lower the viscosity of the slurry to increase the fluidity, and further, improve the dispersibility of inorganic particles. In the stereolithography slurry of this embodiment, a ratio of a mass W1 of the nonionic dispersing agent to a mass W2 of the ionic dispersing agent (W1:W2) preferably satisfies a relationship represented by Inequality (B) below.

91% by mass:9% by mass ≤ W1:W2 ≤ 10% by mass:90% by mass … (B)

When the mass W2 of the ionic dispersing agent relative to a total amount (100% by mass) of the mass W1 of the nonionic dispersing agent and the mass W2 of the ionic dispersing agent is greater than an upper limit (W2 = 90 mass %) shown in Inequality (B) above, the particles in the stereolithography slurry settle in the cured layer formation step (ST20), resulting in a concentration variation between layers, lack of strength, sagging of the manufactured product, defects, and the like, making it difficult to maintain a form of the additive manufactured product. When the mass W2 of the ionic dispersing agent relative to the total amount (100% by mass) of the mass W1 of the non-ionic dispersing agent and the mass W2 of the ionic dispersing agent is less than a lower limit (W2 = 9 mass %) shown in Inequality (B) above, thixotropy increases and fluidity decreases in the hardened layer formation stage (ST20), resulting in insufficient supply of slurry may occur, making satisfactory formation of the manufactured additive product impossible.

The stereolithography slurry of this embodiment contains both the nonionic dispersing agent and the ionic dispersing agent as a dispersing agent. In the case of the nonionic dispersing agent, macromolecular dispersing components adhere to the surfaces of the inorganic particles, making contact of the inorganic particles with each other difficult at a predetermined distance or shorter by repulsion of steric hindrance. As a result, in the slurry for stereolithography, the contact resistance between the inorganic particles is suppressed, whereby improved fluidity and reduced viscosity are achieved. Meanwhile, since the nonionic dispersing agent also has an action such that the macromolecules are strongly entangled with each other, a single addition or the addition of a large amount of it causes aggregation in the suspension thick for stereolithography, resulting in increased viscosity. The ionic dispersing agent causes a high repulsive force due to steric hindrance, and a single addition or addition of a large amount thereof causes the stereolithography slurry to lose the thixotropic property and thus become a Newtonian fluid or a dilatant. Accordingly, by adjusting a composition of the two dispersing agents, it is possible to achieve both thixotropic property and dilatancy suppression in the stereolithography slurry.

[A-1-4] Viscosity of the thick suspension

In the thick suspension for stereolithography of this embodiment, a viscosity η0.5 when a shear speed is 0.5 s^-1, a viscosity η10 when the shear speed is 10 s^-1and a viscosity η30 when the shear speed is 30 s^-1satisfy the relationships represented by Inequality (C1), Inequality (C2), Inequality (C3), Inequality (C4) and Inequality (C5) below. Viscosity η0.5, viscosity η10 and viscosity η30 are values measured using a type B viscometer under a condition where a temperature is 23 °C (JIS Z 8803).

η0.5 ≥ 0 [Pa.s] … (C1)

η10 ≤ 65 [Pa.s] … (C2)

η30 ≤ 50 [Pa.s] … (C3)

η0.5/η10 ≤ 11.00 … (C4)

η10/η30 ≥ 0.86 … (C5)

When the viscosity η0.5 of the stereolithography slurry does not satisfy the above Inequality (C1), the particles in the stereolithography slurry settle easily in the hardened layer forming step (ST20). When the viscosity η10 of the slurry for stereolithography does not satisfy the Inequality (C2) above, the supply of slurry becomes insufficient in the hardened layer formation step (ST20) due to the reduced fluidity. When the viscosity η30 of the slurry for stereolithography does not satisfy the Inequality (C3) above, the supply of slurry becomes insufficient in the hardened layer formation step (ST20) due to the hardened fluidity. When the viscosity η0.5 and the viscosity η10 of the thick suspension for stereolithography do not satisfy the Inequality (C4) above, the thixotropy becomes too great and the supply of thick suspension becomes insufficient in the formation step of hardened layer (ST20) due to reduced fluidity. When the viscosity η10 and the viscosity η30 of the slurry for stereolithography do not satisfy the Inequality (C5) above, the slurry becomes dilatant in the hardened layer formation step (ST20), and the particles settle, resulting in concentration variation between layers, lack of strength, sagging of the manufactured product, defects, and others.

[A-2] Hardened layer formation step (ST20)

As illustrated on the , after implementation of the preparation step (ST10), the hardened layer formation step (ST20) is implemented. There to the are diagrams each schematically illustrating an overview of the hardened layer forming step (ST20) in the method of manufacturing the three-dimensional additive product of this embodiment.

In the hardened layer forming step (ST20), a slurry 10 for stereolithography is put into a tank 100, and a stage 200 is immersed from the top of the slurry 10, as shown in the figure. . As illustrated on the , the light 400 emitted from a light source 300 is irradiated from a lower surface of the tank 100. The irradiation of light 400 hardens the photocurable resin forming the thick suspension 10 to form a hardened layer 20. At the same time, the hardened layer 20 formed adheres to the plate 200.

Then, as illustrated in the , the stage 200 is raised and the slurry 10 is brought to an area where the hardened layer 20 is formed, which is raised simultaneously with the stage 200. As shown in the , light 400 is irradiated from the lower surface of the tank 100 to cure the photocurable resin forming the slurry 10. A 20X laminate of the cured layers 20 is manufactured by repeated processing such as a data-driven step shape of the three-dimensional additive product, for example, three-dimensional design data. The 20X laminate of the cured layers 20 is formed as a precursor to the three-dimensional additive product. Uncured portions of the slurry 10 adhering to the 20X laminate of the cured layers 20 are removed by a cleaning treatment.

[A-3] Degreasing stage (ST30) and sintering stage (ST40)

As illustrated on the , after implementing the hardened layer forming step (ST20), the degreasing step (ST30) and the sintering step (ST40) are implemented.

There is a diagram illustrating a state before implementation of the degreasing step (ST30) in the manufacturing process of the three-dimensional additive product of this embodiment. There is a diagram illustrating a state after implementation of the degreasing step (ST30) in the manufacturing process of the three-dimensional additive product of this embodiment. There is a diagram illustrating a state after implementation of the sintering step (ST40) in the manufacturing process of the three-dimensional additive product of this embodiment. In each of the to the , a cross section of part of the hardened layer, which forms the laminate, is shown schematically.

As illustrated on the , the cured layer 20 formed in the cured layer forming step (ST20) has inorganic particles 21 and a matrix 22. The matrix 22 is a base material and contains a cured component made as a result of curing the photocurable resin in the thick suspension for stereolithography as well as the dispersing agent of the thick suspension for stereolithography. As illustrated on the , when a degreasing treatment is accomplished in the degreasing step (ST30), the matrix 22 is thermally decomposed and removed into the hardened layer 20 (see ). Then, as illustrated in the , by performing a sintering treatment in the sintering step (ST40) on the inorganic particles 21 of the hardened layer having been subjected to the degreasing step (ST30), the inorganic particles 21 are sintered. As described above, a sintered body 30 of the inorganic particles 21 is formed as a three-dimensional additive product.

[B] Summary

The stereolithography slurry of this embodiment contains the inorganic particles, the liquid photocurable resin, and the dispersing agent. The dispersing agent includes the nonionic dispersing agent and the ionic dispersing agent. In the thick suspension for stereolithography of this embodiment, the viscosity η0.5 when the shear speed is 0.5 s ^-1 , the viscosity η10 when the shear speed is 10 s ^-1 and the viscosity η30 when the shear speed is 30 s ^-1 satisfy the relationships represented by Inequality (C1), Inequality (C2), Inequality (C3), Inequality (C4) and Inequality (C5), as described above. Furthermore, the average particle size R of the inorganic particles preferably satisfies the relationship represented by Inequality (A) as mentioned above. The ratio (W1:W2), which is the ratio of the mass W1 of the nonionic dispersing agent to the mass W2 of the ionic dispersing agent, preferably satisfies the relationship represented by Inequality (B) as described above.

Based on the viscosities (η0.5, η10 and η30) of the stereolithography slurry described above, the particles in the stereolithography slurry can be prevented from settling, and the shape of the manufactured product can be well preserved in preventing insufficient supply of the thick suspension for stereolithography, in the hardened layer formation step (ST20) as shown in the examples below. As a result, according to the manufacturing method of the three-dimensional additive product of this embodiment, it is possible to manufacture the three-dimensional additive product with high precision and stability.

EXAMPLES

Examples and their evaluation results are described below with reference to Table 1, Table 2, and to the . In Table 1, Table 2, the and the , Example 1 to Example 19 are examples, and Example C1 to Example C3 are comparative examples. There illustrates the measured viscosity for the stereolithography slurry in each example under several conditions with different shear rates. There illustrates details from shear rate 10 s ^-1 to shear rate 30 s ^-1 on the .

In Table 1, X1 indicates a content (% by mass) of inorganic particles in the slurry for stereolithography. X2 indicates a content (% by mass) of the liquid photocurable resin in the slurry for stereolithography. X31 indicates a content (% by mass) of the nonionic dispersing agent in the slurry for stereolithography. X32 indicates a content (% by mass) of the ionic dispersing agent in the stereolithography slurry. In Table 2, W1 indicates a content (% by mass) of the nonionic dispersing agent to inorganic particles (i.e., W1 = 100*X31/X1) and W2 indicates a content (% by mass) of the agent ionic dispersant to inorganic particles (i.e., W2 = 100*X32/X1).

[1] Manufacture of thick suspension for stereolithography

[1-1] Example 1

In Example 1, the following materials were prepared as inorganic particles, photocurable resin, nonionic dispersing agent and ionic dispersing agent.

(Materials)

Inorganic particles: alumina particles (average particle size: 2.3 μm, manufactured by Nippon Light Metal Company, Ltd., model number: LS-242C)

Photocurable resin: acrylic-based resin (manufactured by Safran SA, model number: SPR-2121)

Non-ionic dispersing agent: polyhydric alcohol non-ionic surfactant (manufactured by San Nopco Ltd., model number: SN-dispersant 9228)

Ionic dispersing agent: polycarboxylic acid-based copolymer (anionic surfactant, manufactured by NOF CORPORATION, model number: MALIALIM SC-0505K)

Then, a mixture obtained by mixing the respective materials at the contents X1,

(Agitated condition)

Agitator: ARE-250 (manufactured by THINKY CORPORATION)

Number of rotations: 800 rpm

Number of revolutions: 2,000 rpm

Stirring time: 5 minutes

[1-2] Example 2 to Example 14, Example C1 to Example C3

In Example 2 to Example 14, Example C1 to Example C3, the stereolithography slurries were manufactured in the same manner as in Example 1, with the exception that the contents , X2, X31, X32 (% by mass) of the materials were different from those in Example 1, as shown in Table 1.

[1-3] Example 15, Example 16

In Example 15 and Example 16, the following material was used as inorganic particles, different from Example 1, as shown in Table 1.

(Material)

Inorganic particles: alumina particles (average particle size: 0.1 μm, manufactured by TAIMEI CHEMICALS CO., LTD., model number: TM-DAR)

Then, a mixture obtained by mixing the respective materials at the contents X1, X2, X31 and

[1-4] Example 17

In Example 17, the following material was used as inorganic particles, different from Example 1, as shown in Table 1.

(Material)

Inorganic particles: zirconia particles (average particle size: 1.6 μm, manufactured by DAIICHI KIGENSO KAGAKU KOGYO CO., LTD., model number: KYZ-8)

Then, a mixture obtained by mixing the respective materials at the contents X1, X2, X31 and

[1-5] Example 18, Example 19

In Example 18 and Example 19, the following material was used as inorganic particles, different from Example 1, as shown in Table 1.

(Material)

Inorganic particles: zirconia particles (average particle size: 4.6 μm, manufactured by DAIICHI KIGENSO KAGAKU KOGYO CO., LTD., model number: UZY-8)

Then, a mixture obtained by mixing the respective materials at the contents X1, X2, X31 and

[2] Viscosity measurement of thick suspension

As indicated on the and in Table 2, a viscosity of the stereolithography slurry in each example manufactured as described above was measured.

Viscosity measurement was accomplished using the following viscometer under the following temperature condition.

Viscometer: HBDV2T type B viscometer (manufactured by EKO INSTRUMENTS CO., LTD.)

Temperature for measurement: 23°C

Here, the viscosity measurement was accomplished under a plurality of conditions where the shear rates were different. There and the illustrate the results of the viscosities measured in the plurality of conditions where the shear rates were different. Table 2 shows the measurement results of viscosity η0.5 when the shear rate is 0.5 s ^-1 , viscosity η10 when the shear rate is 10 s ^-1 , and viscosity η30 when the shear speed is 30 s ^-1 . In addition, Table 2 indicates a value (η0.5/η10) obtained by dividing the viscosity η0.5 by the viscosity η10 and a value (η10/η30) obtained by dividing the viscosity η10 by the viscosity η30.

[3] Test contents

As shown in Table 2, a test for fluidity and a test for an anti-settling property were performed on the stereolithography slurry of each example manufactured as described above.

[3-1] Test for fluency

In the test for fluidity, the presence or absence of groove formation in the slurry for stereolithography, which was stored inside a container of uniform thickness (5 mm), was checked by sliding a spatula horizontally so that a lower surface of the container was visible. Then, 60 seconds after the spatula slid, a groove width state was visually observed. Next, slurry fluidity was determined by estimating a percentage of the groove width buried by slurry flow (a percentage to be contributed) for the groove width using the following grading criteria.

Ranking 5: 100% of the groove width is buried by the thick suspension (100% fluidity)

Ranking 4: More than 90% and less than 100% of the groove width is buried by the thick suspension

Ranking 3: More than 45% and less than 90% of the width of the groove is buried by the thick suspension

Rank 2: More than 5% and less than 45% of the groove width is buried by the thick suspension (within a practical level)

Ranking 1: Less than 5% of the groove width is buried by the thick suspension (apart from a practical level)

[3-2] Test for anti-settling property

In the test for anti-settling, the slurry was stirred and stored at room temperature (23 °C) for 24 hours. The anti-settling property was determined from a percentage of particles at a lower surface of the container after storage. A portion of supernatant was removed from the container with a silicone spatula while maintaining the particles on the bottom surface. A mass of the remaining particles was calculated by subtracting a mass of the container from the mass of the container and the remaining particles. A residual rate was obtained based on the following equation and the anti-settling property was determined using the grading criteria.

Residual rate [% by mass] = amount of particles remaining on the bottom surface [g]/amount of total particles [g] × 100

Classification 5: The residual rate of settled particles is less than 0.5% by mass

Classification 4: The residual rate of settled particles is greater than 0.5% by mass and less than 1.0% by mass

Classification 3: The residual rate of settled particles is greater than 1.0% by mass and less than 1.5% by mass

Classification 2: The residual rate of settled particles is greater than 1.5% by mass and less than 2.0% by mass (within a practical level)

Classification 1: The residual rate of settled particles is 2.0% by mass or more (apart from a practical level)

[4] Test results

As can be seen from Table 1, Example 1 to Example 19 satisfy the relationships represented by Inequality (A), Inequality (B), Inequality (C1), Inequality (C2), Inequality (C3), Inequality (C4) and Inequality (C5) above. Therefore, thixotropy, which maintains fluidity, and dilatancy suppression, which is a settling factor, are obtained in Example 1 to Example 19, as illustrated in Fig. and the . As a result, the fluidity and anti-settling property above the practical level (ranking 2 or higher) are obtained in Example 1 to Example 19, as shown in Table 2.

Furthermore, as can be seen from Table 1, the relationships represented by Inequality (B) and Inequality (C5) are not satisfied in Example C1 and Example C2. Therefore, the particles in the thick suspension settle significantly in Example C1 and Example C2 as illustrated in Figure and the , and the anti-settling property does not reach the practical level (ranking 2 or higher) as shown in Table 2. Example C3 does not satisfy the relationships represented by Inequality (B) and Inequality (C5), as can be seen from Table 1. Therefore, Example C3 had significant thixotropy and the slurry did not flow, resulting in insufficient fluidity, as shown in Figure 1. and the . As a result, Example C3 does not reach the practical level of fluency (ranking 2 or higher) as shown in Table 2.

Although certain embodiments of the present invention have been described, these embodiments have been presented by way of example only and are not intended to limit the scope of the inventions. The new embodiments described here can be made in a variety of other shapes; furthermore, various omissions, substitutions and changes in the form of the embodiments described herein may be made without departing from the spirit of the inventions. The appended claims and their equivalents are intended to cover such forms or modifications which would be within the scope and spirit of the inventions.

Claims (7)

Thick suspension for stereolithography, comprising:
inorganic particles; a liquid photocurable resin; and a dispersing agent, in which
the dispersing agent comprises a nonionic dispersing agent and an ionic dispersing agent, and
a viscosity η0.5 when a shear rate is 0.5 s ^-1 , a viscosity η10 when the shear rate is 10 s ^-1 and a viscosity η30 when the shear rate is 30 s ^-1 satisfy the relations of η0.5 ≥ 0 [Pa.s], η10 ≤ 65 [Pa.s], η30 ≤ 50 [Pa.s], η0.5/η10 ≤ 11.00, and η10/η30 ≥ 0.86 . Thick suspension according to claim 1, in which
a ratio of a mass W1 of the nonionic dispersing agent to a mass W2 of the ionic dispersing agent satisfies a relationship of 91% by mass:9% by mass ≤ W1:W2 ≤ 10% by mass:90% by mass. Thick suspension according to claim 1, in which
a content of the dispersing agent is 0.5 mass% or more and 22.0 mass% or less of the inorganic particles in 100 mass%. Thick suspension according to claim 1, in which
an average particle size R of inorganic particles satisfies a relationship of 0.1 μm ≤ R ≤ 5.0 μm. Thick suspension according to claim 1, in which
a content of inorganic particles is 30% by volume. or more and 65% by vol. or less. Process for manufacturing a three-dimensional additive product, comprising:
preparing the thick suspension for stereolithography according to any one of claims 1 to 5 and storing the thick suspension in a tank; And
forming a hardened layer by irradiation of light from a lower surface of the tank storing the slurry to thereby harden the photocurable resin, wherein
a laminate of the cured layers is formed by repeatedly performing the formation of the cured layer based on shape data of the three-dimensional additive product. A method according to claim 6, further comprising:
obtaining a degreased body by carrying out a degreasing treatment on the laminate of the hardened layers to thereby remove the hardened photocurable resin; And
sintering the inorganic particles in the degreased body by performing a sintering treatment on the degreased body.