JP2020023064A - Slurry for photo molding and method for producing photo molded object using the same - Google Patents

Abstract

To provide slurry used for a photo molding technique of producing a high-definition three-dimensional molded object, and a photo molding method using the same.SOLUTION: Slurry for photo molding comprises: a photocurable resin, first inorganic particles and second inorganic particles, in which the average particle diameter of the first inorganic particles is 1 to 5 [μm], the particle diameter of the second inorganic particles is 0.22 times or lower than that of the first inorganic particles, the volume ratio of the second inorganic particles to the first inorganic particles is 0.01 or higher, and its viscosities in its shear speeds 10 [1/s] and 0.01 [1/s] are to be 50 [Pa s] or lower and 500 [Pa s] or higher, respectively, thus its application characteristics and shape maintaining characteristics upon resting can be made consistent. By forming a pattern on the layer of the slurry with laser light, a high-definition three-dimensional photo molded object can be produced.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a slurry used for an optical molding technique for producing a three-dimensional molded article and a method for producing an optical molded article using the slurry.

As a technique for manufacturing a three-dimensional structure, an optical molding technique is known.
The optical molding technology is a technology for manufacturing a three-dimensional molded object by repeating a process of irradiating a photocurable resin with light to cure the resin. In addition, by irradiating light to a slurry obtained by mixing ceramic or metal inorganic particles with a photocurable resin, the resin is removed from the obtained photocured product, and the inorganic component is sintered, whereby the inorganic component is sintered. There is also known a method for obtaining a three-dimensional model having a skeleton. For example, using a stereolithography apparatus shown in Patent Document 1, a process of applying a thin layer of slurry on a modeling table, scanning with an ultraviolet laser, and curing the slurry in a predetermined pattern shape is repeated, and the slurry is three-dimensionally cured. After forming a photo-cured product and removing the uncured slurry, the resin component is removed by degreasing and sintering to produce a three-dimensional modeled product.
The slurry used in the stereolithography technique needs to have good fluidity when a uniform layer is applied by a recoater, and have thixotropic properties of maintaining the shape after the application is completed.

  Further, in order to manufacture a molded article having a precise and fine structure, it is necessary to reduce the thickness of the slurry layer applied at a time, but if the particle diameter of the inorganic particles contained in the slurry is larger than 10 [μm]. In addition, the smoothness of the surface of the slurry layer is reduced, and high-precision molding is difficult. Therefore, a slurry in which inorganic particles having a fine particle diameter of 10 [μm] or less are required. (For example, Patent Documents 2 and 3)

JP 2018-20521 A JP 2001-26609 A JP 2007-237683 A

If the particle size of the inorganic particles contained in the slurry is reduced in order to produce a high-definition model, it is difficult to uniformly mix the inorganic particles with the resin due to the aggregation of the inorganic particles. In order to avoid this, if the content of the inorganic particles is reduced, the cured photocured product shrinks when it is sintered, causing a problem such as a crack, thereby lowering the yield of the photolithographic product.
Further, the slurry has a low viscosity at the time of application, it is necessary to have a thixotropic property of having a high viscosity after the application, but when the particle size of the inorganic particles to be contained is increased, sufficient thixotropic property can be realized. It becomes difficult.

  In view of the above problems, the present invention provides a stereolithography slurry containing inorganic particles having a fine particle size and capable of realizing a sufficient thixotropic property, and a method for producing a stereolithography using the same. As an issue.

The slurry for stereolithography according to the present invention,
Including first inorganic particles, second inorganic particles and a photocurable resin,
The average particle diameter of the first inorganic particles is 1 to 5 [μm],
The average particle size of the second inorganic particles is not more than 0.22 times the average particle size of the first inorganic particles,
The volume ratio of the second inorganic particles to the first inorganic particles is 0.01 or more,
The viscosity at a shear rate of 10 [1 / s] is 50 [Pa · s] or less,
The viscosity at a shear rate of 0.01 [1 / s] is 500 [Pa · s] or more,
It is characterized by the following.

  By using such a slurry for stereolithography, a slurry for producing a high-definition stereolithography product having good thixotropy can be obtained.

  By using a slurry having such characteristics, the slurry can be uniformly applied, and the slurry can be laminated, thereby facilitating the production of a stereolithography having a high-definition three-dimensional structure.

Further, the slurry for stereolithography according to the present invention,
The volume ratio of the first inorganic particles is equal to or more than a solidification limit value.

Further, the slurry for stereolithography according to the present invention,
The combined volume ratio of the first inorganic particles and the second inorganic particles is 65 to 70 [vol%].

Further, the slurry for stereolithography according to the present invention,
The volume ratio of the second inorganic particles to the first inorganic particles is 0.10 to 0.15.

  By using such a stereolithography slurry, shrinkage during sintering of a photocured product formed from the stereolithography slurry can be reduced, and a high-definition stereolithography product can be accurately manufactured. Becomes

The method of manufacturing an optically shaped article according to the present invention includes:
A first step of discharging the stereolithography slurry,
A second step of extending the stereolithography slurry to form a slurry layer having a thickness of 5 to 200 [μm];
A third step of irradiating the slurry layer with a laser beam by scanning in a predetermined pattern shape;
Repeating the first, second, and third steps to form a photocured product from the slurry layer;
A first heat treatment step of heat treating the photocured material to remove the photocurable resin;
And a second heat treatment step of heat-treating and sintering the photocured product after the first heat treatment step.

The method of manufacturing an optically shaped article according to the present invention includes:
In the first step or the first step and the second step, the temperature of the stereolithography slurry is maintained at 35 to 60 ° C.

  According to such a method of manufacturing an optically formed object, a high-definition optically formed object can be easily manufactured with good reproducibility.

  ADVANTAGE OF THE INVENTION According to this invention, while being able to contain the inorganic particle of a fine particle diameter at high density and realizing sufficient thixotropic property, the slurry for stereolithography and the stereolithography method using the same can be provided.

FIG. 2 is a conceptual diagram showing a main part of the optical shaping apparatus. The figure which shows the state of close packing by two types of particles. Dependence of viscosity on shear rate.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, none of the following embodiments gives a limited interpretation in the recognition of the gist of the present invention. In addition, the same or similar members are denoted by the same reference numerals, and description thereof may be omitted.

  The particle diameter of the inorganic particles follows a logarithmic normal distribution, and the “average particle diameter” of the inorganic particles means the particle diameter at an integrated value of 50% in the particle diameter distribution. The particle diameter (particle diameter) was measured using a wet laser diffraction / scattering method (Microtrac MT330) and SEM observation measurement.

(Embodiment 1)
Hereinafter, a slurry containing inorganic particles in a photocurable resin used in the stereolithography technique will be described.

<Manufacturing process of stereolithography>
FIG. 1 is a conceptual diagram showing a main part of the optical shaping apparatus disclosed in Patent Document 1.
As shown in FIG. 1A, the slurry 1 for stereolithography is discharged from a dispenser 2 and deposited on the upper surface of the auxiliary table 3.
After that, as shown in FIG. 1B, the recoater 4 moves above the modeling table 5 in the Y direction in the figure, for example, at a speed of 1 to 5 [mm / s], and is deposited on the upper surface of the auxiliary table 3. The slurry 1 thus obtained is spread on the modeling surface 5a of the modeling table 5 to form a slurry layer 1a having a uniform thickness. The moving speed of the recoater 4 is appropriately adjusted according to the viscosity characteristics and the coating thickness of the slurry 1.
For example, if the speed of the recoater 4 is set so as to be a typical shearing speed of 20 to 200 [1 / s] with respect to a thickness of 50 [μm] of the slurry layer 1a, the above-mentioned speed 1 to 1 is used. 5 [mm / s]. The speed of the recoater 4 depends on the characteristics of the slurry 1, particularly on the thixotropy described later.
The thickness of the slurry layer 1a is 5 to 200 [μm], and the thickness of the slurry layer 1a suitable for producing a high-definition stereolithographic product is 5 to 50 [μm].
The thickness of the slurry layer 1a can be adjusted by the height of the recoater 4 in the Z direction.
That is, the distance between the XY plane formed by the upper surface (surface) of the modeling surface 5a (or the slurry layer 1a formed immediately before, which will be described later) and the XY plane through which the lower end of the recoater 4 passes is formed in the Z direction. The thickness of the slurry layer 1a formed by the movement of the recoater 4 is determined.

Thereafter, the formed slurry layer 1a is scanned and exposed to laser light having a photosensitive wavelength of the photocurable resin contained in the slurry 1.
The optical path of the laser light is controlled by an optical system using a lens or a mirror (not shown), and the laser light is scanned in a predetermined pattern on the XY plane.
At the location irradiated with the laser beam, the photocurable resin contained in the slurry 1 is cured by a photochemical reaction. As a result, of the slurry 1 in the slurry layer 1a, a portion of the predetermined pattern which has been subjected to the scanning exposure is hardened, and the hardened layer 6 is formed. The portion not irradiated with the laser beam remains uncured slurry 1.

Thereafter, the modeling table 5 moves (falls) in the Z direction by a distance corresponding to the thickness of the slurry layer 1a, for example, 5 to 200 [μm]. As a result, the upper surface of the hardened layer 6 has the same height as the auxiliary table 3 and is in the state shown in FIG.
Here, a first step of discharging the stereolithography slurry 1 from the dispenser 2, a second step of extending the stereolithography slurry 1 by the recoater 4 and forming a new slurry layer 1 a on the hardened layer 6, The third step of irradiating the slurry layer 1a with laser light in a predetermined pattern shape is repeated.

  The above steps are repeated a predetermined number of times, and the cured layer 6 is laminated in the Z direction. The laminated cured layer 6 forms a photo-cured product cured into a predetermined three-dimensional shape.

  Since the slurry 1 is used in the discharging step and the extending step as described above, and the discharging step and the extending step are repeated to form a slurry layer, the slurry 1 preferably has thixotropic properties. The thixotropic property means that the substance has a high viscosity in a stationary state, and the viscosity decreases as the shear rate increases. By having a low viscosity at a high shear rate, the slurry 1 can be discharged and elongated. By having a high viscosity in a stationary state, the shape of the stacked slurry layer can be maintained. Having a low viscosity at a high shear rate preferably means 50 [Pa · s] or less at a shear rate of 10 [1 / s]. Here, the shear rate 10 [1 / s] is a value in consideration of the moving speed of the recoater 4. To have a high viscosity in a stationary state is preferably 500 [Pa · s] or more at a shear rate of 0.01 [1 / s].

  By using the slurry having the thixotropic property and stretching it with the recoater 4 at a shear rate of, for example, 10 [1 / s] or more, the layers of the slurry can be sequentially laminated uniformly and with good reproducibility. Here, as the number of stacked layers increases, the gravity applied to the stacked uncured slurry increases. Therefore, in order to maintain the shape after application in the stacked state, the slurry needs to have a high viscosity. When a slurry having a shear rate of 0.01 [1 / s] and a slurry of 500 [Pa · s] or more is used, the shape of the stacked slurry layer can be maintained, and as a result, a highly accurate three-dimensional structure can be obtained. be able to.

In addition, in order to reduce the viscosity at the time of application, the temperature of the dispenser 2, the recoater 4, and the auxiliary table 3 may be controlled to maintain the temperature of the slurry 1 at 35 ° C to 60 ° C. In particular, when the viscosity at rest is very high due to the thixotropic property, the ejection from the dispenser 2 may be difficult.
In this case, by maintaining at least the temperature of the dispenser 2 and the recoater 4 in the range of 35 to 60 ° C., the viscosity of the slurry 1 is reduced, and the slurry 1 can be discharged smoothly.
However, if the holding temperature exceeds 60 ° C., the photocurable resin reacts thermally and the photocuring performance may be deteriorated. Therefore, it is preferable that the holding temperature does not exceed 60 ° C.

  Thereafter, the uncured slurry 1 is dissolved and removed with an organic solvent or the like, and the region cured in a predetermined three-dimensional shape is left as a photocured material.

Thereafter, the photo-cured product cured into a three-dimensional pattern shape is gradually heated in an air atmosphere (oxygen-containing atmosphere) to, for example, 500 to 600 ° C., and is subjected to a heat treatment, so that a resin component contained in the photo-cured product is obtained. Is decomposed and degreased by vaporization.
Thereafter, the temperature is further increased. For example, when ceramic particles are used as the inorganic material, the inorganic particles contained in the photocured product are sintered by a heat treatment at 1500 to 1600 ° C., and then the temperature is lowered to room temperature.
The degreasing step and the sintering step may be performed continuously and continuously, or may be performed as separate steps.

  Through the above steps, it is possible to provide a high-definition three-dimensional stereolithography made of a sintered inorganic material.

<Slurry>
Items required for a slurry for obtaining a high-definition optical molded article include (1) having thixotropy from a requirement in a process of forming a photocured body, and (2) shrinkage in a sintering process. Are reduced. In the present invention, a slurry that satisfies the above-mentioned requirements at the same time is provided by using a photocurable resin and inorganic particles as main constituents and setting the particle size and content of the inorganic particles in specific ranges.

<Particle size of inorganic particles>
The slurry according to the present invention contains two types of inorganic particles having different average particle sizes and a liquid photocurable resin. Among the inorganic particles having different average particle diameters, the larger one is the first inorganic particle, and the smaller one is the second inorganic particle.

  The preferred range of the average particle size of the first inorganic particles is 1 to 5 μm. When the average particle diameter of the first inorganic particles exceeds 5 μm, the inorganic particles become too large with respect to the thickness of the slurry layer, and a case where the slurry layer is not formed uniformly in the stretching step occurs. The smoothness becomes insufficient. If it is less than 1 μm, the cohesive force of the inorganic particles is increased, the viscosity of the slurry is increased, and the fluidity required in the process cannot be secured.

  The second inorganic particles are characterized by being sufficiently smaller than the first inorganic particles. Sufficiently small means that there is such a difference that the second inorganic particles can enter the gap filled with the first inorganic particles. By mixing the two types of particles having sufficiently different sizes, the space in the slurry that would have been occupied by the photocurable resin without the second inorganic particles was replaced by the second inorganic particles. Can be As a result, the ratio of the volume occupied by the inorganic particles in the slurry per unit volume, that is, the content ratio of the inorganic particles can be increased as compared with the case where the first inorganic particles are blended alone. A high content of the inorganic particles is effective in suppressing shrinkage in the sintering step.

  Furthermore, the presence of the second inorganic particles in the gaps between the first inorganic particles and the relationship within a specific range provides thixotropic properties. Although the reason for the thixotropic property is not always clear, it is considered that it depends on the geometrical arrangement of the particles for the following reasons.

  In a system in which a dispersion medium made of an organic resin is highly filled with micron-order inorganic particles, the inorganic particles repel each other with a repulsive force and move to a position where the repulsive force with the particles existing in the periphery is balanced and stopped. It is considered that the structure takes a structure close to the close-packed structure. At this time, since the particles exert influence on each other and are constrained by the repulsive force, this is observed as a highly viscous state from a macro viewpoint. When an external force is applied, the network structure formed by binding the particles is broken, and the viscosity starts to decrease. The strength of the network structure depends on the geometry of the particles. Further, the relationship between the shear force corresponding to the target phenomenon and the force required to solve the network structure also plays a role in whether thixotropic property is obtained in the phenomenon.

  The preferred range of the average particle size of the second inorganic particles is 0.22 times or less the average particle size of the first inorganic particles. When the particle diameter of the first inorganic particles is 1 to 5 μm, the particle diameter of the second inorganic particles is preferably 1.1 μm or less. If it exceeds 1.1 μm, it will be too large with respect to the first inorganic particles, and the effect of increasing the content of the inorganic particles and exhibiting thixotropic properties cannot be expected. If the particle diameter of the second particles is less than 0.05 μm, the second inorganic particles are likely to agglomerate, agglomerated agglomerates are formed, and it becomes difficult to disintegrate the agglomerates. When the lower limit value of 0.05 μm is converted into a magnification for a particle size of 1 to 5 μm, the value becomes 0.05 times or less.

  The volume ratio of the second inorganic particles to the first inorganic particles is 0.01 or more. If it is less than 0.01, the effect of replacing the gap between the first inorganic particles is too small. More preferably, it is 0.1 to 0.15. In the calculation of the volume ratio, when the volume of the particles cannot be directly measured, the value of the volume calculated from the weight and the density is used. When the same type of material is used as the first inorganic particles and the second inorganic particles, the volume ratio is equal to the weight ratio.

FIG. 2 shows a close-packed state by two kinds of particles. First, a situation in which two types of inorganic particles having different particle sizes are arranged in the absence of a resin is assumed. Ideally, the arrangement of the first inorganic particles having a hexagonal close-packed structure of spherical particles is assumed, and the second inorganic particles having a small particle size are inscribed between the first inorganic particles. And a dense structure can be realized.
FIG. 2 shows a state of close packing by two different particles, in which the dotted line corresponds to the first inorganic particles and the solid line corresponds to the second inorganic particles.
The average particle size of the second inorganic particles in the state of close packing is 0.22 times the average particle size of the first inorganic particles due to geometrical considerations. At this time, the ratio of the volume ratio of the first inorganic particles to the volume ratio of the second inorganic particles is 1: 0.01.
<Each component of slurry>
Metal particles and ceramic particles can be used as the inorganic particles. As the ceramic material, for example, alumina can be used, but silica, zirconia, or the like can also be used.

Although there is no particular limitation on the photocurable resin, an acrylic resin having good optical modeling accuracy, for example, an acrylic resin can be suitably used.
In order to form a fine pattern using laser light, a resin having a penetration depth of laser light of, for example, 5 to 200 [μm] can be suitably used.
In order to adjust the wettability with the inorganic particles, a surfactant may be contained.

<Verification of slurry composition and viscosity characteristics>
A slurry was prepared by changing the particle size and volume ratio of the inorganic particles, and the viscosity characteristics of the obtained slurry were verified. Alumina particles having an average particle size of 1.6 [μm] as first inorganic particles, alumina particles having an average particle size of 0.18 [μm] as second inorganic particles, and a liquid photocurable resin having the following composition Was used.
・ Methoxypropylene glycol acrylate 11.1 g
・ 4.1 g of tris (2-hydroxyethyl) isocyanurate triacrylate
0.8 g of 1-hydroxycyclohexyl phenyl ketone
・ 1.0 g of allyl ether copolymer (dispersant) manufactured by NOF Corporation
The mixing of these inorganic particles and the photo-curable resin is performed by accommodating an object to be mixed in a container, and imparting revolving and rotating motion to the container to perform agitation and defoaming treatments. Performed using the instrument.
In order to evaluate the thixotropic properties of the prepared slurry, the shear rate dependence of the viscosity was measured at a set temperature of 23 ° C. using a rheometer model MCR302ST manufactured by Anton Paar Japan, parallel plate 25 mmφ.

Various slurry samples were prepared by changing the volume ratio of the first inorganic particles, the second inorganic particles, and the photocurable resin. Table 1 summarizes the conditions of each sample.
Table 1 shows the results of determination of the thixotropic property of each sample of the slurry. The criterion is that, at a shear rate of 10 [1 / s], 50 [Pa · s] or less, and at a shear rate of 0.01 [1 / s], 500 [Pa · s] or more is OK, and the others are NG. did. In addition, when viscosity measurement was impossible (for example, when solidified), it was determined as NG.
In Table 1, a slurry containing one kind of inorganic particles having an average particle diameter is described as a comparative example.
FIG. 3 shows a comparison of the shear rate dependence of the viscosity of Samples 1, 4-10, and 12-13.

Table 1

First, as a comparative object, characteristics of a slurry using inorganic particles having one average particle diameter will be described, and then characteristics of a slurry using inorganic particles having two average particles will be described.
Sample 1 (Comparative Example 1)
As the inorganic particles, only the first inorganic particles were added to the photocurable resin at 60 vol%, and the mixture was stirred and defoamed by a revolving stirrer and mixed.
Sample 1 has thixotropy and satisfies the criterion at a high shear rate, but does not satisfy the criterion at a low shear rate as shown by X in FIG. 3 and becomes uncured as the number of layers increases. It is difficult to maintain the height of the slurry layer, and there is a risk that the shape of the formed shape is distorted due to the displacement of the height when drawing on the slurry layer, and it is difficult to use the slurry as a high-definition stereolithography slurry.

Sample 2 (Comparative Example 2)
As the inorganic particles, only the first inorganic particles were added to the photocurable resin in an amount of 65 [vol%], and the mixture was stirred and defoamed by a revolving stirrer and mixed to prepare a sample 2 slurry.
The first inorganic particles could be mixed with the photocurable resin without agglomeration, but the sample 2 after mixing was solidified and the viscosity could not be measured. Therefore, when the first inorganic particles are added to the photocurable resin alone, the threshold value at which the slurry solidifies (the minimum volume ratio at which the slurry solidifies; hereinafter, referred to as the “solidification limit value”) is 60 to 60. It can be understood that it exists in the range of 65 [vol%].
That is, the slurry of the sample 2 can maintain the shape in a stationary state, but cannot be coated with a uniform slurry layer by the recoater 4 of the optical shaping apparatus. Is difficult to use.

  From the results of Sample 1 and Sample 2, it is possible to adjust the viscosity by changing the content (volume ratio) of the inorganic particles in the composition of only the first inorganic particles, but when the content is high, the composition is applied by solidification. It can be understood that if the content is low, it is difficult to maintain the shape in a stationary state, and it is difficult to supply a slurry having thixotropic properties suitable for stereolithography with good reproducibility.

Sample 3 (Comparative Example 3)
As inorganic particles, only the second inorganic particles were added to the photocurable resin at 60 vol%, and the mixture was stirred and defoamed by a revolving stirrer and mixed to prepare Sample 3. However, the second inorganic particles were aggregated, could not be uniformly mixed with the photocurable resin, and could not be measured for viscosity.
When 65 [vol%] of the second inorganic particles was added to the photocurable resin, the second inorganic particles were similarly aggregated and could not be uniformly mixed with the photocurable resin.
From the comparison with Samples 1, 2 and 3, it is understood that even if the content ratio of the inorganic particles is the same volume ratio, mixing with the resin becomes difficult due to the finer particle size of the inorganic particles. it can.

Samples 4 to 13 (Examples and Comparative Examples)
Samples 4 to 13 are slurries obtained by changing the volume ratio of the first inorganic particles and the second inorganic particles to the photocurable resin, performing stirring and defoaming treatment by a revolving stirrer, and mixing.
In Table 1, the samples 7 to 10 and 13 in which the volume ratio of the second inorganic particles to the first inorganic particles is 0.1 or more and 0.15 or less satisfy the thixotropy determination criteria and are suitable for the stereolithography slurry. It can be understood that this is a sample. Note that Sample 11 solidified in a static state after mixing, and the viscosity could not be measured.
FIG. 3 shows samples 4 (サ ン プ ル), 5 (□), 6 (▲), 7 (●), 8 (◇), 9 (○), 10 (◆), 12 (+), and 13 (△). This shows the shear rate dependence of viscosity. Samples 4-6 and 12 have a high viscosity at a shear rate of 10 [1 / s]. Therefore, when this slurry is stretched using a recoater or the like to form a slurry layer, the coating film breaks. Occurs, and a continuous slurry layer cannot be stably formed.

Comparing the samples having the same volume ratio in the vicinity of 65 [vol%], when the inorganic particles contained are only the first inorganic particles, the slurry is solidified (sample 2). If only the second inorganic particles are used, the slurry itself cannot be prepared because of the particle size at which aggregation is likely to occur (sample 3). However, when the first inorganic particles and the second inorganic particles are used in combination, a slurry having viscosity in both the low-speed region (<1 [1 / s]) and the high-speed region (> 1 [1 / s]) is obtained. (Sample 4). However, at this stage, the viscosity in the high-speed range is still too high to produce a high-precision optically formed object using this slurry, which is not appropriate. There are regions where a slurry that achieves good thixotropic properties can be obtained by increasing the ratio of the second particles (samples 7 to 10, 13). At this time, the volume ratio of the first particles is the same as that of the sample containing the inorganic particles at a volume ratio (above the solidification limit value) at which the slurry solidifies when the first inorganic particles are added alone. Again, by using the first inorganic particles and the second inorganic particles in combination, it is possible to obtain a slurry having a good thixotropy (OK is determined).
Since Samples 7 to 10 and 13 contain inorganic particles at a higher content than Samples 1 and 2 composed of only the first inorganic particles, if a stereolithographic product is manufactured using these samples, a photocured product is obtained. Since the density of the inorganic particles therein is high, that is, the resin component removed during the removal and sintering steps is small, shrinkage during sintering can be reduced.

  From the above results, it is preferable that the total volume ratio of the first inorganic particles and the second inorganic particles is 65 to 70 [vol%]. Further, according to the combination of the inorganic particles in the present invention, a slurry suitable for producing an optically shaped article having good thixotropy even at the above volume ratio can be provided.

  In addition, the particle diameter of the second inorganic particles with respect to the particle diameter of the first inorganic particles (average particle diameter 1.6 μm) is 0.22 times or less, preferably 0.11 times (average particle diameter 0.18 [ μm]) and setting the volume ratio of the second inorganic particles to the volume ratio of the first inorganic particles to 0.10 to 0.15 to obtain a slurry that can be used for high-precision stereolithography. Can be.

  In addition, according to the slurry of the present invention, the slurry can be applied to the molding stage of the optical molding apparatus in a stable state in which the shear rate has a small dependence on the shear rate of the viscosity in a high-speed region.

<Conclusion>
In the photocurable resin, fine first inorganic particles having a particle size of 1 to 5 [μm] and a second inorganic particle having a particle size of 0.22 times or less and 0.05 times or more the particle size of the first inorganic particles. By mixing and dispersing with the inorganic particles of No. 2, a slurry having good thixotropic properties can be obtained.
The obtained slurry is applied at a shear rate of 10 [1 / s] or more in an optical shaping apparatus to form a thin slurry layer of 5 to 200 [μm], which is scanned into a predetermined pattern by a laser beam. By repeating this step, a photo-cured product of the cured slurry patterned into a high-definition three-dimensional shape can be manufactured. By degreasing and sintering the photocured product having the three-dimensional structure in which the slurry is cured, a three-dimensional photolithographic product can be manufactured with good reproducibility.

  ADVANTAGE OF THE INVENTION According to this invention, the slurry for manufacturing a high-precision three-dimensional molded object and the manufacturing method of the optical molded object using the same can be provided, and industrial applicability is high.

DESCRIPTION OF SYMBOLS 1 Slurry 1a Slurry layer 2 Dispenser 3 Auxiliary table 4 Recoater 5 Modeling table 5a Modeling surface 6 Hardened layer

Claims (6)

Including first inorganic particles, second inorganic particles and a photocurable resin,
The average particle diameter of the first inorganic particles is 1 to 5 [μm],
The average particle size of the second inorganic particles is not more than 0.22 times the average particle size of the first inorganic particles,
The volume ratio of the second inorganic particles to the first inorganic particles is 0.01 or more,
The viscosity at a shear rate of 10 [1 / s] is 50 [Pa · s] or less,
The viscosity at a shear rate of 0.01 [1 / s] is 500 [Pa · s] or more,
A slurry for stereolithography, comprising: The stereolithography slurry according to claim 1, wherein a volume ratio of the first inorganic particles is equal to or more than a solidification limit value. The stereolithography slurry according to claim 1, wherein a volume ratio of the first inorganic particles to the second inorganic particles is 65 to 70 [vol%]. The stereolithography slurry according to any one of claims 1 to 3, wherein a volume ratio of the second inorganic particles to the first inorganic particles is 0.10 to 0.15. A first step of discharging the stereolithography slurry according to any one of claims 1 to 4,
A second step of extending the stereolithography slurry to form a slurry layer having a thickness of 5 to 200 [μm];
A third step of irradiating the slurry layer with a laser beam by scanning in a predetermined pattern shape;
Repeating the first, second, and third steps to form a photocured product from the slurry layer;
A first heat treatment step of heat treating the photocured material to remove the photocurable resin;
A second heat treatment step of heat-treating and sintering the photocured product after the first heat treatment step.   The method according to claim 5, wherein in the first step or in the first and second steps, the temperature of the slurry is maintained at 35 to 60C.

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