Additive molding material, molded body, and method for manufacturing a molded body.

Abstract

The present invention provides an additive molding material capable of producing highly strong molded bodies, a molded body produced using the molding material, and a method for manufacturing the molded body. [Solution] A molding material for additive molding comprising aggregate, inorganic binder, and organic binder, satisfying the following formula: (-0.700)×W1+(-0.697)×W2+(-0.699)×W3+(-0.724)×W4+(-0.029)×P1+(0.420)×C1+(73.4)>3.00 [W1, W2, W3, and W4 are the mass ratios of aggregate with particle sizes greater than 75 μm and 106 μm or less, greater than 53 μm and 75 μm or less, greater than 38 μm and 53 μm or less, and 38 μm or less, respectively; P1 is the D50 (μm) of the organic binder; and C1 is the mass ratio of inorganic binder to the total amount of molding material]; and a molded body using the molding material and a method for manufacturing a molded body.

Description

[Technical Field]

[0001] This disclosure relates to additive manufacturing materials, molded bodies, and methods for manufacturing molded bodies. [Background technology]

[0002] In the fabrication of three-dimensional products, additive manufacturing is known, which involves creating an object from three-dimensional shape data by continuously joining materials. One type of additive manufacturing is a method called powder bed deposition (PAD) (see, for example, Patent Documents 1 and 2). In PAD, a molding liquid is supplied to a powdered molding material using an inkjet method to form layers having the cross-sectional shape of a three-dimensional product, and these layers are combined to manufacture the molded object. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] International Publication No. 2018 / 212310 [Patent Document 2] International Publication No. 2020 / 122109 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] In additive manufacturing using molding materials, it is desirable for the strength of the molded object to be as high as possible in order to prevent the destruction of the molded object as much as possible. However, to date, there is no knowledge regarding the formulation of molding materials that can produce molded objects with high strength. In view of these circumstances, this disclosure relates to a molding material for additive manufacturing that can produce molded objects with high strength, a molded object produced by the molding material, and a method for producing the molded object. [Means for solving the problem]

[0005] The means for solving the above problems include the following embodiments. <1> Additive molding material comprising aggregate, inorganic binder, and organic binder, and satisfying the following formula. Formula: (-0.700)×W1+(-0.697)×W2+(-0.699)×W3+(-0.724)×W4+(-0.029)×P1+(0.420)×C1+(73.4)>3.00 W1: Mass ratio (mass%) of aggregate with a particle size between 75 μm and 106 μm relative to the total amount of aggregate. W2: Mass ratio (mass%) of aggregate with a particle size between 53 μm and 75 μm relative to the total amount of aggregate. W3: Mass ratio (mass%) of aggregate with a particle size greater than 38 μm and less than or equal to 53 μm relative to the total amount of aggregate. W4: Mass ratio (mass%) of aggregate with a particle size of 38 μm or less relative to the total amount of aggregate. P1: Median diameter D50 (μm) of the organic binder. C1: Mass ratio (mass%) of the inorganic binder to the total amount of the molding material. <2> The inorganic binder includes alumina cement containing 50% by mass or more of Al2O3. <1> The additive molding material described above. <3> The organic binder contains polyvinyl alcohol. <1> or <2> The additive molding material described above. <4> The organic binder is made of polyvinyl alcohol. <1> ~ <3> Additive molding material as described in any one of the items. <5> The polyvinyl alcohol has a viscosity of 25 mPa·s or more at 20°C when it is a 4% by mass aqueous solution. <3> or <4> The additive molding material described above. <6> The degree of saponification of the polyvinyl alcohol is 70-93%. <3> ~ <5> Additive molding material as described in any one of the items. <7> The mass ratio (C1) of the inorganic binder to the total amount of the molding material is 1.5 to 15% by mass. <1> ~ <6> Additive molding material as described in any one of the items. <8> The mass ratio of the aggregate to the total amount of the molding material is 80 to 96% by mass. <1> ~ <7> Additive molding material as described in any one of the items. <9> The mass ratio of the organic binder to the total amount of the molding material is 0.5 to 5% by mass. <1> ~ <8> Additive molding material as described in any one of the items. <10> The BET specific surface area of ​​the aforementioned aggregate is 0.90 m². 2 It is less than or equal to / g. <1> ~ <9> Additive molding material as described in any one of the items. <11> The mass ratio (W1) of aggregates with a particle size greater than 75 μm and less than or equal to 106 μm relative to the total amount of aggregate, and the mass ratio (W2) of aggregates with a particle size greater than 53 μm and less than or equal to 75 μm relative to the total amount of aggregate, are both 80% by mass or less. <1> ~ <10> Additive molding material as described in any one of the items. <12> The mass ratio of aggregate with a particle size greater than 106 μm to the total amount of aggregate is 10% by mass or less. <1> ~ <11> Additive molding material as described in any one of the items. <13> The median diameter D50(P1) of the aforementioned organic binder is 50 μm or less. <1> ~ <12> Additive molding material as described in any one of the items. <14> Furthermore, the material contains lithium carbonate, which is a curing accelerator, in an amount of 0.05 to 0.5% by mass relative to the total amount of the molding material. <1> ~ <13> Additive molding material as described in any one of the items. <15> The following conditions are met: <1> ~ <14> Additive molding material as described in any one of the items. Formula: (-0.700)×W1+(-0.697)×W2+(-0.699)×W3+(-0.724)×W4+(-0.029)×P1+(0.420)×C1+(73.4)>4.00 <16> By the powder bonding lamination method, <1> ~ <15> A method for manufacturing a molded body, comprising curing and laminating an additive molding material described in any one of the items. [Effects of the Invention]

[0006] This disclosure provides an additive manufacturing material capable of producing high-strength molded bodies, a molded body produced using the manufacturing material, and a method for manufacturing the molded body. [Modes for carrying out the invention]

[0007] Hereinafter, modes for carrying out embodiments of the present disclosure will be described in detail. However, embodiments of the present disclosure are not limited to the following embodiments. In the following embodiments, the constituent elements (including element steps and the like) are not essential unless otherwise explicitly stated. The same applies to numerical values and their ranges, which do not limit the embodiments of the present disclosure.

[0008] In the present disclosure, the term "process" includes not only a process independent of other processes, but also a process that cannot be clearly distinguished from other processes, as long as the purpose of the process is achieved. In the present disclosure, the numerical range indicated by using "~" includes the numerical values described before and after "~" as the minimum value and the maximum value, respectively. In the present disclosure, each component may contain a plurality of types of corresponding substances. When a plurality of types of substances corresponding to each component are present in the composition, the content rate or content of each component means the total content rate or content of the plurality of types of substances present in the composition, unless otherwise specified. In the present disclosure, a plurality of types of particles corresponding to each component may be included. When a plurality of types of particles corresponding to each component are present in the composition, the particle diameter of each component means a value for a mixture of the plurality of types of particles present in the composition, unless otherwise specified.

[0009] <<<Shaping Material for Additive Manufacturing>> The shaping material for additive manufacturing of the present disclosure includes an aggregate, an inorganic binder, and an organic binder, and satisfies the following formula. Formula: (-0.700)×W1+(-0.697)×W2+(-0.699)×W3+(-0.724)×W4+(-0.029)×P1+(0.420)×C1+(73.4)>3.00 W1: mass ratio (mass%) of aggregates having a particle diameter of more than 75 µm and 106 µm or less relative to the total amount of the aggregates W2: mass ratio (mass%) of aggregates having a particle diameter of more than 53 µm and 75 µm or less relative to the total amount of the aggregates W3: mass ratio (mass%) of aggregates having a particle diameter of more than 38 µm and 53 µm or less relative to the total amount of the aggregates W4: mass ratio (mass%) of aggregates having a particle diameter of 38 µm or less relative to the total amount of the aggregates P1: Median diameter D50 (μm) of the organic binder C1: Mass ratio (mass%) of the inorganic binder relative to the total amount of the modeling material

[0010] Hereinafter, the value obtained by the formula: (-0.700)×W1+(-0.697)×W2+(-0.699)×W3+(-0.724)×W4+(-0.029)×P1+(0.420)×C1+(73.4) is also referred to as "M value". All of the aggregate, the inorganic binder, and the organic binder in the modeling material are in particle shape.

[0011] The modeling material of the present disclosure is used for additive manufacturing, and is particularly suitably used for the powder bed binding lamination method. Additive manufacturing is a technique for producing an article from three-dimensional shape data by continuously bonding materials. The inventors of the present invention studied the formulation of a modeling material for obtaining a modeled article with high strength, and attempted to develop a modeling material. As a result, they found that there is a correlation between the M value and the strength of the modeled article, and a modeled article with high strength can be obtained when the M value exceeds 3.00. There is a tendency that the larger the M value, the higher the strength of the modeled article after modeling. The modeling material of the present disclosure is not limited by the following theory, but the reason is presumed as follows. W1 to W4 used for calculating the M value represent the mass ratio of the aggregate in each fraction relative to the total amount of aggregate when the aggregate is divided into four fractions according to particle diameter. It is considered that the mass ratio of particles in each of these fractions affects the strength of the obtained modeled article. For example, as compared with W1 to W3, an increase in the value of W4, which is the mass ratio of the aggregate in the smallest particle diameter fraction, contributes relatively greatly to a decrease in the M value. This is considered to indicate that W4 has a relatively large influence on the decrease in the strength of the modeled article. This is presumed to be caused, for example, by the fact that small-diameter aggregate particles are less likely to roll and move when arranged in layers, and are less likely to be densely packed. P1 is the median diameter of the organic binder. The particle size of the organic binder is thought to affect the packing of the aggregate, and consequently, the strength of the molded object. For example, it is thought that the smaller the median diameter of the organic binder, the more densely the aggregate is packed, and as a result, the strength of the molded object tends to improve. C1 is the mass ratio of inorganic binder to the total amount of molding material. The mass ratio of inorganic binder is also thought to affect the strength of the molded object. For example, it is thought that the higher the mass ratio of inorganic binder, the higher the curing properties, and as a result, the strength of the molded object tends to improve. As described above, the strength of the molded object is thought to be influenced in various ways by the particle size, mass ratio, etc., of each component of the molding material. The inventors have found that by considering the elements W1-W4, P1, and C1, the strength of the resulting molded object can be increased.

[0012] The M value in the molding material of this disclosure is greater than 3.00, more preferably greater than 4.00, even more preferably greater than 5.00, particularly preferably greater than 6.00, and extremely preferably greater than 7.00. There is no particular upper limit to the M value, but the M value is preferably 20.00 or less, more preferably 15.00 or less, and even more preferably 10.00 or less.

[0013] W1 to W4 are confirmed as follows: Prepare metal mesh sieves with mesh sizes of 38 μm, 53 μm, 75 μm, and 106 μm, in accordance with JIS Z8801-1:2019. Assemble a multi-stage sieve by stacking the sieves with mesh sizes of 38 μm, 53 μm, 75 μm, and 106 μm in order from vertically downwards. Classify aggregate (e.g., 30 g) by passing it through this sieve and confirm the particle size. Collect aggregate from below the 38 μm sieve, above the 38 μm sieve, above the 53 μm sieve, above the 75 μm sieve, and above the 106 μm sieve, weigh each, and calculate the mass percentage. The mass percentage below the 38 μm sieve is taken as W1, the mass percentage above the 38 μm sieve as W2, the mass percentage above the 53 μm sieve as W3, and the mass percentage above the 75 μm sieve as W4.

[0014] W1 is 0% by mass or more. From the viewpoint of obtaining a molded body with high strength, it is preferably 5% by mass or more, more preferably 10% by mass or more, even more preferably 20% by mass or more, particularly preferably 30% by mass or more, and extremely preferably 40% by mass or more. From the viewpoint of not increasing the fluidity of the molding material too much and not reducing the molding yield, W1 is preferably 80% by mass or less, more preferably 70% by mass or less, even more preferably 65% ​​by mass or less, and particularly preferably 60% by mass or less. W2 is 0% by mass or more. From the viewpoint of obtaining a molded body with high strength, it is preferably 5% by mass or more, more preferably 10% by mass or more, even more preferably 20% by mass or more, particularly preferably 30% by mass or more, and extremely preferably 40% by mass or more. From the viewpoint of not increasing the fluidity of the molding material too much and not reducing the molding yield, W2 is preferably 80% by mass or less, more preferably 70% by mass or less, even more preferably 65% ​​by mass or less, and particularly preferably 60% by mass or less. W3 is 0% by mass or more, and from the viewpoint of improving yield during printing of the molded body, it is preferably 10% by mass or more, more preferably 20% by mass or more, and even more preferably 30% by mass or more. From the viewpoint of obtaining a molded body with high strength, W3 is preferably 90% by mass or less, more preferably 80% by mass or less, and even more preferably 70% by mass or less. W4 is 0% by mass or more, and from the viewpoint of shape accuracy of the molded body, it is preferably 20% by mass or more, more preferably 30% by mass or more, and even more preferably 40% by mass or more. From the viewpoint of obtaining a molded body with high strength, W4 is preferably 97% by mass or less, more preferably 80% by mass or less, and even more preferably 70% by mass or less. Furthermore, at least one of W1 to W4 has a mass of more than 0%.

[0015] In one embodiment, it is preferable that both W1 and W2 are 80% by mass or less, more preferably 75% by mass or less, even more preferably 70% by mass or less, particularly preferably 65% ​​by mass or less, and extremely preferably 60% by mass or less. When both W1 and W2 are within the above range, the molding yield is less likely to decrease.

[0016] P1 is preferably 95 μm or less, more preferably 90 μm or less, even more preferably 80 μm or less, even more preferably 70 μm or less, even more preferably 60 μm or less, particularly preferably 50 μm or less, and extremely preferably 40 μm or less. The smaller P1 is, the more likely it is that the strength and shape accuracy of the molded object produced by the molding material will improve. It also tends to improve resistance to strength reduction under high humidity conditions. There is no particular upper limit on P1, but from the standpoint of raw material procurement costs, P1 is preferably 20 μm or larger, more preferably 25 μm or larger, and even more preferably 30 μm or larger. The median diameter of the organic binder P1 is the median diameter D50, which is the particle size where the cumulative percentage from the smallest particle size to the largest in the volume-based particle size distribution measured by dry measurement using a laser diffraction particle size distribution analyzer is 50%.

[0017] C1 is the mass ratio of the inorganic binder to the total amount of molding material, and can be obtained by calculation using a value weighed with an electronic balance or the like.

[0018] C1 is preferably 1.5% by mass or more, more preferably 2% by mass or more, even more preferably 3% by mass or more, particularly preferably 4% by mass or more, and extremely preferably 5% by mass or more. When the mass percentage of the inorganic binder is above the lower limit, the strength of the molded body is increased and the decrease in the yield of molded body production is suppressed. C1 is preferably 15% by mass or less, more preferably 14% by mass or less, even more preferably 13% by mass or less, particularly preferably 12% by mass or less, and extremely preferably 11% by mass or less. When the mass percentage of the inorganic binder is below the above upper limit, it is easy to remove the uncured molding material after molding the molded body, resulting in excellent workability. From this viewpoint, C1 is preferably 1.5 to 15% by mass, more preferably 2 to 14% by mass, even more preferably 3 to 13% by mass, particularly preferably 4 to 12% by mass, and very preferably 5 to 11% by mass. The following describes the components contained in the molding material.

[0019] <Aggregates> The molding material includes aggregate. Examples of aggregate include inorganic material particles such as ceramic particles and glass particles. One type of aggregate may be used alone, or two or more types may be used in combination.

[0020] Suitable ceramic particles include silica, alumina, zirconia, magnesia, calcia, yttria, multiple types of these, or composite oxides containing one or more of these and other types in a single particle, such as steatite, forsterite, mullite, cordierite, zircon, barium titanate, and silicon nitride, boron nitride, silicon carbide, aluminum nitride, etc. As ceramic particles, spherical molten particles, which are particles formed by melting ceramic raw materials and shaping them into spheres, and granulated sintered particles, which are particles formed by granulating and sintering primary particles such as ceramic powder or ceramic clay into a spherical shape, may be used. When using foundry sand as ceramic particles, either natural or synthetic foundry sand may be used, and either new or recycled sand may be used. Specifically, examples include FINE-Bz (manufactured by AGC Ceramics Inc.), Lunamos (manufactured by Kao Quaker Co., Ltd.), AR SAND (manufactured by Gun-ei Chemical Industry Co., Ltd.), Naigai Cerabeads (manufactured by Itochu Ceratec Co., Ltd.), zircon sand, chromite sand, Espearl (manufactured by Yamakawa Sangyo Co., Ltd.), Mi Casting Sand (manufactured by Mitsubishi Corporation Building Materials Co., Ltd.), spherical molten silica, silica sand, and silica sand processed into spheres. Examples of glass particles include fused silica glass, alkali-free glass, soda-lime glass, aluminosilicate glass, borosilicate glass, aluminoborosilicate glass, and crystallized glass.

[0021] In particular, as the foundry sand, refractory particles containing 75% to 97% by mass of at least one selected from the group consisting of ZrO2 and Al2O3 as chemical components, and 2% to 25% by mass of SiO2, such as FINE-Bz, are preferred from the viewpoint of high refractoriness, high thermal conductivity, and high molding strength. It is also preferable to mix the refractory particles with other aggregates. When the refractory particles are mixed with other aggregates, the mass ratio of the refractory particles to the total amount of aggregate may be 10% by mass or more, 30% by mass or more, 50% by mass or more, 70% by mass or more, or 90% by mass or more. Furthermore, as foundry sand, from the viewpoint of high refractoriness and low thermal expansion, amorphous refractory particles containing 97% by mass or more of SiO2 as a chemical component, such as amorphous spherical silica particles obtained by melting, spheroidizing, and rapidly cooling crushed silica particles in a flame, are preferred. It is also preferable to mix the refractory particles with other aggregates. When the refractory particles are mixed with other aggregates, the mass ratio of the refractory particles to the total amount of aggregate may be 10% by mass or more, 30% by mass or more, 50% by mass or more, 70% by mass or more, or 90% by mass or more.

[0022] The median diameter of the aggregate particles is preferably 5 μm or larger, more preferably 10 μm or larger, and even more preferably 20 μm or larger. When the median diameter of the aggregate is equal to or greater than the lower limit, the fluidity of the aggregate is good, making it easier to perform molding appropriately. The median diameter of the aggregate is preferably 90 μm or less, more preferably 75 μm or less, and even more preferably 50 μm or less. When the median diameter of the aggregate is below the above upper limit, the surface roughness of the molded product does not become too large, making it easier to obtain a precise molded product. The median diameter of aggregate particles is defined as the median diameter D50, which is the particle size where the cumulative percentage from the smallest particle size to the largest in the volume-based particle size distribution measured by a laser diffraction particle size distribution analyzer is 50%.

[0023] The maximum aggregate particle size is preferably 150 μm or less, more preferably 106 μm or less, and even more preferably 100 μm or less. When the maximum aggregate particle size is below the above upper limit, the surface roughness of the molded product does not become too large, making it easier to obtain a precise molded product. The maximum particle size of the aggregate may be 38 μm or larger, 53 μm or larger, or 75 μm or larger.

[0024] In another embodiment, the mass ratio of aggregate with a particle size greater than 106 μm to the total amount of aggregate is preferably 10% by mass or less, more preferably 5% by mass or less, even more preferably 3% by mass or less, particularly preferably 2% by mass or less, and extremely preferably 1% by mass or less. The smaller the mass ratio of aggregate with a particle size greater than 106 μm to the total amount of aggregate, the more likely it is that the yield of the molded body produced by the molding material will improve. When the mass ratio of aggregate with a particle size greater than 106 μm to the total amount of aggregate is small, when the 3D printer is used to build up layers at a layer height of 100 μm, it is possible to suppress the destruction of the molded body due to drag marks caused by coarse aggregate particles greater than 106 μm during the grinding operation, which can reduce the yield. The maximum aggregate particle size is D100, which is the particle size where the cumulative percentage from the smallest particle size to the largest in the volume-based particle size distribution measured by a laser diffraction particle size distribution analyzer is 100%.

[0025] From the perspective of obtaining a highly strong molded object, the BET specific surface area of ​​the aggregate should be 0.90 m². 2 Preferably less than / g, and 0.50m 2 Less than / g is more preferable, and 0.30m 2 More preferably less than or equal to / g, and 0.15m 2 A value of 0.10m or less is particularly preferred. 2 A value of less than / g is extremely preferable. The lower the BET specific surface area, the higher the density of the aggregate and the stronger the aggregate itself tends to be. There is no particular lower limit to the BET specific surface area of ​​the aggregate; for example, a BET specific surface area of ​​0.02m² is preferable. 2 It may be more than / g. The BET specific surface area is determined by the BET method based on nitrogen adsorption using a BET specific surface area measuring device (for example, FlowSorbII 2300, manufactured by Micromerities, Inc., USA).

[0026] From the viewpoint of suppressing shrinkage deformation when firing the molded body, the mass ratio of aggregate to the total amount of molding material is preferably 80% by mass or more, more preferably 85% by mass or more, and even more preferably 88% by mass or more. From the viewpoint of obtaining a molded body with high strength, the mass ratio of aggregate to the total amount of molding material is preferably 96% by mass or less, more preferably 94% by mass or less, and even more preferably 92% by mass or less. From this viewpoint, the mass ratio of aggregate to the total amount of molding material is preferably 80 to 96% by mass, more preferably 85 to 96% by mass, even more preferably 88 to 96% by mass, particularly preferably 88 to 94% by mass, and extremely preferably 88 to 92% by mass.

[0027] <Organic binder> The molding material includes an organic binder. The organic binder is an organic substance that has the function of binding aggregates together during the molding process. In the case of additive manufacturing processes using water-based inks, a water-soluble resin is preferred as the organic binder, such as polyvinyl alcohol, carboxymethylcellulose, or dextrin. One type of organic binder may be used alone, or two or more types may be used in combination. In one embodiment, the organic binder preferably contains polyvinyl alcohol. When the organic binder contains polyvinyl alcohol, it is preferable that the polyvinyl alcohol is present in an amount of 50% by mass, more preferably 60% by mass or more, even more preferably 70% by mass or more, particularly preferably 80% by mass or more, and extremely preferably 90% or more, based on the total amount of the organic binder. It is also preferable to use polyvinyl alcohol alone as the organic binder.

[0028] From the viewpoint of the shape accuracy of the molded body, the maximum particle size of the organic binder is preferably 500 μm or less, more preferably 200 μm or less, and even more preferably 150 μm or less. The maximum particle size of the organic binder may be 50 μm or more, 70 μm or more, or 90 μm or more. The maximum particle size of the organic binder is D100, which is the particle size where the cumulative percentage from the smallest particle size to the largest in the volume-based particle size distribution measured by dry measurement using a laser diffraction particle size distribution analyzer is 100%. The median diameter of the organic binder is as described above.

[0029] The viscosity of a 4% by mass aqueous solution of polyvinyl alcohol at 20°C is preferably 3 mPa·s or higher, more preferably 5 mPa·s or higher, even more preferably 20 mPa·s or higher, even more preferably 25 mPa·s or higher, particularly preferably 30 mPa·s or higher, and extremely preferably 40 mPa·s or higher. The higher the viscosity, the more the water resistance of the molded body produced by the molding material tends to improve, and the more resistant it is to strength reduction under high humidity. Conversely, the lower the viscosity, the less the water resistance of the molded body produced by the molding material decreases, and when immersed in a silica sol solution, the polyvinyl alcohol tends to dissolve due to the influence of moisture, and a gloss due to silica gel residue tends to remain on the surface of the molded body. The viscosity is preferably 300 mPa·s or less, more preferably 200 mPa·s or less, even more preferably 100 mPa·s or less, and particularly preferably 50 mPa·s or less. When the viscosity is below the upper limit, the water resistance of the polyvinyl alcohol does not become too high, and when the molding liquid is added to the molding material to produce a molded body, the polyvinyl alcohol dissolves well, and a molded body with high strength tends to be obtained. The viscosity is measured by the rotational viscometer method specified in JIS K6726:1994.

[0030] The degree of saponification of polyvinyl alcohol is preferably 93 mol% or less, more preferably 92 mol% or less, even more preferably 91 mol% or less, particularly preferably 90 mol% or less, and extremely preferably 89 mol% or less. When the degree of saponification of polyvinyl alcohol is below the above upper limit, the water resistance of the polyvinyl alcohol does not become too high, and when a molding liquid is added to the molding material to produce a molded body, the polyvinyl alcohol dissolves well, and a molded body with high strength tends to be obtained. There is no particular lower limit to the degree of saponification of polyvinyl alcohol; the degree of saponification may be 70 mol% or higher, 80 mol% or higher, or 86 mol% or higher. From this viewpoint, the degree of saponification of polyvinyl alcohol is preferably 70-93 mol%, more preferably 80-92 mol%, even more preferably 86-91 mol%, particularly preferably 86-90 mol%, and most preferably 86-89 mol%. The degree of saponification is determined by the method specified in JIS K6726:1994.

[0031] The organic binder contained in the molding material has the function of binding aggregates together during the molding process. From the viewpoint of obtaining a molded body with high strength, the mass ratio of the organic binder to the total amount of molding material is preferably 0.1% by mass or more, more preferably 0.2% by mass or more, and even more preferably 0.5% by mass or more. If the organic binder content in the molding material is too high, the aggregate density in the printed object tends to decrease, resulting in a lower strength. From the viewpoint of obtaining a high-strength object, the mass ratio of the organic binder to the total amount of molding material is preferably 9% by mass or less, more preferably 7% by mass or less, and even more preferably 5% by mass or less. From this viewpoint, the mass ratio of the organic binder to the total amount of molding material is preferably 0.1 to 9% by mass, more preferably 0.2 to 7% by mass, and even more preferably 0.5 to 5% by mass.

[0032] <Inorganic binder> The molding material includes an inorganic binder. The inorganic binder is an inorganic substance that has the function of binding aggregates together during the molding process. Examples of inorganic binders include Portland cement, alumina cement, rapid-setting cement, phosphate cement, water glass, phosphate compounds, metal alkoxide materials, aluminum sulfate, sulfates such as magnesia sulfate, and chlorides including polyaluminum chloride. One type of inorganic binder may be used alone, or two or more types may be used in combination.

[0033] In one embodiment, alumina cement is preferred as the inorganic binder, and it is also preferred to use alumina cement alone (the inorganic binder consists of alumina cement). The Al2O3 content of the alumina cement is preferably 50% by mass or more, more preferably 55% by mass or more, even more preferably 60% by mass or more, particularly preferably 65% ​​by mass or more, and extremely preferably 70% by mass or more. The higher the Al2O3 content in the cement, the better the heat resistance of the molded body made with the molding material tends to be. Heat resistance can be evaluated by the amount of shrinkage and deformation during heat treatment. The smaller the amount of shrinkage and deformation during heat treatment, the higher the heat resistance can be evaluated. There is no particular upper limit to the Al2O3 content in alumina cement; the Al2O3 content may be 90% by mass or less, 85% by mass or less, or 80% by mass or less.

[0034] Alumina cement may contain components other than Al2O3, such as SiO2 and CaO. If the alumina cement contains SiO2, the SiO2 content in the alumina cement may be 0.1% by mass or more, 0.5% by mass or more, or 1% by mass or more. Furthermore, the SiO2 content in the alumina cement may be 10% by mass or less, 5% by mass or less, or 2% by mass or less. If the alumina cement contains CaO, the CaO content in the alumina cement may be 10% by mass or more, 15% by mass or more, or 20% by mass or more. Furthermore, the CaO content in the alumina cement may be 50% by mass or less, 45% by mass or less, or 40% by mass or less. In one embodiment, the alumina cement may contain Al2O3, SiO2, and CaO.

[0035] From the perspective of the initial strength of the produced shaped article, the median diameter of the inorganic binder particles is preferably 20 µm or less, more preferably 15 µm or less, and still more preferably 10 µm or less. The median diameter of the inorganic binder particles is preferably 1 µm or more, more preferably 3 µm or more, and still more preferably 5 µm or more. When the median diameter of the inorganic binder particles is equal to or more than the above lower limit, there tends to be excellent workability when removing uncured molding material after printing the shaped article with a 3D printer. The median diameter of the inorganic binder is the median diameter D50, which is the particle diameter at which the cumulative percentage from the smaller particle diameter side is 50% in a volume-based particle size distribution measured by a laser diffraction particle size distribution analyzer.

[0036] From the perspective of obtaining a shaped article with high strength, the maximum particle diameter of the inorganic binder is preferably 150 µm or less, more preferably 106 µm or less, and still more preferably 100 µm or less. The maximum particle diameter of the inorganic binder may be 38 µm or more, 53 µm or more, or 75 µm or more. The maximum particle diameter of the inorganic binder is D100, which is the particle diameter at which the cumulative percentage from the smaller particle diameter side is 100% in a volume-based particle size distribution measured by a laser diffraction particle size distribution analyzer.

[0037] The Blaine specific surface area of the inorganic binder is 4000 cm 2 / g or more, preferably 4500 cm 2 / g or more, more preferably 4900 cm 2 / g or more, even more preferably 5000 cm 2 / g or more, particularly preferably. The larger the Blaine specific surface area, the smaller the particle diameter of the inorganic binder, which facilitates promotion of the hydration reaction and tends to reduce the amount of bleeding. Further, the larger the Blaine specific surface area, the higher the initial strength of the produced shaped article tends to be. The upper limit of the Blaine specific surface area is not particularly limited, and the Blaine specific surface area may be 6000 cm 2 / g or less, 5800 cm 2 / g or less, or 5500 cm 2 / g or less. The Blaine specific surface area is measured using a Blaine air permeability device as specified in JIS R5201:2015.

[0038] The mass ratio of inorganic binder to the total amount of molding material is as described above.

[0039] <Curing accelerator> The molding material may contain a curing accelerator. The curing accelerator is a component that accelerates the hardening of the inorganic binder. Examples of curing accelerators include lithium salts or quicklime. Examples of lithium salts include lithium carbonate, lithium bicarbonate, lithium nitrate, lithium sulfate, lithium phosphate, and lithium oxalate, with lithium carbonate being preferred from the viewpoint of availability and stability. When the molding material contains a curing accelerator, the hardening rate of the inorganic binder increases, improving the production efficiency of the molded object. One type of curing accelerator may be used alone, or two or more types may be used in combination.

[0040] From the viewpoint of accelerating curing, the content of the curing accelerator (e.g., lithium carbonate) is preferably 0.05% by mass or more, more preferably 0.07% by mass or more, and even more preferably 0.09% by mass or more, relative to the total amount of molding material. When the heat resistance of the molded body is important, from the viewpoint of improving heat resistance, the content of the curing accelerator (e.g., lithium carbonate) is preferably 0.5% by mass or less, more preferably 0.4% by mass or less, and even more preferably 0.3% by mass or less. From this viewpoint, the content of the curing accelerator (e.g., lithium carbonate) is preferably 0.05 to 0.5% by mass, more preferably 0.07 to 0.4% by mass, and even more preferably 0.09 to 0.3% by mass.

[0041] From the viewpoint of obtaining a highly durable molding material, the maximum particle size of the curing accelerator is preferably 150 μm or less, more preferably 106 μm or less, and even more preferably 100 μm or less. The maximum particle size of the curing accelerator may also be 38 μm or more, 53 μm or more, or 75 μm or more.

[0042] <Other ingredients> The molding material may contain other components. The molding material may contain functional components, such as silica fume, magnesia ultrafine powder, heat-resistant resin, etc. The molding material may also contain a modifier, such as sodium silicate, that suppresses the penetration of moisture into surrounding areas when water is added.

[0043] <<Shaped object and method for manufacturing the shaped object>> A molded body in one aspect of this disclosure is obtained by curing and laminating the molding material of this disclosure as described above. A method for manufacturing a molded body in one aspect of this disclosure includes curing and laminating the molding material of this disclosure as described above.

[0044] In one embodiment, the molded body is manufactured by powder bed deposition. In powder bed deposition, a molding material is placed on a substrate, and a molding liquid is supplied based on the cross-sectional shape of the three-dimensional shape data to harden the molding material, thereby creating a layer having the cross-sectional shape of the molded body. Next, a new cross-sectional shape is created on the surface of the hardened layer in the same manner, and this process is repeated to create the shape of the molded body. The layer height, which is the height of the layer formed during one cycle of this process, may be, for example, 300 μm or less, 200 μm or less, 150 μm or less, 100 μm or less, 75 μm or less, 50 μm or less, or 30 μm or less. The layer height may be 30 μm or more, 50 μm or more, 75 μm or more, 100 μm or more, 150 μm or more, 200 μm or more, or 300 μm or more. While productivity improves with increasing layer height, shape accuracy tends to be compromised. Conversely, productivity decreases with decreasing layer height, but shape accuracy tends to improve. From the viewpoint of achieving both shape accuracy and productivity for the fabricated object, a layer height of, for example, 50 to 150 μm is preferred, and 100 μm is more preferred.

[0045] Molding liquids are used as functional agents to bind inorganic binders together. Examples of molding liquids include water-based inks, which primarily contain water. Water-based inks may consist of water alone, or they may contain other components in addition to water. Other components may include thickeners, surfactants, preservatives, pH adjusters, colorants, defoamers, and inhibitors to suppress temperature rise.

[0046] The water content relative to the total amount of water-based ink is preferably 80% by mass or more, more preferably 85% by mass or more, and may be 90% by mass or more. The water content relative to the total amount of water-based ink may be 99% by mass or less, 97% by mass or less, or 95% by mass or less.

[0047] Examples of surfactants include acetylene glycol-based surfactants, silicone-based surfactants, fluorine-based surfactants, and polyoxyalkylene alkyl ethers. When the water-based ink contains a surfactant, the surfactant content relative to the total amount of water-based ink is preferably 0.01% by mass or more, more preferably 0.03% by mass or more, and even more preferably 0.05% by mass or more. The surfactant content relative to the total amount of water-based ink is preferably 2.0% by mass or less, more preferably 1.5% by mass or less, and even more preferably 1.0% by mass or less.

[0048] After creating the shape of the molded object as described above, any post-processing may be performed. For example, the molded object may be impregnated with colloidal silica or the like by immersing it in silica sol. The impregnation treatment may also be performed under reduced pressure, such as in a vacuum chamber. This process can improve the strength of the molded object and prevent moisture from penetrating to unwanted areas. When impregnating with colloidal silica, it is preferable to then fire the molded object at 400 to 1300°C.

[0049] From the viewpoint of handling in post-processing steps, the molded body preferably has a flexural stress of 3 MPa or more after drying and curing following printing, more preferably 4 MPa or more, even more preferably 5 MPa or more, and particularly preferably 6 MPa or more. The flexural stress of the molded body is measured by the method described in the examples. [Examples]

[0050] The embodiments of this disclosure will now be described in detail by reference to examples, but the embodiments of this disclosure are not limited to these examples. Examples 14, 15, 57, 58, 73, and 84 are comparative examples, while the others are examples.

[0051] [Components of molding materials] (aggregate) • Fine-Bz (product name, manufactured by AGC Ceramics) • Luna Moss (product name, manufactured by Kao Quaker Company) • Amorphous spherical silica (amorphous spherical silica produced by flame method) • Ceramic granulated sintered body A • Ceramic clay granule sintered body B • Ceramic clay granule sintered body C

[0052] As amorphous spherical silica, we used amorphous spherical silica obtained by melting silica particles in a flame, spheroidizing them, and rapidly cooling them. The component composition is shown in the table below.

[0053] [Table 1]

[0054] For the granulated and sintered clay bodies A to C, we used powder obtained by granulating Yamaka Toryo Co., Ltd.'s IMP-1 as the raw material into spherical shapes using the spray-drying method, then heat-treating it at a predetermined temperature to sinter it, and finally crushing and classifying it. The temperature and components during the heat treatment are shown in the table below.

[0055] [Table 2]

[0056] The aforementioned aggregates were separated into fractions consisting of components below the 106 μm mesh and above the 75 μm mesh, components below the 75 μm mesh and above the 53 μm mesh, components below the 53 μm mesh and above the 38 μm mesh, and components below the 38 μm mesh by sieving classification using meshes with openings of 106 μm, 75 μm, 53 μm, and 38 μm. These components were weighed and mixed using an electronic balance to achieve the W1, W2, W3, and W4 ratios listed in the "Mass Percentage (Mass%) of Particle Size in Aggregate" for each example in Tables 5 to 13. Mixing was performed using a Kanto Mixer (manufactured by Kanto Mixing Machine Industry Co., Ltd.) HPi-60LAS at approximately 98 rpm for 10 minutes, under the condition that the total weight at the time of mixing was between 20 kg and 50 kg. The BET specific surface area of ​​the resulting mixed aggregates is shown for each example in Tables 5 to 13.

[0057] (Inorganic binder) • Alumina cement (Product name: Asahi Alumina Cement No. 1, manufactured by AGC Ceramics Co., Ltd.) • Alumina cement (product name: HAC-H, manufactured by Denka Co., Ltd.) • Alumina cement (product name: UAC-70N, manufactured by Union) • Alumina cement (product name: Sekar XR, manufactured by IMERYS) • Alumina cement (product name: HiPerCem, manufactured by Calucem)

[0058] All inorganic binders were classified using a sieve with a mesh size of 106 μm, and only those that passed through the sieve were used. The component composition and Blaine values ​​of each inorganic binder are shown in the table below. The component compositions of SiO2, Al2O3, and CaO are given as percentages (mass%) of the total amount of inorganic binder.

[0059] [Table 3]

[0060] (Organic binder) • Polyvinyl alcohol (product name: Gosenol (registered trademark) GH-20S, manufactured by Mitsubishi Chemical Corporation) • Polyvinyl alcohol (product name: POVAL 5-88, manufactured by Kuraray Co., Ltd.) • Polyvinyl alcohol (product name: POVAL 22-88, manufactured by Kuraray Co., Ltd.) • Polyvinyl alcohol (product name: POVAL 30-88, manufactured by Kuraray Co., Ltd.) • Polyvinyl alcohol (product name: POVAL 44-88, manufactured by Kuraray Co., Ltd.) • Polyvinyl alcohol (product name: POVAL 25-88KL, manufactured by Kuraray Co., Ltd.) • Polyvinyl alcohol (product name: POVAL 95-88, manufactured by Kuraray Co., Ltd.) • Polyvinyl alcohol (product name: JP-45, manufactured by Nippon Vivaceuil Co., Ltd.) • Polyvinyl alcohol (product name: POVAL 17-94, manufactured by Kuraray Co., Ltd.) • Polyvinyl alcohol (product name: POVAL 27-96, manufactured by Kuraray Co., Ltd.) • Polyvinyl alcohol (product name: Gosenol® NH-26S, manufactured by Mitsubishi Chemical Corporation)

[0061] (Curing accelerator) • Lithium carbonate (manufactured by Kishida Chemical Co., Ltd.) Classification was performed using a sieve with a mesh opening of 106 μm, and the material that passed through the sieve was used.

[0062] [Preparation of molding materials] The aggregate, inorganic binder, organic binder, and hardening accelerator were each weighed using an electronic balance and mixed according to the formulations shown in Tables 5 to 13. The resulting materials were stirred for 10 minutes at approximately 98 rpm using a Kanto Mixer (manufactured by Kanto Mixing Machine Industry Co., Ltd.) HPi-60LAS, under conditions that the total weight at the time of mixing was between 20 kg and 50 kg, to obtain the molding material.

[0063] In Tables 5-13, the "viscosity" of the organic binder represents the viscosity of a 4% by mass aqueous solution at 20°C. In Tables 5-13, when classification is performed using a sieve with a mesh opening of 106 μm, the component remaining on the sieve is indicated as "+106 μm", the component that passes through the sieve is indicated as "-106 μm", when classification is performed using a sieve with a mesh opening of 75 μm, the component that passes through the sieve is indicated as "-75 μm", when classification is performed using a sieve with a mesh opening of 53 μm, the component that passes through the sieve is indicated as "-53 μm", and when classification is performed using a sieve with a mesh opening of 38 μm, the component that passes through the sieve is indicated as "-38 μm". Components below the 106 μm mesh and above the 75 μm mesh are indicated as "106-75 μm," components below the 75 μm mesh and above the 53 μm mesh are indicated as "75-53 μm," and components below the 53 μm mesh and above the 38 μm mesh are indicated as "53-38 μm." Products that have undergone crushing treatment are indicated as "crushed and graded products."

[0064] [Creating objects using a 3D printer] A 60mm x 15mm x 10mm flexural resistance test specimen was fabricated by printing using a 3D printer (product name: ProJet660Pro, manufactured by 3D Systems). The water-based ink used for printing was ZB-63 binder (product name, manufactured by 3D Systems). The print data was arranged so that the 60mm side was parallel to the recoater roller, the 15mm side was perpendicular to the recoater roller, and the 10mm side was parallel to the layering direction. The printing settings conditions in Tables 5-13, which were set using the "3DPrint Software" included with the ProJet660Pro, are shown in the table below. One hour after printing was complete, the flexural resistance test specimen was removed from the uncured powder and cured for 24 hours. The ambient conditions during printing and curing were 20°C and 30% relative humidity.

[0065] [Table 4]

[0066] 〔evaluation〕 (Specific gravity and flexural stress after 24 hours of curing after printing) For the fabricated 60mm x 15mm x 10mm bending test specimens, the dimensions were measured using a digital caliper, the weight was measured using an electronic balance, and the bulk density was calculated. In addition, the fracture load was measured by three-point bending using a bending tester (manufactured by Nippon Keisoku System Co., Ltd., model numbers JSV-H1000 and HF-100) with a lower span length of 50mm, an indentation speed of 1.0mm / s, and ambient conditions of 20°C and relative humidity of 30%. Using the measured dimensions and fracture load, the fracture stress σ (unit: MPa) was calculated using the following formula and was defined as the bending stress after 24 hours of curing after printing.

[0067] Formula: σ = (3 × F × L) / (2 × b × h) 2 ) Here, F: Maximum load (breaking load) L: Lower span length b: Width of the bending test specimen h: Thickness of the bending test specimen

[0068] The evaluation results showed a correlation between the M value and the flexural stress 24 hours after printing. When the M value exceeds 3.00, the flexural stress after 24 hours generally exceeds 3 MPa, indicating good strength. Furthermore, when the M value exceeds 4.00, the flexural stress after 24 hours generally exceeds 4 MPa, indicating even better strength.

[0069] (modeling failure rate) When printing 60mm x 15mm x 10mm flexural resistance test specimens using the ProJet660 described above, the failure rate of the printed specimens (percentage of failures out of 23 specimens) was counted. A test specimen that failed to print was defined as one in which, during the repeated process of laying the next layer of material on top of the ink-coated layer of material, the material in the ink-coated area shifted, deviated from the ink-coated area, and broke, resulting in a shape that did not form a rectangular prism after printing was complete.

[0070] The evaluation results show that keeping both W1 and W2 values ​​from being too high tends to suppress the failure rate of the printed model.

[0071] (Substances adhering to the back after molding) Using the aforementioned ProJet 660, a 60 mm × 15 mm × 10 mm bending test piece was printed and molded. When cleaning the molded article, a cured layer caused by ink bleeding may adhere to the back surface of the molded article (that is, the 60×15 mm lower surface). Printing was performed under atmospheric conditions of 20°C and a relative humidity of 30%. One hour after completion of printing, the bending test piece was taken out from the uncured powder, and the degree of adhesion of this cured layer during cleaning was evaluated according to the following criteria.

[0072] A: Cured deposits on the back surface could be removed with a brush B: Cured deposits on the back surface could not be removed with a brush, but could be removed by blowing compressed air from an air nozzle C: Cured deposits on the back surface could not be removed by a brush or compressed air blowing from an air nozzle, and were scraped off with a spatula

[0073] The higher the content of the inorganic binder contained in the molded article, the more the cured layer adheres, which tends to increase the work load during cleaning.

[0074] (Shrinkage after impregnation sintering) Using the aforementioned ProJet 660, a 60 mm × 15 mm × 10 mm bending test piece was immersed in organosilica sol (trade name: MA-ST-M, manufactured by Nissan Chemical Corporation), and subjected to decompression treatment for 3 minutes under a condition of a decompression degree of 0.85 MPa. After returning to normal pressure, the bending test piece was immediately taken out from the organosilica sol and dried for 3 hours or more. After drying, firing treatment was performed in an electric furnace. The firing conditions were as follows: the temperature was raised from normal temperature (about 25°C) to 1500°C at a rate of 100°C / hour, maintained at 1500°C for 3 hours, and then allowed to cool naturally. The dimension X of the 60 mm side of the bending test piece immediately before immersion in the organosilica sol was compared with the dimension Y of the 60 mm side of the bending test piece after firing at 1500°C, the shrinkage rate during firing was determined by the following formula, and evaluated as follows.

[0075] Formula: (X-Y) / X×100

[0076] A: Shrinkage rate is less than 3% B: Shrinkage rate is 3% or more

[0077] The evaluation results show that the higher the Al2O3 content of the inorganic binder, the lower the shrinkage rate and the higher the heat resistance tend to be.

[0078] (Poor performance during impregnation) Using the ProJet660 described above, a 60mm x 15mm x 10mm flexural resistance test specimen was immersed in organosilica sol (product name: MA-ST-M, manufactured by Nissan Chemical Corporation), and subjected to a reduced pressure treatment of 0.85 MPa for 3 minutes. After returning to atmospheric pressure, the flexural resistance test specimen was immediately removed from the organosilica sol, and its appearance was compared to check for defects. Defects during impregnation were evaluated according to the following criteria.

[0079] A: No silica gel residue or gloss is visible on the exterior. B: Silica gel remains on the surface, and a noticeable gloss is visible.

[0080] The evaluation results show that impregnation defects are suppressed in cases where the viscosity of a 4% by mass aqueous solution of polyvinyl alcohol at 20°C is 25 mPa·s or higher, compared to cases where the viscosity is less than 25 mPa·s.

[0081] (shape accuracy) When creating a 60mm x 15mm x 10mm bending test specimen using the ProJet660 described above, the specimen was fabricated using 3D data with a concave shape printed in the outline of the letter "R" on the 15mm x 10mm surface. The shape accuracy was evaluated according to the following criteria.

[0082] A:R: No blurring of letters, and clear outlines. B:R letters are partially distorted, leaving areas with unclear outlines. The C:R characters are completely distorted, and their outlines are not clear.

[0083] The evaluation results show that the smaller the D50 value of the organic binder, the sharper the outline of the letter R tends to be.

[0084] (BET specific surface area of ​​aggregate) The specific surface area of ​​the aggregate was measured using a BET specific surface area analyzer (Micromeristics, Inc., USA, product name FlowSorbII 2300).

[0085] The evaluation results, particularly from Examples 63-65, show that the smaller the specific surface area of ​​the aggregate, the higher the strength tends to be.

[0086] The evaluation results show that if the degree of saponification of polyvinyl alcohol is not too high, it dissolves well in water-based inks and exhibits its binding effect effectively, thereby suppressing a decrease in strength.

[0087] Tables 5-13 show the ingredient composition and evaluation results. In the tables, blank spaces in the evaluation column indicate that the evaluation was not performed.

[0088] [Table 5]

[0089] [Table 6]

[0090] [Table 7]

[0091] [Table 8]

[0092] [Table 9]

[0093] [Table 10]

[0094] [Table 11]

[0095] Table 12

[0096] Table 13

Claims

1. Additive molding material comprising aggregate, inorganic binder, and organic binder, and satisfying the following formula. Formula: (-0.700)×W1+(-0.697)×W2+(-0.699)×W3+(-0.724)×W4+(-0.029)×P1+(0.420)×C1+(73.4)>3.00 W1: Mass ratio (mass%) of aggregate with a particle size greater than 75 μm and less than or equal to 106 μm relative to the total amount of aggregate. W2: Mass ratio (mass%) of aggregate with a particle size greater than 53 μm and less than or equal to 75 μm relative to the total amount of aggregate. W3: Mass ratio (mass%) of aggregate with a particle size greater than 38 μm and less than or equal to 53 μm relative to the total amount of aggregate. W4: Mass ratio (mass%) of aggregate with a particle size of 38 μm or less relative to the total amount of aggregate. P1: Median diameter D50 (μm) of the organic binder. C1: Mass ratio (mass%) of the inorganic binder to the total amount of the molding material.

2. The inorganic binder is Al ２ O ３ The additive molding material according to claim 1, comprising an alumina cement containing 50% by mass or more of the above.

3. The additive molding material according to claim 1, wherein the organic binder contains polyvinyl alcohol.

4. The additive molding material according to claim 3, wherein the organic binder is made of polyvinyl alcohol.

5. The additive molding material according to claim 3, wherein the polyvinyl alcohol has a viscosity of 25 mPa·s or more at 20°C when it is a 4% by mass aqueous solution.

6. The additive molding material according to claim 3, wherein the degree of saponification of the polyvinyl alcohol is 70 to 93%.

7. The additive molding material according to claim 1, wherein the mass ratio (C1) of the inorganic binder to the total amount of the molding material is 1.5 to 15% by mass.

8. The additive molding material according to claim 1, wherein the mass ratio of the aggregate to the total amount of the molding material is 80 to 96% by mass.

9. The additive molding material according to claim 1, wherein the mass ratio of the organic binder to the total amount of the molding material is 0.5 to 5% by mass.

10. The BET specific surface area of ​​the aforementioned aggregate is 0.90 m². ２ The additive molding material according to claim 1, wherein the amount is less than or equal to / g.

11. The additive molding material according to claim 1, wherein the mass ratio (W1) of aggregate with a particle size of more than 75 μm and less than or equal to 106 μm relative to the total amount of aggregate and the mass ratio (W2) of aggregate with a particle size of more than 53 μm and less than or equal to 75 μm relative to the total amount of aggregate are each 80% by mass or less.

12. The additive molding material according to claim 1, wherein the mass ratio of aggregate with a particle size of 106 μm or more to the total amount of aggregate is 10% by mass or less.

13. The additive molding material according to claim 1, wherein the median diameter D50 (P1) of the organic binder is 50 μm or less.

14. Furthermore, the additive molding material according to claim 1, further comprising 0.05 to 0.5% by mass of lithium carbonate, which is a curing accelerator, relative to the total amount of the molding material.

15. A molding material for additive manufacturing according to claim 1, satisfying the following formula. Formula: (-0.700)×W1+(-0.697)×W2+(-0.699)×W3+(-0.724)×W4+(-0.029)×P1+(0.420)×C1+(73.4)>4.00

16. A method for manufacturing a molded body, comprising curing and laminating an additive molding material according to any one of claims 1 to 15 by a powder-bonding lamination method.

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