JP2024046007A - Method for manufacturing three-dimensional additive manufacturing object, and kit for three-dimensional additive manufacturing - Google Patents

Abstract

[Problem] To provide a manufacturing method for a three-dimensional additive manufacturing object, which can easily manufacture a three-dimensional additive manufacturing object with practical strength in a good working environment, and a kit for three-dimensional additive manufacturing. [Solution] A manufacturing method for a three-dimensional additive manufacturing object, which includes a step (a) of spreading a fire-resistant granular material in layers, and a step (b) of injecting a binder into desired areas of the fire-resistant granular material spread in layers, the binder comprising a sugar and a polyvalent carboxylic acid, and the steps (a) and (b) are repeated until a desired three-dimensional additive manufacturing object is manufactured. A three-dimensional additive manufacturing kit, which includes a fire-resistant granular material and a binder, each of which is independent, the binder comprising a sugar and a polyvalent carboxylic acid. [Selected Figure] None

Description

The present invention relates to a method for manufacturing a three-dimensional additive manufacturing object and a kit for three-dimensional additive manufacturing.

Self-hardening molds have been known as one type of casting mold (hereinafter simply referred to as "mold"). Self-hardening molds are manufactured by adding a binder (acid-hardening binder) whose main component is furan resin and the like, and an acid catalyst (hardener) such as sulfuric acid or xylene sulfonic acid to a refractory granular material such as silica sand, mixing the mixture, and then filling a wooden or resin mold (hereinafter collectively referred to as "model") with the resulting mixed sand and allowing the binder to harden.

A liquid made by melting metals such as iron, copper, and aluminum at high temperatures is poured into the mold to obtain a casting, but during pouring, the acid-curing binder is thermally decomposed and gas (pyrolysis gas) is released. This may occur.
Furthermore, if a large amount of acid catalyst is used for the purpose of increasing the curing speed, sulfur oxides such as sulfur dioxide gas are likely to be generated during pouring.
As described above, when gas is generated during pouring, the working environment deteriorates.

Therefore, a method has been proposed in which a mold is manufactured using saccharides as a binder instead of an acid-curable binder.
For example, in Patent Documents 1 and 2, a model is filled with a binder-coated refractory in which the surface of refractory aggregate is coated with a solid coating layer containing sugars as a binder, and the sugars are removed by heating. A method of manufacturing a mold by solidifying or hardening the sugar after melting is disclosed. Since saccharides are carbohydrates, even if they are thermally decomposed, only carbon dioxide gas, water, etc. are generated, and the working environment is unlikely to deteriorate. Further, since the caking property is developed by solidifying or hardening the molten sugar, there is no need to use an acid catalyst.

International Publication No. 2011/030795 JP2016-221540A

By the way, in order to manufacture a mold of a complex shape, it is necessary to increase the number of patterns, but increasing the number of patterns causes the process to become complicated. Even if the number of patterns can be increased, if the mold cannot be removed from the pattern, the mold cannot be manufactured.
In addition, if the mold is hollow, the amount of binder used can be reduced, so that even if an acid-hardening binder is used as the binder, the amount of pyrolysis gas generated during pouring can be reduced and the pyrolysis gas can be easily released outside the mold. However, it is difficult to manufacture a hollow mold using a model.
In order to solve these problems, in recent years, methods for manufacturing molds by three-dimensional additive manufacturing have been proposed, which make it possible to directly manufacture a mold without using a model.

When manufacturing a mold by three-dimensional additive manufacturing using the binder-coated refractory materials described in Patent Documents 1 and 2, in order to obtain a mold of a desired shape, it is necessary to repeat a step of stacking the binder-coated refractory materials in layers and a step of injecting water into desired areas of the binder-coated refractory materials laid out in layers to gelatinize the sugars until the desired three-dimensional additive object is formed, and then to perform a heat treatment.
However, the sugar in the area where water is not injected also melts and then hardens due to the heat treatment, so a three-dimensional additive manufacturing object with the desired shape cannot be obtained.
As described above, a binder-coated refractory material in which refractory aggregate is coated with a sugar is not suitable for manufacturing a casting mold by three-dimensional additive manufacturing.

An object of the present invention is to provide a method for manufacturing a three-dimensional layered product that allows easy production of a three-dimensional layered product with a good working environment and a practical strength, and a three-dimensional layered product kit.

The present invention has the following aspects.
[1] A step (a) of laying a layer of refractory granular material;
(b) injecting a binder into desired areas of the layered refractory granular material;
The binder comprises a sugar and a polyvalent carboxylic acid,
The method for manufacturing a three-dimensional additive object includes repeating the steps (a) and (b) until a desired three-dimensional additive object is manufactured.
[2] The method for producing a three-dimensional additive manufacturing object according to [1], further comprising, after at least the final step (b), a step (c) of curing the binder by heating.
[3] A method for producing a fireproof granular material and a binder, each of which is independently
The binder comprises a sugar and a polycarboxylic acid.

According to the present invention, it is possible to provide a method for manufacturing a three-dimensional layered product in which a working environment is favorable and a three-dimensional layered product with practical strength can be easily manufactured, and a three-dimensional layered product kit.

[Manufacturing method of three-dimensional layered product]
Hereinafter, one embodiment of the method for manufacturing a three-dimensional layered product of the present invention will be described.
The method for manufacturing a three-dimensional layered product according to the present embodiment includes the following steps (a) and (b), and the three-dimensional layered product intended for step (a) and step (b) is manufactured. This is a method of manufacturing a three-dimensional layered product by repeating the process until it is completed.
It is preferable that the method for manufacturing a three-dimensional laminate-molded article of the present embodiment further includes a step (c) shown below after at least the last step (b).

<Fire-resistant granular material>
Refractory particulate materials for use in the present invention include sand, ceramic, metal, and the like.
These refractory granular materials may be used alone or in combination of two or more.

Examples of the sand include natural sand such as silica sand, chromite sand, zircon sand, olivine sand, amorphous silica, alumina sand, and mullite sand; and artificial sand. In addition, used artificial sand or natural sand that has been recovered (recovered sand), or recycled sand (recycled sand) that has been recycled (dry recycling such as roasting, polishing, etc.) can also be used. These sands may be used alone or in combination of two or more.
Artificial sand generally uses bauxite as a raw material and is obtained by any one of the melting method (atomization method), sintering method, and flame fusion method. The specific conditions of the melting method, sintering method, and flame melting method are not particularly limited, and are described in, for example, JP-A-5-169184, JP-A-2003-251434, JP-A-2004-202577, etc. Artificial sand may be manufactured using known conditions.
Examples of metals include nickel, cobalt, molybdenum, iron, stainless steel, aluminum, titanium, and copper. These metals may be used alone or in combination of two or more.

The average particle diameter of the refractory granular material is preferably 10 to 300 μm, more preferably 50 to 150 μm. If the average particle diameter of the refractory granular material is at least the above lower limit, a three-dimensional layered product with high strength can be obtained. If the average particle diameter of the refractory granular material is below the above-mentioned upper limit, a three-dimensional laminate-molded article with excellent surface texture can be obtained.
The average particle diameter of the refractory granular material is a particle diameter (median diameter) corresponding to a cumulative frequency of 50% based on the volume distribution of the refractory granular material measured by a dynamic light scattering method.
Moreover, "surface roughness" refers to the surface roughness in the stacking direction of a three-dimensional layered product.

The fire-resistant granular material is selected depending on the intended use of the resulting three-dimensional laminated object. For example, when the three-dimensional laminated object is used as a mold, sand is suitable as the fire-resistant granular material. Since natural sand is cheaper than artificial sand, it is preferable to use natural sand alone or in combination with artificial sand from the viewpoint of reducing the manufacturing cost, and it is preferable to use natural sand in combination with artificial sand if the fire resistance of the mold is also taken into consideration.
A casting mold is a model for casting metal, and is dismantled to remove the casting after casting. In other words, if the casting is the final object (final product), then the casting mold is meant to be destroyed in the end.
On the other hand, when the three-dimensional additive manufacturing object is the final object (one that is not intended to be destroyed in the end), a metal is suitable as the fire-resistant granular material. In this specification, a three-dimensional additive manufacturing object obtained by using a metal is also referred to as a "metal molded body."

The refractory particulate material may be coated with a coating.
A refractory granular material coated with a coating agent is also referred to as a "coating material." In particular when the refractory granular material is sand, the coating material is also referred to as "coated sand".
Examples of the coating agent include antiblocking agents and acid components other than polyhydric carboxylic acids.

Examples of the antiblocking agent include antiblocking agents such as inorganic particles, zeolite, and lubricants.
Examples of the inorganic particles include silicate minerals such as silica, titania, alumina, zeolite, kaolin, talc, and mica; diatomaceous earth, and the like. Silica may be amorphous or crystalline. Moreover, natural silica or synthetic silica may be used. Examples of synthetic silica include wet silica such as precipitated silica and silica gel; dry silica such as fumed silica (flame hydrolysis silica), arc silica, plasma silica, and quartz glass (flame fused silica).
Zeolite is a general term for crystalline aluminosilicates. Examples of the zeolite skeleton structure include A type, X type, LSX type, beta type, ZSM-5 type, ferrierite type, mordenite type, L type, and Y type.
Examples of lubricants include aliphatic hydrocarbon lubricants such as paraffin wax and carnauba wax; aliphatic amide lubricants such as higher aliphatic alcohols, ethylene bisstearamide, and stearamide; calcium stearate, barium stearate, and stearin. Examples include metal soap-based lubricants such as acid zinc, aluminum stearate, and magnesium stearate; fatty acid ester-based lubricants; and composite lubricants.
These antiblocking agents may be used alone or in combination of two or more.

The acid component is not particularly limited as long as it is not a polyhydric carboxylic acid, but includes, for example, benzoic acid, o-hydroxybenzoic acid, m-hydroxybenzoic acid, p-hydroxybenzoic acid, 2,4-dihydroxybenzoic acid, 2, Monovalent carboxylic acid such as 6-dihydroxybenzoic acid, 3,5-dihydroxybenzoic acid, 3,4,5-trihydroxybenzoic acid (gallic acid), 2,4,6-trihydroxybenzoic acid, salicylic acid, anthranilic acid, etc. Acids; sulfonic acids such as para-toluenesulfonic acid, xylenesulfonic acid, benzenesulfonic acid and methanesulfonic acid; sulfuric acid; phosphoric acid and the like.
These acid components may be used alone or in combination of two or more.
However, acids containing sulfur such as sulfonic acid and sulfuric acid tend to generate sulfur oxides such as sulfur dioxide gas during pouring. Therefore, the content of sulfur-containing acids such as sulfonic acid and sulfuric acid is preferably less than 0.5 parts by mass, more preferably 0.3 parts by mass or less, and 0.1 parts by mass, based on 100 parts by mass of the refractory granular material. Parts by weight or less are more preferred, and it is especially preferred that the refractory particulate material is not coated with a sulfur-containing acid.

The coating material can be obtained, for example, by adding a solution containing a coating agent (hereinafter also referred to as "solution (α)") to a heated refractory granular material.
When a dry coating material is to be obtained, the heating temperature of the refractory granular material is preferably equal to or higher than the boiling point of the solvent contained in the solution (α).
The upper limit of the heating temperature of the refractory granular material is not particularly limited as long as the coating agent does not thermally decompose.
The coating material may be in a dry state, or in a wet state as long as it can be layered in three-dimensional additive manufacturing, but is preferably in a dry state.

<Binder>
The binder used in the present invention comprises a sugar and a polyvalent carboxylic acid.
The binder may contain components (optional components) other than the sugars and polyvalent carboxylic acids, as necessary, within a range that does not impair the effects of the present invention.
In the present invention, a binder comprising a sugar and a polyvalent carboxylic acid is also called a "sugar binder."

(sugar)
Sugars act as binders.
Examples of saccharides include carbohydrates such as monosaccharides, oligosaccharides, and polysaccharides; sugar alcohols, and the like.
In this specification, an "oligosaccharide" is defined as one in which 2 to 10 monosaccharides are bound together, and a "polysaccharide" is defined as one in which 11 or more monosaccharides are bound together.

Examples of monosaccharides include glucose, fructose, mannose, galactose, ribose, and xylose.
Examples of oligosaccharides include disaccharides such as sucrose, maltose, lactose, trehalose, isomaltose, and cellobiose; trisaccharides such as maltotriose and raffinose; maltooligosaccharides; isomaltooligosaccharides; fructooligosaccharides; mannooligosaccharides; and galactooligosaccharides.
Examples of polysaccharides include starch, dextrin, xanthan gum, curdlan, pullulan, cycloamylose, chitin, cellulose, and polydextrose.
Examples of starch include unmodified starch and modified starch. Specific examples include unmodified starches such as potato starch, corn starch, high amylose, sweet potato starch, tapioca starch, sago starch, rice starch, and amaranth starch, and modified starches thereof (roasted dextrin, enzyme-modified dextrin, acid-treated starch, oxidized starch, dialdehyde-modified starch, etherified starch (carboxymethyl starch, hydroxyalkyl starch, cationic starch, methylol-modified starch, etc.), esterified starch (starch acetate, starch phosphate, starch succinate, starch octenylsuccinate, starch maleate, higher fatty acid esterified starch, etc.), crosslinked starch, kraft starch, and heat-moisture treated starch.
Examples of sugar alcohols include maltitol, sorbitol, ribitol, mannitol, arabitol, galactitol, lactitol, xylitol, sucrose, erythritol, and inositol.
Sugar is composed mainly of sucrose (cane sugar), and depending on the raw materials and manufacturing method, there are white sugar, granulated sugar, white double sugar, brown sugar, brown sugar, etc., and any of these can be used as sugars in the present invention.
These sugars may be used alone or in combination of two or more.

(Polyhydric carboxylic acids)
Polyhydric carboxylic acids exhibit caking properties by reacting with saccharides and polymerizing, so they play the role of caking agents. In addition, polycarboxylic acids also serve as acid catalysts (curing agents) for sugars.
In the present invention, the term "polyvalent carboxylic acids" includes not only polyvalent carboxylic acids but also polyvalent carboxylic acid salts, polyvalent carboxylic acid anhydrides, polyvalent carboxylic acid halides, polyvalent carboxylic acid derivatives, etc. It is something that

Examples of polyvalent carboxylic acids include polyvalent carboxylic acids such as citric acid, malic acid, oxalic acid, maleic acid, succinic acid, fumaric acid, tartaric acid, isophthalic acid, itaconic acid, butanetetradicarboxylic acid, myristic acid, palmitic acid, malonic acid, glutaric acid, phthalic acid, terephthalic acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, 5-hydroxyisophthalic acid, 3,6-dihydroxyphthalic acid, 4-hydroxyphthalic acid, and methyl vinyl ether-maleic anhydride copolymer; salts of these polyvalent carboxylic acids (polyvalent carboxylates); anhydrides of these polyvalent carboxylic acids (polyvalent carboxylic acid anhydrides); halides of these polyvalent carboxylic acids (polyvalent carboxylic acid halides); and derivatives of these polyvalent carboxylic acids (polyvalent carboxylic acid derivatives).
Examples of the salts of polycarboxylic acids include salts of polycarboxylic acids and alkali metals (potassium, sodium, etc.), salts of polycarboxylic acids and alkaline earth metals (magnesium, calcium, etc.), salts of polycarboxylic acids and ammonium, and salts of polycarboxylic acids and alkanolamines (monoethanolamine, diethanolamine, triethanolamine, etc.).
Examples of the anhydrides of polycarboxylic acids include those which are formed by intramolecular or intermolecular dehydration condensation of polycarboxylic acids and contain a carboxylic anhydride group (--CO--O--CO--).
Examples of the halides of polycarboxylic acids include acid chlorides of polycarboxylic acids and acid bromides of polycarboxylic acids.
Examples of the derivatives of polycarboxylic acids include ester compounds of polycarboxylic acids with lower alcohols having 1 to 5 carbon atoms (e.g., methanol, ethanol, propanol, butanol, pentanol, etc.) and ester compounds of polycarboxylic acids with low molecular weight glycols (e.g., ethylene glycol).
Among these, polycarboxylic acids are preferred from the viewpoints of plant origin and ease of availability, and citric acid and malic acid are more preferred.
These polyvalent carboxylic acids may be used alone or in combination of two or more kinds.

(optional ingredient)
Examples of optional components include acid components other than polyhydric carboxylic acids, which were exemplified earlier in the description of the refractory granular material.

<Step (a), step (b)>
Step (a) is a step of spreading the refractory granular material in layers.
Step (b) is a step of injecting a binder into a desired area of the layered refractory granular material.
In the method for manufacturing a three-dimensional layered product according to the present embodiment, steps (a) and (b) are repeated until the desired three-dimensional layered product is manufactured.

Steps (a) and (b) are performed as follows using, for example, a three-dimensional lamination apparatus using a printing method.
The three-dimensional lamination apparatus is preferably one that includes a blade mechanism, a printing nozzle head mechanism, and a modeling table mechanism. Furthermore, it is preferable to include a control section that controls the operation of each mechanism using three-dimensional data of the object to be modeled.
The blade mechanism includes a recoater and laminates the refractory granular material to a predetermined thickness on the surface of the metal case or on the upper layer of the shaped part that has been bonded with a binder.
The printing nozzle head mechanism prints with a binder on the laminated refractory granular materials, and shapes each layer by bonding the refractory granular materials.
When the modeling of one layer is completed, the modeling table mechanism is lowered by a distance corresponding to one layer, thereby realizing layered manufacturing with a predetermined thickness.

First, using a three-dimensional lamination apparatus using a printing method, a refractory granular material is laminated on the bottom surface of a metal case installed in the three-dimensional lamination apparatus using a blade mechanism having a recoater (step (a)). Next, the binder is applied to a desired area of the laminated fire-resistant granular material by scanning the printing nozzle head with the printing nozzle head mechanism based on the data obtained by 3D CAD designing the shape of the desired three-dimensional laminate model. Print (inject) (step (b)). The bottom of the metal case is a modeling table that can be moved up and down. After printing the binder, lower the bottom of the metal case (modeling table) by one layer, layer the refractory granular material in the same manner as before (step (a)), and print the binder on top of it (step (a)). b)). These laminating and printing operations are repeated until the desired three-dimensional layered product is manufactured. The thickness of one layer is preferably 100 to 500 μm, more preferably 100 to 300 μm.
In addition, when manufacturing a metal molded body using a fire-resistant granular material in which the refractory granular material is a metal, it is preferable to use a metal 3D printer.

The saccharides and polycarboxylic acids included in the binder may be used in a mixture or separately. That is, in step (b), a mixture containing sugars and polycarboxylic acids (hereinafter also referred to as "mixture (M1)") is injected into a desired area of the refractory granular material spread in layers. Alternatively, the saccharide and polycarboxylic acid may be separately injected. When saccharides and polyvalent carboxylic acids are injected separately, there are no particular restrictions on the order of injection; the polyvalent carboxylic acids may be injected after the saccharides are injected, or the saccharides may be injected after the polyvalent carboxylic acids are injected. It may be injected, or the saccharide and polycarboxylic acid may be injected at the same time. Considering manufacturing cost and labor, it is preferable to inject the mixture (M1).
Hereinafter, in this specification, the case where the mixture (M1) is injected is also referred to as "step (b1)". The case of injecting sugars is also referred to as "step (b2)." The case where polycarboxylic acids are injected is also referred to as "step (b3)."

Preferred embodiments of step (a) and step (b) are as follows.
A mode in which step (a) and step (b1) are repeated in this order until the desired three-dimensional layered product is modeled.
A mode in which step (a), step (b2), and step (b3) are repeated in this order until the desired three-dimensional layered product is modeled.
A mode in which step (a), step (b3), and step (b2) are repeated in this order until the desired three-dimensional layered product is modeled.
A mode in which step (a), step (b2), and step (b3) are repeated in this order (however, step (b2) and step (b3) are simultaneous) until the desired three-dimensional layered product is modeled.

The binder is preferably dissolved or diluted in a solvent in advance and used in the form of a solution so that it has a concentration that is easy to eject from the printing nozzle head mechanism. That is, in step (b), it is preferable to inject a solution containing a binder (hereinafter also referred to as "solution (β)"). The solution (β) may contain the above-mentioned optional components as necessary.
When saccharides and polycarboxylic acids are used in the form of a mixture, it is preferable to use a solution containing the mixture (M1) (hereinafter also referred to as "solution (β1)") in step (b1).
When saccharides and polycarboxylic acids are used separately, it is preferable to use a solution containing saccharides (hereinafter also referred to as "solution (β2)") in step (b2). In step (b3), it is preferable to use a solution containing polyhydric carboxylic acids (hereinafter also referred to as "solution (β3)").
Each of the solution (β1), the solution (β2), and the solution (β3) may contain the above-mentioned optional components as necessary.
Examples of the solvent used for the solution (β), that is, the solution (β1), the solution (β2), and the solution (β3) include water, alcohol, and mixtures thereof. Examples of alcohol include methanol, ethanol, 1-propanol, 2-propanol, and the like. Among these, water is preferred.
The total amount of saccharides and polyvalent carboxylic acids in the solution (β), that is, the solution (β1), the solution (β2), and the solution (β3) is not particularly limited, and should be determined as appropriate depending on the performance of the three-dimensional lamination device, etc. Bye.

In step (b), the sugars and polycarboxylic acids are preferably injected so that the mass ratio of the sugars to the polycarboxylic acids is 90:10 to 10:90, more preferably 80:20 to 20:80, even more preferably 70:30 to 30:70, particularly preferably 60:40 to 40:60, and most preferably 50:50. By injecting the sugars and polycarboxylic acids so that the mass ratio is within the above range, sufficient hardening can be achieved by the reaction between the sugars and the polycarboxylic acids. In particular, if the mass ratio of the sugars to the polycarboxylic acids is within the range of 50:50 to 20:80, a three-dimensional additively shaped product with excellent water resistance tends to be obtained. Therefore, when the three-dimensional additively shaped product is a mold, the strength of the mold can be well maintained even when it is cast in a humid environment.

In step (b), it is preferable, more preferably, that the saccharides and polycarboxylic acids are injected such that the total amount of the saccharides and polycarboxylic acids is 60% by mass or more based on the total mass of the binder. is 70% by mass or more, more preferably 80% by mass or more, particularly preferably 100% by mass.

In addition, the amount of application when printing the binder is preferably an amount, calculated on a pure basis, such that the total amount of sugars and polycarboxylic acids is 0.5 to 10 parts by mass, more preferably 0.5 to 5 parts by mass, and even more preferably 0.5 to 2 parts by mass, when the mass of one layer of fire-resistant granular material in the printing area is 100 parts by mass. If the total amount of sugars and polycarboxylic acids relative to the fire-resistant granular material is equal to or greater than the lower limit above, sufficient binding properties can be obtained. The binding effect tends to be more easily obtained as the ratio of the total amount of sugars and polycarboxylic acids increases, but if the amount increases too much, the effect will simply plateau. Therefore, the total amount of sugars and polycarboxylic acids is preferably 10 parts by mass or less.

In addition, in step (a), the refractory granular material may be used in a state coated with the above-mentioned coating material, or may be used in a state mixed with an antiblocking agent. That is, in step (a), the above-mentioned coating material may be spread in layers, or a mixture containing a fire-resistant granular material or coating material and an antiblocking agent (hereinafter also referred to as "mixture (M2)"). It may be laid out in layers.
When the coating material or mixture (M2) is spread in layers in step (a), in step (b), a binder is injected into a desired area of the coating material or mixture (M2) spread in layers.

The three-dimensional additive model obtained in this way is modeled while being embedded in the powder of fire-resistant granular material. As the injected binder (sugars and polycarboxylic acids) dries and solidifies, the binder forms liquid bridges, bonding the fire-resistant granular material to a certain extent, allowing the three-dimensional additive model to be removed from the powder of fire-resistant granular material. If any fire-resistant granular material is attached to the periphery of the removed three-dimensional additive model in areas where the binder is not printed (non-printed areas), it is removed with a brush, vacuum cleaner, etc.

After the three-dimensional layered product is taken out from the powder of the refractory granular material, the following step (c) is preferably performed for the purpose of increasing the strength of the three-dimensional layered product.
Furthermore, if it is difficult to remove the refractory granular material adhering to the periphery of the three-dimensional layered product taken out, it is preferable to perform the following step (c).
In addition, the following step (c) may be performed in a state where the three-dimensional layered product is buried in the powder of the fire-resistant granular material without taking out the three-dimensional layered product from the powder of the fire-resistant granular material. .

<Step (c)>
Step (c) is a step of curing the binder by heating, at least after the last step (b).
The number of times of step (c) may be one time, or two or more times.
When the number of times of step (c) is one, step (c) is performed only after the last step (b).
When the number of times of step (c) is two or more, step (c) is performed one or more times after steps (b) other than the last step (b). For example, step (a), step (b), and step (c) are repeated in this order until the desired three-dimensional layered product is modeled.
After the last step (b), if the three-dimensional laminate-molded article can be taken out from the powder of the refractory granular material, only the taken-out three-dimensional laminate-molded article may be heated. At that time, heating may be performed in a state in which the refractory granular material in the non-printing area is attached to the periphery of the three-dimensional layered product taken out. Alternatively, the three-dimensional layered product may be heated while being buried in powder of the refractory granular material.

The heating temperature in step (c) is preferably 100 to 300 ° C, more preferably 130 to 290 ° C, even more preferably 150 to 280 ° C, even more preferably 160 to 270 ° C, particularly preferably 170 to 260 ° C, and most preferably 180 to 250 ° C. If the heating temperature is equal to or higher than the lower limit, the binder is easily cured. In particular, if the heating temperature is 150 ° C or higher, a three-dimensional laminated object having practical strength is easily obtained. Furthermore, if the heating temperature is more than 150 ° C, a three-dimensional laminated object having excellent water resistance is easily obtained. Therefore, when the three-dimensional laminated object is a mold, the strength of the mold can be well maintained even when casting is performed in a humid environment. If the heating temperature is equal to or lower than the upper limit, the sugars and polyvalent carboxylic acids can be suppressed from being thermally decomposed.
The heat treatment may be performed using a dryer, or in the case where the three-dimensional stacking device is equipped with a heat treatment mechanism, the heat treatment may be performed inside a metal case of the three-dimensional stacking device.

The sugars and polycarboxylic acids are melted by heating, and then solidified or hardened, thereby firmly bonding the refractory granular materials together. In addition, when the sugars and polycarboxylic acids are melted, the reaction between the sugars and the polycarboxylic acids (esterification, etc.) progresses and it becomes easier to polymerize, so it becomes more difficult to solidify or harden than when the sugars solidify or harden alone. The fire-resistant granular materials become more strongly bonded to each other.
It is preferable to carry out step (c) also from the viewpoint of sufficiently advancing the reaction between the saccharide and the polycarboxylic acid.

When step (c) is performed with the three-dimensional additive model buried in the powder of the refractory granular material, after step (c) is performed after the last step (b), the refractory granular material in the area where the binder is not printed (non-printed area) is removed with a brush, a vacuum cleaner, or the like to remove the three-dimensional additive model. The sugars and polyvalent carboxylic acids are polymerized by heating, so that the refractory granular materials bond more firmly to each other, increasing the strength of the three-dimensional additive model and allowing the three-dimensional additive model to maintain its shape well. Therefore, the three-dimensional additive model can be easily removed from the powder of the refractory granular material.
Since no reaction occurs between the sugars and the polyvalent carboxylic acids in the non-printed areas, the refractory granular material is not bonded to itself, and the refractory granular material in the non-printed areas can be easily removed.

When manufacturing a metal molded body, step (c) may be performed after the final step (b), and then a degreasing step and a sintering step may be performed as necessary.

<Action and effect>
According to the manufacturing method of the present invention for producing a three-dimensional additive object as described above, a binder comprising sugars and polyvalent carboxylic acids is used as a binding agent. Therefore, when the three-dimensional additive object obtained by the present invention is a casting mold, even if it undergoes thermal decomposition during pouring, only carbon dioxide gas, water, etc. are generated, and the working environment during pouring is unlikely to deteriorate.
Furthermore, according to the present invention, there is no need to use an acid containing sulfur, such as sulfonic acid or sulfuric acid, as an acid catalyst. Therefore, when the three-dimensional additive manufacturing object obtained according to the present invention is used as a casting mold, the working environment during pouring is unlikely to deteriorate, from the viewpoint of preventing the generation of sulfur oxides, such as sulfur dioxide gas, during pouring.

In addition, when manufacturing a metal molded body, a degreasing process and a sintering process are normally performed after hardening the binder. During these degreasing and sintering processes, the binder is thermally decomposed and gas (pyrolysis gas) is generated, and sulfur oxides such as sulfur dioxide gas are generated due to acid catalysts such as sulfuric acid and xylene sulfonic acid. may occur, deteriorating the working environment.
However, in the present invention, a binder containing sugars and polycarboxylic acids is used as a binder, and there is no need to use an acid containing sulfur. Even if this is done, pyrolysis gases and sulfur oxides are less likely to be generated, and the working environment is less likely to deteriorate during the manufacturing process of metal molded bodies.

In this way, the present invention uses a binder containing sugars and polyvalent carboxylic acids as a binding agent, which provides a good working environment during pouring and the manufacturing process, and allows the manufacture of 3D additive objects with practical strength. In addition, the use of 3D additive manufacturing makes it easy to manufacture 3D additive objects with complex shapes.
Furthermore, because sugars are plant-derived binders made from plants, the present invention makes it possible to produce carbon-neutral three-dimensional additive manufacturing objects, thereby reducing the amount of fossil fuels such as oil and coal used, and contributing to the prevention of global warming (reducing carbon dioxide emissions) and the creation of a circular society through carbon neutrality.

In addition, in the present invention, since the binder does not harden in the area where the binder is not injected in step (b), the refractory granular materials do not bond to each other, and the three-dimensional additive manufacturing object can be easily removed from the powder of the refractory granular material. Therefore, for example, when manufacturing a hollow three-dimensional additive manufacturing object, it is necessary to remove the refractory granular material located in the hollow part, but in the present invention, the refractory granular material located in the hollow part is difficult to bond to each other, so it can be easily removed, and the hollow three-dimensional additive manufacturing object can be easily manufactured. Note that, when manufacturing a hollow three-dimensional additive manufacturing object, it is preferable to design the shape of the three-dimensional additive manufacturing object so that a removal hole for removing the refractory granular material located in the hollow part is provided at any position of the three-dimensional additive manufacturing object.

[3D additive manufacturing kit]
The three-dimensional additive manufacturing kit of the present invention includes a fire-resistant granular material and a binder, each independently. The three-dimensional additive manufacturing kit may further independently contain an antiblocking agent.
Here, "having independently" means that the respective components are present without being mixed or in contact with each other.

Examples of the fire-resistant granular material constituting the three-dimensional additive manufacturing kit include the fire-resistant granular materials exemplified above in the description of the method for producing a three-dimensional additive-molded article of the present invention.
The binder constituting the three-dimensional additive manufacturing kit includes saccharides and polycarboxylic acids. The binder may contain optional components as necessary within a range that does not impair the effects of the present invention.
Examples of the saccharides, polycarboxylic acids, and optional components include the saccharides, polycarboxylic acids, and optional components previously exemplified in the explanation of the method for producing a three-dimensional laminate-molded article of the present invention.
The saccharides and polycarboxylic acids included in the binder may exist in a mixture or independently.
Examples of the anti-blocking agent constituting the three-dimensional layered manufacturing kit include the anti-blocking agents exemplified above in the description of the method for manufacturing the three-dimensional layered product of the present invention.

A preferred embodiment of the three-dimensional additive manufacturing kit is as follows.
A collection of containers comprising a first container containing a refractory granular material and a second container containing said mixture (M1).
A collection of containers comprising a first container containing a refractory granular material, a third container containing a sugar, and a fourth container containing a polycarboxylic acid.
A collection of containers comprising a first container containing a refractory granular material, a second container containing said mixture (M1), and a fifth container containing an anti-blocking agent.
A collection of containers comprising a first container containing a fire-resistant granular material, a third container containing a sugar, a fourth container containing a polycarboxylic acid, and a fifth container containing an antiblocking agent.
The first container may further contain an anti-blocking agent if necessary, i.e. the refractory granular material may be contained in the first container in a mixture with the anti-blocking agent.
The refractory granular material may also be contained in the first container in a state coated with the above-mentioned coating agent (i.e., as a coating material).

In the above-described method for producing a three-dimensional additive manufacturing object of the present invention, the three-dimensional additive manufacturing kit of the present invention may be used to produce the three-dimensional additive manufacturing object.
For example, the step of spreading the refractory granular material taken out from the first container in layers and the step of injecting the mixture (M1) taken out from the second container into desired areas of the refractory granular material spread in layers are repeated until a desired three-dimensional additively manufactured object is manufactured. In this case, it is preferable to carry out the above-mentioned step (c).
In addition, when an antiblocking agent is further contained in the first container, the refractory granular material is used in a state mixed with the antiblocking agent. When the three-dimensional additive manufacturing kit has the refractory granular material and the antiblocking agent independently, the refractory granular material taken out from the first container and the antiblocking agent taken out from the fifth container may be mixed to prepare a mixture (M2), and then the obtained mixture (M2) may be laid out in a layer shape.
Moreover, the mixture (M1) may be replaced with the saccharides taken out from the third container and the polyvalent carboxylic acids taken out from the fourth container.

According to the three-dimensional additive manufacturing kit of the present invention described above, since it has a binder containing sugars and polyvalent carboxylic acids as a binding agent, it is possible to obtain a product using the three-dimensional additive manufacturing kit of the present invention. When the three-dimensional layered product to be produced is a mold, even if it is thermally decomposed during pouring, only carbon dioxide gas, water, etc. are generated, and the working environment during pouring is unlikely to deteriorate.
Furthermore, in the case of a three-dimensional additive manufacturing kit, there is no need to use an acid containing sulfur such as sulfonic acid or sulfuric acid as an acid catalyst. Therefore, when the three-dimensional additively manufactured object obtained using the three-dimensional additive manufacturing kit of the present invention is a mold, the working environment during pouring is important from the viewpoint that sulfur oxides such as sulfur dioxide gas are less likely to be generated during pouring. is unlikely to worsen.
Furthermore, when manufacturing a metal molded body using the three-dimensional additive manufacturing kit of the present invention, even if a degreasing process and a sintering process are performed after step (c), pyrolysis gas and sulfur oxides are not generated. The working environment is less likely to deteriorate during the manufacturing process of metal molded bodies.

As described above, by using the three-dimensional additive manufacturing kit of the present invention, a three-dimensional additive-molded product with a practical strength can be manufactured in a favorable working environment during pouring and during the manufacturing process.
Moreover, since saccharides are plant-derived binders that are made from plants, the 3D additive manufacturing kit of the present invention can be used to produce carbon-neutral 3D additive products, making it possible to use fossil fuels such as oil and coal. By reducing the amount of carbon dioxide, it can contribute to preventing global warming (reducing carbon dioxide) and building a recycling-oriented society through carbon neutrality.
In addition, by using the three-dimensional additive manufacturing kit of the present invention, it is possible to easily manufacture hollow three-dimensional additive-molded products as well as complex shapes.

EXAMPLES Hereinafter, the present invention will be specifically explained with reference to Examples, but the present invention is not limited thereto. The materials used in each example are shown below. Further, various measurement methods are as follows.

[Measurement and evaluation method]
<Measurement of bending strength>
The bending strength of the test pieces obtained in each of the Examples and Comparative Examples was measured using the measurement method described in JACT Test Method SM-1.

<Evaluation of ease of removal>
In the production of the test piece, the ease of taking out the three-dimensional laminate-molded article (test piece) by removing the fire-resistant granular material in the non-printed portion was evaluated using the following evaluation criteria.
<<Evaluation criteria>>
I: The refractory particulate material in the non-printed area can be easily removed by tracing the surface of the test piece with a brush.
II: By scrubbing the surface of the test piece with a brush, the refractory particulate material in the non-printed areas can be removed.
III: The refractory granular material in the non-printing part cannot be removed and it is difficult to take out the test piece.

[Example 1]
Artificial sand obtained by the melting method (manufactured by Ito Kiko Co., Ltd., "Alsand #1000", average particle size 120 μm) was passed through a sieve with openings of 212 μm, and the sand that passed through the sieve was used as the fire-resistant granular material.
Maltose as a sugar, citric acid as a polycarboxylic acid, and water were mixed in a mass ratio of sugar:polycarboxylic acid:water=10:10:80 to prepare a solution (β1), which was used as a binder solution.
The pH at 25°C, viscosity at 25°C, and specific gravity at 25°C of the solution (β1) were measured. The results are shown in Table 1. The pH was measured using a pH meter at 25°C. The viscosity was measured using a B-type viscometer at a rotor speed of 60 rpm and a measurement temperature of 25°C. The rotor used was a No. 1 rotor. The specific gravity was measured in accordance with JIS Z 8804:2012 "Method of measurement of density and specific gravity of liquids."

(Preparation of test pieces)
Using a three-dimensional additive manufacturing device employing a printing modeling method (manufactured by 3D Systems, product name "ZPrinter 310 Plus"), the fire-resistant granular material was laminated to a thickness of 200 μm on the bottom surface (modeling table) of a metal case (length 210 mm, width 260 mm, height 150 mm) installed in the three-dimensional additive manufacturing device using a blade mechanism having a recoater (step (a)).
Next, the print nozzle head was scanned on the laminated refractory granular material based on the data obtained by designing the shape of the three-dimensional laminated object using 3D CAD, and the solution (β1) was printed (step (b1)). After printing the solution (β1), the modeling table of the metal case was lowered by one layer (200 μm), and the refractory granular material was laminated in the same manner as above (step (a)), and the solution (β1) was printed on it (step (b1)). These steps (a) and (b1) were repeated multiple times.
After three hours had elapsed after the final step (b1), the three-dimensional laminated object was taken out of the metal case while buried in the powder of the refractory granular material, and was heat-treated in a dryer at 200°C for one hour (step (c)). After cooling to room temperature (25°C), the refractory granular material in the non-printed portion of the solution (β1) was removed, and a rectangular three-dimensional laminated object measuring 10 mm in length, 60 mm in width, and 10 mm in height was taken out and used as a test piece. Nine test pieces were made at the same time.
The ease of removing the test piece was evaluated. The results are shown in Table 1.

Next, the bending strength of the nine test pieces after being left to cool was measured, and the average value was determined. The results are shown in Table 2.
Further, using the test piece whose bending strength had been measured, the amount of binder added (total amount of sugars and polyvalent carboxylic acids) to 100 parts by mass of the fire-resistant granular material was determined as follows. The results are shown in Table 2.

(Calculation of the amount of binder added)
The test piece was crushed with a file, and 20 g of the crushed material was collected in a crucible. The crushed material was dried in the crucible at 105°C for 1 hour to remove the moisture in the crushed material, and the weight of the crushed material was measured. Next, the crushed material after removing the moisture was heat-treated at 800°C for 3 hours. After cooling, the weight of the crushed material was measured, and the ignition loss of the test piece was calculated using the following formula (1). The results are shown in Table 1.
Ignition loss [%] = (weight [g] of pulverized material before heat treatment at 800 ° C. - weight [g] of pulverized material after heat treatment at 800 ° C.) / weight [g] of pulverized material before heat treatment at 800 ° C. × 100 (1)

Separately, mixed sand was prepared by adding 2.00 parts by mass, 3.00 parts by mass, or 4.00 parts by mass of the same type of solution (β1) as the solution (β1) used to prepare the test pieces to 100 parts by mass of the fire-resistant granular material.
The obtained mixed sand was heat-treated at 200°C for 1 hour and hardened. After cooling, the hardened mixed sand was crushed with a file, and 20 g of the crushed product was collected in a crucible. The crushed product was dried in the crucible at 105°C for 1 hour to remove moisture from the crushed product, and the weight of the crushed product was measured. Next, the crushed product after removing moisture was heat-treated at 800°C for 3 hours. After cooling, the weight of the crushed product was measured, and the ignition loss was calculated using the following formula (2), and a calibration curve was created by plotting the ignition loss on the vertical axis (y) and the amount of solution (β1) added on the horizontal axis (x).
Ignition loss [%] = (weight [g] of pulverized material before heat treatment at 800 ° C. - weight [g] of pulverized material after heat treatment at 800 ° C.) / weight [g] of pulverized material before heat treatment at 800 ° C. × 100 (2)

Using the prepared calibration curve and the results of the ignition loss of the test pieces obtained above, the amount of solution (β1) added to the test pieces per 100 parts by mass of the refractory granular material was calculated, and this was converted into the amount of solution (β1) added to 100 parts by mass of the refractory granular material. The results are shown in Table 1.
The amount of binder added in terms of the pure content per 100 parts by mass of the fire-resistant granular material was calculated from the calculated amount of solution (β1) added and the concentrations of the sugars and polyvalent carboxylic acids in solution (β1). The results are shown in Table 1. In this example, the amount of binder added is the application amount (total amount of sugars and polyvalent carboxylic acids) in terms of the pure content per 100 parts by mass of the fire-resistant granular material for one layer in the printing area when the binder is printed.

[Examples 2 to 8]
A test piece was prepared in the same manner as in Example 1, except that the fire-resistant granular materials of the types shown in Tables 1 and 2 were used, and the solution (β1) prepared to have the composition shown in Tables 1 and 2 was used. was prepared and the ease of taking out the test piece was evaluated. The results are shown in Tables 1 and 2.
The bending strength of the obtained test piece was measured in the same manner as in Example 1. Further, the amount of binder added was determined in the same manner as in Example 1. These results are shown in Tables 1 and 2.
The refractory granular material used in Example 6 was obtained by passing silica sand (manufactured by Mitsubishi Corporation Kenzai Co., Ltd., "Flattary MS-60", average particle size 150 μm) through a sieve with an opening of 212 μm. It is.

[Comparative example 1]
As the refractory granular material, artificial sand obtained by a melting method (manufactured by Ito Kiko Co., Ltd., "Alsand #1000", average particle diameter 120 μm) was used.
To 100 parts by mass of the refractory granular material heated to 130°C, 1 part by mass of an aqueous citric acid solution with a concentration of 50% by mass (0.5 parts by mass in terms of pure citric acid) was added, and after stirring for 3 minutes. After the sand was removed and cooled to room temperature (25° C.), it was passed through a sieve with an opening of 212 μm, and the material that passed through the sieve was collected as a coating material (coated sand).
Separately, a solution (β2) is prepared by mixing maltose, sodium benzoate (preservative), and water so that the mass ratio is maltose: sodium benzoate: water = 20:0.5:79.5, This was used as the injection liquid used in step (b). Regarding the solution (β2), the pH at 25°C, the viscosity at 25°C, and the specific gravity at 25°C were measured in the same manner as in Example 1. The results are shown in Table 3.

Test pieces were prepared in the same manner as in Example 1, except that the covering material (covering sand) was used instead of the refractory granular material and the solution (β2) was used instead of the solution (β1), and the ease of removing the test pieces was evaluated. The results are shown in Table 3.
The bending strength of the obtained test pieces was measured in the same manner as in Example 1. The amount of binder added was determined in the same manner as in Example 1. The results are shown in Table 3.
The amount of binder added in Comparative Example 1 is the amount of maltose, which is a sugar.

[Comparative Example 2]
As the refractory granular material, artificial sand obtained by a fusion method (manufactured by Ito Kiko Co., Ltd., "Alsand #1000", average particle size 120 μm) was used.
To 100 parts by mass of the refractory granular material heated to 150°C, 2 parts by mass of a 50% concentration maltose aqueous solution (1 part by mass in terms of pure maltose) was added, and the mixture was stirred for 5 minutes to volatilize the water, which was the solvent of the maltose aqueous solution. Next, 0.3 parts by mass of calcium stearate was added and stirred for 1 minute, after which the mixture was discharged and cooled to room temperature (25°C), and the mixture was passed through a sieve with 212 μm openings, and the material that passed through the sieve was collected as the coating material (coated sand).
Separately, ethylene glycol (EG) and water were mixed in a mass ratio of EG:water = 5:95 to prepare a solution (β4), which was used as the injection liquid to be used in step (b). The pH, viscosity, and specific gravity of solution (β4) at 25°C were measured in the same manner as in Example 1. The results are shown in Table 3.

Test pieces were prepared in the same manner as in Example 1, except that a coating material (coating sand) was used instead of the refractory granular material and solution (β4) was used instead of solution (β1), and the ease of removing the test pieces was evaluated. The results are shown in Table 3.

As is clear from the results in Tables 1 and 2, in each Example, the test pieces (three-dimensionally laminated objects) could be easily taken out. Furthermore, the test pieces obtained in each Example had high bending strength.
In addition, since the test pieces obtained in each example use a binder containing sugars and polyvalent carboxylic acids, no sulfur dioxide gas is generated even when heated to the temperature at the time of pouring, and the working environment is unlikely to deteriorate.

On the other hand, as is clear from the results in Table 3, in the case of Comparative Example 1, the bending strength of the test piece was high, but when taking out the test piece, it was necessary to rub it more forcefully than in each of the Examples.
In the case of Comparative Example 2, the non-printing area also solidified after the heat treatment (step (c)) and the test piece could not be taken out. Therefore, it was not possible to measure bending strength, etc.

Claims (3)

(a) laying a layer of refractory granular material;
(b) injecting a binder into desired areas of the layered refractory granular material;
The binder comprises a sugar and a polyvalent carboxylic acid,
The method for manufacturing a three-dimensional additive object includes repeating the steps (a) and (b) until a desired three-dimensional additive object is manufactured. The method for producing a three-dimensional additive manufacturing object according to claim 1, further comprising, after at least the last step (b), a step (c) of curing the binder by heating. having a fire-resistant granular material and a binder each independently;
A kit for three-dimensional additive manufacturing, wherein the binder includes saccharides and polycarboxylic acids.