Add water hard components to the manufacturing equipment

Abstract

To provide a hydraulic composition for an additive manufacturing device that can ensure self-standing until the hydraulic composition for the additive manufacturing device is cured, and produce a shaped article with small shrinkage.SOLUTION: A hydraulic composition for an additive manufacturing device includes cement and a lightweight aggregate, and the amount of the lightweight aggregate is 80 to 1,100 pts.mass relative to 100 pts.mass of cement. The lightweight aggregate is preferably an artificial lightweight fine aggregate with an absolute dry density of 2.0 g / cm3 or less and a water absorption rate of 10 to 20%. The hydraulic composition for the additive manufacturing device preferably does not contain an aggregate other than the lightweight aggregate, or contains an aggregate other than the lightweight aggregate in the amount of 50 pts.mass or less per 100 pts.mass of the lightweight aggregate.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a hydraulic composition for additive manufacturing equipment. [Background technology]

[0002] In recent years, a technique has become widespread in which a photocurable resin is extruded from a nozzle onto the top surface of a 3D printer's stacking bed to form an uncured layered body pre-designed as a two-dimensional shape. This uncured layered body is then cured by light irradiation to obtain a cured layered body. Subsequently, the same operation is repeated on top of this cured layered body to build and cure each layer one by one, ultimately obtaining a laminated object with a pre-designed desired three-dimensional shape (for example, one with an intricate three-dimensional shape). This technique is called additive manufacturing. Additive manufacturing technologies using various materials other than photocurable resins (e.g., cement) have also been developed. Patent Document 1 describes a cementitious material for three-dimensional molding in construction that is excellent in self-supporting properties and strength development, comprising: (A) aggregate; (B) a dispersant in which the mass ratio of a lignin sulfonic acid-based dispersant (R) to a melamine sulfonic acid-based dispersant (M) is R:M = 100:80 to 400; (C) a thickener; (D) a setting retarder; (E) amorphous calcium aluminosilicate containing 10 to 25% by mass of SiO2 in terms of oxides; (F) gypsum; and (G) short fibers. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2018-140906 [Overview of the project] [Problems that the invention aims to solve]

[0004] When manufacturing molded objects from hydraulic compositions using an extrusion-type additive manufacturing apparatus, molds and other structures are usually not installed. Therefore, the hydraulic composition is required to have self-supporting properties (the ability to maintain its shape even when a new hydraulic composition is laminated on top of the extruded hydraulic composition) from the time it is extruded from the nozzle of the additive manufacturing apparatus until it hardens. The object of the present invention is to provide a hydraulic composition for additive manufacturing equipment that can ensure self-supporting properties until the hydraulic composition for additive manufacturing equipment hardens, and can produce molded products with minimal shrinkage. [Means for solving the problem]

[0005] As a result of diligent research to solve the above problems, the inventors of the present invention have found that the above objectives can be achieved by a hydraulic composition for additive manufacturing equipment containing cement and lightweight aggregate, wherein the amount of lightweight aggregate per 100 parts by mass of cement is 80 to 1,100 parts by mass, and have completed the present invention. In other words, the present invention provides the following [1] to [7]. [1] A hydraulic composition for additive manufacturing equipment comprising cement and lightweight aggregate, characterized in that the amount of lightweight aggregate per 100 parts by mass of cement is 80 to 1,100 parts by mass. [2] The above lightweight aggregate has an oven-dry density of 2.0 g / cm³. 3 The hydraulic composition for additive manufacturing apparatus according to [1] above, wherein the artificial lightweight fine aggregate is as follows and has a water absorption rate of 10-20%. [3] The hydraulic composition for additive manufacturing apparatus described above, which does not contain any aggregate other than the lightweight aggregate, or contains any aggregate other than the lightweight aggregate in an amount of 50 parts by mass or less per 100 parts by mass of the lightweight aggregate, as described in [1] or [2] above.

[0006] [4] The hydraulic composition for additive manufacturing equipment described above, when cured in air for 28 days at a temperature of 20°C and a relative humidity of 60%, has a length change rate of 500 × 10⁻¹⁰ in accordance with "JIS A 1129-3:2010" (Method for measuring length change of mortar and concrete - Part 3: Dial gauge method).-6 A hydraulic composition for additive manufacturing apparatus according to any of the above [1] to [3], which is one of the following: [5] The hydraulic composition for additive manufacturing apparatus described above is the hydraulic composition for additive manufacturing apparatus described in any of [1] to [4] above, which contains water. [6] The hydraulic composition for additive manufacturing apparatus described above is the hydraulic composition for additive manufacturing apparatus described above [5], comprising a foaming agent in an amount of 25 parts by mass or less per 100 parts by mass of cement. [7] A method for manufacturing a molded object, comprising: a supply step of supplying the hydraulic composition for additive manufacturing apparatus described in [5] or [6] to an additive manufacturing apparatus; and a lamination step of forming a molded object made of the hydraulic composition for additive manufacturing apparatus using the hydraulic composition for additive manufacturing apparatus in the additive manufacturing apparatus. [Effects of the Invention]

[0007] The hydraulic composition for additive manufacturing equipment of the present invention ensures self-supporting properties until the hydraulic composition for additive manufacturing equipment hardens, and enables the production of molded objects with minimal shrinkage. [Modes for carrying out the invention]

[0008] The hydraulic composition for additive manufacturing equipment of the present invention (hereinafter also simply referred to as "hydraulic composition") is a hydraulic composition for additive manufacturing equipment comprising cement and lightweight aggregate, wherein the amount of lightweight aggregate per 100 parts by mass of cement is 80 to 1,100 parts by mass. In this specification, the term "hydraulic composition for additive manufacturing apparatus" includes compositions that do not contain water (e.g., premixes), compositions containing water before curing, and cured bodies obtained by curing compositions containing water. As the cement, when forming an object using an additive manufacturing apparatus, cement having physical properties that can be used as the material of the object can be used. Examples of such cement include various Portland cements such as ordinary Portland cement, early-strength Portland cement, medium-heat Portland cement, low-heat Portland cement, white Portland cement, super-early-strength Portland cement, etc., ultra-rapid hard cement, blast furnace cement, fly ash cement, alumina cement, eco-cement, and the like. These may be used alone or in combination of two or more.

[0009] From the viewpoint of further improving the self-supporting property of the hydraulic composition, the absolute dry density of the lightweight aggregate is preferably 2.0 g / cm 3 Hereinafter, more preferably 1.9 g / cm 3 Hereinafter, even more preferably 1.8 g / cm 3 Hereinafter, particularly preferably 1.7 g / cm 3 Hereinafter. Also, from the viewpoints of easy availability and improvement of the strength development property of the hydraulic composition, the absolute dry density is preferably 0.8 g / cm 3 or more, more preferably 1.0 g / cm 3 or more, even more preferably 1.2 g / cm 3 or more, particularly preferably 1.4 g / cm 3 or more.

[0010] The water absorption rate of the lightweight aggregate is preferably 10 to 20%, more preferably 11 to 19%, and particularly preferably 12 to 18%. If the water absorption rate is 10% or more, the self-supporting property of the hydraulic composition can be further improved; if the water absorption rate is 20% or less, the fluidity of the hydraulic composition can be further improved, and the workability during manufacturing the object is further improved.

[0011] From the viewpoints of easy quality control, less variation in the particle size and water absorption rate of each particle constituting the lightweight aggregate, and improvement of workability when manufacturing an object using an additive manufacturing apparatus, artificial lightweight aggregate is preferred. The lightweight aggregate can be obtained by using, as a raw material, one or more selected from, for example, expanded clay, expanded slate, fly ash, expanded shale, glass, and pozzolan, and firing and foaming these materials. As the lightweight aggregate, only lightweight fine aggregate or a combination of lightweight fine aggregate and lightweight coarse aggregate can be used. Among them, from the viewpoint of workability when manufacturing a shaped object using an additive manufacturing apparatus, usually only lightweight fine aggregate is used. That is, the hydraulic composition for an additive manufacturing apparatus is preferably mortar.

[0012] The amount of the lightweight aggregate with respect to 100 parts by mass of cement is 80 to 1,100 parts by mass, preferably 120 to 1,080 parts by mass, more preferably 180 to 1,050 parts by mass, still more preferably 250 to 1,000 parts by mass, still more preferably 350 to 1,000 parts by mass, still more preferably 500 to 1,000 parts by mass, and still more preferably 800 to 1,000 parts by mass. If the above amount is less than 80 parts by mass, the self-supporting property of the hydraulic composition decreases, and the height of the laminated shaped object becomes small. Also, the shrinkage of the shaped object increases. If the above amount exceeds 1,100 parts by mass, the mass of the hydraulic composition becomes excessive, the shaped object is crushed by its own weight, and it becomes difficult to laminate the hydraulic composition.

[0013] The hydraulic composition for an additive manufacturing apparatus does not contain aggregates other than the above-described lightweight aggregate, or may contain aggregates other than the lightweight aggregate in an amount of 50 parts by mass or less (preferably 5 to 40 parts by mass, particularly preferably 10 to 35 parts by mass) with respect to 100 parts by mass of the lightweight aggregate. By including aggregates other than the lightweight aggregate, the strength of the obtained shaped object can be increased more. Examples of the aggregates other than the lightweight aggregate include only fine aggregate or a combination of fine aggregate and coarse aggregate. Among them, from the viewpoint of workability when manufacturing a shaped object using an additive manufacturing apparatus, usually only fine aggregate is preferred. The fine aggregate is not particularly limited, and examples thereof include river sand, mountain sand, land sand, sea sand, crushed sand, silica sand, and slag fine aggregate. These may be used alone or in combination of two or more. The coarse aggregate is not particularly limited and can include, for example, river gravel, mountain gravel, land gravel, sea gravel, crushed stone, and slag coarse aggregate. These may be used individually or in combination of two or more types.

[0014] When supplying the hydraulic composition for additive manufacturing equipment of the present invention to additive manufacturing equipment, the hydraulic composition for additive manufacturing equipment contains water, and the materials constituting the composition are supplied in the form of a kneaded, uncured mixture. The type of water used is not particularly limited and includes tap water, and recycled water as defined in "JIS A 5308:2019 (Ready-Mixed Concrete)". The amount of water is determined so that the water-binder ratio is preferably 25-50%, more preferably 30-45%, and particularly preferably 35-42%. If the above ratio is 25% or more, the strength of the molded object can be increased. If the above ratio is 50% or less, the molded object can be made less prone to deformation during the process of laminating the hydraulic composition. The water-to-binder ratio is the mass ratio of water to binder (water / binder) expressed as a percentage (%). The binder includes cement and inorganic powders other than cement.

[0015] The cement composition may contain a foaming agent, from the viewpoint of increasing the volume of the resulting molded object. Examples of foaming agents include surfactant-based foaming agents such as anionic surfactants, cationic surfactants, amphoteric surfactants, and nonionic surfactants, as well as protein-based foaming agents. The amount of foaming agent is preferably 25 parts by mass or less, more preferably 0.5 to 23 parts by mass, even more preferably 5 to 22 parts by mass, and particularly preferably 10 to 21 parts by mass, per 100 parts by mass of cement. If the amount is 25 parts by mass or less, the strength of the molded object can be increased. If the amount is 0.5 parts by mass or more, the volume of the resulting molded object can be increased. In particular, if the amount is 5 parts by mass or more, the volume of the resulting molded object can be increased, and the self-supporting properties of the hydraulic composition can be further improved. Typically, foaming agents are added to other ingredients along with water.

[0016] The hydraulic composition for additive manufacturing equipment may contain other materials that can be optionally blended. Other examples of materials include inorganic powders such as silica fume, blast furnace slag powder, fly ash, limestone powder, and silica powder, as well as admixtures such as cement dispersants, setting retarders, and setting accelerators. The amount of inorganic powder (or the total amount if there are two or more types of inorganic powder) is preferably 2 to 150 parts by mass, more preferably 3 to 120 parts by mass, per 100 parts by mass of cement, from the viewpoint of preventing blockage in the additive manufacturing apparatus. Examples of cement dispersants include water-reducing agents, AE water-reducing agents, high-performance water-reducing agents, and high-performance AE water-reducing agents.

[0017] The hydraulic composition for additive manufacturing equipment, in accordance with "JIS A 1129-3:2010" (Method for measuring length change of mortar and concrete - Part 3: Dial gauge method), has a length change rate of preferably 500 × 10 when cured in air for up to 28 days at a temperature of 20°C and a relative humidity of 60%. -6 More preferably, 480 × 10 -6 More preferably, 440 × 10 -6 More preferably, 410 × 10 -6 More preferably 400 × 10 -6 More preferably, 390 × 10 -6 More preferably, 350 × 10 -6 The following is particularly preferred: 300 × 10 -6 The following applies. Note that a smaller rate of change in length means that the resulting molded object will have less shrinkage.

[0018] Furthermore, from the viewpoint of facilitating the manufacture of molded objects using additive manufacturing equipment, the hydraulic composition for additive manufacturing equipment preferably satisfies the following conditions (i) to (ii). (i) The flow value (zero pour flow value) measured without 15 drop tests in accordance with "12 Flow Test" of "JIS R 5201:2015 (Physical Testing Methods for Cement)" shall be 120 mm or less. (ii) The settling time, when measured in accordance with "JIS A 1147:2019 (Test method for concrete setting time)", is less than 4 hours.

[0019] An example of a method for manufacturing a molded object using the hydraulic composition for additive manufacturing equipment of the present invention is a method that includes a supply step of supplying the hydraulic composition for additive manufacturing equipment to an additive manufacturing equipment, and a lamination step of forming a molded object made of the hydraulic composition for additive manufacturing equipment in the additive manufacturing equipment. Hydraulic compositions for additive manufacturing equipment can be prepared by mixing the constituent materials (including at least cement, lightweight aggregate, and water). The mixing means for mixing the materials is not particularly limited, and a mixer commonly used in mixing mortar and concrete can be used. Specifically, examples include vertical mixers, horizontal mixers, Nauter mixers, tilting cylinder mixers, forced mixers, and twin-screw mixers. Examples of vertical mixers include the "Hobart Mixer" manufactured by Hobart and the "Henschel Mixer" manufactured by Henschel. Examples of horizontal mixers include the "Redige Mixer" manufactured by Redige. The prepared hydraulic composition for additive manufacturing is fed into the additive manufacturing apparatus during the supply process. A commercially available general additive manufacturing apparatus (3D printer) can be used as the additive manufacturing apparatus. In the lamination process, a hydraulic composition for additive manufacturing is extruded from a nozzle or the like of the additive manufacturing apparatus to form a two-dimensional layered body. Subsequently, a second layered body is formed on top of this layered body, and the same operation is repeated thereafter to finally form a fabricated object consisting of a laminate with the desired shape. [Examples]

[0020] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. [Materials used] (1) Cement; manufactured by Taiheiyo Cement Corporation, ordinary Portland cement (2) Lightweight aggregate; artificial lightweight fine aggregate, manufactured by Nippon Mesalite Industries Co., Ltd., product name "Mesalite", absolute dry density: 1.65 ± 0.5 g / cm³ 3 , Water absorption rate: 15.0±2.5% (3) Fine aggregate; Silica sand No. 7, maximum particle size: 0.3 mm or less (4) Foaming agent; anionic surfactant, manufactured by Onoda Chemico Co., Ltd., product name "OFA-2" (5) Water; tap water

[0021] [Examples 1-9, Comparative Examples 1-3] Using a Hobart mixer, cement, lightweight aggregate, fine aggregate, and foaming agent, along with water, were mixed in the amounts shown in Table 1 or 2 to prepare a hydraulic composition. The amount of water was set to a water-cement ratio of 40%. The resulting hydraulic composition satisfied the above-described conditions (i) to (ii). As an additive manufacturing apparatus, a gantry frame with a height of 130 mm, a width of 100 mm, and a depth of 1,200 mm, an extrusion nozzle with an inner diameter of 14 mm, a control computer, and a control panel were used. The prepared hydraulic composition was placed in the cartridge of the additive manufacturing apparatus, and the hydraulic composition was extruded from the extrusion nozzle. Additive manufacturing was performed under the conditions of an injection width of 16 mm, a layer thickness of 8 mm, and a layering speed of 30 mm / second to obtain a fabricated object.

[0022] The layer height ratios of the molded objects obtained in Examples 1-9 and Comparative Examples 1-3 were calculated using the molded object obtained in Comparative Example 1 as the reference. Specifically, the ratio of the height of the molded object to the height of the molded object obtained in Comparative Example 1 (height of molded object / height of molded object obtained in Comparative Example 1) was calculated. Furthermore, the rate of change in length of the molded object was measured in accordance with "JIS A 1129-3:2010" (Method for measuring change in length of mortar and concrete - Part 3: Dial gauge method), under an atmosphere of 20°C and 60% relative humidity, after being cured in air for up to 28 days. In contrast, Comparative Example 3 could not be laminated, and the fabricated object was crushed. The results are shown in Tables 3 and 4.

[0023] [Table 1]

[0024] [Table 2]

[0025] [Table 3]

[0026] [Table 4]

[0027] Tables 3-4 show that the layer height ratios (1.2-2.5) of Examples 1-9 are greater than those of Comparative Examples 1-2 (1.0), indicating that the hydraulic compositions of Examples 1-9 exhibit superior self-supporting properties. Furthermore, a comparison of Examples 1-7 shows that the self-supporting properties of the molded object improve as the amount of lightweight aggregate increases. Also, the length change rate of Examples 1-9 (265-461 × 10 -6 ) is the length change rate of Comparative Examples 1-2 (547-621 × 10 -6 The shrinkage is smaller than that of the hydraulic compositions in Examples 1-9, indicating that they exhibit less shrinkage. Furthermore, a comparison of Examples 1-7 shows that shrinkage decreases as the amount of lightweight aggregate increases.

Claims

1. A hydraulic composition for additive manufacturing equipment containing cement and lightweight aggregate, The amount of the lightweight aggregate per 100 parts by mass of the cement is 500 to 1,100 parts by mass. The above lightweight aggregate is an artificial lightweight fine aggregate with an absolute dry density of 2.0 g / cm³ or less and a water absorption rate of 10-20%. The hydraulic composition for additive manufacturing equipment described above is characterized in that it does not contain any aggregate other than the lightweight aggregate described above, or contains any aggregate other than the lightweight aggregate in an amount of 50 parts by mass or less per 100 parts by mass of the lightweight aggregate described above.

2. The hydraulic composition for additive manufacturing equipment described above, when cured in air for 28 days at a temperature of 20°C and a relative humidity of 60%, exhibits a length change rate of 500 × 10⁻¹⁰ in accordance with "JIS A 1129-3:2010" (Method for measuring length change of mortar and concrete - Part 3: Dial gauge method). －６ The hydraulic composition for additive manufacturing apparatus according to claim 1, wherein the composition is as follows:

3. The hydraulic composition for additive manufacturing apparatus described above is the hydraulic composition for additive manufacturing apparatus according to claim 1 or 2, which comprises water.

4. The hydraulic composition for additive manufacturing apparatus according to claim 3, comprising a foaming agent in an amount of 25 parts by mass or less per 100 parts by mass of cement.

5. A supply step of supplying the hydraulic composition for additive manufacturing apparatus described in claim 3 or 4 to the additive manufacturing apparatus, In the additive manufacturing apparatus described above, a lamination process is performed in which a molded object is formed using the hydraulic composition for the additive manufacturing apparatus, A method for manufacturing a molded object, characterized by including the following:

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