Hydraulic composition

Abstract

To provide a hydraulic composition for laminate modeling having good extrudability from a nozzle and good self-supporting property after lamination.SOLUTION: There is provided a hydraulic composition which comprises (A) a water-soluble hydroxyalkyl alkyl cellulose, which is hydroxypropyl methyl cellulose and / or hydroxyethyl methyl cellulose, (B) a defoaming agent, (C) cement, (D) water, (E) a polyvinyl alcohol and (F) borax, wherein the degree of substitution (DS) of alkoxy groups in the water-soluble hydroxyalkyl alkyl cellulose of the component (A) is 1.6 to 2.0, the 2 mass% aqueous solution viscosity of the water-soluble hydroxyalkyl alkyl cellulose at 20°C is 50 to 1000 mPa s, the saponification degree of the polyvinyl alcohol of the component (E) is 70 to 90 mol%, the 4 mass% aqueous solution viscosity of the polyvinyl alcohol at 20°C is 20 to 80 mPa s and the amount added of the water of the component (D) is 25 to 70 pts.mass based on 100 pts,mass of the cement.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a hydraulic composition suitable for additive manufacturing by 3D printing. [Background technology]

[0002] 3D printing is a method (additive manufacturing) of stacking cross-sectional shapes based on 3D data to create a three-dimensional object. There are four main 3D printing methods: binder jetting (a liquid binder is sprayed onto powdered oil to selectively solidify it), directed energy deposition (controlling the location of heat generation to selectively melt and bond materials), material jetting (droplets of material are sprayed, selectively deposited, and solidified), and material extrusion (fluid material is extruded from a nozzle and solidified).

[0003] When using cement-based materials in 3D printing, the material extrusion method is the most suitable of these methods, but the properties required of the material in this case are ease of extrusion from the nozzle and the ability to stand on its own after layering. Since these are contradictory properties, it has been difficult to achieve both.

[0004] In order to solve this problem, JP 2020-105023 A (Patent Document 1) specifies the relationship between the content of cellulose-based thickener and silica fume, thereby achieving both extrudability and self-supporting properties after lamination. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2020-105023 A Summary of the Invention [Problem to be solved by the invention]

[0006] However, in Patent Document 1, the viscosity of a 1% by mass aqueous solution of a cellulose-based thickener is specified for each shear rate, but since hydraulic compositions containing silica fume are highly thixotropic, the properties of the cellulose-based thickener are not utilized, and there are cases in which the desired effects, such as poor dischargeability, are not obtained.

[0007] The present invention has been made in consideration of the above circumstances, and aims to provide a hydraulic composition that is suitable for material extrusion type 3D printing, has good extrudability from a nozzle, and has good self-supporting properties after lamination. [Means for solving the problem]

[0008] As a result of intensive research conducted by the present inventors in order to achieve the above object, the present inventors have found that by using a water-soluble hydroxyalkyl alkyl cellulose having a specific degree of substitution (DS) and aqueous solution viscosity, an antifoaming agent, cement, water, polyvinyl alcohol having a specific degree of saponification and aqueous solution viscosity, and borax, the pressure required for extruding the resulting hydraulic composition from a nozzle is low and the self-supporting property after lamination is good, which has led to the completion of the present invention.

[0009] Accordingly, the present invention provides the following hydraulic composition. 1. A hydraulic composition comprising (A) a water-soluble hydroxyalkyl alkyl cellulose which is at least one selected from hydroxypropyl methyl cellulose and hydroxyethyl methyl cellulose, (B) an antifoaming agent, (C) cement, (D) water, (E) polyvinyl alcohol, and (F) borax, the degree of substitution (DS) of the alkoxy group of the water-soluble hydroxyalkyl alkyl cellulose of component (A) is 1.6 to 2.0, and the viscosity of a 2% by mass aqueous solution of the water-soluble hydroxyalkyl alkyl cellulose at 20°C is 50 to 1000 mPa s; the degree of saponification of the polyvinyl alcohol of the component (E) is 70 to 90 mol %, and the viscosity of a 4 mass % aqueous solution of the polyvinyl alcohol at 20°C is 20 to 80 mPa s; The amount of the water-soluble hydroxyalkyl alkyl cellulose added as component (A) is 0.1 to 0.6 parts by mass relative to 100 parts by mass of the cement, The amount of water added as component (D) is based on 100 parts by mass of the cement. 30 ~70 parts by weight the law of nature, The amount of polyvinyl alcohol added as component (E) is 0.2 to 0.6 parts by mass per 100 parts by mass of the cement, The amount of borax added as component (F) is 0.01 to 0.2 parts by mass per 100 parts by mass of the cement. Hydraulic composition. 2. The amount of water-soluble hydroxyalkyl alkyl cellulose added as component (A) is based on 100 parts by mass of cement. 0.2 ~ 0.5 2. The hydraulic composition according to claim 1, wherein the content is parts by mass. 3. The amount of polyvinyl alcohol (E) added per 100 parts by mass of cement is 0.24 ~ 0.56 3. The hydraulic composition according to 1 or 2, wherein the content is parts by mass. 4. The amount of borax added as component (F) is based on 100 parts by mass of cement. 0.03 ~ 0.18 3. The hydraulic composition according to 1 or 2, wherein the content is parts by mass. 5. 3. The hydraulic composition according to 1 or 2, wherein the component (A) is hydroxypropyl methylcellulose, and the thermal gelation temperature thereof is 55 to 65°C. 6. 3. The hydraulic composition according to 1 or 2, wherein the component (A) is hydroxyethyl methyl cellulose and has a thermal gelling temperature of 68 to 83°C. 7. 3. The hydraulic composition according to 1 or 2, further comprising a re-emulsifiable powdered resin or a polymer dispersion. 8. 3. The hydraulic composition according to 1 or 2, which is for additive manufacturing. 9. 3. The hydraulic composition according to 1 or 2, further comprising a water reducing agent. Effect of the Invention

[0010] According to the present invention, it is possible to provide a hydraulic composition which is a cement-based material suitable for 3D printing using a material extrusion method, has good extrudability from a nozzle, and also has good self-supporting properties after lamination. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] The hydraulic composition according to the present invention will be described below. The hydraulic composition according to the present invention is a hydraulic composition containing (A) a water-soluble hydroxyalkyl alkyl cellulose which is at least one selected from hydroxypropyl methyl cellulose and hydroxyethyl methyl cellulose, (B) an antifoaming agent, (C) cement, (D) water, (E) polyvinyl alcohol, and (F) borax, characterized in that the degree of substitution (DS) of the alkoxy group of the water-soluble hydroxyalkyl alkyl cellulose of the component (A) is 1.6 to 2.0, and the viscosity of a 2% by mass aqueous solution of the water-soluble hydroxyalkyl alkyl cellulose at 20°C is 50 to 1000 mPa s, the degree of saponification of the polyvinyl alcohol of the component (E) is 70 to 90 mol %, and the viscosity of a 4% by mass aqueous solution of the polyvinyl alcohol at 20°C is 20 to 80 mPa s, and the amount of water added of the component (D) is 25 to 70 parts by mass relative to 100 parts by mass of the cement.

[0012] The hydraulic composition according to the present invention is a hydraulic composition containing a water-soluble hydroxyalkyl alkyl cellulose, an antifoaming agent, cement, water, polyvinyl alcohol and borax.

[0013] (Component (A)) The water-soluble hydroxyalkyl alkyl cellulose used in the present invention is at least one selected from hydroxypropyl methyl cellulose (HPMC) and hydroxyethyl methyl cellulose (HEMC).

[0014] The degree of substitution (DS) of the alkoxy group in the water-soluble hydroxyalkyl alkyl cellulose used in the present invention is 1.6 to 2.0, preferably 1.6 to 1.95, more preferably 1.6 to 1.93, and even more preferably 1.65 to 1.93, from the viewpoint of both extrudability from a nozzle and self-supporting property after lamination. The molar substitution (MS) of the hydroxyalkoxy group in the water-soluble hydroxyalkyl alkyl cellulose is preferably 0.05 to 0.6, more preferably 0.1 to 0.5, and even more preferably 0.15 to 0.4, from the viewpoint of solubility during use in summer.

[0015] The DS of the alkoxy group in the water-soluble hydroxyalkyl alkyl cellulose represents the degree of substitution, and refers to the average number of alkoxy groups per unit of anhydrous glucose. The MS of the hydroxyalkoxy group in the water-soluble hydroxyalkyl alkyl cellulose represents the molar substitution, and refers to the average number of moles of hydroxyalkoxy groups per mole of anhydrous glucose. The DS of the alkoxy group and the MS of the hydroxyalkoxy group in the water-soluble hydroxyalkyl alkyl cellulose can be calculated by converting the values ​​measured by the degree of substitution analysis method for hypromellose (hydroxypropyl methylcellulose) described in the 18th revised Japanese Pharmacopoeia.

[0016] The viscosity of a 2% by mass aqueous solution of the water-soluble hydroxyalkyl alkyl cellulose used in the present invention at 20°C is 50 to 1,000 mPa·s, preferably 100 to 800 mPa·s, more preferably 200 to 700 mPa·s, and even more preferably 300 to 600 mPa·s, from the viewpoint of achieving both extrudability from a nozzle and self-supporting properties after lamination. The viscosity of a 2% by mass aqueous solution of the water-soluble hydroxyalkyl alkyl cellulose at 20°C can be measured using a B-type viscometer.

[0017] Here, the water-soluble hydroxyalkyl alkyl cellulose of component (A) has a degree of substitution (DS) of the alkoxy groups of 1.6 to 2.0 and a 2% by mass aqueous solution viscosity of the water-soluble hydroxyalkyl alkyl cellulose at 20°C of 50 to 1000 mPa·s, preferably has a degree of substitution (DS) of the alkoxy groups of 1.6 to 1.95 and a 2% by mass aqueous solution viscosity of the water-soluble hydroxyalkyl alkyl cellulose at 20°C of 100 to 800 mPa·s, and more preferably has a degree of substitution (DS) of the alkoxy groups of 1.65 to 1.93 and a 2% by mass aqueous solution viscosity of the water-soluble hydroxyalkyl alkyl cellulose at 20°C of 300 to 600 mPa·s.

[0018] In addition, a suitable combination of the degree of substitution (DS) of the alkoxy group, the molar substitution number (MS) of the hydroxyalkoxy group in the water-soluble hydroxyalkyl alkyl cellulose, and the viscosity of a 2% by mass aqueous solution at 20° C. is preferably such that, when the component (A) is hydroxypropyl methyl cellulose, the degree of substitution (DS) of the methoxy group is 1.6 to 2.0, the molar substitution number (MS) of the hydroxypropoxy group is 0.05 to 0.6, and the viscosity of a 2% by mass aqueous solution at 20° C. is 5. The degree of substitution of methoxy groups (DS): 1.6 to 1.95, the molar substitution number of hydroxypropoxy groups (MS): 0.1 to 0.5, and the viscosity of a 2% by mass aqueous solution at 20°C: 100 to 800 mPa s, and even more preferably the degree of substitution of methoxy groups (DS): 1.65 to 1.93, the molar substitution number of hydroxypropoxy groups (MS): 0.15 to 0.4, and the viscosity of a 2% by mass aqueous solution at 20°C: 300 to 600 mPa s. Furthermore, when the component (A) is hydroxyethyl methylcellulose, the degree of substitution with methoxy groups (DS) is preferably 1.6 to 2.0, the number of moles of substitution with hydroxyethoxy groups (MS) is preferably 0.05 to 0.6, and the viscosity of a 2% by mass aqueous solution at 20°C is preferably 50 to 1000 mPa s, more preferably the degree of substitution with methoxy groups (DS) is 1.6 to 1.95, the number of moles of substitution with hydroxyethoxy groups (MS) is 0.1 to 0.5, and the viscosity of a 2% by mass aqueous solution at 20°C is preferably 100 to 800 mPa s, and even more preferably the degree of substitution with methoxy groups (DS) is 1.65 to 1.93, the number of moles of substitution with hydroxyethoxy groups (MS) is 0.15 to 0.4, and the viscosity of a 2% by mass aqueous solution at 20°C is preferably 300 to 600 mPa s.

[0019] From the viewpoint of solubility during use in summer, the thermal gelation temperature of the water-soluble hydroxyalkyl alkyl cellulose used in the present invention is preferably 55 to 65°C, more preferably 55 to 64°C, and even more preferably 55 to 63°C when component (A) is hydroxypropyl methylcellulose, and is preferably 68 to 83°C, more preferably 68 to 81°C, and even more preferably 68 to 80°C when component (A) is hydroxyethyl methylcellulose.

[0020] The thermal gelation temperature of the water-soluble hydroxyalkyl alkyl cellulose can be measured using a torsional vibration viscometer. When the water-soluble hydroxyalkyl alkyl cellulose prepared to a concentration of 2% by mass is heated from 20°C at a rate of 1°C / min, the temperature at which the viscosity starts to decrease is defined as the thermal gelation temperature.

[0021] The amount of water-soluble hydroxyalkyl alkyl cellulose added as component (A) is preferably 0.1 to 0.6 parts by mass, more preferably 0.15 to 0.55 parts by mass, and even more preferably 0.2 to 0.5 parts by mass, per 100 parts by mass of cement as component (C), from the viewpoint of achieving both extrudability from a nozzle and self-supporting properties after lamination.

[0022] ((B) component) The defoaming agent has the function of suppressing bubbles entrained by the water-soluble hydroxyalkyl alkyl cellulose. If there are a lot of bubbles, there are problems such as a decrease in strength and poor self-supporting property after lamination. In the present invention, the defoaming agent used is an oxyalkylene type, a silicone type, an alcohol type, a mineral oil type, a fatty acid type, a fatty acid ester type, etc.

[0023] Examples of oxyalkylene-based defoaming agents include polyoxyalkylenes such as (poly)oxyethylene (poly)oxypropylene adducts; (poly)oxyalkylene alkyl ethers such as diethylene glycol heptyl ether, polyoxyethylene oleyl ether, polyoxypropylene butyl ether, polyoxyethylene polyoxypropylene 2-ethylhexyl ether, and oxyethylene oxypropylene adducts to higher alcohols having 8 or more carbon atoms or secondary alcohols having 12 to 14 carbon atoms; (poly)oxyalkylene (alkyl)aryl ethers such as polyoxypropylene phenyl ether and polyoxyethylene nonyl phenyl ether; alkylene aryl ethers to acetylene alcohols such as 2,4,7,9-tetramethyl-5-decyne-4,7-diol, 2,5-dimethyl-3-hexyne-2,5-diol, and 3-methyl-1-butyne-3-ol. acetylene ethers obtained by addition polymerization of ethylene oxides; (poly)oxyalkylene fatty acid esters such as diethylene glycol oleate, diethylene glycol laurate, and ethylene glycol distearate; (poly)oxyalkylene sorbitan fatty acid esters such as polyoxyethylene sorbitan monolaurate and polyoxyethylene sorbitan trioleate; (poly)oxyalkylene alkyl (aryl) ether sulfate salts such as polyoxypropylene methyl ether sodium sulfate and polyoxyethylene dodecylphenol ether sodium sulfate; (poly)oxyalkylene alkyl phosphates such as (poly)oxyethylene stearyl phosphate; (poly)oxyalkylene alkyl amines such as polyoxyethylene laurylamine; and polyoxyalkylene amides.

[0024] Examples of silicone-based defoaming agents include dimethyl silicone oil, silicone paste, silicone emulsion, organic modified polysiloxane (polyorganosiloxane such as dimethylpolysiloxane), fluorosilicone oil, and the like. Examples of alcohol-based defoamers include octyl alcohol, 2-ethylhexyl alcohol, hexadecyl alcohol, acetylene alcohol, and glycols. Examples of mineral oil-based defoaming agents include kerosene and liquid paraffin. Examples of fatty acid-based antifoaming agents include oleic acid, stearic acid, and alkylene oxide adducts thereof. Examples of fatty acid ester-based defoaming agents include glycerin monoricinoleate, alkenyl succinic acid derivatives, sorbitol monolaurate, sorbitol trioleate, and natural waxes. In the present invention, it is preferable to use an oxyalkylene-based defoaming agent from the viewpoint of defoaming performance.

[0025] The amount of the defoaming agent (B) added is preferably 1 to 30 parts by mass, more preferably 3 to 29 parts by mass, and even more preferably 5 to 28 parts by mass, based on 100 parts by mass of the water-soluble hydroxyalkyl alkyl cellulose, from the viewpoints of the deterioration of self-supporting property after lamination due to air bubbles entrained during preparation of the hydraulic composition and the strength of the hydraulic composition.

[0026] ((C) component) The cement usable in the present invention includes various types of cement such as ordinary Portland cement, high-early-strength Portland cement, moderate-heat Portland cement, blast-furnace cement, silica cement, fly ash cement, alumina cement, and ultra-high-early-strength Portland cement.

[0027] ((D) component) The water used in the present invention may be tap water, seawater, or the like, with tap water being preferred from the viewpoint of preventing salt damage. The amount of water added as component (D) is 25 to 70 parts by mass, preferably 28 to 67 parts by mass, and more preferably 30 to 65 parts by mass, per 100 parts by mass of cement. In addition, the amount of water used in the hydraulic composition is preferably 15 to 70 mass %, more preferably 16 to 65 mass %, and even more preferably 17 to 60 mass %, based on the total amount of cement and fine aggregate described below, from the viewpoint of achieving both extrudability from a nozzle and self-supporting property after lamination.

[0028] ((E) component) In the present invention, the component (E) contains polyvinyl alcohol. The saponification degree of the polyvinyl alcohol used in the present invention is 70.0 to 90.0 mol%, preferably 75.0 to 90.0 mol%, more preferably 80.0 to 90.0 mol%, and even more preferably 86.0 to 90.0 mol%, from the viewpoint of compatibility between extrudability from a nozzle and self-supporting property after lamination. The saponification degree of the polyvinyl alcohol can be measured by the method for measuring the saponification degree described in JIS K 6726 (1994).

[0029] The viscosity of a 4% by mass aqueous solution of the polyvinyl alcohol used in the present invention at 20°C is 20 to 80 mPa s, preferably 20 to 70 mPa s, more preferably 20 to 60 mPa s, and even more preferably 25 to 50 mPa s, from the viewpoint of achieving both extrudability from a nozzle and self-supporting properties after lamination. The viscosity of a 4% by mass aqueous solution of polyvinyl alcohol at 20°C can be measured by the viscosity measuring method described in JIS K 6726 (1994).

[0030] In the present invention, the combined requirement for the degree of saponification of the polyvinyl alcohol of component (E) and the viscosity of a 4 mass% aqueous solution at 20°C is 70 to 90 mol% and 20 to 80 mPa·s, preferably 70.0 to 90.0 mol% and 20 to 70 mPa·s, more preferably 75.0 to 90.0 mol% and 20 to 60 mPa·s, even more preferably 80.0 to 90.0 mol% and 20 to 50 mPa·s, and particularly preferably 86.0 to 90.0 mol% and 25 to 50 mPa·s.

[0031] The amount of polyvinyl alcohol added as component (E) is preferably 0.2 to 0.6 parts by mass, more preferably 0.22 to 0.58 parts by mass, and even more preferably 0.24 to 0.56 parts by mass, per 100 parts by mass of cement, from the viewpoint of achieving both extrudability from a nozzle and self-supporting properties after lamination.

[0032] (Component (F)) In the present invention, borax is contained as component (F). The amount of borax added as component (F) is preferably 0.01 to 0.2 parts by mass, more preferably 0.02 to 0.19 parts by mass, and even more preferably 0.03 to 0.18 parts by mass, per 100 parts by mass of cement, from the viewpoint of achieving both extrudability from a nozzle and self-supporting properties after lamination.

[0033] (Other Ingredients) In the hydraulic composition of the present invention, it is preferable to contain a re-emulsified powdered resin or polymer dispersion in order to increase the adhesive strength between the shaped laminates. Specific examples include copolymers such as styrene-butadiene, homopolymers such as vinyl acetate resin, vinyl versatate resin, and acrylic resin.

[0034] The amount of the re-emulsifiable powdered resin or polymer dispersion added is preferably 0.1 to 15 parts by mass, more preferably 0.2 to 10 parts by mass, and even more preferably 0.5 to 8 parts by mass, in terms of solid content, per 100 parts by mass of cement.

[0035] The hydraulic composition of the present invention can further contain fine aggregate. As the fine aggregate, river sand, mountain sand, sea sand, land sand, silica sand, etc., which are generally used in ready-mixed concrete production and fine aggregate for plastering, are suitable. The particle size is preferably 0.075 to 5 mm, more preferably 0.075 to 2 mm, and even more preferably 0.075 to 1 mm.

[0036] The amount of fine aggregate used is preferably 15 to 85 parts by mass, more preferably 20 to 80 parts by mass, and further preferably 25 to 75 parts by mass, per 100 parts by mass of the total amount of cement and fine aggregate.

[0037] Also, a part of the fine aggregate may be replaced with an inorganic or organic filler. In this case, examples of the inorganic filler include fly ash, blast furnace slag, talc, calcium carbonate, silica fume, marble powder (limestone powder), perlite, and shirasu balloons. Examples of the organic filler include expanded polystyrene beads and crushed expanded ethylene vinyl alcohol. Inorganic or organic fillers with a particle size of 5 mm or less are usually used, and these can be used preferably.

[0038] In the present invention, water-soluble polymeric substances other than those mentioned above can be used for the purpose of further improving both the extrudability from the nozzle and the self-supporting property after lamination. In this case, examples of the water-soluble polymeric substances include synthetic polymeric substances such as polyacrylamide and polyethylene glycol, and polymeric substances derived from natural products such as pectin, gelatin, casein, diutan gum, welan gum, xanthan gum, gellan gum, locust bean gum, and guar gum. The amount of the water-soluble polymeric substance added is preferably 0.01 to 1.0 parts by mass, more preferably 0.05 to 0.8 parts by mass, and even more preferably 0.1 to 0.6 parts by mass relative to 100 parts by mass of cement.

[0039] In the hydraulic composition of the present invention, known water reducing agents, setting retarders, setting accelerators, short fibers, expansive agents, shrinkage reducing agents, etc. can be used as necessary within the limits not impairing the effects of the present invention.

[0040] Examples of the water reducing agent include polycarboxylic acid-based agents such as polycarboxylic acid ether-based agents, complexes of polycarboxylic acid ether-based agents and crosslinked polymers, complexes of polycarboxylic acid ether-based agents and oriented polymers, complexes of polycarboxylic acid ether-based agents and highly modified polymers, polyether carboxylic acid-based polymer compounds, maleic acid copolymers, maleic acid ester copolymers, maleic acid derivative copolymers, carboxyl group-containing polyether-based agents, polycarboxylic acid group-containing multicomponent polymers having terminal sulfonic groups, polycarboxylic acid-based graft copolymers, polycarboxylic acid-based compounds, polycarboxylic acid ether-based polymers, etc. Examples of the melamine-based agents include melamine sulfonate formalin condensates, melamine sulfonate condensates, melamine sulfonate polyol condensates, etc. Examples of the lignin-based agents include lignin sulfonate and its derivatives, etc. In the present invention, it is preferable to use a polycarboxylic acid-based water-reducing agent from the viewpoints of water-reducing effect, fluidity and fluidity retention. The amount of the water reducing agent added is preferably 0.1 to 5 parts by mass with respect to 100 parts by mass of cement.

[0041] Examples of the setting retarder include oxycarboxylic acids such as gluconic acid, citric acid, glucoheptone, etc., or inorganic salts thereof such as sodium, potassium, calcium, magnesium, ammonium, etc., sugars such as glucose, fructose, galactose, saccharose, xylose, avitose, lipose, oligosaccharides, dextran, etc., boric acid, etc. The amount of the setting retarder to be added is preferably 0.005 to 10 parts by mass per 100 parts by mass of cement.

[0042] The setting accelerator is roughly divided into inorganic compounds and organic compounds. Examples of inorganic compounds include chlorides such as calcium chloride and potassium chloride, nitrites such as sodium nitrite and calcium nitrite, nitrates such as sodium nitrate and calcium nitrate, sulfates such as calcium sulfate, sodium sulfate, and alum, thiocyanates such as sodium thiocyanate, hydroxides such as sodium hydroxide and potassium hydroxide, carbonates such as calcium carbonate, sodium carbonate, and lithium carbonate, alumina compounds such as water glass, aluminum hydroxide, and aluminum oxide, etc. Examples of organic compounds include amines such as diethanolamine and triethanolamine, calcium salts of organic acids such as calcium formate and calcium acetate, and maleic anhydride, etc. The amount of the setting accelerator added is preferably 0.005 to 10 parts by mass per 100 parts by mass of cement.

[0043] Examples of short fibers include polypropylene fibers, vinylon fibers, acrylic fibers, glass fibers, steel fibers, basalt fibers, etc. The amount of short fibers added is preferably 0.1 to 5 parts by mass, more preferably 0.2 to 4 parts by mass, and even more preferably 0.3 to 3 parts by mass, relative to 100 parts by mass of cement.

[0044] Examples of the expansive material include ettringite-based expansive materials, lime-based expansive materials, and ettringite-lime composite expansive materials. The amount of the expansive material added is preferably 0.5 to 30 parts by mass, more preferably 1 to 30 parts by mass, and even more preferably 3 to 25 parts by mass, relative to 100 parts by mass of cement.

[0045] Examples of the shrinkage reducing agent include lower or higher alcohol alkylene oxide adducts, glycol ether derivatives, polyether derivatives, etc. The amount of the shrinkage reducing agent added is preferably 0.1 to 0.5 parts by mass, more preferably 0.15 to 0.45 parts by mass, and even more preferably 0.2 to 0.4 parts by mass, relative to 100 parts by mass of cement.

[0046] The hydraulic composition of the present invention as described above has good extrudability from a nozzle and also has good self-supporting properties after lamination, making it suitable for additive manufacturing, particularly for 3D printing using a material extrusion method. EXAMPLES

[0047] The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited to the following examples. In the following examples, the viscosity is a value measured using a B-type rotational viscometer at 20°C. The thermal gelation temperature was determined as the temperature at which the viscosity, measured using a torsional vibration type viscometer, began to decrease when water-soluble hydroxyalkyl alkyl cellulose (CE) prepared to 2% by mass was heated from 20°C at a rate of 1°C / min.

[0048] [Examples 1 to 16, Comparative Examples 1 to 6] <Materials used> (1) Cement (C): Ordinary Portland cement (manufactured by Taiheiyo Cement Co., Ltd.) (2) Water: Tap water (3) Water-soluble hydroxyalkyl alkyl cellulose (CE): Sample details are shown in Table 1 (4) Polyvinyl alcohol (PVA): Sample details are shown in Table 2 (5) Borax: First-class reagent (6) Redispersible powder resin (RDP): Mowinyl-Powder DM201P (Japan Coating Resin Co., Ltd.) (7) Defoamer: SN DEFORMER 14HP (manufactured by San Nopco Ltd.)

[0049] [Table 1] HPMC: Hydroxypropyl methylcellulose HEMC: Hydroxyethyl methylcellulose

[0050] [Table 2]

[0051] <Preparation of hydraulic composition> Using a mortar mixer conforming to JIS R 5201, the materials were placed in a mixing bowl in the amounts shown in Table 3, and mixed for 60 seconds at low speed (rotational motion 140 rpm, planetary motion 60 rpm). Next, mixing was performed for 90 seconds at high speed (rotational motion 290 rpm, planetary motion 120 rpm) to obtain a hydraulic composition. The material temperature was adjusted so that the mixing temperature would be within 20±3°C. CE, PVA, borax, and antifoaming agent were mixed with cement in advance, and then added to the mixing bowl together with the cement.

[0052] [Table 3]

[0053] For the obtained hydraulic composition, the shear stress versus shear rate was measured under the following conditions using a rheometer (HAAKE MARS 60 manufactured by Thermo Fisher Scientific). Measurement tool: 20mm bob-type rotor (CC20) Shear rate: increase 0.1s -1 From 100s -1 Up (120 seconds), Down 100s -1 From 0.1s -1 Until (120 seconds) Gap: 4.2mm ·Temperature: 20℃

[0054] The evaluation items were yield value, hysteresis loop (HL) area, and HL area / yield value, and were calculated using the following method. Yield value (Y): The yield value was calculated by fitting the descending curve obtained by decreasing the shear rate, with the horizontal axis being the shear rate and the vertical axis being the shear stress, to a Casson plot. If the yield value was less than 15 Pa, it was evaluated as having excellent dischargeability. ·HL area (A HL): The difference in area between the ascending curve (horizontal axis: shear rate, vertical axis: shear stress) and the descending curve obtained when the shear rate was increased was evaluated, i.e., the area of ​​the hysteresis loop formed by the ascending curve and the descending curve. When the difference was 1000 Pa / s or more, the material was evaluated as having excellent thixotropy. HL area / yield value (A HL / Y): HL area divided by yield value, 150s -1 In the above cases, it was evaluated that the composition had both ejection property and thixotropy. The test results are shown in Table 4.

[0055] [Table 4]

[0056] Examples 1 to 16 used CE and PVA in which "the water-soluble hydroxyalkyl alkyl cellulose, component (A), has a degree of substitution (DS) of the alkoxy group of 1.6 to 2.0, and the water-soluble hydroxyalkyl alkyl cellulose has a 2 mass% aqueous solution viscosity of 50 to 1000 mPa s at 20°C, and the polyvinyl alcohol, component (E), has a degree of saponification of 70 to 90 mol%, and the polyvinyl alcohol has a 4 mass% aqueous solution viscosity of 20 to 80 mPa s at 20°C," and "the amount of water added, component (D), is 25 to 70 parts by mass relative to 100 parts by mass of the cement," met the criteria for all of "yield value," "HL area," and "HL area / yield value." On the other hand, under the conditions of Comparative Examples 1, 3, 4, and 6, the HL area was low and the thixotropy was poor, and among them, Comparative Example 4 had a result in which the HL area / yield value was also below the standard value. In the case of Comparative Example 5, the yield value was high and the ejection property was poor, and the HL area / yield value was also below the standard value. In addition, in the case of Comparative Example 2, the HL area / yield value was below the standard, and both the ejection property and the thixotropy were poor.

[0057] Although the present invention has been described above using the above-mentioned embodiment, the present invention is not limited to this embodiment, and can be modified within the scope of what a person skilled in the art can imagine, such as other embodiments, additions, modifications, deletions, etc., and any aspect is within the scope of the present invention as long as it achieves the effects of the present invention.

Claims

1. A hydraulic composition comprising (A) a water-soluble hydroxyalkyl alkyl cellulose which is at least one selected from hydroxypropyl methyl cellulose and hydroxyethyl methyl cellulose, (B) an antifoaming agent, (C) cement, (D) water, (E) polyvinyl alcohol, and (F) borax, the degree of substitution (DS) of the alkoxy group of the water-soluble hydroxyalkyl alkyl cellulose of component (A) is 1.6 to 2.0, and the viscosity of a 2% by mass aqueous solution of the water-soluble hydroxyalkyl alkyl cellulose at 20°C is 50 to 1000 mPa s; the degree of saponification of the polyvinyl alcohol of component (E) is 70 to 90 mol %, and the viscosity of a 4% by mass aqueous solution of the polyvinyl alcohol at 20° C. is 20 to 80 mPa s; The amount of the water-soluble hydroxyalkyl alkyl cellulose added as component (A) is 0.1 to 0.6 parts by mass per 100 parts by mass of the cement, The amount of water added as component (D) is 30 to 70 parts by mass per 100 parts by mass of the cement, The amount of polyvinyl alcohol added as component (E) is 0.2 to 0.6 parts by mass per 100 parts by mass of the cement, A hydraulic composition in which the amount of borax added as component (F) is 0.01 to 0.2 parts by mass per 100 parts by mass of the cement.

2. 2. The hydraulic composition according to claim 1, wherein the amount of the water-soluble hydroxyalkyl alkyl cellulose added as component (A) is 0.2 to 0.5 parts by mass per 100 parts by mass of cement.

3. 3. The hydraulic composition according to claim 1, wherein the amount of polyvinyl alcohol added as component (E) is 0.24 to 0.56 parts by mass per 100 parts by mass of cement.

4. 3. The hydraulic composition according to claim 1, wherein the amount of borax added as component (F) is 0.03 to 0.18 parts by mass per 100 parts by mass of cement.

5. 3. The hydraulic composition according to claim 1, wherein the component (A) is hydroxypropyl methylcellulose, and the thermal gelling temperature thereof is 55 to 65°C.

6. 3. The hydraulic composition according to claim 1, wherein the component (A) is hydroxyethyl methyl cellulose, and the thermal gelling temperature thereof is 68 to 83°C.

7. 3. The hydraulic composition according to claim 1, further comprising a re-emulsifiable powdered resin or a polymer dispersion.

8. The hydraulic composition according to claim 1 or 2, which is for layered manufacturing.

9. A hydraulic composition as described in claim 1 or 2, further comprising a water reducing agent.

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