Additive used in hydraulic composition for additive manufacturing

Abstract

Provided is an additive having an excellent effect of improving the laminating properties of a hydraulic composition for additive manufacturing. The additive used in the hydraulic composition for additive manufacturing includes a crosslinked polymer in which constituent units derived from an ionic monomer are 90 mol% or less.

Description

Additives used in hydraulic compositions for additive manufacturing

[0001] The present invention relates to an additive for use in a hydraulic composition for layered manufacturing.

[0002] In recent years, additive manufacturing (3D printing) technology has been utilized in the manufacturing industry to create models and parts. These technologies can be categorized into three types: stereolithography (a method of curing and layering UV-curable resin one layer at a time), inkjet printing (a method of spraying UV-curable resin from a printer head while irradiating it with UV light), powdered gypsum printing (a method of spraying resin or glue from a printer head to harden powdered gypsum), powder sintering (a method of baking and solidifying resin or metal powder with a laser), and fused deposition modeling (a method of ejecting molten thermoplastic resin from a thin nozzle to form layers). Models created using additive manufacturing are primarily composed of resin, gypsum, and metal. Technology for creating large models, such as construction components, using hydraulic material compositions has been explored more extensively overseas than in Japan. In Europe, the United States, and China, automated construction machinery is already being used to produce large models, such as those for single-family homes.

[0003] Examples of technologies related to additive manufacturing using hydraulic compositions include the following Patent Documents 1 to 3. Patent Document 1 discloses a technology in which computer-generated 3D data is cut at a predetermined thickness to create 2D slice data, and mortar mixed with an accelerator is sprayed onto a bed (table) while controlling the movement of a spray nozzle in the vertical and horizontal directions based on the 2D slice data. The sprayed mortar is allowed to self-harden, forming a solidified layer of the shape based on the 2D slice data. This solidified layer formation process is repeated to sequentially stack the layers vertically. Patent Document 2 introduces a material for creating molds for castings using a 3D printer, and discloses a material composed of cement, sand, and a water-soluble silicate as an accelerator. Patent Document 3 discloses a method for producing a hydraulic composition for additive manufacturing using an ionic emulsion-type thickener.

[0004] Furthermore, Patent Document 4 discloses a hydraulic composition for additive manufacturing that contains a water-absorbing resin of poly(meth)acrylate, with the aim of reducing drying shrinkage and improving frost resistance.

[0005] Japanese Patent Application Laid-Open No. 10-235623 U.S. Patent No. 8,211,226 JP 2021-133667 A JP 2023-35840 A

[0006] In three-dimensional modeling technology, the hydraulic composition used is mixed, stirred, and extruded using a spray or extrusion nozzle, and then layered one by one. For this reason, the composition must be able to withstand the weight of the upper layers and maintain its three-dimensional shape even after being layered (layerability). This layerability is a performance required specifically for additive manufacturing, and is not required for conventional self-compacting concrete, etc.

[0007] Therefore, additives that improve lamination properties are required for hydraulic compositions for additive manufacturing.

[0008] The present invention provides an additive that is effective in improving the lamination properties of a hydraulic composition for layered manufacturing. Another object of the present invention is to provide an additive that reduces shrinkage that occurs when the hydraulic composition hardens.

[0009] The present invention is characterized by an additive used in a hydraulic composition for additive manufacturing, which contains a crosslinked polymer in which 90 mol % or less of constitutional units derived from ionic monomers are contained.

[0010] FIG. 1 is a schematic diagram showing a method for measuring autogenous shrinkage strain.

[0011] The details of each of the additives of the present invention are explained below. However, the following description is merely an example for explaining the present invention and is not intended to limit the present invention to the scope of the description. In addition, a combination of two or more of the individual preferred embodiments of the present invention described below is also a preferred embodiment of the present invention and is considered to be disclosed in this specification (i.e., it is a legal basis for amendment).

[0012] Furthermore, in this specification, the range "X to Y" means "X or more and Y or less." Unless otherwise specified, operations and measurements of physical properties are performed under conditions of room temperature (20 to 25°C) and a relative humidity of 45 to 55% RH. In this specification, the expression "(meth)acrylic" means "acrylic and / or methacrylic," and the expression "(meth)acrylate" means "acrylate and / or methacrylate." Furthermore, the expression "acid (salt)" means "acid and / or its salt."

[0013] (Examples of the present invention) Preferred configurations of the additives and the like of the present invention are those described in the following (1) to (16) and the like.

[0014] (1) An additive used in a hydraulic composition for additive manufacturing, comprising a crosslinked polymer in which 90 mol % or less of constitutional units derived from ionic monomers are contained.

[0015] (2) The additive according to (1), wherein the crosslinked polymer is obtained by polymerizing a monomer mixture, and the monomer mixture contains 40 mol % or more of a nonionic non-crosslinkable monomer.

[0016] (3) The additive according to (2), wherein the nonionic non-crosslinkable monomer includes a (meth)acrylamide-based monomer.

[0017] (4) The additive according to (2) or (3), wherein the monomer mixture further contains a nonionic crosslinking monomer.

[0018] (5) The additive according to (4), wherein the content of the nonionic crosslinkable monomer is 10.0 mol % or less based on the monomer mixture.

[0019] (6) The additive according to (4) or (5), wherein the nonionic crosslinkable monomer contains a (meth)acrylamide-based monomer.

[0020] (7) The additive according to any one of (1) to (6), wherein the content of the constitutional units derived from the ionic monomer is 50 mol % or less.

[0021] (8) The additive according to any one of (1) to (7), wherein the crosslinked polymer has a water absorption capacity of 35 g / g or less after immersion in an aqueous solution of pH 12.9 at 25° C. for 5 minutes.

[0022] (9) A hydraulic composition for additive manufacturing, comprising the additive according to any one of (1) to (8) and a hydraulic material.

[0023] (10) The hydraulic composition for additive manufacturing according to (9), further comprising a hydraulic material dispersant.

[0024] (11) The hydraulic composition for additive manufacturing according to (10), wherein the hydraulic material dispersant is a polycarboxylic acid-based hydraulic material dispersant.

[0025] (12) A method for producing a hydraulic composition for additive manufacturing, comprising mixing and stirring a hydraulic material and the additive according to any one of (1) to (8).

[0026] (13) A method for producing a layered object, comprising producing a layered object using the composition according to any one of (9) to (11).

[0027] (14) Use of a composition comprising a hydraulic material and the additive according to any one of (1) to (8) for additive manufacturing.

[0028] (15) A method for improving lamination properties when a composition containing a hydraulic material and water is subjected to additive manufacturing, using the additive according to any one of (1) to (8).

[0029] (16) An additive manufacturing method using the composition according to any one of (9) to (11).

[0030] The additives etc. of the present invention are excellent in the effect of improving the lamination properties of the hydraulic composition for layered manufacturing (the effect of improving the lamination properties when added to the hydraulic composition for layered manufacturing).

[0031] Here, improved buildability refers to the ability of a hydraulic composition, such as mortar or fresh concrete, formed from the hydraulic composition to form a desired height, and to maintain the desired height before the hydraulic composition completely hardens. Specifically, for example, a high yield point, as described below, can be mentioned. The yield point is defined as the stress required for a target material to change from elastic to plastic, and a high yield point can improve buildability. The additive of the present invention can increase the yield point of the hydraulic composition for additive manufacturing, thereby improving buildability. The yield point can be measured according to the examples described below. The yield point according to the examples described below is, for example, preferably 570 Pa or more, more preferably 580 Pa or more, even more preferably 590 Pa or more, even more preferably 600 Pa or more, even more preferably 610 Pa or more, even more preferably 630 Pa or more, and particularly preferably 640 Pa or more. Furthermore, the yield point is preferably 570 Pa or more and 1000 Pa or less, 580 Pa or more and 800 Pa or less, 590 Pa or more and 700 Pa or less, 600 Pa or more and 700 Pa or less, 610 Pa or more and 700 Pa or less, 630 Pa or more and 700 Pa or less, or 640 Pa or more and 700 Pa or less.

[0032] The additives of the present invention are also excellent in reducing the shrinkage (particularly the effect of reducing autogenous shrinkage) that occurs when the hydraulic composition for layered manufacturing is hardened.

[0033] Shrinkage reduction can be divided into autogenous shrinkage and drying shrinkage. Here, autogenous shrinkage refers to the phenomenon in which a structure shrinks rapidly due to hydration reactions in an environment with little water dissipation. Because AM processes are particularly large in height, curing is difficult. This makes it easy for water to become unevenly distributed within the structure. However, if the water distribution is uneven within the structure, areas with uneven water distribution will experience significant autogenous shrinkage, while areas without uneven water distribution will not experience autogenous shrinkage (or will experience minimal shrinkage). Therefore, AM processes require even greater autogenous shrinkage reduction than is required for conventional self-compacting concrete.

[0034] The autogenous shrinkage reduction effect can be specifically exemplified by a low free strain, which will be described later. The free strain according to the examples described later is preferably, for example, less than 330 μm, less than 320 μm, or less than 310 μm. The free strain may be 250 μm or more and less than 330 μm, 250 μm or more and less than 320 μm, or 250 μm or more and less than 310 μm.

[0035] (Additive Manufacturing) In this specification, "additive manufacturing" refers to a technology for manufacturing molded bodies of any shape by layering cross-sectional shapes based on three-dimensional data without using dedicated tools such as molds. This technology is also commonly called "3D printing," "three-dimensional modeling," or "rapid prototyping."

[0036] (Hydraulic composition for additive manufacturing) In the present invention, the term "hydraulic composition for additive manufacturing" refers to a hydraulic composition used for additive manufacturing. The hydraulic composition contains a hydraulic material, preferably a hydraulic material and aggregate (coarse aggregate and / or fine aggregate), and may contain other cement admixtures in addition to the additive of the present invention. Examples of other cement admixtures that can be used include antifoaming agents, hydraulic material dispersants, hardening accelerators, and hardening retarders. Furthermore, cement admixtures such as glass fibers and metal fibers may be added. Examples of hydraulic compositions include mortar and fresh concrete.

[0037] In the hydraulic composition for layered manufacturing, the water / cement ratio (mass ratio) is, for example, 0.1 to 0.65, and more preferably 0.1 to 0.5.

[0038] (Additive used in hydraulic composition for additive manufacturing (hereinafter also simply referred to as additive)) The additive of the present invention is used in a hydraulic composition for additive manufacturing. The additive of the present invention is desirably used by being kneaded with a hydraulic composition such as mortar or fresh concrete.

[0039] The additive of the present invention can be used to more specifically limit its use as a layerability improver in additive manufacturing. More specifically, the additive is a layerability improver in additive manufacturing, comprising a crosslinked polymer containing 90 mol % or less of structural units derived from ionic monomers. The additive is also used as a layerability improver for compositions containing a hydraulic material and water, using a crosslinked polymer containing 90 mol % or less of structural units derived from ionic monomers. The additive is also a method for improving layerability during additive manufacturing of a composition containing a hydraulic material and water, using a crosslinked polymer containing 90 mol % or less of structural units derived from ionic monomers.

[0040] A specific method for using the additive of the present invention is, for example, to add it to a hydraulic composition such as mortar or fresh concrete for additive manufacturing and stir it.

[0041] The additive is mainly composed of a crosslinked polymer. Here, the term "main component" refers to 80% by mass or more of the additive, preferably 90% by mass or more, more preferably 95% by mass or more, most preferably 98% by mass or more, and particularly preferably 100% by mass (the upper limit is 100% by mass, i.e., an additive consisting only of a crosslinked polymer).

[0042] In addition to the crosslinked polymer, the additives may contain surfactants, coloring inhibitors, reducing agents, etc., each in an amount of 0 to 10% by mass, preferably 0.1 to 1% by mass, for the purpose of stabilizing the polymer.

[0043] In the hydraulic composition for additive manufacturing, the content of the additive of the present invention (the total amount when a plurality of additives are included) is preferably set to 0.01 to 1 mass % based on the hydraulic material (e.g., cement) in terms of solid content, more preferably 0.02 to 0.8 mass %, even more preferably 0.05 to 0.5 mass %, and particularly preferably 0.1 to 0.3 mass %.

[0044] (Crosslinked Polymer) The crosslinked polymer is preferably a crosslinked body (hereinafter simply referred to as a crosslinked body) having hydrophilic properties or water absorption properties, and more preferably a crosslinked body having water absorption properties when immersed in an aqueous solution of pH 12.9.

[0045] As used herein, the term "crosslinked material having hydrophilicity or water absorption properties" refers to, for example, a polymer gel having a water swelling capacity (CRC) of 5 g / g or more as defined by NWSP 241.0. R2(15) and an Ext (water-soluble content) of 50 mass% or less as defined by NWSP 270.0. R2(15). "NWSP" stands for "Non-Woven Standard Procedures-Edition 2015," which was jointly published by EDANA (European Disposables and Nonwovens Association) and INDA (Association of the Nonwoven Fabrics Industry) to standardize evaluation methods for nonwoven fabrics and their products in the United States and Europe, and indicates standard measurement methods. Unless otherwise specified, in the present invention, physical properties are measured in accordance with "Non-Woven Standard Procedures-Edition 2015."

[0046] Examples of such crosslinked materials include polyacrylamide resins, polyvinyl alcohol resins, polyethylene oxide resins, polyaspartic acid (salt) resins, polyglutamic acid (salt) resins, polyalginic acid (salt) resins, starch resins, cellulose resins, and sugar-modified resins. Examples of crosslinked materials include polymers obtained by polymerizing the following nonionic non-crosslinkable monomers and nonionic crosslinkable monomers, and optionally a monomer mixture containing an ionic monomer. In addition, a resin that is not a crosslinked polymer and has hydrophilic or water-absorbing properties may be combined with the crosslinked polymer.

[0047] The crosslinked polymer may be in the form of a powder or a slurry. If it is a powder, it may be in the form of spheres or aggregates thereof, or in the form of an amorphous (crushed) powder obtained by subjecting a hydrogel or a dried polymer to a pulverization process, but the amorphous (crushed) form is preferred.

[0048] The average particle size (D50) of the crosslinked polymer (powder) is preferably 10 to 1000 μm, more preferably 100 to 850 μm, and even more preferably 200 to 850 μm, 250 to 850 μm, 250 to 850 μm, 250 to 700 μm, and even more preferably 250 to 600 μm. It is believed that increasing the average particle size of the crosslinked polymer (powder) enhances the sustained release of water and further enhances the shrinkage reduction effect. Furthermore, having the average particle size of the crosslinked polymer (powder) below the upper limit above further enhances the lamination property improvement effect.

[0049] When the crosslinked polymer is a crosslinked product having hydrophilicity or water absorption property, the mass average particle size (D50) of the crosslinked product (powder) can be measured by a method similar to the "Average Particle Diameter and Distribution of Particle Diameter Meter" disclosed in European Patent No. 0349240. That is, 10 g of the crosslinked product is classified using JIS standard sieves (JIS Z8801-1 (2000)) or equivalent sieves having mesh sizes of 850 μm, 710 μm, 600 μm, 500 μm, 420 μm, 300 μm, 212 μm, 150 μm, 106 μm, and 45 μm, and the masses of the crosslinked product remaining on each sieve and the crosslinked product that passed through all the sieves are measured. Classification is carried out for 5 minutes using a vibration classifier (IIDA SIEVE SHA KER, TYPE: ES-65, SER. No. 0501), and the particle size distribution is obtained by plotting the residual percentage R on logarithmic probability paper. The particle diameter corresponding to R=50% by mass is then read as the mass-average particle diameter (D50), which can be used as the average particle diameter.

[0050] The crosslinked polymer preferably has a water absorption capacity of 35 g / g or less after immersion in an aqueous solution of pH 12.9 at 25°C for 5 minutes. The crosslinked polymer preferably has a water absorption capacity of 30 g / g or less, 25 g / g or less, or 20 g / g or less after immersion in an aqueous solution of pH 12.9 at 25°C for 5 minutes. When the water absorption capacity of the crosslinked polymer is below the above upper limit, the water absorption performance is not excessively high, and the re-release of absorbed water can be suppressed, thereby improving lamination properties. Note that the water absorption capacity and the yield point, which is an index of lamination properties, are not necessarily directly proportional to each other, and when the water absorption capacity is below the above upper limit, improvement in lamination properties can be expected. The water absorption capacity can be appropriately adjusted, for example, by adjusting the content of the anionic monomer, the content of the nonionic crosslinkable monomer, etc. On the other hand, from the viewpoint of improving lamination properties, it is preferable that the crosslinked polymer has a certain level of water absorption, specifically, the water absorption capacity after immersion in an aqueous solution of pH 12.9 at 25°C for 5 minutes is preferably 5 g / g or more, more preferably 7 g / g or more, from the viewpoint of improving lamination properties, specifically, the water absorption capacity after immersion in an aqueous solution of pH 12.9 at 25°C for 5 minutes is preferably 5 to 35 g / g, 5 to 30 g / g, 5 to 25 g / g, or 7 to 20 g / g.

[0051] Furthermore, the water absorption capacity of the crosslinked polymer when immersed in an aqueous solution of pH 12.9 at 25 ° C. for 1 day is preferably higher than the water absorption capacity after immersion for 5 minutes. The water absorption capacity of the crosslinked polymer when immersed in an aqueous solution of pH 12.9 at 25 ° C. for 1 day is, for example, 10 g / g or more, or 15 g / g or more, or 16 g / g or more. It is thought that the water absorption capacity after a long period of time is higher than the water absorption capacity after immersion for a short time (for example, 5 minutes), and that having a certain level of water absorption performance is effective in laminating properties, shrinkage reduction, etc. The higher the water absorption capacity when immersed in an aqueous solution of pH 12.9 at 25 ° C. for 1 day, the more preferable. The upper limit is not particularly limited, but it is usually 50 g / g or less, 45 g / g or less, or 40 g / g or less. The water absorption capacity after immersion in an aqueous solution of pH 12.9 at 25°C for 1 day may be 10 to 50 g / g, 15 to 45 g / g, 16 to 45 g / g, or 15 to 40 g / g. Note that the above 25°C means that the room temperature is 25°C.

[0052] In this specification, the aqueous solution of pH 12.9 is CaSO ４ ・2H ２ O 1.72g, Na ２ SO ４ 6.96g, K ２ SO ４ The aqueous solution was a mixture of 4.76 g of ammonium hydroxide, 7.12 g of KOH, and 979.4 g of deionized water. The pH of the aqueous solution was 12.9, which simulates the strong alkalinity of the solution when cement is added. Therefore, this aqueous solution can simulate the behavior of the cross-linked polymer when water is added to a cement composition.

[0053] In the crosslinked polymer of the present invention, the content of structural units derived from ionic monomers is 90 mol % or less. If the content of structural units derived from ionic monomers exceeds 90 mol %, the lamination property decreases. The mechanism by which the lamination property decreases significantly when the content of ionic monomers exceeds 90 mol % is unclear, but it is thought that the counter ions in the hydraulic material cause the ionic functional groups in the ionic monomers to aggregate with each other, releasing the absorbed water and causing the moisture to be unevenly distributed, so even if the ionic functional groups are added to the hydraulic composition, the effect of improving the lamination property by the addition is unlikely to be achieved.

[0054] Here, the ionic monomer refers to an anionic monomer and / or a cationic monomer. The structural units derived from the ionic monomer may be 85 mol% or less, 80 mol% or less, 75 mol% or less, 70 mol% or less, 65 mol% or less, 60 mol% or less, or 55 mol% or less. The lower limit of the structural units derived from the ionic monomer is 0 mol%. In other words, the crosslinked polymer may or may not contain structural units derived from the ionic monomer.

[0055] In one embodiment, the additive is used in a hydraulic composition for additive manufacturing, including a crosslinked polymer in which the content of structural units derived from ionic monomers is 50 mol% or less (lower limit: 0 mol%). This embodiment further improves lamination properties. The content of structural units derived from ionic monomers in the crosslinked polymer may be 45 mol% or less, 40 mol% or less, 35 mol% or less, 30 mol% or less, 25 mol% or less, 20 mol% or less, 15 mol% or less, 10 mol% or less, 5 mol% or less, 3 mol% or less, or 1 mol% or less.

[0056] A preferred embodiment of the crosslinked polymer of the present invention is obtained by polymerizing a monomer mixture. The monomer mixture refers to all polymerizable monomers that form the polymer, which is the main component of the polymer, and the total amount of the monomers that form the polymer is 100 mol %. The polymerizable monomer may be a polymerizable monomer (a monomer having an unsaturated double bond).

[0057] The monomer mixture preferably contains a nonionic non-crosslinkable monomer. The monomer mixture more preferably contains a nonionic non-crosslinkable monomer and a nonionic crosslinkable monomer. In this case, both the nonionic non-crosslinkable monomer and the nonionic crosslinkable monomer are polymerizable monomers (monomers having unsaturated double bonds). The nonionic crosslinkable monomer is, for example, a monomer having two or more unsaturated double bonds and serving to crosslink main chains.

[0058] The molar ratio of the constituent units derived from the nonionic non-crosslinkable monomer, the constituent units derived from the nonionic crosslinkable monomer, and the constituent units derived from the anionic monomer may be considered to be the same as that of the respective monomers when charged in production.

[0059] (Nonionic Non-Crosslinkable Monomer) The nonionic non-crosslinkable monomer refers to a nonionic monomer having one unsaturated double bond in the monomer.

[0060] The nonionic non-crosslinkable monomer is preferably water-soluble, since it can further enhance the effects of the present invention. Hereinafter, a water-soluble nonionic non-crosslinkable monomer will also be referred to as a water-soluble nonionic non-crosslinkable monomer. Herein, "water-soluble" in the water-soluble nonionic non-crosslinkable monomer refers to dissolving 5 g or more in 100 g of water at 25°C. The water-soluble nonionic non-crosslinkable monomer preferably dissolves 10 g or more, more preferably 50 g or more, and even more preferably 100 g or more in 100 g of water.

[0061] The nonionic non-crosslinkable monomer is not particularly limited as long as it has one unsaturated double bond, and preferably excludes N-vinyl acylamido. Specific examples of the nonionic non-crosslinkable monomer include (meth)acrylamide-based monomers such as (meth)acrylamide, N-monomethyl(meth)acrylamide, N-monoethyl(meth)acrylamide, N,N-hydroxymethyl(meth)acrylamide, and N,N-dimethyl(meth)acrylamide; N-vinyl lactam-based monomers such as N-vinylpyrrolidone; hydroxyalkyl (meth)acrylates (wherein the hydroxyalkyl group preferably has 1 to 6, 1 to 4, 2 to 3, or 2 carbon atoms) such as hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, hydroxybutyl (meth)acrylate, and hydroxypentyl (meth)acrylate; unsaturated amines such as N-(2-dimethylaminoethyl)(meth)acrylamide, vinylpyridine, and vinylimidazole; vinyl cyanide-based monomers such as acrylonitrile and methacrylonitrile; and unsaturated polyalkylene glycol alkenyl ether-based monomers represented by the following general formula (1):

[0062]

[0063] (In general formula (1), R １ , R ２ , and R ３each independently represents a hydrogen atom or a methyl group, R ４ represents a hydrogen atom or a hydrocarbon group having 1 to 30 carbon atoms, R ａ O may be the same or different and represent an oxyalkylene group having 2 to 18 carbon atoms; n is R ａ represents the average number of moles of oxyalkylene groups added, n is a number from 1 to 500, x is an integer from 0 to 2, and y is 0 or 1. These can be used alone or in combination of two or more.

[0064] In the above general formula (1), R ４ represents a hydrogen atom or a hydrocarbon group having 1 to 30 carbon atoms. Examples of the hydrocarbon group having 1 to 30 carbon atoms include an alkyl group having 1 to 30 carbon atoms (aliphatic alkyl group or alicyclic alkyl group), an alkenyl group having 1 to 30 carbon atoms, an alkynyl group having 1 to 30 carbon atoms, and an aromatic group having 6 to 30 carbon atoms. In order to further exhibit the effects of the present invention, R ４ is preferably a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms, more preferably a hydrogen atom or a hydrocarbon group having 1 to 12 carbon atoms, even more preferably a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms, and particularly preferably a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. In the above general formula (1), n ​​is a number from 1 to 500, preferably 10 to 300, and more preferably 10 to 100. R ａ O may be the same or different and represent an oxyalkylene group having 2 to 18 carbon atoms, preferably an oxyalkylene group having 2 to 8 carbon atoms, and more preferably an oxyalkylene group having 2 to 4 carbon atoms. ａThe addition form of O may be any of random addition, block addition, alternating addition, etc. In order to ensure a balance between hydrophilicity and hydrophobicity, it is preferable that oxyethylene groups are contained as an essential component in the oxyalkylene group, more preferably 50 mol % or more of the entire oxyalkylene group are oxyethylene groups, even more preferably 90 mol % or more of the entire oxyalkylene group are oxyethylene groups, and particularly preferably 100 mol % of the entire oxyalkylene group are oxyethylene groups. In the above general formula (1), x is an integer of 0 to 2, preferably 1 or 2. y is 0 or 1, preferably 0. The unsaturated polyalkylene glycol alkenyl ether monomer represented by the above general formula (1) can be produced by a conventionally known method. Specific examples include a product in which ethylene oxide is added to the hydroxyl groups of 3-methyl-3-buten-1-ol (isoprenol) (the average number of moles added is preferably 10 to 100).

[0065] In addition, since the effect of improving lamination properties is excellent, the nonionic non-crosslinkable monomer preferably contains at least one selected from the group consisting of a (meth)acrylamide-based monomer, a hydroxyalkyl (meth)acrylate, and an unsaturated polyalkylene glycol alkenyl ether-based monomer represented by the above general formula (1), more preferably contains at least one selected from the group consisting of a (meth)acrylamide-based monomer and a hydroxyalkyl (meth)acrylate, more preferably contains a (meth)acrylamide-based monomer, even more preferably contains a (meth)acrylamide, and particularly preferably contains acrylamide. When the nonionic non-crosslinkable monomer contains a (meth)acrylamide-based monomer, the content of the (meth)acrylamide-based monomer in the nonionic non-crosslinkable monomer may be 50 mol% or more (up to 100 mol%), 75 mol% or more, 80 mol% or more, 85 mol% or more, 90 mol% or more, or 95 mol% or more. Furthermore, it is a preferred embodiment that the nonionic non-crosslinkable monomer is composed solely of a (meth)acrylamide-based monomer, and the nonionic non-crosslinkable monomer may be composed solely of (meth)acrylamide or solely of acrylamide.

[0066] Another preferred embodiment is one in which the nonionic non-crosslinkable monomer is a combination of a (meth)acrylamide monomer and an unsaturated polyalkylene glycol alkenyl ether monomer represented by the general formula (1) above.

[0067] In terms of improving lamination properties, the content of the nonionic non-crosslinkable monomer in the monomer mixture is preferably 10 mol% or more, 15 mol% or more, 20 mol% or more, 25 mol% or more, 30 mol% or more, or 35 mol% or more. In a preferred embodiment of the present invention, the crosslinked polymer is obtained by polymerizing a monomer mixture, and the monomer mixture contains 40 mol% or more of the nonionic non-crosslinkable monomer. The content of the nonionic non-crosslinkable monomer in the monomer mixture is preferably 45 mol% or more, 50 mol% or more, 55 mol% or more, 60 mol% or more, 65 mol% or more, 70 mol% or more, 75 mol% or more, 80 mol% or more, 85 mol% or more, 90 mol% or more, 93 mol% or more, 94 mol% or more, 95 mol% or more, 97 mol% or more, 98 mol% or more, or 99 mol% or more. In order to ensure water absorption performance, the upper limit of the content of the nonionic non-crosslinkable monomer in the monomer mixture is preferably 99.95 mol% or less. The content of the nonionic non-crosslinkable monomer in the monomer mixture may also be 99.85 mol% or less. The content of each monomer in the monomer mixture is calculated to two decimal places. The content of the nonionic non-crosslinkable monomer in the monomer mixture may be 10 to 99.95 mol%, 15 to 99.95 mol%, 20 to 99.95 mol%, 25 to 99.95 mol%, 30 to 99.95 mol%, 35 to 99.95 mol%, 40 to 99.95 mol%, 45 to 99.95 mol%, 50 to 99.95 mol%, 55 to 99.95 mol%, 60 to 99.95 mol%, 70 to 99.95 mol%, 80 to 99.95 mol%, 90 to 99.95 mol%, 10 ...00 to 99.95 mol%, 100 to 99 9.95 mol%, 65 to 99.95 mol%, 70 to 99.95 mol%, 75 to 99.95 mol%, 80 to 99.95 mol%, 85 to 99.95 mol%, 90 to 99.95 mol%, 93 to 99.95 mol%, 95 to 99.95 mol%, 97 to 99.95 mol%, 98 to 99.90 mol%, or 99 to 99.85 mol%.

[0068] (Nonionic crosslinkable monomer) The nonionic crosslinkable monomer is a monomer having two or more polymerizable unsaturated groups. The nonionic crosslinkable monomer forms a crosslinked structure (crosslinked body), which improves water absorption performance and lamination property, so that it is preferable that the monomer mixture contains a nonionic crosslinkable monomer.

[0069] The nonionic crosslinkable monomer is preferably water-soluble, since it can further enhance the effects of the present invention. Hereinafter, a water-soluble nonionic crosslinkable monomer will also be referred to as a water-soluble nonionic crosslinkable monomer. Herein, "water-soluble" in the water-soluble nonionic crosslinkable monomer refers to a monomer that dissolves in an amount of 5 g or more in 100 g of water. The water-soluble nonionic crosslinkable monomer preferably dissolves in an amount of 10 g or more in 100 g of water, more preferably dissolves in an amount of 50 g or more, and even more preferably dissolves in an amount of 100 g or more.

[0070] The nonionic crosslinkable monomer is not particularly limited, but is preferably a compound having two or more polymerizable unsaturated groups, and examples thereof include (meth)acrylamide monomers such as N,N'-methylenebis(meth)acrylamide; (poly)ethylene glycol di(meth)acrylates such as diethylene glycol diacrylate, (poly)propylene glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, ethylene oxide-modified trimethylolpropane tri(meth)acrylate, and polyfunctional (meth)acrylates such as pentaerythritol hexa(meth)acrylate; and allyl esters of cyanuric acid or isocyanuric acid such as triallyl cyanurate and triallyl isocyanurate. These may be used alone or in combination of two or more.

[0071] Among these, the nonionic crosslinkable monomer preferably contains at least one selected from the group consisting of a (meth)acrylamide-based monomer, an allyl ester of cyanuric acid or isocyanuric acid, and a polyfunctional (meth)acrylate, more preferably contains at least one selected from the group consisting of a (meth)acrylamide-based monomer and a polyfunctional (meth)acrylate, and more preferably contains at least one selected from the group consisting of a (meth)acrylamide-based monomer and a polyethylene glycol di(meth)acrylate (preferably having 3 to 50 ethylene glycol repeating units, preferably polyethylene glycol diacrylate). A suitable nonionic non-crosslinkable monomer is a (meth)acrylamide-based monomer, and furthermore, lamination properties are further improved. Therefore, the nonionic crosslinkable monomer also preferably contains a (meth)acrylamide-based monomer, more preferably N,N'-methylenebis(meth)acrylamide, and even more preferably N,N'-methylenebisacrylamide. Furthermore, the nonionic crosslinkable monomer may be only a (meth)acrylamide-based monomer, or may be only N,N'-methylenebis(meth)acrylamide, or may be only N,N'-methylenebisacrylamide.

[0072] From the viewpoint of lamination properties, the (total) content of the nonionic crosslinkable monomer in the monomer mixture is preferably 0.01 mol% or more, 0.05 mol% or more, 0.1 mol% or more, or 0.15 mol% or more. Furthermore, from the viewpoint of lamination properties, the content of the nonionic crosslinkable monomer in the monomer mixture is preferably 15.0 mol% or less, more preferably 10.0 mol% or less, preferably 8.0 mol% or less, more preferably 5.0 mol% or less, even more preferably 3.0 mol% or less, and even more preferably 1.0 mol% or less. The content of the nonionic crosslinkable monomer in the monomer mixture is preferably 0.01 to 15.0 mol%, 0.01 to 10.0 mol%, 0.01 to 8.0 mol%, 0.05 to 5.0 mol%, 0.1 to 3.0 mol%, or 0.15 to 1.0 mol%.

[0073] The nonionic crosslinkable monomer may be added in its entirety to the prepared aqueous solution of the nonionic non-crosslinkable monomer before the polymerization step, or a portion of it may be added after the initiation of polymerization.

[0074] (Anionic Monomer) The anionic monomer refers to a monomer having an anionic functional group or a salt thereof. The anionic functional group refers to a functional group that becomes an anion (anionizes) upon dissociation of a counter ion.

[0075] Examples of the anionic functional group or a salt thereof include a sulfonic acid (salt) group, a sulfuric acid (salt) group, a phosphoric acid (salt) group, a phosphonic acid (salt) group, and a carboxylic acid (salt) group (a carboxyl group or a salt thereof).

[0076] Examples of the anionic monomer include (meth)acrylic acid, (anhydrous) maleic acid, itaconic acid, cinnamic acid, vinyl sulfonic acid, allyl toluene sulfonic acid, vinyl toluene sulfonic acid, styrene sulfonic acid, methallyl sulfonic acid, 2-sulfoethyl methacrylate Na, 2-hydroxy-3-allyloxypropane sulfonic acid, isoprene sulfonic acid, 2-(meth)acrylamido-2-methylpropane sulfonic acid, 2-(meth)acryloylethane sulfonic acid, 2-(meth)acryloylpropane sulfonic acid, 2-hydroxyethyl (meth)acryloyl phosphate, mono(2-hydroxyethyl) methacrylic acid ester, mono(2-hydroxyethyl) acrylic acid ester, and polyalkylene glycol mono(meth)acrylate acid phosphate ester, and salts thereof. The salt is preferably a salt with a monovalent cation, more preferably at least one selected from alkali metal salts, ammonium salts, and amine salts, even more preferably an alkali metal salt, still more preferably at least one selected from sodium salts, lithium salts, and potassium salts, with sodium salts being particularly preferred. The anionic monomer preferably contains at least one selected from the group consisting of (meth)acrylic acid (salt), (anhydrous) maleic acid (salt), and 2-acrylamido-2-methylpropanesulfonic acid (salt), preferably contains (meth)acrylic acid (salt), preferably contains acrylic acid (salt), or may consist solely of acrylic acid (salt).

[0077] The content of the anionic monomer in the monomer mixture is 90 mol % or less because the content of the ionic monomer is 90 mol % or less. By having the content of the anionic monomer in the monomer mixture be 90 mol % or less, the initial water absorption by the crosslinked polymer and the release of absorbed water from the crosslinked polymer are suppressed, and lamination properties are exhibited.

[0078] In one embodiment, the ionic monomer consists solely of anionic monomers (no cationic monomers are included). That is, in one embodiment, the additive is used in a hydraulic composition for additive manufacturing, including a crosslinked polymer in which the constituent units derived from anionic monomers account for 90 mol% or less (lower limit: 0 mol%). In this case, the constituent units derived from anionic monomers may account for 85 mol% or less, 80 mol% or less, 75 mol% or less, 70 mol% or less, 65 mol% or less, 60 mol% or less, 55 mol% or less, 50 mol% or less, 45 mol% or less, 40 mol% or less, 35 mol% or less, 30 mol% or less, 25 mol% or less, 20 mol% or less, 15 mol% or less, 10 mol% or less, 5 mol% or less, 3 mol% or less, or 1 mol% or less. In one embodiment, the additive is used in a hydraulic composition for additive manufacturing, including a crosslinked polymer in which the constituent units derived from (meth)acrylic acid (salt) account for 90 mol% or less. In this case, the structural units derived from (meth)acrylic acid (salt) may be 85 mol% or less, 80 mol% or less, 75 mol% or less, 70 mol% or less, 65 mol% or less, 60 mol% or less, 55 mol% or less, 50 mol% or less, 45 mol% or less, 40 mol% or less, 35 mol% or less, 30 mol% or less, 25 mol% or less, 20 mol% or less, 15 mol% or less, 10 mol% or less, 5 mol% or less, 3 mol% or less, or 1 mol% or less.

[0079] (Cationic Monomer) The cationic monomer refers to a monomer having a cationic functional group or a salt thereof. The cationic functional group refers to a functional group that becomes a cation (cationized) upon dissociation of a counter ion.

[0080] The cationic monomers include quaternized N-vinylimidazole, quaternized N-allylimidazole, quaternized 4-vinylpyridine, quaternized 1-[2-(acryloyloxy)ethyl]-1H-imidazole, 1-[2-(methacryloyloxy)ethyl]-1H-imidazole, and salts thereof.

[0081] The content of the cationic monomer in the monomer mixture is preferably 20 mol% or less, and in order of preference is less than 10 mol%, 5 mol% or less, 4 mol% or less, 3 mol% or less, 2 mol% or less, and 1 mol% or less, and most preferably 0 mol% (i.e., no cationic monomer is contained).

[0082] In a preferred embodiment of the present invention, the crosslinked polymer is obtained by polymerizing a monomer mixture containing 20 mol% or more of a nonionic non-crosslinkable monomer and 0.1 mol% or more of a nonionic crosslinkable monomer, and the content of the anionic monomer in the monomer mixture is 70 mol% or less. In a preferred embodiment of the present invention, the crosslinked polymer is obtained by polymerizing a monomer mixture containing 40 mol% or more of a nonionic non-crosslinkable monomer and 0.1 mol% or more of a nonionic crosslinkable monomer, and the content of the anionic monomer in the monomer mixture is 50 mol% or less. In a preferred embodiment of the present invention, the monomers constituting the crosslinked polymer consist of 40 mol% or more of a nonionic non-crosslinkable monomer, 0.1 mol% or more of a nonionic crosslinkable monomer, and 50 mol% or less (preferably 40 mol% or less) of an anionic monomer. In this case, it is also preferable that the nonionic non-crosslinkable monomer includes at least one selected from the group consisting of a (meth)acrylamide-based monomer and a hydroxyalkyl (meth)acrylate, and that the nonionic crosslinkable monomer includes at least one selected from the group consisting of a (meth)acrylamide-based monomer, an allyl ester of cyanuric acid or isocyanuric acid, and a polyfunctional (meth)acrylate. Furthermore, it is preferable that the anionic monomer is (meth)acrylic acid (salt). In this case, the content of the nonionic crosslinkable monomer in the monomer mixture is preferably 0.01 to 15.0 mol%, 0.01 to 10.0 mol%, or 0.01 to 8.0 mol%, more preferably 0.05 to 8.0 mol%, and even more preferably 0.1 to 8.0 mol%, and may be 0.05 to 5.0 mol%, 0.1 to 3.0 mol%, or 0.15 to 1.0 mol%.

[0083] In a preferred embodiment of the present invention, the monomers forming the crosslinked polymer do not contain ionic monomers (anionic monomers and cationic monomers). In a preferred embodiment of the present invention, the monomers in the monomer mixture consist of nonionic monomers. In a preferred embodiment of the present invention, the monomers in the monomer mixture consist of only nonionic non-crosslinkable monomers and nonionic crosslinkable monomers. In a preferred embodiment of the present invention, the monomers in the monomer mixture consist of only (meth)acrylamide-based monomers.

[0084] Furthermore, in a preferred embodiment of the present invention, the crosslinked polymer is obtained by polymerizing a nonionic non-crosslinking monomer and a nonionic crosslinking monomer. In a preferred embodiment of the present invention, the crosslinked polymer is obtained by polymerizing a nonionic non-crosslinking monomer and a nonionic crosslinking monomer, the nonionic non-crosslinking monomer includes a (meth)acrylamide-based monomer, and the nonionic crosslinking monomer includes at least one selected from the group consisting of a (meth)acrylamide-based monomer, an allyl ester of cyanuric acid or isocyanuric acid, and a polyfunctional (meth)acrylate. In a preferred embodiment of the present invention, the crosslinked polymer is obtained by polymerizing a monomer mixture including acrylamide and N,N'-methylenebisacrylamide. In a preferred embodiment of the present invention, the crosslinked polymer is obtained by polymerizing a monomer mixture containing acrylamide, N,N'-methylenebisacrylamide, and acrylic acid (the content of acrylic acid is preferably 85 mol% or less, 80 mol% or less, 75 mol% or less, 70 mol% or less, 65 mol% or less, 60 mol% or less, 55 mol% or less, 50 mol% or less, 45 mol% or less, 40 mol% or less, 35 mol% or less, 30 mol% or less, 25 mol% or less, 20 mol% or less, 15 mol% or less, 10 mol% or less, 5 mol% or less, 3 mol% or less, or 1 mol% or less). In this case, the content of the nonionic crosslinkable monomer in the monomer is preferably 0.01 to 8.0 mol%, and may be 0.05 to 5.0 mol%, 0.1 to 3.0 mol%, or 0.15 to 1.0 mol%.

[0085] (Method for producing crosslinked polymer) The method for producing the crosslinked polymer is not particularly limited, and the crosslinked polymer can be produced by a conventionally known method. In particular, the crosslinked polymer is preferably a crosslinked body having hydrophilic properties or water absorption properties, and known methods for producing such crosslinked bodies can be referred to as appropriate. Polymerization methods for obtaining the crosslinked polymer include spray polymerization, droplet polymerization, bulk polymerization, precipitation polymerization, aqueous solution polymerization, and reversed-phase suspension polymerization, and here, as an example, a production method using aqueous solution polymerization is mentioned.

[0086] (1) Step of Preparing an Aqueous Monomer Mixture Solution This step is a step of preparing an aqueous monomer mixture solution by dissolving each of the monomers constituting the polymer in water as a solvent.

[0087] The monomers may be added all at once or sequentially. Here, the term "aqueous solution" includes an aqueous dispersion. The aqueous monomer mixture solution may contain components constituting cement additives, such as trace components (chelating agents, surfactants, dispersants, etc.), as necessary.

[0088] The "aqueous solution" in the aqueous monomer mixture solution is not limited to a solution in which 100 mass % of the solvent is water, and a water-soluble organic solvent (e.g., alcohol) may be used in combination in an amount of 0 to 30 mass %, preferably 0 to 5 mass %, and these are treated as aqueous solutions in the present invention.

[0089] (2) Aqueous Solution Polymerization Step Aqueous solution polymerization is a method of polymerizing an aqueous monomer solution without using a dispersion solvent, and is disclosed, for example, in U.S. Pat. Nos. 4,625,001, 4,873,299, 4,286,082, 4,973,632, 4,985,518, 5,124,416, 5,250,640, 5,264,495, 5,145,906, 5,380,808, European Patent Nos. 0,811,636, 0,955,086, and 0,922,717.

[0090] The concentration of the aqueous monomer solution during the polymerization is not particularly limited, but is preferably 20% by mass to the saturated concentration or less, more preferably 25 to 80% by mass, and even more preferably 30 to 70% by mass. A concentration of 20% by mass or more can suppress a decrease in productivity. Note that polymerization in a monomer slurry (aqueous dispersion) is prone to a decrease in physical properties, so it is preferable to carry out the polymerization at a saturated concentration or less.

[0091] In the polymerization step, a polymerization initiator is added to the aqueous monomer mixture solution obtained above.

[0092] The polymerization initiator to be used is appropriately determined depending on the polymerization form and is not particularly limited, but examples thereof include photodegradable polymerization initiators, thermally degradable polymerization initiators, redox-based polymerization initiators, etc. Polymerization is initiated by these polymerization initiators.

[0093] Examples of the photodegradable polymerization initiator include benzoin derivatives, benzyl derivatives, acetophenone derivatives, benzophenone derivatives, azo compounds, etc. Specific examples include benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, α-methylbenzoin, α-phenylbenzoin, anthraquinone, methylanthraquinone, acetophenone, 2,2-diethoxyacetophenone, 2,2-dimethoxy-2-phenylacetone, benzyldiacetylacetophenone, benzophenone, p-chlorobenzophenone, 2-hydroxy-2-methylpropiophenone, diphenyl disulfide, tetramethylthiuram sulfide, α-chloromethylnaphthalene, Examples include anthracene, hexachlorobutadiene, pentachlorobutadiene, Michler's ketone, 2-chlorothioxanthone, 2,4-diethylthioxanthone, benzyl dimethyl ketal, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropanone-1,2-hydroxy-2-methyl-1-phenylpropan-1-one, and 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propan-1-one. Such photodegradable polymerization initiators may be commercially available products, and examples thereof include Irgacure (registered trademark) 184 (hydroxycyclohexyl-phenyl ketone) and Irgacure (registered trademark) 2959 (1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propan-1-one), both of which are trade names of Ciba Specialty Chemicals.

[0094] Examples of the thermally decomposable polymerization initiator include persulfates such as sodium persulfate, potassium persulfate, and ammonium persulfate; peroxides such as hydrogen peroxide, t-butyl peroxide, and methyl ethyl ketone peroxide; and azo compounds such as 2,2′-azobis(2-amidinopropane)dihydrochloride and 2,2′-azobis[2-(2-imidazolin-2-yl)propane]dihydrochloride.

[0095] Furthermore, examples of the redox polymerization initiator include a system in which a reducing compound such as L-ascorbic acid or sodium hydrogen sulfite is used in combination with the persulfate or peroxide.

[0096] The photodecomposition type polymerization initiator may be used in combination with the thermal decomposition type polymerization initiator. Furthermore, active energy rays such as ultraviolet rays, electron beams, and γ rays may be used alone or in combination with the above polymerization initiators.

[0097] The amount of the polymerization initiator used is preferably 0.0001 to 1 mol %, more preferably 0.0005 to 0.5 mol %, based on the amount of the monomer.

[0098] The polymerization step can be carried out under normal pressure, reduced pressure, or increased pressure, but is preferably carried out under normal pressure (or a pressure close to normal pressure, typically ±10 mmHg). The temperature at the start of polymerization is preferably 15 to 130°C, more preferably 20 to 120°C, although this depends on the type of polymerization initiator used.

[0099] In this way, a gel-like crosslinked polymer is obtained.

[0100] (3) Gel Crushing Step This step is an optional step in which a gel-like crosslinked polymer (hereinafter referred to as "hydrogel") obtained through the above-mentioned polymerization step or the like (particularly aqueous solution polymerization) is gel-crushed to obtain a particulate hydrogel (hereinafter referred to as "particulate hydrogel").

[0101] The gel crusher that can be used is not particularly limited, and examples thereof include a batch or continuous double-arm kneader or the like, a gel crusher equipped with a plurality of rotating stirring blades, a single-screw extruder, a twin-screw extruder, a meat chopper, etc. Among these, a screw-type extruder having a perforated plate at the tip is preferred, and an example thereof includes the screw-type extruder disclosed in JP-A-2000-063527.

[0102] (4) Drying step This step is a step of drying the hydrogel obtained through the polymerization step or the like to obtain a dried polymer. When the polymerization step is aqueous solution polymerization, gel pulverization (granulation) is performed before and / or after drying of the hydrogel. Furthermore, the dried polymer (aggregate) obtained in the drying step may be directly supplied to the pulverization step.

[0103] The drying method is not particularly limited, and various methods can be used. Specific examples include heat drying, hot air drying, reduced-pressure drying, infrared drying, microwave drying, azeotropic dehydration drying with a hydrophobic organic solvent, and high-humidity drying using high-temperature water vapor, and the like. One or two of these methods can be used in combination. The drying temperature is preferably 100 to 300°C, more preferably 120 to 250°C. The drying time depends on the surface area and water content of the hydrogel, the type of dryer, and the like, but is preferably, for example, 1 minute to 5 hours.

[0104] (5) Grinding and Classification Step This step is a step in which the dried polymer obtained in the drying step is ground and / or classified to obtain a polymer of a specific particle size. Note that this step differs from the gel grinding step (3) in that the material to be ground is subjected to a drying step.

[0105] The particle size can be controlled in the polymerization step, the gel crushing step, or the crushing and classification step in the drying step, but it is particularly preferably controlled in the classification step after drying.

[0106] (Hydraulic Material) The "hydraulic material" used in the present invention is a hydraulic substance, a pozzolanic reactive substance, or a latent hydraulic substance, and preferably contains a hydraulic substance. When the hydraulic material contains a pozzolanic reactive substance or a latent hydraulic substance, it is desirable that the hydraulic material further contains cement (or calcium hydroxide) and a stimulant.

[0107] (Hydraulic Substance) In the present invention, the "hydraulic substance" refers to so-called cement, and examples of cement include Portland cement (normal, early-strength, ultra-early-strength, moderate-heat, low-heat, sulfate-resistant, and their low-alkali forms), various blended cements (blast furnace cement, silica cement, fly ash cement), white Portland cement, alumina cement, ultra-rapid-hardening cement (1-clinker rapid-hardening cement, 2-clinker rapid-hardening cement, magnesium phosphate cement), cement for grouting, oil well cement, low-heat cement (low-heat blast furnace cement, fly ash-mixed low-heat blast furnace cement, belite-rich cement), ultra-high-strength cement, cement-based solidification material, and ecocement (cement produced using one or more of municipal waste incineration ash and sewage sludge incineration ash as raw materials). The cement in the present invention may be one type, or two or more types.

[0108] (Pozzolanic reactive substance) In the present invention, a "pozzolanic reactive substance" is a substance that does not have hydraulic properties by itself, but gradually combines with components in concrete (for example, calcium hydroxide produced by cement hydration) to form an insoluble compound (for example, calcium silicate hydrate), and examples include natural pozzolan, fly ash, cinder ash, clinker ash, husk ash, metakaolin, and silica fume, with fly ash being preferred. Fly ash comes in types I, II, III, and IV, with type II being preferred. The pozzolan reactive substance is desirably in the form of granules with a particle size of 0.01 to 10 mm.

[0109] (Latent hydraulic substance) In the present invention, a "latent hydraulic substance" is a substance that does not harden simply by mixing with water, but hardens in the presence of a small amount of a substance called a stimulant, such as slag (blast furnace slag, slowly cooled blast furnace slag, steelmaking slag, etc.). The latent hydraulic substance is preferably in the form of granules with a particle size of 0.01 to 10 mm.

[0110] Examples of the stimulant include an aqueous solution of an alkali metal carbonate, an aqueous solution of an alkali metal fluoride, an aqueous solution of an alkali metal hydroxide, an aqueous solution of an alkali metal aluminate, an aqueous solution of an alkali metal silicate (e.g., water glass), and / or a mixture thereof, and can be added to the composition containing the latent hydraulic material of the present invention.

[0111] (Aggregate) The aggregate used in the present invention may be any appropriate aggregate, such as fine aggregate (sand, etc.) or coarse aggregate (crushed stone, etc.). Examples of such aggregates include sand, gravel, crushed stone, granulated slag, recycled aggregate, and refractory aggregates such as silica, clay, zircon, high alumina, silicon carbide, graphite, chromium, chromium-magnesium, and magnesia. These aggregates may be used alone or in combination of two or more. The amount of aggregate added is, for example, 10 to 500 parts by mass per 100 parts by mass of the hydraulic material.

[0112] (Antifoaming Agents) Examples of antifoaming agents include polyoxyalkylene alkyl ethers such as diethylene glycol heptyl ether; polyoxyalkylene acetylene ethers; (poly)oxyalkylene fatty acid esters; polyoxyalkylene sorbitan fatty acid esters; polyoxyalkylene alkyl (aryl) ether sulfates; polyoxyalkylene alkyl phosphates; polyoxypropylene polyoxyethylene laurylamine (e.g., 1 to 20 moles of propylene oxide added, 1 to 20 moles of ethylene oxide added), and polyoxyalkylene alkylamines such as amines derived from fatty acids obtained from hardened beef tallow to which alkylene oxide has been added (e.g., 1 to 20 moles of propylene oxide added, 1 to 20 moles of ethylene oxide added); oxyalkylene antifoaming agents such as polyoxyalkylene amides; mineral oil-based, oil-based, fatty acid-based, fatty acid ester-based, alcohol-based, amide-based, phosphate ester-based, metal soap-based, and silicone-based antifoaming agents. These antifoaming agents may be used alone or in combination of two or more.

[0113] (Hydraulic Material Dispersant) As the hydraulic material dispersant, conventionally known hydraulic material dispersants can be used. Examples of the hydraulic material dispersant include polyalkylarylsulfonate-based dispersants such as naphthalenesulfonic acid formaldehyde condensates; melamine formalin resin sulfonate-based dispersants such as melamine sulfonic acid formaldehyde condensates; aromatic aminosulfonate-based dispersants such as aminoarylsulfonic acid-phenol-formaldehyde condensates; lignin sulfonate-based dispersants such as lignin sulfonates and modified lignin sulfonates; various sulfonic acid-based dispersants having sulfonic acid groups in the molecule, such as polystyrene sulfonate-based dispersants; copolymers obtained from polyalkylene glycol mono(meth)acrylate-based monomers, (meth)acrylic acid-based monomers, and monomers copolymerizable with these monomers, as described in JP-B No. 59-18338 and JP-A No. 7-223852; and copolymers obtained from JP-A No. 10-236858. JP-A-2001-220417, JP-A-2002-121055, JP-A-2002-121056, JP-A-2018-111622, unsaturated (poly) alkylene glycol ether monomers as described in, maleic acid monomers or (meth) acrylic acid monomers, such as copolymers obtained from various polycarboxylic acid dispersants having a (poly) oxyalkylene group and a carboxyl group in the molecule; (alkoxy) polyalkylene glycol mono(meth)acrylates as described in JP-A-2006-52381, phosphate monoester monomers, and various phosphate dispersants having a (poly) oxyalkylene group and a phosphate group in the molecule such as copolymers obtained from phosphate diester monomers, and phosphate dispersants described in JP-T-2008-517080. Among these, it is preferable to use a polycarboxylic acid-based hydraulic material dispersant as the hydraulic material dispersant, since the effects of the present invention are more effectively achieved. The hydraulic material dispersant may be one type or two or more types.

[0114] The polycarboxylic acid-based hydraulic material dispersant is a polymer obtained by polymerizing a monomer component containing an unsaturated carboxylic acid (salt). Examples of the polycarboxylic acid-based hydraulic material dispersant include a copolymer of polyethylene glycol monoallyl ether and maleic acid (salt); a copolymer obtained by copolymerizing a monomer component consisting of polyalkylene glycol (meth)allyl ether or polyalkylene glycol (meth)acrylate, an unsaturated sulfonate, and a (meth)acrylate; a copolymer of (meth)acrylamide and (meth)acrylic acid (salt); a copolymer obtained by copolymerizing a monomer component consisting of (meth)acrylamide having a sulfonate group, a (meth)acrylic acid ester, and a (meth)acrylic acid (salt); a copolymer of polyalkylene glycol vinyl ether or polyalkylene glycol (meth)allyl ether and (meth)acrylic acid (salt); a copolymer of polyalkylene glycol (meth)acrylate and (meth)acrylic acid (salt); and a copolymer obtained by polymerizing a monomer component containing, as essential components, an unsaturated carboxylic acid (salt) and a monomer having a polyalkylene glycol chain.

[0115] Among the above examples, a copolymer obtained by polymerizing a monomer component containing, as essential components, an unsaturated carboxylic acid (salt) and a monomer having a polyalkylene glycol chain (the average number of moles of alkylene oxide added is preferably 1 to 500 moles). Examples of the unsaturated carboxylic acid (salt) include acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, citraconic acid, etc., as well as neutralized and partially neutralized products thereof, and one or more of these can be used. Examples of monomers having a polyalkylene glycol chain include hydroxyalkyl (meth)acrylates such as hydroxylethyl (meth)acrylate; polyalkylene glycol mono(meth)acrylates such as ethylene glycol mono(meth)acrylate, polyethylene glycol / polypropylene glycol mono(meth)acrylate; alkoxypolyalkylene glycol mono(meth)acrylates such as methoxypolyethylene glycol mono(meth)acrylate, ethoxypolyethylene glycol mono(meth)acrylate; polyalkylene glycol mono(meth)allyl ethers such as ethylene glycol mono(meth)allyl ether; alkoxypolyalkylene glycol mono(meth)allyl ethers such as methoxypolyethylene glycol mono(meth)allyl ether; ethers; polyalkylene glycol monochloroethyl ethers such as ethylene glycol monochloroethyl ether; alkoxypolyalkylene glycol monochloroethyl ethers such as methoxypolyethylene glycol monochloroethyl ether; and compounds in which 1 to 500 moles of alkylene oxide are added to any of vinyl alcohol, (meth)allyl alcohol, 3-methyl-3-buten-1-ol (isoprenol), 3-methyl-2-buten-1-ol, 2-methyl-3-buten-2-ol, 2-methyl-2-buten-1-ol, and 2-methyl-3-buten-1-ol (e.g., polyethylene glycol mono(3-methyl-3-butenyl) ether, polyoxyethylene (mono(meth)allyl) ether, etc.), and one or more of these can be used. These polycarboxylic acid-based hydraulic material dispersants can be used alone or in a suitable mixture of two or more.

[0116] In the hydraulic composition, the blending ratio of the hydraulic material dispersant is preferably set to, for example, 0.01 to 10 mass % in terms of solid content relative to the total amount of hydraulic material, from the viewpoint of dispersibility, etc., more preferably 0.02 to 5 mass %, and even more preferably 0.05 to 3 mass %. In this specification, the solid content can be measured as follows.

[0117] (Method for measuring solid content) 1. Accurately weigh the aluminum dish. 2. Accurately weigh the sample for solid content measurement onto the aluminum dish accurately weighed in 1. 3. Place the sample for solid content measurement accurately weighed in 2 in a dryer adjusted to 130°C under a nitrogen atmosphere for 1 hour. 4. After 1 hour, remove from the dryer and allow to cool in a desiccator at room temperature for 15 minutes. 5. After 15 minutes, remove from the desiccator and accurately weigh the aluminum dish + sample for measurement. 6. Subtract the mass of the aluminum dish obtained in 1 from the mass obtained in 5, and divide by the mass of the sample for solid content measurement obtained in 2 to measure the solid content.

[0118] (Method for Producing Hydraulic Composition for Layer-by-Layer Manufacturing) Examples of methods for producing the hydraulic composition for layer-by-layer manufacturing include a production method including a step of mixing and stirring a hydraulic material and the additive of the present invention.

[0119] When producing a hydraulic composition for additive manufacturing, the additive, hydraulic material, other cement admixtures, and water may be mixed at once; the additive and hydraulic material may be mixed together, followed by the other cement admixtures and water; or the hydraulic material, other cement admixtures, and water may be mixed together, followed by the addition of the additive of the present invention. Considering the ease of manifestation of the effect, it is preferable to mix the additive, hydraulic material, and powder cement admixture, followed by the liquid cement admixture and water. In this case, cement admixtures such as dispersants and antifoaming agents may be added together with the additive or separately. It is preferable to mix admixtures such as aggregates (e.g., sand) and fibers before adding water.

[0120] Furthermore, after the above step in the manufacturing method, it is desirable that the fresh concrete be layered on top of another fresh concrete immediately (for example, within 0 to 300 seconds after the above step).

[0121] <Layer-by-Layer-Modeled Article and Layer-by-Layer-Modeling Method> The hydraulic composition of the present invention is suitable for use in layer-by-layer manufacturing. Therefore, the present invention also provides a layer-by-layer-modeled article formed from the hydraulic composition for layer-by-layer manufacturing of the present invention.

[0122] Another embodiment is a method for producing a layered shaped object (shaped body) using the hydraulic composition of the above embodiment.

[0123] Furthermore, another embodiment is an additive manufacturing method using the hydraulic composition of the above embodiment.

[0124] A method for producing a layered object using the hydraulic material composition for layered manufacturing (layered manufacturing method) includes a step of extruding the hydraulic composition of the above embodiment from a nozzle and laminating the hydraulic composition. The layered manufacturing method according to this embodiment preferably includes a step of pressure-feeding the hydraulic composition for layered manufacturing with compressed air, a pump, or the like, and a step of extruding the pressure-fed hydraulic composition for layered manufacturing through a nozzle and laminating the hydraulic composition for layered manufacturing to form a layered object. Since the additive of the present invention can improve the lamination properties without reducing the fluidity of the hydraulic composition, it is preferable to add the additive of the present invention before pressure-feeding the hydraulic composition with compressed air, a pump, or the like. That is, a method for producing a layered object using the hydraulic composition for layered object manufacturing (layered object manufacturing method) includes the steps of preparing a hydraulic composition for layered object manufacturing containing the additive of the present invention, pressure-feeding the obtained hydraulic composition for layered object manufacturing using compressed air, a pump, etc., and extruding the pressure-fed hydraulic composition for layered object manufacturing through a nozzle to laminate the hydraulic composition for layered object manufacturing. After the pressure-fed hydraulic composition for layered object manufacturing is extruded through the nozzle, a known thickener or the like may be added to further improve lamination properties.

[0125] A nozzle (discharge part) is usually provided at the tip of the pressure-feeding pipe for the hydraulic composition for additive manufacturing. The diameter of the nozzle is not particularly limited, but may be set appropriately depending on the size of the aggregate used and the width of the layer of the hydraulic composition for additive manufacturing. For example, if the size of the aggregate is 5 mm or less and the layer width is 50 mm or less, the nozzle diameter is preferably 8 to 15 mm. The shape of the nozzle is not particularly limited, but examples include circular, elliptical, rectangular, cross, and star shapes, and a brim may be provided around the nozzle to impart smoothness to the surface of the discharged hydraulic material composition.

[0126] When building a structure by layering the hydraulic composition for additive manufacturing discharged from a nozzle, the nozzle may be moved vertically or horizontally to build a structure using the hydraulic composition for additive manufacturing. For example, it is preferable to fix the nozzle to a robot arm or a portal plotter and control the movement of the nozzle by computer. A possible method involves cutting three-dimensional data created by a computer at a predetermined thickness to create two-dimensional slice data, controlling the movement of the spray nozzle in horizontal directions such as vertical, horizontal, and diagonal based on the two-dimensional slice data, discharging the hydraulic composition for additive manufacturing from the nozzle, and moving the nozzle vertically to repeatedly build up layers one by one. The nozzle movement speed is not particularly limited and can be changed depending on the width of the layer.

[0127] The effects of the present invention will be explained using the following examples and comparative examples. In the examples, the terms "parts" and "%" are sometimes used, but unless otherwise specified, they represent "parts by mass" or "% by mass." Furthermore, unless otherwise specified, each operation is carried out at room temperature (25°C).

[0128] [Production Example 1] Powdered Crosslinked Polymer 1 (Crosslinked Polymer with Hydrophilic or Water-Absorbent Properties) 29.9 g of acrylamide, 0.0974 g of N,N-methylenebisacrylamide, and 45.5 g of water were charged into a 1000 ml cylindrical separable flask and uniformly dissolved. After purging with nitrogen, the flask was heated to 45°C in a water bath, and 12.56 g of a 1% aqueous solution of sodium persulfate and 12.04 g of a 0.1% aqueous solution of L-ascorbic acid were added. Stirring was stopped to allow polymerization. Here, the monomer mixture consisting of acrylamide and N,N'-methylenebisacrylamide contained 99.85 mol% acrylamide and 0.15 mol% N,N'-methylenebisacrylamide. After the initiation of polymerization, heat was generated and the temperature rose to 80°C after 10 minutes. When the liquid temperature stopped rising, the bath temperature was raised to 80°C and the mixture was aged for 30 minutes. The resulting gel polymer (hydrogel) was fragmented, dried with hot air at 130°C for 3 hours, pulverized, and then sieved using JIS standard sieves with mesh sizes of 500 μm and 250 μm. Particles larger than 500 μm were repeatedly pulverized in a roll mill until all particles passed through a 500 μm wire mesh, yielding a powdery crosslinked polymer 1 having a D50 shown in Table 1. The water absorption capacity of the powdery crosslinked polymer 1 in an aqueous solution at pH 12.9 after 5 minutes was 11.5 g / g. The water absorption capacity of the powdery crosslinked polymer 1 in an aqueous solution at pH 12.9 after 1 day was 23.8 g / g.

[0129] [Production Example 2] Powdered Crosslinked Polymer 2 (Crosslinked Polymer with Hydrophilic or Water-Absorbing Properties) 17.83 g of acrylamide, 12.08 g of acrylic acid, 0.0969 g of N,N-methylenebisacrylamide, and 45.67 g of water were charged into a 1000 ml cylindrical separable flask and uniformly dissolved. After replacing the atmosphere in the flask with nitrogen, the flask was heated to 45°C on a water bath, and 12.49 g of a 1% aqueous solution of sodium persulfate and 11.97 g of a 0.1% aqueous solution of L-ascorbic acid were added. Stirring was stopped to allow polymerization to proceed. After the start of polymerization, heat was generated and the temperature rose to 80°C after 10 minutes. When the liquid temperature stopped rising, the bath temperature was raised to 80°C and the mixture was aged for 30 minutes. The resulting gel-like polymer (hydrogel) was fragmentized, then hot air dried at 130°C for 3 hours, pulverized, and sieved using JIS standard sieves with mesh sizes of 500 μm and 250 μm to obtain powdery crosslinked polymer 2 having a D50 shown in Table 1. Here, the monomer mixture consisting of acrylamide, acrylic acid, and N,N'-methylenebisacrylamide contained 59.85 mol% acrylamide, 40 mol% acrylic acid, and 0.15 mol% N,N'-methylenebisacrylamide. The water absorption capacity of powdery crosslinked polymer 2 in an aqueous solution at pH 12.9 after 5 minutes was 26.1 g / g. Furthermore, the water absorption capacity of powdery crosslinked polymer 2 in an aqueous solution at pH 12.9 after 1 day (24 hours) was 35.0 g / g.

[0130] [Production Examples 3 to 12] The powdery crosslinked polymers of Production Examples 3 to 12 described below were prepared in the same manner as in Production Example 1 above, using a monomer mixture selected from acrylamide, N,N-methylenebisacrylamide, acrylic acid, PEGDA (polyethylene glycol diacrylate (n=9) (=diacrylate of polyethylene glycol (ethylene oxide 8 mol adduct to ethylene glycol))), and HEA (hydroxyethyl acrylate). For the polymers obtained in Production Examples 5 and 6, sieving was performed using the following combination of sieves instead of the combination of 500 μm and 250 μm meshes. In Production Example 5, particles that passed through a sieve with a 710 μm mesh and remained on a 500 μm mesh were collected. In Production Example 6, particles that passed through a sieve with a 250 μm mesh and remained on a 125 μm mesh were collected. The composition ratios (mol %) of the structural units of the crosslinked polymers of Production Examples 3 to 12 are as follows: Production Example 3: Acrylamide / N,N-methylenebisacrylamide = 99 / 1 Production Example 4: Acrylamide / HEA / N,N-methylenebisacrylamide = 80 / 19 / 1 Production Example 5: Acrylamide / N,N-methylenebisacrylamide = 99 / 1 Production Example 6: Acrylamide / N,N-methylenebisacrylamide = 99 / 1 Production Example 7: Acrylamide / acrylic acid / N,N-methylenebisacrylamide = 81 / 18 / 1 Production Example 8: Acrylic acid / PEGDA = 35 / 65 Production Example 9: Acrylamide / acrylic acid / N,N-methylenebisacrylamide / PEGDA = 37.15 / 54.93 / 0.13 / 7.79 Production Example 10: Acrylamide / acrylic acid / N,N-methylenebisacrylamide / PEGDA = 20.55 / 62.03 / 1.22 / 16.20 Production Example 11: Acrylamide / N,N-methylenebisacrylamide / PEGDA=94.86 / 4.99 / 0.15 Production Example 12: Acrylamide / N,N-methylenebisacrylamide / PEGDA=84.87 / 14.98 / 0.15 The D50, water absorption capacity of an aqueous solution at pH 12.9 after 5 minutes, and water absorption capacity of an aqueous solution at pH 12.9 after 1 day (24 hours) of Production Examples 3 to 12 were as shown in Table 1.

[0131] Comparative Production Example 1: 29.9 g of acrylic acid, 0.0961 g of N,N-methylenebisacrylamide, and 45.87 g of water were charged into a 1000 ml cylindrical separable flask and uniformly dissolved. After replacing the atmosphere in the flask with nitrogen, the flask was heated to 45°C in a water bath, and 45.87 g of a 1% aqueous solution of sodium persulfate and 12.39 g of a 0.1% aqueous solution of L-ascorbic acid were added. Stirring was stopped to allow polymerization. After the start of polymerization, heat was generated and the temperature rose to 80°C after 10 minutes. When the increase in liquid temperature stopped, the bath temperature was raised to 80°C and aged for 30 minutes. The resulting gel-like polymer (hydrogel) was fragmented, dried with hot air at 130°C for 3 hours, pulverized, and sieved using JIS standard sieves with mesh sizes of 500 μm and 250 μm to obtain a comparative powdery crosslinked polymer 1 having a D50 shown in Table 1. Here, the monomer mixture consisting of acrylic acid and N,N'-methylenebisacrylamide contained 99.85 mol% acrylic acid and 0.15 mol% N,N'-methylenebisacrylamide. The water absorption capacity of comparative powdery crosslinked polymer 1 in an aqueous solution at pH 12.9 after 5 minutes was 46.0 g / g. Furthermore, the water absorption capacity of comparative powdery crosslinked polymer 1 in an aqueous solution at pH 12.9 after 5 days was 40.3 g / g.

[0132] [Production Example A: Production of Hydraulic Material Dispersant A] 80.0 parts of ion-exchanged water was charged into a glass reaction vessel equipped with a Dimroth condenser, a Teflon (registered trademark) stirrer with stirring blades and agitation seal, a nitrogen inlet tube, and a temperature sensor. The mixture was heated to 70°C while stirring at 250 rpm and introducing nitrogen at 200 mL / min. Next, a mixed solution of 133.4 parts of methoxypolyethylene glycol monomethacrylate (average number of ethylene oxide added: 23), 26.6 parts of methacrylic acid, 1.53 parts of mercaptopropionic acid, and 106.7 parts of ion-exchanged water was added dropwise over 4 hours. Simultaneously, a mixed solution of 1.19 parts of ammonium persulfate and 50.6 parts of ion-exchanged water was added dropwise over 5 hours. After completion of the addition, the temperature was maintained at 70°C for 1 hour to complete the polymerization reaction. The mixture was then neutralized with aqueous sodium hydroxide solution to obtain a polymer (Hydraulic Material Dispersant A).

[0133] [Production Example B: Production of Hydraulic Material Dispersant B] A glass reaction vessel equipped with a Dimroth condenser, a stirrer with Teflon (registered trademark) stirring blades and stirring seal, a nitrogen inlet tube, and a temperature sensor was charged with 198.2 parts of a solution obtained by adding ethylene oxide to the hydroxyl groups of 3-methyl-3-buten-1-ol (isoprenol) (average number of moles of ethylene oxide added: 50) (hereinafter referred to as IPN-50) (80% aqueous solution), 0.32 parts of acrylic acid, 12.47 parts of aqueous hydrogen peroxide (2% aqueous solution), and 44.75 parts of ion-exchanged water, and the mixture was heated to 58°C while stirring at 250 rpm and introducing nitrogen at a rate of 200 mL / min. Next, a mixed solution consisting of 27.12 parts of acrylic acid and 108.5 parts of ion-exchanged water was added dropwise over 3 hours, and at the same time, a mixed solution consisting of 0.74 parts of L-ascorbic acid, 1.61 parts of 3-mercaptopropionic acid, and 86.31 parts of ion-exchanged water was added dropwise over 3 hours and 30 minutes. After completion of the addition, the temperature was maintained at 58°C for 1 hour to complete the polymerization reaction. Then, the mixture was neutralized with an aqueous sodium hydroxide solution to obtain a polymer (hydraulic material dispersant B).

[0134] <Mortar Preparation> Mortar tests were conducted in an environment with a temperature of 20°C ± 1°C and a relative humidity of 60% ± 15%. The mortar mix was C / S / W = 690 / 1600 / 331.2 (g). Here, C: cement (ordinary Portland cement, manufactured by Taiheiyo Cement Corporation); S: fine aggregate (sand from Kakegawa); W: ion-exchanged aqueous solution of dispersant and antifoaming agent. W contained the dispersant and antifoaming agent listed in the table below and was thoroughly and uniformly dissolved in ion-exchanged water. Adekanol LG-299 (manufactured by Adeka) was used as the antifoaming agent, and was added at 0.007 mass% of the cement addition amount. The amount of dispersant added was adjusted so that the mortar flow values ​​were equivalent. The additives were added to the cement in the amounts listed in the table below. Using a mortar mixer (Hobart mixer, model number: N-50), C and S with the additives added were charged into a mixing vessel and mixed at first speed for 10 seconds. While mixing was continued at first speed, W was added over 10 seconds. The mixer was stopped 60 seconds after mixing began, and the mortar was scraped off for 30 seconds. After that, mixing was continued for a further 60 seconds at second speed to prepare mortar. This mortar was used for the following dispersibility evaluation, yield point evaluation, and autogenous shrinkage strain evaluation. The mortar samples used for each evaluation were prepared each time an evaluation was performed.

[0135] <Dispersibility Evaluation> The mortar obtained as described above was half-filled into a mini-slump cone (JIS microconcrete slump cone, upper inner diameter 50 mm, lower inner diameter 100 mm, height 150 mm) placed on a flow measuring plate (60 cm x 60 cm) and rammed 15 times with a ramming rod. Further mortar was filled to the brim of the mini-slump cone and rammed 15 times with the ramming rod, after which the surface of the mini-slump cone was smoothed. Four minutes after the initial start of the mixer, the mini-slump cone was lifted vertically, and the diameter of the spread mortar (the diameter of the longest part (major axis) and the diameter at a 90-degree angle to the major axis) was measured at two points. The average value was used as the mortar flow value. The values ​​are shown in Tables 2 and 3.

[0136] <Yield point evaluation using a rheometer> (1) Apparatus: Brookfield Rotational Rheometer RST rheometer (2) Overview of the apparatus: Consists of a probe, a sample stage, and a stress detector. The probe is rotated at a constant speed, and the stress applied to the probe can be detected at that time. Yield point detection test probe: Vane Spindle VT-60-30 (3) Evaluation method: The (mixed) mortar sample was transferred to a 1000 mL desk cup, placed on the sample stage, and left to stand for 10 minutes after pouring water. Next, the rotation speed of the probe was increased from 0 rpm to 5 rpm over 30 seconds, and stirring was continued at 5 rpm for another 30 seconds. The maximum stress value in the obtained time vs. stress plot was defined as the yield point. The results are shown in Tables 2 and 3.

[0137] <Evaluation of Autogenous Shrinkage Strain> After measuring the flow value, a sample for a free strain test was prepared, and the autogenous shrinkage strain (free strain) was measured under the following conditions.

[0138] The free strain was measured using a strain gauge (model: PMFL-60T (Tokyo Measuring Instruments Research Co., Ltd.)) and a data logger (model: KMC-70-120-H3 (Kyowa Electronics)).

[0139] Fig. 1 is a schematic diagram showing a method for measuring autogenous shrinkage strain (free strain). The starting point for measuring free strain was immediately after the mortar specimen was packed into the formwork.

[0140] The free strain measurement procedure was as follows: (1) The flow value and air content of the prepared mortar were confirmed to be the specified values. (2) Mortar was filled into a polypropylene container (φ100 × 200 mm) equipped with a strain gauge as shown in Figure 1 in two separate batches, up to approximately 100 mm from the bottom. After each filling, the container was poked 15 times with a steel ram (φ9 × 300 mm), and then lightly tapped around the container with a wooden mallet several times to ensure uniform filling. (3) After filling with mortar, the container was covered with a polyvinylidene chloride sheet and stored at 20 ± 2°C for one day. Strain values ​​were measured at 30-minute intervals. After approximately one day, the mold was removed from the formwork and sealed in an aluminum-coated zip-top bag. Strain values ​​were measured after three days. Because additive manufacturing requires the structure to maintain its shape without collapsing under its own weight due to the layering process, strain measurements were performed after three days.

[0141] (Calculation of free strain amount) The free strain amount was calculated using the strain value at each measurement time and starting point according to the following formula.

[0142] [Free strain amount (x 10 －６ ) = [strain value at each measurement time] - [strain value at starting point] The results are shown in Tables 2 and 3. In the tables, % / C means % relative to cement.

[0143]

[0144]

[0145]

[0146] From the above results, it was found that, for mortar compositions with the same flow value (fluidity), the mortar composition using the additives of the examples had a higher yield point and better lamination properties than the mortar composition without additives or the cement composition using the additives of the comparative examples. It was also found that the free strain was smaller and the autogenous shrinkage suppression effect was higher.

[0147] This application is based on Japanese Patent Application No. 2024-023663, filed on February 20, 2024, the disclosure of which is hereby incorporated by reference in its entirety.

Claims

1. An additive used in a hydraulic composition for additive manufacturing, comprising a crosslinked polymer having 90 mol % or less of structural units derived from ionic monomers.

2. The additive according to claim 1, wherein the crosslinked polymer is obtained by polymerizing a monomer mixture, and the monomer mixture contains 40 mol % or more of a nonionic noncrosslinkable monomer.

3. The additive according to claim 2, wherein the nonionic non-crosslinking monomer comprises a (meth)acrylamide monomer.

4. The additive according to claim 2 or 3, wherein the monomer mixture further contains a nonionic crosslinking monomer.

5. The additive according to claim 4, wherein the content of the nonionic crosslinkable monomer is 10.0 mol % or less based on the monomer mixture.

6. The additive according to claim 4, wherein the nonionic crosslinking monomer comprises a (meth)acrylamide monomer.

7. The additive according to claim 1 or 2, wherein the content of constitutional units derived from the ionic monomer is 50 mol % or less.

8. The additive according to claim 1 or 2, wherein the crosslinked polymer has a water absorption capacity of 35 g / g or less after immersion in an aqueous solution of pH 12.9 at 25°C for 5 minutes.

9. A hydraulic composition for additive manufacturing, comprising the additive according to claim 1 or 2 and a hydraulic material.

10. The hydraulic composition for additive manufacturing according to claim 9, further comprising a hydraulic material dispersant.

11. The hydraulic composition for additive manufacturing according to claim 10, wherein the hydraulic material dispersant is a polycarboxylic acid-based hydraulic material dispersant.

12. A method for producing a hydraulic composition for additive manufacturing, comprising mixing and stirring a hydraulic material and the additive according to claim 1 or 2.

13. A method for producing a layered object, comprising producing a layered object using the composition according to claim 9.

14. Use of a composition comprising a hydraulic material and an additive according to claim 1 or 2 for additive manufacturing.

15. A method for improving layering properties during additive manufacturing of a composition containing a hydraulic material and water, using the additive according to claim 1 or 2.

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