US-20260125323-A1 - HYDRAULIC COMPOSITION

Abstract

In a hydraulic composition for additive manufacturing which includes (A) at least one water-soluble hydroxyalkyl alkyl cellulose selected from hydroxypropyl methyl cellulose and hydroxyethyl methyl cellulose, (B) a defoamer, (C) cement, (D) water and (E) diutan gum, the water-soluble hydroxyalkyl alkyl cellulose has an alkoxy group degree of substitution of from 1.6 to 2.0 and a 2 wt % aqueous-solution viscosity at 20° C. of from 50 to 1,000 mPa·s and the water is added in an amount of from 25 to 70 parts by weight per 100 parts by weight of the cement. The composition has a good extrudability from a nozzle and a good self-supportability following deposition.

Inventors

• Hidekazu Konishi

Assignees

• SHIN-ETSU CHEMICAL CO., LTD.

Dates

Publication Date

20260507

Application Date

20251229

Priority Date

20220406

Claims (7)

1. 1 . A hydraulic composition comprising (A) at least one water-soluble hydroxyalkyl alkyl cellulose selected from the group consisting of hydroxypropyl methyl cellulose and hydroxyethyl methyl cellulose, (B) a defoamer, (C) cement, (D) water and (E) diutan gum, wherein the water-soluble hydroxyalkyl alkyl cellulose has an alkoxy group degree of substitution (DS) of from 1.6 to 2.0 and a 2 wt % aqueous-solution viscosity at 20° C. of from 50 to 1,000 mPa·s, the diutan gum is added in an amount of from 0.01 to 0.3 part by weight per 100 parts by weight of the cement, and the water is added in an amount of from 25 to 70 parts by weight per 100 parts by weight of the cement.
2. 2 . The hydraulic composition of claim 1 , wherein the water-soluble hydroxyalkyl alkyl cellulose is added in an amount of from 0.1 to 0.6 part by weight per 100 parts by weight of the cement.
3. 3 . The hydraulic composition of claim 1 , wherein the diutan gum is added in an amount of from 0.1 to 0.2 part by weight per 100 parts by weight of the cement.
4. 4 . The hydraulic composition of claim 1 , wherein the water-soluble hydroxyalkyl alkyl cellulose is hydroxypropyl methyl cellulose which has a thermal gelation temperature of between 55° C. and 65° C.
5. 5 . The hydraulic composition of claim 1 , wherein the water-soluble hydroxyalkyl alkyl cellulose is hydroxyethyl methyl cellulose which has a thermal gelation temperature of between 68° C. and 83° C.
6. 6 . The hydraulic composition of claim 1 which does not include a water-reducing agent.
7. 7 . The hydraulic composition of claim 1 , further comprising a water-reducing agent that is added in an amount of from 0.1 to 5 part by weight per 100 parts by weight of the cement.

Description

CROSS-REFERENCE TO RELATED APPLICATION This application is a Divisional of copending application Ser. No. 18/125,368, filed on Mar. 23, 2023, which claims priority under 35 U.S.C. § 119(a) on Patent Application No. 2022-063346 filed in Japan on Apr. 6, 2022, the entire contents of which are hereby incorporated by reference. TECHNICAL FIELD The present invention relates to a hydraulic composition suitable for additive manufacturing by 3D printing. BACKGROUND ART 3D printing refers to processes that form a three-dimensional object by successively building up layers of a material as sectional shapes based on three-dimensional data (additive manufacturing). Major 3D printing processes are broadly divided into four types: binder jetting (in which a liquid binder is jetted onto a powder bed and selectively solidified), directed energy deposition (the position of heat generation is controlled so as to selectively melt and bond a material), material jetting (liquid droplets of a material are jetted and selectively deposited and cured), and material extrusion (a material having flow properties is extruded from a nozzle and solidified). In cases where a cementitious material is used in 3D printing, of these processes, material extrusion is especially suitable. The properties desired of the material in such cases are ease of extrusion from a nozzle and self-supportability following deposition. Because these are basically incompatible properties, it has been difficult to confer the material with both properties at the same time. To resolve this problem, JP-A 2020-105023 attempts to provide both extrudability and self-supportability following deposition by setting a specific relationship between the content of a cellulose-based thickener and the content of silica fume. However, although JP-A 2020-105023 specifies the 1 wt % aqueous-solution viscosity of the cellulose-based thickener for each shear rate, because silica fume-containing hydraulic compositions are very thixotropic, the properties of the cellulose-based thickener do not fully come into play, leading to a poor dischargeability and other undesirable effects. SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a hydraulic composition which is suitable for 3D printing by a material extrusion process and which has a good extrudability from a nozzle and also has a good self-supportability following deposition. As a result of intensive investigations, I have discovered that by using a water-soluble hydroxyalkyl alkyl cellulose having a specific degree of substitution (DS) and a specific aqueous-solution viscosity, a defoamer, cement, water and diutan gum to prepare a hydraulic composition, the pressure when the resulting composition is extruded from a nozzle is low and the composition has a good self-supportability following deposition. Accordingly, the invention provides a hydraulic composition which includes (A) at least one water-soluble hydroxyalkyl alkyl cellulose selected from the group consisting of hydroxypropyl methyl cellulose and hydroxyethyl methyl cellulose, (B) a defoamer, (C) cement, (D) water and (E) diutan gum, wherein the water-soluble hydroxyalkyl alkyl cellulose has an alkoxy group degree of substitution (DS) of from 1.6 to 2.0 and a 2 wt % aqueous-solution viscosity at 20° C. of from 50 to 1,000 mPa·s, andthe water is added in an amount of from 25 to 70 parts by weight per 100 parts by weight of the cement. In a preferred embodiment of the hydraulic composition of the invention, the water-soluble hydroxyalkyl alkyl cellulose is added in an amount of from 0.1 to 0.6 part by weight per 100 parts by weight of the cement. In another preferred embodiment of the invention, the diutan gum is added in an amount of from 0.01 to 0.3 part by weight per 100 parts by weight of the cement. In yet another preferred embodiment, the water-soluble hydroxyalkyl alkyl cellulose is hydroxypropyl methyl cellulose which has a thermal gelation temperature of between 55° C. and 65° C. In still another preferred embodiment, the water-soluble hydroxyalkyl alkyl cellulose is hydroxyethyl methyl cellulose which has a thermal gelation temperature of between 68° C. and 83° C. In a further preferred embodiment, the hydraulic composition is adapted for use in additive manufacturing. ADVANTAGEOUS EFFECTS OF THE INVENTION This invention makes it possible to provide hydraulic compositions which are cementitious materials suitable for 3D printing by material extrusion and which have good extrudability from a nozzle and good self-supportability following deposition. DESCRIPTION OF THE PREFERRED EMBODIMENTS The hydraulic composition according to the present invention is described in detail below. The hydraulic composition of the invention, which includes (A) at least one water-soluble hydroxyalkyl alkyl cellulose selected from the group consisting of hydroxypropyl methyl cellulose and hydroxyethyl methyl cellulose, (B) a defoamer, (C) cement, (D) w