Inorganic binder for sand mold 3D printing and method for preparing the same

Abstract

The application discloses an inorganic binder for sand mold 3D printing and a preparation method thereof, belongs to the field of casting, and is a phosphate-based liquid inorganic binder for 3D printing, which comprises the following raw materials in mass fractions: 40-70 parts of aluminum dihydrogen phosphate, 5-20 parts of silica sol, 2-10 parts of dimethyl silicone oil, 0.1-3 parts of a surfactant, 5-30 parts of liquid silicone, and 0.1-2 parts of silane coupling agent HD-560. The inorganic binder can meet the use requirements of producing 3D printing inorganic binder sand cores by adopting an infrared heating hardening mode. The 3D printing inorganic binder has the characteristics of low viscosity, high purity, high strength and high collapsibility.

Description

Technical Field

[0001] This invention belongs to the field of casting and provides an inorganic binder used in the 3D printing process of casting sand mold cores and its preparation method. Background Technology

[0002] 3D printing (Three Dimensional Printing, 3DP) is essentially a rapid prototyping technology that uses printing equipment to create physical models by layering powder materials. Unlike traditional manufacturing processes that remove material, 3D printing follows an additive principle, meaning that the physical object is created by stacking layers of powder, hence it is also called "additive manufacturing" technology.

[0003] Currently, the most widely used and efficient additive manufacturing technology in the casting field is sand mold inkjet 3D printing. Inkjet 3D printing technology has stringent requirements for binder materials. It must ensure the physicochemical properties of inorganic binders, such as flowability, viscosity, surface tension, and purity, while also requiring inorganic binders to have high strength, good resistance to wet molding, and good collapsibility, which are important casting process properties. Therefore, the development of inorganic binders for sand mold 3D printing has posed a huge challenge. Summary of the Invention

[0004] This invention addresses the characteristics of inorganic binders and the requirements for using sand cores in 3D printing sand molds, proposing an inorganic binder for 3D sand printing and its preparation method, thus developing an inorganic binder that can replace current organic binders. The 3D printing inorganic binder of this invention features low viscosity, high purity, high strength, and high collapsibility, meeting the technical requirements of 3D printing and enabling the 3D printing of sand molds and complex sand cores.

[0005] The technical solution of this invention is as follows:

[0006] An inorganic binder for sand mold 3D printing, characterized in that: the inorganic binder is a phosphate-based liquid inorganic binder for 3D printing, comprising the following raw materials in parts by weight: 40-70 parts aluminum dihydrogen phosphate, 5-20 parts silica sol, 2-10 parts dimethyl silicone oil, 0.1-3 parts surfactant, 5-30 parts liquid silica gel, and 0.1-2 parts silane coupling agent HD-560.

[0007] As a preferred technical solution:

[0008] The phosphate used in this invention is aluminum dihydrogen phosphate, wherein the density of aluminum dihydrogen phosphate is 1.2-1.4 g / cm³. 3 The preferred concentration is 1.3-1.42 g / cm³. 3 The density of silica sol is 1.1-1.3 g / cm³. 3 The preferred concentration is 1.15-1.2 g / cm³. 3The viscosity of the dimethyl silicone oil is 500-1000 mPa·S, preferably 600-700 mPa·S.

[0009] The surfactant is one or more of alkyl glucoside, fatty acid glycerides, fatty acid sorbitan, polysorbate, sodium dioctyl succinate sulfonate, sodium dodecylbenzene sulfonate, sodium glycocholate, and alkyl phosphocarboxylate, used to reduce the viscosity of the inorganic binder.

[0010] The viscosity of the inorganic binder is ≤30 mPa·S.

[0011] This invention adds modified liquid silica gel to inorganic binders, which greatly reduces the viscosity of inorganic binders and improves the strength of inorganic binder sand. The amount of inorganic binder added is reduced to below 2.0% (far lower than the existing amount of 2.5%), fundamentally solving the technical problems of low bonding strength, slow hardening speed and poor collapsibility of water glass-based inorganic binder molding sand.

[0012] The present invention also provides a method for preparing the inorganic binder for sand mold 3D printing, characterized in that: liquid silica gel is added to a three-hole bottle, dimethyl silicone oil is added to dilute it to a viscosity of 25 mPa·s to 40 mPa·s, and then a surfactant is added. After stirring evenly, aluminum dihydrogen phosphate is added, heated to 80℃ to 110℃, kept at that temperature for 2 hours, cooled to below 30℃, and then silane coupling agent HD-560 is added. After stirring for 60 minutes, the inorganic binder is obtained.

[0013] The inorganic binder described in this invention can be used for 3D printing sand molds. The specific application method is as follows: during the preparation of 3D printing sand cores, sand is laid on the printing platform using a sand spreader, and the nozzle is controlled to spray the inorganic binder at the required position. Then, the inorganic binder is cured by infrared heating. The inorganic sand core is prepared by printing layer by layer. After cleaning the loose sand, it can be used directly. Alternatively, the sand core can be heated in an oven or cured by microwave for a second time to increase the strength of the inorganic sand core before use.

[0014] Table 1 compares the performance parameters of the inorganic binder for 3D printing of this invention with those of 3D furan resin sand. The silica sand is 50 / 100 mesh Dalin standard sand. The molding sand strength in the table was measured according to the method required by GB / T 2684-2009 standard.

[0015] Table 1 Comparison of molding sand performance parameters

[0016]

[0017] Note: The residual strength of a cylindrical specimen with a diameter of 50 mm is the compressive strength value.

[0018] The 3D printing inorganic binder provided by this invention has excellent casting process performance, especially with a gas evolution rate that is significantly lower than that of furan resin sand, which helps to reduce the emission of toxic and harmful gases and has obvious environmental advantages. It is suitable for 3D printing sand mold manufacturing. Detailed Implementation

[0019] Unless otherwise specified, all percentages mentioned in this invention are mass percentages.

[0020] Example 1

[0021] Phosphate-based liquid inorganic binder for 3D printing comprises the following raw materials in parts by weight: 40 parts aluminum dihydrogen phosphate, 5 parts silica sol, 10 parts dimethyl silicone oil, 0.1 parts surfactant (50% fatty acid glycerides, 50% fatty acid sorbitan), 5 parts liquid silica gel, and 0.1 parts silane coupling agent HD-560.

[0022] A certain amount of liquid silica gel was added to a three-hole bottle and diluted with dimethyl silicone oil to achieve a viscosity of 30 mPa / s. A surfactant was then added. After stirring evenly, a certain amount of aluminum dihydrogen phosphate was added and heated to 90°C. The mixture was kept at this temperature for 2 hours, then cooled to below 30°C. A certain amount of silane coupling agent HD-560 was then added and stirred for 60 minutes to obtain the inorganic binder.

[0023] Example 2

[0024] Phosphate-based liquid inorganic binder for 3D printing comprises the following raw materials in parts by weight: 70 parts aluminum dihydrogen phosphate, 20 parts silica sol, 2 parts dimethyl silicone oil, 3 parts surfactant (20% sodium dioctyl succinate, 40% sodium dodecylbenzene sulfonate, 40% sodium cholate), 30 parts liquid silica gel, and 2 parts silane coupling agent HD-560.

[0025] A certain amount of liquid silica gel was added to a three-hole bottle and diluted with dimethyl silicone oil to achieve a viscosity of 30 mPa / s. A surfactant was then added. After stirring evenly, a certain amount of aluminum dihydrogen phosphate was added and heated to 90°C. The mixture was kept at this temperature for 2 hours, then cooled to below 30°C. A certain amount of silane coupling agent HD-560 was then added and stirred for 60 minutes to obtain the inorganic binder.

[0026] Example 3

[0027] Phosphate-based liquid inorganic binder for 3D printing comprises the following raw materials in parts by weight: 50 parts aluminum dihydrogen phosphate, 10 parts silica sol, 5 parts dimethyl silicone oil, 2 parts surfactant (30% alkyl glucoside, 30% fatty acid glycerides, 40% fatty acid sorbitan), 20 parts liquid silica gel, and 1 part silane coupling agent HD-560.

[0028] A certain amount of liquid silica gel was added to a three-hole bottle and diluted with dimethyl silicone oil to achieve a viscosity of 30 mPa / s. A surfactant was then added. After stirring evenly, a certain amount of aluminum dihydrogen phosphate was added and heated to 90°C. The mixture was kept at this temperature for 2 hours, then cooled to below 30°C. A certain amount of silane coupling agent HD-560 was then added and stirred for 60 minutes to obtain the inorganic binder.

[0029] Example 4

[0030] Phosphate-based liquid inorganic binder for 3D printing comprises the following raw materials in parts by weight: 60 parts aluminum dihydrogen phosphate, 15 parts silica sol, 8 parts dimethyl silicone oil, 1.5 parts surfactant (40% fatty acid glycerides, 60% sodium dodecylbenzene sulfonate), 18 parts liquid silica gel, and 1.5 parts silane coupling agent HD-560.

[0031] A certain amount of liquid silica gel was added to a three-hole bottle and diluted with dimethyl silicone oil to achieve a viscosity of 30 mPa / s. A surfactant was then added. After stirring evenly, a certain amount of aluminum dihydrogen phosphate was added and heated to 90°C. The mixture was kept at this temperature for 2 hours, then cooled to below 30°C. A certain amount of silane coupling agent HD-560 was then added and stirred for 60 minutes to obtain the inorganic binder.

[0032] Comparative Example 1

[0033] Phosphate-based liquid inorganic binder for 3D printing comprises the following raw materials in parts by weight: 30 parts aluminum dihydrogen phosphate, 18 parts silica sol, 8 parts dimethyl silicone oil, 0.8 parts surfactant (10% alkyl glucoside, 60% sodium sulfonate, 30% sodium cholate), 25 parts liquid silica gel, and 0.2 parts silane coupling agent HD-560.

[0034] A certain amount of liquid silica gel was added to a three-hole bottle and diluted with dimethyl silicone oil to achieve a viscosity of 30 mPa / s. A surfactant was then added. After stirring evenly, a certain amount of aluminum dihydrogen phosphate was added and heated to 90°C. The mixture was kept at this temperature for 2 hours, then cooled to below 30°C. A certain amount of silane coupling agent HD-560 was then added and stirred for 60 minutes to obtain the inorganic binder.

[0035] Comparative Example 2

[0036] Phosphate-based liquid inorganic binder for 3D printing comprises the following raw materials in parts by weight: 50 parts aluminum dihydrogen phosphate, 25 parts silica sol, 8 parts dimethyl silicone oil, 0.8 parts surfactant (10% alkyl glucoside, 60% sodium sulfonate, 30% sodium cholate), 25 parts liquid silica gel, and 0.2 parts silane coupling agent HD-560.

[0037] A certain amount of liquid silica gel was added to a three-hole bottle and diluted with dimethyl silicone oil to achieve a viscosity of 30 mPa / s. A surfactant was then added. After stirring evenly, a certain amount of aluminum dihydrogen phosphate was added and heated to 90°C. The mixture was kept at this temperature for 2 hours, then cooled to below 30°C. A certain amount of silane coupling agent HD-560 was then added and stirred for 60 minutes to obtain the inorganic binder.

[0038] Comparative Example 3

[0039] Phosphate-based liquid inorganic binder for 3D printing comprises the following raw materials in parts by weight: 50 parts aluminum dihydrogen phosphate, 25 parts silica sol, 8 parts dimethyl silicone oil, 0.8 parts surfactant (10% alkyl glucoside, 60% sodium sulfonate, 30% sodium cholate), 40 parts liquid silica gel, and 0.2 parts silane coupling agent HD-560.

[0040] A certain amount of liquid silica gel was added to a three-hole bottle and diluted with dimethyl silicone oil to achieve a viscosity of 30 mPa / s. A surfactant was then added. After stirring evenly, a certain amount of aluminum dihydrogen phosphate was added and heated to 90°C. The mixture was kept at this temperature for 2 hours, then cooled to below 30°C. A certain amount of silane coupling agent HD-560 was then added and stirred for 60 minutes to obtain the inorganic binder.

[0041] The inorganic binder prepared in the examples was used to conduct sand mixing tests. 100 parts of Dalin standard sand were taken, 2 parts of inorganic binder were added, and the mixture was stirred for 1 min. 1 part of powder accelerator was added, and the mixture was stirred for 1 min. The resulting “8”-shaped sample was then prepared and hardened by infrared heating. The performance parameters are shown in the table below:

[0042] Table 2 Sample performance parameters

[0043]

[0044] Matters not covered in this invention are common knowledge.

[0045] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. An inorganic binder for sand mold 3D printing, characterized in that: The inorganic binder is a phosphate-based liquid inorganic binder for 3D printing, comprising the following raw materials in parts by weight: 40-70 parts aluminum dihydrogen phosphate, 5-20 parts silica sol, 2-10 parts dimethyl silicone oil, 0.1-3 parts surfactant, 5-30 parts liquid silica gel, and 0.1-2 parts silane coupling agent HD-560.

2. The inorganic binder for sand mold 3D printing according to claim 1, characterized in that: The density of the aluminum dihydrogen phosphate is 1.2-1.4 g / cm³. 3 The density of silica sol is 1.1-1.3 g / cm³. 3 The viscosity of dimethyl silicone oil is 500-1000 mPa·S.

3. The inorganic binder for sand mold 3D printing according to claim 1 or 2, characterized in that: Aluminum dihydrogen phosphate has a density of 1.3 g / cm³. 3 The density of silica sol is 1.15-1.2 g / cm³. 3 The viscosity of dimethyl silicone oil is 600-700 mPa·S.

4. The inorganic binder for sand mold 3D printing according to claim 1, characterized in that: The surfactant is one or more of alkyl glucoside, fatty acid glyceride, fatty acid sorbitan, polysorbate, sodium dioctyl succinate sulfonate, sodium dodecylbenzene sulfonate, sodium glycocholate, and alkyl phosphocarboxylate, used to reduce the viscosity of inorganic binders.

5. The inorganic binder for sand mold 3D printing according to claim 1, characterized in that: The viscosity of the inorganic binder is ≤30 mPa·S.

6. A method for preparing an inorganic binder for sand mold 3D printing according to any one of claims 1 to 5, characterized in that: Liquid silica gel is added to a three-hole bottle, and dimethyl silicone oil is added to dilute it to a viscosity of 25 mPa·s to 40 mPa·s. Then, a surfactant is added, and after stirring evenly, aluminum dihydrogen phosphate is added. The mixture is heated to 80℃ to 110℃ and kept at that temperature for 2 hours. After cooling to below 30℃, silane coupling agent HD-560 is added, and the mixture is stirred for 60 minutes to obtain the inorganic binder.

7. The application of the inorganic binder according to any one of claims 1 to 5, characterized in that: The inorganic binder is used for 3D printing sand molds.

8. The application of the inorganic binder according to claim 7, characterized in that, The specific application method is as follows: In the process of 3D printing sand core preparation, sand is laid on the printing platform through a sand spreader, and inorganic binder is sprayed at the required position by controlling the nozzle. Then, the inorganic binder is cured by infrared heating. The inorganic sand core is prepared by printing layer by layer. After cleaning the loose sand, it can be used directly. Alternatively, the sand core can be heated in an oven or microwaved for secondary curing to increase the strength of the inorganic sand core before use.

Images