High-strength low-residual-carbon bipropellant binder, preparation method and application

Abstract

This invention relates to the field of additive manufacturing, providing a high-strength, low-carbon-residue bicomponent binder, its preparation method, and its application. The bicomponent binder comprises a first component, a second component, a solvent, and a surfactant: the first component is composed of a low molecular weight polymer with a weight-average molecular weight ranging from 2000 to 20000; the second component is composed of a high molecular weight polymer with a weight-average molecular weight ranging from 50000 to 500000. The low molecular weight polymer provides structural support in the initial stage of printing the preform; the high molecular weight polymer is used to improve the strength of the preform and reduce impurity content during heat treatment. This invention significantly improves the mechanical strength of the preform and reduces impurity residue, especially carbon residue, by optimizing the combination and ratio of low and high molecular weight polymers. The final preform exhibits excellent mechanical strength after drying and has extremely low impurity content, greatly improving the quality and performance of additively manufactured products.

Description

Technical Field

[0001] This invention relates to the field of additive manufacturing, and in particular to a high-strength, low-carbon-residue bicomponent binder, its preparation method, and its application. Background Technology

[0002] Additive manufacturing (AM) technology has received widespread attention and application in recent years, especially in manufacturing fields with high complexity, high precision, and high customization requirements. Among them, binder jetting (BJ), as an important process in additive manufacturing, has gradually become one of the key technologies in industrial production due to its advantages such as high speed, high efficiency, and diverse material selection.

[0003] In binder spray molding, powder materials are bonded layer by layer by spraying liquid binder to form complex three-dimensional structures. Water-based binders are widely used in existing binder spray molding processes due to their environmental friendliness and safety advantages. However, some problems remain to be solved in practical applications: First, preforms prepared using water-based binders often do not achieve sufficient mechanical strength after curing, making them prone to breakage during subsequent processing and use. Second, water-based binders leave behind many impurities during curing, especially carbon residue, which affects the performance and quality of the final product. Therefore, developing a bicomponent binder system that can significantly reduce residual carbon content while providing high mechanical strength has become a pressing technical challenge to improve the overall performance of binder spray molding.

[0004] Traditional adhesive systems primarily rely on single-component polymers, a method that struggles to achieve an ideal balance between mechanical properties and impurity control. Therefore, researchers have begun exploring the use of combinations of multiple polymers, aiming to improve the overall performance of adhesives through the synergistic effects of polymers with different molecular weights and functions.

[0005] Against this backdrop, this invention proposes a bicomponent binder system comprising a combination of low-molecular-weight polymers and high-molecular-weight polymers. By optimizing the ratio and interaction between the two, it aims to significantly reduce the carbon residue in the preform while maintaining high mechanical strength. Furthermore, this invention optimizes the solvent and surfactant in the binder system to further enhance the binder's performance and spray forming effect. Summary of the Invention

[0006] The purpose of this invention is to overcome at least one of the shortcomings of the prior art and to provide a high-strength, low-carbon-residue bicomponent binder, its preparation method, and its application. This invention aims to solve the technical problems of insufficient green body strength and high impurity residue faced by existing water-based binders in binder spray forming processes.

[0007] The present invention adopts the following technical solution:

[0008] On one hand, the present invention provides a high-strength, low-carbon-residue bicomponent binder for binder spraying in additive manufacturing, the bicomponent binder comprising a first component, a second component, a solvent, and a surfactant:

[0009] The first component is composed of a low molecular weight polymer, wherein the weight-average molecular weight of the low molecular weight polymer is in the range of 2000-20000.

[0010] The second component is composed of a high molecular weight polymer, wherein the weight-average molecular weight of the high molecular weight polymer is in the range of 50,000 to 500,000.

[0011] The low molecular weight polymer provides structural support in the initial stage of printing the preform; the high molecular weight polymer is used to improve the strength of the preform and reduce the impurity content during heat treatment; the solvent is used to dissolve the first component and the second component to form a mixed solution; the surfactant stabilizes the mixed solution system and changes the rheological properties of the two-component binder, so that the two-component binder is stably ejected from the nozzle.

[0012] In addition to any of the possible implementations described above, an implementation is further provided in which the low molecular weight polymer comprises one or more combinations of polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP), and polyethyleneimine (PEI).

[0013] In addition to any of the possible implementations described above, another implementation is provided in which the high molecular weight polymer comprises one or a combination of waterborne acrylic resin, waterborne epoxy resin, and waterborne polyurethane.

[0014] In addition to any of the possible implementations described above, another implementation is provided in which the mass ratio of the low molecular weight polymer to the high molecular weight polymer is 5:1 to 1:1.

[0015] In addition to any of the possible implementations described above, another implementation is provided in which the solid content of the waterborne acrylic resin, waterborne epoxy resin, and waterborne polyurethane is 30–70 wt.%. The above-mentioned resins are in emulsion form, and the solid content refers to the polymer content in the emulsion.

[0016] The low molecular weight polymers selected in this invention begin to thermally decompose at relatively low temperatures, which is manifested as the first obvious plateau or mass loss stage on the TGA curve. Furthermore, the low molecular weight polymers help reduce friction between materials during printing. In this stage, the low molecular weight polymers decompose rapidly, forming polymeric channels and releasing volatile products. Due to the high proportion of low molecular weight polymers, they decompose during the drying and curing process, significantly reducing the impurity content of the preform, especially the carbon content.

[0017] The high molecular weight polymers selected in this invention exhibit high thermal stability due to their long-chain structure, typically decomposing at higher temperatures. During the drying and curing process, the polymers do not decompose, and their large molecular weight ensures high strength in the preform. Furthermore, the high molecular weight polymers constitute a low proportion of the binder system, preventing the introduction of excessive impurities.

[0018] By adapting the bicomponent binder to a suitable degreasing process, the low impurity content of the product can be ensured.

[0019] In addition to any of the possible implementations described above, another implementation is provided in which the solvent includes, but is not limited to, one or more combinations of ethylene glycol methyl ether, propylene glycol methyl ether, ethylene glycol, glycerol, and triethylene glycol, and the proportion of the solvent is 60 to 90 wt.% of the bicomponent binder.

[0020] In addition to any of the possible implementations described above, another implementation is provided in which the surfactant includes, but is not limited to, one or more combinations of sodium dodecylbenzenesulfonate, sodium dodecyl sulfate, alkyl glycosyl, and organosilicon surfactants, wherein the proportion of the surfactant is 0.1 to 1.0 wt.% of the bicomponent binder.

[0021] The solvents and surfactants selected in this invention are primarily chosen for their compatibility with the system, and to prevent the formation of precipitates or flocculent matter.

[0022] On the other hand, such as Figure 1 As shown, the present invention also provides a method for preparing the above-mentioned high-strength, low-carbon-residue bicomponent binder, characterized in that the method includes:

[0023] S1. Preparation of the first component solution: Dissolve the low molecular weight polymer in a solvent to obtain the first component solution;

[0024] S2. Preparation of the second component solution: Dissolve the high molecular weight polymer in a solvent to obtain the second component solution;

[0025] S3. Mix the first component solution and the second component solution according to the predetermined mass ratio, and stir evenly to obtain a mixed solution;

[0026] S4. Add a predetermined amount of surfactant to the mixed solution and stir thoroughly to disperse it evenly, thereby obtaining the bicomponent binder.

[0027] In addition to any of the possible implementations described above, another implementation is provided in which, in step S1, the concentration of the first component solution is 5 to 20 wt.%; and in step S2, the concentration of the second component solution is 1% to 20 wt.%.

[0028] On the other hand, the present invention also provides an application of the above-mentioned high-strength, low-carbon-residue bicomponent binder, wherein the bicomponent binder is applied to a binder spray forming preform process, specifically including:

[0029] The bicomponent binder is sprayed onto the substrate using a spray forming process to obtain a preform. The preform is then heated to solidify, resulting in a high-strength, low-carbon preform.

[0030] The preform has a flexural strength >10MPa and a carbon content <0.2wt.% after curing.

[0031] Traditional binders typically produce green bodies with a flexural strength of less than 11 MPa and a residual carbon content of more than 0.8 wt.%, where the residual carbon content is more than 1.5 wt.% when the green body strength is higher than 10 MPa.

[0032] The beneficial effects of this invention are as follows:

[0033] This invention significantly improves the mechanical strength of the preform and reduces residual impurities, especially carbon residue, by optimizing the combination and ratio of low-molecular-weight and high-molecular-weight polymers. The final preform exhibits excellent mechanical strength (flexural strength > 10 MPa) after drying and extremely low impurity content (carbon content < 0.2 wt.%), greatly enhancing the quality and performance of additively manufactured products. Attached Figure Description

[0034] Figure 1 The diagram shown is a schematic flow chart of a method for preparing a high-strength, low-carbon-residue bicomponent binder according to an embodiment of the present invention. Detailed Implementation

[0035] The specific embodiments of the present invention will be described in detail below with reference to specific examples. It should be noted that the technical features or combinations of technical features described in the following embodiments should not be considered in isolation, but can be combined with each other to achieve better technical effects.

[0036] This invention discloses a high-strength, low-carbon-residue bicomponent binder for binder spraying in additive manufacturing. The bicomponent binder comprises a first component, a second component, a solvent, and a surfactant.

[0037] The first component is composed of a low molecular weight polymer, wherein the weight-average molecular weight of the low molecular weight polymer is in the range of 2000-20000.

[0038] The second component is composed of a high molecular weight polymer, wherein the weight-average molecular weight of the high molecular weight polymer is in the range of 50,000 to 500,000.

[0039] The low molecular weight polymer provides structural support in the initial stage of printing the preform; the high molecular weight polymer is used to improve the strength of the preform and reduce the impurity content during heat treatment; the solvent is used to dissolve the first component and the second component to form a mixed solution; the surfactant stabilizes the mixed solution system and changes the rheological properties of the two-component binder, so that the two-component binder is stably ejected from the nozzle.

[0040] In one specific embodiment, the low molecular weight polymer includes one or more combinations of polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP), and polyethyleneimine (PEI).

[0041] In one specific embodiment, the high molecular weight polymer includes one or a combination of waterborne acrylic resin, waterborne epoxy resin, and waterborne polyurethane.

[0042] In one specific embodiment, the mass ratio of the low molecular weight polymer to the high molecular weight polymer is 5:1 to 1:1.

[0043] In one specific embodiment, the solid content in the waterborne acrylic resin, waterborne epoxy resin, and waterborne polyurethane is 30–70 wt.%.

[0044] In one specific embodiment, the solvent includes one or more combinations of ethylene glycol methyl ether, propylene glycol methyl ether, ethylene glycol, glycerol, and triethylene glycol, and the proportion of the solvent is 60-90 wt.% of the bicomponent binder.

[0045] In one specific embodiment, the surfactant is one or more combinations of sodium dodecylbenzenesulfonate, sodium dodecyl sulfate, alkyl glycosyl, and organosilicon surfactants, and the proportion of the surfactant is 0.1 to 1.0 wt.% of the bicomponent binder.

[0046] like Figure 1 As shown, an embodiment of the present invention provides a method for preparing the above-mentioned high-strength, low-carbon-residue bicomponent binder, comprising:

[0047] S1. Preparation of the first component solution: Dissolve the low molecular weight polymer in a solvent to obtain the first component solution;

[0048] S2. Preparation of the second component solution: Dissolve the high molecular weight polymer in a solvent to obtain the second component solution;

[0049] S3. Mix the first component solution and the second component solution according to the predetermined mass ratio, and stir evenly to obtain a mixed solution;

[0050] S4. Add a predetermined amount of surfactant to the mixed solution and stir thoroughly to disperse it evenly, thereby obtaining the bicomponent binder.

[0051] In one specific embodiment, in step S1, the concentration of the first component solution is 5-20 wt.%; in step S2, the concentration of the second component solution is 1%-20 wt.%.

[0052] An embodiment of the present invention describes the application of the above-mentioned high-strength, low-carbon-residue bicomponent binder, wherein the bicomponent binder is applied to a binder spray forming preform process, specifically including:

[0053] The bicomponent binder is sprayed onto the substrate using a spray forming process to obtain a preform. The preform is then heated to solidify, resulting in a high-strength, low-carbon preform.

[0054] The preform has a flexural strength >10MPa and a carbon content <0.2wt.% after curing.

[0055] Example 1

[0056] The specific process for preparing the preform using the high-strength, low-carbon-residue bicomponent binder of this invention is as follows:

[0057] (1) Material preparation:

[0058] Low molecular weight polymer: Polyvinyl alcohol (PVA), with a weight average molecular weight of 1000;

[0059] High molecular weight polymer: water-based acrylic resin with a weight average molecular weight of 150,000;

[0060] Solvent: A mixture of ethylene glycol methyl ether and propylene glycol methyl ether in a 1:1 ratio;

[0061] Surfactant: Sodium dodecylbenzenesulfonate;

[0062] (2) Preparation of the first component solution

[0063] PVA was dissolved in a mixed solvent of ethylene glycol methyl ether and propylene glycol methyl ether to obtain a first component solution with a concentration of 10 wt.%.

[0064] (3) Preparation of the second component solution

[0065] Aqueous acrylic resin was dissolved in a mixed solvent of ethylene glycol methyl ether and propylene glycol methyl ether to obtain a second component solution with a concentration of 5 wt.%.

[0066] (4) Prepare bicomponent adhesive

[0067] The first component solution and the second component solution were mixed at a mass ratio of 2:1 and stirred evenly to form a bicomponent binder.

[0068] (5) Add surfactant

[0069] Add 0.5 wt.% sodium dodecylbenzenesulfonate to the bicomponent binder and stir thoroughly to ensure uniform dispersion in the binder;

[0070] (6) Spray forming

[0071] The prepared bicomponent binder was loaded into a binder jet printer and sprayed through a nozzle onto a pre-laid stainless steel 316L powder substrate. During the spraying process, the movement path of the nozzle and the spraying frequency were controlled to ensure that the binder was evenly distributed on the powder bed.

[0072] (7) Heat curing

[0073] Move the powder bed into an oven set to 180℃ and set the curing time to 120 minutes;

[0074] (8) Billet performance testing

[0075] The flexural strength and carbon content of the cured green body were tested. The test results showed that the flexural strength of the green body was 12 MPa and the carbon content was 0.10 wt.%, which met the design objectives of this invention.

[0076] Example 2

[0077] The specific process for preparing the preform using the high-strength, low-carbon-residue bicomponent binder of this invention is as follows:

[0078] (1) Material preparation

[0079] Low molecular weight polymer: polyvinylpyrrolidone (PVP), with a weight average molecular weight of 15,000;

[0080] High molecular weight polymer: waterborne epoxy resin with a weight-average molecular weight of 200,000;

[0081] Solvent: A mixture of glycerol and ethylene glycol in a 1:1 ratio;

[0082] Surfactant: Sodium dodecyl sulfate;

[0083] (2) Preparation of the first component solution

[0084] Aqueous epoxy resin was dissolved in a mixed solvent of glycerol and ethylene glycol to obtain a second component solution with a concentration of 5 wt.%.

[0085] (3) Preparation of the second component solution

[0086] Aqueous acrylic resin was dissolved in a mixed solvent of ethylene glycol methyl ether and propylene glycol methyl ether to obtain a second component solution with a concentration of 5 wt.%.

[0087] (4) Prepare bicomponent adhesive

[0088] The first component solution and the second component solution were mixed at a mass ratio of 3:1 and stirred evenly to form a multi-component binder.

[0089] (5) Add surfactant

[0090] Add 0.3 wt.% sodium dodecyl sulfate to the bicomponent binder and stir thoroughly to ensure uniform dispersion in the binder;

[0091] (6) Spray forming

[0092] The prepared multi-component binder is loaded into an binder jet printer and sprayed through a nozzle onto a pre-laid 17-4PH powder substrate. During the spraying process, the movement path of the nozzle and the spraying frequency are controlled to ensure that the binder is evenly distributed on the powder bed.

[0093] (7) Heat curing

[0094] Move the powder bed into an oven set to 200℃ and set the curing time to 120 minutes;

[0095] (8) Billet performance testing

[0096] The flexural strength and carbon content of the cured green body were tested. The test results showed that the flexural strength of the green body was 15 MPa and the carbon content was 0.17 wt.%, which met the design objectives of this invention.

[0097] Example 3

[0098] The specific process for preparing the preform using the high-strength, low-carbon-residue bicomponent binder of this invention is as follows:

[0099] (1) Material preparation

[0100] Low molecular weight polymer: polyethyleneimine (PEI), with a weight average molecular weight of 8000;

[0101] High molecular weight polymer: waterborne polyurethane, with a weight-average molecular weight of 250,000;

[0102] Solvent: A mixture of propylene glycol methyl ether and triethylene glycol in a ratio of 2:1;

[0103] Surfactant: Alkyl glycoside;

[0104] (2) Preparation of the first component solution

[0105] PEI was dissolved in a mixed solvent of propylene glycol methyl ether and triethylene glycol to obtain a first component solution with a concentration of 12 wt.%.

[0106] (3) Preparation of the second component solution

[0107] Aqueous polyurethane was dissolved in a mixed solvent of propylene glycol methyl ether and triethylene glycol to obtain a second component solution with a concentration of 8 wt.%.

[0108] (4) Prepare bicomponent adhesive

[0109] The first component solution and the second component solution are mixed at a mass ratio of 1:1 and stirred evenly to form a multi-component binder.

[0110] (5) Add surfactant

[0111] Add 0.2 wt.% alkyl glycosyl to the multi-component binder and stir thoroughly to ensure uniform dispersion in the binder;

[0112] (6) Spray forming

[0113] The prepared multi-component binder is loaded into an binder jet printer and sprayed onto a pre-laid H13 powder substrate through a nozzle. During the spraying process, the movement path of the nozzle and the spraying frequency are controlled to ensure that the binder is evenly distributed on the powder bed.

[0114] (7) Heat curing

[0115] Move the powder bed into an oven set to 180℃ and set the curing time to 150 minutes;

[0116] (8) Billet performance testing

[0117] The flexural strength and carbon content of the cured green body were tested. The test results showed that the flexural strength of the green body was 13 MPa and the carbon content was 0.08 wt.%, which met the design objectives of this invention.

[0118] Through the specific operation and test results of the above three embodiments, it can be seen that the bicomponent binder of the present invention can achieve the performance goals of high mechanical strength and low impurity residue under different conditions, and has broad application prospects.

[0119] While several embodiments of the present invention have been provided herein, those skilled in the art should understand that modifications can be made to these embodiments without departing from the spirit of the invention. The above embodiments are merely exemplary and should not be construed as limiting the scope of the invention.

Claims

1. A high-strength, low-carbon-residue bicomponent binder for binder spraying in additive manufacturing, characterized in that, The bicomponent binder comprises a first component, a second component, a solvent, and a surfactant: The first component is composed of a low molecular weight polymer, wherein the weight average molecular weight of the low molecular weight polymer is in the range of 2000-20000, and is selected from one or more of polyvinyl alcohol, polyvinylpyrrolidone and polyethyleneimine. The second component is composed of a high molecular weight polymer, wherein the weight average molecular weight of the high molecular weight polymer is in the range of 50,000-500,000, and is selected from one or more of waterborne acrylic resin, waterborne epoxy resin and waterborne polyurethane. The low molecular weight polymer is used to provide structural support in the early stage of printing the preform and decomposes at a lower temperature in subsequent heat treatment; the high molecular weight polymer is used to improve the strength of the preform and reduce the impurity content during heat treatment. The mass ratio of the low molecular weight polymer to the high molecular weight polymer is 5:1 to 1:1; The solvent is selected from one or more of ethylene glycol methyl ether, propylene glycol methyl ether, ethylene glycol, glycerol, and triethylene glycol, and its amount is 60 wt.% to 90 wt.% of the total mass of the bicomponent binder. The surfactant is selected from one or more of sodium dodecylbenzenesulfonate, sodium dodecyl sulfate, alkyl glycosyl and organosilicon surfactants, and its amount is 0.1 wt.% to 1.0 wt.% of the total mass of the bicomponent binder.

2. The bicomponent adhesive according to claim 1, characterized in that, The solid content of the waterborne acrylic resin, waterborne epoxy resin and waterborne polyurethane is from 30 wt.% to 70 wt.%.

3. A method for preparing a high-strength, low-carbon-residue bicomponent binder as described in claim 1 or 2, characterized in that, The method includes: S1. Preparation of the first component solution: Dissolve the low molecular weight polymer in a portion of the solvent to obtain a first component solution with a concentration of 5 wt.% to 20 wt.%. S2. Preparation of the second component solution: Dissolve or disperse the high molecular weight polymer in a portion of the solvent to obtain a second component solution with a concentration of 1 wt.% to 20 wt.%. S3. Mixing: Mix the first component solution and the second component solution according to the mass ratio, and stir evenly to obtain a mixed solution; S4. Add surfactant: Add the surfactant to the mixed solution and stir thoroughly to disperse it evenly to obtain the bicomponent binder.

4. The application of a high-strength, low-carbon-residue bicomponent binder as described in claim 1 or 2 in a binder spray molding process, characterized in that, The applications include: The bicomponent binder is sprayed onto a powder substrate using a spray forming process to obtain a green body; The green body is cured by heating; The cured green body has a flexural strength greater than 10 MPa and a carbon content less than 0.2 wt.%.

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