Aqueous binder solutions for use in additive manufacturing processes

Abstract

To provide a binder solution for shortening penetration time and allowed to check a printer head with a thermosensitive paper.SOLUTION: A water-based binder solution for use in additive manufacturing contains a thermoplastic binder, a non-aqueous solvent of 4 weight% or higher and 20 weight% or lower (having a boiling point of 100°C or higher and 175°C or lower), and water. The thermoplastic binder contains at least one of a first polymer chain having a weight-average molecular weight (Mw) of 5,000-15,000 g / mol, a second polymer chain having a weight-average molecular weight (Mw) of 10,000-50,000 g / mol and a third polymer chain having a weight-average molecular weight (Mw) of 1,000-5,000 g / mol. A method of monitoring a print head in an additive manufacturing process includes applying a water-based binder solution onto a thermosensitive paper.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present disclosure relates to additive manufacturing, and more particularly, to binders used in additive manufacturing processes. [Background technology]

[0002] Additive manufacturing, also known as 3D printing, is a process in which material is deposited layer by layer to form three-dimensional parts. Binder jetting is an additive manufacturing technique based on using a binder to bind powder particles together to form a three-dimensional part. In particular, the binder is jetted from a print head onto successive layers of powder in a build volume, where the powder layers and the binder adhere to each other to form a green body part. In some applications, the green body part is suitable for the end use. In other applications, subsequent processing, such as removal of the binder and sintering of the powder, may be required to convert the green body part into a finished three-dimensional part. Summary of the Invention

[0003] Conventional binder solutions may require a relatively long time to wick into a layer of powder, which can increase the time required before a subsequent layer of powder can be deposited into the build volume. Longer wicking times reduce the throughput of the additive manufacturing device, which in turn reduces productivity. However, some binder solutions that achieve improved wicking times may not form a pattern on the thermal paper during the printhead check.

[0004] Therefore, there is a need for an alternative binder solution that reduces penetration time and allows for printhead checking with thermal paper.

[0005] Various embodiments disclosed herein meet these needs by providing an aqueous binder solution including a thermoplastic binder, a non-aqueous solvent having a boiling point of 100° C. to 175° C., inclusive, in an amount of 4% to 20% by weight, and water. The thermoplastic binder includes a first polymer strand and at least one of a second polymer strand and a third polymer strand. In various embodiments, the first polymer strand has a weight average molecular weight (Mw) of 5,000 g / mol to 15,000 g / mol, the second polymer strand has a weight average molecular weight of 10,000 g / mol to 50,000 g / mol, and the third polymer strand has a weight average molecular weight of 1,000 g / mol to 5,000 g / mol. The first polymer strand is different from each of the second polymer strand and the third polymer strand, and the second polymer strand is different from the third polymer strand. The formulation also has a balance of fast penetration into the powder layer while providing a short cure time compared to conventional binder solutions and the ability to pattern thermal paper during printhead checks. Additional features and advantages are described in more detail below.

[0006] According to a first aspect A1, an aqueous binder solution for use in additive manufacturing includes a first polymer chain having a weight average molecular weight (Mw) of from 5,000 g / mol to 15,000 g / mol, at least one of a second polymer chain having a weight average molecular weight (Mw) of from 10,000 g / mol to 50,000 g / mol and a third polymer chain having a weight average molecular weight (Mw) of from 1,000 g / mol to 5,000 g / mol (wherein the first polymer chain is different from each of the second polymer chain and the third polymer chain, and the second polymer chain is different from the third polymer chain), a non-aqueous solvent (having a boiling point of from 100° C. to 175° C.) in an amount of from 4 weight percent (wt%) to 20 wt%, based on a total weight of the non-aqueous binder solution, and water.

[0007] A second aspect A2 includes the aqueous binder solution according to the first aspect A1, wherein the non-aqueous solvent is present in the aqueous binder solution in an amount of 6% by weight or more and less than 18% by weight, based on the total weight of the aqueous binder solution.

[0008] A third aspect A3 includes the aqueous binder solution according to the first aspect A1, wherein the non-aqueous solvent includes at least one of 2-methoxyethanol, butanol, 2-butanol, tert-butanol, 1-methoxy-2-propanol, 2-butoxyethanol, isoamyl alcohol, isobutyl alcohol, 2-butoxyethanol, and di(propylene glycol) dimethyl ether.

[0009] A fourth aspect A4 includes the aqueous binder solution according to the first aspect A1, wherein the first polymer chain includes at least one of polyvinylpyrrolidone (PVP) and polyvinyl alcohol (PVA).

[0010] A fifth aspect A5 comprises the aqueous binder solution according to the fourth aspect A4, wherein the first polymer chains are present in an amount of 5% to 20% by weight, based on the total weight of the aqueous binder solution.

[0011] A sixth aspect A6 includes the aqueous binder solution according to the first aspect A1, wherein the thermoplastic binder includes the second polymer chains in an amount of 0.5% to 7% by weight, based on the total weight of the aqueous binder solution.

[0012] A seventh aspect A7 includes the aqueous binder solution according to the sixth aspect A6, wherein the thermoplastic binder includes the third polymer chain in an amount of 0.1% by weight or more and 5% by weight or less, based on the total weight of the aqueous binder solution.

[0013] An eighth aspect A8 includes the aqueous binder solution according to the first aspect A1, wherein the second polymer chain includes at least one of polyvinyl alcohol (PVA), polyacrylamide (PAAm), polyvinyl methyl ether maleic anhydride (PVME-MA), and derivatives thereof.

[0014] A ninth aspect A9 includes the aqueous binder solution according to the first aspect A1, wherein the third polymer chain includes at least one of polyacrylic acid (PAA), polymethyl methacrylate (PMMA), polyacrylamide (PAAm), and derivatives thereof.

[0015] A tenth aspect A10 includes the aqueous binder solution according to the first aspect A1, the aqueous binder solution further including 0.1% by weight or more and 2% by weight or less of a surfactant based on the total weight of the aqueous binder solution.

[0016] An eleventh aspect A11 comprises the aqueous binder solution according to the first aspect A1, wherein the total weight of polymers present in the aqueous binder solution is 5% to 20% by weight, based on the total weight of the aqueous binder solution.

[0017] According to a twelfth aspect A12, a method of monitoring a print head of an additive manufacturing process may include placing thermal paper on a work surface and applying an aqueous binder solution onto the thermal paper, the aqueous binder solution including a non-aqueous solvent having a boiling point of 100° C. to 175° C. in an amount of 4% to 20% by weight based on a total weight of the aqueous binder solution, and a thermoplastic binder. The thermoplastic binder includes a first polymer chain having a weight average molecular weight (Mw) of 5,000 g / mol to 15,000 g / mol, and at least one of a second polymer chain having a weight average molecular weight (Mw) of 10,000 g / mol to 50,000 g / mol and a third polymer chain having a weight average molecular weight (Mw) of 1,000 g / mol to 5,000 g / mol, wherein the first polymer chain is different from each of the second polymer chain and the third polymer chain, and the second polymer chain is different from the third polymer chain.

[0018] A thirteenth Aspect A13 includes the method according to the twelfth Aspect A12, wherein the non-aqueous solvent is present in the aqueous binder solution in an amount of 6% or more and less than 18% by weight, based on the total weight of the aqueous binder solution.

[0019] A fourteenth Aspect A14 includes the method according to the twelfth Aspect A12, wherein the non-aqueous solvent includes at least one of 2-methoxyethanol, butanol, 2-butanol, tert-butanol, 1-methoxy-2-propanol, 2-butoxyethanol, isoamyl alcohol, isobutyl alcohol, 2-butoxyethanol, and di(propylene glycol) dimethyl ether.

[0020] A fifteenth aspect A15 includes the method according to the twelfth aspect A12, wherein the first polymer chain includes at least one of polyvinylpyrrolidone (PVP) and polyvinyl alcohol (PVA).

[0021] A sixteenth Aspect A16 includes the method according to the fifteenth Aspect A15, wherein the first polymer chain is present in an amount of 5% to 20% by weight, based on the total weight of the aqueous binder solution.

[0022] A seventeenth Aspect A17 includes the method according to the twelfth Aspect A12, wherein the thermoplastic binder includes the second polymer chains in an amount of 0.5% to 7% by weight, based on the total weight of the aqueous binder solution.

[0023] An eighteenth Aspect A18 includes the method according to the seventeenth Aspect A17, wherein the thermoplastic binder includes the third polymer chains in an amount of 0.1 wt % or more and 5 wt % or less, based on the total weight of the aqueous binder solution.

[0024] A nineteenth Aspect A19 includes the method according to the twelfth Aspect A12, wherein the total weight of polymer present in the aqueous binder solution is 5% to 20% by weight, based on the total weight of the aqueous binder solution.

[0025] According to a twentieth aspect A20, a method of additive manufacturing includes depositing a layer of powder on a work surface and selectively applying an aqueous binder solution to the layer of powder in a pattern representative of the structure of a part, the aqueous binder solution including a thermoplastic binder and a non-aqueous solvent having a boiling point between 100° C. and 175° C., inclusive, in an amount of between 4% and 20% by weight, based on the total weight of the aqueous binder solution. a thermoplastic binder comprising a first polymer chain having a weight average molecular weight (Mw) of from 5,000 g / mol to 15,000 g / mol and at least one of a second polymer chain having a weight average molecular weight (Mw) of from 10,000 g / mol to 50,000 g / mol and a third polymer chain having a weight average molecular weight (Mw) of from 1,000 g / mol to 5,000 g / mol, wherein the first polymer chain is different from each of the second polymer chain and the third polymer chain, and the second polymer chain is different from the third polymer chain; and selectively applying an aqueous binder solution to combine the first polymer chain with at least one of the second polymer chain and the third polymer chain to form a green body part.

[0026] Additional features and advantages of the embodiments disclosed herein are set forth in the detailed description which follows, and in part will be readily apparent to those skilled in the art from the detailed description, or may be learned by practice of the embodiments described and disclosed herein, including the following detailed description, the claims, and the accompanying drawings.

[0027] It is to be understood that both the foregoing general description and the following detailed description present aspects that are intended to provide an overview or framework for understanding the nature and characteristics of the claimed aspects. The accompanying drawings are included to provide a further understanding, and are incorporated in and constitute a part of this specification. The drawings illustrate various aspects of the present disclosure and, together with the description, serve to explain its principles and operation. [Brief description of the drawings]

[0028] [Figure 1]FIG. 1 is a flowchart of an exemplary method for producing a part by additive manufacturing using an aqueous binder solution according to one or more embodiments shown and described herein. [Diagram 2] FIG. 2 is a block diagram of one embodiment of an additive manufacturing apparatus used to manufacture a part according to the method of FIG. [Diagram 3] FIG. 3 is a flowchart of an exemplary method for monitoring a print head of an additive manufacturing process using an aqueous binder solution according to one or more embodiments shown and described herein. [Figure 4] FIG. 4 is a block diagram of the additive manufacturing device shown in FIG. 2 used to monitor a printhead according to the method of FIG. 3. [Diagram 5] FIG. 5 is a photograph of a comparative aqueous binder solution coated on thermal paper according to one or more embodiments shown and described herein. [Figure 6] FIG. 6 is a photograph of an example aqueous binder solution coated on thermal paper according to one or more embodiments shown and described herein. [Figure 7] FIG. 7 is a photograph of an example aqueous binder solution coated on thermal paper according to one or more embodiments shown and described herein. [Figure 8] FIG. 8 is a photograph of an example aqueous binder solution coated on thermal paper according to one or more embodiments shown and described herein. [Figure 9] FIG. 9 is a photograph of a comparative aqueous binder solution coated on thermal paper. [Figure 10] FIG. 10 is a photograph of an example aqueous binder solution coated on thermal paper according to one or more embodiments shown and described herein. [Figure 11] FIG. 11 is a photograph of an example aqueous binder solution coated on thermal paper according to one or more embodiments shown and described herein. [Figure 12] FIG. 12 is a photograph of an example aqueous binder solution coated on thermal paper according to one or more embodiments shown and described herein. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0029] Various embodiments of the aqueous binder solution for use in additive manufacturing processes are described in detail below. In particular, the various embodiments of the aqueous binder solution include a thermoplastic binder, 4% to 20% by weight of a non-aqueous solvent (having a boiling point of 100° C. to 175° C.), and water. Various embodiments of the aqueous binder solution are described herein with specific reference to the accompanying drawings.

[0030] As used herein, ranges can be expressed as from "about" one particular value, or to "about" another particular value. When such a range is expressed, another aspect includes from the one particular value or to the other particular value. Similarly, when values ​​are expressed as approximations, for example by use of the antecedent "about," it will be understood that the particular value forms another aspect. It will be understood that the endpoints of each of the ranges (upper and lower) are significant both in relation to the other endpoint, and independently of the other endpoint.

[0031] Directional terms used in this specification (e.g., up, down, right, left, front, back, top, bottom) are used solely with reference to the depicted drawings and are not intended to imply absolute directions.

[0032] As used herein, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to an element preceded by "a" includes aspects having two or more of such elements unless the context clearly dictates otherwise.

[0033] The terms "weight percent" or "weight % (wt%)" used herein refer to the weight fraction of a component of an aqueous binder solution based on the total amount (i.e., weight) of the aqueous binder solution, unless otherwise specified.

[0034] The term "boiling point" as used herein refers to the boiling point of a component at one atmosphere pressure, unless otherwise specified.

[0035] As used herein, "non-covalent bond" means that the first and second functional groups interact with each other through weak non-covalent forces, such as interactions or bonds, to link or otherwise bond the thermoplastic polymer chains. As used herein, the term "weak non-covalent forces" is intended to refer to hydrogen bonds, ionic bonds, van der Waals forces, and the like.

[0036] As used herein, the phrases "green body metal part" and "green body part" refer to a part that has not been subjected to a heat treatment to remove the chemical binder. As used herein, the phrases "brown body metal part" and "brown body part" refer to a part that has been subjected to a heat treatment to remove the chemical binder. As used herein, "metal part" refers to a part having a metallic material. Although various embodiments are described in the context of metal parts, the binder solutions described herein are applicable to a wide variety of parts, including, but not limited to, polymeric and ceramic parts.

[0037] The phrase "water-based" as used herein includes mixtures, solutions, suspensions, dispersions, and the like that contain water as the primary liquid by volume, but may contain one or more other liquids. Thus, the solvent used in the various binder solutions is predominantly water. In some embodiments, water is present in a concentration of at least about 50% by volume of the binder solution, and in certain embodiments, water is present in a concentration of at least about 75% by volume. As used herein, the term "water" includes deionized water, distilled water, and tap water, unless otherwise specified. In some embodiments, the water is ASTM D1193 Type IV or higher grade water.

[0038] Many binder jetting additive manufacturing processes use a chemical binder (e.g., a polymer adhesive) to bond layers of powder together to form a three-dimensional object. The chemical binder may be, for example, a polymer adhesive that is selectively applied onto a powder bed in a pattern that represents the layers of the part being manufactured.

[0039] Conventional binder solutions that contain a relatively large amount of non-aqueous solvent (e.g., greater than 20 wt%) may require a relatively long time to penetrate into a layer of powder, which can increase the time required before a subsequent layer of powder can be deposited within the build volume. Long penetration times reduce the throughput of an additive manufacturing device, which in turn reduces productivity.

[0040] To shorten the penetration time, a portion of the non-aqueous solvent can be replaced with water, however, reducing the amount of non-aqueous solvent to a relatively small amount (e.g., less than 4% by weight) may result in a solution that does not form a pattern on the thermal paper.

[0041] As mentioned above, the aqueous binder solution described herein includes a thermoplastic binder, 4% to 20% by weight of a non-aqueous solvent (having a boiling point of 100° C. to 175° C.), and water. The 20% or less by weight of the non-aqueous solvent ensures that the aqueous binder solution has a relatively short penetration time compared to conventional binder solutions. The 4% or more by weight of the non-aqueous solvent ensures that the aqueous binder solution forms a pattern on the thermal paper, which is important for monitoring the health of the printhead since sporadic spurting can result in poor part quality. These and additional advantages are described in more detail below.

[0042] In various aspects, the thermoplastic binder can include a first polymer chain and at least one of a second polymer chain and a third polymer chain. As used herein, the term "polymer chain" includes a polymer backbone (main chain) and functional groups grafted thereon. In some aspects, the thermoplastic binder can include oxygen (O 2A thermoplastic binder is a thermoplastic binder that decomposes without the need for the presence of a metal oxide (e.g., in a vacuum, inert or reducing atmosphere) and generally with a very low char yield. Thus, in some aspects, the thermoplastic binder can be cleanly and easily removed from the part during sintering to produce a consolidated part that is substantially free of the thermoplastic binder and decomposition products (including, but not limited to, metal oxides and carbides) that may be produced during heat treatment of a printed metal part.

[0043] The first polymer chain may include at least a first functional group. The functional group of the first thermoplastic polymer chain may include, by way of example and not limitation, at least one of a hydrogen bond donor, a hydrogen bond acceptor, a negatively charged group, and a positively charged group. For example, in various embodiments, the first functional group may be incorporated into or grafted onto the backbone of the polymer chain (e.g., a vinyl backbone, an amide backbone, an acrylic backbone, etc.), and the first functional group may be selected from a hydroxyl group, a carboxylate group, an amine, a thiol, an amide, or other suitable functional group that allows for weak non-covalent bonding (e.g., hydrogen bonding) between the first polymer chain and the second or third polymer chain.

[0044] In various embodiments, the first polymer chain may include a polymer such as, but not limited to, polyvinylpyrrolidone (PVP), polyvinyl alcohol (PVA), and at least one of their derivatives. In some embodiments, the first polymer chain may have a weight average molecular weight (Mw or weight average) of 5,000 g / mol to 15,000 g / mol. For example, the first polymer chain may have a weight average molecular weight (Mw) of 5,000 g / mol to 15,000 g / mol, 5,000 g / mol to 12,500 g / mol, 7,000 g / mol to 15,000 g / mol, 7,000 g / mol to 12,500 g / mol, 9,000 g / mol to 15,000 g / mol, or 9,000 g / mol to 12,500 g / mol, including any ranges and subranges therebetween.

[0045] The first polymer chains can be present in the binder solution in an amount of from 5% to 20% by weight, from 5% to 18% by weight, from 5% to 16% by weight, from 5% to 14% by weight, from 5% to 12% by weight, from 7% to 20% by weight, from 7% to 18% by weight, from 7% to 16% by weight, from 7% to 14% by weight, from 7% to 12% by weight, from 9% to 20% by weight, from 9% to 18% by weight, from 9% to 16% by weight, from 9% to 14% by weight, from 9% to 12% by weight, based on the total weight of the aqueous binder solution, including any range and subrange therebetween.

[0046] The thermoplastic binder may include, in addition to the first polymer chain, a second polymer chain, a third polymer chain, or a second polymer chain and a third polymer chain. The second polymer chain may include at least a second functional group. The functional group of the second thermoplastic polymer chain may include, by way of example and not limitation, at least one of a hydrogen bond donor, a hydrogen bond acceptor, a negatively charged group, and a positively charged group. In some embodiments, the second functional group of the second polymer chain may be complementary to the functional group of the first polymer chain of the thermoplastic binder to facilitate non-covalent bonding between the first polymer chain and the second polymer chain. For example, in various embodiments, the second functional group can be incorporated into or grafted onto the backbone of the polymer chain (e.g., a vinyl backbone, an amide backbone, an acrylic backbone, etc.), and the second functional group can be selected from a hydroxyl group, a carboxylate group, an amine, a thiol, an amide, or other suitable functional group that allows for weak non-covalent bonding (e.g., hydrogen bonding) between the first polymer chain and the second polymer chain.

[0047] In various embodiments, the second polymer chain may include a polymer such as, but not limited to, polyvinyl alcohol (PVA), polyamide, polyacrylamide (PAAm), polyvinyl methyl ether maleic anhydride (PVME-MA), and at least one of their derivatives. In some embodiments, the second polymer chain may have a weight average molecular weight (Mw or weight average) of 10,000 g / mol to 50,000 g / mol. For example, the second polymer chain may have a molecular weight of 10,000 g / mol to 50,000 g / mol, 10,000 g / mol to 30,000 g / mol, 10,000 g / mol to 25,000 g / mol, 10,000 g / mol to 23,000 g / mol, 13,000 g / mol to 50,000 g / mol, 13,000 g / mol to 30,000 g / mol, The polymer may have a weight average molecular weight (Mw) of from 13,000 g / mol to 25,000 g / mol, from 13,000 g / mol to 23,000 g / mol, from 23,000 g / mol to 50,000 g / mol, from 23,000 g / mol to 30,000 g / mol, from 23,000 g / mol to 25,000 g / mol, including any ranges and subranges therebetween.

[0048] When present, the second polymer chain can be included in the binder solution in an amount of from 0.5 to 7 wt%, from 0.5 to 6 wt%, from 0.5 to 5 wt%, from 1 to 7 wt%, from 1 to 6 wt%, from 1 to 5 wt%, from 2 to 7 wt%, from 2 to 6 wt%, from 2 to 5 wt%, from 3 to 7 wt%, from 3 to 6 wt%, or from 3 to 5 wt%, based on the total weight of the aqueous binder solution, including any ranges and subranges therebetween.

[0049] The third polymer chain may include at least a third functional group different from the first functional group of the first polymer chain and the second functional group of the second polymer chain. The functional group of the third thermoplastic polymer chain may include, by way of example and not limitation, at least one of a hydrogen bond donor, a hydrogen bond acceptor, a negatively charged group, and a positively charged group. In some embodiments, the second functional group of the second polymer chain and the third functional group of the third polymer chain may each be complementary to the first functional group of the first polymer chain of the thermoplastic binder to facilitate non-covalent bonding between the first polymer chain, the second polymer chain, and the third polymer chain. For example, in various embodiments, the third functional group may be selected from a hydroxyl group, a carboxylate group, an amine, a thiol, an amide, or other suitable functional group that allows for weak non-covalent bonding between the first polymer chain and the third polymer chain.

[0050] In various embodiments, the third polymer chain can include a polymer such as, but not limited to, polyacrylic acid (PAA), polymethacrylic acid (PMAA), polyacrylamide (PAAm), and at least one of their derivatives. In some embodiments, the third polymer chain can have a weight average molecular weight (Mw or weight average) of 1,000 g / mol to 5,000 g / mol. For example, the second polymer chain can have a weight average molecular weight (Mw) of 1,000 g / mol to 5,000 g / mol, 1,500 g / mol to 3,000 g / mol, or 1,500 g / mol to 2,000 g / mol, including any ranges and subranges therebetween.

[0051] In some embodiments, the specific polymer selected as the third polymer chain may vary depending on the specific polymer selected as the first polymer chain and the specific polymer selected as the second polymer chain, if any.For example, the first polymer chain may be PVP, the second polymer chain may be PVA, and the third polymer chain may be PAA.Other combinations of polymers may be used, provided that their functional groups can form non-covalent bonds with each other.For example, in some embodiments, one of the functional groups is a hydrogen donor and the other functional group is a hydrogen acceptor.

[0052] When present, the third polymer chain can be included in the binder solution in an amount of from 0.1 to 5 wt%, from 0.1 to 3 wt%, from 0.1 to 2 wt%, from 0.5 to 5 wt%, from 0.5 to 3 wt%, from 0.5 to 2 wt%, from 1 to 5 wt%, from 1 to 3 wt%, from 1 to 2 wt%, based on the total weight of the aqueous binder solution, including any ranges and subranges therebetween.

[0053] As mentioned above, in some aspects, one or both of the second polymer chain and the third polymer chain may be included in the binder solution. For example, the binder solution may include a first polymer chain and a second polymer chain, may include a first polymer chain and a third polymer chain, or may include a first polymer chain, a second polymer chain, and a third polymer chain. It should be further understood that in various aspects, the first polymer chain is different from each of the second polymer chain and the third polymer chain, and the second polymer chain is different from the third polymer chain. The particular polymer selected for each polymer chain may vary depending on the particular polymer(s) selected for the other polymer chain. In some aspects, the binder solution may include PVP as the first polymer chain and PVA as the second polymer chain. In some aspects, the binder solution may include PVP as the first polymer chain and PAA as the third polymer chain. In some embodiments, the binder solution may include PVP as a first polymer chain, PVA as a second polymer chain, and PAA as a third polymer chain. Other polymer chain combinations are possible and contemplated.

[0054] In some embodiments, the polymers of the thermoplastic binder (e.g., the first polymer chain, the second polymer chain, or the third polymer chain) can be present in a total weight of 5% to 20% by weight based on the total weight of the aqueous binder solution. For example, the total weight of the polymers can be 5% to 20% by weight, 5% to 19% by weight, 5% to 18% by weight, 10% to 20% by weight, 10% to 19% by weight, 10% to 18% by weight, 12% to 20% by weight, 12% to 19% by weight, or 12% to 18% by weight based on the total weight of the aqueous binder solution.

[0055] The first polymer chain and the second polymer chain or the third polymer chain may be included in the binder solution in an amount that allows for a suitable degree of bonding between the first polymer chain and the second polymer chain or the third polymer chain to result in a green body part having suitable green body strength for handling during processing after printing. Additionally, the polymer chain may be included in an amount such that the binder solution has a viscosity (rheometer viscosity) of about 1 centipoise (cP) to about 40 cP. In some embodiments, the binder solution has a viscosity of 2 cP to 40 cP, 2 cP to 35 cP, 2 cP to 30 cP, 2 cP to 25 cP, 2 cP to 20 cP, 2 cP to 15 cP, 2 cP to 12 cP, 4 cP to 40 cP, 4 cP to 35 cP, 4 cP to 30 cP, 4 cP to 25 cP, 4 cP to 20 cP, 4 cP to 15 cP, 4 cP to 12 cP, 6 cP to 40 cP, 6 cP to 35 cP, 6 cP to 30 cP, 6 cP to 25 cP, 6 cP to 20 cP, 6 cP to 15 cP, 6 cP to 12 cP, 8 cP to 40 cP, 8 cP to 35 cP, 8 cP to 30 cP, 8 cP to 25 cP, 8 cP to 20 cP, 8 cP to 15 cP, 8 cP to 12 cP, and any ranges and subranges therebetween.

[0056] The binder solution includes a binder medium in addition to the thermoplastic binder. The binder medium may include, for example, at least one of water and one or more non-aqueous solvents. In some embodiments, the aqueous binder solution may include a non-aqueous solvent having a boiling point of more than 100° C. and less than or equal to 175° C. at 1 atmosphere. The non-aqueous solvent may generally be non-reactive (e.g., inert) so as not to react with the powder material, the thermoplastic binder, or other additives that may be included in the aqueous binder solution. In some embodiments, the non-aqueous solvent, in addition to being a solvent for the polymer chains, may act as a wetting agent, slowing the evaporation of water in the binder medium, thereby maintaining the reliability of the deposition and reducing the risk of flash curing during printing. The non-aqueous solvent may be at least one of, by way of example and not limitation, 2-methoxyethanol, butanol, 2-butanol, tert-butanol, 1-methoxy-2-propanol, 2-butoxyethanol, isoamyl alcohol, isobutyl alcohol, 2-butoxyethanol, and di(propylene glycol) dimethyl ether. In various embodiments, the non-aqueous solvent may be at least one of 2-butoxyethanol and di(propylene glycol) dimethyl ether. The particular non-aqueous solvent may be selected based at least in part on the polymer chains of the thermoplastic binder and any other additives that may be included in the aqueous binder solution.

[0057] It is believed that limiting the use of non-aqueous solvents with boiling points above 100° C. can increase the vapor pressure of the aqueous binder solution while maintaining the viscosity and penetration properties of the aqueous binder solution and reduce the required curing energy. However, it has been found that solvents with boiling points above 175° C. generally increase the post-curing time by up to 50%. Thus, in various embodiments, the non-aqueous solvents can have boiling points greater than 100° C. and less than 175° C., greater than 125° C. and less than 175° C., greater than 150° C. and less than 175° C., or greater than 165° C. and less than 175° C., including any ranges and subranges therebetween. Furthermore, in some embodiments, the aqueous binder solution does not include solvents with boiling points greater than 200° C., greater than 195° C., greater than 190° C., greater than 185° C., greater than 180° C., or greater than 175° C. at 1 atmosphere pressure.

[0058] Limiting the amount of non-aqueous solvent (e.g., 20% by weight or less) ensures that the aqueous binder solution has a relatively short penetration time compared to conventional binder solutions. However, the non-aqueous solvent should be included in an amount (e.g., 4% by weight or more) that forms a pattern on the thermal paper and allows the health of the print head to be monitored. Thus, in some embodiments, the non-aqueous solvent may be included in the aqueous binder solution in an amount of 4% by weight or more and 20% by weight or less based on the total weight of the aqueous binder solution. For example, the non-aqueous solvent may be included in the aqueous binder solution in an amount of from 4% to 20% by weight, from 4% to 18% by weight, from 4% to 16% by weight, from 4% to 14% by weight, from 4% to 12% by weight, from 6% to 20% by weight, from 6% to 18% by weight, from 6% to 16% by weight, from 6% to 14% by weight, from 6% to 12% by weight, from 8% to 20% by weight, from 8% to 18% by weight, from 8% to 16% by weight, from 8% to 14% by weight, from 8% to 12% by weight, from 10% to 20% by weight, from 10% to 18% by weight, from 10% to 16% by weight, from 10% to 14% by weight, from 10% to 12% by weight, or any range or subrange therebetween.

[0059] In some embodiments, the non-aqueous solvent can include at least one of 2-butoxyethanol and di(propylene glycol) dimethyl ether, and the non-aqueous solvent can be included in the aqueous binder solution in an amount of from 4 wt % to 20 wt %, from 4 wt % to 18 wt %, from 4 wt % to 16 wt %, from 4 wt % to 14 wt %, or from 4 wt % to 12 wt %, based on the total weight of the aqueous binder solution.

[0060] In some embodiments, the non-aqueous solvent can include at least one of 2-methoxyethanol and 2-ethoxyethanol, and the non-aqueous solvent can be included in the aqueous binder solution in an amount of from 10 wt % to 20 wt %, from 10 wt % to 18 wt %, from 10 wt % to 16 wt %, from 10 wt % to 14 wt %, or from 10 wt % to 12 wt %, based on the total weight of the aqueous binder solution.

[0061] In some embodiments, the aqueous binder solution may optionally include one or more additives, such as additives that may facilitate application of the thermoplastic binder to the powder material, improve the wetting of the powder material, and improve the surface tension of the aqueous binder solution. Optional additives include surfactants, diluents, viscosity modifiers, dispersants, stabilizers, dyes or other colorants, or other additives known and used in the art. In some embodiments, the aqueous binder solution includes at least one surfactant.

[0062] In some embodiments, the surfactant improves the wetting rate and mediates the interaction between the thermoplastic binder and the powder. Surfactants suitable for use in the aqueous binder solution can include ionic (e.g., zwitterionic, cationic, or anionic) surfactants, or non-ionic surfactants, depending on the properties of the thermoplastic binder or powder material. In various embodiments, the surfactant is 2-[4-(2,4,4-trimethylpentan-2-yl)phenoxy]ethanol (e.g., TRITON® X-100 available from The Dow Chemical Company), polyoxyethylene (80) sorbitan monooleate (e.g., TWEEN® 80 available from Croda America), polyoxyethylene-23-lauryl ether (e.g., BRIJ® L23 available from Croda America), alkylene oxide copolymers (e.g., HYPERMER® KD2 available from Croda Advanced Materials), sodium dodecyl sulfate (SDS), hexadecyltrimethylammonium bromide (CTAB), and dodecyltrimethylammonium bromide (DTAB), polypropoxy quaternary ammonium chloride (e.g., Evonik). The material may be at least one of "VARIQUAT® CC42NS" available from Industries, Inc.

[0063] It is believed that the inclusion of a surfactant in the binder solution can reduce the surface tension of the binder solution, thereby improving the wetting of the powder material by the binder solution. Thus, in some embodiments, the surfactant can be included in the binder solution in an amount of 0.1 wt % or more and 2 wt % or less, 0.1 wt % or more and 1 wt % or less, 0.25 wt % or more and 2 wt % or less, or 0.25 wt % or more and 1 wt % or less, based on the total weight of the binder solution, including any ranges and subranges therein.

[0064] In various embodiments, the binder medium may include water, and water may comprise the balance of the solution in various embodiments, hi various embodiments, water may be present in an amount of 70% or more, 75% or more, 80% or more, or 85% or more by weight, based on the total weight of the binder solution.

[0065] Further, in various embodiments, green body parts formed using the aqueous binder solutions described herein may exhibit a green body strength of 10 MPa or more in each of the x- and y-directions of printing. As used herein, the "x-direction" refers to the portion having the largest dimension (e.g., length) along the x-axis, and the "y-direction" refers to the portion having the largest dimension (e.g., length) along the y-axis. As used herein, the "x-axis" refers to the direction in which the print head moves relative to the build plate on which the green body part is produced, as shown in FIG. 2, unless otherwise specified. As used herein, the "y-axis" refers to the direction perpendicular to the x-axis (as shown in FIG. 2) such that each layer of the green body part lies in the xy-plane. The "z-axis" refers to the axis perpendicular to the xy-plane, as shown in FIG. 2, and the layers are stacked together along the z-axis. For example, the green body parts may exhibit a green body strength of 10 MPa or more and 25 MPa or less, 10 MPa or more and 20 MPa or less, 12 MPa or more and 25 MPa or less, or 12 MPa or more and 20 MPa or less, as measured according to a three-point bending test.

[0066] 1 is a block diagram illustrating one embodiment of a method 100 for producing an article by additive manufacturing using an aqueous binder solution described herein. To facilitate the description of an embodiment of method 100, reference is made to FIG. 2, which is a block diagram illustrating one embodiment of an additive manufacturing apparatus 200 that may be used to perform method 100.

[0067] 1, the method 100 begins with depositing a layer of powder material 202 that will be used to manufacture the part (block 102). In various embodiments, the layer of powder material 202 is deposited on a working surface 204 of an additive manufacturing apparatus. The powder material can be a metal powder such as nickel alloys, cobalt alloys, cobalt chromium alloys, casting alloys, titanium alloys, aluminum-based materials, tungsten, stainless steel, and the like. Depending on the particular embodiment, other powder materials may be used.

[0068] The method 100 then continues with selectively applying an aqueous binder solution 206 to the layer of powder material 202 in a pattern representative of the structure of the part (block 104). The binder solution 206 may be, for example, any one of the various embodiments of a binder solution described herein. In various embodiments, the binder solution 206 may be selectively printed using a print head 208 operated by a controller 210 based on a CAD design that includes a representation of the layer of the part to be printed.

[0069] In various aspects, a controller 210 for controlling the print head 208 can include a distributed control system or any suitable device employing a general purpose computer or an application specific device. The controller 210 can generally include a memory 212 that stores one or more instructions for controlling the operation of the print head 208. In some aspects, the memory 212 can store a CAD design that represents the structure of the part to be manufactured. In some aspects, the CAD design may include distortion compensation, and thus the CAD design may not exactly match the geometry of the final desired part. Additionally, the controller 210 can include at least one processor 214 (e.g., a microprocessor), and the memory 212 can include one or more tangible, non-transitory, machine-readable media that collectively store instructions executable by the processor 214 to control the operations described herein.

[0070] After the binder solution 206 is selectively applied to the layer of powder material 202, the thermoplastic binder 216 in the binder solution 206 at least partially coats the outer surfaces of the powder particles, thereby generating binder-coated particles 218. As described below, the thermoplastic binder 216 bonds the binder-coated particles 218 according to the pattern of the binder solution 206 printed on the layer of powder material 202 to form a layer of a green body part.

[0071] The method 100 can continue to build the part layer by layer by repeating the steps of depositing layers of powder material (block 102) and selectively applying the binder solution 206 to the layers of powder material (block 104) until a desired number of layers are printed. The thermoplastic binder 216 of the binder solution 206 bonds each successive layer and provides some strength (e.g., green body strength) to the green body part so that the structural integrity of the green body part is maintained during post-printing processing (e.g., transportation, inspection, or depowdering). That is, the green body strength provided by the thermoplastic binder 216 of the binder solution 206 maintains the bond between the particles of the powder material 202 within a layer and inhibits (e.g., resists or prevents) delamination of the layers during processing and post-printing processing of the green body part.

[0072] In various embodiments, the method 100 continues with curing the thermoplastic binder (block 106). For example, as described above, the binder solution 206 may be a mixture of the thermoplastic binder 216 and at least one solvent. In various embodiments, the first polymer chain 220 and the second polymer chain 222 of the thermoplastic binder 216 may be bonded to each other via interactions between a first functional group of the first polymer chain and a second functional group of the second polymer chain, respectively. Although the embodiment shown in FIG. 1 refers to the first polymer chain 220 and the second polymer chain 222, other polymer chains (e.g., a third polymer chain), if present, may also interact with other polymer chains in the thermoplastic binder 216.

[0073] Although some of the solvent in the binder solution 206 may evaporate during application (e.g., printing) of the binder solution 206, a certain amount of solvent may remain in the layer of powder material 202. Thus, in some embodiments, the binder solution 206 can be heat cured at a suitable temperature to evaporate the solvent and enable efficient bonding of the printed layers, thereby forming the green body part. Heat may be applied to the green body part using infrared (IR) lamps or a heating plate, or may be applied by placing the green body part in an oven.

[0074] Unbound particles (e.g., powder material not bound by the binder solution 206) can be removed from the powder layer before or after the curing step of block 106 to create a green body part for post-processing steps such as debinding and sintering.

[0075] 1, the method 100 includes removing (e.g., debinding) a portion of the thermoplastic binder from the green body part to produce a brown body part (block 108). In various embodiments, the binder provides strength (e.g., green body strength) to the green body part, and only a portion (i.e., less than all) of the thermoplastic binder is removed during debinding of the green body part to improve the handling strength of the resulting brown body part prior to sintering.

[0076] During debinding at block 108, the green body part is heated to break some of the polymer chains of the thermoplastic binder 216. For example, the green body part may be heated to a temperature of about 600° C. or less, or about 450° C. or less. In some embodiments, the green body part is heated to a temperature between 250° C. and 450° C. Heating can be performed, for example, in an oxygen-free environment (e.g., vacuum, inert atmosphere, or a combination of both) or in air in the case of sintering of ceramic parts. In embodiments where debinding is performed in an inert atmosphere, argon, nitrogen, or another substantially inert gas can be used. In some embodiments, the debinding step can be combined with a sintering step to produce the final consolidated part.

[0077] According to various embodiments, the debinding step of block 108 may be effective to remove greater than about 95% of the thermoplastic binder 216. For example, 95% or more, 96% or more, 97% or more, 98% or more, or 99% or more of the total amount of thermoplastic binder is removed during debinding. In some embodiments, the portion of the thermoplastic binder 216 remaining in the brown body part is 5% or less, 4% or less, 3% or less, 2% or less, or 1% or less of the amount of thermoplastic binder present before the debinding step. In some embodiments, the portion of the thermoplastic binder 216 remaining in the brown body part ranges from 0.05% to 2%, or 0.1% to 1% of the amount of thermoplastic binder present before the debinding step and removed at a post-sintering stage (e.g., above 600° C., leading to higher sintering temperatures, as described according to block 110 for stainless steels, nickel alloys, etc.).

[0078] Following binder removal at block 108, the method 100 continues with sintering the brown body part to form a consolidated part (block 110). During sintering, remaining portions of the thermoplastic binder (e.g., oligomers formed during binder removal) may be removed from the brown body part, and the particles of the metal powder may be consolidated to form a consolidated part. Sintering imparts strength and integrity to the brown body part such that after cooling, the consolidated part may be suitable for use, for example, in a machine.

[0079] In some embodiments, sintering may be performed according to a two-step process including a pre-sintering step in which remnants of the thermoplastic binder are removed, and a sintering step in which the metal powder particles are consolidated. In some embodiments, sintering may be performed as a single step. During sintering, the Brown body part may be heated to a temperature greater than 500° C., greater than 800° C., or greater than 1000° C. In some embodiments, heat may be applied by placing the Brown body part in a furnace or by exposing the Brown body part to a focused energy source, such as a laser beam, an electron beam, or another suitable energy source, depending on the particular embodiment.

[0080] As described herein, it is important to monitor the health of the print head since sporadic jetting can lead to poor part quality. Figure 3 is a block diagram illustrating an embodiment of a method 300 for monitoring a print head of an additive manufacturing process using the aqueous binder solutions described herein. To facilitate the description of an embodiment of the method 300, reference is made to Figure 4, which is a block diagram illustrating the additive manufacturing apparatus 200 shown in Figure 1 that may be used to perform the method 300.

[0081] 3, the method 300 begins with placing thermal paper 400 on the work surface 204 of the additive manufacturing apparatus 200 (block 302). The thermal paper 400 is coated with a material that contains a developer compound that changes color when in contact with a particular solution. Commercially available examples of suitable thermal paper that may be used in the method 300 include Gorilla Supply® thermal paper, POS thermal paper, Methdic thermal paper, and Alliance Supply thermal paper.

[0082] The method 300 then continues at block 304 with applying an aqueous binder solution 206 onto the thermal paper 400. The binder solution 206 may be, for example, any one of the various embodiments of binder solutions described herein. In some embodiments, the binder solution 206 may be selectively printed using a printhead 208 operated by a controller 410 based on a design that allows for evaluation of the health of the printhead (e.g., nozzle cleanliness).

[0083] The method 300 continues at block 306 by allowing the binder solution 206 to dry on the thermal paper 400 at room temperature for a period of time (eg, 10 minutes).

[0084] The method 300 continues at block 308 with evaluating the thermal paper to determine the health of the printhead 208. For example, sporadic patterns or patterns that do not match the intended design may indicate a printhead problem (e.g., clogged nozzles) that may need to be further evaluated. Typically, the printhead is given several cleaning cycles to ensure robust jetting and native pattern formation.

[0085] Although various embodiments described herein are described with reference to methods 100 and 300, it should be understood that the aqueous binder solution embodiments described herein may be used with a variety of methods known and used by those of skill in the art. In particular, curing and sintering may be accomplished in a number of different ways, at a number of different steps, and at a number of different locations. EXAMPLES

[0086] The following examples are provided to illustrate various aspects, but are not intended to limit the scope of the claims. Unless otherwise specified, all parts and percentages are by weight. Approximate physical properties, characteristics, parameters, etc. are provided below for various examples, comparative examples, and materials used in the examples and comparative examples.

[0087] Six example aqueous binder solutions (Samples 1-6) and two comparative aqueous binder solutions (Comparative Samples A and B) were prepared by mixing a thermoplastic binder in the form of one or more polymer chains in water and at least one additional co-solvent. All formulations (Comparative Samples A and B and Samples 1-6) contained water as the primary solvent. Comparative Sample A and Samples 1-3 contained the non-aqueous solvent 2-butoxyethanol, which has a boiling point of 171° C. at 1 atm and a vapor pressure of 0.8 mmHg. Comparative Sample B and Samples 4-6 contained the non-aqueous solvent di(propylene glycol) dimethyl ether (DPGDME), which has a boiling point of 175° C. at 1 atm and a vapor pressure of 0.6 mmHg. All formulations (Comparative Samples A and B and Samples 1-6) contained polyvinylpyrrolidone (PVP) as the first polymer chain, poly(vinyl alcohol) (PVA) as the second polymer chain, and poly(acrylic acid) (PAA) as the third polymer chain. All formulations (Comparative Samples A and B and Samples 1-6) also contained surfactants Triton-X and KD-2. The formulations for Comparative Samples A and B and Samples 1-6 are shown in Table 1 below.

[0088] [Table 1] To evaluate the penetration rate, samples were prepared by depositing Praxair Truform 316-L00 powder into a Petri dish and repeatedly tapping down the Petri dish containing the powder approximately 0.5 to 1 inch from the surface 332 times using an AutoTap Tap Density Analyzer. For each sample, three 20 μL droplets of binder solution were dispensed onto the powder bed and observed using video or timed using a stopwatch. The penetration time of the droplets was measured from the first contact of the binder solution to the disappearance of the sheen. The penetration times (seconds) are reported in Table 1.

[0089] Green body samples were prepared by filling a circular silicone mold (4 cm × 0.45 cm) with metal powder and adding binder to make a wet block. The samples were cured in a conventional oven at 200 °C or 170 °C for 1 h. After cooling, the sample block was removed from the mold and used for further studies. The green body strength was measured using an Instron three-point tester. The green body strength is reported in Table 1.

[0090] As shown in Table 1, Samples 1-3, which contained 4 wt%, 6 wt%, and 8 wt%, respectively, of 2-butoxyethanol, had similar penetration times compared to Comparative Sample A, which contained 2 wt% 2-butoxyethanol. Samples 4-6, which contained 4 wt%, 6 wt%, and 8 wt%, respectively, of DPGDME, had similar penetration times compared to Comparative Sample B, which contained 2 wt% DPGDME.

[0091] 5-12, 40 μL of Comparative Samples A and B (designated as CA and CB) and Samples 1-6 (designated as S1-S6) were drawn into a capillary tube, spread onto thermal paper in an "X" pattern, and allowed to dry for 10 minutes. As shown, formulations of Samples 1-6 with 4 wt%, 6 wt%, or 8 wt% non-aqueous solvent, respectively, formed a pattern on the thermal paper. Comparative Samples A and B only wetted the thermal paper and did not form a pattern on the thermal paper.

[0092] As illustrated in Table 1 and Figures 5 to 12, an aqueous binder solution containing 4 wt % to 20 wt % of a non-aqueous solvent has a comparable penetration time to an aqueous binder solution containing less than 4 wt % of a non-aqueous solvent, and forms a pattern on the thermal paper.

[0093] Further aspects of the present disclosure are provided by the subject matter of the following appendices.

[0094] (Appendix 1) 1. An aqueous binder solution for use in additive manufacturing, comprising: A first polymer chain having a weight average molecular weight (Mw) of 5,000 g / mol or more and 15,000 g / mol or less; At least one of a second polymer chain having a weight average molecular weight (Mw) of 10,000 g / mol to 50,000 g / mol and a third polymer chain having a weight average molecular weight (Mw) of 1,000 g / mol to 5,000 g / mol; a non-aqueous solvent having a boiling point of 100° C. or more and 175° C. or less, and in an amount of 4% by weight or more and 20% by weight or less based on the total weight of the aqueous binder solution; Water, the first polymer chain is different from each of the second polymer chain and the third polymer chain, and the second polymer chain is different from the third polymer chain; Water-based binder solution.

[0095] (Appendix 2) 2. The aqueous binder solution of claim 1, wherein the non-aqueous solvent is present in the aqueous binder solution in an amount of 6 wt % or more and less than 18 wt %, based on a total weight of the aqueous binder solution.

[0096] (Appendix 3) 3. The aqueous binder solution of claim 1 or 2, wherein the non-aqueous solvent comprises at least one of 2-methoxyethanol, butanol, 2-butanol, tert-butanol, 1-methoxy-2-propanol, 2-butoxyethanol, isoamyl alcohol, isobutyl alcohol, 2-butoxyethanol, and di(propylene glycol) dimethyl ether.

[0097] (Appendix 4) 4. The aqueous binder solution according to any one of claims 1 to 3, wherein the first polymer chain contains at least one of polyvinylpyrrolidone (PVP) and polyvinyl alcohol (PVA).

[0098] (Appendix 5) 5. The aqueous binder solution according to claim 1, wherein the first polymer chains are present in an amount of 5% by weight to 20% by weight, based on the total weight of the aqueous binder solution.

[0099] (Appendix 6) 6. The aqueous binder solution according to any one of claims 1 to 5, wherein the thermoplastic binder contains the second polymer chain in an amount of 0.5% by weight or more and 7% by weight or less, based on the total weight of the aqueous binder solution.

[0100] (Appendix 7) 7. The aqueous binder solution according to any one of claims 1 to 6, wherein the thermoplastic binder contains the third polymer chain in an amount of 0.1% by weight or more and 5% by weight or less, based on the total weight of the aqueous binder solution.

[0101] (Appendix 8) 8. The aqueous binder solution according to any one of claims 1 to 7, wherein the second polymer chain comprises at least one of polyvinyl alcohol (PVA), polyacrylamide (PAAm), polyvinyl methyl ether maleic anhydride (PVME-MA), and derivatives thereof.

[0102] (Appendix 9) 9. The aqueous binder solution according to any one of claims 1 to 8, wherein the third polymer chain comprises polyacrylic acid (PAA), polymethyl methacrylate (PMMA), polyacrylamide (PAAm), and derivatives thereof.

[0103] (Appendix 10) The aqueous binder solution according to any one of claims 1 to 9, further comprising 0.1 wt % to 2 wt % of a surfactant based on the total weight of the aqueous binder solution.

[0104] (Appendix 11) 11. The aqueous binder solution according to claim 1, wherein a total weight of the polymer present in the aqueous binder solution is 5% by weight or more and 20% by weight or less, based on a total weight of the aqueous binder solution.

[0105] (Appendix 12) 1. A method for monitoring a print head in an additive manufacturing process, comprising: Placing thermal paper on a work surface; applying an aqueous binder solution onto the thermal paper; The aqueous binder solution has a boiling point of 100° C. or more and 175° C. or less, and includes a non-aqueous solvent in an amount of 4% by weight or more and 20% by weight or less based on the total weight of the aqueous binder solution, and a thermoplastic binder; The thermoplastic binder is A first polymer chain having a weight average molecular weight (Mw) of 5,000 g / mol or more and 15,000 g / mol or less; At least one of a second polymer chain having a weight average molecular weight (Mw) of 10,000 g / mol to 50,000 g / mol and a third polymer chain having a weight average molecular weight (Mw) of 1,000 g / mol to 5,000 g / mol, the first polymer chain is different from each of the second polymer chain and the third polymer chain, and the second polymer chain is different from the third polymer chain; method.

[0106] (Appendix 13) 13. The method of claim 12, wherein the non-aqueous solvent is present in the aqueous binder solution in an amount of 6 wt % or more and less than 18 wt %, based on the total weight of the aqueous binder solution.

[0107] (Appendix 14) 14. The method of claim 12 or 13, wherein the non-aqueous solvent comprises at least one of 2-methoxyethanol, butanol, 2-butanol, tert-butanol, 1-methoxy-2-propanol, 2-butoxyethanol, isoamyl alcohol, isobutyl alcohol, 2-butoxyethanol, and di(propylene glycol) dimethyl ether.

[0108] (Appendix 15) 15. The method according to any one of claims 12 to 14, wherein the first polymer chain contains at least one of polyvinylpyrrolidone (PVP) and polyvinyl alcohol (PVA).

[0109] (Appendix 16) 16. The method according to any one of claims 12 to 15, wherein the first polymer chains are present in an amount of 5% by weight or more and 20% by weight or less, based on the total weight of the aqueous binder solution.

[0110] (Appendix 17) 17. The method according to any one of claims 12 to 16, wherein the thermoplastic binder contains the second polymer chain in an amount of 0.5% by weight or more and 7% by weight or less, based on the total weight of the aqueous binder solution.

[0111] (Appendix 18) The method according to any one of claims 12 to 17, wherein the thermoplastic binder contains the third polymer chain in an amount of 0.1% by weight or more and 5% by weight or less, based on the total weight of the aqueous binder solution.

[0112] (Appendix 19) The method according to any one of claims 12 to 18, wherein the total weight of the polymer present in the aqueous binder solution is 5% by weight or more and 20% by weight or less based on the total weight of the aqueous binder solution.

[0113] (Appendix 20) 1. A method of additive manufacturing comprising: depositing a layer of powder on a work surface; selectively applying an aqueous binder solution to the layer of powder in a pattern representative of the structure of the part, the aqueous binder solution including a thermoplastic binder and a non-aqueous solvent having a boiling point of 100° C. to 175° C. in an amount of 4% by weight to 20% by weight, based on the total weight of the aqueous binder solution; The thermoplastic binder is A first polymer chain having a weight average molecular weight (Mw) of 5,000 g / mol or more and 15,000 g / mol or less; At least one of a second polymer chain having a weight average molecular weight (Mw) of 10,000 g / mol to 50,000 g / mol and a third polymer chain having a weight average molecular weight (Mw) of 1,000 g / mol to 5,000 g / mol; a non-aqueous solvent having a boiling point of 100° C. or more and 175° C. or less, and in an amount of 4% by weight or more and 20% by weight or less based on the total weight of the aqueous binder solution; Water, selectively applying the aqueous binder solution, wherein the first polymer chains are different from each of the second polymer chains and the third polymer chains, and the second polymer chains are different from the third polymer chains; and combining the first polymer chain with at least one of the second polymer chain and the third polymer chain to form a green body part.

[0114] It will be apparent to those skilled in the art that various modifications and variations can be made to the aspects of the present disclosure without departing from the spirit and scope of the disclosure, and thus the present disclosure is intended to cover such modifications and variations provided they come within the scope of the appended claims and their equivalents.

Claims

1. An aqueous binder solution (206) for use in additive manufacturing, comprising: A thermoplastic binder (216), A first polymer chain (220) having a weight average molecular weight (Mw) of 5,000 g / mol or more and 15,000 g / mol or less; at least one of a second polymer chain (222) having a weight average molecular weight (Mw) of 10,000 g / mol to 50,000 g / mol and a third polymer chain having a weight average molecular weight (Mw) of 1,000 g / mol to 5,000 g / mol; a thermoplastic binder (216), wherein the first polymer chains (220) are different from each of the second polymer chains (222) and the third polymer chains, and the second polymer chains (222) are different from the third polymer chains; a non-aqueous solvent having a boiling point of 100° C. or more and 175° C. or less, and in an amount of 4% by weight or more and 20% by weight or less based on the total weight of the aqueous binder solution (206); Water, Including, the non-aqueous solvent is present in the aqueous binder solution (206) in an amount of 6% by weight or more and less than 18% by weight, based on the total weight of the aqueous binder solution (206); Aqueous binder solution (206).

2. 2. The aqueous binder solution (206) of claim 1, wherein the non-aqueous solvent comprises at least one of 2-methoxyethanol, butanol, 2-butanol, tert-butanol, 1-methoxy-2-propanol, 2-butoxyethanol, isoamyl alcohol, isobutyl alcohol, 2-butoxyethanol, and di(propylene glycol) dimethyl ether.

3. 2. The aqueous binder solution (206) of claim 1, wherein the first polymer chains (220) comprise at least one of polyvinylpyrrolidone (PVP) and polyvinyl alcohol (PVA).

4. 4. The aqueous binder solution (206) of claim 3, wherein the first polymer chains (220) are present in an amount of 5% to 20% by weight, based on a total weight of the aqueous binder solution (206).

5. 2. The aqueous binder solution of claim 1, wherein the thermoplastic binder comprises the second polymer chains in an amount of from 0.5% to 7% by weight, based on a total weight of the aqueous binder solution.

6. 6. The aqueous binder solution of claim 5, wherein the thermoplastic binder comprises the third polymer chains in an amount of from 0.1% to 5% by weight, based on a total weight of the aqueous binder solution.

7. 1. A method (300) for monitoring a print head (208) in an additive manufacturing process, comprising: Placing thermal paper (400) on a work surface (204); applying an aqueous binder solution (206) onto the thermal paper (400); Including, The aqueous binder solution (206) has a boiling point of 100° C. or more and 175° C. or less, and contains 4% by weight or more and 20% by weight or less of a non-aqueous solvent based on the total weight of the aqueous binder solution (206). and a thermoplastic binder (216), the non-aqueous solvent is present in the aqueous binder solution (206) in an amount of 6% by weight or more and less than 18% by weight, based on the total weight of the aqueous binder solution (206); The thermoplastic binder (216) is A first polymer chain (220) having a weight average molecular weight (Mw) of 5,000 g / mol or more and 15,000 g / mol or less; at least one of a second polymer chain (222) having a weight average molecular weight (Mw) of 10,000 g / mol to 50,000 g / mol and a third polymer chain having a weight average molecular weight (Mw) of 1,000 g / mol to 5,000 g / mol; the first polymer chain (220) is different from each of the second polymer chain (222) and the third polymer chain; the second polymer chain (222) is different from the third polymer chain; Method (300).

8. 8. The method (300) of claim 7, wherein the non-aqueous solvent comprises at least one of 2-methoxyethanol, butanol, 2-butanol, tert-butanol, 1-methoxy-2-propanol, 2-butoxyethanol, isoamyl alcohol, isobutyl alcohol, 2-butoxyethanol, and di(propylene glycol) dimethyl ether.

9. 9. The method (300) of claim 7 or claim 8, wherein the first polymer chain (220) comprises at least one of polyvinylpyrrolidone (PVP) and polyvinyl alcohol (PVA).

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