Three-dimensional printing

Abstract

In one example of a 3D printing method, a polymeric build material or a polymeric composite build material is applied. A portion of the build material is negatively patterned to define a removable build material portion and a remaining build material portion. The negative patterning includes selectively applying an anti-coalescing polymer solution including a polymer having pendent reactive functional groups, and selectively applying an anti-coalescing crosslinker solution including a multifunctional crosslinker. The pendent reactive functional groups react with the multifunctional crosslinker to form an insoluble gel network within the polymeric build material or the polymeric composite build material in the removable build material portion. Layers of a final 3D object are formed from at least a portion of the remaining build material portion based on a 3D object model. A portion of the polymeric build material or the polymeric composite build material in the removable build material portion remains physically separated from the layers.

Description

BACKGROUND

[0001] Three-dimensional (3D) printing can be an additive printing method for making three-dimensional solid parts from a digital model. 3D printing is often used for rapid product prototyping, mold generation, mold master generation, and small batch manufacturing. Some 3D printing techniques are considered additive methods in that they involve the application of successive layers of material, which in some instances can include a build material, a binder, and / or other printing liquid(s), or combinations thereof. This is in contrast to traditional machining processes, which often rely on the removal of material to generate the final part. Some 3D printing methods use a chemical binder or binding agent in order to bind the build material together. Other 3D printing methods involve at least partial solidification, thermal fusion / fusing, melting, sintering, etc. of the build material, and the mechanism of material coalescence can depend on the type of build material used. For some materials, at least partial melting can be achieved using heat-assisted extrusion, for other materials (e.g., polymerizable materials), solidification or fusing can be achieved using, for example, ultraviolet or infrared light.

[0002] SUMMARY

[0003] Features of examples of the present disclosure will become apparent by reference to the following detailed description and drawings, in which like reference numerals correspond to similar, though perhaps not identical, components. For the sake of brevity, the figures can not include a description of all features of the examples in which identical structures are commonly present. Furthermore, in an effort to provide a concise description of the examples, all features of an actual implementation can not be described in the specification. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made. These decisions will significantly affect the

[0004] Figure 1 is a flowchart illustrating one example of a 3D printing method disclosed herein;

[0005] Figures 2A-2E is a schematic and partially cross-sectional view depicting the formation of a final 3D object using one example of a 3D printing method disclosed herein;

[0006] Figure 3 is a top view of build material, some of which is negatively patterned, some of which is patterned with a fusing agent, and some of which has a detailing agent applied thereto;

[0007] Figure 4 is a flowchart illustrating another example of a 3D printing method disclosed herein; and

[0008] Figure 5 is a schematic and partially cross-sectional view of one example of a 3D printing system disclosed herein. DETAILED DESCRIPTION

[0010] Some examples of three-dimensional (3D) printing can utilize a fusing agent to pattern a polymeric build material or a polymeric composite build material. In these examples, an entire layer of the polymeric build material or the polymeric composite build material is exposed to radiation, but a patterned region of the polymeric build material or the polymeric composite build material (which in some cases is less than the entire layer) fuses and hardens to be a layer of the 3D object. In the patterned region, the fusing agent is able to at least partially penetrate into the voids between the polymeric build material or the polymeric composite build material particles and also able to spread onto the outer surfaces of the polymeric build material or the polymeric composite build material particles. This fusing agent is able to absorb radiation and convert the absorbed radiation into thermal energy, which in turn causes the polymeric build material or the polymeric composite build material in contact with the fusing agent to fuse.

[0011] Other examples of 3D printing can employ selective laser sintering (SLS) or selective laser melting (SLM). In selective laser sintering or melting processes, a laser beam is directed at a selected region (typically less than the entire layer) of a layer of polymeric build material or polymeric composite build material. The heat from the laser beam causes the polymeric build material or the polymeric composite build material under the laser beam to fuse.

[0012] Fusing (by use of a fusing agent or a laser beam) causes the polymeric build material or the polymeric composite build material to join or blend to form a single entity (i.e., a layer of the 3D object). Fusing can involve at least partial thermal fusion, melting, adhesion, and / or coalescence of the polymeric build material or the polymeric composite build material to form the layer of the 3D object.

[0013] In some cases, the thermal energy converted from absorbed radiation or applied by a laser beam can bleed or transfer into polymeric build material or polymeric composite build material particles that are not in contact with the fusing agent or the laser beam. This bleeding or transfer of thermal energy can cause polymeric build material or polymeric composite build material particles that are not desirably fused (i.e., not patterned with a fusing agent or not having a laser beam applied to them) to fuse or semi-fuse to the surface of the 3D object. These fused or semi-fused particles that are attached to the surface of the 3D object can reduce the surface finish quality and precision of the 3D object. For example, the surface can be undesirably rough and / or can have an undesirable appearance. As another example, the 3D object can be larger than intended.

[0014] The examples disclosed herein use an anti-coalescing polymer solution comprising a polymer having pendent reactive functional groups and an anti-coalescing crosslinker solution comprising a multifunctional crosslinker. The anti-coalescing polymer solution and the anti-coalescing crosslinker solution can be used to partially negative pattern polymer build material or polymer composite build material (referred to herein as build material) that is not desired to be part of the final 3D object but can be exposed to thermal energy that is exuded or transferred from the portion of the build material that is to be part of the final 3D object.

[0015] The terms "partially negative pattern," "negative pattern," "negative patterned," and the like as used herein refer to the application of a liquid (e.g., an anti-coalescing polymer solution and an anti-coalescing crosslinker solution) to a portion(s) of build material that is not desired to be part of the final 3D object. It is to be understood that "negative patterning" can include applying a liquid to all or less than all of the build material that is not desired to be part of the final 3D object. Thus, in some examples disclosed herein, the anti-coalescing polymer solution and the anti-coalescing crosslinker solution can be used to negative pattern i) around portions of build material that are to be part of the final 3D object, ii) features, such as holes, notches, kerfs, or other areas where build material should not fuse, or iii) combinations thereof. When using the anti-coalescing polymer solution and the anti-coalescing crosslinker solution, it is to be understood that there can be some build material that is patterned only with a detailing agent or is unpatterned (i.e., no anti-coalescing polymer solution, anti-coalescing crosslinker solution, fusing agent, laser beam, detailing agent applied thereon). In other examples disclosed herein, the anti-coalescing polymer solution and the anti-coalescing crosslinker solution can be used to negative pattern all of the build material that is not desired to be part of the final 3D object. In these examples, there is no unpatterned build material.

[0016] When the anti-coalescing polymer solution and the anti-coalescing crosslinker solution are applied on the build material, the pendent reactive functional groups react with the crosslinker to form an insoluble gel network in the build material. The term "in" as used herein means that the insoluble gel network can be on top of, along the sides of, and / or within the interstitial voids of the polymer build material or polymer composite build material. Thus, negative patterning of the build material with the anti-coalescing polymer solution and the anti-coalescing crosslinker solution defines a removable build material portion whose build material remains physically separated from the final 3D object even after exposure to energy / radiation.

[0017] The term "removable build material portion" as used herein refers to the insoluble gel network and the polymeric build material or polymeric composite build material within the insoluble gel network that can be removed from the final 3D object with a degrading agent solution. The build material within the insoluble gel network can be fused (i.e., thermally fused or coalesced), semi-fused, or unfused. When the build material within the insoluble gel network is fused or semi-fused, it is understood that the build material particles within the insoluble gel network are fused or semi-fused with other build material particles within the insoluble gel network and that these build material particles are not fused or semi-fused with build material particles outside of the insoluble gel network. The build material particles can be fused with other build material particles within the insoluble gel network when the insoluble gel network does not separate the individual particles within the insoluble gel network from each other.

[0018] The insoluble gel network prevents the build material within the insoluble gel network from fusing or semi-fusing with build material outside of the insoluble gel network. Thus, the insoluble gel network can prevent the portion of build material that does not desire to be part of the final 3D object but is exposed to the infiltrating or transferred thermal energy from fusing to the final 3D object. As such, the printing method produces i) a final 3D object having improved surface finish quality and / or precision (as compared to a 3D object printed according to a comparative 3D printing method but without using the anti-coalescing polymer solution and the anti-coalescing crosslinker solution) and ii) a removable object in contact with at least a portion of the final 3D object. The term "removable object" as used herein refers to the sum of the removable build material portions formed throughout the printing process. As such, the removable object comprises the insoluble gel network and the polymeric build material or polymeric composite build material particles intermingled with the insoluble gel network. It is understood that the removable build material portions that make up the removable object can be continuous or can be separate from each other (e.g., separated by the final 3D object).

[0019] The insoluble gel network is insoluble in any solvent, such as water, organic solvents, and the like, including the cosolvents used in the anti-coalescing polymer solution, the anti-coalescing crosslinker solution, the fusing agent, and / or the detailing agent. In some examples, the solvent can cause the insoluble gel network to swell, but not dissolve. As such, the insoluble gel network remains intact throughout the 3D printing process and is robust, at least until it is exposed to a degrading agent solution comprising a strong acid, a weak acid, and / or a reducing agent. After printing, the removable object can be exposed to a degrading agent solution to degrade the insoluble gel network. The degrading agent solution can degrade the crosslinks between the polymer and the multifunctional crosslinker, which can break down the insoluble gel network and enable the polymer to dissolve. The degradation of the insoluble gel network enables the final 3D object to be separated from the removable object and the polymeric build material or polymeric composite build material therein.

[0020] In examples disclosed herein, the anti-agglomerating polymer solution includes a polymer having pendent reactive functional groups, and the anti-agglomerating crosslinker solution includes a multifunctional crosslinker. The polymer and multifunctional crosslinker are selected so that they will react to form an insoluble gel network. More particularly, the multifunctional crosslinker crosslinks the pendent reactive functional groups of the polymer. In one example, the polymer and multifunctional crosslinker are selected so that they have a high reaction rate and a high equilibrium constant, such that the reaction to form the insoluble network occurs within the cycle time of the 3D printing process (i.e., the time from when the solutions are applied to when the build material is exposed to radiation). In this example, the pendent reactive functional groups and the multifunctional crosslinker can react almost instantaneously to form the insoluble gel network upon contact with each other. In another example, the polymer and multifunctional crosslinker are selected so that a degrading agent solution can degrade the crosslinks formed.

[0021] The pendent reactive functional groups of the polymer can be any pendent reactive functional groups that can be crosslinked by the multifunctional crosslinker to form an insoluble gel network. In one example, the pendent reactive functional groups include maleic anhydride functional groups, maleimide functional groups, alcohol functional groups, epoxy functional groups, or combinations thereof. Examples of polymers including maleic anhydride functional groups include styrene maleic anhydride (SMA) copolymers. Examples of polymers including maleimide functional groups include polymaleimides and derivatives thereof, such as poly(meth)acrylates having pendent maleimide groups (e.g., poly(3-maleimidopropyl methacrylate)). An example of a polymer including alcohol functional groups is polyvinyl alcohol. An example of a polymer including epoxy functional groups is poly(glycidyl methacrylate).

[0022] In some examples, the pendent reactive functional groups can be present in the repeat units of the polymer. In these examples, the polymer has multiple pendent reactive functional groups, and these groups can each be the same type of functional group (e.g., each can be an alcohol functional group).

[0023] The amount of polymer included in the anti-coalescing polymer solution can depend, in part, on the polarity of the polymer (i.e., polar or non-polar), the structure of the polymer (i.e., linear, branched, etc.), and / or the jetting technology to be used to dispense the anti-coalescing polymer solution. For example, when using a piezoelectric inkjet printhead, a greater amount of polymer can be included in the anti-coalescing polymer solution than when using a thermal inkjet printhead. As another example, when the polymer is branched, a greater amount of polymer can be included in the anti-coalescing polymer solution than when the polymer is linear. This can be because solutions including branched polymer structures have a lower solution viscosity (as compared to the solution viscosity of solutions including linear polymer structures) due to the smaller hydrodynamic radius (as compared to linear polymers, branched polymers). The lower solution viscosity can correspond to better jetting performance (e.g., better decap performance as compared to decap performance at a higher solution viscosity).

[0024] In one example, the polymer is included in the anti-coalescing polymer solution in an amount of about 2 wt% to about 30 wt% based on the total weight of the anti-coalescing polymer solution. In this example, the anti-coalescing polymer solution can be dispensed using a piezoelectric inkjet printhead. In another example, the polymer is included in the anti-coalescing polymer solution in an amount of about 2 wt% to about 20 wt% or in an amount of about 2 wt% to about 15 wt% based on the total weight of the anti-coalescing polymer solution. In this example, the polymer can be polar and branched, and the anti-coalescing polymer solution can be dispensed using a thermal inkjet printhead. In yet another example, the polymer is included in the anti-coalescing polymer solution in an amount of about 2 wt% to about 10 wt% based on the total weight of the anti-coalescing polymer solution. In this example, the polymer can be polar and linear, and the anti-coalescing polymer solution can be dispensed using a thermal inkjet printhead. In still another example, the polymer is included in the anti-coalescing polymer solution in an amount of about 3 wt% to about 10 wt% based on the total weight of the anti-coalescing polymer solution.

[0025] The multifunctional crosslinker can be any multifunctional crosslinker capable of crosslinking the pendant reactive functional group(s) of the polymer to form an insoluble gel network. The multifunctional crosslinker also includes internal functional groups (e.g., disulfide bonds, boronate-alcohol bonds) that are degradable as needed (e.g., upon exposure to a degrading agent solution). In one example, the multifunctional crosslinker is selected from the group consisting of diamines, dithiols, diacyl chlorides, tetraborates, di-nucleophiles, and combinations thereof. Examples of diamines include cystamine dihydrochloride (which also includes an internal disulfide functional group). Examples of dithiols include hexa(ethylene glycol) dithiol. Examples of diacyl chlorides include adipoyl dichloride. An example of a tetraborate is sodium tetraborate. An example of a di-nucleophile includes adiponitrile.

[0026] In one example, the multifunctional crosslinking agent is included in the anti-coalescing crosslinking agent solution in an amount of about 1 wt% to about 15 wt% based on the total weight of the anti-coalescing crosslinking agent solution. In another example, the multifunctional crosslinking agent is included in the anti-coalescing crosslinking agent solution in an amount of about 3 wt% to about 10 wt% based on the total weight of the anti-coalescing crosslinking agent solution.

[0027] As examples, the pendant reactive functional groups of the polymer include maleic anhydride functional groups and the multifunctional crosslinking agent is a diamine; or the pendant reactive functional groups of the polymer include maleimide functional groups and the multifunctional crosslinking agent is a dithiol; or the pendant reactive functional groups of the polymer include alcohol functional groups and the multifunctional crosslinking agent is a diacyl chloride or a tetraborate; or the pendant reactive functional groups of the polymer include epoxy functional groups and the multifunctional crosslinking agent is a difunctional nucleophile. In one specific example, the polymer is polyvinyl alcohol and the multifunctional crosslinking agent is sodium tetraborate.

[0028] As described above, the pendant reactive functional groups react with the multifunctional crosslinking agent to form an insoluble gel network. The insoluble gel network allows the build material in the removable build material portion to remain physically separated from the layers of the final 3D object. The insoluble gel network forms a physical barrier between the polymer build material or polymer composite build material in the removable build material portion and the polymer build material or polymer composite build material in the portion to form a part of the final 3D object.

[0029] The insoluble gel network can have an insolubility, crosslinking density, and / or viscosity that allows the insoluble gel network to form a physical barrier between the build material in the removable build material portion and the build material in the portion to form a part of the final 3D object. As described above, the insoluble gel network is insoluble in water, organic solvents, and the like. The crosslinking density of the insoluble gel network can provide the gel with sufficient mechanical integrity to remain intact until exposed to a degradation agent solution (i.e., the insoluble gel network does not disintegrate during printing or removal from the build area platform). The crosslinking density can depend, in part, on the polymer and the multifunctional crosslinking agent used to form the insoluble gel network. In one example, the insoluble gel network has a crosslinking density of about 1 wt% to about 50 wt% based on the weight of the polymer. The insoluble gel network can also have a viscosity of about 50,000 cP to about 300,000 cP at room temperature (e.g., a temperature of about 18 °C to about 25 °C).

[0030] The anti-coalescing polymer solution and the anti-coalescing crosslinking agent solution can each include a carrier. In one example, the anti-coalescing polymer solution consists of the polymer and the carrier, without any other components. In another example, the anti-coalescing crosslinking agent solution consists of the multifunctional crosslinking agent and the carrier, without any other components.

[0031] As used herein, "carrier" can refer to a liquid in which a polymer is dissolved to form an anti- agglomerated polymer solution, or a liquid in which a multifunctional crosslinker is dissolved to form an anti-agglomerated crosslinker solution. It is to be understood that although one carrier is described herein, the anti-agglomerated polymer solution and the anti-agglomerated crosslinker solution are separate solutions (until combined to form a gel network) each having its own carrier. The term "anti-agglomerated solution" can refer to either an anti-agglomerated polymer solution or an anti-agglomerated crosslinker solution. Further, the composition of the carrier included in the anti-agglomerated polymer solution can be the same as or different from the composition of the carrier included in the anti-agglomerated crosslinker solution.

[0032] In some examples, the carrier includes water, a co-solvent, a surfactant, a wetting agent, or a combination thereof. In these examples, the carrier can include additional components such as an anti-coking agent(s), an anti-microbial agent(s), and / or a chelating agent(s), each of which are described below with reference to the fusing agent. In other examples, the carrier consists of water, a co-solvent, a surfactant, a wetting agent, or a combination thereof, without any additional components.

[0033] Water can make up the balance of the anti-agglomerated solution. As such, the amount of water can vary depending on the amount of other components included. As one example, deionized water can be used.

[0034] The carrier can also include co-solvent(s). In one example, the total amount of co-solvent(s) present in the anti-agglomerated solution is from about 10 wt.% to about 20 wt.% based on the total weight of the anti-agglomerated solution.

[0035] Classes of organic co-solvents that can be used in the carrier include aliphatic alcohols, aromatic alcohols, glycols, glycol ethers, polyglycol ethers, 2-pyrrolidone, caprolactam, formamide, acetamide, glycol, and long chain alcohols. Examples of these co-solvents include aliphatic primary alcohols, aliphatic secondary alcohols, 1,2-alcohols, 1,3-alcohols, 1,5-alcohols, 1,6-hexanediol or other glycols (e.g., 1,5-pentanediol, 2-methyl-1,3-propanediol, and the like), higher homologs of ethylene glycol alkyl ethers (C6-C 12 ), triethylene glycol, tetraethylene glycol, tripropylene glycol methyl ether, N-alkyl caprolactam, unsubstituted caprolactam, substituted and unsubstituted formamides, substituted and unsubstituted acetamides, and the like. Other examples of organic co-solvents include dimethyl sulfoxide (DMSO), isopropyl alcohol, ethanol, pentanol, acetone, and the like.

[0036] Other examples of suitable co-solvents include water soluble high boiling point solvents having a boiling point of at least 120 °C or more. Some examples of high boiling point solvents include 2-pyrrolidone (i.e., 2-pyrrolidone, boiling point of approximately 245 °C), 1 -methyl-2-pyrrolidone (boiling point of approximately 203 °C), N-(2-hydroxyethyl)-2-pyrrolidone (boiling point of approximately 140 °C), 2-methyl-1,3-propanediol (boiling point of approximately 212 °C), and combinations thereof.

[0037] The co-solvent(s) of the carrier can depend in part on the jetting technology to be used to dispense the anti-coalescence solution. For example, if a thermal inkjet printhead is to be used, water and / or ethanol and / or other longer chain alcohols (e.g., pentanol) can make up 35% or more by weight of the anti-coalescence solution. For another example, if a piezoelectric inkjet printhead is to be used, water can make up from about 25% to about 30% by weight of the anti-coalescence solution, and 35% or more by weight of the anti-coalescence solution can be ethanol, isopropanol, acetone, and the like.

[0038] The carrier can include a surface active agent(s) to improve the jetability of the anti-coalescence solution. In one example, the total amount of the surface active agent(s) present in the anti-coalescence solution is from about 0.25% to about 3% by weight based on the total weight of the anti-coalescence solution.

[0039] In one example, the carrier includes a blend of surface active agents. The blend can include a non-ionic surface active agent(s) and an anionic surface active agent(s). As one example, the blend includes three different non-ionic surface active agents and one anionic surface active agent. For example, the surface active agents include a first non-ionic surface active agent having a first hydrophilic chain length; a second non-ionic surface active agent having a second hydrophilic chain length that is different than the first hydrophilic chain length; a third non-ionic surface active agent, wherein the third non-ionic surface active agent is selected from a polyether siloxane and an alkoxylated alcohol; and an anionic surface active agent. More particularly, the first non-ionic surface active agent can be TERGITOL TM TMN-6 (available from The Dow Chemical Company), the second non-ionic surface active agent can be TERGITOL TM 15-S-30 (which has a higher HLB value and a longer hydrophilic chain length than TERGITOL TM TMN-6), the third non-ionic surface active agent is a polyether siloxane (e.g., DYNASYL® Wet 270 or DYNASYL® Wet 280, available from Evonik), or an alkoxylated alcohol (e.g., DYNOL® 250, available from Evonik). DYNASYL® Wet 280, available from Evonik), or an alkoxylated alcohol (e.g., DYNOL® 250, available from Evonik). Wet 510), and the anionic surfactant can be an alkyl diphenyloxide disulfonate (e.g., the DOWFAX TM series, such as 2A1, 3B2, 8390, C6L, C10L, and 30599). The first nonionic surfactant and the second nonionic surfactant can also be selected from the Igepal® series (available from Rhodia), the Pluronic® series (available from BASF Corp.), TRITON TM the Surfonic® series (available from The Dow Chemical Company), ECOSURF TM the Surfonic® EH series (available from The Dow Chemical Company), and ECOSURF TM the Surfonic® SA series (available from The Dow Chemical Company), so long as the two nonionic surfactants have different hydrophilic chain lengths.

[0040] The balance of nonionic surfactants to anionic surfactants enables better stabilization of all components and balances the overall surface tension of the anti- coalescing solution. In some examples, the first nonionic surfactant can be present in an amount of about 0.1 wt% to about 1 wt%; the second nonionic surfactant can be present in an amount of about 0.1 wt% to about 1 wt%; the third nonionic surfactant can be present in an amount of about 0.1 wt% to about 1 wt%; and / or the anionic surfactant can be present in an amount of about 0.1 wt% to about 1 wt% (based on the total weight of the anti-coalescing solution).

[0041] In other examples, the nonionic surfactants of the surfactant blend can be replaced with other nonionic surfactants, such as self-emulsifiable nonionic wetting agents based on acetylenic diol chemistry (e.g., ZETES® SEF) from Air Products and Chemicals, Inc., and / or ethoxylated low foam wetting agents (e.g., ZETES® 465, 440, or CT-111), and / or ethoxylated wetting agents and molecular defoamers (e.g., ZETES® 420) from Air Products and Chemical Inc. Still other suitable nonionic surfactants include nonionic wetting agents and molecular defoamers (e.g., ZETES® 104E) or water-soluble nonionic surfactants (such as TERGITOL from The Dow Chemical Company) TM TMN-6, TERGITOL TM 15-S-7, TERGITOL TM 15-S-9 or TERGITOL TM 15-S-30 (a secondary alcohol ethoxylate)). Another suitable nonionic surfactant is an alkoxylated alcohol, such as those available from Evonik. Wet 510.

[0042] In other instances, the surfactant can be a fluorinated surfactant. As an example, a nonionic fluorinated surfactant (e.g., from EIdu Pont de Nemours and Company) can be used. Fluorinated surfactants, such as FS-35 (formerly known as ZONYL FSO).

[0043] The carrier may also contain one or more wetting agents. In one example, the total amount of one or more wetting agents present in the anti-agglomeration solution is approximately 3% to approximately 10% by weight based on the total weight of the anti-agglomeration solution. An example of a suitable wetting agent is... EG-1 (i.e., LEG-1, glycerol polyether-26, ethoxylated glycerol, available from Lipo Chemicals).

[0044] Now refer to Figure 1 and Figures 2A-2E Examples of three-dimensional (3D) printing methods 100 and 200 are depicted. Before or as part of executing methods 100 and 200, controller 54 (see, for example...) Figure 5 It can access the data stored in the data storage 56 (see example). Figure 5 The controller 54 can determine the number of layers of the polymer building material or polymer composite building material 16 to be formed, and the locations on which the anti-agglomeration polymer solution 28 and the anti-agglomeration crosslinking agent solution 30 from the applicator 24B and applicator 24C, respectively, are to be deposited on the respective layers.

[0045] like Figure 1As shown, one example of a three-dimensional (3D) printing method 100 includes: applying a polymeric building material or polymeric composite building material 16 (reference numeral 102); negatively patterning a portion 34' of the polymeric building material or polymeric composite building material 16 to define a removable building material portion 34 and a remaining building material portion, said negative patterning including: selectively applying an anti-agglomeration polymer solution 28 comprising a polymer having side-reactive functional groups; and selectively applying an anti-agglomeration crosslinking agent solution 30 comprising a multifunctional crosslinking agent; wherein the side-reactive functional groups react with the multifunctional crosslinking agent to form an insoluble gel network 38 (reference numeral 104) within the polymeric building material or polymeric composite building material 16 in the removable building material portion 34; and forming a layer 42 of a final 3D object 44 from at least a portion 32 of the remaining building material portion based on a 3D object model, wherein a portion 34' of the polymeric building material or polymeric composite building material 16 in the removable building material portion 34 remains physically separated from the layer 42 (reference numeral 106).

[0046] like Figure 1 At reference numeral 102 in the attached figure and Figure 2A and 2B As shown, methods 100 and 200 include applying a polymeric building material or a polymeric composite building material 16. Figure 2A and 2B In the examples shown, the printing system (e.g.) Figure 5 The printing system 10 shown can be used to apply build material 16. The printing system 10 may include a build area platform 12, a build material supplier 14 containing build material particles 16, and a build material distributor 18.

[0047] The build area platform 12 receives build material 16 from the build material supplier 14. The build area platform 12 can move in the direction indicated by arrow 20 (e.g., along the z-axis) to deliver build material 16 to the build area platform 12 or a previously formed layer 42. In one example, when delivering build material particles 16, the build area platform 12 can be programmed to advance sufficiently (e.g., downwards) so that the build material distributor 18 can push the build material particles 16 onto the build area platform 12 to form a substantially uniform layer 40 of build material 16 thereon. The build area platform 12 can also return to its original position, for example, when building a new part.

[0048] The build material supplier 14 can be a container, a bed, or another surface that positions the build material particles 16 between the build material distributor 18 and the build area platform 12.

[0049] The build material distributor 18 can move over the build material supply 14 and across the build area platform 12 in a direction as indicated by arrow 22 (e.g., along the y-axis) to spread a layer 40 of build material 16 over the build area platform 12. The build material distributor 18 can also return to a position adjacent to the build material supply 14 after spreading the build material particles 16. The build material distributor 18 can be a doctor blade (e.g., a squeegee), a roller, a combination of a roller and a doctor blade, and / or any other device capable of spreading the build material 16 over the build area platform 12. For example, the build material distributor 18 can be counter-rotating rollers. In some examples, the build material supply 14 or a portion of the build material supply 14 can translate with the build material distributor 18, thereby continuously delivering build material 16 to the material distributor 18, rather than being supplied from a single location at the side of the printing system 10 as depicted in Figure 2A FIG. 1.

[0050] As shown in Figure 2A FIG. 1, the build material supply 14 can supply build material particles 16 to a location in preparation for their spreading onto the build area platform 12. The build material distributor 18 can spread the supplied build material particles 16 onto the build area platform 12. The controller 54 can process control build material supply data and, in response, control the build material supply 14 to properly position the build material particles 16, and can process control spreader data and, in response, control the build material distributor 18 to spread the supplied build material particles 16 over the build area platform 12 to form a layer 40 of build material 16 thereon. As shown in Figure 2B FIG. 1, a build material layer 40 has been formed. The spacing of the build material 16 in Figure 2B FIG. 1, and Figures 2C-2E FIG. 1, and Figure 5 FIG. 1 is exaggerated and can not represent the actual spacing or voids within the build material layer 40. The exaggerated spacing is used to show, for example, the insoluble gel network 38 or other deposited liquid among the build material 16.

[0051] The layer 40 of polymer build material or polymer composite build material 16 has a substantially uniform thickness across the build area platform 12. In one example, the thickness of the build material layer 40 is about 100 μιη. In another example, the thickness of the build material layer 40 is about 30 μιη to about 300 μιη, although thinner or thicker layers can also be used. For example, the thickness of the build material layer 40 can be about 20 μιη to about 500 μιη, or about 50 μιη to about 80 μιη. For finer part definition, the layer thickness can be a minimum of about 2x (i.e., 2 times) the particle diameter (as shown in Figure 2B FIG. 1). In some examples, the layer thickness can be about 1.5x the particle diameter.

[0052] After the building material 16 is applied and before further processing, the building material layer 40 may be exposed to heat. Heating may be performed to preheat the building material particles 16, and the heating temperature may be below the melting or softening point of the polymer building material or polymer composite building material particles 16. Therefore, the selected temperature will depend on the polymer building material or polymer composite building material particles 16 used. As an example, the preheating temperature may be approximately 5°C to approximately 50°C lower than the melting or softening point of the polymer building material or polymer composite building material particles 16. In one example, the preheating temperature is approximately 50°C to approximately 250°C. In another example, the preheating temperature is approximately 150°C to approximately 170°C.

[0053] The preheating of layer 40 of build material particles 16 can be accomplished using any suitable heat source that exposes all polymer build material or polymer composite build material particles 16 on the build region platform 12 to heat. Examples of heat sources include thermal heating sources (e.g., heaters integrated into the build region platform 12, which may include sidewalls, not shown) or radiation sources 50, 50' (see example...). Figure 5 ).

[0054] like Figure 1 The attached figure at point 104 and Figure 2C As shown, methods 100 and 200 proceed by negatively patterning a portion 34' of the polymeric building material or polymeric composite building material 16 to define the removable building material portion 34 and the remaining building material portion. Once the anti-agglomeration polymer solution 28 and the anti-agglomeration crosslinking agent solution 30 are applied to the portion 34' of the building material 16, an insoluble gel network 38 is formed within the portion 34' of the building material 16, and this forms the removable building material portion 34. Thus, the removable building material portion 34 contains the insoluble gel network 38 and any building material particles 16 mixed therein.

[0055] The remaining build material portion includes any build material 16 that has not been negatively patterned using solutions 28 and 30. At least a portion 32 of the remaining build material portion is to form the final 3D object 44 (displayed in the image). Figure 5 Layer 42 (in the middle). In some instances, all remaining build material portions will form layer 42. In other instances, the remaining build material portions may also include another portion 36 (also referred to herein as a third portion), which does not form layer 42 of the final 3D object 44. In some instances, the third portion 36 may be unpatterned (i.e., may not have liquid applied to it).

[0056] In one example, the removable build material portion 34 is at least partially adjacent to the at least a portion of the remaining build material portion 32. In another example, the removable build material portion 34 includes i) a portion of the build material 16 surrounding the at least a portion of the remaining build material portion 32, ii) a feature, such as a hole, a notch, a cutout, or other area where the build material 16 should not be fused, or iii) a combination thereof.

[0057] One example of this situation is shown in Figure 3 , a top view of the build material 16 on the build area platform 12. In the example shown in this figure, the shape of the layer of the final 3D object to be formed is a cube or rectangular prism, and the cross-sectional pattern parallel to the surface of the build area platform 12 is a square or rectangle with an edge boundary 33. The build material 16 within the edge boundary 33 is the at least a portion of the remaining build material portion 32 of the layer 42 of the final 3D object 44 to be formed. The build material 16 outside of the edge boundary 33 is the removable build material portion 34. Figure 3 In the example shown in Figure 3 , the at least a portion of the remaining build material portion 32 has the fusing agent 26 applied to it. The build material 16 located along the outside of the edge boundary 33 is the build material 16 within the removable build material portion 34, and thus is within the insoluble gel network 38. The build material 16 located outside of the removable build material portion 34 is the build material 16 within the third portion 36, and thus can be unpatterned, or can have the detailing agent 52 applied to it (see, e.g., Figure 5 ). In the example shown in Figure 3 , the third portion 36 has the detailing agent 52 applied to it.

[0058] As shown in Figure 2C , the negative patterning includes the selective application of the anti-coalescing polymer solution 28 and the selective application of the anti-coalescing crosslinker solution 30. As shown in Figure 2CAs shown in FIG. 1, the anti-coalescing polymer solution 28 can be dispensed by the second applicator 24B and the anti-coalescing crosslinker solution 30 can be dispensed by the third applicator 24C. In one example, the anti-coalescing polymer solution 28 can be dispensed first onto the portion 34' of the build material 16 and the anti-coalescing crosslinker solution 30 can be dispensed subsequently onto the portion 34' of the build material 16. It can be desirable to dispense the anti-coalescing polymer solution 28 prior to the anti-coalescing crosslinker solution 30 so that the polymer penetrates the entire depth of the layer 40 before encountering the multifunctional crosslinker, thereby forming the insoluble gel network 38 throughout the entire depth of the layer 40. In another example, the anti-coalescing crosslinker solution 30 can be dispensed first onto the portion 34' of the build material 16 and the anti-coalescing polymer solution 28 can be dispensed subsequently onto the portion 34' of the build material 16. In yet another example, the solutions 28, 30 can be dispensed one after the other in back-to-back printing passes or in the same pass. In all of these examples, the subsequently applied solution 28 or 30 (i.e., the second applied solution) can be applied before the previously applied solution 28 or 30 (i.e., the first applied solution) dries, thereby not slowing the reaction and thereby forming the insoluble gel network 38 throughout the entire depth of the layer 40.

[0059] The applicators 24B and / or 24C can each be thermal inkjet printheads, piezoelectric printheads, continuous inkjet printheads, and the like, and selectively applying the anti-coalescing polymer solution 28 and selectively applying the anti-coalescing crosslinker solution 30 can each be achieved by thermal inkjet printing, piezoelectric inkjet printing, continuous inkjet printing, and the like. The anti-coalescing polymer solution 28 and the anti-coalescing crosslinker solution 30 can each be contained in and dispensed by different printheads. This separation prevents the pendant group(s) from prematurely reacting with the crosslinker and avoids the risk of gelation occurring at the orifice plate of the applicator(s) 24B, 24C, which would otherwise occur if dispensed by a single applicator and which can adversely affect the ability of the applicator to dispense liquids. In one example of the methods 100, 200, the anti-coalescing polymer solution 28 and the anti-coalescing crosslinker solution 30 are each selectively applied via thermal inkjet printing, and the anti-coalescing polymer solution 28 and the anti-coalescing crosslinker solution 30 each comprise a carrier comprising: water; a co-solvent; a surfactant; and a wetting agent.

[0060] The controller 54 can process the data and, in response, control the second applicator 24B (e.g., in the direction indicated by arrow 38) to deposit the anti-coalescence polymer solution 28 and the third applicator 24C (e.g., in the direction indicated by arrow 38) to deposit the anti-coalescence crosslinker solution 30, thereby defining the removable build material portion 34 and the remaining build material portion. As described above, the removable build material portion 34 includes the insoluble gel network 38 (formed from the polymer and the multifunctional crosslinker) and the build material 16 in the insoluble gel network 38. The second applicator 24B can be programmed to receive instructions from the controller 54 and deposit the anti-coalescence polymer solution 28 according to the cross-sectional pattern of the removable build material portion 34, and the third applicator 24C can be programmed to receive instructions from the controller 54 and deposit the anti-coalescence crosslinker solution 30 according to the cross-sectional pattern of the removable build material portion 34. In Figure 2C the example shown in FIG. 6, the second applicator 24B and the third applicator 24C selectively apply the anti-coalescence polymer solution 28 and the anti-coalescence crosslinker solution 30, respectively, to the build material 16 that is to become part of the removable build material portion 34. In Figure 2C the example shown in FIG. 7, the anti-coalescence polymer solution 28 and the anti-coalescence crosslinker solution 30 are deposited on a portion 34' of the build material 16, but not on at least a portion 32 or a third portion 36 of the remaining build material portion.

[0061] When the anti-coalescence polymer solution 28 and the anti-coalescence crosslinker solution 30 are selectively applied, the polymer (present in the anti-coalescence polymer solution 28) and the multifunctional crosslinker (present in the anti-coalescence crosslinker solution 30) react to form the insoluble gel network 38 in the build material 16 in the removable build material portion 34. The respective volumes of the anti-coalescence polymer solution 28 and the anti-coalescence crosslinker solution 30 applied per unit of build material 16 can be sufficient to achieve the insoluble gel network 38 that is capable of keeping the build material 16 in the removable build material portion 34 physically separated from the fused layer 42.

[0062] In one example, the volume of the anti-coalescing polymer solution 28 and the volume of the anti-coalescing crosslinker solution 30 can establish a desired crosslinking density (e.g., a crosslinking density of about 1 wt% to about 50 wt% based on the weight of the polymer) of the insoluble gel network 38, and thereby a desired mechanical integrity (e.g., a mechanical integrity that enables the insoluble gel network 38 to remain intact until exposure to a degrading agent solution) of the insoluble gel network 38. For example, if the desired crosslinking density is 50 wt%, the anti-coalescing polymer solution 28 and the anti-coalescing crosslinker solution 30 can be applied such that the weight ratio of the multi-functional crosslinker to the polymer is 1 :2. The volume of each of the anti-coalescing polymer solution 28 and the anti-coalescing crosslinker solution 30 applied per unit of build material 16 can thus depend in part on the desired crosslinking density, the amount of polymer included in the anti-coalescing polymer solution 28, and / or the amount of multi-functional crosslinker included in the anti-coalescing crosslinker solution 30.

[0063] As shown by reference number 106, the methods 100, 200 continue by forming a layer 42 of the final 3D object 44 from at least a portion of the remaining build material 32. The formation of the layer 42 can be based on a 3D object model of the final 3D object 44.

[0064] In one example of the method 100, the formation of the layer 42 involves selective laser sintering of at least a portion of the remaining build material 32 based on the 3D object model. In these examples, a laser beam is used to selectively apply radiation to at least a portion of the remaining build material 32. The laser beam can be applied with the radiation source 50.

[0065] When the formation of the layer 42 involves selective laser sintering (SLS), the removable build material portion 34 is first negatively patterned, and then an energy beam is selectively applied to at least a portion of the remaining build material portion 32.

[0066] In SLS, the energy beam can be supplied by the source 50, which can be a tightly focused energy source such as a laser, electron beam, or microwave tip emitter.

[0067] The controller 54 can process the data and, in response, control the radiation source 50 (e.g., in the direction indicated by arrow 58 and / or in a direction along the X-axis) to apply radiation to at least a portion of the remaining build material portion 32 that is to become part of the final 3D object 44. The source 50 can be connected to a scanning system that allows the source 50 to be moved to a desired location in order to selectively apply the energy beam to at least a portion of the remaining build material portion 32 where it is desired to form the layer 42. In one example, the tightly focused energy source 50 and the scanning system can be connected to a moving XY stage or translation carriage 60 (see, e.g.,Figure 5 ), which moves in proximity to the energy source 50 and a scanning system of the layer 40, thereby directing the energy beam in the desired area(s). Depending in part on the size of the energy source 50 and the area of the build material 16 (i.e., a portion 32) to be fused, the tightly focused energy source 50 can have to be moved to generate the layer 42. For example, the source 50 can be programmed to receive instructions from the controller 54 and apply radiation according to a cross-sectional pattern of the layer 42 of the final 3D object 44 to be formed. The scanning system can move the source 50 to the appropriate position relative to a portion 32 of the remaining build material to generate the layer 42. In other examples, the tightly focused energy source 50 and the scanning system can be fixed, while a support member (similar to the build area platform 12) is configured to move relative thereto.

[0068] The amount of energy applied per unit of build material 16 and / or the exposure time in at least a portion 32 of the remaining build material can be sufficient to cause the build material 16 in the portion 32 to fuse. The amount of energy applied per unit of build material 16 and / or the exposure time can depend at least in part on the radiation source 50 used, the energy of the radiation applied, the wavelength of the radiation applied, and the build material 16 used.

[0069] The build material 16 exposed to the energy from the tightly focused energy source 50 fuses. The selective application of energy heats the polymer build material or polymer composite build material particles 16. In one example, the selective application of radiation raises the temperature of the polymer build material or polymer composite build material particles 16 in the layer 40 sufficiently above the melting or softening point of the particles 16 such that fusion (e.g., coalescence, melting, bonding, etc.) of the polymer build material or polymer composite build material particles 16 is able to occur. The selective application of radiation forms the fused layer 42.

[0070] In another example of the methods 100, 200, the formation of the layer 42 involves: selectively applying a fusing agent 26 on at least a portion 32 of the remaining build material based on the 3D object model; and exposing the polymer build material or polymer composite build material 16 to radiation to fuse at least a portion 32 of the remaining build material. The fusing agent 26 includes a radiation absorber. The composition of the fusing agent 26 will be described in greater detail below.

[0071] As Figure 2DAs shown in, the fusing agent 26 can be dispensed by the first applicator 24A (which can be similar to the applicators 24B, 24C) to pattern at least a portion 32 of the remaining build material portion. In one example, the removable build material portion 34 can be first negatively patterned, and then at least a portion 32 of the remaining build material portion can be patterned. In another example, at least a portion 32 of the remaining build material portion can be first patterned, and then the removable build material portion 34 can be negatively patterned. In yet another example, at least a portion 32 of the remaining build material portion can be patterned and the removable build material portion 34 can be negatively patterned at least substantially simultaneously (e.g., simultaneously). In all of these examples, the removable build material portion 34 is negatively patterned prior to exposing the build material 16 to radiation.

[0072] The controller 54 can process the data and, in response, control the first applicator 24A (e.g., in the direction indicated by arrow 58) to deposit the fusing agent 26 onto at least a portion 32 of the remaining build material portion that is to become part of the final 3D object 44. The first applicator 24A can be programmed to receive instructions from the controller 54 and deposit the fusing agent 26 according to the cross-sectional pattern of the layer 42 of the final 3D object 44 to be formed. In Figure 2D In the example shown in, the first applicator 24A selectively applies the fusing agent 26 on at least a portion 32 of the remaining build material portion of the layer 40 that is to become the first layer 42 of the final 3D object 44. In Figure 2D In the example shown in, the fusing agent 26 is deposited on at least a portion 32 of the remaining build material portion of the layer 40 without being on the removable build material portion 34 or the third portion 36.

[0073] As described above, the fusing agent 26 includes a radiation absorber. The volume of fusing agent 26 applied per unit of build material 16 in at least a portion 32 of the remaining build material portion can be sufficient to absorb and convert enough radiation to fuse the build material 16 in the patterned portion 32. The volume of fusing agent 26 applied per unit of build material 16 can depend at least in part on the radiation absorber used, the radiation absorber loading in the fusing agent 26, and the build material 16 used.

[0074] After the fusing agent 26 is selectively applied, the build material 16 is exposed to radiation to fuse at least a portion 32 of the remaining build material portion. The radiation can be applied with the radiation source 50, 50'.

[0075] The fusing agent 26 enhances absorption of the radiation, converts the absorbed radiation into heat energy, and facilitates transfer of the heat to the polymer build material or polymer composite build material particles 16 in contact therewith. In one example, the fusing agent 26 sufficiently raises the temperature of the build material particles 16 in the layer 40 above the melting or softening point of the particles 16 such that fusion (e.g., coalescence, melting, bonding, etc.) of the polymer build material or polymer composite build material particles 16 is able to occur. The application of the radiation forms a fused layer 42, shown in Figure 2E

[0076] Whether using an energy beam (e.g., SLS) or using a combination of the fusing agent 26 and the applied radiation, it is to be understood that the build material 16 in the removable build material portion 34 does not fuse or semi-fuse to the layer 42. As shown in Figure 2E

[0077] In some examples, the build material 16 in the removable build material portion 34 reaches a temperature at or above the melting temperature of the polymer build material or polymer composite build material 16. In these examples, the insoluble gel network 38 still maintains separation between the build material 16 in the removable build material portion 34 and the fused layer 42. As described above, if the build material 16 in the removable build material portion 34 fuses or semi-fuses, the build material particles 16 in the insoluble gel network 38 fuse or semi-fuse with other build material particles 16 in the insoluble gel network 38, but not with build material particles 16 outside of the insoluble gel network 38 or outside of the removable build material portion 34. Thus, the insoluble gel network 38 forms a physical barrier between the layer 42 and the build material particles 16 in the removable build material portion 34.

[0078] ​​In addition, the insoluble gel network 38 can withstand temperatures to which the removable build material portion 34 and, thus, the insoluble gel network 38 can be exposed (i.e., at temperatures at which the insoluble gel network 38 does not degrade) (e.g., temperatures at or above the melting temperature of the polymeric build material or polymeric composite build material 16). In addition, the cross-linking density of the insoluble gel network 38 can be sufficiently high such that if any gas that is expelled from the liquid (e.g., from the carrier(s) of the solution 28, 30) becomes trapped in pockets of the insoluble gel network 38, the insoluble gel network 38 does not swell.

[0079] In some examples, the methods 100, 200 further include repeating the applying, the negative patterning, and the forming of the polymeric build material or polymeric composite build material 16, wherein the repeating forms i) a final 3D object 44 that includes the layer 42, and ii) a removable object 46 in contact with at least a portion of the final 3D object 44 (see, e.g., FIG. 2B) that includes the removable build material portion 34; and exposing the removable object 46 to a degrading agent solution to degrade the insoluble gel network 38. Figure 5

[0080] In these examples, a three-dimensional (3D) printed article 48 can be formed (see, e.g., FIG. 2C). Figure 5 In one example, the three-dimensional (3D) printed article 48 includes: a fused polymeric or polymeric composite material object 44; and a removable object 46 in contact with at least a portion of the fused polymeric or polymeric composite material object 44, the removable object 46 including: an insoluble gel network 38; and polymeric build material or polymeric composite build material particles 16 intermingled with the insoluble gel network 38.

[0081] In one example, the removable object 46 at least partially surrounds the final 3D object 44. In another example, the final 3D object 44 at least partially surrounds the removable object 46 (e.g., once removed, the removable object 46 will form a notch, a hole, etc. in the final 3D object 44).

[0082] The removable object 46 can be removed from the final 3D object 44 using a degrading agent solution. The degrading agent solution can be any solution that is capable of degrading the cross-linking between the polymer and the multifunctional cross-linking agent without degrading (e.g., breaking, marking, etc.) the final 3D object 44. In one example, the insoluble gel network 38 of the removable object 46 can be removed in a degrading agent solution selected from the group consisting of a strong acid solution, a weak acid solution, a reducing solution, and combinations thereof.

[0083] As an example, the degrading agent solution is selected from the group consisting of a strong acid solution, a weak acid solution, a reducing solution, and combinations thereof. Examples of strong acid solutions have a pK a ​(pKa) values. Specific examples of strong acid solutions include hydrochloric acid solutions (pK a values of -7), nitric acid solutions (pK a values of -1.3), hydrobromic acid solutions (pK a values of -9), perchloric acid solutions (pK a values of -1.6), and hydroiodic acid solutions (pK a values of -10). Examples of strong acid solutions do not include sulfuric acid solutions. Examples of weak acid solutions have pK a (pKa) values of about 0 to about 14. Specific examples of weak acid solutions include ascorbic acid solutions (first pK a value of 4.17), carbonic acid solutions (pK a value of 6.35), phosphoric acid solutions (first pK a value of 2.15), hydrofluoric acid solutions (pK a value of 3.17), and acetic acid solutions (pK a value of 4.75). Examples of weak acid solutions do not include formic acid solutions or boric acid solutions. Examples of reducing solutions include reducing agents such as sodium borohydride, tocopherol (vitamin E), phenolic compounds, and glucose.

[0084] In one example (e.g., when the degrading agent solution includes a strong acid solution or a weak acid solution), the degrading agent solution has a potential hydrogen (pH) value of about 3 to about 6. The concentration of the acid (e.g., strong acid or weak acid) in the degrading agent solution can depend, in part, on the pK a value of the acid and / or the desired pH value. As one example, a desired pH of 3 can be achieved in a 1 mM concentration of a hydrochloric acid solution (pK a value of -7). As another example, a desired pH of 3 can be achieved in a 14.8 mM concentration of an ascorbic acid solution (first pK a value of 4.17).

[0085] In one example, the removable object 46 can be exposed to the degrading agent solution by spraying the removable object 46 with the degrading agent solution using a tool, a hose and a sprayer, a spray gun, or the like. In other examples, exposing the removable object 46 to the degrading agent solution can include ultrasonically treating the removable object 46 in a bath of the degrading agent solution, or soaking the removable object 46 in the degrading agent solution.

[0086] When the removable object 46 is exposed to the degrading agent solution, the insoluble gel network 38 degrades, which releases the build material particles 16 that were in the insoluble gel network 38. The degradation of the insoluble gel network 38 disassembles the removable object, leaving the build material particles 16. The final 3D object 46 can be removed from and / or the build material particles 16 can be removed from the final 3D object 46. In some examples, the released build material particles 16 can be collected and used to print another 3D object.

[0087] Several variations of the previously described methods 100, 200 will now be described.

[0088] In some examples of the methods 100, 200, a detailing agent 52 can be used. In some examples, the detailing agent 52 can include a surfactant, a cosolvent, and water. The composition of the detailing agent 52 will be described in more detail below. The detailing agent 52 can be dispensed by another (e.g., fourth) applicator 24D (which can be similar to the applicators 24A, 24B, 24C) and applied to the portion(s) of build material 16.

[0089] The detailing agent 52 can provide an evaporative cooling effect to the build material 16 to which it is applied. The cooling effect of the detailing agent 52 reduces the temperature of the polymeric build material or polymeric composite build material 16 containing the detailing agent 52 during the energy / radiation exposure. The detailing agent 52 and its rapid cooling effect can be used to achieve different levels of fusion / bonding / adhesion within the layers 42 of the 3D object 44 being formed. Different levels of fusion / bonding / adhesion can be desirable to control the internal stress distribution, warping, mechanical strength performance, and / or elongation performance of the final 3D object 44.

[0090] In one example of using detailing agent 52 to obtain different levels of melting / fusing / bonding within layer 42, fusing agent 26 can be selectively applied according to the cross-sectional pattern of layer 42 of 3D object 44, and detailing agent 52 can be selectively applied within at least a portion of the cross-section. As such, some examples of methods 100, 200 further include selectively applying detailing agent 52 on at least a portion 32 of the remaining build material, wherein detailing agent 52 includes a surfactant, a co-solvent, and water. Evaporative cooling provided by detailing agent 52 can remove energy from at least a portion 32 of the remaining build material; however, fusing can not be completely prevented due to the presence of fusing agent 26 with detailing agent 52. Due to the evaporative cooling, the level of fusing can be altered, which can alter the internal stress distribution, warping, mechanical strength performance, and / or elongation performance of 3D object 44. It is to be understood that detailing agent 52 can be applied in any desirable pattern when applied within the same portion as fusing agent 26. When fusing agent 26 is used, detailing agent 52 can be applied before, after, or at least substantially simultaneously with (e.g., one after the other or simultaneously in a single printing pass) fusing agent 26, and then exposing build material 16 to radiation.

[0091] In another example of using detailing agent 52 to obtain different levels of melting / fusing / bonding within layer 42, detailing agent 52 can be applied on at least a portion 32 of the remaining build material where an energy beam is applied to selectively fuse at least a portion 32 of the remaining build material. When an energy beam is used, detailing agent 52 can be applied prior to selectively applying the energy beam.

[0092] In some examples, whether fusing agent 26 and radiation exposure or an energy beam is used to form layer 42, detailing agent 52 can likewise or alternatively be applied after fusing layer 42 to control thermal gradients within layer 42 and / or final 3D object 44. In these examples, the evaporative cooling provided by detailing agent 52 can be used to control the thermal gradients.

[0093] In another example utilizing the evaporative cooling effect of detailing agent 52, methods 100, 200 further include selectively applying detailing agent 52 on a third portion 36 of the polymeric build material or polymeric composite build material 16 to prevent the polymeric build material or polymeric composite build material 16 in third portion 36 from fusing, wherein third portion 36 does not include removable build material portion 34 or at least a portion 32 of the remaining build material, and detailing agent 52 includes a surfactant, a co-solvent, and water. The evaporative cooling provided by detailing agent 52 can remove energy from third portion 36, which can lower the temperature of build material 16 in third portion 36 and prevent build material 16 in third portion 36 from fusing.

[0094] The detailing agent 52 can also be used to improve wetting of the solutions 28, 30 on the build material 16. In this example, the methods 100, 200 further include selectively applying a detailing agent 52 on a portion 34' of the polymeric build material or polymeric composite build material 16 to at least partially facilitate the reaction of the pendant reactive functional groups with the polyfunctional crosslinking agent to form the insoluble gel network 38, where the detailing agent 52 includes a surfactant, a cosolvent, and water. The detailing agent 52 can at least partially facilitate the penetration of the polymer (in the anti-coalescing polymer solution 28) into the interstitial spaces between the build material particles 16 and / or wetting of the polymer on the build material particles 16. Similarly, the detailing agent 52 can at least partially facilitate the penetration of the polyfunctional crosslinking agent (in the anti-coalescing crosslinking agent solution 30) into the interstitial spaces between the build material particles 16 and / or wetting of the polymer on the build material particles 16. The detailing agent 52 and the anti-coalescing polymer solution 28 can be applied at least substantially simultaneously (e.g., one immediately after the other, or concurrently, in a single print pass) when the detailing agent 52 is applied on the portion 34' of the build material 16. The detailing agent 52 and the anti-coalescing crosslinking agent solution 30 can likewise or alternatively be applied at least substantially simultaneously (e.g., one immediately after the other, or concurrently, in a single print pass) when the detailing agent 52 is applied on the portion 34' of the build material 16.

[0095] Referring now to Figure 4 depicts another example of a three-dimensional (3D) printing method 300. As Figure 4As shown in FIG. 3, one example of a three-dimensional (3D) printing method 300 includes: applying a polymeric build material or a polymeric composite build material 16 (reference numeral 302); negative patterning a portion 34' of the polymeric build material or the polymeric composite build material 16 to define a removable build material portion 34, the negative patterning including: selectively applying an anti-coalescing polymer solution 28 including a polymer having a pendant reactive functional group; and selectively applying an anti-coalescing crosslinker solution 30 including a multifunctional crosslinker; wherein the pendant reactive functional group reacts with the multifunctional crosslinker to form an insoluble gel network 38 in the polymeric build material or the polymeric composite build material 16 in the removable build material portion 34 (reference numeral 304); selectively applying a fusing agent 26 on another portion of the polymeric build material or the polymeric composite build material 16 to define a portion 32 of the polymeric build material or the polymeric composite build material 16 that is to form a portion of a final 3D object 44, and wherein the removable build material portion 34 is at least partially adjacent to the portion 32 (reference numeral 306); exposing the polymeric build material or the polymeric composite build material 16 to radiation to fuse the polymeric build material or the polymeric composite build material 16 in the portion 32, thereby forming a layer 42 of the final 3D object 44, wherein the polymeric build material or the polymeric composite build material 16 in the removable build material portion 34 remains physically separated from the layer 42 (reference numeral 308); and repeating the applying, the negative patterning, the selective applying of the fusing agent 26, and the exposing, wherein the repeating forms the final 3D object 44 including the layer 42 and a removable object 46 in contact with at least a portion of the final 3D object 44, the removable object 46 including the removable build material portion 34 (reference numeral 310).

[0096] Referring now to Figure 5 , one example of a 3D printing system 10 is schematically depicted. It is to be understood that the 3D printing system 10 can include additional components (some of which are described herein) and that some of the components described herein can be removed and / or modified. Further, Figure 5 The components of the 3D printing system 10 depicted in FIG. 3 can not be drawn to scale, and as such, the 3D printing system 10 can have different dimensions and / or configurations than those shown herein.

[0097] In one example, a three-dimensional (3D) printing system 10 includes a supply 14 of a polymeric build material or a polymeric composite build material 16; a build material distributor 18; a supply of an anti-coalescing polymer solution 28 including a polymer having pendant reactive functional groups; an applicator 24B for selectively dispensing the anti-coalescing polymer solution 28; a supply of an anti-coalescing crosslinker solution 30 including a multifunctional crosslinker; an applicator 24C for selectively dispensing the anti-coalescing crosslinker solution 30; a radiation source 50, 50'; a controller 54; and a non-transitory computer readable medium having stored thereon computer executable instructions to enable the controller 54 to: utilize the build material distributor 18 to dispense the polymeric build material or polymeric composite build material 16; utilize the applicators 24B and 24C to selectively dispense the anti-coalescing polymer solution 28 and the anti-coalescing crosslinker solution 30, respectively, to thereby negative pattern a portion 34' of the polymeric build material or polymeric composite build material and define a removable build material portion 34 and a remaining build material portion, wherein the pendant reactive functional groups react with the multifunctional crosslinker to form an insoluble gel network 38 in the polymeric build material or polymeric composite build material 16 in the removable build material portion 34; and utilize the radiation source 50, 50' to form a layer 42 of a final 3D object 44 from at least a portion of the remaining build material portion 32, wherein the portion 34' of the polymeric build material or polymeric composite build material 16 in the removable build material portion 34 remains physically separated from the layer 42.

[0098] As shown in FIG. 1, the printing system 10 includes a build area platform 12, a build material supply 14 containing a build material 16, and a build material distributor 18. Figure 5 As shown in FIG. 1, the printing system 10 includes a build area platform 12, a build material supply 14 containing a build material 16, and a build material distributor 18.

[0099] As described above, the build area platform 12 receives the build material 16 from the build material supply 14. The build area platform 12 can be integrated with the printing system 10 or can be a component that is separately inserted into the printing system 10. For example, the build area platform 12 can be a module that is available independently of the printing system 10. The build material platform 12 shown is one example and can be replaced with another support member such as a platen, a manufacturing / print bed, a glass plate, or another build surface.

[0100] As also noted above, the build material supply 14 can be a container, a bed, or other surface that positions the build material 16 between the build material distributor 18 and the build area platform 12. In some examples, the build material supply 14 can include a surface on which build material 16 can be supplied, e.g., by a build material source (not shown) located above the build material supply 14. Examples of build material sources can include a hopper, an auger, and the like. Additionally or alternatively, the build material supply 14 can include a mechanism, e.g., a delivery piston, to provide, e.g., move, build material 16 from a storage location to a location to be spread onto the build area platform 12 or a previously formed layer 42 of the final 3D object 44.

[0101] As also noted above, the build material distributor 18 can be a doctor blade, e.g., a squeegee, a roller, a combination of a roller and a doctor blade, and / or any other device capable of spreading the build material 16 on the build area platform 12, e.g., counter-rotating rollers.

[0102] As shown in FIG. 1, the print system 10 includes a first applicator 24A that can contain a fusing agent 26 and a second applicator 24B that can contain an anti-coalescence polymer solution 28. As also shown in FIG. 1, the print system 10 includes a third applicator 24C that can contain an anti-coalescence cross-linker solution 30 and a fourth applicator 24D that can contain a detailing agent 52. Figure 5 As also noted above, the print system 10 can also include a first applicator 24A that can contain a fusing agent 26 and a fourth applicator 24D that can contain a detailing agent 52. Figure 5

[0103] The applicators 24A, 24B, 24C, 24D can be scanned across the build area platform 12 in the direction indicated by arrow 58, e.g., along the y-axis. The applicators 24A, 24B, 24C, 24D can be, e.g., thermal inkjet printheads, piezoelectric printheads, continuous inkjet printheads, and the like, and can extend across the width of the build area platform 12. Although four applicators 24A, 24B, 24C, 24D are shown in FIG. 1, the print system 10 can include more or fewer applicators 24A, 24B, 24C, 24D. Figure 5 ​Each of applicators 24A, 24B, 24C, 24D is shown as a single applicator, it being understood that each of applicators 24A, 24B, 24C, 24D can include multiple applicators spanning the width of build area platform 12. Further, applicators 24A, 24B, 24C, 24D can be positioned in multiple print bars. Applicators 24A, 24B, 24C, 24D can also be scanned along the x-axis, for example in configurations in which applicators 24A, 24B, 24C, 24D do not span the width of build area platform 12 to enable applicators 24A, 24B, 24C, 24D to deposit respective liquids 26, 28, 30, 52 over a large area of a layer 40 of build material particles 16, respectively. Applicators 24A, 24B, 24C, 24D can thereby be connected to a moving XY table or translation carriage 60 that moves applicators 24A, 24B, 24C, 24D adjacent to build area platform 12 in order to deposit respective liquids 26, 28, 30, 52 in respective regions 32, 34, 36 of a layer 40 of build material particles 16 that have been formed on build area platform 12 according to methods 100, 200, 300 disclosed herein. Applicators 24A, 24B, 24C, 24D can include multiple nozzles (not shown) through which respective liquids 26, 28, 30, 52 are ejected.

[0104] Applicators 24A, 24B, 24C, 24D can deliver droplets of respective liquids 26, 28, 30, 52 at a resolution of about 300 dots per inch (DPI) to about 1200 DPI. In other examples, applicators 24A, 24B, 24C, 24D can deliver droplets of respective liquids 26, 28, 30, 52 at a higher or lower resolution. Droplet velocity can be about 5 m / s to about 24 m / s, and firing frequency can be about 1 kHz to about 100 kHz. In one example, each droplet can be on the order of about 3 picoliters (pl) to about 18 pl, although it is contemplated that higher or lower droplet volumes can be used. In some examples, applicators 24A, 24B, 24C, 24D are capable of delivering variable size droplets of respective liquids 26, 28, 30, 52. One example of a suitable print head has a resolution of 600 DPI and can deliver droplet volumes of about 6 pl to about 14 pl.

[0105] The foregoing physical elements can each be operatively connected to a controller 54 of the printing system 10. The controller 54 can process print data based on a 3D object model of the final 3D object 44 to be generated. In response to the data processing, the controller 54 can control the operation of the build area platform 12, the build material supply 14, the build material distributor 18, and the applicators 24A, 24B, 24C, 24D. As one example, the controller 54 can control actuators (not shown) to control the various operations of the 3D printing system 10 components. The controller 54 can be a computing device, a semiconductor-based microprocessor, a central processing unit (CPU), an application-specific integrated circuit (ASIC), and / or another hardware device. Although not shown, the controller 54 can be connected to the 3D printing system 10 components via communication lines.

[0106] The controller 54 manipulates and transforms data, which can be represented as physical (electronic) quantities within the printer's registers and memories, in order to control the physical elements to generate the final 3D object 44. As such, the controller 54 is depicted in communication with a data store 56. The data store 56 can include data related to the final 3D object 44 to be printed by the 3D printing system 10. The data for selectively delivering the build material particles 16, the anti-coalescence polymer solution 28, the anti-coalescence crosslinker solution 30, and the like can be derived from a model of the final 3D object 44 to be formed. For example, the data can include locations on various layers of the build material particles 16 where the second applicator 24B is to deposit the anti-coalescence polymer solution 28 and the third applicator 24C is to deposit the anti-coalescence crosslinker solution 30. In one example, the controller 54 can use the data to control the second applicator 24B to selectively apply the anti-coalescence polymer solution 28. In another example, the controller 54 can use the data to control the third applicator 24C to selectively apply the anti-coalescence crosslinker solution 30. The data store 56 can also include machine-readable instructions (stored on a non-transitory computer-readable medium) that enable the controller 54 to control the amount of build material particles 16 supplied by the build material supply 14, the movement of the build area platform 12, the movement of the build material distributor 18, the movement of the applicators 24A, 24B, 24C, 24D, and the like.

[0107] As Figure 5As shown in the middle, the printing system 10 can also include a radiation source 50, 50'. In some examples, the radiation source 50' can be in a fixed position relative to the build material platform 12. The source 50' in a fixed position can be a conduction or radiant heater that is part of the printing system 10. These types of heaters can be placed below the build area platform 12 (e.g., conductive heating from below the platform 12) or can be placed above the build area platform 12 (e.g., radiant heating of the build material layer surface). In other examples, the radiation source 50 can be positioned to apply energy / radiation to the layer 40 of build material particles 16 immediately after the fusing agent 26 has been applied thereto. In Figure 5 In the example shown in the middle, the radiation source 50 is connected to the side of the applicator 24A, 24B, 24C, 24D, which enables patterning and heating / exposure to radiation in a single pass.

[0108] In still other examples (not shown), the radiation source 50 can be a laser or other tightly focused energy source that can selectively apply energy to the layer 40 as described previously for SLS. A laser can emit light based on stimulated emission of radiation through optical amplification. The laser can emit light coherently (i.e., constant phase difference and frequency), which enables the radiation to be emitted in the form of a laser beam that remains narrow and focused on a small area over long distances. In some examples, the laser or other tightly focused energy source can be a pulsed laser (i.e., light power occurs in pulses). The use of a pulsed laser allows energy to accumulate between pulses, which enables the light beam to have more energy. A single laser or multiple lasers can be used.

[0109] The radiation source 50, 50' can emit radiation having a wavelength of about 100 nm to about 1 mm. As one example, the radiation can be about 800 nm to about 2 μιη. As another example, the radiation can be black body radiation having a maximum intensity at a wavelength of about 1100 nm. The radiation source 50, 50' can be an infrared (IR) or near infrared light source, such as an IR or near IR curing lamp, an IR or near IR light emitting diode (LED), or a laser having a desired IR or near IR electromagnetic wavelength.

[0110] The radiation sources 50, 50' can be operatively connected to a lamp / laser driver, an input / output temperature controller, and temperature sensors, collectively shown as a radiation system assembly 62. The radiation system assembly 62 can operate together to control the radiation sources 50, 50'. A temperature profile (e.g., a radiation exposure rate) can be submitted to the input / output temperature controller. During heating, the temperature sensors can sense the temperature of the build material particles 16, and the temperature measurements can be transmitted to the input / output temperature controller. For example, thermocouples associated with the heating zones can provide temperature feedback. The input / output temperature controller can adjust the power set points of the radiation sources 50, 50' based on any differences between the profile and the real-time measurements. These power set points are sent to the lamp / laser driver, which transmits the appropriate lamp / laser voltage to the radiation sources 50, 50'. This is one example of a radiation system assembly 62, and it is understood that other radiation source control systems can be used. For example, the controller 54 can be configured to control the radiation sources 50, 50'.

[0111] In examples of the methods 100, 200, 300 and systems 10 disclosed herein, the build material particles 16 can be polymeric build material or polymeric composite build material. As used herein, the term "polymeric build material" can refer to crystalline or semi-crystalline polymeric particles. As used herein, the term "polymeric composite build material" can refer to composite particles composed of a polymer and a ceramic.

[0112] Examples of semi-crystalline polymers include semi-crystalline thermoplastics having a wide processing window (i.e., a temperature range between the melting point and the recrystallization temperature) of greater than 5°C. Some specific examples of semi-crystalline thermoplastics include polyamides (PA) (e.g., PA 11 / nylon 11, PA 12 / nylon 12, PA 6 / nylon 6, PA 8 / nylon 8, PA 9 / nylon 9, PA 66 / nylon 66, PA 612 / nylon 612, PA 812 / nylon 812, PA 912 / nylon 912, etc.). Other examples of crystalline or semi-crystalline polymers suitable for use as build material particles 16 include polyethylene, polypropylene, and polyoxymethylene (i.e., polyacetals). Still other examples of suitable build material particles 16 include polystyrene, polycarbonate, polyesters, polyurethanes, other engineering plastics, and blends of any two or more of the polymers listed herein.

[0113] Any of the previously recited crystalline or semi-crystalline polymer particles can be combined with ceramic particles to form polymer composite build material particles 16. Examples of suitable ceramic particles include metal oxides, inorganic glasses, carbides, nitrides, and borides. Some specific examples include aluminum oxide (AI2O3), glass, silicon mononitride (SiN), silicon dioxide (SiO2), zirconium oxide (ZrO2), titanium dioxide (TiO2), or combinations thereof. The amount of ceramic particles that can be combined with the crystalline or semi-crystalline polymer particles can depend on the materials used and the final 3D object to be formed. In one example, the ceramic particles can be present in an amount of about 1 wt% to about 40 wt% based on the total weight of the polymer composite build material particles 16.

[0114] In some examples, the polymer build material or polymer composite build material 16 can be in the form of a powder. In other examples, the build material 16 can be in the form of a powdered material that includes, for example, short fibers having a length that is greater than their width. In some examples, the powder can be formed from or can include short fibers that can have been cut to a short length from a long strand or wire of the material.

[0115] The polymer build material or polymer composite build material particles 16 can have a melting point or softening point of about 50 °C to about 400 °C. The melting point or softening point can be higher or lower depending on the composition of the composite material. As one example, the material particles 16 can be a polyamide having a melting point of about 180 °C.

[0116] The polymer build material or polymer composite build material particles 16 can be composed of similarly sized particles or differently sized particles. In the examples shown herein Figures 2A-2E and Figure 5 ), the build material 16 includes similarly sized particles. In one example, the build material particles 16 have an average particle size of about 2 μιη to about 200 μιη. In another example, the build material particles 16 have an average particle size of about 20 μιη to about 90 μιη. In yet another example, the build material particles 16 have an average particle size of about 60 μιη.

[0117] In some examples, the polymer build material or polymer composite build material 16 includes an antioxidant, a whitening agent, a charge agent, a flow aid, or combinations thereof, in addition to the polymer particles (and in some cases ceramic particles).

[0118] Antioxidant(s) can be added to the polymer build material or polymer composite build material 16 to prevent or slow the molecular weight drop of the build material 16 and / or can prevent or slow discoloration (e.g., yellowing) of the build material 16 by preventing or slowing oxidation of the build material 16. In some examples, the antioxidant can be a free radical scavenger. In these examples, the antioxidant can include 1098 (benzenepropanamide, N,N'-1,6-hexanediylbis(3,5-bis(1,1-dimethylethyl)-4- hydroxy)), 254 (a mixture of 40% triethylene glycol bis(3-tert-butyl-4-hydroxy-5- methylphenyl), polyvinyl alcohol, and deionized water), and / or other hindered phenols. In other examples, the antioxidant can include phosphites and / or organic sulfides (e.g., thioesters). In one example, the antioxidant can be included in the polymer build material or polymer composite build material 16 in an amount of about 0.01 wt% to about 5 wt% based on the total weight of the build material 16.

[0119] Whitening agent(s) can be added to the build material 16 to improve visibility. Examples of suitable whitening agents include titanium dioxide (Ti02), zinc oxide (ZnO), calcium carbonate (CaC03), zirconium dioxide (Zr02), aluminum oxide (AI2O3), silicon dioxide (Si02), and combinations thereof. In some examples, stilbene derivatives can be used as whitening agents. In these examples, the temperature of the 3D printing process can be below a threshold temperature above which the stilbene derivatives can become unstable. In one example, the whitening agent can be included in the polymer build material or polymer composite build material 16 in an amount of about 0.01 wt% to about 10 wt% based on the total weight of the polymer build material or polymer composite build material 16.

[0120] Charging agent(s) can be added to the build material 16 to suppress tribocharging. Examples of suitable charging agents include aliphatic amines (which can be ethoxylated), aliphatic amides, quaternary ammonium salts (e.g., behenyltrimethylammonium chloride or cocamidopropyl betaine), esters of phosphoric acid, polyethylene glycol esters, or polyols. Some suitable commercially available charging agents include FA 38 (natural-based ethoxylated alkylamines), FE2 (fatty acid esters), and HS 1 (alkane sulfonate salts), each of which can be obtained from Clariant Int. Ltd. In one example, the charging agent is added in an amount of greater than 0 wt% to less than 5 wt% based on the total weight of the polymer build material or polymer composite build material 16.

[0121] Flow aid(s) can be added to improve the coating flowability of the build material 16. Flow aids can be particularly beneficial when the particle size of the build material 16 is less than 25 microns. Flow aids improve the flowability of the polymeric build material or polymeric composite build material 16 by reducing friction, lateral drag, and frictional charge buildup (by increasing particle conductivity). Examples of suitable flow aids include tribasic calcium phosphate (E341), powdered cellulose (E460(ii)), magnesium stearate (E470b), sodium bicarbonate (E500), sodium ferrocyanide (E535), potassium ferrocyanide (E536), calcium ferrocyanide (E538), bone phosphate (E542), sodium silicate (E550), silicon dioxide (E551), calcium silicate (E552), magnesium trisilicate (E553a), talc (E553b), sodium aluminosilicate (E554), potassium aluminum silicate (E555), calcium aluminosilicate (E556), bentonite (E558), aluminum silicate (E559), stearic acid (E570), or polydimethylsiloxane (E900). In one example, the flow aid is added in an amount greater than 0 wt% to less than 5 wt% based on the total weight of the polymeric build material or polymeric composite build material 16.

[0122] Also in some examples of the methods 100, 200, 300 and systems 10 disclosed herein, and as described above, a fusing agent 26 can be used. An example of a fusing agent 26 is a dispersion comprising a radiation absorber (i.e., an active material). The active material can be any infrared light absorbing colorant. In one example, the active material is a near infrared light absorbing agent. Any near infrared colorant can be used in the fusing agent 26, such as those produced by Fabricolor, Eastman Kodak, or Yamamoto. As one example, the fusing agent 26 can be a print liquid formulation comprising carbon black as the active material. Examples of such print liquid formulations are commercially known as CM997A, 516458, C18928, C93848, C93808, and the like, which are all available from HP Inc. Other suitable active materials include near infrared absorbing dyes or plasmonic resonance absorbers.

[0123] As another example, the fusing agent 26 can be a print liquid formulation comprising a near infrared absorbing dye as the active material. Examples of such print liquid formulations are described in U.S. Patent No. 9,133,344, which is incorporated herein by reference in its entirety. Some examples of near infrared absorbing dyes are water-soluble near infrared absorbing dyes selected from the group consisting of:

[0124]

[0125]

[0126]

[0127]

[0128] and mixtures thereof. In the above formulations, M can be a divalent metal atom (e.g., copper, etc.), or if the metal is more than divalent (e.g., indium, etc.) can have OSO3Na axial groups filling any unfilled valence state, R can be any Ci-C8alkyl group (including substituted and unsubstituted alkyl groups), and Z can be a counterion such that the total charge of the near infrared absorbing dye is neutral. For example, the counterion can be sodium, lithium, potassium, NH4 + etc.

[0129] Further examples of near infrared absorbing dyes are hydrophobic near infrared absorbing dyes selected from the group consisting of:

[0130]

[0131]

[0132]

[0133] and mixtures thereof. For the hydrophobic near infrared absorbing dyes, M can be a divalent metal atom (e.g., copper, etc.), or if the metal is more than divalent can include metals with Cl, Br, or OR' (R' = H, CH3, COCH3, COCH2COOCH3, COCH2COCH3) axial groups filling any unfilled valence state, and R can be any Ci-C8alkyl group (including substituted and unsubstituted alkyl groups).

[0134] In other examples, the active material can be a plasmonic resonance absorber. The plasmonic resonance absorber allows the fusing agent 26 to absorb radiation having a wavelength of 800 nm to 4000 nm (e.g., at least 80% of the radiation having a wavelength of 800 nm to 4000 nm is absorbed), which enables the fusing agent 26 to convert enough radiation into heat energy to fuse the polymer build material or polymer composite build material particles 16. The plasmonic resonance absorber also enables the fusing agent 26 to have transparency at wavelengths of 400 nm to 780 nm (e.g., 20% or less of the radiation having a wavelength of 400 nm to 780 nm is absorbed), which enables the final 3D object 44 to be white or light in color.

[0135] The absorption of the plasmonic resonance absorber is a result of the plasmonic resonance effect. Electrons associated with the atoms of the plasmonic resonance absorber can be collectively excited by radiation, which results in collective oscillation of the electrons. The wavelength at which these electrons can be collectively excited and oscillate depends on the number of electrons present in the plasmonic resonance absorber particle, which in turn depends on the size of the plasmonic resonance absorber particle. The amount of energy at which the electrons of the particle can collectively oscillate is low enough that very small particles (e.g., 1-100 nm) can absorb radiation having a wavelength that is several times (e.g., 8 to 800 times or more) larger than the size of the particle. The use of these particles makes the fusing agent 26 inkjet sprayable and electromagnetically selective (e.g., having absorption at wavelengths of 800 nm to 4000 nm and transparency at wavelengths of 400 nm to 780 nm).

[0136] In one example, the plasmonic resonance absorber has an average particle size (e.g., volume weighted average diameter) of greater than 0 nm to less than 220 nm. In another example, the plasmonic resonance absorber has an average particle size of greater than 0 nm to 120 nm. In yet another example, the plasmonic resonance absorber has an average particle size of about 10 nm to about 200 nm.

[0137] In one example, the plasmonic resonance absorber is an inorganic pigment. Examples of suitable inorganic pigments include lanthanum hexaboride (LaB6), tungsten bronze (A x WO3), indium tin oxide (In2O3: SnO2, ITO), aluminum zinc oxide (AZO), ruthenium oxide (RuO2), silver (Ag), gold (Au), platinum (Pt), hypersthene (A x Fe y Si2O6, where A is Ca or Mg, x = 1.5-1.9 and y = 0.1-0.5), modified iron phosphate (A x Fe y PO4), and modified copper pyrophosphate (A x Cu y P2O7). The tungsten bronze can be an alkali metal doped tungsten oxide. Examples of suitable alkali metal dopants (i.e., A x WO3) can be cesium, sodium, potassium, or rubidium. In one example, the alkali metal doped tungsten oxide can be doped in an amount of greater than 0 mole % to about 0.33 mole % based on the total mole % of the alkali metal doped tungsten oxide. Examples of suitable modified iron phosphate (A x Fe yPO4) can include copper iron phosphate (A = Cu, x = 0.1-0.5 and y = 0.5-0.9), magnesium iron phosphate (A = Mg, x = 0.1-0.5 and y = 0.5-0.9), and zinc iron phosphate (A = Zn, x = 0.1-0.5 and y = 0.5-0.9). For modified iron phosphate, it is understood that the number of phosphate groups can vary based on charge balance with the cations. Suitable modified copper pyrophosphates (A x Cu y P2O7) include copper iron pyrophosphate (A = Fe, x = 0-2 and y = 0-2), magnesium copper pyrophosphate (A = Mg, x = 0-2 and y = 0-2), and zinc copper pyrophosphate (A = Zn, x = 0-2 and y = 0-2). Combinations of inorganic pigments can also be used.

[0138] The amount of active material present in the fusing agent 26 is greater than 0 wt% to about 40 wt% based on the total weight of the fusing agent 26. In other examples, the amount of active material in the fusing agent 26 is about 0.3 wt% to 30 wt%, about 1 wt% to about 20 wt%, about 1.0 wt% up to about 10.0 wt%, or greater than 4.0 wt% up to about 15.0 wt%. It is believed that these active material loadings provide a balance between jetting reliability and thermal and / or electromagnetic radiation absorption efficiency of the fusing agent 26.

[0139] As used herein, "FA carrier" can refer to a liquid in which an active material is dispersed or dissolved to form the fusing agent 26. A variety of FA carriers, including aqueous and non-aqueous carriers, can be used in the fusing agent 26. In some examples, the FA carrier can comprise water alone or a non-aqueous solvent alone, without other components. In other examples, the FA carrier can comprise other components, depending in part on the first applicator 24A to be used to dispense the fusing agent 26. Examples of other suitable fusing agent components include dispersants, silane coupling agents, co-solvents, surfactants, antimicrobial agents, anti-coking agents, and / or chelating agents.

[0140] When the active material is a plasmonic resonance absorber, the plasmonic resonance absorber can in some cases be dispersed with a dispersant. In this way, the dispersant helps to uniformly distribute the plasmonic resonance absorber throughout the fusing agent 26. Examples of suitable dispersants include polymeric or small molecule dispersants, charged groups attached to the surface of the plasmonic resonance absorber, or other suitable dispersants. Some specific examples of suitable dispersants include water-soluble acrylic polymers (such as K7028) available from Lubrizol, water-soluble styrene-acrylic copolymers / resins (such as Joncryl® 499 available from BASF Corp.), and water-soluble polyvinylpyrrolidone (PVP) polymers (such as Kollidon® 25, Kollidon® 30, and Kollidon® 90F available from BASF Corp.). 296、 671、 678、 680 683、 690, etc.), high molecular weight block copolymers with pigment affinity groups (e.g., those available from BYK Additives and Instruments). -190) or water-soluble styrene-maleic anhydride copolymer / resin.

[0141] Whether using a single dispersant or a combination of dispersants, the total amount of one or more dispersants in the flux 26 can be from about 10% by weight to about 200% by weight based on the weight of the plasma resonance absorber in the flux 26.

[0142] When the active material is a plasma resonance absorber, a silane coupling agent can also be added to the flux 26 to facilitate the bonding of organic and inorganic materials. Examples of suitable silane coupling agents include those manufactured by Momentive. Series A.

[0143] Whether using a single silane coupling agent or a combination of silane coupling agents, the total amount of one or more silane coupling agents in the flux 26 can be from about 0.1 wt% to about 50 wt% based on the weight of the plasma resonance absorber in the flux 26. In one example, the total amount of one or more silane coupling agents in the flux 26 is from about 1 wt% to about 30 wt% based on the weight of the plasma resonance absorber. In another example, the total amount of one or more silane coupling agents in the flux 26 is from about 2.5 wt% to about 25 wt% based on the weight of the plasma resonance absorber.

[0144] The solvent for the flux 26 can be water or a non-aqueous solvent (e.g., ethanol, acetone, n-methylpyrrolidone, aliphatic hydrocarbons, etc.). In some instances, the flux 26 consists of an active material and a solvent (excluding other components). In these instances, the solvent constitutes the balance of the flux 26.

[0145] One or more co-solvents that can be used in the water-based flux 26 include any of the co-solvents listed above with reference to anti-agglomeration solutions 28, 30. One or more co-solvents may be present in the flux 26 in a total amount of approximately 1% by weight to approximately 50% by weight based on the total weight of the flux 26, depending on the spraying architecture of the applicator 24. In one example, the total amount of one or more co-solvents present in the flux 26 is 25% by weight based on the total weight of the flux 26.

[0146] Similar to the anti-coalescing solutions 28, 30, the coalescent 26 can include one or more co-solvents, which can depend in part on the jetting technology to be used to dispense the coalescent 26. For example, if a thermal inkjet print head is to be used, water and / or ethanol and / or other longer chain alcohols (e.g., amyl alcohol) can be the solvent (i.e., make up 35% or more by weight of the coalescent 26) or co-solvent. For another example, if a piezoelectric inkjet print head is to be used, water can make up about 25% to about 30% by weight of the coalescent 26, and the solvent (i.e., 35% or more by weight of the coalescent 26) can be ethanol, isopropyl alcohol, acetone, and the like.

[0147] In some examples, the FA carrier includes one or more surfactants to improve the jetability of the coalescent 26. Examples of suitable surfactants include those listed above with respect to the anti-coalescing solutions 28, 30. Whether a single surfactant is used or a combination of surfactants is used, the total amount of the one or more surfactants in the coalescent 26 can be about 0.01% to about 10% by weight, based on the total weight of the coalescent 26. In one example, the total amount of the one or more surfactants in the coalescent 26 can be about 3% by weight, based on the total weight of the coalescent 26.

[0148] An anti-coking agent can be included in the coalescent 26 to be jetted using a thermal inkjet print. Coking refers to the deposit of a dried print liquid (e.g., the coalescent 26) on the heating elements of a thermal inkjet print head. The inclusion of one or more anti-coking agents aids in preventing coking buildup. Examples of suitable anti-coking agents include oleyl polyether-3-phosphate (e.g., available as CRODAFOS TM O3A or CRODAFOS TM N-3 Acid from Croda), or a combination of oleyl polyether-3-phosphate and a low molecular weight (e.g., < 5,000) polyacrylic acid polymer (e.g., available as CARBOSPERSE TM K-7028 Polyacrylate from Lubrizol).

[0149] Whether a single anti-coking agent is used or a combination of anti-coking agents is used, the total amount of the one or more anti-coking agents in the coalescent 26 can be greater than 0.20% to about 0.65% by weight, based on the total weight of the coalescent 26. In one example, oleyl polyether-3-phosphate is included in an amount of about 0.20% to about 0.60% by weight, and a low molecular weight polyacrylic acid polymer is included in an amount of about 0.005% to about 0.03% by weight.

[0150] The FA carrier can also include antimicrobial agent(s). Suitable antimicrobial agents include biocides and fungicides. Exemplary antimicrobial agents can include NIOSEPT TM (Troy Corp.), UCARCIDE TM (Dow Chemical Co.), B20 (Thor Chemicals), M20 (Thor Chemicals), MBL (a blend of 2-methyl-4-isothiazolin-3-one (MIT), 1,2-benzisothiazolin-3-one (BIT), and bromonitropyrrol) (Thor Chemicals), AXIDE TM (Planet Chemical), NIPACIDE TM (Clariant), a blend of 5-chloro-2-methyl-4-isothiazolin-3-one (CIT or CMIT) and MIT under the trademark KATHON TM (Dow Chemical Co.), and combinations thereof. Examples of suitable biocides include an aqueous solution of 1,2-benzisothiazolin-3-one (e.g., NALCO® GXL from Arch Chemicals, Inc.), a quaternary ammonium compound (e.g., VARSAFECT® 2250 and 2280, 50-65B, and 250-T, all from Lonza Ltd. Corp.), and an aqueous solution of methylisothiazolinone (e.g., NALCO® MLX from Dow Chemical Co.). In one example, the fusing agent 26 can include a total amount of antimicrobial agent of about 0.05 wt% to about 1 wt%. In one example, the antimicrobial agent(s) is biocide(s) and is present in the fusing agent 26 in an amount of about 0.25 wt% (based on the total weight of the fusing agent 26). Chelating agents (or sequestering agents) can be included in the FA carrier to eliminate the deleterious effects of heavy metal impurities. Examples of chelating agents include disodium ethylenediaminetetraacetate (EDTA-Na), ethylenediaminetetraacetic acid (EDTA), and methylglycinediacetic acid (e.g., TRILON® M from BASF Corp.).

[0151]

[0152]

[0153] ​​​​Whether a single chelating agent is used or a combination of chelating agents is used, the total amount of chelating agent(s) in the fusing agent 26 can be greater than 0 wt% to about 2 wt% based on the total weight of the fusing agent 26. In one example, the chelating agent(s) is present in the fusing agent 26 in an amount of about 0.04 wt% (based on the total weight of the fusing agent 26).

[0154] Also in some examples of the methods 100, 200, 300 and systems 10 disclosed herein, a detailing agent 52 can be used. The detailing agent 52 can include a surfactant, a co-solvent, and a balance of water. In some examples, the detailing agent 52 consists of these components, without other components. In other examples, the detailing agent 52 can further include a colorant. In yet other examples, the detailing agent 52 consists of a colorant, a surfactant, a co-solvent, and a balance of water, without other components. In still other examples, the detailing agent 52 can further include additional components, such as an anti-coking agent, an antimicrobial agent, and / or a chelating agent (each of which is described above with reference to the fusing agent 26).

[0155] The surfactant(s) that can be used in the detailing agent 52 include any of the surfactants listed above with reference to the anti-coalescing solutions 28, 30. The total amount of surfactant(s) in the detailing agent 52 can be about 0.10 wt% to about 5.00 wt% relative to the total weight of the detailing agent 52.

[0156] The co-solvent(s) that can be used in the detailing agent 52 include any of the co-solvents listed above with reference to the anti-coalescing solutions 28, 30. The total amount of co-solvent(s) in the detailing agent 52 can be about 1.00 wt% to about 20.00 wt% relative to the total weight of the detailing agent 52.

[0157] Similar to the anti-coalescing solutions 28, 30 and the fusing agent 26, the co-solvent(s) of the detailing agent 52 can depend in part on the jetting technology to be used to dispense the detailing agent 52. For example, if a thermal inkjet printhead is to be used, then water and / or ethanol and / or other longer chain alcohols (e.g., amyl alcohol) can make up 35 wt% or more of the detailing agent 52. For another example, if a piezoelectric inkjet printhead is to be used, then water can make up about 25 wt% to about 30 wt% of the detailing agent 52, and 35 wt% or more of the detailing agent 52 can be ethanol, isopropyl alcohol, acetone, and the like.

[0158] When the detailing agent 52 includes a colorant, the colorant can be a dye of any color that has substantially no absorption in the range of 650 nm to 2500 nm. By "substantially no absorption" it is meant that the dye does not absorb radiation at wavelengths in the range of 650 nm to 2500 nm, or that the dye absorbs less than 10% of radiation at wavelengths in the range of 650 nm to 2500 nm. The dye can also absorb radiation at wavelengths of 650 nm or less. Thus, the dye absorbs at least a portion of the wavelengths within the visible spectrum, but absorbs little or none of the wavelengths within the near infrared spectrum. This is in contrast to the active material in the fusing agent 26, which absorbs wavelengths within the near infrared spectrum. Thus, the colorant in the detailing agent 52 will substantially not absorb the fusing radiation, and will therefore not initiate melting and fusing of the polymer build material or polymer composite build material 16 with which it is in contact when the layer 40 is exposed to the fusing radiation.

[0159] The dye selected as the colorant in the detailing agent 52 can also have a high diffusivity (i.e., it can penetrate into the build material particles 16 by more than 10 pm and up to 100 pm). The high diffusivity enables the dye to penetrate into the build material particles 16 to which the detailing agent 52 is applied, and also enables the dye to diffuse into portions of the build material 16 adjacent to the portions of the build material 16 to which the detailing agent 52 is applied. The dye penetrates deeply into the build material particles 16 to dye / color the particles 16. When the detailing agent 52 is applied at the edge boundary 33 (of the final 3D object 44) or just outside the edge boundary 33, the build material particles 16 at the edge boundary 33 can be colored. In some examples, at least a portion of these dyed build material particles 16 can be present at the edge(s) or surface(s) of the formed 3D layer or object, which prevents or reduces any pattern (due to the different color of the fusing agent 26 and the polymer build material or polymer composite build material 16) from being formed at the edge(s) or surface(s).

[0160] The dye in the detailing agent 52 can be selected so that its color matches the color of the active material in the fusing agent 26. As an example, the dye can be any azo dye having sodium or potassium counterion(s) or any diazo (i.e., bis-azo) dye having sodium or potassium counterion(s), where the color of the azo or diazo dye matches the color of the fusing agent 26.

[0161] In one example, the dye is a black dye. Some examples of black dyes include an azo dye with sodium or potassium counterion(s) or a diazo (i.e., disazo) dye with sodium or potassium counterion(s). Examples of azo and diazo dyes can include (6Z)-4-acetamido-5-oxo-6-[[7-sulfonato-4-(4-sulfonatophenyl)azo-1-naphthyl]hydrazono]naphthalene-1,7-disulfonic acid tetrasodium salt with the following chemical structure: (available as Food Black 1); 6-amino-4-hydroxy-3-[[7-sulfonato-4-[(4-sulfonatophenyl)azo]-1-naphthyl]azo]naphthalene-2,7-disulfonic acid tetrasodium salt with the following chemical structure: (available as Food Black 2); (6E)-4-amino-5-oxo-3-[[4-(2-sulfonatoethoxysulfonyl)phenyl]diazenyl]-6-[[4-(2-sulfonatoethoxysulfonyl)phenyl]hydrazono]naphthalene-2,7-disulfonic acid tetrasodium salt with the following chemical structure: (available as Reactive Black 31); (6E)-4-amino-5-oxo-3-[[4-(2-sulfonatoethoxysulfonyl)phenyl]diazenyl]-6-[[4-(2-sulfonatoethoxysulfonyl)phenyl]hydrazono]naphthalene-2,7-disulfonic acid tetrasodium salt with the following chemical structure: and combinations thereof. Some other commercially available examples of dyes for the detailing agent 52 include multipurpose liquid based on black azo dyes such as Fast Black 1 (available from Fujifilm Holdings) and liquid based on black azo dyes with enhanced water fastness such as Fast Black 2 (available from Fujifilm Holdings).

[0162] In some cases, the colorant in the detailing agent 52 can include another dye in addition to the black dye. In one example, the other dye can be a cyan dye used in combination with any of the dyes disclosed herein. The other dye can also have substantially no absorption above 650 nm. The other dye can be any colored dye that helps improve the shade and color uniformity of the final 3D object.

[0163] Some examples of the other dye include a salt such as a sodium, ammonium, or potassium salt. Some specific examples include ethyl-[4-[[4-[ethyl-[(3-sulfophenyl)methyl]amino]phenyl]-(2-sulfophenyl)ethylidene]-1-cyclohexa-2,5-dienyl]-[(3-sulfophenyl)methyl]azanium with the following chemical structure:

[0164]

[0165] 4-[(E)-{4-[benzyl(ethyl)amino]phenyl}{(4E)-4-[benzyl(ethyl)iminio]cyclohexa-2,5- dien-1 -yl}methyl]benzene-1,3-disulfonic acid sodium salt having the following chemical structure:

[0166] Phthalocyanine having the following chemical structure:

[0167] In one example of the detailing agent 52, the dye can be present in an amount of about 1.00 wt% to about 3.00 wt% based on the total weight of the detailing agent 52. In another example of the detailing agent 52 comprising a combination of dyes, one dye (e.g., a black dye) is present in an amount of about 1.50 wt% to about 1.75 wt% based on the total weight of the detailing agent 52, and another dye (e.g., a cyan dye) is present in an amount of about 0.25 wt% to about 0.50 wt% based on the total weight of the detailing agent 52.

[0168] The remainder of the detailing agent 52 is water. As such, the amount of water can vary depending on the amount of other components included.

[0169] To further illustrate the disclosure, an example is set forth herein. It is to be understood that this example is provided by way of illustration and should not be construed as limiting the scope of the disclosure. Example

[0170] Examples of anti-coalescing polymer solutions were prepared. The exemplary anti-coalescing polymer solutions included polyvinyl alcohol as the polymer. The general formulation of the exemplary anti-coalescing polymer solutions, as well as the wt% of each component used, is shown in Table 1 below.

[0171] Table 1

[0172]

[0173]

[0174] Examples of anti-coalescing crosslinker solutions were also prepared. The exemplary anti-coalescing crosslinker solutions included sodium tetraborate as the multifunctional crosslinker. The general formulation of the exemplary anti-coalescing crosslinker solutions, as well as the wt% of each component used, is shown in Table 2 below.

[0175] Table 2 ​

[0176]

[0177] One of the example anti-coalescing polymer solutions and one of the example anti-coalescing crosslinker solutions were used to form an insoluble gel network and mixed with polyamide 12 (PA 12) powder to form an example removable build material portion. The example removable build material portion was placed in a dish of polyamide 12 powder, which was subsequently irradiated with a near-IR lamp for 25 seconds. After irradiation, the polyamide 12 powder surrounding the example removable build material portion was fused, and the polyamide 12 powder within the example insoluble gel network was not fused. The fused polyamide 12 powder was removed from the example removable build material portion, and the example removable build material portion was torn into pieces. One portion of the pieces was placed in a mild hydrochloric acid solution (pH 3), and another portion of the pieces was placed in an ascorbic acid solution (pH 3.5). After 60 seconds, the example insoluble gel network in both solutions was completely degraded, leaving unfused / sintered polyamide 12 powder.

[0178] It is to be understood that the ranges provided herein include the stated range and any value or sub-range within the stated range. For example, about 3 wt% to about 10 wt% should be interpreted to include not only about 3 wt% to about 10 wt% recited limits but also to include the independent values, such as about 4 wt%, about 5.1 wt%, about 7.25 wt%, about 8.85 wt%, about 9.5 wt%, etc., as well as sub-ranges, such as about 3.5 wt% to about 7.35 wt%, about 3.15 wt% to about 9.5 wt%, about 5 wt% to about 8.5 wt%, etc. Furthermore, when "about" is used to describe a value, it means that slight variations (up to + / - 10%) from the stated value are encompassed.

[0179] Reference throughout this specification to "one example", "another example", "an example", and so forth, means that a particular element (e.g., feature, structure, and / or characteristic) described in connection with the example is included in at least one example described herein, and can or can not be present in other examples. In addition, it is to be understood that the described elements can be combined in any suitable manner in the various examples unless the context clearly dictates otherwise.

[0180] In describing and claiming the examples disclosed herein, the singular forms "a", "an", and "the" include plural referents unless the context clearly dictates otherwise.

[0181] While several embodiments have been described in detail, it will be apparent that modifications can be made to the embodiments without departing from the scope of the disclosed examples. Accordingly, the foregoing description is to be considered non-limiting.

Claims

1. Three-dimensional 3D printing methods, including: Apply polymer building materials or polymer composite building materials; Negatively patterning a portion of the polymer building material or polymer composite building material to define a removable building material portion and a remaining building material portion, the negative patterning comprising: Selective application of an anti-agglomeration polymer solution containing a polymer having side-dependent reactive functional groups; and Selective application of an anti-agglomeration crosslinking agent solution containing a multifunctional crosslinking agent; The side-reactive functional groups react with the multifunctional crosslinking agent to form an insoluble gel network in the polymeric building material or polymeric composite building material in the removable building material portion, wherein the insoluble gel network forms a barrier between the polymeric building material or polymeric composite building material in the removable building material portion and the polymeric building material or polymeric composite building material in the portion to be formed as part of the final 3D object, such that the polymeric building material or polymeric composite building material in the removable building material portion remains physically separated from the final 3D object even after exposure to energy / radiation; Based on a 3D object model, at least a portion of the remaining building material portion forms a layer of the final 3D object, wherein the portion of the polymer building material or polymer composite building material in the removable building material portion remains physically separated from the layer.

2. The method as defined in claim 1, wherein the formation of the layer involves: Based on a 3D object model, a fusion agent is selectively applied to at least a portion of the remaining building material; and The polymer building material or polymer composite building material is exposed to radiation to fuse at least a portion of the remaining building material portion.

3. The method as defined in claim 2, further comprising selectively applying a refining agent to at least a portion of the remaining building material portion, wherein the refining agent comprises a surfactant, a cosolvent, and water.

4. The method as defined in claim 1, wherein the formation of the layer involves selective laser sintering of at least a portion of the remaining building material portion based on a 3D object model.

5. The method as defined in claim 1, further comprising selectively applying a refining agent to the portion of the polymeric building material or polymeric composite building material to at least partially promote the reaction of the side-reactive functional groups with the multifunctional crosslinking agent to form an insoluble gel network, wherein the refining agent comprises a surfactant, a cosolvent, and water.

6. The method as defined in claim 1, further comprising selectively applying a refining agent to a third portion of the polymeric building material or polymeric composite building material to prevent the polymeric building material or polymeric composite building material in the third portion from fusing, wherein the third portion does not include the at least a portion of the removable building material portion or the remaining building material portion, and the refining agent comprises a surfactant, a co-solvent, and water.

7. The method as defined in claim 1, further comprising: The application of the polymer building material or polymer composite building material, the negative patterning, and the formation are repeated, wherein the repeated formation i) comprises a final 3D object of the layer, and ii) a removable object in contact with at least a portion of the final 3D object, the removable object comprising a portion of the removable building material; and The removable object is exposed to a degradation agent solution to degrade the insoluble gel network.

8. The method as defined in claim 7, wherein the degradation agent solution is selected from strong acid solutions, weak acid solutions, reducing solutions, and combinations thereof.

9. The method as defined in claim 1, wherein: The polymer has side-reactive functional groups including maleic anhydride functional groups, and the multifunctional crosslinking agent is a diamine; or The polymer has side-reactive functional groups including maleimide functional groups, and the multifunctional crosslinking agent is a dithiol; or The polymer's side-reactive functional groups include alcohol functional groups, and the multifunctional crosslinking agent is a diacyl chloride or a tetraborate; or The polymer has side-reactive functional groups including epoxy functional groups, and the multifunctional crosslinking agent is a bifunctional nucleophile.

10. The method as defined in claim 1, wherein the polymer is contained in the anti-agglomeration polymer solution in an amount of 2% to 30% by weight based on the total weight of the anti-agglomeration polymer solution.

11. The method as defined in claim 1, wherein the multifunctional crosslinking agent is included in the anti-agglomeration crosslinking agent solution in an amount of 1% to 15% by weight based on the total weight of the anti-agglomeration crosslinking agent solution.

12. The method as defined in claim 1, wherein the anti-agglomeration polymer solution and the anti-agglomeration crosslinking agent solution are each selectively applied via thermal inkjet printing, and wherein each of the anti-agglomeration polymer solution and the anti-agglomeration crosslinking agent solution comprises a carrier, the carrier comprising: water; Cosolvent; Surfactants; and Wetting agent.

13. Three-dimensional 3D printing methods, including: Apply polymer building materials or polymer composite building materials; Negatively patterning a portion of the polymer building material or polymer composite building material to define a removable building material portion, the negative patterning comprising: Selective application of an anti-agglomeration polymer solution containing a polymer having side-dependent reactive functional groups; and Selective application of an anti-agglomeration crosslinking agent solution containing a multifunctional crosslinking agent; The side-reactive functional groups react with the multifunctional crosslinking agent to form an insoluble gel network in the polymeric building material or polymeric composite building material in the removable building material portion, wherein the insoluble gel network forms a barrier between the polymeric building material or polymeric composite building material in the removable building material portion and the polymeric building material or polymeric composite building material in the portion to be formed as part of the final 3D object, such that the polymeric building material or polymeric composite building material in the removable building material portion remains physically separated from the final 3D object even after exposure to energy / radiation; A flux is selectively applied to another portion of the polymer building material or polymer composite building material to define a portion of the polymer building material or polymer composite building material to be formed as part of the final 3D object, and wherein the removable building material portion is at least partially adjacent to the portion. The polymeric building material or polymeric composite building material is exposed to radiation to fuse the polymeric building material or polymeric composite building material in the portion, thereby forming a layer of the final 3D object, wherein the polymeric building material or polymeric composite building material in the removable building material portion remains physically separated from the layer; and The application of the polymer building material or polymer composite building material, the negative patterning, the selective application of the fusion agent, and the exposure are repeated, wherein the repeated formation forms a final 3D object comprising the layer and a removable object in contact with at least a portion of the final 3D object, the removable object comprising a portion of the removable building material.

14. Three-dimensional 3D printed products, among which, The 3D printed article is manufactured by the method according to any one of claims 1 to 13, and the 3D printed article comprises: Fused polymer or polymer composite objects; and A removable object in contact with at least a portion of the fused polymer or polymer composite object, the removable object comprising: Insoluble gel network; and Polymer building material or polymer composite building material particles mixed with the insoluble gel network.

15. The 3D printed article as defined in claim 14, wherein the insoluble gel network of the removable object is removable in a degrading agent solution selected from strong acid solutions, weak acid solutions, reducing solutions, and combinations thereof.

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