Methods and kits for three-dimensional (3D) printing

Abstract

An example of a three-dimensional (3D) printing kit includes an ultraviolet (UV) light fusing agent. The ultraviolet (UV) light fusing agent includes an aqueous carrier and a B vitamin or a B vitamin derivative present in an amount dissolved in the aqueous carrier. The aqueous carrier includes a cosolvent, a surfactant, and water. The B vitamin or the B vitamin derivative has absorption at a wavelength of about 340 nm to about 415 nm.

Description

Technical Field

[0001] The present disclosure relates generally to three-dimensional printing.

[0002] background

[0003] Three-dimensional (3D) printing can be an additive printing method for manufacturing three-dimensional solid parts from digital models. 3D printing is commonly used for rapid product prototyping, mold generation, master mold generation and small batch manufacturing. Some 3D printing technologies are considered additive methods because they involve applying successive layers of materials (which may include build materials, adhesives and / or other one or more printing liquids or combinations thereof in some instances). This is different from traditional machining methods, which usually rely on removing materials to make the final parts. Some 3D printing methods use chemical adhesives or adhesives to bond the build materials together. Other 3D printing methods involve at least partial curing, thermal merging / fusion, melting, sintering, etc. of the build materials, and the material coalescence mechanism may depend on the type of build material used. For some materials, heat-assisted extrusion can be used to achieve at least partial melting, and for other materials (such as polymerizable materials), infrared light can be used, for example, to achieve curing or fusion. Summary of the invention

[0004] According to a first aspect of the present disclosure, there is provided a three-dimensional (3D) printing kit, comprising: an ultraviolet (UV) light fusing agent, comprising: an aqueous carrier comprising a cosolvent, a surfactant and water; and B vitamins or B vitamin derivatives present in an amount dissolved in the aqueous carrier, the B vitamins or B vitamin derivatives having absorption at a wavelength of about 340 nm to about 415 nm, wherein the B vitamins or B vitamin derivatives are selected from riboflavin, folic acid, cyanocobalamin, pantothenic acid, biotin, pyridoxine and a combination thereof and are present in an amount of about 1 wt % to about 5 wt % based on the total weight of the UV light fusing agent; or wherein the B vitamins or B vitamin derivatives are selected from flavin mononucleotide, pyridoxal phosphate hydrate, pyridoxal hydrochloride, pyridoxine hydrochloride, pyridoxamine and a combination thereof and are present in an amount of about 1 wt % to about 8 wt % based on the total weight of the UV light fusing agent.

[0005] According to a second aspect of the present disclosure, a three-dimensional (3D) printing method is provided, comprising: applying a polymer building material composition to form a building material layer; selectively applying an ultraviolet (UV) light fusing agent on at least a portion of the building material layer based on a 3D object model, the UV light fusing agent comprising: an aqueous carrier comprising a cosolvent, a surfactant, and water; and a B vitamin or a B vitamin derivative present in an amount dissolved in the aqueous carrier, the B vitamin or the B vitamin derivative having an absorption at a wavelength of about 340 nm to about 415 nm, wherein the B vitamin or the B vitamin derivative has an absorption at a wavelength of about 340 nm to about 415 nm. The vitamin or B vitamin derivative is selected from riboflavin, folic acid, cyanocobalamin, pantothenic acid, biotin, pyridoxine and combinations thereof and is present in an amount of about 1 wt % to about 5 wt % based on the total weight of the UV fusing agent; or wherein the B vitamin or B vitamin derivative is selected from flavin mononucleotide, pyridoxal phosphate hydrate, pyridoxal hydrochloride, pyridoxine hydrochloride, pyridoxamine and combinations thereof and is present in an amount of about 1 wt % to about 8 wt % based on the total weight of the UV fusing agent; and exposing the layer of build material to ultraviolet radiation to cause at least the portion to coalesce to form a layer of the 3D object. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] With reference to the following detailed description and accompanying drawings, features of examples of the present disclosure will be apparent, in which like reference numerals correspond to similar but perhaps not identical components. For the sake of brevity, reference numerals or features having previously described functions may or may not be described in connection with other drawings in which they appear.

[0008] Figure 1 Schematically illustrating an example of a three-dimensional printing suit;

[0009] Figure 2 is a flow chart depicting an example of a 3D printing method;

[0010] Figure 3 yes Figure 2 A schematic diagram of an example of a 3D printing method;

[0011] Figures 4A to 4F are black and white reproductions of original color photographs of exemplary 3D object layers formed using different examples of UV fusing agents;

[0012] Figures 5A to 5D are black and white reproductions of original color photographs of exemplary 3D object layers formed using the same UV fusing agent (comprising folic acid and a type of aqueous carrier) and UV intensity but at different UV exposure times;

[0013] Figures 6A to 6Dis a black and white reproduction of an original color photograph of an exemplary 3D object layer formed using the same UV fusing agent (comprising folic acid and another type of aqueous carrier) and UV intensity but at different UV exposure times; and

[0014] Figures 7A to 7D are black and white reproductions of original color photographs of respective exemplary 3D objects formed with the same UV fusing agent (comprising folic acid and one type of aqueous carrier) but at different UV intensities with 1 or 2 second UV exposure times.

[0015] Details

[0016] Some three-dimensional (3D) printing methods utilize a fusing agent containing an energy absorber to pattern a polymer building material. In these examples, the entire polymer building material layer is exposed to electromagnetic radiation, but the patterned area of ​​the polymer building material (which is smaller than the entire layer in some cases) fuses / coalesces and hardens to become a layer of a 3D component. In the patterned area, the fusing agent can at least partially penetrate the gaps between the polymer building material particles, and can also spread on the outer surface of the polymer building material particles. The energy absorber in the fusing agent can absorb radiation and convert the absorbed radiation into thermal energy, thereby fusing / coalescing the polymer building material in contact with the fusing agent. Fusion / coalescing causes the polymer building materials to combine or blend to form a single entity (i.e., a layer of a 3D component). Fusion / coalescing may involve at least partially thermal merging, melting, bonding, and / or some other mechanisms that coalesce the polymer building materials to form a layer of a 3D component.

[0017] In this type of 3D printing method, infrared (IR) and / or visible radiation is typically used. These types of radiation can be generated using incandescent lamps (black body emitters) that emit a broad band of photon energy. This can cause selectivity issues because incandescent lamps emit a large amount of near infrared (NIR) and infrared radiation, which can be absorbed by non-patterned polymer build materials. This can result in inaccurate part shapes and / or rough part edges. In addition, some infrared (IR) and / or visible radiation absorbers are dark gray or black, which can result in printed parts having a corresponding, and generally undesirable, dark color or even black.

[0018] Narrow-band emission sources such as UV light-emitting diodes (LEDs) may be suitable alternatives for these 3D printing systems.

[0019] Disclosed herein is an ultraviolet light fusing agent formulated with B vitamins or B vitamin derivatives having absorption at wavelengths of about 340 nm to about 415 nm. The B vitamins and B vitamin derivatives disclosed herein are highly soluble in water, which makes them particularly suitable for incorporation into aqueous carriers. The resulting ultraviolet light fusing agent can be dispensed from an inkjet printhead, which enables it to be controllably applied at the voxel level. The B vitamins and B vitamin derivatives disclosed herein also exhibit strong absorption in the near-ultraviolet range, which facilitates efficient UV-based coalescence of 3D objects formed with the ultraviolet light fusing agent. Further, the B vitamins or B vitamin derivatives are complementary to human metabolism, which makes the fusing agent suitable for making 3D objects for various applications, such as food packaging, other commodity packaging, pharmacology, biomedical applications, etc. Further still, some B vitamins or B vitamin derivatives are substantially colorless, and thus can generate 3D objects that are much lighter in color (e.g., white, off-white, or even translucent) than comparative infrared (IR) and / or visible radiation absorbers.

[0020] Throughout this disclosure, weight percentages referred to as "weight % actives" refer to the loading of active components present in a dispersion or other formulation, such as a fusing agent, a refiner, etc. For example, a surfactant may be present in a water-based formulation (e.g., a stock solution or dispersion) prior to incorporation into a fusing agent vehicle. In this example, the weight % actives of the surfactant takes into account the loading of surfactant molecules present in the fusing agent (as weight %), and does not take into account the weight of other components (e.g., water, etc.) present in the stock solution or dispersion with the surfactant molecules. The term "weight %" without the term "actives" refers to the loading of 100% active components (in a fusing agent, etc.) where other inactive components are not included.

[0021] UV light fuse

[0022] The ultraviolet (UV) light fusing agent disclosed herein comprises: an aqueous carrier comprising a cosolvent, a surfactant and water; and a B vitamin or a B vitamin derivative present in an amount dissolved in the aqueous carrier, wherein the B vitamin or the B vitamin derivative has absorption at a wavelength of about 340 nm to about 415 nm. In some examples, the ultraviolet light fusing agent consists of these components. In other examples, the ultraviolet light fusing agent may include other additives. Examples of suitable additives include anti-fouling agents, chelating agents, antimicrobial agents, buffers, pH adjusters, preservatives and combinations thereof.

[0023] B vitamins and / or B vitamin derivatives act as ultraviolet energy absorbers in the fusing agent. Exemplary vitamins and vitamin derivatives absorb ultraviolet radiation efficiently, convert the absorbed ultraviolet radiation into heat energy, and promote the transfer of heat to the polymer building material composition to coalesce the polymer building material composition. Any B vitamins and / or B vitamin derivatives that are water-soluble and have absorption at a wavelength of about 340nm to about 415nm can be used for the ultraviolet light fusing agent. The phrase "absorption at a wavelength of about 340nm to about 415nm" means that the B vitamin or B vitamin derivative exhibits maximum absorption at a wavelength within a given range and / or has an absorbance of about 0.1 (about 80% transmittance or less) at one or more wavelengths within a given range. Some B vitamins or B vitamin derivatives have lower absorbance. When they are combined with higher intensity and / or higher dose (wherein dose = intensity * radiation time), these B vitamins or B vitamin derivatives can still bring about suitable coalescence and fusion.

[0024] Examples of suitable B vitamins include riboflavin (vitamin B2), pantothenic acid (vitamin B5), pyridoxine (a form of vitamin B6), pyridoxamine (another form of vitamin B6), biotin (vitamin B7), folic acid (a synthetic form of vitamin B9), cyanocobalamin (a synthetic form of vitamin B12), and combinations thereof. Examples of suitable B vitamin derivatives include flavin mononucleotides, pyridoxal phosphate hydrate, pyridoxal hydrochloride, pyridoxine hydrochloride, and combinations thereof. Any combination of one or more B vitamins and one or more B vitamin derivatives may also be used. This may be desirable, for example, when the absorbance of one vitamin or vitamin derivative is low.

[0025] B vitamins and / or B vitamin derivatives can be selected to have a target maximum absorption wavelength for a 3D printing system that includes a narrow UV band emission source. For example, cyanocobalamin exhibits a maximum absorption at approximately 360 nm and can therefore be selected for use as a fusing agent when the 3D printing system includes an ultraviolet light emitting diode (LED) that emits at 365 nm. Additionally, folic acid exhibits a maximum absorption at approximately 365 nm and can therefore be selected for use as a fusing agent when the 3D printing system includes a UV LED that emits at 365 nm. Still further, riboflavin exhibits its second highest absorption peak at approximately 375 nm and can therefore be selected for use as a fusing agent when the 3D printing system includes a UV LED that emits at 365 nm or 395 nm. Still further, pyridoxal phosphate exhibits a maximum absorption at approximately 390 nm and can therefore be selected for use as a fusing agent when the 3D printing system includes a UV light emitting diode that emits at 395 nm. Although the B vitamins or B vitamin derivatives may be specifically selected to have a target maximum absorption wavelength for a target narrow UV band emission source, it is understood that sufficient absorption and fusion may occur at wavelengths in the tail of the peak. Thus, the B vitamins or B vitamin derivatives do not necessarily have to be selected to have a target maximum absorption wavelength for a target narrow UV band emission source. Additionally, as described above, the UV intensity and / or dosage may also be adjusted to enhance agglomeration and fusion.

[0026] The amount of the UV absorber, i.e., B vitamins and / or B vitamin derivatives, present in the UV flux depends in part on their solubility in water and their effect on the sprayability of the flux. When the solubility limit of the B vitamins and / or B vitamin derivatives is low, the B vitamins and / or B vitamin derivatives may be present in an amount of about 1 wt % to about 5 wt % of the total weight of the flux. For example, when the B vitamins or B vitamin derivatives are selected from riboflavin (water solubility 1000 mg / 3,000-15,000 mL, depending on the crystal structure), folic acid (water solubility 0.01 mg / mL), cyanocobalamin (water solubility 1000 mg / 80 mL), pantothenic acid (water solubility 2110 mg / mL), biotin (water solubility 0.22 mg / mL), pyridoxine (water solubility 79 mg / mL to 220 mg / mL) and combinations thereof, the B vitamins or B vitamin derivatives are present in an amount of about 1 wt % to about 5 wt % based on the total weight of the UV fusing agent.

[0027] For example, when the B vitamins or B vitamin derivatives are selected from pyridoxal phosphate hydrate (water solubility 5.7 mg / mL), pyridoxal hydrochloride (water solubility 11.7 mg / mL), pyridoxine hydrochloride (water solubility 200 mg / mL), pyridoxamine (water solubility 29 mg / mL) and combinations thereof, the B vitamins or B vitamin derivatives may be present in an amount of about 1 wt % to about 8 wt % based on the total weight of the UV fusing agent.

[0028] The B vitamins or B vitamin derivatives are capable of absorbing sufficient energy during the 3D printing process to heat and coalesce the polymer building material composition. Therefore, the UV light fusing agent does not contain an adhesive. For example, the UV light fusing agent does not contain a polymer molecule with an adhesive portion.

[0029] The aqueous carrier of the UV light flux contains a cosolvent. Classes of water-soluble or water-miscible organic cosolvents that can be used in the flux include aliphatic alcohols, aromatic alcohols, diols, polyols, glycols, long-chain alcohols, glycol ethers, polyglycol ethers, lactams, formamides (substituted and unsubstituted) and acetamides (substituted and unsubstituted). Examples of these cosolvents include aliphatic primary alcohols, aliphatic secondary alcohols, 1,2-ols, 1,3-ols, 1,5-ols, 1,6-hexanediol or other diols (e.g., 1,2-propylene glycol, 1,5-pentanediol, 2-methyl-1,3-propanediol, etc.), glycerol, ethylene glycol alkyl ethers, propylene glycol alkyl ethers, higher homologues (C6-C8) of polyethylene glycol alkyl ethers. 12 ), triethylene glycol, tetraethylene glycol, tripropylene glycol methyl ether, polyethylene glycol (PEG) of different weight average molecular weights (e.g., PEG 200, PEG 300, PEG 400, etc.), N-alkyl caprolactam, unsubstituted caprolactam, 2-pyrrolidone, 1-methyl-2-pyrrolidone, 1-(2-hydroxyethyl)-2-pyrrolidone, etc. In one example, the UV fusing agent comprises an environmentally friendly cosolvent, such as glycerol, polyethylene glycol (PEG) of different weight average molecular weights (e.g., PEG 200, PEG 300, PEG 400, etc.), or a combination thereof.

[0030] One or more co-solvents may be present in the UV fusing agent in a total amount of about 1 wt % active to about 55 wt % active based on the total weight of the UV fusing agent. In one example, the UV fusing agent comprises about 2 wt % active to about 15 wt % active, or about 5 wt % active to about 10 wt % active, or about 10 wt % active to about 50 wt % active of one or more co-solvents.

[0031] The aqueous carrier of the UV light fusing agent comprises a surfactant. Suitable one or more surfactants include nonionic or anionic surfactants. Other suitable one or more surfactants include quaternary ammonium surfactants. Some exemplary surfactants include alcohol ethoxylates, alcohol ethoxy sulfates, acetylenic glycols, alkyl polyethylene oxides, alkylphenyl polyethylene oxides, polyethylene oxide block copolymers, acetylenic polyethylene oxides, polyethylene oxide (di) esters, polyethylene oxide amines, protonated polyethylene oxide amines, protonated polyethylene oxide amides, polydimethylsiloxane copolyols, substituted amine oxides, fluorinated surfactants, etc. Some specific examples of nonionic surfactants include the following from Evonik Degussa: SEF (self-emulsifiable wetting agents based on acetylenic diol chemistry), 440 or CT-111 (nonionic ethoxylated low foaming wetting agent), 420 (nonionic ethoxylated wetting agent and molecular defoamer), 104E (nonionic wetting agent and molecular defoamer) and Wet 510 (organic surfactant). Other specific examples of nonionic surfactants include the following from The Dow Chemical Company: TERGITOL TM TMN-6, TERGITOL TM 15-S-7 and TERGITOL TM 15-S-9 (secondary alcohol ethoxylate). Other suitable nonionic surfactants are available from Chemours, including Fluorinated surfactants, such as FS-35 (nonionic fluorosurfactant). Some specific examples of anionic surfactants include alkyl diphenyl oxide disulfonates (e.g. DOWFAX TM Series, such as 2A1, 3B2, 8390, C6L, C10L and 30599), docusate sodium (i.e., sodium dioctyl sulfosuccinate), sodium dodecyl sulfate (SDS). In one example, the UV fusing agent includes an environmentally friendly co-surfactant, such as docusate sodium, sodium dodecyl sulfate or a combination thereof.

[0032] Whether a single surfactant or a combination of surfactants is used, the total amount of one or more surfactants in the UV fusing agent may be from about 0.01 wt % active to about 3 wt % active based on the total weight of the UV fusing agent. In one example, the total amount of one or more surfactants in the UV fusing agent may be about 1 wt % active based on the total weight of the UV fusing agent.

[0033] Some examples of UV fusing agents include anti-kogation agents. Anti-kogation agents may be particularly desirable in UV fusing agents to be jetted using thermal inkjet printing. Kogation refers to the deposition of dried printing liquid (e.g., fusing agent) on the heating elements of a thermal inkjet printhead. One or more anti-kogation agents are included to help prevent kogation accumulation.

[0034] Examples of suitable antifouling agents include oleyl polyoxyethylene (3) ether phosphate (available as CRODAFOS TM O3A or CRODAFOS TM N-3A is available commercially) or dextran 500k. Other suitable examples of anti-fouling agents include CRODAFOS TM HCE (phosphate ester from Croda Int.), O10A (Oleyl polyoxyethylene (10) ether phosphate from Croda Int.) or LFH (polymeric dispersant with aromatic anchor groups, acid form, anionic, from Clariant) etc. It is to be understood that any combination of the listed antifouling agents may be used.

[0035] When included, the anti-fouling agent can be present in the UV fusing agent in an amount of about 0.1 wt % active to about 1.5 wt % active based on the total weight of the UV fusing agent. In one example, the anti-fouling agent is present in an amount of about 0.5 wt % active based on the total weight of the UV fusing agent.

[0036] Some examples of UV light fusing agents include chelating agents. Chelating agents (or sequestering agents) may be included in the aqueous carrier of the UV light fusing agent to eliminate the harmful effects of heavy metal impurities. In one example, the chelating agent is selected from methylglycine diacetic acid, trisodium salt; 4,5-dihydroxy-1,3-benzenedisulfonic acid disodium salt monohydrate; ethylenediaminetetraacetic acid (EDTA); hexamethylenediaminetetrakis (methylenephosphonic acid), potassium salt; and combinations thereof. Methylglycine diacetic acid, trisodium salt (Na3MGDA) may be used as M was purchased from BASF Corp. 4,5-Dihydroxy-1,3-benzenedisulfonic acid disodium salt monohydrate can be used as TIRON TM The monohydrate is available as a commercial product. Hexamethylenediaminetetrakis(methylenephosphonic acid), potassium salt can be used as 2054 was purchased from Italmatch Chemicals.

[0037] Whether a single chelating agent or a combination of chelating agents is used, the total amount of one or more chelating agents in the UV fuse can be greater than 0 wt% active to about 0.5 wt% active based on the total weight of the UV fuse. In one example, the chelating agent is present in an amount of about 0.05 wt% active to about 0.2 wt% active based on the total weight of the UV fuse. In another example, the one or more chelating agents are present in the UV fuse in an amount of about 0.05 wt% active (based on the total weight of the UV fuse).

[0038] Some examples of UV fuses include antimicrobial agents. Antimicrobial agents are also known as biocides and / or fungicides. Examples of suitable antimicrobial agents include (Ashland Inc.), UCARCIDE TM or KORDEK TM or ROCIMA TM (The Dow Chemical Company), (Arch Chemicals) series, B20 and M20 and MBL (a blend of 2-methyl-4-isothiazolin-3-one (MIT), 1,2-benzisothiazolin-3-one (BIT) and Bronopol) (Thor Chemicals), AXIDE TM (Planet Chemical), NIPACIDE TM (Clariant), trade name KATHON TM Blends of 5-chloro-2-methyl-4-isothiazolin-3-one (CIT or CMIT) and MIT (The Dow Chemical Company) and combinations thereof.

[0039] In one example, the total amount of the one or more antimicrobial agents in the UV fuse is about 0.01 wt % active to about 0.05 wt % active (based on the total weight of the UV fuse). In another example, the total amount of the one or more antimicrobial agents in the UV fuse is about 0.04 wt % active (based on the total weight of the UV fuse).

[0040] Some examples of UV light fusing agents include a buffer. The buffer may be TRIS (tris(hydroxymethyl)aminomethane or ), TRIS or hydrochloride, bis-tris propane, TES (2-[(2-hydroxy-1,1-bis(hydroxymethyl)ethyl)amino]ethanesulfonic acid), MES (2-ethanesulfonic acid), MOPS (3-(N-morpholino)propanesulfonic acid), HEPES (4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid), DIPSO (3-(N,N-bis[2-hydroxyethyl]amino)-2-hydroxypropanesulfonic acid), Tricine (N-[tris(hydroxymethyl)methyl]glycine), HEPPSO (β-hydroxy-4-(2-hydroxyethyl)-1-piperazinepropanesulfonic acid monohydrate), POPSO (piperazine-1, 4-bis(2-hydroxypropanesulfonic acid)), EPPS (4-(2-hydroxyethyl)-1-piperazinepropanesulfonic acid, 4-(2-hydroxyethyl)piperazine-1-propanesulfonic acid), TEA (triethanolamine buffer solution), Gly-Gly (bisglycine), bicine (N,N-bis(2-hydroxyethyl)glycine), HEPBS (N-(2-hydroxyethyl)piperazine-N′-(4-butanesulfonic acid)), TAPS ([tris(hydroxymethyl)methylamino]propanesulfonic acid), AMPD (2-amino-2-methyl-1,3-propanediol), TABS (N-tris(hydroxymethyl)methyl-4-aminobutanesulfonic acid), etc.

[0041] In one example, the total amount of the one or more buffers in the UV fusing agent is about 0.01 wt % to about 3 wt % (based on the total weight of the UV fusing agent).

[0042] Some examples of UV fusing agents include pH adjusting agents. Suitable pH adjusting agents may include amino acids or sodium bicarbonate. An example of a suitable amino acid pH adjusting agent is taurine. In one example, the total amount of one or more pH adjusting agents in the UV fusing agent is (based on the total weight of the UV fusing agent) from about 0.01 wt % to about 3 wt %.

[0043] Some examples of UV fusing agents include preservatives. Examples of suitable preservatives include 2-phenoxyethanol, sodium benzoate, and parabens. In one example, the total amount of one or more preservatives in the UV fusing agent is (based on the total weight of the UV fusing agent) from about 0.1 wt % to about 3 wt %.

[0044] Some examples of UV fusing agents also include a base. In some examples, B vitamins or B vitamin derivatives are more soluble at neutral or alkaline pH. For example, folic acid is more soluble in aqueous carriers with a pH greater than 5. Therefore, it may be desirable to add a base, such as potassium hydroxide, sodium hydroxide, or tetramethylammonium hydroxide, until the desired pH is obtained. In one example, the total amount of base in the UV fusing agent is (based on the total weight of the UV fusing agent) from about 0.5% to about 5% by weight. In other examples, the amount of base may be from about 0.75% to about 2.5% by weight.

[0045] The balance of the UV fusing agent is water (e.g., deionized water, purified water, etc.). The amount of water may vary with the amounts of other components in the UV fusing agent. In one example, the UV fusing agent may be jetted by a thermal inkjet print head and contains about 50 wt % to about 90 wt % water.

[0046] An example of an ultraviolet light fusing agent comprises B vitamins or B vitamin derivatives, a cosolvent, a surfactant, water, and an additive selected from an anti-fouling agent, a chelating agent, an antimicrobial agent, a buffer, and a combination thereof. As a specific example having these components, the ultraviolet light fusing agent comprises riboflavin, tripropylene glycol methyl ether, SEF, FS-35, CRODAFOS TM O3A, B20, TRIS and water.

[0047] Another example of a UV fusing agent comprises B vitamins or B vitamin derivatives, a cosolvent, a surfactant, water, and an additive selected from a pH adjuster, a preservative, and a combination thereof. As a specific example having these components, the UV fusing agent comprises folic acid, glycerol, PEG 300, taurine, 2-phenoxyethanol, sodium docusate, sodium lauryl sulfate, potassium hydroxide, and water. This example of a UV fusing agent may be suitable for food packaging, other commodity packaging, pharmacology, biomedicine, and other similar applications because these components can be considered to be relatively environmentally friendly.

[0048] 3D Printing Kit and 3D Printing Multi-Fluid Kit

[0049] The UV light fusing agent disclosed herein can be part of a kit for 3D printing that does not include other fluids or reagents. In this example, the kit is a single fluid kit. In other examples, the UV light fusing agent can be included in a multi-fluid kit for 3D printing. An example of a multi-fluid kit is schematically shown in Figure 1In one example, the multi-fluid set 12 includes a UV fusing agent 10, which includes an aqueous carrier containing a cosolvent, a surfactant, and water; and a B vitamin or a B vitamin derivative present in an amount dissolved in the aqueous carrier, the B vitamin or the B vitamin derivative having absorption at a wavelength of about 340 nm to about 415 nm; and a thinning agent 14, which includes a second aqueous carrier and does not include an absorbent having absorption at a wavelength of about 340 nm to about 415 nm. In other examples, the multi-fluid set 12 may include the UV fusing agent 10 and the colored ink 16. In further examples, the multi-fluid set 12 may include the UV fusing agent 10, the thinning agent 14, and the colored ink 16.

[0050] The UV light fusing agent 10 disclosed herein may also be included in a 3D printing kit. One example of a 3D printing kit includes a polymeric build material composition; and an ultraviolet (UV) light fusing agent 10. Some examples of 3D printing kits also include a detailing agent 14 and / or a colored ink 16.

[0051] It is to be understood that the fluids 10, 14, 16 of the multi-fluid set 12 or one or more fluids 10, 14, 16 and compositions of the 3D printing set can be kept separate until used together in an example of the 3D printing method disclosed herein. One or more fluids 10, 14, 16 and / or compositions can each be contained in one or more containers before and during printing, but can be combined together during the printing process. The container can be any type of vessel (e.g., a reservoir), a box, or a receptacle made of any material.

[0052] As used herein, it is to be understood that the term "set" or "kit" is synonymous with "combination" in some instances.

[0053] Exemplary compositions of detailing agent 14, colored ink 16, and build material compositions that may be used with UV fusing agent 10 will now be described.

[0054] Refining agent

[0055] Some examples of the multi-fluid set 12 and / or the 3D printing set include a thinning agent 14. The thinning agent 14 may include a surfactant, a co-solvent, and a balance of water. In some examples, the thinning agent 14 consists of these components and has no other components. In other examples, the thinning agent 14 may further include additional components, such as one or more anti-fouling agents and / or one or more antimicrobial agents and / or preservatives (each described above with reference to the UV fusing agent 10).

[0056] The one or more surfactants useful in the thinning agent 14 include any of the surfactants listed herein with respect to the UV fusing agent 10. The total amount of the one or more surfactants in the thinning agent 14 may be from about 0.10 wt % to about 5 wt % relative to the total weight of the thinning agent 14.

[0057] The one or more co-solvents that may be used in the thinning agent 14 include any of the co-solvents listed above with respect to the UV fusing agent 10. The total amount of the one or more co-solvents in the thinning agent 14 may be from about 1 wt % to about 65 wt % relative to the total weight of the thinning agent 14.

[0058] In the examples disclosed herein, the thinning agent 140 does not contain a colorant. In these examples, the thinning agent 140 can be colorless, meaning that the thinning agent is achromatic and does not contain a colorant (eg, a pigment or dye).

[0059] The balance of the thinning agent 14 is water. Therefore, the amount of water may vary depending on the amounts of other components included.

[0060] Colored ink

[0061] Some examples of multi-fluid sets 12 and / or 3D printing sets include colored ink 16. In these examples, the colored ink 16 is separate from the UV fusing agent 10 disclosed herein. The colored ink 16 that is separate from the UV fusing agent 10 may be desirable because the two agents 10, 16 can be applied separately, thereby enabling control over where the color is added. The colored ink 16 can be applied during the printing process (e.g., on a polymeric build material with the UV fusing agent 10) or applied after printing (e.g., on a 3D printed object) to give the 3D printed object a colored appearance.

[0062] Colored ink 16 may include a colorant, a cosolvent, and a balance of water. In some examples, colored ink 16 consists of these components and no other components. In other examples, colored ink 16 may further include additional components that aid in the dispersibility of the colorant and / or the jettability of the ink. Some examples of additional ink components include one or more dispersants (e.g., water-soluble acrylic polymers (e.g., available from Lubrizol) K7028), water-soluble styrene-acrylic acid copolymer / resin (e.g., available from BASF Corp. 296, 671, 678, 680, 683, 690, etc.), high molecular weight block copolymers with pigment-affinic groups (e.g., available from BYK Additives and Instruments ) or water-soluble styrene-maleic anhydride copolymer / resin), one or more wetting agents, one or more surfactants, one or more anti-fouling agents and / or one or more antimicrobial agents (some of which are described herein with reference to UV light fuse 10).

[0063] The colored ink 16 may be a black agent, a cyan agent, a magenta agent, or a yellow agent. Therefore, the colorant may be a black colorant, a cyan colorant, a magenta colorant, a yellow colorant, or a combination of colorants that together realize black, cyan, magenta, or yellow.

[0064] The colorant of the colored ink 16 may be any pigment or dye. When the colored ink 16 is a separate agent, the pigment or dye is intended to provide color and is not intended to replace the UV absorber (i.e., B vitamins and / or B vitamin derivatives) in the fusing agent 10. Therefore, the colorant may act as a UV absorber or as a partial UV absorber, or may not provide any UV absorption.

[0065] An example of pigment-based colored ink can include one or more pigments of about 1 wt % to about 10 wt %, one or more cosolvents of about 10 wt % to about 30 wt %, one or more dispersants of about 1 wt % to about 10 wt %, one or more anti-scaling agents of 0.01 wt % to about 1 wt %, one or more antimicrobials of about 0.05 wt % to about 0.1 wt %, and surplus water. An example of dye-based colored ink can include one or more dyes of about 1 wt % to about 7 wt %, one or more cosolvents of about 10 wt % to about 30 wt %, one or more dispersants of about 1 wt % to about 7 wt %, one or more antimicrobials of about 0.05 wt % to about 0.1 wt %, one or more chelating agents of 0.05 wt % to about 0.1 wt %, one or more buffers of about 0.005 wt % to about 0.2 wt %, and surplus water.

[0066] Building material composition

[0067] The building material composition comprises a polymer building material. Examples of suitable polymer materials 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.), polyolefins (e.g., polyethylene, polypropylene, etc.), thermoplastic polyamides (TPA), thermoplastic polyurethanes (TPU), styrene block copolymers (TPS), thermoplastic polyolefin elastomers (TPO), thermoplastic vulcanizates (TPV), thermoplastic copolyesters (TPC), polyether block amides (PEBA), or combinations thereof.

[0068] In some examples, the polymeric building material may be in the form of a powder. In other examples, the polymeric building material may be in the form of a powdered material that includes, for example, short fibers that are longer than they are wide. In some examples, the powder or powdered material may be formed from or may include short fibers that may, for example, be cut into short lengths from a long tow or strand.

[0069] The polymeric building material can be composed of particles of similar size and / or particles of different sizes. In one example, the average particle size of the polymeric building material is about 2 μm to about 225 μm. In another example, the average particle size of the polymeric building material is about 10 μm to about 130 μm. As described above, the term "average particle size" used herein can refer to the number-weighted average diameter or volume-weighted average diameter of the particle distribution. In some cases, the average particle size represents D50, or the size that divides the distribution into half above a given diameter and half below a given diameter.

[0070] When the polymer building material is a crystalline or semi-crystalline material, the polymer can have a wide processing window of greater than 5°C, which can be defined by the temperature range between the melting point and the recrystallization temperature. In one example, the polymer can have a melting point of about 35°C to about 300°C. As other examples, the polymer can have a melting point of about 155°C to about 225°C, about 155°C to about 215°C, about 160°C to about 200°C, about 170°C to about 190°C, or about 182°C to about 189°C. As yet another example, the polymer can be a polyamide having a melting point of about 180°C or a polypropylene having a melting point of about 160°C.

[0071] As discussed herein, other polymers do not have a melting point, but rather have a temperature range at which the polymer softens. In some examples, this softening temperature range is from about 130°C to about 250°C.

[0072] In some examples, the polymeric building material does not substantially absorb radiation having a wavelength in the range of 300 nm to 405 nm. The phrase "substantially non-absorbing" means that the polymeric building material has an absorptivity of 25% or less (e.g., 20%, 10%, 5%, etc.) at a particular wavelength.

[0073] In some examples, in addition to the polymeric building material, the building material composition may also include an antioxidant, an antistatic agent, a flow aid, or a combination thereof. Although several examples of these additives are provided, it is understood that these additives are selected to be thermally stable (i.e., not decomposed) at 3D printing temperatures.

[0074] One or more antioxidants may be added to the build material composition to prevent or slow the molecular weight degradation of the polymer build material and / or to further prevent or slow discoloration (e.g., yellowing) of the composition by preventing or slowing oxidation of the polymer particles. In some examples, the antioxidant may be a free radical scavenger. In these examples, the antioxidant may include 1098 (phenylpropionamide, 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 may include a phosphite and / or an organic sulfide (e.g., a thioester). The antioxidant may be in a fine particle form (e.g., having an average particle size of 5 μm or less) and dry mixed with the polymeric building material. In one example, the antioxidant may be included in the building material composition in an amount of approximately 0.01 wt % to approximately 5 wt %, based on the total weight of the building material composition. In other examples, the antioxidant may be included in the building material composition in an amount of approximately 0.01 wt % to approximately 2 wt % or approximately 0.2 wt % to approximately 1 wt %, based on the total weight of the building material composition.

[0075] One or more antistatic agents may be added to the build material composition to inhibit triboelectric charging. Examples of suitable antistatic agents include aliphatic amines (which may be ethoxylated), aliphatic amides, quaternary ammonium salts (e.g., behentrimonium chloride or cocamidopropyl betaine), esters of phosphoric acid, polyethylene glycol esters, or polyols. Some suitable commercially available antistatic agents include FA 38 (natural ethoxylated alkylamine), FE2 (fatty acid esters) and HS1 (alkane sulfonate), each available from Clariant Int. Ltd. In one example, the antistatic agent is added in an amount of greater than 0 wt % to less than 5 wt % based on the total weight of the build material composition.

[0076] One or more glidants may be added to improve the coating flowability of the build material composition. Flow aids may be particularly beneficial when the build material composition has an average particle size of less than 25 μm. Flow aids improve the flowability of the build material composition by reducing friction, lateral drag, and triboelectric charge accumulation (by increasing particle conductivity). Examples of suitable glidants include tricalcium 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), 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) and polydimethylsiloxane (E900). In one example, the glidant is added in an amount of greater than 0 wt % to less than 5 wt % based on the total weight of the build material composition.

[0077] Printing method and usage

[0078] Reference Figure 2 and Figure 3 An example of a 3D printing method is shown and described.

[0079] Figure 2 The 3D printing method 100 shown in the figure includes applying a polymer building material composition to form a building material layer (reference numeral 102); based on the 3D object model, selectively applying an ultraviolet (UV) light fusing agent on at least a portion of the building material layer, the ultraviolet light fusing agent comprising an aqueous carrier containing a cosolvent, a surfactant and water, and a B vitamin or a B vitamin derivative present in an amount dissolved in the aqueous carrier, the B vitamin or the B vitamin derivative having absorption at a wavelength of about 340 nm to about 415 nm (reference numeral 104); and exposing the building material layer to ultraviolet radiation to cause at least the portion to coalesce to form a layer of the 3D object (reference numeral 106).

[0080] Before executing method 100, it is understood that the controller can access data stored in the data storage device about the 3D object to be printed. For example, the controller can determine the number of layers of the building material composition to be formed, the deposition position of any reagents on each layer, etc.

[0081] Reference now Figure 3, graphically depicts one example of a method 100 utilizing a UV fusing agent 10 (comprising B vitamins and / or B vitamin derivatives), a build material composition 18, and a detailing agent 14.

[0082] exist Figure 3 In the embodiment of the present invention, a layer 20 of a build material composition 18 is applied on a build area platform 22. A printing system can be used to apply build material composition 18. The printing system can include a build area platform 22, a build material supply 24 containing build material composition 18, and a build material dispenser 26.

[0083] Build area platform 22 is a substantially horizontal build platform that does not act as a mold for build material composition 18 applied thereto. Rather, build area platform is a flat surface onto which build material composition 18 can be applied and patterned to define any desired shape. Build area platform 22 can be integrated with the printing system or can be a component that can be separately inserted into the printing system. For example, build area platform 22 can be a module that is supplied separately from the printing system. The build material platform 22 shown is also an example and can be replaced by another support member, such as a platen, a manufacturing / printing bed, a glass plate, or another build surface.

[0084] Build area platform 22 receives build material composition 18 from build material supply 24. Build area platform 22 can move in the direction indicated by arrow 28, such as along the z-axis, so that build material composition 18 can be delivered onto build area platform 22 or onto a previously formed layer. In one example, when build material composition 18 is to be delivered, build area platform 22 can be programmed to advance sufficiently (e.g., downward) so that build material dispenser 26 can push build material composition 18 onto build area platform 22, or another dispenser can dispense build material composition 18 onto build area platform 22 to form a substantially uniform layer of build material composition 18 thereon. Build area platform 22 can also return to its original position, such as when a new part is to be built.

[0085] Build material supply 24 can be a container, bed, or other container or surface that delivers build material composition 18 to a suitable spreading location. In one example (not shown), Figure 3), build material supply 24 is a remote container that feeds build material composition 18 from above via a pipe or other conduit into a build material dispenser (e.g., a feeder blade). In some cases, build material supply 24 can be part of the build material dispenser and can therefore translate with the build material dispenser. In this example, the dispenser can move above and across build area platform 22 in the direction indicated by arrow 30, such as along the y-axis, to spread a layer 20 of build material composition 18 on build area platform 22. This enables continuous delivery of build material composition 18 to build area platform 22 rather than as Figure 3 2. Depicted in FIG. 2 is a supply from a single location on the side of the printing system. In this example, build material distributor 26 can also be used to level the dispensed layer 20.

[0086] exist Figure 3 In the example shown in , build material supply 24 includes a mechanism 21 (e.g., a delivery piston or pump) to provide (e.g., move) build material composition 18 from a storage location to a location to be spread onto build area platform 22 or onto a previously patterned layer. For example, Figure 3 As shown in , build material supply 24 can be a fixed container located on the side of the printing system, and its delivery mechanism 21 can push build material composition 18 to a certain position, where it can be spread on build area platform 22, for example, by build material distributor 26.

[0087] Build material distributor 26 may move over build material supply 24 and across build area platform 22 in the direction indicated by arrow 30, e.g., along the y-axis, to spread layer 20 of build material composition 18 on build area platform 22. Build material distributor 26 may also return to a position proximate to build material supply 24 after spreading build material composition 18. Build material distributor 26 may be a blade (e.g., a scraper), a roller, a combination of a roller and a blade, and / or any other device capable of spreading build material composition 18 on build area platform 22. For example, build material distributor 26 may be a counter-rotating roller.

[0088] One example of build material supply 24 may include a heater to heat build material composition 18 to a supply temperature of about 25° C. to about 150° C. In these examples, the supply temperature may depend in part on the build material composition 18 used and / or the 3D printer used. Therefore, the range provided is an example, and higher or lower temperatures may be used.

[0089] To generate layer 20 of build material composition 18, a controller (not shown) may process the data and, in response, build material supply 24 may deliver build material composition 18 to a dispenser, or may appropriately place particles of build material composition 18 for spreading by build material distributor 26. The controller may also process additional data and, in response, control build material distributor 26 to spread build material composition 18 on build area platform 22 to form layer 20 of build material composition 18 thereon. Figure 3 In the embodiment of the present invention, a building material layer 20 has been formed.

[0090] Layer 20 has a substantially uniform thickness on build area platform 22. In one example, build material layer 20 has a thickness of about 50 μm to about 950 μm. In another example, build material layer 20 has a thickness of about 30 μm to about 300 μm. It is understood that thinner or thicker layers may also be used. For example, build material layer 20 may have a thickness of about 20 μm to about 500 μm. For finer component definition, the layer thickness may be at least about 2x (i.e., 2 times) the average particle size of the polymer particles. In some examples, layer 20 thickness may be about 1.2x the average particle size of the polymer particles in build material composition 18.

[0091] After build material composition 18 has been applied and before further processing, build material layer 20 can be exposed to preheating. In one example, the preheat temperature can be below the melting point or melting range of the polymer particles of build material composition 18. As an example, the preheat temperature can be about 5°C to about 50°C lower than the lowest temperature of the melting point or softening range of the polymer material. In one example, the preheat temperature is about 50°C to about 205°C. In another example, the preheat temperature is about 100°C to about 190°C. It is to be understood that the preheat temperature can depend in part on the build material composition 18 used. Therefore, the ranges provided are some examples, and higher or lower temperatures can be used.

[0092] In other examples, build material layer 20 is not preheated, but rather maintained at room temperature.

[0093] When preheating is used, layer 20 may be preheated using any suitable heat source that exposes all build material compositions 18 in layer 20 to heat. Examples of heat sources include thermal heat sources (e.g., heaters (not shown) integrated into build area platform 22 (which may include sidewalls)) or radiation sources 32.

[0094] After layer 20 is formed and, in some cases, preheated, UV fusing agent 10 is selectively applied to at least some of build material composition 18 in layer 20 .

[0095] To form layer 34 of the 3D object, at least a portion (e.g., portion 36) of layer 20 of build material composition 18 is patterned with UV fusing agent 10. The volume of UV fusing agent 10 applied per unit of build material composition 18 in patterned portion 36 may be sufficient to absorb and convert sufficient UV radiation to cause coalescence / fusion of build material composition 18 in patterned portion 36. The volume of UV fusing agent 10 applied per unit of build material composition 18 may depend, at least in part, on the UV absorber (B vitamins and / or B vitamin derivatives) used, the UV absorber loading in fusing agent 10, and the build material composition 18 used.

[0096] Some portions 38 of build material layer 20 are not patterned by UV fusing agent 10 and therefore do not become part of final 3D object layer 34. However, thermal energy generated during UV radiation exposure may propagate into one or more surrounding portions 38 to which fusing agent 10 is not applied. An example of a detailing agent 14 disclosed herein may be selectively applied to one or more portions 38 of layer 20. Detailing agent 14 inhibits the propagation of thermal energy and thus helps prevent coalescence of one or more unpatterned build material portions 38.

[0097] After selectively applying UV fusing agent 10 and, in some cases, thinning agent 14 in one or more specific portions 36, 38 of layer 20, the entire layer 20 of build material composition 18 is exposed to ultraviolet electromagnetic radiation (at Figure 3 (shown as UV EMR in Figure 2).

[0098] Ultraviolet radiation is emitted by radiation source 32. The duration of application of ultraviolet radiation or energy exposure time may depend on one or more of: characteristics of radiation source 32; characteristics of build material composition 18; and / or characteristics of UV light fuse 10, for example.

[0099] It is to be understood that the ultraviolet radiation exposure can be completed in a single radiation event or in multiple radiation events. In one example, the ultraviolet radiation exposure of the build material layer 20 is completed in multiple radiation events. In a specific example, the number of ultraviolet radiation events is 3 to 8. In another specific example, the build material layer 20 can be exposed to electromagnetic radiation in 3 radiation events. It may be desirable to expose the build material layer 20 to ultraviolet radiation in multiple radiation events to counteract the cooling effect caused by the amount of reagents 10 and reagents 14 that may be applied to the build material layer 20. In addition, it may be desirable to expose the build material layer 20 to ultraviolet radiation in multiple radiation events to fully increase the temperature of the polymer build material composition 18 in one or more patterned portions 36 without overheating the build material composition 18 in one or more non-patterned portions 38.

[0100] The UV absorber (i.e., B vitamins and / or B vitamin derivatives) has a high efficiency temperature raising capability and thus enhances the absorption of UV radiation, converts the absorbed UV radiation into thermal energy, and promotes heat transfer to the polymeric building material composition 18 in contact therewith. In one example, the B vitamins and / or B vitamin derivatives in the UV fusing agent 10 sufficiently raise the temperature of the polymeric building material composition 18 in the portion 36 to a temperature at or above the melting point or softening range of the polymeric material to allow agglomeration / fusion (e.g., thermal merging, melting, bonding, etc.) of the polymeric building material composition 18 to occur. The application of UV radiation forms the 3D object layer 34.

[0101] In some examples, the ultraviolet radiation has a wavelength of 300 nm to 415 nm, or 350 nm to 405 nm, or 360 nm to 380 nm. Radiation having a wavelength within the provided ranges may be absorbed by the B vitamins and / or B vitamin derivatives in fusing agent 10 and may heat polymeric build material composition 18 in contact therewith, and is substantially not absorbed by non-patterned polymeric build material composition 18 in one or more portions 38.

[0102] After forming 3D object layer 26, one or more additional layers may be formed thereon to create an example of a 3D object. To form the next layer, additional polymeric build material composition 18 may be applied to layer 34. UV fusing agent 10 is then selectively applied to at least a portion of additional build material composition 18 in accordance with the 3D object model. Detailing agent 14 may be applied to any areas of additional build material composition 18 where coalescence is not desired. After applying UV fusing agent 10 and, in some cases, detailing agent 14, the entire layer of additional polymeric build material composition 18 is exposed to UV radiation in the manner described herein. The application of additional polymeric build material composition 18, the selective application of one or more agents 10, 14, and the UV radiation exposure may be repeated for a predetermined number of cycles in accordance with the 3D object model to form the final 3D object.

[0103] Thus, an example of method 100 includes iteratively applying polymeric build material composition 18 to form respective build material layers 20; selectively applying UV fusing agent 10 on respective build material layers 20 to form respective patterned portions 36; and exposing respective build material layers 20 to UV radiation.

[0104] If it is desired to change or enhance the color of the formed 3D object, a separate colored ink 16 may also be applied with the UV fusing agent 10 in one or more patterned portions 36. The colored ink 16 may be deposited in each layer or in the outermost layer. In this example, the colored ink 16 is embedded in the entire coalesced / fused build material composition of the 3D object layer 34. In other examples, the separate colored ink 16 may be applied to the surface of the final 3D object.

[0105] In the exemplary method 100, any of the agents (fusing agent 10, thinning agent 14, coloring agent 16) may be dispensed from an applicator. Figure 3 Two applicators 40, 40' are shown, dispensing the UV fusing agent 10 and the thinning agent 14, respectively. One or more applicators 40, 40' can each be a thermal inkjet printhead, a piezoelectric printhead, a continuous inkjet printhead, etc., and the selective application of one or more agents 10, 14, 16 can be achieved by thermal inkjet printing, piezoelectric inkjet printing, continuous inkjet printing, etc. It is understood that other applicators 40, 40' that can selectively dispense controlled amounts of one or more agents 10, 14 can be used.

[0106] The controller may process the data and, in response, control one or more applicators 40, 40' to deposit fusing agent 10 and detailing agent 14 onto one or more predetermined portions 36, 38 of polymeric build material composition 18. The controller may also process the data and, in response, control one or more applicators 40, 40' to deposit colorant 16. It is to be understood that applicators 40, 40' may be separate applicators or a single applicator having several separate cartridges to dispense the respective agents.

[0107] It is to be understood that the selective application of any reagent (e.g., UV fusing agent 10, thinning agent 14, etc.) can be done in a single print pass or in multiple print passes. In some examples, one or more reagents / one or more formulations are selectively applied in a single print pass. In other examples, one or more reagents are selectively applied in multiple print passes. In one of these examples, the number of print passes is 2 to 4. In other examples, 2 or 4 print passes are used. It may be desirable to apply UV fusing agent 10 in multiple print passes to increase the amount of, for example, UV absorbers applied to polymeric build material composition 18, avoid liquid splashing, avoid displacement of build material composition 18, etc.

[0108] In order to further illustrate the present disclosure, examples are given herein. It is to be understood that these examples are provided for illustration and should not be construed as limiting the scope of the present disclosure. Example

[0109] Example 1

[0110] Different B vitamins and B vitamin derivatives were used to generate several aqueous formulations. Each B vitamin or B vitamin derivative was dissolved in water. The absorbance behavior was then measured and the results are shown in Table 1.

[0111] Table 1

[0112]

[0113]

[0114] As shown, each B vitamin and B vitamin derivative exhibits absorption in the wavelength range of 325nm to 450nm. Based on these results, a UV LED radiation source having an emission at 365nm or 395nm may be suitable for use with most B vitamins and B vitamin derivatives in a 3D printing process. When a 365nm or 395nm UV LED radiation source is used with a flux containing pyridoxal HCl or pyridoxine HCl, additional B vitamins or B vitamin derivatives having a peak absorption at a wavelength above 350nm may need to be added to the flux. Alternatively, an increased UV intensity and / or UV dose may be used for a flux containing pyridoxal HCl or pyridoxine HCl.

[0115] Example 2

[0116] Exemplary UV fusing agents were prepared using two different types of aqueous carriers. The formulations of the exemplary agents are shown in Tables 2 and 3.

[0117] Table 2

[0118]

[0119]

[0120] Table 3

[0121]

[0122] An exemplary UV light fuser is used to generate a single 3D printed layer.

[0123] In some instances, the polymeric building material is polyamide-12, and in other instances, the polymeric building material is polypropylene. The building materials are laid down in thin layers. Respective exemplary UV fusing agents are inkjet printed in rectangular patterns on different building material layers. The fusing agent loading is approximately 1 drop / pixel (dpp) or 2 drops / pixel.

[0124] The patterned build material layer was kept at room temperature and exposed to UV radiation (395 nm, intensity = 12 W / cm 2or 10.8W / cm 2 ) for a period of 0.5 to 2 seconds. All patterned areas form 3D printed object layers, while non-patterned areas remain non-agglomerated powders. The 3D printed object layers are identified in Table 4 by the type of polymer building material used, the flux used, the flux loading, and the UV exposure conditions.

[0125] Table 4

[0126]

[0127] Photographs of the resulting 3D printed object layers and the non-patterned build material surrounding the 3D printed object layers were taken. These photographs are reproduced here in black and white. FIG. 4A to FIG. 4E Among them Figure 4A Displays 3D printed object layer 1 (originally yellow-light brown), Figure 4B Display 3D printed object layer 2 (originally grayish white). Figure 4C Displays 3D printed object layer 3 (originally yellow-light brown), Figure 4D Displays 3D printed object layer 4 (originally yellow), Figure 4E Displays 3D printed object layer 5 (originally light brown). Figure 4F 3D printed object layer 6 (original pink-light brown) is shown.

[0128] Overall, the 3D printed object layers were continuous, well-fused layers. As shown in the figure, each 3D object layer was moved from its original position, indicating that the mechanical strength of the 3D object layers was also high. These results indicate that the fusing agent carrier does not affect the absorption of various B vitamins or B vitamin derivatives.

[0129] The worst coalescence was shown for the exemplary 3D object layer 2 formulated with Example 2 UVFA (with pyridoxal HCl as the B vitamin derivative). This may be attributed to the weaker absorption of this B vitamin derivative at 395 nm than the other B vitamins or B vitamin derivatives used in this example (see Table 1).

[0130] FIG. 4A to FIG. 4E Each also depicts a scratch (or a portion of a scratch) in a non-patterned building material. This scratch was made to show that the non-patterned building material did not coalesce like the patterned building material. In addition, no changes (e.g., color) were observed in the non-patterned building material. This indicates that the building material was not adversely affected by UV exposure.

[0131] Example 3

[0132] Two different UV fusing agents were used in this example to illustrate that the degree of fusing / coalescence can be varied by varying the UV exposure conditions. In this example, Example 1 UVFA from Example 2 (containing folic acid, see Table 2) was used. An additional fusing agent was also prepared with folic acid. The formulation of this additional fusing agent is shown in Table 5.

[0133] Table 5

[0134]

[0135] Example 1 UVFA and Example 6 UVFA were used to generate a single 3D printed layer. In this example, the polymer building material was polyamide-12. The building material was laid out in a thin layer. Each exemplary UV light fuse was inkjet printed in a rectangular pattern on a different building material layer. The fuse loading was 2 dpp. The patterned building material layer was kept at room temperature and exposed to the same intensity (12 W / cm 2 ) for different times ranging from 0.4 seconds to 1 second. The 3D printed object layers are identified in Table 6 by the fusing agent and UV exposure time.

[0136] Table 6

[0137]

[0138]

[0139] Photographs were taken of the resulting 3D printed object layers and the non-patterned build material surrounding the 3D printed object layers. FIG. 5A to FIG. 5D Display 3D printed object layers 7-10 respectively, FIG. 6A to FIG. 6D 3D printed object layers 11-14 are shown respectively. Table 7 provides the colors of the 3D printed object layers.

[0140] Table 7

[0141] 3D Printed Object Layers Object color 7 Yellow-light brown 8 yellow 9 Light yellow 10 Light yellow 11 brown 12 Yellow-Brown 13 Yellow-light brown 14 yellow

[0142] Compare Figure 5A and Figure 5D and comparison Fig. 6A and Fig.6D It is clear that higher UV exposure times can lead to over-fused parts. 2 ), the exposure time can be reduced to obtain a 3D object with good fusion but no over-fusion.

[0143] Example 4

[0144] Any of the following parameters, such as UV irradiation intensity, B vitamin / B vitamin derivative loading and / or exposure time, can be adjusted for the specific B vitamin / B vitamin derivative used. The absorption characteristics of the B vitamin / B vitamin derivative can be considered to adjust the parameters and obtain a well-fused 3D object. To illustrate this, four more 3D object layers were printed using Example 1 UVFA.

[0145] For the other four 3D object layers, Example 1 UVFA was inkjet printed in a rectangular pattern on a polyamide 12 build material layer. The fusing agent loading was 2 dpp. The patterned build material layer was kept at room temperature and exposed to different intensities of ultraviolet radiation (395 nm) for the same or different times. These additional 3D printed object layers are identified in Table 8 by UV intensity and UV exposure time.

[0146] Table 8

[0147] 3D Printed Object Layers UV intensity UV exposure time 15 <![CDATA[12W / cm 2 ]]> 1 second 16 <![CDATA[10.8W / cm 2 ]]> 2 seconds 17 <![CDATA[9.6W / cm 2 ]]> 2 seconds 18 <![CDATA[8.4W / cm 2 ]]> 2 seconds

[0148] Photographs were taken of the resulting 3D printed object layers and the non-patterned build material surrounding the 3D printed object layers. FIG. 7A to FIG. 7D 3D printed object layers 15-18 are shown respectively. The colors of each 3D printed object layer 15-18 are off-white, light yellow, light yellow-light brown and light yellow respectively. These 3D object layers are well fused without over-fusion. By reducing the time ( Fig. 7A ) or by increasing the time when using lower UV intensities ( FIG. 7B to FIG. 7D ), the degree of fusion / coalescence can be well controlled to form beautiful and mechanically strong 3D printed parts.

[0149] 3D Object Layer 15( Fig. 7A ) is off-white in color. The color can be adjusted by using lower concentrations of folic acid. Lower concentrations can still produce well-fused 3D object layers, for example by heating the powder before and during UV exposure and / or by increasing the intensity of the UV source.

[0150] Overall, the 3D printed object layers generated in Examples 2-4 were continuous, well-fused layers. These results indicate that various B vitamins and B vitamin derivatives are suitable UV absorbers for 3D printing fusing agents.

[0151] Furthermore, in Examples 2-4, it is also noted that all of the exemplary fusing agents exhibited reliable inkjet printing, for example, in terms of decap, nozzle health, etc.

[0152] It is to be understood that the ranges provided herein include the specified range and any value or sub-range within the specified range, as if the value or sub-range were explicitly recited. For example, about 1 wt % to about 5 wt % should be interpreted as including not only the explicitly recited limits of about 1 wt % to about 5 wt %, but also individual values, such as about 1.25 wt %, about 2 wt %, about 3.7 wt %, about 4 wt %, etc., and sub-ranges, such as about 1.5 wt % to about 4.5 wt %, about 1 wt % to about 3.5 wt %, about 2.4 wt % to about 5 wt %, etc. In addition, when "about" is used to describe a value, this is intended to include minor variations (up to + / - 10%) from the specified value.

[0153] References throughout the specification to "one example," "another example," "an example," etc., mean 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 may or may not be present in other examples. Furthermore, it is to be understood that the elements described for any example may be combined in any suitable manner in the various examples unless the context clearly dictates otherwise.

[0154] In describing and claiming the examples disclosed herein, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise.

[0155] Although several examples have been described in detail, it is to be understood that the disclosed examples may be modified. Therefore, the above description should be regarded as non-limiting.

Claims

1. A three-dimensional (3D) printing kit, comprising: Ultraviolet (UV) light fusing agent, comprising: an aqueous carrier comprising a cosolvent, a surfactant and water; and a B vitamin or a B vitamin derivative present in an amount dissolved in an aqueous carrier, the B vitamin or B vitamin derivative having an absorption at a wavelength of about 340 nm to about 415 nm, wherein the B vitamin or B vitamin derivative is selected from riboflavin, folic acid, cyanocobalamin, pantothenic acid, biotin, pyridoxine, and combinations thereof and is present in an amount of about 1 wt % to about 5 wt % based on the total weight of the UV fusing agent; or The B vitamins or B vitamin derivatives are selected from flavin mononucleotides, pyridoxal phosphate hydrate, pyridoxal hydrochloride, pyridoxine hydrochloride, pyridoxamine and combinations thereof and are present in an amount of about 1 wt % to about 8 wt % based on the total weight of the UV fusing agent.

2. The kit of claim 1, wherein the UV fusing agent further comprises a base.

3. The kit of claim 1, wherein the UV fuser does not contain polymer molecules with adhesive moieties.

4. The kit as recited in claim 1, wherein the UV fusing agent further comprises an additive selected from the group consisting of an anti-fouling agent, a chelating agent, an antimicrobial agent, a buffer, and combinations thereof.

5. The kit as claimed in claim 1, wherein the UV fusing agent further comprises an additive selected from the group consisting of a pH adjuster, a preservative, and combinations thereof.

6. The kit of claim 1 further comprising a thinning agent comprising a second aqueous carrier and not comprising an absorber having absorption at a wavelength of about 340 nm to about 415 nm.

7. The kit of claim 1 further comprising colored ink.

8. A three-dimensional (3D) printing method comprising: applying a polymeric build material composition to form a build material layer; Based on the 3D object model, an ultraviolet (UV) light fusing agent is selectively applied to at least a portion of the layer of build material, the UV light fusing agent comprising: an aqueous carrier comprising a cosolvent, a surfactant and water; and a B vitamin or a B vitamin derivative present in an amount dissolved in an aqueous carrier, the B vitamin or B vitamin derivative having an absorption at a wavelength of about 340 nm to about 415 nm, wherein the B vitamin or B vitamin derivative is selected from riboflavin, folic acid, cyanocobalamin, pantothenic acid, biotin, pyridoxine, and combinations thereof and is present in an amount of about 1 wt % to about 5 wt % based on the total weight of the UV fusing agent; or wherein the B vitamin or B vitamin derivative is selected from flavin mononucleotide, pyridoxal phosphate hydrate, pyridoxal hydrochloride, pyridoxine hydrochloride, pyridoxamine, and combinations thereof and is present in an amount of about 1 wt % to about 8 wt % based on the total weight of the UV fusing agent; and The layer of build material is exposed to ultraviolet radiation to cause at least the portion to coalesce to form a layer of the 3D object.

9. The method of claim 8, further comprising: iteratively applying polymeric build material compositions to form respective build material layers; selectively applying an ultraviolet light fusing agent on respective building material layers to form respective patterned portions; and The respective build material layers are exposed to ultraviolet radiation.

10. A three-dimensional (3D) printed article produced by the method of claim 8.

Images