Three-dimensional object by inkjet printing

Abstract

Provided herein is a method of forming a three-dimensional object on a substrate using multiple liquid inkjet compositions, machinery, and multiple methods without multiple dry powders or multiple ultraviolet curing agents. According to the additive method, the three-dimensional object is digitally printed by inkjet printing a top layer on a base layer before curing the base layer, to form a layer with a gel, and subsequently curing the gel object.

Description

[0001] Cross-references to related applications

[0002] This application claims priority to U.S. Provisional Patent Application No. 63 / 131,343, filed December 29, 2020, the entire contents of which are incorporated herein by reference.

[0003] Technical Field and Background Art of the Invention

[0004] In some embodiments of the present invention, the present invention relates to three-dimensional (3D) printing, and more specifically, but not exclusively, to methods of printing 3D objects by inkjet standard methods, mechanics, and compositions.

[0005] The concept of inkjet printing was first proposed by Lord Rayleigh in 1878, and Siemens obtained a patent for the first two-dimensional inkjet printer in 1951, called the Rayleigh decomposed inkjet device. Since then, 3D inkjet printing has been conceptualized and put into practice, but it remains primarily a powder-based method (aka the MIT method), in which layers of solid particles, typically 200 micrometers (μm) high and ranging in size from 50 to 100 μm, are bonded together by a printed liquid material to create a 3D model. In powder-based techniques, a first layer of powder is uniformly distributed, for example, by rollers on top of a support platform, after which the inkjet print head prints droplets of liquid binder onto the desired curing areas of the powder layer. Once the first layer is complete, the platform drops, and a second powder layer is distributed and selectively bonded with the printed binder. These steps are repeated until a 3D model is generated, after which the model is typically heat-treated to enhance the bonding of the powder in the desired areas. Unbonded powder acts as a support material during processing and is removed after manufacturing.

[0006] In thermal phase change technology, a waxy material that is solid at room temperature is melted and deposited onto a substrate via inkjet printing. The wax solidifies upon cooling, and a new layer of liquid wax is then deposited. The support structure is constructed in the same way as the model building layers, using the same materials. The main disadvantages of this technology are relatively poor surface quality, difficulty in removing the support, and the poor mechanical properties of the wax materials used.

[0007] In the PolyJet method, selective inkjet deposition and immediate curing of a UV-curable liquid composition are used to form slices layer by layer by exposure to pan-ultraviolet radiation. The support structure is constructed in the same way as the 3D object slices, but using different materials. The support material is typically a UV-curable gel material that can be easily removed, leaving a well-defined and smooth object surface. Because PolyJet has proven to overcome many traditional drawbacks of existing 3D printing methods, it has become the dominant method in 3D inkjet printing.

[0008] Despite numerous improvements and different methods developed over the years, a system capable of constructing objects using multiple modeling materials simultaneously was not available until a decade ago. In November 2007, Israel's Objet Geometry Ltd. unveiled a new technological breakthrough that allows the simultaneous use of two UV-cured modeling materials to construct complex components and structures. Furthermore, as Objet Geometry Ltd. claims, this new technology also offers the possibility of constructing composite or digital materials.

[0009] U.S. Patent No. 7,134,749 discloses a method and apparatus for color printing on dark textiles, the method comprising the steps of: directly digitally applying a layer of white ink to the textile, and digitally printing a color image on the white ink layer prior to curing the white ink. The limitation of this technique is that it is only suitable for synthetic fabrics dyed with disperse dyes, wherein the dye migrates to the white underlayer and colors it during the image curing step.

[0010] U.S. Patent No. 9,624,390 discloses a method for inkjet printing an image on a dyed synthetic textile substrate. The method includes modifying the synthetic textile to exhibit negatively charged functional groups, thereby obtaining a modified synthetic textile substrate; dyeing the modified synthetic textile substrate to obtain a dyed modified synthetic textile substrate; contacting at least a portion of the surface of the modified substrate with a fixing composition comprising an acid to obtain a wetted portion of the modified substrate; directly inkjet printing a colored ink composition and / or an opaque white base ink composition onto the wetted portion to form an image; and curing the image. A limitation of this technique is the need for fabric pretreatment, which increases processing time and cost, and it may not be suitable for all synthetic fibers.

[0011] WIPO Patent Application No. WO / 2018 / 138720 discloses an ink assembly designed for printing on dyed synthetic fabrics, comprising a fixative composition and at least one ink composition, said ink composition containing dispersed pigments and / or dyes, a low-temperature curing self-crosslinking resin, and an aqueous carrier, and formulated to exhibit an alkaline pH higher than 7; said fixative composition containing an acid and an aqueous carrier, and formulated to exhibit an acidic pH lower than 7, said ink assembly for direct digital inkjet printing of color images onto dyed substrates, wherein the low-temperature curing self-crosslinking resin is a pH-sensitive low-temperature curing self-crosslinking resin that initiates a crosslinking reaction at temperatures below typical curing temperatures, ranging from 90°C to 110°C. A limitation of this technology is the cost of such a low-temperature curing self-crosslinking resin, and its applicability to all synthetic fabrics, even at low curing temperatures of 100 to 110°C, which may be affected by dye migration due to the quality of the fabric dyeing process or other properties, ink composition, and customer requirements.

[0012] Other prior art documents include U.S. Patents Nos. 4,575,330, 5,387,380, 5,733,497, 5,855,836, 6,569,373, and 7,300,619. Summary of the Invention

[0013] This invention provides a solution to problems related to the flowability and key properties of inkjet compositions used in digital inkjet printing, which hinder the use of such compositions and techniques for three-dimensional (3D) objects. As is known in the art, inkjet compositions must meet certain rheological requirements, which are disadvantageous for additive methods in 3D object printing. However, this invention teaches the formation of each layer of the resulting object using a two-part jetting reaction while these layers remain wet and uncured, utilizing the same properties to form complex, high-resolution 3D objects on any substrate, including uneven and absorbent surfaces such as fabrics. Each layer is formed by inkjet printing a layer-forming composition and a jetting composition, with the layer-forming composition gelling upon contact with the gelling composition on the substrate (or the previous layer). The 3D object is formed by adding layers sequentially while all layers are still wet (uncured), and finally by thermally curing the object.

[0014] Therefore, according to one aspect of some embodiments of the present invention, a method is provided for printing or otherwise forming a three-dimensional solid object on the surface of a substrate, which is performed by:

[0015] (a) Using a layering composition and a gel composition, a pattern is inkjet printed on a region of the surface to form a first gel layer;

[0016] (b) Repeat step (a) on the first gel layer to form a second gel layer on the first gel layer;

[0017] (c) Repeat step (b) n times to form an nth gel layer on the second gel layer, thereby forming a three-dimensional gel object, where n is an integer equal to or greater than 1; and

[0018] (d) Solidify the three-dimensional gel object to form the three-dimensional object.

[0019] According to some embodiments of the present invention, the thickness / height of each of the first gel layer, the second gel layer and the nth gel layer is independently at least 10 micrometers (μm).

[0020] According to some embodiments of the present invention, the spatial resolution of the identifiable structural features in the three-dimensional gel object is at least 0.1 millimeters (mm).

[0021] According to some embodiments of the present invention, n is greater than 2 or greater than 4.

[0022] According to some embodiments of the invention, each of the layered composition and the gel composition is substantially free of a UV-curable agent.

[0023] According to some embodiments of the present invention, the layered composition comprises a pigment.

[0024] According to some embodiments of the invention, the pigment is opaque.

[0025] According to some embodiments of the invention, the concentration of the opaque pigment is 1 to 40 wt%.

[0026] According to some embodiments of the invention, the pigment is translucent.

[0027] According to some embodiments of the invention, the concentration of the translucent pigment is 2 to 30 wt%.

[0028] According to some embodiments of the invention, the layering composition comprises a gelling agent that coagulates at a pH less than 7, upon contact with cations, or upon contact with metal oxides.

[0029] According to some embodiments of the invention, the gelling agent is selected from the group consisting of pH-sensitive alkali-soluble polymers, which are selected from the group consisting of polyacrylate, polyurethane, polyester, polybutadiene, polyvinyl chloride, polyvinyl alcohol, polyvinyl acetate, polyimine, and any mixtures and / or copolymers thereof.

[0030] According to some embodiments of the invention, the concentration of the gelling agent in the layered composition is from 0.1 to 30 wt%.

[0031] According to some embodiments of the invention, the layering composition further comprises a non-coagulating film-forming agent at a concentration of 0 to 30 wt%.

[0032] According to some embodiments of the invention, the gelling agent is selected, and / or the non-coagulating film-forming agent is selected when present, such that an independently cured 1 mm thick film exhibits an elongation factor of at least 5%, the independently cured 1 mm thick film being formed from the layering composition comprising the gelling agent and / or the non-coagulating film-forming agent.

[0033] According to some embodiments of the present invention, the viscosity of the layered composition at 25°C is 4 to 25 cps.

[0034] According to some embodiments of the present invention, the maximal dispersed particle size in the layered composition is less than 5 μm.

[0035] According to some embodiments of the invention, the layered composition is printed in droplet sizes of 10 to 120 picoliters (pl).

[0036] According to some embodiments of the invention, the gel composition comprises a gelling initiator selected from the group consisting of acids, divalent cations, and metal oxides.

[0037] According to some embodiments of the invention, the concentration of the gel initiator in the gel composition is from 0.1 to 20 wt%.

[0038] According to some embodiments of the invention, the gel initiator is a transient acid, and the pH of the gel composition is from 3 to 6.5.

[0039] According to some embodiments of the invention, the layering composition is applied before, simultaneously with, or after the application of the gel composition.

[0040] According to some embodiments of the invention, the method is performed on an absorbent substrate for each of the layered composition and the gel composition, and prior to step (a), it further includes applying a base jelling composition to the surface of the substrate.

[0041] According to some embodiments of the present invention, the base gel composition is at a concentration of 5 to 50 mg / cm². 2 Apply the amount of )

[0042] According to some embodiments of the present invention, step (d) of the method is performed by heating the three-dimensional gel object to a temperature of 90 to 200°C.

[0043] According to some embodiments of the present invention, the method is essentially a curing process without photoinitiation, propagation, and / or any UV light influence.

[0044] According to another aspect of some embodiments of the present invention, a substrate having a 3D object on its surface is provided, said substrate having a 3D object on its surface is obtained by the methods provided herein.

[0045] According to some embodiments of the invention, the three-dimensional object can be stretched to at least 5% longitudinal elongation before breaking or separating from the surface.

[0046] According to some embodiments of the present invention, the height (Z-axis) of the three-dimensional object is at least 30 μm, 40 μm, 50 μm or at least 60 μm.

[0047] According to some embodiments of the present invention, the substrate used in the methods provided herein is selected from the group consisting of absorbent materials, non-absorbent materials, flexible materials and stretchable materials.

[0048] According to some embodiments of the present invention, the absorbent material is a fabric.

[0049] According to some embodiments of the present invention, there are essentially no layer markings on or within the three-dimensional object.

[0050] According to some embodiments of the present invention, the three-dimensional object includes at least one distinguishable layer.

[0051] According to another aspect of some embodiments of the present invention, a three-dimensional object is provided, which is obtained by the method of any one of claims 1-26, and can also be obtained by separating the object from the substrate.

[0052] According to some embodiments of the invention, the object exhibits a height of at least 50 μm.

[0053] According to some embodiments of the invention, the three-dimensional object can be stretched to at least 5% longitudinal elongation before fracture.

[0054] According to some embodiments of the invention, there are substantially no layer markings on or within the object.

[0055] According to some embodiments of the invention, the object comprises at least one identifiable layer.

[0056] According to another aspect of some embodiments of the present invention, a three-dimensional gel object is provided, comprising a jetted layer-forming composition of at least three layers of gel.

[0057] According to some embodiments of the invention, the layered composition in the gel object is gelled by contact with the gel composition.

[0058] According to some embodiments of the present invention, at least one of the plurality of layers in the gel object is characterized by at least one property that is different from the properties of the other layers.

[0059] According to some embodiments of the present invention, the property is color.

[0060] According to some embodiments of the present invention, the gel object is in contact with the surface of the substrate.

[0061] According to another aspect of some embodiments of the present invention, a three-dimensional solid object is provided comprising at least three layers of a cured layered composition.

[0062] According to some embodiments of the present invention, at least one layer of the solid object is characterized by at least one property that is different from the properties of the other layers.

[0063] According to some embodiments of the present invention, the property is color.

[0064] According to some embodiments of the present invention, the solid object is in contact with the surface of the substrate.

[0065] Unless otherwise defined, all technical and / or scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. Although methods and materials similar to or equivalent to those described herein may be used in the practice or testing of embodiments of the invention, exemplary methods and / or materials are described below. In case of conflict, the patent specification (including definitions) shall prevail. Furthermore, materials, methods, and embodiments are illustrative only and are not intended to be necessarily limiting. Attached Figure Description

[0066] This document describes some embodiments of the invention by way of example and with reference to the accompanying drawings. Reference will now be made in detail to the drawings, emphasizing that the details shown are by way of example and are intended to illustrate embodiments of the invention. In this respect, the description taken in conjunction with the drawings will make it apparent to those skilled in the art how to practice the embodiments of the invention.

[0067] In the attached image:

[0068] Figures 1A to 1D A schematic diagram of the steps in the method provided herein according to some embodiments of the present invention is shown, wherein... Figure 1A The steps following the formation of the first gel layer 11 are shown; Figure 1B The steps following the formation of the second gel layer 12 are shown; Figure 1C The diagram shows the three-dimensional (3D) gel object after printing the nth gel layer 13 and additive layers 14 to 16; and Figure 1D A solid object 17 on the substrate is shown after the curing step;

[0069] Figure 2 A schematic diagram illustrating a value for defining the resolution of a 3D object according to an embodiment of the invention is presented, wherein distance 21 determines the spatial resolution (d) of the object. c ) is defined as the minimum distance between gel structure feature 22 and gel structure feature 23 that can be achieved without coalescing;

[0070] Figure 3 It is a black and white photograph of a fabric substrate on which several 3D objects in the form of letters and horizontal parallel lines are printed, showing the three-dimensional conical structure in the objects, indicating that these layers are printed from a series of layers from large areas in the bottom layer to small areas in the next layer.

[0071] Figures 4A to 4CPresented on a PET film (non-absorbent substrate); Figure 4A ), on cotton clothing (absorbent substrate; Figure 4B ) and with Figure 4B The same pattern but without printing the gel composition pattern on the substrate or between layers. Figure 4C A photograph of a parallel line pattern;

[0072] Figures 5A to 5C Photographs of an 8-layer pattern printed using an intermediate layer (FOF) gel composition but without a base layer (FIXA) gel composition are presented. Figure 5A The same 8-layer pattern was printed using a base (FIXA) gel composition but without an intermediate layer (FOF) gel composition. Figure 5B ); and the same 8-layer pattern printed using a base (FIXA) gel composition and an intermediate layer (FOF) gel composition. Figure 5C );and

[0073] Figure 6 A cross-sectional photograph of a 12-layer 3D object printed on cotton clothing is presented, showing an average thickness of approximately 240 micrometers (μm). Detailed Implementation Plan

[0074] In some embodiments of the present invention, the present invention relates to three-dimensional (3D) printing, and more specifically, but not exclusively, to methods of printing 3D objects by inkjet standard methods, machinery, and compositions.

[0075] The principles and operation of this invention can be better understood by referring to the accompanying drawings and descriptions.

[0076] Before explaining at least one embodiment of the present invention in detail, it should be understood that the invention is not necessarily limited in its application to the details set forth in the following description or illustrated by the examples. The invention can have other embodiments, or can be practiced or implemented in various ways.

[0077] The fashion industry has long needed a method for 3D relief printing on fabrics with high resolution and acceptable durability. Problems associated with 3D printing using digital inkjet printing stem from a combination of surface absorption and ink composition rheological requirements, the latter being detrimental to additive 3D printing methods unless each layer cures before the next.

[0078] In conceiving this invention, the inventors envisioned an intermediate stage of instantaneous semi-solidification (jellification) of layers, which would allow the entire object to be formed before final solidification takes effect, thereby eliminating the time-consuming and energy-inefficient requirement of curing each layer at once, while preventing structural collapse (Z-axis), pattern feature joining (X / Y-axis), and maintaining high-resolution continuous 3D objects.

[0079] While two-layer gel inks have been widely adopted, the successful layering of more than two layers of wet gel inks is surprising, and even more surprising is the ability to produce more than 12 layers of 3D objects with high spatial resolution using inkjet methods.

[0080] An inkjet method for printing 3D objects:

[0081] Therefore, according to some aspects of this disclosure, a method for forming a three-dimensional (3D) object on the surface of a substrate is provided. In the context of this invention, the final 3D object is a solid object that can exhibit a range of mechanical properties, such as elasticity, brittleness, texture, as well as color, shape, and size, depending on the printing composition and printing pattern.

[0082] In some implementations, the method is performed step-by-step through the following steps:

[0083] (a) Using a layering composition and a gel composition, a pattern is inkjet printed on a region of the surface to form a first gel layer;

[0084] (b) Repeat step (a) on the first gel layer to form a second gel layer on the first gel layer;

[0085] (c) Repeat step (b) n times to form the nth gel layer on top of the previous (second) gel layer, thereby forming a three-dimensional gel object, where n is an integer equal to or greater than n; and

[0086] (d) Solidify the three-dimensional gel object to form the 3D object.

[0087] Figures 1A to 1D A schematic diagram of the steps in the method provided herein according to some embodiments of the present invention is shown, wherein... Figure 1A The steps following the formation of the first gel layer 11 are shown. Figure 1B The steps following the formation of the second gel layer 12 are shown. Figure 1C The 3D gel object after printing the nth gel layer 13 and additive layers 14-16 is shown, and Figure 1D The solid object 17 on the substrate is shown after the curing step.

[0088] As used herein, the term "gelatinous" is an adjective referring to the consistency, texture, and general mechanical properties of a substance. A gel is a semi-solid material with a jelly-like consistency and / or viscosity. In the context of this invention, the term "gel" is used to refer to a pre-cured / uncured object being printed, which differs from a cured object, which is a hard or elastic solid but not a gel.

[0089] According to some embodiments of the invention, a layered composition is applied / printed before, together with, or after the application of a gel composition. In some embodiments, particularly when using an absorbent substrate, the first step of the method may be to apply a base gel composition before applying the layered composition to reduce absorption / soaking / exudation / wicking and to smooth some uneven surfaces of the substrate. The base gel composition is substantially similar to, and sometimes identical to, the gel composition, the former referred to herein as “FIXA” and the latter as “FOF” (further details below).

[0090] Inkjet printing is characterized by high resolution, stemming from its ability to eject extremely small droplets through a precisely and repeatably positioned printhead. This high-resolution characteristic of two-dimensional (2D) inkjet printing has been remarkably reproduced and is applicable to currently disclosed 3D processes, according to several implementations.

[0091] In the context of embodiments of the present invention, the resolution of the resulting 3D object corresponds to the resolution of the printed pattern in each layer. The limitation on the resolution of the object's structural features stems from the undesirable tendency for adjacent gel-like (semi-liquid / solid) features of the pattern to contact and coalesce. According to embodiments of the present invention, one criterion for defining the spatial resolution of structural features in a 3D object printed by this method is the minimum distance between adjacent features at the substrate on the object, i.e., the minimum distance between two distinguishable features in the first layer, which can be printed on the substrate without coalescing, such as... Figure 2 As shown.

[0092] Figure 2 A schematic diagram illustrating a value for defining the resolution of a 3D object according to an embodiment of the invention is presented, wherein distance 21 determines the spatial resolution (d) of the object. c ) is defined as the minimum distance between gel structure feature 22 and gel structure feature 23 that can be achieved without coalescing.

[0093] According to some embodiments, and according to embodiments of the present invention, the spatial resolution (d) characterizing the distinguishable structural features of the 3D printing process is... cThe minimum distance between the gel structure features is 0.1 mm. This value may depend on factors other than the printer and printing composition, such as the type of material, the temperature of the printing environment, and stillness, which also affect the nature of the gel structure features and therefore the minimum distance between these features before curing.

[0094] One of the surprising discoveries made by the inventors in putting this invention into practice is the number of printable layers—the number of layers that can be printed one after another while all layers are still uncured (still wet) without any collapse of the gel structure (gel 3D object). Therefore, in some embodiments, n (the number of layers beyond the first and second layers) is greater than 1, or greater than 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 25, 30, 40, or greater than 50 wet layers before curing.

[0095] The process described herein differs fundamentally from known inkjet-based 3D printing methods, in which each layer is typically cured by ultraviolet (UV) radiation before the next layer is placed on top. The method disclosed herein differs in that the object is fully formed by all layers before curing, and all layers are still in a gel-like (wet) state. Although as stated above, the invention is not limited to curing gel 3D objects; gel 3D objects can be formed as described, and curing can be achieved, for example, by UV radiation, provided that the UV curing agent is part of the layered composition.

[0096] In some embodiments of the invention, each of the layered composition and the gel composition is substantially free of UV curing agents. In some embodiments of the invention, the method involves curing that is substantially free of photoinitiated, propagated, and / or otherwise photo-affected curing.

[0097] In some embodiments of the invention, curing (“step (d)”) is performed by heating the three-dimensional gel object to a temperature of 90 to 200°C, 140 to 180°C, or about 160°C. In some embodiments in which the layering composition comprises a low-temperature curing crosslinking agent, the curing step may be performed at a temperature below 120°C or below 100°C.

[0098] Layer-forming composition:

[0099] Typically, according to embodiments of the invention, the layering composition is an aqueous suspension / emulsion / solution that meets all the requirements of inkjet ink compositions in terms of rheology, viscosity, particle size, conductivity, reactivity / inertness, and stability, as known in the art. According to some embodiments of the invention, compositions that cannot be ejected from an inkjet printhead (as known in the art, "inkjet printhead") based on any of the foregoing requirements are excluded from the scope of the term "layering composition." For example, compositions comprising dry powder that forms layers in some additive 3D printing methods, and / or compositions that do not exhibit a viscosity suitable for ejection from an inkjet printhead (too thick or too thin), are not included in the term "layering composition."

[0100] For example, in some embodiments of the invention, the viscosity of the layered composition is in the range of 4 to 25 cps or 4 to 20 cps, and / or the maximum dispersed particle size in the layered composition is up to 5 micrometers (μm).

[0101] In some embodiments, the layered composition is an inkjet ink composition, which in this sense includes all elements of an inkjet ink composition in terms of composition and properties. Therefore, the layered composition may include any one or more of colorants, resins, humectants, co-solvents, surfactants, defoamers, rheology modifiers, biocides / fungicides, and carriers / solvents (i.e., water).

[0102] Alternatively, the layered composition is a colorless, substantially transparent composition that forms a colorless, substantially transparent layer of material in the final 3D object.

[0103] A layered composition includes one or more components that form a film upon curing, such as a film-forming agent. The term "film-forming agent" is used herein in its industrial sense. A film formed by a film-forming agent in a layered composition corresponds to a monolayer or layer in the final 3D object. A film-forming agent is a group of substances that, when applied to a substrate surface, leave a flexible, tacky, and continuous cover / coating on the substrate. In the context of embodiments of the invention, non-limiting examples of substances that can be used as film-forming agents include (poly)acrylates, (poly)urethanes, (poly)acrylamide, polyvinylpyrrolidone (PVP), polysiloxanes, and copolymers thereof.

[0104] When formulating a film-forming composition, the film-forming agent in the composition can be selected based on its properties of interacting with light, such as transparency / opaqueness / turbidity, refraction, reflection, absorbance, luminescence, phosphorescence, fluorescence, etc.

[0105] When formulating a laminating composition, the film-forming agent in the composition can be selected according to the desired mechanical properties of the resulting film, which will affect the mechanical properties of the 3D object. Therefore, the laminating composition can be particularly defined by the mechanical properties of the independently cured film it provides. For example, the laminating composition is defined by an elongation factor of at least 5%, 10%, 20%, 30%, 40%, 50%, or at least 100%, which is exhibited by the independently cured film of 0.5 mm thickness it provides.

[0106] In this respect, film-forming agents can be defined by the mechanical properties exhibited by the individual films made from them. For example, a layered composition comprising a primary film-forming agent is characterized by forming a film with the desired T0. g (e.g., -30 to 0°C) stand-alone films. Alternatively, the film-forming agent may be characterized by an elongation factor (e.g., at least 5%, 10%, 20%, 30%, 40%, 50%, or at least 100%), which is exhibited by stand-alone films (e.g., 0.5 mm thick) formed from a layered composition containing the film-forming agent as a major component.

[0107] In the context of embodiments of the present invention, the film-forming agent may be a non-coagulating film-forming agent, i.e., the layering composition may include a non-coagulating film-forming agent and a coagulating film-forming agent used as a gelling agent. The non-coagulating film-forming agent contributes to the bulk of the layer and imparts mechanical properties to the resulting 3D object, and is used at a concentration of 0 to 30 wt%, 0 to 20 wt%, 0 to 10 wt%, or 0 to 5 wt% of the total weight of the composition.

[0108] According to some embodiments of the invention, the amount of the layering composition printed for each layer corresponds to the desired thickness of the layer, which also depends on the concentration / amount of the film-forming agent in the layering composition. Typically, due to the technical complexities associated with physical measurements, the thickness of the gel layer is not measured prior to the curing step; however, shrinkage due to curing has been observed to be almost negligible or very small, therefore, for the sake of simplicity and flowability in this specification, the thickness of the gel layer is comparable to the thickness of the cured layer, and thus they are referred to interchangeably herein.

[0109] In some embodiments, the layered composition is printed in amounts ranging from 10 to 120 picoliters (pl) droplet sizes. Printing of the layered composition typically produces a gel layer and / or a cured layer with a thickness (i.e., height) of about 10 to 60 μm.

[0110] According to some implementation schemes, before or after the curing step, the thickness / height of the monolayer is at least 10 μm, or at least 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, or at least 50 μm.

[0111] Therefore, the height of the 3D object printed by the method provided in this paper is at least 30μm, 35μm, 40μm, 45μm, 5μm, or at least 60μm.

[0112] Gel agent:

[0113] According to some embodiments of the present invention, the 3D object is formed layer by layer from a layered composition comprising a substance that undergoes coagulation upon contact with a gelling initiator, referred herein as a gelling agent.

[0114] A gelling agent can be a film-forming agent (coagulating film-forming agent), resin / binder or dispersant, wetting agent, cosolvent, surfactant, rheology modifier, or any other component of a layered composition, provided that it is sensitive to a gel initiator, as the gel initiator causes the layered composition to coagulate upon contact with the gel initiator. Without being bound by any particular theory, it should be noted that upon contact with a gel initiator, the gelling agent loses its solubility in the carrier of the ink composition (the gelling agent becomes insoluble in the carrier), at least to a certain extent sufficient to cause cogelation / coagulation of the layered composition.

[0115] According to some embodiments, coagulation can be provided by adding one or more alkali-soluble gelling agents (e.g., acid-sensitive, cation-sensitive, or metal oxide-sensitive gelling agents), peptide-based gelling agents (e.g., acid-sensitive gelling agents), and polysaccharide-based gelling agents (e.g., divalent metal cation-sensitive gelling agents, or combinations thereof) to the layered composition. According to some embodiments of the invention, the gelling agent is an alkali-soluble gelling agent or an acid-sensitive gelling agent, in which case the pH of the layered composition is neutral (pH = 7) or higher, or the pH range is 7 to 10, 8 to 9, or 8 to 8.5.

[0116] In some embodiments, the gelling agent is an alkali-soluble gelling agent that can be associated with the dispersed pigment, an alkali-soluble gelling agent that is not associated with the dispersed pigment, or a combination thereof. For example, the surfactant, dispersant, or hydrophilic portion can be an alkali-soluble gelling agent that is sensitive to pH reduction, for example, in the presence of an acid, whereby the acid-containing layer-curing composition coagulates (experiencing a sharp increase in viscosity) upon contact with the acid to form a gel layer.

[0117] According to some embodiments of the invention, experiments have determined that the total amount of gelling agent in the layered compositions presented herein is sufficient to gel the layer. According to some embodiments, the amount / concentration of the gelling agent in the layered composition is 0.1 to 30, 1 to 30, 2 to 20, or 5 to 20 wt% of the total weight of the composition. Alternatively, the concentration of the gelling agent in the layered composition is greater than about 1% of the total mass of the composition, or at least 0.1%, 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, or 30%.

[0118] In the context of this invention, a gelling agent that is sensitive to acid so that contact with acid causes the layered composition to coagulate is also called an alkali-soluble gelling agent. According to embodiments of the invention, the alkali-soluble gelling agent includes an alkali-soluble dispersant, an alkali-soluble surfactant, an alkali-soluble polymer, an alkali-soluble resin, an alkali-soluble film-forming agent, and an alkali-soluble binder.

[0119] According to some embodiments, the alkali-soluble agent is an alkali-soluble polymer, such as an alkali-soluble acrylic polymer or an alkali-soluble coacrylic polymer, such as a poly(styrene / acrylic) polymer. It is noted herein that, without being bound by any particular theory, alkali-soluble acrylic or coacrylic polymers are soluble under alkaline conditions where the carboxyl groups in the polymer are charged; consequently, acidification of the aqueous medium containing the alkali-soluble polymer neutralizes the charged groups, resulting in a loss of solubility in the aqueous medium. In some embodiments, the alkali-soluble gelling agent is selected from the group consisting of emulsified / dispersed polyacrylates, polyurethanes, polyethers, polyesters, polyvinyl chloride, polyvinyl acetate, polyvinyl butyral, aminosilicone polymers, polybutadiene, polyvinyl alcohol, polyvinyl acetate, polyimides, and any salts, copolymers, and / or combinations thereof. Commercially available alkali-soluble polymers include Joncryl 586, Joncryl 678, Joncryl 96, Joncryl 296, and Joncryl 538.

[0120] In the context of some embodiments of the present invention, alkali-soluble (acid-sensitive) surfactants include cationic surfactants. Exemplary cationic surfactants include, but are not limited to, commercially available surfactants such as BYK's Series, BYK 3XX series, Air products Series, BASF and series.

[0121] According to some embodiments of the invention, the pH of the layered composition is maintained above neutral pH, i.e., the pH of the layered composition is higher than 7, higher than 7.5, higher than 8, higher than 8.5, higher than 9, higher than 9.5, higher than 10, higher than 10.5, or higher than 11. The pH of the layered composition can be set by the amount of all the alkaline substances therein, and can be further maintained at the desired level by using alkaline pH adjusters such as bases and / or buffers. Typically, the pH can be set to an alkaline level by using organic amines and / or ammonium hydroxide.

[0122] In some embodiments, the gelling agent is sensitive to the presence of divalent or polyvalent ions. For example, soluble salts of alginate (e.g., sodium alginate) are sensitive to calcium ions (Ca ions). 2+ It is sensitive to the presence of (used as a gel initiator) and forms calcium alginate gel upon contact.

[0123] Other gelling agents include alginate, sodium alginate, potassium alginate, ammonium alginate, calcium alginate, and other polysaccharides derived from brown algae; agar and other polysaccharides derived from red algae; carrageenan and other polysaccharides derived from red algae; locust bean gum and other gum polysaccharides derived from carob seeds; pectin and other polysaccharides extracted from fruits; and non-toxic gelling agents such as gelatin of plant or animal origin.

[0124] Colorant:

[0125] The layered composition may contain a colorant (coloring agent). Preferably, the layered composition contains pigments, which are essentially a large number of insoluble fine particles that remain suspended / dispersed in the composition and are trapped in the cured film / layer after curing, i.e., fixed to the surface of the substrate by an adhesive, resin, or binding agent.

[0126] In some implementations, the colorant is a dye, or a combination of dye and pigment.

[0127] In many inkjet applications, the most common reason for replacing dyes with pigments is lightfastness, also known as resistance to UV fading. Dyes can produce intense colors, but the saturation of these colors changes over time and they are easily oxidized and faded by UV exposure in sunlight. Print durability is an important consideration for preserving records, and the increased use of pigment colorants helps inkjet compete with electrophotography in this regard. In the context of embodiments of the present invention, pigments also play a role in providing the body and texture of the layers that constitute the 3D object, as discussed herein. The use of pigments in the context of the present invention is advantageous because pigments can be selected or combined to have / produce any color and are opaque or translucent. However, the present invention is not limited to layered compositions comprising pigments, as in some embodiments, dyes can also play a role in the formation and coloring of the final 3D object.

[0128] In the context of some embodiments of the present invention, 3D objects are formed from multiple layered compositions, each containing or not containing a different pigment, similar to inkjet inks used to form 2D images. Generally, each layer of a 3D object can be considered a 2D image, and the appearance and texture of the object are derived from the combination of these layers.

[0129] When formulating layered compositions, the colorants in the composition can be selected based on their photo-interaction properties, such as transparency / opaqueness / turbidity, refraction, reflectivity, absorbance, luminescence, phosphorescence, fluorescence, etc. For example, the pigments can be selected to be opaque or translucent, thereby producing opaque or translucent layers respectively. Additionally, layers containing metallic ink pigments in combination with translucent layers can be used to provide additional special light-reflecting effects, as discussed below.

[0130] According to some embodiments of the invention, the concentration of the opaque pigment in the layered composition ranges from 1 to 40 wt% or 2 to 30 wt% of the total weight of the composition.

[0131] According to some embodiments of the invention, the concentration of the translucent pigment in the layered composition ranges from 2 to 30 wt% of the total weight of the composition, or from 2 to 10 wt%.

[0132] Gel composition:

[0133] According to some embodiments of the invention, the layered composition undergoes gelation, which is necessary for forming 3D objects according to embodiments of the invention. The methods and compositions provided herein are based on the ability of the layered composition to undergo instant gelation once sprayed onto the surface of an immersed, uncured 3D object or a previous layer, which is accomplished by contacting the layered composition with a gel composition that typically contains a gel initiator in an aqueous carrier (water as the primary or sole solvent). Instant gelation of any given layer is crucial for depositing the next layer on top of said layer by inkjet printing, as it allows skipping the curing / hardening step between each layer deposition. This instant gelation can omit and generally avoid any intermediate steps between inkjet printing channels, which is equivalent to layer deposition in other additive 3D printing processes, with the added advantage that the layers fuse together vertically (from top to bottom), and if all layers are printed using the same layered composition before and / or after curing, no visible marks or significant signs of delamination are left in the resulting 3D object.

[0134] The choice of gel initiator depends on the chemical properties of the gelling agent, and more specifically, on the properties to which the gelling agent is sensitive. For example, in embodiments where the gelling agent is pH sensitive, a suitable gel initiator is an acid. In some embodiments, the gelling agent coagulates upon contact with a divalent cation, and a suitable gel initiator is Ca. 2+ Ion source.

[0135] The concentration of the gel initiator in the gel composition also depends on the type and sensitivity of the gelling agent, and can be determined experimentally and applied to all compositions containing the same gelling agent and initiator. Typically, the concentration of the gel initiator ranges from 0.1 to 20 wt%, 1 to 20 wt%, 2 to 15 wt%, or 1 to 10 wt% of the total weight of the composition.

[0136] According to some preferred embodiments, the gelling agent is pH / acid sensitive, and the gel initiator is an acid or H3O+ (H+) ion source. More preferably, the gel initiator is a transient acid. Acids that can be neutralized by heat are collectively referred to herein as transient acids. Therefore, the phrase "transient acid" as used herein refers to an acid that can be removed by volatility, decomposability, or internal / cross-reactivity to form a substantially neutral substance.

[0137] While evaporation is one mechanism by which heat can reduce the presence of volatile acids, such as in the case of acetic acid and other organic acids, heat can also reduce acidity through other mechanisms. Some acidic compounds may exhibit pH changes under a range of physical conditions, such as temperature. For example, some organic acid compounds may undergo chemical reactions, such as condensation, when heat is applied to the composition. This chemical reaction ultimately leads to the loss of acidity and the increase and neutralization of pH in the cured product, and it typically involves heating.

[0138] This article notes that, in general, α-hydroxy acids are suitable as temporary acids according to some embodiments of the invention.

[0139] For example, lactic acid can be used to adjust the pH of aqueous solutions to approximately 2 to 3 (pKa is 3.8 in water at 25°C), but when heated to above 100°C under dehydration conditions, lactic acid molecules react with each other to provide a neutral and stable lactone species called lactide, which is a cyclic diester of lactic acid. Lactide may undergo further transformations and participate in polymerization reactions on substrates, as it is known to lead to the formation of PLA, polylactic acid polymers, and copolymers.

[0140] Another example of this transient acid is glycolic acid, which forms the cyclic and neutral lactone 1,4-dioxane-2,5-dione.

[0141] When a minimal or no trace of acid is desired in the final product, transient acidity is required. Therefore, the amount of acid residue should be reduced before or during the curing step of the process (typically at 90–180°C or 140–160°C) without further damaging the substrate. On the other hand, highly volatile acid fumes can seep into the pores when printing stops, reacting with other parts of the ink composition, causing immediate printhead clogging and, over a longer period, corrosion of the printer's sensitive components and the environment. Another factor is the potential adverse effects on worker health from highly volatile acids. Furthermore, some volatile acids produce toxic or unpleasant odors even in trace amounts in the finished product. Some volatile acids leave a noticeable and mostly unpleasant odor and should therefore be avoided, as toxic odors can affect the workplace and contribute to foul smells in the end-user product. Therefore, odorless or transient volatile organic acids should be chosen whenever possible.

[0142] Exemplary temporary organic acids that can provide all the above advantages and have the fewest disadvantages include, but are not limited to, lactic acid and glycolic acid.

[0143] Therefore, according to some implementation schemes, the acid is glycolic acid or lactic acid. The acid can be buffered by a weak amine, such as tris(hydroxymethyl aminomethane), also known as Tris or THAM.

[0144] According to some embodiments, the acidic gel composition is characterized by a low pH, or a pH range of 3-6, 4-6, or 5-6.5. In some embodiments, the pH of the gel composition is buffered by a suitable salt or weak base (e.g., an ammonia / ammonium base or another volatile amine) to ensure complete extraction of any trace amounts of acid or base from the printed image.

[0145] According to some embodiments of the invention, the process of forming 3D objects on certain substrates can vary from one substrate to another, particularly when the substrate is absorbent relative to the liquid composition. For example, when forming 3D objects on fabric, the process first wets the surface of the substrate with a gel composition, the amount of which should reduce the absorption of the subsequent layered composition and mitigate the unevenness of the fabric surface. The initial application of the gel composition can also be achieved by a device capable of delivering larger quantities of the composition more quickly, such as a spray nozzle, as opposed to delivery via an inkjet printhead. Delivery of the gel composition between layers is preferably carried out via an inkjet printhead, which allows for more precise delivery in terms of both position and quantity.

[0146] According to some embodiments of the invention, the amount of gel composition (also referred to herein as FIXA gel composition or simply "FIXA") applied through a spray nozzle differs from the amount applied through an inkjet printhead nozzle (also referred to herein as FOF gel composition or simply "FOF"). For example, the amount of gel composition delivered through the nozzle ranges from 6 to 46 mg / cm³. 2 (Approximately 0.04 g / cm² to 0.3 g / cm²), while the amount delivered via inkjet printheads ranges from 0.15 to 15 mg / cm². 2 (Approximately 0.001 g / sq inch to 0.1 g / sq inch).

[0147] The gel composition (FIXA) used for initial wetting of the substrate may also differ from the gel composition (FOF) used between layers in other parameters, such as the viscosity and concentration of the gel initiator. For example, see Table 1 below for a comparison of FIXA and FOF.

[0148] Table 1

[0149] Viscosity (cps) 1-4 4-20 Gel initiator concentration 0.5-5wt% 3-15wt% Application device spray nozzle Inkjet printhead Application content <![CDATA[6-46mg / cm 2 ]]> <![CDATA[0.15-15mg / cm 2 ]]>

[0150] 3D patterns and objects:

[0151] The method provided herein results in inkjet embossed (3D) prints adhered to the surface of a substrate. According to embodiments of the invention, the substrate is not limited and can be made of absorbent, non-absorbent, flexible, or stretchable materials.

[0152] According to various aspects of the present invention, 3D objects are the result of 3D printing or additive manufacturing processes that create three-dimensional solid objects from digital files. The creation of printed 3D objects described herein is achieved by adding layers upon layers, i.e., by placing successive layers of material until an object is obtained; additive manufacturing processes create objects. The objects provided herein are also attached to the substrate by forces and interactions similar to those used to fix an inkjet-printed image to a substrate.

[0153] The 3D object is the result of curing and solidifying a precursor gel 3D object, provided by layering gel layers one on top of another while substantially maintaining the shape and size of the precursor object. Regardless of the additive manufacturing process used, when all layers are printed using the same layering composition, the final solid 3D object has essentially no layering marks on or within it. In other words, according to some embodiments of the invention, the layers are not visually or otherwise distinguishable from each other unless they are printed from different layering compositions (inks).

[0154] In some implementations, an object is printed using more than one layered composition (ink), and the different inks are visually and / or mechanically different from each other, making the layers printed by the different inks distinguishable.

[0155] Therefore, one aspect of the present invention is a 3D gel object, which is the result of the methods and compositions provided herein prior to a curing step. The gel object possesses mechanical properties, such as viscosity and gel strength, which can be measured by suitable and widely used means and methods, as known in the art for semi-solid gel-like substances and objects. For example, gel strength can be tested and characterized by texture analysis equipment following standard industrial protocols.

[0156] The resulting 3D object can retain the mechanical properties of the film-forming agents(s) used in the layered composition. For example, in some embodiments, the object can be stretched to at least 10% longitudinal elongation before breaking or separating from the surface, a property derived from the properties of the adhesives / resins and other film-forming agents used in the layered composition.

[0157] In some implementations, the height of the 3D object is at least 10, 20, 30, 40, 50, or 60 μm. This size is limited by the strength of the precursor gel 3D object, which is non-solid and may easily spread, flatten, sagging, drooping, sinking, or otherwise descend and deform beyond a certain size. The strength of the precursor gel 3D object can be controlled to some extent by the choice and concentration of the gelling agent, the number and thickness of the layers, and the minimization of agitation applied to the precursor before curing.

[0158] Similar to other layer-based additive manufacturing processes for forming 3D objects, the process described herein is based on constructing objects layer by layer, starting with a base layer attached to a substrate and adding two or more layers on top. Each layer is applied as a 2D pattern, and the next layer applied over the previous layer can be printed with the same or a different pattern. According to some embodiments of the invention, the area of ​​the upper layer printed over the lower layer is equal to or smaller than the area of ​​the lower layer. Therefore, the 3D object, essentially a result of curing a gel 3D object, can be cured into a shape with vertical sidewalls and / or a shape that tapers gradually from a flat base. Figure 1C As shown, the gel 3D object gradually tapers to a non-limiting exemplary shape, which then solidifies into... Figure 1D The shape shown tapers smoothly, where... Figure 2 In the example, a non-limiting example shows the structural features of a 3D object having a straight vertical wall on its right side and a curved, tapering left side.

[0159] Figure 3 It is a black and white photograph of a fabric substrate on which several 3D objects are printed in the form of letters and horizontal parallel lines, showing the three-dimensional conical structure in the objects, indicating that these layers are printed from a series of layers from a large area at the bottom to a small area at the next bottom.

[0160] Due to the semi-liquid / solid nature of precursor gel 3D objects, this paper notes that, unlike other additive methods in 3D printing, the method presented here is disadvantageous in its use of the concept of a support structure, as this term is used in the art for 3D solid printing. In short, a 3D printed support structure is not part of the final 3D object, but rather serves to support certain parts of the object during the printing process. This means that the support structure is removed once printing is complete.

[0161] According to another aspect of some embodiments of the invention, a freestanding 3D object is provided, provided by the methods and compositions disclosed herein, and further provided by separating the cured object from a substrate. In other words, the methods provided herein also include the step of removing the cured object from the substrate, substantially without deforming or substantially altering the object except for separation from the surface of the substrate.

[0162] Light shape effect:

[0163] According to some embodiments of the invention, 3D objects can be formed from substantially transparent and colorless layered compositions and / or from layered compositions comprising opaque or translucent pigments, producing transparent, translucent, semi-transparent, or opaque colored or colorless layers, some or all of different types of films, in various portions of the object. These options open up pathways for forming transparent, translucent, and opaque 3D objects, as well as 3D objects comprising structural elements including any combination thereof, on substrates.

[0164] For example, a 3D object can be formed by printing a pattern in one or more substrate layers using an opaque, light-colored layering composition (e.g., one or more opaque white substrate layers), and then printing an additive layer using a layering composition comprising any combination of translucent pigments, thereby forming a colored 3D object with an opaque white underside. This embodiment is particularly useful when printing 3D objects on non-white substrates.

[0165] In another exemplary embodiment of the invention, an object is printed from a transparent, colorless, or translucent layered composition in the form / shape of an object having a refractive and reflective surface, such as in a Fresnel lens, forming an object capable of refracting, reflecting, and focusing light. The light-refracting and reflecting object can be formed on (multiple) substrates comprising light-reflecting components, blended into the layered composition to enhance the light refraction and reflection effect.

[0166] This invention benefits from the principles of lenticular printing. Lenticular printing is a technique that uses lenticular lenses (also used in 3D displays) to generate printed images with the illusion of depth, or the ability for an image to change or move when viewed from different angles. Examples of lenticular printing include flipping and animation effects (such as blinking), and modern advertising graphics that change their information based on viewing angle. Common terms for lenticular printing include “3D postcards,” “flickers,” “winkies,” “wiggle pictures,” and “tilt cards.” The trademarks Vari-Vue and Magic Motion are also frequently used for lenticular images. In the context of embodiments of this invention, 3D objects are formed by printing a biconvex lens that acts as a magnifying lens, and is designed such that different images are magnified when viewed from slightly different angles. The most common example is the lens used in lenticular printing, a technique used to create the illusion of depth, or to make an image appear to change or move when viewed from different angles.

[0167] In some embodiments, an object is formed using two or more different layered compositions, each layer being characterized by a different color (or lack thereof), elasticity, thickness, coverage area, etc., such that at least some delamination marks in the object are detectable before and / or after the curing step.

[0168] During the patent term of this application, it is anticipated that many related processes for inkjet printing of 3D objects will be developed, and the scope of this application is intended to include all such new technologies a priori.

[0169] The term "about" as used here refers to ±10%.

[0170] The terms “comprises,” “comprising,” “includes,” “including,” “having,” and their variant forms mean “including but not limited to.”

[0171] The term "consisting of" means "including and limited to".

[0172] The term "consisting essentially of" means that a composition, method, or structure may include additional ingredients, steps, and / or portions, provided that the additional ingredients, steps, and / or portions do not substantially alter the fundamental and novel characteristics of the claimed composition, method, or structure.

[0173] As used herein, the phrases “substantially devoid of” and / or “essentially devoid of” in the context of a substance or composition mean either the complete absence of that substance or the inclusion of a substance in amounts less than about 5%, 1%, 0.5%, or 0.1% by weight or volume of the composition. Alternatively, in the context of a process, method, property, or characteristic, the phrases “substantially devoid of” and / or “essentially devoid of” mean a process, composition, structure, or article lacking a particular process / method step or a particular property or characteristic, or a process / method in which a particular process / method step is performed in amounts less than about 5%, 1%, 0.5%, or 0.1% compared to a given standard process / method, or a property or characteristic characterized by being less than about 5%, 1%, 0.5%, or 0.1% of said property or characteristic compared to a given standard.

[0174] When applied to the original, desired, or endowed properties of an object or composition, the term "substantially maintaining" as used herein means that the properties of the object or composition being processed change by no more than 20%, 10%, or 5%.

[0175] The term "exemplary" is used herein to mean "used as an embodiment, example, or illustration." Any embodiment described as "exemplary" is not necessarily to be construed as preferred, advantageous, or excluding combinations of features from other embodiments.

[0176] The terms "optionally" or "alternatively" are used herein to mean "provided in some embodiments but not in others." Any particular embodiment of the invention may include multiple "optional" features unless these features conflict with each other.

[0177] As used herein, unless the context clearly indicates otherwise, the singular forms “a,” “an,” and “the” include plural references. For example, the terms “a compound” or “at least one compound” can include multiple compounds, including mixtures thereof.

[0178] Throughout this application, various embodiments of the invention may be presented in a scope format. It should be understood that the scope format is for convenience and brevity only and should not be construed as a rigid limitation on the scope of the invention. Therefore, the scope description should be considered to have specifically disclosed all possible sub-scopes and the individual values ​​within those scopes. For example, a description of a scope such as 1 to 6 should be considered to have specifically disclosed sub-scopes such as 1 to 3, 1 to 4, 1 to 5, 2 to 4, 2 to 6, 3 to 6, etc., and individual numbers within said scope, such as 1, 2, 3, 4, 5, and 6. This applies regardless of how broad the scope may be.

[0179] Whenever this document indicates a range of numbers, it is intended to include any referenced numbers (fractions or integers) within the indicated range. The phrases “range between the first indicated number and the second indicated number” and “range from the first indicated number to the second indicated number” are used interchangeably in this document and are intended to include the first and second indicated numbers, as well as all decimals and integers in between.

[0180] As used herein, the terms “process” and “method” refer to the manner, means, techniques and procedures used to accomplish a given task, including but not limited to those manner, means, techniques and procedures known to or readily derived from known manner, means, techniques and procedures by practitioners in the fields of chemistry, materials, mechanics, computing and digital science.

[0181] It should be understood that, for clarity, certain features of the invention described in the context of individual embodiments may also be provided in combination in a single embodiment. Conversely, for brevity, various features of the invention described in the context of a single embodiment may also be provided individually, or in any suitable sub-combination, or appropriately provided in any other described embodiment of the invention. Certain features described in the context of various embodiments should not be considered essential features of those embodiments unless the embodiment would not function without these elements.

[0182] As described above and as claimed in the following claims, the various embodiments and aspects of the invention are supported by experiments and / or calculations in the following examples.

[0183] Example

[0184] The following embodiments, together with the above description, illustrate some implementations of the invention in a non-limiting manner.

[0185] Example 1

[0186] Materials and methods

[0187] To verify some aspects of the concepts of this disclosure, according to some embodiments of the invention, this disclosure is carried out by inkjet printing a pattern of parallel lines, the pattern being selected to display a high resolution of a 3D pattern, which can be achieved by inkjet forming a 3D object.

[0188] For some exemplary proof-of-concept experiments, absorbent cotton fabrics were chosen as the substrate to demonstrate the method’s ability to mitigate material inhomogeneity and capillary surfaces.

[0189] Substrate:

[0190] A cotton garment is used as the absorbent base material. Specifically, it uses... The purchased garments underwent no further processing; the fabrics were used as directed by the manufacturer, without washing, smoothing, or any surface modifiers or pretreatment processes.

[0191] A transparent polyethylene terephthalate (PET) film was used as a non-absorbent substrate.

[0192] machine:

[0193] The substrate is mounted on an ATLAS printer (KORNIT), which is equipped with at least one nozzle (referred to herein and throughout as "FIXA") for jetting a gel composition formulated for mass jetting, at least one printhead (referred herein and throughout as "FOF") for inkjet printing a gel composition formulated for inkjet printing conditions, and at least one printhead for inkjet printing a layered composition comprising a white opaque pigment (titanium dioxide). The printer includes a curing unit located downstream of its printing section, configured to cure the printed pattern at 160°C for 8 minutes. The machine operates at 600*600 DPI and is equipped with a printhead with a nominal droplet size of 35pl.

[0194] pattern:

[0195] The pattern chosen to validate the concept consists of two sets of parallel lines spaced at intervals of 0.25 mm, 0.5 mm, 1.0 mm, and 1.5 mm (see...). Figures 4A to 4C ).

[0196] FIXA gel composition:

[0197] The acidic base jelling composition (a variant of a gel composition for mitigating unevenness and absorbent surfaces of a substrate) is applied via a nozzle sprayer at a rate of 0.16 g / square inch and comprises:

[0198] BYK 348 (as a wetting agent) 0.05wt%; and water To QS pH 4.6

[0199] FOF gel composition:

[0200] The acidic gel composition, used to coagulate interlayer laminations, is digitally printed using an inkjet printhead at a rate of 0.005 g / sq inch and comprises:

[0201]

[0202]

[0203] Layered composition:

[0204] Through the inkjet printhead at approximately 4 mg / cm 2 The rate of digital printing of an opaque white film-forming composition for forming layers of a 3D object includes:

[0205]

[0206] analyze:

[0207] The final results (3D objects attached to the substrate surface) were analyzed using multiple standard tests, including abrasion resistance tests to ensure the curing and adhesion of digitally printed and cured 3D objects to the substrate (Color Fastness to Crocking / Rubbing Test, BS EN ISO 105X12 and AATCC 8, using a crockmeter).

[0208] Example 2

[0209] result

[0210] Critical degree of gelation:

[0211] According to some embodiments of the invention, the methods provided herein are simplified to be practiced on absorbent and non-absorbent substrates using the methods and materials described above.

[0212] Specifically, FIXA is used only on absorbent substrates, and during the same printhead bridging motion, the opaque white layered composition and FOF are printed substantially simultaneously from separate, designated inkjet printheads. Four layers are printed on two substrates using a specified line pattern.

[0213] Figures 4A to 4C A PET film (non-absorbent substrate) is shown. Figure 4A ), on cotton clothing (absorbent substrate; Figure 4B ) and with Figure 4B The same pattern but without printing the gel composition pattern on the substrate or between layers. Figure 4C A photograph of a parallel line pattern.

[0214] like Figures 4A to 4B As shown, the printing timeline is considered as relief on the patterns on both the non-absorbent and absorbent substrates, while Figure 4C The smear pattern is shown after only 3 out of the expected 4 layers have been printed, demonstrating the crucial role of the gel composition.

[0215] Cementation of the base and intermediate layers:

[0216] Absorbent cotton garments were used to demonstrate the role of the base and intermediate layer gel composition in forming 3D objects on which they are formed.

[0217] Figures 5A to 5CA photograph shows an 8-layer pattern printed using an intermediate layer (FOF) gel composition but without a base layer (FIXA) gel composition. Figure 5A The same 8-layer pattern was printed using a base (FIXA) gel composition but without an intermediate layer (FOF) gel composition. Figure 5B ); and the same 8-layer pattern printed using a base (FIXA) gel composition and an intermediate layer (FOF) gel composition. Figure 5C ).

[0218] like Figures 5A to 5C As shown, according to some embodiments of the invention, both FIXA and FOF are crucial for forming high-resolution, well-defined 3D objects with substrate retention by inkjet printing on cotton fabric. Figure 5A As shown, without addressing the wicking and uneven surface of cotton garments, the first layer printed on this substrate (the first layer constituting the object) feathers and becomes smudged without first applying a FIXA coating to the surface. Figure 5B This shows what happens when there is no printing gel composition and how the 8 layers of opaque white laminating composition are applied and become flowing without solidifying. Figure 5B This shows what happens when there is no printing gel composition and how the 8 layers of opaque white laminating composition are applied and become flowing without solidifying. Figure 5C This provides a clear demonstration of the concepts of the invention disclosed herein, showing an array of 3D objects inkjet printed on absorbent substrates, including closed and parallel lines, complex patterns (flying, roses, and swirls), and alphanumeric characters in the direction of and perpendicular to the movement (X / Y axis) of the rapid printhead assembly (bridge; mount).

[0219] Once it was determined that achieving gelation of the layered composition was crucial—otherwise, printing more than two layers would result in a free-flowing, liquid-thick ink layer without forming a 3D object—the next step was to verify the contribution of each layer to the object's thickness. To achieve easily measurable thickness, 12 simple rectangular patterns were printed on the same substrate using the same layered composition as described above; the substrate and the object were then cut at the center of the simple planar object, and the cross-section of the object was measured. Figure 6 As shown, in this experiment, it was found that each layer contributes approximately 20 μm to the height (Z-axis) of the object.

[0220] Figure 6 A cross-sectional photograph of a 12-layer 3D object printed on a cotton garment is shown, revealing an average thickness of approximately 240 μm.

[0221] To characterize the 3D objects printed and cured on a cotton garment substrate, four layers of the layered composition (opaque white) and gel composition as described above were printed after applying a base gel composition (FIXA). Two identical prints were prepared; one was tested directly after printing without curing, while the second was first cured in a hot air oven at 160°C for 8 minutes.

[0222] Using a crockmeter (James Heal) for color fastness to rubbing TM Using the Crockmaster, following the procedures of AATCC8 and EN ISO 105-X12, a 9N load was generated using weights, and then the printed layer was rubbed with a friction cloth.

[0223] As expected, the test probe dispersed the ink in the uncured sample, while on the cured layer, the rubbing fastness tester probe had almost no visible effect on the 3D object.

[0224] Although the invention has been described in conjunction with specific embodiments thereof, it will be apparent to those skilled in the art that many alternatives, modifications, and variations will be readily apparent. Therefore, the invention is intended to include all such alternatives, modifications, and variations falling within the spirit and broad scope of the appended claims.

[0225] The applicant intends that all publications, patents, and patent applications mentioned in this specification be incorporated herein by reference in their entirety, as if each individual publication, patent, or patent application were specifically and individually indicated as being incorporated herein by reference. Furthermore, any reference or identification of any reference in this application should not be construed as an admission that such reference is prior art to the invention. The use of section headings should not be construed as a necessary limitation.

[0226] Furthermore, any priority documents in this application are incorporated herein by reference in their entirety.

Claims

1. A method for forming a three-dimensional object on the surface of a substrate, characterized in that, The method includes the following steps: (a) A pattern is inkjet printed on the area of ​​the surface using the following material to form a first gel layer: (i) a layered composition, and (ii) Gel composition; (b) Repeat step (a) on the first gel layer to form a second gel layer on the first gel layer; (c) Repeat step (b) n times to form the nth gel layer on the second gel layer, thereby forming a three-dimensional gel object, where n is an integer equal to or greater than 1; as well as (d) The three-dimensional object is formed by heating it to a temperature of 90 to 200°C to solidify it. Each layer is formed by a two-part gelation reaction between the layered composition and the gel composition. The layered composition coagulates upon contact with the gel composition. Each of the layered composition and the gel composition is free of UV curing agent, and The viscosity of the layered composition at 25°C is 4 to 25 cps.

2. The method as described in claim 1, characterized in that: The thickness / height of each of the first gel layer, the second gel layer, and the nth gel layer is independently at least 10 micrometers.

3. The method as described in claim 1, characterized in that: The spatial resolution of the identifiable structural features in the three-dimensional gel object is at least 0.1 mm.

4. The method as described in claim 1, characterized in that: n is greater than 2.

5. The method as described in claim 1, characterized in that: The layered composition contains pigments.

6. The method as described in claim 5, characterized in that: The pigment is opaque.

7. The method as described in claim 6, characterized in that: The concentration of the opaque pigment is 1 to 40 wt%.

8. The method as described in claim 5, characterized in that: The pigment is translucent.

9. The method as described in claim 8, characterized in that: The concentration of the translucent pigment is 2 to 30 wt%.

10. The method according to any one of claims 1 to 9, characterized in that: The layered composition comprises a gelling agent that coagulates at a pH less than 7, upon contact with cations, or upon contact with metal oxides.

11. The method as described in claim 10, characterized in that: The gelling agent is selected from the group consisting of pH-sensitive alkali-soluble polymers, which are selected from the group consisting of polyacrylates, polyurethanes, polyesters, polybutadiene, polyvinyl chloride, polyvinyl alcohol, polyvinyl acetate, polyimide, and any mixtures and / or copolymers thereof.

12. The method as described in claim 11, characterized in that: The concentration of the gelling agent in the layered composition is from 0.1 to 30 wt%.

13. The method as described in claim 12, characterized in that: The layering composition further comprises a non-coagulating film-forming agent at a concentration of 0 to 30 wt%.

14. The method as described in claim 13, characterized in that: The gelling agent is selected, and / or the non-coagulating film-forming agent is selected when present, such that the independently cured 1 mm thick film exhibits an elongation of at least 5%, the independently cured 1 mm thick film being formed from the layering composition comprising the gelling agent and / or the non-coagulating film-forming agent.

15. The method as described in claim 1, characterized in that: The maximum dispersed particle size in the layered composition is less than 5 micrometers.

16. The method as described in claim 1, characterized in that: The layered composition is printed with droplet sizes ranging from 10 to 120 picoliters.

17. The method as described in claim 1, characterized in that: The gel composition contains a gel initiator selected from the group consisting of acids, divalent cations, and metal oxides.

18. The method as described in claim 17, characterized in that: The concentration of the gel initiator in the gel composition is from 0.1 to 20 wt%.

19. The method as described in claim 17, characterized in that: The gel initiator is a temporary acid, and the pH of the gel composition is from 3 to 6.

5.

20. The method as described in claim 1, characterized in that: The layering composition is applied before, simultaneously with, or after the application of the gel composition.

21. The method as described in claim 1, characterized in that: The method is carried out on an absorbent substrate, and prior to step (a), it further includes applying a base gel composition to the surface of the substrate.

22. The method as described in claim 21, characterized in that: The base gel composition is applied at an amount of 5 to 50 mg / cm².

23. The method as described in claim 1, characterized in that: The method involves curing that is essentially free from photoinitiation, propagation, and / or any UV light influence.

24. A substrate having a three-dimensional object on its surface, characterized in that, The substrate is obtained by the method described in any one of claims 1 to 23.

25. The substrate as claimed in claim 24, characterized in that: The three-dimensional object can be stretched to at least 5% longitudinal elongation before breaking or separating from the surface.

26. The substrate as claimed in claim 24, characterized in that: The height of the three-dimensional object is at least 50 micrometers.

27. The substrate as claimed in claim 24, characterized in that: The substrate is selected from the group consisting of absorbent materials, non-absorbent materials, flexible materials and stretchable materials.

28. The substrate as claimed in claim 27, characterized in that: The absorbent material is a fabric.

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