Cartridge, system and method for volumetric 3D printing

Abstract

The present invention includes a cartridge for printing one or more three-dimensional objects, the cartridge configured to contain a volume of a photopolymerizable composition, the cartridge including side walls connected with a bottom wall to define a volume space for containing the volume, the cartridge configured to include one or more printing zones, wherein the printing zone is dimensioned to be conveniently irradiated by one or more, preferably at least two, excitation light projections to at least partially form a three-dimensional printed object within the volume of photopolymerizable composition in the printing zone. Systems and methods including the cartridges described herein are also disclosed.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to U.S. Provisional Patent Application No. 63 / 343,562, filed by Quadratic 3D, Inc. on May 19, 2022, entitled “Cartridge, System, and Method for Volumetric 3D Printing,” and U.S. Provisional Patent Application No. 63 / 400,448, filed by Quadratic 3D, Inc. on August 24, 2022, entitled “Volumetric Three-Dimensional (3D) Printing System,” each of which is incorporated herein by reference in its entirety for all purposes. Technical Field

[0003] The present invention relates to the technical field of three-dimensional printing. Summary of the invention

[0004] According to one aspect of the present invention, there is provided a cartridge for printing one or more three-dimensional objects, the cartridge being configured to hold a certain volume of a photopolymerizable composition, the cartridge comprising side walls, preferably four side walls, the side walls being connected to a bottom wall to define a volume space for holding the volume, the cartridge being configured to include one or more printing zones, wherein the size of the printing zones is designed to facilitate being irradiated by one or more, preferably at least two, excitation light projections to at least partially form a three-dimensional printed object within the volume of photopolymerizable composition in the printing zone. The cartridge may be open and may optionally include a removable lid or a top wall opposite to the bottom. Optionally, at least one of the walls may include at least one openable / closable port to facilitate the introduction of unpolymerized photopolymerizable composition and / or the removal of unpolymerized photopolymerizable composition and / or the removal of one or more three-dimensional objects from the cartridge.

[0005] According to another aspect of the present invention, a box for printing one or more three-dimensional objects is provided, the box being configured to hold a certain volume of a photopolymerizable composition, the box comprising opposite end walls and comprising at least one port in at least one end wall of the box to facilitate the introduction of unpolymerized photopolymerizable composition and / or the removal of unpolymerized photopolymerizable composition and / or the removal of one or more three-dimensional objects from the box, the box being configured to include one or more printing zones, wherein the size of the printing zone is designed to facilitate irradiation by one or more, preferably at least two, excitation light projections to at least partially form a three-dimensional printed object within the volume of photopolymerizable composition in the printing zone.

[0006] According to another aspect of the present invention, a system for printing one or more three-dimensional objects is provided, the system comprising a box configured to hold a certain volume of a photopolymerizable composition, the box comprising side walls, preferably four side walls, the side walls being connected to a bottom wall to define a volumetric space holding the volume, the box being configured to include one or more printing zones, wherein the size of the printing zones is designed to facilitate illumination by one or more, preferably at least two, excitation light projections to at least partially form a three-dimensional printed object within the volume of photopolymerizable composition in the printing zone; and one or more optical systems, wherein the optical systems are positioned or positionable to selectively direct one or more, preferably at least two, excitation light projections into a single printing zone.

[0007] According to another aspect of the present invention, a system for printing one or more three-dimensional objects is provided, the system comprising a box configured to hold a certain volume of photopolymerizable composition, the box comprising opposite end walls and comprising at least one port in at least one end wall of the box to facilitate the introduction of unpolymerized photopolymerizable composition and / or the removal of unpolymerized photopolymerizable composition and / or the removal of one or more three-dimensional objects from the box, the box being configured to include one or more printing zones, wherein the size of the printing zones is designed to facilitate illumination by one or more, preferably at least two, excitation light projections to at least partially form a three-dimensional printed object within the volume of photopolymerizable composition in the printing zone; and one or more optical systems, wherein the optical systems are positioned or positionable to selectively direct one or more, preferably at least two, excitation light projections into a single printing zone.

[0008] A cartridge included in a system according to the present invention may also optionally include one or more of any of the cartridge features described herein.

[0009] Systems according to the present invention may also optionally include one or more of the additional components described herein.

[0010] The system according to the invention may also optionally comprise a separator unit for separating the partially formed three-dimensional object from the unpolymerized photohardenable composition in the cartridge after printing.

[0011] The system may further include a recovery unit connected to the separator unit for receiving the separated unpolymerized photopolymerizable composition.

[0012] The system according to the present invention may also optionally include one or more inspection units or areas (also referred to herein as zones), which are preferably non-light-opaque. The inspection units may facilitate visualization and / or characterization (e.g., measurement, defect detection, etc.) of the printed object. The inspection units or areas may be positioned so as to allow inspection of the printed part after it is formed, e.g., before separation (if included), after separation (if included), and / or after post-processing (if included). Optionally, light may be projected into the inspection area for purposes such as visualization or measurement. Optionally, ultrasound may be projected into the inspection area for purposes such as visualization or measurement.

[0013] The system according to the invention may also comprise a post-processing unit or zone.

[0014] According to another aspect of the present invention, there is provided a method for printing one or more three-dimensional objects, the method comprising:

[0015] A volume of a photopolymerizable composition is provided in a box for printing one or more three-dimensional objects, the box being configured to hold the volume of the photopolymerizable composition, the box comprising side walls, preferably four side walls, connected to a bottom wall to define a volume space for holding the volume, the box being configured to include one or more printing zones, wherein the size of the printing zones is designed to facilitate illumination by one or more, preferably at least two, excitation light projections to at least partially form a three-dimensional printed object within the volume of the photopolymerizable composition in the printing zone, and

[0016] The one or more, preferably at least two, excitation light projections are directed into each printing area to selectively induce photopolymerization or cross-linking reactions of the photopolymerizable composition at one or more selected locations in the printing area, thereby at least partially forming a three-dimensional object in the printing area.

[0017] According to another aspect of the present invention, there is provided a method for printing one or more three-dimensional objects, the method comprising:

[0018] providing a volume of photopolymerizable composition in a box configured to hold the volume of photopolymerizable composition, the box comprising opposed end walls and comprising at least one port in at least one of the end walls of the box to facilitate introduction of unpolymerized photopolymerizable composition and / or removal of unpolymerized photopolymerizable composition and / or removal of one or more three-dimensional objects from the box, the box being configured to include one or more printing zones, wherein the printing zones are sized to facilitate illumination by one or more, preferably at least two, excitation light projections to at least partially form a three-dimensional printed object in the volume of photopolymerizable composition in the printing zones, and

[0019] The one or more, preferably at least two, excitation light projections are directed into each printing zone to selectively photopolymerize the photopolymerizable composition at one or more selected locations in the printing zone to at least partially form a three-dimensional object in the printing zone.

[0020] The cartridges included in the methods according to the invention may also optionally include one or more of any of the cartridge features described herein.

[0021] The method according to the present invention may also optionally include a step of post-processing the separated objects. Examples of post-processing are described below.

[0022] Preferably, the photopolymerizable composition used in the boxes, systems and methods described herein exhibits non-Newtonian rheological behavior so that an object formed in the photopolymerizable composition in the printing area remains in a fixed position or undergoes minimal displacement in the unpolymerized photopolymerizable composition during formation, and excitation light is directed through at least one optically transparent window into the printing area to selectively photopolymerize the photopolymerizable composition in the printing area in the absence of a support structure to form a printed object, wherein the printed object remains in a fixed position or undergoes minimal displacement in the unpolymerized photopolymerizable composition during formation.

[0023] More preferably, the photopolymerizable composition for use in the boxes, systems and methods described herein comprises a photohardenable component and a photoswitchable photoinitiator, wherein the photoswitchable photoinitiator can be activated by exposure to light having a first wavelength and light having a second wavelength to induce a crosslinking or polymerization reaction in the photohardenable component, wherein the first wavelength is different from the second wavelength, and wherein the photopolymerizable composition exhibits non-Newtonian rheological behavior. Optionally, the photopolymerizable composition may also include a co-initiator and / or a sensitizer. The sensitizer can produce an excited state of the photoswitchable photoinitiator by absorbing light and transferring energy to the photoswitchable photoinitiator. The photopolymerizable composition may optionally include a synergist.

[0024] In the system and method according to the present invention, the wavelength of the excitation light used for the excitation light projection is preferably selected taking into account the photopolymerizable composition and the hardening mechanism used.

[0025] For example, for a photopolymerizable composition that can be hardened by a hardening mechanism involving a single wavelength of excitation light, the wavelengths of the two or more excitation light projections can be the same. Optionally, in this case, at least one of the two or more excitation light projections can include light of a different wavelength, for example, to inhibit undesired hardening of the photopolymerizable composition.

[0026] In the case where the photopolymerizable composition can be hardened by a hardening mechanism involving multiple wavelengths of excitation light, the wavelengths of at least two of the two or more excitation light projections will be selected to project excitation light having an appropriate wavelength for the hardening mechanism. Optionally, light of other wavelengths may also be used to inhibit undesired hardening of the photopolymerizable composition.

[0027] The systems and methods according to the present invention may also include one or more control systems for controlling at least one of the following: selectively projecting the one or more, preferably at least two, excitation light projections to one or more printing areas at one or more selected locations; dispensing the photopolymerizable composition into the box; discharging unpolymerized photopolymerizable composition and one or more printed three-dimensional objects from the box; and if at least one box wall includes an inlet and / or outlet, opening and closing it.

[0028] The optical system included in the system and method described herein is usually used in combination with a computer and software. The software can be used to coordinate the generation of optical projections (e.g., point illumination, line illumination, two-dimensional patterns, or light sheets) from each position of its respective optical projection system along the respective projection direction, so that the parts are built (developed) plane by plane. The plane of the optical projection can be orthogonal to the projection direction into the photopolymerizable composition. When two optical projections are projected into the printing area, the projection directions of the two projections are preferably orthogonal to each other. The selection of computer control systems and software is within the technical scope of ordinary technicians in the relevant field. The system can also optionally include other components or be used together with other components.

[0029] The system according to the present invention may also optionally include one or more inspection units or areas (also referred to herein as zones), which are preferably not light tight. The inspection unit may facilitate visualization and / or characterization (e.g., measurement, defect detection, etc.) of the printed object. The inspection unit or area may be positioned so that the printed part is inspected after it is formed, e.g., before separation (if included), after separation (if included), and / or after post-processing (if included). Optionally, light may be projected into the inspection area for purposes such as visualization or measurement. Optionally, ultrasound may be projected into the inspection area for purposes such as visualization or measurement.

[0030] The method according to the present invention may also optionally include one or more inspection steps. The method described herein may include an inspection step to allow inspection of the printed part after it has been formed, for example before the separation step (if included), after the separation step (if included) and / or after the post-processing step (if included).

[0031] The preferred system and method according to the present invention are particularly useful for printing three-dimensional (3D) objects from a photopolymerizable composition that exhibits non-Newtonian behavior and can be cured at two or more volumetric locations illuminated by excitation light projection to form a printed object without the need to add support structures and is easier to separate from the unpolymerized photopolymerizable composition. Most 3D printing technologies involving VAT polymerization technology generally require support structures to stabilize the part during printing or allow thinner or fragile parts to be printed with overhanging parts; after printing, post-processing is required to remove the support structures, which may damage the printed part or leave marks on the printed part. Avoiding the addition of support structures will advantageously simplify the post-processing of the printed part and improve the surface quality of the part. The non-Newtonian behavior of the photopolymerizable composition can also simplify the separation of the part from the unpolymerized polymerizable liquid because when stress is applied, the apparent viscosity of the non-Newtonian photopolymerizable composition drops to a lower value (e.g., steady-state shear viscosity) than the static value (e.g., zero shear viscosity or yield stress), allowing the unpolymerized polymerizable liquid to flow out and separate from the part more easily.

[0032] In addition to applying stress, heating the unpolymerized photopolymerizable composition can also enhance the ability of the liquid to flow out and separate from the part.

[0033] Systems and methods according to the present invention also advantageously do not require the printed object to be adhered to a fixed substrate (eg, a build plate) at the beginning of the printing process, thereby avoiding a post-processing step of separating the printed object from the fixed substrate.

[0034] In the systems and methods including at least two excitation light projections according to various aspects of the present invention, optionally, one or more of the two excitation light projections may include a light sheet, which may be constructed by means known in the art, such as but not limited to: a Powell prism, a galvanometer, a multifaceted scanning mirror.

[0035] In systems and methods comprising at least two excitation light projections according to aspects of the present invention, preferably at least two of the at least two excitation light projections are directed into the volume in directions perpendicular to each other.

[0036] The method according to the present invention may also include pre-treating the photopolymerizable composition before it is introduced into the box, for example, to remove bubbles and any suspended debris. Non-limiting examples of such pre-treatments include degassing, centrifugation, filtration. A pre-treatment module or zone may also be optionally included in the system described herein.

[0037] The above and other aspects and embodiments described herein and contemplated by the present disclosure all constitute embodiments of the present invention.

[0038] It will be understood by those skilled in the art that any feature described herein with respect to any particular aspect and / or embodiment of the invention may be combined with one or more of any other features of any other aspect and / or embodiment of the invention described herein, with appropriate modifications to ensure compatibility of the combination. Such combinations are considered to be part of the invention contemplated by the present disclosure.

[0039] It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed.

[0040] Other embodiments will be apparent to those skilled in the art from consideration of the specification and drawings, claims, and practice of the invention disclosed herein. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In the accompanying drawings,

[0042] Figure 1A Examples of dimensional parameters that can be used to determine preferred box dimensions are shown. The figure also shows the coordinate axes of the drawing.

[0043] Figure 1B An example of a dimension parameter example that can be used to determine the preferred box size is shown. The coordinate axes of the drawing are also shown.

[0044] Figure 1C Shows Figure 1A and 1B Legend for .

[0045] Figure 2A Examples of dimensional parameters that can be used to determine preferred box dimensions are shown. The figure also shows the coordinate axes of the drawing.

[0046] Figure 2B An example of the size parameters of a box including multiple print areas is shown, where one print area is framed and labeled "1 Bounding Box". The coordinate axes of the drawing are also shown.

[0047] Figure 2C Shows Figure 2A and 2B Legend for .

[0048] Figure 3 An example of a box including five printing areas is shown.

[0049] Figure 4 An example of this system is shown that includes two optical systems positioned to direct the projection of excitation light into the print zone. (Other optical systems associated with other print zones are not shown in the figure.)

[0050] The drawings are simplified representations and are for illustrative purposes only; actual structures may differ in many respects, particularly including the relative proportions of the items depicted and their various aspects.

[0051] For a better understanding of the present invention and other advantages and capabilities thereof, reference should be made to the following disclosure and appended claims taken in conjunction with the above-described drawings. DETAILED DESCRIPTION

[0052] Various aspects and embodiments of the invention are further described in the following detailed description.

[0053] The present invention includes a cartridge, system, and method for printing one or more three-dimensional objects.

[0054] Volumetric 3D printing involves selectively hardening a three-dimensional pattern (e.g., an object or part) in a volume of a photohardenable (hardenable) composition by applying one or more light projections. Preferably, the cartridge includes an optically transparent region and an optically flat region adapted to direct each light projection into the volume of the photohardenable (hardenable) composition to facilitate optically addressing the photohardenable composition. The cartridges and systems and methods including the cartridges according to the present invention are sized to accommodate printing multiple objects in a single cartridge, which advantageously can improve overall printing efficiency.

[0055] The invention described herein may also facilitate reducing the labor required for 3D printing by being easily adaptable to autonomous and efficient filling, handling, printing, emptying and cleaning, unlike volumetric 3D printing techniques that rely on vessels or vials that must be manually filled, emptied and cleaned for each print, which is a slow and cumbersome process.

[0056] According to one aspect of the present invention, there is provided a box for printing one or more three-dimensional objects, the box being configured to accommodate a certain volume of a photopolymerizable composition, the box comprising side walls, preferably four side walls, the side walls being connected to a bottom wall to define a volume space for accommodating the volume, the box being configured to include one or more printing zones, wherein the size of the printing zone is designed to facilitate illumination by one or more, preferably at least two, excitation light projections to at least partially form a three-dimensional printed object within the volume of photopolymerizable composition in the printing zone.

[0057] The box may be open. An open box may also include a removable lid for closing the box. The box may be closed and include a top wall, opposite a bottom wall, in which case at least one wall may include at least one port in at least one wall to facilitate the introduction of unpolymerized photopolymerizable composition and / or the removal of unpolymerized photopolymerizable composition and / or the removal of one or more three-dimensional objects from the box.

[0058] According to another aspect of the present invention, the present invention provides a box for printing one or more three-dimensional objects, the box being configured to accommodate a certain volume of photopolymerizable composition, the box comprising opposite end walls, and comprising at least one port in at least one end wall of the box to facilitate the introduction of unpolymerized photopolymerizable composition and / or the removal of unpolymerized photopolymerizable composition and / or the removal of one or more three-dimensional objects from the box, the box being configured to include one or more printing areas, wherein the size of the printing area is designed to facilitate irradiation by one or more, preferably at least two, excitation light projections to at least partially form a three-dimensional printed object within the volume of photopolymerizable composition in the printing area.

[0059] It may be desirable that the entire cartridge described herein be optically clear.

[0060] Alternatively, the boxes described herein may include one or more optically transparent areas associated with the print zone to facilitate directing the projection of excitation light into the print zone through the one or more optically transparent areas. For example, when the print zone is located by two optical systems, two optically transparent areas or sides may be included in the box. When three optical systems locate the print zone, three optically transparent areas or sides may be included in the box. Other optically transparent areas or sides may be optionally included.

[0061] Preferably, the optically transparent area of ​​the box is also optically flat.

[0062] The box can include a first port for introducing the photopolymerizable composition into the box and a second port for removing unpolymerized photopolymerizable composition and / or one or more three-dimensional objects from the box. For example, it may be desirable to include two ports for the purpose of removing the contents of the box after printing. For example, the inclusion of two ports on opposite end walls of the box can facilitate the application of pressure (e.g., by pumping air) or pumping fluid into the box through one port to transport the contents toward and through the outlet, thereby removing / expelling the contents from the box through the second port.

[0063] The printing area in the cartridges described herein preferably has a size determined taking into account the size of the object to be printed, the numerical aperture characteristics of the projected light projection, the refractive index of the photopolymerizable composition (or suitable alternatives).

[0064] Figure 1A Examples of dimensions of the projected optical image are shown: projected image height A; projected image width B; and maximum positionable Z dimension C for printing. In the example shown, values ​​A=20 nm, B=70 nm, C=80 nm are assumed. These values ​​are exemplary only, and other values ​​may be found to be suitable.

[0065] Figure 1B Shown superimposed on Figure 1AExamples of projected image entrance area dimensions on the projected optical image dimensions shown and calculations used to determine the dimensions of the projected image entrance area. Two times the half angle standoff δ are used to determine the maximum projected dimensions of the optical system projection of one print zone. The projected image entrance height is represented by A'; the projected image entrance width is represented by B'; the farthest (from the entrance plane) projection plane depth is represented by C'; NA is the numerical aperture of the projection under consideration; ε is the distance selected to separate the print zone from the front and back walls of the container. These values ​​are calculated using the following equations:

[0066] C' = C + ε

[0067]

[0068] A' = A + 2δ

[0069] B' = B + 2δ

[0070] in:

[0071] n = refractive index of the medium (e.g., photohardenable composition)

[0072] NA = Numerical aperture of the projector

[0073] ε = distance between shaft and wall

[0074] δ = half angle spacing

[0075] exist Figure 1B middle:

[0076] The following projection image incident area assumptions are used to calculate Figure 1B A', B' and C' in:

[0077] n = 1 (air)

[0078] NA = 0.05 (f / 11)

[0079] ε = 2 mm

[0080] calculate:

[0081] C' = C + ε = 82 mm

[0082]

[0083] A' = A + 2δ = 28 mm

[0084] B' = B + 2δ = 78 mm

[0085] The values ​​of NA and ε provided in FG.1B are exemplary only, and other values ​​may be suitable. It should be noted that the same analysis can be performed for each of the multiple optical projections in the print volume, with different sizes and numerical apertures, and selecting the largest corresponding value of δ.

[0086] Figure 1C It describes Figure 1A and 1B Legend for the variables contained in .

[0087] Figure 2A Shown superimposed on Figure 1B An image of an example of the size of a print area (referred to in the figure as a "bounding box") over the projected image incident area size shown and the calculations used to determine the size of a print area (referred to in the figure as a "bounding box"). The bounding box height is denoted by A''; the bounding box width is denoted by B''; the bounding box depth is denoted by C''; and ζ is the distance chosen to separate a print area from an adjacent print area. These values ​​are calculated using the following equations:

[0088] A'' = A' + 2ζ

[0089] B'' = B' + 2ζ

[0090] C'' = C' + ε

[0091] in:

[0092] NA = Numerical aperture of the projector

[0093] ε = distance between shaft and wall

[0094] C' = box interior depth

[0095] δ = half angle spacing

[0096] A' = Projected image entrance height

[0097] B' = Projected image entrance width

[0098] ζ = Projected image spacing

[0099] A'' = bounding box height

[0100] B'' = bounding box width

[0101] C” = bounding box depth

[0102] L = Box interior length

[0103] W = box inner width

[0104] H = box interior height

[0105] V = box volume

[0106] n = refractive index of the medium (e.g., photohardenable composition)

[0107] exist Figure 2A middle:

[0108] The following bounding box assumptions are used to calculate Figure 2B A'', B'' and C'' in:

[0109] A' = 28 mm

[0110] B' = 78 mm

[0111] C' = 82 mm

[0112] ε = 2 mm

[0113] ζ = 1 mm

[0114] The values ​​provided here for ζ are merely exemplary, and other values ​​may also be suitable.

[0115] calculate:

[0116] A'' = A' + 2ζ = 30 mm

[0117] B'' = B' + 2ζ = 80 mm

[0118] C'' = C' + ε = 84 mm

[0119] Figure 2B An example of a box designed to include multiple print zones (referred to as "bounding boxes" in the figure) is shown. As shown, the box includes five (5) print zones. Figure 1A , 1B , 1C and 2A, the dimensions of the box shown (including five print zones) are: the box interior length is represented by L; the box interior width is represented by W; and the box interior height is represented by H. The box interior length takes into account the selected number of print zones to be included in the box. The calculated interior volume of the box is the product of L x W x H.

[0120] Figure 2C It describes Figure 2A and 2B Legend for the variables included in .

[0121] Figure 3An example of a box including five print zones is shown, with the top wall and the opposite end walls labeled. The bottom wall opposite the top wall and the side walls opposite the labeled side walls are not shown. It is desirable that optical projection be irradiated into the print zones through one or more of the top wall, the bottom wall and any side wall.

[0122] Preferably, when more than one printing zone is included in the box to accommodate forming multiple objects in the same box, the printing zones are sized to prevent objects printed in adjacent printing zones from contacting each other during printing.

[0123] Optionally, when multiple printing zones are included in the box, a separator may be included between the printing zones to further protect adjacent printing zones from undesirable aggregation. When separators are included, it may be desirable that any such separators are removable to facilitate emptying the box after printing.

[0124] Optionally, a movable partition may be included to facilitate changing the volume of the print zone. Optionally, the movable partition may be translated during addition (filling) of the photohardenable composition to the box and / or emptying of the photohardenable composition and one or more three-dimensional objects from the box. Optionally, fluid and / or air pressure may be used to facilitate movement of the partition.

[0125] The box preferably has a uniform cross-section along its length dimension.

[0126] The box may have a circular or oval cross-section.

[0127] The box may have a polygonal cross-section.

[0128] The box preferably has a rectangular or square cross-section.

[0129] Optionally, the box has an oval (oblong, rectangular) or other elongated shape. Other shapes may also be available.

[0130] The printing zone is preferably configured to facilitate directing one or more, preferably at least two, excitation light projections into the printing zone.

[0131] To facilitate directing the projection of excitation light into the print zone, the print zone may include one or more optically transparent regions.

[0132] Preferably, the box includes one or more optically transparent areas positioned to direct the excitation light projection and the path of the excitation light projection into the print zone in the box. As described above, optionally, the entire box can be optically transparent, and all sides of the print zone can be optically transparent. For an open box, if a removable cover is included, it can also be desirable that the cover is optically transparent.

[0133] The box can be made of materials including, for example, but not limited to, glass, quartz, fluoropolymers (e.g., Teflon FEP, Teflon AF, Teflon PFA), cyclic olefin copolymers, polymethyl methacrylate (PMMA), polynorbornene, sapphire, or transparent ceramics. Other optically transparent and optically flat materials with appropriate hardness may also be suitable.

[0134] It may be desirable that a box according to the present invention comprises straight sides that intersect at a 90° angle.

[0135] Preferably, the box has a rectangular prism shape. In this case, the rectangular prism box preferably has a uniform cross section in its longest dimension.

[0136] The box according to the present invention (regardless of the ports included in its walls or sides, if included) can be a one-piece unit or can be composed of two or more parts. For example, a box including more than one part can include side or wall parts that are fused together at their edges to form a three-dimensional box unit. Alternatively, the side or wall parts can be fixed together by a frame to form a three-dimensional rectangle. Other construction schemes may also be suitable.

[0137] When a port is included, the port is preferably disposed in a wall other than the wall through which the excitation light is directed into the volume.

[0138] Optionally, one or more of the walls or sides of the box, or the entire box, can be coated. For example, but not limited to, one or more sides can include an anti-reflective coating, a mechanical enhancement coating, a chemical resistance coating, etc. Optionally, one or more sides can include a coating on its inner surface to enhance the cleanability of the side after the box is emptied.

[0139] The cartridge is preferably reusable.

[0140] According to another aspect of the present invention, a system for printing one or more three-dimensional objects is provided, the system comprising a box as described herein and one or more optical systems, wherein the optical system is positioned or positionable to selectively direct one or more, preferably at least two, excitation light projections into a single printing area.

[0141] Preferably, the cartridge is removable or replaceable.

[0142] Optionally, the system may include a robot (e.g., a robot arm or gantry with a gripping mechanism) that can be used to remove a removable / replaceable cartridge from the system, or insert a cartridge into the system. Other suitable means may be used in the alternative.

[0143] Preferably, the cartridge and at least one of the one or more optical systems are movable relative to each other.

[0144] Preferably, the cartridge is reusable. For example, the cartridge can be emptied, cleaned, refilled and reused for printing.

[0145] The system may also include a separator unit for receiving the unpolymerized photopolymerizable composition and one or more printed three-dimensional objects removed from the box through the port. The separator unit is configured to separate any printed three-dimensional objects from the unpolymerized photopolymerizable liquid contained in the discharge content. The separator unit may include a first discharge port for discharging any separated printed objects from the separator. The separator unit may also include a second discharge port for discharging the separated unpolymerized photopolymerizable liquid from the separator unit. Optionally, the separated unpolymerized photopolymerizable liquid can be recycled.

[0146] The separator unit is optionally sealed to prevent the introduction of air or oxygen into the unit during separation.

[0147] The separator unit can mechanically separate any printed objects from the unpolymerized photopolymerizable liquid in the contents removed from the box after printing. Examples of techniques for mechanically separating the printed objects from the unpolymerized photopolymerizable liquid in the discharged contents include, but are not limited to, sieving techniques, extracting any printed objects from the discharged contents using a spoon or claw, a cyclone separator, a spiral separator, a compressed air curtain (e.g., an air knife); and a combination of two or more techniques. In addition to applying stress, heating the unpolymerized photopolymerizable liquid can further enhance the ability of the liquid to flow out and separate from the part.

[0148] Optionally, the second discharge port of the separator unit is adapted to be connected to a return line or recirculation loop for recirculating the separated unpolymerized photopolymerizable composition to the source of photopolymerizable composition to be pumped into the cassette.

[0149] The separated unpolymerized photopolymerizable liquid can be optionally processed or repaired after separation from any printed object. Examples of such processing include, but are not limited to, cleaning / purification, filtration, degassing, centrifugation, solvent or monomer addition.

[0150] The printed objects collected from the separator unit may optionally be post-processed.

[0151] Examples of post-processing include, but are not limited to, washing, post-curing (e.g., by heat, non-ionizing radiation, ionizing radiation, humidity, pressure, or a combination of multiple techniques simultaneously or sequentially), metering, labeling or marking with a trackable device (e.g., barcode, QR code, RFID tag), lyophilization, critical point drying, sterilization (e.g., with UKV, X-rays, electron beam, ethylene oxide, ozone), and packaging.

[0152] Optionally, the system may further comprise a post-processing unit or area for performing one or more selected post-processing steps on the printed object after separation from the unpolymerized photopolymerizable liquid. The post-processing unit or area may be configured to receive the printed object separated from the separator unit.

[0153] The system may further include a recovery unit connected to the optional separator unit (if included) for receiving the separated unpolymerized photopolymerizable composition. The recovery unit may recondition the separated unpolymerized photopolymerizable composition before recycling it for distribution into the cartridge. Preferably, the recovery unit is configured to recondition the separated unpolymerized photopolymerizable composition before recycling it into the storage of the photopolymerizable composition.

[0154] The system may also optionally include a recirculation loop connected to the second discharge port of the optional separator (if present), or to the optional recovery unit (if included), for recycling the separated unpolymerized photopolymerizable composition into a storage of the photopolymerizable composition for future use.

[0155] The system may also include a control system for controlling, for example, the projection of excitation light into one or more printing zones and other aspects of the printing process and system.

[0156] The system may also optionally include a post-processing unit or area.

[0157] The system may also optionally include one or more inspection units or areas for inspecting the printed object after formation.

[0158] The system may further comprise one or more optical systems positioned or positionable to selectively direct one or more, preferably at least two, excitation light projections into the print zone, preferably through an optically transparent region of the print zone.

[0159] Depending on the hardening mechanism of the photohardenable composition, it may be preferred that one or more separate optical systems are positioned or positionable to selectively direct one or more excitation light projections through one or more optically transparent regions of the box into the printing zone.

[0160] Optionally, a single optical system including two light sources may be used, the optical system being configured to project two excitation light projections into the print zone.

[0161] Depending on the photopolymerizable mechanism selected for printing the part, the one or more excitation light projections may include the same wavelength or different wavelengths.

[0162] Multiple optical systems may be provided, positioned simultaneously or sequentially to the same print zone using the same or different excitation lights. For example, two or more optical systems may be located on opposite or adjacent sides of the print zone, or at any other location relative to each other. When multiple optical systems are used to position to a single print zone, the excitation lights from each optical system may fully intersect, partially intersect, or not intersect. It may be desirable that two or more optical excitation light projections from multiple optical systems are directed into the print zone in directions orthogonal to each other. For example, it may be desirable that the orthogonal projections include a light sheet and an optical image.

[0163] Optionally, at least one optical system used with or included in the system is movable relative to the print zone so that one or more, preferably at least two, projections of excitation light can be projected into the print zone from one or more sides of the print zone (e.g., from the top, one side, both sides, the bottom, or any combination including two or more sides). If a movable optical system is to be used, the print zone will include transparent portions or areas to accommodate the projection of excitation light into the print zone from one or more sides. For example, each side or surface of the print zone through which the excitation light passes will be optically transparent, or at least include an optically transparent area through which the excitation light can pass.

[0164] As an example and not limitation, the box may be translated along a first direction ("z") to facilitate printing, or the projection may be translated while the box remains in a fixed position. The projection may also remain fixed by using a variable focus lens or 2D scanning optics. The object is formed (or "painted") by sweeping the intersection of a first light projection (e.g., a light sheet) and a second light projection (e.g., an image) across a first print volume, where the illumination is contained within a reprint zone (or bounding box), and where hardening occurs at each intersection. The box may then be moved, and a second part painted within a second bounding box, and so on.

[0165] Optionally, the excitation light may be temporally and / or spatially modulated. Optionally, the intensity of the excitation light may be modulated.

[0166] Optionally, two or more optical systems direct excitation light of multiple wavelengths through two or more optically transparent regions into separate printing zones. Preferably, at least one optical system directing excitation light of a first wavelength can be modulated. Preferably, at least one optical system directing excitation light of a second wavelength can be moved relative to the printing zone.

[0167] Figure 4 An example of a system of the present invention is shown, the system comprising two optical systems positioned to direct the projection of excitation light into the printing zone.

[0168] The spatially modulated excitation light can be generated by known spatial modulation techniques, including, for example, a liquid crystal display (LCD), a digital micromirror display (DMD), a micro-LED array, a grating light valve, a galvanometer scanner, or a polygonal mirror scanner. Other known spatial modulation techniques can be easily identified by those skilled in the art.

[0169] The optical system may be selected to apply continuous excitation light. The optical system may be selected to apply intermittent excitation light. Intermittent excitation may include randomly turning the light on and off or performing periodic light application. Examples of periodic light application include pulses. The optical system may be selected to apply a combination of continuous excitation light and intermittent excitation light, including, for example, an irradiation step that includes applying intermittent excitation light before or after continuous light irradiation.

[0170] Preferably, the wavelength of the excitation light is in the visible light or ultraviolet light range.

[0171] The optical system may be movable in one or more of the x, y, and z directions relative to a given print zone.

[0172] It may be desirable that the cartridge includes more than one printing zone. Each printing zone will include at least one optically transparent area to facilitate projection of one or more, preferably at least two, excitation lights into the photopolymerizable liquid in each printing zone. As described above, other portions of the printing zone or the entire printing zone may be optically transparent to accommodate at least one optical system to be used and its mobility.

[0173] When the system includes more than one printing zone, the system may include one or more optical systems associated with each printing zone. Alternatively, when the system includes more than one printing zone, the system may include one or more optical systems that are movable relative to the location of at least the printing zone in the box and repositionable so as to shine the excitation light into each printing zone one at a time.

[0174] For example, when it is desired to print multiple objects in a cassette, the cassette includes a number of print zones corresponding to the number of objects to be printed. In this case, the system may optionally include one or more optical systems for each print zone (based on the hardening mechanism involved), or the system may include a single configuration of one or more optical systems, and the first object may be printed in a first print zone, and the cassette may be repositioned to align the next print zone with the optical system configuration to print the next part, and this process may be repeated until the selected number of objects has been printed.

[0175] For example, depending on the photopolymerizable mechanism chosen for printing the part, when two or more excitation light projections are involved, they may include the same or different wavelengths.

[0176] The excitation light projection is usually produced by a separate optical system connected to the excitation light source. One or more light sources may emit the same or a different wavelength than another light source used.

[0177] Preferred optical projection systems for projecting optical images include digital micromirror display projection systems.

[0178] Preferably, the cartridge, optical system and / or other optional components of the system are modular and independently removable and / or replaceable.

[0179] It may be desirable for one or more components of the system to be contained within a single housing.

[0180] Preferably, the system can be light-tight, except for the printing area, to reduce undesired photopolymerization, and any inspection cells or areas can utilize light as part of the inspection / characterization technique.

[0181] Preferably, the boxes and systems described herein can be leakproof (also referred to herein as liquid-tight) to prevent unwanted leakage of the photopolymerizable composition. For example, under leakproof conditions, the photopolymerizable composition will be retained without loss due to leakage.

[0182] In use, the cartridge is filled with a photopolymerizable composition to be selectively photopolymerized in the print zone to form a three-dimensional object.

[0183] Optionally, two or more optical systems direct excitation light of multiple wavelengths through two or more optically transparent regions into the print zone. Preferably, at least one optical system directing excitation light of a first wavelength can be modulated. Preferably, at least one optical system directing excitation light of a second wavelength can be moved relative to the print zone. Figure 4 An example of a system of the present invention is shown, which includes two optical systems positioned to direct the projection of excitation light into the printing zone.

[0184] The system may optionally include more than one printing zone. Each printing zone will include at least one optically transparent area to facilitate the projection of one or more, preferably at least two, excitation lights into the photopolymerizable composition in each printing zone. As described above, other parts of the printing zone or the entire printing zone may be optically transparent to accommodate at least one optical system to be used and its mobility.

[0185] When the system includes more than one printing zone, the system may include one or more optical systems associated with each printing zone. Alternatively, when the system includes more than one printing zone, the system may include one or more optical systems that are movable relative to the position of at least the printing zone and repositionable so as to shine the excitation light into each printing zone one at a time.

[0186] The separator unit, if included, is optionally sealed to prevent the introduction of air or oxygen into the unit during separation.

[0187] Optionally, the system may further include a post-processing unit or area for performing one or more selected post-processing steps on the printed object after separation from the unpolymerized photopolymerizable composition. The post-processing unit or area may be configured to receive the printed object separated from the separator unit.

[0188] The methods described herein preferably include a photopolymerizable composition that exhibits non-Newtonian rheological behavior, and selectively directing one or more excitation light projections into a printing zone to selectively photopolymerize the photopolymerizable composition at one or more selected locations in the printing zone to form a printed object without a support structure, wherein the printed object is maintained in a fixed position or minimally shifted in the unpolymerized photopolymerizable composition during formation.

[0189] In order to allow customization of the 3D printing method (process) performed by the system described herein, it may be desirable that the system be fully or partially modular to accommodate one or more components of the system that are exchanged with one or more replacement components to perform similar corresponding functions but include features and / or capabilities to achieve the specific customization desired. For example, a box can be replaced with a larger or smaller box to accommodate different sizes or capacities, a box can be replaced with multiple boxes, a box can be replaced with a box including one or more optically transparent areas that are configured to accommodate one or more optical systems selected; an optical system can be replaced with one or more systems having different excitation wavelengths and / or power capabilities; if a separator is included in the system, the separator can be replaced with a separator that achieves separation of printed parts from unpolymerized photopolymerizable composition through a specific technique; if a post-processing component is included, the post-processing component can be selected based on the desired post-processing steps selected.

[0190] Optionally, the box and / or optical system (whether internal or external to the printing device) can also be adapted to move, for example, in one or more of the x, y, and z directions to selectively direct the projection of excitation light to one or more selected locations in the printing zone during printing or forming a 3D object. Such movement can be achieved by an x, y, z translation stage (not shown). Optionally, the unpolymerized photopolymerizable composition from which the printed object is separated can be reused or recycled, as described herein.

[0191] The system may include separate modules operably connected for 3D printing an object having a selected design contained in a volume of photopolymerizable composition within a printing zone of a cartridge; discharging the contents of the cartridge into a separator to separate the printed object from unpolymerized photopolymerizable composition; and transporting the separated printed object to a post-processing unit or area of ​​the system to perform one or more desired post-processing steps.

[0192] Alternatively, the system may include a system in which one or more components are included in a unitary housing.

[0193] According to another aspect of the present invention, a method for printing one or more three-dimensional objects is provided, the method comprising: providing a certain volume of photopolymerizable composition in the box described herein, and directing one or more, preferably at least two, excitation light projections into each printing area to selectively photopolymerize the photopolymerizable composition at one or more selected positions in the printing area, thereby at least partially forming a three-dimensional printed object within the volume of photopolymerizable composition in the printing area.

[0194] The method may further include separating any printed objects from unpolymerized photopolymerizable composition included in the contents removed from the cartridge after printing.

[0195] Optionally, the method is performed in a light-tight environment, except for the printing area and any inspection elements or areas where light may be utilized as part of the inspection / characterization technique, to reduce the occurrence of undesired photopolymerization.

[0196] Optionally, the method further comprises recovering separated unpolymerized photopolymerizable composition from the removed contents.

[0197] Optionally, the method may further include treating or modifying the separated unpolymerized photopolymerizable composition after separation from any printed object. Examples of such treatments include, but are not limited to, cleaning / purification, filtration, degassing, centrifugation, solvent or monomer addition.

[0198] The method may further include post-processing the at least partially formed three-dimensional object after separation from the unpolymerized photopolymerizable composition.

[0199] For example, the method may also include one or more of the following: washing / cleaning the separated object; post-curing the at least partially formed three-dimensional object after separation from the unpolymerized photopolymerizable composition (e.g., by heating or ultraviolet light); inspecting the at least partially formed three-dimensional object; packaging the object, etc.

[0200] Optionally, the process is carried out in an inert atmosphere.

[0201] The systems described herein can be used to perform the various methods described herein.

[0202] In one example of the method, 1) a resin or photohardenable composition is photocured without a support structure so that the parts are suspended therein; 2) the resin or photohardenable composition is thixotropic (shear thinning) or has a yield stress so that the parts remain fixed in space or undergo minimal displacement during the curing operation; 3) after applying pressure or other force, the cured one or more parts are removed from the box; 4) the parts are separated from the unpolymerized photohardenable composition (which may also be referred to as resin herein); and 5) the unpolymerized photohardenable composition is optionally recovered.

[0203] The methods of the present invention may utilize light-induced curing of a photopolymerizable composition to produce one or more printed objects.

[0204] Preferably, the photopolymerizable composition exhibits non-Newtonian rheological behavior so that an object formed in the photopolymerizable composition in the printing area remains in a fixed position or undergoes minimal displacement in the unpolymerized photopolymerizable composition during formation, and excitation light is guided through at least the optically transparent window into the printing area to selectively photopolymerize the photopolymerizable composition in the printing area without a supporting structure to form a printed object, wherein the printed object remains in a fixed position or undergoes minimal displacement in the unpolymerized photopolymerizable composition during formation.

[0205] Examples of such non-Newtonian rheological behavior include pseudoplastic fluids, yield pseudoplastics, or Bingham plastomers. Such properties may be due to a combination of reactive components (monomers and oligomers) in the resin, or may be imparted by non-reactive additives (thixotropic agents, rheology modifiers). The formulation / recipe of a photopolymerizable component that exhibits non-Newtonian behavior is within the skill of one skilled in the relevant art. Examples include a formulation of a photopolymerizable composition for use in the present method that includes 86 parts of GENOMER 4259 (aliphatic urethane acrylate), 14 parts of N,N-dimethylacrylamide, 13.3 parts of a 60 wt% dispersion of nanoparticles in N,N-dimethylacrylamide, 2 parts of Rheobyk 410 thixotropic agent, 0.5 parts of bis(2,6-difluoro-3-(1-hydropyrrol-1-yl)phenyl)titanocene photoinitiator, and 0.001 parts of 2,2,6,6-tetramethyl-1-piperidinyloxy free radical inhibitor. Another example of a photopolymerizable composition formulation for use in the present method includes 90 parts GENOMER 4247 (aliphatic urethane methacrylate), 10 parts N,N-dimethylacrylamide, 1.2 parts Crystasense HP-5 thixotrope (polyalkyleneoxy terminated polyamide), 0.20 parts butyrylcholine butyltriphenylborate, and 0.005 parts 1'-benzyl-3',3'-dimethyl-8-iodo-7-methoxy-6-nitrobenzospiropyran photoswitchable photoinitiator.

[0206] For photopolymerizable compositions that exhibit non-Newtonian rheological behavior, the preferred steady state shear viscosity is less than 10,000 cP, and most preferably less than 1,000 cP. (The steady state shear viscosity refers to the viscosity after the thixotropic network is broken.)

[0207] Preferred photopolymerizable compositions included in the methods and / or systems described herein comprise a photohardenable component, a photoswitchable photoinitiator, and a co-initiator, wherein the photoswitchable photoinitiator can be activated by exposure to light having a first wavelength and light having a second wavelength to induce a crosslinking or polymerization reaction in the photohardenable component, wherein the first wavelength and the second wavelength are different, and wherein the photopolymerizable composition exhibits non-Newtonian rheological behavior.

[0208] In the discussion of other aspects of the invention, additional information that may be helpful with the components / steps included in the method may be found elsewhere herein.

[0209] Examples of sources of excitation light sources for the methods described herein include laser diodes, such as commercially available laser diodes, light emitting diodes, DMD projection systems, micro-LED arrays, vertical cavity lasers (VCL). In some embodiments, the excitation radiation source (e.g., light source) is a light emitting diode (LED).

[0210] The system and method according to the present invention are particularly useful for printing three-dimensional (3D) objects from a photopolymerizable composition that exhibits non-Newtonian behavior and can be cured at a volumetric location irradiated with stimulated light to form a printed object without the need to add support structures. Most 3D printing technologies involving VAT polymerization technology typically require support structures to stabilize the part during printing or allow printing of thin and fragile overhanging parts of the part; after printing, post-processing is required to remove the support structure, which may damage the printed part or leave marks on the printed part. Avoiding the addition of support structures will advantageously simplify the post-processing process of the printed part.

[0211] The systems and methods according to the present invention are particularly useful for printing three-dimensional (3D) objects from a photopolymerizable composition that exhibits non-Newtonian behavior and can be cured at volumetric locations irradiated by stimulated light to form a printed object without the need to add a support structure, which advantageously simplifies the separation of the part from the unpolymerized polymerizable liquid because when stress is applied, the apparent viscosity of the non-Newtonian photopolymerizable composition drops to a value (e.g., steady-state shear viscosity) lower than a static value (e.g., zero shear viscosity or yield stress), which allows the unpolymerized polymerizable liquid to flow out more easily and be separated from the part.

[0212] Systems and methods according to the present invention also advantageously do not require the printed object to be adhered to a fixed substrate (eg, a build plate) at the beginning of the printing process, avoiding a post-processing step of separating the printed object from the fixed substrate.

[0213] Post-processing steps to remove support structures and / or remove the printed object from the fixed substrate add labor (e.g., manual removal), waste (discarded support structures), and reduce throughput (the build plate cannot be reused until the printed object is removed), all of which increase process costs.

[0214] Optionally, depending on the oxygen sensitivity of the photopolymerizable composition used, the photopolymerizable composition is purged or sprayed with an inert gas before introduction into the cartridge and maintained in an inert atmosphere during printing. The photopolymerizable composition source and the photopolymerizable composition contained in the reservoir used to feed the cartridge may also be optionally cleaned and maintained under inert conditions prior to use in the systems and methods of the present invention.

[0215] The method and system according to the present invention are also particularly useful for printing 3D objects from a photopolymerizable composition that exhibits non-Newtonian behavior and can be cured at volume locations by two-color photopolymerization under irradiation with excitation light of two different wavelengths.

[0216] Preferably, the photopolymerizable composition comprises (i) a photopolymerizable component; and (ii) a dual-color photoinitiator (also referred to herein as a photoswitchable photoinitiator), which initiates polymerization of the photopolymerizable component under simultaneous or sequential excitation by light of two different wavelengths, wherein the photopolymerizable composition exhibits non-Newtonian behavior.

[0217] As described herein, the photopolymerizable composition may preferably comprise: a photopolymerizable component; a dual-color photoinitiator that is converted from an inactive (non-initiated) form to an active (initiated) form by excitation light of a first wavelength, wherein subsequent or simultaneous excitation light of a second wavelength absorbed by the active form cures the photopolymerizable component; and an optional synergist that promotes photoinitiation of the active form of the dual-color photoinitiator in a combined manner, for example, by electron transfer or hydrogen transfer.

[0218] The dual-color photoinitiator or photo-switchable photoinitiator may contain a photochromic dye. The dual-color photoinitiator preferably spontaneously recovers from the active form to the inactive form (T-type photochromic) by thermal energy at ambient temperature. Various types of T-type photochromic dyes are known to those skilled in the art, including but not limited to spiropyrans. These dyes form merocyanine dyes (active forms) by photoactivated ring opening. The active form can then absorb light of different wavelengths to form an excited state of the active form, which can then induce photoinitiation alone or in combination with a co-initiator or synergist (e.g., amine, thiol, organic borate compound). Important properties for selecting a dual-color photoinitiator include the absorption spectra of the inactive and active forms; the switching rate of the conversion between the two forms; and the equilibrium concentration of the two forms; and the intersystem crossover yield of the excited state of the active form. The high intersystem crossover yield of the excited state of the active form is conducive to the generation of a triplet excited state with a longer life span, which can interact with the synergist to induce photoinitiation by electron, proton or energy transfer. An example of a suitable two-color photoinitiator is 1'-benzyl-3',3'-dimethyl-8-iodo-7-methoxy-6-nitrobenzospiropyran.

[0219] Co-initiators or synergists may include, for example, amines, thiols, thioethers, mercaptans, silanes, organic borate compounds, diaryliodonium salts, triarylsulfonium salts. A preferred example of a suitable synergist is butyrylcholine butyltriphenylborate.

[0220] The photopolymerizable composition may also contain additional additives. Examples of such additives include, but are not limited to, thixotropic agents, oxygen scavengers, and the like.

[0221] Examples of excitation light sources for the methods described herein include laser diodes, such as commercially available laser diodes, light emitting diodes, DMD projection systems, micro-LED arrays, vertical cavity lasers (VCL). In some embodiments, the excitation radiation source (e.g., light source) is a light emitting diode (LED).

[0222] The system and method according to the present invention are also particularly useful for printing 3D objects from a photopolymerizable composition that exhibits non-Newtonian behavior and can be cured by sequential or simultaneous illumination of a volumetric location with excitation light of two different wavelengths. Most preferably, the photopolymerizable composition comprises a two-color photoinitiator that is converted from an inactive form to an active form by excitation with a first wavelength and then subsequently excited with a second wavelength, which alone or through interaction with a synergist induces photoinitiation and subsequently cures the photopolymerizable composition.

[0223] Preferably, the photopolymerizable composition comprises (i) a photopolymerizable component; (ii) a two-color photoinitiator; and (iii) a co-initiator or synergist. More preferably, the photopolymerizable composition exhibits non-Newtonian behavior.

[0224] The first wavelength and the second wavelength may be in the ultraviolet, visible or near infrared range. Preferably, the first wavelength is in the ultraviolet range and the second wavelength is in the visible range.

[0225] Examples of photoconvertible photoinitiators that can be used in the photopolymerizable composition can absorb at about 300 nm to about 550 nm, including but not limited to about 300 nm to about 450 nm. Depending on the absorption spectrum of the specific photoconvertible photoinitiator, the conversion to the second form can be induced by exposure to any source (e.g., laser, light emitting diode, mercury lamp) that emits in this range. Filters can be used to limit the output wavelength. Non-limiting examples of filtered light include filtered emission from a mercury arc lamp, etc. The second form of the photoconvertible photoinitiator preferably absorbs in the range of about 450 to 1000 nm, most typically in the range of 450 to 850 nm.

[0226] Examples of the power density of the first wavelength light include about 0.01 to about 100,000 W / cm 2 Examples of the power density of the second wavelength light include about 0.01 to about 100,000 W / cm 2 Power density within the range (including the end points).

[0227] Examples of the exposure energy of the first wavelength light include about 0.001 to about 1000 mJ / cm 2 The exposure energy of the second wavelength light includes an exposure energy in the range of about 0.01 to about 100,000 mJ / cm2 Exposure energy within the range (including the endpoints).

[0228] Preferably, light of the first wavelength and light of the second wavelength are projected into the volume as separate optical projections. More preferably, light of the first wavelength is directed into the volume along a light sheet illumination axis orthogonal to the direction in which the projection of light of the second wavelength is directed.

[0229] Preferably, the light of the first wavelength comprises a light sheet.The light sheet may desirably comprise a light emitting planar structure having opposing major faces, the major faces being parallel to the direction in which the light sheet is directed into the volume.

[0230] Preferably, the projection of the second wavelength light comprises an optical image which is perpendicular to the direction in which the optical image is directed or projected into the volume.A digital micromirror device (DMD) is preferably used for the projection of the optical image.

[0231] In a preferred embodiment, the light sheet is directed into the volume along a light sheet illumination axis and the optical image is directed into the volume along a projection or illumination axis, wherein the light sheet illumination axis and the projection axis are orthogonal to each other and the optical image is orthogonal to the projection axis, such that the light sheet and the optical image intersect in a common plane. It is desirable that the intersection of the light sheet and the optical image is coplanar or substantially coplanar.

[0232] The optical image may include any optical projection generated by an optical projection system. Examples of optical images include, but are not limited to, patterned or unpatterned two-dimensional images, rays, or single light points. The two-dimensional image may include a cross-section of the three-dimensional image being printed. The two-dimensional image may represent a cross-sectional slice of the object to be printed. Such cross-sectional slices are typically generated using slicing software.

[0233] Examples of excitation light sources that may be suitable for the methods described herein include, by way of example, but are not limited to, lasers, laser diodes, light emitting diodes, light emitting diodes (LEDs), micro-LED arrays, vertical cavity lasers (VCLs), and filter lamps. Such light sources are commercially available, and a person of ordinary skill in the relevant art can easily select a suitable light source. It may be preferred that the type of LED used with a DMD, such as the Phlatlight LED provided by Luminus. Other suitable light sources may also be available.

[0234] Optionally, the excitation light may be temporally and / or spatially modulated. Optionally, the intensity of the excitation light may be modulated.

[0235] Examples of projection devices for the methods and systems described herein may include, but are not limited to, laser projection systems, liquid crystal displays (also referred to herein as “LCDs”), spatial light modulators (also referred to herein as “SLMs”) (such as, but not limited to, digital micromirror devices (also referred to herein as “DMDs”)), micro-LED arrays, vertical cavity laser arrays (also referred to herein as “VCLs”), vertical cavity surface emitting laser arrays (also referred to herein as “VCSELs”), liquid crystal on silicon (also referred to herein as “LCoS”) projectors, and scanning laser systems. (Light emitting diodes are also referred to herein as “LEDs”).

[0236] The optical image projection system may also optionally include one or more optical components (eg, projection optics, illumination optics, lenses, lens systems, mirrors, prisms, etc.).

[0237] Additional information that can be used to connect dual wavelength photoinitiators and their uses includes U.S. Patent No. 5,230,986 to Neckers; U.S. Patent Nos. 4,041,476, 4,078,229, 4,238,840, 4,466,080, 4,471,470 and 4,333,165 to Swainson; U.S. Patent No. 4,575,330 to Hull; U.S. Patent No. 10,843,410 to Lippert et al., "System And Method For A Three-Dimensional Optical Switch Display (OSD) Device", each of which is incorporated herein by reference in its entirety.

[0238] Optionally, depending on the oxygen sensitivity of the photopolymerizable composition used, the photopolymerizable composition is purged or sparged with an inert gas before introduction into the box and maintained in an inert atmosphere while in the closed box. The photopolymerizable composition source and the photopolymerizable composition contained in the reservoir used to feed the closed box can also be optionally purged and maintained under inert conditions prior to use in the systems and methods of the present invention.

[0239] The selected dimensions of the system (eg, height, width, footprint) may also factor into the size, shape, and orientation of boxes and other components (eg, regions, units, modules, etc.) included in the system.

[0240] Non-limiting examples of embodiments of the invention

[0241] Embodiment 1 is a box for printing one or more three-dimensional objects, wherein the box is configured to accommodate a certain volume of a photopolymerizable composition, the box includes side walls, preferably four side walls, the side walls are connected to the bottom wall to define a volume space for accommodating the volume, and the box is configured to include one or more printing areas, wherein the size of the printing area is designed to facilitate being irradiated by one or more, preferably at least two, excitation light projections to at least partially form a three-dimensional printed object in the volume of photopolymerizable composition in the printing area. The box can be open and can optionally include a removable lid or top wall opposite to the bottom. Optionally, at least one of the walls may include at least one openable / closable port to facilitate the introduction of unpolymerized photopolymerizable composition and / or the removal of unpolymerized photopolymerizable composition and / or the removal of one or more three-dimensional objects from the box.

[0242] Embodiment 2 is a box for printing one or more three-dimensional objects, wherein the box is configured to accommodate a certain volume of photopolymerizable composition, the box includes side walls, the side walls are connected to the bottom wall to define a volume space for accommodating the volume, and the box is configured to include one or more printing areas, wherein the size of the printing area is designed to facilitate illumination by one or more, preferably at least two, excitation light projections to at least partially form a three-dimensional printed object within the volume of photopolymerizable composition in the printing area.

[0243] Embodiment 3 is a box as described in embodiment 1 or 2, wherein the box includes two or more printing zones, and wherein the printing zones are spaced apart from each other so that the excitation light projection can be directed into one printing zone to at least partially form a three-dimensional object without triggering photopolymerization of the photopolymerizable composition in an adjacent printing zone.

[0244] Embodiment 4 is a box as described in embodiment 1 or 2, wherein the box includes two or more printing zones, and wherein the dimensions of the printing zones are designed so that three-dimensional objects at least partially formed in adjacent printing zones do not contact each other during printing.

[0245] Embodiment 5 is a box as described in embodiment 2, wherein the box includes a first port for introducing the photopolymerizable composition into the box and a second port for removing unpolymerized photopolymerizable composition and / or one or more three-dimensional objects from the box.

[0246] Embodiment 6 is a box as described in embodiment 2, wherein the port is openable and closable.

[0247] Embodiment 7 is a box as described in embodiment 1 or 2, wherein the printing area has a size based on the size of the object to be printed, the numerical aperture characteristics of the projected light projection, the refractive index of the photopolymerizable composition (or suitable alternatives).

[0248] Embodiment 8 is a box as described in embodiment 7, wherein the box includes two or more printing zones, and wherein the printing zones are spaced apart from each other so that the excitation light projection can be directed into one printing zone to at least partially form a three-dimensional object without triggering photopolymerization of the photopolymerizable composition in an adjacent printing zone.

[0249] Embodiment 9 is a box as described in embodiment 7, wherein the box includes two or more printing zones, and wherein the dimensions of the printing zones are designed so that three-dimensional objects at least partially formed in adjacent printing zones do not contact each other during printing.

[0250] Embodiment 10 is a box as described in embodiment 3, wherein the size of the printing area is designed to prevent objects printed in adjacent printing areas from contacting each other during printing.

[0251] Embodiment 11 is a box as described in embodiment 9, wherein the size of the printing area is designed to prevent objects printed in adjacent printing areas from contacting each other during printing.

[0252] Embodiment 12 is a box as described in embodiment 1 or 2, wherein the box has a rectangular prism shape.

[0253] Embodiment 13 is a box as described in embodiment 1 or 2, wherein the box has a uniform cross-section along its longest dimension.

[0254] Embodiment 14 is a box as described in embodiment 12, wherein the box has a uniform cross-section along its longest dimension.

[0255] Embodiment 15 is a box as described in embodiment 1 or 2, wherein the box has a rectangular cross-section.

[0256] Embodiment 16 is a box as described in embodiment 1 or 2, wherein the box is optically transparent.

[0257] Embodiment 17 is a box as described in embodiment 12, wherein the box is optically transparent.

[0258] Embodiment 18 is a box as described in embodiment 1 or 2, wherein the box is optically flat.

[0259] Embodiment 19 is a box as described in embodiment 12, wherein the box is optically flat.

[0260] Embodiment 20 is a box as described in embodiment 1 or 2, wherein the box includes one or more optically transparent areas, which are positioned to guide the projection of excitation light and the passage of excitation light projection into the printing area in the box.

[0261] Embodiment 21 is a box as described in embodiment 12, wherein the box includes one or more optically transparent areas that are positioned to guide the projection of excitation light and the passage of the excitation light projection into the printing area in the box.

[0262] Embodiment 22 is a box as described in embodiment 1 or 2, wherein the box includes straight walls that intersect at a 90° angle.

[0263] Embodiment 23 is a box as described in embodiment 12, wherein the box includes straight walls that intersect at a 90° angle.

[0264] Embodiment 24 is a box as described in embodiment 22, wherein the walls of the box are fused together at their edges to form a three-dimensional rectangle.

[0265] Embodiment 25 is a box as described in embodiment 23, wherein the walls of the box are fused together at their edges.

[0266] Embodiment 26 is a box as described in embodiment 1 or 2, wherein the walls of the box are held together by a frame to form a three-dimensional rectangle.

[0267] Embodiment 27 is a box as described in embodiment 1 or 2, wherein one or more walls of the box include an anti-reflective coating.

[0268] Embodiment 28 is a box as described in embodiment 1 or 2, wherein one or more walls of the box include a mechanical strengthening coating.

[0269] Embodiment 29 is a box as described in embodiment 1 or 2, wherein one or more walls of the box include a chemical-resistant coating.

[0270] Embodiment 30 is a box as described in embodiment 1 or 2, wherein one or more walls of the box include a coating on its inner surface to enhance its cleanability.

[0271] Embodiment 31 is a system for printing one or more three-dimensional objects, the system comprising a box for printing one or more three-dimensional objects, the box being configured to hold a volume of a photopolymerizable composition, the box comprising side walls connected to a bottom wall to define a volumetric space holding the volume, the box being configured to include one or more printing zones, wherein the size of the printing zones is designed to facilitate illumination by one or more, preferably at least two, excitation light projections to at least partially form a three-dimensional printed object within the volume of photopolymerizable composition in the printing zone; and one or more optical systems, wherein the optical systems are positioned or positionable to selectively direct one or more, preferably at least two, excitation light projections into a single printing zone.

[0272] Embodiment 32 is a system for printing one or more three-dimensional objects, the system comprising a box configured to hold a certain volume of photopolymerizable composition, the box comprising opposing end walls and including at least one port in at least one end wall of the box to facilitate the introduction of unpolymerized photopolymerizable composition and / or the removal of unpolymerized photopolymerizable composition and / or the removal of one or more three-dimensional objects from the box, the box being configured to include one or more printing zones, wherein the size of the printing zones is designed to facilitate illumination by one or more, preferably at least two, excitation light projections to at least partially form a three-dimensional printed object within the volume of photopolymerizable composition in the printing zone; and one or more optical systems, wherein the optical systems are positioned or positionable to selectively direct one or more, preferably at least two, excitation light projections into a single printing zone.

[0273] Embodiment 33 is a system as described in embodiment 31 or 32, wherein the box and at least one of the one or more optical systems are movable relative to each other.

[0274] Embodiment 34 is a system as described in embodiment 31 or 32, which also includes a separator unit for removing unpolymerized photopolymerizable composition and one or more printed three-dimensional objects from the box.

[0275] Embodiment 35 is a system as described in embodiment 31 or 32, wherein the separator unit is capable of separating the printed three-dimensional object from the unpolymerized photopolymerizable composition contained in the removed contents.

[0276] Embodiment 36 is a system as described in embodiment 34, wherein the separator unit includes an exhaust port for exhausting any separated printed objects from the separator unit.

[0277] Embodiment 37 is a system as described in embodiment 34, wherein the separator unit includes an exhaust port for exhausting any separated printed objects from the separator unit.

[0278] Embodiment 38 is the system of embodiment 37, wherein the separator unit further comprises a second exhaust port for discharging the separated unpolymerized photopolymerizable composition from the separator unit.

[0279] Embodiment 39 is a system as described in embodiment 34, which also includes a recovery unit connected to the separator unit for receiving the separated unpolymerized photopolymerizable composition for recovery.

[0280] Embodiment 40 is a system as described in embodiment 38, wherein the system also includes a recycling loop connected to the second discharge port for recycling the separated unpolymerized photopolymerizable composition into the storage of the photopolymerizable composition.

[0281] Embodiment 41 is a system as described in embodiment 39, wherein the system also includes a recycling loop connected to the recovery unit for recycling the separated unpolymerized photopolymerizable composition into the storage of the photopolymerizable composition.

[0282] Embodiment 42 is a system as described in embodiment 39, wherein the recovery unit is configured to repair the separated unpolymerized photopolymerizable composition before recycling it into the storage of the photopolymerizable composition.

[0283] Embodiment 43 is a system as described in embodiment 31 or 32, wherein a single optical system is configured to project one or more, preferably at least two, excitation light projections into a printing area.

[0284] Embodiment 44 is a system as described in embodiment 31 or 32, wherein the system includes at least two excitation light projections comprising the same wavelength.

[0285] Embodiment 45 is a system as described in embodiment 43, wherein the system includes at least two excitation light projections comprising the same wavelength.

[0286] Embodiment 46 is a system as described in embodiment 31 or 32, wherein the system includes at least two excitation light projections comprising different wavelengths.

[0287] Embodiment 47 is a system as described in embodiment 43, wherein the system includes at least two excitation light projections comprising different wavelengths.

[0288] Embodiment 48 is a system as described in embodiment 31 or 32, wherein the box is removable or replaceable.

[0289] Embodiment 49 is a system as described in embodiment 31, wherein the box includes one or more ports in at least one wall, wherein at least one port is preferably openable and closable.

[0290] Embodiment 50 is a system as described in embodiment 31 or 32, wherein the optical system is connected to one or more excitation light sources.

[0291] Embodiment 51 is a system as described in embodiment 31 or 32, wherein the excitation light projection is generated by a separate optical system connected to the excitation light source.

[0292] Embodiment 52 is a system as described in embodiment 31 or 32, wherein the excitation light projection is generated by a separate optical system connected to an excitation light source emitting a different wavelength.

[0293] Embodiment 53 is a system as described in embodiment 31 or 32, wherein at least one of the optical systems includes a digital micromirror display projection system.

[0294] Embodiment 54 is a system as described in embodiment 31 or 32, wherein at least one of the optical systems includes a light sheet generation system.

[0295] Embodiment 55 is a system as described in embodiment 53, which also includes an optical system including a light sheet generating system.

[0296] Embodiment 56 is a system as described in embodiment 55, wherein the wavelength of light projected by the digital micromirror display projection system is different from the wavelength of light projected by the light sheet generation system.

[0297] Embodiment 57 is a system as described in embodiment 31 or 32, which also includes a post-processing unit or area.

[0298] Embodiment 58 is a system as described in embodiment 31 or 32, which also includes one or more inspection units or areas for inspecting the printed object after formation.

[0299] Embodiment 59 is a system as described in embodiment 31 or 32, wherein the box, optical system and other optional components of the system are modular and can be independently removed and / or replaced.

[0300] Embodiment 60 is a system as described in embodiment 31 or 32, wherein one or more of the optical systems are replaceable.

[0301] Embodiment 61 is a system as described in embodiment 31 or 32, wherein one or more components of the system are included in a single housing.

[0302] Embodiment 62 is the system of embodiment 31, wherein the box further comprises (i) a top wall and at least one openable / closable port, or (ii) a removable lid.

[0303] Embodiment 63 is a system as described in embodiment 31 or 32, wherein the box wall includes one or more optically transparent regions associated with the printing zone to facilitate guiding the excitation light projection through the one or more optically transparent regions into the printing zone.

[0304] Embodiment 64 is a method of printing one or more three-dimensional objects, the method comprising:

[0305] providing a volume of photopolymerizable composition in a box configured to hold the volume of photopolymerizable composition, the box comprising side walls, preferably four side walls, connected to a bottom wall to define a volume space for holding the volume, the box being configured to include one or more printing zones, wherein the printing zones are sized to be illuminated by one or more, preferably at least two, excitation light projections to at least partially form a three-dimensional printed object within the volume of photopolymerizable composition in the printing zones, and

[0306] At least two excitation light projections are directed into each printing zone to selectively photopolymerize the photopolymerizable composition at one or more selected locations in the printing zone.

[0307] Embodiment 65 is a method of printing one or more three-dimensional objects, the method comprising:

[0308] providing a volume of photopolymerizable composition in a box configured to hold the volume of photopolymerizable composition, the box comprising opposed end walls and comprising at least one port in at least one of the end walls of the box to facilitate introduction of unpolymerized photopolymerizable composition and / or removal of unpolymerized photopolymerizable composition and / or removal of one or more three-dimensional objects from the box, the box being configured to include one or more printing zones, wherein the printing zones are sized to facilitate illumination by one or more, preferably at least two, excitation light projections to at least partially form a three-dimensional printed object within the volume of photopolymerizable composition in the printing zones, and

[0309] The one or more, preferably at least two, excitation light projections are directed into each printing zone to selectively photopolymerize the photopolymerizable composition at one or more selected locations in the printing zone, thereby at least partially forming a three-dimensional printed object within the volume of photopolymerizable composition in the printing zone.

[0310] Embodiment 66 is a method as described in embodiment 64, wherein the box includes one or more ports in at least one wall, wherein at least one port is preferably openable and closable.

[0311] Embodiment 67 is a method as described in Embodiment 65, wherein the port is openable and closable.

[0312] Embodiment 68 is a method as described in embodiment 65, wherein the box includes a port at each end, and wherein each port is openable and closable.

[0313] Embodiment 69 is a method as described in embodiment 64 or 65, wherein the photopolymerizable composition exhibits non-Newtonian rheological behavior, and the one or more, preferably at least two excitation light projections are selectively directed into the printing area to selectively photopolymerize the photopolymerizable composition at one or more selected locations in the printing area, thereby forming a printed object without a supporting structure.

[0314] Embodiment 70 is a method as described in embodiment 69, wherein the printed object is maintained in a fixed position or undergoes minimal displacement in the unpolymerized photopolymerizable composition during formation.

[0315] Embodiment 71 is a method as described in embodiment 70, wherein the minimum displacement includes an amount of displacement of the printed object that is acceptable for accurately reproducing the geometry of the object to be printed during the time interval required to form the object.

[0316] Embodiment 72 is a method as described in embodiment 64 or 65, wherein the one or more, preferably at least two, excitation light projections are selectively directed into the printing area to selectively photopolymerize the photopolymerizable composition at one or more selected locations in the printing area, thereby printing an object without a supporting structure.

[0317] Embodiment 73 is a method as described in embodiment 64 or 65, wherein the box has a uniform cross-section along its length dimension.

[0318] Embodiment 74 is a method as described in embodiment 64 or 65, wherein the box has a rectangular or square cross-section.

[0319] Embodiment 75 is a method as described in embodiment 64 or 65, wherein the box has a non-uniform cross-section along its length dimension.

[0320] Embodiment 76 is a method as described in embodiment 64 or 65, wherein the box is optically transparent.

[0321] Embodiment 77 is a method as described in embodiment 64 or 65, wherein the box is optically flat.

[0322] Embodiment 78 is a method as described in embodiment 64 or 65, wherein the box includes one or more optically transparent areas that are positioned to guide the projection of excitation light and the passage of the excitation light projection into the printing area in the box.

[0323] Embodiment 79 is the method of embodiment 64, wherein the box further comprises (i) a top wall and at least one openable / closable port, or (ii) a removable lid.

[0324] Embodiment 80 is a method as described in embodiment 64 or 65, wherein the method is carried out in an inert atmosphere.

[0325] Embodiment 81 is a method as described in Embodiment 64 or 65, wherein the method is carried out in a non-inert atmosphere.

[0326] Embodiment 82 is a method as described in embodiment 64 or 65, which also includes separating the at least partially formed three-dimensional object from the unpolymerized photopolymerizable composition contained in the box.

[0327] Embodiment 83 is a method as described in embodiment 64 or 65, which also includes recovering the unpolymerized photopolymerizable composition after separating the at least partially formed three-dimensional object from the unpolymerized photopolymerizable composition.

[0328] Embodiment 84 is a method as described in embodiment 64 or 65, wherein the photopolymerizable composition exhibits non-Newtonian rheological behavior so that an object formed in the photopolymerizable composition in the printing zone remains in a fixed position or undergoes minimal displacement in an unpolymerized photopolymerizable composition during formation, and excitation light is guided through the optically transparent area of ​​the box into the printing zone to selectively photopolymerize the photopolymerizable composition in the printing zone in the absence of a supporting structure, wherein the printed object remains in a fixed position or undergoes minimal displacement in the unpolymerized photopolymerizable composition during formation.

[0329] Embodiment 85 is a method as described in embodiment 64 or 65, wherein the photopolymerizable composition comprises a photohardenable component and a photoconvertible photoinitiator, wherein the photoconvertible photoinitiator can be activated by exposure to light having a first wavelength and light having a second wavelength to induce a crosslinking or polymerization reaction in the photohardenable composition, wherein the first wavelength is different from the second wavelength.

[0330] Embodiment 86 is a method as described in embodiment 85, wherein the photopolymerizable composition exhibits non-Newtonian rheological behavior.

[0331] Embodiment 87 is a method as described in embodiment 85, wherein the photopolymerizable composition further comprises a co-initiator.

[0332] Embodiment 88 is a method as described in embodiment 85, wherein the photopolymerizable composition further comprises a sensitizer.

[0333] Embodiment 89 is a method as described in embodiment 85, wherein the photopolymerizable composition further comprises a synergist.

[0334] Embodiment 90 is the method of embodiment 85, further optionally comprising at least one of a coinitiator, a synergist, and a sensitizer.

[0335] Embodiment 91 is a method as described in embodiment 64 or 65, which also includes post-processing the at least partially formed three-dimensional object after separation from the unpolymerized photopolymerizable composition.

[0336] Embodiment 92 is a method as described in embodiment 64 or 65, which also includes post-curing the at least partially formed three-dimensional object after separation from the unpolymerized photopolymerizable composition.

[0337] Embodiment 93 is a method as described in embodiment 64 or 65, which also includes inspecting the at least partially formed three-dimensional object.

[0338] Embodiment 94 is a method as described in embodiment 64 or 65, wherein at least one of the optical systems includes a digital micromirror display projection system.

[0339] Embodiment 95 is a method as described in embodiment 64 or 65, wherein at least one of the optical systems includes a light sheet generation system.

[0340] Embodiment 96 is a method as described in embodiment 64 or 65, which also includes an optical system comprising a light sheet generating system.

[0341] Other information that may be used in connection with the present invention includes International Patent Application No. PCT / US2021 / 035791, filed by Quadratic 3D, Inc. on June 3, 2021, entitled “Volumetric Three-Dimensional Printing Methods Including A Light Sheet And Systems” (published as WO 2021 / 247930 A1 on December 9, 2021) and U.S. Patent Application No. 63 / 223,112, filed by Quadratic 3D, Inc. on July 19, 2021, and International Application No. PCT / US2021 / 024878, filed by Quadratic 3D, Inc. on March 30, 2021 (published as WO 2021 / 202524 A1 on October 7, 2021), each of which is incorporated herein by reference in its entirety.

[0342] The systems and methods of the present invention can be used in other 3D printing technologies that involve initiating photochemical reactions in photoreactive systems by absorbing light energy provided by one or more excitation light projections to form objects. Examples include tomography, two-photon printing, upconversion printing, and dual-wavelength printing.

[0343] Prior to printing, a digital file of the object to be printed is obtained. If the digital file is not in a format that can be used to print the object, the digital file is converted into a format that can be used to print the object. An example of a typical format that can be used for printing is an STL file. Typically, the STL file is then cut into two-dimensional layers using three-dimensional slicer software and converted into G-code, or a set of machine commands, which helps build the object. See B. Redwood et al., "The 3D Printing Handbook - Technologies, designs applications," 3D HUBS BV 2018.

[0344] When used as a feature of a portion of a box or build chamber, "optically clear" means highly transparent to the wavelength of light used, and "optically flat" means undistorted (e.g., the optical wavefront entering the box or build chamber is largely unaffected).

[0345] As used herein, the singular forms "a", "an", and "the" include the plural forms as well, unless the context clearly dictates otherwise. Thus, for example, reference to an emissive material includes reference to one or more of such materials.

[0346] The applicant specifically incorporates the full content of all cited references into the present disclosure. In addition, when equivalent, concentration or other values ​​or parameters are given as scope, when preferred range or upper preferred value and lower preferred value are listed, this should be understood as specifically disclosing all ranges formed by any upper range limit or preferred value and any lower range limit or preferred value, and no matter whether the scope is disclosed separately. When numerical range is quoted herein, unless otherwise stated, the scope is intended to include all integers and fractions in its endpoints and the scope. The scope of the present invention is not limited to the specific value quoted when defining the scope.

[0347] Other embodiments of the invention will be apparent to those skilled in the art through consideration of the specification and practice of the invention disclosed herein.It is intended that the specification and examples be considered as exemplary only, with the true scope and spirit of the invention being indicated by the following claims and their equivalents.

Claims

1. A system for printing one or more three-dimensional objects, the system comprising a box for printing one or more three-dimensional objects, the box being configured to hold a certain volume of a photopolymerizable composition, the box comprising side walls connected to a bottom wall to define a volumetric space for holding the volume, the box being configured to include one or more printing zones, wherein the size of the printing zones is designed to facilitate illumination by one or more, preferably at least two, excitation light projections to at least partially form a three-dimensional printed object within the volume of photopolymerizable composition in the printing zones; and one or more optical systems, wherein the optical systems are positioned or positionable to selectively direct one or more, preferably at least two, excitation light projections into a single printing zone.

2. A system for printing one or more three-dimensional objects, the system comprising a box configured to hold a certain volume of photopolymerizable composition, the box comprising opposite end walls and at least one port in at least one end wall of the box to facilitate the introduction of unpolymerized photopolymerizable composition and / or the removal of unpolymerized photopolymerizable composition and / or the removal of one or more three-dimensional objects from the box, the box being configured to include one or more printing zones, wherein the size of the printing zones is designed to facilitate illumination by one or more, preferably at least two, excitation light projections to at least partially form a three-dimensional printed object within the volume of photopolymerizable composition in the printing zones; and one or more optical systems, wherein the optical systems are positioned or positionable to selectively direct one or more, preferably at least two, excitation light projections into a single printing zone.

3. The system according to claim 1 or 2, in, The box and at least one of the one or more optical systems are movable relative to each other.

4. The system of claim 1 or 2, further comprising a separator unit for removing the unpolymerized photopolymerizable composition and one or more printed three-dimensional objects from the box.

5. The system according to claim 1 or 2, in, The separator unit is capable of separating unpolymerized photopolymerizable composition from the printed three-dimensional object contained in the removed contents.

6. The system of claim 4, in, The separator unit includes a discharge port for discharging any separated printed objects from the separator unit.

7. The system of claim 4, in, The separator unit includes a discharge port for discharging any separated printed objects from the separator unit.

8. The system of claim 7, in, The separator unit further includes a second exhaust port for exhausting the separated unpolymerized photopolymerizable composition from the separator unit.

9. The system of claim 4, further comprising a recovery unit connected to the separator unit for receiving the separated unpolymerized photopolymerizable composition for recovery.

10. The system according to claim 8, in, The system further includes a recirculation loop connected to the second exhaust port for recirculating the separated unpolymerized photopolymerizable composition to a storage of the photopolymerizable composition.

11. The system of claim 9, in, The system further comprises a recycling loop connected to the recovery unit for recycling the separated unpolymerized photopolymerizable composition into a storage of the photopolymerizable composition.

12. The system of claim 9, in, The recovery unit is configured to recondition the separated unpolymerized photopolymerizable composition before recycling it into a storage of photopolymerizable composition.

13. The system according to claim 1 or 2, in, A single optical system is configured to project one or more, preferably at least two, excitation light projections into a printing zone.

14. The system according to claim 1 or 2, in, The system comprises at least two excitation light projections comprising the same wavelength.

15. The system of claim 13, in, The system comprises at least two excitation light projections comprising the same wavelength.

16. The system according to claim 1 or 2, in, The system includes at least two excitation light projections comprising different wavelengths.

17. The system of claim 13, in, The system includes at least two excitation light projections comprising different wavelengths.

18. The system according to claim 1 or 2, in, The cartridge is removable or replaceable.

19. The system of claim 1, in, The box comprises one or more ports in at least one wall, wherein at least one port is preferably openable and closable.

20. The system of claim 1 or 2, in, The optical system is connected to one or more excitation light sources.

21. The system of claim 1 or 2, in, The excitation light projection is produced by a separate optical system connected to the excitation light source.

22. The system of claim 1 or 2, in, The excitation light projection is produced by a separate optical system connected to an excitation light source emitting a different wavelength.

23. The system of claim 1 or 2, in, At least one of the optical systems comprises a digital micromirror display projection system.

24. The system of claim 1 or 2, in, At least one of the optical systems comprises a light sheet generating system.

25. The system of claim 23, further comprising an optical system including a light sheet generating system.

26. The system of claim 25, in, The wavelength of light projected by the digital micromirror display projection system is different from the wavelength of light projected by the light sheet generation system.

27. The system of claim 1 or 2, further comprising a post-processing unit or area.

28. The system of claim 1 or 2, further comprising one or more inspection units or areas for inspecting the printed object after formation.

29. The system of claim 1 or 2, in, The cartridge, optical system, and other optional components of the system are modular and may be independently removed and / or replaced.

30. The system of claim 1 or 2, in, One or more of the optical systems may be replaceable.

31. The system of claim 1 or 2, in, One or more components of the system are included in a single housing.

32. The system of claim 1, in, The box also includes (i) a top wall and at least one openable / closable port, or (ii) a removable cover.

33. The system of claim 1 or 2, in, The box wall includes one or more optically transparent areas associated with the printing area to facilitate the projection of excitation light through the one or more optically transparent areas and guide it into the printing area.

34. A method for printing one or more three-dimensional objects, the method include: providing a volume of photopolymerizable composition in a box configured to hold a volume of photopolymerizable composition, the box comprising side walls, preferably four side walls, connected to a bottom wall to define a volume space for holding the volume, the box being configured to include one or more printing zones, wherein the printing zones are sized to be illuminated by one or more, preferably at least two, excitation light projections to at least partially form a three-dimensional printed object within the volume of photopolymerizable composition in the printing zones, and The at least two excitation light projections are directed into each printing zone to selectively photopolymerize the photopolymerizable composition at one or more selected locations in the printing zone to at least partially form a three-dimensional object in the printing zone.

35. A method for printing one or more three-dimensional objects, the method include: providing a volume of photopolymerizable composition in a box configured to hold the volume of photopolymerizable composition, the box comprising opposing end walls and comprising at least one port in at least one of the end walls of the box to facilitate introduction of unpolymerized photopolymerizable composition and / or removal of unpolymerized photopolymerizable composition and / or removal of one or more three-dimensional objects from the box, the box being configured to include one or more printing zones, wherein the printing zones are sized to facilitate illumination by one or more, preferably at least two, excitation light projections to at least partially form a three-dimensional printed object within the volume of photopolymerizable composition in the printing zones, and The one or more, preferably at least two, excitation light projections are directed into each printing zone to selectively photopolymerize the photopolymerizable composition at one or more selected locations in the printing zone, thereby at least partially forming a three-dimensional printed object within the volume of photopolymerizable composition in the printing zone.

36. The method of claim 34, in, The box includes one or more ports in at least one wall, wherein at least one port is openable and closeable.

37. The method of claim 35, in, The port is openable and closable.

38. The method of claim 35, in, The box includes a port at each end, and wherein each port is openable and closeable.

39. The method of claim 34 or 35, in, The photopolymerizable composition exhibits non-Newtonian rheological behavior, and the one or more, preferably at least two, excitation light projections are selectively directed into the printing zone to selectively photopolymerize the photopolymerizable composition at one or more selected locations in the printing zone, thereby forming a printed object without a supporting structure.

40. The method of claim 39, in, The printed object is maintained in a fixed position or minimally displaced within the unpolymerized photopolymerizable composition during formation.

41. The method of claim 40, in, The minimal degree of displacement includes the amount of displacement of the printed object that is acceptable for accurately reproducing the geometry of the object to be printed during the time interval required to form the object.

42. The method of claim 34 or 35, in, The one or more, preferably at least two, excitation light projections are selectively directed into the printing zone to selectively induce polymerization and cross-linking reactions in the photopolymerizable composition at one or more selected locations in the printing zone, thereby forming a printed object without a supporting structure.

43. The method of claim 34 or 35, in, The box has a uniform cross-section along its length dimension.

44. The method of claim 34 or 35, in, The box has a rectangular or square cross-section.

45. The method of claim 34 or 35, in, The box has a non-uniform cross-section in its length dimension.

46. ​​The method of claim 34 or 35, in, The box is optically transparent.

47. The method of claim 34 or 35, in, The cell is optically flat.

48. The method of claim 34 or 35, in, The box includes one or more optically transparent areas that are positioned to direct the excitation light projection and the passage of the excitation light projection into a printing area in the box.

49. The method of claim 34, in, The box also includes (i) a top wall and at least one openable / closable port, or (ii) a removable cover.

50. The method of claim 34 or 35, in, The method is carried out in an inert atmosphere.

51. The method of claim 34 or 35, in, The method is carried out in a non-inert atmosphere.

52. The method of claim 34 or 35, further comprising separating the at least partially formed three-dimensional object from unpolymerized photopolymerizable composition included in the box.

53. The method of claim 34 or 35, further comprising recovering the unpolymerized photopolymerizable composition after separating the at least partially formed three-dimensional object from the unpolymerized photopolymerizable composition.

54. The method of claim 34 or 35, in, The photopolymerizable composition exhibits non-Newtonian rheological behavior, so that the object formed in the photopolymerizable composition in the printing area remains in a fixed position or undergoes minimal displacement in the unpolymerized photopolymerizable composition during formation, and the excitation light is guided into the printing area through the optically transparent area of ​​the box to selectively photopolymerize the photopolymerizable composition in the printing area without a supporting structure, thereby forming a printed object, wherein the printed object remains in a fixed position or undergoes minimal displacement in the unpolymerized photopolymerizable composition during formation.

55. The method of claim 34 or 35, in, The photopolymerizable composition comprises a photohardenable component and a photoswitchable photoinitiator, wherein the photoswitchable photoinitiator can be activated by exposure to light having a first wavelength and light having a second wavelength to induce a crosslinking or polymerization reaction in the photohardenable composition, wherein the first wavelength is different from the second wavelength.

56. The method of claim 55, in, The photopolymerizable composition exhibits non-Newtonian rheological behavior.

57. The method of claim 55, in, The photopolymerizable composition also includes a co-initiator.

58. The method of claim 55, in, The photopolymerizable composition also includes a sensitizer.

59. The method of claim 55, in, The photopolymerizable composition also includes a synergist.

60. The method of claim 55, further optionally comprising at least one of a coinitiator, a synergist, and a sensitizer.

61. The method of claim 34 or 35, further comprising post-processing the at least partially formed three-dimensional object after separation from the unpolymerized photopolymerizable composition.

62. The method of claim 34 or 35, further comprising post-curing the at least partially formed three-dimensional object after separation from the unpolymerized photopolymerizable composition.

63. The method of any one of claims 34 or 35, further comprising inspecting the at least partially formed three-dimensional object.

64. The method of claim 34 or 35, in, At least one of the optical systems comprises a digital micromirror display projection system.

65. The method of claim 34 or 35, in, At least one of the optical systems comprises a light sheet generating system.

66. The method of claim 64, further comprising an optical system comprising a light sheet generating system.

67. New, usable, and non-obvious processes, machines, manufacture, and compositions of matter as herein shown and described.

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