WO2025008826A1

WO2025008826A1 - Method and system for correcting color artifacts in additive manufacturing

Info

Publication number: WO2025008826A1
Application number: PCT/IL2024/050657
Authority: WO
Inventors: Alexander Libinson; Gilad NAHARI; Lior KHAIMOV
Original assignee: Stratasys Ltd.
Priority date: 2023-07-05
Filing date: 2024-07-05
Publication date: 2025-01-09

Abstract

A method of encoding data for additive manufacturing, comprises receiving a first computer object shell dataset and a second computer object shell dataset, respectively describing geometries and optical property assignments of a first object part and a second object part, and obtaining a combined dataset describing an object assembly representing a partial embedding of the first object part in the second object part. The method also comprises updating optical property assignment for the combined dataset by replacing optical property assignment for each dataset element corresponding to a portion of a respective object part which is external in the object part but internal in the object assembly.

Description

METHOD AND SYSTEM FOR CORRECTING COLOR ARTIFACTS IN ADDITIVE

MANUFACTURING

RELATED APPLICATIONS

This application claims the benefit of priority of U.S. Provisional Patent Application No. 63/525,066 filed on 5 July 2023, the contents of which are incorporated herein by reference in their entirety.

This application is also related to U.S. Provisional Patent Application No. 63/525,074 filed on July 5, 2023, the contents of which are incorporated herein by reference in their entirety.

This application is further related co-filed PCT Application entitled “ADDITIVE MANUFACTURING OF DENTAL PROSTHESES” (Attorney Docket No. 100033), the contents of which are incorporated herein by reference in their entirety.

FIELD AND BACKGROUND OF THE INVENTION

The present invention, in some embodiments thereof, relates to additive manufacturing and, more particularly, but not exclusively, to a method and system for correcting color artifacts in additive manufacturing.

Additive manufacturing (AM) is generally a process in which a three-dimensional (3D) object is manufactured utilizing a computer model of the objects. Such a process is used in various fields, such as design related fields for purposes of visualization, demonstration and mechanical prototyping, as well as for rapid manufacturing (RM). The basic operation of any AM system consists of slicing a three-dimensional computer model into thin cross sections, translating the result into two-dimensional position data and feeding the data to control equipment which manufacture a three-dimensional structure in a layerwise manner.

One type of AM is three-dimensional inkjet printing processes. In this process, a building material is dispensed from a dispensing head having a set of nozzles to deposit layers on a supporting structure. Depending on the building material, the layers may then be cured or solidified using a suitable device.

Various three-dimensional inkjet printing techniques exist and are disclosed in, e.g., U.S. Patent Nos. 6,259,962, 6,569,373, 6,658,314, 6,850,334, 7,183,335, 7,209,797, 7,225,045, 7,300,619, 7,479,510, 7,500,846, 7,962,237, and International Publication No. WO2020/194318, the contents of which are hereby incorporated by reference. SUMMARY OF THE INVENTION

According to an aspect of some embodiments of the present invention there is provided a method of encoding data for additive manufacturing. The method comprises: receiving a first computer object shell dataset and a second computer object shell dataset, respectively describing geometries and optical property assignments of a first object part and a second object part, and obtaining a combined dataset describing an object assembly representing a partial embedding of the first object part in the second object part. The method also comprises updating optical property assignment for the combined dataset by replacing optical property assignment for each dataset element corresponding to a portion of a respective object part which is external in the object part but internal in the object assembly.

According to some embodiments of the invention at least one of the computer object shell datasets describes an object part having an inner region encapsulated by an outer region, wherein the method comprises replacing optical property assignment for each dataset element corresponding to a portion of the outer region which is internal in the object assembly.

According to some embodiments of the invention at least one of the computer object shell datasets describes an object part having a core region enclosed by a plurality of encapsulating regions defining an onion-like structure for the object part, wherein the method comprises replacing optical property assignment for each dataset element corresponding to a portion of at least one encapsulating region which is internal in the object assembly.

According to some embodiments of the invention the optical property assignment is replaced such as to increase an opacity level of the portion of the respective object part.

According to some embodiments of the invention the method comprises slicing the combined dataset into a plurality of slices, each defined over a plurality of voxels, and assigning for each voxel of each slice, a building material formulation corresponding to an optical property assignment of a respective dataset element of the combined dataset following the update.

According to some embodiments of the invention the method comprises transmitting the plurality of slices to a controller of an additive manufacturing system for additive manufacturing of a plurality of layers respectively corresponding to the plurality of slices.

According to some embodiments of the invention the optical property assignments are replaced by substituting a colorless or colored optical property with a substitute optical property, wherein an amount of white portion in the substitute optical property is higher than an amount of white portion in the colorless or colored optical property.

According to some embodiments of the invention the method comprises receiving a first geometry dataset describing a first geometry of the first object part, a second geometry dataset describing a second geometry of the second object part, presenting the first and the second geometry datasets on a graphical user interface (GUI), and selecting, using the GUI, at least one optical property for each geometry dataset, thereby generating the first and the second computer object shell datasets.

According to some embodiments of the invention the method comprises prior to the update, using the computer object shell datasets for defining external and internal regions for each object part, and identifying portions of the external regions that are internal in the object assembly.

According to some embodiments of the invention the method comprises identifying dataset elements in the combined dataset that correspond to air gaps between the object parts, wherein the update of the optical property assignment comprises assigning a predetermined optical property for each identified dataset element.

According to an aspect of some embodiments of the present invention there is provided a method of encoding data for additive manufacturing. The method comprises receiving slice data describing a plurality of slices, each slice being defined over a plurality of voxels, and each voxel being assigned with a building material formulation, and applying image processing to each slice, to identify in the slice regions corresponding to a layer of a first object part and a layer of a second object, wherein the layer of the first object part is at least partially embedded in the layer of the second object part. The method further comprises updating building material assignments for at least one of the slices by replacing material assignment for each voxel corresponding to a portion of a respective object part which is external in the object part but internal within the slice.

According to some embodiments of the invention the method comprises constructing, based on the identification, a first computer object shell dataset describing a three-dimensional geometry and building material assignments of the first object part, a second computer object shell dataset describing a three-dimensional geometry and building material assignments of the second object part, and a combined computer object shell dataset describing a three-dimensional geometry and building material assignments of an object assembly representing a partial embedding of the first object part in the second object part. In these embodiments, the updating of the building material assignments is executed by replacing material assignment for voxels corresponding to a portion of a respective object part which are external in the object part but internal in the object assembly.

According to some embodiments of the invention at least one of the first and the second object parts has an inner region encapsulated by an outer region, and the method comprises replacing material assignment for each voxel corresponding to a portion of the outer region which is internal in the slice. According to some embodiments of the invention at least one of the object parts has a core region enclosed by a plurality of encapsulating regions defining an onion-like structure for the object part, and the method comprises replacing material assignment for each voxel corresponding to a portion of at least one encapsulating region which is internal in the slice.

According to some embodiments of the invention the material assignment is replaced such as to increase an opacity level of the portion of the respective object part.

According to some embodiments of the invention the method comprises, following the update of the building material assignments, transmitting the plurality of slices to a controller of an additive manufacturing system for additive manufacturing of a plurality of layers respectively corresponding to the plurality of slices.

According to some embodiments of the invention the first object part has a shape of a tooth or a plurality of teeth, and the second object part has a shape of a gingiva.

According to some embodiments of the invention the material assignments are replaced by substituting a colorless or colored building material formulation with a substitute building material formulation, wherein an amount of white coloring agent in the substitute building material formulation is higher than an amount of white coloring agent in the colorless or colored building material formulation.

According to some embodiments of the invention the colorless or colored building material formulation is colorless.

According to some embodiments of the invention the colorless or colored building material formulation is a colored building material formulation comprising a coloring agent other than a white coloring agent.

According to an aspect of some embodiments of the present invention there is provided a computer software product, comprising a computer-readable medium in which program instructions are stored, which instructions, when read by a data processor, cause the data processor to execute the method as delineated above and optionally and preferably as further detailed below.

Unless otherwise defined, all technical and/or scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the invention pertains. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of embodiments of the invention, exemplary methods and/or materials are described below. In case of conflict, the patent specification, including definitions, will control. In addition, the materials, methods, and examples are illustrative only and are not intended to be necessarily limiting. Implementation of the method and/or system of embodiments of the invention can involve performing or completing selected tasks manually, automatically, or a combination thereof. Moreover, according to actual instrumentation and equipment of embodiments of the method and/or system of the invention, several selected tasks could be implemented by hardware, by software or by firmware or by a combination thereof using an operating system.

For example, hardware for performing selected tasks according to embodiments of the invention could be implemented as a chip or a circuit. As software, selected tasks according to embodiments of the invention could be implemented as a plurality of software instructions being executed by a computer using any suitable operating system. In an exemplary embodiment of the invention, one or more tasks according to exemplary embodiments of method and/or system as described herein are performed by a data processor, such as a computing platform for executing a plurality of instructions. Optionally, the data processor includes a volatile memory for storing instructions and/or data and/or a non-volatile storage, for example, a magnetic hard-disk and/or removable media, for storing instructions and/or data. Optionally, a network connection is provided as well. A display and/or a user input device such as a keyboard or mouse are optionally provided as well.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

Some embodiments of the invention are herein described, by way of example only, with reference to the accompanying drawings. With specific reference now to the drawings in detail, it is stressed that the particulars shown are by way of example and for purposes of illustrative discussion of embodiments of the invention. In this regard, the description taken with the drawings makes apparent to those skilled in the art how embodiments of the invention may be practiced.

In the drawings:

FIGs. 1A-D are schematic illustrations of additive manufacturing systems according to some embodiments of the invention;

FIGs. 2A-2C are schematic illustrations of printing heads according to some embodiments of the present invention;

FIGs. 3A and 3B are schematic illustrations demonstrating coordinate transformations according to some embodiments of the present invention;

FIGs. 4A-C are schematic illustrations of an object which is defined as an assembly of two shells, according to some embodiments of the present invention;

FIG. 5 is an image of an object assembly demonstrating color artifacts; FIG. 6 is a flowchart diagram of a method suitable for encoding data for additive manufacturing, according to various exemplary embodiments of the present invention;

FIGs. 7A-C are schematic illustrations showing planar views representing a cross-section of an object assembly in which one object part having a core region and an encapsulating region is partially embedded in another object part which also has a core region and an encapsulating region, according to some embodiments of the present invention;

FIG. 8 is a schematic illustration showing a cross-section view of an object part having a core region enclosed by a plurality of encapsulating regions defining an onion-like structure, according to some embodiments of the present invention;

FIG. 9 is a flowchart diagram of another method suitable for encoding data for additive manufacturing, according to various exemplary embodiments of the present invention;

FIGs. 10A-C are schematic illustrations of slice images representing layers of an object assembly in which one object part having a core region and an encapsulating region is partially embedded in another object part which also has a core region and an encapsulating region, according to some embodiments of the present invention;

FIGs. 11A-C are slice images of three slice datasets extracted from the same input slice data, as obtained by applying image processing to the input slice data, according to some embodiments of the present invention;

FIGs. 12A-E are slice images describing the application of image processing to a slice image for the purpose of identifying object parts in the slice image, according to some embodiments of the present invention; and

FIG. 13 is a diagram describing an exemplified workflow suitable for preparing object shell datasets and for using these datasets to fabricate an object assembly, according to some embodiments of the present invention.

DESCRIPTION OF SPECIFIC EMBODIMENTS OF THE INVENTION

Before explaining at least one embodiment of the invention in detail, it is to be understood that the invention is not necessarily limited in its application to the details of construction and the arrangement of the components and/or methods set forth in the following description and/or illustrated in the drawings and/or the Examples. The invention is capable of other embodiments or of being practiced or carried out in various ways. The method and system of the present embodiments manufacture three-dimensional objects based on computer object data in a layerwise manner by forming a plurality of layers in a configured pattern corresponding to the shape of the objects. The formation of the layers is optionally and preferably by printing, more preferably by inkjet printing. The computer object data can be in any known format, including, without limitation, a Standard Tessellation Language (STL) or a StereoLithography Contour (SLC) format, an OBJ File format (OBJ), a 3D Manufacturing Format (3MF), Virtual Reality Modeling Language (VRML), Additive Manufacturing File (AMF) format, Drawing Exchange Format (DXF), Polygon File Format (PLY), or any other format suitable for Computer-Aided Design (CAD).

Typically, the outer shape of the object to be manufactured is selected by means of appropriate software, e.g., CAD software or the like. The software typically generates computer object data in the form of graphic elements (e.g., a mesh of polygons, non-uniform rational basis splines, etc.) defining a surface of the object. The graphic elements are processed by a computer which employs software known as "a slicer" that transforms the graphic elements to a grid of voxels that define the internal shape of the object, and that are arranged as a plurality of slices, each comprising a plurality of voxels describing a layer of the 3D object.

Each layer of the object can be formed by an AM apparatus which scans a two-dimensional surface and patterns it. While scanning, the apparatus visits a plurality of target locations on the two-dimensional layer or surface, and decides, for each target location or a group of target locations, whether or not the target location or group of target locations is to be occupied by building material formulation, and which type of building material formulation is to be delivered thereto. The decision is made according to a computer image of the surface.

In preferred embodiments of the present invention the AM comprises three-dimensional printing, more preferably three-dimensional inkjet printing. In these embodiments a building material is dispensed from a printing head having one or more arrays of nozzles to deposit building material in layers on a supporting structure. The AM apparatus thus dispenses building material in target locations which are to be occupied and leaves other target locations void. The apparatus typically includes a plurality of arrays of nozzles, each of which can be configured to dispense a different building material. This is typically achieved by providing the printing head with a plurality of fluid channels separated from each other, wherein each channel receives a different building material through a separate inlet and conveys it to a different array of nozzles.

Thus, different target locations can be occupied by different building material formulations. The types of building material formulations can be categorized into two major categories: modeling material formulation and support material formulation. The support material formulation serves as a supporting matrix or construction for supporting the object or object parts during the fabrication process and/or other purposes, e.g., providing hollow or porous objects. Support constructions may additionally include modeling material formulation elements, e.g. for further support strength.

The modeling material formulation is generally a composition which is formulated for use in additive manufacturing and which is able to form a three-dimensional object on its own, without having to be mixed or combined with any other substance.

The final three-dimensional object is made of the modeling material formulation or a combination of modeling material formulations or modeling and support material formulations or modification thereof (e.g., following curing). All these operations are well-known to those skilled in the art of solid freeform fabrication.

In some exemplary embodiments of the invention an object is manufactured by dispensing two or more different modeling material formulations, each material formulation from a different array of nozzles (belonging to the same or different printing heads) of the AM apparatus. In some embodiments, two or more such arrays of nozzles that dispense different modeling material formulations are both located in the same printing head of the AM apparatus. In some embodiments, arrays of nozzles that dispense different modeling material formulations are located in separate printing heads, for example, a first array of nozzles dispensing a first modeling material formulation is located in a first printing head, and a second array of nozzles dispensing a second modeling material formulation is located in a second printing head.

In some embodiments, an array of nozzles that dispense a modeling material formulation and an array of nozzles that dispense a support material formulation are both located in the same printing head. In some embodiments, an array of nozzles that dispense a modeling material formulation and an array of nozzles that dispense a support material formulation are located in separate printing heads.

A representative and non-limiting example of a system 110 suitable for AM of an object 112 according to some embodiments of the present invention is illustrated in FIG. 1A. System 110 comprises an additive manufacturing apparatus 114 having a dispensing unit 16 which comprises a plurality of printing heads. Each head preferably comprises one or more arrays of nozzles 122, typically mounted on an orifice plate 121, as illustrated in FIGs. 2A-C described below, through which a liquid building material formulation 124 is dispensed.

Preferably, but not obligatorily, apparatus 114 is a three-dimensional printing apparatus, in which case the printing heads are printing heads, and the building material formulation is dispensed via inkjet technology. This need not necessarily be the case, since, for some applications, it may not be necessary for the additive manufacturing apparatus to employ three-dimensional printing techniques. Representative examples of additive manufacturing apparatus contemplated according to various exemplary embodiments of the present invention include, without limitation, fused deposition modeling apparatus and fused material formulation deposition apparatus.

Each printing head is optionally and preferably fed via one or more building material formulation reservoirs which may optionally include a temperature control unit (e.g. , a temperature sensor and/or a heating device), and a material formulation level sensor. To dispense the building material formulation, a voltage signal is applied to the printing heads to selectively deposit droplets of material formulation via the printing head nozzles, for example, as in piezoelectric inkjet printing technology. Another example includes thermal inkjet printing heads. In these types of heads, there are heater elements in thermal contact with the building material formulation, for heating the building material formulation to form gas bubbles therein, upon activation of the heater elements by a voltage signal. The gas bubbles generate pressures in the building material formulation, causing droplets of building material formulation to be ejected through the nozzles. Piezoelectric and thermal printing heads are known to those skilled in the art of solid freeform fabrication. For any types of inkjet printing heads, the dispensing rate of the head depends on the number of nozzles, the type of nozzles and the applied voltage signal rate (frequency).

Optionally, the overall number of dispensing nozzles or nozzle arrays is selected such that half of the dispensing nozzles are designated to dispense support material formulation and half of the dispensing nozzles are designated to dispense modeling material formulation, i.e. the number of nozzles jetting modeling material formulations is the same as the number of nozzles jetting support material formulation. In the representative example of FIG. 1A, four printing heads 16a, 16b, 16c and 16d are illustrated. Each of heads 16a, 16b, 16c and 16d has a nozzle array. In this Example, heads 16a and 16b can be designated for modeling material formulation/s and heads 16c and 16d can be designated for support material formulation. Thus, head 16a can dispense one modeling material formulation, head 16b can dispense another modeling material formulation and heads 16c and 16d can both dispense support material formulation. In an alternative embodiment, heads 16c and 16d, for example, may be combined in a single head having two nozzle arrays for depositing support material formulation. In a further alternative embodiment any one or more of the printing heads may have more than one nozzle arrays for depositing more than one material formulation, e.g. two nozzle arrays for depositing two different modeling material formulations or a modeling material formulation and a support material formulation, each formulation via a different array or number of nozzles.

Yet it is to be understood that it is not intended to limit the scope of the present invention and that the number of modeling material formulation printing heads (modeling heads) and the number of support material formulation printing heads (support heads) may differ. In some embodiments, the number of arrays of nozzles that dispense modeling material formulation, the number of arrays of nozzles that dispense support material formulation, and the number of nozzles in each respective array are selected such as to provide a predetermined ratio, a, between the maximal dispensing rate of the support material formulation and the maximal dispensing rate of modeling material formulation. The value of the predetermined ratio, a, is preferably selected to ensure that in each formed layer, the height of modeling material formulation equals the height of support material formulation. Typical values for a are from about 0.6 to about 1.5.

As used herein throughout the term “about” refers to ± 10 %.

For example, for a = 1, the overall dispensing rate of support material formulation is generally the same as the overall dispensing rate of the modeling material formulation when all the arrays of nozzles operate.

Apparatus 114 can comprise, for example, M modeling heads each having m arrays of p nozzles, and S support heads each having s arrays of q nozzles such that Mxmxp = Sxsxq. Each of the Mxm modeling arrays and Sxs support arrays can be manufactured as a separate physical unit, which can be assembled and disassembled from the group of arrays. In this embodiment, each such array optionally and preferably comprises a temperature control unit and a material formulation level sensor of its own, and receives an individually controlled voltage for its operation.

Apparatus 114 can further comprise a solidifying device 324 which can include any device configured to emit light, heat or the like that may cause the deposited material formulation to harden. For example, solidifying device 324 can comprise one or more radiation sources, which can be, for example, an ultraviolet or visible or infrared lamp, or other sources of electromagnetic radiation, or electron beam source, depending on the modeling material formulation being used. In some embodiments of the present invention, solidifying device 324 serves for curing or solidifying the modeling material formulation.

In addition to solidifying device 324, apparatus 114 optionally and preferably comprises an additional radiation source 328 for solvent evaporation. Radiation source 328 optionally and preferably generates infrared radiation. In various exemplary embodiments of the invention solidifying device 324 comprises a radiation source generating ultraviolet radiation, and radiation source 328 generates infrared radiation.

In some embodiments of the present invention apparatus 114 comprises cooling system

134 such as one or more fans or the like The printing head(s) and radiation source are preferably mounted in a frame or block 128 which is preferably operative to reciprocally move over a tray 360, which serves as the working surface. In some embodiments of the present invention the radiation sources are mounted in the block such that they follow in the wake of the printing heads to at least partially cure or solidify the material formulations just dispensed by the printing heads. Tray 360 is positioned horizontally. According to the common conventions an X-Y-Z Cartesian coordinate system is selected such that the X-Y plane is parallel to tray 360. Tray 360 is preferably configured to move vertically (along the Z direction), typically downward. In various exemplary embodiments of the invention, apparatus 114 further comprises one or more leveling devices 32, e.g. a roller 326. Leveling device 326 serves to straighten, level and/or establish a thickness of the newly formed layer prior to the formation of the successive layer thereon. Leveling device 32 preferably comprises a waste collection device 136 for collecting the excess material formulation generated during leveling. Waste collection device 136 may comprise any mechanism that delivers the material formulation to a waste tank or waste cartridge.

In use, the printing heads of unit 16 move in a scanning direction, which is referred to herein as the X direction, and selectively dispense building material formulation in a predetermined configuration in the course of their passage over tray 360. The building material formulation typically comprises one or more types of support material formulation and one or more types of modeling material formulation. The passage of the printing heads of unit 16 is followed by the curing of the modeling material formulation(s) by radiation source 126. In the reverse passage of the heads, back to their starting point for the layer just deposited, an additional dispensing of building material formulation may be carried out, according to predetermined configuration. In the forward and/or reverse passages of the printing heads, the layer thus formed may be straightened by leveling device 32, which preferably follows the path of the printing heads in their forward and/or reverse movement. Once the printing heads return to their starting point along the X direction, they may move to another position along an indexing direction, referred to herein as the Y direction, and continue to build the same layer by reciprocal movement along the X direction. Alternately, the printing heads may move in the Y direction between forward and reverse movements or after more than one forward-reverse movement. The series of scans performed by the printing heads to complete a single layer is referred to herein as a single scan cycle.

Once the layer is completed, tray 360 is lowered in the Z direction to a predetermined Z level, according to the desired thickness of the layer subsequently to be printed. The procedure is repeated to form three-dimensional object 112 in a layerwise manner. In another embodiment, tray 360 may be displaced in the Z direction between forward and reverse passages of the printing head of unit 16, within the layer. Such Z displacement is carried out in order to cause contact of the leveling device with the surface in one direction and prevent contact in the other direction.

The present embodiments contemplate use of a liquid material formulation supply system 330, which comprises one or more liquid material containers or cartridges 430, and which supplies the liquid material(s) to printing heads. Supply system 330 can be used in an AM system such as system 110, in which case the liquid material in each container is a building material.

A controller 20 controls fabrication apparatus 114 and optionally and preferably also supply system 330. Controller 20 typically includes an electronic circuit configured to perform the controlling operations. Controller 20 preferably communicates with a computer 24 which transmits digital data pertaining to fabrication instructions based on computer object data, e.g., a CAD configuration represented on a computer readable medium in a form of a Standard Tessellation Language (STL) format or the like. Typically, controller 20 controls the voltage applied to each printing head or each nozzle array and the temperature of the building material formulation in the respective printing head or respective nozzle array.

Once the manufacturing data is loaded to controller 20 it can operate without user intervention. In some embodiments, controller 20 receives additional input from the operator, e.g., using computer 24 or using a user interface 116 communicating with controller 20. User interface 116 can be of any type known in the art, such as, but not limited to, a keyboard, a touch screen and the like. For example, controller 20 can receive, as additional input, one or more building material formulation types and/or attributes, such as, but not limited to, color, characteristic distortion and/or transition temperature, viscosity, electrical property, magnetic property. Other attributes and groups of attributes are also contemplated.

Another representative and non-limiting example of a system 10 suitable for AM of an object according to some embodiments of the present invention is illustrated in FIGs. 1B-D. FIGs. 1B-D illustrate a top view (FIG. IB), a side view (FIG. 1C) and an isometric view (FIG. ID) of system 10.

In the present embodiments, system 10 comprises a tray 12 and a plurality of inkjet printing heads 16, each having one or more arrays of nozzles with respective one or more pluralities of separated nozzles. The material used for the three-dimensional printing is supplied to heads 16 by building material supply system 330, with one or more liquid material containers or cartridges 430, as further detailed hereinabove. Tray 12 can have a shape of a disk or it can be annular. Non-round shapes are also contemplated, provided they can be rotated about a vertical axis. Tray 12 and heads 16 are optionally and preferably mounted such as to allow a relative rotary motion between tray 12 and heads 16. This can be achieved by (i) configuring tray 12 to rotate about a vertical axis 14 relative to heads 16, (ii) configuring heads 16 to rotate about vertical axis 14 relative to tray 12, or (iii) configuring both tray 12 and heads 16 to rotate about vertical axis 14 but at different rotation velocities (e.g., rotation at opposite direction). While some embodiments of system 10 are described below with a particular emphasis to configuration (i) wherein the tray is a rotary tray that is configured to rotate about vertical axis 14 relative to heads 16, it is to be understood that the present application contemplates also configurations (ii) and (iii) for system 10. Any one of the embodiments of system 10 described herein can be adjusted to be applicable to any of configurations (ii) and (iii), and one of ordinary skills in the art, provided with the details described herein, would know how to make such adjustment.

In the following description, a direction parallel to tray 12 and pointing outwardly from axis 14 is referred to as the radial direction r, a direction parallel to tray 12 and perpendicular to the radial direction r is referred to herein as the azimuthal direction <p, and a direction perpendicular to tray 12 is referred to herein is the vertical direction z-

The radial direction r in system 10 enacts the indexing direction y in system 110, and the azimuthal direction cp enacts the scanning direction x in system 110. Therefore, the radial direction is interchangeably referred to herein as the indexing direction, and the azimuthal direction is interchangeably referred to herein as the scanning direction.

The term “radial position,” as used herein, refers to a position on or above tray 12 at a specific distance from axis 14. When the term is used in connection to a printing head, the term refers to a position of the head which is at specific distance from axis 14. When the term is used in connection to a point on tray 12, the term corresponds to any point that belongs to a locus of points that is a circle whose radius is the specific distance from axis 14 and whose center is at axis 14.

The term “azimuthal position,” as used herein, refers to a position on or above tray 12 at a specific azimuthal angle relative to a predetermined reference point. Thus, radial position refers to any point that belongs to a locus of points that is a straight line forming the specific azimuthal angle relative to the reference point.

The term “vertical position,” as used herein, refers to a position over a plane that intersect the vertical axis 14 at a specific point.

Tray 12 serves as a building platform for three-dimensional printing. The working area on which one or objects are printed is typically, but not necessarily, smaller than the total area of tray 12. In some embodiments of the present invention the working area is annular. The working area is shown at 26. In some embodiments of the present invention tray 12 rotates continuously in the same direction throughout the formation of object, and in some embodiments of the present invention tray reverses the direction of rotation at least once (e.g., in an oscillatory manner) during the formation of the object. Tray 12 is optionally and preferably removable. Removing tray 12 can be for maintenance of system 10, or, if desired, for replacing the tray before printing a new object. In some embodiments of the present invention system 10 is provided with one or more different replacement trays (e.g., a kit of replacement trays), wherein two or more trays are designated for different types of objects (e.g., different weights) different operation modes (e.g., different rotation speeds), etc. The replacement of tray 12 can be manual or automatic, as desired. When automatic replacement is employed, system 10 comprises a tray replacement device 36 configured for removing tray 12 from its position below heads 16 and replacing it by a replacement tray (not shown). In the representative illustration of FIG. IB tray replacement device 36 is illustrated as a drive 38 with a movable arm 40 configured to pull tray 12, but other types of tray replacement devices are also contemplated.

Exemplified embodiments for the printing head 16 are illustrated in FIGs. 2A-2C. These embodiments can be employed for any of the AM systems described above, including, without limitation, system 110 and system 10.

FIGs. 2A-B illustrate a printing head 16 with one (FIG. 2A) and two (FIG. 2B) nozzle arrays 22. The nozzles in the array are preferably aligned linearly, along a straight line. Printing head 16 is fed by a liquid material and dispenses it through the nozzle arrays 22, in response to a voltage signal applied thereto by the controller of the printing system. Head 16 is fed by a liquid material which is a building material formulation.

In embodiments in which a particular printing head has two or more linear nozzle arrays, the nozzle arrays are optionally and preferably can be parallel to each other. When a printing head has two or more arrays of nozzles (e.g., FIG. 2B) all arrays of the head can be fed with the same building material formulation, or at least two arrays of the same head can be fed with different building material formulations.

When a system similar to system 110 is employed, all printing heads 16 are optionally and preferably oriented along the indexing direction with their positions along the scanning direction being offset to one another.

When a system similar to system 10 is employed, all printing heads 16 are optionally and preferably oriented radially (parallel to the radial direction) with their azimuthal positions being offset to one another. Thus, in these embodiments, the nozzle arrays of different printing heads are not parallel to each other but are rather at an angle to each other, which angle being approximately equal to the azimuthal offset between the respective heads. For example, one head can be oriented radially and positioned at azimuthal position 91, and another head can be oriented radially and positioned at azimuthal position 92. In this example, the azimuthal offset between the two heads is 91-92, and the angle between the linear nozzle arrays of the two heads is also 91-92.

In some embodiments, two or more printing heads can be assembled to a block of printing heads, in which case the printing heads of the block are typically parallel to each other. A block including several inkjet printing heads 16a, 16b, 16c is illustrated in FIG. 2C.

In some embodiments, system 10 comprises a stabilizing structure 30 positioned below heads 16 such that tray 12 is between stabilizing structure 30 and heads 16. Stabilizing structure 30 may serve for preventing or reducing vibrations of tray 12 that may occur while inkjet printing heads 16 operate. In configurations in which printing heads 16 rotate about axis 14, stabilizing structure 30 preferably also rotates such that stabilizing structure 30 is always directly below heads 16 (with tray 12 between heads 16 and tray 12).

Tray 12 and/or printing heads 16 is optionally and preferably configured to move along the vertical direction z, parallel to vertical axis 14 so as to vary the vertical distance between tray 12 and printing heads 16. In configurations in which the vertical distance is varied by moving tray 12 along the vertical direction, stabilizing structure 30 preferably also moves vertically together with tray 12. In configurations in which the vertical distance is varied by heads 16 along the vertical direction, while maintaining the vertical position of tray 12 fixed, stabilizing structure 30 is also maintained at a fixed vertical position.

The vertical motion can be established by a vertical drive 28. Once a layer is completed, the vertical distance between tray 12 and heads 16 can be increased (e.g., tray 12 is lowered relative to heads 16) by a predetermined vertical step, according to the desired thickness of the layer subsequently to be printed. The procedure is repeated to form a three-dimensional object in a layerwise manner.

The operation of inkjet printing heads 16 and optionally and preferably also of one or more other components of system 10, e.g., the motion of tray 12, are controlled by a controller 20. The controller can have an electronic circuit and a non-volatile memory medium readable by the circuit, wherein the memory medium stores program instructions which, when read by the circuit, cause the circuit to perform control operations as further detailed below.

Controller 20 can also communicate with a host computer 24 which transmits digital data pertaining to fabrication instructions based on computer object data which can be according to any format suitable for additive manufacturing, such as, but not limited to, one of the aforementioned formats. The object data formats can be structured according to a Cartesian system of coordinates. In these cases, computer 24 preferably executes a procedure for transforming the coordinates of each slice in the computer object data from a Cartesian system of coordinates into a polar system of coordinates. Computer 24 optionally and preferably transmits the fabrication instructions in terms of the transformed system of coordinates. Alternatively, computer 24 can transmit the fabrication instructions in terms of the original system of coordinates as provided by the computer object data, in which case the transformation of coordinates is executed by the circuit of controller 20.

The transformation of coordinates allows three-dimensional printing over a rotating tray. In non-rotary systems with a stationary tray with the printing heads typically reciprocally move above the stationary tray along straight lines. In such systems, the printing resolution is the same at any point over the tray, provided the dispensing rates of the heads are uniform. In system 10, unlike non-rotary systems, not all the nozzles of the head points cover the same distance over tray 12 during at the same time. The transformation of coordinates is optionally and preferably executed so as to ensure equal amounts of excess material formulation at different radial positions. Representative examples of coordinate transformations according to some embodiments of the present invention are provided in FIGs. 3A-B, showing three slices of an object (each slice corresponds to fabrication instructions of a different layer of the objects), where FIG. 3A illustrates a slice in a Cartesian system of coordinates and FIG. 3B illustrates the same slice following an application of a transformation of coordinates procedure to the respective slice.

Typically, controller 20 controls the voltage applied to the respective component of the system 10 based on the fabrication instructions and based on the stored program instructions as described below.

Generally, controller 20 controls printing heads 16 to dispense, during the rotation of tray 12, droplets of building material formulation in layers, such as to print a three-dimensional object on tray 12.

System 10 optionally and preferably comprises one or more radiation sources 18, which can be, for example, an ultraviolet or visible or infrared lamp, or other sources of electromagnetic radiation, or electron beam source, depending on the modeling material formulation being used. Radiation source can include any type of radiation emitting device, including, without limitation, light emitting diode (LED), digital light processing (DLP) system, resistive lamp and the like. Radiation source 18 serves for curing or solidifying the modeling material formulation. In various exemplary embodiments of the invention the operation of radiation source 18 is controlled by controller 20 which may activate and deactivate radiation source 18 and may optionally also control the amount of radiation generated by radiation source 18.

In some embodiments of the invention, system 10 further comprises one or more leveling devices 32 which can be manufactured as a roller 326 or a blade. Leveling device 32 serves to straighten the newly formed layer prior to the formation of the successive layer thereon. In some embodiments, leveling device 32 has the shape of a conical roller positioned such that its symmetry axis 34 is tilted relative to the surface of tray 12 and its surface is parallel to the surface of the tray. This embodiment is illustrated in the side view of system 10 (FIG. 1C).

The conical roller can have the shape of a cone or a conical frustum.

The opening angle of the conical roller is preferably selected such that there is a constant ratio between the radius of the cone at any location along its axis 34 and the distance between that location and axis 14. This embodiment allows roller 32 to efficiently level the layers, since while the roller rotates, any point p on the surface of the roller has a linear velocity which is proportional (e.g., the same) to the linear velocity of the tray at a point vertically beneath point p. In some embodiments, the roller has a shape of a conical frustum having a height h, a radius Ri at its closest distance from axis 14, and a radius R2 at its farthest distance from axis 14, wherein the parameters h, R\ and R satisfy the relation R IR2=(R-h)lh and wherein R is the farthest distance of the roller from axis 14 (for example, R can be the radius of tray 12).

The operation of leveling device 32 is optionally and preferably controlled by controller 20 which may activate and deactivate leveling device 32 and may optionally also control its position along a vertical direction (parallel to axis 14) and/or a radial direction (parallel to tray 12 and pointing toward or away from axis 14.

In some embodiments of the present invention printing heads 16 are configured to reciprocally move relative to tray along the radial direction r. These embodiments are useful when the lengths of the nozzle arrays 22 of heads 16 are shorter than the width along the radial direction of the working area 26 on tray 12. The motion of heads 16 along the radial direction is optionally and preferably controlled by controller 20.

In any of the embodiments described herein, the term "object" refers to a whole three- dimensional object or a part thereof. The present embodiments contemplate several types of object parts.

In the simplest case, an object part is an external object part, in which case the volume V of the three-dimensional space enclosed by the outer surface of the object is the sum of the volume V 1 enclosed by the outer surface of the object part, and the volume V2 enclosed by the outer surface of the object excluding that object part. An example of an external object part is an external wall or a cover or a structure that is connected to the outer surface of the object.

An object part can also be an internal object part, in which case the volume V of the three- dimensional space enclosed by the outer surface of the object equals the volume V2 enclosed by the outer surface of the object excluding that object part. In other words, an internal object part is a structure that is completely embedded within the three-dimensional space enclosed by the outer surface of the object.

A third type of object part is an object part that is partially internal and partially external. In this case, the sum of the volume V 1 enclosed by the outer surface of the object part, and the volume V2 enclosed by the outer surface of the object excluding that object part is larger than the volume V of the three-dimensional space enclosed by the outer surface of the object. In this case, the object can be described as comprising one object part that is partially embedded within another object part.

The computer object data used by the AM system of the present embodiments can describe the object as a whole, or the data can be structured in a manner that allows extracting a separate geometrical definition for each of a plurality of object parts, where the extracted geometrical definition defines the outer surface of the respective object part and may optionally and preferably also define an internal structure of the respective object part. An object part for which the computer object data allows extracting a separate geometrical definition of that object part is referred to herein as "a shell," and the computer object data that describe only the shell form a dataset referred to herein as computer object shell dataset. The computer object data of the entire object can thus be structured to include a collection of two or more computer object shell datasets which collectively describe the object as an assembly of shells. Such an object is referred to herein as an object assembly. Each shell of an object assembly can be an internal object part, an external object part, or a partially external, partially internal object part. All the computer object data in a collection of two or more computer object shell datasets that describes an object assembly form a dataset which is referred to herein as a combined computer object dataset, or briefly a combined dataset.

A representative example of an object assembly which is defined as an assembly of two shells is illustrated in FIG. 4A, and the two individual shells are illustrated in FIGs. 4B and 4C.

Some embodiments contemplate the fabrication of an object by dispensing different material formulations from different arrays of nozzles (belonging to the same or different printing head). These embodiments provide, inter alia, the ability to select material formulations from a given number of material formulations and define desired combinations of the selected material formulations and their properties. According to the present embodiments, the spatial locations of the deposition of each material formulation with the layer is defined, either to effect occupation of different three-dimensional spatial locations by different material formulations, or to effect occupation of substantially the same three-dimensional location or adjacent three-dimensional locations by two or more different material formulations so as to allow post deposition spatial combination of the material formulations within the layer, thereby to form a composite material formulation at the respective location or locations.

Any post deposition combination or mix of modeling material formulations is contemplated. For example, once a certain material formulation is dispensed it may preserve its original properties. However, when it is dispensed simultaneously with another modeling material formulation or other dispensed material formulations which are dispensed at the same or nearby locations, a composite material formulation having a different property or properties to the dispensed material formulations may be formed.

When the object is fabricated by dispensing more than one material formulation, the computer object data may optionally and preferably also comprise material assignment data, which assign a specific type of material formulation to each voxel or group of voxels, and therefore provide the controller with information regarding the type of material formulation to be dispensed at each voxel. When the computer object data comprises a collection of two or more computer object shell datasets, each dataset optionally and preferably also comprises material assignment data. When a shell of the object is to be fabricated from a single material formulation, the material assignment data of all the dataset elements is the same. When a shell of the object is to be fabricated from more than one material formulations, the respective dataset has two or more dataset elements that contain different material assignments.

In some embodiments of the present invention the system dispenses digital material formulation for at least one of the layers.

The phrase “digital material formulations”, as used herein and in the art, describes a combination of two or more material formulations on a pixel level or voxel level such that pixels or voxels of different material formulations are interlaced with one another over a region. Such digital material formulations may exhibit new properties that are affected by the selection of types of material formulations and/or the ratio and relative spatial distribution of two or more material formulations.

As used herein, a "voxel" of a layer refers to a physical three-dimensional elementary volume within the layer that corresponds to a single pixel of a bitmap describing the layer. The size of a voxel is approximately the size of a region that is formed by a building material, once the building material is dispensed at a location corresponding to the respective pixel, leveled, and solidified. The building material dispensed to form a voxel comprises one or more drops of building material dispensed by at least one inkjet printhead.

The present embodiments thus enable the deposition of a broad range of material formulation combinations, and the fabrication of an object which may consist of multiple different combinations of material formulations, in different parts of the object, according to the properties desired to characterize each part of the object.

Further details on the principles and operations of an AM system suitable for the present embodiments are found in U.S. Patent No. 9,031,680, the contents of which are hereby incorporated by reference.

While reducing to practice embodiments of the present invention it was unexpectedly found that when printing an object assembly, some color artifacts may arise, in particular at interfaces between the object parts that compose the assembly. A representative example of such color artifacts is shown in FIG. 5, which is an image of an object assembly 500 fabricated by additive manufacturing. Object assembly 500 is composed of a first object part 502 and a second object part 504, where first object part 502 is partially embedded in second object part 504. The computer object data that describe object 500 is a combined dataset that is formed by combining a first computer object shell dataset that describes only the first object part 502 with a second computer object shell dataset that describes only the second object part 504. Each of object parts 502 and 504 therefore has a separate geometrical definition that is described by a different dataset, and is therefore a shell.

As shown in the image, while the colors of each of the object parts are generally solid or vary gradually, there some color artifacts (pointed by arrows in FIG. 5) at the interfaces between object parts 502 and 504. These color artifacts are undesired for aesthetic reasons. The example shown in FIG. 5 is a case in which object 500 is a denture structure in which part 502 has a shape of teeth and object part 504 has a shape of a gingiva. When a denture is used in the mouth of a patient, the color artifacts may be aesthetically unpleasant (in this exemplified case, the marginal gingiva region is translucent while it should have been more opaque).

In a search for a solution to the above problem, the inventors found that color artifacts, particularly color artifacts at the interfaces between object parts, can be reduced or eliminated by updating the color or other optical property that are assigned by one or more of the computer object shell datasets that are combined to collectively describe the object assembly. It is to be understood that while FIG. 5 shows color artifacts for the specific case in which the object parts have shapes of teeth and gingiva, the solution described below is applicable also for other shapes of object assemblies. Reference is now made to FIG. 6, which is a flowchart diagram of a method suitable for encoding data for additive manufacturing, according to various exemplary embodiments of the present invention. It is to be understood that, unless otherwise defined, the operations described hereinbelow can be executed either contemporaneously or sequentially in many combinations or orders of execution. Specifically, the ordering of the flowchart diagrams is not to be considered as limiting. For example, two or more operations, appearing in the following description or in the flowchart diagrams in a particular order, can be executed in a different order (e.g., a reverse order) or substantially contemporaneously. Additionally, several operations described below are optional and may not be executed.

Computer programs implementing the method can commonly be distributed to users on a distribution medium such as, but not limited to, a flash memory, CD-ROM, or a remote medium communicating with a local computer over the internet. From the distribution medium, the computer programs can be copied to a hard disk or a similar intermediate storage medium. The computer programs can be run by loading the computer instructions either from their distribution medium or their intermediate storage medium into the execution memory of the computer, configuring the computer to act in accordance with the method. All these operations are well- known to those skilled in the art of computer systems.

The method can be embodied in many forms. For example, it can be embodied on a tangible medium such as a computer for performing the method steps. It can be embodied on a computer readable medium, comprising computer readable instructions for carrying out the method steps. In can also be embodied in an electronic device having digital computer capabilities arranged to run the computer program on the tangible medium or execute the instruction on a computer readable medium.

The method of the present embodiments can be executed by a data processor operating an AM system (e.g., computer 24). The computer object data processed by the method can be transmitted to the controller of the AM system (e.g., controller 20). The processed computer object data can be transmitted in its entirety before the AM process begins, or in batches (e.g., slice by slice) wherein the AM process begins after the first batch arrives but before receiving the last batch. The method of the present embodiments can alternatively be executed by the controller of the AM system (e.g., controller 20). In these embodiments, the controller receives input data and executes the method using these input data. The input data can be received by the controller before the AM process begins, or in batches, wherein the AM process begins after the first batch arrives but before receiving the last batch. The method begins at 600 and optionally and preferably continues to 601 at which types of building material formulations loaded to the AM system are obtained. This can be achieved by transmitting an interrogating signal to the AM system (e.g., to controller 20), and responsively receiving a signal pertaining to the types of building materials that are currently loaded to the AM system. Alternatively, the types of building material formulations can be entered manually.

Still alternatively, the method can be application-specific, wherein the type (but not necessarily the shape) of object assembly to be fabricated is predetermined and known in advance, in which case a specific set of building material formulations that are to be used during the fabrication process is also predetermined and known in advance, and so operation 601 can be skipped. As a representative example, the method can be a method of encoding data for additive manufacturing of a monolithic denture structure using a specific and predetermined set of building material formulations. In this exemplified case, there is no need to execute operation 601.

The method proceeds to 602 at which object shell datasets are received. Each of the received object shell datasets describes a different object part of the object assembly to be manufactured. Each object part is preferably described by the respective object shell dataset both in terms of the geometry of the object part and in terms of the visible optical property (e.g., color, hue, shading, transparency, etc.) of the object part.

The object shell datasets can thus be viewed as data structures that include a plurality of dataset elements each containing geometrical information and optical information. The geometrical information is in the form of three-dimensional coordinates describing a location and optionally shape of a geometrical element (e.g., a contour, a contour segment, a volumetric shape, a group of voxels, an individual voxel), such that the geometrical information of all dataset elements forms the respective object part. The optical information assigns the respective geometrical element with an optical property (e.g., color, hue, shading, transparency, etc.) that is used in order to decide which building material formulation or combination of building material formulations is to be used during fabrication. The object shell datasets may optionally and preferably also include metadata (e.g., creator, creation time, etc.).

Typically, the software operating the computer of the AM system selects the building material formulations for dispensing based on the optical properties in the object shell datasets. For example, when a particular dataset element is assigned with a particular color and/or a particular transparency, the software operating the computer of the AM system selects a building material formulation or a combination of building material formulations that provides that particular color and/or transparency. The building material formulation(s) that are selected based on the optical property of the dataset element is/or referred to as the building material formulation or combination of building material formulations that correspond to the optical property of the respective dataset element.

The object shell datasets are typically prepared in advance and are read by the method from a computer readable medium. Preparation of data structures suitable for use as the object shell datasets of the present embodiments can be by any commercially available computer software products suitable for generating computer object data. A representative example of such computer software product includes, without limitation, 3Shape Dental System, distributed by 3Shape Denmark, and GrabCAD®, distributed by Stratasys Inc., USA.

The preparation of object shell dataset(s) may include constructing datasets in which each dataset element contains geometrical and optical information, as further detailed hereinabove. Alternatively, the preparation may include constructing datasets in which each dataset element contains geometrical information, but not optical information, wherein the optical information is added by the operator at a later stage. Representative examples for workflows suitable for preparing object shell datasets, and for using these datasets to fabricate an object assembly are provided in Example 4 of the Examples section that follows.

The method optionally and preferably proceeds to 603 at which the datasets are combined into a combined dataset, describing the object assembly to be fabricated. In some embodiments, the method reads the combined dataset from a computer readable medium, in which case the object shell datasets need not be combined by the method. The object assembly that is described by the combined dataset represents partial embeddings of object parts. The partial embeddings are of the type that is schematically illustrated in the perspective view of FIG. 4A above.

Further details regarding the partial embeddings are provided in FIG. 7A, which schematically illustrates a planar view representing a cross-section in an arbitrary plane (forming an arbitrary angle with the tray of the AM system) passing through an object assembly 700. Object assembly 700 is composed of a first object part 702 that is partially embedded in a second object part 704. The illustration in FIG. 7A also represents the respective object shell datasets, wherein the geometry of each of the object parts 702 and 704 is illustrated as contours delineated by solid lines and the optical property assignments of each of the object parts are illustrated as fillings or hatchings, and wherein each hatching or filling style represents a specific optical property assigned to the respective contour of the geometry.

In the illustration of FIG. 7A, which is not to be considered as limiting, the information provided by the computer object shell dataset that describes object part 702 includes an inner region 702a encapsulated by an outer encapsulating region 702b, where each region is assigned with a different optical property. Similarly, the information provided by the computer object shell dataset that describes object part 704 includes an inner region 704a encapsulated by an outer encapsulating region 704b, where each region is assigned with a different optical property. It is to be understood that other geometries and optical property assignments are also contemplated in some embodiments of the present invention. For example, one or more of the computer object shell datasets can describe an object part having a core region enclosed by a plurality of encapsulating regions defining an onion-like structure for that object part.

As used herein, "onion-like structure" is defined as a structure which includes a core region and a plurality of encapsulating regions each encapsulating a different volume size, wherein each encapsulating region encapsulates the core region, and wherein for any pair of the encapsulating regions one of the encapsulating regions of the pair is encapsulated by another encapsulating region of that pair. Conveniently, the encapsulating regions can be viewed as a series in which the encapsulating regions are ordered according to the size of the encapsulation volumes that are encapsulated by them. With such a view, the zth encapsulating region of the series encapsulates a volume Vi that contains the core and all the z-1 encapsulating regions for which the encapsulation volume is smaller than Vz.

A representative example of an object part 800 in embodiment in which the object part has a core region 800a enclosed by three encapsulating regions 800b, 800c, 800d defining an onionlike structure is illustrated in FIG. 8. The structure of the four regions is onion-like because region 800b encapsulates core region 800a, region 800c encapsulates regions 800b and 800a, and region 800d encapsulates regions 800c, 800b and 800a. Similarly to FIG. 7A above, FIG. 8 also represents the respective object shell dataset, wherein the geometry is illustrated as contours delineated by solid lines and the optical property assignments are illustrated as fillings or hatchings. Note that in the representative illustration of FIG. 8, when viewed as an object shell dataset, the optical property assigned to region 800a is the same as the optical property assigned to region 800c, and the optical property assigned to region 800b is the same as the optical property assigned to region 800d. However, while this embodiment is preferred, embodiments in which the optical property assigned to region 800a is different from the optical property assigned to region 800c, and/or in which the optical property assigned to region 800b is different from the optical property assigned to region 800d, are also contemplated.

In some embodiments of the present invention the object shell datasets received at 602 include only geometrical information that describes the outermost surfaces of object parts 702 and 704, and do not include any information regarding the shape, location, and size of the individual regions therein. In these embodiments, the outer and inner regions (e.g., one or more of regions 702a, 702b, 704a, 704b, 702a, 800a, 800b, 800c, 800d), are defined by the method. Such a definition can be according to predetermined parameters, such as, but not limited to, the wall thickness of the respective region, the distance between the respective region and the outermost surface of the object part, the shape of the respective region, etc. Following the definition of the regions, an optical property or properties is/are assigned top each region, thereby providing the object shell dataset including both geometrical and optical information. The optical properties can be assigned to one or more of the individual regions automatically and/or by receiving input from the user, e.g., by means of a graphical user interface (GUI). For example, the object parts can be displayed on the GUI, and the user can be allowed to select a desired optical property (e.g., from a predefined list of optical properties) separately for each object part or for each region. Typically, but not necessarily, the optical properties of the internal regions are selected automatically, based on a predefined color and transparency scheme, and the optical properties of the external regions is selected based on user input.

The method proceeds to 604 at which the optical property assignments for the combined dataset are updated. Generally, the update includes replacing optical property assignment for each dataset element that corresponds to a portion of a respective object part which is external in the object part but internal in the object assembly. The replacement is by substituting the optical property assigned to the dataset element with a substitute optical property that corresponds to a substitute building material formulation or combination of substitute building material formulations that is/are selected from the material formulations obtained at 601. In one embodiment, the substitute building material formulations is selected from a white material, and a combination of a clear material and a white material.

Referring again to FIG. 7A, when object parts 702 and 704 are viewed individually, the respective object shell datasets define each of regions 702b and 704b as outer regions. Yet, once the individual object shell datasets are combined to describe object assembly 700, there are portions of regions 702b and 704b that become internal regions in object assembly 700. These portions are shown at 706 and 708, respectively. The update 604 therefore comprises replacing the optical property assigned to portions 706 and 708 of regions 702b and 704b, without replacing the optical property assigned to other portions of regions 702b and 704b.

It is appreciated that when object 702 is partially embedded in object 704 there may be some mismatches between the shape of the outer surfaces of object parts at the region in which they are embedded, and so the partial imbedding may result in one or more air gaps 712 between object parts 702 and 704. Such air gaps are optionally and preferably identified and the update 604 preferably includes assigning an optical property also to these air gaps. Preferably, the optical property that is assigned to air gaps 712 is the substitute optical property, for example, an optical property that is the same or similar to one of the optical properties that are assigned to regions 702a and 704a.

The identification of portions 706 and 708 can be by any image processing technique known in the art. For example, portions 706 and 708 can be identified by searching for areas in which regions 702b and 704b are adjacent to each other or within a predetermined distance from each other. Also contemplated is the use of one or more filters or masks. A representative example of a mask is illustrated in FIG. 7B. In the illustrated embodiment, the method defines a mask 710 that includes all the internal regions of the object assembly. The portions 706 and 708 of regions 702b and 704b are then identified as the intersects regions 702b and 704b and mask 710. Mask 710 can be conveniently defined as including all the internal points of the assembly for which the distance to the outer surface of the assembly is above a predetermined threshold.

FIG. 7C illustrates object assembly 700 following the replacement of the optical property assignments of portions 706 and 708 of regions 702b and 704b. Note that the replacement of optical property assignments as illustrated in FIG. 7B may be described as segmentation of one or more of the contours that define the geometries of object parts 702 and 704. Thus, outer region 702b (see FIG. 7A) is now composed of a segment 702bl (FIG. 7C) which is assigned with the same optical property as outer region 702b before the update, and a segment 702b2 which is assigned with a substitute optical property which corresponds to a material formulation or combination of material formulations that is/are selected from the material formulations obtained at 601. Similarly, outer region 704b (see FIG. 7A) is now composed of a segment 704bl (FIG. 7C) which is assigned with the same optical property as outer region 704b before the update, and a segment 704b2 which is assigned with a substitute optical property corresponding to a substitute optical property which corresponds to a material formulation or combination of material formulations that is/are selected from the material formulations obtained at 601. In some embodiments, each of the segments 702b2 and 704b2 is assigned with an optical property corresponding to one or more building material formulations selected from a white material, and a combination of a clear material and a white material. In some embodiments of a combination of white and clear material, the ratio between the white material to the clear material is between 100:0 to 0:100, preferably between 100:0 to 25:75.

Alternatively, the replacement of optical property assignments may be accompanied by unification of regions. For example, regions 702a, 704a, 702b2, and 704b2 can all be defined as the same inner region of assembly 700 (e.g., all the points of mask 710 of FIG. 7B) and can thus be assigned with the same optical property (e.g., the optical property assigned to region 704a or 702a before the update). In embodiments in which one or more of the object parts includes more than one encapsulating region, such as in the case shown in FIG. 8, the update can include replacing the optical property assignment for each dataset element corresponding to a portion of at least one encapsulating region 800b, 800c, 800d, which is internal in object assembly 700. Preferably, no optical property assignment update is applied to the core region 800a. In embodiments in which one of the encapsulating regions has the same optical property assignment as the core 800a, no optical property assignment update is applied to that encapsulating region (e.g., region 800c in FIG. 8).

The advantage of the update 604 is that it prevents a situation in which an inner region of object assembly 700 is fabricated from a material formulation or material formulation combination that is intended for use at an outer region of the object to be fabricated. The Inventor found that such an update significantly reduces color artifacts at the outermost surface of the fabricated object.

Preferably, the replacement of optical property assignment is executed such as to increase an opacity level of the portion of the respective object part for which the replacement is applied. Thus, with reference to FIG. 7C, the replacement of optical property is executed such that region 702b2 is fabricated with a material formulation which, once hardened, provides a material that is more opaque than the material provided once the material formulation used to fabricate region 702c is hardened. Similarly, the replacement of optical property is executed such that region 704b2 is fabricated with a material formulation which, once hardened, provides a material that is more opaque than the material provided once the material formulations used to fabricate region 704c is hardened.

The advantage of the embodiments in which the opacity level is increased is that it ensures that the inner region of the object is more opaque than the encapsulating outer region, thus making the appearance of the fabricated object more pleasant.

In some embodiments of the present invention the update 604 comprises substituting a colorless or colored optical property with a substitute optical property, wherein the amount of white portion in the substitute optical property is higher than the amount of white portion in the colorless or colored optical property. In terms of the corresponding building material formulations, the substitute optical property corresponds to a substitute building material formulation or combination of substitute building material formulations which is/are selected from the material formulations obtained at 601, wherein the amount of white coloring agent (e.g., white pigment) in the substitute building material formulation is higher than the amount of white coloring agent in the colorless or colored building material formulation. The advantage of these embodiments is that it increases the color brightness at the outermost surface of the fabricated object, thus reducing color artifacts, which typically appear darker due to too high transparency of the inner regions at or near the interface between the object parts. Representative examples of colorless or colored building material formulations and of substitute building material formulations suitable for the present embodiments are provided in Example 2, below.

The method optionally and preferably continues to 605 at which the combined dataset is sliced into a plurality of slices. The slicing 605 can be done by the computer running slicer software to provide slice data describing a plurality of slices, each defined over a plurality of voxels, and describing one of the layers of the object to be manufactured. The slicing operation 605 preferably assigns to each voxel of each slice, a building material according to the optical property assignments as updated at 604. Typically, the slicing operation 605 first uses the geometrical information in the combined dataset to determine to which region the respective voxel belongs, and then uses the optical information to assign the voxel with a building material formulation that corresponds to the optical property assigned to the determined region.

In some embodiments of the present invention the method continues to 606 at which the slice data are transmitted to a controller of an AM system (e.g., controller 20) for additive manufacturing of a plurality of layers respectively corresponding to the plurality of slices.

The method ends at 607.

Method 600 is useful in cases in which the computer object shell datasets of the object parts are loadable from a computer readable medium or the software that generates these datasets. In some cases, however, the data that are available are slice data, and the individual computer object shell datasets are not easily retrievable. The Inventors found that the aforementioned problem of color artifacts can be solved also in such cases. This can be done by subjecting the slice data to one or more image processing procedures, and using the output of these procedures for extracting information that is available when the computer object shell datasets are known, but is not directly retrievable from the slice data. A flowchart diagram of a method suitable for encoding data for additive manufacturing in this case is provided in FIG. 9.

The method begins at 900 and optionally and preferably continues to 601 at which types of building material formulations loaded to the AM system are obtained, as further detailed hereinabove. In case in which the method is application-specific, the specific set of building material formulations that are to be used during the fabrication process is predetermined and known in advance, and so operation 601 can be skipped, as further detailed hereinabove.

The method proceeds to 902 at which slice data are received. The slice data describe a plurality of slices, where each slice is defined over a plurality of voxels, and wherein each voxel is either assigned with a building material formulation or is assigned to remain void (or, equivalently, assigned with air). The method proceeds to 903 at which image processing is applied to each slice, to identify in the slice regions corresponding to layers of different object parts (e.g., object parts 702, and 704), wherein the layer of one of the object parts is at least partially embedded in the layer of the other second object part.

Consider for example the slices 950, 952, and 954 illustrated in FIGs. 10A-C, respectively. The data describing these slices includes a material assignment for each voxel of the respective slice. For clarity of presentation the voxels themselves are not illustrated, but the material assignments are represented by fillings and hatchings and so a region of a particular filling or hatching (including a region without filling) is to be understood as composed of voxels, where all the voxels in that region have the same material and/or material combination assignment. In FIGs. 10A-C, a region without filling represents no material assignment, and so no formulation is to be dispensed in the voxels of that region. Slices 950, 952, and 954 correspond to planes at different vertical coordinate over the object assembly, where the vertical coordinate of slice 950 is higher than the vertical coordinate of slice 952 and the vertical coordinate of slice 952 is higher than the vertical coordinate of slice 954. For clarity of presentation, regions of different fillings or hatchings are delineated by solid lines, but the slice data typically do not contain information regarding such delineation.

Each of the slices is represented as an image where the pixels of the image correspond to voxels in the fabricated object, and where the height of the voxels equals the thickness of the layer that the slice represents. The slice image can be subjected to image processing to obtain positions and shapes of distinct image regions. Each image region can be identified using its shape and size and optionally and preferably using a non-geometric image feature, such as, but not limited to, grey level, color, or hue, in each of the pixels of the image. A typical situation is when two object parts are to be fabricated from different materials on their outer encapsulating region but the same material in their core, wherein one of the objects is partially embedded in the other object and is therefore smaller in size compared to the other object. In this case, the cores of the object part have the same non-geometric characteristics (e.g., the same grey level), and so the distinction between the two object parts within the slice can be made by analyzing the sizes of the identified image regions.

Suppose that the object assembly to be fabricated is of the type shown in FIG. 7A, namely an object assembly having a first object part that is partially embedded in a second object part, wherein each of the object parts has an inner region, and an outer encapsulating region, respectively. Applying image processing to slice 950 can result in the identification of two instances of the first object part 702, where each instance comprises inner region 702a and outer encapsulating region 702b. Applying image processing to slice 952 can result in the identification of the aforementioned instances of the first object part 702 and also of one instance of second object part 704 with its inner region 704a and outer region 704b. A distinction between object part 702 and object part 704 can be made based on the sizes and/or geometries of the regions in slice 952. Applying image processing to slice 954 can result in the identification of the aforementioned second object part 704 with its inner region 704a and outer region 704b.

Note that in slice 954 object part 704 can be identified as such by comparing its size and/or geometry also to regions in other slices. For example, the region corresponding to object 704 is larger in slice 954 than the regions corresponding to object part 702 in slice 952. Similarly, in slice 950 object part 702 can be identified as such by comparing its size and/or geometry to regions in slice 952, wherein the regions corresponding to object part 702 is smaller in slice 950 than the regions corresponding to object part 704 in slice 952.

It is recognized that a slice can include also voxels that are designated to be part of support structures and that are therefore assigned with support material formulation. These voxels can be identified by their non-geometric imagery characteristics, because voxels that are assigned with support material formulation are typically represented in the slice data by a unique grey level, color or hue.

A representative example of an image processing procedure suitable for identifying layers of different object parts from slice data are provided in Example 1 of the Examples section that follows.

Once the image processing of all the slices is completed, the method can optionally determine that the first object part 702 is partially embedded in the second object part 704, because there are slices (e.g., slice 950) that contain layers of first object part 702 but do not contain layers of second object part 704. The method can optionally and preferably proceed to 904 at which a computer object shell dataset is constructed for each of the object parts, based on the identification of the layers of the object parts in each slice. Each computer object shell dataset describes the respective object part in three dimensions, and is constructed by considering each object part as a stack of layers as identified over the slices. Operation 904 may optionally and preferably also include constructing a combined computer object shell dataset describing a three-dimensional geometry and building material assignments of an object assembly representing a partial embedding of the first object part 702 in the second object part 704. This can be done constructed by considering the object assembly as a stack of layers in which each layer contains all the object part layers as identified over the slices. The method continues to 905 at which building material assignments are updated for at least one of the slices by replacing material assignment for each voxel corresponding to a portion of a respective object part which is external in the object part but internal within the layer of the object assembly in the slice. With reference to the exemplified situation illustrated in FIGs. 10A- C, the material assignment is replaced for region 702b in slice 952 because this region is external in object part 702 but is internal in the object assembly's layer described by slice 952. The material assignment is replaced also for the region 704b in slice 952 that encapsulates region 702b because this region is external in object part 704 but is internal in the object assembly's layer described by slice 952. Conversely, the material assignment is not replaced for the region 704b in slice 952 that encapsulate region 704a, for region 702b in slice 950, and for region 704b in slice 954, because in these slices the respective region is not internal in the object assembly's layer.

Note that it is not required to explicitly identify the individual regions 702a, 702b, 704a, and 704b within the slice in order to execute operation 905. The identification of regions with the slice for which material assignment replacement is required can be based on the proximity of the respective voxel to the outer surface of the object and to the nearby object part. Thus, the method can apply a set of proximity criteria to each voxel that is identified as belonging to a particular object part, by calculating the distance between the voxel under analysis and the outermost edge of the object assembly within the slice, and/or the distance between the voxel under analysis and one or more voxels identified as belonging to another object part. The calculated distances can be compared to a predetermined distance threshold, wherein the voxel under analysis is defined as a voxel that satisfies a proximity criterion when the respective calculated distance is less that the distance threshold. Following is an example that demonstrates the use of these criteria for deciding whether or not a material assignment update is required.

When the voxel under analysis satisfies the proximity criterion with respect to the outermost edge of the object assembly within the slice, the method can determine that no material assignment update is required for that voxel, because it belongs to a region that is external in the object assembly.

When the voxel under analysis fails to satisfy the proximity criterion with respect to the outermost edge of the object assembly within the slice, and also fails to satisfy the proximity criterion with respect to voxels identified as belonging to another object part, the method can determine that no material assignment update is required for that voxel, because it belongs to a region that is internal in the object part.

When the voxel under analysis satisfies the proximity criterion with respect to voxels identified as belonging to another object part, but fails to satisfy the proximity criterion with respect to the outermost edge of the object assembly, the method can update the material assignment for that voxel, because it belongs to a region that is external in the respective object but internal in the object assembly.

In the optional embodiments in which operation 904 is executed, the update of building material assignments can be executed by replacing material assignment for voxels corresponding to a portion of a respective object part which are external in the object part but internal in the object assembly. This operation is similar to operation 604 described with respect to method 600 above, except that it is executed on a per-slice basis.

The replacement is by substituting the building material formulation of the respective voxel with a substitute building material formulation, as further detailed hereinabove with respect to method 600.

In some embodiments of the present invention method 900 continues to 606 at which the slice data are transmitted to a controller of an AM system (e.g., controller 20) for additive manufacturing of a plurality of layers respectively corresponding to the plurality of slices.

The method ends at 907.

As used herein the term “about” refers to ± 10 %.

The terms "comprises", "comprising", "includes", "including", “having” and their conjugates mean "including but not limited to".

The term “consisting of’ means “including and limited to”.

The term "consisting essentially of" means that the composition, method or structure may include additional ingredients, steps and/or parts, but only if the additional ingredients, steps and/or parts do not materially alter the basic and novel characteristics of the claimed composition, method or structure.

As used herein, the singular form "a", "an" and "the" include plural references unless the context clearly dictates otherwise. For example, the term "a compound" or "at least one compound" may include a plurality of compounds, including mixtures thereof.

Throughout this application, various embodiments of this invention may be presented in a range format. It should be understood that the description in range format is merely for convenience and brevity and should not be construed as an inflexible limitation on the scope of the invention. Accordingly, the description of a range should be considered to have specifically disclosed all the possible subranges as well as individual numerical values within that range. For example, description of a range such as from 1 to 6 should be considered to have specifically disclosed subranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6 etc., as well as individual numbers within that range, for example, 1, 2, 3, 4, 5, and 6. This applies regardless of the breadth of the range.

Whenever a numerical range is indicated herein, it is meant to include any cited numeral (fractional or integral) within the indicated range. The phrases “ranging/ranges between” a first indicate number and a second indicate number and “ranging/ranges from” a first indicate number “to” a second indicate number are used herein interchangeably and are meant to include the first and second indicated numbers and all the fractional and integral numerals therebetween.

It is appreciated that certain features of the invention, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention, which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable sub-combination or as suitable in any other described embodiment of the invention. Certain features described in the context of various embodiments are not to be considered essential features of those embodiments, unless the embodiment is inoperative without those elements.

Various embodiments and aspects of the present invention as delineated hereinabove and as claimed in the claims section below find experimental support in the following examples.

EXAMPLES

Reference is now made to the following examples, which together with the above descriptions illustrate some embodiments of the invention in a non limiting fashion.

EXAMPLE 1

Image Processing of Slice Data

Typically, the input slice data provide information to fabricate more than one three- dimensional objects on the same tray of the AM system. In this case, the image processing procedure optionally and preferably comprises a cropping operation that is applied to each input slice in order to separate the slice data of individual objects. The output of this operation is two or more slice datasets, each including all the data of all the slices of one of the objects. Slice images of three slice datasets extracted from the same input slice data are shown in FIGs. 11A-C, where each image represents one slice of the respective slice dataset. In FIGs. 11A-C, black color represents air (namely voxels which are to remain vacant during the fabrication), grey color represents support material formulation, and white color represents reinforcing elements made of a modeling material. When rectangular cropping is insufficient to isolate the objects from each other (see FIGs. 11 A and 1 IB), non-air parts at the borders of the crops are removed. The image processing operation preferably includes a cleaning procedure that cleans noisy 3D image data in order to identify regions corresponding to teeth. The procedure typically includes one or more morphology operations and may optionally and preferably be followed by a regionfilling operation. The morphology operations may include a binary operation in which a value of a pixel is selected based on the values stored in the majority of the pixels in its neighborhood (e.g., "1" when the majority of the pixels in its neighborhood store a "1", and "0" otherwise).

The morphology operations may additionally or alternatively include morphological opening and/or morphological closing. The morphological opening applies eroding followed by dilation, where both eroding and dilation use the same structuring element. The morphological closing applies dilation followed by eroding, where both eroding and dilation use the same structuring element. In the present example, the structuring element which was used to identify the teeth was a sphere. The radius of the sphere for the morphological closing is typically larger than the radius of the sphere for the morphological opening. For example, the radius of the sphere for the morphological closing can be from 4 to 6, and the radius of the sphere for the morphological opening can be from 1 to 3. In the present example, the radius of the sphere for the morphological closing was set to 5 and the radius of the sphere for the morphological opening was set to 2.

In the present example, all three morphological operations were executed, where the morphological opening followed the binary operation and the morphological closing followed the morphological opening. The region-filling operation followed the morphological opening.

The image processing operation preferably includes identification of surrounding regions, e.g., regions that immediately surround regions identified as corresponding to teeth, and/or regions that immediately surround regions identified as corresponding to gingiva, and/or regions that immediately surround regions identified as voids (containing no building material). This identification can be done by applying a dilation operation using a 3D structuring element. In the present example the structuring element for the dilation operation was a cuboid, and the size of the cuboid defined for the voids was about 40% smaller that the size of the cuboids defined for each of the teeth and gingiva.

FIG. 12A is an image of a single slice of an object assembly including an object part that has a shape of a plurality of teeth and an object part that has a shape of a gingiva. In FIG. 12A, black pixels represent air, white pixels represent support material, light grey pixels represent core regions and reinforcing elements (e.g. white opaque modeling material), and dark grey pixels represent colored and transparent modeling materials. As shown, it is difficult to identify the outer regions of the teeth and the gingiva in the slice, because these regions are represented by similar colors (dark grey). On the other hand, the regions that correspond to support structures can be removed by means of grey level identification because the support material formulation has a unique color code in the slice data (white, in the present Example).

The regions that correspond to the reinforcing elements can be distinguished from the regions that correspond to the core regions of the object parts by means of geometrical analysis wherein regions containing distribution of isolated dots colored in light grey correspond to reinforcing elements, and regions containing a continuum colored in light grey correspond to core regions of the object parts. The different object parts can be identified by size analysis, wherein a region that corresponds to the embedding object part (gingiva in the present Example) can be identified as the largest continuum over the slice that is colored in light grey, and the regions that corresponds to the embedded object part (teeth in the present Example) can be identified as all the regions other than the gingiva and the reinforcing elements. Alternatively or additionally, a region that corresponds to the embedded object part can be identified as a continuum that is colored in light grey, that is encapsulated or partially encapsulated by dark gray region, and that is embedded or partially embedded in the previously identified embedding object part.

The results of the identifications are shown in FIGs. 12B and 12C, where FIG. 12B is a slice image containing only the regions that correspond to the gingiva and FIG. 12C is a slice image containing only the regions that correspond to the teeth.

Once the object parts (teeth and gingiva, in the present Example) are identified, material assignment update can be applied based on proximity criteria. FIG. 12D shows a slice image in which the result of the application of proximity criteria is represented by different shades of grey, and is also designated by reference signs 1002, 1004, 1006, 1008, 1010 and 1012. In FIG. 12D, black color represents air. Region 1002 is identified as a region of the teeth that is proximal to the air, and is therefore classified as belonging to the outermost region of the teeth. Region 1008 is identified as a region of the gingiva that is proximal to the air, and is therefore classified as belonging to the outermost region of the gingiva. Region 1006 is identified as a region of the teeth that is proximal to the gingiva, and is therefore classified as belonging to a region that is external in the teeth but internal in the object assembly. Region 1010 is identified as a region of the gingiva that is proximal to the teeth, and is therefore classified as belonging to a region that is external in the gingiva but internal in the object assembly. Region 1012 is identified as region of the gingiva that is not proximal to air or teeth, and is therefore classified as belonging to a region that is internal in the gingiva. Region 1004 is identified as region of the teeth that is not proximal to air or gingiva, and is therefore classified as belonging to a region that is internal in the teeth. According to some embodiments of the present invention the material assignments are updated for regions 1010 and 1006 because these regions are external in the respective object part but internal in the object assembly, as shown in FIG. 12E. The material assignments in the other regions are preferably not updated.

EXAMPLE 2

Formulation Suitable for use as a Colored, Colorless or Substitute Building Material Formulation

Following is a description of modeling material formulations suitable for use as a colorless or colored building material formulation (referred to in this Example as Type A Modeling Material Formulation), and of a modeling material formulation suitable for use as a substitute building material formulation (referred to in this Example as Type B Modeling Material Formulation).

The type A formulation described below is optionally and preferably, but not necessarily, transparent or partially transparent. The type A formulation described below is particularly useful for the fabrication of an outermost region of the object assembly. In some embodiments of the present invention the type A formulation described below is used for the fabrication of an outermost region of an object assembly which is a monolithic structure comprising a denture base having a shape of a gingiva and artificial teeth.

The type B formulation described below is suitable for use as an opaque or partially opaque formulation, according to some embodiments of the present invention. The type B formulation described below is optionally and preferably more opaque and less transparent than the type A formulation described below. The type B formulation described below is particularly useful for the fabrication of one or more of the inner regions of the object assembly. In some embodiments of the present invention the type B formulation described below is used for the fabrication of one or more of the inner regions of an object assembly which is a monolithic structure comprising a denture base having a shape of a gingiva and artificial teeth. Preferably, but not necessarily, the type B formulation described below is used for the fabrication of one or more of the inner regions of the denture base of the monolithic structure.

According to some of any of the embodiments described herein, each of the modeling material formulations is such that is usable in three-dimensional inkjet printing and meets the process requirements of three-dimensional inkjet printing, as described herein.

According to some of any of the embodiments described herein, a modeling material formulation as described herein comprises one or more curable materials, and is also referred to herein as a curable formulation. A curable formulation is characterized in that its viscosity (e.g., at room temperature) increases, upon exposure to a curing condition as described herein, by at least 2-folds, preferably by at least 5-folds, and more preferably by at least one order of magnitude. Herein throughout, a “curable material”, which is also referred to herein as a “solidifiable material” is a compound (e.g., monomeric or oligomeric or polymeric compound) which, when exposed to a curing condition (e.g., curing energy), as described herein, solidifies or hardens to form a cured modeling material as defined herein. Curable materials are typically polymerizable materials, which undergo polymerization and/or cross-linking when exposed to a suitable curing condition, typically a suitable energy source. A curable or solidifiable material is typically such that its viscosity increases by at least one order of magnitude when it is exposed to a curing condition.

In some of any of the embodiments described herein, a curable material can be a monomer, an oligomer or a short-chain polymer, each being polymerizable and/or cross -linkable as described herein.

In some of any of the embodiments described herein, when a curable material is exposed to a curing condition (e.g., curing energy such as, for example, radiation), it polymerizes by any one, or combination, of chain elongation and cross -linking.

In some of any of the embodiments described herein, a curable material is a monomer or a mixture of monomers which can form a polymeric modeling material upon a polymerization reaction, when exposed to a curing condition at which the polymerization reaction occurs. Such curable materials are also referred to herein as monomeric curable materials.

In some of any of the embodiments described herein, a curable material is an oligomer or a mixture of oligomers which can form a polymeric modeling material upon a polymerization reaction, when exposed to a curing condition at which the polymerization reaction occurs. Such curable materials are also referred to herein as oligomeric curable materials.

In some of any of the embodiments described herein, a curable material, whether monomeric or oligomeric, can be a mono-functional curable material or a multi-functional curable material.

Herein, a mono-functional curable material comprises one functional group that can undergo polymerization when exposed to a curing condition (e.g., curing energy).

A multi-functional curable material comprises two or more, e.g., 2, 3, 4 or more, functional groups that can undergo polymerization when exposed to a curing condition. Multi-functional curable materials can be, for example, di-functional, tri-functional or tetra-functional curable materials, which comprise 2, 3 or 4 groups that can undergo polymerization, respectively. The two or more functional groups in a multi-functional curable material are typically linked to one another by a linking moiety, as defined herein. When the linking moiety is an oligomeric moiety, the multifunctional group is an oligomeric multi-functional curable material. Exemplary curable materials that are commonly used in additive manufacturing and in some of the present embodiments are acrylic materials.

Herein throughout, the term “acrylic materials” collectively encompasses materials bearing one or more acrylate, methacrylate, acrylamide and/or methacrylamide group(s).

The term “(meth) acrylate” and grammatical diversions thereof encompasses materials bearing one or more acrylate and/or methacrylate group(s).

The curable materials included in the formulations described herein may be defined by the properties of the materials before hardening, when appropriate. Such properties include, for example, molecular weight (MW), functionality (e.g., mono-functional or multi-functional), and viscosity

The curable materials included in the formulations described herein are otherwise defined by the properties provided by each material, when hardened. That is, the materials may be defined, when appropriate, by properties of a material formed upon exposure to a curing condition, for example, upon polymerization. These properties (e.g., Tg, HDT), are of a polymeric material formed upon curing any of the described curable materials alone.

As used herein, the term “curing” or “hardening” describes a process in which a formulation is hardened. This term encompasses polymerization of monomer(s) and/or oligomer(s) and/or cross-linking of polymeric chains (either of a polymer present before curing or of a polymeric material formed in a polymerization of the monomers or oligomers). The product of a curing reaction or of a hardening is therefore typically a polymeric material and in some cases a crosslinked polymeric material.

A “rate of hardening” as used herein represents the rate at which curing is effected, that is, the extent at which curable materials underwent polymerization and/or cross-linking in/within a given time period (for example, one minute). When a curable material is a polymerizable material, this phrase encompasses both a mol % of the curable materials in a formulation that underwent polymerization and/or cross-linking at the given time period, upon exposure to a curing condition; and/or the degree at which polymerization and/or cross-linking was effected, for example, the degree of chain elongation and/or cross -linking, at a given time period. Determining a rate of polymerization can be performed by methods known to those skilled in the art.

A “rate of hardening” can alternatively be represented by a degree at which a viscosity of a formulation changes in a given time period, that is, the rate at which the viscosity of a formulation increases upon exposure to curing condition.

Herein, the phrase “a condition that affects curing” or “a condition for inducing curing”, which is also referred to herein interchangeably as “curing condition” or “curing inducing condition” describes a condition which, when applied to a formulation that contains a curable material, induces at least partial polymerization of monomer(s) and/or oligomer(s) and/or crosslinking of polymeric chains. Such a condition can include, for example, application of a curing energy, as described hereinafter, to the curable material(s), and/or contacting the curable material(s) with chemically reactive components such as catalysts, co-catalysts, and activators.

When a condition that induces curing comprises application of a curing energy, the phrase “exposing to a curing condition” means that the dispensed layers, preferably each of the dispensed layers, is/are exposed to the curing energy and the exposure is typically performed by applying a curing energy to (e.g., each of) the dispensed layers.

A “curing energy” typically includes application of radiation or application of heat.

The radiation can be electromagnetic radiation (e.g., ultraviolet or visible light), or electron beam radiation, or ultrasound radiation or microwave radiation, depending on the materials to be cured. The application of radiation (or irradiation) is effected by a suitable radiation source. For example, an ultraviolet or visible or infrared or Xenon lamp can be employed, as described herein.

A curable material, formulation or system that undergoes curing upon exposure to radiation is referred to herein interchangeably as “photopolymerizable” or “photoactivatable” or “photocurable”.

In some of any of the embodiments described herein, a curable material is a photopolymerizable material, which polymerizes or undergoes cross-linking upon exposure to radiation, as described herein, and in some embodiments the curable material is a UV-curable material, which polymerizes or undergoes cross-linking upon exposure to UV-vis radiation, as described herein.

In some embodiments, a curable material as described herein includes a polymerizable material that polymerizes via photo-induced radical polymerization.

According to some of any of the embodiments as described herein, all the curable materials in the formulation are photocurable materials, for example, (meth)acrylic materials. According to some of these embodiments, the curing condition is preferably irradiation, further preferably UV- irradiation.

According to some of any of the embodiments described herein, the modeling material formulation is such that when hardened it meets the requirements of common standards in the denture field, such as ISO 20795-1 Dentistry, ISO 10477 Dentistry and ISO 10993-1, as described herein, which are also referred to herein simply as ISO 20795-1, ISO 10477 and ISO 10993-1, respectively. Modeling material formulations that are usable in the context of additive manufacturing of dental structures, according to some of the present embodiments, can comprise two or more, three or more, four or more, five or more, or all, of the components described herein as Components A, B, C, D, E, F, G and H (see, Table 1 hereinbelow), and in some of these embodiments, further comprise one or more of the components I, J, P and Dp (see, Table 1 hereinbelow).

As described in further detail hereinafter, modeling material formulations that are usable in the context of additive manufacturing of dental structures can include two types of formulations, which are referred to herein as Type B formulation and Type A formulations, as these are described herein in any of the respective embodiments and any combination thereof.

According to some of any of the embodiments described herein, a modeling material formulation comprises two or more, three or more, four or more, five or more, and preferably all, of the following components: a multi-functional (e.g., di-functional) urethane (meth)acrylate featuring, when hardened, high Tg (Component A); a multi-functional (e.g., di-functional) non-aromatic (meth) acrylate featuring, when hardened, high Tg (Component B); a filler in a form of particles, preferably sub-micron- sized particles (Component C); a multi-functional (e.g., di-functional) ethoxylated aromatic (meth)acrylate (Component D); a mono-functional (meth)acrylate (Component E); a multi-functional (e.g., tri-functional) (meth)acrylate (Component F); and a multi-functional (e.g., di-functional) aliphatic urethane (meth) acrylate featuring, when hardened, low Tg (Component G).

According to some of any of the embodiments described herein, Component A is a multifunctional (e.g., di-functional) aliphatic urethane (meth)acrylate featuring, when hardened, Tg higher than 100 °C.

According to some of any of the embodiments described herein, Component B is a multifunctional (e.g., di-functional) non-aromatic (meth)acrylate featuring, when hardened, Tg higher than 100 °C.

According to some of any of the embodiments described herein, Component C comprises micron-sized filler particles functionalized by curable groups, as described herein.

According to some of any of the embodiments described herein, Component D is a multifunctional (e.g., di-functional) ethoxylated aromatic (meth) acrylate featuring less than 10 ethoxylated groups and/or featuring, when hardened, Tg that ranges from 50 to 150 °C (Component DI) or a multi-functional (e.g., di-functional) ethoxylated aromatic (meth)acrylate featuring at least 10 ethoxylated groups and/or featuring, when hardened, Tg lower than 50 or lower than 0, °C (Component D2).

According to some of any of the embodiments described herein, Component E comprises at least one or at least two mono-functional (meth)acrylate(s).

According to some of any of the embodiments described herein, Component F is a multifunctional (e.g., tri-functional) cyclic (meth)acrylate.

According to some of any of the embodiments described herein, Component G is a multifunctional (e.g., di-functional) aliphatic urethane (meth)acrylate featuring, when hardened, low Tg, e.g., Tg lower than 100 °C.

According to some of any of the embodiments described herein, an amount of the filler (Component C) is no more than 20, or no more than 15, % by weight of the total weight of the formulation.

Component A:

According to some of any of the embodiments described herein, Component A is a multifunctional (e.g., di-functional) urethane (meth)acrylate featuring, when hardened, Tg higher than 100 °C.

According to some of any of the embodiments described herein, Component A is a multifunctional (e.g., di-functional) aliphatic urethane (meth)acrylate.

According to some of any of the embodiments described herein, Component A is a multifunctional (e.g., di-functional) aliphatic urethane (meth)acrylate featuring, when hardened, Tg higher than 100 °C, as described herein.

According to some of any of the embodiments described herein, Component A is a di- functional urethane (meth)acrylate featuring, when hardened, Tg higher than 100 °C, as described herein.

According to some of any of the embodiments described herein, Component A is a di- functional aliphatic urethane (meth)acrylate.

According to some of any of the embodiments described herein, Component A is a di- functional aliphatic urethane (meth) acrylate featuring, when hardened, Tg higher than 100 °C, as described herein.

According to some of any of the embodiments described herein, Component A is a difunctional urethane methacrylate featuring, when hardened, Tg higher than 100 °C, as described herein. According to some of any of the embodiments described herein, Component A is a difunctional aliphatic urethane methacrylate.

According to some of any of the embodiments described herein, Component A is a difunctional aliphatic urethane methacrylate featuring, when hardened, Tg higher than 100 °C, as described herein.

According to some of any of the embodiments described herein, Component A features, when hardened, Tg that ranges from 100 to 200, or from 120 to 200, or from 100 to 150, or from 120 to 150, °C, including any intermediate values and subranges therebetween.

According to some of any of the embodiments described herein, an average molecular weight of Component A is lower than 1,000 grams/mol.

Any multi-functional (e.g., di-functional) aliphatic urethane (meth)acrylate is contemplated, and preferably such materials that are acceptable for inclusion in medical devices, such as devices for long term contact in a mucosal cavity and/or in edible (e.g., food-grade) products, and/or are characterized by a toxicity profile that is considered safe for long term contact with a mucosal cavity.

An exemplary, non-limiting, material is marketed under the tradename Genomer 4297. Other urethane (meth)acrylates according to these embodiments are contemplated.

Component B:

According to some of any of the embodiments described herein, Component B is a multifunctional (e.g., di-functional) non-aromatic (meth)acrylate featuring, when hardened, high Tg, for example, Tg higher than 100 °C, as described herein.

By “non-aromatic” it is meant a material that is devoid of aryl or heteroaryl groups or moieties, as these are defined herein.

Non-aromatic materials can be, for example, aliphatic or alicyclic.

According to some of any of the embodiments described herein, Component B is a multifunctional (e.g., di-functional) alicyclic (meth) acrylate featuring, when hardened, high Tg, for example, Tg higher than 100, and is referred to herein as Component Bl.

According to some of any of the embodiments described herein, Component Bl is a di- functional alicyclic (meth)acrylate featuring, when hardened, high Tg, for example, Tg higher than 100 °C, as described herein.

According to some of any of the embodiments described herein, Component Bl is a di- functional alicyclic acrylate, or an alicyclic diacrylate, featuring, when hardened, high Tg, for example, Tg higher than 100 °C, as described herein. According to some of any of the embodiments described herein, Component B 1 comprises an alicyclic moiety of at least 6, 7, 8, 9, 10 or more carbon atoms.

According to some of any of the embodiments described herein, Component B 1 comprises an alicyclic moiety which comprises 2, 3 or more fused rings.

According to some of any of the embodiments described herein, Component B or Bl features, when hardened, Tg that ranges from 100 to 300, or from 150 to 300, or from 100 to 200, or from 150 to 200, °C, including any intermediate values and subranges therebetween.

According to some of any of the embodiments described herein, Component B is a multifunctional (e.g., di-functional) aromatic (meth)acrylate featuring, when hardened, high Tg, for example, Tg higher than 200 °C, and is referred to herein as Component B2.

According to some of any of the embodiments described herein, Component B2 is a difunctional aromatic (meth)acrylate featuring, when hardened, high Tg, for example, Tg higher than 200 °C, as described herein.

Component C:

According to embodiments of the present invention, Component C is a filler in a particulate form, comprising a plurality of particles, preferably sub-micron-sized particles.

The term “filler” as used herein describes an inert material that modifies the properties of a polymeric material and/or adjusts a quality of the end products.

Fillers (reinforcing materials) usable in additive manufacturing are typically inorganic particles of, for example, silica, calcium carbonate, clay, carbon black, and others.

In some of any of the embodiments described herein, the filler is or comprises silica particles.

In some of any of the embodiments described h, the average diameter of the filler particles (sub-micron particles) is less than 1 micron, preferably less than 500 nm, preferably less than 200 nm and preferably less than 100 nm.

In some of any of the embodiments described herein, the filler is or comprises silica particles featuring an average diameter which is less than 1 micron, preferably less than 500 nm, preferably less than 200 nm and preferably less than 100 nm. Such silica particles are referred to also as silica nanoparticles.

In some of any of the embodiments described herein, the average diameter of the particles ranges from 10 nm to 100 nm, or from 20 nm to 100 nm, or from 20 nm to 80 nm, or from 10 nm to 50 nm, including any intermediate values and subranges therebetween. In some of any of the embodiments described herein, at least a portion of such particles may aggregate, upon being introduced to the formulation. In some of these embodiments, the aggregate has an average size of no more than a few micrometers (microns).

Any commercially available formulation of sub-micron silica particles is usable in the context of the present embodiments, including fumed silica, colloidal silica, precipitated silica, layered silica (e.g., montmorillonite), and aerosol assisted self-assembly of silica particles.

The silica particles can be such that feature a hydrophobic or hydrophilic surface. The hydrophobic or hydrophilic nature of the particles’ surface is determined by the nature of the surface groups on the particles.

In a preferred embodiment, at least a portion, or all, of the silica particles are functionalized by curable functional groups (particles featuring curable groups on their surface).

The curable functional groups can be any polymerizable groups as described herein. In some embodiments, the curable functional groups are polymerizable by the same polymerization reaction as the curable monomers in the formulation, and/or when exposed to the same curing condition as the curable monomers. In some embodiments, the curable groups are photocurable (e.g., UV-curable) groups. In some embodiments, the curable groups are (meth)acrylic (acrylic or methacrylic) groups, as defined herein, preferably (meth)acrylate groups.

By “at least a portion”, as used in the context of the present embodiments, it is meant at least 10 %, or at least 20 %, or at least 30 %, or at least 40 %, or at least 50 %, or at least 60 %, or at least 70 %, or at least 80 %, or at least 90 %, or at least 95 %, or at least 98 %, of the particles.

In some embodiments, the silica particles comprise silica nanoparticles featuring acrylate and/or methacrylate groups on their surface.

According to some of any of the embodiments described herein, Component B, as described herein in any of the respective embodiments and any combination thereof, preferably Component Bl as described herein, and Component C as described herein in any of the respective embodiments, are included in the formulation as a pre-mixed composition (e.g., a dispersion of the Component C filler particles in Component B).

According to some of these embodiments, a weight ratio of Component B and Component C in the pre-mixed composition (and in a formulation comprising same) is about 1:1.

According to some of any of the embodiments described herein, a total amount of Component B (e.g., Component Bl) and Component C ranges from about 15 to about 30, or from about 15 to about 25, or from about 2- to about 25, or from about 20 to about 30, % by weight of the total weight of the formulation, including any intermediate values and subranges therebetween. Component D:

According to some of any of the embodiments described herein, Component D is a multifunctional ethoxylated (meth)acrylate.

According to some of any of the embodiments described herein, Component D is multifunctional (e.g., di-functional) ethoxylated aromatic (meth)acrylate, which comprises one or more aromatic (aryl or heteroaryl) moieties.

According to some of any of the embodiments described herein, Component D comprises a Bisphenol A moiety as a branching unit from which two or three ethoxylated moieties that terminate by (meth) acrylate groups extend.

According to some of any of the embodiments described herein, Component D is a difunctional ethoxylated aromatic (meth) acrylate.

According to some of any of the embodiments described herein, Component D is multifunctional (e.g., di-functional) ethoxylated aromatic (meth)acrylate featuring, when hardened, Tg lower than 200 °C.

According to some of any of the embodiments described herein, Component D is multifunctional (e.g., di-functional) ethoxylated aromatic (meth)acrylate featuring, when hardened, Tg that ranges from 50 to 150 °C, including any intermediate values and subranges therebetween.

According to some of any of the embodiments described herein, Component D is a di- functional ethoxylated aromatic (meth)acrylate featuring, when hardened, Tg that ranges from 50 to 150 °C, including any intermediate values and subranges therebetween.

According to some of any of the embodiments described herein, Component D is a multifunctional (e.g., di-functional) ethoxylated aromatic methacrylate featuring, when hardened, Tg that ranges from 50 to 150 °C, including any intermediate values and subranges therebetween.

According to some of any of the embodiments described herein, Component D is a di- functional ethoxylated aromatic methacrylate (ethoxylated aromatic dimethacrylate) featuring, when hardened, Tg that ranges from 50 to 150 °C, including any intermediate values and subranges therebetween.

According to some of any of the embodiments described herein, Component D comprises less than 10 ethoxylated moieties, or less than 8, or less than 6 or less than 5, ethoxylated moieties.

According to some of any of the embodiments described herein, Component D comprises a total of 4 ethoxylated moieties.

According to some of any of the embodiments described herein, Component D is a multifunctional (e.g., di-functional) ethoxylated aromatic (meth)acrylate featuring, when hardened, Tg that ranges from 50 to 150 °C, including any intermediate values and subranges therebetween and/or comprising less than 10 ethoxylated moieties, or less than 8, or less than 6 or less than 5, ethoxylated moieties, for example, 4 ethoxylated moieties. Such a component is referred to herein as Component DI.

According to some of any of the embodiments described herein, Component DI is a multifunctional (e.g., di-functional) ethoxylated aromatic (meth)acrylate featuring, when hardened, Tg that ranges from 50 to 150 °C, including any intermediate values and subranges therebetween and comprises less than 10 ethoxylated moieties, or less than 8, or less than 6 or less than 5, ethoxylated moieties, for example, 4 ethoxylated moieties.

According to some of any of the embodiments described herein, Component DI is a difunctional ethoxylated aromatic (meth)acrylate featuring, when hardened, Tg that ranges from 50 to 150 °C, including any intermediate values and subranges therebetween and comprises less than 10 ethoxylated moieties, or less than 8, or less than 6 or less than 5, ethoxylated moieties, for example, 4 ethoxylated moieties.

According to some of any of the embodiments described herein, Component DI is a multifunctional (e.g., di-functional) ethoxylated aromatic methacrylate featuring, when hardened, Tg that ranges from 50 to 150 °C, including any intermediate values and subranges therebetween and comprises less than 10 ethoxylated moieties, or less than 8, or less than 6 or less than 5, ethoxylated moieties, for example, 4 ethoxylated moieties.

According to some of any of the embodiments described herein, Component DI is a di- functional ethoxylated aromatic methacrylate featuring, when hardened, Tg that ranges from 50 to 150 °C, including any intermediate values and subranges therebetween and comprises less than 10 ethoxylated moieties, or less than 8, or less than 6 or less than 5, ethoxylated moieties, for example, 4 ethoxylated moieties.

An exemplary Component DI is, without limitation, such as marketed under the tradename SR-540, yet, any other materials are contemplated.

According to some of any of the embodiments described herein, Component D is a multifunctional (e.g., di-functional) ethoxylated aromatic (meth) acrylate featuring, when hardened, lower Tg, for example, Tg lower than 50, lower than 20, or lower than 0, °C, for example, Tg of from -100 to 50, or from -100 to 0, or from -100 to -20, or from -20 to 0, °C, including any intermediate values and subranges therebetween and/or comprising at least 10, or at least 15, or at least 20, or at least 25, or at least 30, ethoxylated moieties, for example, from 10 to 50, or from 20 to 50, or from 20 to 40, or from 25, to 35, ethoxylated moieties, including any intermediate values and subranges therebetween, for example about 30 ethoxylated moieties. Such a component is referred to herein as Component D2. According to some of any of the embodiments described herein, Component D2 is a multifunctional (e.g., di-functional) ethoxylated aromatic (meth)acrylate featuring, when hardened, Tg lower than 50 or lower than 0 °C, as described herein, and comprises at least 10, or at least 15, or at least 20, or at least 25, or at least 30, ethoxylated moieties, for example, from 10 to 50, or from 20 to 50, or from 20 to 40, or from 25, to 35, ethoxylated moieties, including any intermediate values and subranges therebetween, for example about 30 ethoxylated moieties

According to some of any of the embodiments described herein, Component D2 is a difunctional ethoxylated aromatic (meth)acrylate featuring, when hardened, Tg lower than 50 or lower than 0 °C, as described herein, and comprises at least 10, or at least 15, or at least 20, or at least 25, or at least 30, ethoxylated moieties, for example, from 10 to 50, or from 20 to 50, or from 20 to 40, or from 25, to 35, ethoxylated moieties, including any intermediate values and subranges therebetween, for example about 30 ethoxylated moieties

According to some of any of the embodiments described herein, Component D2 is a multifunctional (e.g., di-functional) ethoxylated aromatic methacrylate featuring, when hardened, Tg lower than 50 or lower than 0 °C, as described herein, and comprises at least 10, or at least 15, or at least 20, or at least 25, or at least 30, ethoxylated moieties, for example, from 10 to 50, or from 20 to 50, or from 20 to 40, or from 25, to 35, ethoxylated moieties, including any intermediate values and subranges therebetween, for example about 30 ethoxylated moieties

According to some of any of the embodiments described herein, Component D2 is a di- functional ethoxylated aromatic methacrylate featuring, when hardened, Tg lower than 50 or lower than 0 °C, as described herein, and comprises at least 10, or at least 15, or at least 20, or at least 25, or at least 30, ethoxylated moieties, for example, from 10 to 50, or from 20 to 50, or from 20 to 40, or from 25, to 35, ethoxylated moieties, including any intermediate values and subranges therebetween, for example about 30 ethoxylated moieties

An exemplary Component D2 is, without limitation, such as marketed under the tradename SR9036A, yet, any other materials are contemplated.

Component E:

According to some of any of the embodiments described herein, Component E comprises one or more mono-functional (meth)acrylate materials.

According to some of any of the embodiments described herein, Component E comprises two or more mono-functional (meth) acrylate materials.

According to some of any of the embodiments described herein, Component E comprises two or more mono-functional (meth)acrylate materials, at least one is a mono -functional methacrylate, also referred to herein as Component El, and at least one is a mono-functional acrylate, also referred to herein as Component E2 or E3. Optionally, Component E2 is or comprises a mono-functional alicyclic acrylate, which comprises one or more alicyclic moieties that are attached directly or indirectly to the acrylate moiety. Component E2 can be amphiphilic, hydrophilic or hydrophobic, and is preferably amphiphilic or hydrophobic.

According to some of any of the embodiments described herein, at least one, or each, of Components El, E2 and E3, is a hydrophilic and/or an amphiphilic material.

As used herein throughout, the term “hydrophilic” describes a physical property of a material or a portion of a material (e.g., a chemical group in a compound) which accounts for transient formation of bond(s) with water molecules, typically through hydrogen bonding.

Hydrophilic materials dissolve more readily in water than in oil or other hydrophobic solvents. Hydrophilic materials can be determined, for example, as having LogP lower than 0.5, when LogP is determined in octanol and water phases at room temperature.

Hydrophilic materials can alternatively, or in addition, be determined as featuring a lipophilicity/hydrophilicity balance (HLB), according to the Davies method, of at least 10, or of at least 12.

As used herein throughout, the term “amphiphilic” describes a property of a material that combines both hydrophilicity, as described herein for hydrophilic materials, and hydrophobicity or lipophilicity, as defined herein for hydrophobic materials.

Amphiphilic materials typically comprise both hydrophilic groups as defined herein and hydrophobic groups, as defined herein, and are substantially soluble in both water and a water- immiscible solvent (oil).

Amphiphilic materials can be determined by, for example, as having LogP of 0.8 to 1.2, or of about 1, when LogP is determined in octanol and water phases at room temperature.

Amphiphilic materials can alternatively, or in addition, be determined as featuring a lipophilicity/hydrophilicity balance (HLB), according to the Davies method, of 3 to 12, or 3 to 9.

As used herein throughout, the term “hydrophobic” describes a physical property of a material or a portion of a material (e.g., a chemical group in a compound) which does not form bond(s) with water molecules. Hydrophobic materials dissolve more readily in oil than in water. Hydrophobic materials can be determined, for example, as having LogP higher than 1, preferably higher than 2, when LogP is determined in octanol and water phases.

A hydrophilic material or portion of a material (e.g., a chemical group in a compound) is one that is typically charge -polarized and capable of hydrogen bonding.

Amphiphilic materials typically comprise one or more hydrophilic groups (e.g., a charge- polarized group), in addition to hydrophobic groups. Hydrophilic materials or groups, and amphiphilic materials, typically include one or more electron-donating heteroatoms which form strong hydrogen bonds with water molecules. Such heteroatoms include, but are not limited to, oxygen and nitrogen. Preferably, a ratio of the number of carbon atoms to a number of heteroatoms in a hydrophilic materials or groups is 10:1 or lower, and can be, for example, 8:1, more preferably 7:1, 6:1, 5:1 or 4:1, or lower. It is to be noted that hydrophilicity and amphiphilicity of materials and groups may result also from a ratio between hydrophobic and hydrophilic moieties in the material or chemical group, and does not depend solely on the above-indicated ratio.

A hydrophilic or amphiphilic material can have one or more hydrophilic groups or moieties. Hydrophilic groups are typically polar groups, comprising one or more electron-donating heteroatoms such as oxygen and nitrogen.

Exemplary hydrophilic groups include, but are not limited to, an electron-donating heteroatom, a carboxylate, a thiocarboxylate, oxo (=0), a linear amide, hydroxy, a (Cl-4)alkoxy, an (Cl-4)alcohol, a heteroalicyclic (e.g., having a ratio of carbon atoms to heteroatoms as defined herein), a cyclic carboxylate such as lactone, a cyclic amide such as lactam, a carbamate, a thiocarbamate, a cyanurate, an isocyanurate, a thiocyanurate, urea, thiourea, an alkylene glycol (e.g., ethylene glycol or propylene glycol), and a hydrophilic polymeric or oligomeric moiety, as these terms are defined hereinunder, and any combinations thereof (e.g., a hydrophilic group that comprises two or more of the indicated hydrophilic groups).

In some embodiments, the hydrophilic group is, or comprises, an electron donating heteroatom, a carboxylate, a heteroalicyclic, an alkylene glycol and/or a hydrophilic oligomeric moiety.

An amphiphilic moiety or group typically comprises one or more hydrophilic groups as described herein and one or more hydrophobic groups, or, can a heteroatom-containing group or moiety in which the ratio of number of carbon atoms to the number of heteroatoms accounts for amphiphilicity.

A hydrophilic or amphiphilic mono-functional curable material according to some embodiments of the present invention can be a hydrophilic acrylate represented by Formula Al:

Formula Al wherein Ri and R2 are as defined herein and at least one of Ri and R2 is and/or comprises a hydrophilic or amphiphilic moiety or group, as defined herein.

In some of any of these embodiments, the carboxylate group, -C(=O)-ORa, comprises Ra which is a hydrophilic or amphiphilic moiety or group, as defined herein. Exemplary Ra groups in the context of these embodiments include, but are not limited to, heteroalicyclic groups (having a ratio of 10:1 or 8:1 or 6:1 or 5:1 or lower of carbon atoms to electron-donating heteroatoms, such as morpholine, tetrahydrofurane, oxalidine, and the likes), hydroxyl, C(l-4)alkoxy, thiol, alkylene glycol or a hydrophilic or amphiphilic polymeric or oligomeric moiety, as described herein.

Exemplary hydrophilic or amphiphilic oligomeric mono-functional curable materials include, but are not limited to, a mono-(meth)acrylated urethane oligomer derivative of polyethylene glycol, a mono-(meth)acrylated polyol oligomer, a mono-(meth)acrylated oligomer having hydrophilic substituents, a mono-(meth)acrylated polyethylene glycol (e.g., methoxypolyethylene glycol), and a mono urethane acrylate.

According to some of any of the embodiments described herein, Component El is a hydrophilic or amphiphilic mono-functional methacrylate.

According to some of any of the embodiments described herein, Component E2 is a monofunctional acrylate, and in some embodiments, it is a mono-functional acrylate that has an alicyclic group as Ra in Formula Al.

According to some of any of the embodiments described herein, Component El is a hydrophilic or amphiphilic mono-functional methacrylate and Component E2 is a mono-functional acrylate, and in some embodiments, it is a mono-functional acrylate that has an alicyclic group as Ra in Formula Al.

Exemplary materials that are usable as Component El include, without limitation, methacrylates featuring hydroxyalkyl groups, such as, for example, marketed under the tradename BISOMEROHPMA.

Exemplary materials that are usable as Component E2 include, without limitation, acrylates featuring mono-cyclic or bi-cyclic hydrocarbon groups (cycloalkyl), such as, for example, marketed under the tradename Genomer 1120, SR-789 and SR-420.

Component E3 is or comprises a mono-functional acrylate that is hydrophilic or amphiphilic, and is preferably water-soluble as described herein, which can be aliphatic or alicyclic. In exemplary embodiments, Component E3 is a hydrophilic heteroalicyclic acrylate. An exemplary hydrophilic monomeric mono-functional acrylate is acryloyl morpholine (ACMO).

According to some of any of the embodiments described herein, each of the monofunctional materials (Components El, E2 and E3) has an average molecular weight lower than 1,000 grams/mol or lower than 500 grams/mol, for example, of from 100 to 500 grams/mol, or from 100 to 400, or from 100 to 300, grams/mol, including any intermediate values and subranges therebetween.

According to some of any of any of the embodiments described herein, Component E is included in the formulation, inter alia, for balancing properties such as reactivity and/or viscosity, and Components El, E2 and/or E3, and a ratio thereof, are selected accordingly.

According to some of any of the embodiments described herein, when two or more of Components El, E2 and E3 are included in a formulation as described herein, a weight ratio between each two components can range, for example, from 1:5 to 5:1, or from 3:1 to 1:3, or from 2:1 to 1:2, including any intermediate values and subranges therebetween.

According to some of any of the embodiments described herein, at least Components El and E2 are included in a formulation as described herein.

According to some of any of the embodiments described herein, a weight ratio of the monofunctional methacrylate (Component El) and the mono-functional acrylate (Component E2), when both are included in a formulation as described herein, ranges from 2:1 to 1:2.

According to some of any of the embodiments described herein, at least one or all of the mono-functional alicyclic acrylate (Component E2), the mono-functional methacrylate (Component El), and the hydrophilic or amphiphilic mono-functional acrylate (Component E3), features, when hardened, Tg lower than 100 °C or lower than 80 °C.

According to some of any of the embodiments described herein, the mono-functional alicyclic acrylate (Component E2) features, when hardened, Tg lower than 100 °C or lower than 80 °C.

According to some of any of the embodiments described herein, the mono-functional methacrylate (Component El), features, when hardened, Tg lower than 100 °C or lower than 80 °C.

Component F:

According to some of any of the embodiments describes herein, Component F is a trifunctional (meth)acrylate.

According to some of any of the embodiments describes herein, Component F is a multifunctional (e.g., tri-functional) (meth) acrylate that features, when hardened, Tg higher than 150, or higher than 180, or higher than 200, °C.

According to some of any of the embodiments describes herein, Component F is a multifunctional (e.g., tri-functional) cyclic (meth)acrylate, which comprises one or more cyclic moieties such as aryl and/or alicyclic, and is also referred to herein as Component Fl. According to some of any of the embodiments describes herein, Component Fl is a trifunctional cyclic (meth)acrylate, which comprises one or more cyclic moieties such as aryl and/or alicyclic.

According to some of any of the embodiments describes herein, Component Fl is a trifunctional cyclic methacrylate, or cyclic trimethacrylate, which comprises one or more cyclic moieties such as aryl and/or alicyclic.

According to some of any of the embodiments described herein, Component F or Fl features, when hardened, high Tg, for example, Tg higher than 100, or higher than 150, or higher than 200, or even higher than 250, °C.

According to some of any of the embodiments describes herein, Component Fl is a trifunctional cyclic methacrylate, or cyclic trimethacrylate, which comprises one or more cyclic moieties such as aryl and/or alicyclic, and features, when hardened, high Tg, for example, Tg higher than 100, or higher than 150, or higher than 200, or even higher than 250, °C.

In some of any of the embodiments of Component F or Fl, the cyclic moiety is a branching unit as defined herein.

In some of any of the embodiments of Component F or Fl, the cyclic moiety is or comprises a cyanurate or an isocyanurate.

In some of any of the embodiments of Component F or Fl, the cyclic moiety is or comprises a cyanurate or an isocyanurate and is a branching unit, from which moieties that comprise the (meth)acrylate groups extend. An exemplary such material is, without limitation, marketed under the tradename SR-368.

Component G:

According to some of any of the embodiments described herein, Component G is a multifunctional (e.g., di-functional) aliphatic urethane (meth)acrylate, featuring low Tg and, optionally and preferably, having an average MW of at least 1,000 grams/mol, for example, of from 1,000 to 10,000 grams/mol, including any intermediate values and subranges therebetween. Such a component is also referred to herein as an oligomeric curable material.

According to some of any of the embodiments described herein, Component G is a difunctional aliphatic urethane (meth)acrylate, having an average MW of at least 1,000 grams/mol, for example, of from 1,000 to 10,000 grams/mol, including any intermediate values and subranges therebetween. According to some of any of the embodiments described herein, Component G (including Component G1 and Component G2) is an oligomeric di-functional aliphatic urethane (meth)acrylate. According to some of any of the embodiments described herein, Component G is a multifunctional (e.g., di-functional) aliphatic urethane methacrylate, having an average MW of at least 1,000 grams/mol, for example, of from 1,000 to 10,000 grams/mol, including any intermediate values and subranges therebetween.

According to some of any of the embodiments described herein, Component G is a difunctional aliphatic urethane methacrylate, having an average MW of at least 1,000 grams/mol.

According to some of any of the embodiments described herein, Component G is a difunctional aliphatic urethane acrylate, having an average MW of at least 1,000 grams/mol.

According to some of any of the embodiments described herein, Component G features, when hardened, low Tg.

According to some of any of the embodiments described herein, Component G features, when hardened, Tg lower than 100 °C or lower than 80 °C.

According to some of any of the embodiments described herein, Component G is a nonpolar (e.g., non-hydrophilic or hydrophobic) multi-functional (e.g., di-functional) aliphatic urethane (meth) acrylate as described herein.

According to some of any of the embodiments described herein, Component G is a multifunctional (e.g., di-functional) aliphatic urethane (meth)acrylate, featuring Tg lower than 0 °C, for example, of from -100 to 0, or from -100 to 20 °C, , including any intermediate values and subranges therebetween, and, optionally and preferably, having an average MW of at least 1,000 grams/mol, for example, of from 1,000 to 10,000 grams/mol, including any intermediate values and subranges therebetween. Such a component is also referred to herein as Component Gl.

According to some of any of the embodiments described herein, Component Gl is a di- functional aliphatic urethane (meth)acrylate, featuring Tg lower than 0 °C, for example, of from - 100 to 0, or from -100 to -20 °C, including any intermediate values and subranges therebetween, and having an average MW of at least 1,000 grams/mol, for example, of from 1,000 to 10,000 grams/mol, including any intermediate values and subranges therebetween.

According to some of any of the embodiments described herein, Component Gl is a multifunctional (e.g., di-functional) aliphatic urethane acrylate, featuring Tg lower than 0 °C, for example, of from -100 to 0, or from -100 to -20 °C, including any intermediate values and subranges therebetween, and having an average MW of at least 1,000 grams/mol, for example, of from 1,000 to 10,000 grams/mol, including any intermediate values and subranges therebetween.

According to some of any of the embodiments described herein, Component Gl is a di- functional aliphatic urethane acrylate, featuring Tg lower than 0 °C, for example, of from -100 to 0, or from -100 to -20 °C, including any intermediate values and subranges therebetween, having an average MW of at least 1,000 grams/mol, or at least 2,000 grams/mol, or at least 3,000 grams/mol, for example, of from 3,000 to 10,000 or from 3,000 to 8,000, grams/mol, including any intermediate values and subranges therebetween.

An exemplary Component G1 is marketed under the tradename CN9002, yet, any other materials are contemplated.

According to some of any of the embodiments described herein, Component G is a multifunctional (e.g., di-functional) aliphatic urethane (meth)acrylate, featuring Tg lower than 100 °C, for example, of from 0 to 100, or from 0 to 50, or from 0 to 20, or from -20 to 50, or from -20 to 20, °C, including any intermediate values and subranges therebetween, and, optionally and preferably, having an average MW of at least 1,000 grams/mol, for example, of from 1,000 to 10,000 grams/mol, including any intermediate values and subranges therebetween. Such a component is also referred to herein as Component G2.

According to some of any of the embodiments described herein, Component G2 is a difunctional aliphatic urethane (meth)acrylate, featuring Tg lower than 100 °C, for example, of from 0 to 100, or from 0 to 50, or from 0 to 20, or from -20 to 50, or from -20 to 20, °C, including any intermediate values and subranges therebetween, and having an average MW of at least 1,000 grams/mol, for example, of from 1,000 to 10,000 grams/mol, including any intermediate values and subranges therebetween.

According to some of any of the embodiments described herein, Component G2 is a multifunctional (e.g., di-functional) aliphatic urethane methacrylate, featuring Tg lower than 100 °C, for example, of from 0 to 100, or from 0 to 50, or from 0 to 20, or from -20 to 50, or from -20 to 20, °C, including any intermediate values and subranges therebetween, having an average MW of at least 1,000 grams/mol, for example, of from 1,000 to 10,000 grams/mol, including any intermediate values and subranges therebetween.

According to some of any of the embodiments described herein, Component G2 is a di- functional aliphatic urethane methacrylate, featuring Tg lower than 100 °C, for example, of from 0 to 100, or from 0 to 50, or from 0 to 20, or from -20 to 50, or from -20 to 20, °C, including any intermediate values and subranges therebetween, having an average MW of at least 1,000 grams/mol, for example, of from 1,000 to 5,000 or from 1,000 to 3,000, grams/mol, including any intermediate values and subranges therebetween.

An exemplary Component G2 is marketed under the tradename CN1970EU, yet, any other materials are contemplated. Component H

According to some of any of the embodiments described herein, the modeling material formulation further comprises a dispersant (Component H).

According to some of these embodiments, the dispersant features curable groups, preferably (meth)acrylic groups.

According to some of any of the embodiments described herein, the dispersant is a multifunctional (e.g., di-functional) aliphatic silicon (meth)acrylate.

According to some of any of the embodiments described herein, the dispersant is a difunctional aliphatic silicon (meth)acrylate.

According to some of any of the embodiments described herein, the dispersant is a multifunctional (e.g., di-functional) aliphatic silicon acrylate.

According to some of any of the embodiments described herein, the dispersant is a di- functional aliphatic silicon acrylate.

According to some of any of the embodiments described herein, the dispersant has an average MW of at least 1,000, or at least 2,000, or at least 3,000 grams/mol, and is considered as an oligomeric material.

According to some of any of the embodiments described herein, the dispersant is a multifunctional (e.g., di-functional) aliphatic silicon (meth)acrylate, having an average MW of at least 1,000 grams/mol as described herein.

According to some of any of the embodiments described herein, the dispersant is a di- functional aliphatic silicon (meth)acrylate, having an average MW of at least 1,000 grams/mol as described herein.

According to some of any of the embodiments described herein, the dispersant is a multifunctional (e.g., di-functional) aliphatic silicon acrylate, having an average MW of at least 1,000 grams/mol as described herein.

According to some of any of the embodiments described herein, the dispersant is a di- functional aliphatic silicon acrylate, having an average MW of at least 1,000 grams/mol as described herein.

According to some of any of the embodiments described herein, the dispersant features, when hardened, low Tg, preferably lower than 0, or lower than -20, or lower than -50, °C.

According to some of any of the embodiments described herein, an amount of the dispersant ranges from 0.1 to 1 or from 0.1 0.5, % by weight, of the total weight of the formulation, including any intermediate values and subranges therebetween. Additional Components:

According to some of any of the embodiments described herein, the modeling material formulation further comprises a polymerization inhibitor (Component I), as described herein, for example, a phenol-type inhibitor or any other inhibitor that is commonly used in medical devices or applications and/in food products.

According to some of any of the embodiments described herein, an amount of the inhibitor ranges from 0.001 to 0.010, % by weight, of the total weight of the formulation, including any intermediate values and subranges therebetween.

According to some of any of the embodiments described herein, the modeling material formulation further comprises at least one photoinitiator (Component J).

According to some of any of the embodiments described herein, an amount of the photoinitiator ranges from 1 to 5, % by weight of the total weight of the formulation, including any intermediate values and subranges therebetween.

According to some of any of the embodiments described herein, the photoinitiator(s) comprises, or consists essentially of, a phosphine oxide-type (e.g., mono-acrylated (MAPO) or bis- acrylated phosphine oxide-type (BAPO) photoinitiator.

Exemplary monoacyl and bisacyl phosphine oxides include, but are not limited to, 2,4,6- trimethylbenzoyldiphenyl phosphine oxide, bis(2,4,6-trimethylbenzoyl) phenylphosphine oxide, dibenzoylphenylphosphine oxide, bis(2,6-dimethoxybenzoyl)phenyl phosphine oxide, tris(2,4- dimethylbenzoyl) phosphine oxide, tris(2-methoxybenzoyl)phosphine oxide, 2,6- dimethoxybenzoyldiphenyl phosphine oxide, 2,6-dichlorobenzoyldiphenyl phosphine oxide, 2,3,5,6-tetramethylbenzoyldiphenyl phosphine oxide, benzoyl-bis(2,6-dimethylphenyl) phosphonate, and 2,4,6-trimethylbenzoylethoxyphenyl phosphine oxide. Commercially available phosphine oxide photoinitiators capable of free-radical initiation when irradiated at wavelength ranges of greater than about 380 nm to about 450 nm include 2,4,6-trimethylbenzoyldiphenyl phosphine oxide (TPO), bis(2,4,6-trimethylbenzoyl)phenyl phosphine oxide (marketed as IRGACURE® 819), bis(2,6-dimethoxybenzoyl)-(2,4,4-trimethylpentyl) phosphine oxide (marketed as CGI 403), a 25:75 mixture, by weight, of bis(2,6-dimethoxybenzoyl)-2,4,4- trimethylpentyl phosphine oxide and 2-hydroxy-2-methyl-l-phenylpropan-l-one (marketed as IRGACURE® 1700), a 1:1 mixture, by weight, of bis(2,4,6-trimethylbenzoyl)phenyl phosphine oxide and 2-hydroxy-2-methyl-l -phenylpropane- 1 -one (marketed as DAROCUR® 4265), and ethyl 2,4,6-trimethylbenzylphenyl phosphinate (LUCIRIN LR8893X).

In an exemplary embodiments, the photoinitiator is or comprises bis(2,4,6- trimethylbenzoyl)phenyl phosphine oxide (marketed as IRGACURE® 819). In an exemplary embodiments, the photoinitiator is devoid of 2,4,6- trimethylbenzoyldiphenyl phosphine oxide (marketed as TPO) and/or bis(2,4,6- trimethylbenzoyl)phenyl phosphine oxide (marketed as IRGACURE® 819).

According to some of any of the embodiments described herein, the modeling material formulation is a clear (e.g., transparent), colorless formulation, which is devoid of a coloring agent.

According to some of any of the embodiments described herein, the modeling material formulation further comprises one or more coloring agent(s) (Component P).

The coloring agent can be a pigment or a dye and is preferably a pigment.

The pigments can be organic and/or inorganic and/or metallic pigments, and in some embodiments the pigments are nanoscale pigments, which include nanoparticles.

Exemplary inorganic pigments include nanoparticles of titanium oxide, and/or of zinc oxide and/or of silica. Exemplary organic pigments include nano- sized carbon black.

In some embodiments, combinations of white and color pigments are used to prepare colored cured materials.

According to some of any of the embodiments described herein, the coloring agent comprises a mixture of a pigment and at least one (meth)acrylic material, such that the pigment is introduced to the formulation within this mixture.

According to some of any of the embodiments described herein, the pigment is a white pigment and the formulation provides a white hardened material.

According to some of any of the embodiments described herein, the coloring agent comprises a mixture of a white pigment and one or more curable materials such as (meth)acrylic materials, such that the pigment is introduced to the formulation within this mixture.

According to some of these embodiments, an amount of the white pigment in the mixture ranges from 20 to 50 % by weight of the total weight of the mixture, including any intermediate values and subranges therebetween.

According to some of these embodiments, an amount of the coloring agent, which is a mixture of a white pigment and at least one (meth)acrylic material ranges from 1 to 5 % by weight of the total weight of the formulation, including any intermediate values and subranges therebetween.

According to some of any of the embodiments described herein, the pigment is a cyan pigment and the formulation provides a cyan hardened material.

According to some of any of the embodiments described herein, the coloring agent comprises a mixture of a cyan pigment and one or more curable materials such as (meth)acrylic materials, such that the cyan pigment is introduced to the formulation within this mixture. According to some of these embodiments, an amount of the cyan pigment in the mixture ranges from 0.01 to 1, or from 0.05 to 0.5, or from 0.1 to 0.2, % by weight of the total weight of the mixture.

According to some of these embodiments, an amount of the coloring agent, which is a mixture of a cyan pigment and at least one (meth)acrylic material ranges from 0.1 to 1 % by weight of the total weight of the formulation, including any intermediate values and subranges therebetween.

According to some of any of the embodiments described herein, the pigment is a yellow pigment and the formulation provides a yellow hardened material.

According to some of any of the embodiments described herein, the coloring agent comprises a mixture of a yellow pigment and one or more curable materials such as (meth)acrylic materials, such that the yellow pigment is introduced to the formulation within this mixture.

According to some of these embodiments, an amount of the yellow pigment in the mixture ranges from 0.01 to 1, or from 0.05 to 0.5, or from 0.1 to 0.2, % by weight of the total weight of the mixture, including any intermediate values and subranges therebetween.

According to some of these embodiments, an amount of the coloring agent, which is a mixture of a yellow pigment and at least one (meth)acrylic material ranges from 0.1 to 1 % by weight of the total weight of the formulation, including any intermediate values and subranges therebetween.

According to some of any of the embodiments described herein, the pigment is a magenta pigment and the formulation provides a magenta hardened material.

According to some of any of the embodiments described herein, the coloring agent comprises a mixture of a magenta pigment and one or more curable materials such as (meth)acrylic materials, such that the magenta pigment is introduced to the formulation within this mixture.

According to some of these embodiments, an amount of the magenta pigment in the mixture ranges from 0.01 to 1, or from 0.05 to 0.5, or from 0.1 to 0.2, % by weight of the total weight of the mixture, including any intermediate values and subranges therebetween.

According to some of these embodiments, an amount of the coloring agent, which is a mixture of a magenta pigment and at least one (meth)acrylic material ranges from 0.1 to 1 % by weight of the total weight of the formulation, including any intermediate values and subranges therebetween.

According to some of any of the embodiments described herein, the formulation comprises one or more of a white, magenta, cyan, and yellow coloring agents, and in some of these embodiments, each pigment is introduced to the formulation in a mixture with curable materials as described herein.

According to some of any of the embodiments described herein, the coloring agent further comprises a pigment dispersant (Component Dp). Preferred pigment dispersants are such that have a plurality of groups that feature an affinity to the pigment.

According to some of any of the embodiments described herein, the modeling material formulation comprises Components H, I, and J, as described herein in any of the respective embodiments. An exemplary such a formulation is a clear colorless formulation, which is devoid of a coloring agent (devoid of Component P as described herein).

According to some of any of the embodiments described herein, the modeling material formulation comprises Components H, I, J and P, as described herein in any of the respective embodiments. An exemplary such a formulation is a white formulation that comprises a white pigment as described herein.

According to some of any of the embodiments described herein, the modeling material formulation comprises Components H, I, J, P and Dp, as described herein in any of the respective embodiments. Exemplary such formulations are the cyan, magenta and yellow formulations as described herein.

Table 1

(Table 1; Cont.)

Type B modeling material formulation:

According to some of any of the embodiments described herein, a Type B formulation comprises multi-functional (meth) acrylate materials that feature relatively high MW (e.g., higher than 1,000 grams/mol; oligomeric materials) and relatively low Tg (e.g., lower than 100 °C), such as, for example, Components D2, G1 and G2 as described herein, combined with mono-functional materials such Component E (e.g., Component El, E2 and/or E3), and optionally and preferably Component H as described herein in any of the respective embodiments.

According to some of any of the embodiments described herein, the Type B formulation comprises Component D2, Component G, preferably Component G2, and a mixture of two or more of Components El, E2 and E3.

According to some of any of the embodiments described herein, a Type B formulation comprises: at least one multi-functional (e.g., di-functional) ethoxylated aromatic (meth) acrylate featuring at least 10 ethoxylated groups and/or Tg lower than 0 °C (Component D2); at least one multi-functional (e.g., di-functional) urethane (meth)acrylate featuring Tg lower than 100 °C (Component G); at least one mono-functional alicyclic (meth)acrylate, preferably a mono-functional alicyclic acrylate (Component E2); optionally at least one mono-functional acrylate (Component E3), preferably hydrophilic or amphiphilic; and at least one dispersant (Component H).

According to some embodiments, the formulation comprises at least one multi-functional (e.g., di-functional) ethoxylated aromatic (meth) acrylate featuring at least 10 ethoxylated groups and/or Tg lower than 0 °C (Component D2); and at least one multi-functional (e.g., di-functional) urethane (meth) acrylate featuring Tg lower than 100 °C (Component G), preferably Component G2 as described herein, in a total amount (of Component D2 and Component G) of from 20 to 50, or from 30 to 50, or from 35 to 45, % by weight of the total weight of the formulation, including any intermediate values and subranges therebetween.

According to some of any of the embodiments described herein, the formulation further comprises a mixture of two or more of Components E2 and E3, and in some of these embodiments, this mixture is in a total amount of from 40 to 60, or from 45 to 60, or from 50 to 60, % by weight of the total weight of the formulation, including any intermediate values and subranges therebetween.

According to some embodiments, the formulation comprises: at least one multi-functional (e.g., di-functional) ethoxylated aromatic (meth) acrylate featuring at least 10 ethoxylated groups and/or Tg lower than 0 °C (e.g., Component D2); at least one multi-functional (e.g., di-functional) urethane (meth)acrylate featuring Tg lower than 100 °C (e.g., Component G); at least one mono-functional alicyclic (meth)acrylate (e.g., Component E2), preferably a mono-functional alicyclic acrylate; at least one mono-functional acrylate (e.g., Component E3), preferably hydrophilic or amphiphilic; and at least one dispersant (e.g., Component H).

According to some of any of the embodiments described herein, the formulation comprises: at least one multi-functional (e.g., di-functional) ethoxylated aromatic (meth) acrylate featuring at least 10 ethoxylated groups and/or Tg lower than 0 °C, (e.g., Component D2) in a total amount of from 15 to 25 % by weight, of the total weight of the formulation, including any intermediate values and subranges therebetween; at least one multi-functional (e.g., di-functional) urethane (meth)acrylate featuring Tg lower than 100 °C (e.g., Component G), in a total amount of from 15 to 25 % by weight, of the total weight of the formulation, including any intermediate values and subranges therebetween; at least one mono-functional alicyclic (meth)acrylate, preferably a mono-functional alicyclic acrylate (e.g., Component E2), in a total amount of at least 40, or at least 45, or of from 45 to 55, % by weight, of the total weight of the formulation, including any intermediate values and subranges therebetween; at least one mono-functional acrylate, preferably hydrophilic or amphiphilic (e.g.,

Component E3), in a total amount of from 3 to 10, or from 5 to 10, or from 3 to 8, % by weight, of the total weight of the formulation, including any intermediate values and subranges therebetween; and at least one dispersant (e.g., Component H), as described herein in any of the respective embodiments.

According to some of any of the embodiments described herein, the formulation comprises: at least one multi-functional (e.g., di-functional) ethoxylated aromatic (meth) acrylate featuring at least 10 ethoxylated groups and/or Tg lower than 0 °C (Component D2), in a total amount of from 15 to 25 % by weight, of the total weight of the formulation, including any intermediate values and subranges therebetween; at least one multi-functional (e.g., di-functional) urethane (meth)acrylate featuring Tg lower than 100 °C (Component G), in a total amount of from 15 to 25 % by weight, of the total weight of the formulation, including any intermediate values and subranges therebetween; at least one mono-functional alicyclic (meth)acrylate, preferably a mono-functional alicyclic acrylate (Component E2), in a total amount of at least 40, or at least 45, or of from 45 to 55, % by weight, of the total weight of the formulation, including any intermediate values and subranges therebetween; at least one mono-functional acrylate (Component E3), preferably hydrophilic or amphiphilic, in a total amount of from 3 to 10, or from 5 to 10, or from 3 to 8, % by weight, of the total weight of the formulation, including any intermediate values and subranges therebetween; and at least one dispersant (Component H).

According to some of any of the embodiments described herein for Type B formulation, the formulation comprises:

Component D2, as described herein in any of the respective embodiment and any combination thereof, in a total amount of from 15 to 25 % by weight, of the total weight of the formulation, including any intermediate values and subranges therebetween;

Component G, preferably Component G2, as described herein in any of the respective embodiment and any combination thereof, in a total amount of from 15 to 25 % by weight, of the total weight of the formulation, including any intermediate values and subranges therebetween; at least one, or at least two of Component E2, as described herein in any of the respective embodiment and any combination thereof, in a total amount of at least 40, or at least 45, or of from 45 to 55, % by weight, of the total weight of the formulation, including any intermediate values and subranges therebetween; at least one Component E3, as described herein in any of the respective embodiment and any combination thereof, in a total amount of from 3 to 10, or from 5 to 10, or from 3 to 8, % by weight, of the total weight of the formulation, including any intermediate values and subranges therebetween; and at least one dispersant, as described herein in any of the respective embodiment and any combination thereof, preferably in a total amount of from 0.1 to 1 or from 0.1 to 0.5, % by weight of the total weight of the formulation, including any intermediate values and subranges therebetween.

According to some of any of the embodiments described herein for the Type B formulation, Component D2 comprises a multi-functional (e.g., di-functional) ethoxylated aromatic (meth)acrylate featuring at least 10 ethoxylated groups and Tg lower than 0 °C features, when hardened, Tg lower than 0 °C.

According to some of any of the embodiments described herein for the Type B formulation, Component D2 has a molecular weight of at least 1,000 grams/mol.

According to some of any of the embodiments described herein for the Type B formulation, Component D2 is a multi-functional (e.g., di-functional) ethoxylated aromatic methacrylate featuring at least 10 ethoxylated groups.

According to some of any of the embodiments described herein for the Type B formulation, Component D2 comprises a multi-functional (e.g., di-functional) ethoxylated aromatic methacrylate featuring at least 10 ethoxylated groups, features, when hardened, Tg lower than 0 °C, and has a molecular weight of at least 1,000 grams/mol.

According to some of any of the embodiments described herein for the Type B formulation, Component G comprises or consists of a multi-functional (e.g., di-functional) urethane (meth)acrylate having a molecular weight of at least 1,000 grams/mol.

According to some of any of the embodiments described herein for the Type B formulation, Component G features Tg lower than 100 °C, preferably Tg that ranges from 0 to 100, or from 50 to 100, °C, including any intermediate values and subranges therebetween and is or comprises Component G2, as described herein.

According to some of any of the embodiments described herein for the Type B formulation, Component G comprises a multi-functional (e.g., di-functional) urethane methacrylate.

Component G comprises a Component G2 which is a multi-functional (e.g., di-functional) urethane (meth)acrylate featuring, when hardened, Tg that ranges from 0 to 100, or from 50 to 100, °C, including any intermediate values and subranges therebetween, and having a molecular weight of at least 1,000 grams/mol. According to some of any of the embodiments described herein for the Type B formulation, a total amount of the at least one Component D2 and the at least one Component G (e.g., Component G2) ranges from about 30 to about 50, or from about 40 to about 50, % by weight of the total weight of the formulation, including any intermediate values and subranges therebetween.

According to some of any of the embodiments described herein for the Type B formulation, the at least one Component E2 has a molecular weight (MW) of no more than 500 (e.g., of from 100 to 500) grams/mol.

According to some of any of the embodiments described herein for the Type B formulation, each of the one or more of Component E2 independently features, when hardened, Tg lower than 100 °C, or lower than 50 °C (e.g., of from 20 to 60, or from 20 to 50 °C, including any intermediate values and subranges therebetween).

According to some of any of the embodiments described herein for the Type B formulation, the one or more Components E2 comprises a mono-functional alicyclic, preferably hydrophobic, acrylate having a molecular weight (MW) of no more than 500 (e.g., of from 100 to 500) grams/mol and featuring, when hardened, Tg lower than 100 °C, or lower than 50 °C (e.g., of from 20 to 60, or from 20 to 50 °C, including any intermediate values and subranges therebetween).

According to some of any of the embodiments described herein for the Type B formulation, Component E3 comprises a mono-functional hydrophilic or amphiphilic acrylate having a molecular weight (MW) of no more than 500 (e.g., of from 100 to 500) grams/mol.

According to some of any of the embodiments described herein for the Type B formulation, Component E3 comprises a mono-functional hydrophilic or amphiphilic acrylate featuring, when hardened, Tg higher than 50 °C, or higher than 80 °C (e.g., of from 50 to 150 °C, including any intermediate values and subranges therebetween).

According to some of any of the embodiments described herein for the Type B formulation, an amount of the Component H is at least 0.1, or from 0.1 to 1, or from 0.1 to 0.5, % by weight of the total weight of the formulation, including any intermediate values and subranges therebetween.

According to some of any of the embodiments described herein for the Type B formulation, the Component D2 comprises a multi-functional (e.g., di-functional) ethoxylated aromatic methacrylate featuring at least 10 ethoxylated groups, having a molecular weight of at least 1,000 grams/mol as described herein, which features, when hardened, Tg lower than 0 °C, and has a molecular weight of at least 1,000 grams/mol; the Component G comprises a Component G2 which is a multi-functional (e.g., di-functional) urethane (meth)acrylate , featuring, when hardened, Tg that ranges from 0 to 100, or from 50 to 100, °C, including any intermediate values and subranges therebetween, and having a molecular weight of at least 1,000 grams/mol as described herein; a total amount of the at least one Component D2 and the at least one Component G2 is at least 35, or at least 40, or ranges from 35 to 50, or from about 40 to 50, % by weight of the total weight of the formulation; the at least one Component E2 comprises a mono-functional alicyclic, preferably hydrophobic, acrylate having a molecular weight (MW) of no more than 500 (e.g., of from 100 to 500) grams/mol and featuring, when hardened, Tg lower than 100 °C, or lower than 50 °C (e.g., of from 20 to 60, or from 20 to 50 °C, including any intermediate values and subranges therebetween); the at least one Component E3 comprises a mono-functional hydrophilic or amphiphilic acrylate having a molecular weight (MW) of no more than 500 (e.g., of from 100 to 500) grams/mol and featuring, when hardened, Tg higher than 50 °C, or higher than 80 °C (e.g., of from 50 to 150 °C, including any intermediate values and subranges therebetween); and an amount of the Component H is at least 0.1 or ranges from 0.1 to 1 or from 0.1 to 0.5, % by weight of the total weight of the formulation.

According to some of any of the embodiments described herein for the Type B formulation, the formulation further comprises an inhibitor (Component I) and/or a photoinitiator (Component J), as these are described herein in any of the respective embodiments.

According to some of any of the embodiments described herein for the Type B formulation, the formulation further comprises a coloring agent (Component P), as described herein, which preferably comprises a mixture of a pigment and at least one (meth)acrylic material.

In exemplary embodiments, the pigment is a white pigment.

In exemplary embodiments, the Type B formulation is devoid of a pigment or a coloring agent Component P, and is, for example, a transparent or clear formulation.

Type A modeling material formulation:

According to some of any of the embodiments described herein, the Type A modeling material formulation comprises two or more, three or more, four or more, five or more, or all, of the components described herein as Components A, B, C, D, E, F and G (see, Table 1 hereinbelow), and in some of these embodiments, it further comprises one or more of the components H, I, J, P and Dp (see, Table 1 hereinbelow).

According to some of any of the embodiments described herein, the Type A modeling material formulation comprises two or more, three or more, four or more, five or more, and preferably all, of the following components: a multi-functional (e.g., di-functional) urethane (meth)acrylate featuring, when hardened, high Tg (Component A); a multi-functional (e.g., di-functional) non-aromatic (meth) acrylate featuring, when hardened, high Tg (Component B); a filler in a form of micron-sized particles (Component C); a multi-functional (e.g., di-functional) ethoxylated aromatic (meth)acrylate (Component D); a mono-functional (meth)acrylate (Component E); a multi-functional (e.g., tri-functional) (meth)acrylate (Component F); and a multi-functional (e.g., di-functional) aliphatic urethane (meth) acrylate featuring, when hardened, low Tg (Component G).

According to some of any of the embodiments described herein, Component C comprises filler particles functionalized by curable groups, as described herein, and having an average diameter of less than 1 micron (sub-micron-sized particles or nanoparticles).

According to some of any of the embodiments described herein, Component D is a multifunctional (e.g., di-functional) ethoxylated aromatic (meth) acrylate featuring less than 10 ethoxylated groups and/or featuring, when hardened, Tg that ranges from 50 to 150 °C, including any intermediate values and subranges therebetween.

According to some of any of the embodiments described herein, Component G is a multifunctional (e.g., di-functional) aliphatic urethane (meth)acrylate featuring, when hardened, Tg lower than 100 °C.

According to some of any of the embodiments as described herein, an amount of the

Component D is no more than 20, or no more than 15, % by weight of the total weight of the formulation. According to some of any of the embodiments described herein, an amount of the filler is no more than 20, or no more than 15, % by weight of the total weight of the formulation; and an amount of the Component D is no more than 20, or no more than 15, % by weight of the total weight of the formulation.

According to some of any of the embodiments described herein, the Type A modeling material formulation comprises: a multi-functional (e.g., di-functional) aliphatic urethane (meth) acrylate featuring, when hardened, Tg higher than 100 °C (Component A); a multi-functional (e.g., di-functional) non-aromatic (meth) acrylate featuring, when hardened, Tg higher than 100 °C (Component B); a filler in a form of micron-sized particles (Component C); a multi-functional (e.g., di-functional) ethoxylated aromatic (meth) acrylate featuring less than 10 ethoxylated groups and/or featuring, when hardened, Tg that ranges from 50 to 150 °C (Component D); a mono-functional (meth)acrylate (Component E); a multi-functional (e.g., tri-functional) cyclic (meth)acrylate (Component F); and a multi-functional (e.g., di-functional) aliphatic urethane (meth) acrylate featuring, when hardened, Tg lower than 100 °C (Component G), wherein: an amount of the filler (Component C) is no more than 20, or no more than 15, % by weight of the total weight of the formulation; and an amount of the Component D is no more than 20, or no more than 15, % by weight of the total weight of the formulation.

According to some of any of the embodiments described herein, the Type A modeling material formulation comprises Component A as defined herein, Component B 1 as defined herein, Component C as defined herein, Component DI as defined herein, Components El and E2 as defined herein, Component Fl as defined herein, and Component G, as defined herein (for example, Component G2).

According to some of any of the embodiments described herein, an amount of Component A, as described herein in any of the respective embodiments and any combination thereof, ranges from 15 to 25, % by weight of the total weight of the formulation, including any intermediate values and subranges therebetween.

According to some of any of the embodiments described herein, an amount of each of Components B and C, as described herein in any of the respective embodiments and any combination thereof, is no more than 20, or no more than 15, % by weight of the total weight of the formulation, and, for example, ranges from about 5 to about 20, or preferably from about 5 to about 15, % by weight, of the total weight of the formulation, including any intermediate values and subranges therebetween.

According to some of any of the embodiments described herein, an amount of Component D, as described herein in any of the respective embodiments and any combination thereof, is no more than 20, or no more than 15, % by weight of the total weight of the formulation, and preferably ranges from about 5 to about 20, or preferably from about 5 to about 15, % by weight, including any intermediate values and subranges therebetween.

According to some of any of the embodiments described herein, a total amount of Component E, as described herein in any of the respective embodiments and any combination thereof, ranges 30 to 40 % by weight of the total weight of the formulation, including any intermediate values and subranges therebetween.

According to some of any of the embodiments described herein, an amount of Component

F, as described herein in any of the respective embodiments and any combination thereof, ranges from 5 to 10, % by weight of the total weight of the formulation, including any intermediate values and subranges therebetween.

G, as described herein in any of the respective embodiments and any combination thereof, ranges from about 5 to about 10, % by weight of the total weight of the formulation, including any intermediate values and subranges therebetween.

According to some of any of the embodiments described herein, the Type A modeling material formulation comprises:

Component A, as described herein in any of the respective embodiments and any combination thereof, in an amount that ranges from 15 to 25, % by weight of the total weight of the formulation, including any intermediate values and subranges therebetween;

Components B and C, as described herein in any of the respective embodiments and any combination thereof, each independently in an amount of no more than 20, or no more than 15, % by weight of the total weight of the formulation;

Component D, as described herein in any of the respective embodiments and any combination thereof, in an amount of no more than 20, or no more than 15, % by weight of the total weight of the formulation; Component E, as described herein in any of the respective embodiments and any combination thereof, in an amount of from 30 to 40 % by weight of the total weight of the formulation, including any intermediate values and subranges therebetween;

Component F, as described herein in any of the respective embodiments and any combination thereof, in an amount of from 5 to 10, % by weight of the total weight of the formulation, including any intermediate values and subranges therebetween; and

Component G, as described herein in any of the respective embodiments and any combination thereof, in an amount of from 5 to 10, % by weight of the total weight of the formulation, including any intermediate values and subranges therebetween.

Component B, as described herein in any of the respective embodiments and any combination thereof, in an amount of no more than 20, or no more than 15, % by weight of the total weight of the formulation;

Component C, as described herein in any of the respective embodiments and any combination thereof, in an amount of no more than 20, or no more than 15, % by weight of the total weight of the formulation;

Component D, as described herein in any of the respective embodiments and any combination thereof, in an amount of no more than 20, or no more than 15, % by weight of the total weight of the formulation;

Components El and E2, as described herein in any of the respective embodiments and any combination thereof, in a total amount of from 30 to 40 % by weight of the total weight of the formulation, including any intermediate values and subranges therebetween;

Component Fl, as described herein in any of the respective embodiments and any combination thereof, in an amount of from 5 to 10, % by weight of the total weight of the formulation, including any intermediate values and subranges therebetween; and

According to some of any of the embodiments described herein, a weight ratio of the monofunctional methacrylate (El) and the mono-functional acrylate (E2) ranges from 2:1 to 1:2, or is about 1:1.

According to some of any of the embodiments described herein, an amount of each of the mono-functional acrylate (E2) and the mono-functional methacrylate (El) independently ranges from 10 to 20, or from 15 to 20, % by weight of the total weight of the formulation, including any intermediate values and subranges therebetween.

According to some of any of the embodiments described herein, a total amount of the one or more mono-functional (meth)acrylate(s) (e.g., Components El and E2) ranges from 30 to 40 % by weight of the total weight of the formulation, including any intermediate values and subranges therebetween.

According to some of any of the embodiments described herein, at least one or both of the mono-functional acrylate (Component E2) and the mono-functional methacrylate (Component El) features, when hardened, Tg lower than 100 °C or lower than 80 °C.

According to exemplary embodiments, the Type A modeling material formulation comprises:

Component A as described herein in any of the respective embodiments and any combination thereof in an amount that ranges from 15 to 25, % by weight of the total weight of the formulation, including any intermediate values and subranges therebetween;

Component B as described herein in any of the respective embodiments and any combination thereof, preferably Component B 1, in an amount of no more than 20, or no more than 15, % by weight of the total weight of the formulation;

Component C as described herein in any of the respective embodiments and any combination thereof, in an amount of no more than 20, or no more than 15, % by weight of the total weight of the formulation;

Component D as described herein in any of the respective embodiments and any combination thereof, preferably Component DI, in an amount of no more than 20, or no more than 15, % by weight of the total weight of the formulation;

Component E as described herein in any of the respective embodiments and any combination thereof, preferably a mixture of Components El and E2, in a total amount of from 30 to 40 % by weight of the total weight of the formulation, including any intermediate values and subranges therebetween; Component F as described herein in any of the respective embodiments and any combination thereof, preferably Component Fl, in an amount of from 5 to 10, % by weight of the total weight of the formulation, including any intermediate values and subranges therebetween; and Component G as described herein in any of the respective embodiments and any combination thereof, in an amount of from 5 to 10, % by weight of the total weight of the formulation, including any intermediate values and subranges therebetween.

According to exemplary embodiments, the Type A modeling material formulation comprises: as Component A - a di-functional aliphatic urethane methacrylate featuring, when hardened, Tg higher than 100 °C, such as described herein; as Component B - Component B 1 which is a di-functional alicyclic acrylate featuring, when hardened, Tg higher than 100 °C, such as described herein; as Component C comprises silica particles having curable groups attached thereto, such as described herein; as Component D - Component DI which is a di-functional ethoxylated aromatic methacrylate featuring less than 5 ethoxylated groups and, when hardened, Tg that ranges from 50 to 150 °C, such as described herein; as Component E - a mono-functional acrylate (Component E2) and a mono-functional methacrylate (Component El), each independently in an amount of from 10 to 20, or from 15 to 20, % by weight, of the total weight of the formulation; as Component F - Component Fl which is a tri-functional isocyanurate triacrylate; and as Component G - a di-functional aliphatic urethane dimethacrylate featuring, when hardened, Tg lower than 100 °C and an average MW of at least 1,000 grams/mol, such as described herein.

According to exemplary embodiments, the modeling material formulation comprises: as Component A - a di-functional aliphatic urethane methacrylate featuring, when hardened, Tg higher than 100 °C, such as described herein, in an amount that ranges from 15 to 25, % by weight of the total weight of the formulation, including any intermediate values and subranges therebetween; as Component B - Component B 1 which is a di-functional alicyclic acrylate featuring, when hardened, Tg higher than 100 °C, such as described herein, in an amount of no more than 20, or no more than 15, % by weight of the total weight of the formulation; as Component C - comprises silica particles having curable groups attached thereto, in an amount of no more than 20, or no more than 15, % by weight of the total weight of the formulation; as Component D - Component DI which is a di-functional ethoxylated aromatic methacrylate featuring less than 5 ethoxylated groups and, when hardened, Tg that ranges from 50 to 150 °C, including any intermediate values and subranges therebetween, such as described herein, in an amount of no more than 20, or no more than 15, % by weight of the total weight of the formulation; as Component E - a mono-functional acrylate (Component E2) and a mono-functional methacrylate (Component El), each independently in an amount of from 10 to 20, or from 15 to 20, % by weight, of the total weight of the formulation, including any intermediate values and subranges therebetween, in a total amount of from 30 to 40 % by weight of the total weight of the formulation, including any intermediate values and subranges therebetween; as Component F - Component Fl which is a tri-functional isocyanurate triacrylate, in an amount of from 5 to 10, % by weight of the total weight of the formulation, including any intermediate values and subranges therebetween; and as Component G - a di-functional aliphatic urethane dimethacrylate featuring, when hardened, Tg lower than 100 °C and an average MW of at least 1,000 grams/mol, such as described herein, in an amount of from 5 to 10, % by weight of the total weight of the formulation, including any intermediate values and subranges therebetween.

According to some of any of the embodiments described herein, the Type A modeling material formulation comprises, as Component G, Component G1 as described herein in any of the respective embodiments.

According to some of any of the embodiments described herein, the Type A modeling material formulation is devoid of methyl methacrylate and/or methylacrylate, and/or is such that the hardened modeling material is devoid of poly(methyl methacrylate) (PMMA).

Herein throughout, by “devoid of’ it is meant less than 1 %, or less than 0.1 %, or less than 0.01 %, or less than 0.001 %, or null.

According to some of any of the embodiments described herein, the Type A modeling material formulation further comprises a dispersant (Component H), as described herein in any of the respective embodiments.

According to some of any of the embodiments described herein, an amount of the dispersant ranges from 0.1 to 0.5, % by weight, of the total weight of the formulation, including any intermediate values and subranges therebetween.

According to some of any of the embodiments described herein, the Type A modeling material formulation further comprises a polymerization inhibitor (Component I), as described herein, for example, a phenol-type inhibitor or any other inhibitor that is commonly used in medical devices or applications and/in food products.

According to some of any of the embodiments described herein, the Type A modeling material formulation further comprises one or more coloring agent(s) (Component P).

The coloring agent can be a pigment or a dye and is preferably a pigment.

According to some of these embodiments, an amount of the white pigment in the mixture with the one or more curable materials ranges from 20 to 50 % by weight of the total weight of the mixture, including any intermediate values and subranges therebetween.

According to some of these embodiments, an amount of the coloring agent, which is a mixture of a white pigment and at least one (meth)acrylic material ranges from 1 to 5 % by weight of the total weight of the (e.g. Type A) formulation, including any intermediate values and subranges therebetween. According to some of any of the embodiments described herein, the pigment is a cyan pigment and the formulation provides a cyan hardened material.

According to some of any of the embodiments described herein, the coloring agent comprises a mixture of a cyan pigment and one or more curable materials such as (meth)acrylic materials, such that the cyan pigment is introduced to the formulation within this mixture.

According to some of these embodiments, an amount of the cyan pigment in the mixture with the one or more curable materials ranges from 0.01 to 1, or from 0.05 to 0.5, or from 0.1 to 0.2, % by weight of the total weight of the mixture, including any intermediate values and subranges therebetween.

According to some of these embodiments, an amount of the coloring agent, which is a mixture of a cyan pigment and at least one (meth)acrylic material ranges from 0.1 to 1 % by weight of the total weight of the (e.g., Type A) formulation, including any intermediate values and subranges therebetween.

According to some of these embodiments, an amount of the yellow pigment in the mixture with the one or more curable materials ranges from 0.01 to 1, or from 0.05 to 0.5, or from 0.1 to 0.2, % by weight of the total weight of the mixture, including any intermediate values and subranges therebetween.

According to some of these embodiments, an amount of the coloring agent, which is a mixture of a yellow pigment and at least one (meth)acrylic material ranges from 0.1 to 1 % by weight of the total weight of the (e.g., Type A) formulation, including any intermediate values and subranges therebetween.

According to some of these embodiments, an amount of the magenta pigment in the mixture with the one or more curable materials ranges from 0.01 to 1, or from 0.05 to 0.5, or from 0.1 to 0.2, % by weight of the total weight of the mixture, including any intermediate values and subranges therebetween.

According to some of these embodiments, an amount of the coloring agent, which is a mixture of a magenta pigment and at least one (meth)acrylic material ranges from 0.1 to 1 % by weight of the total weight of the (e.g., Type A) formulation, including any intermediate values and subranges therebetween.

According to some of any of the embodiments described herein, the coloring agent further comprises a pigment dispersant (Component Dp). Preferred pigment dispersants are such that has a plurality of groups that feature an affinity to the pigment.

According to some of any of the embodiments described herein, the modeling material formulation comprises Components H, I, and J, as described herein in any of the respective embodiments. An exemplary such a formulation is a clear colorless formulation, which is devoid of a coloring agent.

According to some of any of the embodiments described herein, the modeling material formulation comprises Components H, I, J, P and Dp, as described herein in any of the respective embodiments. Exemplary such formulations are the cyan, magenta and yellow formulation as described herein.

Support material formulation:

The modeling material formulations described herein can be used together with a support material formulation that is usable, for example, in AM such as 3D inkjet printing is contemplated.

In exemplary embodiments, the support material formulation comprises: a non-curable water-soluble or water-miscible polymeric material, in an amount of from about 40 to about 60 % by weight of the total weight of the formulation, including any intermediate values and subranges therebetween; a hydrophilic mono-functional (meth)acrylate, in an amount of from 15 to 25 % by weight of the total weight of the formulation, including any intermediate values and subranges therebetween; a hydrophilic mono-functional (meth) acrylamide in an amount of from 10 to 20 % by weight of the total weight of the formulation, including any intermediate values and subranges therebetween; and a multi-functional non-aromatic (e.g., aliphatic or alicyclic) (meth) acrylate in an amount of from 1 to 5 % by weight of the total weight of the formulation, including any intermediate values and subranges therebetween.

According to some of any of these embodiments, the non-curable polymeric material comprises a polyol.

Herein and in the art, the term “polyol” describes a polymeric material that features two or more free hydroxy groups, typically from about 10 to dozens or hundreds free hydroxy groups. Representative examples of a polyol include, without limitation, a polyester polyol, a polyether polyol and a urethane polyol. Preferably, the polyol is a polyether polyol such as, for example, a poly(alkylene glycol).

The polyol can be a linear polyol or a non-linear (e.g., branched polyol).

According to some of any of the embodiments described herein, the polyol is a poly(alkylene glycol), for example, a poly(ethylene glycol) or a poly(propylene glycol) or a mixture thereof. In some embodiments, the polyol is or comprises a poly(propylene glycol).

According to some of any of the embodiments described herein, the polyol comprises an alkoxylated branched polyol, such as, for example, marketed as Polyol 3165.

According to some of any of the embodiments described herein, the polyol has an average molecular weight lower than 1,200, or lower than 1,000 grams/mol.

The polyol can have an average molecular weight that ranges from about 200 to about 1,100, or from about 400 to about 1,100, including any intermediate values and subranges therebetween.

According to some of any of the embodiments described herein, the support material formulation further comprises a non-curable water-soluble or water- miscible non-polymeric material, such as a diol, or triol, or glycerol, etc. In exemplary embodiments, it is a diol such as propanediol.

According to some of any of the embodiments described herein, the support material formulation comprises a mixture of polymeric and non-polymeric materials as described herein, and in some of these embodiments it comprises a mixture of a poly(alkylene glycol), a branched polyol, and a diol. In some embodiments, the total amount of these materials ranges from about 40 to about 80 % by weight of the total weight of the formulation, including any intermediate values and subranges therebetween.

According to some of any of the embodiments described herein, the formulation comprises one or more mono-functional curable materials.

According to some of any of the embodiments described herein, one or more, or each, of the mono-functional curable material(s) is a hydrophilic material, as defined herein, for example, having Formula Al.

According to some embodiments, at least one of the mono-functional curable materials is a mono-functional (meth)acrylate, preferably a mono-functional acrylate having Formula Al in which Ri is a carboxylate. In some of these embodiments, R’ is a poly(alkylene glycol), as defined herein. An exemplary such hydrophilic mono-functional acrylate is hexa(ethylene glycol) acrylate, (6-PEA).

According to some embodiments, at least one of the mono-functional curable materials is a mono-functional (meth)acrylamide, preferably a mono-functional acrylate having Formula Al in which Ri is amide. According to some embodiments, at least one of the mono-functional curable materials is a mono -functional acrylamide. In some of these embodiments, Ra is a shorty alkyl, of 2 to 8, or 2 to 6, or 2 to 4, carbon atom in length, which terminates by a hydrophilic group as defined herein. An exemplary such hydrophilic group is hydroxy alkyl, for example, hydroxyethyl.

According to some of any of the embodiments described herein, one or more, or each, of the mono-functional curable material(s) is a water-miscible or water-soluble material, as defined herein.

According to some of any of the embodiments described herein, the formulation comprises a multi-functional (e.g., di-functional) aliphatic or alicyclic (meth) acrylate.

According to some embodiments, the formulation comprises a di-functional aliphatic or alicyclic (meth) acrylate.

According to some of any of the embodiments described herein, the formulation comprises a multi-functional (e.g., di-functional) aliphatic or alicyclic acrylate.

According to some of any of the embodiments described herein, the formulation comprises a di-functional aliphatic or alicyclic acrylate, that is, an aliphatic or alicyclic diacrylate.

According to some of any of the embodiments described herein, the formulation comprises a multi-functional (e.g., di-functional) alicyclic (meth)acrylate.

According to some of any of the embodiments described herein, the formulation comprises a di-functional alicyclic (meth)acrylate. According to some of any of the embodiments described herein, the formulation comprises a multi-functional alicyclic acrylate.

According to some of any of the embodiments described herein, the formulation comprises a di-functional alicyclic acrylate, an alicyclic diacrylate.

According to some of any of the embodiments described herein, the formulation comprises a multi-functional (e.g., di-functional) alicyclic (meth)acrylate features, when hardened, high Tg, for example, Tg higher than 100 °C.

According to some of any of the embodiments described herein, the formulation comprises a di-functional alicyclic (meth)acrylate featuring, when hardened, high Tg, for example, Tg higher than 100 °C.

According to some of any of the embodiments described herein, the formulation comprises a di-functional alicyclic acrylate, or an alicyclic diacrylate, featuring, when hardened, high Tg, for example, Tg higher than 100 °C.

According to some of any of the embodiments described herein, the alicyclic diacrylate comprises an alicyclic moiety of at least 6, 7, 8 or more carbon atoms.

According to some of any of the embodiments described herein, the alicyclic diacrylate comprises an alicyclic moiety which comprises 2, 3 or more fused rings.

According to some of any of the embodiments described herein, the multi-functional (meth)acrylate as described herein in any of the respective embodiments features, when hardened, Tg that ranges from 100 to 300, or from 150 to 300, or from 100 to 200, or from 150 to 200, °C, including any intermediate values and subranges therebetween.

According to some of any of the embodiments of this aspect of the present invention, the support material formulation further comprises a photoinitiator, and optionally one or more of a dispersant, an inhibitor, and the like, as described herein in any of the respective embodiments of the modeling material formulation.

According to some embodiments, an amount of the photoinitiator ranges from 0.1 to 1 % by weight of the total weight of the formulation, including any intermediate values and subranges therebetween.

Definitions:

Herein throughout, whenever the phrase “weight percent”, or “% by weight” or “% wt.”, is indicated in the context of embodiments of a formulation (e.g., a modeling formulation), it is meant weight percent of the total weight of the respective uncured formulation.

Herein throughout, an acrylic material is used to collectively describe material featuring one or more acrylate, methacrylate, acrylamide and/or methacrylamide group(s). Similarly, an acrylic group is used to collectively describe curable groups which are acrylate, methacrylate, acrylamide and/or methacrylamide group(s), preferably acrylate or methacrylate groups (referred to herein also as (meth)acrylate groups).

Herein throughout, the term “(meth) acrylic” encompasses acrylic and methacrylic materials.

Herein throughout, the phrase “linking moiety” or “linking group” describes a group that connects two or more moieties or groups in a compound. A linking moiety is typically derived from a bi- or tri-functional compound, and can be regarded as a bi- or tri-radical moiety, which is connected to two or three other moieties, via two or three atoms thereof, respectively.

Exemplary linking moieties include a hydrocarbon moiety or chain, optionally interrupted by one or more heteroatoms, as defined herein, and/or any of the chemical groups listed below, when defined as linking groups.

When a chemical group is referred to herein as “end group” it is to be interpreted as a substituent, which is connected to another group via one atom thereof.

Herein throughout, the term “hydrocarbon” collectively describes a chemical group composed mainly of carbon and hydrogen atoms. A hydrocarbon can be comprised of alkyl, alkene, alkyne, aryl, and/or cycloalkyl, each can be substituted or unsubstituted, and can be interrupted by one or more heteroatoms. The number of carbon atoms can range from 2 to 30, and is preferably lower, e.g., from 1 to 10, or from 1 to 6, or from 1 to 4. A hydrocarbon can be a linking group or an end group.

Bisphenol A is an example of a hydrocarbon comprised of 2 aryl groups and one alkyl group. Dimethylenecyclohexane is an example of a hydrocarbon comprised of 2 alkyl groups and one cycloalkyl group.

As used herein, the term “amine” describes both a -NR’R” group and a -NR'- group, wherein R’ and R" are each independently hydrogen, alkyl, cycloalkyl, aryl, as these terms are defined hereinbelow.

The amine group can therefore be a primary amine, where both R’ and R” are hydrogen, a secondary amine, where R’ is hydrogen and R” is alkyl, cycloalkyl or aryl, or a tertiary amine, where each of R’ and R” is independently alkyl, cycloalkyl or aryl.

Alternatively, R' and R" can each independently be hydroxyalkyl, trihaloalkyl, cycloalkyl, alkenyl, alkynyl, aryl, heteroaryl, heteroalicyclic, amine, halide, sulfonate, sulfoxide, phosphonate, hydroxy, alkoxy, aryloxy, thiohydroxy, thioalkoxy, thioaryloxy, cyano, nitro, azo, sulfonamide, carbonyl, C-carboxylate, O-carboxylate, N-thiocarbamate, O-thiocarbamate, urea, thiourea, N-carbamate, O-carbamate, C-amide, N-amide, guanyl, guanidine and hydrazine. The term “amine” is used herein to describe a -NR'R" group in cases where the amine is an end group, as defined hereinunder, and is used herein to describe a -NR'- group in cases where the amine is a linking group or is or part of a linking moiety.

The term "alkyl" describes a saturated aliphatic hydrocarbon including straight chain and branched chain groups. Preferably, the alkyl group has 1 to 30, or 1 to 20 carbon atoms. Whenever a numerical range; e.g., "1-20", is stated herein, it implies that the group, in this case the alkyl group, may contain 1 carbon atom, 2 carbon atoms, 3 carbon atoms, etc., up to and including 20 carbon atoms. The alkyl group may be substituted or unsubstituted. Substituted alkyl may have one or more substituents, whereby each substituent group can independently be, for example, hydroxyalkyl, trihaloalkyl, cycloalkyl, alkenyl, alkynyl, aryl, heteroaryl, heteroalicyclic, amine, halide, sulfonate, sulfoxide, phosphonate, hydroxy, alkoxy, aryloxy, thiohydroxy, thioalkoxy, thioaryloxy, cyano, nitro, azo, sulfonamide, C-carboxylate, O-carboxylate, N-thiocarbamate, O-thiocarbamate, urea, thiourea, N-carbamate, O-carbamate, C-amide, N-amide, guanyl, guanidine and hydrazine.

The alkyl group can be an end group, as this phrase is defined hereinabove, wherein it is attached to a single adjacent atom, or a linking group, as this phrase is defined hereinabove, which connects two or more moieties via at least two carbons in its chain. When the alkyl is a linking group, it is also referred to herein as “alkylene” or “alkylene chain”.

Alkene and Alkyne, as used herein, are an alkyl, as defined herein, which contains one or more double bond or triple bond, respectively.

The term "cycloalkyl" describes an all-carbon monocyclic ring or fused rings (z.e., rings which share an adjacent pair of carbon atoms) group where one or more of the rings does not have a completely conjugated pi-electron system. Examples include, without limitation, cyclohexane, adamantine, norbomyl, isobomyl, and the like. The cycloalkyl group may be substituted or unsubstituted. Substituted cycloalkyl may have one or more substituents, whereby each substituent group can independently be, for example, hydroxyalkyl, trihaloalkyl, cycloalkyl, alkenyl, alkynyl, aryl, heteroaryl, heteroalicyclic, amine, halide, sulfonate, sulfoxide, phosphonate, hydroxy, alkoxy, aryloxy, thiohydroxy, thioalkoxy, thioaryloxy, cyano, nitro, azo, sulfonamide, C- carboxylate, O-carboxylate, N-thiocarbamate, O-thiocarbamate, urea, thiourea, N-carbamate, O-carbamate, C-amide, N-amide, guanyl, guanidine and hydrazine. The cycloalkyl group can be an end group, as this phrase is defined hereinabove, wherein it is attached to a single adjacent atom, or a linking group, as this phrase is defined hereinabove, connecting two or more moieties at two or more positions thereof. The term "heteroalicyclic" describes a monocyclic or fused ring group having in the ring(s) one or more atoms such as nitrogen, oxygen and sulfur. The rings may also have one or more double bonds. However, the rings do not have a completely conjugated pi-electron system. Representative examples are piperidine, piperazine, tetrahydrofurane, tetrahydropyrane, morpholino, oxalidine, and the like.

The heteroalicyclic may be substituted or unsubstituted. Substituted heteroalicyclic may have one or more substituents, whereby each substituent group can independently be, for example, hydroxyalkyl, trihaloalkyl, cycloalkyl, alkenyl, alkynyl, aryl, heteroaryl, heteroalicyclic, amine, halide, sulfonate, sulfoxide, phosphonate, hydroxy, alkoxy, aryloxy, thiohydroxy, thioalkoxy, thioaryloxy, cyano, nitro, azo, sulfonamide, C-carboxylate, O-carboxylate, N-thiocarbamate, O-thiocarbamate, urea, thiourea, O-carbamate, N-carbamate, C-amide, N-amide, guanyl, guanidine and hydrazine. The heteroalicyclic group can be an end group, as this phrase is defined hereinabove, where it is attached to a single adjacent atom, or a linking group, as this phrase is defined hereinabove, connecting two or more moieties at two or more positions thereof.

The term "aryl" describes an all-carbon monocyclic or fused-ring polycyclic (z.e., rings which share adjacent pairs of carbon atoms) groups having a completely conjugated pi-electron system. The aryl group may be substituted or unsubstituted. Substituted aryl may have one or more substituents, whereby each substituent group can independently be, for example, hydroxyalkyl, trihaloalkyl, cycloalkyl, alkenyl, alkynyl, aryl, heteroaryl, heteroalicyclic, amine, halide, sulfonate, sulfoxide, phosphonate, hydroxy, alkoxy, aryloxy, thiohydroxy, thioalkoxy, thioaryloxy, cyano, nitro, azo, sulfonamide, C-carboxylate, O-carboxylate, N-thiocarbamate, O-thiocarbamate, urea, thiourea, N-carbamate, O-carbamate, C-amide, N-amide, guanyl, guanidine and hydrazine. The aryl group can be an end group, as this term is defined hereinabove, wherein it is attached to a single adjacent atom, or a linking group, as this term is defined hereinabove, connecting two or more moieties at two or more positions thereof.

The term "heteroaryl" describes a monocyclic or fused ring (z.e., rings which share an adjacent pair of atoms) group having in the ring(s) one or more atoms, such as, for example, nitrogen, oxygen and sulfur and, in addition, having a completely conjugated pi-electron system. Examples, without limitation, of heteroaryl groups include pyrrole, furan, thiophene, imidazole, oxazole, thiazole, pyrazole, pyridine, pyrimidine, quinoline, isoquinoline and purine. The heteroaryl group may be substituted or unsubstituted. Substituted heteroaryl may have one or more substituents, whereby each substituent group can independently be, for example, hydroxyalkyl, trihaloalkyl, cycloalkyl, alkenyl, alkynyl, aryl, heteroaryl, heteroalicyclic, amine, halide, sulfonate, sulfoxide, phosphonate, hydroxy, alkoxy, aryloxy, thiohydroxy, thioalkoxy, thioaryloxy, cyano, nitro, azo, sulfonamide, C-carboxylate, O-carboxylate, N-thiocarbamate, O-thiocarbamate, urea, thiourea, O-carbamate, N-carbamate, C-amide, N-amide, guanyl, guanidine and hydrazine. The heteroaryl group can be an end group, as this phrase is defined hereinabove, where it is attached to a single adjacent atom, or a linking group, as this phrase is defined hereinabove, connecting two or more moieties at two or more positions thereof. Representative examples are pyridine, pyrrole, oxazole, indole, purine and the like.

The term "halide" and “halo” describes fluorine, chlorine, bromine or iodine.

The term “haloalkyl” describes an alkyl group as defined above, further substituted by one or more halide.

The term “sulfate” describes a -O-S(=O)2-OR’ end group, as this term is defined hereinabove, or an -O-S(=O)2-O- linking group, as these phrases are defined hereinabove, where R’ is as defined hereinabove.

The term “thiosulfate” describes a -O-S(=S)(=O)-OR’ end group or a -O-S(=S)(=O)-O- linking group, as these phrases are defined hereinabove, where R’ is as defined hereinabove.

The term “sulfite” describes an -O-S(=O)-O-R’ end group or a -O-S(=O)-O- group linking group, as these phrases are defined hereinabove, where R’ is as defined hereinabove.

The term “thiosulfite” describes a -O-S(=S)-O-R’ end group or an -O-S(=S)-O- group linking group, as these phrases are defined hereinabove, where R’ is as defined hereinabove.

The term “sulfinate” describes a -S(=O)-OR’ end group or an -S(=O)-O- group linking group, as these phrases are defined hereinabove, where R’ is as defined hereinabove.

The term “sulfoxide” or “sulfinyl” describes a -S(=O)R’ end group or an -S(=O)- linking group, as these phrases are defined hereinabove, where R’ is as defined hereinabove.

The term "sulfonate” describes a -S(=O)2-R’ end group or an -S(=O)2- linking group, as these phrases are defined hereinabove, where R’ is as defined herein.

The term “S-sulfonamide” describes a -S(=0)2-NR’R” end group or a -S(=O)2-NR’- linking group, as these phrases are defined hereinabove, with R’ and R” as defined herein.

The term "N- sulfonamide" describes an R’S(=0)2-NR”- end group or a -S(=O)2-NR’- linking group, as these phrases are defined hereinabove, where R’ and R’ ’ are as defined herein.

The term “disulfide” refers to a -S-SR’ end group or a -S-S- linking group, as these phrases are defined hereinabove, where R’ is as defined herein.

The term “phosphonate” describes a -P(=O)(OR’)(OR”) end group or a -P(=O)(OR’)(O)- linking group, as these phrases are defined hereinabove, with R’ and R” as defined herein. The term “thiophosphonate” describes a -P(=S)(OR’)(OR”) end group or a -P(=S)(OR’)(O)- linking group, as these phrases are defined hereinabove, with R’ and R” as defined herein.

The term “phosphinyl” describes a -PR'R" end group or a -PR’- linking group, as these phrases are defined hereinabove, with R’ and R" as defined hereinabove.

The term “phosphine oxide” describes a -P(=O)(R’)(R”) end group or a -P(=O)(R’)- linking group, as these phrases are defined hereinabove, with R’ and R” as defined herein.

The term “phosphine sulfide” describes a -P(=S)(R’)(R”) end group or a -P(=S)(R’)- linking group, as these phrases are defined hereinabove, with R’ and R” as defined herein.

The term “phosphite” describes an -O-PR'(=O)(OR") end group or an -O-PH(=O)(O)- linking group, as these phrases are defined hereinabove, with R’ and R" as defined herein.

The term "carbonyl" or "carbonate" as used herein, describes a -C(=O)-R’ end group or a -C(=O)- linking group, as these phrases are defined hereinabove, with R’ as defined herein.

The term "thiocarbonyl" as used herein, describes a -C(=S)-R’ end group or a -C(=S)- linking group, as these phrases are defined hereinabove, with R’ as defined herein.

The term “oxo” as used herein, describes a (=0) group, wherein an oxygen atom is linked by a double bond to the atom (e.g., carbon atom) at the indicated position.

The term “thiooxo” as used herein, describes a (=S) group, wherein a sulfur atom is linked by a double bond to the atom (e.g., carbon atom) at the indicated position.

The term “oxime” describes a =N-0H end group or a =N-0- linking group, as these phrases are defined hereinabove.

The term “hydroxyl” describes a -OH group.

The term "alkoxy" describes both an -O-alkyl and an -O-cycloalkyl group, as defined herein. The term alkoxide describes -R’0“ group, with R’ as defined herein.

The term "aryloxy" describes both an -O-aryl and an -O-heteroaryl group, as defined herein.

The term "thiohydroxy" or “thiol” describes a -SH group. The term “thiolate” describes a -S’ group.

The term "thioalkoxy" describes both a -S-alkyl group, and a -S-cycloalkyl group, as defined herein.

The term "thioaryloxy" describes both a -S-aryl and a -S-heteroaryl group, as defined herein. The “hydroxy alkyl” is also referred to herein as “alcohol”, and describes an alkyl, as defined herein, substituted by a hydroxy group.

The term "cyano" describes a -C=N group.

The term “isocyanate” describes an -N=C=O group.

The term “isothiocyanate” describes an -N=C=S group.

The term "nitro" describes an -NO2 group.

The term “acyl halide” describes a -(C=O)R"" group wherein R"" is halide, as defined hereinabove.

The term "azo" or “diazo” describes an -N=NR’ end group or an -N=N- linking group, as these phrases are defined hereinabove, with R’ as defined hereinabove.

The term "peroxo" describes an -O-OR’ end group or an -O-O- linking group, as these phrases are defined hereinabove, with R’ as defined hereinabove.

The term “carboxylate” as used herein encompasses C-carboxylate and O-carboxylate.

The term “C-carboxylate” describes a -C(=0)-0R’ end group or a -C(=0)-0- linking group, as these phrases are defined hereinabove, where R’ is as defined herein.

The term “O-carboxylate” describes a -0C(=0)R’ end group or a -0C(=0)- linking group, as these phrases are defined hereinabove, where R’ is as defined herein.

A carboxylate can be linear or cyclic. When cyclic, R’ and the carbon atom are linked together to form a ring, in C-carboxylate, and this group is also referred to as lactone. Alternatively, R’ and O are linked together to form a ring in O-carboxylate. Cyclic carboxylates can function as a linking group, for example, when an atom in the formed ring is linked to another group.

The term “thiocarboxylate” as used herein encompasses C-thiocarboxylate and O- thiocarboxylate.

The term “C-thiocarboxylate” describes a -C(=S)-OR’ end group or a -C(=S)-O- linking group, as these phrases are defined hereinabove, where R’ is as defined herein.

The term “O-thiocarboxylate” describes a -OC(=S)R’ end group or a -OC(=S)- linking group, as these phrases are defined hereinabove, where R’ is as defined herein.

A thiocarboxylate can be linear or cyclic. When cyclic, R’ and the carbon atom are linked together to form a ring, in C-thiocarboxylate, and this group is also referred to as thiolactone. Alternatively, R’ and O are linked together to form a ring in O-thiocarboxylate. Cyclic thiocarboxylates can function as a linking group, for example, when an atom in the formed ring is linked to another group.

The term “carbamate” as used herein encompasses N-carbamate and O-carbamate. The term “N-carbamate” describes an R”OC(=O)-NR’- end group or a -OC(=O)-NR’- linking group, as these phrases are defined hereinabove, with R’ and R” as defined herein.

The term “O-carbamate” describes an -OC(=O)-NR’R” end group or an -OC(=O)- NR’- linking group, as these phrases are defined hereinabove, with R’ and R” as defined herein.

A carbamate can be linear or cyclic. When cyclic, R’ and the carbon atom are linked together to form a ring, in O-carbamate. Alternatively, R’ and O are linked together to form a ring in N-carbamate. Cyclic carbamates can function as a linking group, for example, when an atom in the formed ring is linked to another group.

The term “carbamate” as used herein encompasses N-carbamate and O-carbamate..

The term “thiocarbamate” as used herein encompasses N-thiocarbamate and O- thiocarbamate.

The term “O-thiocarbamate” describes a -OC(=S)-NR’R” end group or a -OC(=S)-NR’- linking group, as these phrases are defined hereinabove, with R’ and R” as defined herein.

The term “N-thiocarbamate” describes an R”OC(=S)NR’- end group or a -OC(=S)NR’- linking group, as these phrases are defined hereinabove, with R’ and R” as defined herein.

Thiocarbamates can be linear or cyclic, as described herein for carbamates.

The term “dithiocarbamate” as used herein encompasses S -dithiocarbamate and N- dithiocarbamate.

The term “S -dithiocarbamate” describes a -SC(=S)-NR’R” end group or a -SC(=S)NR’- linking group, as these phrases are defined hereinabove, with R’ and R” as defined herein.

The term “N-dithiocarbamate” describes an R”SC(=S)NR’- end group or a -SC(=S)NR’- linking group, as these phrases are defined hereinabove, with R’ and R” as defined herein.

The term "urea", which is also referred to herein as “ureido”, describes a -NR’C(=O)- NR”R’ ’ ’ end group or a -NR’C(=O)-NR”- linking group, as these phrases are defined hereinabove, where R’ and R” are as defined herein and R'" is as defined herein for R' and R".

The term “thiourea”, which is also referred to herein as “thioureido”, describes a -NR’- C(=S)-NR”R”’ end group or a -NR’-C(=S)-NR”- linking group, with R’, R” and R’” as defined herein.

The term “amide” as used herein encompasses C-amide and N-amide.

The term “C-amide” describes a -C(=O)-NR’R” end group or a -C(=O)-NR’- linking group, as these phrases are defined hereinabove, where R’ and R” are as defined herein. The term “N-amide ’ describes a R C(=O)-NR end group or a R C(=O)-N- linking group, as these phrases are defined hereinabove, where R’ and R” are as defined herein.

An amide can be linear or cyclic. When cyclic, R’ and the carbon atom are linked together to form a ring, in C-amide, and this group is also referred to as lactam. Cyclic amides can function as a linking group, for example, when an atom in the formed ring is linked to another group.

The term “guanyl” describes a R’R”NC(=N)- end group or a -R’NC(=N)- linking group, as these phrases are defined hereinabove, where R’ and R” are as defined herein.

The term “guanidine” describes a -R’NC(=N)-NR”R”’ end group or a - R’NC(=N)- NR”- linking group, as these phrases are defined hereinabove, where R’, R" and R'" are as defined herein.

The term “hydrazine” describes a -NR’-NR”R’” end group or a -NR’ -NR”- linking group, as these phrases are defined hereinabove, with R’, R”, and R'" as defined herein.

As used herein, the term “hydrazide” describes a -C(=O)-NR’-NR”R”’ end group or a - C(=O)-NR’-NR”- linking group, as these phrases are defined hereinabove, where R’, R” and R’” are as defined herein.

As used herein, the term “thiohydrazide” describes a -C(=S)-NR’-NR”R”’ end group or a -C(=S)-NR’-NR”- linking group, as these phrases are defined hereinabove, where R’, R” and R’” are as defined herein.

The term “cyanurate” describes

end group

linking group, with R’ and R’ ’ as defined herein.

The term “isocyanurate” describes an

linking group, with R’ and R’ ’ as defined herein.

linking group, with R’ and R’ ’ as defined herein.

As used herein, the term “alkylene glycol” describes a -O-[(CR’R”)_Z-O]y-R”’ end group or a -O-[(CR’R”)_Z-O]y- linking group, with R’, R” and R’” being as defined herein, and with z being an integer of from 1 to 10, preferably, from 2 to 6, more preferably 2 or 3, and y being an integer of 1 or more. Preferably R’ and R” are both hydrogen. When z is 2 and y is 1, this group is ethylene glycol. When z is 3 and y is 1, this group is propylene glycol. When y is 2-4, the alkylene glycol is referred to herein as oligo(alkylene glycol).

Herein, an “ethoxylated” material describes an acrylic or methacrylic compound which comprises one or more alkylene glycol groups, or, preferably, one or more alkylene glycol chains, as defined herein. Ethoxylated (meth)acrylate materials can be mono-functional, or, preferably, multi-functional, namely, di-functional, tri-functional, tetrafunctional, etc.

In multi-functional materials, typically, each of the (meth)acrylate groups are linked to an alkylene glycol group or chain, and the alkylene glycol groups or chains are linked to one another through a branching unit, such as, for example, a branched alkyl, cycloalkyl, aryl (e.g., Bisphenol A), etc.

In some embodiments, the ethoxylated material comprises at least one, or at least two ethoxylated group(s), that is, at least one or at least two alkylene glycol moieties or groups. Some or all of the alkylene glycol groups can be linked to one another to form an alkylene glycol chain. For example, an ethoxylated material that comprises 30 ethoxylated groups can comprise a chain of 30 alkylene glycol groups linked to one another, two chains, each, for example, of 15 alkylene glycol moieties linked to one another, the two chains linked to one another via a branching moiety, or three chains, each, for example, of 10 alkylene glycol groups linked to one another, the three chains linked to one another via a branching moiety. Shorter and longer chains are also contemplated.

The ethoxylated material can comprise one, two or more alkylene glycol chains, of any length.

The term “branching unit” as used herein describes a multi-radical, preferably aliphatic or alicyclic group. By “multi-radical” it is meant that the unit has two or more attachment points such that it links between two or more atoms and/or groups or moieties.

In some embodiments, the branching unit is derived from a chemical moiety that has two, three or more functional groups. In some embodiments, the branching unit is a branched alkyl or a cycloalkyl (alicyclic) or an aryl (e.g., phenyl) as defined herein.

As used herein, the phrase “impact resistance”, which is also referred to interchangeably, herein and in the art, as “impact strength” or simply as “impact”, describes the resistance of a material to fracture by a mechanical impact, and is expressed in terms of the amount of energy absorbed by the material before complete fracture. Impact resistance can be measured using, for example, the ASTM D256-06 standard Izod impact testing (also known as “Izod notched impact”, or as “Izod impact”), and/or as described hereinunder, and is expressed as J/m.

As used herein, HDT refers to a temperature at which the respective formulation or combination of formulations deforms under a predetermined load at some certain temperature. Suitable test procedures for determining the HDT of a formulation or combination of formulations are the ASTM D-648 series, particularly the ASTM D-648-06 and ASTM D-648-07 methods. In various exemplary embodiments of the invention the core and shell of the structure differ in their HDT as measured by the ASTM D-648-06 method as well as their HDT as measured by the ASTM D-648-07 method. In some embodiments of the present invention the core and shell of the structure differ in their HDT as measured by any method of the ASTM D-648 series. In the majority of the examples herein, HDT at a pressure of 0.45 MPa was used.

Herein, "Tg" of a material refers to glass transition temperature defined as the location of the local maximum of the E" curve, where E" is the loss modulus of the material as a function of the temperature.

Broadly speaking, as the temperature is raised within a range of temperatures containing the Tg temperature, the state of a material, particularly a polymeric material, gradually changes from a glassy state into a rubbery state.

Herein, "Tg range" is a temperature range at which the E" value is at least half its value (e.g., can be up to its value) at the Tg temperature as defined above.

Without wishing to be bound to any particular theory, it is assumed that the state of a polymeric material gradually changes from the glassy state into the rubbery within the Tg range as defined above. The lowest temperature of the Tg range is referred to herein as Tg(low) and the highest temperature of the Tg range is referred to herein as Tg(high).

Herein throughout, whenever a curable material is defined by a property of a hardened material obtained therefrom, it is to be understood that this property is for a hardened material obtained from this curable material per se.

By “Tensile strength” it is meant the maximum stress that a material can withstand while being stretched or pulled before breaking. Tensile strength may be determined, for example, according to ASTM D-638-03.

By “Tensile modulus” it is meant the stiffness of a material, defined as the relationship between stress (force per unit area) and strain (proportional deformation) in a material in the linear elasticity regime of a uniaxial deformation. Tensile modulus may be determined, for example, according to ASTM D-638-04. By “flexural strength” or “flexural stress” it is meant the stress in a material just before it yields in a flexure test. Flexural strength may be determined, for example, according to ASTM D- 790-03, unless otherwise indicated.

By “flexural modulus” or “flexural Y modulus” it is meant the ratio of stress to strain in flexural deformation, which is determined from the slope of a stress-strain curve produced by a flexural test such as the ASTM D790. Flexural modulus may be determined, for example, according to ASTM D-790-04, unless otherwise indicated.

According to some embodiments, flexural strength and flexural modulus are determined in accordance to ISO 20795-1(8.5).

“Fracture toughness properties” as used herein described, for example, Maximum Strength intensity factor or Kmax and Total Fracture Work or Wf, which determine the resistance of the printed object to crack propagation, and are determined according to ISO 20795-1.

Herein throughout, unless otherwise indicated, viscosity values are provided for a viscosity of a material or a formulation when measured at 25 °C on a Brookfield’s viscometer. Measured values are provided in centipoise units, which correspond to mPa/second units.

By “transparent curable formulation” it is meant a curable formulation, as defined herein, which provides, when hardened, a transparent material. Such a formulation is also referred to herein as “clear” formulation, and encompasses formulations that are devoid of pigments, as described herein.

The term “transparent” describes a property of a hardened material that reflects the transmittance of light therethrough. A transparent material is typically characterized as capable of transmitting at least 70 % of a light that passes therethrough, or by transmittance of at least 70 %. Transmittance of a material can be determined using methods well known in the art.

A transparent curable formulation as described herein can be transparent also before it is hardened.

A transparent curable formulation as described herein can be characterized as colorless and/or by color properties as determined by the L*a*b* scale, as described hereinafter for a hardened material.

EXAMPLE 3

Exemplified Workflow

Following is a description of a workflow that is suitable for fabricating an object assembly, according to some embodiments of the present invention. The workflow is illustrated schematically in FIG. 13, and is described for the case in which the object assembly is a denture structure, wherein the object parts have shapes of teeth and gingiva, but the skilled person, provided with the details described herein would know how to adapt this workflow for other shapes of object assemblies.

The input 1301 to the workflow includes an object shell dataset for each of the two object parts (gingiva and teeth, in the present example). When the datasets do not include optical information, an additional input 1302 which includes the optical properties of the two object parts is received separately. In this case, the received optical properties are assigned to the object shell datasets. This can be done by loading the object shell datasets to a graphical user interface (GUI) and selecting a desired optical property (e.g. , from a predefined list of optical properties) separately for each object part. Alternatively, the object shell datasets can be received already with previously- assigned optical properties to their dataset elements.

Once the datasets, including the optical information, are obtained, the inner and outer regions of each object part are defined 1303. Optimally, the two parts are assembled 1304 in a manner that one object part (the teeth in the present example) is partially embedded in the other object part (the gingiva in the present example). Portions of regions that are outer in each part but internal in the assembly are identified 1305, as further detailed hereinabove. These portions are then re-defined 1306 as belonging to the inner region of the assembly. In some embodiments of the present invention air gaps in the assembly between the two object parts are identified 1307. A bridging geometry dataset that includes all the identified air gaps is created 1308, and the dataset elements of the bridging geometry are defined 1309 as belonging to the inner region of the assembly. All the inner regions are then optionally and preferably combined into a single region and an inner region dataset is created 1310. The obtained datasets are subjected to a slicing operation 1311 which generates slice data slice data describing a plurality of slices, each slice being defined over a plurality of voxels, wherein each voxel is assigned with a building material formulation. The generated slice data are transmitted to an AM system for fabricating a plurality of layers respectively corresponding to the slices.

Although the invention has been described in conjunction with specific embodiments thereof, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art. Accordingly, it is intended to embrace all such alternatives, modifications and variations that fall within the spirit and broad scope of the appended claims.

It is the intent of the applicant(s) that all publications, patents and patent applications referred to in this specification are to be incorporated in their entirety by reference into the specification, as if each individual publication, patent or patent application was specifically and individually noted when referenced that it is to be incorporated herein by reference. In addition, citation or identification of any reference in this application shall not be construed as an admission that such reference is available as prior art to the present invention. To the extent that section headings are used, they should not be construed as necessarily limiting. In addition, any priority document(s) of this application is/are hereby incorporated herein by reference in its/their entirety.

Claims

WHAT IS CLAIMED IS:

1. A method of encoding data for additive manufacturing, comprising: receiving a first computer object shell dataset and a second computer object shell dataset, respectively describing geometries and optical property assignments of a first object part and a second object part; obtaining a combined dataset describing an object assembly representing a partial embedding of said first object part in said second object part; and updating optical property assignment for said combined dataset by replacing optical property assignment for each dataset element corresponding to a portion of a respective object part which is external in said object part but internal in said object assembly.

2. The method according to claim 1, wherein at least one of said computer object shell datasets describes an object part having an inner region encapsulated by an outer region, and the method comprises replacing optical property assignment for each dataset element corresponding to a portion of said outer region which is internal in said object assembly.

3. The method according to claim 1 , wherein at least one of said computer object shell datasets describes an object part having a core region enclosed by a plurality of encapsulating regions defining an onion-like structure for said object part, and the method comprises replacing optical property assignment for each dataset element corresponding to a portion of at least one encapsulating region which is internal in said object assembly.

4. The method according to any of claims 1-3, wherein said replacing said optical property assignment is such as to increase an opacity level of said portion of said respective object part.

5. The method according to any of claims 1-4, comprising slicing said combined dataset into a plurality of slices, each defined over a plurality of voxels, and assigning for each voxel of each slice, a building material formulation corresponding to optical property assignments of said combined dataset following said update.

6. The method according to claim 5, comprising transmitting said plurality of slices to a controller of an additive manufacturing system for additive manufacturing of a plurality of layers respectively corresponding to said plurality of slices.

7. The method according to any of claims 1-6, wherein said replacing said optical property assignments comprises substituting a colorless or colored optical property with a substitute optical property, wherein an amount of white portion in said substitute optical property is higher than an amount of white portion in said colorless or colored optical property.

8. The method according to any of claims 1-7, comprising receiving a first geometry dataset describing a first geometry of said first object part, a second geometry dataset describing a second geometry of said second object part, presenting said first and said second geometry datasets on a graphical user interface (GUI), and selecting, using said GUI, at least one optical property for each geometry dataset, thereby generating said first and said second computer object shell datasets.

9. The method according to any of claims 1-8, comprising, prior to said updating, using said computer object shell datasets for defining external and internal regions for each object part, and identifying portions of said external regions that are internal in said object assembly.

10. The method according to any of claims 1-9, comprising identifying dataset elements in said combined dataset that correspond to air gaps between said object parts, wherein said updating said optical property assignment comprises assigning a predetermined optical property for each identified dataset element.

11. A method of encoding data for additive manufacturing, comprising: receiving slice data describing a plurality of slices, each slice being defined over a plurality of voxels, and each voxel being assigned with a building material formulation; applying image processing to each slice, to identify in said slice regions corresponding to a layer of a first object part and a layer of a second object, wherein said layer of said first object part is at least partially embedded in said layer of said second object part; and updating building material assignments for at least one of said slices by replacing material assignment for each voxel corresponding to a portion of a respective object part which is external in said object part but internal within said slice.

12. The method according to claim 11, further comprising constructing, based on said identification, a first computer object shell dataset describing a three-dimensional geometry and building material assignments of said first object part, a second computer object shell dataset describing a three-dimensional geometry and building material assignments of said second object part, and a combined computer object shell dataset describing a three-dimensional geometry and building material assignments of an object assembly representing a partial embedding of said first object part in said second object part, wherein said updating of said building material assignments for said at least one slice is executed by replacing material assignment for voxels corresponding to a portion of a respective object part which are external in said object part but internal in said object assembly.

13. The method according to any of claims 11 and 12, wherein at least one of said first and said second object parts has an inner region encapsulated by an outer region, and the method comprises replacing material assignment for each voxel corresponding to a portion of said outer region which is internal in said slice.

14. The method according to any of claims 11 and 12, wherein at least one of said object parts has a core region enclosed by a plurality of encapsulating regions defining an onionlike structure for said object part, and the method comprises replacing material assignment for each voxel corresponding to a portion of at least one encapsulating region which is internal in said slice.

15. The method according to any of claims 11-14, wherein said replacing said material assignment is such as to increase an opacity level of said portion of said respective object part.

16. The method according to any of claims 11-15, comprising, following said update of said building material assignments, transmitting said plurality of slices to a controller of an additive manufacturing system for additive manufacturing of a plurality of layers respectively corresponding to said plurality of slices.

17. The method according to any of claims 1-16, wherein said first object part has a shape of a tooth or a plurality of teeth, and said second object part has a shape of a gingiva.

18. The method according to any of claims 1-17, wherein said replacing said material assignments comprises substituting a colorless or colored building material formulation with a substitute building material formulation, wherein an amount of white coloring agent in said substitute building material formulation is higher than an amount of white coloring agent in said colorless or colored building material formulation.

19. The method according to claim 18, wherein said colorless or colored building material formulation is colorless.

20. The method according to any of claims 18 and 19, wherein said colorless or colored building material formulation is a colored building material formulation comprising a coloring agent other than a white coloring agent.

21. A computer software product, comprising a computer-readable medium in which program instructions are stored, which instructions, when read by a data processor, cause the data processor to execute the method according to any of claims 1-20.