Photopolymerizable compositions, articles, and methods comprising a urethane component and a reactive diluent

Abstract

The present disclosure provides a photopolymerizable composition comprising 50% to 90% by weight of at least one urethane component, 5% to 50% by weight of at least one reactive diluent, 0.1% to 5% by weight of a photoinitiator, and optionally, an inhibitor, the composition having a viscosity of 10 Pa·s or less at a temperature of 40°C, as determined using a magnetic bearing rheometer with a 40 mm cone-plate measurement system at a shear rate of 0.1 [1 / s]. The present disclosure also provides an article comprising a reaction product of the photopolymerizable composition, the article exhibiting an elongation at break of 25% or more. Furthermore, the present disclosure provides a method for making an article, the method comprising: (i) providing a photopolymerizable composition; and (ii) selectively curing the photopolymerizable composition to form an article. The method also optionally includes (iii) curing any unpolymerized urethane component and / or reactive diluent remaining after step (ii). Additionally, a method is provided that includes receiving, by a manufacturing device having one or more processors, a digital object including data defining an article, and generating, using the manufacturing device by an additive manufacturing process, an article based on the digital object. Also provided is a system that includes a display that displays a 3D model of the article, and one or more processors that cause a 3D printer to create a physical object of the article in response to the 3D model selected by a user.

Description

[Technical Field]

[0001] FIELD OF THE DISCLOSURE The present disclosure relates generally to articles comprising a urethane component and at least one reactive diluent, and methods of making the articles, for example, additive manufacturing methods. [Background technology]

[0002] The use of stereolithography and inkjet printing to produce three-dimensional articles has been known for a relatively long time, and these processes are commonly referred to as 3D printing (or additive manufacturing) methods. In bath polymerization techniques (stereolithography being one type of bath polymerization technique), a desired 3D article is fabricated from a liquid curable composition using two alternating successive steps. In the first step, a layer of the liquid curable composition, one of whose boundaries is the surface of the composition, is cured with appropriate radiation at the height of this layer and in a surface region corresponding to the desired cross-sectional area of ​​the molded article to be formed. In the second step, the cured layer is covered with a new layer of liquid curable composition, and this series of steps is repeated until a so-called green body (i.e., a gelled article) of the desired shape is achieved. This green body is often not yet fully cured and typically requires post-curing. The mechanical strength of the green body immediately after curing is also known as green strength and is relevant for subsequent processing of the printed article.

[0003] Other 3D printing technologies use ink jetted as a liquid through a printhead to form various three-dimensional objects. During operation, the printhead may deposit a curable photopolymer layer by layer. Some jet printers deposit the polymer with a support material or binder. In some instances, the build material is solid at room temperature and changes to a liquid when raised to the jetting temperature. In other instances, the build material is liquid at room temperature.

[0004] One particularly attractive opportunity for 3D printing is the direct formation of clear tray aligners for orthodontic treatment. These trays, also known as aligners or polymer or shell appliances, come in sets and are intended to be worn continuously over several months to gradually move teeth in incremental steps toward a desired target position. Some types of clear tray aligners have a row of tooth-shaped receptacles that receive each tooth in the patient's dental arch, with the receptacles oriented slightly differently from one appliance to the next to incrementally move each tooth toward the desired target position via the elastic properties of the polymer material. Various methods have been proposed to manufacture clear tray aligners and other elastic appliances. Typically, additive manufacturing methods, such as the aforementioned stereolithography, are used to create positive arch models for each dental arch. A sheet of polymer material is then placed over each arch model and formed to fit the model teeth in each model arch using heat, pressure, and / or negative pressure. The formed sheet is cleaned, trimmed as necessary, and the resulting arch-shaped appliance is shipped to a treating professional along with the desired number of other appliances.

[0005] Aligners or other elastic appliances formed directly by 3D printing would eliminate the need to print arch molds and then thermoform the appliances. Furthermore, new aligner designs would become possible, allowing for greater flexibility in treatment planning. Exemplary methods for directly printing clear tray aligners and other elastic orthodontic appliances are described in PCT Publications WO 2016 / 109660 (Raby et al.), WO 2016 / 148960 (Cinader et al.), and WO 2016 / 149007 (Oda et al.), as well as U.S. Patent Publications 2011 / 0091832 (Kim, et al.) and 2013 / 0095446 (Kitching). Summary of the Invention

[0006] Existing printable / polymerizable resins tend to be too brittle (e.g., low elongation, short-chain crosslinking, thermosetting compositions, and / or high glass transition temperatures) for elastic oral appliances such as aligners. Aligners or other appliances made with such resins can easily break in a patient's mouth during treatment, creating pieces of material that can abrade or puncture exposed tissue or be swallowed. Such breakage can, at a minimum, interrupt treatment and have serious health consequences for the patient. Therefore, a need exists for curable liquid resin compositions that are compatible and suitable for forming elastomeric articles using 3D printing (e.g., additive manufacturing) methods. Preferably, curable liquid resin compositions used in bath polymerization 3D printing processes have low viscosity, adequate cure rates, and excellent mechanical properties, both in the final cured article. In contrast, compositions for inkjet printing processes need to be much lower viscosities so they can be jetted through a nozzle, which is not the case with most bath polymerization resins.

[0007] Urethane (meth)acrylates are a class of raw materials with interesting properties, such as elongation of over 100% when cured and very high toughness. However, these resins also have very high viscosities and are essentially solid at room temperature. Therefore, urethane (meth)acrylates are only used in small amounts in photopolymer formulations for liquid vat polymerization or stereolithography, and the properties of these resins are affected by other components.

[0008] In a first aspect, a photopolymerizable composition is provided. The photopolymerizable composition comprises: (a) 50% to 90% by weight (inclusive) of at least one urethane component; and (b) 5% to 50% by weight (inclusive) of at least one reactive diluent. The photopolymerizable composition further comprises: (c) 0.1% to 5% by weight (inclusive) of a photoinitiator; and (d) an optional inhibitor, if present, in an amount of 0.001% to 1% by weight (inclusive), based on the total weight of the photopolymerizable composition. Often, the photopolymerizable composition has a viscosity of 10 Pa·s or less at a temperature of 40°C, as determined using a magnetic bearing rheometer using a 40 mm cone-plate measuring system at a shear rate of 0.1 1 / s.

[0009] In a second aspect, an article is provided. The article comprises the reaction product of a photopolymerizable composition comprising: (a) 50% to 90% by weight, inclusive, of at least one urethane component; and (b) 5% to 50% by weight, inclusive, of at least one reactive diluent. The photopolymerizable composition further comprises: (c) 0.1% to 5% by weight, inclusive, of a photoinitiator; and (d) an optional inhibitor, when present, in an amount of 0.001% to 1% by weight, inclusive, based on the total weight of the photopolymerizable composition. Typically, the article exhibits an elongation at break of 25% or greater.

[0010] In a third aspect, a method for making an article is provided. The method includes (i) providing a photopolymerizable composition and (ii) selectively curing the photopolymerizable composition to form an article. The method also optionally includes (iii) curing any unpolymerized urethane component and / or reactive diluent remaining after step (ii). The photopolymerizable composition includes, based on the total weight of the photopolymerizable composition, (a) 50% to 90% by weight, inclusive, of at least one urethane component; (b) 5% to 50% by weight, inclusive, of at least one reactive diluent; (c) 0.1% to 5% by weight, inclusive, of a photoinitiator; and (d) optional inhibitors, when present, in an amount of 0.001% to 1% by weight, inclusive.

[0011] In a fourth aspect, a non-transitory machine-readable medium is provided. The non-transitory machine-readable medium has data representing a three-dimensional model of an article, and when accessed by one or more processors interfaced with a 3D printer, causes the 3D printer to produce the article. The article comprises the reaction product of a photopolymerizable composition comprising: (a) 50% to 90% by weight, inclusive, of at least one urethane component; and (b) 5% to 50% by weight, inclusive, of at least one reactive diluent. The photopolymerizable composition further comprises: (c) 0.1% to 5% by weight, inclusive, of a photoinitiator; and (d) an optional inhibitor, when present, in an amount of 0.001% to 1% by weight, inclusive, based on the total weight of the photopolymerizable composition. The article exhibits an elongation at break of 25% or greater.

[0012] In a fifth aspect, a method is provided. The method includes retrieving data representing a 3D model of an article from a non-transitory machine-readable medium, executing, by one or more processors, a 3D printing application that interfaces with a manufacturing device using the data, and generating, by the manufacturing device, a physical object of the article. The article comprises the reaction product of a photopolymerizable composition including: (a) 50% to 90% by weight, inclusive, of at least one urethane component; and (b) 5% to 50% by weight, inclusive, of at least one reactive diluent. The photopolymerizable composition further includes: (c) 0.1% to 5% by weight, inclusive, of a photoinitiator; and (d) optional inhibitors, when present, in an amount of 0.001% to 1% by weight, inclusive, based on the total weight of the photopolymerizable composition. The article exhibits an elongation at break of 25% or greater.

[0013] In a sixth aspect, another method is provided. The method includes receiving, by a manufacturing device having one or more processors, a digital object including data defining multiple layers of an article, and generating an article based on the digital object using the manufacturing device via an additive manufacturing process. The article includes the reaction product of a photopolymerizable composition including: (a) 50% to 90% by weight, inclusive, of at least one urethane component; and (b) 5% to 50% by weight, inclusive, of at least one reactive diluent. The photopolymerizable composition further includes: (c) 0.1% to 5% by weight, inclusive, of a photoinitiator; and (d) an optional inhibitor, when present, in an amount of 0.001% to 1% by weight, inclusive, based on the total weight of the photopolymerizable composition. The article exhibits an elongation at break of 25% or greater.

[0014] In a seventh aspect, a system is provided. The system includes a display that displays a 3D model of an article and one or more processors that cause a 3D printer to create a physical object of the article in response to a 3D model selected by a user. The article includes the reaction product of a photopolymerizable composition that includes: (a) 50% to 90% by weight, inclusive, of at least one urethane component; and (b) 5% to 50% by weight, inclusive, of at least one reactive diluent. The photopolymerizable composition further includes: (c) 0.1% to 5% by weight, inclusive, of a photoinitiator; and (d) an optional inhibitor, when present, in an amount of 0.001% to 1% by weight, inclusive, based on the total weight of the photopolymerizable composition. The article exhibits an elongation at break of 25% or greater.

[0015] Transparent tray aligners and drawbars made in accordance with at least certain embodiments of the present disclosure have been found to exhibit low brittleness, good resistance to water, and good toughness.

[0016] The above summary of the present disclosure is not intended to describe each disclosed embodiment or every implementation of the present disclosure. The following description more particularly exemplifies exemplary embodiments. In several places throughout this application, guidance is provided by listing examples, which examples can be used in various combinations. In each instance, the recited listings serve only as a representative group and should not be interpreted as an exclusive listing. [Brief explanation of the drawings]

[0017] [Figure 1] FIG. 1 is a flow diagram of a process for constructing an article using the photopolymerizable composition disclosed herein. [Figure 2] FIG. 1 is a generalized schematic diagram of a stereolithography apparatus. [Figure 3] FIG. 1 is an isometric view of a printed transparent tray aligner according to one embodiment of the present disclosure. [Figure 4] FIG. 1 is a flow diagram of a process for manufacturing printed orthodontic appliances according to the present disclosure. [Figure 5] 1 is a generalized schematic diagram of an apparatus in which radiation is directed through a container. [Figure 6] FIG. 6 is a block diagram of a generalized system 600 for additive manufacturing of an article. [Figure 7] FIG. 1 is a block diagram of a generalized manufacturing process for an article. [Figure 8] FIG. 1 is a high-level flow diagram of an exemplary article manufacturing process. [Figure 9] FIG. 1 is a high-level flow diagram of an exemplary additive manufacturing process for an article. [Figure 10] 1 is a schematic front view of an exemplary computing device 1000. FIG.

[0018] While the above-identified figures illustrate several embodiments of the present disclosure, other embodiments are also contemplated as noted herein. The figures are not necessarily drawn to scale. In all cases, this disclosure presents the invention by way of representation and not limitation. It is to be understood that numerous other modifications and embodiments can be devised by those skilled in the art which are within the scope and spirit of the principles of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0019] As used herein, the term "hardenable" refers to a material that can be hardened or solidified, such as by heating to remove solvent or by heating to cause polymerization, chemical crosslinking, or radiation-induced polymerization or crosslinking.

[0020] As used herein, "curing" means hardening or partially hardening a composition by any mechanism, such as, for example, heat, light, radiation, electron beam, microwave, chemical reaction, or a combination thereof.

[0021] As used herein, "cured" refers to a material or composition that has been hardened or partially hardened (e.g., polymerized or crosslinked) by curing.

[0022] As used herein, "integral" refers to being made at the same time or not being able to be separated without damaging one or more of the (integral) parts.

[0023] As used herein, the term "(meth)acrylate" is an abbreviation for acrylate, methacrylate, or a combination thereof, and "(meth)acrylic" is an abbreviation for acrylic, methacrylic, or a combination thereof. As used herein, a "(meth)acrylate-functional compound" is, among other things, a compound that includes a (meth)acrylate moiety.

[0024] As used herein, "non-crosslinkable" refers to a polymer that does not undergo crosslinking when exposed to actinic radiation or high heat. Typically, a non-crosslinkable polymer is a non-functionalized polymer that lacks functional groups that participate in crosslinking.

[0025] As used herein, "oligomer" refers to a molecule that has one or more properties that change upon the addition of a single additional repeating unit.

[0026] As used herein, "polymer" refers to a molecule that has one or more properties that do not change upon the addition of a single further repeating unit.

[0027] As used herein, "polymerizable composition" refers to a curable composition that can be polymerized upon initiation (e.g., upon initiation of free radical polymerization). Typically, prior to polymerization (e.g., hardening), the polymerizable composition has a viscosity profile consistent with the requirements and parameters of one or more 3D printing systems. For example, in some embodiments, hardening involves exposure to actinic radiation having sufficient energy to initiate a polymerization or crosslinking reaction. For example, in some embodiments, ultraviolet (UV) radiation, electron beam radiation, or both can be used.

[0028] As used herein, "resin" includes all polymerizable components (monomers, oligomers, and / or polymers) present in a curable composition. A resin may contain only one polymerizable component compound or a mixture of different polymerizable compounds.

[0029] As used herein, "thermoplastic" refers to a polymer that flows when heated sufficiently above its glass transition point and becomes solid when cooled.

[0030] As used herein, "thermoset" refers to a polymer that is permanently set upon curing and does not flow upon subsequent application of heat. Thermoset polymers are typically crosslinked polymers.

[0031] As used herein, "occlusal" means in a direction toward the outer tips of the patient's teeth, "facial" means in a direction toward the patient's lips or cheeks, and "lingual" means in a direction toward the patient's tongue.

[0032] The words "preferred" and "preferably" refer to embodiments of the present disclosure that may offer certain benefits, under certain circumstances, although other embodiments may also be preferred, under the same or other circumstances. Furthermore, the recitation of one or more preferred embodiments does not imply that other embodiments are not useful, and is not intended to exclude other embodiments from the scope of the present disclosure.

[0033] In this application, terms such as "a," "an," and "the" are not intended to refer only to a singular entity, but include general classes, specific examples of which may be used for illustration. The terms "a," "an," and "the" are used interchangeably with the term "at least one." The phrases "at least one of" and "including at least one of" following a list refer to any one of the items in the list, and any combination of two or more items in the list.

[0034] As used herein, the term "or" is generally used in its ordinary sense including "and / or" unless the content clearly dictates otherwise.

[0035] The term "and / or" means one or all of the listed elements or a combination of any two or more of the listed elements.

[0036] Also, herein, all numbers are intended to be modified by the term "about," and preferably by the term "exactly." When used herein with respect to a measured quantity, the term "about" refers to the variation in the measured quantity that may be expected by one of ordinary skill in the art exercising a degree of care commensurate with the measurement, the purpose of the measurement, and the precision of the measuring device used. Also, herein, the recitation of numerical ranges by endpoints includes all numbers subsumed within that range and those endpoints (e.g., 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, 5, etc.).

[0037] When used herein as a modifier to a characteristic or attribute, the term "generally," unless otherwise specified, means that the characteristic or attribute would be readily recognized by one of ordinary skill in the art, but does not require absolute precision or perfect agreement (e.g., within + / - 20% for quantifiable characteristics). The term "substantially," unless otherwise specified, means a close approximation (e.g., within + / - 10% for quantifiable characteristics), but again, does not require absolute precision or perfect agreement. Terms such as identical, equal, uniform, constant, exactly, etc., are understood to not require absolute precision or perfect agreement, but rather within normal tolerances or measurement error applicable to the particular situation.

[0038] In a first aspect, the present disclosure provides a photopolymerizable composition, the photopolymerizable composition comprising, based on the total weight of the photopolymerizable composition: (a) 50% to 90% by weight (inclusive) of at least one urethane component; (b) 5% to 50% by weight (inclusive) of at least one reactive diluent; (c) 0.1 wt % to 5 wt % (inclusive) of a photoinitiator; and (d) an optional inhibitor, if present, in an amount of 0.001% to 1% by weight, inclusive; Components (a) to (d) are described in detail below.

[0039] Urethane component The photopolymerizable compositions of the present disclosure include at least one urethane component. As used herein, "urethane component" refers to a compound that includes one or more carbamate functional groups in the backbone of the compound. In certain embodiments, the carbamate functional group is represented by Formula I: -N(H)-C(O)O- I It consists of:

[0040] Urethanes are prepared by the reaction of isocyanates with alcohols to form carbamate linkages. Furthermore, the term "polyurethane" has become more commonly used to refer to the reaction product of a polyisocyanate with any polyactive hydrogen compound, including polyfunctional alcohols, amines, and mercaptans.

[0041] The at least one urethane component provides both toughness (e.g., at least a minimum tensile strength and / or modulus) and flexibility (e.g., at least a minimum elongation at break) to the final article. In some embodiments, in addition to the urethane functional group, the urethane component further comprises one or more functional groups selected from hydroxyl groups, carboxyl groups, amino groups, and siloxane groups. These functional groups can react with other components of the photopolymerizable composition during polymerization. The at least one urethane component often comprises a urethane (meth)acrylate, a urethane acrylamide, or a combination thereof, and the at least one urethane component comprises a linking group selected from alkyl, polyalkylene, polyalkylene oxide, aryl, polycarbonate, polyester, polyamide, and combinations thereof. As used herein, "linking group" refers to a functional group connecting two or more urethane groups. The linking group may be divalent, trivalent, or tetravalent. In selected embodiments, the at least one urethane component comprises a urethane (meth)acrylate comprising a polyalkylene oxide linking group, a polyamide linking group, or a combination thereof.

[0042] For example, the polymerizable component can include a multifunctional urethane acrylate or urethane methacrylate. These urethane (meth)acrylates are known to those skilled in the art and can be prepared by known methods, for example, by reacting a hydroxyl-terminated polyurethane with acrylic acid, methacrylic acid, or isocyanatoethyl methacrylate, or by reacting an isocyanate-terminated prepolymer with a hydroxyalkyl (meth)acrylate to obtain a urethane (meth)acrylate. Suitable processes are disclosed, inter alia, in U.S. Patent Nos. 8,329,776 (Hecht et al.) and 9,295,617 (Cub et al.). Suitable urethane methacrylates can include PEGDMA (polyethylene glycol dimethacrylate having a molecular weight of about 400), aliphatic urethane methacrylate, aliphatic polyester urethane methacrylate, and aliphatic polyester triurethane acrylate.

[0043] Typically, the urethane component has a number average molecular weight (Mn) of 200 grams / mole to 5,000 grams / mole. The number average molecular weight can be measured by matrix-assisted laser deposition ionization mass spectrometry (MALDI). As used herein, "urethane component" optionally includes each of "high Mn urethane component" and "low Mn urethane component." High Mn urethane components include compounds that contain one or more urethane functional groups in the backbone of the compound and have a number average molecular weight of 1,000 grams / mole (g / mol) or greater, provided that all branches from the backbone of the compound, if present, have an Mn of 200 g / mol or less. In other words, the high Mn urethane component typically has a Mn content of 1,000 g / mol or more, 1,100 g / mol or more, 1,200 g / mol or more, 1,300 g / mol or more, 1,400 g / mol or more, 1,500 g / mol or more, 1,600 g / mol or more, 1,700 g / mol or more, 1,800 g / mol or more, 2,000 g / mol or more, 2,250 g / mol or more, 2,500 g / mol or more, 2,750 g / mol or more, 3,000 g / mol or more, 3,250 g / mol or more, 3,500 g / mol or more, 3, It has a Mn of 7500 g / mol or more, or even 4,000 g / mol or more, and a Mn of 5,000 g / mol or less, 4,800 g / mol or less, 4,600 g / mol or less, 4,400 g / mol or less, 4,100 g / mol or less, 3,900 g / mol or less, 3,700 g / mol or less, 3,400 g / mol or less, 3,100 g / mol or less, 2,900 g / mol or less, 2,700 g / mol or less, 2,400 g / mol or less, or 2,200 g / mol or less, or even 1,900 g / mol or less.

[0044] Low Mn urethane components include compounds containing one or more urethane functional groups in the backbone of the compound and have either 1) a number average molecular weight of 100 g / mol or more and less than 1,000 g / mol, or 2) a number average molecular weight of 100 g / mol or more and less than 2,000 g / mol, provided that the number average molecular weight of any one or more linear segments between two reactive groups and / or branches is less than 1,000 g / mol. For example, a branched urethane component may have a total Mn of more than 1,000 g / mol, but still be a low Mn urethane component by having a linear segment between two branch points with an Mn of less than 1,000 g / mol. In other words, 1) the category of low Mn urethane components is usually 100 g / mol or more, 150 g / mol or more, 200 g / mol or more, 250 g / mol or more, 300 g / mol or more, 350 g / mol or more, 400 g / mol or more, 450 g / mol or more, 500 g / mol or more, 550 g / mol or more, 600 g / mol or more, 650 g / mol or more, 700 g / mol or more, 750 g / mol or more, or has a Mn of 800 g / mol or more and less than 1,000 g / mol, 975 g / mol or less, 925 g / mol or less, 875 g / mol or less, 825 g / mol or less, 775 g / mol or less, 725 g / mol or less, 675 g / mol or less, 625 g / mol or less, 575 g / mol or less, 525 g / mol or less, 475 g / mol or less, or 425 g / mol or less, or even 375 g / mol or less.2) The low Mn urethane component category is usually 200 g / mol or more, 250 g / mol or more, 300 g / mol or more, 350 g / mol or more, 400 g / mol or more, 450 g / mol or more, 500 g / mol or more, 550 g / mol or more, 600 g / mol or more, 650 g / mol or more, 700 g / mol or more, 750 g / mol or more, or 800 g / mol or more, and 1,500 g / mol or less, 1,400 g / mol or less, 1,300 g / mol or less, mol or less, 1,200 g / mol or less, 1,100 g / mol or less, 1,000 g / mol or less, 975 g / mol or less, 925 g / mol or less, 875 g / mol or less, 825 g / mol or less, 775 g / mol or less, 725 g / mol or less, 675 g / mol or less, 625 g / mol or less, 575 g / mol or less, 525 g / mol or less, 475 g / mol or less, or 425 g / mol or less, or even 375 g / mol or less. Each of the low Mn urethane components in the second category described above includes the proviso that the number average molecular weight of any one or more linear segments between two reactive groups and / or branches is less than 1,000 g / mol, 950 g / mol or less, 900 g / mol or less, 850 g / mol or less, 800 g / mol or less, or 750 g / mol or less, and the number average molecular weight of any one or more linear segments between two reactive groups and / or branches is 100 g / mol or more, 200 g / mol or more, 250 g / mol or more, 300 g / mol or more, 350 g / mol or more, 400 g / mol or more, 450 g / mol or more, or 500 g / mol or more.

[0045] The use of a high Mn urethane component having a number average molecular weight of 1,000 g / mol or greater tends to result in a final article having at least a certain desired minimum elongation at break (e.g., 25% or greater). 80% or more by weight of at least one urethane component is provided by one or more high Mn (e.g., long chain) urethane components. More specifically, in embodiments in which a low molecular weight urethane component is present, typical ratios of high number average molecular weight urethane component to low number average molecular weight urethane component range from 95:5 high Mn urethane component to low Mn urethane component to 80:20 high Mn urethane component to low Mn urethane component. In other words, photopolymerizable compositions according to at least certain embodiments of the present disclosure comprise 80% or more by weight of the total urethane components as the high-Mn urethane component, 85% or more by weight, 87% or more by weight, 90% or more by weight, 92% or more by weight, 95% or more by weight, or even 97% or more by weight of the total urethane components as the high-Mn urethane component, and 100% or less by weight of the total urethane components as the high-Mn urethane component, and 98% or less by weight, 96% or less by weight, 94% or less by weight, 91% or less by weight, 89% or less, or 86% or less by weight of the total urethane components as the high-Mn urethane component. Similarly, photopolymerizable compositions according to at least certain embodiments of the present disclosure may comprise 2% or more by weight of the total urethane components as the low-Mn urethane component, 4% or more, 5% or more, 8% or more, 10% or more, 12% or more, 15% or more, or even 17% by weight of the total urethane components as the low-Mn urethane component, and 20% or less by weight of the total urethane components as the low-Mn urethane component, and 18% or less, 16% or less, 14% or less, 11% or less, 9% or less, 7% or less, 6% or less, or 3% or less by weight of the total urethane components as the low-Mn urethane component.

[0046] According to certain embodiments, the at least one urethane component comprises at least one (meth)acrylate component having a urethane moiety, which may serve to improve the physical properties of the cured composition, such as flexural strength and / or elongation at break. Such urethane components may be characterized by the following features, either singly or in combination: a) comprises at least two, three, or four (meth)acrylate moieties. b) Number average molecular weight (Mn): 1,000 to 5,000 g / mol, or 1,000 to 2,000 g / mol. c) The (meth)acrylate moiety comprises a C1 to C20 straight or branched chain alkyl moiety attached via a urethane moiety. d) Viscosity: 0.1 to 100 Pa·s or 1 to 50 Pa·s at 23°C.

[0047] Combinations of features (a) and (b), or (b) and (c), or (a) and (d) may be preferred.

[0048] Urethane (meth)acrylates can be obtained by many processes known to those skilled in the art. Urethane (meth)acrylates are usually obtained by reacting an NCO-terminated compound with a suitable monofunctional (meth)acrylate monomer, such as hydroxyethyl acrylate, hydroxyethyl methacrylate, or hydroxypropyl methacrylate, preferably hydroxyethyl and hydroxypropyl methacrylate. For example, a polyisocyanate can be reacted with a polyol to form an isocyanate-terminated urethane prepolymer, which is then reacted with a (meth)acrylate, such as 2-hydroxyethyl (meth)acrylate. These types of reactions can be carried out at room temperature or at elevated temperatures, optionally in the presence of a catalyst, such as a tin catalyst or a tertiary amine.

[0049] The polyisocyanate that can be used to form the isocyanate-functional urethane prepolymer can be any organic isocyanate having at least two free isocyanate groups, including aliphatic, cycloaliphatic, aromatic, and araliphatic isocyanates. Any of the known polyisocyanates, such as alkyl and alkylene polyisocyanates, cycloalkyl and cycloalkylene polyisocyanates, and combinations of alkylene and cycloalkylene polyisocyanates, can be used. Preferably, diisocyanates having the formula X(NCO)2 can be used, where X represents an aliphatic hydrocarbon group having 2 to 12 carbon atoms, an alicyclic hydrocarbon group having 5 to 18 carbon atoms, an aromatic hydrocarbon group having 6 to 16 carbon atoms, and / or an aliphatic hydrocarbon group having 7 to 15 carbon atoms.

[0050] Examples of suitable polyisocyanates include 2,2,4-trimethylhexamethylene-1,6-diisocyanate, hexamethylene-1,6-diisocyanate (HDI), cyclohexyl-1,4-diisocyanate, 4,4'-methylene-bis(cyclohexylisocyanate), 1,1'-methylenebis(4-isocyanato)cyclohexane, isophorone diisocyanate, 4,4'-methylenediphenyl diisocyanate, 1,4-tetramethylene diisocyanate, meta- and para-tetra-methylxylene diisocyanate, 1,4-phenylene diisocyanate, 2,6- and 2,4-toluene diisocyanate, 1,5-naphthylene diisocyanate, 2,4' and 4,4'-diphenylmethane diisocyanate, and mixtures thereof.

[0051] It is also possible to use known high-functionality polyisocyanates derived from polyurethane chemistry or other modified polyisocyanates, which contain, for example, carbodiimide, allophanate, isocyanurate, and / or biuret groups. Particularly preferred isocyanates are isophorone diisocyanate, 2,4,4-trimethyl-hexamethylene diisocyanate, and high-functionality polyisocyanates with an isocyanurate structure.

[0052] The isocyanate-terminated urethane compound is end-capped with (meth)acrylate to produce a urethane (meth)acrylate compound. Generally, any (meth)acrylate-type end-capping agent having a terminal hydroxyl group and also having an acrylic or methacrylic moiety can be used, with methacrylic moieties being preferred. Examples of suitable end-capping agents include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, glycerol di(meth)acrylate, and / or trimethylolpropane di(meth)acrylate. Particularly preferred are 2-hydroxyethyl methacrylate (HEMA) and / or 2-hydroxyethyl acrylate (HEA).

[0053] The equivalent ratio of the isocyanate group to the compound reactive with the isocyanate group is 1.1:1 to 8:1, preferably 1.5:1 to 4:1.

[0054] The isocyanate polyaddition reaction can be carried out in the presence of catalysts known from polyurethane chemistry, such as organotin compounds such as dibutyltin dilaurate or amine catalysts such as diazabicyclo[2.2.2]octane. Furthermore, the synthesis can be carried out both in the melt and in a suitable solvent, which can be added before or during prepolymer preparation. Suitable solvents include, for example, acetone, 2-butanone, tetrahydrofuran, dioxane, dimethylformamide, N-methyl-2-pyrrolidone (NMP), ethyl acetate, alkyl ethers of ethylene and propylene glycol, and aromatic hydrocarbons. It is particularly preferred to use ethyl acetate as the solvent.

[0055] According to selected embodiments, urethane dimethacrylates of the following formulae I and II are preferred. [ka] (wherein n is 9 or 10), [ka]

[0056] Examples of commercially available urethane components include those available under the trade names EXOTHANE 108 (e.g., Formula I), EXOTHANE 8, and EXOTHANE 10 (e.g., Formula II) from Esstech Inc., and DESMA from 3M Company. DESMA is described, for example, in paragraph

[0135] and Table 3 of EP 2167013(B1) (Hecht et al.).

[0057] The urethane component is contained in the photopolymerizable composition in an amount of 50 to 90% by weight (inclusive), for example, 60 to 80% by weight (inclusive), based on the total weight of the photopolymerizable composition. Typically, the urethane component is contained in the photopolymerizable composition in an amount of 50% by weight or more, 52% by weight or more, 55% by weight or more, 57% by weight or more, 60% by weight or more, 61% by weight or more, 62% by weight or more, 63% by weight or more, 64% by weight or more, 65% by weight or more, 70% by weight or more, or 72% by weight or more, and 90% by weight or less, 87% by weight or less, 85% by weight or less, 80% by weight or less, 77% by weight or less, or 75% by weight or less, based on the total weight of the photopolymerizable composition.

[0058] Reactive Diluents The photopolymerizable compositions of the present disclosure include at least one reactive diluent. For purposes of reference herein, a "reactive diluent" is a component containing at least one free-radical reactive group (e.g., an ethylenically unsaturated group) that can co-react with at least one urethane component (e.g., undergo addition polymerization). The reactive diluent has a smaller molecular weight than the at least one (e.g., high Mn) urethane component, often less than 400 grams / mole, and does not contain urethane functionality (e.g., does not include any urethane functionality).

[0059] In selected embodiments, the at least one reactive diluent comprises a (meth)acrylate, a polyalkylene oxide di(meth)acrylate, an alkanediol di(meth)acrylate, or a combination thereof, such as a (meth)acrylate.

[0060] Suitable free radically polymerizable reactant diluents include di-, tri-, or other polyacrylates and methacrylates, such as glycerol diacrylate, ethoxylated bisphenol A dimethacrylate (D-zetaacrylate), tetraethylene glycol dimethacrylate (TEGDMA), glycerol triacrylate, ethylene glycol diacrylate, diethylene glycol diacrylate, triethylene glycol dimethacrylate, 1,3-propanediol diacrylate, 1,3-propanediol dimethacrylate, trimethylolpropane triacrylate, 1,2,4-butanetriol trimethacrylate, 1,4-cyclohexanediol diacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, Examples of suitable acrylates include pentaerythritol tetramethacrylate, sorbitol hexaacrylate, bis[1-(2-acryloxy)]-p-ethoxyphenyldimethylmethane, bis[1-(3-acryloxy-2-hydroxy)]-p-propoxyphenyldimethylmethane, and trishydroxyethylisocyanurate trimethacrylate; bisacrylates and bismethacrylates of polyethylene glycols having molecular weights of 200 to 500, copolymerizable mixtures of acrylated monomers such as those described in U.S. Pat. No. 4,652,274 (Boettcher et al.), and acrylated oligomers such as those described in U.S. Pat. No. 4,642,126 (Zador et al.); and polyfunctional (meth)acrylates containing urea or amide groups such as those described in EP 2008636 (Hecht et al.).

[0061] The reactive diluent may comprise one or more poly(meth)acrylates, such as di-, tri-, tetra-, or penta-functional monomeric or oligomeric aliphatic, cycloaliphatic, or aromatic acrylates or methacrylates.

[0062] Examples of suitable aliphatic poly(meth)acrylates having two or more (meth)acrylate groups in the molecule include the triacrylate and trimethacrylate of hexane-2,4,6-triol; glycerol or 1,1,1-trimethylolpropane; ethoxylated or propoxylated glycerol or 1,1,1-trimethylolpropane; and hydroxyl-containing tri(meth)acrylates obtained by reacting triepoxide compounds, such as the triglycidyl ethers of the above triols, with (meth)acrylic acid.Furthermore, it is also possible to use, for example, pentaerythritol tetraacrylate, bistrimethylolpropane tetraacrylate, pentaerythritol monohydroxytriacrylate or methacrylate, or dipentaerythritol monohydroxypentaacrylate or methacrylate.

[0063] Another suitable class of free-radically polymerizable compounds includes aromatic di(meth)acrylate compounds and tri- or higher-functional (meth)acrylate compounds. Tri- or higher-functional meth(acrylates) can be tri-, tetra-, or penta-functional monomeric or oligomeric aliphatic, cycloaliphatic, or aromatic acrylates or methacrylates.

[0064] Examples of suitable aliphatic tri-, tetra-, and pentafunctional (meth)acrylates include the triacrylate and trimethacrylate of hexane-2,4,6-triol; glycerol or 1,1,1-trimethylolpropane; ethoxylated or propoxylated glycerol or 1,1,1-trimethylolpropane; and hydroxyl-containing tri(meth)acrylates obtained by reacting triepoxide compounds, such as the triglycidyl ethers of the above triols, with (meth)acrylic acid.Furthermore, it is also possible to use, for example, pentaerythritol tetraacrylate, bistrimethylolpropane tetraacrylate, pentaerythritol monohydroxytriacrylate or methacrylate, or dipentaerythritol monohydroxypentaacrylate or methacrylate. In some embodiments, the tri(meth)acrylate comprises 1,1-trimethylolpropane triacrylate or methacrylate, ethoxylated or propoxylated 1,1,1-trimethylolpropane triacrylate or methacrylate, ethoxylated or propoxylated glycerol triacrylate, pentaerythritol monohydroxy triacrylate or methacrylate, or tris(2-hydroxyethyl)isocyanurate triacrylate. Further examples of suitable aromatic tri(meth)acrylates are the reaction products of triglycidyl ethers of trihydroxybenzenes containing three hydroxyl groups and phenol or cresol novolac with (meth)acrylic acid.

[0065] In some cases, the reactive diluent comprises a diacrylate and / or dimethacrylate ester of an aliphatic, cycloaliphatic, or aromatic diol, examples of which include 1,3- or 1,4-butanediol, neopentyl glycol, 1,6-hexanediol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, tripropylene glycol, ethoxylated or propoxylated neopentyl glycol, 1,4-dihydroxymethylcyclohexane, 2,2-bis(4-hydroxycyclohexyl)propane or bis(4-hydroxycyclohexyl)methane, hydroquinone, 4,4′-dihydroxybiphenyl, bisphenol A, bisphenol F, bisphenol S, ethoxylated or propoxylated bisphenol A, ethoxylated or propoxylated bisphenol F, or ethoxylated or propoxylated bisphenol S. In some cases, the reactive diluents described herein include one or more higher functional acrylates or methacrylates, such as dipentaerythritol monohydroxypentaacrylate or bis(trimethylolpropane)tetraacrylate.

[0066] In certain embodiments, the photopolymerizable composition consists essentially of multifunctional components or is free of monofunctional components. This means that the photopolymerizable composition contains 2% or less by weight of monofunctional components. An advantage of such photopolymerizable compositions is that they tend to contain minimal to no unreacted reactive diluent that can leach out of the article after curing. In applications where the article is an orthodontic article, this minimizes the release of unreacted reactive diluent into the patient's mouth.

[0067] In certain embodiments, at least one reactive diluent has a molecular weight of 400 g / mol or less, 375 g / mol or less, 350 g / mol or less, 325 g / mol or less, 300 g / mol or less, 275 g / mol or less, 225 g / mol or less, or 200 g / mol or less. The inclusion of one or more reactive diluents having such molecular weights aids in obtaining a photopolymerizable composition with a viscosity sufficiently low for use in bath polymerization processes. In certain embodiments, at least one reactive diluent has a molecular weight of 200 g / mol to 400 g / mol, inclusive.

[0068] The reactive diluent is contained in the photopolymerizable composition in an amount of 5 to 50% by weight (inclusive), for example, 25 to 50% by weight (inclusive), based on the total weight of the photopolymerizable composition. Typically, the reactive diluent is contained in the photopolymerizable composition in an amount of 5% by weight or more, 10% by weight or more, 15% by weight or more, 20% by weight or more, 25% by weight or more, or 30% by weight or more, and 50% by weight or less, 45% by weight or less, 40% by weight or less, 35% by weight or less, 30% by weight or less, 25% by weight or less, or 20% by weight or less, based on the total weight of the photopolymerizable composition.

[0069] additives The photopolymerizable compositions described herein, in some examples, further comprise one or more additives, such as one or more additives selected from the group consisting of photoinitiators, inhibitors, stabilizers, sensitizers, absorption modifiers, fillers, and combinations thereof. For example, the photopolymerizable compositions further comprise one or more photoinitiators. Suitable exemplary photoinitiators are available from BASF (Ludwigshafen, Germany) under the trade names IRGACURE and DAROCUR, including 1-hydroxycyclohexyl phenyl ketone (IRGACURE 184), 2,2-dimethoxy-1,2-diphenylethan-1-one (IRGACURE 651), bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide (IRGACURE 819), 1-[4-(2-hydroxybenzoyl)phenyl]-2-methyl-1,2-propanol (IRGACURE 820), 1-[4-(2-hydroxybenzoyl)phenyl]-2-methyl-1,2-propanol (IRGACURE 821), 1-[4-(2-hydroxybenzoyl)phenyl]-2-methyl-1,2-propanol (IRGACURE 822), 1-[4-(2-hydroxybenzoyl)phenyl]-2-methyl-1,2-propanol (IRGACURE 823), 1-[4-(2-hydroxybenzoyl)phenyl]-2-methyl-1,2-propanol (IRGACURE 824), 1-[4-(2-hydroxybenzoyl)phenyl]-2-methyl-1,2-propanol (IRGACURE 825), 1-[4-(2-hydroxybenzoyl)phenyl]-2-methyl-1,2-propanol (IRGACURE 826), 1-[4-(2-hydroxybenzoyl)phenyl]-2-methyl-1,2-propanol (IRGACURE 827), 1-[4-(2-hydroxybenzoyl)phenyl]- [2-hydroxy-2-methyl-1-[4-(1-methylvinyl)phenyl]propanone] ESACURE ONE (Lamberti SpA, Gallarate, Italy), 2-hydroxy-2-methyl-1-phenylpropan-1-one (DAROCUR 1173), 2,4,6-trimethylbenzoyldiphenylphosphine oxide (IRGACURE TPO), and 2,4,6-trimethylbenzoylphenylphosphinate (IRGACURE TPO-L). Additional suitable photoinitiators include, but are not limited to, benzil dimethyl ketal, 2-methyl-2-hydroxypropiophenone, benzoin methyl ether, benzoin isopropyl ether, anisoin methyl ether, aromatic sulfonyl chlorides, photoactive oximes, and combinations thereof.

[0070] The photoinitiator can be present in the photopolymerizable compositions described herein in any amount consistent with the specific constraints of the additive manufacturing process. In some embodiments, the photoinitiator is present in the photopolymerizable composition in an amount of up to about 5 wt %, based on the total weight of the photopolymerizable composition. In some cases, the photoinitiator is present in an amount of about 0.1 wt % to 5 wt %, based on the total weight of the photopolymerizable composition.

[0071] In addition, the photopolymerizable material compositions described herein may further include one or more sensitizers to increase the effectiveness of one or more photoinitiators that may also be present. In some embodiments, the sensitizer includes isopropylthioxanthone (ITX) or 2-chlorothioxanthone (CTX). Other sensitizers may also be used. When used in a photopolymerizable composition, the sensitizer may be present in an amount ranging from about 0.01 wt % to about 1 wt %, based on the total weight of the photopolymerizable composition.

[0072] The photopolymerizable compositions described herein also optionally include one or more polymerization inhibitors or stabilizers. Polymerization inhibitors are often included in photopolymerizable compositions to add additional thermal stability to the composition. In some examples, the stabilizer includes one or more antioxidants. Any antioxidant not inconsistent with the objectives of the present disclosure may be used. For example, in some embodiments, suitable antioxidants include various aryl compounds, including butylated hydroxytoluene (BHT), which can also be used as a polymerization inhibitor in the embodiments described herein. Additionally or alternatively, polymerization inhibitors include methoxyhydroquinone (MEHQ).

[0073] In some embodiments, when a polymerization inhibitor is used, the polymerization inhibitor is present in an amount of about 0.001% to 2%, 0.001% to 1%, or 0.01% to 1% by weight, based on the total weight of the photopolymerizable composition. Further, when a stabilizer is used, the stabilizer is present in the photopolymerizable compositions described herein in an amount of about 0.1% to 5%, about 0.5% to 4%, or about 1% to 3% by weight, based on the total weight of the photopolymerizable composition.

[0074] The photopolymerizable compositions described herein can also include one or more absorption modifiers (e.g., dyes, optical brighteners, pigments, particulate fillers, etc.) to control the transmittance of actinic radiation. One particularly suitable absorption modifier is Tinopal OB (benzoxazole, 2,2'-(2,5-thiophenediyl)bis[5-(1,1-dimethylethyl)]), available from BASF Corporation (Florham Park, NJ). When used, the absorption modifier can be present in an amount of about 0.001% to 5%, about 0.01% to 1%, 0.1% to 3%, or about 0.1% to 1% by weight, based on the total weight of the photopolymerizable composition.

[0075] The photopolymerizable composition may contain fillers, including nanoscale fillers. Examples of suitable fillers include naturally occurring or synthetic materials, including, but not limited to, silica (SiO (e.g., quartz)), alumina (AlO), zirconia, nitrides (e.g., silicon nitride), glasses and fillers derived from, for example, Zr, Sr, Ce, Sb, Sn, Ba, Zn, and Al, feldspar, borosilicate glass, kaolin (china clay), talc, zirconia, titania, and submicron silica particles (e.g., pyrogenic silicas such as those available under the trade name AEROSIL, including "OX50", "130", "150", and "200" silicas from Degussa Corp., Akron, OH, and CAB-O-SIL M5 and TS-720 silicas from Cabot Corp., Tuscola, IL). Organic fillers made from polymeric materials, such as those disclosed in WO 09 / 045752 (Kalgutkar et al.), are also possible.

[0076] The composition may further comprise a fiber reinforcement and a colorant, such as a dye, pigment, or pigment dye. Examples of suitable fiber reinforcements include PGA microfibrils, collagen microfibrils, and other fiber reinforcements described in U.S. Patent No. 6,183,593 (Narang et al.). Examples of suitable colorants described in U.S. Patent No. 5,981,621 (Clark et al.) include 1-hydroxy-4-[4-methylphenylamino]-9,10-anthracenedione (FD&C Purple No. 2), 6-hydroxy-5-[(4-sulfophenyl)oxo]-2-naphthalenesulfonic acid, disodium salt (FD&C Yellow No. 6), 9-(o-carboxyphenyl)-6-hydroxy-2,4,5,7-tetraiodo-3H-xanthen-3-one, disodium salt, monohydrate (FD&C Red No. 3), and the like.

[0077] Discontinuous fibers are also suitable fillers, such as fibers containing carbon, ceramic, glass, or combinations thereof. Suitable discontinuous fibers can have a variety of compositions, such as ceramic fibers. Ceramic fibers can be produced in continuous lengths, which are chopped or sheared to obtain discontinuous ceramic fibers. Ceramic fibers can be produced from various commercially available ceramic filaments. Examples of filaments useful for forming ceramic fibers include ceramic oxide fibers sold under the trademark NEXTEL (3M Company, St. Paul, MN). NEXTEL is a continuous filament ceramic oxide fiber with low elongation and shrinkage at operating temperatures, providing good chemical resistance, low thermal conductivity, thermal shock resistance, and low porosity. Specific examples of NEXTEL fibers include NEXTEL 312, NEXTEL 440, NEXTEL 550, NEXTEL 610, and NEXTEL 720. NEXTEL 312 and NEXTEL 440 are refractory aluminoborosilicates containing Al2O3, SiO2, and B2O3. NEXTEL 550 and NEXTEL 720 are aluminosilicates, and NEXTEL 610 is alumina. During manufacturing, NEXTEL filaments are coated with organic sizing or finishes, which function as fiber processing aids. Sizing can involve the use of starch, oil, wax, or other organic components applied to the filament strand for protection and handling aids. Sizing can be removed from ceramic filaments by thermally washing the filaments or ceramic fibers at temperatures of 700°C for 1 to 4 hours.

[0078] Ceramic fibers can be cut, crushed, or chopped to provide relatively uniform lengths. This can be achieved by cutting continuous filaments of ceramic material with mechanical shearing or laser cutting operations, among other cutting operations. Given the highly controlled nature of certain cutting operations, the size distribution of ceramic fibers can be very narrow, allowing for control of composite properties. For example, ceramic fiber length can be measured using an optical microscope (Olympus MX61, Tokyo, Japan) equipped with a CCD camera (Olympus DP72, Tokyo, Japan) and analysis software (Olympus Stream Essentials, Tokyo, Japan). Samples can be prepared by spreading a representative sample of ceramic fibers on a glass slide and measuring the lengths of at least 200 ceramic fibers at 10x magnification.

[0079] Suitable fibers include ceramic fibers available under the trade name NEXTEL (available from 3M Company, St. Paul, MN), such as, for example, NEXTEL 312, 440, 610, and 720. One currently preferred ceramic fiber comprises polycrystalline α-Al2O3. Suitable alumina fibers are described, for example, in U.S. Pat. No. 4,954,462 (Wood et al.) and U.S. Pat. No. 5,185,299 (Wood et al.). A representative alpha alumina fiber is commercially available under the trade name NEXTEL 610 (3M Company, St. Paul, MN). In some embodiments, the alumina fiber is a polycrystalline alpha alumina fiber and comprises, on a theoretical oxide basis, greater than 99 wt. % Al2O3 and 0.2 wt. % to 0.5 wt. % SiO2, based on the total weight of the alumina fiber. In other embodiments, some desirable polycrystalline alpha alumina fibers comprise alpha alumina having an average particle size of less than 1 micrometer (or even, in some embodiments, less than 0.5 micrometer). In some embodiments, the polycrystalline alpha alumina fibers have an average tensile strength of at least 1.6 GPa (in some embodiments, at least 2.1 GPa, or even at least 2.8 GPa). Suitable aluminosilicate fibers are described, for example, in U.S. Pat. No. 4,047,965 (Karst et al.). Exemplary aluminosilicate fibers are commercially available under the tradenames NEXTEL 440 and NEXTEL 720 from 3M Company (St. Paul, MN). Aluminoborosilicate fibers are described, for example, in U.S. Pat. No. 3,795,524 (Sowman). Exemplary aluminoborosilicate fibers are commercially available under the tradename NEXTEL 312 from 3M Company. Boron nitride fibers can be made, for example, as described in US Pat. No. 3,429,722 (Economy) and US Pat. No. 5,780,154 (Okano et al.).

[0080] Ceramic fibers can also be formed from other suitable ceramic oxide filaments. Examples of such ceramic oxide filaments include those available from Central Glass Fiber Co., Ltd. (e.g., EFH75-01, EFH150-31). Aluminoborosilicate glass fibers containing less than about 2% alkali or substantially alkali-free (i.e., "E-glass" fibers) are also preferred. E-glass fibers are available from a number of commercial suppliers.

[0081] Non-limiting examples of useful pigments include white pigments such as titanium oxide, zinc phosphate, zinc sulfide, zinc oxide, and lithopone; red and red-orange pigments such as iron oxide (maroon, red, bright red), iron / chromium oxide, cadmium sulfoselenide, and mercury cadmium sulfide (maroon, red, orange); ultramarine (blue, pink, and purple), chromium tin (pink), manganese (purple), cobalt (purple); barium titanate, cadmium sulfide (yellow), chromium (orange, yellow), molybdate (orange), zinc chromate (yellow), nickel titanate (yellow), iron oxide (yellow), Orange, yellow, and buff pigments such as nickel tungsten titanium, zinc ferrite, and chromium titanate; brown pigments such as iron oxide (buff, brown), manganese oxide / antimony oxide / titanium oxide, manganese titanate, natural sienna (amber), and titanium tungsten manganese; blue-green pigments such as chromium aluminate (blue), chromium cobalt alumina (turquoise), iron blue (blue), manganese blue, chromium and chromium oxide (green), and titanium green; and black pigments such as iron oxide black and carbon black. Combinations of pigments are commonly used to achieve the desired color tone in the cured composition.

[0082] The use of fluorescent dyes and pigments can be useful to make printed compositions visible under invisible light. A particularly useful hydrocarbon-soluble fluorescent dye is 2,5-bis(5-tert-butyl-2-benzoxazolyl)-1-thiophene. Fluorescent dyes such as rhodamine can be attached to cationic polymers and incorporated as part of the resin.

[0083] If desired, the compositions of the present disclosure may contain other additives, such as indicators, accelerators, surfactants, humectants, antioxidants, tartaric acid, chelating agents, buffers, and other similar ingredients that will be apparent to those skilled in the art. In addition, pharmaceutical or other therapeutic substances can optionally be added to the photopolymerizable composition. Examples include, but are not limited to, fluoride sources, whitening agents, anti-caries agents (e.g., xylitol), mineral supplements (e.g., calcium phosphate compounds and other calcium and phosphate sources), enzymes, breath fresheners, anesthetics, coagulants, acid neutralizers, chemotherapeutic agents, immune response modifiers, thixotropes, polyols, anti-inflammatory agents, antibacterial agents, antifungal agents, dry mouth treatment agents, desensitizing agents, and the like, types often used in dental compositions.

[0084] Combinations of any of the above additives may be used, and one of ordinary skill in the art can select any one of such additives and the amount thereof to achieve the desired result without undue experimentation.

[0085] The photopolymerizable composition materials described herein can also exhibit a variety of desirable properties as uncured, cured, and post-cured articles. When uncured, the photopolymerizable composition has a viscosity profile that conforms to the requirements and parameters of one or more additive manufacturing devices (e.g., 3D printing systems). In some cases, the photopolymerizable compositions described herein exhibit a dynamic viscosity, when uncured, of about 0.1 to 1,000 Pa·s, about 0.1 to 100 Pa·s, or about 1 to 10 Pa·s, measured according to ASTM D4287, as described in the Examples test methods below, at 40°C and a shear rate of 0.1 [1 / s], using a TA Instruments AR-G2 magnetic bearing rheometer with a 40 mm cone-plate measurement system. In some cases, the photopolymerizable compositions described herein exhibit a dynamic viscosity, when uncured, of less than about 10 Pa·s, measured according to modified ASTM D4287.

[0086] Articles and methods In a second aspect, the present disclosure provides an article, the article comprising the reaction product of a photopolymerizable composition, the photopolymerizable composition comprising, based on the total weight of the photopolymerizable composition: (a) 50% to 90% by weight (inclusive) of at least one urethane component; (b) 5% to 50% by weight (inclusive) of at least one reactive diluent; (c) 0.1 wt % to 5 wt % (inclusive) of a photoinitiator; and (d) an optional inhibitor, if present, in an amount of 0.001% to 1% by weight, inclusive; In many embodiments, the photopolymerizable composition of the article is bath polymerized, as described in detail below.

[0087] The shape of the article is not limited and may include a film or a molded one-piece article. For example, a film can be readily prepared by casting a photopolymerizable composition according to the first aspect and then exposing the cast composition to actinic radiation to polymerize the photopolymerizable composition. In many embodiments, the article comprises a molded one-piece article in which two or more dimensional variations are achieved in a single one-piece article. For example, the article may include one or more channels, one or more undercuts, one or more perforations, or a combination thereof. Such features are typically not possible to achieve in a one-piece article using conventional molding methods. In selected embodiments, the article comprises an orthodontic article. Orthodontic articles are described in more detail below.

[0088] In a third aspect, the present disclosure provides a method for manufacturing an article, the method comprising: (i) providing a photopolymerizable composition comprising, based on the total weight of the photopolymerizable composition, (a) 50% to 90% by weight, inclusive, of at least one urethane component; (b) 5% to 50% by weight, inclusive, of at least one reactive diluent; (c) 0.1% to 5% by weight, inclusive, of a photoinitiator; and (d) 0.001% to 1% by weight, inclusive, of an optional inhibitor, if present; (ii) selectively curing the photopolymerizable composition to form an article; and (iii) optionally curing any unpolymerized urethane component and / or reactive diluent remaining after step (ii); and Includes.

[0089] In many embodiments, the photopolymerizable composition is cured using actinic radiation, including ultraviolet light, electron beam radiation, visible light, or a combination thereof. Additionally, the method further includes post-curing the article using actinic radiation or heat.

[0090] In additive manufacturing methods, the method further comprises (iv) repeating steps (i) and (ii) to form multiple layers to produce an article comprising a three-dimensional structure prior to step (iii). In certain embodiments, the method comprises bath polymerization of the photopolymerizable composition. When bath polymerization is employed, radiation may be directed through a wall of a container (e.g., a bath) holding the photopolymerizable composition, such as a side wall or bottom wall.

[0091] The photopolymerizable compositions described herein in their cured state can, in some embodiments, exhibit one or more desirable properties. A "cured" photopolymerizable composition can include a photopolymerizable composition comprising a polymerizable component that is at least partially polymerized and / or crosslinked. For example, in some instances, the cured article is at least about 10% polymerized or crosslinked, or at least about 30% polymerized or crosslinked. In some instances, the cured photopolymerizable composition is at least about 50%, at least about 70%, at least about 80%, or at least about 90% polymerized or crosslinked. The cured photopolymerizable composition can also be from about 10% to about 99% polymerized or crosslinked.

[0092] The suitability and durability of cured articles made from the photopolymerizable compositions of the present disclosure can be determined, in part, by standard tensile, modulus, and / or elongation tests. Photopolymerizable compositions can typically be characterized, after hardening, by at least one of the following parameters: Advantageously, the elongation at break is typically 25% or more, 27% or more, 30% or more, 32% or more, 35% or more, 40% or more, 45% or more, 50% or more, 55% or more, or 60% or more, and 200% or less, 100% or less, 90% or less, 80% or less, or 70% or less. In other words, the elongation at break of the cured article can range from 25% to 200%. In some embodiments, the elongation at break is at least 30% and 100% or less. The ultimate tensile strength, as determined in accordance with ASTM D638-10, is typically 15 megapascals (MPa) or greater, 20 MPa or greater, 25 MPa or greater, or 30 MPa or greater, and typically 80 MPa or less. While the urethane component has the greatest effect on the article's elongation at break, other components of the photopolymerizable composition also affect the elongation at break; for example, the linear or branched length of the reactive diluent tends to positively correlate with the elongation at break of the final article. The tensile modulus, as determined in accordance with ASTM D638-10, is typically 200 MPa or greater. Such elongation properties can be measured, for example, using Type V specimens by the method outlined in ASTM D638-10. The above mechanical properties are particularly suitable for articles requiring elasticity and flexibility, along with adequate abrasion resistance and low moisture absorption.

[0093] The photopolymerizable compositions described herein can be mixed using known techniques. In some embodiments, for example, a method for preparing the photopolymerizable compositions described herein includes mixing all or substantially all of the components of the photopolymerizable composition, heating the mixture, and optionally filtering the heated mixture. Softening the mixture, in some embodiments, occurs at a temperature of about 50°C or in a range of about 50°C to about 85°C. In some embodiments, the photopolymerizable compositions described herein are produced by placing all or substantially all of the components of the composition in a reaction vessel and heating the resulting mixture to a temperature in a range of about 50°C to about 85°C with stirring. Heating and stirring are continued until the mixture reaches a substantially homogenized state.

[0094] Manufacture of goods Once prepared as described above, the photopolymerizable compositions of the present disclosure can be used in a variety of additive manufacturing processes to produce a variety of articles, including casting films as described above. A generalized method 100 for producing three-dimensional articles is shown in FIG. 1. Each step of the method is described in detail below. First, in step 110, a desired photopolymerizable composition (e.g., including at least one urethane component, at least one reactive diluent, and a photoinitiator) is prepared and introduced into a reservoir, cartridge, or other suitable container for use by or within an additive manufacturing device. The additive manufacturing device selectively cures the photopolymerizable composition according to a set of computerized design instructions in step 120. In step 130, steps 110 and / or 120 are repeated to form multiple layers to produce an article (e.g., an orthodontic aligner) comprising a three-dimensional structure. Optionally, in step 140, uncured photopolymerizable composition is removed from the article, and then, optionally, in step 150, the article is subjected to additional curing to polymerize any remaining uncured photopolymerizable components within the article.

[0095] Methods of printing three-dimensional articles or objects described herein can include forming an article from multiple layers of the photopolymerizable compositions described herein in a layer-by-layer manner. Further, layers of the material composition to be built can be deposited according to an image of the three-dimensional article in computer-readable form. In some or all embodiments, the photopolymerizable composition is deposited according to preselected computer-aided design (CAD) parameters.

[0096] Additionally, it is understood that the methods for producing the 3D articles described herein can include so-called "stereolithography / vapour polymerization" 3D printing methods. Other techniques for three-dimensional fabrication are known and may be appropriately adapted for use in the applications described herein. More generally, three-dimensional fabrication techniques are becoming increasingly available. All such techniques can be adapted for use with the photopolymerizable compositions described herein, so long as they provide fabrication viscosities and resolution consistent with the specified article characteristics. Fabrication may be performed using any of the fabrication techniques described herein, alone or in various combinations, using data representing the three-dimensional object, which can be reformatted or otherwise adapted as needed for a particular printing or other fabrication technique.

[0097] It is entirely possible to form 3D articles from the photopolymerizable compositions described herein using liquid vat polymerization (e.g., stereolithography). For example, in some cases, a method of printing a 3D article includes holding the photopolymerizable composition described herein in a fluid state in a container and selectively applying energy to the photopolymerizable composition in the container to solidify at least a portion of the fluid layer of the photopolymerizable composition, thereby forming a hardened layer that defines a cross-section of the 3D article. In addition, the methods described herein can further include raising or lowering the hardened layer of the photopolymerizable composition to provide a new, or second, fluid layer of unhardened photopolymerizable composition on the surface of the fluid in the container, and then selectively applying energy again to the photopolymerizable composition in the container to solidify at least a portion of the new, or second, fluid layer of the photopolymerizable composition to form a second solidified layer that defines a second cross-section of the 3D article. Furthermore, the application of energy to solidify the photopolymerizable composition can bond or adhere the first and second cross sections of the 3D article to each other in the z-direction (i.e., the build direction corresponding to the above-described ascending or descending direction). Furthermore, selectively applying energy to the photopolymerizable composition in the container can include applying actinic radiation, such as ultraviolet, visible, or electron beam radiation, having sufficient energy to cure the photopolymerizable composition. The methods described herein can also include planarizing the new layer of fluid photopolymerizable composition provided by raising and lowering the elevator platform. Such planarization can, in some cases, be achieved by utilizing a wiper or roller or recoater beads. Planarization involves flattening the dispensed material to remove excess material and create a uniform, smooth, exposed, or flat, upward-facing surface on the printer's support platform, thereby correcting the thickness of one or more layers before the material is cured.

[0098] It is further understood that the above-described process can be repeated a selected number of times to provide a 3D article. For example, in some cases, the process can be repeated "n" times. It is further understood that one or more steps of the methods described herein, such as selectively applying energy to a layer of a photopolymerizable composition, can be performed according to a computer-readable image of the 3D article. Suitable stereolithography printers include the Viper Pro SLA available from 3D Systems, Rock Hill, SC, and the Asiga Pico Plus39 available from Asiga USA, Anaheim Hills, CA.

[0099] FIG. 2 shows an example of a stereolithography apparatus ("SLA") that may be used with the photopolymerizable compositions and methods described herein. Generally, SLA 200 may include a laser 202, optics 204, a steering lens 206, an elevator 208, a platform 210, and a linear edge 212 within a bath 214 filled with the photopolymerizable composition. During operation, laser 202 is steered across the surface of the photopolymerizable composition to harden a cross-section of the photopolymerizable composition, after which elevator 208 slightly lowers platform 210 to harden another cross-section. Linear edge 212 may sweep across the surface of the cured composition between layers to smooth and normalize the surface before adding a new layer. In other embodiments, bath 214 may be slowly filled with liquid resin while an article is drawn layer by layer on top of the photopolymerizable composition.

[0100] A related technique, bath polymerization by digital light processing ("DLP"), also uses a reservoir of curable polymer (e.g., a photopolymerizable composition). However, DLP-based systems project a two-dimensional cross-section onto the curable material, curing the desired portion of the entire plane orthogonal to the projected beam at once. All curable polymer systems that may be modified for use with the photopolymerizable compositions described herein are intended to be within the scope of the term "bath polymerization system" as used herein. In certain embodiments, equipment adapted for use in a continuous mode, such as that commercially available from Carbon 3D, Inc. (Redwood City, CA), may be used, as described, for example, in U.S. Pat. Nos. 9,205,601 and 9,360,757 (both to DeSimone et al.).

[0101] 5, a schematic diagram of another SLA apparatus that may be used with the photopolymerizable compositions and methods described herein is provided. Generally, apparatus 500 may include a laser 502, optics 504, a steering lens 506, an elevator 508, and a platform 510 within a bath 514 filled with a photopolymerizable composition 519. During operation, laser 502 is directed through a wall 520 (e.g., a floor) of bath 514 toward the photopolymerizable composition, curing a cross section of photopolymerizable composition 519 to form article 517, after which elevator 508 slightly raises platform 510 and another cross section is cured.

[0102] More generally, photopolymerizable compositions are typically cured using actinic radiation, such as ultraviolet radiation, electron beam radiation, visible radiation, or any combination thereof. One of ordinary skill in the art can select a suitable radiation source and wavelength range for a particular application without undue experimentation.

[0103] After the 3D article is formed, it is typically removed from the additive manufacturing apparatus and cleaned (e.g., ultrasonically, foam, or spray-cleaned in a solvent that dissolves a portion of the uncured photopolymerizable composition but not the cured solid-state article (e.g., substrate)). Any other conventional method may also be utilized to clean the article and remove uncured material from the surface of the article. At this stage, the three-dimensional article typically has sufficient green strength for handling in any remaining steps of method 100.

[0104] In certain embodiments of the present disclosure, it is expected that the formed article resulting from step 120 will shrink (i.e., decrease in volume), resulting in smaller dimensions of the article after (optional) step 150 than anticipated. For example, the cured article may shrink in volume by less than 5%, less than 4%, less than 3%, less than 2%, or even less than 1%, as opposed to other compositions that result in articles that shrink in volume by approximately 6-8% upon optional post-cure. The amount of volumetric shrinkage typically does not result in significant distortion of the final object shape. Therefore, it is specifically contemplated that the dimensions in the digital representation of the final cured article may be scaled up according to an overall scaling factor to compensate for this shrinkage. For example, in some embodiments, at least a portion of the digital article representation may be at least 101%, in some embodiments at least 102%, in some embodiments at least 104%, in some embodiments at least 105%, and in some embodiments at least 110% of the desired size of the printed orthosis.

[0105] The overall magnification can be calculated for a given photopolymerizable composition formulation by creating a calibration part according to above steps 110 and 120. The dimensions of the calibration article can be measured before post-cure.

[0106] Typically, the three-dimensional article formed by the initial additive manufacturing in step 120 is not fully cured, as described above, meaning that not all of the photopolymerizable material in the composition is polymerized, even after washing. Some uncured photopolymerizable material is typically removed from the surface of the printed article during the washing process (e.g., optional step 140). The article surface, and the bulk article itself, typically still retains uncured photopolymerizable material, indicating further curing. Removing residual uncured photopolymerizable composition is particularly useful in minimizing uncured residual photopolymerizable composition from undesirably curing directly on the article when the article is subsequently post-cured.

[0107] Further curing can be achieved by further actinic radiation, heating, or both. Exposure to actinic radiation may be achieved from any convenient radiation source, typically ultraviolet, visible, and / or electron beam radiation, for a time ranging from about 10 minutes to more than 60 minutes. Heating is typically achieved under an inert atmosphere at a temperature ranging from about 75°C to 150°C for a time ranging from about 10 minutes to more than 60 minutes. So-called post-cure ovens, which combine ultraviolet and thermal energy, are particularly suitable for use in the post-cure process of step 150. Generally, post-curing improves the mechanical properties and stability of the three-dimensional article compared to the same three-dimensional article that has not been post-cured.

[0108] A general method for making a clear tray aligner as a printed appliance 300 is described below. However, similar techniques and the photopolymerizable composition of the present disclosure can be used to make other dental and orthodontic articles. Representative examples include, but are not limited to, removable appliances with occlusal windows as described in International Application Publication No. 2016 / 109660 (Raby et al.), removable appliances with palatal plates as described in U.S. Patent Publication No. 2014 / 0356799 (Cinader et al.), and resilient polymeric dental arch members as described in International Application Publication Nos. 2016 / 148960 and 2016 / 149007 (Oda et al.) and U.S. Patent Publication No. 2008 / 0248442 (Cinader et al.). Additionally, the photopolymerizable compositions can be used to make indirect bonding trays, such as those described in WO 2015 / 094842 (Paehl et al.) and U.S. Patent Application Publication No. 2011 / 0091832 (Kim et al.), as well as other dental articles, including, but not limited to, crowns, bridges, veneers, inlays, onlays, fillings, and prostheses (e.g., partial or complete dentures). Other orthodontic appliances and devices include, but are not limited to, orthodontic brackets, buccal tubes, lower retainers, orthodontic bands, Class II and Class III braces, sleep apnea devices, mouth gag devices, buttons, cleats, and other accessory devices.

[0109] Alternatively, the photopolymerizable compositions can be used in other industries such as aerospace, animation and entertainment, architecture and art, automotive, consumer goods and packaging, education, electronics, hearing aids, sporting goods, jewelry, medical, manufacturing, and the like.

[0110] Fabrication of orthodontic appliances using photopolymerizable compositions One particularly interesting implementation of the article is shown generally in FIG. 3 . The additively manufactured article 300 is a clear tray aligner that can be removably positioned over some or all of a patient's teeth. In some embodiments, the appliance 300 is one of a plurality of graduated adjustable appliances. The appliance 300 may include a shell having an internal cavity. The internal cavity is configured to receive and resiliently reposition teeth from one tooth arrangement to a successive tooth arrangement. The internal cavity may include a plurality of receiving portions, each adapted to connect with and receive a respective tooth in the patient's dental arch. The receiving portions are spaced apart along the length of the cavity, although nearby regions of adjacent receiving portions may communicate with each other. In some embodiments, the shell fits over all of the teeth present in the upper or lower jaw. Typically, only one specific tooth is repositioned, with the other teeth providing base or anchor regions that hold the dental appliance in place while applying a resilient repositioning force against the tooth or teeth being treated.

[0111] To facilitate positioning of the patient's teeth, at least one of the receiving portions may be misaligned with respect to the patient's corresponding teeth. As such, the appliance 300 may be configured to apply rotational and / or translational forces to the patient's corresponding teeth when the appliance 300 is worn by the patient. In some particular examples, the appliance 300 may be configured to apply only compressive or linear forces. In the same or a different example, the appliance 300 may be configured to apply a translational force to one or more of the teeth within the receiving portions.

[0112] In some embodiments, the shell of appliance 300 fits over some or all of the anterior teeth present in the upper or lower jaw. Typically, only one particular tooth will be repositioned, with the other teeth providing a base or anchor area to hold the appliance in place while exerting a resilient repositioning force on the tooth or teeth being repositioned. Thus, appliance 300 can be designed so that any receiving portion is shaped to facilitate tooth retention in a specific position to maintain the tooth's current position.

[0113] A method 400 for forming orthodontic appliances using the photopolymerizable composition of the present disclosure may include the overall general steps outlined in FIG. 4. Individual aspects of the process are described in further detail below. The process includes creating a treatment plan to reposition a patient's teeth. Briefly, the treatment plan may include obtaining data representing an initial arrangement of the patient's teeth (step 410), which typically involves obtaining impressions or scans of the patient's teeth prior to the start of treatment. The treatment plan also includes identifying a desired final or target arrangement of the patient's anterior and posterior teeth (step 420) and identifying a number of planned successive or intermediate tooth arrangements for moving at least the anterior teeth from the initial arrangement toward the selected final or target arrangement along a treatment path (step 430). One or more appliances are virtually designed based on the treatment plan (step 440), and image data representing the appliance design may be exported in STL format or other suitable computer-processable format to an additive manufacturing device (e.g., a 3D printer system) (step 450). The photopolymerizable composition of the present disclosure held within the additive manufacturing device can be used to manufacture the orthosis (step 460).

[0114] In some embodiments, in accordance with at least certain aspects of the present disclosure, a (e.g., non-transitory) machine-readable medium is used in additive manufacturing of an article. Data is typically stored on the machine-readable medium. The data represents a three-dimensional model of the article, which model is accessible by at least one computer processor interfacing with an additive manufacturing apparatus (e.g., a 3D printer, manufacturing device, etc.). The data is used to cause the additive manufacturing apparatus to produce an article comprising the reaction product of a photopolymerizable composition, the photopolymerizable composition comprising, based on the total weight of the photopolymerizable composition, (a) 50% to 90% by weight, inclusive, of at least one urethane component; (b) 5% to 50% by weight, inclusive, of at least one reactive diluent; (c) 0.1% to 5% by weight, inclusive, of a photoinitiator; and (d) optional inhibitors, when present, in an amount of 0.001% to 1% by weight, inclusive. In certain embodiments, the article is an orthodontic article. Preferably, the article has an elongation at break of 25% or greater.

[0115] Data representing the article may be generated using computer modeling, such as computer-aided design (CAD) data. Image data representing the design of the (e.g., polymer) article can be exported to additive manufacturing equipment in STL format or any other suitable computer-processable format. Scanning methods for scanning three-dimensional objects can also be used to create data representing the article. One exemplary technique for acquiring data is digital scanning. Any other suitable scanning technique can be used to scan the article, including radiography, laser scanning, computed tomography (CT), magnetic resonance imaging (MRI), and ultrasound imaging. Other possible scanning methods are described, for example, in U.S. Patent Application Publication No. 2007 / 0031791 (Cinader, Jr., et al.). The initial digital dataset, which may include both raw data from the scanning operation and data representing the article derived from the raw data, can be processed to segment the design of the article from any surrounding structures (e.g., supports for the article). In embodiments where the article is an orthodontic article, the scanning technique may include, for example, scanning the patient's oral cavity to customize the orthodontic article for the patient.

[0116] In many cases, the machine-readable medium is provided as part of a computing device. A computing device may have one or more processors, volatile memory (RAM), a device for reading the machine-readable medium, and input / output devices such as a display, a keyboard, and a pointing device. Additionally, a computing device may also include other software, such as an operating system and other application software, firmware, or a combination thereof. A computing device may be, for example, a workstation, laptop, personal digital assistant (PDA), server, mainframe, or any other general-purpose or special-purpose computing device. A computing device may read executable software instructions from a computer-readable medium (e.g., a hard drive, CD-ROM, or computer memory) or may receive instructions from another source logically connected to the computer, such as another networked computer. Referring to FIG. 10 , a computing device 1000 often includes an internal processor 1080, a display 1100 (e.g., a monitor), and one or more input devices, such as a keyboard 1140 and a mouse 1120. In FIG. 10 , an aligner 1130 is displayed on the display 1100.

[0117] 6 , in certain embodiments, the present disclosure provides a system 600. The system 600 includes a display 620 that displays a 3D model 610 of an article (e.g., an aligner 1130 as displayed on display 1100 of FIG. 10 ) and one or more processors 630 that cause a 3D printer / additive manufacturing device 650 to create a physical object of the article 660 in response to the 3D model 610 selected by a user. Often, an input device 640 (e.g., a keyboard and / or mouse) is used in conjunction with the display 620 and at least one processor 630, particularly for user selection of the 3D model 610. Article 660 comprises the reaction product of a photopolymerizable composition comprising, based on the total weight of the photopolymerizable composition, (a) 50% to 90% by weight, inclusive, of at least one urethane component; (b) 5% to 50% by weight, inclusive, of at least one reactive diluent; (c) 0.1% to 5% by weight, inclusive, of a photoinitiator; and (d) an optional inhibitor, if present, in an amount of 0.001% to 1% by weight, inclusive.

[0118] 7, a processor 720 (or two or more processors) is in communication with each of a machine-readable medium 710 (e.g., a non-transitory medium), a 3D printer / additive manufacturing device 740, and, optionally, a display 730 for viewing by a user. The 3D printer / additive manufacturing device 740 is configured to manufacture one or more articles 750 based on instructions from the processor 720, which provides data representing a 3D model of the article 750 (e.g., an aligner 1130 as shown in display 1100 of FIG. 10 ) from the machine-readable medium 710.

[0119] 8 , for example, but not by way of limitation, an additive manufacturing method includes retrieving 810 data representing a 3D model of an article according to at least one embodiment of the present disclosure from a (e.g., non-transitory) machine-readable medium. The method further includes executing 820, by one or more processors, an additive manufacturing application that interfaces with a manufacturing device using the data, and generating 830, by the manufacturing device, a physical object of the article. The additive manufacturing equipment can selectively cure a photopolymerizable composition to form the article. The article comprises a reaction product of a photopolymerizable composition, the photopolymerizable composition comprising, based on the total weight of the photopolymerizable composition, (a) 50% to 90% by weight (inclusive) of at least one urethane component; (b) 5% to 50% by weight (inclusive) of at least one reactive diluent; (c) 0.1% to 5% by weight (inclusive) of a photoinitiator; and (d) an optional inhibitor, if present, in an amount of 0.001% to 1% by weight (inclusive). One or more various optional post-processing steps 840 may be performed. Typically, residual unpolymerized photopolymerizable components are allowed to harden. In certain embodiments, the article comprises an orthodontic article. Further, referring to FIG. 9 , a method of manufacturing an article includes receiving 910 a digital object including data defining multiple layers of the article by a manufacturing device having one or more processors, and generating 920 an article based on the digital object using the manufacturing device by an additive manufacturing process. Again, the article may be subjected to one or more steps of post-processing 930.

[0120] Selected Embodiments of the Present Disclosure Embodiment 1 is a photopolymerizable composition. The photopolymerizable composition includes: (a) 50% to 90% by weight (inclusive) of at least one urethane component; and (b) 5% to 50% by weight (inclusive) of at least one reactive diluent. The photopolymerizable composition further includes: (c) 0.1% to 5% by weight (inclusive) of a photoinitiator; and (d) an optional inhibitor, if present, in an amount of 0.001% to 1% by weight (inclusive), based on the total weight of the photopolymerizable composition.

[0121] Embodiment 2 is the photopolymerizable composition of embodiment 1, wherein the at least one urethane component is present in an amount of 60% to 80% by weight, inclusive, of the total weight of the photopolymerizable composition.

[0122] Embodiment 3 is the photopolymerizable composition of embodiment 1 or embodiment 2, wherein at least one urethane component comprises a high number average molecular weight (Mn) urethane component having one or more urethane functional groups in the backbone of the compound and a number average molecular weight of 1,000 grams per mole (g / mol) or greater, provided that all branches from the backbone of the compound, if present, have an Mn of 200 g / mol or less.

[0123] Embodiment 4 is the photopolymerizable composition of embodiment 3, wherein the at least one urethane component comprises 80% or more, 85% or more, 90% or more, or 95% or more by weight of a high Mn urethane component.

[0124] Embodiment 5 is the photopolymerizable composition of embodiment 3 or embodiment 4, wherein at least one urethane component further comprises a low Mn urethane component having one or more urethane functional groups in the backbone of the compound, and has either 1) a number average molecular weight of 100 g / mol or more and less than 1,000 g / mol, or 2) an Mn of 100 g / mol or more and 2,000 g / mol or less, provided that the Mn of any one or more linear segments between two reactive groups and / or branches is less than 1,000 g / mol.

[0125] Embodiment 6 is the photopolymerizable composition of embodiment 5, wherein the at least one urethane component comprises 20% by weight or less, 16% by weight or less, 11% by weight or less, 9% by weight or less, or 6% by weight or less of a low-Mn urethane component.

[0126] Embodiment 7 is the photopolymerizable composition according to embodiment 5 or 6, wherein the ratio of the high Mn urethane component to the low Mn urethane component is in the range of 95:5 to 80:20.

[0127] Embodiment 8 is the photopolymerizable composition of any one of embodiments 1 to 7, wherein at least one urethane component comprises a urethane (meth)acrylate, a urethane acrylamide, or a combination thereof, and wherein at least one urethane component comprises a linking group selected from an alkyl, a polyalkylene, a polyalkylene oxide, an aryl, a polycarbonate, a polyester, a polyamide, and a combination thereof.

[0128] Embodiment 9 is the photopolymerizable composition of any one of embodiments 1-8, wherein at least one urethane component comprises a urethane (meth)acrylate comprising a polyalkylene oxide linking group, a polyamide linking group, or a combination thereof.

[0129] Embodiment 10 is the photopolymerizable composition of any one of embodiments 1-9, wherein the at least one reactive diluent has a molecular weight of from 200 grams / mole to 400 grams / mole, inclusive.

[0130] Embodiment 11 is the photopolymerizable composition of any one of embodiments 1-10, wherein the at least one reactive diluent comprises a (meth)acrylate, a polyalkylene oxide di(meth)acrylate, an alkanediol di(meth)acrylate, or a combination thereof.

[0131] Embodiment 12 is the photopolymerizable composition of any one of embodiments 1-11, wherein the at least one reactive diluent comprises a (meth)acrylate.

[0132] Embodiment 13 is the photopolymerizable composition of any one of embodiments 1-12, consisting essentially of a multifunctional component.

[0133] Embodiment 14 is the photopolymerizable composition of any one of embodiments 1 to 13, which does not include a monofunctional component.

[0134] Embodiment 15 is the photopolymerizable composition of any one of embodiments 1-14, comprising 25% to 50% by weight (inclusive) of at least one reactive diluent.

[0135] Embodiment 16 is the photopolymerizable composition of any one of embodiments 1 to 15, further comprising 0.01 wt % to 1 wt % (inclusive) of an absorption modifier.

[0136] Embodiment 17 is the photopolymerizable composition of any one of embodiments 1 to 16, having a viscosity of 10 Pa·s or less at a temperature of 40°C, as determined using a magnetic bearing rheometer using a 40 mm cone-plate measurement system at a shear rate of 0.1 [1 / s].

[0137] Embodiment 18 is the photopolymerizable composition of any one of embodiments 1-17, further comprising at least one filler.

[0138] Embodiment 19 is the photopolymerizable composition of any one of embodiments 1 to 18, further comprising at least one filler selected from silica, alumina, zirconia, and discontinuous fibers.

[0139] Embodiment 20 is the photopolymerizable composition of embodiment 19, wherein the discontinuous fibers comprise carbon, ceramic, glass, or a combination thereof.

[0140] Embodiment 21 is an article comprising the reaction product of a photopolymerizable composition. The photopolymerizable composition comprises: (a) 50% to 90% by weight, inclusive, of at least one urethane component; and (b) 5% to 50% by weight, inclusive, of at least one reactive diluent. The photopolymerizable composition further comprises: (c) 0.1% to 5% by weight, inclusive, of a photoinitiator; and (d) an optional inhibitor, when present, in an amount of 0.001% to 1% by weight, inclusive, based on the total weight of the photopolymerizable composition.

[0141] Embodiment 22 is the article of embodiment 21, comprising multiple layers.

[0142] Embodiment 23 is the article of embodiment 21 or embodiment 22, comprising a film or molded integral article.

[0143] Embodiment 24 is the article of any one of embodiments 21-23, including an orthodontic article.

[0144] Embodiment 25 is the article of any one of embodiments 21-24, comprising one or more channels, one or more undercuts, one or more perforations, or a combination thereof.

[0145] Embodiment 26 is the article of any one of embodiments 21-25, exhibiting an elongation at break of 25% or greater.

[0146] Embodiment 27 is the article of any one of embodiments 21-26, exhibiting a tensile strength, as determined according to ASTM D638-10, of 20 megapascals (MPa) or greater.

[0147] Embodiment 28 is the article of any one of embodiments 21-27, exhibiting a modulus of elasticity, as determined according to ASTM D638-10, of 200 MPa or greater.

[0148] Embodiment 29 is the article of any one of embodiments 21-28, wherein the at least one urethane component is present in the photopolymerizable composition in an amount of 60% to 80% by weight, inclusive, of the total weight of the photopolymerizable composition.

[0149] Embodiment 30 is the article of any one of embodiments 21-29, wherein at least one urethane component comprises a high number average molecular weight (Mn) urethane component having one or more urethane functional groups in the backbone of the compound and a number average molecular weight of 1,000 grams per mole (g / mol) or greater, provided that all branches from the backbone of the compound, if present, have an Mn of 200 g / mol or less.

[0150] Embodiment 31 is the article of embodiment 30, wherein the at least one urethane component comprises at least 80%, at least 85%, at least 90%, or at least 95% by weight of the high Mn urethane component.

[0151] Embodiment 32 is the article of embodiment 30 or embodiment 31, wherein at least one urethane component further comprises a low Mn urethane component having one or more urethane functional groups in the backbone of the compound and having either 1) a number average molecular weight greater than or equal to 100 g / mol and less than 1,000 g / mol, or 2) an Mn greater than or equal to 100 g / mol and less than or equal to 2,000 g / mol, with the proviso that the Mn of any one or more linear segments between two reactive groups and / or branches is less than 1,000 g / mol.

[0152] Embodiment 33 is the article of embodiment 32, wherein the at least one urethane component comprises at most 20%, at most 16%, at most 11%, at most 9%, or at most 6% by weight of a low-Mn urethane component.

[0153] Embodiment 34 is the article of embodiment 32 or embodiment 33, wherein the ratio of high Mn urethane component to low Mn urethane component ranges from 95:5 high Mn urethane component to low Mn urethane component to 80:20 high Mn urethane component to low Mn urethane component.

[0154] Embodiment 35 is the article of any one of embodiments 21-34, wherein at least one urethane component comprises a urethane (meth)acrylate, a urethane acrylamide, or a combination thereof, and wherein the at least one urethane component comprises a linking group selected from an alkyl, a polyalkylene, a polyalkylene oxide, an aryl, a polycarbonate, a polyester, a polyamide, and combinations thereof.

[0155] Embodiment 36 is the article of any one of embodiments 21-35, wherein at least one urethane component comprises a urethane (meth)acrylate comprising a polyalkylene oxide linking group, a polyamide linking group, or a combination thereof.

[0156] Embodiment 37 is the article of any of embodiments 21-36, wherein the at least one urethane component comprises two urethane components.

[0157] Embodiment 38 is the article of any of embodiments 21-37, wherein the at least one reactive diluent has a molecular weight of from 200 grams / mole to 400 grams / mole, inclusive.

[0158] Embodiment 39 is the article of any one of embodiments 21-38, wherein the at least one reactive diluent comprises a (meth)acrylate, a polyalkylene oxide di(meth)acrylate, an alkanediol di(meth)acrylate, or a combination thereof.

[0159] Embodiment 40 is the article of any one of embodiments 21-39, wherein the at least one reactive diluent comprises a (meth)acrylate.

[0160] Embodiment 41 is the article of any one of embodiments 21-40, wherein the photopolymerizable composition consists essentially of the multifunctional component.

[0161] Embodiment 42 is the article of any one of embodiments 21-41, wherein the photopolymerizable composition does not include a monofunctional component.

[0162] Embodiment 43 is the article of any one of embodiments 21-42, wherein the photopolymerizable composition comprises 25% to 50% by weight (inclusive) of at least one reactive diluent.

[0163] Embodiment 44 is the article of any one of embodiments 21-43, wherein the photopolymerizable composition further comprises 0.01 wt % to 1 wt % (inclusive) of an absorption modifier.

[0164] Embodiment 45 is the article of any one of embodiments 21 to 44, wherein the photopolymerizable composition has a viscosity of 10 Pa·s or less at a temperature of 40°C, as determined using a magnetic bearing rheometer using a 40 mm cone-plate measurement system at a shear rate of 0.1 [1 / s].

[0165] Embodiment 46 is the article of any one of embodiments 21-45, further comprising at least one filler.

[0166] Embodiment 47 is the article of any one of embodiments 21-46, further comprising at least one filler selected from silica, alumina, zirconia, and discontinuous fibers.

[0167] Embodiment 48 is the article of embodiment 47, wherein the discontinuous fibers comprise carbon, ceramic, glass, or a combination thereof.

[0168] Embodiment 49 is a method for making an article. The method includes (i) providing a photopolymerizable composition and (ii) selectively curing the photopolymerizable composition to form an article. The method also optionally includes (iii) curing any unpolymerized urethane component and / or reactive diluent remaining after step (ii). The photopolymerizable composition includes, based on the total weight of the photopolymerizable composition, (a) 50% to 90% by weight, inclusive, of at least one urethane component; (b) 5% to 50% by weight, inclusive, of at least one reactive diluent; (c) 0.1% to 5% by weight, inclusive, of a photoinitiator; and (d) optional inhibitors, when present, in an amount of 0.001% to 1% by weight, inclusive, of an optional inhibitor.

[0169] Embodiment 50 is the method of embodiment 49, further comprising (iv) repeating steps (i) and (ii) to form multiple layers to create an article having a three-dimensional structure before step (iii).

[0170] Embodiment 51 is the method of embodiment 49 or embodiment 50, wherein the photopolymerizable composition is cured using actinic radiation, including ultraviolet radiation, electron beam radiation, visible radiation, or a combination thereof.

[0171] Embodiment 52 is the method of embodiment 51, wherein the radiation is directed through a wall of a container holding the photopolymerizable composition.

[0172] Embodiment 53 is the method of any one of embodiments 49-51, wherein the photopolymerizable composition is cured through the floor of a container holding the photopolymerizable composition.

[0173] Embodiment 54 is the method of any one of embodiments 49-53, further comprising post-curing the article using actinic radiation or heat.

[0174] Embodiment 55 is the method of any one of embodiments 49-54, comprising bath polymerization of the photopolymerizable composition.

[0175] Embodiment 56 is the method of any one of embodiments 49-55, wherein the article comprises a film or a molded integral article.

[0176] Embodiment 57 is the method of any one of embodiments 49-56, wherein the article comprises an orthodontic article.

[0177] Embodiment 58 is the method of any one of embodiments 49-57, wherein the article comprises one or more channels, one or more undercuts, one or more perforations, or a combination thereof.

[0178] Embodiment 59 is the method of any one of embodiments 49-58, wherein the article comprises an elongation at break of 25% or greater.

[0179] Embodiment 60 is the method of any one of embodiments 49-59, wherein the article exhibits a tensile strength of 20 megapascals (MPa) or greater, as determined according to ASTM D638-10.

[0180] Embodiment 61 is the method of any one of embodiments 49-60, wherein the article exhibits a modulus of elasticity, as determined according to ASTM D638-10, of 200 MPa or greater.

[0181] Embodiment 62 is the method of any one of embodiments 49 through 61, wherein the at least one urethane component is present in the photopolymerizable composition in an amount of 60 wt% to 80 wt%, inclusive, of the total weight of the photopolymerizable composition.

[0182] Embodiment 63 is the method of any one of embodiments 49-62, wherein at least one urethane component comprises a high number average molecular weight (Mn) urethane component having one or more urethane functional groups in the backbone of the compound and a number average molecular weight of 1,000 grams per mole (g / mol) or greater, provided that all branches from the backbone of the compound, if present, have an Mn of 200 g / mol or less.

[0183] Embodiment 64 is the method of embodiment 63, wherein the at least one urethane component comprises at least 80%, at least 85%, at least 90%, or at least 95% by weight of a high Mn urethane component.

[0184] Embodiment 65 is the method of embodiment 63 or embodiment 64, wherein at least one urethane component further comprises a low Mn urethane component having one or more urethane functional groups in the backbone of the compound and having either 1) a number average molecular weight of 100 g / mol or more and less than 1,000 g / mol, or 2) an Mn of 100 g / mol or more and less than 2,000 g / mol, with the proviso that the Mn of any one or more linear segments between two reactive groups and / or branches is less than 1,000 g / mol.

[0185] Embodiment 66 is the method of embodiment 65, wherein the at least one urethane component comprises at most 20%, at most 16%, at most 11%, at most 9%, or at most 6% by weight of a low Mn urethane component.

[0186] Embodiment 67 is the method of embodiment 63 or embodiment 66, wherein the ratio of high Mn urethane component to low Mn urethane component ranges from 95:5 high Mn urethane component to low Mn urethane component to 80:20 high Mn urethane component to low Mn urethane component.

[0187] Embodiment 68 is the method of any one of embodiments 49-67, wherein at least one urethane component comprises a urethane (meth)acrylate, a urethane acrylamide, or a combination thereof, and wherein at least one urethane component comprises a linking group selected from an alkyl, a polyalkylene, a polyalkylene oxide, an aryl, a polycarbonate, a polyester, a polyamide, and combinations thereof.

[0188] Embodiment 69 is the method of any one of embodiments 49-68, wherein at least one urethane component comprises a urethane (meth)acrylate comprising a polyalkylene oxide linking group, a polyamide linking group, or a combination thereof.

[0189] Embodiment 70 is the method of any one of embodiments 49 to 69, wherein the at least one reactive diluent has a molecular weight of from 200 grams / mole to 400 grams / mole, inclusive.

[0190] Embodiment 71 is the method of any one of embodiments 49-70, wherein the at least one reactive diluent comprises a (meth)acrylate, a polyalkylene oxide di(meth)acrylate, an alkanediol di(meth)acrylate, or a combination thereof.

[0191] Embodiment 72 is the method of any one of embodiments 49-71, wherein the at least one reactive diluent comprises a (meth)acrylate.

[0192] Embodiment 73 is the method of any one of embodiments 49 through 72, wherein the photopolymerizable composition consists essentially of the multifunctional component.

[0193] Embodiment 74 is the method of any one of embodiments 49 through 73, wherein the photopolymerizable composition does not include a monofunctional component.

[0194] Embodiment 75 is the method of any one of embodiments 49 to 74, wherein the photopolymerizable composition comprises 25% to 50% by weight (inclusive) of at least one reactive diluent.

[0195] Embodiment 76 is the method of any one of embodiments 49 to 75, wherein the photopolymerizable composition further comprises 0.01 wt % to 1 wt % (inclusive) of an absorption modifier.

[0196] Embodiment 77 is the method of any one of embodiments 49 to 76, wherein the photopolymerizable composition has a viscosity of 10 Pa·s or less at a temperature of 40°C, as determined using a magnetic bearing rheometer using a 40 mm cone-plate measurement system at a shear rate of 0.1 [1 / s].

[0197] Embodiment 78 is the method of any one of embodiments 49 to 77, further comprising at least one filler.

[0198] Embodiment 79 is the method of any one of embodiments 49-78, further comprising at least one filler selected from silica, alumina, zirconia, and discontinuous fibers.

[0199] Embodiment 80 is the method of embodiment 79, wherein the discontinuous fibers comprise carbon, ceramic, glass, or a combination thereof.

[0200] Embodiment 81 is a non-transitory machine-readable medium. The non-transitory machine-readable medium has data representing a three-dimensional model of an article, and when accessed by one or more processors interfaced with the 3D printer, causes the 3D printer to produce the article. The article comprises the reaction product of a photopolymerizable composition comprising: (a) 50% to 90% by weight, inclusive, of at least one urethane component; and (b) 5% to 50% by weight, inclusive, of at least one reactive diluent. The photopolymerizable composition further comprises: (c) 0.1% to 5% by weight, inclusive, of a photoinitiator; and (d) an optional inhibitor, when present, in an amount of 0.001% to 1% by weight, inclusive, based on the total weight of the photopolymerizable composition. The article exhibits an elongation at break of 25% or greater.

[0201] Embodiment 82 is a method. The method includes retrieving data representing a 3D model of an article from a non-transitory machine-readable medium, executing, by one or more processors, a 3D printing application that interfaces with a manufacturing device using the data, and generating, by the manufacturing device, a physical object of the article. The article comprises the reaction product of a photopolymerizable composition including: (a) 50% to 90% by weight, inclusive, of at least one urethane component; and (b) 5% to 50% by weight, inclusive, of at least one reactive diluent. The photopolymerizable composition further includes: (c) 0.1% to 5% by weight, inclusive, of a photoinitiator; and (d) an optional inhibitor, when present, in an amount of 0.001% to 1% by weight, inclusive, based on the total weight of the photopolymerizable composition. The article exhibits an elongation at break of 25% or greater.

[0202] Embodiment 83 is an article produced using the method of embodiment 82.

[0203] Embodiment 84 is the article of embodiment 82, comprising an orthodontic article.

[0204] Embodiment 85 is a method. The method includes receiving, by a manufacturing device having one or more processors, a digital object including data defining multiple layers of an article, and generating an article based on the digital object using the manufacturing device by an additive manufacturing process. The article includes the reaction product of a photopolymerizable composition including: (a) 50% to 90% by weight, inclusive, of at least one urethane component; and (b) 5% to 50% by weight, inclusive, of at least one reactive diluent. The photopolymerizable composition further includes: (c) 0.1% to 5% by weight, inclusive, of a photoinitiator; and (d) an optional inhibitor, when present, in an amount of 0.001% to 1% by weight, inclusive, based on the total weight of the photopolymerizable composition. The article exhibits an elongation at break of 25% or greater.

[0205] Embodiment 86 is the method of embodiment 85, wherein the additive manufacturing equipment selectively cures the photopolymerizable composition to form an article. The photopolymerizable composition comprises: (a) 50% to 90% by weight, inclusive, of at least one urethane component; and (b) 5% to 50% by weight, inclusive, of at least one reactive diluent. The photopolymerizable composition further comprises: (c) 0.1% to 5% by weight, inclusive, of a photoinitiator; and (d) an optional inhibitor, if present, in an amount of 0.001% to 1% by weight, inclusive, based on the total weight of the photopolymerizable composition. The article exhibits an elongation to break of 25% or greater.

[0206] Embodiment 87 is the method of embodiment 86, further comprising curing any unpolymerized urethane components and / or reactive diluents remaining in the article.

[0207] Embodiment 88 is the method of embodiment 86 or embodiment 87, wherein the article comprises an orthodontic article.

[0208] Embodiment 89 is a system. The system includes a display that displays a 3D model of an article and one or more processors that cause a 3D printer to create a physical object of the article in response to a 3D model selected by a user. The article includes the reaction product of a photopolymerizable composition that includes: (a) 50% to 90% by weight, inclusive, of at least one urethane component; and (b) 5% to 50% by weight, inclusive, of at least one reactive diluent. The photopolymerizable composition further includes: (c) 0.1% to 5% by weight, inclusive, of a photoinitiator; and (d) an optional inhibitor, when present, in an amount of 0.001% to 1% by weight, inclusive, based on the total weight of the photopolymerizable composition. The article exhibits an elongation at break of 25% or greater. [Example]

[0209] Objects and advantages of the present disclosure are further illustrated by the following examples; however, the particular materials and amounts thereof recited in these examples, as well as other conditions and details, should not be construed to unduly limit the present disclosure.

[0210] Testing of Exemplary Compositions The materials used in the following examples are summarized in Table 1.

[0211] [Table 1]

[0212] Preparation of compounded resin Resins were prepared according to the formulations listed in Table 2 below by tumble mixing the ingredients overnight to ensure thorough mixing.

[0213] [Table 2]

[0214] Resin viscosity The absolute (e.g., dynamic) viscosity of the resins of the examples was measured using a TA Instruments AR-G2 magnetic bearing rheometer using a 40 mm cone-plate measurement system at a shear rate of 0.1 [1 / s] at 40° C. Two replicates were measured, and the average value was reported as viscosity (units: Pa·s) in Table 3 below.

[0215] [Table 3]

[0216] Physical properties of polymers from cast resin formulations The Example 1 (E-1) formulation shown in Table 1 was mixed in a glass jar. The E-1 mixture was placed on a rolling mixer to create a homogeneous mixture. The mixture was degassed and mixed for 90 seconds at 2000 rpm under vacuum in a THINKY Planetary Mixer (Thinky Corporation, Tokyo). The mixture was then poured into a silicone dogbone mold (V-shaped mold, ASTM D638-10). The filled mold was placed between two glass plates and cured for 5 minutes in a broad-spectrum UV chamber (Dymax Light Curing Systems Model 2000 Flood). According to ASTM D638-10, the sample was demolded and cured in the chamber for an additional 5 minutes. These dogbone samples were tested at a speed of 5 mm / min on an Insight MTS with a 5 kN load cell. Five replicate samples were tested, and the average and standard deviation are reported. According to ASTM D638-10, the tensile strength, tensile modulus, and elongation at break of the samples were determined and are shown in Table 4 below.

[0217] The following Examples, E-2 through E-8 and CE-1 through CE-4, were made in the same manner (the formulations of these Examples are summarized in Table 2 above) and tested. Test results for the cast samples are summarized in Table 4 below.

[0218] [Table 4]

[0219] Additive Manufacturing of Tailored Resins 385 nm and approximately 23 mW / cm 2E-3 and E-7 resin formulations were photopolymerized using an Asiga Pico 2 printer with a 1000 W power LED light source. V-shaped tensile test bars according to ASTM D638-10 were produced. The printer's resin bath was heated to 35-40°C prior to photopolymerization to reduce the viscosity so that tensile test bars could be produced. The settings used were slice thickness = 50 μm, burn-in layers = 3, separation speed = 10 mm / s, number of slides per layer = 1, burn-in exposure time = 15.0 s, and normal exposure time = 3.1 s. The test bars were then washed in isopropanol to remove unreacted resin. The test bars were then post-cured under a fusion lamp for 90 minutes on each side. The post-cured dog bones were tested at a speed of 5 mm / min on an Insight MTS with a 5 kN load cell. Five replicate samples were tested, and the average and standard deviation are reported. The tensile strength of the samples was determined according to ASTM D638-10 and is shown in Table 5 below.

[0220] [Table 5]

[0221] Additive manufacturing of aligner articles from compounded resins 385 nm and approximately 16 mW / cm 2 The E-3 formulation was photopolymerized using an Asiga Pico 2HD printer with a 1000W power LED light source. The aligner STL file was loaded into the software and the support structure was generated. The printer's resin bath was heated to 35-40°C prior to photopolymerization to reduce the viscosity so that the part could be fabricated. The settings used were slice thickness = 50 μm, burn-in layers = 3, separation speed = 10 mm / s, number of slides per layer = 1, burn-in exposure time = 15.0 s, and normal exposure time = 3.1 s. The photopolymerized aligner was then washed in isopropanol to remove unreacted resin and then post-cured under a fusion lamp for 90 minutes on each side. The photopolymerized aligner fit a model demonstrating the accuracy of the additively manufactured part. The aligner also had acceptable strength and flexibility.

[0222] All of the above patents and patent applications are expressly incorporated herein by reference. The above-described embodiments are illustrative of the invention, and other constructions are possible. Accordingly, the present invention should not be deemed limited to the embodiments described in detail above and illustrated in the accompanying drawings, but rather should be limited only by the fair scope of the following claims, including equivalents.

Claims

1. 1. An orthodontic article comprising the reaction product of a photopolymerizable composition, the photopolymerizable composition comprising, based on the total weight of the photopolymerizable composition: (a) 50% to 90% by weight, inclusive, of at least one urethane component, the at least one urethane component comprising a urethane (meth)acrylate or a urethane (meth)acrylate oligomer; (b) 5% to 50% by weight, inclusive, of at least one reactive diluent having a molecular weight of 400 grams per mole or less, not containing any urethane functionality, and comprising a methacrylate; (c) 0.1 wt % to 5 wt % (inclusive) of a photoinitiator; and (d) an optional inhibitor, if present, in an amount of 0.001% to 1% by weight, inclusive; Including, the urethane component comprises a high Mn urethane component (excluding those corresponding to the low Mn urethane component described below) having a number average molecular weight of 1,000 g / mol or more, provided that all branches from the main chain of the compound, if present, have an Mn of 200 g / mol or less, and a low Mn urethane component having a number average molecular weight of less than 1,000 g / mol, or a number average molecular weight of 2,000 g / mol or less, provided that the number average molecular weight of any one or more linear chain portions between two reactive groups and / or branches is less than 1,000 g / mol, and 80% by weight or more of the urethane component is the high Mn urethane component; The photopolymerizable composition does not contain a monofunctional component, the orthodontic article exhibits an elongation at break of 25% or greater as measured in accordance with ASTM D638-10; Orthodontic items.

2. The orthodontic article of claim 1 , comprising one or more channels, one or more undercuts, one or more perforations, or a combination thereof.

3. 3. The orthodontic article of claim 1 or 2, having a tensile strength of 20 megapascals (MPa) or greater, as determined according to ASTM D638-10.

4. The orthodontic article of any one of claims 1 to 3, having a modulus of elasticity, determined according to ASTM D638-10, of 200 MPa or greater.

5. 1. A method of manufacturing an orthodontic article, comprising: (i) providing a photopolymerizable composition; (ii) selectively hardening the photopolymerizable composition to form an orthodontic article; (iii) optionally curing any unpolymerized urethane component and / or reactive diluent remaining after step (ii); and Including, The photopolymerizable composition comprises, based on the total weight of the photopolymerizable composition: (a) 50% to 90% by weight, inclusive, of at least one urethane component, the at least one urethane component comprising a urethane (meth)acrylate or a urethane (meth)acrylate oligomer; (b) 5% to 50% by weight, inclusive, of at least one reactive diluent having a molecular weight of 400 grams per mole or less, not containing any urethane functionality, and comprising a methacrylate; (c) 0.1 wt % to 5 wt % (inclusive) of a photoinitiator; and (d) an optional inhibitor, if present, in an amount of 0.001% to 1% by weight, inclusive; Including, The photopolymerizable composition does not contain a monofunctional component, the urethane component comprises a high Mn urethane component (excluding those corresponding to the low Mn urethane component described below) having a number average molecular weight of 1,000 g / mol or more, provided that all branches from the main chain of the compound, if present, have an Mn of 200 g / mol or less, and a low Mn urethane component having a number average molecular weight of less than 1,000 g / mol, or a number average molecular weight of 2,000 g / mol or less, provided that the number average molecular weight of any one or more linear chain portions between two reactive groups and / or branches is less than 1,000 g / mol, and 80% by weight or more of the urethane component is the high Mn urethane component; the orthodontic article exhibits an elongation at break of 25% or greater as measured in accordance with ASTM D638-10; method.

6. 6. The method of claim 5, further comprising: (iv) repeating steps (i) and (ii) to form multiple layers to create an orthodontic article having a three-dimensional structure prior to step (iii).

7. 1. A non-transitory machine-readable medium having data representing a three-dimensional model of an orthodontic article, the medium having data representing a three-dimensional model of an orthodontic article, the data comprising: The orthodontic article comprises the reaction product of a photopolymerizable composition, the photopolymerizable composition comprising, based on the total weight of the photopolymerizable composition: (a) 50% to 90% by weight, inclusive, of at least one urethane component, the at least one urethane component comprising a urethane (meth)acrylate or a urethane (meth)acrylate oligomer; (b) 5% to 50% by weight, inclusive, of at least one reactive diluent having a molecular weight of 400 grams per mole or less, not containing any urethane functionality, and comprising a methacrylate; (c) 0.1 wt % to 5 wt % (inclusive) of a photoinitiator; and (d) an optional inhibitor, if present, in an amount of 0.001% to 1% by weight, inclusive; Including, the urethane component comprises a high Mn urethane component (excluding those corresponding to the low Mn urethane component described below) having a number average molecular weight of 1,000 g / mol or more, provided that all branches from the main chain of the compound, if present, have an Mn of 200 g / mol or less, and a low Mn urethane component having a number average molecular weight of less than 1,000 g / mol, or a number average molecular weight of 2,000 g / mol or less, provided that the number average molecular weight of any one or more linear chain portions between two reactive groups and / or branches is less than 1,000 g / mol, and 80% by weight or more of the urethane component is the high Mn urethane component; The photopolymerizable composition does not contain a monofunctional component, the orthodontic article exhibits an elongation at break of 25% or greater as measured in accordance with ASTM D638-10; Non-transitory machine-readable medium.

8. receiving, by a manufacturing device having one or more processors, a digital object including data defining a plurality of layers of an orthodontic article; generating the orthodontic article based on the digital object using the manufacturing device by an additive manufacturing process, The orthodontic article comprises the reaction product of a photopolymerizable composition, the photopolymerizable composition comprising, based on the total weight of the photopolymerizable composition: (a) 50% to 90% by weight, inclusive, of at least one urethane component, the at least one urethane component comprising a urethane (meth)acrylate or a urethane (meth)acrylate oligomer; (b) 5% to 50% by weight, inclusive, of at least one reactive diluent having a molecular weight of 400 grams per mole or less and free of any urethane functionality; at least one reactive diluent comprising a methacrylate; (c) 0.1 wt % to 5 wt % (inclusive) of a photoinitiator; and (d) an optional inhibitor, if present, in an amount of 0.001% to 1% by weight, inclusive; Including, the urethane component comprises a high Mn urethane component (excluding those corresponding to the low Mn urethane component described below) having a number average molecular weight of 1,000 g / mol or more, provided that all branches from the main chain of the compound, if present, have an Mn of 200 g / mol or less, and a low Mn urethane component having a number average molecular weight of less than 1,000 g / mol, or a number average molecular weight of 2,000 g / mol or less, provided that the number average molecular weight of any one or more linear chain portions between two reactive groups and / or branches is less than 1,000 g / mol, and 80% by weight or more of the urethane component is the high Mn urethane component; the photopolymerizable composition does not comprise a monofunctional component; The method, wherein the orthodontic article exhibits an elongation at break of 25% or greater as measured in accordance with ASTM D638-10.

9. a display for displaying a 3D model of the orthodontic article; one or more processors that cause a 3D printer to create the physical object of the orthodontic article in response to a 3D model selected by a user; A system comprising: The orthodontic article comprises the reaction product of a photopolymerizable composition, the photopolymerizable composition comprising, based on the total weight of the photopolymerizable composition: (a) 50% to 80% by weight, inclusive, of at least one urethane component, the at least one urethane component comprising a urethane (meth)acrylate or a urethane (meth)acrylate oligomer; (b) 5% to 50% by weight, inclusive, of at least one reactive diluent having a molecular weight of 400 grams per mole or less, not containing any urethane functionality, and comprising a methacrylate; (c) 0.1 wt % to 5 wt % (inclusive) of a photoinitiator; and (d) an optional inhibitor, if present, in an amount of 0.001% to 1% by weight, inclusive; Including, the urethane component comprises a high Mn urethane component (excluding those corresponding to the low Mn urethane component described below) having a number average molecular weight of 1,000 g / mol or more, provided that all branches from the main chain of the compound, if present, have an Mn of 200 g / mol or less, and a low Mn urethane component having a number average molecular weight of less than 1,000 g / mol, or a number average molecular weight of 2,000 g / mol or less, provided that the number average molecular weight of any one or more linear chain portions between two reactive groups and / or branches is less than 1,000 g / mol, and 80% by weight or more of the urethane component is the high Mn urethane component; The photopolymerizable composition does not contain a monofunctional component, the orthodontic article exhibits an elongation at break of 25% or greater as measured in accordance with ASTM D638-10; system.

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