This application is the U.S. national phase of International Application No. PCT/EP2017/077779, filed 30 Oct. 2017, which designated the EP and claims priority to the following EP Application No. 16196338.4, filed 28 Oct. 2016. The entirety of the contents of each of these applications is hereby incorporated by reference as if fully set forth herein.

FIELD

The invention relates to thermosetting compositions and methods for producing three-dimensional objects by additive fabrication techniques, and articles produced therefrom.

BACKGROUND

Additive fabrication, also known as three-dimensional printing, is a technique for forming three-dimensional objects from computer data by building up objects one portion at a time until a final three-dimensional object is produced. Additive techniques can be contrasted with subtractive techniques, such as milling, wherein portions of material are removed from a larger amount of material to produce the final three-dimensional object.

Various types of materials are used in additive fabrication processes. Generally, thermoplastic materials are used in, for example fused filament fabrication (FFF) and selective laser sintering (SLS) processes, whereas thermoset materials are used in, for example vat based processes and processes that involve jetting of liquid materials.

Generally, electromagnetic radiation is used to encourage rapid curing of the thermosetting materials. The electromagnetic radiation may be UV, visible, or infrared light and may be applied, for example, by lasers, lamps, or LEDs. The electromagnetic radiation may be applied selectively, e.g. by drawing a specific pattern with a laser, using a digital micromirror device (DMD), or a mask, or unselectively, e.g. by passing a lamp over the entirety of a surface. Post-processing by applying additional temperature or light to the newly formed three-dimensional object may be necessary to achieve the desired properties of a three-dimensional object formed from a thermosetting composition.

Various advances have been made to thermosetting materials for additive fabrication to improve the mechanical properties of the finished article. For example, US2010/0304088 describes a radiation curable resin composition comprising cationically polymerizable components and an impact modifier that, after full cure, results in a material having a high tensile modulus and high toughness, as shown by high impact strength and/or high resistance against crack propagation.

In US2011/0104500, there is described a radiation curable resin that, upon cure, attains a desirable combination of modulus, impact strength, heat deflection temperature, and water absorption. The radiation curable resin comprises a combination of epoxy functional components, an oxetane component, a (meth) acrylate component, an impact modifier, a free-radical photo-initiators, and a cationic photo-initiator.

Although various advances have been made to thermosetting materials for additive fabrication in recent years, the industry continues to demand better mechanical properties. An example of a material that has not yet been realized is a photo-polymerizable material that simultaneously achieves high glass transition temperature (Tg) and high toughness.

SUMMARY

The invention employs an oligomer comprising i) a backbone comprising a polyepoxide based on Bisphenol A, F, or S, a polyepoxide based on hydrogenated Bisphenol A, F, or S, a polycarbonate, or a polyimide, and ii) a number average of at least two polymerizable groups per molecule, wherein the polymerizable groups comprise acrylate, methacrylate, itaconate, vinyl ether, allyl ether, maleate, or fumarate (hereinafter, “first oligomer”). The first oligomer has a number average molecular weight of from 800 to 10,000 g/mol and a glass transition temperature (Tg) of 40° C. or more. The first oligomers may be employed in compositions, such as compositions for forming a three-dimensional object via an additive fabrication processes, or as a kit of materials, which forms a composition when the elements of the kit of materials are combined.

In an embodiment, the first oligomer is present in a composition as part of a first-network forming component consisting of 19.95 to 80 wt % of the first oligomer, 19.95 to 80 wt % of one or more first network monomers having a number average of 0.95 to 1.1 polymerizable groups, 0.05 to 5 wt % of one or more first network-forming initiators, and, optionally, up to 15 wt % of one or more further first network, monomers, oligomers, or polymers having a number average of 2 or more polymerizable groups. The substituents of the first network-forming component are able to (co)polymerize with the polymerizable groups of the first oligomer and/or the one or more first-network monomers. If a component of the polymerizable composition cannot (co)polymerize with any of the first network-forming components then the component cannot be a first network-forming component. Particulate fillers that comprise polymerizable groups that are able to (co)polymerize with the polymerizable groups of the first oligomer are not part of the first network-forming component.

An optional second network-forming component may be present in the composition. The second network-forming component comprises one or more second network compounds that comprise polymerizable groups that do not (co)polymerize with the polymerizable groups of the first oligomer, and a second network initiator for initiating polymerization of the one or more second network compounds.

The components of the composition may also be separated and provided as a kit of materials. Further embodiments of the invention are described below.

