Radiation curable resin composition for manufacturing three-dimensional molds

Abstract

The present disclosure relates to a radiation curable composition comprising (a) at least one photopolymerizable liquid; (b) at least one spherical inorganic particle having an average particle size D50 of 50 to 2000 nm; and (c) at least one photoinitiator.

Description

Technical Field

[0001] The present invention relates to the technical field of chemical materials for three-dimensional (hereinafter referred to as "3D") printing, and in particular to a radiation-curable composition containing spherical inorganic particles. The present invention further relates to a method for forming a 3D object by using the composition, and to a 3D object formed by using the composition. Background Art

[0002] 3D printing or additive manufacturing (AM) is a manufacturing method that aims to avoid traditional manufacturing techniques, which are either subtractive manufacturing techniques (i.e. machining and ablation) or form-based manufacturing techniques (i.e. molding and casting), and in doing so brings considerable benefits in terms of design freedom. Radiation-curable photopolymers are a class of 3D printable materials that have been widely used in various applications, including prototyping of plastic parts, metal investment casting, dental applications, etc. To date, radiation-curable photopolymers available in the market are suitable for making prototypes and demonstrations, but may not be sufficient for actual applications that require thermal and mechanical properties. In order to bridge the gap from prototyping to actual manufacturing, it is crucial to have advanced materials that have specific properties required by the targeted industrial applications.

[0003] 3D printing can be an effective way to manufacture molds, which usually requires materials with sufficient heat deflection temperature (HDT) and mechanical properties, which can hardly be achieved by traditional acrylate-based photopolymers. Therefore, it becomes crucial to adopt new processes in 3D material development to obtain advanced properties that can match existing plastics made with traditional manufacturing methods.

[0004] To solve this problem, attempts have been made to combine inorganic fillers with photopolymerizable liquids in radiation 3D printing processes. However, inorganic fillers will significantly increase the viscosity of the liquid, making 3D printing impossible. Although some curable compositions containing inorganic fillers have been developed, the viscosity of these compositions is still very high, which limits the 3D printing process, or the mechanical properties of the 3D printed objects are unsatisfactory. Therefore, there is a strong need to provide a ceramic-like radiation-curable composition with good dispersibility that can develop 3D printed objects with high HDT and high stiffness as well as good printability and high precision. Summary of the invention

[0005] The object of the present invention is to provide a radiation curable composition with good dispersibility, which enables the development of 3D objects with high HDT and high stiffness, wherein the radiation curable composition comprises (a) at least one photopolymerizable liquid;

[0006] (b) at least one average particle size D 50Spherical inorganic particles with a diameter of 50 to 2000 nm; and (c) at least one photoinitiator.

[0007] Another object of the present invention is to provide a 3D printed object formed from the radiation curable composition.

[0008] It is a further object of the present invention to provide a method of forming a 3D printed object by using the radiation curable composition of the present invention.

[0009] It has been surprisingly found that the above objects can be achieved by the following embodiments:

[0010] (a) at least one photopolymerizable liquid;

[0011] (b) at least one average particle size D 50 Spherical inorganic particles with a diameter of 50 to 2000 nm;

[0012] (c) at least one photoinitiator.

[0013] In one embodiment, the average particle size D of the spherical inorganic particles is 50 In the range of 100 to 1500 nm, preferably 300 to 1000 nm.

[0014] In another embodiment, the spherical inorganic particles are surface treated with silanes, preferably with alkoxysilanes.

[0015] In further embodiments, the spherical inorganic particles are spherical silica particles.

[0016] Another object of the present invention is a 3D printed object formed from the radiation curable composition.

[0017] The radiation curable composition according to the present invention exhibits excellent stability and good printing accuracy, and is easy to 3D print due to low viscosity. Objects formed from the radiation curable composition also exhibit high HDT values ​​and sufficient mechanical properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 The stability test of Examples 4-7 and Comparative Example 1 at 25°C using a centrifuge is shown.

[0019] FIG. 2( a ) shows a picture of a standard reference model, and FIG. 2( b ) shows a picture of a 3D printed object obtained by printing the composition of Example 10 according to the standard reference model.

[0020] Figure 3 A picture of a 3D printed object obtained by printing the composition of Example 10 is shown. DETAILED DESCRIPTION

[0021] Unless defined otherwise, all technical and scientific terms used herein have the meaning commonly understood by one of ordinary skill in the art to which the invention belongs. As used herein, unless otherwise stated, the following terms have the meanings ascribed to them below.

[0022] As used herein, the articles "a," "an," and "the" refer to one or more of the species specified by the term following the article.

[0023] The term "liquid" as used in the present invention is equivalent to "liquid at room temperature", which is typically a temperature between about 5°C and about 30°C.

[0024] In the context of this disclosure, any specific values ​​mentioned for features (including specific values ​​mentioned as endpoints in ranges) can be recombined to form new ranges.

[0025] Photopolymerizable liquid (a)

[0026] The radiation curable composition of the present invention comprises as component (a) at least one photopolymerizable liquid.

[0027] In an embodiment of the present invention, the photopolymerizable liquid (a) of the present invention comprises monomers and / or oligomers containing at least one radiation curable functional group.

[0028] The radiation-curable functional group of the photopolymerizable liquid (a) of the present invention can be selected from the group consisting of ethylenically unsaturated functional groups, epoxy groups or mixtures thereof. For example, at least one radiation-curable functional group of the monomer and / or oligomer containing at least one radiation-curable functional group suitable as the photopolymerizable liquid (a) is selected from the group consisting of ethylenically unsaturated functional groups, epoxy groups and mixtures thereof.

[0029] Preferably, the number of radiation-curable functional groups in the photopolymerizable liquid (a) is in the range of 1 to 12, for example 1.2, 1.5, 1.8, 2, 2.2, 2.5, 3, 3.5, 4, 5, 6, 7, 8, 9, 10, 11, preferably 1 to 10, such as 1 to 8, or 1.5 to 6 per molecule of photopolymerizable liquid (a).

[0030] As the photopolymerizable liquid (a) containing at least one epoxy group, non-limiting examples may include epoxidized olefins, aromatic glycidyl ethers, aliphatic glycidyl ethers, or a combination thereof, preferably aromatic or aliphatic glycidyl ethers.

[0031] Examples of possible epoxidized olefins include epoxidized C2-C 10Olefins, such as ethylene oxide, propylene oxide, isobutylene oxide, 1-butene oxide, 2-butene oxide, vinylethylene oxide, styrene oxide or epichlorohydrin, preferably ethylene oxide, propylene oxide, isobutylene oxide, vinylethylene oxide, styrene oxide or epichlorohydrin, particularly preferably ethylene oxide, propylene oxide or epichlorohydrin and very particularly preferably ethylene oxide and epichlorohydrin.

[0032] Aromatic glycidyl ethers are, for example, bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, bisphenol B diglycidyl ether, bisphenol S diglycidyl ether, hydroquinone diglycidyl ether, alkylation products of phenol / dicyclopentadiene, such as 2,5-bis[(2,3-epoxypropoxy)phenyl]octahydro-4,7-methano-5H-indene (CAS No. [13446-85-0]), tris[4-(2,3-epoxypropoxy)phenyl]methane isomers (CAS No. [66072-39-7]), phenol-based epoxy novolacs (CAS No. [9003-35-4]) and cresol-based epoxy novolacs (CAS No. [37382-79-9]).

[0033] Examples of the aliphatic glycidyl ethers include 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane triglycidyl ether, pentaerythritol tetraglycidyl ether, 1,1,2,2-tetrakis[4-(2,3-epoxypropoxy)phenyl]ethane (CAS No. [27043-37-4]), diglycidyl ether of polypropylene glycol (α,ω-bis(2,3-epoxypropoxy)poly(oxypropylene), CAS No. [16096-30-3]), and diglycidyl ether of hydrogenated bisphenol A (2,2-bis[4-(2,3-epoxypropoxy)cyclohexyl]propane, CAS No. [13410-58-7]).

[0034] More preferably, the photopolymerizable liquid (a) of the present invention contains at least one ethylenically unsaturated functional group.

[0035] In an embodiment of the present invention, the ethylenically unsaturated functional group contains a carbon-carbon unsaturated bond, such as those found in the following functional groups: allyl, vinyl, acrylate, methacrylate, acryloxy, methacryloyloxy, acrylamide, methacrylamide, ethynyl, maleimide, etc.; preferably, the ethylenically unsaturated functional group contains acrylate or methacrylate.

[0036] In a preferred embodiment of the present invention, the photopolymerizable liquid (a) of the present invention contains, in addition to ethylenically unsaturated functional groups and / or epoxy groups, urethane groups, ether groups, ester groups, carbonate groups and any combination thereof.

[0037] As the photopolymerizable liquid (a) of the present invention, the oligomer containing at least one radiation-curable functional group includes, for example, an oligomer containing a core structure optionally connected to an ethylenically unsaturated functional group by a linking group. The linking group can be an ether, ester, amide, carbamate, carbonate or carbonate group. In some cases, the linking group is an ethylenically unsaturated functional group, for example a part of acryloxy or acrylamide. The core group can be an alkyl (straight and branched alkyl), an aryl (for example phenyl), a polyether, a polyester, a siloxane, carbamate or other core structures and oligomers thereof. Suitable ethylenically unsaturated functional groups can include a group containing a carbon-carbon double bond, such as a methacrylate group, an acrylate group, a vinyl ether group, an allyl ether group, an acrylamide group, a methacrylamide group or a combination thereof, preferably a methacrylate or an acrylate. In certain embodiments, suitable oligomers include monofunctional and / or multifunctional acrylates, such as mono(methyl)acrylate, di(methyl)acrylate, tri(methyl)acrylate or higher acrylate or a combination thereof. Optionally, the oligomer may include a siloxane backbone to further improve the curing, flexibility, and / or other properties of the radiation curable composition for 3D printing.

[0038] In some embodiments, the oligomer containing at least one ethylenically unsaturated functional group can be selected from the following categories: carbamate (e.g., carbamate-based oligomer containing ethylenically unsaturated functional groups), polyether (e.g., polyether-based oligomer containing ethylenically unsaturated functional groups), polyester (e.g., polyester-based oligomer containing ethylenically unsaturated functional groups), polycarbonate (e.g., polycarbonate-based oligomer containing ethylenically unsaturated functional groups), polyestercarbonate (e.g., polyestercarbonate-based oligomer containing ethylenically unsaturated functional groups), epoxy (e.g., epoxy-based oligomer containing ethylenically unsaturated functional groups), silicone (e.g., silicone-based oligomer containing ethylenically unsaturated functional groups), or any combination thereof. Preferably, the oligomer containing at least one ethylenically unsaturated functional group may be selected from the following categories: urethane-based oligomers, epoxy-based oligomers, polyester-based oligomers, polyether-based oligomers, polyether urethane-based oligomers, polyester urethane-based oligomers or silicone-based oligomers, and any combination thereof.

[0039] In a preferred embodiment of the present invention, the oligomer containing at least one ethylenically unsaturated functional group includes an oligomer based on carbamate, which includes a carbamate repeating unit and one, two or more ethylenically unsaturated functional groups, such as those containing carbon-carbon unsaturated double bonds, such as (methyl) acrylate groups, (methyl) acrylamide groups, allyl groups and vinyl groups. Preferably, the oligomer contains at least one carbamate bond (e.g., one, two or more carbamate bonds) in the skeleton of the oligomer molecule and at least one acrylate and / or methacrylate functional group (e.g., one, two or more acrylate and / or methacrylate functional groups) side-connected to the oligomer molecule. In certain embodiments, aliphatic, alicyclic or mixed aliphatic and alicyclic carbamate repeating units are suitable. Carbamate is typically prepared by the condensation of diisocyanates and diols. It is useful for each repeating unit to have an aliphatic carbamate with at least two carbamate moieties. Furthermore, the diisocyanates and diols used to prepare the urethanes contain divalent aliphatic groups which may be the same or different.

[0040] In one embodiment, the oligomer containing at least one ethylenically unsaturated functional group includes a polyester urethane-based oligomer or a polyether urethane-based oligomer containing at least one ethylenically unsaturated functional group. The ethylenically unsaturated functional group may be one containing a carbon-carbon unsaturated double bond, such as an acrylate group, a methacrylate group, a vinyl group, an allyl group, an acrylamide group, a methacrylamide group, etc., preferably an acrylate group and a methacrylate group.

[0041] Suitable oligomers based on carbamates are known in the art and can be easily synthesized by a variety of different procedures. For example, a polyfunctional alcohol can react with a polyisocyanate (preferably, a stoichiometric excess of polyisocyanate) to form an NCO-terminated pre-oligomer, which is thereafter reacted with a hydroxy-functional ethylenically unsaturated monomer (such as a hydroxy-functional (meth) acrylate). The polyfunctional alcohol can be any compound containing two or more OH groups per molecule, and can be a monomeric polyol (e.g., a diol), a polyester polyol, a polyether polyol, etc. In one embodiment of the invention, the oligomer based on carbamates is an oligomer based on aliphatic carbamates containing a (meth) acrylate functional group.

[0042] Suitable oligomers based on polyether or polyester urethanes include the reaction products of aliphatic or aromatic polyether or polyester polyols and aliphatic or aromatic polyisocyanates functionalized with monomers containing ethylenically unsaturated functional groups such as (meth)acrylate groups. In a preferred embodiment, the polyethers and polyesters are aliphatic polyethers and polyesters, respectively. In a preferred embodiment, the oligomers based on polyether and polyester urethanes are oligomers based on aliphatic polyether and polyester urethanes and contain (meth)acrylate groups.

[0043] In one embodiment, the viscosity of the oligomer containing at least one ethylenically unsaturated functional group at 60° C. can be in the range of 200 to 200,000 cP, such as 500 cP, 800 cP, 1000 cP, 2000 cP, 3000 cP, 4000 cP, 5000 cP, 6000 cP, 7000 cP, 8000 cP, 10000 cP, 20000 cP, 30000 cP. , 40000 cP, 50000 cP, 60000 cP, 70000 cP, 80000 cP, 90000 cP, 95000 cP, preferably 500 to 60000 cP, for example 1000 to 50000 cP, 2000 to 40000 cP, 3000 to 20000 cP, 4000 to 15000 cP, or 20000 cP to 60000 cP, as measured according to DIN EN ISO 3219.

[0044] The monomer can reduce the viscosity of the composition. The monomer can be monofunctional or multifunctional (such as difunctional, trifunctional), preferably monofunctional. In one embodiment, the monomer can be selected from the group consisting of: (meth)acrylate monomers, (meth)acrylamide monomers, vinyl aromatic compounds with up to 20 carbon atoms, vinyl esters of carboxylic acids with up to 20 carbon atoms, α,β-unsaturated carboxylic acids with 3 to 8 carbon atoms and their anhydrides, and vinyl-substituted heterocycles,

[0045] In the context of the present disclosure, the term "(meth)acrylate monomer" means a monomer comprising a (meth)acrylate moiety. The structure of the (meth)acrylate moiety is as follows:

[0046]

[0047] wherein R is H or methyl.

[0048] The (meth)acrylate monomer may be a monofunctional or multifunctional (eg, bifunctional, trifunctional) (meth)acrylate monomer. Exemplary (meth)acrylate monomers may include (meth)acrylic acid C1 to C 20 Alkyl esters, (meth)acrylic acid C1 to C10 Hydroxyalkyl esters, (meth) acrylic acid C3 to C 10 Cycloalkyl esters, urethane acrylates, 2-(2-ethoxy)ethyl acrylate, tetrahydrofurfuryl (meth)acrylate, 2-phenoxyethyl acrylate, dicyclopentenyloxyethyl (meth)acrylate, dicyclopentadienyl (meth)acrylate, caprolactone (meth)acrylate, morpholine (meth)acrylate, ethoxylated nonylphenol (meth)acrylate, (5-ethyl-1,3-dioxan-5-yl) methacrylate, phenyl (meth)acrylate, benzyl (meth)acrylate, phenethyl (meth)acrylate, dicyclopentyl (meth)acrylate, 3,3,5-trimethylcyclohexyl (meth)acrylate and dicyclopentenyl (meth)acrylate.

[0049] (Meth) acrylic acid C1 to C 20 Specific examples of the alkyl ester may include methyl (meth)acrylate, ethyl (meth)acrylate, isopropyl (meth)acrylate, n-propyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, sec-butyl (meth)acrylate, amyl (meth)acrylate, n-hexyl (meth)acrylate, octyl (meth)acrylate, isooctyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, n-lauryl (meth)acrylate, n-tridecyl (meth)acrylate, n-cetyl (meth)acrylate, n-stearyl (meth)acrylate, isomyristyl (meth)acrylate, stearyl (meth)acrylate, and isostearyl (meth)acrylate (ISTA). Preferably, C6 to C8 (meth)acrylate is used. 18 Alkyl esters, especially (meth) acrylic acid C6 to C 16 Alkyl ester or (meth) acrylic acid C8 to C 12 Alkyl esters.

[0050] (Meth) acrylic acid C1 to C 10 Specific examples of hydroxyalkyl esters, such as C2 to C8 hydroxyalkyl (meth)acrylates, may include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, or 3-hydroxy-2-ethylhexyl (meth)acrylate, etc.

[0051] (Meth) acrylic acid C3 to C 10 Specific examples of the cycloalkyl ester may include isobornyl acrylate, isobornyl methacrylate, cyclohexyl acrylate, or cyclohexyl methacrylate.

[0052] Examples of monofunctional acrylates include methyl acrylate, ethyl acrylate, butyl acrylate, 2-(2-ethoxy)ethyl acrylate, tetrahydrofurfuryl acrylate, lauryl acrylate, isooctyl acrylate, isodecyl acrylate, 2-phenoxyethyl acrylate, 2-ethylhexyl acrylate, isobornyl acrylate, dicyclopentenyloxyethyl acrylate, dicyclopentadienyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxybutyl acrylate, 4-hydroxybutyl acrylate, caprolactone acrylate, morpholine acrylate, epoxy-acrylate hybrid monomers such as 3,4-epoxy-cyclohexyl-14-methyl acrylate.

[0053] In the context of the present disclosure, the term "(meth)acrylamide monomer" means a monomer comprising a (meth)acrylamide moiety. The structure of the (meth)acrylamide moiety is as follows: CH2=CR 1 -CO-N, where R 1 is hydrogen or methyl. Specific examples of the (meth)acrylamide monomer may include acryloylmorpholine, methacryloylmorpholine, N-(hydroxymethyl)acrylamide, N-hydroxyethylacrylamide, N-isopropylacrylamide, N-isopropylmethacrylamide, N-tert-butylacrylamide, N,N'-methylenebisacrylamide, N-(isobutoxymethyl)acrylamide, N-(butoxymethyl)acrylamide, N-[3-(dimethylamino)propyl]methacrylamide, N,N-dimethylacrylamide, N,N-diethylacrylamide, N-(hydroxymethyl)methacrylamide, N-hydroxyethylmethacrylamide, N-isopropylmethacrylamide, N-isopropylmethacrylamide, N-tert-butylmethacrylamide, N,N'-methylenebismethacrylamide, N-(isobutoxymethyl)methacrylamide, N-(butoxymethyl)methacrylamide, N-[3-(dimethylamino)propyl]methacrylamide, N,N-dimethylmethacrylamide, and N,N-diethylmethacrylamide. The (meth)acrylamide monomers may be used alone or in combination.

[0054] Examples of monofunctional acrylamide or methacrylamide components include acryloylmorpholine (ACMO), methacrylmorpholine, N-(hydroxymethyl)acrylamide, N-hydroxyethylacrylamide, N-isopropylacrylamide, N-isopropylmethacrylamide, N-tert-butylacrylamide, N,N'-methylenebisacrylamide, N-(isobutoxymethyl)acrylamide, N-(butoxymethyl)acrylamide, N-[3-(dimethylamino)propyl]methacrylamide, N,N-dimethylacrylamide, N , N-diethylacrylamide, N-(hydroxymethyl)methacrylamide, N-hydroxyethylmethacrylamide, N-isopropylmethacrylamide, N-isopropylmethylmethacrylamide, N-tert-butylmethacrylamide, N,N'-methylenebismethacrylamide, N-(isobutoxymethyl)methacrylamide, N-(butoxymethyl)methacrylamide, N-[3-(dimethylamino)propyl]methylmethacrylamide, N,N-dimethylmethacrylamide and N,N-diethylmethacrylamide.

[0055] Examples of vinyl aromatic compounds having up to 20 carbon atoms may include, for example, styrene and C1-C4-alkyl-substituted styrenes such as vinyltoluene, p-tert-butylstyrene and α-methylstyrene.

[0056] Examples of the vinyl ester of carboxylic acid having up to 20 carbon atoms (eg, 2 to 20 or 8 to 18 carbon atoms) may include vinyl laurate, vinyl stearate, vinyl propionate, and vinyl acetate.

[0057] Examples of the α,β-unsaturated carboxylic acid having 3 to 8 carbon atoms may be acrylic acid or methacrylic acid.

[0058] Examples of vinyl-substituted heterocycles may include monovinyl-substituted heterocycles, wherein the heterocycle is a 5- to 8-membered ring containing 2 to 7 carbon atoms and 1 to 4 (preferably 1 or 2) heteroatoms selected from N, O and S, such as vinylpyridine, N-vinylpyrrolidone, N-vinylmorpholin-2-one, N-vinylcaprolactam and 1-vinylimidazole, vinylalkyloxazolidinone such as vinylmethyloxazolidinone.

[0059] Preferred monomers are (meth)acrylate monomers and (meth)acrylamide monomers. More preferably, these monomers are monofunctional.

[0060] In a preferred embodiment, the photopolymerizable liquid (a) of the present invention comprises both oligomers and monomers containing at least one ethylenically unsaturated functional group. The weight ratio of oligomer to monomer can be in the range of 10:1 to 1:10, preferably 8:1 to 1:8, or 5:1 to 1:5, or 3:1 to 1:5, or 1:1 to 1:4.

[0061] Based on the total weight of the curable composition, the amount of the photopolymerizable liquid (a) can be in the range of 20 to 90 wt.%, for example 25 wt.%, 30 wt.%, 35 wt.%, 40 wt.%, 50 wt.%, 60 wt.%, 70 wt.%, 80 wt.%, 90 wt.%, preferably 25 to 80 wt.%, more preferably 30 to 70 wt.% or 30 to 60 wt.%.

[0062] Spherical inorganic particles (b)

[0063] According to the present invention, the radiation curable composition further comprises at least one 50 Spherical inorganic particles with a size of 50 to 2000 nm.

[0064] Examples of inorganic fillers are silica particles, glass or silica beads, calcium carbonate, barium sulfate, talc, mica, glass or silica bubbles, zirconium silicate, iron oxide, diatomaceous earth, dolomite, powdered metals, titanium oxide, pulp powder, kaolin, modified kaolin, hydrated kaolin metal fillers, ceramics and composite materials.

[0065] In the present invention, spherical inorganic particles are used so that a larger amount of inorganic particles can be added to the composition to achieve good mechanical properties while maintaining good stability and low viscosity. The spherical inorganic particles have a sphericity of 0.7 to 1, preferably 0.8 to 1, more preferably 0.9 to 1.

[0066] In an embodiment, the spherical inorganic particles are silica particles, such as silica, fumed silica, precipitated silica, colloidal silica, vaporized metal combustion (VMC) silica, and mixtures thereof.

[0067] In a preferred embodiment, the silica particles are vaporized metal combustion (VMC) spherical silica particles.The VMC process provides fine spherical silica particles from metal powders by direct oxidation.

[0068] It is preferred that the silica particles are surface treated with a known surface treatment agent such as an organosilicon compound. More preferably, the silica particles are surface treated with a silane coupling agent. Spherical silica particles that can be treated to provide silica particles treated with silane according to the present invention are generally commercially available or can be prepared from various starting materials (e.g., wet process silica) by known methods.

[0069] The silica particles treated with silane can be obtained by reacting silica particles with a silane coupling agent.

[0070] The silane coupling agent has the form R-SiX3, wherein R is an organic functional group, such as amino, methacryloyl, glycidyloxy, mercapto, vinyl, and X is a hydrolyzable group. Preferably, the silane coupling agent is an alkoxysilane having the structure of the following formula:

[0071] R 1 n Si(OR 2 ) 4-n

[0072] Where R 1 Can be selected from C1-C 30 (Preferably C1-C 18 , or C1-C 12 , or C1-C6 or C1-C4) alkyl, amino C1-C 30 (Preferably C1-C 18 , or C1-C 12 , or C1-C6 or C1-C4) alkyl, C2-C 30 (Preferably C2-C 18 , or C2-C 12 , or C2-C6 or C2-C4) alkenyl, amino C2-C 30 (Preferably C2-C 18 , or C2-C 12 , or C2-C6 or C2-C4) alkenyl and methacryloyl C4-C 30 (Preferably C4-C 18 , or C4-C 12 or C4-C8) alkyl, C3-C 10 Cycloalkyl and C6-C 10 Aryl; R 2 Can be selected from C1-C 18 Alkyl (preferably C1-C 15 、C1-C 10 , C1-C8, C1-C6 or C1-C4 alkyl); and n is an integer from 1 to 3.

[0073] In an embodiment, the alkoxysilane is a trialkoxysilane. The trialkoxysilane may have the following structure:

[0074] R 1 Si(OR 2 )3

[0075] Where R 1 Can be selected from C1-C 30 (Preferably C1-C 18 , or C1-C 12 , or C1-C6 or C1-C4) alkyl, amino C1-C 30 (Preferably C1-C18 , or C1-C 12 , or C1-C6 or C1-C4) alkyl, C2-C 30 (Preferably C2-C 18 , or C2-C 12 , or C2-C6 or C2-C4) alkenyl, amino C2-C 30 (Preferably C2-C 18 , or C2-C 12 , or C2-C6 or C2-C4) alkenyl and methacryloyl C4-C 30 (Preferably C4-C 18 , or C4-C 12 or C4-C8) alkyl, and C3-C 10 Cycloalkyl; R 2 Can be selected from C1-C 10 Alkyl (preferably C1-C8 or C1-C6 or C1-C4 alkyl).

[0076] Specific examples of alkoxysilanes may be selected from methyltrimethoxysilane, ethyltrimethoxysilane, propyltrimethoxysilane, butyltrimethoxysilane, pentyltriethoxysilane, hexyltriethoxysilane, heptyltriethoxysilane, octyltriethoxysilane, 3-aminopropyltriethoxysilane, 3-aminobutyltriethoxysilane, methacryloxyethyltrimethoxysilane, methacryloxypropyltrimethoxysilane, and combinations thereof.

[0077] The silica particles treated with silane may have an average particle size D in the range of 50 to 2000 nm. 50 , for example 60nm, 70nm, 80nm, 90nm, 100nm, 120nm, 140nm, 160nm, 180nm, 200nm, 300nm, 400nm, 500nm, 600nm, 700nm, 800nm, 900nm, 1000nm, 1200nm, 1500nm, 1800nm ​​or 2000nm, preferably 100 to 1500nm or 300 to 1000nm.

[0078] In the present invention, it is not necessary to add other types of inorganic particles with different particle size distributions to balance the viscosity and filler content of the radiation curable composition, such as an average particle size D 50 The particles are 1 to 6 μm.

[0079] In the radiation curable composition of the present invention, the amount of spherical inorganic particles can be in the range of 10 to 80 wt.%, for example, 15 wt.%, 20 wt.%, 25 wt.%, 30 wt.%, 35 wt.%, 40 wt.%, 50 wt.%, 60 wt.%, 65 wt.%, 70 wt.%, preferably 30 wt.% to 70 wt.%, or 50 wt.% to 70 wt.%, based on the total weight of the radiation curable composition.

[0080] Photoinitiator (c)

[0081] The radiation curable composition comprises at least one photoinitiator as component (c). For example, the photoinitiator component (c) may include at least one free radical photoinitiator and / or at least one ionic photoinitiator, and preferably at least one (e.g. one or two) free radical photoinitiator. For example, all photoinitiators known in the art for use in compositions for 3D printing may be used, for example, photoinitiators known in the art for use in SLA, DLP or PPJ (photopolymer jetting) methods may be used.

[0082] Exemplary photoinitiators can include benzophenone, acetophenone, chlorinated acetophenone, dialkoxyacetophenone, dialkylhydroxyacetophenone, dialkylhydroxyacetophenone esters, benzoin and derivatives (such as benzoin acetate, benzoin alkyl ether), dimethoxybenzoin, dibenzyl ketone, benzoyl cyclohexanol and other aromatic ketones, α-amino ketone compounds, phenylglyoxylate compounds, oxime esters, acyl oxime esters, acylphosphine oxides, acylphosphonates, keto sulfides, dibenzoyl disulfide, diphenyl dithiocarbonate, mixtures thereof, and mixtures with α-hydroxy ketone compounds or α-alkoxy ketone compounds.

[0083] Examples of suitable acylphosphine oxide compounds have the formula (XII),

[0084]

[0085] in

[0086] R 50 is unsubstituted cyclohexyl, cyclopentyl, phenyl, naphthyl or biphenyl; or is substituted by one or more halogen, C1-C 12 Alkyl, C1-C 12 Alkoxy, C1-C 12 Alkylthio or NR 53 R 54 substituted cyclohexyl, cyclopentyl, phenyl, naphthyl or biphenyl;

[0087] or R 50 is an unsubstituted C1-C 20 Alkyl or substituted with one or more halogen, C1-C12 Alkoxy, C1-C 12 Alkylthio, NR 53 R 54 or -(CO)-O-C1-C 24 Alkyl-substituted C1-C 20 alkyl;

[0088] R 51 is unsubstituted cyclohexyl, cyclopentyl, phenyl, naphthyl or biphenyl; or is substituted by one or more halogen, C1-C 12 Alkyl, C1-C 12 Alkoxy, C1-C 12 Alkylthio or NR 53 R 54 Substituted cyclohexyl, cyclopentyl, phenyl, naphthyl or biphenyl; or R 51 Yes - (CO)R' 52 ; or R 51 is unsubstituted or substituted with one or more halogen, C1-C 12 Alkoxy, C1-C 12 Alkylthio, or NR 53 R 54 Substituted C1-C 12 alkyl;

[0089] R 52 and R' 52 R is independently unsubstituted cyclohexyl, cyclopentyl, phenyl, naphthyl or biphenyl, or cyclohexyl, cyclopentyl, phenyl, naphthyl or biphenyl substituted by one or more halogen, C1-C4 alkyl or C1-C4 alkoxy groups; or 52 is a 5-membered or 6-membered heterocyclic ring containing an S atom or a N atom;

[0090] R 53 and R 54 are independently hydrogen, unsubstituted C1-C 12 Alkyl or C1-C substituted by one or more OH or SH 12 alkyl, wherein the alkyl chain is optionally interrupted by one to four oxygen atoms; or R 53 and R 54 Independently of each other are C2-C 12 cyclopentyl, cyclohexyl, benzyl or phenyl.

[0091] Specific examples of the photoinitiator may include 1-hydroxycyclohexyl phenyl ketone, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one, 2-benzyl-2-N,N-dimethylamino-1-(4-morpholinophenyl)-1-butanone, a combination of 1-hydroxycyclohexyl phenyl ketone and benzophenone, 2,2-dimethoxy-2-phenylacetophenone, bis(2,6-dimethoxybenzoyl-1-(2,4,4-trimethylpentyl)phosphine oxide, 2-(4-( ... -hydroxy-2-methyl-1-phenyl-propan-1-one, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, 2-hydroxy-2-methyl-1-phenyl-1-propane, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, a combination of 2-hydroxy-2-methyl-1-phenyl-propan-1-one, 2,4,6-trimethylbenzoyldiphenylphosphinate and 2,4,6-trimethylbenzoyldiphenylphosphine oxide and also any combination thereof.

[0092] In a particularly preferred embodiment, the photoinitiator (c) is a compound of formula (XII), such as, for example, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide; 2,4,6-trimethylbenzyl-diphenyl-phosphine oxide; ethyl (2,4,6-trimethylbenzoylphenyl)phosphinate; (2,4,6-trimethylbenzoyl)-2,4-dipentyloxyphenylphosphine oxide and bis(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide.

[0093] Based on the total weight of the composition, the amount of photoinitiator (c) can be in the range of 0.1 to 10 wt.%, for example 0.2 wt.%, 0.5 wt.%, 0.8 wt.%, 1 wt.%, 2 wt.%, 3 wt.%, 5 wt.%, 8 wt.%, or 10 wt.%, preferably 0.1 to 5 wt.% or 0.5 to 5 wt.% or 0.5 to 3 wt.%.

[0094] In one embodiment, the radiation curable resin composition comprises

[0095] (a) at least one photopolymerizable liquid;

[0096] (b) at least one average particle size D 50 Spherical inorganic particles with a diameter of 50 to 2000 nm;

[0097] (c) at least one photoinitiator.

[0098] The amount of component (a) can be expressed as 20 to 90 wt.% or 25 to 80 wt.% or 30 to 60 wt.%; the amount of component (b) can be expressed as 10 to 80 wt.% or 30 to 70 wt.% or 50 to 70 wt.%; the amount of component (c) can be expressed as 0.1 to 10 wt.% or 0.5 to 5 wt.% or 0.5 to 3 wt.%.

[0099] Additives

[0100] The composition of the present invention may further comprise one or more adjuvants.

[0101] As auxiliary agents, the following preferred examples may be mentioned: surface-active substances, flame retardants, nucleating agents, lubricant waxes, adhesion promoters, rheology modifiers, dyes, pigments, catalysts, UV absorbers and stabilizers (e.g. against oxidation, hydrolysis, light, heat or discoloration), inorganic and / or organic fillers, reinforcing materials and plasticizers. As hydrolysis inhibitors, oligomeric and / or polymeric aliphatic or aromatic carbodiimides are preferred. In order to stabilize the curing material of the invention against aging and destructive environmental influences, in a preferred embodiment, stabilizers are added to the system.

[0102] If the composition of the invention is exposed to thermo-oxidative damage during use, an antioxidant is added in a preferred embodiment. Phenolic antioxidants are preferred. Phenolic antioxidants such as BASF SE 1010 is given in Plastics Additive Handbook, 5th edition, H. Zweifel, ed., Hanser Publishers, Munich, 2001, pp. 98-107, 116 and 121.

[0103] If the composition of the present invention is exposed to UV light, it is preferably additionally stabilized with a UV absorber. UV absorbers are generally referred to as molecules that absorb high-energy UV light and dissipate the energy. Conventional UV absorbers used in industry belong to the group of, for example, cinnamate, diphenylcyanoacrylate, formamidine, benzylidenemalonate, diarylbutadiene, triazine and benzotriazole. Examples of commercial UV absorbers can be found in Plastics Additive Handbook, 5th edition, H. Zweifel, ed., Hanzel Verlag, Munich, 2001, pp. 116-122.

[0104] More details on the abovementioned additives can be found in the specialist literature, for example in Plastics Additive Handbook, 5th edition, ed. H. Zweifel, Hanzel-Verlag, Munich, 2001.

[0105] According to the present invention, the auxiliary agent may be present in an amount of 0 to 50% by weight, 0.01 to 50% by weight, for example 0.5 to 30% by weight, based on the total weight of the radiation curable composition.

[0106] Preparation of radiation curable compositions

[0107] One aspect of the invention relates to a method of preparing a radiation curable composition of the invention for 3D printing, the method comprising mixing the components of the composition. There is no particular requirement for the order in which the components are added. The inorganic particles may be added together to the photopolymerizable liquid and then the entire composition is mixed, or the inorganic particles may be added after first mixing the photopolymerizable liquid.

[0108] According to an embodiment of the present invention, mixing can be carried out under stirring at room temperature. There is no particular restriction on the mixing time and stirring rate, as long as all components are uniformly mixed together. In a specific embodiment, mixing can be carried out by a speed mixer at 1000 to 3000RPM, preferably 1500 to 2500RPM for 5 to 60min, more preferably 6 to 30min.

[0109] The radiation curable composition has a viscosity at 25°C of less than 2000 mPa.s, preferably less than 1500 mPa.s, more preferably less than 1200 mPa.s.

[0110] The radiation curable composition of the present invention shows excellent stability. When the composition is centrifuged at 25°C, there is only a slight phase separation after 2 hours, preferably after 5 hours, more preferably after 16 hours.

[0111] 3D printed objects and their preparation

[0112] One aspect of the present invention relates to a method of forming a 3D printed object, the method comprising using the radiation curable composition of the present invention.

[0113] In one embodiment of the present invention, a method for forming a 3D printed object comprises the following steps:

[0114] (i) applying light to cure the curable composition layer by layer to form an intermediate 3D object;

[0115] (ii) curing the entire intermediate 3D printed object by radiation to form a cured 3D printed object; and

[0116] (iii) optionally thermally curing the entire solidified 3D printed object to form a final 3D printed object.

[0117] According to the present invention, the curing time in steps (i) and (ii) can be determined by a technician according to actual applications. For example, in step (i) of the method, the curing time for each layer can be 0.5 to 15 seconds, such as 1 to 10 seconds.

[0118] In step (ii) of the method, the curing time for the entire intermediate 3D printed object can be in the range of 10 min to 500 min, for example 20 min, 30 min, 40 min, 60 min, 80 min, 100 min, 120 min, 180 min, 250 min, 300 min, 400 min, preferably 10 min to 250 min.

[0119] There is no particular limitation on the temperature during step (i) or step (ii). Specifically, the temperature can be selected according to the material and 3D printer used.

[0120] Step (iii) of the method for forming a 3D printed object of the present invention can be carried out at a temperature of 60°C to 180°C, preferably 80°C to 150°C, more preferably 100°C to 140°C, such as 1 hour to 48 hours, for example 2 hours, 4 hours, 6 hours, 8 hours, 10 hours, 12 hours, 16 hours, 20 hours, 24 hours, 28 hours, 32 hours, 36 hours, 40 hours, 44 hours, 48 ​​hours, preferably 4 hours to 36 hours, 6 hours to 36 hours, 8 hours to 36 hours, 10 hours to 24 hours, 12 hours to 24 hours, 12 hours to 20 hours, 16 hours to 36 hours, 20 hours to 36 hours, 24 hours to 36 hours, 28 hours to 36 hours. The temperature during step (iii) can be changed as needed. For example, in an embodiment of the present invention, step (iii) of the method of forming a 3D printed object of the present invention can be performed in two stages, wherein the first stage is performed at a temperature of 80°C for one hour and the second stage is performed at a temperature of 130°C for 2 hours.

[0121] The radiation used in steps (i) and (ii) of the method of forming a 3D printed object of the present invention can be adopted by a technician according to the actual 3D printing application. For example, the radiation can be actinic radiation having sufficient energy to initiate a polymerization or crosslinking reaction. Actinic radiation can include, but is not limited to, α-rays, γ-rays, ultraviolet radiation (UV radiation), visible light, and electron beams, wherein UV radiation and electron beams, especially UV radiation, are preferred.

[0122] In a specific embodiment, the wavelength of the radiated light may be in the range of 350 to 480 nm, for example 365 nm, 385 nm, 395 nm, 405 nm, 420 nm, 440 nm, 460 nm, 480 nm.

[0123] Stereolithography (SLA), digital light processing (DLP), photopolymer jetting (PPJ), LCD technology or other technologies known to those skilled in the art can be used in step (i) of the method for forming a 3D printed object of the present invention. Preferably, the production of a cured 3D object of a complex shape is carried out, for example, by digital light processing (DLP) which has been known for many years. In this technology, a desired shaped article is constructed from a radiation curable composition by means of three steps (1), (2) and (3) in a repeated, alternating order. In step (1), the radiation curable composition is filled into the construction area between the carrier and the optically transparent film. In step (2), a layer of the radiation curable composition is cured by means of suitable imaging radiation, preferably imaging radiation from a computer-controlled UV light projector, the imaging radiation corresponding to the desired cross-sectional area of ​​the shaped article to be formed, and in step (3), the cured radiation curable composition and the carrier are removed from the optically transparent film. The sequence of steps (1), (2) and (3) is repeated until the desired 3D shape is completed.

[0124] The present invention further relates to a 3D printed object formed from the curable composition of the present invention or obtained by the method of the present invention.

[0125] Examples of 3D printed objects include functional parts with advanced properties for automotive / mold applications, or demonstration parts that require a ceramic-like feel.

[0126] Examples

[0127] The present invention is further illustrated by the following examples, which are provided for the purpose of illustrating the present invention and are not intended to limit the present invention. Unless otherwise indicated, all parts and percentages are by weight.

[0128] Materials and abbreviations

[0129] Component (a)

[0130] Miramer M370, tris(2-hydroxyethyl)isocyanurate triacrylate, available from Miwon;

[0131] Sartomer SR833S, tricyclodecane dimethanol diacrylate, available from Sartomer Co., Exton, Pennsylvania;

[0132] ACMO, acryloylmorpholine, available from RAHN;

[0133] Component (b)

[0134] TG-C100, spherical silica particles, average particle size D 50115 nm, surface treated with 1,1,1-trimethyl-N-(trimethylsilyl)-(TMS), available from Cabot Corporation;

[0135] TPX-5110, spherical silica particles, average particle size D 50 115 nm, surface treated with methacrylic silane (methacryloxypropyltrimethoxysilane (MPS)), available from Cabot Corporation;

[0136] SC2500-SMJ, spherical silica particles, average particle size D 50 The thickness of the nanoparticles was 500 nm and the surface was treated with methacrylic silane (methacryloxypropyltrimethoxysilane (MPS)), which can be obtained from Admatechs.

[0137] Component (c)

[0138] Omnicure TPO-L, ethyl (2,4,6-trimethylbenzoyl)-phenylphosphonate, available from IGM

[0139] Composition Example 1

[0140] Formlabs Rigid 10K Resin, product code FLRG1001, available from Formlabs

[0141] method

[0142] (1) Viscosity

[0143] The viscosity of the radiation curable composition was determined using a Brookfield AMETEK DV3T rheometer. For each test, approximately 0.65 ml of sample was used and the flow rate was set at 1 s depending on the viscosity. -1 With 30s -1 between the shear rates.

[0144] (2) Tensile test

[0145] The tensile test was performed using a Zwick Z050 tensile tester according to ISO 527-5A:2009, wherein the parameters used included: starting position: 50 mm; preload: 0.02 MPa; test speed: 5 mm / min.

[0146] (3) Heat deflection temperature (HDT)

[0147] Determine heat deflection temperature according to ASTM D648-07

[0148] (4) Stability

[0149] Resin stability was measured using a stability analyzer (LumiFuge, LUM). Liquid samples were loaded into plastic vials and centrifuged at a specified rotation speed, duration, and temperature, during which the particle settling behavior was monitored by measuring the transmittance of a laser beam through the surface area of ​​the liquid sample. And the resin stability can be directly compared by observing the phase separation after the test.

[0150] Example 1-3

[0151] Photopolymerizable liquid composition 1 was prepared by adding all components in the amounts listed in Table 1 to a plastic vial and mixing by a speed mixer at 50° C. at 2000 RPM for 10 minutes to obtain a liquid base composition.

[0152] Table 1

[0153] Composition 1 Serving size (g) M370 30 833S 30 ACMO 40 TPO-L 2

[0154] Examples 1-3 were prepared by mixing Composition 1 and three spherical silica particles at different filler loadings listed in Table 2 into a plastic vial and mixing by a speed mixer at 2000 RPM for 10 minutes to obtain a uniform filler-containing resin. Filler loading means the weight percentage of inorganic particles based on the total weight of the radiation curable composition.

[0155] As shown in Table 2, the viscosities of radiation curable compositions containing different amounts of inorganic particles were tested.

[0156] Table 2

[0157]

[0158]

[0159] For all three silica particles, the viscosity increased significantly with increasing filler loading. However, the radiation curable composition containing SC2500-SMJ silica particles showed the lowest viscosity, allowing the use of higher filler loadings in the composition to improve mechanical properties.

[0160] Examples 4-7, Comparative Example 1

[0161] The compositions of Examples 4-7 are the same, but the preparation methods are different, as shown in Table 3. The composition consists of 35 g of Composition 1 and 65 g of SC2500-SMJ.

[0162] Table 3

[0163]

[0164] For each set of stability tests, 10ml-20ml of liquid sample was loaded into a plastic vial and sealed with a PP stopper. The sample was then centrifuged at 4000RPM for 16 hours at 25°C, during which the particle sedimentation behavior was monitored by measuring the transmittance of the laser beam passing through the sample. Particle sedimentation during centrifugation will reduce the particle content on the surface area, leaving fewer particles to block the laser beam, and in turn leading to an increase in transmittance. After the test, the resin stability was then directly compared by observing the phase separation behavior of the tested samples.

[0165] The phase separation of Examples 4-7 and Comparative Example 1 after 16 hours is shown in Figure 1 middle.

[0166] Examples 8-11

[0167] The curable compositions in Examples 8-11 were prepared by adding silica particles in the amounts listed in Table 4 to a plastic vial and mixing with Composition 1 by a speed mixer at 2000 RPM for 10 minutes to obtain a uniform filler-containing resin.

[0168] The curable compositions of Examples 8-11 were printed using a MiiCraft 150 3D printer, which is a desktop digital light processing (DLP) 3D printer with a wavelength of 405 nm. For a typical printing process, the curable composition was loaded into a cylinder in the printer. The detailed printing parameters are summarized as follows: UV energy was 4.75 mW / cm 2 , base curing time is 10.0s, base layer 1, curing time is 2.0s, buffer layer 5.

[0169] After the 3D printing process, the printed parts were soaked in isopropyl alcohol and shaken for 10 seconds to remove the uncured resin on the surface, followed by drying using compressed air. After UV post-curing for 40 minutes using a NextDent post-curing unit (LC-3DPrint box), parts with a smooth dry surface were obtained. Heat treatment was performed by heating the samples at 120 °C for 2 hours.

[0170] The physical properties of the cured samples obtained by 3D printing from the compositions of Examples 8-11 are also shown in Table 4, from which it can be concluded that Example 11 shows a much higher tensile modulus than the other three while maintaining a low viscosity for 3D printing.

[0171] Table 4

[0172] Components Example 8 Example 9 Example 10 Example 11 Composition 1 (g) 100 70 50 35 TG-C100(g) 0 30 0 0 TPX-5110 0 0 50 0 TPO-L 0.7 0.7 0.7 0.7 SC2500-SMJ 0 0 0 65 total 100.7 100.7 100.7 100.7 Viscosity at 25°C (mPa·s) 86.0 629.0 566.9 1189.1 Tensile modulus (MPa) 2700 5060 5170 10500 Tensile strength(MPa) 57 43 63 90 Elongation at break (%) 3.0 0.9 1.6 1.3

[0173] Example 12

[0174] The curable composition in Example 12 was prepared by adding all components in the amounts shown in Table 5 to a plastic vial and mixing by a speed mixer at 50° C. at 2000 RPM for 10 minutes to obtain a liquid curable composition.

[0175] The curable composition of Example 12 was printed using a MiiCraft 150 3D printer, which is a desktop digital light processing (DLP) 3D printer with a wavelength of 405 nm. For a typical printing process, the curable composition was loaded into a cylinder in the printer. The detailed printing parameters are summarized as follows: UV energy was 4.75 mW / cm 2 , base curing time is 10.0s, base layer 1, curing time is 2.0s, buffer layer 5.

[0176] After the 3D printing process, the printed parts were soaked in isopropyl alcohol and shaken for 12 seconds to remove the uncured resin on the surface, followed by drying using compressed air. After UV post-curing for 40 minutes using a NextDent post-curing unit (LC-3DPrint box), parts with a smooth dry surface were obtained. Heat treatment was performed by heating the samples at 120 °C for 2 hours.

[0177] The physical properties of the cured samples obtained by 3D printing from the composition of Example 12 are shown in Table 5, which show both high stiffness and high HDT.

[0178] Table 5

[0179]

[0180]

[0181] A picture of a 3D printed object obtained by printing the composition of Example 12 according to the standard reference model is shown in Figure 2(b). Comparison between the standard reference model (Figure 2(a)) and Figure 2(b) shows that good printability and high precision can be achieved by the radiation curable composition of the present invention.

[0182] The picture of the 3D printed object obtained by printing the composition of Example 12 is shown in Figure 3 middle.

Claims

1. A radiation-curable resin composition comprising (a) at least one photopolymerizable liquid; (b) at least one average particle size D 50 Spherical inorganic particles with a diameter of 50 to 2000 nm; (c) at least one photoinitiator.

2. The radiation curable composition according to claim 1, wherein The average particle size D of the spherical inorganic particles 50 In the range of 100 to 1500 nm, preferably 300 to 1000 nm.

3. The radiation curable composition according to claim 1 or 2, wherein The spherical inorganic particles are surface-treated with silane, preferably with alkoxysilane.

4. The radiation curable composition according to any one of claims 1 to 3, wherein The spherical inorganic particles are silica particles.

5. The radiation curable composition according to any one of claims 1 to 4, wherein The photopolymerizable liquid contains at least one radiation curable functional group, preferably the radiation curable functional group is selected from the group consisting of ethylenically unsaturated functional groups, epoxy groups or mixtures thereof, more preferably the radiation curable functional group is an ethylenically unsaturated functional group.

6. The radiation curable composition according to claim 5, wherein The photopolymerizable liquid comprises at least one monomer and / or oligomer containing one or more ethylenically unsaturated functional groups.

7. The radiation curable composition according to claim 6, wherein The monomer containing at least one ethylenically unsaturated functional group is monofunctional.

8. The radiation curable composition according to claim 6 or 7, wherein The oligomer containing at least one ethylenically unsaturated functional group is a (meth)acrylate oligomer having 1 to 12, preferably 1 to 10, more preferably 1 to 8 ethylenically unsaturated functional groups.

9. The radiation curable composition according to any one of claims 1 to 8, wherein The amount of the spherical inorganic particles is 10 to 80% by weight, preferably 40 to 70% by weight, based on the total weight of the radiation curable composition.

10. The radiation curable composition according to any one of claims 1 to 9, wherein The amount of the photopolymerizable liquid ranges from 20 to 90% by weight, preferably from 30 to 60% by weight, based on the total weight of the radiation curable composition.

11. The radiation curable composition according to any one of claims 1 to 10, wherein The radiation curable composition has a viscosity at 25°C of less than 1500 mPa.s, preferably less than 1200 mPa.s.

12. The radiation curable composition according to any one of claims 1 to 11, wherein The photoinitiator is a free radical photoinitiator.

13. A method of forming a 3D object, the method comprising: (i) applying light to cure the curable composition according to any one of claims 1 to 12 layer by layer to form an intermediate 3D object; (ii) further applying light to solidify the intermediate 3D object as a whole to form a solidified 3D object; and (iii) optionally treating the solidified 3D object as a whole by heating and / or microwave irradiation to form a final 3D object.

14. The method according to claim 13, wherein: In step (i) stereolithography, photopolymer jetting, digital light processing or LCD technology is used to form the intermediate 3D printed object.

15. The method according to claim 13 or 14, wherein: The radiation is UV radiation.

16. A 3D printed object formed from the composition according to any one of claims 1 to 12 or obtained by the method according to any one of claims 13 to 15.

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