Flame-retardant liquid radiation curable compositions

Abstract

A halogen free liquid radiation curable composition comprising: component a) 10 to 50 weight percent of one or more reactive oligomer(s), said reactive oligomer(s) containing at least two urethane and / or urea linkages in the backbone and two to three ethylenic unsaturated group(s) which can form polymeric crosslink networks in the presence of radicals, anions, nucleophiles or combinations thereof, with a weight average molecular weight (Mw) of greater than 3500 g / mol; component b) 3 to 40 weight percent of one or more reactive monomer(s), said reactive monomer(s) containing two to three ethylenic unsaturated group(s) capable of forming polymeric crosslinked networks in the presence of radicals, anions, nucleophiles or combinations thereof, the said reactive monomer(s) having a glass transition temperature (Tg) of the cured reactive monomer(s) of greater than 40°C; component c) 3 to 40 weight percent of one or more reactive monomer(s), said reactive monomer(s) containing one ethylenic unsaturated group capable of forming polymer crosslinked networks in the presence of radicals, anions, nucleophiles or combinations thereof and at least one of the said reactive monomer(s) contain nitrogen- or phosphorus-group in its backbone; component d) 10 to 40 weight percent of one or more flame-retardant additive(s) selected from the group consisting of phosphate-based flame retardant additives, nitrogen-based flame retardant additives, inorganic flame retardants or combinations thereof. component e) 0.01 to 5 weight percent of one or more photoinitiator(s) capable of producing radicals when irradiated with actinic radiation; component f) 0 to 5 weight percent of one or more additive(s) are selected from the group consisting of filler(s), pigment(s), thermal stabilizer(s) or antioxidant(s), non-reactive diluent or solvent(s), UV light stabilizer(s), UV light absorber(s), radical inhibitor(s), smoke suppression agent(s); with the provision that the composition has a viscosity of 15000 mPa.s at 25°C or less.

Description

[0001] Flame-Retardant Liquid Radiation Curable Compositions

[0002] This invention relates to liquid radiation curable compositions for additive manufacturing processes to obtain flame-retardant three dimensional objects.

[0003] Additive manufacturing (AM) technology through VAT photopolymerization is a layer-by-layer process of solidification of liquid resinous materials by means of radiation curing (e.g. ultraviolet or UV light) to manufacture three-dimensional solid polymeric objects.

[0004] Additive manufacturing (AM) technology has tremendous potential for direct manufacturing of end-use engineering parts. In certain applications, these engineering parts are required to be tough while subjected to heat during its service life and to possess flame retardant behavior.

[0005] Application that require such toughness, heat-resistance and flame retardant properties include: (i) electrical connector, (ii) housings and assembly casing, (iii) automotive and aerospace spare-parts and etc. For the above applications, halogen-free resin formulation are usually demanded in order to comply with environmental and safety regulations.

[0006] Commercially available halogen free flame-retardant resins are often brittle with an elongation at break of less than 4% for 1 K resin.

[0007] When 2K resin systems are used, parts with slightly higher elongation at break of up to 10.0% can be produced, rendering it slightly tougher than the 1 K resin at the expense of having to handle 2 components.

[0008] It is also noticeable when halogen-based flame-retardant resins are employed, parts with significantly much higher elongation at break up to 45% can be obtained but unfortunately at the expense of heat resistance.

[0009] Table 1 below gives an overview of commercially available flame-retardant resins and their properties.

[0010] Table 1: Properties of Commercial flame-retardant SLA / DLP resins and printed parts respectively.

[0011] Commercially available 3D printable, flame retardant radiation curable liquid resins specifically for SLA or DLP printing technology, are not able to achieve good elongation at break.

[0012] Various attempts have been made in the prior art to address this challenges. WO2022192330A1 discloses a 1 K (single-cure) polymerizable liquid formulation based on curable isocyanurate component and a brominated acrylate ester component (i.e. one or more acrylate or methacrylate esters having bromine atoms bonded to aliphatic carbons). The cured article as per WO2022192330A1 passes UL94 VO even down to 0.8mm thickness and HDT of greater than 95°C, however it contains halogens and has poor elongation at break of no more than 7.5%.

[0013] WO2022125668A1 discloses a 1 K (single-cure) polymerizable liquid formulation based on isocyanurate component and an organophosphate component comprising one or more organophosphate compounds. The cured article as per WO2022125668 A1 is halogen-free and passes UL94 VO at 3mm thickness. While 3D printed bodies have moderate to high heat deflection temperature elongation at break is not satisfactory at 5 % or lower.

[0014] W02020055682A1 discloses a 2K (dual-cure) polymerizable liquid formulation based on the a halogenbased flame-retardant group such as bromine and optionally flame retardant synergist (an antimony or aromatic amine synergist). The cured article as per W02020055682A1 passes UL94 VO down to 1.5mm thickness and HDT up to 142°C, however it contains halogen-containing components and has poor elongation at break of between 7-8%.

[0015] US20050209357A1 discloses a 1 K (single-cure) radiation curable composition comprising at least two flame retardants and wherein the flame retardants belong to different classes of compounds (e.g. brominated i.e. halogenated compounds, P-containing compounds and aluminum hydroxide). The cured articles obtained were having moderate heat deflection temperature and low elongation at break of less than 5% after UV and thermal post-curing process.

[0016] The prior art references demonstrate that 3D printed objects can possess excellent UL94 VO flammability results and good thermomechanical properties. However, there are some limitations or challenges with these approaches presented in the prior art. For example, the toughness (elongation at break) and resin composition shelf-life are often sacrificed. In addition to this, some methods resort to the use of halogenbased flame retardant additives which may contradict with various countries local regulations and specific applications requirements.

[0017] Alternative routes towards flame retardant materials that not only has good toughness (higher elongation at break) but also good heat resistance (HDT) and passing the flame retardancy UL 94 VO flammability test at the same time while remaining halogen-free continue to be much needed especially for industrial applications.

[0018] It is therefore an object of this invention to provide halogen free liquid radiation curable compositions suitable for additive manufacturing applications in which the disadvantages of prior art resins are at least reduced and which have flame retardant properties and a sufficient degree of toughness and heat resistance.

[0019] The object of this invention is achieved by a halogen free liquid radiation curable composition comprising: component a) 10 to 50 weight percent of one or more reactive oligomer(s), said reactive oligomer(s) containing at least two urethane and / or urea linkages in the backbone and two to three ethylenic unsaturated group(s) which can form polymeric crosslink networks in the presence of radicals, anions, nucleophiles or combinations thereof, with a weight average molecular weight (M„) of greater than 3500 g / mol; component b) 3 to 40 weight percent of one or more reactive monomer(s), said reactive monomer(s) containing two to three ethylenic unsaturated group(s) capable of forming polymeric crosslinked networks in the presence of radicals, anions, nucleophiles or combinations thereof, the said reactive monomer(s) having a glass transition temperature (Tg) of the cured reactive monomer(s) of greater than 40°C; component c) 3 to 40 weight percent of one or more reactive monomer(s), said reactive monomer(s) containing one ethylenic unsaturated group capable of forming polymer crosslinked networks in the presence of radicals, anions, nucleophiles or combinations thereof and at least one of the said reactive monomer(s) contain nitrogen- or phosphorus-group in its backbone; component d) 10 to 40 weight percent of one or more flame-retardant additive(s) selected from the group consisting of phosphate-based flame retardant additives, nitrogen-based flame retardant additives, inorganic flame retardants or combinations thereof; component e) 0.01 to 5 weight percent of one or more photoinitiator(s) capable of producing radicals when irradiated with actinic radiation; component f) 0 to 5 weight percent of one or more additive(s) selected from the group consisting of filler(s), pigment(s), thermal stabilizer(s) or antioxidant(s), non-reactive diluent or solvents), UV light stabilizer(s), UV light absorber(s), radical inhibitor(s), smoke suppression agents; with the provision that the composition has a viscosity of 15000 mPa.s at 25°C or less and characterized in that the total content of nitrogen and phosphorus contributed by component a), component b), component c), component d), component e) and component f) in claim 1 is defined by the formula:

[0020] [N] + [P] > 7.2 wt% wherein [N] is the total weight percent (wt%) of the element nitrogen and [P] is the total weight percent (wt%) of the element phosphorous in the liquid radiation curable composition.

[0021] The halogen free liquid radiation curable composition according to the invention may optionally contain a smoke suppression agent. Such smoke suppression agents may include molybdenum oxides, ammonium octamolybdate (AOM), calcium and zinc molybdates, iron, copper, manangese, cobalt or vanadyl phthalocyanines, ferrocenes, aluminum hydroxide (ATH) and magnesium hydroxide (MH).

[0022] The sum of components a) to e) and the optional smoke suppression agent equals 100 weight percent.

[0023] The viscosity is measured using a rotational rheometer equipped with cone plate (2°) at 25°C and reading is obtained at 1 Hz shear rate.

[0024] Surprisingly it could be shown that the halogen free liquid radiation curable composition according to the invention yields three dimensional objects with excellent toughness (elongation at break), excellent heat deflection temperature and flame retardancy behavior that passes the V0 criteria for UL94 flammability standards while at the same time has a viscosity that allows easy processing.

[0025] A total [N] and [P] content of greater than 7.2 wt% ensures flame retardant properties that pass UL94 V0 at 3mm thickness.

[0026] More preferably the total [N] and [P] content is equal or higher to 7.3 wt % of the total composition, even more preferably equal or higher than 7.4 wt % and most preferably equal or higher than 7.5 wt %.

[0027] The term “oligomers” is used synonymous with the “pre-polymer” or “polymer” terminology. As used herein oligomer means intermediate of a polymerization reaction that involves two or more components.

[0028] The term “ethylenic unsaturated group” refers to a vinyl, allyl, itaconate or a (meth)acrylate groups.

[0029] Preferably the liquid radiation curable composition according to the invention has a viscosity 8000 mPa.s at 25°C or less.

[0030] The oligomer of component a) can be linear and it may have side chains. The urethane linkages are preferably located in the linear part of the oligomer.

[0031] The weight average molecular weights (Mw) of component a) and component b) are determined by gel permeation chromatography (GPC) measurement using tetrahydrofuran (THF) as eluent with PS / DVB (polystyrene divinylbenzene) column (size: 4.6mm I D. x 15cm, particle size : 3pm) and PS / DVB (polystyrene divinylbenzene) guard column (size: 4.6mm I.D. x 2cm, particle size : 4pm) at a temperature of 40°C and a flow rate of 0.35 mL / min with refractive index detector. The sample concentration is 5 to 6 mg / mL in THF with injection amount of 20 pL. The weight average molecular weights are calculated relative to polystyrene standard.

[0032] The term “(meth)acrylate group” means either a methacrylate group, an acrylate group or a mixture of both groups.

[0033] The reactive oligomer(s) of component a) are preferably a reaction product of hydroxyl-terminated (meth)acrylate(s) with difunctional or trifunctional aliphatic or aromatic isocyanate(s) and polyester polyol(s), polyether polyol(s) and / or polyamine(s) or a reaction product of isocyanate-terminated (meth)acrylate(s) with difunctional or trifunctional polyester polyol(s), polyether polyol(s) and / or polyamine(s).

[0034] More preferably component a) has the chemical structure (1a) below with Ri being a hydrocarbon residue from the reaction of aliphatic or aromatic difunctional isocyanate with polyester polyol or polyether polyol or polyamine, R2 being a hydrocarbon residue formed by the reaction of aliphatic or aromatic difunctional isocyanate with a polyester polyol or a polyether polyol, R3 being a hydrocarbon residue formed by the reaction of aliphatic or aromatic difunctional isocyanate with polyester polyol, polyether polyol or diamine, X being either H or CH3, Y is O, Z being either O or NH, Y being the same or different than Z, n is an integer ranging from 1 to 100 and m is an integer ranging from 0 to 100; R4 is selected from the group consisting of monofunctional (meth)acrylate bearing one hydroxyl functional group such as 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, 4-hydroxybutyl acrylate, 4-hydroxybutyl methacrylate, 2-hydroxybutyl acrylate, 2- hydroxybutyl methacrylate; Rs can be equal to R4 or Rs is selected from the group consisting of difunctional (meth)acrylate bearing one hydroxyl functional group.

[0035] The difunctional (meth)acrylate bearing one hydroxyl functional group may e.g. be glycerol 1 ,3- di(meth)acrylate, 3-(acryloyloxy)-2-hydroxypropyl methacrylate and trimethylolpropane di(meth)acrylate.

[0036] The polyols used to prepare the polyester-polyol are preferably selected from the group consisting of monoethylene glycol, 1 ,2- and 1 ,3-propylene glycol, 1 ,4- and 2,3-butylene glycol, di-p- hydroxyethylbutanediol, 1 ,5-pentanediol, 1 ,6-hexanediol, 1 ,8-octanediol, decanediol, dodecanediol, neopentyl glycol, cyclohexanediol, 3(4),8(9)-bis(hydroxymethyl)tricyclo[5.2.1 .02,6]decane (Dicidol), 1 ,4- bis(hydroxymethyl)cyclohexane, 2,2-bis(4-hydroxycyclohexyl)propane, 2,2-bis[4-(p- hydroxyethoxy)phenyl]propane, 2-methylpropane-1 ,3-diol, 2-methyl-pentane-1 ,5-diol, 2, 2, 4(2, 4,4)- trimethylhexane-1 ,6-diol and also diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, polypropylene glycols, polybutylene glycols, xylylene glycol, and neopentyl glycol hydroxypivalate.

[0037] In another preferred embodiment the urethane linkages in the reactive oligomer(s) of component a) are obtained by reacting polyether polyol, with aliphatic or aromatic diisocyanate to form a hydroxyl-terminated or isocyanate-terminated polyurethane intermediate. The polyether polyols are preferably selected from the group consisting of polyethylene glycol, polypropylene glycol, polypropylene glycol-ethylene glycol copolymer, polytetramethylene glycol, polyhexamethylene glycol, polyheptamethylene glycol and polydecamethylene glycol.

[0038] Preferably the aliphatic and aromatic diisocyanates in Structure (1a) are selected from the group consisting of 5-lsocyanato-1-(isocyanatomethyl)-1 ,3,3-trimethylcyclohexane (isophorone diisocyanate), 1 ,6- diisocyanatohexane, 1 ,3-Bis(2-isocyanatopropan-2-yl)benzene, 2,2,4-trimethylhexane diisocyanate, 2,4,4- trimethylhexane diisocyanate, pentane diisocyanate, 4,4’- methylene bis(cyclohexyl isocyanate), 4-Methyl- 1 ,3-phenylene diisocyanate, 2,2'-methylenebis(phenyl isocyanate), 2,4'-methylenebis(phenyl isocyanate), 4,4'-methylenebis(phenyl isocyanate) and mixtures thereof.

[0039] The polyamines used for obtaining component a) preferably have two primary amine groups at the terminus. Said polyamines according to the invention can be of low(er) molecular weight such as aromatic amine (e.g. diethyl-toluenediamine, dimethylthio-toluenediamine, N,N’-di(sec. butyl)- amino-biphenyl methane) or aliphatic amines (e.g. diethylenetriamine, triethylene tetraamine) which usually act as chain extender. The polyamines used for obtaining component a) can also be of high(er) molecular weight such as amine- terminated ethylene or propylene oxide based polyethers (e.g. Jeffamines®).

[0040] In another preferred embodiment of the invention component a) has the chemical structure (1 b) or (1 c) below: with R? being a hydrocarbon residue from the reaction of aliphatic or aromatic difunctional isocyanate with polyester polyol or polyether polyol Re and monofunctional (meth)acrylate bearing one hydroxyl functional group Rs; Re is selected from the group consisting of polyether polyol or polyester polyol with three hydroxyl functional groups (triol) such as polyethylene glycol trimethylolpropane ether, polypropylene glycol trimethylolpropane ether, glycerine / propylene oxide based polyether triol or glycerine / ethylene oxide based polyether triol; Rs is selected from the group consisting monofunctional (meth)acrylate bearing one hydroxyl functional group such as 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, 4-hydroxybutyl acrylate, 4- hydroxy butyl methacrylate, 2-hydroxybutyl acrylate, 2-hydroxybutyl methacrylate; Rg is selected from the group consisting monofunctional (meth)acrylate bearing one isocyanate functional group such as 2-acryloyloxyethyl isocyanate, 2-methacryloyloxyethyl isocyanate, 2-[2-(methacryloyloxy)ethyloxy]ethyl isocyanate.

[0041] Preferably the aliphatic and aromatic diisocyanates in Structure (1 b) are selected from the group consisting of 5-lsocyanato-1-(isocyanatomethyl)-1 ,3,3-trimethylcyclohexane (isophorone diisocyanate), 1 ,6- diisocyanatohexane, 1 ,3-Bis(2-isocyanatopropan-2-yl)benzene, 2,2,4-trimethylhexane diisocyanate, 2,4,4- trimethylhexane diisocyanate, pentane diisocyanate, 4,4’- methylene bis(cyclohexyl isocyanate), 4-Methyl- 1 ,3-phenylene diisocyanate, 2,2'-methylenebis(phenyl isocyanate), 2,4'-methylenebis(phenyl isocyanate), 4,4'-methylenebis(phenyl isocyanate) and mixtures thereof.

[0042] The reactive monomer(s) of component b) that contain two to three ethylenic unsaturated group(s) and having a glass transition temperature (Tg) of the cured reactive monomer(s) of greater than 40°C are preferably a reaction product of aliphatic or aromatic diisocyanate with hydroxyl-terminated (meth)acrylates.

[0043] More preferably component b) has the following chemical structure (2): with R10 being a hydrocarbon residue from the reaction of aliphatic or aromatic difunctional isocyanate with hydroxyl-terminated compound bearing (meth)acrylate functional group and Rn is the hydroxyl-terminated compound bearing (meth)acrylate functional group selected from the group consisting of 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, 4-hydroxybutyl acrylate, 4-hydroxybutyl methacrylate, 2-hydroxybutyl acrylate and 2-hydroxybutyl methacrylate.

[0044] Alternatively, the reactive monomers of component b) are selected from the group consisting of 1 ,3,5- trially 1-1 , 3, 5-triazinane-2, 4, 6-trione, 2,4,6-triallyloxy-1 ,3,5-triazine, tris(2-hydroxyethyl) isocyanurate triacrylate, tris(2-hydroxyethyl) isocyanurate trimethacrylate, 1 ,3,5-triacryloylhexahydrotriazine, 1 ,3,5- trimethacryloylhexahydrotriazine, tricyclodecane dimethanol diacrylate, tricyclodecane dimethanol dimethacrylate, bisphenol A diacrylate, bisphenol A dimethacrylate, bisphenol A ethoxylate diacrylate, bisphenol A ethoxylate dimethacrylate, bisphenol F ethoxylate diacrylate, bisphenol F ethoxylate dimethacrylate, isosorbide diacrylate, isosorbide dimethacrylate and mixtures thereof.

[0045] More preferably, the reactive monomer(s) of component b) are selected from the group consisting of 1 ,3,5- triallyl-1 ,3, 5-triazinane-2, 4, 6-trione, tris(2-hydroxyethyl) isocyanurate triacrylate, tricyclodecane dimethanol dimethacrylate, bisphenol A dimethacrylate, isosorbide dimethacrylate.

[0046] Component c) comprises one or more reactive monomer(s), said reactive monomer(s) containing one ethylenic unsaturated group capable of forming polymer crosslinked networks in the presence of radicals, anions, nucleophiles or combinations thereof. Such reactive monomer(s) of component c) that contain one ethylenic unsaturated group are preferably selected from the group consisting of 2-hydroxylethyl methacrylate, hydroxypropyl methacrylate, 4-hydroxylbutyl acrylate, 2-hydroxypropyl acrylate, 2- hydroxylethyl acrylate, t-Butyl acrylate, cyclohexyl acrylate, cyclohexyl methacrylate, benzyl acrylate, benzyl methacrylate, phenoxy ethyl acrylate, phenoxy ethyl methacrylate, tetrahydrofurfuryl acrylate, tetrahydrofurfuryl methacrylate, lauryl acrylate, stearyl acrylate, lauryl methacrylate, stearyl methacrylate,

[0047] 3-ethyl-3-oxatanylmethyl acrylate, 3-ethyl-3-oxatanylmethyl methacrylate, (2-ethyl-2-methyl-1 ,3-Dioxolate-

[0048] 4-yl)-methyl acrylate, (2-ethyl-2-methyl-1 ,3-Dioxolate-4-yl)-methyl methacrylate, caprolactone acrylate, caprolactone methacrylate, cyclic trimethylolpropane formal acrylate, cyclic trimethylolpropane formal methacrylate, 4-tert-butylcyclohexyl acrylate, 4-tert-butylcyclohexyl methacrylate, isobornyl acrylate, isobornyl methacrylate, isoborncyclohexyl acrylate, isoborncyclohexyl methacrylate, trimethyl cyclohexyl acrylate, trimethyl cyclohexyl methacrylate, ethoxy ethoxy ethyl acrylate, polyethylene glycol monoacrylate, polypropylene glycol monoacrylate, polyethylene glycol monomethacrylate, polypropylene glycol monomethacrylate, isosorbide monomethacrylate, glycerol carbonate methacrylate, glycerol carbonate acrylate, isopropylideneglycerol methacrylate, glycerol formal methacylate and mixtures thereof.

[0049] More preferably the reactive monomer(s) of component c) that contain one ethylenic unsaturated group are selected from the group consisting of 2-hydroxylethyl methacrylate, isobornyl methacrylate, glycerol formal methacylate and glycerol carbonate methacrylate.

[0050] The invention also requires that at least one of the said reactive monomer(s) of component c) contains nitrogen- or phosphorus-group in its backbone. Preferably the at least one of the said reactive monomer(s) of component c) containing nitrogen- or phosphorus-group in its backbone is selected from the group consisting of 4-acrylolmorpholine, A / ,A / -dimethyl acrylamide, / V, / V-diethy I acrylamide, / V-isopropyl acrylamide, / V, / V-dimethylaminopropyl acrylamide, (N-(2-Hydroxyethyl)acrylamide), diacetone acrylamide, 2-(tert-Butylamino) ethyl methacrylate, dimethylaminoethyl methacrylate, 2- [[(Butylamino)carbonyl]oxy]ethyl acrylate, 2-dimethylaminoethyl methacrylate, 3-dimethylaminopropyl methacrylamide, 2-methacryloyloxyethyl phosphate, trisacryloyloxyethyl phosphate, trismethacryloylxyethyl phosphate and mixtures thereof.

[0051] More preferably the at least one reactive monomer(s) of component c) that contains nitrogen- or phosphorus group in its backbone is 4-acrylolmorpholine and 2-methacryloyloxyethyl phosphate.

[0052] The liquid radiation curable resin composition according to the invention comprise of 10 to 40 weight percent of one or more flame-retardant additive(s) selected from the group consisting of phosphate-based flame retardant additives, nitrogen-based flame retardant additives, inorganic flame retardants or combinations thereof.

[0053] The phosphate-based flame retardant additives can be selected from inorganic phosphorus such as red phosphorus (RP), organophosphates, organophosphonates & metal alkyl-substituted phosphinates such aluminum diethyl phosphinate, aluminum methylethyl phosphinate, aluminum dimethyl phosphinate, ammonium polyphosphate, bisphenol A bis(diphenylphosphate), triphenyl phosphate or TPP, resorcinol bis(diphenyl phosphate) or RDP, bisphenol A diphenyl phosphate or BADP, tricresyl phosphate or TCP, dimethyl methyl phosphonate or DMMP, phosphoric acid, mixed esters with [1 , 1 -bipheny l]-4,4-diol and phenol, oligomer phosphate ester, phytic acid and mixtures thereof.

[0054] The nitrogen-based flame retardant additives can be selected from materials that contain nitrogen and work by releasing ammonia or other nitrogen-containing gases when exposed to heat, such as melamine cyanurate (MC).

[0055] The inorganic flame retardants can be selected from metallic hydroxide such as aluminum trihydroxide (ATH), magnesium hydroxide (MH) as well as boron compounds.

[0056] In some embodiment, intumescent flame retardants that can expand and form a thick and protective layer of char when exposed to heat can be used. Some examples include hydrated sodium silicate or intercalated graphite.

[0057] In other embodiment, hybrid flame retardants which are combination of two or more types and work together to provide the flame retardancy can be included. Relevant example includes phosphorus and nitrogencontaining materials such as melamine polyphosphate (MPP) and ammonium polyphosphate (APP), ammonium phosphate, ammonium dihydrogen phosphate, diammonium hydrogen phosphate and mixture thereof.

[0058] Component d) is preferably selected from the group consisting of organophosphate, organophosphinate or organophosphonate group consisting of resorcinol bis(diphenylphosphate), aluminum diethyl phosphinate, aluminum methylethyl phosphinate, aluminum dimethyl phosphinate, and oligomeric phosphate ester.

[0059] Component e) of the liquid radiation curable composition is a photoinitiator or a mixture of photoinitiators capable of producing radicals when irradiated with actinic radiation. The amount of photoinitiator added to the liquid radiation curable composition according to the invention ranges from 0.01% to 5% weight of the total liquid formulation. Preferably the actinic radiation source irradiating the said photoinitiator(s) is a mercury lamp or a LED source that has an emission wavelength between 230 nm to 600 nm, more preferably 300nm to 460nm.

[0060] Preferably component e) is a free radical photoinitiator, more preferably the free radical photoinitiator is an aromatic ketone type photoinitiator or a phosphine oxide type photoinitiator.

[0061] Aromatic ketone type photo initiators are preferably selected from the group consisting of 1- hydroxycyclohexyl phenyl ketone, 2-hydroxy-l-(4-(4-(2-hydroxy-2- methylpropionyl) benzyl)phenyl-2- methylpropan- 1 -one, 2-hydroxy-2-methyl- 1 - phenylpropanone, 2-hydroxy-2-methyl-l-(4- isopropylphenyl)propanone, oligo (2- hydroxy -2 -methyl- 1 -(4-(l -methylvinyl)phenyl)propanone, 2- hydroxy-2-methyl- 1 -(4- dodecylphenyl)propanone, 2-hydroxy-2-methyl-l-[(2- hydroxyethoxy)phenyl]propanone, benzophenone, substituted benzophenones, 2,2 -Dimethoxy-1 ,2- diphenylethanone or mixtures thereof.

[0062] Phosphine type photoinitiators are preferably selected from the group consisting of diphenyl(2,4,6- trimethylbenzoyl) phosphine oxide (TPO), phenylbis(2,4,6-trimethylbenzoyl) phosphine oxide (BAPO), 2,4,6-trimethylbenzoyl bis (p-tolyl) phosphine oxide (TMO) or Ethyl phenyl(2,4,6- trimethylbenzoyl)phosphinate (TPO-L) or mixtures thereof.

[0063] The liquid radiation curable resin composition according to the invention may preferably comprise 0.1 to 5 weight percent of one or more additive(s) as component f).

[0064] Component f) is selected from the group consisting of filler(s), pigment(s), dispersant(s), defoamer(s), antioxidant(s), UV light stabilizer(s), UV light absorber(s), radical inhibitor(s), smoke suppression agent(s), non-reactive diluent or solvent(s).

[0065] Filler(s) may be inorganic or organic particles or mixtures of both. Preferably filler(s) are nano-sized to micron-sized inorganic particles selected from the group consisting of silica, alumina, zirconia, titania or mixtures thereof. In case the filler(s) include organic particles, such nano-sized to micron-sized organic particles are selected from the group consisting of poly(methyl methacrylate), poly(vinyl alcohol), poly(vinyl butyrate), polyamide, polyimide or mixtures thereof. Pigment(s) may include carbon black and organic dye or colorants which are able to provide color to otherwise clear or blank liquid mixture.

[0066] Dispersant(s) or dispersing agent is used to improve the stabilization of fillers and pigments in the liquid mixture. The dispersant(s) are preferably selected from the group consisting of but not limited to Tego Dispers 685, Tego Dispers 650, Tego Dispers 652, Tego Dispers 655, Tego Dispers 656, Tego Dispers 689, Tego Dispers 673, Tego Dispers 1010, Tego Dispers 670, Tego Dispers 688, Tego Dispers 676, Tego Dispers 690, Tego Variplus LK, BYK-220S, BYK-9076, BYK-9077, BYKJET-9150, BYKJET-9151 , DISPERBYK-101 N, DISPERBYK-163, DISPERBYK-163 TF, DISPERBYK-164, DISPERBYK-2001 , DISPERBYK-21 17, DISPERBYK-2118, DISPERBYK-2155, DISPERBYK-2155 TF, DISPERBYK-2200, Efka PX 4310, Efka PX 4320, Efka PX 4731 , Efka PX 4732, Efka PX 4733, Efka PX 4787.

[0067] Defoamer(s) or an anti-foaming agent can be added to reduce and hinder the formation of foam in process liquids. Some example of defoamers may be mentioned, for example Tego Airex 920 and Tego Airex 921 . In some embodiments, anti-oxidants can be added to provide long-term thermal stabilization, preventing oxidation of the three-dimensional printed object. Anti-oxidants are preferably selected from the group consisting of phenolic antioxidants, phosphite antioxidants, thioester antioxidants, aminic antioxidants or mixtures thereof. Some of the anti-oxidants may be mentioned, for example 1 ,3,5-Trimethyl-2,4,6-tris(3,5- di-tert-butyl-4-hydroxybenzyl)benzene, Calcium bisfethyl 3,5-di-tert-butyl-4-hydroxybenzylphosphonate), 1 ,3,5-Tris(3,5-di-tert-butyl-4-hydroxybenzyl)-1 , 3, 5-triazinane-2, 4, 6-trione, Bis[4-(2-phenyl-2- propyl)phenyl]amine, 2-(1 -(2-Hydroxy-3,5-di-tert-pentyl-phenyl)ethyl)-4,6-di-tert-pentylphenyl acrylate, 4- ((4,6-Bis(octy lthio)-1 ,3,5-triazin-2-yl)amino)-2,6-di-tert-butylphenol or mixtures thereof.

[0068] UV light absorbers are preferably selected from the group consisting of Ethyl 4- [[(methylphenylamino)methylene]amino], 2-(2-hydroxyphenyl)-benzotriazole, 2-(4,6-Bis-(2,4- dimethylphenyl)-1 ,3,5-triazin-2-yl)-5-(octyloxy)-phenol, 2-(4,6-diphenyl-1 ,3,5-triazin-2-yl)-5-[(hexyl)oxy]- phenol, 2-(2H-benzotriazol-2-yl)-4,6-bis(1-methyl-1-phenylethyl)phenol, 2,2-Bis(((2-cyano-3,3- diphenylacryloyl)oxy)methyl)propane-1 ,3-diyl bis(2-cyano-3,3-diphenylacrylate), ethyl 2-cyano-3,3- diphenylacrylate, 2-ethylhexyl 2-cyano-3,3-diphenylacrylate, 2-(3-tert-butyl-2-hydroxy-5-methylphenyl)-5- chlorobenzotriazole, 2-(2H-Benzotriazol-2-yl)-4-(1 ,1 ,3,3-tetramethylbutyl)phenol, 2,2 ' -Methylenebis[6- (2H-benzotriazol-2-yl)-4-(1 ,1 ,3,3-tetramethylbutyl)phenol], 2,2 ’ -(1 ,4-Phenylene)bis[4H-3,1-Benzoxazin- 4-one] 2-[4-(4-oxo-4H-3,1-benzoxazin-2-yl)phenyl]-4H-3,1-benzoxazin-4-one, 2-(2H-Benzothiazol-2-yl)-6- dodecyl-4-methylphenol, branched and linear, 2-Hydroxy-4-n-octyloxybenzophenone, 2-hydroxy-4- methoxybenzophenone, 2-(2H-Benzotriazol-2-yl)-6-(1-methyl-1-phenylethyl)-4-(1 ,1 ,3,3- tetramethylbutyljphenol, 2-(2H-benzotriazol-2-yl)-p-cresol, 2-isopropylthioxanthone, 1 -phenylazo-2- naphtol as well as optical brightener such as 2,5-bis- (5-tert-butyl-2-benzoxazolyl) thiophene, 4,4'-bis(2- methoxystyryl)-1 ,1 '-biphenyl, or mixtures thereof.

[0069] In some embodiments, the UV light stabilizer is selected from the group consisting of 1 ,5,8,12-Tetrakis[4,6- bis(N-butyl-N-1 ,2,2,6,6-pentamethyl-4-piperidylamino)-1 ,3,5-triazin-2-yl]-1 ,5,8,12-tetraazadodecane, 4- Hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl, Bis(1 -octyloxy-2,2,6,6-tetramethyl-4-piperidyl) sebacate, 2,2,6,6-Tetramethyl-4- piperidinol; reaction mass of Bis(1 ,2,2,6, 6-pentamethyl-4-piperidyl) sebacate and Methyl 1 ,2,2,6, 6-pentamethyl-4-piperidyl sebacate, 1-methyl 1 ,2,2,6, 6-pentamethylpiperidin-4-yl decanedioate bis(1 ,2,2,6,6-pentamethylpiperidin-4-yl) decanedioate, Poly[N,N'-bis(2,2,6,6-tetramethyl-4- piperidiny l)-1 ,6-hexanediamine-co-2,4-dichloro-6-morpholino-1 ,3,5-triazine], 1 ,6-hexanediylbis[N-(2, 2,6,6- tetramethyl-4-piperidinyl), bis(2,2,6,6,-tetramethyl-4-piperidyl)sebacate; bis (2,2,6,6-tetramethyl-1- (octyloxy)-4-piperidinyl) ester; bis (1 ,2,2,6, 6-pentamethyl-4-piperidinyl)-[[3,5-bis(1 ,1-dimethylethyl)-4- hydroxyphenyl]methyl] butylmalonate or mixtures thereof.

[0070] A polymerization or radical inhibitor as well as stabilizing agent can be added to provide additional thermal stability. Suitable radical inhibitors are but not limited to methoxyhydroquinone (MEHQ) or various aryl compounds like butylated hydroxytoluene (BHT). The liquid radiation curable composition of the invention is advantageously used in an additive manufacturing process that comprises the repeated steps of deposition or layering and irradiating the composition to form a three-dimensional object.

[0071] Preferably such use comprises the additional post-processing steps of cleaning, washing, sonication, additional dosage of radiation, UV treatment, curing, thermal-heating, polishing, coating or combinations thereof.

[0072] The invention also encompasses a three-dimensional object formed by an additive manufacturing process using the liquid radiation curable composition according to the invention with the following properties: an elongation at break of 10% to 150% determined according to ASTM D638 and a heat deflection temperature (HDT) at 0.455 MPa of 50°C to 150°C determined according to ASTM D648.

[0073] Preferably the three dimensional object exhibits an elongation at break of 15% to 150%, more preferably 20% to 150% determined according to ASTM D638.

[0074] In UL94 Vertical Burn Test, the liquid radiation curable composition is commonly printed to a test specimen having a size of 125 mm in length, 13 mm in width and 3.2 mm or lower in thickness and the properties are determined after UV and thermal post-curing processing. Each test specimen is clamped in a vertical position. After 10 seconds the flame is removed, the time that the specimen continues to burn for is recorded. Once the flame is extinguished the burner is applied for another 10 seconds and the process is repeated. Table i below shows the test criteria for UL94 Vertical Burn Test. When the test specimen is ignited, the flame extinguishes within 10 seconds with no dripping or ignition of cotton balls, and passes the UL94 V0 flammability standards.

[0075] Table i: Test criteria for achieving UL94 V0,V1 and V2 designation

[0076] Therefore, the three dimensional object formed by an additive manufacturing process using the liquid radiation curable composition according to the invention passes the flame retardancy UL 94 V0 flammability standards.

[0077] The three-dimensional object according to the invention, characterized in that the elongation at break of the three-dimensional object measured according to ASTM D638 in XY direction and in Z direction differs not more than 20% from each other. Examples

[0078] The subject matter of the present invention is illustrated in more detail in the following examples, without any intention that the subject matter of the present invention to be restricted to these following examples.

[0079] The liquid radiation curable resin composition is prepared by mixing the ingredients as mentioned in the Table A and Table B below in a mixing equipment or apparatus.

[0080] Table A. Example of component a), its corresponding functionality, Mw, Tgand [N] content

[0081] Table B. Example of component b), its corresponding functionality and [N] content

[0082] Table C. Example of component c), its corresponding functionality, [N] and / or [P] content

[0083] Table D. Example of component d), its corresponding state and [P] content The photoinitiator E1 cited in the supporting examples and comparative examples are Diphenyl(2,4,6- trimethylbenzoyljphosphine oxide (herein abbreviated as TPO).

[0084] The weight average molecular weight of component a) was determined by gel permeation chromatography (GPC) measurement (TOSOH). The GPC was performed in tetrahydrofuran (THF) as eluent with PS / DVB (polystyrene divinylbenzene) column (size: 4.6mm I D. x 15cm, particle size : 3pm) and PS / DVB (polystyrene divinylbenzene) guard column (size: 4.6mm I.D. x 2cm, particle size : 4pm) at a temperature of 40°C and a flow rate of 0.35 mL / min with refractive index detector. The sample concentration is 5 to 6 mg / mL in THF with injection amount of 20 pL. The weight average molecular weights of component a) were calculated relative to polystyrene standard. The viscosity of the final liquid radiation curable composition is measured using rotational rheometer equipped with cone plate (2°) and reading is obtained at 1 Hz shear rate. Unless otherwise indicated viscosity is measured at a temperature of 25°C.

[0085] The thus prepared resin composition is used to generate printed specimens through DLP 3D printing process at layer height thickness setting of 100 pm and an actinic irradiation between 30 and 80 mJ / cm2.per 100 pm layer thickness.

[0086] Elongation at break of the printed, washed and UV post-cured specimen was determined according to ASTM D638, izod impact strength (notched) of the printed, washed and UV post-cured specimen was determined according to ASTM D256 and heat deflection temperature (HDT) of the printed, washed and UV post-cured specimen is measured at an applied stress of 0.45 MPa (66 psi) according to ASTM D648 Method B.

[0087] Example 1

[0088] Example 1 encompasses liquid radiation curable composition 1A, 1 B, 1C, 1 D, 1 E, 1 F. Table 1 : Liquid radiation curable compositions 1A, 1 B, 1 C, 1 D, 1 E, 1 F as well as the thermomechanical and flammability properties of the printed specimen.

[0089] The viscosity of composition 1 A, 1 B, 1 C, 1 D, 1 E, 1 F are all within the required range of less than 15000 mPa.s at 25°C.

[0090] All liquid radiation curable compositions in the main examples also contain [N] + [P] content of more than or equal to 7.2 wt% of the total formulation weight.

[0091] The printed specimens of composition 1A, 1 B, 1C, 1 D, 1 E, 1 F are in the required range of heat deflection temperature of between 50°C to 150°C in accordance to ASTM D648 test method and all specimen reaches the required elongation at break of 10% to 150% in accordance to ASTM D638 test method.

[0092] Printed specimens of curable compositions 1A, 1 B, 1 C, 1 D, 1 E, 1 F according to the invention show flammability UL 94 V0 burn-test passing at 3.0mm sample thickness.

[0093] Example 2

[0094] Example 2 encompasses liquid radiation curable composition 2A, 2B, 2C, 2D, 2E and 2F.

[0095] Table 2: Liquid radiation curable compositions 2A, 2B, 2C, 2D, 2E and 2F as well as the thermomechanical and flammability properties of the printed specimen. The viscosity of composition 2A, 2B, 2C, 2D, 2E and 2F are within the required range of less than 8000 mPa.s at 25°C. However, all liquid radiation curable compositions in Example 2 contain [N] + [P] content of less than 7.2 wt% of total formulation weight.

[0096] The printed specimens of composition 2A, 2B, 2C, 2D, 2E and 2F are in the required range of heat deflection temperature of between 50°C to 150°C in accordance to ASTM D648 test method and all specimen reaches the required elongation at break of 10% to 150% in accordance to ASTM D638 test method.

[0097] Printed specimens of curable composition 2A, 2B, 2C, 2D, 2E and 2F according to the invention show flammability UL 94 V0 burn-test not passing at 3.0mm sample thickness.

[0098] Comparative examples 2A, 2B, 2C, 2D, 2E and 2Fshowed the criticality of having [N] + [P] content of more than or equal to 7.2 wt% of total formulation weight and it is therefore out of the inventive range.

[0099] Example 3

[0100] For example 3, liquid radiation curable composition 1 F according to the invention was used which was printed in XY direction (parallel to the printer platform direction) and another specimen was printed in Z direction (perpendicular to the printer platform direction).

[0101] Table 3: Properties of printed specimens printed in XY and in Z direction.

[0102] Printed specimens of composition 1 F printed in XY direction and printed in Z direction are in the required range of elongation at break of 10% to 150% and heat deflection temperature of of 50°C to 150°C. Neither elongation at break nor tensile toughness or heat deflection temperature differ more than 20% between printing in XY direction and printing in Z direction. There is also no difference in the flammability UL 94 V0 (3.0mm) properties between printing in XY direction and printing in Z direction.

Claims

Claims:1 . A halogen free liquid radiation curable composition comprising: component a) 10 to 50 weight percent of one or more reactive oligomer(s), said reactive oligomer(s) containing at least two urethane and / or urea linkages in the backbone and two to three ethylenic unsaturated group(s) which can form polymeric crosslink networks in the presence of radicals, anions, nucleophiles or combinations thereof, with a weight average molecular weight (M„) of greater than 3500 g / mol; component b) 3 to 40 weight percent of one or more reactive monomer(s), said reactive monomer(s) containing two to three ethylenic unsaturated group(s) capable of forming polymeric crosslinked networks in the presence of radicals, anions, nucleophiles or combinations thereof, the said reactive monomer(s) having a glass transition temperature (Tg) of the cured reactive monomer(s) of greater than 40°C; component c) 3 to 40 weight percent of one or more reactive monomer(s), said reactive monomer(s) containing one ethylenic unsaturated group capable of forming polymer crosslinked networks in the presence of radicals, anions, nucleophiles or combinations thereof and at least one of the said reactive monomer(s) contain nitrogen- or phosphorus-group in its backbone; component d) 10 to 40 weight percent of one or more flame-retardant additive(s) selected from the group consisting of phosphate-based flame retardant additives, nitrogen-based flame retardant additives, inorganic flame retardants or combinations thereof. component e) 0.01 to 5 weight percent of one or more photoinitiator(s) capable of producing radicals when irradiated with actinic radiation; component f) 0 to 5 weight percent of one or more additive(s) selected from the group consisting of filler(s), pigment(s), thermal stabilizer(s) or antioxidant(s), non-reactive diluent or solvent(s), UV light stabilizer(s), UV light absorber(s), radical inhibitor(s), smoke suppression agent(s); with the provision that the composition has a viscosity of 15000 mPa.s at 25°C or less and characterized in that the total content of nitrogen and phosphorus contributed by component a), component b), component c), component d), component e) and component f) in claim 1 is defined by the formula:[N] + [P] > 7.2 wt% wherein [N] is the total weight percent (wt%) of the element nitrogen and [P] is the total weight percent (wt%) of the element phosphorous in the liquid radiation curable composition.

2. The liquid radiation curable composition according to claim 1 , characterized in that the viscosity of the composition is less than 8000 mPa.s at 25°C.

3. The liquid radiation curable composition according to claim 1 or 2, characterized in that the reactive oligomer(s) of component a) is a reaction product of hydroxyl-terminated (meth)acrylate(s) with difunctional or trifunctional aliphatic or aromatic isocyanate(s) and polyester polyol(s), polyether polyol(s) and / or polyamine(s) or a reaction product of isocyanate-terminated (meth)acrylate(s) with difunctional or trifunctional polyester polyol(s), polyether polyol(s) and / or polyamine(s).

4. The liquid radiation curable composition according to any one of claim 1 to 3, characterized in that component a) has the chemical structure (1a)with Ri being a hydrocarbon residue from the reaction of aliphatic or aromatic difunctional isocyanate with polyester polyol or polyether polyol or polyamine, R2 being a hydrocarbon residue formed by the reaction of aliphatic or aromatic difunctional isocyanate with a polyester polyol or a polyether polyol, R3 being a hydrocarbon residue formed by the reaction of aliphatic or aromatic difunctional isocyanate with polyester polyol, polyether polyol or diamine, X being either H or CH3, Y is O, Z being either O or NH, Y being be the same or different than Z, n is an integer ranging from 1 to 100 and m is an integer ranging from 0 to 100; R4 is selected from the group consisting of monofunctional (meth)acrylate bearing one hydroxyl functional group such as 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, 4- hydroxybutyl acrylate, 4-hydroxybutyl methacrylate, 2-hydroxybutyl acrylate, 2-hydroxybutyl methacrylate; R5 can be equal to R4 or Rs is selected from the group consisting of difunctional (meth)acrylate bearing one hydroxyl functional group.

5. The liquid radiation curable composition according to any one of claims 1 to 3, characterized in that component a) has the chemical structure (1 b) or chemical structure (1 c)with R7 being a hydrocarbon residue from the reaction of aliphatic or aromatic difunctional isocyanate with polyester polyol or polyether polyol Re and monofunctional (meth)acrylate bearing one hydroxyl functional group Re; Re is selected from the group consisting of polyether polyol or polyester polyol with three hydroxyl functional groups (triol) such as polyethylene glycoltrimethylolpropane ether, polypropylene glycol trimethylolpropane ether, glycerine / propylene oxide based polyether triol or glycerine / ethy lene oxide based polyether triol; Rs is selected from the group consisting monofunctional (meth)acrylate bearing one hydroxyl functional group such as 2- hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, 4-hydroxybutyl acrylate, 4-hydroxybutyl methacrylate, 2-hydroxybutyl acrylate, 2- hydroxybutyl methacrylate; Rg is selected from the group consisting monofunctional (meth)acrylate bearing one isocyanate functional group such as 2-acryloyloxyethyl isocyanate, 2- methacryloyloxyethyl isocyanate, 2-[2-(methacryloyloxy)ethyloxy]ethyl isocyanate.

6. The liquid radiation curable composition according to claim 1 , characterized in that the reactive monomer(s) of component b) that contains two to three ethylenic unsaturated group(s) and having a glass transition temperature (Tg) of the cured reactive monomer(s) of greater than 40°C are a reaction product of aliphatic or aromatic diisocyanate with hydroxyl-terminated (meth)acrylates.

7. The liquid radiation curable composition according to claim 1 , characterized in that the reactive monomer(s) of component b) has the chemical structure (2),with Rio being a hydrocarbon residue from the reaction of aliphatic or aromatic difunctional isocyanate with hydroxyl-terminated compound bearing (meth)acrylate functional group and Rn is the hydroxyl-terminated compound bearing (meth)acrylate functional group selected from the group consisting of 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, 4-hydroxybutyl acrylate, 4-hydroxybutyl methacrylate, 2-hydroxybutyl acrylate and 2-hydroxybutyl methacrylate.

8. The liquid radiation curable composition according to claim 1 , characterized in that the reactive monomer(s) of component b) containing two to three ethylenic unsaturated group(s) are selected from the group consisting of 1 ,3,5-trially 1-1 , 3, 5-triazinane-2, 4, 6-trione, tris(2-hydroxyethyl) isocyanurate triacrylate, tricyclodecane dimethanol dimethacrylate, bisphenol A dimethacrylate, isosorbide dimethacrylate.

9. The liquid radiation curable composition according to claim 1 , characterized in that the reactive monomer(s) of component c) that contains one ethylenic unsaturated group are selected from the group consisting of 2-hydroxylethyl methacrylate, isobornyl methacrylate, glycerol formal methacylate and glycerol carbonate methacrylate.

10. The liquid radiation curable composition according to claim 1 , characterized in that the reactive monomer(s) of component c) that contains nitrogen- or phosphorus group in its backbone is 4- acrylolmorpholine and 2-methacryloyloxyethyl phosphate.

11. The liquid radiation curable composition according to claim 1 , characterized in that component d) is selected from the group consisting of organophosphate, organophosphinate or organophosphonate group consisting of resorcinol bis(diphenylphosphate), aluminum diethyl phosphinate, aluminum methylethyl phosphinate, aluminum dimethyl phosphinate, and oligomeric phosphate ester.

12. Use of the liquid radiation curable composition according to any one of claims 1 to 11 in an additive manufacturing process that comprises the repeated steps of deposition or layering and irradiating the composition to form a three-dimensional object.

13. Use of the liquid radiation curable composition according to claim 12, characterized in that the additive manufacturing process comprises the additional post-processing steps of cleaning, washing, sonication, additional dosage of radiation, UV treatment, curing, thermal-heating, polishing, coating or combinations thereof.

14. The three-dimensional object formed by an additive manufacturing process using a liquid radiation curable composition according to any one of claims 1 to 13, characterized in that the three- dimensional object has: an elongation at break of 10% to 150% according to ASTM D638, a heat deflection temperature (HDT) at 0.455 MPa of 50°C to 150°C according to ASTM D648.

15. The three-dimensional object according to claim 14, characterized in that the three-dimensional object passes the flame retardancy UL 94 VO flammability standards.

16. The three-dimensional object according to claim 14 or 15, characterized in that the elongation at break of the three-dimensional object measured according to ASTM D638 in XY direction and in Z direction differs not more than 20% from each other.