Composition for printing a three-dimensional object

Abstract

The invention concerns a printable composition comprising: i) at least 18 wt.% photo polymerization reactive compound (M) provided by a secondary acryl amide of the structure type H2C=CH-CO-NH-R1, with R1 represented by an organic residue, ii) photo polymerization reactive organic compound (N) which is different from (M) with the proviso that: all species of the reactive organic compound (N) have a viscosity of maximum 50 mPa s at 25 °C (measured according to DIN EN ISO 3219-2, August 2021, with the proviso that: use of rotational rheometer in cone-plate geometry: cone diameter 60 mm, zero-gap distance 0.061 mm, cone angle 0.5 °; use of active thermal cover and heat plate; use of shear-rate of 600 s-1; general temperature measurement range 25-70 °C) and iii) radical photo initiator (R), where the wt.% ratio of contained (N) to contained (M) is at least 1.3 and the wt.% is relative to the total weight of the composition.

Description

[0001] COMPOSITION FOR PRINTING A THREE-DIMENSIONAL OBJECT

[0002] The present invention relates to printable composition, the use of the printable composition and a three-dimensional object.

[0003] Three dimensional (3D) printing or additive manufacturing is a process in which a 3D digital model is manufactured by the addition of construction material. The 3D printed object is created by utilizing the computer-aided design (CAD) data of an object through sequential construction of two dimensional (2D) layers that correspond to cross-sections of 3D objects. These layers were printed over one another with the proviso that each layer is rapidly cured (e. g. by UV curing) before the next layer is printed accordingly.

[0004] One way to perform said 3D printing is inkjet printing: In inkjet printing, tiny drops of ink (having a limited viscosity) are projected directly onto a receiver surface without physical contact between the printing device and the ink-receiver. The printing device stores the printing data electronically and controls a mechanism for ejecting the drops image-wise. Printing is accomplished by moving a print head across the ink-receiver or vice versa or both.

[0005] Other options of 3D-printing concern resin printing technologies like stereolithography, digital light processing and liquid crystal display vat polymerizations in either top-down or bottom-up approaches.

[0006] Three-dimensional printing technologies are relatively speedy and flexible printing methods for the production of prototype parts, tooling and rapid manufacturing of three-dimensional complex structures directly from a CAD file. Radiation curable compositions for use in three-dimensional printing methods of complex structures are e. g. described in WO 2004 / 096514.

[0007] Challenges encountered with said 3D printing are on the one hand poor mechanical properties such as low heat deflection temperature (HDT), high curing (polymerization) shrinkage, brittleness, low rigidity and material ageing. On the other hand the processability of the printed composition (ink or resin) is a relevant factor. The printed composition needs to have a sufficient low viscosity (especially in case of inkjet-printing) and thus also a corresponding high (polymerization) stability. However, a sufficient (photopolymerization) curing is needed after its application in order to provide mechanical properties and to avoid the generation of uncured resin (result: “bleeding” of non-reacted reactive chemicals).

[0008] Thus, an appropriate “printing composition” (typically provided as an ink or as a (liquid) resin) has to combine (to fulfill) at the same time the following conditions: having a sufficient low viscosity (preferably enabling the printing of tiny drops: especially important in case of inkjet-printing), providing a high viscosity stability (e.g. should not polymerize in the printing apparatus prior the printing) and being (radiation) curable to achieve the desired mechanical properties.

[0009] Thus, it is an object to the present invention to provide a printable composition of high quality which fulfills the requirements discussed above.

[0010] The solution to this object is a printable composition comprising: i) at least 18 wt.% photo polymerization reactive compound (M) provided by a secondary acryl amide of the structure type H2C=CH-CO-NH-R1 , with R1 represented by an organic residue, where at least 50 wt.% of the contained (M) comprises an organic residue R1 which contains an aromatic group, ii) photo polymerization reactive organic compound (N) which is different from (M) with the proviso that: all species of the reactive organic compound (N) have a viscosity of maximum 50 mPa s at 25 °C (measured according to DIN EN ISO 3219-2, August 2021, with the proviso that: use of rotational rheometer in cone-plate geometry: cone diameter 60 mm, zero-gap distance 0.061 mm, cone angle 0.5 °; use of active thermal cover and heat plate; use of shear-rate of 600 s-1; general temperature measurement range 25-70 °C) and iii) radical photo initiator (R), where the wt.% ratio of contained (N) to contained (M) is at least 1.3 and the wt.% is relative to the total weight of the composition.

[0011] Compound (N) is not of the above structure type H2C=CH-CO-NH-R1 (with R1 represented by an organic residue).

[0012] All species subsumed to (N) have to fulfill the above viscosity requirement (measurement of the viscosity of each relevant individual species).

[0013] Acryl amides are generally highly photo polymerization reactive (free radical polymerization).

[0014] The printable composition according to the present invention fulfills the relevant quality requirements:

[0015] The composition provides the basis for a sufficient low viscosity. This is especially important in case of an ink-jetting application, where the generation of tiny (inkjettable) ink drops is necessary. However, also in case of resin printing a sufficient low viscosity is important (“processability of immersion of building platform and recoating of liquid surface”). Additionally, the composition provides the basis concerning a sufficient viscosity stability which is a basic requirement to maintain a working printing process (e. g. gelling of the ink or the resin would block and possibly even destroy the printer). Furthermore, the composition according to the present invention allows the generation of a print-product with beneficial mechanical properties - especially: high heat deflection temperature (HDT), low curing (polymerization) shrinkage, low brittleness, high rigidity and low material ageing. A sufficient (photopolymerization) curing after its application is possible in order to provide said mechanical properties and to avoid the generation of uncured material.

[0016] The use of a printable composition according to the present invention provides a kind of “compromise” that does take all of these relevant different issues into consideration - e. g. curing has to be intensive enough to provide a corresponding durability on the one hand but must be limited on the other hand in order to avoid brittleness.

[0017] The ink composition according to the present invention is often liquid at 25 °C (at 1 atm). Furthermore, the ink composition is normally also printable and often also jettable (printing through a nozzle be possible) - at elevated temperatures up to 65 °C (at 1 atm).

[0018] Typically, the composition is flowable and printable at temperatures of 10 - 65 °C. However, in some cases temperatures of at least 40 °C are necessary.

[0019] According to a special embodiment to the invention the printable composition according to the present invention might be provided as a kit: corresponding kit-in- parts composition may comprise a combination of at least the photocurable compounds and a separate photo initiator. However, in most cases it is not necessary and not advantageous to provide such a kit (a kit might be avoided).

[0020] Generally, photopolymerization mixtures are typically based on acrylates which represent effective photopolymerization monomers / oligomers. Such acrylates contain acryloyl groups (H2C=CH-C(=O)- , which might be a part of an “acryl ester group” of the type H2C=CH-C(=O)-O-). These groups are known as to be very reactive and efficient free radical polymerization groups (and much more reactive like e. g. meth acryl groups). As already said above, also acryl amides in general are effective photopolymerization compounds. However, in contrast to acrylates, secondary acrylamides (of the structure type H2C=CH-CO-NH-R1) provide also a hydrogen atom which works as a donor for hydrogen bonds. This fact might be a decisive factor for the special mechanical properties of such polymers containing structural units of secondary acrylamides: especially high HDT values might be achieved. In order to obtain the desired HDT values, polyacrylates (work as effective polymerization based crosslinkers) might be alternatively used but with the disadvantage that a non-desired intensive shrinkage (and sometimes also a low final double bond conversion) is caused.

[0021] Generally, secondary acryl amides have a high viscosity or are present as solids. Thus, viscosity reducing compounds / solvents as “co-compounds” are normally necessary to use these compounds in a printing ink or in a printing resin. In order to avoid the use of non-reacted compounds (being mechanical “weakeners’7 often volatile and / or bleeding out) these viscosity reducing co-compounds / solvents should react in order to become structural units of the polymer matrix. Such compounds are often called as “reactive diluents” which are substances which reduce the viscosity for processing and become part of the polymer matrix during its subsequent curing via copolymerization. According to the present invention the photo polymerization reactive compound (N) is provided as such a kind of “reactive diluent”.

[0022] The following reactive compounds (M) might be used (as single components or as mixtures of them):

[0023] PhAAm, N-phenyl acrylamide (a solid); Benzyl-AAm, N-benzyl acrylamide (a solid); tBu-AAm, N-tert butyl acrylamide (a solid); tOctyl-AAm, N-tert-Octylacrylamide (a solid);

[0024] Butoxymethyl-AAm, N-(butoxymethyl)acrylamide (viscous liquid); iButoxymethyl- AAm, N-(isobutoxymethyl)acrylamide (viscous liquid); diacetone acrylamide (solid). Typically, at least 50 wt.% of the contained (M) comprises an organic residue R1 which has at least 6 carbon atoms.

[0025] Preferably, at least 50 wt.% of the contained (M) comprises an organic residue R1 which contains a substituted or non-substituted phenyl group.

[0026] According to a special preferred embodiment at least 50 wt.% of the contained (M) is contributed by N-Phenyl acrylamide (which often provides excellent mechanical properties).

[0027] Phenyl acrylamide for example is a solid and should be solved in the component (N) entirely before its application.

[0028] Also, the component (N) should be preferably highly (photo) polymerization reactive. Thus, corresponding acrylates and tertiary acrylamides (“having not such a hydrogen atom”) might be used. Preferably, at least 50 wt.% of the contained (N) is provided by species of the group consisting of tertiary acrylamides and compounds containing acryloyl groups.

[0029] The following reactive organic compounds (N) might be used (as single components or as mixtures of them):

[0030] ACMO, acryloyl morpholine; VMOX, mono-vinyl oxazolidinone and I BOA, isobornyl acrylate. Especially I BOA, ACMO und VMOX each have a low viscosity (and are also good solvents for (M)) and generally contribute as co-polymerized structural units to beneficial mechanical properties (especially for avoiding brittleness).

[0031] Furthermore, crosslinking polyacrylates might be used for (N) - for example: TCCDA (tricyclodecane dimethanol diacrylate) as a di-acrylate and PEG600DA (polyethylene glycol diacrylate (n=approx. 9)) as a di-acrylate oligomer.

[0032] According to a preferred embodiment the wt.% sum of contained (N) and contained (M) is at least 51 wt.%, preferably a least 64 wt.% and more preferably at least 80 wt. %.

[0033] The radical photoinitiator (R) generates reactive species (free radicals) when exposed to radiation (e. g. UV or visible light).

[0034] The photo initiator might be comprised in the composition in an amount of 0.2 to 2.0 wt.%, based on the total weight of the printable composition. According to one embodiment species of the radical photoinitiator (R) are provided by phosphinoxide-based photoinitiators, preferably by diphenyl(2,4,6- trimethylbenzoyl)phosphine oxide and / or phenyl bis(2,4,6- trimethylbenzoyl)phosphine oxide.

[0035] The invention is also directed to the use of the printable composition in a printing procedure which is preferably a three-dimensional printing procedure. Generally, in such a printing procedure at least two layers of the ink composition according to the present invention were printed on top of each other. Furthermore, the present invention is directed to a three-dimensional object which has been prepared by using a printable composition according to the present invention.

[0036] In some cases, it is advantageous to treat the printing product (the three- dimensional object) with a thermal post processing to improve the mechanical properties (tension in the material is reduced by this).

[0037] The present invention is further described below by using examples.

[0038] General Terms and Definitions

[0039] Reactants as used in the examples

[0040] Isobornylacrylate (I BOA, SR506D) - CAS No 5888-33-5 from ARKEMA

[0041] Isobornylmethacrylate (IBOMA, Genomer 1121 M) - CAS No 7534-94- 3 from RAHN

[0042] - Acryloyl morpholine (ACMO) - CAS No 5117-12-4 from RAHN 5-Methyl-3-vinyl-2-oxazolidinone (VMOX) - CAS No 3395-98-0 from BASF

[0043] Triethylene glycol divinyl ether (TEGVE) - CAS No 765-12-8 from SIGMA ALDRICH

[0044] Trimethylolpropane triacrylate (TMPTA, SR351) - CAS No 15625-89-5 from ARKEMA

[0045] Tricyclo [5.2.102,6]decanedimethanol diacrylate (TCDDA, SR833S) - CAS No 42594-17-2 from ARKEMA

[0046] Tricyclo [5.2.102,6]decanedimethanol di methacrylate (TCDDMA, SR834) - CAS No 43048-08-4 from ARKEMA

[0047] 4-Hyroxybutyl acrylate (4-HBA) - CAS No 2478-10-6 from BASF

[0048] - Urethane dimethacrylate (UDMA, CN1964CG) - CAS No 72869-86-4 from ARKEMA

[0049] Polyethylene glycol 600 diacrylate (PEG600DA, Miramer M286) - CAS No 26570-48-9 from Ml WON

[0050] Polyethylene glycol 400 diacrylate (PEG400DA, Miramer M280) - CAS No 26570-48-9 from Ml WON

[0051] Polyethylene glycol 550 di methacrylate (PEG550DMA, SR252) - CAS No 25852-47-5 from ARKEMA

[0052] Bisphenol A-glycerolate (1 glycerin / phenol) diacrylate (BisGA) - CAS No 4687-94-9 from SIGMA ALDRICH

[0053] Genomer4230) - aliphatic urethane diacrylate from RAHN BDT-4330 - mixture of dendritic acrylate, dipentaerythritol penta- / hexaacrylate and dipentaerythritol hexaacrylate from BOMAR BR941 - mixture of aliphatic urethane hexaacrylate and pentaerythritol tetraacrylate from BOMAR

[0054] CN104 - Bisphenol A epoxy diacrylate oligomer - CAS No 55818-57-0 from ARKEMA

[0055] CN981 - polyether ester urethane diacrylate - CAS No 72162-39-1 from ARKEMA

[0056] 2-Hydroxy-3-(prop-enoyloxy)propyl 2-methyl-2-propylhexanoate (Ebecryl113) - CAS No 444649-70-1 from ALLNEX Hydroxyethylcaprolactone acrylate (Ebecryll 17) - CAS No 110489-05- 9 from ALLNEX

[0057] Bisphenol A ethoxylate diacrylate (Ebecryl150) - CAS No 64401-02-1 from ALLNEX

[0058] Phenyl acrylamide (PhAAm) - CAS No 2210-24-4 from CHEMOSYNTHA

[0059] Benzyl acrylamide (BenzylAAm) - CAS No 113304-62-6 from CHEMOSYNTHA

[0060] N-(1 ,1 ,3,3-Tetramethyl butyl)-acrylamide (tOctylAAm) - CAS No 4223- 03-4 from TCI

[0061] N-Butyoxy methyl acrylamide (ButoxymethylAAm) - CAS No 1852-16- 0 from TCI

[0062] N-(lsobutoxy methyl)acrylamide (i ButoxymethylAAm) - CAS No 16669- 59-3 from TCI

[0063] Diacetone acrylamide (DAAAm) - CAS No 2873-97-4 from TCI Omnirad 819 - photoinitiator with CAS No 162881-26-7 from IGM Resins

[0064] Genorad 16 - polymerisation inhibitor being a combination of glycerol propoxylate (1 PO / OH) and 4-methoxyphenol from RAHN

[0065] - BHT - CAS No 128-37-0 from SIGMA ALDRICH

[0066] BYK 333 - polyether modified polydimethylsiloxane additive from BYK

[0067] Viscosity of reactive diluents

[0068] Table 1: Viscosity measurements of reactive diluents.

[0069] Reactive q @25°C q @30°C q @40°C q @60°C diluent [mPa-s] [mPa-s] [mPa-s] [mPa-s]

[0070] IBOA 7.3 6.2 4.7 3.2

[0071] ACMO 10.1 8.2 5.9 3.7

[0072] VMOX 3.7 3.2 2.6 1.9

[0073] TEGVE 3.3 2.9 2.3 1.6 General methods for measuring

[0074] Viscosity is measured on a thermally controlled rotational rheometer in cone-plate geometry (Anton Paar Physica MCR 300, cone diameter: 60 mm, zero-gap distance: 0,061 mm, cone angle: 0,5°, shear-rate 600s-1) at temperatures from 25 to 55°C with a heating ramp of 2 K / min following the DIN EN ISO 3219. For comparison, the viscosity at 25 or 50 °C is shown in the following examples.

[0075] Storage stability of inks was determined with the same experiment than described above after storing closed sample jars for 7 days at 60 or 80 °C.

[0076] The Shore hardness D was measured following the DIN EN ISO norm 7619 by a OS-2 measuring device from Hildebrand Pruf- und Messtechnik GmbH with cylindrical specimens in diameter of 40 mm and thickness of 6 mm. The results were taken off the scale after 3 seconds of placing the needle on the specimen. The measurement was repeated 5 times.

[0077] Tensile testing was performed on a Zwick-Roell tensile tester 1445 following the DIN EN ISO norm 527-1 with 5A specimen. E-Modulus was determined from the slope of the stress-strain curve at deformations from 0.05-0.25 % at 1 mm / min. Tensile strength and elongation at break were determined by pulling the specimen at 5 mm / min.

[0078] The heat deflection temperature B (0.45 MPa) as a three-point-bending test was performed on a HDT-measuring device Compact 3 from Coesfeld on specimens with dimensions of 80 x 10 x 4 mm according to DIN EN ISO 75. The heat rate was set to 2 K / min in a range from 30 °C until reaching the HDT-value. The impact strength was measured using an IZOD set-up following DIN EN ISO norm 180 with notched specimens (notch base radius 0,25 mm and 8 mm remaining width at notch base) of dimensions of 80 x 10 x 4 mm and an impact pendulum of 1 J on a Zwick HIT5.5P Plus.

[0079] Resin printing was performed on a 405 nm LCD-printer SLS1s from Prusa.

[0080] Specimens were printed flat or vertically with 50 pm layer thickness. Each layer has a certain time of illumination which can vary from the illumination time of ten bottom layers. The detachment of specimens from bottom film was set in normal mode.

[0081] Inkjet printing was performed on a DP Polar inkjet printer using Xaar1003 printing heads and a 395 nm LED light source with an intensity of 12 W / cm2. The layer thickness, printing speed and intensity of the light source may vary by each experiment.

[0082] Different devices were used for post-curing. Thermal post-cure was carried out using an LIF55+ from Memmert placing one tray in the pre-heated chamber. UV post-curing was performed using a LC-3DPrint Box (3D Sys) from 3D Systems or the curing station (atum) from atum3D with broad-spectrum UV lamps or a UVAcube 2000 mercury post-cure unit from Hbnle (Hg) EXAMPLES

[0083] Example 1-8:

[0084] Synthesis, processing and characterization of resin compositions Synthesis, processing and liquid as well as mechanical characterization will be summarized in Table 2 and Table 3. In general, the compounds of said formulation were mixed and thoroughly stirred at elevated temperatures between 40 and 65 °C. The resin was then printed on an open source SLS1s LCD-screen printer from PRUSA with 405 nm (printing parameters are shown in Table 3: 10x bottom layer illumination time / time of illumination for each layer / layer thickness).

[0085] All flat and vertically printed specimens were cleaned using deminerialized water, dried for 1 to 48 hours at standard atmosphere and post-cured with given different post-processings (Table 3). Especially, example 6 shows the positive impact of the aromatic acrylamide regarding the impact resistance.

[0086] Table 2 Synthesis, viscosity and formulation ratios of resin compositions (1 content (M) wt.%; II ratio (N):(M); III content (N)+(M) wt.% ).

[0087] Ex Formulation r) 1 II III

[0088] 1 ACMO:PEG600DA:TCDDA:PhAAm:BAPO:Genorad16: 32 2 2.0 66.

[0089] BYK333 2 0 1

[0090] [44.05:18.0:15.0:22:0:0.5:0.25:0.2]

[0091] 2 IBOMA:ACMG:PEG600DA:TCDDMA:PhAAm:BAPO:G - 2 1.8 62. enorad16 2 2 0

[0092] [21 .0:19.0:25.0:11 .0:22:0:0.5:0.25]

[0093] 3 VMOX:PEG550DMA:TCDDMA:PhAAm:BAPO:BHT 25 2 1.4 54.

[0094] [32.0:30.0:15.0:22:0:0.5:0.25] 2 6 0

[0095] 4 VMOX:PEG550DMA:BDT-4330:PhAAm:BAPO:BHT 52 2 1.4 54.

[0096] [32.0:30.0:15.0:22:0:0.5:0.25] 2 6 0

[0097] 5 VMOX:PEG550DMA:UDMA:PhAAm:BAPO:Genorad16 30 2 1.6 58.

[0098] [36.8:30.0:10.0:22.0:1.0:0.25] 2 7 8

[0099] 6 VMOX:PEG600DA:PhAAm:BAPO:Genorad16 - 3 1.2 68.

[0100] [38.8:30.0:30.0:1.0:0.25] 0 9 8

[0101] 7 IBOA:VMOX:PEG600DA:PhAAm:BAPO:Genorad16 - 2 2.1 69.

[0102] [17.0:30.0:30.0:22:0:1.0:0.25] 2 4 0

[0103] Table 3: Printing parameters, post-curing parameters and mechanical and thermomechanical characterization of resin compositions.

[0104] Ex Printing Post E- Tensile Elongati HD Hardne Impact

[0105] Parameters - Modulu Strengt on at T B ss Strengt

[0106] Cure s [GPa] h break [°C] [Shore h [J / m]

[0107] 1 10s / 7,5s / 50 1 h 2.1 44 12 54 - 144* pm 130°

[0108] C

[0109] 2 12s / 10s / 50p 1 h 1.8 50 5.2 69 m 130°

[0110] C

[0111] 3 10s / 4s / 50p 1 h 1.6 35 16 62 - m 3D-

[0112] Sys

[0113] 4 10s / 5s / 50p 1 h 2.0 48 9.2 83 m 3D-

[0114] Sys

[0115] 5 10s / 4s / 50p 0,5h 2.1 43 3.8 68 80 26 m atum

[0116] 6 10s / 4s / 50p 0,5h 2.2 43 15 63 79 50 m atum

[0117] 7 10s / 4s / 50p 0,5h 2.5 55 13 79 82 41 m atum

[0118] 8 10s / 4s / 50p 0,5h 2.0 41 10 64 80 34 m atum *Unnotched specimens were measured following DIN EN ISO 180.

[0119] Example 9-12: Synthesis, processing and characterization of inkjet compositions

[0120] Synthesis, processing and liquid as well as mechanical characterization will be summarized in Table 4 and Table 5. In general, the compounds of said formulation were mixed and thoroughly stirred at elevated temperatures between 40 and 65 °C and filtered over 1 m. All inks were ink-jet UV printed with a 395 nm LED light source (printing parameters are shown in Table 5: speed of building platform / layer thickness, UV-intensity). All printed specimens were cleaned using water in an ultrasonic bath, dried for 1 to 48 hours at standard atmosphere and post-cured with given different post-processings (Table 5).

[0121] Table 4: Synthesis, viscosity and formulation ratios of inkjet compositions (I content (M) wt.%; II ratio (N):(M); III content (N)+(M) wt.%).

[0122] E Formulation r) I II III x. @30°C

[0123] [mPa-s]

[0124] 9 ACMG:PEG600DA:TCDDA:PhAAm:CN104:BAPO:Ge 61 22 1.7 60. norad 16: BYK333 4 3

[0125] [38.3:15.7:13.1 :22.0:10.0:0.5:0.25:0.2]

[0126] 1 IBGA:ACMO:PEG600DA:TCDDA:PhAAm:BAPO:Gen 45 25 1.3 59.

[0127] 0 orad16: BYK333 6 1

[0128] [24.1 :10.0:20.0:20.0:25.0:0.5:0.25:0.2]

[0129] 1 IBGMA:ACMO:PEG600DA:TCDDA:PhAAm:BAPO:Ge 31 22 2.0 66.

[0130] 1 norad 16: BYK333 0 1

[0131] [5.0:39.1 :18.0:15.0:22.0:0.5:0.25:0.2]

[0132] 1 IBGA:ACMO:PEG600DA:TCDDA:PhAAm:TMPTA:BA 38 20 1.8 56.

[0133] Table 5: Printing parameters, post-curing parameters and mechanical and thermomechanical characterization of inkjet compositions.

[0134] Ex. Printing Post- E- Tensile Elongation HDT B

[0135] Parameters Cure Modulus Strength at break [°C]

[0136] 9 15 m / min / 12 pm, 1 h 3.1 79 8.5 97

[0137] 60% 130°C

[0138] 10 15 m / min / 12 pm, 1 h 2.3 53 17 83

[0139] 60% 130°C

[0140] 11 15 m / min / 12 pm, 1 h 2.8 64 15 95

[0141] 60% 130°C

[0142] 12 15 m / min / 12 pm, - 1.1 21 10

[0143] 100% Example 13-31 :

[0144] To screen ink and material properties of potential resins and inkjet formulations molded specimens are cured for 30 s from each side in translucent silicon molds from the bottom at a distance of 15 cm by UV-light (LED 395 nm, 16 W / cm2). Testing results of this photopolymerized bulk specimens are then emphasizing in a good proximity the final material performance of material jetted or resin printed and post-cured formulations, even though the preparation process in the first curing-step differs. Examples 13-25 (Table 6 and Table 7) illustrate a varying formulation ratio of different reactive diluent, acrylate and aromatic acrylamide compounds to highlight the correlation of printing application and material characteristics. Comparative examples 23 - 25 stresses the importance of a defined reactive diluent to aromatic acrylamide ratio. The higher the content of the aromatic acrylamide, the higher the heat deflection temperature, but the lower the solubility in the mixture. Example 25 is not a stable homogenous mixture over several weeks in storage conditions. Examples 27 - 31 (

[0145] Table 8 and Table 9) show comparative examples with secondary acrylamides to the aromatic moiety (example 26).

[0146] Table 6: Synthesis, viscosity and formulation ratios of resin compositions, molded (I content (M) wt.%; II ratio (N):(M); III content (N)+(M) wt.%).

[0147] Ex Formulation r) I II III

[0148] 13 ACMO:PEG600DA:TCDDA:PhAAm:BisGA:BAPO:Gen 51 2 1.9 65. orad16 2 7 4

[0149] [43.4:17.5:14.5:22.0:3.0:0.3:0.25]

[0150] 14 ACMO:PEG600DA:TCDDA:PhAAm:BisGA:BAPO:Gen 144 2 1.5 55. orad16 2 0 0

[0151] [33.0:13.4:11 .1 :22.0:22.0:0.3:0.25]

[0152] 15 ACMO:PEG600DA:TCDDA:PhAAm:Ebecryl150:BAPO: 46 2 1.7 60.

[0153] Genorad16 [38.7:15.7:13.1 :22.0:10.0:0.3:0.25] 2 6 7

[0154] 16 VMOX:PEG600DA:TCDDA:PhAAm:4- 19 2 1.3 51.

[0155] HBA:BAPO:Genorad16 2 4 5

[0156] [29.5:18.0:15.0:22.0:15.0:0.3:0.25] 17 VMOX:PEG600DA:TCDDA:PhAAm:Ebecryl113:BAPO: 30 2 1.3 51. Genorad16 [29.5:18.0:15.0:22.0:15.0:0.3:0.25] 2 4 5

[0157] 18 VMOX:PEG600DA:TCDDA:PhAAm:Ebecryl117:BAPO: 73 2 1.3 51. Genorad16 [29.5:18.0:15.0:22.0:15.0:0.3:0.25] 2 4 5

[0158] 19 VMGX:PEG600DA:TCDDA:PhAAm:CN981 :BAPO:Gen 73 2 1.3 51. orad16 2 4 5

[0159] [29.5:18.0:15.0:22.0:15.0:0.3:0.25]

[0160] 20 IBGA:ACMO:PEG600DA:TCDDA:PhAAm:BR941 :BAP 36 2 1.8 56. O: Genorad16 [19.6:17.1 :16.2:16.2:20.3:10.0:0.3:0.25] 0 1 9

[0161] 21 ACMO:VMOX:PEG600DA:TCDDA:PhAAm:Genomer4 134 2 1.5 55.

[0162] 230: BAPO:Genorad16 2 0 0 [9:65:23.3:20.0:7.0:22.0:17.5:0.3:0.25]

[0163] 22 TEGVE:PEG600DA:TCDDA:PhAAm:BAPG:Genorad1 2 1.7 63. 6 [40.0:18.0:18.0:23.0:0.3:0.25] 3 4 0

[0164] 23 ACMO:PEG600DA:TCDDA:PhAAm:BAPO:Genorad16 60 1 1.8 28. [18.0:53.0:18.0:10.0:0.3:0.25] 0 0 0

[0165] 24 IBOA:ACMG:PEG600DA:TCDDA:PhAAm:BAPO:Geno 56 1 4.0 50. rad16 [22.0:18.0:31.0:18.0:10.0:0.3:0.25] 0 0 0

[0166] 25 ACMO:PEG600DA:TCDDA:PhAAm:BAPO:Genorad16 63 4 1.0 80.

[0167] Table 7: Mechanical and thermomechanical characterization of molded resin compositions.

[0168] Ex. E-Modulus Tensile Elongation HDT B Impact

[0169] [GPa] Strength at break [%] [°C] Strength

[0170] 13 3.1 80 7.1 115

[0171] 14 3.1 80 6.2 119

[0172] 15 2.4 73 6.0 111

[0173] 16 2.5 51 12 77 19

[0174] 17 2.4 52 6.9 87 17

[0175] 18 2.2 46 7.6 76 20

[0176] 19 2.6 61 8.7 90 24

[0177] 20 2.2 42 2.7

[0178] 21 1.3 31 23 73 43

[0179] 22 0.2 7.0 11 37

[0180] 23 0.8 21 16 41

[0181] 24 1.8 37 13 68

[0182] 25 3.2 79 3.6 128

[0183] Table 8: Synthesis, viscosity and formulation ratios of resin compositions, molded (I content (M) wt.%; II ratio (N):(M); III content (N)+(M) wt.%).

[0184] 26 IBGA:ACMO:PEG600DA:TCDDA:PhAAm:BAPO: 37 2 1.7 64.

[0185] Genorad16 [22.0:19.0:18.0:18.0:22.5:0.3:0.25] 3 8 0

[0186] 27 IBGA:ACMO:PEG600DA:TCDDA:BenzylAAm:BAPO: 25 2 1.7 64.

[0187] Genorad16 [22.0:19.0:18.0:18.0:22.5:0.3:0.25] 3 8 0

[0188] 28 IBGA:ACMO:PEG600DA:TCDDA:tOctylAAm:BAPO: 29 2 1.7 64.

[0189] Genorad16 [22.0:19.0:18.0:18.0:22.5:0.3:0.25] 3 8 0

[0190] 29 IBGA:ACMO:PEG600DA:TCDDA:ButoxymethylAAm:B 20 2 1.7 64.

[0191] APO: Genorad16 [22.0:19.0:18.0:18.0:22.5:0.3:0.25] 3 8 0

[0192] 30 IBOA:ACMO:PEG600DA:TCDDA:iButoxymethylAAm: 22 2 1.7 64.

[0193] BAPO: Genorad16 [22.0:19.0:18.0:18.0:22.5:0.3:0.25] 3 8 0

[0194] 31 IBOA:ACMO:PEG600DA:TCDDA:DAAAm:BAPO:Gen 27 2 1.7 64.

[0195] Table 9: Mechanical and thermomechanical characterization of molded resin compositions.

[0196] Ex. E-Modulus Tensile Elongation HDT B Impact

[0197] [GPa] Strength at break [%] [°C] Strength

[0198] 26 2.5 61 5.8 100

[0199] 27 2.3 52 6.2 83

[0200] 28 2.1 43 6.1 78

[0201] 29 2.0 40 8.8 62

[0202] 30 2.2 45 8.2 64

[0203] 31 2.2 47 6.2 82

[0204] Example 32-36:

[0205] Comparative examples 33, 35 and 36 show the influence of aromatic acrylamides in potential resins and inks for printing applications in comparison to formulations only containing of acrylate and methacrylate compounds. Within the experiments, the content of the monofunctional aromatic secondary acrylamide was added onto the amount of a chosen reactive diluent. Synthesis, processing and liquid as well as mechanical characterization was summarized in Table 10 and Table 11. In general, the compounds of said formulation were mixed and thoroughly stirred at elevated temperatures between 40 and 65 °C. The resin was then printed on an open source SLS1s LCD-screen printer from PRLISA with 405 nm (printing parameters are shown in Table 10: 10x bottom layer illumination time / time of illumination for each layer / layer thickness). All vertically printed specimens were cleaned using deminerialized water, dried for 1 to 48 hours at standard atmosphere and post-cured with given different post-processings (Table 10).

[0206] In examples 32 and 33 different effects of the aromatic acrylamide PhAAm can be observed. Without PhAAm (33) the formulation is less rigid (E-modulus and tensile strength) and shows a high tendency for cracking under the influence of thermal energy. Formulations with aromatic acrylamide are more ductile as well as stable and resistant in thermal conditions. Moreover, even though a quite similar network density is given in the cured parts, the formulation without aromatic acrylamide does not pass in-vitro cytotoxicity testing following EN ISO 10993-5.

[0207] Examples 34 - 36 show the difference of formulating with aromatic acrylamide (34) in comparison to using a methacrylate moiety (35, 36). In general, methacrylates are reaching higher HDT B values than their counter acrylate compounds due to an intrinsic higher glass transition temperature. But with reaching high HDT values the brittleness in terms of elongation at break increases and less ductile materials with lower impact resistance follows. This contrasts with the good balance in impact resistance, flexibility, toughness to high HDT B values in resin and ink formulations composed by aromatic secondary acrylamides. Moreover, due to the lower reactivity towards LED light sources formulations containing methacrylates compared to highly reactive aromatic acrylamides need a prolonged curing and therefore processing time.

[0208] Table 10: Synthesis, viscosity and formulation ratios of resin compositions (I content (M) wt.%; II ratio (N):(M); III content (N)+(M) wt.% ).

[0209] 32 10s / 4s / 50pm 0,5h 2.2 45 8 72 - atum 10s / 4s / 50pm 0,3h Hg 2.2 47 12 73 -

[0210] + 1 h 190°C

[0211] 33 10s / 4s / 50pm 0,5h 1.7 35 13 67 - atum 10s / 4s / 50|jm 0,3h Hg Cracks, no measurement possible + 1 h 190°C

[0212] 34 10s / 4s / 50pm 0,5h 2.3 47 10 74 34 atum

[0213] 35 15s / 9s / 50pm 0,5h 2.0 40 5 83 15 atum

[0214] 36 15s / 9s / 50pm 0,5h 2.2 47 7 97 13 atum

Claims

Claims1. A printable composition comprising: i) at least 18 wt.% photo polymerization reactive compound (M) provided by a secondary acryl amide of the structure type H2C=CH- CO-NH-R1, with R1represented by an organic residue, where at least 50 wt.% of the contained (M) comprises an organic residue R1which contains an aromatic group, ii) photo polymerization reactive organic compound (N) which is different from (M) with the proviso that: all species of the reactive organic compound (N) have a viscosity of maximum 50 mPa s at 25 °C (measured according to DIN EN ISO 3219-2, August 2021 , with the proviso that: use of rotational rheometer in cone-plate geometry: cone diameter 60 mm, zero-gap distance 0.061 mm, cone angle 0.5 °; use of active thermal cover and heat plate; use of shearrate of 600 s-1 ; general temperature measurement range 25-70 °C) and iii) radical photo initiator (R), where the wt.% ratio of contained (N) to contained (M) is at least 1 .3 and the wt.% is relative to the total weight of the composition.

2. A printable composition according to claim 1 , where the wt.% sum of contained (N) and contained (M) is at least 51 wt.%.

3. A printable composition according to claim 1 or 2 that is flowable and printable at temperatures of 10 - 65 °C.

4. A printable composition according to one of the claims 1 - 3, where at least 50 wt.% of the contained (M) comprises an organic residue R1which has at least 6 carbon atoms.

5. A printable composition according to one of the claims 1 - 4, where at least 50 wt.% of the contained (M) comprises an organic residue R1which contains a substituted or non-substituted phenyl group.

6. A printable composition according to one of the claims 1 - 5, where at least 50 wt.% of the contained (M) is contributed by N-Phenyl acrylamide.

7. A printable composition according to one of the claims 1 - 6, where at least 50 wt.% of the contained (N) is provided by species of the group consisting of tertiary acrylamides and compounds containing acryloyl groups.

8. Use of a printable composition according to one of the claims 1 - 7 in a printing procedure.

9. Use according to claim 8 in which the printing procedure is a three- dimensional printing procedure.

10. Use according to claim 9, where at least two layers of the printable composition according to one of the claims 1 - 7 were printed on top of each other.

11. Three-dimensional object which has been prepared by using a printable composition according to one of the claims 1 - 7.

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