Method for making additives using compositions comprising polyesters

Abstract

The present invention relates to a method for additive manufacturing using a composition comprising the reaction product of a polyester polyol and a compound comprising at least one functional group reactive with a hydroxyl group of the polyester polyol and at least one further functional group selected from acrylate or methacrylate groups as a photopolymerizable material, wherein the polyester polyol is based on at least one organic acid comprising at least two carboxyl groups or anhydrides thereof and at least one polyol comprising at least two hydroxyl groups, wherein the reaction product has a glass transition temperature Tg of less than 23° C., wherein the composition optionally further comprises a photoinitiator.

Description

[0001] The present invention relates to a method for additive manufacturing using a composition comprising the reaction product of a polyester polyol and a compound comprising at least one functional group reactive with a hydroxyl group of the polyester polyol and at least one further functional group selected from an acrylate or methacrylate group as a photopolymerizable material, wherein the polyester polyol is based on at least one organic acid comprising at least two carboxyl groups or anhydrides thereof and at least one polyol comprising at least two hydroxyl groups, wherein the reaction product has a glass transition temperature Tg of less than 23° C., and wherein the composition optionally further comprises a photoinitiator. Background Art

[0002] Additive manufacturing based on lithography (such as stereolithography), like general 3D printing processes, has traditionally been used primarily for the production of prototypes and functional patterns ("rapid prototyping"). Due to technological advances, practical production applications, such as transparent brackets or hearing aid housings, are becoming increasingly important. For these applications, the mechanical and thermal properties of the printed material are crucial. However, the materials currently available for additive manufacturing do not yet have the mechanical properties of conventional manufacturing materials (see, for example, T. Swetly, J. Stampfl, G. Kempf and R.-M. Hucke, "Capabilities of Additive Manufacturing Technologies (AMT) in the Validation of the Automobile Cockpit", RTejournal-Forum for RapidTechnology 2014 (1)).

[0003] These materials (resins) used for lithography-based additive manufacturing are based on reactive components that can be exposed and thus cured. For this purpose, free radical (e.g., for acrylates) or cationic (e.g., for epoxides) polymerization is often used. For this purpose, special photoinitiators are added to the resin, which change their state upon exposure and thus initiate polymerization of the reactive components.

[0004] Various methods such as stereolithography, digital light processing and multi-jet modeling can be used to manufacture objects from these resins. Using all procedures, these resins are hardened layer by layer, thereby producing three-dimensional objects. Usually, low-viscosity resins are required, for example 20-40 mPa.s (see I. Gibson, DW Rosen, B. Stucker et al., "Additive manufacturing technologies", vol. 238, Springer Verlag (2010)). In order to improve the mechanical properties of the products cured in this way, in particular toughness and elongation at break, the crosslinking density must be reduced, or the molecular weight of the monomers must be increased. However, this increases the viscosity or melting point of the uncured resin, and due to the latter, it has not been possible to use additive manufacturing methods for curing until recently.

[0005] However, new developments have made it possible to process resins with even higher viscosities. For example, WO 2015 / 075094 A1 and WO 2016 / 078838 A1 disclose stereolithography apparatuses in which sequentially cured layers of polymerizable material can be heated, allowing the processing of even highly viscous resins. WO 2015 / 074088 A2 discloses a photopolymerizable composition with a viscosity of at least 20 Pa.s at room temperature that is heated to at least 30°C during curing. For comparison: 20 Pa.s is roughly equivalent to the viscosity of ethylene glycol or viscous honey, while butter with a viscosity of approximately 30 Pa.s barely flows.

[0006] However, issues regarding the mechanical properties of hardened products, such as 3D-printed parts, remain unresolved. For example, such products have insufficient impact strength and ductility, are too brittle, and absorb too much moisture from the ambient air.

[0007] WO 2008 / 125202 A1 discloses polyurethane systems curable by radiation and thermal crosslinking and their use for producing holographic media. The polyurethane composition comprises A) a polyisocyanate, B) a polyol comprising at least one poly(ε-caprolactone) polyester polyol, C) a compound having groups that react with ethylenically unsaturated compounds upon polymerization upon exposure to actinic radiation, D) a free radical stabilizer (if necessary), and E) a photoinitiator. The polycaprolactone polyols present preferably have a molecular weight of 500 to 2000 g / mol and serve as "structural units of the matrix polymer," meaning they are polyaddition-polymerized with the polyisocyanate to give the desired polyurethane.

[0008] WO 2018 / 197677 A1 describes an improved photocurable composition for use in additive manufacturing (AM) production processes. The photocurable composition has a viscosity of at least 20 Pa.s at 20°C and comprises a photopolymerizable matrix material, at least one thermoplastic polymer dissolved therein, and at least one photoinitiator, wherein polycaprolactone or a derivative thereof is used as the dissolved thermoplastic polymer.

[0009] WO 2019213585 A1 describes a curable composition for use in a high-temperature photolithography-based photopolymerization process, a method for producing a crosslinked polymer using the curable composition, the crosslinked polymer produced thereby, and an orthodontic appliance comprising the crosslinked polymer. The curable composition contains a so-called toughness modifier, preferably comprising (poly)carbonate and (poly)urethane groups.

[0010] WO2019213588 A1 describes a curable composition for use in a high-temperature photolithography-based photopolymerization process, a method for producing a cross-linked polymer using the curable composition, the cross-linked polymer produced thereby, and an orthodontic appliance comprising the cross-linked polymer. The curable composition comprises a monomer based on 2-, 3-, or 4-(meth)acryloyloxybenzoate as a novel polymerizable monomer.

[0011] The problem underlying the present invention is to provide a composition which is photocurable and exhibits good properties, in particular with regard to tensile strength and elongation at break. Summary of the Invention

[0012] Surprisingly, it has been found that this problem is solved by the composition according to the claims.

[0013] The present invention therefore achieves these objects by providing a method for additive manufacturing using as a photopolymerizable material a composition comprising the reaction product of a polyester polyol and a compound comprising at least one functional group reactive with the hydroxyl groups of the polyol and at least one further functional group selected from acrylate or methacrylate groups, wherein the polyester polyol is based on at least one organic acid comprising at least two carboxyl groups or its anhydride and at least one polyol comprising at least two hydroxyl groups, wherein the composition optionally further comprises a photoinitiator.

[0014] The compositions used in the present invention have the advantage that they can be processed at temperatures below 120° C., preferably at or below 100° C. This is because the viscosity of the composition at the processing temperature is preferably below 20 Pa·s.

[0015] The compositions used in the present invention have the advantage that they preferably do not contain any solvents. Therefore, no organic volatiles are generated during the additive manufacturing process.

[0016] The compositions used according to the invention may further have the advantage that they can be produced in a simple manner.

[0017] The compositions used according to the invention have the advantage that they can contain fillers which lead to better properties, in particular better tensile strength and elongation at break.

[0018] The compositions used in the present invention have the additional advantage that they comprise polymers (reaction products) having a low Tg and that, by using such compositions, elastomers or products having one or more properties typically associated with elastomers (e.g., an elongation at break preferably greater than 40%, more preferably greater than 60%, most preferably greater than 100%) can be obtained by aiding manufacturing.

[0019] The compositions, methods and uses according to the present invention are described below by way of example, without intending to limit the present invention to these exemplary embodiments. When the scope, general formula or category of a compound are specified below, these are not only intended to cover the corresponding range or group of the compound explicitly mentioned, but also to cover all sub-ranges and sub-groups of the compound that can be obtained by not considering a single value (scope) or compound. In the context of this specification, when citing a document, its content should fully constitute a part of the disclosure of the present invention, particularly with regard to the matters cited. Unless otherwise stated, the percentages specified below are all by weight. In the case of reporting average values ​​below, these are numerical averages unless otherwise stated. In the case of mentioning the properties (such as viscosity, etc.) of a material below, these are the properties of the material at 25°C unless otherwise stated. In the case of using a chemical (empirical) formula in the present invention, the subscript specified can be not only an absolute number, but also an average value.

[0020] The additive manufacturing method of the present invention is characterized in that a composition comprising a reaction product of a polyester polyol and a compound comprising at least one functional group reactive with the hydroxyl groups of the polyester polyol and at least one further functional group selected from acrylate or methacrylate groups is used as the photopolymerizable material, wherein the polyester polyol is based on at least one organic acid comprising at least two carboxyl groups or its anhydride and at least one polyol comprising at least two hydroxyl groups, the organic acid preferably comprising 4 to 44, more preferably 18 to 44, most preferably 24 to 44 carbon atoms, wherein the reaction product has a Tg of less than 23°C, preferably a Tg of -60°C to 0°C, more preferably a Tg of -50°C to -20°C, and wherein the composition optionally further comprises a photoinitiator.

[0021] Preferably, the polyester polyol is based on a dicarboxylic acid, more preferably on an aliphatic dicarboxylic acid, most preferably on an acyclic aliphatic dicarboxylic acid.

[0022] The polyester polyols of the present invention preferably do not contain any carbonate groups, such as groups of the formula -OC(O)-O-. Most preferably, the polyester polyols of the present invention preferably do not contain any carbonate groups and are based on dicarboxylic acids, more preferably on aliphatic dicarboxylic acids, most preferably on acyclic aliphatic dicarboxylic acids.

[0023] The organic acid or anhydride containing at least two carboxyl groups, preferably two carboxyl groups, is preferably a dimer fatty acid (also called dimerized fatty acid or dimer acid). These dimer fatty acids are mixtures prepared by oligomerization of unsaturated fatty acids. The starting materials that can be used preferably include unsaturated C 12 to C 22 Fatty acids. According to the C used to prepare dimerized fatty acids 12 to C 22 The number and position of double bonds in the fatty acids. The carboxyl groups of the dimerized fatty acids are linked to one another via hydrocarbon groups having primarily 24 to 44 carbon atoms. These hydrocarbon groups are typically branched and may contain double bonds, C6 alicyclic hydrocarbon groups, or C6 aromatic hydrocarbon groups; these alicyclic hydrocarbon groups and / or aromatic hydrocarbon groups may also be fused. The groups linking the carboxyl groups of the dimerized fatty acids preferably have no aromatic hydrocarbon groups, and very preferably have no unsaturated bonds and no aromatic hydrocarbon groups.

[0024] Preferably, the organic acid is a dimer acid of a fatty acid containing 12 to 22, preferably 16 to 20, most preferably 18 carbon atoms. 18 Fatty acids are used to produce dimerized fatty acids. It is particularly preferred to use C 18 As fatty acids, very preferably linolenic acid, linoleic acid and / or oleic acid are used.

[0025] The oligomerization mentioned above can produce a mixture that mainly comprises dimeric molecules but also trimeric molecules as well as monomeric molecules and other by-products, depending on the reaction scheme. Purification can usually be carried out by distillation. Commercial dimer fatty acids preferably comprise at least 80 wt % of dimeric molecules, at most 19 wt % of trimeric molecules and no more than 1 wt % of monomeric molecules and other by-products.

[0026] For the purposes of the present invention, preference is given to using dimerized fatty acids composed of ≥90% by weight of dimerized molecules, ≤5% by weight of trimerized molecules, and ≤5% by weight of monomeric molecules and other by-products. Particular preference is given to using dimerized fatty acids composed of 95 to 98% by weight of dimerized molecules, less than 5% by weight of trimerized molecules, and less than 1% by weight of monomeric molecules and other by-products. Likewise, particular preference is given to using dimerized fatty acids composed of ≥98% by weight of dimerized molecules, ≤1.5% by weight of trimerized molecules, and ≤0.5% by weight of monomeric molecules and other by-products.

[0027] According to the reaction scheme, dimerized fatty acids contain aliphatic and aromatic molecular fragments. The aliphatic molecular fragments can be further divided into linear and cyclic fragments, which can be saturated or unsaturated. Aromatic and unsaturated aliphatic molecular fragments can be converted into the corresponding saturated aliphatic molecular fragments by hydrogenation.

[0028] Preferred dimerized fatty acids for use in the present invention are for example those from Oleon 0970, 0971, 0972, 0975, 0976 and 0977, Pripol 1006, Pripol 1009, Pripol 1012 and Pripol 1013 from Unichema, and Pripol 1013 from BASF 1008, 1061 and 1062, and from Arizona Chemical 10 and TI.

[0029] Instead of using dimer fatty acids as organic acids containing at least two carboxyl groups or their anhydrides, it may be advantageous to use aliphatic dicarboxylic acids containing 4 to 10, preferably 6 to 8, carbon atoms. Most preferably, adipic acid (fatty acid) is used as the aliphatic dicarboxylic acid.

[0030] The at least one polyol is preferably selected from the group consisting of octahydro-4,7-methylene-1H-indenedimethanol, methylpropylene glycol-1,3, monoethylene glycol, neopentyl glycol and hexanediol-1,6.

[0031] It is particularly preferred if at least one of the at least one polyol is octahydro-4,7-methylene-1H-indenedimethanol and at least one of the at least one organic acid comprising at least two carboxyl groups is a dimer acid of a fatty acid comprising 18 carbon atoms or preferably adipic acid.

[0032] The polyester polyol present in the composition according to the invention can be obtained by esterification processes known in the art. Preferably, the polyester polyol is obtained using a process as described in process step A of the process according to the invention.

[0033] The concentration of acid end groups in the polyester polyols, determined to DIN EN ISO 2114, is preferably between 0 and 10 mg KOH / g, but preferably below 2 mg KOH / g.

[0034] The number-average molecular weight of the polyester polyols used according to the invention is preferably from 1000 to 20 000 g / mol, preferably from 3000 to 10 000 g / mol. It is determined in accordance with DIN 55672-1 by gel permeation chromatography using tetrahydrofuran as eluent and polystyrene for calibration.

[0035] The compound comprising at least one functional group reactive with the hydroxyl group of the polyester polyol and at least one additional functional group selected from acrylate or methacrylate groups is preferably an isocyanate compound comprising at least one (meth)acrylate group and at least one isocyanate group. More preferably, the isocyanate compound is a reaction product of a diisocyanate with a compound comprising a hydroxyl group and a (meth)acrylate group, preferably a reaction product of hydroxyethyl methacrylate or hydroxyethyl acrylate with isophorone diisocyanate (IPDI), one or more trimethyl-1,6-hexane diisocyanate (TMDI), 4,4'-dicyclohexylmethane diisocyanate (H12MDI) or hexamethylene diisocyanate (HDI), and most preferably a reaction product of hydroxyethyl methacrylate or hydroxyethyl acrylate with isophorone diisocyanate.

[0036] Isocyanate compounds comprising at least one (meth)acrylate group and at least one isocyanate group can be prepared as described, for example, in WO 2010115644 A1 or WO 2019213585 A1.

[0037] The compositions used according to the invention may include additional ingredients:

[0038] It may be advantageous to have one or more photoinitiators present in the compositions of the present invention. A photoinitiator is preferably a molecule that generates reactive species (e.g., free radicals, cations, or anions) when exposed to radiation (ultraviolet or visible light). Any suitable photoinitiator may be present in the compositions of the present invention, including Type I and Type II photoinitiators and including conventional ultraviolet photoinitiators, examples of which include, but are not limited to, acetophenones (e.g., diethoxyacetophenone), phosphine oxides, diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide, phenyl bis (2,4,6-trimethylbenzoyl) phosphine oxide (PPO), Irgacure 369, and the like (see, for example, U.S. Patent No. 9,453,142 to Rolland et al.). Preferred photoinitiators according to the present invention are those that generate free radicals. The most preferred photoinitiator is bis (2,4,6-trimethylbenzoyl) -phenyl phosphine oxide, which is available from IGM resins under the trade name Irgacure 369. 819 (formerly known as Other photoinitiators that can be used in the compositions of the present invention are available from IGM resins under the product names TPO and The amount of the one or more photoinitiators present in the composition of the present invention is preferably from 0.1 to 5 wt%, more preferably from 0.5 to 2 wt%, most preferably from 0.8 to 1.2 wt%, based on the total composition.

[0039] The compositions used according to the present invention may have solid particles suspended or dispersed therein. Depending on the final product being manufactured, any suitable solid particles may be used. The particles may be metallic, organic / polymeric, inorganic, or a composite or mixture thereof. The particles may be non-conductive, semi-conductive, or conductive (including metallic and non-metallic or polymeric conductors); and the particles may be magnetic, ferromagnetic, paramagnetic, or non-magnetic. The particles may have any suitable shape, including spherical, ellipsoidal, cylindrical, and the like. The particles may have any suitable size (e.g., an average diameter of 1 nm to 200 μm).

[0040] The particles may comprise the active agent or detectable compound, although these may also be provided solubilized and / or dissolved in the composition of the invention.For example, magnetic or paramagnetic particles or nanoparticles may be used.

[0041] The compositions used in the methods of the present invention may have additional ingredients mixed or dissolved therein, including pigments, dyes, active or pharmaceutical compounds, detectable compounds (e.g., fluorescent, phosphorescent, radioactive), etc., again depending on the specific purpose of the product being manufactured.

[0042] It may be advantageous if the composition used in the method of the present invention includes one or more non-reactive pigments or dyes that absorb light. Suitable examples of such light absorbers include, but are not limited to: (i) titanium dioxide (e.g., included in an amount of 0.05 wt % or 0.1 wt % to 1 wt % or 5 wt %), (ii) carbon black (e.g., included in an amount of 0.05 wt % or 0.1 wt % to 1 wt % or 5 wt %), and / or an organic UV absorber such as a hydroxybenzophenone, hydroxyphenylbenzotriazole, oxanilide, benzophenone, thioxanthone, hydroxyphenyltriazine and / or a benzotriazole UV absorber (e.g., Mayzo BLS1326) (e.g., included in an amount of 0.001 wt % or 0.005 wt % to 1 wt %, 2 wt % or 4 wt %). Examples of suitable organic ultraviolet light absorbers include, but are not limited to, those described in US Pat. Nos. 3,213,058; 6,916,867; 7,157,586; and 7,695,643, the disclosures of which are incorporated herein by reference.

[0043] Depending on the desired properties of the component or object to be manufactured, the composition used in the method according to the present invention may contain any suitable filler. Thus, the filler may be solid or liquid, organic or inorganic, and may include reactive and non-reactive rubbers: silicones, acrylonitrile-butadiene rubber; reactive and non-reactive thermoplastics (including but not limited to: poly(etherimide), maleimide-styrene terpolymers, polyarylates, polysulfones and polyethersulfones, etc.); inorganic fillers such as silicates (such as talc, clay, silica, mica), glass, carbon nanotubes, graphene, cellulose nanocrystals, etc., including combinations of all of the above. Suitable fillers include toughening agents, such as core-shell rubbers.

[0044] The composition used in the method according to the invention preferably contains one or more fillers, more preferably 0.5 to 50% by weight, preferably 1 to 15% by weight of fillers, based on the composition. The filler is preferably selected from inorganic particles, more preferably from carbon black and / or silica. Most preferably, silica functionalized with methacrylate groups is present as filler in the composition according to the invention. Suitable silica functionalized with methacrylate groups is available, for example, from Evonik Industries AG (Evonik Resource Efficiency GmbH) under the trade name 701 or 711 obtained.

[0045] It may be advantageous if the composition used in the method of the invention contains a further compound containing at least one methacrylate group, wherein the compound does not contain isocyanate groups or other functional groups. The further compound can serve as a reactive diluent and / or crosslinking agent. The compound is preferably present in an amount of 5 to 95% by weight, more preferably 10 to 50% by weight, based on the total weight of the composition. Suitable compounds are, for example, commercially available from Evonik Industries AG under the trade name The preferred compound is glycerol formal methacrylate ( Glyfoma), diurethane dimethacrylate ( HEMA TMDI), butyl diglycol methacrylate ( BDGMA), polyethylene glycol 200 dimethacrylate ( PEG200DMA), trimethylolpropane methacrylate ( TMPTMA) or isobornyl methacrylate ( Terra IBOMA). The compositions of the present invention most preferably comprise isobornyl methacrylate ( Terra IBOMA) (preferably in an amount of 10 to 50% by weight, based on the total weight of the composition) as a further compound comprising at least one methacrylate group, wherein this compound does not comprise isocyanate groups or other functional groups.

[0046] The composition used in the method according to the invention preferably comprises a polymerization inhibitor and / or an antioxidant. By using a polymerization inhibitor and / or an antioxidant, polymerization of the composition can be prevented before it is used in the additive manufacturing method. Suitable polymerization inhibitors are, for example, 2,6-di-tert-butyl-4-methylphenol, catechol, 4-methoxyphenol, 4-tert-butyloxyphenol, 4-benzyloxyphenol, naphthol, phenothiazine, 10-10-dimethyl-9,10-dihydroacridine, bis-[2-hydroxy-5-methyl-3-cyclohexylphenyl]-methane, bis-[2-hydroxy-5-methyl-3-tert-butylphenyl]-methane, hydroquinone, pyrogallol, 3,4-dihydroxy-1-tert-butylbenzene, 4-methoxy-2(3)-tert-butylphenol (BHA), a combination of BHA and bis-[2-carboxyethyl]-sulfide (TDPA), 4-methyl-2, 6-di-tert-butylphenol (BHT), bis-[4-hydroxy-2-methyl-5-tert-butylphenyl]-sulfide, 4-butylmercaptomethyl-2,6-di-tert-butylphenol, distearyl 4-hydroxy-3,5-di-tert-butylphenylmethanesulfonate, 2,5-dihydroxy-1-tert-butylbenzene, 2,5-dihydroxy-1,4-di-tert-butylbenzene, 3,4-dihydroxy-1-tert-butylbenzene and 2,3-dimethyl-1,4-bis-[3,4-dihydroxyphenyl]-butane, 2,2′-thiobis-(4-tert-octylphenol), TEMPO, and TEMPO derivatives such as, for example, 4-hydroxy-TEMPO. A preferred polymerization inhibitor is 2,6-di-tert-butyl-4-methylphenol (BHT), which is marketed by Oxiris Chemicals SA under the trade name The amount of polymerization inhibitor present in the composition of the present invention is preferably 0.001 to 1 wt%, more preferably 0.01 to 0.5 wt%, based on the total composition.

[0047] The composition used in the method according to the invention may be obtained by any suitable method. Preferably, the composition according to the invention is obtained by the method of the invention as described below.

[0048] The process for preparing the composition according to the invention comprises at least two reaction steps (and a mixing step C),

[0049] A polyester polyol is prepared by reacting at least one organic acid comprising at least two carboxyl groups or its anhydride with at least one polyol comprising at least two hydroxyl groups, said organic acid preferably comprising 18 to 44, more preferably 24 to 44, carbon atoms,

[0050] B. reacting the polyester polyol of step A with at least one compound comprising at least one functional group reactive with the hydroxyl groups of the polyol and at least one additional functional group selected from acrylate or methacrylate groups, preferably an isocyanate compound, to obtain a reaction product having a Tg below 23°C, preferably having a Tg of from -60°C to 0°C, more preferably having a Tg of from -50°C to -20°C, and

[0051] C. Optionally, the reaction product of step B is mixed with a photoinitiator.

[0052] Process step A is preferably carried out as a melt condensation. For this purpose, the aforementioned monomers are preferably initially charged and melted in an equivalent ratio of hydroxyl groups to carboxyl groups of preferably 0.5 to 1.5, preferably 1.0 to 1.3. The polycondensation is preferably carried out in the melt at a temperature of preferably 150 to 280° C. over a period of preferably 3 to 30 hours.

[0053] It may be advantageous if the majority of the released water is initially distilled off under standard pressure. In the further course, the remaining water of reaction and volatile diols are preferably removed until the target molecular weight is reached. Optionally, this can be facilitated by reducing the pressure, by increasing the surface area, or by passing an inert gas stream through the reaction mixture.

[0054] Before or during the reaction, the esterification can be accelerated by adding an azeotrope precursor and / or a catalyst. Examples of suitable entrainer precursors are toluene and xylene. Preferred catalysts are organotitanium or organotin compounds (such as tetrabutyl titanate or dibutyltin oxide) and catalysts based on other metals such as zinc or antimony, as well as metal-free esterification catalysts.

[0055] Furthermore, it may be advantageous to add other additives and processing aids to the esterification mixture, such as antioxidants or color stabilizers.

[0056] The polyesters obtained in the esterification preferably have at least one hydroxyl and / or carboxyl end group; the functionality is preferably from 1.0 to 4.0, particularly preferably from 1.5 to 3.0.

[0057] Process step B is preferably carried out in the presence of a suitable catalyst. Suitable catalysts are, for example, organotin compounds, preferably dibutyltin dilaurate (DBTL). Process step B can be carried out with or without a solvent. Preferably, process step B is carried out in the presence of a solvent. A suitable solvent is, for example, acetone. Most preferably, acetone is used as the solvent in step B.

[0058] It may be advantageous to carry out process step B in the presence of an antioxidant / inhibitor. Preferably, the inhibitor is added to the reaction mixture together with at least one compound comprising at least one functional group reactive with the hydroxyl groups of the polyol and at least one further functional group selected from acrylate or methacrylate groups.

[0059] If a solvent is used in process step B, it is preferably removed after completion of the reaction, preferably under vacuum.

[0060] Process step C can be carried out in the usual manner. Preferably, mixing is carried out using a conventional mixing device at room temperature. A suitable mixing device is, for example, a SpeedMixer machine. Mixing is carried out for a period of time and at a speed that results in a homogeneous composition. Preferably, mixing is carried out at a speed of 500 to 5000 rpm, preferably 1200 to 2300 rpm, for 1 to 60 minutes, preferably 10 to 20 minutes. If one or more fillers and / or one or more reactive diluents are to be added to the composition, these components can be introduced together with the photoinitiator.

[0061] The composition used in the method according to the present invention can be used as a photopolymerizable material in an additive manufacturing method, preferably a 3D printing process using stereolithography. The composition used in the method according to the present invention can particularly be used as a starting material in an additive manufacturing method as described in WO 2015 / 075094 A1 or WO 2016 / 078838 A1. Therefore, one object of the present invention is a method comprising an additive manufacturing method, preferably an additive manufacturing method as described in WO 2015 / 075094 A1 or WO 2016 / 078838 A1, in which the composition of the present invention is used as a starting material.

[0062] Additive manufacturing methods, and 3D processes in particular, are generally based on the process of processing a photopolymerizable material layer by layer to produce a shaped body. In this process, a newly provided layer of photopolymerizable material is polymerized to have the desired contour in each case. By successively defining the individual contours of each layer, the desired body is formed with its three-dimensional shape resulting from the succession of produced layers.

[0063] Even without further elaboration, it is believed that one skilled in the art will be able to utilize the above description to its broadest extent. Therefore, the preferred embodiments and examples are to be construed as merely descriptive disclosures which are not limiting in any way.

[0064] The subject matter of the invention is illustrated in detail in the following examples, without intending that the subject matter of the invention be restricted thereto. Example

[0065] 1. Test method:

[0066] a) Determination of acid value:

[0067] The concentration of acid end groups is determined by titration in mg KOH / g polymer to DIN EN ISO 2114.

[0068] b) Determination of OH value (OHN):

[0069] The concentration of OH groups is determined by titration in mg KOH / g polymer according to DIN 53240-2.

[0070] c) Determination of NCO value (NCON):

[0071] The NCO value is determined in % by weight by titration in accordance with DIN EN 1242.

[0072] d) Determination of viscosity:

[0073] The viscosity of the produced polyesters and reaction products of polyesters and diisocyanates was determined in Pa·s using a rotational viscometer at the temperature specified in each case in accordance with DIN EN ISO 3219.

[0074] e) Determination of glass transition temperature Tg:

[0075] The thermal properties of the polyesters used in the context of the present invention were determined by differential scanning calorimetry (DSC) according to the DSC method DIN 53765. The values ​​for the second heating interval are indicated, and the heating rate was 10 K / min.

[0076] f) Determination of molecular weight:

[0077] The number-average molecular weight of the polyesters according to the invention is determined by gel permeation chromatography in accordance with DIN 55672-1 using tetrahydrofuran as eluent and polystyrene as calibration.

[0078] 2. Raw materials used

[0079]

[0080] IPDI–HEMA was synthesized as described in WO 2019213585 A1 by mixing 260 g of 2-hydroxyethyl methacrylate (M = 130.14 g / mol, 2 mol) and 445 g of isophorone diisocyanate (M = 222.3 g / mol, 2 mol) at 40° C. for 2 h.

[0081] IPDI–HEA was synthesized by mixing 232 g of 2-hydroxyethyl acrylate (M = 116.12 g / mol, 2 mol) and 445 g of isophorone diisocyanate (M = 222.3 g / mol, 2 mol) at 40° C. for 2 h according to the method described in WO 2019213585 A1.

[0082] 3. Synthetic method for producing polyester (step A)

[0083] a.) Polyester PE1

[0084] DFAD (3347 g, 5.8 mol), TCD-alcohol (325 g, 1.7 mol), methylpropanediol-1,3-diol (597 g, 6.6 mol), and 0.8 g of OGT were charged to a 6 L reaction flask equipped with a column and distillation top under a nitrogen stream and heated. Water began to evaporate when a temperature of 165°C was reached. The temperature was raised to 230°C within one hour. After approximately another hour at this temperature, water separation slowed. The column and distillation top were removed and replaced with a distillation bridge. The process was continued under vacuum, which was adjusted during the reaction so that distillate was still produced. The process was stopped after the desired hydroxyl and acid number ranges were reached. The properties of polyester PE1 are shown in Table 1.

[0085] b.) Polyester PE2

[0086] DFAD (3387 g, 6.0 mol), TCD-alcohol (272 g, 1.4 mol), 1,3-methylpropanediol (499 g, 5.5 mol), and 0.8 g of OGT were charged to a 6 L reaction flask equipped with a column and a distillation top under a nitrogen stream and heated. Water began to evaporate when a temperature of 165°C was reached. The temperature was raised to 230°C within one hour. After approximately another half hour at this temperature, water separation slowed. The column and distillation top were removed and replaced with a distillation bridge. The process was continued under vacuum, adjusted to maintain distillate production during the reaction. The process was stopped after the desired hydroxyl and acid number ranges were reached. The properties of polyester PE2 are shown in Table 1.

[0087] c.) Polyester PE3

[0088] DFAD (3504 g, 6.1 mol), TCD-alcohol (341 g, 1.7 mol), methylpropanediol-1,3-diol (626 g, 7.0 mol), and 0.8 g of OGT were charged to a 6 L reaction flask equipped with a column and a distillation top under a nitrogen stream and heated. Water began to evaporate when a temperature of 165°C was reached. The temperature was raised to 230°C within one hour. After approximately another half hour at this temperature, water separation slowed. The column and distillation top were removed and replaced with a distillation bridge. The process was continued under vacuum, adjusted to maintain distillate production during the reaction. The process was stopped after the desired hydroxyl and acid number ranges were reached. The properties of polyester PE3 are shown in Table 1.

[0089] d.) Polyester PE4

[0090] DFAD (3275 g, 5.7 mol), phthalic anhydride (210 g, 1.4 mol), hexanediol-1,6 (210 g, 1.8 mol), methylpropanediol-1,3 (640 g, 7.1 mol), and 0.8 g of OGT were charged to a 6 L reaction flask equipped with a column and a distillation top under a nitrogen stream and heated. Water began to evaporate when a temperature of 170°C was reached. The temperature was raised to 230°C within one hour. After approximately another hour at this temperature, water separation slowed. The column and distillation top were removed and replaced with a distillation bridge. The process was continued under vacuum, adjusted to maintain distillate production during the reaction. The process was stopped after the desired hydroxyl and acid number ranges were reached. The properties of polyester PE4 are shown in Table 1.

[0091] e.) Polyester PE5

[0092] DFAD (3176 g, 5.5 mol), phthalic anhydride (203 g, 1.4 mol), TCD-alcohol (340 g, 1.7 mol), 1,3-methylpropanediol (625 g, 6.9 mol), and 0.8 g of OGT were charged to a 6 L reaction flask equipped with a column and a distillation top under a nitrogen stream and heated. Water began to evaporate when a temperature of 165°C was reached. The temperature was raised to 230°C within one hour. After approximately another half hour at this temperature, water separation slowed. The column and distillation top were removed and replaced with a distillation bridge. The process was continued under vacuum, adjusted to maintain distillate production during the reaction. The process was stopped after the desired hydroxyl and acid number ranges were reached. The properties of polyester PE5 are shown in Table 1.

[0093] f.) Polyester PE6

[0094] DFAD (3301 g, 5.7 mol), TCD-alcohol (237 g, 1.2 mol), 1,3-methylpropanediol (435 g, 4.8 mol), trimethylolpropane (270 g, 2.0 mol), and 0.8 g of OGT were charged to a 6 L reaction flask equipped with a column and a distillation top under a nitrogen stream and heated. Water began to evaporate when a temperature of 165°C was reached. The temperature was raised to 230°C within one hour. After approximately another hour at this temperature, water separation slowed. The column and distillation top were removed and replaced with a distillation bridge. The process was continued under vacuum, with the vacuum adjusted to maintain distillate production during the reaction. The process was stopped after the desired hydroxyl and acid number ranges were reached. The properties of polyester PE6 are shown in Table 1.

[0095] g.) Polyester PE7

[0096] Adipic acid (3349 g, 22.9 mol), monoethylene glycol (778 g, 12.5 mol), neopentyl glycol (2878 g, 14.7 mol), and 0.8 g of OGT were charged to a 6 L reaction flask equipped with a column and a distillation top under a nitrogen stream and heated. Water began to evaporate when a temperature of 154°C was reached. The temperature was raised to 240°C within one hour. After approximately two more hours at this temperature, water separation slowed. The column and distillation top were removed and replaced with a distillation bridge. The process was continued under vacuum, with the vacuum adjusted during the reaction so that distillate was still produced. The process was stopped after the desired hydroxyl and acid number ranges were reached. The properties of polyester PE7 are shown in Table 1.

[0097] h.) Polyester PE8

[0098] DFAD (3434 g, 5.9 mol), TCD-alcohol (289 g, 1.5 mol), methylpropanediol-1,3-diol (531 g, 5.9 mol), and 0.8 g of OGT were charged to a 6 L reaction flask equipped with a column and a distillation top under a nitrogen stream and heated. Water began to evaporate when a temperature of 165°C was reached. The temperature was raised to 230°C within one hour. After approximately another hour at this temperature, water separation slowed. The column and distillation top were removed and replaced with a distillation bridge. The process was continued under vacuum, with the vacuum adjusted to maintain distillate production during the reaction. The process was stopped after the desired hydroxyl and acid number ranges were reached. The properties of polyester PE8 are shown in Table 1.

[0099] Table 1: Properties of the polyesters obtained in Examples 3a.) to 3h.) (Step A)

[0100]

[0101] nd: not determined

[0102] 4. Reaction with IPDI–HE(M)A (Step B)

[0103] a.) PEMA1

[0104] 428.9 g of polyester PE1 and 0.21 g of DBTL catalyst were charged into a 2 L reaction flask equipped with a stirrer, a temperature sensor and a reflux condenser in an air stream and dissolved in 286.1 g of acetone. The mixture was heated to 45°C and 167.9 g of IPDI-HEMA and 3.0 g of A solution of CP in 113.9 g of acetone was prepared. The temperature was then raised to 60°C and maintained there for 8 hours. The reaction mixture was cooled to room temperature and stirred for a further 18 hours. After reaching the desired NCO value of <0.5% (based on solids content), the process was stopped. The acetone solvent was removed under vacuum at 40°C for 100 hours. The properties of the reaction product are shown in Table 2.

[0105] b.) PEMA2

[0106] 537.0 g of polyester PE2 and 0.27 g of DBTL catalyst were charged into a 2 L reaction flask equipped with a stirrer, a temperature sensor and a reflux condenser in an air stream and dissolved in 359.2 g of acetone. The mixture was heated to 45°C and 59.75 g of IPDI-HEMA and 3.0 g of acetone were added dropwise through a dropping funnel over a period of 15 minutes. A solution of CP in 41.8 g of acetone was prepared. The temperature was then raised to 60°C and maintained there for 5 hours. The reaction mixture was cooled to room temperature and stirred for a further 16 hours. After reaching the desired NCO value of <0.5% (based on solids content), the process was stopped. The acetone solvent was removed under vacuum at 40°C for 100 hours. The properties of the reaction product are shown in Table 2.

[0107] c.) PEMA3

[0108] 562.7 g of polyester PE3 and 0.28 g of DBTL catalyst were charged into a 2 L reaction flask equipped with a stirrer, a temperature sensor and a reflux condenser in an air stream and dissolved in 563.0 g of acetone. The mixture was heated to 45°C and 34.0 g of IPDI-HEMA and 3.0 g of acetone were added dropwise through a dropping funnel over a period of 15 minutes. A solution of CP in 37.0 g of acetone was prepared. The temperature was then raised to 60°C and maintained there for 4 hours. The reaction mixture was cooled to room temperature and stirred for a further 18 hours. After reaching the desired NCO value of <0.5% (based on solids content), the process was stopped. The acetone solvent was removed under vacuum at 40°C for 100 hours. The properties of the reaction product are shown in Table 2.

[0109] d.) PEMA4

[0110] 463.5 g of polyester PE4 and 0.23 g of DBTL catalyst were charged into a 2 L reaction flask equipped with a stirrer, a temperature sensor and a reflux condenser in an air stream and dissolved in 309.0 g of acetone. The mixture was heated to 45 ° C. and 63.7 g of IPDI-HEMA and 2.7 g of A solution of CP in 42.5 g of acetone was prepared. The temperature was then raised to 60°C and maintained there for 5 hours. The reaction mixture was cooled to room temperature and stirred for a further 15 hours. After reaching the desired NCO value of <0.5% (based on solids content), the process was stopped. The acetone solvent was removed under vacuum at 40°C for 100 hours. The properties of the reaction product are shown in Table 2.

[0111] e.) PEMA5

[0112] 459.4 g of polyester PE5 and 0.23 g of DBTL catalyst were charged into a 2 L reaction flask equipped with a stirrer, a temperature sensor and a reflux condenser in an air stream and dissolved in 306.0 g of acetone. The mixture was heated to 45°C and 57.7 g of IPDI-HEMA and 2.6 g of acetone were added dropwise through a dropping funnel over a period of 30 minutes. A solution of CP in 38.5 g of acetone was prepared. The temperature was then raised to 60°C and maintained there for 4 hours. The reaction mixture was cooled to room temperature and stirred for a further 17 hours. After reaching the desired NCO value of <0.5% (based on solids content), the process was stopped. The acetone solvent was removed in vacuo at 40°C for 110 hours. The properties of the reaction product are shown in Table 2.

[0113] f) PEMA6

[0114] 392.0 g of polyester PE6 and 0.20 g of DBTL catalyst were charged to a 2 L reaction flask equipped with a stirrer, temperature sensor, and reflux condenser under air flow and dissolved in 261.3 g of acetone. The mixture was heated to 45°C, and a solution of 207.8 g of IPDI–HEMA in 138.5 g of acetone was added dropwise via a dropping funnel over 20 minutes. The temperature was then raised to 60°C and maintained there for 6 hours. The reaction mixture was cooled to room temperature and stirred for a further 64 hours. After reaching the desired NCO value of <0.5% (based on solids content), the process was stopped. The acetone solvent was removed under vacuum at 40°C for 96 hours. The characteristics of the reaction product are shown in Table 2.

[0115] g) PEMA7

[0116] 862.4 g of polyester PE7 and 0.5 g of DBTL catalyst were charged to a 2 L reaction flask equipped with a stirrer, temperature sensor, and reflux condenser under air flow and dissolved in 574.9 g of acetone. The mixture was heated to 45°C, and a solution of 137.1 g of IPDI–HEMA in 91.4 g of acetone was added dropwise via a dropping funnel over a period of 45 minutes. The temperature was then raised to 60°C and maintained there for 15 hours. After reaching the desired NCO value of <0.5% (based on solids content), the process was stopped. The acetone solvent was removed under vacuum at 40°C for 205 hours. The characteristics of the reaction product are shown in Table 2.

[0117] h) PEMA8

[0118] 492.0 g of polyester PE8 and 0.25 g of DBTL catalyst were charged into a 2 L reaction flask equipped with a stirrer, a temperature sensor and a reflux condenser in an air stream and dissolved in 328.0 g of acetone. The mixture was heated to 45°C and 104.8 g of IPDI-HEMA and 3.0 g of A solution of CP in 69.9 g of acetone was prepared. The temperature was then raised to 60°C and maintained there for 8 hours. The reaction mixture was cooled to room temperature and stirred for a further 17 hours. After reaching the desired NCO value of <0.5% (based on solids content), the process was stopped. The acetone solvent was removed under vacuum at 40°C for 100 hours. The properties of the reaction product are shown in Table 2.

[0119] i)PEA1

[0120] 430.0 g of polyester PE1 and 0.21 g of DBTL catalyst were charged into a 2 L reaction flask equipped with a stirrer, a temperature sensor and a reflux condenser in an air stream and dissolved in 286.7 g of acetone. The mixture was heated to 45°C and 163.8 g of IPDI-HEA and 6.0 g of acetone were added dropwise through a dropping funnel over a period of 45 minutes. A solution of CP in 109.2 g of acetone was prepared. The temperature was then raised to 60°C and maintained there for 12 hours. The reaction mixture was cooled to room temperature and stirred for a further 30 hours. After reaching the desired NCO value of <0.5% (based on solids content), the process was stopped. The acetone solvent was removed in vacuo at 40°C for 160 hours. The properties of the reaction product are shown in Table 2.

[0121] Table 2: Characteristics of the reaction products obtained in Examples 4a.) to 4i.) (Step B)

[0122] Example Tg[℃] Viscosity at 80°C [Pa*s] 4a.) -41 7 4b.) -49 19 4c.) -48 52 4d.) -51 5 4e.) -47 20 4f.) -30 12 4g.) -41 7 4h.) -46 6 4i.) -40 3

[0123] nd: not determined

[0124] 5.) Resin Preparation (Step C)

[0125] A mixture comprising the reaction product according to one of Examples 4a.) to 4i.), a photoinitiator ( 819), optionally at least one reactive diluent ( product series) and optionally fillers ( The compositions of the different formulations are shown in Table 3.

[0126] Table 3a: Composition of the resin formulation prepared in Example 5 in parts by weight (given in brackets)

[0127] Reaction products Photoinitiator diluent filler 5a 4a(99) I819(1) - - 5b 4a(99,5) I819(0.5) - - 5c 4a(98) I819(2) - - 5d 4h(98) I819(2) - - 5e 4h(99) I819(1) - - 5f 4f(98) I819(2) - - 5g 4f(99) I819(1) - - 5h 4c(98) I819(2) - - 5i 4c(99) I819(1) - - 5j 4b(90) I819(1) IBOMA(10) - 5k 4b(70) I819(1) IBOMA(30) - 5l 4b(50) I819(1) IBOMA(50) - 5m 4b(70) I819(1) IBOMA / TMPTMA(25) / (5) - 5n 4b(90) I819(1) GLYFOMA(10) - 5o 4b(70) I819(1) GLYFOMA(30) - 5p 4b(90) I819(1) TMCHMA(10) - 5q 4b(70) I819(1) TMCHMA(30) -

[0128] Table 3b: Composition of the resin formulation prepared in Example 5 in parts by weight (given in brackets)

[0129]

[0130] 6.) 3D Printing

[0131] The resin was then printed on a thermal lithography (SLA) machine (Cubicure Caligma 200). The temperature was adjusted according to the viscosity of the resin. The target viscosity was approximately 20 Pa.s at the printing temperature. This typically resulted in a printing temperature in the range of 30 to 100°C. The layers were 100 μm thick. At the end of the print run, the object was removed from the build platform. The parameters used are listed in Table 4.

[0132] Typical post-processing required was to wash the printed objects in pure isopropyl alcohol for 1 hour in a Formlab cleaning station. Afterwards, the printed objects were placed in a Formlab curing station, where they were irradiated with blue (405nm) light while being heated at 80°C for 2 hours.

[0133] Finally, the printed objects were tested according to standard DIN EN ISO 527 (tensile test). The results are also summarized in Tables 4a and 4b.

[0134] Table 4a: Parameters used for printing and test results of printed objects

[0135] Resin formulations Printing temperature (℃) Tensile strength (MPa) Elongation at break (%) Tg(℃) 5a 70 8 44 nd 5b 70 8 67 -36 5c 70 6 42 nd 5d 70 2 44 nd 5e 70 2 61 -42 5f 70 15 49 nd 5g 70 15 44 -26 5h 100 1.4 124 nd 5i 100 1.9 133 -44 5j 70 1.5 84 -42 5k 70 4 188 -36 5l 30 11 150(6) -34 5m 70 15 105 -39 5n 70 2 97 -44 5o 60 5 75 -45 5p 60 1 105 -43 5q 50 2 203 -35

[0136] Elongation at break (value given in brackets: yield point), nd: not determined

[0137] Table 4b: Parameters used for printing and test results of printed objects

[0138] Resin formulations Printing temperature (℃) Tensile strength (MPa) Elongation at break (%) Tg(℃) 5r 60 6 95 nd 5s 60 1.6 173 nd 5t 30 3 200 nd 5u 50 3 200 nd 5v 70 8 100 nd 5w 60 7 88 nd 5x 50 10 110 nd 5y 80 7 222 -36 5z 80 5.2 196 -36 5aa 70 6 178 -37 5ab 80 6 165 -38 5ac 60 9 180 nd 5ad 80 14 217 nd 5ae 80 10 174 nd

[0139] Elongation at break, nd: not determined

[0140] As can be seen from the examples, the highest elongation at break (>200%) is achieved with good tensile strength (7 MPa) for the highest Mn polymer (PEMA3). Tensile strength can be gained at the expense of elongation by adding crosslinkers / diluents. Viscosity increases with Mn. W increases with the increase of .

[0141] Silica, especially fumed silica treated with methacrylsilane, can increase tensile strength without significantly affecting elongation at break values.

Claims

1. An additive manufacturing method, characterized in that: A composition comprising a reaction product of a polyester polyol and a compound comprising at least one functional group capable of reacting with hydroxyl groups of the polyester polyol and at least one further functional group selected from acrylate or methacrylate groups is used as a photopolymerizable material, characterized in that the polyester polyol is based on at least one organic acid comprising at least two carboxyl groups or its anhydride and at least one polyol comprising at least two hydroxyl groups, wherein the reaction product has a glass transition temperature Tg of less than 23° C. in the second heating interval, determined according to the DSC method DIN 53765 at a heating rate of 10 K / min, and wherein the composition optionally further comprises a photoinitiator.

2. The method of claim 1, wherein the organic acid comprises two carboxyl groups.

3. The method of claim 1, wherein the organic acid comprises 4 to 44 carbon atoms. The method of claim 1 , wherein the organic acid comprises 18 to 44 carbon atoms. The method of claim 1 , wherein the organic acid comprises 24 to 44 carbon atoms.

6. The method according to claim 1, characterized in that The organic acid is a dimer acid of a fatty acid containing 12 to 22 carbon atoms or adipic acid.

7. The method according to claim 6, characterized in that The organic acid is a dimer acid of a fatty acid containing 16 to 20 carbon atoms or adipic acid.

8. The method according to claim 6, characterized in that The organic acid is a dimer acid of a fatty acid containing 18 carbon atoms or adipic acid.

9. The method according to claim 1 or 6, characterized in that The compound is an isocyanate compound comprising at least one (meth)acrylate group and at least one isocyanate group.

10. The method according to claim 9, characterized in that The isocyanate compound is a reaction product of a diisocyanate and a compound containing a hydroxyl group and a (meth)acrylate group.

11. The method according to claim 10, characterized in that The isocyanate compound is hydroxyethyl methacrylate or a reaction product of hydroxyethyl methacrylate and isophorone diisocyanate.

12. The method according to any one of claims 1 to 8, characterized in that The at least one polyol is selected from the group consisting of octahydro-4,7-methylene-1H-indenedimethanol, methylpropylene glycol-1,3, monoethylene glycol, neopentyl glycol and hexanediol-1,6.

13. The method according to any one of claims 1 to 8, characterized in that The at least one polyol is octahydro-4,7-methylene-1H-indenedimethanol, and the at least one organic acid comprising at least two carboxyl groups is adipic acid or a dimer acid of a fatty acid comprising 18 carbon atoms.

14. The method according to any one of claims 1 to 8, characterized in that The composition comprises a filler.

15. The method according to claim 14, characterized in that The composition comprises from 0.5 to 50% by weight of filler, based on the composition.

16. The method according to claim 14, characterized in that The composition comprises from 1 to 15% by weight of filler, based on the composition.

17. The method according to claim 14, characterized in that The filler is selected from inorganic particles.

18. The method according to claim 17, characterized in that The filler is selected from carbon black and silica.

19. The method according to claim 17, wherein The filler is chosen from silica functionalized with methacrylate groups.

20. The method according to any one of claims 1 to 8, characterized in that The composition comprises a further compound comprising at least one methacrylate group, wherein the compound does not comprise an isocyanate group.

21. The method according to claim 20, characterized in that The compound is present in an amount of 5 to 95 weight percent based on the total weight of the composition.

22. The method according to claim 21, characterized in that The compound is present in an amount of 10 to 50 weight percent based on the total weight of the composition.

23. The method according to any one of claims 1 to 8, characterized in that The reaction product has a Tg of -60°C to 0°C.

24. The method according to claim 23, wherein The reaction product has a Tg of -50°C to -20°C.

25. The method according to any one of claims 1 to 8, characterized in that The composition is obtained by a process comprising at least two reaction steps: A preparing a polyester polyol by reacting at least one organic acid comprising at least two carboxyl groups or anhydride thereof with at least one polyol comprising at least two hydroxyl groups, B. reacting the polyester polyol of step A with at least one compound comprising at least one functional group reactive with the hydroxyl groups of the polyester polyol and at least one additional functional group selected from acrylate or methacrylate groups to obtain a reaction product having a Tg of less than 23°C, and C. Optionally, the reaction product of step B is mixed with a photoinitiator.

26. The method according to claim 25, wherein Step A: the organic acid contains 18 to 44 carbon atoms, Step B: The reaction product has a Tg of -60°C to 0°C.

27. The method of claim 25, wherein Step A: the organic acid contains 24 to 44 carbon atoms, Step B: The reaction product has a Tg of -50°C to -20°C.

28. The method according to any one of claims 1 to 8, characterized in that The additive manufacturing method is a 3D printing process using light.

29. The method of claim 28, wherein the additive manufacturing method is a 3D printing process using stereolithography.

30. The method of claim 28, wherein the additive manufacturing method is a 3D printing process using digital light processing or irradiation with LCD.

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