Polyester-containing compositions for additive manufacturing processes

Abstract

The present invention provides A polyester polyol, a compound comprising at least one functional group capable of reacting with the hydroxyl groups of the polyester polyol and at least one other functional group selected from an acrylate group or a methacrylate group; an additive manufacturing method using a composition comprising the reaction product of the formula (1) as a photopolymerizable material, The polyester polyols are based on at least one organic acid containing at least two carboxyl groups, or an anhydride thereof, and at least one polyol containing at least two hydroxyl groups; the reaction product has a glass transition temperature (Tg) of less than 23°C; The composition relates to additive manufacturing processes and optionally further comprises a photoinitiator.

Description

[Technical field]

[0001] The present invention relates to A polyester polyol; a compound comprising at least one functional group capable of reacting with a hydroxyl group of the polyester polyol and at least one other functional group selected from an acrylate group or a methacrylate group; A method for additive manufacturing, comprising the step of: The polyester polyols are based on at least one organic acid containing at least two carboxyl groups, or anhydrides thereof, and at least one polyol containing at least two hydroxyl groups; The reaction product has a glass transition temperature (Tg) of less than 23° C. The composition relates to additive manufacturing processes and optionally further comprises a photoinitiator. [Background technology]

[0002] Lithography-based additive manufacturing methods such as stereolithography, as well as 3D printing in general, have traditionally been used primarily for the creation of prototypes and functional patterns ("rapid prototyping"). As a result of technological advances, their application in real production, such as transparent braces and hearing aid shells, is becoming increasingly important. For this application, the mechanical and thermal properties of the printing material are of great importance. However, the materials currently available for additive manufacturing do not yet have the mechanical properties of traditional building materials (e.g., Non-Patent Document 1).

[0003] These materials (resins) for lithographic additive manufacturing are based on reactive components that can be cured by exposure to light, for which radical polymerization (e.g. in the case of acrylates) or cationic polymerization (e.g. in the case of epoxides) is frequently used. For this purpose, special photoinitiators are added to the resins, which change their state by exposure to light and cause the polymerization of the reactive components.

[0004] To additively manufacture objects from these resins, various methods are available, such as stereolithography, digital light processing, and multijet modeling. In all cases, these resins are cured layer by layer to create three-dimensional objects. In principle, resins with low viscosity (for example, 20-40 mPa·s) are required (see Non-Patent Document 2). To improve the mechanical properties of the products thus cured, especially the toughness and elongation at break, it is necessary to either reduce the crosslink density or increase the molecular weight of the monomer. However, doing so increases the viscosity or the melting point of the uncured resin, the latter of which made it impossible to cure them using additive manufacturing methods until recently.

[0005] However, new developments are enabling the processing of higher viscosity resins. For example, US Pat. No. 5,399,663 and US Pat. No. 5,499,626 disclose stereolithography apparatus that can heat successively cured layers of polymerizable material, making it possible to process even high viscosity resins. US Pat. No. 5,499,626 discloses photopolymerizable compositions having a viscosity of at least 20 Pa·s at room temperature, which are heated to at least 30° C. during curing. By way of comparison, 20 Pa·s corresponds roughly to the viscosity of ethylene glycol or viscous honey, while butter, with a viscosity of about 30 Pa·s, barely flows.

[0006] However, challenges remain regarding the mechanical properties of cured products, such as 3D printed parts: For example, such products have insufficient impact strength and ductility, are too brittle, and absorb too much moisture from the surrounding air.

[0007] Patent document 4 discloses radiation and thermal crosslinking curable polyurethane systems and their use for producing holographic media. The polyurethane composition contains A) a polyisocyanate, B) a polyol including at least one poly(ε-caprolactone)-polyester polyol, C) a compound having a group that reacts with an ethylenically unsaturated compound in polymerization under exposure to actinic radiation, D) optionally a radical stabilizer, and E) a photopolymerization initiator. The polycaprolactone polyols contained preferably have a molecular weight of 500 to 2000 g / mol and function as "building blocks of the matrix polymer". That is, they undergo polyaddition with the polyisocyanate to give the desired polyurethane.

[0008] Patent document 5 describes an improved photocurable composition for the generative modeling process of additive manufacturing. 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 photopolymerization initiator, where polycaprolactone or a derivative thereof is used as the dissolved thermoplastic polymer.

[0009] Patent Document 6 describes a hardenable composition for use in high temperature lithography-based photopolymerization processes, a method for producing a crosslinked polymer using the hardenable composition, the crosslinked polymer thus produced, and an orthodontic appliance made of the crosslinked polymer. The hardenable composition contains a so-called toughness modifier, preferably containing (poly)carbonate and (poly)urethane groups.

[0010] Patent Document 7 describes a hardenable composition for use in high temperature lithography-based photopolymerization processes, a method for producing a crosslinked polymer using the hardenable composition, the crosslinked polymer so produced, and an orthodontic appliance comprising the crosslinked polymer. The hardenable composition contains a 2-, 3-, or 4-(meth)acryloxybenzoic acid ester-based monomer as a novel polymerizable monomer. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] International Publication No. 2015 / 075094A1 [Patent Document 2] International Publication No. 2016 / 078838A1 [Patent Document 3] International Publication No. 2015 / 074088A2 [Patent Document 4] International Publication No. 2008 / 125202A1 [Patent Document 5] International Publication No. 2018 / 197677A1 [Patent Document 6] International Publication No. 2019 / 213585A1 [Patent Document 7] International Publication No. 2019 / 213588A1 [Non-patent literature]

[0012] [Non-Patent Document 1] 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 Rapid Technology 2014(1) [Non-Patent Document 2] I. Gibson, DW Rosen, B. Stucker et al., Additive Manufacturing Technologies, Vol. 238, Springer Verlag (2010) Summary of the Invention [Problem to be solved by the invention]

[0013] The problem which the present invention aims to solve was to provide a composition which is photocurable and which exhibits good properties, in particular with regard to tensile strength and elongation at break. [Means for solving the problem]

[0014] Surprisingly, it has been found that this problem is solved by the compositions claimed.

[0015] Therefore, the objective is to: A polyester polyol; a compound comprising at least one functional group capable of reacting with a hydroxyl group of the polyester polyol and at least one other functional group selected from an acrylate group or a methacrylate group; A method for additive manufacturing, comprising the step of: The polyester polyols are based on at least one organic acid containing at least two carboxyl groups, or anhydrides thereof, and at least one polyol containing at least two hydroxyl groups; The composition may further comprise a photoinitiator, if desired, for use in an additive manufacturing process. This is achieved by the present invention which provides:

[0016] The compositions used in the present invention have the advantage that they can be processed at temperatures below 120° C., preferably below 100° C., since the viscosity of the composition at the processing temperature is preferably below 20 Pa·s.

[0017] The compositions used in the present invention have the advantage that they preferably do not contain any solvents, therefore no organic volatiles are produced during the additive manufacturing process.

[0018] The compositions used in the present invention have the further advantage that they can be prepared in a simple manner.

[0019] The compositions used in the present invention have the advantage that they can contain fillers which provide better properties, particularly better tensile strength and elongation at break.

[0020] The composition used in the present invention comprises a polymer (reaction product) with a low glass transition temperature (Tg), which has the further advantage that its use allows elastomers or products to be obtained by additive manufacturing processes having one or more properties typical of elastomers, such as an elongation at break of preferably more than 40%, more preferably more than 60% and most preferably more than 100%.

[0021] The compositions, methods and uses according to the present invention are illustrated by the following examples, without intending that the present invention is limited to these exemplary embodiments. When ranges, general formulas or compound groups are specified below, they are intended to encompass not only the corresponding ranges or compound groups explicitly mentioned, but also all subranges or subcompound groups obtained by excluding the individual values ​​(ranges) or compounds. When documents are cited in the context of this specification, their contents shall fully form part of the disclosure of the present invention, with particular reference to the matter referred to. The percentages specified below are by weight, unless otherwise stated. When average values ​​are reported below, these are numerical averages, unless otherwise stated. When material properties (e.g. viscosity, etc.) are referred to below, these are material properties at 25°C, unless otherwise stated. When chemical formulas (empirical formulas) are used herein, the specified indices may be average values ​​as well as absolute numbers.

[0022] The additive manufacturing process of the present invention comprises: A polyester polyol; a compound comprising at least one functional group capable of reacting with a hydroxyl group of the polyester polyol and at least one other functional group selected from an acrylate group or a methacrylate group; The present invention is characterized in that a composition comprising the reaction product of the above is used as a photopolymerizable material, The polyester polyols are based on at least one organic acid or anhydride containing at least two carboxyl groups, preferably having 4 to 44, more preferably 18 to 44, most preferably 24 to 44 carbon atoms, and at least one polyol containing at least two hydroxyl groups, The reaction product has a glass transition temperature (Tg) of less than 23°C, preferably from -60°C to 0°C, more preferably from -50°C to -20°C; The composition optionally further comprises a photopolymerization initiator.

[0023] Preferably, the polyester polyols are based on dicarboxylic acids, more preferably aliphatic dicarboxylic acids, and most preferably acyclic aliphatic dicarboxylic acids.

[0024] The polyester polyols of the present invention preferably do not contain any carbonate groups (e.g., groups of the formula -OC(O)-O-), and most preferably do not contain any carbonic acid groups and are based on dicarboxylic acids, more preferably aliphatic dicarboxylic acids, and most preferably acyclic aliphatic dicarboxylic acids.

[0025] The organic acid, or anhydride thereof, containing at least two carboxyl groups, preferably two carboxyl groups, is preferably a dimeric fatty acid (also known as dimerized fatty acid or dimer acid). These dimeric fatty acids are mixtures prepared by oligomerization of unsaturated fatty acids. The starting materials that can be used preferably include unsaturated C 12 ~C 22 fatty acids. C, used in the preparation of dimeric fatty acids 12 ~C 22Depending on the number and position of the double bonds in the fatty acid, the carboxyl groups of the dimeric fatty acids are linked together by hydrocarbon radicals, mainly having 24 to 44 carbon atoms. These hydrocarbon radicals are generally branched and may contain C6 alicyclic or C6 aromatic hydrocarbon radicals that are double-bonded. These alicyclic and / or aromatic radicals may be linked.

[0026] The radicals linking the carboxyl groups of the dimer fatty acids preferably have no aromatic hydrocarbon radicals, and very preferably have no unsaturated bonds and no aromatic hydrocarbon radicals.

[0027] Preferably, the organic acid is a dimer acid of a fatty acid having 12 to 22, preferably 16 to 20, and most preferably 18 carbon atoms. In the present invention, C 18 It is preferred to use fatty acids. Particularly preferred are C 18 The use of fatty acids, highly preferred is the use of linolenic acid, linoleic acid and / or oleic acid.

[0028] Depending on the reaction regime, the oligomerization may produce a mixture containing mainly dimeric molecules, but also trimeric and monomeric molecules, as well as other by-products. Purification can generally be carried out distillatively. Commercially available dimeric fatty acids preferably contain at least 80% by weight of dimeric molecules, at most 19% by weight of trimeric molecules, and up to 1% by weight of monomeric molecules and other by-products.

[0029] For the purposes of the present invention, it is preferred to use dimeric fatty acids consisting of 90% by weight or more of dimeric molecules, 5% by weight or less of trimer molecules, 5% by weight or less of monomeric molecules and other by-products. It is particularly preferred to use dimeric fatty acids consisting of 95-98% by weight of dimeric molecules, less than 5% by weight of trimer molecules, less than 1% by weight of monomeric molecules and other by-products. Similarly, it is particularly preferred to use dimeric fatty acids consisting of 98% by weight or more of dimeric molecules, 1.5% by weight or less of trimer molecules, 0.5% by weight or less of monomeric molecules and other by-products.

[0030] Depending on the reaction regime, dimeric fatty acids contain both aliphatic and aromatic molecular fragments. The aliphatic molecular fragments can be further divided into linear and cyclic fragments, which in turn can be saturated or unsaturated. Hydrogenation can convert the aromatic and unsaturated aliphatic molecular fragments into the corresponding saturated aliphatic molecular fragments.

[0031] Preferred dimeric fatty acids that can be used in the present invention are, for example, Radiacid® 0970, Radiacid® 0971, Radiacid® 0972, Radiacid® 0975, Radiacid® 0976, and Radiacid® 0977 from Oleon, Pripol 1006, Pripol 1009, Pripol 1012, and Pripol 1013 from Unichema, Empol® 1008, Empol® 1061, and Empol® 1062 from BASF, and Unidyme® 10 and Unidyme® TI from Arizona Chemical.

[0032] Instead of using dimeric fatty acids as organic acids containing at least two carboxyl groups or their anhydrides, it may be advantageous to use aliphatic dicarboxylic acids having 4 to 10, preferably 6 to 8, carbon atoms. Most preferably, hexanedioic acid (adipic acid) is used as the aliphatic dicarboxylic acid.

[0033] The at least one polyol is preferably selected from the group consisting of octahydro-4,7-methano-1H-indene dimethanol, methylpropanediol-1,3, monoethylene glycol, neopentyl glycol, and hexanediol-1,6.

[0034] It is particularly preferred when at least one of the at least one polyol is octahydro-4,7-methano-1H-indenedimethanol and at least one of the at least one organic acid containing at least two carboxyl groups is a dimer acid of a fatty acid having 18 carbon atoms, or preferably adipic acid.

[0035] The polyester polyols present in the composition according to the invention can be obtained by esterification methods known in the art. Preferably, the polyester polyols are obtained using a method as described below as step A) of the process according to the invention.

[0036] The concentration of acid end groups in the polyester polyols, measured in accordance with DIN EN ISO 2114, is preferably between 0 and 10 mg KOH / g, but is preferably less than 2 mg KOH / g.

[0037] The number-average molecular weight of the polyester polyols used according to the invention is preferably 1,000 to 20,000 g / mol, preferably 3,000 to 10,000 g / mol, determined by gel permeation chromatography in accordance with DIN 55672-1 with tetrahydrofuran as eluent and polystyrene for calibration.

[0038] The compound comprising at least one functional group capable of reacting with the hydroxyl group of the polyester polyol and at least one other functional group selected from an acrylate group or a methacrylate group is preferably an isocyanate compound comprising at least one (meth)acrylate group and at least one isocyanate group. More preferably, the isocyanate compound is - reaction products of diisocyanates with compounds containing hydroxyl groups and (meth)acrylate groups, - preferably a reaction product of hydroxyethyl methacrylate or hydroxyethyl acrylate with isophorone diisocyanate (IPDI), with one or more trimethyl-1,6-hexane diisocyanates (TMDI), with 4,4'-dicyclohexylmethane diisocyanate (H12MDI) or with hexamethylene diisocyanate (HDI), Most preferably, the reaction products of hydroxyethyl methacrylate or hydroxyethyl acrylate with isophorone diisocyanate (IPDI). It is.

[0039] Isocyanate compounds containing at least one (meth)acrylate group and at least one isocyanate group can be prepared, for example, as described in WO 2010 / 115644 A1 or WO 2010 / 115644 A1.

[0040] The compositions used according to the present invention may include additional components. It may be advantageous to have one or more photoinitiators present in the compositions of the present invention. Photoinitiators are preferably molecules that generate reactive species, e.g., free radicals, cations, or anions when exposed to radiation (UV or visible light). Examples of any suitable photoinitiators, including type I and type II photoinitiators and commonly used UV photoinitiators, include, but are not limited to, acetophenone (e.g., diethoxyacetophenone), phosphine oxides, diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide, phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide (PPO), Irgacure 369, and the like (see, e.g., U.S. Patent No. 9,453,142 to Rolland et al.). These may be present in the compositions of the present invention. Preferred photoinitiators according to the present invention are those that generate free radicals. The most preferred photoinitiator is bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, available under the trade name OMNIRAD® 819 from IGM resins (previously known as IRGACURE® 819 from BASF SE). Other photoinitiators that can be used in the compositions of the present invention are available under the trade names OMNIRAD® TPO and OMNIRAD® TPO-L from IGM resins. The amount of photoinitiator present in the compositions of the present invention is preferably 0.1-5 wt. %, more preferably 0.5-2 wt. %, and most preferably 0.8-1.2 wt. %, based on the total composition.

[0041] The compositions used according to the invention may have solid particles suspended or dispersed therein. Any suitable solid particles may be used depending on the final product to be produced. The particles may be metallic, organic / polymeric, inorganic, or composites or mixtures thereof. The particles may be non-conductive, semi-conductive, or conductive (such as metallic and non-metallic or polymeric conductors). The particles may be magnetic, ferromagnetic, paramagnetic, or non-magnetic. The particles may be of any suitable shape, such as spherical, ellipsoidal, cylindrical, etc. The particles may be of any suitable size (e.g., average diameter ranging from 1 nm to 200 μm).

[0042] The particles may include active agents and detectable compounds, which may also be dissolved / solubilized in the compositions of the invention. For example, magnetic or paramagnetic particles or nanoparticles may be used.

[0043] The compositions used in the methods of the invention can have additional components mixed or solubilized in the composition, such as pigments, dyes, active or medicinal compounds, detectable compounds (e.g., fluorescent materials, phosphorescent materials, radioactive materials), etc., depending on the particular purpose of the product being manufactured.

[0044] It may be advantageous for the compositions used in the methods of the present invention to include 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., present in an amount of 0.05 or 0.1 to 1 or 5% by weight), (ii) carbon black (e.g., present in an amount of 0.05 or 0.1 to 1 or 5% by weight), and / or organic UV absorbers such as hydroxybenzophenones, hydroxyphenylbenzotriazoles, oxanilides, benzophenones, thioxanthones, hydroxyphenyltriazines, and / or benzotriazole UV absorbers (e.g., Mayzo BLS1326) (e.g., present in an amount of 0.001 or 0.005 to 1, 2 or 4% by weight). Examples of suitable organic UV absorbers include, but are not limited to, those described in U.S. Patent No. 3,213,058, U.S. Patent No. 6,916,867, U.S. Patent No. 7,157,586, and U.S. Patent No. 7,695,643, the disclosures of which are incorporated herein by reference.

[0045] The composition used in the method of the present invention may contain any suitable filler depending on the properties desired for the part or article to be manufactured. Thus, the filler may be solid or liquid, organic or inorganic. Fillers may include reactive and non-reactive rubbers (siloxanes, acrylonitrile-butadiene rubbers), reactive and non-reactive thermoplastics (such as, but not limited to, poly(etherimides), maleimide-styrene terpolymers, polyaryl acid salts, polysulfones, and polyethersulfones), inorganic fillers such as silicates (e.g., talc, clay, silica, mica), glass, carbon nanotubes, graphene, cellulose nanocrystals, and combinations of all of the above. Suitable fillers are toughening agents such as core-shell rubbers.

[0046] The composition used in the method according to the invention preferably comprises one or more fillers, more preferably 0.5 to 50% by weight, preferably 1 to 15% by weight, of the composition. The fillers are preferably selected from inorganic particles, more preferably from carbon black and / or silica. Most preferably, silica functionalized with methacrylate groups is present in the composition according to the invention as filler. Suitable silica functionalized with methacrylate groups is available, for example, under the trade name AEROSIL® 701 or 711 from Evonik Industries AG (Evonik Resource Efficiency GmbH).

[0047] It may be advantageous for the composition used in the method of the invention to contain another compound that contains at least one methacrylate group and does not contain an isocyanate group or another functional group. The other compound can be used as a reactive diluent and / or crosslinker. 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, those sold by Evonik Industries AG under the VISIOMER® product line. Preferred compounds are glycerol formal methacrylate (VISIOMER® Glyfoma), diurethane dimethacrylate (VISIOMER® HEMA TMDI), butyl diglycol methacrylate (VISIOMER® BDGMA), polyethylene glycol 200 dimethacrylate (VISIOMER® PEG200DMA), trimethylolpropane methacrylate (VISIOMER® TMPTMA) or isobornyl methacrylate (VISIOMER® Terra IBOMA). Most preferably, the composition of the invention comprises isobornyl methacrylate (VISIOMER® Terra IBOMA) as another compound containing at least one methacrylate group and not containing an isocyanate group or another functional group, preferably in an amount of 10 to 50% by weight relative to the total weight of the composition.

[0048] The composition used in the method according to the invention preferably comprises a polymerization inhibitor and / or an antioxidant. The use of a polymerization inhibitor and / or an antioxidant can prevent the composition from polymerizing before it is used in the additive manufacturing process. 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-butylbenzol, 4-methoxy-2(3)-tert-butylphenol (BHA), BHA in combination with 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, 4-hydroxy-3,5-di-tert-butylphenyl methanesulfonic acid-dioctadecyl ester, 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, TEMPO derivatives (e.g. 4-hydroxy-TEMPO). A preferred polymerization inhibitor is 2,6-di-tert-butyl-4-methylphenol (BHT), sold under the name IONOL® CP by Oxiris Chemicals SA. The amount of the polymerization inhibitor present in the composition of the present invention is preferably 0.001 to 1% by weight, more preferably 0.01 to 0.5% by weight, based on the total composition.

[0049] 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 according to the invention described below.

[0050] The process for preparing the composition according to the present invention comprises at least the two following reaction steps (and a mixing step C)). A) preparing a polyester polyol by reacting at least one organic acid containing at least two carboxyl groups, preferably having 18 to 44, more preferably 24 to 44 carbon atoms, or anhydride thereof, with at least one polyol containing at least two hydroxyl groups; B) reacting the polyester polyol of step A) with at least one compound, preferably an isocyanate compound, comprising at least one functional group capable of reacting with a hydroxyl group of the polyester polyol and at least one other functional group selected from an acrylate group or a methacrylate group, to obtain a reaction product having a glass transition temperature (Tg) of less than 23°C, preferably between -60°C and 0°C, more preferably between -50°C and -20°C; and C) optionally mixing the reaction product of step B) with a photoinitiator.

[0051] Step A is preferably carried out as a melt condensation. For this purpose, the above monomers are first preferably charged and melted at an equivalent ratio of hydroxyl groups to carboxyl groups of 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., preferably for 3 to 30 hours.

[0052] It may be advantageous to first distill off most of the water discharged at standard pressure. In a further step, it is preferable to remove the remaining water of reaction and the volatile diol until the target molecular weight is reached. In some cases, this can be facilitated by reducing the pressure, by increasing the surface area, or by passing a stream of inert gas through the reaction mixture.

[0053] The esterification can be further promoted by adding an azeotrope former and / or catalyst before or during the reaction. Examples of suitable azeotrope formers are toluene and xylene. Preferred catalysts are organotitanium or organotin compounds such as tetrabutyl titanate or dibutyltin oxide, catalysts based on other metals such as zinc or antimony, and metal-free esterification catalysts.

[0054] Additionally, it may be advantageous to add further additives and processing aids to the esterification mixture, such as antioxidants or color stabilizers.

[0055] The polyester obtained by esterification preferably has at least one hydroxyl and / or carboxyl end group and a functionality of preferably 1.0 to 4.0, particularly preferably 1.5 to 3.0.

[0056] Step B is preferably carried out in the presence of a suitable catalyst. Suitable catalysts are, for example, organotin compounds, preferably dibutyltin dilaurate (DBTL). Step B may be carried out in the presence or absence of a solvent. Preferably, step B is carried out in the presence of a solvent. Suitable solvents are, for example, acetone. Most preferably, acetone is used as the solvent for step B.

[0057] It may be advantageous to carry out step B in the presence of an antioxidant / polymerization inhibitor. Preferably, the inhibitor is added to the reaction mixture together with at least one compound comprising at least one functional group capable of reacting with the hydroxyl group of the polyol and at least one other functional group selected from an acrylate or methacrylate group.

[0058] If a solvent is used in step B, it is preferred that the solvent be removed, preferably under vacuum, after the reaction is complete.

[0059] Step C can be carried out in a conventional manner. Preferably, mixing is carried out at room temperature using conventional mixing equipment. A suitable mixing equipment is, for example, a SpeedMixer machine. Mixing is carried out for a period and speed that results in a homogeneous composition. Preferably, mixing is carried out at a speed of 500-5000 rpm, preferably 1200-2300 rpm, for 1-60 minutes, preferably 10-20 minutes. If fillers and / or reactive diluents need to be added to the composition, these components can be introduced together with the photoinitiator.

[0060] The composition used in the method according to the invention can be used as a photopolymerizable material in an additive manufacturing process, preferably in a 3D printing process using stereolithography. The composition used in the method according to the invention can be applied as a raw material in the additive manufacturing process described in WO 2005 / 023636 or WO 2005 / 023666. The object of the invention is therefore a method comprising an additive manufacturing process, preferably an additive manufacturing process described in WO 2005 / 023666 or WO 2005 / 023666, in which the composition according to the invention is applied as a raw material.

[0061] In general, additive manufacturing methods, and in particular 3D methods, are based on the following technology: A photopolymerizable material is processed layer by layer to produce a moulded body. In this process, a freshly applied layer of photopolymerizable material is polymerized in each case with the desired contour. The desired object is formed in three-dimensional form by the succession of produced layers, with the individual contours of each layer being successively defined.

[0062] Without further explanation, a person skilled in the art can utilize the above description in the broadest possible manner. Therefore, the preferred embodiments and examples should be interpreted merely as an explanatory disclosure and are in no way limiting.

[0063] The subject matter of the present invention is explained in more detail in the following examples, but it is not intended that the subject matter of the present invention is limited thereto. EXAMPLES

[0064] 1. Test Method a) Acid value measurement The concentration of acid end groups is determined by titration of the polymer in accordance with DIN EN ISO 2114 (mg KOH / g). b) Measurement of OH value (OHN) The concentration of OH groups is determined by titration of the polymer in accordance with DIN 53240-2 (mg KOH / g). c) Measurement of NCO value (NCON) The NCO number was determined titrimetrically in accordance with DIN EN 1242 (% by weight). d) Viscosity measurement The viscosity of the polyesters produced and of the reaction products of polyesters with diisocyanates was determined in each case in accordance with DIN EN ISO 3219 using a rotational viscometer at the specified temperature (Pa·s). e) Measurement of glass transition temperature (Tg) The thermal properties of the polyesters used in the context of this specification are measured by differential scanning calorimetry (DSC) in accordance with the DSC method DIN 53765. Values ​​are given for the second heating interval, the heating rate was 10 K / min. f) Molecular weight measurement The number-average molecular weights of the polyesters according to the invention are determined by gel permeation chromatography in accordance with DIN 55672-1 with tetrahydrofuran as eluent and polystyrene for calibration.

[0065] 2. Raw materials used

[0066] [Table 0]

[0067] As described in Patent Document 6, IPDI-HEMA was synthesized 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 hours. As described in Patent Document 6, IPDI-HEA was synthesized by mixing 232 g (M = 116.12 g / mol, 2 mol) of 2-hydroxyethyl acrylate and 445 g (M = 222.3 g / mol, 2 mol) of isophorone diisocyanate at 40°C for 2 hours.

[0068] 3. Synthetic Method for Producing Polyester (Step A) a) Polyester PE1 DFAD (3347 g, 5.8 mol), TCD-alcohol (325 g, 1.7 mol), methylpropanediol-1,3 (597 g, 6.6 mol), and 0.8 g OGT were placed in a 6 L reaction flask equipped with a column and distillation top, under nitrogen flow, and heated. Upon reaching a temperature of 165°C, water began to distill. Within an hour the temperature rose to 230°C. After approximately another hour at this temperature, separation of water slowed. The column and distillation top were removed and replaced with a distillation bridge. The process continued under vacuum, adjusting the vacuum during the reaction so that more distillate was produced. After reaching the desired hydroxyl number and acid number ranges, the process was stopped. The properties of polyester PE1 are shown in Table 1.

[0069] b) Polyester PE2 DFAD (3387 g, 6.0 mol), TCD-alcohol (272 g, 1.4 mol), methylpropanediol-1,3 (499 g, 5.5 mol), and OGT (0.8 g) were placed in a 6 L reaction flask equipped with a column and distillation top under a nitrogen flow and heated. Upon reaching a temperature of 165°C, water began to distill. Within an hour the temperature increased to 230°C. After approximately another hour and a half at this temperature, the separation of water slowed. The column and distillation top were removed and replaced with a distillation bridge. The process continued under vacuum, adjusting the vacuum during the reaction so that more distillate was produced. After reaching the desired hydroxyl number and acid number ranges, the process was stopped. The properties of polyester PE2 are shown in Table 1.

[0070] c) Polyester PE3 DFAD (3504 g, 6.1 mol), TCD-alcohol (341 g, 1.7 mol), methylpropanediol-1,3 (626 g, 7.0 mol), and OGT (0.8 g) were placed in a 6 L reaction flask equipped with a column and distillation top under nitrogen flow and heated. Upon reaching a temperature of 165°C, water began to distill. Within an hour the temperature increased to 230°C. After approximately another hour and a half at this temperature, the separation of water slowed. The column and distillation top were removed and replaced with a distillation bridge. The process continued under vacuum, adjusting the vacuum during the reaction so that more distillate was produced. After reaching the desired hydroxyl number and acid number ranges, the process was stopped. The properties of polyester PE3 are shown in Table 1.

[0071] d) Polyester PE4 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 OGT (0.8 g) were placed in a 6 L reaction flask equipped with a column and distillation top, under nitrogen flow, and heated. Upon reaching a temperature of 170 °C, water began to distill. Within an hour, the temperature increased to 230 °C. After approximately another hour at this temperature, separation of water slowed. The column and distillation top were removed and replaced with a distillation bridge. The process continued under vacuum, adjusting the vacuum during the reaction so that more distillate was produced. After reaching the desired hydroxyl number and acid number ranges, the process was stopped. The properties of polyester PE4 are shown in Table 1.

[0072] e) Polyester PE5 DFAD (3176 g, 5.5 mol), phthalic anhydride (203 g, 1.4 mol), TCD-alcohol (340 g, 1.7 mol), methylpropanediol-1,3 (625 g, 6.9 mol), and OGT (0.8 g) were placed in a 6 L reaction flask equipped with a column and distillation top, under nitrogen flow, and heated. Upon reaching a temperature of 165°C, water began to distill. Within an hour the temperature rose to 230°C. After approximately another hour and a half at this temperature, separation of water slowed. The column and distillation top were removed and replaced with a distillation bridge. The process continued under vacuum, adjusting the vacuum during the reaction so that more distillate was produced. After reaching the desired hydroxyl number and acid number ranges, the process was stopped. The properties of polyester PE5 are shown in Table 1.

[0073] f) Polyester PE6 DFAD (3301 g, 5.7 moles), TCD-alcohol (237 g, 1.2 moles), methylpropanediol-1,3 (435 g, 4.8 moles), trimethylolpropane (270 g, 2.0 moles), and OGT (0.8 g) were placed in a 6 L reaction flask equipped with a column and distillation top, under a nitrogen flow, and heated. Upon reaching a temperature of 165°C, water began to distill. Within an hour the temperature increased to 230°C. After approximately another hour at this temperature, separation of water slowed. The column and distillation top were removed and replaced with a distillation bridge. The process continued under vacuum, adjusting the vacuum during the reaction so that more distillate was produced. After reaching the desired hydroxyl number and acid number ranges, the process was stopped. The properties of polyester PE6 are shown in Table 1.

[0074] g) Polyester PE7 Adipic acid (3349 g, 22.9 moles), monoethylene glycol (778 g, 12.5 moles), neopentyl glycol (2878 g, 14.7 moles), and OGT (0.8 g) were placed in a 6 L reaction flask equipped with a column and distillation top under a nitrogen flow and heated. Upon reaching a temperature of 154°C, water began to distill. Within an hour the temperature rose to 240°C. After approximately another 2 hours at this temperature, separation of water slowed. The column and distillation top were removed and replaced with a distillation bridge. The process continued under vacuum, adjusting the vacuum during the reaction so that more distillate was produced. After reaching the desired hydroxyl number and acid number ranges, the process was stopped. The properties of polyester PE7 are shown in Table 1.

[0075] h) Polyester PE8 DFAD (3434 g, 5.9 mol), TCD-alcohol (289 g, 1.5 mol), methylpropanediol-1,3 (531 g, 5.9 mol), and OGT (0.8 g) were placed in a 6 L reaction flask equipped with a column and distillation top, under a nitrogen flow, and heated. Upon reaching a temperature of 165°C, water began to distill. Within an hour the temperature increased to 230°C. After approximately another hour at this temperature, separation of water slowed. The column and distillation top were removed and replaced with a distillation bridge. The process continued under vacuum, adjusting the vacuum during the reaction so that more distillate was produced. After reaching the desired hydroxyl number and acid number ranges, the process was stopped. The properties of polyester PE8 are shown in Table 1.

[0076] [Table 1]

[0077] 4. Reaction with IPDI-HE(M)A (Step B) a) PEMA1 Polyester PE1 (428.9 g) and DBTL catalyst (0.21 g) were dissolved in acetone (286.1 g) in a 2 L reaction flask equipped with a stirrer, temperature sensor and reflux condenser in an air stream. The mixture was heated to 45° C. and a solution of IPDI-HEMA (167.9 g) and IONOL® CP (3.0 g) in acetone (113.9 g) was added dropwise using a dropping funnel over 45 min. The temperature was then raised to 60° C. and held for 8 h. The reaction mixture was cooled to room temperature and stirred for an additional 18 h. The process was stopped when the desired NCO value (on solids) of less than 0.5% was reached. The acetone solvent was removed under vacuum at 40° C. for 100 h. The properties of the reaction product are shown in Table 2.

[0078] b) PEMA2 Polyester PE2 (537.0 g) and DBTL catalyst (0.27 g) were dissolved in acetone (359.2 g) in a 2 L reaction flask equipped with a stirrer, temperature sensor and reflux condenser in an air stream. The mixture was heated to 45° C. and a solution of IPDI-HEMA (59.75 g) and IONOL® CP (3.0 g) in acetone (41.8 g) was added dropwise using a dropping funnel over 15 min. The temperature was then increased to 60° C. and held for 5 h. The reaction mixture was cooled to room temperature and stirred for an additional 16 h. The process was stopped when the desired NCO value (on solids) of less than 0.5% was reached. The acetone solvent was removed under vacuum at 40° C. for 100 h. The properties of the reaction product are shown in Table 2.

[0079] c) PEMA3 Polyester PE3 (562.7 g) and DBTL catalyst (0.28 g) were dissolved in acetone (563.0 g) in a 2 L reaction flask equipped with a stirrer, temperature sensor and reflux condenser in an air stream. The mixture was heated to 45° C. and a solution of IPDI-HEMA (34.0 g) and IONOL® CP (3.0 g) in acetone (37.0 g) was added dropwise using a dropping funnel over 15 min. The temperature was then increased to 60° C. and held for 4 h. The reaction mixture was cooled to room temperature and stirred for an additional 18 h. The process was stopped when the desired NCO value (on solids) of less than 0.5% was reached. The acetone solvent was removed under vacuum at 40° C. for 100 h. The properties of the reaction product are shown in Table 2.

[0080] d) PEMA4 Polyester PE4 (463.5 g) and DBTL catalyst (0.23 g) were dissolved in acetone (309.0 g) in a 2 L reaction flask equipped with a stirrer, temperature sensor and reflux condenser in an air stream. The mixture was heated to 45° C. and a solution of IPDI-HEMA (63.7 g) and IONOL® CP (2.7 g) in acetone (42.5 g) was added dropwise using a dropping funnel over 30 minutes. The temperature was then raised to 60° C. and held for 5 hours. The reaction mixture was cooled to room temperature and stirred for an additional 15 hours. The process was stopped when the desired NCO value (on solids) of less than 0.5% was reached. The acetone solvent was removed under vacuum at 40° C. for 100 hours. The properties of the reaction product are shown in Table 2.

[0081] e) PEMA5 Polyester PE5 (459.4 g) and DBTL catalyst (0.23 g) were dissolved in acetone (306.0 g) in a 2 L reaction flask equipped with a stirrer, temperature sensor and reflux condenser in an air stream. The mixture was heated to 45° C. and a solution of IPDI-HEMA (57.7 g) and IONOL® CP (2.6 g) in acetone (38.5 g) was added dropwise using a dropping funnel over 30 minutes. The temperature was then increased to 60° C. and held for 4 hours. The reaction mixture was cooled to room temperature and stirred for an additional 17 hours. The process was stopped when the desired NCO value (on solids) of less than 0.5% was reached. The acetone solvent was removed under vacuum at 40° C. for 110 hours. The properties of the reaction product are shown in Table 2.

[0082] f) PEMA6 Polyester PE6 (392.0 g) and DBTL catalyst (0.20 g) were dissolved in acetone (261.3 g) in a 2 L reaction flask equipped with a stirrer, temperature sensor and reflux condenser in an air stream. The mixture was heated to 45° C. and a solution of IPDI-HEMA (207.8 g) in acetone (138.5 g) was added dropwise using an addition funnel over 20 min. The temperature was then raised to 60° C. and held for 6 h. The reaction mixture was cooled to room temperature and stirred for an additional 64 h. The process was stopped when the desired NCO value (on solids) of less than 0.5% was reached. The acetone solvent was removed under vacuum at 40° C. for 96 h. The properties of the reaction product are shown in Table 2.

[0083] g) PEMA7 Polyester P7 (862.4 g) and DBTL catalyst (0.5 g) were dissolved in acetone (574.9 g) in a 2 L reaction flask equipped with a stirrer, temperature sensor and reflux condenser in an air stream. The mixture was heated to 45° C. and a solution of IPDI-HEMA (137.1 g) in acetone (91.4 g) was added dropwise using an addition funnel over 45 min. The temperature was then raised to 60° C. and held for 15 h. The process was stopped when the desired NCO value (on solids) of less than 0.5% was reached. The acetone solvent was removed under vacuum at 40° C. for 205 h. The properties of the reaction product are shown in Table 2.

[0084] h) PEMA8 Polyester PE8 (492.0 g) and DBTL catalyst (0.25 g) were dissolved in acetone (328.0 g) in a 2 L reaction flask equipped with a stirrer, temperature sensor and reflux condenser in an air stream. The mixture was heated to 45° C. and a solution of IPDI-HEMA (104.8 g) and IONOL® CP (3.0 g) in acetone (69.9 g) was added dropwise using an addition funnel over 40 minutes. The temperature was then increased to 60° C. and held for 8 hours. The reaction mixture was cooled to room temperature and stirred for an additional 17 hours. The process was stopped when the desired NCO value (on solids) of less than 0.5% was reached. The acetone solvent was removed under vacuum at 40° C. for 100 hours. The properties of the reaction product are shown in Table 2.

[0085] i) PEA1 Polyester PE1 (430.0 g) and DBTL catalyst (0.21 g) were dissolved in acetone (286.7 g) in a 2 L reaction flask equipped with a stirrer, temperature sensor and reflux condenser in an air stream. The mixture was heated to 45° C. and a solution of IPDI-HEA (163.8 g) and IONOL® CP (6.0 g) in acetone (109.2 g) was added dropwise using a dropping funnel over 45 min. The temperature was then increased to 60° C. and held for 12 h. The reaction mixture was cooled to room temperature and stirred for an additional 30 h. The process was stopped when the desired NCO value (on solids) of less than 0.5% was reached. The acetone solvent was removed under vacuum at 40° C. for 160 h. The properties of the reaction product are shown in Table 2.

[0086] [Table 2]

[0087] 5) Preparation of resin (Step C) Formulations consisting of the reaction product according to one of the examples 4a) to 4i), a photoinitiator (Irgacure® 819), optionally at least one reactive diluent (from the VISIOMER® product line) and optionally a filler (from the AEROSIL® product line) were prepared by mixing the various components in a speed mixer machine (1200-2300 rpm for 10-20 minutes) until a homogenous resin was obtained. The composition of the various formulations is shown in Table 3.

[0088] [Table 3a]

[0089] [Table 3b]

[0090] 6)3D printing The resin was then printed with a hot lithography (SLA) machine (Cubicure Caligma200). The temperature was adjusted depending on the viscosity of the resin. A viscosity of approximately 20 Pa·s at the printing temperature was targeted. Therefore, the printing temperature was basically in the range of 30–100 °C. The layer thickness was 100 μm. At the end of the printing job, the object was removed from the building platform. The parameters used are shown in Table 4.

[0091] Typical post-treatment entailed washing the printed object in pure isopropanol in a Formlab wash station for 1 h, after which the printed object was placed in a Formlab cure station and exposed to blue light (405 nm) while being heated at 80 °C for 2 h. Finally, the printed objects were tested according to standard DIN EN ISO 527 (tensile test) and the results are also summarized in Tables 4a and 4b.

[0092] [Table 4a]

[0093] [Table 4b]

[0094] The experimental examples show that the highest Mn polymer (PEMA3) achieves the highest elongation at break (over 200%) with good tensile strength (7MPa). By adding crosslinkers / diluents, tensile strength can be gained at the expense of elongation. Increasing Mw increases adhesion. Silica, especially fumed silica after treatment with methacrylsilane, can improve tensile strength without significantly affecting the elongation at break value.

Claims

1. A polyester polyol; a compound comprising at least one functional group capable of reacting with a hydroxyl group of said polyester polyol and at least one other functional group selected from an acrylate group or a methacrylate group; A method for additive manufacturing, comprising the step of: The polyester polyol is based on at least one organic acid containing at least two carboxyl groups, or an anhydride thereof, and at least one polyol containing at least two hydroxyl groups, The reaction product has a glass transition temperature (Tg) of less than 23° C., as measured according to DSC method DIN 53765; The additive manufacturing method, wherein the composition optionally further comprises a photopolymerization initiator.

2. The additive manufacturing method according to claim 1 , wherein the organic acid is a dimer acid of a fatty acid having 12 to 22 carbon atoms or adipic acid.

3. The method according to claim 1 or 2, wherein the compound is an isocyanate compound comprising at least one (meth)acrylate group and at least one isocyanate group.

4. The additive manufacturing method according to claim 3 , wherein the isocyanate compound is a reaction product of a diisocyanate and a compound containing a hydroxyl group and a (meth)acrylate group.

5. The additive manufacturing method according to any one of claims 1 to 4, wherein the at least one polyol is selected from the group consisting of octahydro-4,7-methano-1H-indene dimethanol, methylpropanediol-1,3, monoethylene glycol, neopentyl glycol, and hexanediol-1,6.

6. the at least one polyol is octahydro-4,7-methano-1H-indene dimethanol; The method according to any one of claims 1 to 5, wherein the at least one organic acid comprising at least two carboxyl groups is adipic acid or a dimer acid of a fatty acid having 18 carbon atoms.

7. The method according to any one of claims 1 to 6, wherein the composition comprises a filler.

8. The additive manufacturing method of claim 7 , wherein the filler is selected from inorganic particles.

9. The additive manufacturing method according to any one of claims 1 to 8, wherein the composition further comprises a compound comprising at least one methacrylate group but no isocyanate group.

10. The additive manufacturing method of claim 9, wherein the compound is present in an amount of 5 to 95% by weight, based on the total weight of the composition.

11. The method according to any one of claims 1 to 10, wherein the glass transition temperature (Tg) of the reaction product is between -60°C and 0°C.

12. The composition comprises at least two of the following: A) preparing a polyester polyol by reacting at least one organic acid containing at least two carboxyl groups, or anhydride thereof, with at least one polyol containing at least two hydroxyl groups; B) reacting the polyester polyol of step A) with a compound that contains at least one functional group capable of reacting with the hydroxyl groups of the polyester polyol and at least one other functional group selected from an acrylate group or a methacrylate group to obtain a reaction product having a glass transition temperature (Tg) of less than 23° C. and C) optionally mixing the reaction product of step B) with a photopolymerization initiator; The additive manufacturing method according to any one of claims 1 to 11, which is obtained by a method comprising:

13. The additive manufacturing method according to any one of claims 1 to 12, which is a 3D printing method using light.

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