Isocyanurates

Abstract

The invention relates to the use of multi-functional isocyanates as monomers in a polymerizable composition in order to produce solid polyisocyanates. The composition additionally comprises at least one polymerization initiator and optionally a cocatalyst. The invention is characterized in that a) a multifunctional non-aromatic primary isocyanate of the formula R(CH2-NCO)m is used as monomers, wherein R is an m-valent hydrocarbon group with up to 100 carbon atoms, one or more of which is optionally replaced with a heteroatom selected from O, N, and S, and m is a whole number ≥ 2; b) an organometallic photoinitiator is used as the polymerization initiator, said photoinitiator being an organometallic complex of an Mn or Fe ion; and c) the polymerization is carried out during the course of a method involving the heating and exposing of the photopolymerizable composition. A homogenous liquid mixture is first produced from all of the components of the composition, and the liquid mixture is then irradiated with a wavelength which is suitable for activating the organometallic photoinitiator in order to cure the composition into the solid polyisocyanurate. The composition is heated to a temperature of at least 50 °C during and / or after the exposure process. The invention also relates to solid polyisocyanurates which can be obtained in this manner.

Description

[0001] Isocyanurates

[0002] The present invention relates to the use of multifunctional isocyanates as monomers in a polymerizable composition for the preparation of solid polyisocyanurates.

[0003] STATE OF THE ART

[0004] Polyisocyanurates obtainable by polytrimerization of multifunctional and especially difunctional isocyanates according to the following reaction scheme 1 have been considered as promising materials for several years, since they form dense networks whose properties, such as thermal, mechanical and solubility properties, can be controlled within relatively wide limits by suitable choice of the radicals R.

[0005] Scheme 1

[0006] Various nucleophiles were used as catalysts, which are capable of initiating the reaction by attacking the electrophilic carbon atom of an isocyanate group. Various nitrogen compounds and transition metal complexes were employed for this purpose. For example, Polenz et al., "Thermally cleavable imine base / isocyanate adducts and oligomers suitable as initiators for radical homo- and copolymerization," Polym. Chem 5, 6678-6686 (2014), disclose the suitability of certain imine bases as catalysts for the oligomerization of diisocyanates. More specifically, it is revealed that these bases, when mixed with mono- and diisocyanates, form 2:1 adducts, whereby an isocyanate group of two molecules adds to the imine group of the base and to each other, thus forming a cyclic adduct or polyadduct, as shown in Scheme 2 below from Polenz et al.:

[0007] Scheme 2

[0008] The two bicyclic bases 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) and 1,5-diazabicyclo[4.3.0]non-5-ene (DBN) as well as 2-tert-butyl-1,1,3,3-tetramethylguanidine (tBuTMG) are specifically mentioned as suitable imine bases:

[0009] DBU DBN tBuTMG

[0010] Ethyl isocyanate, cyclohexyl isocyanate, dodecyl isocyanate, phenyl isocyanate, hexamethylene diisocyanate and isophorone diisocyanate were used as mono- and difunctional isocyanates: The reactants were mixed by combining dilute solutions in diethyl ether by dropwise addition at -5 °C, followed by warming to room temperature and stirring the mixture for 12 h and 18 h, respectively. Molecular weights of up to 6400 g / mol are disclosed for the oligomers obtained from two diisocyanates, namely the two aliphatic compounds hexamethylene diisocyanate (HMDI) and isophorone diisocyanate (IPDI), and the respective base, which in Scheme 2 above corresponds to values ​​for n of up to 20. Polenz et al. further describes that these adducts are only stable up to a certain temperature and decompose back into the original reactants upon further temperature increases, for which the formation of a radical transition state of the bases after elimination of the first isocyanate molecule is postulated. In the presence of radically polymerizable monomers, such asMethyl methacrylate, this leads to their polymerization, which is why the adducts are suitable as thermal radical polymerization initiators.

[0011] However, to the knowledge of the present inventors, only one publication exists to date that discloses the use of a photoinitiator to catalyze the trimerization of isocyanates, namely Martelli et al., "Cyclotrimerization of Aryl Isocyanates Photocatalyzed by a Metal Carbonyl Complex," J. Mol. Catal. 22, 89-91 (1983). In the course of this work, which was published 31 years before Polenz et al. (see above), only two monofunctional aromatic isocyanates were converted under UV irradiation to trimers of the following formula: phenyl and p-tolyl isocyanate (R 1 = H or CH3):

[0012] The reactions were carried out at room temperature in solution in an organic solvent (approximately 8 wt% isocyanate in THF) in the presence of 2.5 mol% of the known transition metal complex photoinitiator MeCpMn(CO)3 by irradiating the mixtures with a 125 W high-pressure mercury vapor lamp for 5 hours, resulting in a colorless precipitate which was subsequently characterized as the corresponding trimer by molecular weight determination, IR and mass spectrometry.

[0013] Against this background, the aim of the present invention was to develop a process for the production of solid polyisocyanurates, such as coatings or three-dimensional bodies, by means of photopolymerization.

[0014] DISCLOSURE OF THE INVENTION

[0015] The present invention achieves this objective by providing the use of multifunctional isocyanates as monomers in a polymerizable composition for producing solid polyisocyanurates, the composition further comprising at least one polymerization initiator and optionally a co-catalyst, the process according to the invention being characterized in that a) multifunctional, non-aromatic, primary isocyanates of the formula R(CH2-NCO)m are used as monomers, wherein R is an m-valent hydrocarbon radical having up to 100 carbon atoms, one or more of which are optionally replaced by a heteroatom selected from O, N and S, and m is an integer > 2; b) an organometallic photoinitiator is used as polymerization initiator,which is an organometallic complex of a Mn or Fe ion; and c) the polymerization is carried out in the course of a process comprising heating and irradiating the photopolymerizable composition, wherein a homogeneous liquid mixture is first prepared from all components of the composition, which mixture is subsequently irradiated with a wavelength suitable for activating the organometallic photoinitiator in order to cure the composition to the solid polyisocyanurate, wherein the composition is heated to a temperature of at least 50 °C during and / or after irradiation. The inventors have surprisingly found that the polytrimerization reactions shown in Scheme 1 under photocatalysis can only be carried out successfully with multifunctional, non-aromatic, primary isocyanate monomers of the formula R(CH2-NCO)m (m > 2). As the later examples demonstrate, monomers with aliphatic,Consistently good results were obtained with both cycloaliphatic and aromatic divalent radicals R, whereas no conversions were observed with secondary or aromatic isocyanates – not even with isophorone diisocyanate (IPDI), which has both a primary and a secondary isocyanate group, not even at temperatures above 100 °C during exposure. This contradicts, at least in part, the teaching of the publication by Martelli et al. (see above), where two aromatic – albeit only monomeric – isocyanates were successfully trimerized using a photoinitiator.

[0016] The properties of the resulting polyisocyanurates can be controlled within a wide range by specifically selecting the R radical. When using R radicals with more than 50 or more than 80 carbon atoms, the degree of crosslinking can decrease significantly, while with trifunctional or higher-functional monomers, complete conversions may be more difficult to achieve. Therefore, in preferred embodiments of the invention, multifunctional primary isocyanates of the formula R(CH2-NCO)m are used as monomers, wherein R has up to 50 carbon atoms, preferably up to 30 carbon atoms, more preferably up to 20 carbon atoms; and / or m = 2 or 3, preferably 2.

[0017] The multifunctional primary isocyanate is otherwise not specifically restricted according to the present invention, but hexamethylene diisocyanate, 2,2,4- and / or 2,4,4-trimethylhexamethylene diisocyanate, m-xylylene diisocyanate or 1,3-bis(isocyanatomethyl)cyclohexane are preferably used according to the invention, since these monomers are commercially available and have already provided good results.

[0018] The organometallic complex of a Mn or Fe ion as the organometallic photoinitiator is also not specifically restricted according to the present invention, as long as it is capable of photocatalyzing the polytrimerization reactions. Preferably, an organometallic complex of a Mn ion is used, with a sandwich or half-sandwich compound, in particular a sandwich compound or half-sandwich carbonyl complex, of the Fe or Mn ion being used as the organometallic complex even more preferably, since several other organometallic photoinitiators have shown no activity in the experiments conducted to date, as demonstrated by the later comparative examples. For this reason, in particular, methylcyclopentadienylmanganese tricarbonyl (MeCpMn)(CO)3) or cyclopentadienyl(p-cymene)iron(I) hexafluorophosphate (Irgacure 261) is used as the organometallic complex according to the invention.

[0019] According to the present invention, the use of a co-catalyst is not absolutely necessary, but can sometimes significantly increase the conversions and reaction rates of the photopolymerizations, as the later examples also demonstrate. Therefore, in preferred embodiments of the process according to the invention, a non-nucleophilic base, such as a tertiary amine, is used as the co-catalyst, more preferably a guanidine derivative or an N-substituted cyclic or a bi- or tricyclic amidine. In particularly preferred embodiments, according to the present invention, 1,5-diazabicyclo[4.3.0]non-5-ene (DBN), N-methylated 1,5,7-triazabicyclo[4.4.0]dec-5-ene (MTBD) or 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) is used as the co-catalyst.

[0020] These are commercially available and represent very strong non-nucleophilic bases and thus excellent co-catalysts, as demonstrated by the results with DBN in the later examples. The proportions of the individual components of the photopolymerizable composition are not specifically limited, as long as complete curing of the composition is ensured by exposure and, if appropriate, subsequent heat treatment. In preferred embodiments, the composition comprises at least 90 mol% of multifunctional primary isocyanate and at least 0.1 mol%, preferably at least 0.5 mol%, of organometallic photoinitiator, more preferably about 94 mol% of multifunctional primary isocyanate, about 1 mol% of organometallic photoinitiator, and about 5 mol% of co-catalyst.

[0021] Of course, the composition may also contain other components, such as sensitizers, inhibitors, property modifiers, and dyes. Furthermore, it may also comprise one or more solvents if only the polyisocyanurate polymer product is desired, which is then applied to its intended use, e.g., formed into a specific shape. The appropriate selection of corresponding components, solvents, and proportions can, in any case, be easily determined by those of ordinary skill in the art through routine tests similar to those disclosed herein, and without undue experimentation.

[0022] In preferred embodiments, however, a solvent-free polymerizable composition is used, which is either applied to a solid surface before exposure to produce a polyisocyanurate coating, or is exposed and cured layer by layer in a generative manufacturing process, preferably hot lithography, to produce a three-dimensional molded body made of polyisocyanurate, wherein both the coating and the three-dimensional molded body can be subjected to a subsequent heat treatment for post-curing.

[0023] In a second aspect, the invention also relates to the polyisocyanurates obtainable by the process according to the invention using multifunctional, non-aromatic, primary isocyanates. BRIEF DESCRIPTION OF THE FIGURES

[0024] The present invention is described in more detail below using specific embodiments and comparative examples which serve solely to illustrate the invention and are not intended to limit it.

[0025] Reference is made to the accompanying drawings, Fig. 1a-d, Fig. 2a-d and Fig. 3a-b, of which the first two each show graphic representations of the results measured or calculated therefrom in Examples 4 to 7 under variation of the process parameters photoinitiator concentration (Fig. 1a and 2a), co-catalyst concentration (Fig. 1b and 2b), temperature during exposure (Fig. 1c and 2c) and exposure intensity (Fig. 1d and 2d).

[0026] And Fig. 3 shows photographs of polyisocyanurate coatings produced by the process according to the invention on a glass plate (Fig. 3a) and a metal plate (Fig. 3b).

[0027] EXAMPLES

[0028] Materials and processes

[0029] All starting materials were obtained from commercial sources, the monomers of which were previously distilled, but the photoinitiators and bases were used without further purification.

[0030] Components

[0031] In the polymerizable mixtures of the examples and comparative examples, the following compounds were used as reaction components:

[0032] Monomers

[0033] Hexamethylene diisocyanate (HMDI), a mixture of 2,2,4- and 2,4,4-trimethylhexamethylene diisocyanate (TMDI), 1,3-bis(isocyanatomethyl)cyclohexane (HeXDI), m-xylylene diisocyanate (XDI), toluene diisocyanate (TDI), methylene di(phenyl isocyanate) (MDI), isophorone diisocyanate (IPDI) and 4,4'-diisocyanatodicyclohexylmethane (H12MDI):

[0034] IPDI H 12 MDI

[0035] Photoinitiators

[0036] (Methylcyclopentadienyl)mangan(ll)-tricarbonyl (MeCpMn(CO)3): Bis(2,6-difluor-3-(1 H-pyrrol-1 -yl)phenyl)titanocen (Irgacure 784):

[0037] Bis(cyclopentadienyl)zirconium(IV)-dichlorid (Zirconocendichlorid, Cp2ZrCl2):

[0038] Cyclopentadienyl(p-cymol)ruthenium(ll)-hexafluorophosphat (Cp(p-cymol)RuPF6):

[0039] Cyclopentadienyl(triethylphosphin)kupfer(l) (Cp(Et3P)Cu): Zink(ll)-tetraphenylporphyrin (TPPZn):

[0040] Tris[tris(dimethylamino)phosphoranyliden]phosphorimidtriamid ("Phosphazen-Super- Messungen

[0041] The photo-DSC measurements were carried out in a Netzsch DSC 204 F1 Phoenix model, measuring the reaction enthalpy (in kJ / mol) and the time to maximum heat development tmax (in s). From this, the monomer content in the composition, and the molecular weight of the respective isocyanate monomer were used to determine the reaction conversion (in %) and the polymerization rate Rp (in mmol / l) using well-known equations (see, for example, calculated.

[0042] Examples 1 and 2, Comparison Examples 1 to 14 - Photo-DSC without base

[0043] First, it was investigated which of the available photocatalysts was able to initiate the photopolymerization of hexamethylene diisocyanate (HMDI) as an aliphatic diisocyanate and of toluene diisocyanate (TDI) as an aromatic diisocyanate.

[0044] For this purpose, the monomers were mixed at room temperature with 5 mol% photoinitiator each. Subsequently, 10 to 12 mg of the formulations were poured into aluminum DSC crucibles and subsequently heated to 100 °C under a nitrogen atmosphere. At this temperature, the monomers were then irradiated with the Exfo OmniCure™ Series 2000 medium-pressure mercury lamp of the DSC instrument using light with a wavelength between 320 nm and 500 nm at 60 mW / cm. 2 The enthalpy and tmax were measured. The results are shown in Table 1 below.

[0045] Table 1

[0046] From these results, it is clearly evident that only the Mn half-sandwich complex MeCpMn(CO)3 and the Fe sandwich complex Irgacure 261 of inventive examples 1 and 2 were capable of initiating the polymerization of the aliphatic diisocyanate HMDI, with the manganese catalyst clearly outperforming the iron sandwich complex, which did not lead to complete curing. Even with the manganese catalyst dimanganese decacarbonyl, no conversion was observed with HMDI in Comparative Example 3. However, none of the eight catalysts tested succeeded in polytrimerizing the aromatic diisocyanate TDI, which was very surprising in light of the disclosure by Martelli et al. (see above), where monomeric phenyl and tolyl isocyanate could indeed be trimerized using MeCpMn(CO)3. Example 3, Comparison Examples 15 and 16 - Photo-DSC with Base

[0047] To investigate whether the addition of a base as co-catalyst increases the performance of the system, 5 mol% of one of the above-mentioned bases was initially added to the combination of Example 1, i.e. HMDI as monomer and MeCpMn(CO)3 as photoinitiator, and the course of the reaction was again monitored by photo-DSC, where possible.

[0048] In this case, the monomers were first mixed at room temperature with 5 mol% of the respective base. The addition of DBN in Example 3 resulted in the precipitation of an adduct with HMDI, as known from the literature; see Polenz et al. (see above). Furthermore, the addition of the "phosphazene superbase" P4-t-Bu to HMDI in Comparative Example 15 resulted in immediate heat evolution, i.e., polymerization was initiated immediately. This base is therefore unsuitable for the present invention due to the lack of stability of the polymerizable composition prior to irradiation. The mixtures of HMDI and DBN (Example 3) or TMG (Comparative Example 16) were subsequently heated to 80°C, whereby the precipitated HMDI-DBN 2:1 adduct dissolved in the excess HMDI. After cooling, 5 mol% MeCpMn(CO)3 was added, after which the reaction mixtures were heated to 100 °C under N2 atmosphere and exposed to light by photo-DSC and the reaction processes were observed.The results obtained and, for comparison purposes, those of Example 1 are summarized in Table 2 below.

[0049] Table 2

[0050] The reaction started even at room temperature without photoinitiator. As can easily be seen, the addition of DBN in Example 3 did not increase the reaction enthalpy compared to Example 1, but did shorten the tmax by about half. In general, it can therefore be stated that even the adduct between HMDI and DBN, which according to Polenz et al. (see above) would have decomposed only at 106 °C, was able to promote polymerization at the metal center of the photoinitiator at 100 °C. In contrast, the addition of TMG as a base completely inhibited the photoinitiator compared to Example 1, so that no heat was generated during polymerization. Therefore, preferred bases according to the present invention, as explained above, are N-substituted cyclic or bi- (or even tri-)cyclic amidines, such as DBN, DBU, or MTBD, all of which should yield comparable results.

[0051] Examples 4 to 7 - Variation of process parameters

[0052] In light of the above results, the inventors conducted experiments to optimize the process parameters. For this purpose, several reaction mixtures containing HMDI as the monomer, MeCpMn(CO)3 as the photoinitiator, and DBN as the base were prepared by mixing the components at room temperature, and their reaction processes were investigated using photo-DSC.

[0053] One of four process parameters was varied in each case: the photoinitiator concentration (Example 4), the base concentration (Example 5), the temperature during exposure (Example 6), and the exposure intensity (Example 7). The reaction enthalpy and tmax were again measured using photo-DSC. From these results, the reaction conversion (in %) and the polymerization rate Rp (in mmol / l) were calculated using standard equations. The results are shown graphically in Figures 1 and 2 and are discussed below.

[0054] Example 4

[0055] First, the concentration of the initiator MeCpMn(CO)3 was varied between 0.2, 0.5, 0.75, 1 and 5 mol%, while that of the base DBN was kept constant at 5 mol% and the irradiation was carried out at 100 °C and with an intensity of 60 mW / cm 2 The results obtained in this way are graphically presented in Figs. 1a and 2a. In general, in Fig. 1, tmax (s) is plotted against the respective varied parameter, while in Fig. 2, the scales for Rp (mmol / ls; left) and for conversion (%; right) are found on the x-axes, and the calculated values ​​for these are plotted against the respective varied parameter. Of the two "curves" obtained by connecting the measurement points, the one for conversion is the higher one (at least for low y-values) (as can also be seen from the arrows).

[0056] From Fig. 1 a and 2a it is easy to see that above a photoinitiator concentration of 1 mol% no improvement in the results can be achieved, which is why this concentration was used as standard in the later examples.

[0057] Example 5

[0058] The same applies to the variation of the co-catalyst amount (at constant 0.5 mol% photoinitiator, 100 °C exposure temperature and 60 mW / cm 2 Intensity) between 1, 2, 3, 4, 5, and 10 mol%. As shown in Figs. 1b and 2b, increasing the DBN concentration from 5 to 10 mol% increased the reaction rate by approximately 15%, while the conversion and tmax even decreased slightly. The previously selected base concentration of 5 mol% was therefore retained in the subsequent examples.

[0059] Example 6

[0060] When the exposure temperature was varied between 80 °C and 140 °C in steps of 20 °C (at constant 1 mol% photoinitiator, 5 mol% base and 60 mW / cm 2Intensity), however, a steady improvement was observed for two of the three values, as can be seen in Figs. 1 c and 2 c. Only the conversion decreased by about 3 percentage points at 140 °C compared to that at 120 °C. However, since the improvement in the values ​​during the transition from 80 °C to 100 °C was many times greater than the (two) later ones, the later examples were also exposed at 100 °C (with one exception). What was remarkable in this experiment was that increasing the temperature from 100 °C to 120 °C only led to relatively moderate improvements, even though the adducts between HMDI and DBN should have gradually decomposed from 106 °C onwards. The improvements during the transition from 80 °C to 100 °C were many times greater in all three cases.Without wishing to commit to a theory, the inventors assume, in view of the small difference between 100 °C and 106 °C, that even at an exposure temperature of 100 °C, the reaction mixture would have been at least locally at more than 106 °C due to the reaction enthalpy released.

[0061] Example 7

[0062] During the final variation of the exposure intensity between 30, 60 and 120 mW / cm 2 (at a constant 1 mol% photoinitiator, 5 mol% base, and 100 °C exposure temperature), improvements in the values ​​were indeed consistently observed, as shown in Fig. 1d and 2d. However, since these improvements – especially in the conversion – were due to the doubling of the intensity from 60 to 120 mW / cm 2 could not meet the requirements, the later examples continued to use 60 mW / cm 2 exposed.

[0063] Nevertheless, these four examples demonstrate that the efficiency of the method according to the invention can be significantly increased by varying the parameters.

[0064] Example 8, Comparison Examples 17 to 22 - Photo-DSC with Base

[0065] Subsequently, after MeCpMn(CO)3 and Irgacure 261, the remaining catalysts listed in Table 1 were also tested for the effect of adding 5 mol% DBN to 94 mol% HMDI and now only 1 mol% initiator at 100 °C and 60 mW / cm 2 The results obtained and, for comparison purposes, those of Example 2 are summarized in Table 3 below. Table 3

[0066] It can be seen that again only the iron sandwich complex Irgacure 261 was able to trigger the photopolymerization of HMDI - but this time in the presence of the base to a considerably better extent despite reducing its concentration from 5 to 1 mol%: In Example 8, complete curing was achieved with good values ​​for the reaction enthalpy and for tmax.

[0067] However, all other metal complex compounds showed no activity as initiators of the photopolymerization of HMDI even in the presence of DBN - as previously in Comparative Examples 1 to 6 without the addition of base.

[0068] Examples 9 to 12, Comparison Examples 23 to 25 - Photo-DSC of other monomers with base

[0069] Following the initial testing of the monomers HMDI and TDI, the remaining diisocyanates mentioned and described above were also tested for their suitability for the process according to the invention. For this purpose, 94 mol% of monomer or 47 mol% of two monomers in Example 12 were mixed with 1 mol% of the most effective initiator, MeCpMn(CO)3, and 5 mol% DBN at 80 °C and then heated at 100 °C with 60 mW / cm 2 exposed. The results obtained and measured by photo-DSC, as well as those of Example 3 and Comparative Example 7 (each with 5 mol% initiator) for comparison purposes, are summarized in Table 4 below.

[0070] Table 4

[0071] It can be seen that only multifunctional primary diisocyanates of the formula R(CH2-NCO)2, namely hexamethylene diisocyanate (HMDI), a mixture of 2,2,4- and 2,4,4-trimethylhexamethylene diisocyanate (TMDI), 1,3-bis(isocyanatomethyl)cyclohexane (HeXDI), and m-xylylene diisocyanate (XDI), could be photopolymerized in this way, while multifunctional aromatic diisocyanates, namely toluene diisocyanate (TDI) and methylene di(phenyl isocyanate) (MDI), and secondary diisocyanates, namely isophorone diisocyanate (IPDI) and 4,4'-diisocyanatodicyclohexylmethane (H12MDI), showed no reaction at all—not even IPDI, which has a primary and a secondary isocyanate group. With regard to aromatic diisocyanates, as already mentioned, this contradicts at least partially the teachings of Martelli et al. (see above), but also those of Polenz et al. (see above).The former had trimerized phenyl and tolyl isocyanate using MeCpMn(CO)3 as a catalyst, and the latter had successfully prepared adducts with phenyl isocyanate, as well as with cyclohexyl isocyanate and isophorone diisocyanate, i.e., with secondary isocyanate groups, using DBN as a base. Example 13 - Exposure at room temperature.

[0072] To test whether heating of the reaction mixtures is mandatory during exposure in the process according to the invention, the approach from Example 3 was repeated, but the components—94 mol% HMDI, 5 mol% DBN, and 1 mol% MeCpMn(CO)3—were cooled to room temperature and exposed after mixing and heating to 80 °C. Only then was the exposed mixture heated to 100 °C and 120 °C, respectively, where it solidified to form the polyisocyanurate. In contrast, an analogous unexposed mixture showed no solidification upon heating.

[0073] In this way, it was proven that the initiation of the polytrimerization reactions is successful by appropriate exposure even at normal temperature.

[0074] Examples 14 and 15 - Coatings of solid polyisocyanates

[0075] To produce polymer coatings on solid surfaces, the batches of Examples 3 and 9 were repeated using 5 mol% DBN, 1 mol% MeCpMn(CO)3, and 94 mol% HMDI (Example 14) or TMDI (Example 15). After heating to 80 °C, the mixtures were dropwise applied to a glass plate (Example 14) or drawn onto a metal plate with a doctor blade (layer thickness: 30 μm; Example 15). Both reaction mixtures were subsequently exposed to a mercury vapor lamp at 120 °C and post-cured in an oven at 120 °C for 24 hours, yielding solid polyisocyanurate coatings in both cases.

[0076] Photographs of this can be seen in Fig. 3a for Example 14 and Fig. 3b for Example 15.

[0077] The above examples thus demonstrate that solid polyisocyanurates can be obtained in a completely new way by the process according to the invention using multifunctional, non-aromatic, primary isocyanates.

Claims

PATENT CLAIMS 1. Use of multifunctional isocyanates as monomers in a polymerizable composition for producing solid polyisocyanurates, the composition further comprising at least one polymerization initiator and optionally a co-catalyst, characterized in that a) multifunctional, non-aromatic, primary isocyanates of the formula R(CH2-NCO)m are used as monomers, wherein R is an m-valent hydrocarbon radical having up to 100 carbon atoms, one or more of which are optionally replaced by a heteroatom selected from O, N and S, and m is an integer > 2; b) an organometallic photoinitiator is used as the polymerization initiator, which is an organometallic complex of a Mn or Fe ion;and c) the polymerization is carried out in the course of a process comprising heating and irradiating the photopolymerizable composition, wherein a homogeneous liquid mixture is first prepared from all components of the composition, which mixture is subsequently irradiated with a wavelength suitable for activating the organometallic photoinitiator in order to cure the composition to form the solid polyisocyanurate, wherein the composition is heated to a temperature of at least 50°C during and / or after irradiation; 2. Use according to claim 1, characterized in that multifunctional primary isocyanates of the formula R(CH2-NCO)m are used as monomers, wherein R has up to 50 carbon atoms, preferably up to 30 carbon atoms, more preferably up to 20 carbon atoms; and / or m = 2 or 3, preferably 2.

3. Use according to claim 1 or 2, characterized in that the multifunctional primary isocyanate used is hexamethylene diisocyanate, 2,2,4- and / or 2,4,4- Trimethylhexamethylene diisocyanate, m-xylylene diisocyanate or 1,3-bis(isocyanatomethyl)cyclohexane is used.

4. Use according to one of claims 1 to 3, characterized in that an organometallic complex of a Mn ion is used as organometallic photoinitiator.

5. Use according to one of claims 1 to 4, characterized in that a sandwich or half-sandwich compound of the ion is used as the organometallic complex.

6. Use according to claim 5, characterized in that a sandwich compound or a half-sandwich carbonyl complex of the ion is used as the organometallic complex.

7. Use according to claim 6, characterized in that methylcyclopentadienylmanganese tricarbonyl (MeCpMn)(CO)3) or cyclopentadienyl(p-cymene)iron(I) hexafluorophosphate (Irgacure 261) is used as the organometallic complex.

8. Use according to one of claims 1 to 7, characterized in that a non-nucleophilic base is used as co-catalyst.

9. Use according to claim 8, characterized in that 1,5-diazabicyclo[4.3.0]non-5-ene (DBN) is used as co-catalyst.

10. Use according to one of claims 1 to 9, characterized in that the polymerizable composition comprises at least 90 mol% of multifunctional primary isocyanate, at least 0.1 mol% or at least 0.5 mol% of organometallic photoinitiator and about 5 mol% of co-catalyst.

11. Use according to claim 10, characterized in that the polymerizable composition comprises about 94 mol% multifunctional primary isocyanate, about 1 mol% organometallic photoinitiator and about 5 mol% co-catalyst.

12. Use according to one of claims 1 to 11, characterized in that the polymerizable composition is first heated to a temperature of at least 80 °C, optionally to a temperature of 80 °C to 90 °C, and exposed to light at this temperature.

13. Use according to one of claims 1 to 13, characterized in that the polymerizable composition is applied to a solid surface before exposure to produce a polyisocyanurate coating, or is exposed and cured layer by layer in a generative manufacturing process, such as hot lithography, to produce a three-dimensional molded body from polyisocyanurate, wherein the coating or the three-dimensional molded body is optionally subjected to a subsequent heat treatment for post-curing.

14. A polyisocyanurate obtainable by a process according to any one of claims 1 to 13 using multifunctional, non-aromatic, primary isocyanates.

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