Patent Description:
Oxazolidinones are widely used structural motifs in pharmaceutical applications and the cycloaddition of epoxides and isocyanates seems to be a convenient one-pot synthetic route to it. Expensive catalysts, reactive polar solvents, long reaction times and low chemoselectivities are common in early reports for the synthesis of oxazolidinones (<NPL>). Due to these disadvantages there was the need for alternative methods for the production of oxazolidinones especially for application of oxazolidinones as structural motif in polymer applications.

The scientific publication <NPL> discloses polyoxazolidinones prepared from various bisepoxides and various diisocyanates in the presence of alkaline metal halide catalysts. A solution of equimolar bisepoxide and diisocyanate amounts is added dropwise to a reactor containing a LiCl catalyst dissolved in DMF under reflux conditions within <NUM> and a subsequent post reaction of <NUM> to <NUM> was carried out under reflux conditions in order to complete the reaction.

<CIT> discloses a powder coating composition comprising an epoxy-terminated polyoxazolidinone, prepared by reacting a diepoxide with a diisocyanate, wherein the ratio of epoxide equivalents to isocyanate equivalents ranges from <NUM>:<NUM> to <NUM>:<NUM>. The resulting polyoxazolidinones have an epoxy equivalent weight from <NUM> to <NUM>. In example <NUM>, an epoxy-terminated polyoxazolidinone powder is prepared, wherein in a first step a urethane is formed by reaction of the toluene diisocyanate with a stoichiometric excess of ethanol in the presence of dibutyltindilaurate followed by the reaction of this urethane with an epoxide in the presence of triethyldiamine forming the oxazolidinone. In examples <NUM> and <NUM> epoxy-terminated polyoxyazolidinone powders were synthesized with epoxide equivalents to isocyanate equivalents of <NUM> and <NUM> in the presence of a tetraethylammonium bromide catalyst.

<CIT> describes an oxazolidinone-ring containing epoxy resin, wherein the epoxy resin is prepared by firstly obtaining a blocked polyurethane diisocyanate by reaction of an diisocyanate with an alcohol and allowing it to react with a diepoxide, wherein the reaction may proceed in the presence of a tertiary amine catalyst and optionally a tin co-catalyst.

<CIT> provides a process for the production of oligomeric oxazolidinone-containing polyepoxides based on bisepoxides and diisocyanates in the presence of a phosphonium carboxylates or halides as catalyst systems. In the disclosed examples, the ratio of NCO-groups of the applied diisocyanates to epoxy-groups of the applied bisepoxides is between <NUM>:<NUM> until <NUM>:<NUM> resulting in solid polyoxazolidinones with epoxy equivalent weights between <NUM> and <NUM>.

In <NPL>)) oxazolidinone formation was investigated by reaction of <NUM>,<NUM>-methylene diphenyl diisocyanate (MDI) with o-cresyl glycidyl ether (OGCE) or Bisphenol A diglycidyl ether (BADGE) in the presence of various tetra-n-butyl ammonium halides, wherein molar BADGE to MDI ratios up to <NUM> to <NUM> were applied. However, significant amounts of side products, i.e. isocyanurates, were detected.

<CIT> disclose a method for the production of oxazolidinone compounds, wherein an isocyanate composition comprising at least one isocyanate compound is reacted with an epoxide composition comprising an epoxide compound, wherein a multi metal cyanide compound is used as a catalyst, wherein this catalyst is applied in low catalyst concentrations of <NUM> ppm to <NUM> ppm. The resulting oxazolidinone compound have an characteristic signal for the oxazolidinone carbonyl group at <NUM>-<NUM> while also a signal at app. <NUM>-<NUM> can be detected by infrared spectroscopy which is assigned to urethane carbonyl moiety as a side product.

Objective of the present invention was therefore to identify a simple one-step process for the preparation of epoxy-group terminated polyoxazolidinones with defined epoxy equivalent weights preferable in combination with a low polydispersity and reduced viscosities for further polymerization applications. In this context, side reactions, e.g. by formation of isocyanurates or polyurethanes should be reduced or avoided. In addition, the use of high-boiling solvents typically applied in oxazolidinone synthesis which need to be removed at high temperature should be avoided to reduce the number of side products, obtain less colored oxazolidinones, and result in a more energy-efficient process.

Surprisingly, it has been found that the problem can be solved by a process for producing an epoxy-group terminated polyoxazolidinone comprising the copolymerization of a polyisocyanate compound (A) with two or more isocyanate groups with a polyepoxide compound (B) with two or more epoxy groups in the presence of a catalyst (C);.

As used herein, the term "polyoxazolidinone" is meant to denote compounds containing at least two oxazolidinone groups in the molecule. The term "epoxy-group terminated" polyoxazolidinone is related to polyoxazolidinone compounds, wherein the molar ratio of the epoxy groups of the polyepoxide compound (B) to the isocyanate groups of the polyisocyanate compound (A) is from <NUM>:<NUM>, so no terminal isocyanate groups are present within the polyoxazolidinone compound according to the present invention.

In an embodiment of the method according to the invention the copolymerization process is performed at a reaction temperature of ≥ <NUM> to ≤ <NUM>, preferably at a temperature of ≥ <NUM> to ≤ <NUM>, more preferred at a temperature of ≥ <NUM> to ≤ <NUM>, most preferred at a temperature of ≥ <NUM> to ≤ <NUM>. If temperatures below <NUM> are set, the reaction is generally very slow. At temperatures above <NUM>, the amount of undesirable secondary products increases considerably.

As used herein, the term "polyisocyanate compound" is meant to denote compounds having two or more isocyanate groups.

In an embodiment of the method according to the invention, the polyisocyanate compound (A) is an aliphatic or cycloaliphatic polyisocyanate compound (A-<NUM>), and/or an araliphatic or aromatic polyisocyanate compound (A-<NUM>), preferable an aromatic and/or araliphatic polyisocyanate compound (A-<NUM>).

In an embodiment of the method according to the invention, the polyisocyanate compound (A) is at least one polyisocyanate accessible in various ways, for example by phosgenation in the liquid or gas phase or by a phosgene-free route, for example by thermal urethane cleavage.

In an embodiment of the method according to the invention, the polyisocyanate compound (A) is at least one compound selected from the group consisting of polyisocyanates from the molecular weight range of <NUM>/mol to <NUM>/mol having aliphatically, cycloaliphatically, araliphatically and/or aromatically bonded isocyanate groups, examples being <NUM>,<NUM>-diisocyanatobutane, <NUM>,<NUM>-diisocyanatopentane (pentamethylene diisocyanate, PDI), <NUM>,<NUM>-diisocyanatohexane (hexamethylene diisocyanate, HDI), <NUM>-methyl-<NUM>,<NUM>-diisocyanatopentane, <NUM>,<NUM>-diisocyanato-<NUM>,<NUM>-dimethylpentane, <NUM>,<NUM>,<NUM>- or <NUM>,<NUM>,<NUM>-trimethyl-<NUM>,<NUM>-diisocyanatohexane, <NUM>,<NUM>-diisocyanatooctane, <NUM>,<NUM>-diisocyanatodecane, <NUM>,<NUM>-diisocyanatododecane, <NUM>,<NUM>- and <NUM>,<NUM>-diisocyanatocyclohexane, <NUM>,<NUM>- and <NUM>,<NUM>-bis(isocyanatomethyl)cyclohexane, <NUM>-isocyanato-<NUM>,<NUM>,<NUM>-trimethyl-<NUM>-isocyanatomethylcyclohexane (isophorone diisocyanate, IPDI), <NUM>,<NUM>'- and <NUM>,<NUM>'-diisocyanatodicyclohexylmethane (H12-MDI), <NUM>,<NUM>'-diisocyanato-<NUM>,<NUM>-dicyclohexyl propane, <NUM>-isocyanato-<NUM>-methyl-<NUM>(<NUM>)isocyanatomethylcyclohexane, bis(isocyanatomethyl)norbornane, or any polyisocyanates having uretdione, isocyanurate, allophanate, biuret, iminooxadiazinedione and/or oxadiazinetrione structure, prepared by modification of simple aliphatic and/or cycloaliphatic diisocyanates, for example those of the type mentioned above, as described for example in <NPL>, in <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT> and <CIT> or in <CIT>, <CIT> and <CIT> or by mixtures of at least two such polyisocyanates, and <NUM>,<NUM>- and <NUM>,<NUM>-bis(isocyanatomethyl)benzene (xylylene diisocyanate, XDI), <NUM>,<NUM>- and <NUM>,<NUM>-bis(<NUM>-isocyanatopropan-<NUM>-yl)benzene (tetramethylxylylene diisocyanate, TMXDI), <NUM>,<NUM>-bis(isocyanatomethyl)-<NUM>-methylbenzene, <NUM>,<NUM>-bis(isocyanatomethyl)-<NUM>-ethylbenzene, <NUM>,<NUM>-bis(isocyanatomethyl)-<NUM>-methylbenzene, <NUM>,<NUM>-bis(iscyanatomethyl)-<NUM>,<NUM>,<NUM>-trimethlybenzene, <NUM>,<NUM>-bis(isocyanatomethyl)-<NUM>,<NUM>-dimethylbenzene, <NUM>,<NUM>-bis(isocyanatomethyl)-<NUM>,<NUM>-dimethylbenzene, <NUM>,<NUM>-bis(isocyanatomethyl)-<NUM>,<NUM>,<NUM>,<NUM>-tetramethylbenzene, <NUM>,<NUM>-bis(isocyanatomethyl)-<NUM>-tert-butylbenzene, <NUM>,<NUM>-bis(isocyanatomethyl)-<NUM>-chlorobenzene, <NUM>,<NUM>-bis(isocyanatomethyl)-<NUM>,<NUM>-dichlorobenzene, <NUM>,<NUM>-bis(isocyanatomethyl)-<NUM>,<NUM>,<NUM>,<NUM>-tetrachlorobenzene, <NUM>,<NUM>-bis(isocyanatomethyl)-<NUM>,<NUM>,<NUM>,<NUM>-tetrachlorobenzene, <NUM>,<NUM>-bis(isocyanatomethyl)-<NUM>,<NUM>,<NUM>,<NUM>-tetrabromobenzene, <NUM>,<NUM>-bis(<NUM>-isocyanatoethyl)benzene and <NUM>,<NUM>-bis(isocyanatomethyl)naphthalene, <NUM>,<NUM>-, <NUM>,<NUM>- and <NUM>,<NUM>-diisocyanatobenzene (phenylene diisocyanate), <NUM>,<NUM>- and <NUM>,<NUM>-diisocyanatotoluene (toluene diisocyanate, TDI), <NUM>,<NUM>,<NUM>,<NUM>-tetramethyl-<NUM>,<NUM>-diisocyanatobenzene, the isomeric diethylphenylene diisocyanates, diisopropylphenylene diisocyanates, diisododecylphenylene diisocyanates and biphenyl diisocyanates, <NUM>,<NUM>'-dimethoxybiphenyl-<NUM>,<NUM>'-diisocyanate, <NUM>,<NUM>'-, <NUM>,<NUM>'- and <NUM>,<NUM>'-diisocyanatodiphenylmethane (MDI), <NUM>,<NUM>'-dimethyl diphenylmethane-<NUM>,<NUM>'-diisocyanate, <NUM>,<NUM>'-diisocyanatodiphenylethane, <NUM>,<NUM>-diisocyanatonaphthalene (NDI), diphenylether diisocyanate, ethylene glycol diphenylether diisocyanate, diethylene glycol diphenylether diisocyanate, <NUM>,<NUM>-propylene glycol diphenylether diisocyanate, benzophenone diisocyanate, triisocyanatobenzene, <NUM>,<NUM>,<NUM>-triisocyanatotoluene, trimethylbenzene triisocyanate, diphenylmethane-<NUM>,<NUM>,<NUM>'-triisocyanate, <NUM>-methyldiphenylmethane-<NUM>,<NUM>,<NUM>'-triisocyanate, the isomeric naphthalene triisocyanates and methylnaphthalene diisocyanates, triphenylmethane triisocyanate, <NUM>,<NUM>-diisocyanato-<NUM>-[(<NUM>-isocyanato-<NUM>-methylphenyl)methyl]benzene, <NUM>-methyl-diphenylmethane-<NUM>,<NUM>,<NUM>',<NUM>',<NUM>'-pentaisocyanate, and also the polynuclear homologues of diisocyanatodiphenylmethane known as "polymer-MDI", and also the polyisocyanates having urethane and/or isocyanurate structures obtainable from monomeric <NUM>,<NUM>- and/or <NUM>,<NUM>-TDI by reaction with polyols and/or oligomerization, preferably trimerization, which are obtainable by any known methods, described for example in <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT> or <CIT> or are mixtures of at least two such polyisocyanates, and also those polyisocynanate compounds bearing both aromatic and aliphatic isocyanate groups, for example the mixed trimers or allophanates of <NUM>,<NUM>- and/or <NUM>,<NUM>-TDI with HDI described in <CIT>, <CIT>, <CIT> and <CIT>.

More preferred, the polyisocyanate compound (A) is at least one compound selected from the group consisting of polyisocyanates from the molecular weight range of <NUM>/mol to <NUM>/mol having aliphatically, cycloaliphatically, araliphatically and/or aromatically bonded isocyanate groups, examples being <NUM>,<NUM>-diisocyanatobutane, <NUM>,<NUM>-diisocyanatopentane (pentamethylene diisocyanate, PDI), <NUM>,<NUM>-diisocyanatohexane (hexamethylene diisocyanate, HDI), <NUM>,<NUM>-diisocyanato-<NUM>,<NUM>-dimethylpentane, <NUM>,<NUM>,<NUM>- or <NUM>,<NUM>,<NUM>-trimethyl-<NUM>,<NUM>-diisocyanatohexane, <NUM>,<NUM>-diisocyanatooctane, <NUM>,<NUM>- and <NUM>,<NUM>-diisocyanatocyclohexane, <NUM>,<NUM>- and <NUM>,<NUM>-bis(isocyanatomethyl)cyclohexane, <NUM>-isocyanato-<NUM>,<NUM>,<NUM>-trimethyl-<NUM>-isocyanatomethylcyclohexane (isophorone diisocyanate, IPDI), <NUM>,<NUM>'- and <NUM>,<NUM>'-diisocyanatodicyclohexylmethane (H12-MDI), <NUM>,<NUM>'-diisocyanato-<NUM>,<NUM>-dicyclohexyl propane, or any polyisocyanates having uretdione, isocyanurate, allophanate, biuret, iminooxadiazinedione and/or oxadiazinetrione structure, prepared by modification of simple aliphatic and/or cycloaliphatic diisocyanates, for example those of the type mentioned above, as described for example in <NPL>, in <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT> and <CIT> or in <CIT>, <CIT> and <CIT>, and <NUM>,<NUM>- and <NUM>,<NUM>-bis(isocyanatomethyl)benzene (xylylene diisocyanate, XDI), <NUM>,<NUM>- and <NUM>,<NUM>-bis(<NUM>-isocyanatopropan-<NUM>-yl)benzene (tetramethylxylylene diisocyanate, TMXDI), <NUM>,<NUM>-bis(isocyanatomethyl)-<NUM>-methylbenzene, <NUM>,<NUM>-bis(isocyanatomethyl)-<NUM>-ethylbenzene, <NUM>,<NUM>-bis(isocyanatomethyl)-<NUM>-methylbenzene, <NUM>,<NUM>-bis(iscyanatomethyl)-<NUM>,<NUM>,<NUM>-trimethlybenzene, <NUM>,<NUM>-bis(isocyanatomethyl)-<NUM>,<NUM>-dimethylbenzene, <NUM>,<NUM>-bis(isocyanatomethyl)-<NUM>,<NUM>-dimethylbenzene, <NUM>,<NUM>-bis(isocyanatomethyl)-<NUM>,<NUM>,<NUM>,<NUM>-tetramethylbenzene, <NUM>,<NUM>-bis(isocyanatomethyl)-<NUM>-tert-butylbenzene, <NUM>,<NUM>-bis(<NUM>-isocyanatoethyl)benzene, <NUM>,<NUM>-bis(isocyanatomethyl)naphthalene, <NUM>,<NUM>-, <NUM>,<NUM>- and <NUM>,<NUM>-diisocyanatobenzene (phenylene diisocyanate), <NUM>,<NUM>- and <NUM>,<NUM>-diisocyanatotoluene (toluene diisocyanate, TDI), <NUM>,<NUM>,<NUM>,<NUM>-tetramethyl-<NUM>,<NUM>-diisocyanatobenzene, diisopropylphenylene diisocyanates, diisododecylphenylene diisocyanates and biphenyl diisocyanates, <NUM>,<NUM>'-dimethoxybiphenyl-<NUM>,<NUM>'-diisocyanate, <NUM>,<NUM>'-, <NUM>,<NUM>'- and <NUM>,<NUM>'-diisocyanatodiphenylmethane (MDI), <NUM>,<NUM>'-dimethyl diphenylmethane-<NUM>,<NUM>'-diisocyanate, <NUM>,<NUM>'-diisocyanatodiphenylethane, <NUM>,<NUM>-diisocyanatonaphthalene (NDI), diphenylether diisocyanate, ethylene glycol diphenylether diisocyanate, <NUM>,<NUM>-propylene glycol diphenylether diisocyanate, triisocyanatobenzene, <NUM>,<NUM>,<NUM>-triisocyanatotoluene, trimethylbenzene triisocyanate, <NUM>-methyldiphenylmethane-<NUM>,<NUM>,<NUM>'-triisocyanate, the isomeric naphthalene triisocyanates and methylnaphthalene diisocyanates, triphenylmethane triisocyanate, <NUM>,<NUM>-diisocyanato-<NUM>-[(<NUM>-isocyanato-<NUM>-methylphenyl)methyl]benzene and also the polynuclear homologues of diisocyanatodiphenylmethane known as "polymer-MDI", and also the polyisocyanates having urethane and/or isocyanurate structures obtainable from monomeric <NUM>,<NUM>- and/or <NUM>,<NUM>-TDI by reaction with polyols and/or oligomerization, preferably trimerization, which are obtainable by any known methods, described for example in <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT> or <CIT>, and also those polyisocynanate compounds bearing both aromatic and aliphatic isocyanate groups, for example the mixed trimers or allophanates of <NUM>,<NUM>- and/or <NUM>,<NUM>-TDI with HDI described in <CIT>, <CIT>, <CIT> and <CIT>.

And most preferred, the polyisocyanate compound (A) is at least one compound selected from the group consisting of <NUM>,<NUM>-diisocyanatopentane (pentamethylene diisocyanate, PDI), <NUM>,<NUM>-diisocyanatohexane (hexamethylene diisocyanate, HDI), <NUM>-isocyanato-<NUM>,<NUM>,<NUM>-trimethyl-<NUM>-isocyanatomethylcyclohexane (isophorone diisocyanate, IPDI), <NUM>,<NUM>'- and <NUM>,<NUM>'-diisocyanatodicyclohexylmethane (H12-MDI), and <NUM>,<NUM>- and <NUM>,<NUM>-bis(isocyanatomethyl)benzene (xylylene diisocyanate, XDI), <NUM>,<NUM>- and <NUM>,<NUM>-bis(<NUM>-isocyanatopropan-<NUM>-yl)benzene (tetramethylxylylene diisocyanate, TMXDI), <NUM>,<NUM>'-, <NUM>,<NUM>'- and <NUM>,<NUM>'-diisocyanatodiphenylmethane (MDI), <NUM>,<NUM>'-dimethyl diphenylmethane-<NUM>,<NUM>'-diisocyanate, <NUM>,<NUM>'-diisocyanatodiphenylethane, <NUM>,<NUM>-diisocyanatonaphthalene (NDI).

A mixture of two or more of the aforementioned polyisocyanate compounds (A) can also be used.

As used herein, the term "aromatic polyisocyanate compound" is meant to denote compounds having two or more isocyanate groups and aromatic moieties.

In a more preferred embodiment of the method according to the invention the polyisocyanate compound (A) is an aromatic and/or araliphatic polyisocyanate compound (A-<NUM>).

In a preferred embodiment of the method according to the invention, the aromatic polyisocyanate compound (A-<NUM>) is at least one compound and is selected from the group consisting of araliphatic and/or aromatic diisocyanates and triisocyanateare of the molecular weight range from <NUM>/mol to <NUM>/mol, such as <NUM>,<NUM>- and <NUM>,<NUM>-bis(isocyanatomethyl)benzene (xylylene diisocyanate, XDI), <NUM>,<NUM>- and <NUM>,<NUM>-bis(<NUM>-isocyanatopropan-<NUM>-yl)benzene (tetramethylxylylene diisocyanate, TMXDI), <NUM>,<NUM>-bis(isocyanatomethyl)-<NUM>-methylbenzene, <NUM>,<NUM>-bis(isocyanatomethyl)-<NUM>-ethylbenzene, <NUM>,<NUM>-bis(isocyanatomethyl)-<NUM>-methylbenzene, <NUM>,<NUM>-bis(iscyanatomethyl)-<NUM>,<NUM>,<NUM>-trimethlybenzene, <NUM>,<NUM>-bis(isocyanatomethyl)-<NUM>,<NUM>-dimethylbenzene, <NUM>,<NUM>-bis(isocyanatomethyl)-<NUM>,<NUM>-dimethylbenzene, <NUM>,<NUM>-bis(isocyanatomethyl)-<NUM>,<NUM>,<NUM>,<NUM>-tetramethylbenzene, <NUM>,<NUM>-bis(isocyanatomethyl)-<NUM>-tert-butylbenzene, <NUM>,<NUM>-bis(<NUM>-isocyanatoethyl)benzene, <NUM>,<NUM>-bis(isocyanatomethyl)naphthalene, <NUM>,<NUM>-, <NUM>,<NUM>- and <NUM>,<NUM>-diisocyanatobenzene (phenylene diisocyanate), <NUM>,<NUM>- and <NUM>,<NUM>-diisocyanatotoluene (toluene diisocyanate, TDI), <NUM>,<NUM>,<NUM>,<NUM>-tetramethyl-<NUM>,<NUM>-diisocyanatobenzene, diisopropylphenylene diisocyanates, diisododecylphenylene diisocyanates and biphenyl diisocyanates, <NUM>,<NUM>'-dimethoxybiphenyl-<NUM>,<NUM>'-diisocyanate, <NUM>,<NUM>'-, <NUM>,<NUM>'- and <NUM>,<NUM>'-diisocyanatodiphenylmethane (MDI), <NUM>,<NUM>'-dimethyl diphenylmethane-<NUM>,<NUM>'-diisocyanate, <NUM>,<NUM>'-diisocyanatodiphenylethane, <NUM>,<NUM>-diisocyanatonaphthalene (NDI), diphenylether diisocyanate, ethylene glycol diphenylether diisocyanate, <NUM>,<NUM>-propylene glycol diphenylether diisocyanate, triisocyanatobenzene, <NUM>,<NUM>,<NUM>-triisocyanatotoluene, trimethylbenzene triisocyanate, <NUM>-methyldiphenylmethane-<NUM>,<NUM>,<NUM>'-triisocyanate, the isomeric naphthalene triisocyanates and methylnaphthalene diisocyanates, triphenylmethane triisocyanate, <NUM>,<NUM>-diisocyanato-<NUM>-[(<NUM>-isocyanato-<NUM>-methylphenyl)methyl]benzene and also the polynuclear homologues of diisocyanatodiphenylmethane known as "polymer-MDI", and also the polyisocyanates having urethane and/or isocyanurate structures obtainable from monomeric <NUM>,<NUM>- and/or <NUM>,<NUM>-TDI by reaction with polyols and/or oligomerization, preferably trimerization, which are obtainable by any known methods, described for example in <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT> or <CIT>, and also those polyisocynanate compounds bearing both aromatic and aliphatic isocyanate groups, for example the mixed trimers or allophanates of <NUM>,<NUM>- and/or <NUM>,<NUM>-TDI with HDI described in <CIT>, <CIT>, <CIT> and <CIT>.

In a more preferred embodiment of the method according to the invention, the aromatic polyisocyanate compound (A-<NUM>) is at least one compound and is selected from the group consisting of araliphatic and/or aromatic diisocyanates and triisocyanateare of the molecular weight range from <NUM>/mol to <NUM>/mol, such as <NUM>,<NUM>- and <NUM>,<NUM>-bis(isocyanatomethyl)benzene (xylylene diisocyanate, XDI), <NUM>,<NUM>- and <NUM>,<NUM>-bis(<NUM>-isocyanatopropan-<NUM>-yl)benzene (tetramethylxylylene diisocyanate, TMXDI), <NUM>,<NUM>-bis(isocyanatomethyl)-<NUM>-methylbenzene, <NUM>,<NUM>-bis(isocyanatomethyl)-<NUM>-ethylbenzene, <NUM>,<NUM>-bis(isocyanatomethyl)-<NUM>-methylbenzene, <NUM>,<NUM>-bis(iscyanatomethyl)-<NUM>,<NUM>,<NUM>-trimethlybenzene, <NUM>,<NUM>-bis(isocyanatomethyl)-<NUM>,<NUM>-dimethylbenzene, <NUM>,<NUM>-bis(isocyanatomethyl)-<NUM>,<NUM>-dimethylbenzene, <NUM>,<NUM>-bis(isocyanatomethyl)-<NUM>,<NUM>,<NUM>,<NUM>-tetramethylbenzene, <NUM>,<NUM>-bis(isocyanatomethyl)-<NUM>-tert-butylbenzene, <NUM>,<NUM>-bis(isocyanatomethyl)-<NUM>-chlorobenzene, <NUM>,<NUM>-bis(isocyanatomethyl)-<NUM>,<NUM>-dichlorobenzene, <NUM>,<NUM>-bis(isocyanatomethyl)-<NUM>,<NUM>,<NUM>,<NUM>-tetrachlorobenzene, <NUM>,<NUM>-bis(isocyanatomethyl)-<NUM>,<NUM>,<NUM>,<NUM>-tetrachlorobenzene, <NUM>,<NUM>-bis(isocyanatomethyl)-<NUM>,<NUM>,<NUM>,<NUM>-tetrabromobenzene, <NUM>,<NUM>-bis(<NUM>-isocyanatoethyl)benzene and <NUM>,<NUM>-bis(isocyanatomethyl)naphthalene, <NUM>,<NUM>-, <NUM>,<NUM>- and <NUM>,<NUM>-diisocyanatobenzene (phenylene diisocyanate), <NUM>,<NUM>- and <NUM>,<NUM>-diisocyanatotoluene (toluene diisocyanate, TDI), <NUM>,<NUM>,<NUM>,<NUM>-tetramethyl-<NUM>,<NUM>-diisocyanatobenzene, the isomeric diethylphenylene diisocyanates, diisopropylphenylene diisocyanates, diisododecylphenylene diisocyanates and biphenyl diisocyanates, <NUM>,<NUM>'-dimethoxybiphenyl-<NUM>,<NUM>'-diisocyanate, <NUM>,<NUM>'-, <NUM>,<NUM>'- and <NUM>,<NUM>'-diisocyanatodiphenylmethane (MDI), <NUM>,<NUM>'-dimethyl diphenylmethane-<NUM>,<NUM>'-diisocyanate, <NUM>,<NUM>'-diisocyanatodiphenylethane, <NUM>,<NUM>-diisocyanatonaphthalene (NDI), diphenylether diisocyanate, ethylene glycol diphenylether diisocyanate, diethylene glycol diphenylether diisocyanate, <NUM>,<NUM>-propylene glycol diphenylether diisocyanate, benzophenone diisocyanate, triisocyanatobenzene, <NUM>,<NUM>,<NUM>-triisocyanatotoluene, trimethylbenzene triisocyanate, diphenylmethane-<NUM>,<NUM>,<NUM>'-triisocyanate, <NUM>-methyldiphenylmethane-<NUM>,<NUM>,<NUM>'-triisocyanate, the isomeric naphthalene triisocyanates and methylnaphthalene diisocyanates, triphenylmethane triisocyanate, <NUM>,<NUM>-diisocyanato-<NUM>-[(<NUM>-isocyanato-<NUM>-methylphenyl)methyl]benzene, <NUM>-methyl-diphenylmethane-<NUM>,<NUM>,<NUM>',<NUM>',<NUM>'-pentaisocyanate, and also the polynuclear homologues of diisocyanatodiphenylmethane known as "polymer-MDI", and also the polyisocyanates having urethane and/or isocyanurate structures obtainable from monomeric <NUM>,<NUM>- and/or <NUM>,<NUM>-TDI by reaction with polyols and/or oligomerization, preferably trimerization, which are obtainable by any known methods, described for example in <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT> or <CIT> or are mixtures of at least two such polyisocyanates, and also those polyisocynanate compounds bearing both aromatic and aliphatic isocyanate groups, for example the mixed trimers or allophanates of <NUM>,<NUM>- and/or <NUM>,<NUM>-TDI with HDI described in <CIT>, <CIT>, <CIT> and <CIT>.

In a most preferred embodiment of the method according to the invention, the aromatic polyisocyanate compound (A-<NUM>) is at least one compound and is selected from the group consisting of <NUM>,<NUM>- and <NUM>,<NUM>-bis(isocyanatomethyl)benzene (xylylene diisocyanate, XDI), <NUM>,<NUM>- and <NUM>,<NUM>-bis(<NUM>-isocyanatopropan-<NUM>-yl)benzene (tetramethylxylylene diisocyanate, TMXDI), <NUM>,<NUM>'-, <NUM>,<NUM>'- and <NUM>,<NUM>'-diisocyanatodiphenylmethane (MDI), <NUM>,<NUM>'-dimethyl diphenylmethane-<NUM>,<NUM>'-diisocyanate, <NUM>,<NUM>'-diisocyanatodiphenylethane, <NUM>,<NUM>-diisocyanatonaphthalene (NDI).

A mixture of two or more of the aromatic polyisocyanate compounds (A-<NUM>) can also be used.

As used herein, the term "aliphatic polyisocyanate compound" is meant to denote compounds having two or more isocyanate groups and no aromatic moieties.

In a less preferred embodiment of the method according to the invention the polyisocyanate compound (A) is an aliphatic or cycloaliphatic polyisocyanate (A-<NUM>).

In an embodiment of the method according to the invention, the aliphatic polyisocyanate compound (A-<NUM>) is at least one compound selected from the group consisting of polyisocyanates from the molecular weight range of <NUM>/mol to <NUM>/mol having aliphatically or cycloaliphatically bonded isocyanate groups, examples being <NUM>,<NUM>-diisocyanatobutane, <NUM>,<NUM>-diisocyanatopentane (pentamethylene diisocyanate, PDI), <NUM>,<NUM>-diisocyanatohexane (hexamethylene diisocyanate, HDI), <NUM>-methyl-<NUM>,<NUM>-diisocyanatopentane, <NUM>,<NUM>-diisocyanato-<NUM>,<NUM>-dimethylpentane, <NUM>,<NUM>,<NUM>- or <NUM>,<NUM>,<NUM>-trimethyl-<NUM>,<NUM>-diisocyanatohexane, <NUM>,<NUM>-diisocyanatooctane, <NUM>,<NUM>-diisocyanatodecane, <NUM>,<NUM>-diisocyanatododecane, <NUM>,<NUM>- and <NUM>,<NUM>-diisocyanatocyclohexane, <NUM>,<NUM>- and <NUM>,<NUM>-bis(isocyanatomethyl)cyclohexane, <NUM>-isocyanato-<NUM>,<NUM>,<NUM>-trimethyl-<NUM>-isocyanatomethylcyclohexane (isophorone diisocyanate, IPDI), <NUM>,<NUM>'- and <NUM>,<NUM>'-diisocyanatodicyclohexylmethane (H12-MDI), <NUM>,<NUM>'-diisocyanato-<NUM>,<NUM>-dicyclohexyl propane, <NUM>-isocyanato-<NUM>-methyl-<NUM>(<NUM>)isocyanatomethylcyclohexane, bis(isocyanatomethyl)norbornane, or any polyisocyanates having uretdione, isocyanurate, allophanate, biuret, iminooxadiazinedione and/or oxadiazinetrione structure, prepared by modification of simple aliphatic and/or cycloaliphatic diisocyanates, for example those of the type mentioned above, as described for example in <NPL>, in <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT> and <CIT> or in <CIT>, <CIT> and <CIT> or by mixtures of at least two such polyisocyanates.

More preferred, the aliphatic polyisocyanate compound (A-<NUM>) is at least one compound selected from the group consisting of polyisocyanates from the molecular weight range of <NUM>/mol to <NUM>/mol having aliphatically, cycloaliphatically, araliphatically and/or aromatically bonded isocyanate groups, examples being <NUM>,<NUM>-diisocyanatobutane, <NUM>,<NUM>-diisocyanatopentane (pentamethylene diisocyanate, PDI), <NUM>,<NUM>-diisocyanatohexane (hexamethylene diisocyanate, HDI), <NUM>,<NUM>-diisocyanato-<NUM>,<NUM>-dimethylpentane, <NUM>,<NUM>,<NUM>- or <NUM>,<NUM>,<NUM>-trimethyl-<NUM>,<NUM>-diisocyanatohexane, <NUM>,<NUM>-diisocyanatooctane, <NUM>,<NUM>- and <NUM>,<NUM>-diisocyanatocyclohexane, <NUM>,<NUM>- and <NUM>,<NUM>-bis(isocyanatomethyl)cyclohexane, <NUM>-isocyanato-<NUM>,<NUM>,<NUM>-trimethyl-<NUM>-isocyanatomethylcyclohexane (isophorone diisocyanate, IPDI), <NUM>,<NUM>'- and <NUM>,<NUM>'-diisocyanatodicyclohexylmethane (H12-MDI), <NUM>,<NUM>'-diisocyanato-<NUM>,<NUM>-dicyclohexyl propane, or any polyisocyanates having uretdione, isocyanurate, allophanate, biuret, iminooxadiazinedione and/or oxadiazinetrione structure, prepared by modification of simple aliphatic and/or cycloaliphatic diisocyanates, for example those of the type mentioned above, as described for example in <NPL>, in <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT> and <CIT> or in <CIT>, <CIT> and <CIT> or by mixtures of at least two such polyisocyanates.

And most preferred, the aliphatic polyisocyanate compound (A-<NUM>) is at least one compound selected from the group consisting of <NUM>,<NUM>-diisocyanatopentane (pentamethylene diisocyanate, PDI), <NUM>,<NUM>-diisocyanatohexane (hexamethylene diisocyanate, HDI), <NUM>-isocyanato-<NUM>,<NUM>,<NUM>-trimethyl-<NUM>-isocyanatomethylcyclohexane (isophorone diisocyanate, IPDI), <NUM>,<NUM>'- and <NUM>,<NUM>'-diisocyanatodicyclohexylmethane (H12-MDI).

A mixture of two or more of the aforementioned polyisocyanate compounds (A-<NUM>) can also be used.

As used herein, the term "polyepoxide compound" is meant to denote compounds having two or more epoxide groups
In a preferred embodiment of the invention, the aliphatic polyepoxide compound (B-<NUM>) is one or more compound(s) and is selected from the group consisting of neopentyl glycol diglycidyl ether, hydrogenated bisphenol A diglycidyl ether, <NUM>,<NUM>-cyclohexane dicarboxylic acid diglycidyl ester, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, diethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, dipropylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, glycerol triglycidyl ether, polyglycerol polyglycidyl ether, polyglycidyl ether of ethoxylated trimethylolpropane, poly(tetramethylene-oxid) diglycidyl ether, pentaeritrol polyglycidyl ether, vinylcyclohexene diepoxide, the diepoxides of double unsaturated fatty acid C1 - C18 alkyl esters, polyepoxides of double unsaturated ethoxylated fatty alcohols, Aliphatic di- or polydiglycidyl ether, derived via epoxidation of di- or polyfunctional alcohols with aliphatic linear, aliphatic branched, or cycloaliphatic moieties consisting of <NUM>-<NUM> carbon atoms, for example ethanediol diglycicyl ether, propanediol diglycidyl ether, <NUM>,<NUM>-butanediol diglycidyl ether, <NUM>,<NUM>-hexanediol diglycidyl ether, octanediol diglycidyl ether, trimethylolpropane polyglycidyl ether, glycerol polyethylene triglycidyl ether, <NUM>-ethyl hexyl diglycidyl ether, isosorbide diglycidyl ether.

In a more preferred embodiment of the invention, the aliphatic polyepoxide compound (B-<NUM>) is one or more compound(s) and is selected from the group consisting of hydrogenated bisphenol A diglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, glycerol triglycidyl ether, polyglycidyl ether of ethoxylated trimethylolpropane, poly(tetramethylene-oxid) diglycidyl ether, pentaeritrol polyglycidyl ether, the diepoxides of double unsaturated fatty acid C1 - C18 alkyl estersAliphatic di- or polydiglycidyl ether, derived via epoxidation of di- or polyfunctional alcohols with aliphatic linear, aliphatic branched, or cycloaliphatic moieties consisting of <NUM>-<NUM> carbon atoms, for example ethanediol diglycicyl ether, <NUM>,<NUM>-butanediol diglycidyl ether, <NUM>,<NUM>-hexanediol diglycidyl ether, trimethylolpropane polyglycidyl ether, glycerol polyethylene triglycidyl ether, <NUM>-ethyl hexyl diglycidyl ether, isosorbide diglycidyl ether.

Most preferred the aliphatic polyepoxide compound (B-<NUM>) is one or more compound(s) and is selected from the group consisting of ethanediol diglycidyl ether, butanediole diglycidyl ether, hexane diol diglycidyl ether, trimethylopropane triglycidyl ether.

A mixture of two or more of the aforementioned aliphatic polyepoxide compounds (B-<NUM>) can also be used.

In a first alternative preferred embodiment of the invention the polyisocyanate compound (A) is an aliphatic polyisocyanate compound (A-<NUM>) and the polyepoxide compound (B) is an aliphatic polyepoxide compound (B-<NUM>).

In a third alternative preferred embodiment of the invention the polyisocyanate compound (A) is an aromatic polyisocyanate compound (A-<NUM>) and the polyepoxide compound (B) is an aliphatic polyepoxide compound (B-<NUM>).

A mixture of one or more of the aforementioned aliphatic polyisocyanates (A-<NUM>), aromatic polyisocyanate compound (A-<NUM>), and aliphatic polyepoxide compound (B-<NUM>) can also be used.

In a preferred embodiment of the invention, the molar ratio of epoxy groups of the polyepoxide compound (B) to the isocyanate groups of the polyisocyanate compound (A) is from <NUM>:<NUM> to <NUM>:<NUM>. If the latter molar ratio is higher than <NUM>:<NUM>, resulting epoxy-terminated oxazolidinones, the oxazolidinone group ratio in the overall mixture is diluted by the epoxy compound (B) in such a way that the mixture will not give a significant benefit in the final polymer, compared to only using the epoxy compound (B) in further polymerization applications.

In a preferred embodiment of the invention, the process comprises the steps:.

In an alternative preferred embodiment of the invention, the process comprises the steps:.

In a further alternative, less-preferred embodiment of the invention, the process comprises the steps:.

The conditions for the copolymerization process at elevated temperatures and temperatures are explained above.

In a preferred embodiment of the invention the catalyst (C) is at least one compound selected from the group consisting LiCl, LiBr, LiI and MgCl2.

In a more preferred embodiment of the invention the catalyst (C) is selected from the group consisting of LiCl, LiBr, and LiI.

In a more preferred embodiment of the invention the catalyst (C) is LiCl.

In one embodiment of the method according to the invention, the catalyst (C) is present in a molar amount of <NUM> to ≤ <NUM> mol-%, more preferred ≥ <NUM> to ≤ <NUM> mol-%, based on the polyepoxide compound (B).

A solvent (D) and in particular the solvent (D-<NUM>) is defined in alignment to the general definition as a substance that dissolves a solute, i.e. compound (A), compound (B) and/or compound (C) but does not (chemically) react with compound (A), compound (B) and the catalyst (C), in particular the polyisocyanate compound (A).

According to the inventive process, the copolymerization is operated in the absence of an additional solvent (D-<NUM>) with a boiling point higher than <NUM>, preferred higher than <NUM>, more preferred higher than <NUM>, and most preferred higher than <NUM> at <NUM> bar (absolute).

In the absence of an additional solvent (D-<NUM>) means solvent amounts of (D-<NUM>) of less than <NUM> wt-% preferably <NUM> wt-% more preferably <NUM> wt-%.

These additional solvents (D-<NUM>) are for example organic solvents such as linear or branched alkanes or mixtures of alkanes, mono or polysubstituted halogenated aromatic solvents or halogenated alkane solvents, for example, <NUM>,<NUM>-dichlorobenzene, linear or cyclic ester, or polar aprotic solvents such as cyclic carbonate, such as ethylencarbonate or propylencarbonate, N-methylpyrrolidone (NMP), sulfolane, tetramethylurea, N,N'-dimethylethylenurea or mixtures of the above mentioned solvents and/or with other solvents. These solvents (D-<NUM>) are in particular <NUM>,<NUM>-dichlorobenzene, sulfolane and N-methylpyrrolidone (NMP).

In a preferred embodiment of the invention the copolymerization is operated in the absence of an additional solvent (D) which is an advantage since no additional energy-intensive and time-consuming solvent removal process, e.g. distillation, is necessary.

In an embodiment of the invention the calculated mass ratio of the sum of diisocyanate compound (A), the bisepoxide compound (B), and catalyst (C) with respect to the sum of diisocyanate compound (A), the bisepoxide compound (B), the catalyst (C), and the solvent (D) is in the range from <NUM> wt-% to <NUM> wt-%, preferred from <NUM> wt-% to <NUM> wt-% and more preferred from <NUM> wt-% to <NUM> wt-%. The upper mass ratio of <NUM> wt-% means applying no solvent (D), and leads to a most energy-efficient process since no solvent needs to be separated. The lower mass ratio of <NUM> wt-% leads to higher amount of solvent (D) optionally comprising that needs to be separated and potentially purified. This leads to a less efficient overall process due to no energy savings.

Another aspect of the present invention is an epoxy-group terminated polyoxazolidinone, obtainable by a method according to the invention.

In an embodiment of the invention, the polyoxazolidinones have epoxy equivalent weights (EEW) of from <NUM>/eq to <NUM>/eq, preferable of from <NUM>/eq to <NUM>/eq more preferred of from <NUM>/eq to <NUM>/eq, wherein the epoxy equivalent weight was measured with a Metrohm <NUM> Titrando using a potentiometric hydrochloric acid titration. The epoxy sample was added to a <NUM> beaker and then mixed with tetrabutylammonium bromide (TBAB) in glacial acetic acid (<NUM>/L). Then the solution was titrated with a peracetic acid (<NUM> mol/L) until after the equivalent point.

The epoxy-equivalent weight (EEW) of the polyoxazolidinone-group containing prepolymers is defined as the total mass of the substance that contains <NUM> equivalent of epoxy groups.

The present invention will be further described with reference to the following examples without wishing to be limited by them.

MDI, LiCl, BDDE were used as received without further purification. Sulfolane was used after melting at <NUM> and drying over molecular sieves. o-DCB were dried over molecular sieves prior to use.

Batch Protocol: All components are weighted into a glass flask, which is put into an oil bath pre-heated to <NUM> and stirred immediately.

Semi-batch Protocol: The catalyst (C) and diepoxide (B) are provided in a glass flask and heated to <NUM>. The diisocyanate compound is added to the reactor containing the catalyst (C) dissolved in the diepoxide compound while the mixture is continuously stirred.

IR analyses were performed on a Bruker ALPHA-P IR spectrometer equipped with a diamond probe head. The software OPUS <NUM> was used for data treatment. A background spectrum was recorded against ambient air. Thereafter, a small sample of the polyoxazolidinone prepolymer (<NUM>) was applied to the diamond probe and the IR spectrum recorded averaging over <NUM> spectra obtained in the range of <NUM> to <NUM>-<NUM> with a resolution of <NUM>-<NUM>.

The epoxy equivalent weight was measured with a Metrohm <NUM> Titrando using a potentiometric hydrochloric acid titration. The epoxy sample was added to a <NUM> beaker and then mixed with tetrabutylammonium bromide (TBAB) in glacial acetic acid (<NUM>/L). Then the solution was titrated with a peracetic acid (<NUM> mol/L) until after the equivalent point.

GPC measurements were performed at <NUM> in tetrahydrofuran (THF, flow rate of <NUM> min-<NUM>). The column set consisted of <NUM> consecutive columns (PSS SDV, <NUM>, 8x50 mm precolumn, <NUM> PSS SDV linear S, <NUM>, 8x300 mm). Samples (concentration <NUM>-<NUM> L-<NUM>, injection volume <NUM>µL) were injected employing an Agilent technologies <NUM> series auto sampler. An RID detector of the Agilent <NUM> series was used to follow the concentration at the exit of the column. Raw data were processed using the PSS WinGPC Unity software package. Polystyrene of known molecular weight was used as reference to calculate the molecular weight distribution (PSS ReadyCal Kit in an area of <NUM> Da to <NUM> Da was used). The number average molecular weight measured by GPC is denominated as Mn(GPC) in the examples.

The Gardner color index was determined by using a Lico <NUM> from Hach. Therefore, sample of the product mixture was filled into a cuvette which was subsequently analyzed following the DIN EN ISO <NUM>.

The viscosity values were determined via a cone/plate rheometer from Anton Paar MCR <NUM>. A ramp of shear rates reaching from <NUM> - <NUM><NUM>/min was used to determine the viscosity of the products. The viscosity is given in the unit mPa·s, following the procedure according to DIN EN ISO <NUM>/A.

Under a continuous flow of argon, the reactions were performed in a <NUM> two-neck round-bottom flask. A syringe pump (KD Scientific Inc. ) was connected to the flask to add the diisocyanate compound to the catalyst (C) dissolved in the diepoxide compound.

Example <NUM>: Synthesis of epoxy-terminated polyoxazolidinone-based prepolymers with Araldite DY-D/CH as compound (B-I) and with MDI <NUM> as compound (A) using LiCl as compound (C) according to the Batch Protocol with molar ratio of epoxy groups to isocyanate groups of <NUM>:<NUM>.

A reactor as previously described was charged with LiCl (<NUM>, <NUM> mmol), MDI <NUM> (<NUM>, <NUM> mmol) and Araldite DY-D/CH (<NUM>, <NUM> mmol BDDE). The reactor was closed and inertized with argon. The mixture was stirred (<NUM> rpm) and heated to <NUM>. After <NUM>, the reaction mixture was allowed to cool to room temperature.

The completion of the reaction was confirmed by the absence of the isocyanate band (<NUM>-<NUM>) in the IR spectrum from the reaction mixture.

In the IR spectrum the characteristic signal for the oxazolidinone carbonyl group was observed at <NUM>-<NUM> as it can be seen in <FIG>.

In the IR spectrum the characteristic signal for isocyanurate groups was not observed as it can be seen in <FIG>.

The analysis of the molecular weight with GPC showed an average molecular weight of <NUM>·mol-<NUM> and a Polydispersity Index of <NUM>.

The color index was determined to be <NUM> on the Gardner scale.

The viscosity of the product was determined to be <NUM> mPa·s.

Example <NUM>: Synthesis of epoxy-terminated polyoxazolidinone-based prepolymers with Araldite DY <NUM> as compound (B-II) and with MDI <NUM> as compound (A) using LiCl as compound (C) according to the Batch Protocol with molar ratio of epoxy groups to isocyanate groups of <NUM>:<NUM>.

A reactor as previously described was charged with LiCl (<NUM>, <NUM> mmol), MDI <NUM> (<NUM>, <NUM> mmol) and Araldite DY <NUM> (<NUM>, <NUM> mmol BDDE). The reactor was closed and inertized with argon. The mixture was stirred (<NUM> rpm) and heated to <NUM>. After <NUM>, the reaction mixture was allowed to cool to room temperature.

In the IR spectrum the characteristic signal for the oxazolidinone carbonyl group was observed at <NUM>-<NUM>.

In the IR spectrum the characteristic signal for isocyanurate groups was not observed.

Example <NUM>: Synthesis of epoxy-terminated polyoxazolidinone-based prepolymers with Araldite DY/D-CH as compound (B-I) and with MDI <NUM> as compound (A) using LiCl as compound (C) according to the Semi-Batch Protocolwith molar ratio of epoxy groups to isocyanate groups of <NUM>:<NUM>.

A reactor as previously described was charged with LiCl (<NUM>, <NUM> mmol) and Araldite DY/D-CH (<NUM>, <NUM> mmol BDDE). The reactor was closed an inertized with argon. The mixture was stirred (<NUM> rpm) and heated to <NUM>. After <NUM> minutes at this temperature, MDI <NUM> (<NUM>, <NUM> mmol) as compound (A) was added at a rate of <NUM>/min. After <NUM>, the reaction mixture was allowed to cool to room temperature.

Example <NUM>: Synthesis of epoxy-terminated polyoxazolidinone-based prepolymers with Araldite DY-D/CH as compound (B-I) and with MDI <NUM> as compound (A) using LiCl as compound (C) according to the Batch Protocol with molar ratio of epoxy groups to isocyanate groups of <NUM>:<NUM> in the presence of a mixture of ortho-dichlorobenzene and sulfolane as compound (D).

A reactor as previously described was charged with LiCl (<NUM>, <NUM> mmol), MDI <NUM> (<NUM>, <NUM> mmol), Araldite DY-D/CH (<NUM>, <NUM> mmol BDDE) ortho-dichlorobenzene (<NUM>) and sulfolane (<NUM>). The reactor was closed and inertized with kargon. The mixture was stirred (<NUM> rpm) and heated to <NUM>. After <NUM>, the reaction mixture was allowed to cool to room temperature. The completion of the reaction was confirmed by the absence of the isocyanate band (<NUM>-<NUM>) in the IR spectrum from the reaction mixture.

In order to remove the solvent, the mixture was heated to <NUM>, above the boiling point of o-DCB, for <NUM>. In the course of this treatment, the sample turned highly viscous and showed an intensified color.

The analysis of the molecular weight with GPC showed an average molecular weight of <NUM>·mol-<NUM> and a Polydispersity Index of <NUM> before the distillation and an average molecular weight of <NUM>·mol-<NUM> and a Polydispersity Index of <NUM> after the distillation.

The color index was determined to be <NUM> on the Gardner scale before distillation and <NUM> on the Garndner scale after distillation.

The viscosity of the product was determined to be <NUM> mPa·s before the distillation and <NUM> mPa·s after the distillation.

Example <NUM> (Comparative): Synthesis of epoxy-terminated polyoxazolidinone-based prepolymers with Araldite DY/D-CH as compound (B-I) and with MDI <NUM> as compound (A) using LiCl as compound (C) according to the Batch Protocol with molar ratio of epoxy groups to isocyanate groups of <NUM>:<NUM>.

Example <NUM>: Synthesis of epoxy-terminated polyoxazolidinone-based prepolymers with Araldite DY/D-CH as compound (B-I) and with MDI <NUM> as compound (A) using LiCl as compound (C) according to the Batch Protocol with molar ratio of epoxy groups to isocyanate groups of <NUM>:<NUM>.

A reactor as previously described was charged with LiCl (<NUM>, <NUM> mmol), MDI <NUM> (<NUM>, <NUM> mmol) and Araldite DY-D/CH (<NUM>, <NUM> mmol BDDE). The reactor was closed and inertized with argon. The mixture was stirred (<NUM> rpm) and heated to <NUM>. After <NUM> minutes, the reaction was stopped due to solidification of the reaction mixture.

In the IR spectrum the characteristic signal for the oxazolidinone carbonyl group was observed at <NUM>-<NUM>, along with a lot of other peaks indicating side products as it can be seen in <FIG>.

In the IR spectrum the characteristic signal for the oxazolidinone carbonyl group was observed at <NUM>-<NUM> while the signal at <NUM>-<NUM> can be assigned to urethane carbonyl moiety and the signal at <NUM>-<NUM> to the carbonyl group of formed isocyanurate as it can be seen in <FIG>.

The determination of the EEW was not possible.

The analysis of the molecular weight with GPC was not possible.

The color index was determined to be ><NUM> and consequently out of the range of the Gardner scale.

Example <NUM> (Comparative): Synthesis of epoxy-terminated polyoxazolidinone-based prepolymers with Araldite DY-D/CH as compound (B-I) and with MDI <NUM> as compound (A) using DMC as compound (C) according to the Batch Protocol with molar ratio of epoxy groups to isocyanate groups of <NUM>:<NUM>.

A reactor as previously described was charged with DMC (<NUM>), MDI <NUM> (<NUM>, <NUM> mmol) and Araldite DY-D/CH (<NUM>, <NUM> mmol BDDE). The reactor was closed and inertized with argon. The mixture was stirred (<NUM> rpm) and heated to <NUM>. After <NUM>, the reaction mixture was allowed to cool to room temperature.

Example <NUM> (Comparative): Synthesis of epoxy-terminated polyoxazolidinone-based prepolymers with Araldite DY-D/CH as compound (B-I) and with MDI <NUM> as compound (A) using DMC as compound (C) according to the Batch Protocol with molar ratio of epoxy groups to isocyanate groups of <NUM>:<NUM> (analogue to example <NUM> but with an increased catalyst concentration).

A reactor as previously described was charged with DMC (<NUM>,) MDI <NUM> (<NUM>, <NUM> mmol) and Araldite DY-D/CH (<NUM>, <NUM> mmol BDDE). The reactor was closed and inertized with argon. The mixture was stirred (<NUM> rpm) and heated to <NUM>. After <NUM>, the reaction mixture was allowed to cool to room temperature.

The color index could not be determined as the product sample was inhomogeneous and turbid.

The viscosity of the product could not be determined as the product sample was too inhomogeneous.

Example <NUM>: Synthesis of epoxy-terminated polyoxazolidinone-based prepolymers with Araldite DY-D/CH as compound (B-I) and with MDI <NUM> as compound (A) using Tetraphenylphosphonium bromide as compound (C) according to the Batch Protocol with molar ratio of epoxy groups to isocyanate groups of <NUM>:<NUM>.

A reactor as previously described was charged with Ph<NUM>PBr (<NUM>, <NUM> mmol), MDI <NUM> (<NUM>, <NUM> mmol) and Araldite DY-D/CH (<NUM>, <NUM> mmol BDDE). The reactor was closed and inertized with argon. The mixture was stirred (<NUM> rpm) and heated to <NUM>. After <NUM>, the reaction mixture was allowed to cool to room temperature.

In the IR spectrum the characteristic signal for the oxazolidinone carbonyl group was observed at <NUM>-<NUM> while the signal at <NUM>-<NUM>.

The viscosity of the product was determined to be <NUM> mPa·s.

Claim 1:
A process for producing an epoxy-group terminated polyoxazolidinone comprising the copolymerization of a polyisocyanate compound (A) with two or more isocyanate groups with a polyepoxide compound (B) with two or more epoxy groups in the presence of a catalyst (C);
, wherein the polyepoxide compound (B) is an aliphatic polyepoxide compound (B-<NUM>);
wherein the molar ratio of the epoxy groups of the polyepoxide compound (B) to the isocyanate groups of the polyisocyanate compound (A) is from <NUM>:<NUM> and less than <NUM>:<NUM>;
wherein the catalyst (C) is at least one compound selected from the group consisting of LiCl, LiBr, LiI, MgCl<NUM>, MgBr2, MgI2, SmI3, Ph4SbBr, Ph4SbCl, Ph4PBr, Ph4PCl, Ph3(C6H4-OCH3)PBr, Ph3(C6H4-OCH3)PCl, Ph3(C6H4F)PCl, and Ph3(C6H4F)PBr;
, wherein the catalyst (C) is used in a molar amount of <NUM> to <NUM> mol-%, based on the polyepoxide compound (B);
and wherein the copolymerization is operated in the absence of an additional solvent (D-<NUM>) with a boiling point higher than <NUM>, preferred higher than <NUM>, more preferred higher than <NUM>, and most preferred higher than <NUM> at <NUM> bar (absolute).