EP3237476A1 - Oxazolidinone- and isocyanurate-crosslinked matrix for fibre-reinforced material - Google Patents

Abstract

The present invention relates to a method for producing a cured composition, which has at least one oxazolidinone ring and at least one isocyanurate ring and is crosslinked thereby, starting from a liquid reaction mixture comprising: (a) at least one liquid, aromatic epoxy resin; (b) at least one liquid, aromatic polyisocyanate; and (c) a catalyst composition; relative to the at least one polyisocyanate, the at least one epoxy resin is used in amounts such that the molar equivalent ratio of epoxide groups to isocyanate groups is at least 0.4; and curing the reaction mixture to give a cured polymer composition comprising at least one oxazolidinone ring and at least one isocyanurate ring, and also to the cured compositions obtainable by these methods.

Description

 "Oxazolidinone and Isocyanurate Crosslinked Matrix for Fiber Reinforced Material"

The present invention relates to a process for the preparation of a cured composition comprising and crosslinked by at least one oxazolidinone ring and at least one isocyanurate ring starting from a reaction mixture containing at least one epoxide, at least one isocyanate and a catalyst, and the resulting cured composition.

Although commercially available resin systems which have high glass transition temperatures are suitable for the production of moldings capable of withstanding the high temperatures encountered in electrophoretic deposition (dip coating), they are disadvantageous because of low stabilities during storage and long curing cycles.

International Patent Publication WO 2008/147641 describes solid polyepoxide and polyisocyanate based resin systems which upon curing form oxazolidinone and isocyanurate rings. However, these resin systems have the disadvantage of not being applicable to the commonly used RTM processes which require liquid resin systems.

Since such moldings, in particular carbon fiber reinforced plastic parts, are used in the automotive industry, there is a need for polymer systems which overcome the known disadvantages but nevertheless have the required mechanical properties.

The present invention is based on the discovery of the inventors that when using stable at room temperature polyepoxide or polyisocyanate monomers with low viscosity in certain ratios in short curing cycles oxazolidinone and isocyanurate-crosslinked plastics can be produced which have high glass transition temperatures and therefore in manufacturing processes, in which these plastics are exposed to high temperatures, can be used. The plastics thus obtainable also show advantageous mechanical properties, in particular high impact strength, which are suitable for use in the automotive industry. Furthermore, the performance and properties of the polymers thus obtainable can be varied over a wide range by controlling the curing conditions and the type of catalyst systems. Finally, such systems are also advantageous in that they remain stable at room temperature and therefore do not need to be refrigerated.

It has now surprisingly been found that reaction mixtures containing at least one liquid, aromatic epoxy resin, at least one liquid, aromatic polyisocyanate, and a suitable catalyst compositions comprise, upon curing, oxazolidinone- and isocyanurate-crosslinked polymer compositions which have a high glass transition temperature and a high mechanical resistance and are therefore particularly suitable for the production of automotive parts, in particular fiber-reinforced plastic moldings.

The present invention therefore relates, in a first aspect, to a process for the preparation of a cured polymer composition comprising at least one oxazolidinone ring and at least one isocyanurate ring, which process comprises the steps:

 (1) providing a liquid reaction mixture comprising

 (a) at least one liquid, aromatic epoxy resin;

 (b) at least one liquid, aromatic polyisocyanate; and

(c) a catalyst composition;

 wherein the at least one epoxy resin is used in amounts based on the at least one polyisocyanate such that the molar equivalent ratio of epoxy groups to isocyanate groups is at least 0.4, in particular at least 0.7, more preferably at least 1, even more preferably 1: 1; and;

 (2) curing the reaction mixture to obtain a cured polymer composition comprising at least one oxazolidinone ring and at least one isocyanurate ring.

The present invention in a further aspect relates to a cured composition obtainable by the methods described herein.

"At least one" as used herein refers to 1 or more, for example, 1, 2, 3, 4, 5, 6, 7, 8, 9 or more. It refers to constituents of the catalyst compositions described herein Specification not on the absolute amount of molecules but on the nature of the component. "At least one epoxy resin" therefore means, for example, one or more different epoxy resins, ie one or more different types of epoxy resins. Together with quantities, the quantities refer to the total amount of the corresponding designated type of ingredient as defined above.

"Liquid" as used herein refers to flowable compositions at room temperature (20 ° C) and normal pressure (1013 mbar).

In particular, the viscosity of the liquid composition described herein is low enough for the composition to be pumpable and, for example, to wet and impregnate fiber materials as used for fiber reinforced plastic parts. In various embodiments, the reaction mixture at a temperature of 120 ° C has a viscosity of <100 mPas. To determine the viscosity, the resin mixture is prepared at room temperature with a suitable mixer and determined on a plate / plate rheometer in oscillation, the viscosity with increasing temperature at a heating rate of 50 K / min.

The epoxy resin may comprise epoxy group-containing monomers, prepolymers and polymers, as well as mixtures of the abovementioned and is also referred to below as epoxy or epoxide group-containing resin. Suitable epoxy-group-containing resins are in particular resins having 1 to 10, preferably 2 to 10 epoxide groups per molecule. "Epoxide groups" as used herein refers to 1,2-epoxide groups (oxiranes).

The epoxy resins usable herein may vary and include conventional and commercially available epoxy resins, each of which may be used individually or in combination of two or more different epoxy resins. In selecting the epoxy resins, not only the properties of the final product but also the properties of the epoxy resin, such as the viscosity and other properties that affect processability, play a role.

The epoxy group-containing resin is a liquid, aromatic epoxy compound. Examples of suitable resins include, but are not limited to, (poly) glycidyl ethers commonly obtained by reacting epichlorohydrin or epibromohydrin with polyphenols in the presence of alkali, or also (poly) glycidyl ethers of phenol-formaldehyde novolak resins, alkyl-substituted Phenol-formaldehyde resins (epoxy novolac resins), phenol-hydroxybenzaldehyde resins, cresol-hydroxybenzaldehyde resins, dicyclopentadiene-phenolic resins, and dicyclopentadiene-substituted phenolic resins. Suitable polyphenols for this purpose are, for example, resorcinol, pyrocatechol, hydroquinone, bisphenol A (2,2-bis (4-hydroxyphenyl) propane), bisphenol F (bis (4-hydroxyphenyl) methane), 1, 1-bis (4-hydroxyphenyl ) isobutane, 4,4-dihydroxybenzophenone, 1, 1-bis (4-hydroxyphenyl) ethane and 1, 5-hydroxynaphthalene. Also suitable are diglycidyl ethers of ethoxylated resorcinol (DGER), diglycidyl ether of resorcinol, catechol, hydroquinone, bisphenol, bisphenol A, bisphenol AP (1,1-bis (4-hydroxyphenyl) -1-phenylethane), bisphenol F, bisphenol K, bisphenol S, and tetramethylbiphenol.

Other suitable epoxy resins are known in the art and can be found, for example, Lee H. & Neville, K., Handbook of Epoxy Resins, McGraw-Hill Book Company, 1982 Reissue. Particularly preferred epoxy group-containing compounds are aromatic glycidyl ethers, in particular diglycidyl ethers, very particularly preferably those based on aromatic glycidyl ether monomers. Examples include, without limitation, di- or polyglycidyl ethers of polyhydric phenols which can be obtained by reacting a polyhydric phenol with an excess of chlorohydrin such as epichlorohydrin. Such polyhydric phenols include resorcinol, bis (4-hydroxyphenyl) methane (bisphenol F), 2,2-bis (4-hydroxyphenyl) propane (bisphenol A), 2,2-bis (4'-hydroxy-3 ', 5' -dibromophenyl) propane, 1,1,2,2-tetrakis (4'-hydroxyphenyl) ethane or condensates of phenols with formaldehyde obtained under acidic conditions, such as phenol novolacs and cresol novolacs.

Diglycidyl ethers of bisphenol A are available, for example, as DER 331 (liquid bisphenol A epoxy resin) and DER 332 (diglycidyl ether from bisphenol A) from Dow Chemical Company, Midland, Michigan. Although not specifically mentioned, other epoxy resins available under the trade names DER and DEN from Dow Chemical Company may also be used.

The polyisocyanate contains two or more isocyanate groups and includes any known and suitable for the purpose of the invention isocyanate and is hereinafter also referred to in part as isocyanate or isocyanate group-containing resin.

As polyisocyanates in the polyisocyanate component, isocyanates having two or more isocyanate groups are suitable. The polyisocyanates preferably contain 2 to 10, preferably 2 to 5, preferably 2 to 4, in particular exactly 2 isocyanate groups per molecule. The use of isocyanates having a functionality of more than two may under certain circumstances be advantageous since such polyisocyanates are suitable as crosslinking agents.

As the at least one polyisocyanate of the polyisocyanate component, an aromatic polyisocyanate will be used. In an aromatic polyisocyanate, the NCO groups are attached to aromatic carbon atoms. Examples of suitable aromatic polyisocyanates are 1,5-naphthylene diisocyanate, 2,4'-, 2,2'- or 4,4'-diphenylmethane diisocyanate (MDI), xylylene diisocyanate (XDI), m- and p-tetramethylxylylene diisocyanate (TMXDI), 2 , 4- or 2,6-tolylene diisocyanate (TDI), di- and tetraalkyldiphenyl-methane diisocyanate, 3,3'-dimethyl-diphenyl-4,4'-diisocyanate (TODI) 1, 3-phenylene diisocyanate, 1, 4-phenylene diisocyanate, 4,4'-Dibenzyl diisocyanate.

The polyisocyanate component may also contain portions of low molecular weight prepolymers, for example reaction products of MDI or TDI with low molecular weight diols or triols such as ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, triethylene glycol, glycerol or trimethylolpropane. These prepolymers can be prepared by reacting an excess of monomeric polyisocyanate in the presence of diols of the triols. The number average molecular weight of the diols and triols is generally below 1000 g / mol. Optionally, the reaction product can be freed by distillation of monomeric aromatic isocyanates.

Preferably, the at least one polyisocyanate has an NCO content of more than 25% by weight, more preferably more than 28% by weight, particularly preferably more than 30% by weight, particularly preferably from 30 to 50% by weight, based on the at least one polyisocyanate, on. When using only one polyisocyanate, the proportion by mass refers to the amount of this polyisocyanate used, whereas, when using a mixture of polyisocyanates, it refers to the amount of the mixture of these polyisocyanates used.

Preferably, the at least one polyisocyanate has a viscosity of less than 80 mPas, in particular from 30 to 60 mPas (DIN ISO 2555, Brookfield Viscometer RVT, Spindle No. 3, 25 ° C, 50 rpm).

It is particularly preferred that the at least one polyisocyanate has a number average molecular weight of less than 1500 g / mol, more preferably less than 1000 g / mol.

Particularly suitable isocyanate group-containing resins are methylenediphenyl diisocyanate (MDI), toluene-2,4-diisocyanate (TDI), polymeric diphenylmethane diisocyanate (PMDI), and mixtures of the foregoing. These polyisocyanates are commercially available, for example, under the brand name Desmodur from Bayer AG (DE) and Desmodur® N3300.

Particularly preferred are aromatic polyisocyanate monomers, in particular aromatic diisocyanates such as MDI and TDI.

It is generally preferred that both the epoxides used and the isocyanates used are monomers, in particular at standard conditions (20 ° C., 1013 mbar), liquid, low-viscosity monomers. These are particularly advantageous because they are compared to other, high molecular weight epoxy resins significantly more stable, especially storage stable, and must not be stored refrigerated.

In various embodiments of the invention, the reaction mixture may contain a plurality of different epoxide group-containing compounds and / or a plurality of different isocyanate group-containing compounds. The weight ratio of the at least one epoxy resin and the at least one polyisocyanate can be varied and depends on the particular compounds used and their chemical and physical properties and on the desired physical and chemical properties of the cured composition. In general, the epoxide is used in amounts such that the molar equivalent ratio of epoxide to isocyanate groups is at least 0.4, in particular at least 0.7, more preferably at least 1. The molar equivalent ratio is formed as the ratio of epoxide groups to isocyanate groups, with a double number of epoxide groups to isocyanate groups corresponding to a molar equivalent ratio of 2. A molar equivalent ratio of at least 0 4 therefore means, for example, that at most 2.5 mol of isocyanate groups are present per mol of epoxide groups, Preferably, the molar equivalent ratio of epoxide to isocyanate groups is between 0.4 and 5, in particular between 0.5 and 3, more preferably between 0.7 and 2, more preferably between 0.9 and 1.5 The inventors have found that the use of such proportions gives particularly advantageous properties in terms of glass transition temperature, modulus of elasticity and impact strength.

As another ingredient, the reaction mixture comprises a catalyst composition. In various embodiments, the catalyst composition does not include curing agents, i. Compounds that undergo an epoxide polyaddition reaction, such as dicyandiamide, DDS (diaminodiphenyl sulfone) and similar compounds, but only compounds that catalyze the polymerization of polyisocyanate and epoxide. The reaction mixture is therefore in preferred embodiments free of dicyandiamide or DDS, preferably a total of free of curing agents such as dicyandiamide or DDS.

"Free from" as used in this context means that the amount of the corresponding substance in the reaction mixture is less than 0.05% by weight, preferably less than 0.01% by weight, more preferably less than 0.001% by weight. %, based on the total weight of the reaction mixture.

The catalyst composition may contain one or more catalysts. In various embodiments, it is useful for forming oxazolidinone and isocyanurate rings from the indicated ingredients.

The catalyst composition may, in various embodiments, contain at least one nitrogen-containing base.

In preferred embodiments, the base is an ionic compound of formula (I).

 Formula (I)

Ri and R3 in formula (I) are each independently selected from the group consisting of substituted or unsubstituted, linear or branched alkyl of 1 to 20 carbon atoms, substituted or unsubstituted, linear or branched alkenyl of 3 to 20 carbon atoms, and substituted or unsubstituted Aryl having 5 to 20 carbon atoms. Preferably, Ri and R3 are selected from the group consisting of substituted or unsubstituted, linear or branched alkyl of 1 to 10 carbon atoms and substituted or unsubstituted aryl of 5 to 10 carbon atoms.

The radicals R4 and R5 are each independently selected from the group consisting of hydrogen, substituted or unsubstituted, linear or branched alkyl of 1 to 20 carbon atoms, substituted or unsubstituted, linear or branched alkenyl of 3 to 20 carbon atoms, substituted or unsubstituted, linear or branched alkoxy of 1 to 20 carbon atoms and substituted or unsubstituted aryl of 5 to 10 carbon atoms. Preferably, R4 and R5 in formula (I) are hydrogen.

In various embodiments, (i) Ri and R5 and / or R3 and R4 or (ii) R4 and R5 may be taken together with the carbon or nitrogen atoms to which they are attached a 5-6 membered substituted or unsubstituted cycloalkyl, cycloheteroalkyl, Aryl or heteroaryl ring, wherein the cycloheteroalkyl or heteroaryl ring contains 1 to 3 heteroatoms selected from O, N and S, form. Thus, in certain embodiments, both Ri and R5 and R3 and R4 may combine with each other to form a ring. However, it is preferred that R4 and R5 combine together, particularly to form a 6-membered aryl ring, such that the resulting compound is a benzimidazolium or a benzimidazolidinium.

The anion X of the formula (I) may be any known anion suitable for the purpose according to the invention and may merely serve for charge balance of the cation of the ionic compound of the formula (I). It may be advantageous if the anion has no chelating properties. In a preferred embodiment, X is selected from the group consisting of dicyandiamide anion, F, Cr, Br, I ^" , OH ^" , HSOs-, S0 ₃ ^2_ , S0 ₄ ^2_ , N0 ₂ ^" , NO 3 -, P0 ₄ ^3_ , BF ₄ ^" , PF ₆ ^" , CIO 4 ^" , acetate, citrate, formate, glutarate, lactate, malate, malonate, oxalate, pyruvate, tartrate, cyanocyanamide (This anion is included in the disclosure of the invention, please check = cyanamide?), SCN ^" and P (OEt) 202 ^" . In a particularly preferred embodiment, X is selected from the group consisting of Cr, Br, I ^" , S0 ₄ ^2" , N0 ₂ ^" , N0 ₃ ^" , Ρ0 ₄ ^{3 "} , BF ₄ ^" , SbF ₆ ^" PF ₆ ^" , ClO , Acetate, cyanocyanamide (see above), SCN ^" and P (OEt) ₂ 0 ₂ -.

"" Represents a single or double bond, in particular a double bond.

The index n is 1, 2 or 3.

In the catalyst compositions described herein, several different ionic compounds of formula (I) may be included.

"Alkyl" as used herein refers to linear or branched alkyl groups such as methyl, ethyl, n-propyl and iso-propyl The alkyl groups may be substituted or unsubstituted but are preferably unsubstituted Substituents in particular selected from the group consisting of Ce-ιο aryl, -OR, -NRR ', wherein R and R' may each be independently H or unsubstituted C1-10 alkyl.

"Alkenyl" as used herein refers to linear or branched alkenyl groups containing at least one C =C double bond, such as ethenyl, n-propenyl, iso-propenyl, and n-butenyl The alkenyl radicals may be substituted or unsubstituted but preferably unsubstituted, when substituted, the substituents are especially selected from the group consisting of Ce-ιο aryl, -OR, -NRR ', where R and R' may each independently be H or unsubstituted C 1-10 alkyl.

"Aryl" as used herein refers to aromatic groups which may have at least one aromatic ring, but may also have multiple condensed rings, such as phenyl, naphthyl, anthracenyl, etc. The aryl groups may be substituted or unsubstituted , the substituents are selected from the group consisting of C 1-10 alkyl, C 2-10 alkenyl, -OR, -NRR ', where R and R' may each independently be H or unsubstituted C 1-10 alkyl.

In various embodiments of the invention, the compound of formula (I) is a 1,3-substituted imidazolium compound, ie R2, R4 and R5 are hydrogen. The substituents R 1 and R _{3 are} preferably selected from unsubstituted C 1-4 -alkyl radicals, in particular methyl and ethyl, ie the compounds are, for example, 1-ethyl-3-methylimidazolium compounds or unsubstituted or substituted C ₆ -aryl radicals, in particular phenyl substituted with one or more C 1-4 alkyl substituents, such as, for example, 2,6-diisopropylphenyl.

The anion may be in particular acetate, chloride, thiocyanate, diethyl phosphate or dicayanamide.

In various embodiments, the compound of formula (I) is selected from 1-ethyl-3-methyl-1H-imidazolium acetate, 1-ethyl-3-methyl-1H-imidazolium thiocyanate, 1-ethyl-3-methyl-1H- Imidazolium cyanocyanamide, 1-ethyl-3-methyl-1H-imidazolium diethyl phosphate and 1,3-bis (2,6-diisopropylphenyl) -1H-imidazolidinium chloride.

In various other embodiments, the base used as a catalyst is a nonionic nitrogen-containing base containing at least one tertiary nitrogen atom and / or one imine nitrogen atom.

The term "tertiary" as used herein indicates that to the nitrogen atom contained in the at least one base, three organic moieties are covalently bonded via single bonds.

Alternatively, the at least one base may contain an imine nitrogen atom. The term "imines" as used herein refers to the known class of compounds and indicates that the nitrogen atom has a covalent double bond to an organic radical and a single covalent bond to another organic radical. Imines are Schiff bases.

The catalyst composition may, in various embodiments, contain several of the nonionic bases described above, for example a base with an imine nitrogen and a base with a tertiary nitrogen atom. The nonionic base may also be both a tertiary amine and an imine containing both a tertiary nitrogen atom and an imine nitrogen.

In various embodiments, the at least one nonionic base is a tertiary amine of (II) NReR / Rs and / or an imine of the formula (III)

The radicals R6 to Rs and R10 are each independently selected from the group consisting of substituted or unsubstituted, linear or branched alkyl of 1 to 20 carbon atoms, substituted or unsubstituted, linear or branched alkenyl of 3 to 20 carbon atoms and substituted or unsubstituted aryl 5 to 20 carbon atoms, or at least two of R6 to Rs together with the nitrogen atom to which they are attached form a 5- to 10-membered heteroalicyclic ring or heteroaryl ring, which optionally contains one or more further nitrogen atoms, in particular 1 further nitrogen atom.

R9 is a substituted or unsubstituted, linear or branched alkylenyl having from 3 to 20 carbon atoms, or R9 and R10 together with the nitrogen atom to which they are attached form a 5- to 10-membered heteroalicyclic ring or heteroaryl ring, optionally further Contains nitrogen atoms ..

"Alkylenyl" as used herein refers to an alkyl radical attached to the nitrogen atom via a double bond. When substituted, the substituents are defined as described above for alkyl radicals.

In various embodiments of the invention, the tertiary amine bases or imine bases, respectively, are cyclic compounds containing at least two nitrogen atoms, i. at least two of R6 to R10 combine with each other to form a ring with the nitrogen atom to which they are attached, and further contain another nitrogen atom in the form of a group -NRR ', wherein the nitrogen atom is a ring atom and the group R or R 'is involved in ring formation. Particularly preferred are bases based on imidazole or imidazolidine. Thus, in various embodiments, the bases are, for example, imidazole derivatives such as, for example, 1-alkyl-imidazole or 2,4-dialkylimidazole.

In various embodiments, the at least one nonionic base is selected from the group consisting of 1-methylimidazole and 2,4-ethylmethylimidazole.

In various particularly preferred embodiments, the catalyst composition according to the invention comprises at least one compound of the formula (I) and at least one nonionic nitrogen-containing base which preferably contains a tertiary nitrogen atom and / or an imine nitrogen, both of which are each defined as described above , In such compositions, the nonionic base used in the present invention may preferably be a nonionic nitrogen-containing base capable of deprotonating the ionic compound of the formula (I) in the 2-position. That is, the base has a corresponding acid with an acid constant pKs greater than the acid constant of the H atom in position 2 of the compound of formula (I) (pKs (base)> pKs (compound of formula (I)) Acid constant is preferably at least 1. In various embodiments, the corresponding acid of the base has a pKa of 10 or greater, more preferably 12-14 or greater. "Corresponding acid" as used in this context refers to the protonated form of the base. In various embodiments, such a catalyst composition contains a 1-ethyl-3-methyl-1H-imidazolium salt, especially the thiocyanate, as a compound of formula (I) and 2,4-ethylmethylimidazole as a nonionic nitrogen-containing base.

The catalyst composition may comprise the at least one ionic compound of the formula (I) and the at least one nonionic base, for example, in a weight ratio of 10: 1 to 1:10, preferably 3: 1 to 1: 3 and more preferably 1: 1: 1 to 1: 1, 1 included.

In a preferred embodiment, based on the total amount of the epoxide (a) and the isocyanate (b), 0.01 to 10 wt.%, Preferably 0.1 to 5 wt.%, Preferably 1 wt.% Of the catalyst composition (c) used.

"Provide" as used herein refers to mixing the constituents of the reaction mixture in any order It may be advantageous, for example, first to combine two or more ingredients and optionally to mix into a heterogeneous or homogeneous mixture before adding the remaining ingredients Thus, for example, the at least one epoxy group-containing compound and the catalyst composition may first be combined and mixed and then, for example just before curing, added the at least one isocyanate group-containing compound and mixed into the other already mixed components Combination and mixing steps, it may be advantageous to cool the reaction mixture to room temperature.

In general, the individual components of the reaction mixture can be used as such or as a solution in a solvent, such as an organic solvent or a mixture of organic solvents. For this purpose, any known and suitable for the purpose of the invention solvents can be used. For example, the solvent may be a high boiling organic solvent. The solvent may be selected from the group consisting of petroleum, benzene, toluene, xylene, ethylbenzene and mixtures thereof. Since the epoxide and isocyanate compounds are preferably selected from liquid, low viscosity monomers, in various embodiments, the catalyst composition may be employed as a solution as described above.

In various embodiments, in addition to the epoxide (a), the isocyanate (b) and the catalyst composition (c), the reaction mixture comprises additional constituents known and customary in the art. For example, as further ingredients, for example, a modified resin can be used which imparts improved impact resistance and low temperature properties to the post cure compositions. Modified epoxide group-containing resins of this type are known in the art and include reaction products of epoxy resins having an epoxy functionality of greater than 1 with carboxy-functional rubbers, dimer fatty acids or so-called core / shell polymers, the Cores have a glass transition temperature of below -30 ° C. The epoxy group-containing resin in this case is preferably used in a stoichiometric excess and produces an epoxide-functional reaction product. The excess of epoxide group-containing resin may also be well above the stoichiometric excess. An epoxide functionality of greater than 1 means that the compounds contain more than 1, preferably at least 2, 1, 2-epoxide groups per molecule. There are such modified epoxy-containing resins having an epoxide equivalent weight between 150 and 4000 are advantageous. Epoxy group-containing resins may also be modified in particular with a copolymer of a 1,3-diene or an ethylenically unsaturated co-monomer and / or with core-shell-particles (CSR core-shell-rubber). These modified resins are used in addition to the epoxy resin (a) and the isocyanate (b).

Alternatively or in addition to the above, other tougheners, such as polyols, especially polyalkylene glycols, such as polypropylene glycol, or liquid rubbers may also be employed Preferably, the compositions contain a toughening agent, preferably as described above. With additional use of a toughener, the K1 c value increases significantly, and surprisingly, the Tg value does not change or only slightly.

The reaction mixture described herein may be combined with other ingredients such as the tougheners described above, in the form of an adhesive composition or an injection resin.

Such adhesive compositions can contain a variety of other components, all of which are well known to those skilled in the art, including, but not limited to, commonly used adjuvants and additives such as fillers, plasticizers, reactive and / or non-reactive diluents, flow agents , Coupling agents (eg silanes), adhesion promoters, wetting agents, adhesives, flame retardants, wetting agents, thixotropic agents and / or rheological auxiliaries (eg fumed silica), aging and / or corrosion inhibitors, stabilizers and / or dyes. Depending on the requirements of the adhesive or the injection resin and its application and in terms of production, flexibility, strength and bonding with substrates, the auxiliaries and additives are incorporated in different amounts in the composition. In various embodiments of the invention, depending on the desired use, the reaction mixture is applied to a substrate, for example when used as an adhesive, or filled into a mold, when used as a molding compound for producing plastic parts. In preferred embodiments, the process is a transfer molding (RTM) process and the reaction mixture is a reactive injection resin. "Reactive" as used in this context refers to the fact that the injection resin is chemically crosslinkable In the RTM process, the provision of the reaction mixture, ie step (1) of the described process, may include the filling, in particular injection (injection In the production of fiber-reinforced plastic parts, for which the described processes and reaction mixtures are particularly suitable, fibers or semi-finished fiber products (prefovens / preforms) can be inserted into the mold before being injected into the mold. or semi-finished fiber products, the materials known in the art for this application, in particular carbon fibers, can be used.

The invention further relates to the reaction mixtures described in connection with the methods, i. Resin compositions containing at least one epoxy group-containing resin (a), a polyisocyanate (b) and a catalyst composition (c), each as defined above.

In various embodiments, such resin compositions will be adhesive compositions or injection resins. The injection resins are preferably pumpable and particularly suitable for transfer molding (RTM process). In various embodiments, therefore, the reaction mixture has a temperature of 120 ° C, i. a typical infusion temperature, a viscosity of <100 mPas. To determine the viscosity, the resin mixture is prepared at room temperature with a suitable mixer and determined on a plate / plate rheometer in oscillation, the viscosity with increasing temperature at a heating rate of 50 K / min.

The invention therefore also relates in one embodiment to the moldings obtainable by means of the resin systems according to the invention in the RTM process. The RTM processes in which the described resin systems (polymer compositions) can be used are known as such in the prior art and can readily be adapted by the person skilled in the art such that the reaction mixture according to the invention can be used.

The opening times of the resin compositions (reaction mixture) as described herein are preferably greater than 90 seconds and more preferably in the range of 2 to 5 Minutes, especially at about 3 minutes. "Approximately" as used herein in connection with a numerical value means the numerical value ± 10%.

Depending on the nature of the epoxides and iso-isocyanates used, and depending on the catalyst composition and the use of the cured composition, the reaction mixture in step (2) of the process according to the invention can be cured at different reaction temperatures. Thus, the curing temperature between 10 ° C and 230 ° C set. In general, cure at elevated temperature, i. > 25 ° C, take place. Preferably, the resins are cured between 50 ° C and 190 ° C, and preferably between 90 ° C and 150 ° C. The duration of curing also depends on the resins to be cured and the catalyst composition and may be between 0.01 hours to 10 hours. Preferably, the cure cycle lasts a few minutes, i. especially 1 to 5 minutes. The curing can be done in one or more stages.

During curing, the epoxy group-containing resin reacts with the isocyanate in the presence of the catalyst to form at least one oxazolidinone which cross-links the resins and, among other things, confers to the cured composition its beneficial physical properties. The at least one oxazolidinone formed upon curing may contain one of 1,2-oxazolidin-3-one, 1,2-oxazolidin-4-one, 1,2-oxazolidin-5-one, 1,3-oxazolidin-2-one , 1, 3-oxazolidin-4-one, or 1, 3-oxazolidin-5-one. Thus, the cured composition may also contain a plurality of different of the aforementioned oxazolidinone isomers.

Further, in the presence of the catalyst composition described herein, the isocyanate groups react with one another to form at least one isocyanurate which crosslinks the resins together and also contributes to the advantageous properties of the cured composition.

The resins cured by the catalyst systems and methods described herein preferably have a critical stress intensity factor K1 c of> 0.5, preferably at least 0.6. The glass transition temperature of the cured resins is, in various embodiments, in the range of more than 100, in particular more than 150 ° C, typically in the range up to 200 ° C. The elastic modulus of the cured resins is preferably at least 2500, preferably at least 3000 N / mm ² , typically in the range of 2500 to 5000 N / mm ² .

Furthermore, the present invention relates to the cured composition obtainable by the method described herein. This can, depending on the process, as a molded part, in particular be present as a fiber-reinforced plastic molding. Such moldings are preferably used in the automotive industry.

Thus, the cured polymer composition are particularly suitable as a matrix resin for fiber composites. These can be used in various application methods, for example in the resin transfer molding process (RTM process) or in the infusion process.

As fiber components of fiber composites known high-strength fiber materials are suitable. These can be made of glass fibers, for example; synthetic fibers such as polyester fibers, polyethylene fibers, polypropylene fibers, polyamide fibers, polyimide fibers or aramid fibers; Carbon fibers; boron fibers; oxide or non-oxide ceramic fibers such as alumina / silica fibers, silicon carbide fibers; Metal fibers, for example of steel or aluminum; or consist of natural fibers such as flax, hemp or jute. These fibers may be incorporated in the form of mats, fabrics, knits, mats, fleeces or rovings. Two or more of these fiber materials may also be used as a mixture. Short cut fibers can be selected, but preferably synthetic long fibers are used, in particular fabrics and scrims. Such high strength fibers, scrims, fabrics and rovings are known to those skilled in the art.

In particular, the fiber composite material fibers in a volume fraction of more than 40 vol .-%, preferably more than 50 vol .-%, particularly preferably between 50 and 70 vol .-% based on the total fiber composite material to achieve particularly good mechanical properties , In the case of carbon fibers, the volume fraction is determined in accordance with the standard DIN EN 2564: 1998-08, in the case of glass fibers in accordance with the standard DIN EN ISO 1 172: 1998-12.

Such a fiber composite material is particularly suitable as an automotive component. Such fiber composites have several advantages over steel, so they are lighter, are characterized by an improved crash resistance and are also more durable.

Incidentally, it should be understood that all embodiments disclosed above in connection with the inventive methods are equally applicable to the described resin systems and cured compositions, and vice versa. Examples

DER331 (Dow Chemical, epichlorohydrin liquid epoxy resin and bisphenol A) and a catalyst composition were mixed for 30 seconds at 2000 rpm in a vacuum in the Speedmixer. After cooling this mixture to RT, methylene diphenyl diisocyanate (MDI) was added and also blended for 30 sec at 2000 rpm in a vacuum using a Speedmixer. The reaction mixture was poured into an upright mold and gelled at RT. Thereafter, the mixture was cured in two stages (1 h at 90 ° C and 1 h at 150 ° C). After cooling, the specimens required for the mechanical tests are milled from the resulting plate.

Table 1: Components of the reaction mixtures

 E: According to the invention; V: comparative experiment

 E1: catalyst = imidazolium + 2,4-EMI

 E2: catalyst = 1-methylimidazole

 E3: catalyst = 1-methylimidazole

 E4: catalyst = 1-methylimidazole

 E5: Catalyst = 2-phenyl-2-imidazoline

 E6: catalyst = N, N-dimethylbenzylamine

 E7: Catalyst = 2-ethyl-4-methylimidazole

 E8: Catalyst = 1, 8-diazabicyclo [5.4.0] undec-7-ene (DBU)

 E9: Catalyst = 1, 4-diazabicyclo [2.2.2] octane (DABCO)

V1: Catalyst = 1-methylimidazole

Table 2: Physical properties

 E1 E2 E3 E4 E5 E6 E7 E8 E9 V1

Tensile test EMod in MPa 3303 3210 3250 4140 4601 3489 4234

 Harden 1 B bone

 g still

EN-ISO 527 / 2,3 Max. Tension in 53,1 29,3 75,4 1 1, 1 29,4 38,8 19 34,5 51, 2 sticky

 MPa

Elongation at break 1, 65 0.92 2.67 0.25 0.64 0.88 0.5 0.99 1, 23 in%

 Voltage break in 53.1 29.3 74.8 1 1, 1 29.4 38.8 19 34.5 51

 MPa

3-point EMod in MPa 3745 3737 2904 3995 4323 2945 3038 2338 3850

 Bending test

 DIN EN-ISO 178 F max in MPa 1 13 143 157 150 170 21, 8 32,8 23 1 19

 % Compression 3 4.1 7.5 3.9 4.3 0.7 1 0.95 3

K1c In MPa.vm 0.67 0.58 0.92 0.61 0.52 0.55 0.57 0.65

ISO 13586

DMTA TG G "163 182 165 133 98 1 12 210 160 70 139

 180

 240

 Tg tan delta 203 213 178 215 183 188 235 207 1 17 150

 265

Claims

claims A process for producing a cured polymer composition comprising at least one oxazolidinone ring and at least one isocyanurate ring, said process comprising the steps of:  (1) providing a liquid reaction mixture comprising  (a) at least one liquid, aromatic epoxy resin;  (b) at least one liquid, aromatic polyisocyanate; and (c) a catalyst composition;  wherein the at least one epoxy resin is used in amounts relative to the at least one polyisocyanate such that the molar equivalent ratio of epoxy groups to isocyanate groups is at least 0.4, more preferably at least 0.7, more preferably at least 1, even more preferably 1; and  (2) curing the reaction mixture to obtain a cured polymer composition comprising at least one oxazolidinone ring and at least one isocyanurate ring. A method according to claim 1, characterized in that the at least one epoxy resin is a glycidyl ether, in particular an aromatic diglycidyl ether, particularly preferably a bisphenol diglycidyl ether. A method according to claim 1 or 2, characterized in that the at least one polyisocyanate is a methylene diphenyl diisocyanate (MDI). Method according to one of claims 1 to 3, characterized in that the catalyst composition contains at least one nitrogen-containing base. A method according to claim 4, characterized in that base is an ionic compound of formula (I)  Formula (I)  in which Ri and R3 are each independently selected from the group consisting of substituted or unsubstituted, linear or branched alkyl of 1 to 20 Carbon atoms, substituted or unsubstituted, linear or branched alkenyl of 3 to 20 carbon atoms and substituted or unsubstituted aryl of 5 to 20 carbon atoms;  R4 and R5 are each independently selected from the group consisting of hydrogen, substituted or unsubstituted, linear or branched alkyl of 1 to 20 carbon atoms, substituted or unsubstituted, linear or branched alkenyl of 3 to 20 carbon atoms, substituted or unsubstituted, linear or branched Alkoxy of 1 to 20 carbon atoms and substituted or unsubstituted aryl of 5 to 10 carbon atoms; or  R1 and R5 and / or R3 and R4 or R4 and R5 together with the carbon or nitrogen atoms to which they are attached, a 5-6 membered substituted or unsubstituted cycloalkyl, cycloheteroalkyl, aryl or heteroaryl ring, wherein the cycloheteroalkyl or Heteroaryl ring contains 1 to 3 heteroatoms selected from O, N and S, form;  the anion X is any anion;  "" Represents a single or double bond, in particular a double bond, and n is 1, 2 or 3. 6. The method according to claim 4 or 5, characterized in that the catalyst composition contains at least one nonionic base comprising at least one tertiary nitrogen atom and / or an imine nitrogen atom, in particular an imidazole or imidazolidine. 7. The method according to any one of claims 1 to 6, characterized in that based on the total weight of the reaction mixture 0.01 to 10 wt.%, Preferably 0.05 to 5 wt.%, Particularly preferably 0.1 to 2 wt.% the catalyst composition are used according to. 8. The method according to any one of claims 1 to 7, characterized in that  (a) the reaction mixture is free of epoxy hardeners that catalyze a polyaddition reaction;  (B) the reaction mixture at a temperature of 120 ° C has a viscosity of <100 mPas; (c) the cured polymer composition has a modulus of elasticity greater than 2500, preferably greater than 3000 N / mm ² ; and or (D) the cured polymer composition has a glass transition temperature of more than 100, in particular more than 150 ° C. 9. The method according to any one of claims 1 to 8, characterized in that (a) the reaction mixture in step (2) at a temperature between 10 ° C and 230 ° C, preferably between 50 ° C and 190 ° C and preferably between 90 ° C and 150 ° C for 0.01 hours to 10 hours, preferably for 0.1 hours to 5 hours, preferably for 1 hour; or  (B) the reaction mixture in step (2) initially at a temperature between 50 ° C and 130 ° C, preferably 70 ° C and 1 10 ° C and preferably at 90 ° C for 0, 1 hours to 3 hours, preferably for 0 , 5 hours to 2 hours, preferably for 1 hour and then at a temperature between 1 10 ° C and 190 ° C, preferably 130 ° C and 170 ° C and preferably at 150 ° C for 0.1 hours to 3 hours, preferably for 0.5 hours to 2 hours, preferably for 1 hour. 10. The method according to any one of claims 1 to 9, characterized in that the method is a transfer molding (RTM) method and the reaction mixture is a reactive injection resin. 1 1. A method according to claim 10, characterized in that step (1) comprises injecting the injection resin into a mold, in which fibers or semi-finished fiber products (Prewovens / Preform) are inserted. A cured polymer composition obtainable by a process of claims 1 to 11. A cured polymer composition according to claim 12, characterized in that the cured polymer composition is a molded part, in particular a fiber-reinforced molded part.