Epoxy resin-based fiber matrix composition containing alkyl-substituted ethyleneamines

Abstract

The present invention relates to epoxy resin fiber matrix compositions containing alkyl-substituted ethyleneamines, such as dimethyldiethylenetriamine (DMDETA, also known as dimethyl-1,4,7-triazaheptane), as curing agents. These curing agents are characterized by short cure times during relatively long processing times, and allow for the production of cured epoxy resins that exhibit low brittleness, high tensile strength, and high glass transition temperatures. As a result, the claimed fiber matrix compositions are particularly suitable for use in pultrusion and winding processes.

Description

[Technical field]

[0001] The present invention relates to an epoxy resin-based fiber-matrix composition comprising an alkyl-substituted ethyleneamine, such as dimethyldiethylenetriamine (DMDETA, also known as dimethyl-1,4,7-triazaheptane), as a curing agent. The present invention further relates to a method for producing cured composites from the fiber-matrix composition, in particular by pultrusion and filament winding processes, and to the cured composites obtained thereby. [Background technology]

[0002] Epoxy resins are commonly known and are used as materials for surface coatings, as adhesives, for molding and laminating, and for making fiber-reinforced composites because of their toughness, flexibility, adhesion, and chemical resistance.

[0003] Starting from an epoxy compound having at least two epoxy groups, it is possible to cure by polyaddition (chain extension) with, for example, an amino compound having two amino groups. The amino compound with higher reactivity is generally added shortly before the desired cure. Such systems are therefore called two-component systems (2K systems).

[0004] In principle, amine-based hardeners (amino hardeners) are classified according to their chemical structure as aliphatic, cycloaliphatic, or aromatic. Further classification is possible according to the degree of substitution of the amino group, which can be primary, secondary, or tertiary. However, for tertiary amines, a catalytic mechanism of curing of epoxy resins is assumed, whereas for secondary and primary amines, the basis for the formation of the polymer network is a stoichiometric curing reaction.

[0005] In general, aliphatic amines have been shown to exhibit the highest reactivity among primary amino curing agents in epoxy curing. Cycloaliphatic amines typically exhibit somewhat slower reactivity, while aromatic amines (amines in which the amino group is attached directly to a carbon atom of an aromatic ring) have by far the slowest reactivity.

[0006] These known differences in reactivity are exploited in the curing of epoxy resins so that processing times and curing rates can be adjusted as needed. In the production of fiber-reinforced composites (composites), it is desirable if the epoxy resin composition (matrix component) used to embed or impregnate the reinforcing fibers has a very long processing time (pot life: the time during which the composition can be processed). In the production of composites by pultrusion or by infusion or injection methods such as vacuum-assisted resin transfer molding (VARTM) or resin transfer molding (RTM), particularly in the production of large parts, a sufficiently long processing time is required for the matrix component to efficiently wet the reinforcing fibers and distribute homogeneously around them. For the same reason, a low mixing viscosity of the matrix component is also desirable. At the same time, in order to allow short production cycles and thus high productivity, the matrix component should cure within an acceptable time at high temperatures.

[0007] Cycloaliphatic amines, such as isophorone diamine (IPDA), allow relatively long processing times and, assuming appropriate formulation, simultaneously high curing rates and low mix viscosities (Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH, Weinheim, Germany, 2012, Vol. 13, Epoxy Resins, H. Pham & M. Marks, Chapter 15.1.1.2, Tab. 14 (online: 15.10.2005, DOI: 10.1002 / 14356007.a09_547.pub2)). Furthermore, epoxy resins cured with cycloaliphatic amines, such as IPDA, are generally noted for their high glass transition temperatures. Cycloaliphatic amines are therefore also used in particular for the production of composites. Aromatic amines and anhydrides, which are also used in the production of composites, have the disadvantage that long curing times and high curing temperatures are required. Furthermore, curing with anhydrides generally results in relatively brittle resins. EP2307358A states that the addition of tetramethylguanidine in epoxy resin curing with IPDA and D230 polyetheramine can simultaneously extend the pot life and increase the cure rate, but the system described therein has a relatively low glass transition temperature.

[0008] The production of composites by the pultrusion process is particularly in need of a curable composition. In the pultrusion process, a bundle of long fibers (e.g. glass, carbon or aramid fibers) is pulled in a continuous process through a device in which the fiber bundle is first impregnated with a curable composition (matrix component) and then cured at high temperature to obtain a composite part (pultruded profile). The matrix component used is generally a curable composition based on polyester resin or epoxy resin. For example, the fibers can be impregnated by pulling them through a bath containing the matrix component (bath process or "resin bath pultrusion") or by injecting the matrix component under pressure between the fibers (injection process or "resin injection pultrusion"). For curing and molding, the impregnated fiber strand is pulled through a heated zone where the matrix component cures at temperatures in the range of 100-200 ° C. For the pultrusion process, the matrix component must firstly have a sufficiently long pot life to carry out the impregnation step, but secondly also cure rapidly at high temperatures. The curing rate limits the speed at which the fiber strands can be drawn through the heating zone and thus the throughput of the process. In practice, the matrix components used are typically epoxy resin systems based on anhydrides as curing agents in combination with accelerators (e.g. imidazoles or tertiary amines) (for example, as described in technical data sheets published by Huntsman in 2012 for mixtures of Araldite® LY 1564 (mixture of bisphenol A epoxy resin and butanediol diglycidyl ether reactive diluent), Aradur® 917 (mixture of 4-methyltetrahydrophthalic anhydride and tetrahydrophthalic anhydride), and Accelerator 960-1 (2,4,6-tris(dimethylaminomethyl)phenol), or for mixtures of Araldite® LY 1556 (bisphenol A epoxy resin), Aradur® 917, and Accelerator DY 070 (1-methylimidazole)).Unfortunately, the anhydride cure of epoxy resins, in contrast to the amino cure, results in a relatively brittle product (Lee & Neville, Handbook of Epoxy Resins (1967), pp. 12-36ff.).

[0009] WO2016 / 177533 describes a pultrusion process for producing rebars with a matrix component composed of an epoxy resin and an amino hardener, such as IPDA. Thus, the use of IPDA rather than an anhydride hardener provides improved alkali stability and a higher glass transition temperature. The pot life of IPDA-based epoxy resin systems is significantly shorter than systems based on anhydride hardeners, but is still sufficient for use in pultrusion processes.

[0010] Therefore, against this background, there is a search for epoxy resin-based fiber-matrix compositions using amino hardeners, which, in particular in the pultrusion process, like the epoxy resin systems using the known cycloaliphatic amino hardener IPDA, are characterized by a relatively long pot life and low mix viscosity at room temperature (23°C), leading to cured epoxy resins with high glass transition temperatures and good mechanical properties (especially low brittleness), but at the same time allowing relatively high curing rates at moderate curing temperatures, e.g. 70-180°C, in particular 90-150°C. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] EP2307358A [Patent Document 2] WO2016 / 177533 [Non-patent literature]

[0012] [Non-Patent Document 1] Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH, Weinheim, Germany, 2012, Volume 13, Epoxy Resins, H. Pham & M. Marks, Chapter 15.1.1.2, Tab. 14 (online: 15.10.2005, DOI: 10.1002 / 14356007.a09_547.pub2) [Non-Patent Document 2] Lee & Neville, Handbook of Epoxy Resins (1967), pp. 12-36 et seq. Summary of the Invention [Problem to be solved by the invention]

[0013] It is an object of the present invention to provide such an epoxy resin based fiber-matrix composition, especially in the pultrusion process, which has a relatively long pot life and low mix viscosity at room temperature, while at the same time having an improved cure rate at moderate curing temperatures of 70-180° C., especially 90-150° C. The composition should preferably enable a high glass transition temperature and good mechanical properties (especially low brittleness) for the cured resin, similar to compositions composed of epoxy resin and cycloaliphatic amino hardener IPDA. [Means for solving the problem]

[0014] In the context of the present invention, it has been found that the use of alkyl-substituted ethyleneamines, such as dimethyldiethylenetriamine (DMDETA), despite being structurally an aliphatic amine, gives rise to cured epoxy resins having pot life and viscosity at room temperature comparable to the cycloaliphatic amino hardener IPDA, similar glass transition temperatures and similarly good mechanical properties, but at the same time curing particularly rapidly at moderate curing temperatures of 70-180° C., especially 90-150° C., and therefore particularly well suited for use in pultrusion processes. Alkyl-substituted ethyleneamines, such as DMDETA, unexpectedly combine the rapid cure characteristic of aliphatic amines with the relatively long pot life and relatively high glass transition temperatures characteristic of cycloaliphatic amines.

[0015] The present invention therefore provides a fiber-matrix composition having a fiber component consisting of reinforcing fibers and a matrix component comprising an epoxy resin and a curing agent, the curing agent being represented by the formula I H 2 NA-(NH-A-) n NH 2 (I) [In the formula, A independently represents a group of the formula -CHR-CH 2 -or-CH 2 and wherein R=H, ethyl, or methyl, but at least one A in the alkyl-substituted ethyleneamine of formula I is an ethylene group of formula -CHR-CH 2 -or-CH 2 an alkylethylene group of the formula -CHR-, where R=ethyl or methyl; n=1 to 4, preferably n=1 or 2, particularly preferably n=1. The present invention relates to a fiber-matrix composition characterized in that it contains at least one alkyl-substituted ethyleneamine, such as dimethyldiethylenetriamine (DMDETA). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] In a preferred embodiment, the alkyl-substituted ethyleneamine of the present invention is represented by formula I [In the formula, A is independently a group of the formula -CH(CH 3 )-CH 2 -or-CH 2 -CH(CH 3 )-methylethylene group, n = 1 to 4, preferably n = 1 or 2. It is a compound of the formula:

[0017] In a particularly preferred embodiment, the alkyl-substituted ethyleneamine of the present invention is dimethyldiethylenetriamine (DMDETA), formula II H 2 NA-NH-A-NH 2 (II) [wherein A independently represents a group of the formula -CH(CH 3 )-CH 2 -or-CH 2 -CH(CH 3 )-methylethylene group] or an isomeric mixture of compounds of formula II. Preferably, the DMDETA of the present invention is an isomer of formula IIa, IIb, or IIc, or a mixture of isomers of formula IIa, IIb, and IIc (or a mixture of two of these three isomers).

[0018] [ka]

[0019] In the use according to the invention of DMDETA isomer mixtures, in particular mixtures essentially consisting of compounds of the formulae IIa and IIb are used, for example to the extent of at least 60% by weight, in particular to the extent of at least 80% by weight, of compounds of the formulae IIa and IIb.

[0020] The empirical amine hardener equivalent weight (AHEW) of the DMDETA of the present invention emp ) is preferably in the range of 25 to 30 g / eq.

[0021] The fundamental usefulness of DMDETA as a hardener for epoxy resins has been mentioned, though not in detail, by Akhmadeyeva and Zagidullin (Mukmeneva, ed., Materialy Yubileinoi Nauchno-Metodicheskoi Konferentsii "III Kirpichnikovskie Chteniya", Kazan, Russian Federation, March 25-28, 2003, pp. 473-475).

[0022] The epoxy resin according to the invention typically has 2 to 10, preferably 2 to 6, even more preferably 2 to 4, in particular 2 epoxy groups. The epoxy groups are in particular glycidyl ether groups, such as those formed in the reaction of alcohol groups with epichlorohydrin. The epoxy resins generally have an average molecular weight (M n) or higher molecular weight compounds (polymers). Such polymeric epoxy resins preferably have a degree of oligomerization of 2 to 25 units, more preferably 2 to 10 units. The resins may be aliphatic or cycloaliphatic compounds or compounds with aromatic groups. In particular, epoxy resins are compounds with two aromatic or aliphatic six-membered rings or their oligomers. Industrially important epoxy resins are those obtained by reaction of epichlorohydrin with compounds having at least two reactive hydrogen atoms, in particular with polyols. Of particular importance are epoxy resins obtained by reaction of epichlorohydrin with compounds containing at least two, preferably two hydroxy groups and two aromatic or aliphatic six-membered rings. Such compounds include in particular bisphenol A and bisphenol F, and also hydrogenated bisphenol A and hydrogenated bisphenol F, the corresponding epoxy resins being diglycidyl ethers of bisphenol A or bisphenol F or of hydrogenated bisphenol A or hydrogenated bisphenol F. The epoxy resin used according to the invention is typically bisphenol A diglycidyl ether (DGEBA). Suitable epoxy resins according to the invention also include tetraglycidyl methylene dianiline (TGMDA) and triglycidyl aminophenol, or mixtures thereof. Reaction products of epichlorohydrin with other phenols, such as cresol or phenol-aldehyde adducts, such as phenol-formaldehyde resins, especially novolaks, are also suitable. Epoxy resins not derived from epichlorohydrin are also suitable. Examples of useful resins include epoxy resins that contain epoxy groups by reaction with glycidyl (meth)acrylate. The use of epoxy resins or mixtures thereof that are liquid at room temperature (23° C.) is preferred according to the invention. The epoxy equivalent weight (EEW) indicates the average mass (g) of epoxy resin per mole of epoxy group.

[0023] The matrix component of the fiber-matrix composition of the present invention preferably consists of epoxy resin to the extent of at least 50% by weight.

[0024] In certain embodiments, the fiber-matrix composition of the present invention may further comprise a reactive diluent. A reactive diluent in the context of the present invention is a compound that reduces the mixing viscosity (also called initial viscosity) of the curable composition and forms chemical bonds during the curing process of the curable composition while developing a network structure of the epoxy resin and the curing agent. A preferred reactive diluent in the context of the present invention is a low molecular weight organic compound, preferably an aliphatic compound, containing one or more epoxy groups.

[0025] The reactive diluent of the present invention is preferably selected from the group consisting of butane-1,4-diol bisglycidyl ether, hexane-1,6-diol bisglycidyl ether (HDDE), glycidyl neodecanoate, glycidyl versatate, 2-ethylhexyl glycidyl ether, neopentyl glycol diglycidyl ether, p-tert-butyl glycidyl ether, butyl glycidyl ether, C8-C10-alkyl glycidyl ether, C12-C14-alkyl glycidyl ether, nonylphenyl glycidyl ether, p-tert-butylphenyl glycidyl ether, phenyl glycidyl ether, o-cresyl glycidyl ether, polyoxypropylene glycol diglycidyl ether, trimethylolpropane triglycidyl ether (TMP), glycerol triglycidyl ether, triglycidyl paraaminophenol (TGPAP), divinylbenzyl dioxide, and dicyclopentadiene diepoxide. They are more preferably selected from the group consisting of butane-1,4-diol bisglycidyl ether, hexane-1,6-diol bisglycidyl ether (HDDE), 2-ethylhexyl glycidyl ether, C8-C10-alkyl glycidyl ether, C12-C14-alkyl glycidyl ether, neopentyl glycol diglycidyl ether, p-tert-butyl glycidyl ether, butyl glycidyl ether, nonylphenyl glycidyl ether, p-tert-butylphenyl glycidyl ether, phenyl glycidyl ether, o-cresyl glycidyl ether, trimethylolpropane triglycidyl ether (TMP), glycerol triglycidyl ether, divinylbenzyl dioxide, and dicyclopentadiene diepoxide. They are in particular selected from the group consisting of butane-1,4-diol bisglycidyl ether, C8-C10-alkyl monoglycidyl ethers, C12-C14-alkyl monoglycidyl ethers, hexane-1,6-diol bisglycidyl ether (HDDE), neopentyl glycol diglycidyl ether, trimethylolpropane triglycidyl ether (TMP), glycerol triglycidyl ether and dicyclopentadiene diepoxide.

[0026] The reactive diluent according to the invention preferably accounts for a maximum of 30% by weight, more preferably a maximum of 25% by weight, in particular from 1% to 20% by weight, based on the amount of epoxy resin.

[0027] The curing agent of the matrix component of the present invention may contain not only the alkyl-substituted ethyleneamines of the present invention, but also further aliphatic, cycloaliphatic, and aromatic polyamines, or further primary monoamines. Examples of suitable further aliphatic, cycloaliphatic, or aromatic polyamines include diphenylamine, dimethyldiphenylamine (DMDC), isophoronediamine (IPDA), diethylenetriamine (DETA), triethylenetetramine (TETA), tetraethylenepentamine (TEPA), 1,3-bis(aminomethyl)cyclohexane (1,3-BAC), bis(p-aminocyclohexyl)methane (PACM), methylenedianiline (e.g., 4,4'-methylenedianiline), ... polyetheramines such as D230 polyetheramine, D400 polyetheramine, D2000 polyetheramine, or T403 polyetheramine; 4,9-dioxadodecane-1,12-diamine (DODA); 4,7,10-trioxatridecane-1,13-diamine (TTD); polyaminoamides such as Versamid 140; diaminodiphenylmethane (DDM); diaminodiphenylsulfone (DDS); toluene -2,4-diamine, toluene-2,6-diamine, 4-methylcyclohexane-1,3-diamine, 2-methylcyclohexane-1,3-diamine, mixture of 4-methylcyclohexane-1,3-diamine and 2-methylcyclohexane-1,3-diamine (MCDA), 1,2-diaminocyclohexane (DACH), 2,4-diamino-3,5-diethyltoluene, 2,6-diamino-3,5-diethyltoluene (DETDA), 1,2-diaminobenzene Zene, 1,3-diaminobenzene, 1,4-diaminobenzene, diaminodiphenyl oxide, 3,3',5,5'-tetramethyl-4,4'-diaminodiphenyl, 3,3'-dimethyl-4,4'-diaminodiphenyl, 1,12-diaminododecane, 1,10-diaminodecane, 1,5-diaminopentane (cadaverine), propane-1,2-diamine, propane-1,3-diamine, 2,2'-oxybis(ethylamine), 3,3'-dimethyl-4,These include 4'-diaminodicyclohexylmethane, 4-ethyl-4-methylamino-1-octylamine, ethylenediamine, hexamethylenediamine, menthenediamine, meta-xylylenediamine (MXDA), reaction products of benzene-1,3-dimethanamine with styrene (Gaskamine® 240), N-(2-aminoethyl)piperazine (AEPIP), neopentanediamine, norbornanediamine, dimethylaminopropylaminopropylamine (DMAPAPA), octamethylenediamine, 4,8-diaminotricyclo[5.2.1.0]decane, trimethylhexamethylenediamine, and piperazine. Preferentially suitable further aliphatic, cycloaliphatic or aromatic polyamines are disicane, dimethyl disicane (DMDC), isophorone diamine (IPDA), diethylenetriamine (DETA), triethylenetetramine (TETA), tetraethylenepentamine (TEPA), 1,3-bis(aminomethyl)cyclohexane (1,3-BAC), bis(p-aminocyclohexyl)methane (PACM), polyetheramines such as, for example, D230 polyetheramine, D400 polyetheramine, D2000 polyetheramine or T403 polyetheramine, 4,9-dioxadodecane-1,12-diamine (D ODA), 4,7,10-trioxatridecane-1,13-diamine (TTD), polyaminoamides such as Versamid 140, 4-methylcyclohexane-1,3-diamine, 2-methylcyclohexane-1,3-diamine, mixtures of 4-methylcyclohexane-1,3-diamine and 2-methylcyclohexane-1,3-diamine (MCDA), 1,2-diaminocyclohexane (DACH), 2,4-diamino-3,5-diethyltoluene, 2,6-diamino-3,5-diethyltoluene (DETDA), 1,5-diaminopentane (cadaverine), meta-xylylenediamine (MXDA), benzene-1,The reaction product of 3-dimethanamine with styrene (Gaskamine® 240), N-(2-aminoethyl)piperazine (AEPIP), and dimethylaminopropylaminopropylamine (DMAPAPA). Examples of suitable further primary monoamines include dimethylaminopropylamine (DMAPA) and diethylaminopropylamine (DEAPA).

[0028] In certain embodiments, the alkyl-substituted ethyleneamine of the present invention comprises at least 50% by weight, more preferably at least 80% by weight, and most preferably at least 90% by weight, based on the total amount of curatives in the fiber-matrix composition. In a preferred embodiment, the fiber-matrix composition does not include any anhydride curatives. In certain embodiments, the fiber-matrix composition does not include any additional curatives apart from the alkyl-substituted ethyleneamine of the present invention.

[0029] Curing agents in the context of the present invention are understood to mean amino or anhydride curing agents. Amino curing agents in the context of the present invention are understood to mean amines with an NH functionality of 2 or more (thus, for example, primary monoamines have an NH functionality of 2, primary diamines have an NH functionality of 4, and amines with three secondary amino groups have an NH functionality of 3). Anhydride curing agents in the context of the present invention are understood to mean intramolecular carboxylic acid anhydrides, for example 4-methyltetrahydrophthalic anhydride.

[0030] In the matrix component of the fiber-matrix composition of the present invention, it is preferred to use the epoxy compound (epoxy resin, including any reactive diluent with epoxy groups) and the amino hardener in an approximately stoichiometric ratio based on the epoxy resin and the NH functionality. A particularly suitable ratio of epoxy groups to NH functionality is, for example, 1:0.8 to 1:1.2. Alternatively, in a particular embodiment of the present invention, the epoxy compound (epoxy resin, including any reactive diluent with epoxy groups) and the amino hardener are used in the matrix component of the fiber-matrix composition of the present invention in an approximate stoichiometric ratio based on the epoxy resin and the NH functionality. emp Based on the above, the amount is approximately equivalent, preferably in a ratio ranging from 1:0.8 to 1:1.2.

[0031] The reinforcing fibers of the invention are preferably glass, carbon, aramid or basalt fibers or mixtures thereof. Particular preference is given to glass and carbon fibers, in particular glass fibers. The glass fibers used are typically E-glass fibers, but also R-, S- and T-glass fibers. The choice of glass type may affect the mechanical properties of the composite material. According to the invention, the reinforcing fibers are used in the form of monofilaments, but preferably in the form of fiber filaments, fiber rovings, fiber mats or combinations thereof. Particular preference is given to using the reinforcing fibers in the form of fiber rovings. The reinforcing fibers may take the form of short fiber pieces, for example having a length of a few mm to cm, or medium fiber pieces, having a length of a few cm to a few meters, or long fiber pieces, having a length in the range of several meters or more. According to the invention, in particular in pultrusion or filament winding processes, the reinforcing fibers are preferably used in the form of continuous fiber filaments, continuous fiber rovings or continuous fiber mats. A continuous fibre filament, continuous fibre roving or continuous fibre mat in the context of the present invention has a length of at least 10 m, preferably at least 100 m, in particular at least 200 m.

[0032] The fiber-matrix composition of the invention may also contain further additives, such as inert diluents, curing accelerators, pigments, colorants, fillers, release agents, toughening agents, flow agents, defoamers, flame retardants, or thickeners. Such additives are typically added in functional amounts, i.e., for example, pigments are typically added in an amount that imparts the desired color to the composition. The composition of the invention typically contains all additives in total in an amount of 0% to 50% by weight, preferably 0% to 20% by weight, for example 2% to 20% by weight, based on the entire fiber-matrix composition. In the context of the present invention, additives are understood to mean any additive to the fiber-matrix composition that is neither an epoxy compound nor a curing agent (amino curing agent and / or anhydride curing agent) nor a reinforcing fiber.

[0033] The fiber-matrix compositions of the present invention preferably comprise reinforcing fibers impregnated with a matrix component.

[0034] The present invention also relates to the use of the alkyl-substituted ethyleneamines of the present invention as curing agents in the preparation of epoxy resin-based composites.

[0035] DMDETA may be produced, for example, as a by-product in the preparation of propane-1,2-diamine (PDA) by amination of monoisopropanolamine (MIPOA) with ammonia. Alternatively, it may be selectively prepared by catalytic alcohol amination of MIPOA with PDA in the presence of hydrogen and optionally further ammonia. Furthermore, DMDETA may be prepared from 1,2-dichloropropane according to Akhmadeyeva and Zagidullin (Mukmeneva, ed., Materialy Yubileinoi Nauchno-Metodicheskoi Konferentsii "III Kirpichnikovskie Chteniya", Kazan, Russian Federation, March 25-28, 2003, pp. 473-475). Other alkyl-substituted ethyleneamines of the present invention may be prepared by corresponding methods.

[0036] The invention further provides a method for producing a cured composite material from the fiber-matrix composition of the invention. In the method of the invention for producing such a cured composite material, the fiber-matrix composition of the invention is provided and then cured. For this purpose, the constituents of the matrix component are contacted and mixed with each other, contacted with the reinforcing fibers (impregnation of the reinforcing fibers with the matrix component or mixing (embedding) the reinforcing fibers in the matrix component) and then cured at a practical temperature. The fiber-matrix composition is preferably provided by impregnating the reinforcing fibers with the matrix component. The curing is preferably carried out at a temperature of at least 70°C, more preferably at least 90°C. The curing can be carried out at a temperature below 180°C, in particular below 150°C, in particular within the temperature range of 70 to 180°C, most preferably within the temperature range of 90 to 150°C. The curing is preferably carried out under standard pressure.

[0037] The present invention further provides a cured composite material composed of the fiber-matrix composition of the present invention, in particular composed of reinforcing fibers impregnated with a matrix component. More particularly, the present invention provides a cured composite material obtainable or obtained by curing the fiber-matrix composition of the present invention, in particular the reinforcing fibers impregnated with a matrix component. More particularly, the present invention provides a cured composite material obtainable or obtained by the inventive method for producing a cured composite material. Composite materials cured according to the present invention, or their matrix component, have a relatively high glass transition temperature Tg.

[0038] The present invention relates to a particularly preferred method for producing a hardened composite material, such as a rebar, comprising the steps of: a. A process of arranging a large number of reinforcing fibers to obtain a bundle; b. drawing the bundle through an impregnation device to impregnate the reinforcing fibers in the bundle with the curable composition; c. drawing the impregnated reinforcing fiber bundle through a heating device that cures the bundle at a temperature in the range of 70-180°C to obtain a cured composite material; A pultrusion process comprising: Also provided is a pultrusion process in which the curable composition is the matrix component of the invention. The reinforcing fibers are preferably glass or carbon fibers, in particular glass fibers, preferably having a length of at least 1 m, in particular at least 10 m. The reinforcing fibers are preferably in the form of continuous fiber filaments, continuous fiber rovings or continuous fiber mats, or a combination thereof. To avoid direct appearance of the fibers on the surface of the bundle, a surface veil rich in matrix components may be added to the bundle. The impregnation device of step b is preferably a bath containing the curable composition in which the bundle of reinforcing fibers is immersed, or an injection device with a curable composition, in which the curable composition is injected under pressure into the bundle on the surface of the reinforcing fibers. In particular, the impregnation device of step b is an injection device with a curable composition, in which the curable composition is injected under pressure into the bundle on the surface of the reinforcing fibers. Preference is given to curing the impregnated bundle of reinforcing fibers in the heating device of step c at a temperature in the range of 90 to 150 ° C. In a particular embodiment of this process, the bundle of reinforcing fibers may be spread out for better impregnation in the impregnation device. In a particular embodiment, the impregnated bundle of reinforcing fibers may be shaped to a particular cross section during curing in the heating device, so that the cured composite material takes the form of a profile with a particular cross section, for example a rectangular or circular cross section. It is preferred to carry out the pultrusion process as a continuous process. The impregnation and heating devices in the continuous process are designed in such a way that a constant speed at which the bundle of reinforcing fibers is drawn through the device ensures a sufficient impregnation and a sufficient curing of the reinforcing fibers. A uniform and practical impregnation requires a sufficiently long pot life of the matrix components. At the same time, in order to realize a relatively short heating zone of the heating device or a relatively fast pultrusion speed, it is important to rapidly cure the matrix components at the curing temperature of the heating device. A fast pultrusion speed is crucial for the productivity of the process. The profiles produced by the pultrusion process can be used, for example, as reinforcing bars in the construction of concrete structures.

[0039] The present invention also relates to a particularly preferred method for producing a hardened composite material, such as a reinforcing bar, comprising the steps of: a. impregnating one or more reinforcing fibers with a curable composition and then winding the one or more impregnated reinforcing fibers thus obtained onto a winding core to obtain an uncured composite material; b. curing the uncured composite material at a temperature in the range of 70 to 180°C to obtain a cured composite material; A filament winding method comprising: Also provided is a filament winding process, in which the curable composition is the matrix component of the invention. The reinforcing fibers are preferably glass or carbon fibers, in particular glass fibers, preferably having a length of at least 1 m, in particular at least 10 m. The reinforcing fibers are preferably in the form of continuous fiber filaments, continuous fiber rovings or continuous fiber mats, or combinations thereof. The impregnation device of step a is preferably a bath containing the curable composition in which one or more reinforcing fibers are immersed. The uncured composite material is preferably cured in step b at a temperature in the range of 90 to 150 ° C. The winding core may be, for example, conical and may be removed from the cured composite material after curing, or may consist of a material that can be dissolved, for example, after curing the composite material, or may remain in the cured composite material. The filament winding process is preferably used to manufacture rotationally symmetrical components, but it is also possible to wrap cores having more complex shapes and to manufacture components of corresponding complex shapes. In a particular embodiment, the filament winding process is carried out as a continuous process. A uniform and practical impregnation requires a sufficiently long pot life of the matrix component. At the same time, in order to realize the relatively short curing times or relatively high productivity of this method, it is important that the matrix components are rapidly cured at the curing temperature of the heating device. Components produced by the filament winding method can be used, for example, as reinforcing bars in the construction of concrete structures.

[0040] It is possible to manufacture reinforcing bars by the methods of the invention, in particular by the pultrusion method of the invention, and by the filament winding method of the invention. Such reinforcing bars made of the composite material of the invention are particularly resistant to weathering, whereas conventional reinforcing bars made of steel are subject to corrosion. The use of such reinforcing bars in concrete structures therefore allows the construction of particularly long-lived structures.

[0041] The invention therefore also provides a reinforcing bar composed of the hardened composite material of the invention. More particularly, the invention provides a reinforcing bar obtainable or obtained by hardening a matrix component impregnated reinforcing fiber. The invention in particular provides a reinforcing bar obtainable or obtained by the method of the invention for producing a hardened composite material, preferably by the pultrusion method of the invention or by the filament winding method of the invention. Such reinforcing bars can be produced in any length and thickness, the reinforcing bars preferably having a length in the range of 0.5-50 m, in particular 1-20 m, and a thickness of 0.5-5 cm, in particular 1-3 cm. The cross section of such reinforcing bars may have any shape, preferably essentially rectangular or circular. To improve the anchoring in the concrete, such reinforcing bars preferably have a surface profile, for example one or more grooves or ridges forming a spiral around the reinforcing bar. Such a surface profile may for example be machined later into the already hardened reinforcing bar or may be applied by wrapping before hardening with a corresponding impregnated reinforcing fiber material. Such rebars may also have an additional surface coating, for example of a pure epoxy resin material, to further protect the reinforcing fibers from weathering and from chemical and thermal influences or to improve interaction with the concrete.

[0042] Further methods for producing cured composites for which the matrix components of the present invention are suitable include pultrusion and filament winding processes, as well as the curing of pre-impregnated fibers or fiber fabrics (e.g. prepregs) after storage and the production of composite moldings by infusion or injection processes, such as vacuum assisted resin transfer molding (VARTM), resin transfer molding (RTM), and also wet compression processes, such as BMC (bulk mould compression) and SMC (sheet mould compression).

[0043] The present invention further relates to a cured composite material obtainable or obtained by curing the fiber-matrix composition of the present invention or obtainable or obtained by the process of the present invention for producing a cured composite material. The present invention also relates to a molding (composite molding) consisting of the cured composite material of the present invention.

[0044] The pot life can be determined according to the standard DIN 16 945 (1989) ("Isothermal Viscosity Profile"). This gives an indication of the time from mixing of the components during which the reactive resin composition can be handled. For this purpose, at a constant temperature (e.g. room temperature (23°C)), the progress of the viscosity is measured over time with a rheometer (e.g. a shear stress controlled plate-plate rheometer (e.g. MCR301, Anton Paar)) with a plate diameter of e.g. 15 mm and a gap of e.g. 0.25 mm, until a certain viscosity limit (e.g. 6000 mPa*s) is reached. The pot life is thus the time until this viscosity limit is reached.

[0045] The gel time according to standard DIN 16 945 (1989) gives an indication regarding the time between the addition of the hardener to the reaction mixture and the transition of the reactive resin composition from the liquid state to a gel-like body. The temperature plays an important role, therefore the gel time is determined for a predefined temperature in each case. Dynamic mechanical methods, in particular rotational viscometry, make it possible to analyze even small samples in a quasi-isothermal manner and to capture their entire viscosity / stiffness profile. According to standard ASTM D 4473-08 (2016), the intersection of the storage modulus G' and the loss modulus G'' with a value of damping tan δ of 1 is the gel point, and the time between the addition of the hardener to the reaction mixture and the reaching of the gel point is the gel time. The gel time determined in this way can be considered as a measure of the curing rate.

[0046] In the determination of the B time, which also serves as a measure of the curing speed, according to standard DIN EN ISO 8987 (2005), a sample (e.g. 0.5 g) of the freshly produced reactive resin composition is applied to a hot plate (e.g. a non-embedded plate, e.g. 145° C.) and the time to the formation of threads (gel point) or to the time to sudden hardening (curing) is determined.

[0047] The glass transition temperature (Tg) can be determined using a differential scanning calorimeter (DSC), for example according to standard ASTM D 3418-15 (2015). This involves heating a very small amount of sample (for example about 10 mg) in an aluminum crucible (for example at 20° C. / min) and measuring the heat flow to a reference crucible. This cycle is repeated three times. The glass transition is determined from the second measurement or as the average of the second and third measurements. The evaluation of the Tg step of the heat flow curve can be determined by the inflection point, according to the half-width or according to the midpoint temperature method.

[0048] Amine hydrogen equivalent weight (AHEW) can be determined theoretically or empirically as described by B. Burton et al. (Huntsman, "Epoxy Formulations using Jeffamine Polyetheramines", April 27, 2005, pp. 8-11). The theoretically calculated AHEW is defined as the molecular weight of the amine divided by the number of available amine hydrogens (e.g., two for each primary amino group plus one for each secondary amino group). For example, for IPDA with a molecular weight of 170.3 g / mol and two primary amino groups, i.e., four available amine hydrogens, the theoretically calculated AHEW is 170.3 / 4 g / eq = 42.6 g / eq. Empirical AHEW determination is based on the assumption that equal amounts of epoxy resin and amino hardener will result in a cured epoxy resin characterized by maximum heat distortion resistance (heat distortion temperature (HDT)) or maximum gas transition temperature (Tg). Therefore, to ascertain the empirical AHEW, mixtures of fixed amounts of epoxy resin and varying amounts of amino hardener are cured as completely as possible, their respective HDTs or Tg's are determined, and the characteristics thus ascertained are plotted against the ratio of the starting materials. emp ) is expressed by the following formula: AHEW emp =(AH max ×EEW epox ) / ER [In the formula, AH max = amount of amino hardener at maximum HDT or Tg (grams) E.E.W. epox = EEW value of the epoxy resin used in the test ER = amount of epoxy resin used in the test (grams)] is defined as:

[0049] In the context of the present invention, AHEW emp means the empirical amine hydrogen equivalent weight based on the determination of the maximum Tg (measured by DSC according to standard ASTM D 3418-15 (2015)). Empirical AHEW empis particularly important when the theoretically calculated AHEW cannot be obtained, such as in the case of mixtures of polymeric amines.

[0050] The initial viscosity ("mixed viscosity") of the curable composition, for example the matrix component of the fiber-matrix composition of the invention, can be determined immediately after mixing of the components according to standard DIN ISO 3219 (1993). The mixed viscosity is determined using a shear stress controlled rheometer (for example MCR 301 from Anton Paar) with a cone-plate configuration (for example cone and plate diameter: 50 mm; cone angle: 1°; gap width: 0.1 mm). The measurement temperature has a large effect on the viscosity and the curing speed of the curable composition and is therefore a crucial factor in these measurements. Therefore, to be comparable, the mixed viscosity must be determined at a specific temperature, for example room temperature (23°C).

[0051] The impact resistance of test specimens made of cured epoxy resins can be determined by Charpy notched bar impact tests at room temperature according to standard DIN EN ISO 179-1 (2010). High impact resistance corresponds to low brittleness. EXAMPLES

[0052] [Example 1a] Preparation of DMDETA from aminopropanol (MIPOA) and propanediamine (PDA) A tubular reactor was charged with 600 ml of Cu catalyst. The catalyst was activated by heating it to a temperature in the range of 180-200 °C at standard pressure under a nitrogen flow. Hydrogen was metered into the nitrogen flow while carefully controlling the exotherm of activation. Finally, pure hydrogen was passed over the catalyst for 6 hours at standard pressure and a temperature of 200 °C. After the catalyst was activated, the reactor was placed under 200 bar hydrogen pressure and 100 g / h 1-aminopropan-2-ol (mixed with about 10% 2-aminopropan-2-ol), 200 g / h propane-1,2-diamine, 80 g / h NH were added at a temperature in the range of 180-200 °C. 3 , and 100 L(STP) / hour H2 The stream was passed through the reactor. The product stream was expanded to standard pressure and collected. The crude product thus obtained, containing about 20% to 30% by weight of DMDETA, was purified by vacuum distillation to obtain a DMDETA fraction. This DMDETA fraction had a purity of more than 99% (with respect to the sum of all DMDETA isomers) and an isomer ratio (GC area %) of about 6:87:6 for isomers of formula IIa:IIb:IIc.

[0053] [Example 1b] Preparation of DMDETA from aminopropanol (MIPOA) A tubular reactor was charged with 800 ml of Co / Ni / Cu catalyst. The catalyst was activated by heating it to a temperature of 280 °C under hydrogen flow at standard pressure. After the catalyst was activated, the reactor was placed under 200 bar hydrogen pressure and heated with 320 g / h 1-aminopropan-2-ol (mixed with about 10% 2-aminopropan-2-ol), 200-730 g / h NH at temperatures ranging from 170 to 190 °C. 3 , and 100 L(STP) / hour H 2 The stream was passed through the reactor. The product stream was expanded to standard pressure and collected. The crude product thus obtained, containing about 5 wt. % DMDETA as well as the main product propanediamine (PDA), was purified by vacuum distillation to obtain a DMDETA fraction. This DMDETA fraction had a purity of more than 99% (with respect to the sum of all DMDETA isomers) and an isomer ratio (GC area %) of about 42:53:4 for the isomers of formula IIa:IIb:IIc.

[0054] [Example 2] Curing of epoxy resins with DMDETA The DMDETA mixture according to Example 1a or Example 1b and epoxy resin (bisphenol A diglycidyl ether, Epilox A19-03, Leuna, EEW: 185 g / mol) were mixed in a stirrer system (1 min at 2000 rpm) according to the amounts listed in Table 1. DSC measurements (differential scanning calorimetry) and rheological analysis were carried out immediately after mixing. As a comparison, the corresponding compositions containing IPDA (Baxxodur® EC 201, BASF), diethylenetriamine (DETA, BASF), 4-methyltetrahydrophthalic anhydride (MTHPA, Sigma-Aldrich) in combination with the accelerator 2,4,6-tris(dimethylaminomethyl)phenol (K54, Sigma-Aldrich) or MTHPA in combination with the accelerator 1-methylimidazole (1-MI, BASF) were also investigated.

[0055] DSC analysis of the curing reaction of DMDETA or IPDA, DETA, MTHPA / K54 or MTHPA / 1-MI to determine the onset temperature (To), exotherm enthalpy (ΔH) and glass transition temperature (Tg) was carried out according to ASTM D 3418-15(2015) using the following temperature profile: 0°C → 20K / min 200°C → 10min 200°C. Tg was determined in the second run. The results are summarized in Table 1.

[0056] Rheological measurements to investigate the reactivity profile (pot life and gel time) of epoxy resins with different amino hardeners (IPDA, DETA, and DMDETA) and different anhydride hardener systems (MTHPA / K54 and MTHPA / 1-MI) were carried out at different temperatures in a shear stress controlled plate-plate rheometer (MCR 301, Anton Paar) with a plate diameter of 15 mm and a gap of 0.25 mm. For the pot life as a measure of the time that the reactive resin composition can be handled, the time it takes for a freshly prepared reactive resin composition to reach a viscosity of 6000 mPa*s was measured by rotation of the rheometer at room temperature (23°C). The gel time was determined by oscillation of the rheometer at 90°C or 110°C, and the intersection of the loss modulus (G'') and the storage modulus (G') gave the gel time according to standard ASTM D 4473-08 (2016). Using a shear stress controlled rheometer (e.g. MCR 301 from Anton Paar) with a cone-plate configuration (e.g. diameter of cone and plate: 50 mm; cone angle: 1°; gap width: 0.1 mm), the mixing viscosity (η) was measured according to standard DIN ISO 3219 (1993) immediately after the components were mixed. o ) was measured at room temperature (23° C.). In the determination of the B time, which also serves as a measure of the curing speed, samples (0.5 g) of the freshly produced reactive resin composition were applied to a non-embedded plate at 145° C. in accordance with standard DIN EN ISO 8987 (2005) and the time it took for fibers to form (gel point) and the time to sudden hardening (curing) were measured. The results of the rheological measurements are summarized in Table 1.

[0057] Immediately after the epoxy resin and the amino or anhydride hardener system were mixed, the mixture was degassed at 1 mbar and then cured (8 h at 60° C., then 4 h at 100° C., then 2 h at 160° C.). After curing, the mechanical properties of the cured resins (tensile modulus (Et), tensile strength (σ-M), tensile elongation (ε-M), flexural modulus (Ef), flexural strength (σ-fM) and flexural elongation (ε-fM)) were determined at room temperature according to ISO 527-2:1993 and ISO 178:2006. The results are likewise summarized in Table 1. The impact resistance was determined by Charpy notched bar impact testing at room temperature according to standard DIN EN ISO 179-1 (2010). High impact resistance corresponds to low brittleness.

[0058] [Table 1]

[0059] [Example 3] Pultrusion molding using a matrix consisting of epoxy resin and DMDETA Pultruded profiles were produced by the pultrusion process. For this purpose, continuous glass fibers (E-CR glass; PulStrand® 4100 Type 30; from Owens Corning) were impregnated with a matrix mixture consisting of 100 parts of epoxy resin (ER5700, from Leuna Harze, EEW: 180.5), 15 parts of DMDETA (Example 1a) and 3 parts of a release agent (PAT C656 / 3-7, from Wurtz) in a pultrusion machine (Px 750-08T; from Pultrex), bundled and cured at a pultrusion speed of 1.1 m / min and a temperature of 160° C. (length of heating zone: 1 m). In addition to these glass fiber-based pultrusion profiles (GF pultrusions), carbon fiber-based pultrusion profiles (CF pultrusions) were produced using continuous carbon fiber (Sigrafil C T50-4.0 / 240-E100, SGL) in a corresponding manner, except that 5 parts of separation agent were used and the pultrusion speed was set at 0.4 m / min.

[0060] The glass transition temperature (Tg) was measured as described for Example 2 according to ASTM D 3418-15 (2015). For this purpose, a portion of the material was removed from the pultrusion and ground to a powder, its fiber content was removed by density gradient, and the Tg determination was carried out on the remaining powdered resin material. The GF pultrusion achieved a glass transition temperature of 88.7°C and a glass transition temperature of 92.1°C after further curing (110°C for 6 hours). The CF pultrusion achieved a glass transition temperature of 89.1°C.

[0061] The pultrusion had a fiber volume content of about 60%.

[0062] In a three-point bending test according to standard DIN EN ISO 14125 (2011) (apparatus: Z050 Allround (fin: r = 5 mm, support: r = 5 mm), manufactured by Zwick / Roell), the flexural modulus (Ef), flexural strength (σ-fM) and flexural elongation (ε-fM) were determined in the longitudinal direction (0°) and transverse direction (90°) respectively to the alignment of the fibres. In each case 6 specimens with dimensions 3 mm x 15 mm x 200 mm (longitudinal measurements) or 5 specimens with dimensions 3 mm x 15 mm x 150 mm (transverse measurements) were analysed at a temperature of 23 °C, a relative humidity of 50%, a force sensor of 50 kN, a speed of 1% / min and a support width of 120 mm (longitudinal measurements) or 60 mm (transverse measurements). The measurements were corrected if necessary in accordance with the standard for large deflections. The results are summarised in Table 2.

[0063] [Table 2]

[0064] The interlaminar shear strength (ILSS) of the GF and CF pultrusions was determined in each case longitudinally (0°) to the fiber orientation by the three-point method according to standard DIN EN ISO 14130 (1998) (apparatus: Z050 Allround; from Zwick / Roell; with a support radius of 3 mm). In each case, six specimens with a thickness of 3 mm were analyzed at a temperature of 23° C., a relative humidity of 50% and a force sensor of 50 kN. The results are summarized in Table 3.

[0065] [Table 3] The present invention includes the following embodiments. (Embodiment 1) A fiber-matrix composition having a fiber component consisting of reinforcing fibers and a matrix component containing an epoxy resin and a curing agent, wherein the curing agent is represented by the formula I H 2 NA-(NH-A-) n NH 2 (I) [In the formula, A independently represents a group of the formula -CHR-CH 2 -or-CH 2 and wherein R=H, ethyl, or methyl, but at least one A in the alkyl-substituted ethyleneamine of formula I is an ethylene group of the formula -CHR-CH 2 -or-CH 2 an alkylethylene group of the formula -CHR-, where R=ethyl or methyl; n = 1 to 4] 1. A fiber-matrix composition comprising at least one alkyl-substituted ethyleneamine of the formula: (Embodiment 2) A is independently a compound of the formula -CH(CH 3 )-CH 2 -or-CH 2 -CH(CH 3 2. The fiber-matrix composition of embodiment 1, wherein n is a methylethylene group of the formula: (Embodiment 3) The alkyl-substituted ethyleneamine is represented by the formula II H 2 NA-NH-A-NH 2 (II) [wherein A independently represents a group of the formula -CH(CH3 )-CH 2 -or-CH 2 -CH(CH 3 )-methylethylene group] 2. The fiber-matrix composition of embodiment 1, wherein the dimethyldiethylenetriamine is dimethyldiethylenetriamine. (Embodiment 4) 4. The fiber-matrix composition of any one of the preceding embodiments, wherein the alkyl-substituted ethyleneamine comprises at least 50% by weight, based on the total amount of curatives in the fiber-matrix composition. (Embodiment 5) 5. The fiber-matrix composition of any one of the preceding claims, wherein the epoxy resin is selected from the group consisting of diglycidyl ethers of bisphenol A, diglycidyl ethers of bisphenol F, diglycidyl ethers of hydrogenated bisphenol A, and diglycidyl ethers of hydrogenated bisphenol F, or mixtures thereof. (Embodiment 6) 6. The fiber-matrix composition of any one of the preceding claims, wherein the reinforcing fibers are glass fibers or carbon fibers or a mixture thereof. (Embodiment 7) 7. The fiber-matrix composition of any one of the preceding embodiments, wherein the reinforcing fibers are impregnated with the matrix component. (Embodiment 8) 8. A method of producing a cured composite material, comprising providing a fiber-matrix composition according to any one of embodiments 1 to 7, and then curing. (Embodiment 9) 9. The method of embodiment 8, wherein the curing is carried out at a temperature in the range of 70 to 180° C. (Embodiment 10) 10. The method of claim 8 or 9, wherein the fiber-matrix composition is provided by impregnating the reinforcing fibers with a matrix component. (Embodiment 11) a. A process of arranging a large number of reinforcing fibers to obtain a bundle; b. drawing the bundle through an impregnation device to impregnate the reinforcing fibers in the bundle with the matrix component; c. drawing the impregnated reinforcing fiber bundle through a second heating device and curing the bundle in the second heating device at a temperature in the range of 70-180° C. to obtain a cured composite material; 9. The method of embodiment 8, comprising: (Embodiment 12) a. impregnating one or more reinforcing fibers with a matrix component and then winding the one or more impregnated reinforcing fibers thus obtained onto a winding core to obtain an uncured composite material; b. curing the uncured composite material at a temperature in the range of 70-180° C. to obtain a cured composite material. (Embodiment 13) 13. The method according to any one of embodiments 8 to 12, wherein the reinforcing fibers are used in the form of continuous fiber filaments, continuous fiber rovings, or continuous fiber mats. (Embodiment 14) A cured composite material obtainable by the method according to any one of embodiments 8 to 13. (Embodiment 15) 15. A molded article comprising the cured composite material of embodiment 14. (Embodiment 16) 15. A reinforcing bar comprising the hardened composite material of embodiment 14. (Embodiment 17) As a curing agent in the production of epoxy resin-based composites, H 2 NA-(NH-A-) n NH 2 (I) [In the formula, A independently represents a group of the formula -CHR-CH 2 -or-CH 2 and wherein R=H, ethyl, or methyl, but at least one A in the alkyl-substituted ethyleneamine of formula I is an ethylene group of formula -CHR-CH 2 -or-CH 2 an alkylethylene group of the formula -CHR-, where R=ethyl or methyl; n = 1 to 4] Use of alkyl substituted ethyleneamines.

Claims

1. A fiber-matrix composition having a fiber component consisting of reinforcing fibers and a matrix component containing an epoxy resin and a curing agent, wherein the curing agent is represented by the formula I H 2 N-A-(NH-A-) n NH 2 (I) [In the formula, A independently represents a group of the formula -CHR-CH 2 -or-CH 2 and at least one A of the alkyl-substituted ethyleneamine of formula I is an ethylene group of the formula -CHR-, where R=H, ethyl, or methyl. 2 -or-CH 2 an alkylethylene group of the formula -CHR-, where R=ethyl or methyl; n = 1 to 4] 1. A fiber-matrix composition comprising at least one alkyl-substituted ethyleneamine of the formula:

2. A is independently a compound of the formula -CH(CH 3 )-CH 2 -or-CH 2 -CH(CH 3 2. The fiber-matrix composition of claim 1, wherein n is a methylethylene group of the formula:

3. The alkyl-substituted ethyleneamine is represented by the formula II H 2 NA-NH-A-NH 2 (II) [wherein A independently represents a group of the formula -CH(CH 3 )-CH 2 -or-CH 2 -CH(CH 3 )-methylethylene group] 2. The fiber-matrix composition of claim 1, wherein the dimethyldiethylenetriamine is dimethyldiethylenetriamine.

4. 4. The fiber-matrix composition of claim 1, wherein the alkyl-substituted ethyleneamine comprises at least 50% by weight, based on the total amount of curatives in the fiber-matrix composition.

5. 5. The fiber-matrix composition of claim 1, wherein the epoxy resin is selected from the group consisting of diglycidyl ethers of bisphenol A, diglycidyl ethers of bisphenol F, diglycidyl ethers of hydrogenated bisphenol A, and diglycidyl ethers of hydrogenated bisphenol F, or mixtures thereof.

6. 6. The fiber-matrix composition according to claim 1, wherein the reinforcing fibers are glass fibers or carbon fibers or a mixture thereof.

7. 7. The fiber-matrix composition of claim 1, wherein the reinforcing fibers are impregnated with the matrix component.

8. 8. A method for producing a cured composite material, comprising providing a fiber-matrix composition according to any one of claims 1 to 7, followed by curing.

9. The method of claim 8, wherein the curing is carried out at a temperature in the range of 70 to 180°C.

10. 10. The method of claim 8 or 9, wherein the fiber-matrix composition is provided by impregnating the reinforcing fibers with a matrix component.

11. a. A process of arranging a large number of reinforcing fibers to obtain a bundle; b. drawing the bundle through an impregnation device to impregnate the reinforcing fibers in the bundle with the matrix component; c. drawing the impregnated reinforcing fiber bundle through a second heating device and curing the bundle in the second heating device at a temperature in the range of 70-180°C to obtain a cured composite material; 9. The method of claim 8, comprising:

12. a. impregnating one or more reinforcing fibers with a matrix component and then winding the one or more impregnated reinforcing fibers thus obtained onto a winding core to obtain an uncured composite material; b. curing the uncured composite material at a temperature in the range of 70-180° C. to obtain a cured composite material.

13. 13. The method according to any one of claims 8 to 12, wherein the reinforcing fibers are used in the form of continuous fiber filaments, continuous fiber rovings, or continuous fiber mats.

14. A cured composite material obtained by curing the fiber-matrix composition of any one of claims 1 to 7.

15. A molded article comprising the cured composite material of claim 14.

16. A reinforcing bar comprising the hardened composite material of claim 14.

17. As a curing agent in the production of epoxy resin-based composites, H 2 N-A-(NH-A-) n NH 2 (I) [In the formula, A independently represents a group of the formula -CHR-CH 2 -or-CH 2 and wherein R=H, ethyl, or methyl, but at least one A in the alkyl-substituted ethyleneamine of formula I is an ethylene group of formula -CHR-CH 2 -or-CH 2 an alkylethylene group of the formula -CHR-, where R=ethyl or methyl; n = 1 to 4] Use of alkyl substituted ethyleneamines.

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