DE102012015315A1 - Liquid curing agent useful for curing polymer resins, preferably curable polymer resins comprising epoxide resins, preferably impregnated fiber materials or impregnated fabrics, comprises cyanamide, urea derivative, and viscosity modifier - Google Patents

Abstract

Liquid curing agent comprises (a) cyanamide, (b) at least one urea derivative (I), and (c) at least one viscosity modifier comprising mono-, di-, polyols, ethers, polyethers, polyether polyols ketones, aldehydes, nitriles and/or carboxylic esters. Liquid curing agent for curing polymer resins, preferably curable polymer resins comprising epoxide resins comprises (a) cyanamide, (b) at least one urea derivative of formula (I), and (c) at least one viscosity modifier comprising mono-, di-, polyols, ethers, polyethers, polyether polyols ketones, aldehydes, nitriles and/or carboxylic esters. either R1, R2 : H, 1-15C-alkyl or 3-15C cycloalkyl; or R1R2 : ring of 3-10C alkylene; and R3 : H, 1-15C alkyl, 3-15C cycloalkyl, aryl, arylalkyl, -NHC(O)NOR2 substituted 1-15C alkyl, -NHC(O)NR1R2 substituted 3-15C cycloalkyl, -NHC(O)NR1R2 substituted aryl or -NHC(O)NR1R2 substituted arylalkyl. Independent claims are also included for: (1) an epoxide resin composition comprising at least one curable epoxide resin and at least one liquid curing agent; (2) a polyurethane resin composition comprising at least one curable polyurethane resin and at least one liquid curing agent; and (3) a composite material comprising a support material, preferably a fiber material, at least one curable epoxide resin, curable polyurethane resin and at least one liquid curing agent. [Image].

Description

The present invention relates to novel liquid hardeners for curing curable polymer resins, in particular epoxy resins, and epoxy resin compositions comprising these hardeners for the production of fiber composites.

The use of thermosetting epoxy resins is widely used because of their good chemical resistance, their very good thermal and dynamic mechanical properties and their high electrical insulation capacity. In addition, epoxy resins show good adhesion on many substrates and are thus ideally suited for use in fiber composites. For use in fiber composites both good wetting of the fiber, d. H. a low viscosity of the selected resin formulation for compositing as well as high mechanical properties after curing desirable.

For the production of molded parts made of fiber composite materials, various methods are used, such as, for example, the prepreg process, various infusion or injection methods, in particular the RTM process (Resin Transfer Molding). Of these methods, infusion or injection methods in particular have become more important in recent years. Thus, for example, in the infusion process, dry reinforcing materials such as fiber mats, nonwoven fabrics, woven or knitted fabrics are covered with a dense vacuum film and soaked with resin formulations via distribution channels after application of the vacuum. These methods have the advantage that large elements with complicated geometry can be formed in a short time.

The epoxy resin formulation for an infusion or injection procedure must have a low viscosity to allow impregnation of the fiber materials in vacuum in appropriate time. If resin formulations having excessively high viscosities are used or if resin formulations are used which too rapidly produce excessively high viscosities during the injection period, unimpregnated parts and other imperfections in the resulting composite are obtained.

The curing of epoxy resins proceeds according to different mechanisms. In addition to curing with phenols or anhydrides, hardening with amines is often carried out. These substances are usually liquid and mix very well with epoxy resins. Due to the high reactivity and thus very low latency of such epoxy resin compositions are carried out in two parts. This means that the resin (A component) and hardener (B component) are stored separately and are mixed in the correct ratio just before use. In this case, "latent" means that a mixture of the individual components is stable under defined storage conditions. These two-component resin formulations are also referred to as so-called cold-curing resin formulations, wherein the hardeners used for this are usually selected from the group of amines or amidoamines.

One-component, thermosetting epoxy resin formulations, however, are ready to use ready-made, that is, that epoxy resin and hardener are factory mixed. Mixing errors of the individual components in use on site are therefore excluded. A prerequisite for this is formed by latent hardener systems which do not react with the epoxy resin at room temperature (can be stored), but readily react when heated, depending on the energy input. For such one-component epoxy resin formulations, for example, dicyandiamide is a particularly suitable and also cost-effective hardener. Under ambient conditions, appropriate resin-hardener mixtures can be stored for up to twelve (12) months.

Unfortunately, these epoxy resin blends with high latent dicyandiamide or other highly latent hardeners have the disadvantage that the hardeners are sparingly soluble in epoxy resins and are trapped and filtered out by the fiber mats in the infusion or injection process to produce fiber composites at the resin inlet sites. Thus, a homogeneous mixture of the hardener in the resins in the composite is prevented before use. This prevents hardening of the entire composite.

The patent literature describes a few suggestions for overcoming these disadvantages. Thus, both with the German patent application DE 27 43 015 A1 as well as the Austrian patent AT 351,772 in each case a method for curing epoxy resins using aqueous solutions of cyanamide or a mixture of cyanamide with up to 75 wt .-% urea described by cyanamide. Curing can also be carried out using catalytic amounts of accelerators become. Correspondingly prepared epoxy resin compositions can be used for the production of preimpregnated glass fiber fabrics, so-called prepregs. Thus, these two patent documents describe aqueous hard solutions which are liquid and which contain the stated components. The disadvantage here, however, is that the said hardeners are solutions whose solvent water must be removed during the curing process, so as not to adversely affect the quality of the finished cured molding. This disadvantage is independent of the choice of a solvent, since these solvents must always be removed during curing.

Furthermore, with the unpublished patent applications PCT / EP2012 / 053092 and PCT / EP2012 / 053091 liquid hardeners for curing curable polymer resins comprising cyanamide and at least one urea derivative of given formula.

It is an object of the present invention to provide novel hardeners for curing curable polymer resins, in particular curable epoxy resins, and also epoxy resin compositions which can be used for the production of composites and fiber-reinforced matrices. In this case, there was still the need for such hardeners to combine the advantages of the known amine hardeners and of the known dicyandiamide powder hardeners without taking over their disadvantages, such as low latency or filtration of the particles. These new hardeners should have a high latency thus a high storage stability below the curing temperature and a high reactivity at the curing temperature, allow complete crosslinking of the epoxy resin, be soluble or completely miscible in epoxy resins and for use in infusion, injection or RTM process be suitable.

wobei für die Reste gleichzeitig oder unabhängig voneinander gilt und mindestens ein Rest R¹, R², R³ ungleich Wasserstoff ist:
R¹, R² = gleichzeitig oder unabhängig voneinander Wasserstoff, C1- bis C15-Alkyl, C3- bis C15-Cycloalkyl oder gemeinsam unter Bildung eines Ringes C3- bis C10-Alkylen;
R³ = Wasserstoff, C1- bis C15-Alkyl, C3- bis C15-Cycloalkyl, Aryl, Arylalkyl,
mit -NHC(O)NR¹R² substituiertes C1- bis C15-Alkyl,
mit -NHC(O)NR¹R² substituiertes C3- bis C15-Cycloalkyl,
mit -NHC(O)NR¹R² substituiertes Aryl oder
mit -NHC(O)NR¹R² substituiertes Arylalkyl.These objects are achieved by liquid curing agents according to claim 1. Thus, according to a first embodiment, a liquid hardener for curing curable polymer resins, in particular curable epoxy resins, polyurethane resins and mixtures thereof, object of the present invention, the a) cyanamide, b) at least one urea derivative of the formula (I) and c) comprises at least one viscosity modifier selected from the group of mono-, di- and / or polyols, ethers, polyethers, polyether polyols, ketones, aldehydes, nitriles, carboxylic esters or mixtures thereof, wherein the urea derivatives have the following structure

where the radicals are the same or independent of one another and at least one radical R ¹ , R ² , R ^{3 is} other than hydrogen:
R ¹ , R ² = simultaneously or independently hydrogen, C 1 to C 15 alkyl, C 3 to C 15 cycloalkyl or together to form a ring C 3 to C 10 alkylene;
R ³ = hydrogen, C 1 - to C 15 -alkyl, C ³ - to C 15 -cycloalkyl, aryl, arylalkyl,
with -NHC (O) NR ¹ R ² substituted C1 to C15-alkyl,
with -NHC (O) NR ¹ R ² substituted C 3 to C 15 cycloalkyl,
with -NHC (O) NR ¹ R ² substituted aryl or
with -NHC (O) NR ¹ R ² substituted arylalkyl.

Essential to the invention, a liquid hardener according to the present invention comprises cyanamide (CAS 420-04-2). Surprisingly, it has been found that intensive mixing of cyanamide and at least one urea derivative of the formula (I) with the meanings given above results in liquid to semi-liquid mixtures with low melting points (in comparison to the starting materials) which completely dissolve in epoxy resin at room temperature or completely Mix. Although analytically separate substances are still present, DSC analyzes show endothermic melting peaks of single-component systems. These mixtures can be mixed without substantial influence on their liquid state with viscosity modifiers from the group of mono-, di- and / or polyols, ethers, polyethers, ether alcohols, polyether polyols, ketones, aldehydes, nitriles, carboxylic acid esters or mixtures thereof and are excellent for the curing of curable polymer resins, in particular curable epoxy resins, curable polyurethane resins or mixtures thereof, suitable. Their mode of action in the epoxy resin is comparable to the curing properties of imidazole-accelerated dicyandiamide and is <100 ° C. Nevertheless, a latency of several days to several weeks remains at room temperature.

Surprisingly, it has also been found that liquid hardeners according to the invention consistently initiate curing of the polymer resins at lower temperatures compared to powder mixtures or suspensions of the same composition, and thus allow a shorter time for the production of molded parts.

In addition, the viscosity of the finished formulated resins, in particular of epoxy resin compositions, can be significantly influenced by the liquid hardener according to the invention, whereby these hardeners are eminently suitable for use in infusion resins or resins for the production of prepregs, in particular since a considerable time savings for the production of molded parts is made possible. For example, to prepare prepregs, a viscosity modifier can be used which causes an increase in viscosity of the resulting resin composition. As a result, a particularly good adhesion of the resulting resin composition is achieved on the Trägerermatrialien. On the other hand, the viscosity of the resin composition to be produced can be reduced by adding suitable viscosity modifiers by adding a corresponding viscosity modifier to the liquid hardeners according to the invention. Such liquid hardeners with viscosity-reducing properties are particularly well applicable in infusion or injection procedures. These viscosity modifiers can be added to the liquid hardeners according to the invention without significantly affecting their liquid state. It was particularly surprising here that these modifiers in many cases do not affect the latency of the resinous compositions mixed with the liquid hardeners. Rather, it could also be shown that the latency was increased and thus the shelf life of the resulting resin compositions could be improved.

It should be emphasized that the usual disadvantages of other liquid Hartem, such as a very low latency and thus very high reactivity even at room temperature, is not observed. In addition, resins cured with the hardener of the present invention can provide high glass transition temperatures with resins cured in comparison to amine hardeners.

Overall, a liquid hardener can thus be made available which, due to the high latency in the polymer resin compositions and the high reactivity in the polymer resin compositions at the curing temperature, is outstandingly suitable for use in infusion or injection methods.

In a further development of the present invention it can be provided that the liquid hardener comprises cyanamide and at least one urea derivative of the formula (I) or mixtures of these urea derivatives in a molar ratio of cyanamide: urea derivative or urea derivative mixture of 1: 1 to 4: 1. In particular, according to the present invention, it is provided that the molar ratio of cyanamide: urea derivative or urea derivative mixture is 1: 1 to 3: 1 and furthermore preferably 1: 1 to 2: 1 and very preferably 2: 1 to 4: 1.

In the presence of at least one viscosity modifier of the group of mono-, di- and / or polyols, ethers, polyethers, ether alcohols, polyether polyols, ketones, aldehydes, nitriles, carboxylic esters or mixtures thereof, the molar ratios of cyanamide: urea derivative also outside the preferred range of 1 : 1 to 4: 1. For example, molar ratios of cyanamide: urea derivative of 0.1 to <1: 1, in particular from 0.2 to <1: 1, possible, but also molar ratios of cyanamide: urea derivative of> 4: 1 to 20: 1, in particular > 4: 1 to 10: 1.

In this case, a hardener according to the present invention should be understood to mean a hardener which has a melting point S _m with S _m <20 ° C. (normal pressure) or is liquid at a temperature of 20 ° C. (normal pressure) and has a viscosity of less than 1 Pa · s. The liquid hardeners according to the invention preferably have a viscosity of ≦ 100 mPa · s, more preferably <20 mPa · s and even more preferably ≦ 12 mPa · s at 25 ° C. However, particular preference is given to those liquid hardeners which have a melting point S _m with S _m <10 ° C. (normal pressure), very particularly preferably a melting point S _m with S _m <0 ° C. (normal pressure) or at a temperature of 10 ° C (normal pressure), most preferably at a temperature of 0 ° C (atmospheric pressure), are liquid and have a viscosity of less than 1 Pa · s.

It should be emphasized in this case that these hardeners are liquid as such and in particular in addition to cyanamide, at least one urea derivative or mixtures thereof and at least one viscosity modifier no solvent or solubilizer include and thus solvent-free or solubilizer-free. It is in the context of the present invention under a solvent or solubilizer any inorganic or organic solvents or solvents or solubilizers or mixtures thereof which is used in the chemical synthesis or in the analytics to prepare a solution. However, viscosity modifiers according to the present invention are not solvents. In the context of the present invention, the term "solvent-free or solubilizer-free" is understood as meaning a hardener which is essentially free from solvents or solubilizers and contains at most 1.0% by weight of solvent or solubilizer as a result of the preparation.

In an alternative embodiment, however, it is also possible for the hardeners to contain a solvent, in particular water. The addition of solvent is not required to make the mixtures liquid, but may be favorable for other process engineering requirements.

Furthermore, in the context of the present invention, C1- to C15-alkyl is understood to mean a linear or branched alkyl radical having a chain length of up to 15 carbon atoms, which in particular has the general formula C _n H _{2n + a} , where n = 1 to 15 , In this case, it is preferably provided that C 1 - to C 15 -alkyl methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl or decyl, these alkyl radicals furthermore preferably also unbranched, monobranched, multi-branched or alkyl-substituted ,

Preference is given to those C 1 - to C 15 -alkyl radicals which in turn are monosubstituted or polysubstituted by alkyl, in particular substituted by C 1 - to C 5 -alkyl. C 1 to C 5 alkyl according to the present invention may furthermore preferably be methyl, ethyl, n-propyl, 1-methylethyl, n-butyl, 1-methylpropyl, 2-methylpropyl, 1,1-dimethylethyl, n-pentyl, 1-methylbutyl , 2-methylbutyl, 3-methylbutyl, 1,1-dimethylpropyl, 1,2-dimethylpropyl, 2,2-dimethylpropyl or 1-ethylpropyl. Thus, C1- to C15-alkyl according to the present invention may in particular also be 1-methylethyl, 1-methylpropyl, 1-methylbutyl, 1-methylpentyl, 1-methylhexyl, 1-methylheptyl, 1-methyloctyl, 1-methylnonyl, 1-methyldecanyl, 1-ethylpropyl, 1-ethylbutyl, 1-ethylpentyl, 1-ethylhexyl, 1-ethylheptyl, 1-ethyloctyl, 1-ethylnonyl, 1-ethyldecanyl, 2-methylpropyl, 2-methylbutyl, 2-methylpentyl, 2-methylhexyl, 2- Methylheptyl, 2-methyloctyl, 2-methylnonyl, 2-methyldecanyl, 2-ethylpropyl, 2-ethylbutyl, 2-ethylpentyl, 2-ethylhexyl, 2-ethylheptyl, 2-ethyloctyl, 2-ethylnonyl, 2-ethyldecanyl, 1,1- Dimethylethyl, 1,1-dimethylpropyl, 1,1-dimethylbutyl, 1,1-dimethylpentyl, 1,1-dimethylhexyl, 1,1-dimethylheptyl, 1,1-dimethyloctyl, 1,1-dimethylnonyl, 1,1-dimethyldecanyl, 1,2-dimethylpropyl, 1,2-dimethylbutyl, 1,2-dimethylpentyl, 1,2-dimethylhexyl, 1,2-dimethylheptyl, 1,2-dimethyloctyl, 1,2-dimethylnonyl, 1,2-dimethyldecanyl, 2- Ethyl 1-methylbutyl, 2-ethyl-1-methylpentyl, 2-ethyl-1-methylhexyl, 2-ethyl-1-methyl heptyl, 2-ethyl-1-methyloctyl, 2-ethyl-1-methylnonyl, 2-ethyl-1-methyldecanyl, 1-ethyl-2-methylpropyl, 1-ethyl-2-methylbutyl, 1-ethyl-2-methylpentyl, 1-ethyl-2-methylhexyl, 1-ethyl-2-methylheptyl, 1-ethyl-2-methyloctyl, 1-ethyl-2-methylnonyl or 1-ethyl-2-methyldecanyl.

Furthermore, a C1- to C15-alkyl radical, in particular methyl, ethyl, propyl, butyl, in turn may also be substituted by a C3- to C15-cycloalkyl radical, where C3- to C15-cycloalkyl has the meaning given below. Thus, C1- to C15-alkyl, in particular also C3- to C15-cycloalkylmethyl, 1- (C3- to C15-cycloalkyl) -1-ethyl, 2- (C3- to C15-cycloalkyl) -1-ethyl, 1 - (C3 to C15 cycloalkyl) -1-propyl, 2- (C3 to C15 cycloalkyl) -1-propyl or 3- (C3 to C15 cycloalkyl) -1-propyl, wherein C3 to C15 -Cycloalkyl having reproduced below.

In the context of the present invention, C3- to C15-cycloalkyl is understood as meaning a monocyclic or bicyclic cycloalkyl radical having 3 to 15 carbon atoms, in particular a cycloalkyl radical which has the general formula C _n H _2n-1 with n = 3 to 15. Furthermore, C 3 -C 15 -cycloalkyl may preferably be cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl or cycloheptyl, where these cycloalkyl radicals may in turn be further preferably monosubstituted or polysubstituted by C 1 - to C 5 -alkyl radicals of the meaning given above. It is furthermore preferably possible for C 3 -C 15 -cycloalkyl to also be 1-methyl-1-cyclopropyl, 1-methyl-1-cyclobutyl, 1-methyl-1-cyclopentyl, 1-methyl-1-cyclohexyl, 1-methyl-1-cycloheptyl , 2-methyl-1-cyclopropyl, 2-methyl-1-cyclobutyl, 2-methyl-1-cyclopentyl, 2-methyl-1-cyclohexyl, 2-methyl-1-cycloheptyl, 3-methyl-1-cyclobutyl, 3 Methyl 1-cyclopentyl, 3-methyl-1-cyclohexyl, 3-methyl-1-cycloheptyl, 4-methyl-1-cyclohexyl, 4-methyl-1-cycloheptyl, 1,2-dimethyl-1-cyclopropyl, 2 , 2-dimethyl-1-cyclopropyl, 2,3-dimethyl-1-cyclopropyl, 1,2-dimethyl-1-cyclobutyl, 1,3-dimethyl-1-cyclobutyl, 2,2-dimethyl-1-cyclobutyl, 2 , 3-Dimethyl-1-cyclobutyl, 2,4-dimethyl-1-cyclobutyl, 3,3-dimethyl-1-cyclobutyl, 1,2-dimethyl-1-cyclopentyl, 1,3-dimethyl-1-cyclopentyl, 2 , 2-Dimethyl-1-cyclopentyl, 2,3-dimethyl-1-cyclopentyl, 2,4-dimethyl-1-cyclopentyl, 2,5-dimethyl-1-cyclopentyl, 3,3-dimethyl-1-cyclopentyl, 3 , 4-dimethyl-1-cyclopentyl, 1,2-dimethyl-1-cyclohexyl, 1,3-dimethyl-1-cyclohexyl, 1,4-dimethyl-1-cyclohexyl, 1,5-dimethyl 1-cyclohexyl, 1,6-dimethyl-1-cyclohexyl, 2,2-dimethyl-1-cyclohexyl, 2,3-dimethyl-1-cyclohexyl, 2,4-dimethyl-1-cyclohexyl, 2,5-dimethyl 1-cyclohexyl, 2,6-dimethyl-1-cyclohexyl, 3,3-dimethyl-1-cyclohexyl, 3, 4-dimethyl-1-cyclohexyl, 3,5-dimethyl-1-cyclohexyl, 3,6-dimethyl-1-cyclohexyl, 4,4-dimethyl-1-cyclohexyl, 1,2,2-trimethyl-1-cyclopropyl, 1,2,3-trimethyl-1-cyclopropyl, 1,2,2-trimethyl-1-cyclobutyl, 1,3,3-trimethyl-1-cyclobutyl, 1,2,3-trimethyl-1-cyclobutyl, 2, 2,3-trimethyl-1-cyclobutyl, 2,2,4-trimethyl-1-cyclobutyl, 1,2,2-trimethyl-1-cyclopentyl, 1,2,3-trimethyl-1-cyclopentyl, 1,2, 4-trimethyl-1-cyclopentyl, 1,2,5-trimethyl-1-cyclopentyl, 1,3,3-trimethyl-1-cyclopentyl, 1,3,4-trimethyl-1-cyclopentyl, 1,3,5- Trimethyl-1-cyclopentyl, 2,2,3-trimethyl-1-cyclopentyl, 2,2,4-trimethyl-1-cyclopentyl, 2,2,5-trimethyl-1-cyclopentyl, 2,3,3-trimethyl 1-cyclopentyl, 2,3,4-trimethyl-1-cyclopentyl, 2,3,5-trimethyl-1-cyclopentyl, 2,3,3-trimethyl-1-cyclopentyl, 2,4,4-trimethyl-1 Cyclopentyl, 2,4,5-trimethyl-1-cyclopentyl, 2,5,5-trimethyl-1-cyclopentyl, 3,3,4-trimethyl-1-cyclopentyl, 3,3,5-trimethyl-1-cyclopentyl, 3,4,5-trimethyl-1-cyclopentyl, 3,4,4-trimethyl-1-cyclopentyl, 1,2,2-trimethyl-1-cyclohexyl, 1 , 2,3-trimethyl-1-cyclohexyl, 1,2,4-trimethyl-1-cyclohexyl, 1,2,5-trimethyl-1-cyclohexyl, 1,2,6-trimethyl-1-cyclohexyl, 1,3 , 3-trimethyl-1-cyclohexyl, 1,3,4-trimethyl-1-cyclohexyl, 1,3,5-trimethyl-1-cyclohexyl, 1,3,6-trimethyl-1-cyclohexyl, 1,4,4 Trimethyl-1-cyclohexyl, 2,2,3-trimethyl-1-cyclohexyl, 2,2,4-trimethyl-1-cyclohexyl, 2,2,5-trimethyl-1-cyclohexyl, 2,2,6-trimethyl 1-Cyclohexyl, 2,3,3-trimethyl-1-cyclohexyl, 2,3,4-trimethyl-1-cyclohexyl, 2,3,5-trimethyl-1-cyclohexyl, 2,3,6-trimethyl-1 Cyclohexyl, 2,4,4-trimethyl-1-cyclohexyl, 2,4,5-trimethyl-1-cyclohexyl, 2,4,6-trimethyl-1-cyclohexyl, 2,5,5-trimethyl-1-cyclohexyl , 2,5,6-trimethyl-1-cyclohexyl, 2,6,6-trimethyl-1-cyclohexyl, 3,3,4-trimethyl-1-cyclohexyl, 3,3,5-trimethyl-1-cyclohexyl, 3 , 3,6-trimethyl-1-cyclohexyl, 3,4,4-trimethyl-1-cyclohexyl, 3,4,5-trimethyl-1-cyclohexyl, 3,4,6-trimethyl-1-cyclohexyl, 3,5 , 6-trimethyl-1-cyclohexyl, 1,2,3,3-tetramethyl-1-cyclopropyl, 2,2,3,3-tetramethyl-1-cyclopropyl, 1,2,2,3-tetramethyl-1-cycloprop yl, 1,2,2,3-tetramethyl-1-cyclobutyl, 1,2,3,3-tetramethyl-1-cyclobutyl, 2,2,3,3-tetramethyl-1-cyclobutyl, 2,3,3, 4-tetramethyl-1-cyclobutyl, 1,2,2,3-tetramethyl-1-cyclopentyl, 1,2,2,4-tetramethyl-1-cyclopentyl, 1,2,2,5-tetramethyl-1-cyclopentyl, 1,2,3,3-tetramethyl-1-cyclopentyl, 1,2,3,4-tetramethyl-1-cyclopentyl, 1,2,3,5-tetramethyl-1-cyclopentyl, 1,2,5,5- Tetramethyl-1-cyclopentyl, 2,2,3,3-tetramethyl-1-cyclopentyl, 2,2,3,3-tetramethyl-1-cyclohexyl, 2,2,4,4-tetramethyl-1-cyclohexyl, 2, 2,5,5-tetramethyl-1-cyclohexyl, 3,3,4,4-tetramethyl-1-cyclohexyl, 3,3,5,5-tetramethyl-1-cyclohexyl, 1-ethyl-1-cyclopropyl, 1 Ethyl 1-cyclobutyl, 1-ethyl-1-cyclopentyl, 1-ethyl-1-cyclohexyl), 1-ethyl-1-cycloheptyl, 2-ethyl-1-cyclopropyl, 2-ethyl-1-cyclobutyl, 2-ethyl 1-cyclopentyl, 2-ethyl-1-cyclohexyl, 2-ethyl-1-cycloheptyl, 3-ethyl-1-cyclobutyl, 3-ethyl-1-cyclopentyl, 3-ethyl-1-cyclohexyl, 3-ethyl-1 Cycloheptyl, 4-ethyl-1-cyclohexyl or 4-ethyl-1-cycloheptyl.

According to the present invention, R ¹ and R ^{2 may} also together be C 3 -C 10 -alkylene, wherein R ¹ and R ² together with the nitrogen of the urea derivative form a nitrogen-containing ring. In particular, it may be provided in this case that R ¹ and R ² together denote ethylene, propylene, butylene, pentylene or hexylene, these alkylene radicals in turn may optionally be monosubstituted or polysubstituted by alkyl radicals. In this case, R ¹ and R ² together with the nitrogen of the urea derivative forms an aziridine, azetidine, azolidine, azinane or azepane, which in turn may optionally be monosubstituted or polysubstituted by C 1 - to C 5 -alkyl radicals of the meaning given above.

According to the present invention, -NHC (O) NR ¹ R ^{2 represents} a 1-ureayl radical which is substituted on the nitrogen N 3 by the radicals R ¹ and R ² , wherein R ¹ and R ^{2 have} the meanings given above, and is bound to a backbone via the nitrogen N1.

Halogen means according to the present invention, in particular fluorine, chlorine or bromine.

According to the present invention, aryl is in particular an aromatic aryl radical having from 3 to 20 carbon atoms, which may furthermore, in turn, preferably be monosubstituted or polysubstituted by a C 1 to C 5 alkyl radical of the meaning given above. Particularly preferably it can be provided that the aryl radical used is a benzene radical, naphthalene radical, anthracene radical or perylene radical, which in turn may be monosubstituted or polysubstituted by a C 1 to C 5 alkyl radical of the meaning given above. Thus, aryl is especially toluyl, xylenyl, pseudocumolyl or mesitylenyl.

According to the present invention arylalkyl is a C1-C15 alkyl radical of the meaning given above, which is substituted by an aryl radical of the meaning given above. In particular, arylalkyl may be a benzyl radical.

Particular preference is given to liquid hardeners according to the invention comprising at least one aliphatic urea derivative of the formula (I). In these aliphatic urea derivatives according to formula (I), R ¹ and R ^{2 are} simultaneously or independently hydrogen or C 1 to C 15 alkyl and R ³ is hydrogen, C 1 to C 15 alkyl, C 3 to C 15 cycloalkyl, with -NHC (O) NR ¹ R ² substituted C 1 to C 15 alkyl or C ^{1 to} C 15 cycloalkyl substituted with -NHC (O) NR ¹ R ² .

The liquid hardeners according to the invention particularly preferably comprise at least one urea derivative of the formula (I) in which at least one of the radicals R ¹ and R ^{2 is} a methyl radical. Particularly preferred is methylurea, 1,3-dimethylurea or 1,1-dimethylurea (ie R ¹ = R ² = methyl and R ³ = H).

wobei für die Reste gleichzeitig oder unabhängig voneinander gilt:
R¹, R² = gleichzeitig oder unabhängig voneinander Wasserstoff, C1- bis C15-Alkyl, C3- bis C15-Cycloalkyl oder gemeinsam unter Bildung eines Ringes C3- bis C10-Alkylen;
R⁴, R^{4 '}, R⁵, R^{5 '}, R⁶, R^{6 '}, R⁷, R^7', R⁸, R^{8 '} = gleichzeitig oder unabhängig voneinander Wasserstoff, C1- bis C15-Alkyl, C3- bis C15-Cycloalkyl, -NHC(O)NR¹R² oder
mit -NHC(O)NR¹R² substituiertes C1- bis C15-Alkyl.Also preferred are aliphatic urea derivatives of the formula (I) in which R ¹ and R ^{2 have} the abovementioned meaning, in particular hydrogen, methyl or ethyl, and R ^{3 is} C1- to C15 -NHC (O) NR ¹ R ² -substituted Cycloalkyl means. Very particular preference is given to liquid hardeners comprising aliphatic urea derivatives of the formula (II)

where the radicals are the same or independent of each other:
R ¹ , R ² = simultaneously or independently hydrogen, C 1 to C 15 alkyl, C 3 to C 15 cycloalkyl or together to form a ring C 3 to C 10 alkylene;
R ⁴ , R ^{4 '} , R ⁵ , R ^{5 '} , R ⁶ , R ^{6 '} , R ⁷ , R ^7' , R ⁸ , R ^{8 '} = simultaneously or independently of one another hydrogen, C 1 - to C 15 -alkyl, C 3 - to C 15 -cycloalkyl, -NHC (O) NR ¹ R ² or
with -NHC (O) NR ¹ R ² substituted C1 to C15 alkyl.

Also preferred are liquid hardeners comprising aliphatic urea derivatives of the formula (II) in which R ¹ and R ^{2 are} simultaneously or independently hydrogen or methyl and R ⁴ , R ^{4 '} , R ⁵ , R ^{5 '} , R ⁶ , R ^{6 '} , R ⁷ , R ^{7 '} , R ⁸ , R ^{8 '} mean, simultaneously or independently, of hydrogen, methyl, ethyl, -NHC (O) NR ¹ R ² or -NHC (O) NR ¹ R ² substituted methyl or ethyl. Particularly preferred is 1- (N, N-dimethylurea) -3- (N, N-dimethylureamethyl) -3,5,5-trimethylcyclohexane, hereinafter also N '- [3 - [[[(dimethylamino) carbonyl] amino] methyl ] -3,5,5-trimethylcyclohexyl] -N, N-dimethyl-urea (ie R ¹ = R ² = R ⁵ = R ^{5 '} , = R ⁷ = methyl and R ^{7 '} = -CH ₂ -NHC (O ) N (CH ₃ ) ₂ and R ⁴ = R ^{4 '} = R ⁸ = R ^6' = R ⁸ = R ^{8 '} = hydrogen).

wobei die Reste R¹, R² die oben angegebene Bedeutung aufweisen und für die weiteren Reste gleichzeitig oder unabhängig voneinander gilt:
R⁴, R⁵, R⁶, R⁷, R⁸ = Wasserstoff, Halogen, C1- bis C15-Alkyl, C3- bis C15-Cycloalkyl, Aryl, Arylalkyl, -CF₃, -NHC(O)NR¹R²,
mit -NHC(O)NR¹R² substituiertes C1- bis C15-Alkyl,
mit -NHC(O)NR¹R² substituiertes Aryl oder
mit -NHC(O)NR¹R² substituiertes Arylalkyl;
R⁹, R¹⁹ = gleichzeitig oder unabhängig voneinander Wasserstoff oder C1- bis C5-Alkyl;
n = eine Zahl zwischen 0 und 10.In an alternative embodiment, however, it can also be provided that a liquid hardener according to the invention comprises an aromatic urea derivative. Thus, this liquid curing agent comprises at least one urea derivative of the formula (I) in which the radical R ³ = aryl, arylalkyl, with -NHC (O) NR ¹ R ² substituertes aryl or -NHC (O) NR ¹ R ² substituertes arylalkyl for a radical of the general formula (III)

where the radicals R ¹ , R ^{2 have} the abovementioned meaning and the following radicals have the same or independent of one another:
R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ = hydrogen, halogen, C 1 - to C 15 -alkyl, C 3 - to C 15 -cycloalkyl, aryl, arylalkyl, -CF ₃ , -NHC (O) NR ¹ R ² .
with -NHC (O) NR ¹ R ² substituted C1 to C15-alkyl,
with -NHC (O) NR ¹ R ² substituted aryl or
arylalkyl substituted with -NHC (O) NR ¹ R ² ;
R ⁹ , R ¹⁹ = simultaneously or independently of one another are hydrogen or C 1 - to C 5 -alkyl;
n = a number between 0 and 10.

in welcher R¹, R², R⁴ und R⁵ die oben angegebenen Bedeutungen aufweisen und insbesondere gleichzeitig oder unabhängig voneinander Wasserstoff, C1-C15-Alkyl, darstellen. Bevorzugt bedeuten die Reste R¹ und R² in Zusammenhang mit der Formel (VI) ein Methylrest. Besonders bevorzugt ist 1,1'-(4-Methyl-m-phenylen)-bis-(3,3-dimethylharnstoff) und 1,1'-(2-Methyl-m-phenylen)-bis-(3,3-dimethylharnstoff) (also R¹ = R² = R⁵ Methyl und R⁴ Wasserstoff).Of these aromatic urea derivatives, particular preference is given to those urea derivatives in which the radicals R ⁴ , R ⁵ , R ⁸ , R ⁷ and R ^8, simultaneously or independently of one another, are hydrogen, C 1 - to C 15 -alkyl, -NHC (O) NR ¹ R ² , with -NHC (O) NR ¹ R ² substituted C 1 to C 15 aryl or with -NHC (O) NR ¹ R ² substituted C 1 to C 15 arylalkyl. Also preferred are liquid hardeners comprising urea derivatives of the formula (IV)

in which R ¹ , R ² , R ⁴ and R ^{5 have} the meanings given above and in particular simultaneously or independently of one another are hydrogen, C ¹ -C 15 -alkyl. The radicals R ¹ and R ² in connection with the formula (VI) preferably represent a methyl radical. Particularly preferred is 1,1 '- (4-methyl-m-phenylene) bis (3,3-dimethylurea) and 1,1' - (2-methyl-m-phenylene) bis- (3,3- dimethylurea) (ie R ¹ = R ² = R ⁵ methyl and R ^{4 is} hydrogen).

According to a further embodiment it can be provided in particular that the liquid hardener according to the invention comprises a) cyanamide, b) two different urea derivatives of the formulas (I), (II) and / or (IV) and c) contains at least one viscosity modifier, in particular contains these liquid hardeners furthermore preferably comprise cyanamide and two different urea derivatives of the formula (I), (II) and / or (IV) in a molar ratio cyanamide: urea derivative or urea derivative mixture of 1: 1 to 4: 1.

According to a further embodiment of the invention, such liquid hardeners are the subject of the invention which a) cyanamide, b) at least one urea derivative selected from the group urea, 1-methylurea, 1,1-dimethylurea, 1,3-dimethylurea, 3- (3 Chloro-4-methylphenyl) -1,1-dimethylurea, 3- (p-chlorophenyl) -1,1-dimethylurea, 3-phenyl-1,1-dimethylurea, 3- (3,4-dichlorophenyl) -1, 1-dimethylurea, 1,1 '- (methylenedi-p-phenylene) bis- (3,3-dimethylurea), 3- (3-trifluoromethylphenyl) 1,1-dimethylurea, 1,1' - (2-methyl- m-phenylene) -bis (3,3-dimethylurea) and / or 1,1 '- (4-methyl-m-phenylene) bis (3,3-dimethylurea); and c) at least one viscosity modifier, in particular cyanamide and the urea derivative or urea derivative mixture are furthermore preferably used in a molar ratio of 1: 1 to 4: 1.

Essential to the invention, liquid hardeners according to the present invention comprise at least one viscosity modifier selected from the group of mono-, di- and / or polyols, ethers, polyethers, ether alcohols, polyether polyols, ketones, aldehydes, nitriles, carboxylic esters or mixtures thereof. These viscosity modifiers may increase or decrease the viscosity of the resin compositions to be prepared, depending on the choice and application of the resin compositions to be prepared. Particularly preferred are liquid hardener comprising a viscosity modifier from the listed group, which in turn have a boiling point of at least 100 ° C. These modifiers remain during curing in the moldings to be produced and are preferably incorporated into the polymer matrix or additionally crosslink this polymer matrix.

Viscosity modifiers from the group of mono-, di- and / or polyols, ethers, polyethers, ether alcohols, polyether polyols or mixtures thereof have proven to be particularly effective viscosity modifiers, in particular those which in turn have a boiling point of at least 100.degree.

wobei für die Reste gleichzeitig oder unabhängig voneinander gilt:
R¹¹, R²² = gleichzeitig oder unabhängig voneinander Wasserstoff, -OH oder C1- bis C15-Alkyl;
R¹², R¹⁴, R¹⁶, R¹⁸, R²⁰ = gleichzeitig oder unabhängig voneinander Wasserstoff, -OH oder C1- bis C5-Alkyl;
R¹³, R¹⁵, R¹⁷, R¹⁹, R²¹ = gleichzeitig oder unabhängig voneinander Wasserstoff, -OH, -NH₂ oder C1- bis C5-Alkyl;
mit
n, o, s, q, t = gleichzeitig oder unabhängig voneinander eine Zahl von 0 bis 10; und
i) m, s, u = gleichzeitig oder unabhängig voneinander eine Zahl von 1 bis 10; und/oder
ii) p, t, u = gleichzeitig oder unabhängig voneinander eine Zahl von 1 bis 10.In a particularly preferred embodiment, a liquid hardener comprises at least one viscosity modifier selected from the group of mono-, di- and / or polyols, ethers, polyethers, ether alcohols or polyether polyols or mixtures thereof according to general formula (V)

where the radicals are the same or independent of each other:
R ¹¹ , R ²² = simultaneously or independently of one another are hydrogen, -OH or C 1 - to C 15 -alkyl;
R ¹² , R ¹⁴ , R ¹⁶ , R ¹⁸ , R ²⁰ = simultaneously or independently of one another hydrogen, -OH or C 1 - to C 5 -alkyl;
R ¹³ , R ¹⁵ , R ¹⁷ , R ¹⁹ , R ²¹ = simultaneously or independently of one another are hydrogen, -OH, -NH ₂ or C 1 - to C 5 -alkyl;
With
n, o, s, q, t = simultaneously or independently of one another a number from 0 to 10; and
i) m, s, u = simultaneously or independently of one another a number from 1 to 10; and or
ii) p, t, u = simultaneously or independently of one another a number from 1 to 10.

Preference is furthermore given to monoalcohols from the group of C 2 - to C 10 -alcohols and C 6 - to C 12 -alcohols, in particular 1-hexanol, 1-heptanol, 1-octanol, 1-nonanol, 1-decanol, 2-hexanol, 2 -Heptanol, 2-octanol, 2-nonanol, 2-decanol, 2-aminoethanol, 3-aminopropanol, 4-aminobutanol, 5-aminopentanol, 6-aminohexanol, 7-aminoheptanol, 8-aminooctanol, 9-aminononanol, 10-aminodecanol or mixtures thereof, the dialcohols from the group of C2 to C12 alcohols, in particular ethylene glycol, propylene glycol, butylene glycol, pentylene glycol, hexylene glycol or mixtures thereof, the trialcohols from the group of C3 to C12 alcohols, in particular 1,2,3 -Propanetriol, 1,2,3-butanetriol, 1,2,3-pentanetriol, 1,2,3-hexanetriol, 1,2,4-hexanetriol, 1,2,6-hexanetriol or mixtures thereof, the aldehydes from the Group of C6 to C12 aldehydes, in particular hexanal, heptanal, octanal, nonanal, decanal or mixtures thereof, of ketones, in particular 2-pentanone, 3-pentanone, 2-hexanone, 3-hexanone, 2-heptanone, 3-heptanone, 2-octanone, 3-octanone or mixtures thereof, the ethers, nitriles, polyethers, ether alcohols or polyether polyols from the group dibutyl ether, dipentyl ether, dihexyl ether, diheptyl ether, dioctyl ether, dinonyl ether, didecanyl ether, methoxy and ethoxy alcohols , Methoxy and ethoxydialcohols, polyethylene glycols, polypropylene glycols, polyethylene glycols, polyethylene glycol monoalkyl ethers, especially polyethylene glycol monomethyl ether, polyethylene glycol monoethyl ether, ethylhexyl ether, ethylheptyl ether, ethyloctyl ether, ethylnonyl ether, ethyldecanyl ether, benzonitrile, acetonitrile, or mixtures thereof.

In addition, studies have shown that better processing can be provided in infusion or injection processes, but also in prepreg processes, of a polymeric resin composition, especially an epoxy resin composition comprising a liquid hardener of the type described herein, if the liquid hardeners Furthermore, at least one Hartngsbeshleuniger from the class of imidazolines, hereinafter also 4,5-dihydro-1H-imidazoles, or the imidazoles is added.

The liquid hardeners according to the invention can be mixed without influencing their liquid state with hardening accelerators from the group of imidazolines according to formula (VI) or imidazoles according to formula (VII) and are excellent for curing curable polymer resins, in particular curable epoxy resins, curable polyurethane resins or mixtures thereof , suitable. Their mode of action in the epoxy resin is comparable to the curing properties of imidazole-accelerated dicyandiamide and is <100 ° C. Nevertheless, a latency of several days to several weeks remains at room temperature.

und wobei für die Reste gleichzeitig oder unabhängig voneinander gilt:
R³⁰ = gleichzeitig oder unabhängig voneinander Wasserstoff, C1- bis C15-Alkyl, C3- bis C15-Cycloalkyl, Aryl, Arylalkyl;
R³², R³⁴ = gleichzeitig oder unabhängig voneinander Wasserstoff, C1- bis C15-Alkyl, C3- bis C15-Cycloalkyl oder gemeinsam unter Bildung eines Ringes C3- bis C15-Alkylen;
R³³, R³⁵ = gleichzeitig oder unabhängig voneinander Wasserstoff, C1- bis C15-Alkyl, C3- bis C15-Cycloalkyl oder gemeinsam unter Bildung eines Ringes C3- bis C15-Alkylen.Thus, according to a further embodiment, a liquid hardener is the subject matter of the present invention which comprises d) at least one hardening accelerator from the class of imidazolines according to formula (VI) or imidazoles according to formula (VII), wherein the imidazolines and the imidazoles have the following structure

and wherein the radicals are the same or independent of one another:
R ³⁰ = simultaneously or independently of one another hydrogen, C 1 - to C 15 -alkyl, C 3 - to C 15 -cycloalkyl, aryl, arylalkyl;
R ³² , R ³⁴ = simultaneously or independently of one another are hydrogen, C 1 - to C 15 -alkyl, C 3 - to C 15 -cycloalkyl or together to form a ring C 3 - to C 15 -alkylene;
R ³³ , R ³⁵ = simultaneously or independently of one another hydrogen, C 1 - to C 15 -alkyl, C 3 - to C 15 -cycloalkyl or together to form a ring C 3 - to C 15 -alkylene.

These imidazolines and imadazoles, in combination with liquid cyanamide masterbatches and at least one urea derivative of the type described herein, have a very good cure-accelerating effect, with no substantial change in the liquid properties and the continued existence of liquid hardeners. In addition, it has been found, particularly surprisingly, that the latency of the liquid hardener can be improved in comparison to the basic mixtures or the liquid hardeners without a curing accelerator, and thus the shelf life can be increased. Overall, a hardener can thus be made available which, due to the high latency in the polymer resin compositions and the high reactivity in the polymer resin compositions at the curing temperature, is outstandingly suitable for use in infusion or injection methods.

Particular preference may liquid hardeners in development of the invention, a curing accelerator from the class of imidazolines according to formula (II) or the imidazoles according to formula (III), wherein the radicals are the same or independently:
R ³⁰ = hydrogen, methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decanyl or phenyl;
R ³² , R ³⁴ = simultaneously or independently of one another hydrogen, C 1 - to C 5 -alkyl or phenyl;
R ³³ , R ³⁵ = simultaneously or independently of one another are hydrogen, C 1 - to C 5 -alkyl or phenyl.

Very particular preference according to the present invention as curing accelerator imidazoles according to formula (II) or imidazoles according to formula (III) selected from the group 2-methyl-1H-imidazole, 2-ethyl-1H-imidazole, 2-propyl-1H-imidazole , 2-butyl-1H-imidazole, 2-pentyl-1H-imidazole, 2-hexyl-1H-imidazole, 2-heptyl-1H-imidazole, 2-octyl-1H-imidazole, 2-nonyl-1H-imidazole, 2 -Decyl-1H-imidazole, 2-phenyl-1H-imidazole, 2-methyl-1H-imidazoline, 2-ethyl-1H-imidazoline, 2-propyl-1H-imidazoline, 2-butyl-1H-imidazoline, 2-pentyl 1H-imidazoline, 2-hexyl-1H-imidazoline, 2-heptyl-1H-imidazoline, 2-octyl-1H-imidazoline, 2-nonyl-1H-imidazoline, 2-decyl-1H-imidazoline and / or 2-phenyl 1H-imidazoline. The imidazoles surprisingly continue to improve the latency compared to 1-alkylimidazoles and thus increase the storage stability of the liquid hardener.

According to a further advantageous embodiment, a liquid hardener for curing curable polymer resins is therefore also the subject of the present invention, which comprises a) cyanamide, b) at least one urea derivative of the formula (I), (IV) and / or (VI), c) a Viscosity modifier, in particular a viscosity modifier according to formula (V) and d) at least one curing accelerator from the class of imidazolines according to formula (VI) or imidazoles according to formula (VII) comprises, in particular, wherein the liquid hardener preferably cyanamide and at least one urea derivative of Formula (I), (II) or (IV) in a molar ratio of cyanamide: urea derivative or urea derivative mixture of 1: 1 to 4: 1.

In the presence of at least one curing accelerator from the class of imidazolines according to formula (VI) or imidazoles according to formula (VII), the molar ratios of cyanamide: urea derivative may also be outside the preferred range of 1: 1 to 4: 1. For example, molar ratios of cyanamide: urea derivative of 0.1 to <1: 1, in particular from 0.2 to <1: 1, possible, but also molar ratios of cyanamide: urea derivative of> 4: 1 to 20: 1, in particular > 4: 1 to 10: 1.

Furthermore, it has surprisingly been found that a particularly high latency and thus high storage stability of the hardener itself and also of epoxy resin compositions comprising these hardeners can be adjusted if the hardeners are further added a stabilizer from the group of inorganic or organic acids becomes. By adding stabilizers from the group of inorganic or organic acids, the latency could be doubled, in some cases even tripled. At the same time, the excellent curing properties, such as the high reactivity at the curing temperature, are maintained compared to the hardeners without stabilizers.

Thus, according to a further embodiment, the present invention also encompasses a liquid hardener which preferably also comprises e) a stabilizer selected from the group of inorganic or organic acids.

As stabilizers in particular organic acids from the group of aromatic and non-aromatic carboxylic acids, dicarboxylic acids or tricarboxylic acids have been found particularly suitable. Also preferred as organic acids or as aromatic and non-aromatic carboxylic acids, dicarboxylic acids or tricarboxylic acids are acids from the group of formic acid, acetic acid, propionic acid, maleic acid, malonic acid, salicylic acid, lactic acid, citric acid, oxalic acid, adipic acid, benzoic acid, phthalic acid, alkyl sulfonic acids, arylsulfonic acids , in particular toluenesulfonic acid, or their anhydrides are used.

However, it can also be provided that hardeners according to the invention comprise as stabilizer inorganic acids selected from the group hydrochloric acid, sulfuric acid, sulfurous acid, phosphoric acid, phosphorous acid, ortho-phosphoric acid, diphosphoric acid, triphosphoric acid, polyphosphoric acid, nitric acid or their anhydrides. Thus, a liquid hardener is the subject of the present invention which comprises as stabilizer an inorganic or organic acid from the group of salicylic acid, phthalic acid, toluenesulfonic acid, sulfuric acid, phosphoric acid or their anhydrides or mixtures thereof.

According to a further advantageous embodiment, a liquid hardener for curing curable polymer resins is therefore also the subject of the present invention, which comprises a) cyanamide, b) at least one urea derivative of the formula (I), (II) and / or (IV), c) at least a viscosity modifier, in particular a viscosity modifier according to formula (V), d) optionally at least one curing accelerator from the class of imidazolines according to formula (IV) or imidazoles according to formula (V), and e) at least one stabilizer selected from the group of organic acids , in particular aromatic and non-aromatic carboxylic acids, dicarboxylic acids or tricarboxylic acids, or inorganic acids, in particular inorganic acids selected from the group of hydrochloric acid, sulfuric acid, sulfurous acid, phosphoric acid, phosphorous acid, ortho-phosphoric acid, diphosphoric acid, triphosphoric acid, polyphosphoric acid, nitric acid or their anhydrides , ins wherein the liquid hardener comprises in particular cyanamide and at least one urea derivative of the formula (I) in a molar ratio of cyanamide: urea derivative or urea derivative mixture of 1: 1 to 4: 1.

In the presence of at least one stabilizer, the molar ratios of cyanamide: urea derivative may also be outside the preferred range of 1: 1 to 4: 1. For example, molar ratios of cyanamide: urea derivative of 0.1 to <1: 1, in particular from 0.2 to <1: 1, possible, but also molar ratios of cyanamide: urea derivative of> 4: 1 to 20: 1, in particular > 4: 1 to 10: 1.

Particular preference is given to those acids, in particular inorganic acids, which have a water content of less than 20% by weight (based on the acid). Very particular preference is given to those acids, in particular inorganic acids, which have a water content of less than 15% by weight, more preferably less than 10% by weight and very particularly less than 5% by weight (in each case based on the acid) , Thus, liquid hardeners can be provided, which in turn are liquid and solvent-free in the sense of the present invention.

According to a particularly preferred embodiment of the present invention contains a liquid hardener a) 1 to 50 parts by weight Cyanamid, b) 1 to 50 parts by weight at least one urea derivative of the formula (I), (II) and / or (IV), c) 0.01 to 50 parts by weight at least one viscosity modifier, d) 0 to 10 parts by weight at least one curing accelerator from the class of imidazolines of the formula (VI) and / or imidazoles of the formula (VII) and e) 0 to 10 parts by weight at least one stabilizer.

In a further development of the present invention are also epoxy resin compositions comprising a) at least one curable epoxy resin and b) at least one liquid curing agent according to the type described above, and polyurethane resin compositions comprising a) at least one curable polyurethane resin and b) at least one liquid curing agent according to the described above, object of the present invention.

With respect to the epoxy resins to be cured, the present invention is not limited. There are all commercially available products in question, which usually have more than one 1,2-epoxide group (oxirane) and thereby may be saturated or unsaturated, aliphatic, cycloaliphatic, aromatic or heterocyclic. In addition, the epoxy resins may have substituents such as halogens, phosphorus and hydroxyl groups.

2,2-bis (4-hydroxyphenyl) -propane (bisphenol A) -based epoxy resins and the bromine-substituted derivative (tetrabromobisphenol A), glycidyl polyethers of 2,2-bis (4-hydroxyphenyl) methane (bisphenol F) and Glycidyl polyethers of novolaks and based on aniline or substituted anilines such For example, p-aminophenol or 4,4'-diaminodiphenylmethanes can be cured particularly well by using the hardener according to the invention.

The amount of use of the liquid hardener according to the invention is not subject to any restrictions. However, 0.01 to 15 parts, preferably 0.1 to 15 parts, preferably 0.1 to 10 parts and most preferably 1 to 10 parts are preferably used per 100 parts of resin, curable epoxy resin or curable polyurethane resin. A combination of several liquid hardeners according to the invention or a combination of liquid hardeners according to the invention with further co-hardeners is also covered by this invention.

The curing of the epoxy resins using the hardener used according to the invention is usually carried out at temperatures above 80 ° C. The choice of the curing temperature depends on the specific processing and product requirements and can be varied via the formulation, in particular by regulating the amounts of hardener and by adding further additives. It is irrelevant in which way the resin formulations energy is supplied. For example, this can be done in the form of heat through an oven or heating elements, but also by means of infrared radiators or excitation by microwaves or other radiation.

By adding further commercially available additives, as are known to the person skilled in the art for curing epoxy resins, the curing profile of the formulations according to the invention can be varied.

Additives for improving the processability of the uncured epoxy resin compositions or of the uncured polyurethane compositions or additives for adapting the thermo-mechanical properties of the thermoset products produced therefrom to the requirement profile include, for example, reactive diluents, fillers, rheology additives, such as thixotropic agents or dispersing additives, defoamer, dyes, Pigments, tougheners, impact modifiers or fire retardant additives.

Epoxy resin formulations containing the hardeners according to the invention are suitable both for manual and mechanical processing methods and, in particular, for the production of impregnated reinforcing fibers and composites, as described, inter alia, in the specifications of GW Ehrenstein, Faserverbund-Kunststoffe, 2006, 2nd edition, Carl Hanser Verlag, Munich, chapter 5, page 148ff , and M. Regne, Composite Solutions, 2006, JEC Publications, Chapter 5, page 51ff , are described. In addition to the use in prepreg process, in particular the handling in infusion and injection methods is a preferred form of processing. In this case, the generally very good miscibilities of the liquid hardeners according to the invention in the epoxy resins are advantageous, since flowable infusion resins with low viscosity are required for the impregnation process (cf., inter alia M. Regne, Composite Solutions, 2006, JEC Publications, Chapter 5, page 65 ; and GW Ehrenstein, Faserverbund-Kunststoffe, 2006, 2nd edition, Carl Hanser Verlag, Munich, chapter 5, page 166 ).

Thus, a composite material comprising a) a carrier material, in particular a fiber material, b) at least one curable epoxy resin and / or curable polyurethane resin and c) at least one liquid hardener of the type described above, the subject of the invention.

Thus, the use of liquid hardeners of the type described above for curing curable compositions are also subject matter of the present invention. In particular, this use is directed to compositions comprising at least one curable epoxy resin and / or a curable polyurethane resin.

Furthermore, the present invention also encompasses the use of liquid hardeners of the type described above for curing impregnated fiber materials or impregnated fabrics, knits or braids.

Due to the favorable application properties of the liquid hardener according to the invention and its low dosage, an advantageous cost-benefit ratio is achieved, with which these hardeners are particularly well suited for industrial application.

Examples

1) Raw materials used:

Cyanamid:

AlzChem AG

Harnstoff B1:

1,1-Dimethylharnstoff – (AlzChem AG)

Harnstoff B2:

1,1'-(4-Methyl-m-phenylen)-bis-(3,3-dimethylharnstoff) – (AlzChem AG)

Harnstoff B4:

N'-[3-[[[(dimethylamino)carbonyl]amino]methyl]-3,5,5-trimethylcyclohexyl]-N,N-dimethyl-Harnstofff – (AlzChem AG)

E 828 LVEL:

Epoxidharz Epikote 828 LVEL – (Fa. Momentive)

RIMR 135:

Epoxidharz – (Fa. Momentive Specialty Chemicals)

RIMR 137:

flüssiger Aminhärter – (Fa. Momentive Specialty Chemicals)

Vestamin IPDA:

flüssiger Aminhärter – (Fa. Evonik Degussa GmbH)

Modifikator M1:

1-Hexanol (Sdp 157°C) – (Fa. Merck)

Modifikator M2:

Ethylenglycol (Sdp 197°C) – (Fa. Merck)

Modifikator M3:

Hexantriol (Sdp 178°C) – (Fa. Evonik Degussa GmbH)

Modifikator M4:

3-Pentanon (Sdp 102°C) – (Fa. Baker)

Modifikator M5:

Octanal (Sdp 171°C) – (Fa. Merck)

Modifikator M6:

Benzonitril (Sdp 191°C) – (AlzChem AG, Trostberg)

Modifikator M7:

Acetessigsäureethylester (Sdp 180°C) – (Fa. Fluka)

Modifikator M8:

Methylglycol (Sdp 124°C) – (Fa. Roth)

Modifikator M9:

2-Aminoethanol (Sdp 172°C) – (Fa. Roth)

Modifikator M10:

Essigsäureanhydrid (Sdp 139°C) – (Fa. Merck)

Beschleuniger I1:

2-Methyl-1H-imidazol – (AlzChem AG)

Beschleuniger I2:

1-Methylimidazol – (Fa. Roth)

Beschleuniger I3:

2-Phenyl-1H-imidazol – (AlzChem AG)

Beschleuniger I4:

2-Phenyl-1H-imidazolin – (AlzChem AG)

Beschleuniger I5:

4,5-Dihydro-2-nonyl-1H-Imidazol – (AlzChem AG)

Beschleuniger I6:

2-Nonyl-1H-Imidazol – (AlzChem AG)

Tabelle 3: Zusammensetzung erfindungsgemäße flüssige Härter mit Viskositätsmodifikatoren und Härtungsbeschleuniger – Molverhältnisse/[mol:mol] Ausgangsgemisch gemäß Tabelle 1 Ausgangsgemisch M3 Flüssige Härter H6I1 1 0,276 H6I1M3 H6I2 1 0,276 H6I2M3 H6I3 1 0,276 H6I3M3 H6I4 1 0,276 H6I4M3 H6I5 1 0,276 H6I5M3 H6I6 1 0,276 H6I6M3 H7I1 1 0,276 H7I1M3

Cyanamid:

AlzChem AG

Urea B1:

1,1-dimethylurea - (AlzChem AG)

Urea B2:

1,1 '- (4-methyl-m-phenylene) bis- (3,3-dimethylurea) - (AlzChem AG)

Urea B4:

N '- [3 - [[[(dimethylamino) carbonyl] amino] methyl] -3,5,5-trimethylcyclohexyl] -N, N-dimethyl-urea (AlzChem AG)

E 828 LVEL:

Epoxy Epikote 828 LVEL - (Momentive)

RIMR 135:

Epoxy resin (from Momentive Specialty Chemicals)

RIMR 137:

liquid amine hardener - (from Momentive Specialty Chemicals)

Vestamin IPDA:

liquid amine hardener - (Evonik Degussa GmbH)

Modifier M1:

1-hexanol (bp 157 ° C) - (Merck)

Modifier M2:

Ethylene glycol (bp 197 ° C) - (Merck)

Modifier M3:

Hexane triol (bp 178 ° C) - (from Evonik Degussa GmbH)

Modifier M4:

3-pentanone (bp 102 ° C) - (Baker)

Modifier M5:

Octanal (bp 171 ° C) - (Merck)

Modifier M6:

Benzonitrile (bp 191 ° C) - (AlzChem AG, Trostberg)

Modifier M7:

Acetoacetic acid ethyl ester (bp 180 ° C) - (from Fluka)

Modifier M8:

Methyl glycol (bp 124 ° C) - (Roth)

Modifier M9:

2-aminoethanol (bp 172 ° C) - (Roth)

Modifier M10:

Acetic anhydride (bp 139 ° C) - (Merck)

Accelerator I1:

2-Methyl-1H-imidazole - (AlzChem AG)

Accelerator I2:

1-methylimidazole - (Roth)

Accelerator I3:

2-phenyl-1H-imidazole - (AlzChem AG)

Accelerator I4:

2-phenyl-1H-imidazoline - (AlzChem AG)

Accelerator I5:

4,5-dihydro-2-nonyl-1H-imidazole - (AlzChem AG)

Accelerator I6:

2-nonyl-1H-imidazole - (AlzChem AG)

Table 3: Composition of liquid hardeners according to the invention with viscosity modifiers and curing accelerator - molar ratios / [mol: mol] Starting mixture according to Table 1 starting mixture M3 Liquid hardener H6I1 1 0.276 H6I1M3 H6I2 1 0.276 H6I2M3 H6I3 1 0.276 H6I3M3 H6I4 1 0.276 H6I4M3 H6I5 1 0.276 H6I5M3 H6I6 1 0.276 H6I6M3 H7I1 1 0.276 H7I1M3

2) Preparation of liquid hardener

a) with viscosity modifiers and hardener accelerators

• Apparatus: 500 ml double wall reaction vessel, thermostat, KPG stirrer, 3-blade metal stirrer, thermometer, powder funnel,
• Procedure: Cyanamide, the various ureas (B1, B2, B4), the viscosity modifier (M3) and the hardener accelerators (I1-I6) are first added to the reaction vessel via the powder funnel. Then the double wall reaction vessel is charged with 40 to 42 ° C warm water and the 3-blade metal stirrer (200 rpm) is turned on. Depending on the viscosity modifier, a liquid hardener is now produced at an internal temperature of 35 to 40 ° C in 20 to 40 minutes. Subsequently, the liquid hardener is cooled to 20 to 25 ° C, transferred to glass containers and stored at 23 ° C.

b) with viscosity modifiers

• Apparatus: 500 ml double wall reaction vessel, thermostat, KPG stirrer, 3-blade metal stirrer, thermometer, powder funnel,
• Procedure: Cyanamide, the various ureas (B1, B2, B4) and the viscosity modifier (M1-M10) are added to the reaction vessel via the powder funnel. Then the double wall reaction vessel is charged with 40 to 42 ° C warm water and the 3-blade metal stirrer (200 rpm) is turned on. Depending on the viscosity modifier, a liquid hardener is now produced at an internal temperature of 35 to 40 ° C in 20 to 40 minutes. Subsequently, the liquid hardener is cooled to 20 to 25 ° C, transferred to glass containers and stored at 23 ° C.

3) Use Tests - Results: Properties of epoxy resin compositions according to the invention

a) Composition of inventive epoxy resin compositions

For the use tests epoxy resin composition with liquid hardener according to the invention were used at the same mixing ratios (each 100 parts by weight of epoxy resin, 10 parts by weight of liquid hardener).

b) Preparation of Epoxy Resin Compositions According to the Invention

100 parts by weight of epoxy resin (Epikote 828 LVEL) and 10 parts by weight of the hardener according to the invention are weighed into a 250 ml dispersing vessel according to Tables 1-3 and mixed on a dissolver at 500 rpm for 2 minutes. The mixture is then deaerated in vacuo for 10 minutes.

c) Measurement methods for determining the properties

• • Dyn-DSC: Measurement on Mettler Toledo DSC 822 Standard 30-250 ° C, with a heating rate of 10 K / min
• • Glass point: Heat measurement on Mettler Toledo DSC 822 Tg 3 × heating from 30 ° C to 200 ° C at 20 K / min held for 10.0 min at 200 ° C cool from 200 ° C to 50 ° C at 20 K / min maintained at 50 ° C for 5.0 min heating of 50 ° C kept at 200 ° C at 20 K / min maintained at 200 ° C for 10 min. Cool from 200 ° C to 50 ° C at 20 K / min maintained at 50 ° C for 5.0 min. Heating from 50 ° C to 220 ° C C at 20 K / min
• • Viscosity: Measurement on HAAKE Rheostress 1 carried out at 25 ° C in Pa · s, with rotary body cone 1 ° C35 / 1 Ti ⌀ 35 mm with a shear rate of 5.0 1 / s (reciprocal second)
• • Gel time: Measurement on metal block thermostat VLM 2.0 / -HAT in aluminum plug-in caps (⌀ 15 mm × 25 mm height) at 140 ° C
• • Latency: Shelf life of the epoxy resin compositions in days (d) after storage at 23 ° C in the climatic chamber. Definition of Latency: Is the time in days (d) after which the viscosity of the epoxy resin composition has doubled. At this time, the end of shelf life is reached. Table 4: Epoxy resin compositions liquid hardeners, as well as their properties
  
  *: not according to the invention **: Not used according to the invention, used epoxy resin E828 - (from Momentiv Specialty Chemicals), 100 parts epoxy resin: 23 parts Vestamin IPDA - (from Evonik Degussa GmbH) ***: epoxy resin RIMR 135 not used according to the invention (from Momentive Specialty Chemicals), 100 parts of epoxy resin: 30 parts of RIMR 137 (from Momentiv Specialty Chemicals)

The results of the reactions of the various viscosity-modified liquid hardeners with epoxy resin shown in Table 4 clearly show that the viscosity modifiers exert little influence on the glass transition temperature (Tg) of the resulting polymer. Their influence, however, on the viscosities, as intended, the latencies and the gel times is considerable. Here, the various classes of viscosity modifiers can exert different influences on the viscosity-modified liquid hardener according to the invention.

While monohydric alcohols, dihydric alcohols, ketones, nitriles and ethers have a viscosity-reducing effect on hardeners H5 and H6, trihydric alcohols increase their viscosity. Aldehydes have a viscosity-neutral effect. In the case of the hardeners H6, esters and anhydrides also have a viscosity-reducing effect, while amino alcohols increase the viscosities. The hardeners H5 react spontaneously with the viscosity modifiers from the series of esters, anhydrides and amino alcohols, therefore viscosities, gel times and latencies can not be measured.

Both the storage stabilities (latencies) of the various epoxy resin / hardener mixtures and their reactivity, the different viscosity modifiers have an exceptionally strong influence. For the H5 hardeners, monohydric alcohols, dihydric alcohols, aldehydes, and nitriles reduce latencies by half, while trihydric alcohols, ketones, and ethers more than triple latencies. The latencies of the epoxy resin / H6 mixtures behave unevenly, here also divalent alcohols and nitriles trip the storage stabilities.

The gel times provide information about the reactivity of the epoxy resin / hardener mixtures. It is striking that viscosity modifiers can reduce the gel time and others can increase this. Monohydric and dihydric alcohols usually accelerate the reaction, while trihydric alcohols, ketones and ethers slow them down. Aldehydes and nitriles accelerate reactions of the H5 hardeners while slowing down the reactions of the H6 hardeners. In H6, esters and anhydrides also have a slowing effect, while amino alcohols naturally accelerate without, however, reacting spontaneously.

If the viscosity-modified liquid hardeners are modified in their composition with imidazoles, it is true that further reductions in the gel times and thus an increase in reactivity can be observed, but this is accompanied by considerable increases in the viscosities and storage stabilities (latencies).

In comparison, the known and commonly used liquid amine hardeners such. B. RIMH 137 (from Momentiv Specialty Chemicals) or IPDA (Evonik Degussa GmbH), although lower curing temperatures, the mixtures of the invention start the polymerization but at comparable times and achieve far higher glass transition temperatures, but have a much greater latency.

Through the use of viscosity modifiers and imidazoles in the viscosity-modified liquid hardeners according to the invention, a bundle of special property profiles of these liquid hardeners is produced, as required in many applications in the composite sector. Due to this wide range of properties, the viscosity-modified liquid hardener according to the invention can be adapted to almost all requirements individually. Table 5: Infusion experiment with epoxy resin compositions according to Table 4 The epoxy resin composition Injection time in minutes Hardening time in h Temperature in ° C Cold-Tg End-Tg Remarks E2 4 4 h 78 ° -80 ° C 116 118 Fiber composite can be gut core fiber composite looks good, is uniform, has no defects E20 4 6 h 88 ° -90 ° C 120 126 Fiber composite can be gut core fiber composite looks good, is uniform, has no defects E30 4 2 h 78 ° -80 ° C 118 121 Fiber composite can be gut core fiber composite looks good, is uniform, has no defects Table 6: Fiber composite - setup for infusion experiments component material base layer R & G vacuum foil no. 390160 seal Tacky Tape SM5126-1 / 2 '' x X1 / 8 '' Separation film (below) Nylon Peel ply (plain weave 64 g / m ³ ) offset Laminate (glass fiber) 5 layers of Atlas FK 144 (296 g / m ³ ) Separation film (above) Nylon Peel ply (plain weave 64 g / m ³ ) offset release film R & G release film no. 390190 ventilation film R & G fleece no. 390180 Vacuum mesh Venting network 150 g / m ³ (direction - black) vacuum film R & G vacuum foil no. 390160 Hoses (supply and discharge) Teflon, (4.0 mm inside ⌀, 5.0 mm outside ⌀) PVC, clear (6.0 mm inside ⌀, 7.0 mm outside ⌀) carrier glass plate Shape: heating plate Storage jar: beaker Vacuum: Vacuum pump standard (15-20 mbar)

Experimental procedure:

Epoxy resin compositions E2, E20 are mixed in a heatable storage vessel and preheated. The supply hose is inserted into the storage vessel and fixed, the discharge hose (see Structure of an infusion test, Table 5) is connected via a safety valve to the vacuum pump, the pump is turned on. The heating plate (it simulates the heatable shape) is brought to the infusion temperature. With the application of the vacuum, the epoxy resin composition is sucked through the fiber composite. After complete impregnation inlet and outlet hose are disconnected and capped, the entire structure now hardens on the heating plate to a laminate. After complete curing and cooling, the laminate is removed from the assembly.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 2743015 A1 [0008]
• AT 351772 [0008]
• EP 2012/053092 [0009]
• EP 2012/053091 [0009]

Cited non-patent literature

• GW Ehrenstein, Faserverbund-Kunststoffe, 2006, 2nd Edition, Carl Hanser Verlag, Munich, Chapter 5, page 148ff [0066]
• M. Regne, Composite Solutions, 2006, JEC Publications, Chapter 5, page 51ff. [0066]
• M. Regne, Composite Solutions, 2006, JEC Publications, Chapter 5, page 65 [0066]
• GW Ehrenstein, Faserverbund-Kunststoffe, 2006, 2nd Edition, Carl Hanser Verlag, Munich, Chapter 5, page 166 [0066]

Claims (15)

A liquid hardener for curing curable polymer resins, in particular epoxy resins, comprising a) cyanamide; b) at least one urea derivative of the formula (I)

where the radicals are the same or independent of one another and at least one radical R ¹ , R ² , R ^{3 is} not hydrogen: R ¹ , R ² = simultaneously or independently of one another hydrogen, C 1 - to C 15 -alkyl, C 3 - to C 15 -cycloalkyl or together to form a ring C3 to C10 alkylene; R ³ = hydrogen, C 1 to C 15 alkyl, C ³ to C 15 cycloalkyl, aryl, arylalkyl, with -NHC (O) NR ¹ R ² substituted C 1 to C 15 alkyl, with -NHC (O) NR ¹ R ² represents C3 to C15-cycloalkyl, with -NHC (O) NR ¹ R ² is substituted aryl or -NHC (O) NR ¹ R ² is substituted arylalkyl; and c) at least one viscosity modifier selected from the group of mono-, di- and / or polyols, ethers, polyethers, polyether polyols, ketones, aldehydes, nitriles, carboxylic esters or mixtures thereof. Liquid hardener according to claim 1, characterized in that the hardener cyanamide and at least one urea derivative of the formula (I) in a molar ratio of cyanamide: urea derivative or urea derivative mixture of 1: 1 to 4: 1. Liquid curing agent according to claim 1 or 2 characterized in that the radical R ³ = aryl, arylalkyl, with -NHC (O) NR ¹ R ² is substituted aryl or -NHC (O) NR ¹ R ² substituted arylalkyl is a radical of the general Formula (II) stands

where the radicals R ¹ , R ^{2 have} the abovementioned meaning and the following radicals have the same or the same independence: R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ = hydrogen, halogen, C 1 - to C 15 -alkyl, C ₃ to C 15 cycloalkyl, aryl, arylalkyl, -CF ₃ , -NHC (O) NR ¹ R ² , C ^{1 to} C 15 alkyl substituted with -NHC (O) NR ¹ R ² , with -NHC (O) NR ¹ R ^{2 is} substituted aryl or -NHC (O) NR ¹ R ² substituted arylalkyl; R ⁹ , R ¹⁰ = simultaneously or independently of one another are hydrogen or C 1 - to C 5 -alkyl; n = a number between 0 and 10. Liquid hardener according to at least one of the preceding claims, characterized in that the hardener comprises a urea derivative of the formula (I), wherein for the radicals simultaneously or independently of one another: R ¹ , R ² = simultaneously or independently of one another hydrogen or C 1 - to C 15- alkyl; R ³ = hydrogen, C1 to C15 alkyl, C1 C3-C15-cycloalkyl, with -NHC (O) NR ¹ R ² is substituted to C15 alkyl or -NHC (O) NR ¹ R ² is substituted C3- to C15-cycloalkyl. Liquid hardener according to at least one of the preceding claims, characterized in that the hardener is a urea derivative according to formula (I) selected from the group 1-methylurea, 1,1-dimethylurea, 1,3-dimethylurea, 3- (3-chloro-4- methylphenyl) -1,1-dimethylurea, 3- (p-chlorophenyl) -1,1-dimethylurea, 3-phenyl-1,1-dimethylurea, 3- (3,4-dichlorophenyl) -1,1-dimethylurea, 1 , 1 '- (Methylenedi-p-phenylene) bis (3,3-dimethylurea), 3- (3-trifluoromethylphenyl) -1,1-dimethylurea, 1,1' - (2-methyl-m-phenylene) -bis (3,3-dimethylurea) and / or 1,1 '- (4-methyl-m-phenylene) bis- (3,3-dimethylurea). Liquid hardener according to at least one of the preceding claims, characterized in that the hardener comprises a viscosity modifier, which in turn has a boiling point of at least 100 ° C. Liquid hardener according to at least one of the preceding claims, characterized in that the hardener comprises at least one viscosity modifier selected from the group of mono-, di- and / or polyols, ethers, ether alcohols, polyethers or polyether polyols or mixtures thereof according to general formula (V),

where the radicals are the same or independent of one another: R ¹¹ , R ²² = simultaneously or independently of one another are hydrogen, -OH or C 1 - to C 10 -alkyl; R ¹² , R ¹⁴ , R ¹⁶ , R ¹⁸ , R ²⁰ = simultaneously or independently of one another hydrogen, -OH or C 1 - to C 5 -alkyl; R ¹³ , R ¹⁶ , R ¹⁷ , R ¹⁹ , R ²¹ = simultaneously or independently of one another are hydrogen, -OH, -NH ₂ or C 1 - to C 5 -alkyl; with n, o, s, q, t = simultaneously or independently of one another a number from 0 to 10, and iii) m, s, u = simultaneously or independently of one another a number from 1 to 10, and / or iv) p, t , u = simultaneously or independently of one another a number from 1 to 10. Liquid hardener according to at least one of the preceding claims, characterized in that the hardener further comprises d) at least one curing accelerator from the class of imidazolines according to formula (VI) or imidazoles according to formula (VII)

where the radicals are the same or independent of one another: R ³⁰ = simultaneously or independently of one another hydrogen, C 1 - to C 20 -alkyl, C 3 - to C 20 -cycloalkyl, aryl, arylalkyl; R ³² , R ³⁴ = simultaneously or independently of one another are hydrogen, C 1 - to C 15 -alkyl, C 3 - to C 15 -cycloalkyl or together to form a ring C 3 - to C 15 -alkylene; R ³³ , R ³⁵ = simultaneously or independently of one another hydrogen, C 1 - to C 15 -alkyl, C 3 - to C 15 -cycloalkyl or together to form a ring C 3 - to C 15 -alkylene. Liquid hardener according to at least one of the preceding claims, characterized in that the hardener further comprises e) a stabilizer selected from the group of inorganic or organic acids. Liquid hardener according to at least one of the preceding claims, characterized in that the stabilizer comprises an inorganic or organic acid from the group of salicylic acid, phthalic acid, toluenesulfonic acid, sulfuric acid, phosphoric acid or their anhydrides or mixtures thereof. Liquid hardener according to at least one of the preceding claims, characterized in that the hardener contains: 1 to 50 parts by weight of cyanamide, 1 to 50 parts by weight of at least one urea derivative of the formula (I), 0.01 to 50 parts by weight of at least one viscosity modifier 0 to 10 parts by weight of at least one Hardening accelerator from the class of imidazolines of the formula (VI) and / or the imidazoles of the formula (VII) and 0 to 10 parts by weight of at least one stabilizer. Epoxy resin composition comprising a) at least one curable epoxy resin and b) at least one liquid hardener according to at least one of the preceding claims 1 to 11. Polyurethane resin composition comprising a) at least one curable polyurethane resin and b) at least one liquid hardener according to at least one of the preceding claims 1 to 11. Comprising composite material a) a carrier material, in particular a fiber material, b) at least one curable epoxy resin and / or curable polyurethane resin and c) at least one liquid hardener according to at least one of the preceding claims 1 to 11. Use of liquid hardeners according to at least one of the preceding claims 1 to 11 for the hardening of impregnated fiber materials or impregnated fabrics, knitted fabrics or braids.