WO2013041398A1 - Curing of epoxy resin compositions comprising cyclic carbonates using mixtures of amino hardeners - Google Patents

Abstract

A process for curing epoxy resins which comprises curing epoxy resin compositions comprising a) epoxy resins and b) a compound of the general formula I in which R¹ and R² independently of one another are hydrogen, C₁-C₆-alkyl, C₁-C₄-alkoxy-C₁-C₄-alkyl, C₅-C₆-cycloalkyl, phenyl, phenyl-C₁-C₄-alkyl, C₂-C₆-alkenyl or C₂-C₆-alkynyl, or R¹ and R² together are a C₃-C₁₁-alkylene group; R³ and R⁴ independently of one another are hydrogen, C₁-C₆-alkyl, C₁-C₄-alkoxy-C₁-C₄-alkyl, C₅-C₆-cycloalkyl, phenyl, phenyl-C₁-C₄-alkyl, C₂-C₆-alkenyl or C₂-C₆-alkynyl, or R³ and R⁴ together are a C₄-C₆-alkylene group; by adding amino hardeners, 0.1% to 50% by weight of the amino hardeners being aliphatic, cycloaliphatic or aromatic amine compounds having 1 to 4 primary amino groups and optionally further functional groups, selected from secondary amino groups, tertiary amino groups, and hydroxyl groups, the primary amino groups in the case of the cycloaliphatic and aromatic amine compounds being attached as aminomethylene groups (H₂N-CH₂-) to the cycloaliphatic or aromatic ring system (referred to below for short as co-hardeners).

Description

 Curing of epoxy resin compositions containing cyclic carbonates with mixtures of amino hardeners

description

The present application incorporates by reference the US Provisional Application 61/536079 filed on Sep. 19, 2011.

The present invention relates to a process for curing epoxy resin compositions with amine hardeners, which is characterized in that epoxy resin compositions containing a) epoxy resins and

b) a compound of general formula I.

wherein

R ¹ and R ² independently of one another are hydrogen, C 1 -C 6 -alkyl, C 1 -C 4 -alkoxy-C 1 -C 4 -alkyl, C 5 -C 6 -cycloalkyl, phenyl, phenyl-C 1 -C 4 -alkyl, C 2 -C 6 -alkenyl or C2-C6-alkynyl, or R ¹ and R ² together represent a C3-Cn-alkylene group;

R ³ and R ⁴ independently of one another are hydrogen, C 1 -C 6 -alkyl, C 1 -C 4 -alkoxy-C 1 -C 4 -alkyl, C 5 -C 6 -cycloalkyl, phenyl, phenyl-C 1 -C 4 -alkyl, C 2 -C 6 -alkenyl or C2-C6-alkynyl, or R ³ and R ⁴ together represent a C4-C6-alkylene group; are hardened by adding amino hardeners and 0.1 to 50% by weight of the amino hardeners are aliphatic, cycloaliphatic or aromatic amine compounds having 1 to 4 primary amino groups and optionally further functional groups selected from secondary amino groups, tertiary amino groups and hydroxyl groups, wherein the primary amino groups in the case of the cycloaliphatic and aromatic amine compounds are bonded as aminomethylene groups (H 2 N-CH 2 -) to the cycloaliphatic or aromatic ring system (hereinafter referred to briefly as co-hardener). Epoxy resins (also called epoxy resins) are usually called oligomeric compounds having on average more than one epoxide group per molecule. These can be converted into thermosets by reaction with suitable hardeners or by polymerization of the epoxide groups. Cured epoxy resins, due to their excellent mechanical and chemical properties, such as high impact strength, high abrasion resistance, good chemical lienbeständigkeit, in particular a high resistance to alkalis, acids, oils and organic solvents, high weather resistance, excellent adhesion to many materials and high electrical insulation capacity, widely used. By reaction with hardeners, the epoxy prepolymers are converted into non-fusible, three-dimensionally "crosslinked", thermosetting materials. Suitable hardeners are compounds having at least two functional groups which can react with the epoxide groups (also called oxirane groups) and / or hydroxyl groups of the epoxy resin prepolymers to form covalent bonds, for example compounds having amino groups, hydroxyl groups and carboxyl groups or derivatives thereof , like anhydrides. Accordingly, aliphatic and aromatic polyamines, carboxylic anhydrides, polyamidoamines, aminoplasts or phenoplasts are usually used as hardeners for epoxy resins.

The prepolymers used for the preparation of cured epoxy resins usually have a high viscosity, which makes the application difficult. In addition, the high viscosity of the resins often limits the use of fillers which are desirable for modifying the mechanical properties of the cured resin composition. In addition, in many cases, the use of fillers allows to reduce the cost of the products made from the resins, such as moldings or coatings. Therefore, diluents are often added to the uncured epoxy resin which reduce the viscosity of the resin to the value desired for use. Suitable diluents are in particular reactive diluents. Reactive diluents are solvents which have functional groups which react with the epoxide groups of the resin and / or the functional groups of the hardener to form covalent bonds, e.g. Compounds, which in turn contain oxirane groups. Reactive diluents are, in particular, glycidyl ethers of polyfunctional aliphatic alcohols such as 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, diethylene glycol diglycidyl ether or glycidyl ether of trimethylolpropane.

A particularly suitable reactive diluent for epoxy resins is the abovementioned compound of general formula I. Compositions containing epoxy resins and compounds of formula I are the subject of unpublished patent application PCT / EP201 1/059767.

In the compositions described in PCT / EP201 1/059767 the viscosity is reduced by adding the compounds of the formula I. The performance properties, e.g. the cure rate of the described compositions are good.

Basically, there is the object of further improving the performance characteristics of the cured epoxy resin compositions. In particular, even faster curing rates are often desirable. Object of the present invention were therefore epoxy resin compositions or a method for curing epoxy resin compositions, which further improve the cure rate. Accordingly, the method defined above was found. Also found were epoxy resin compositions which contain compounds of the formula I and special hardener mixtures.

In the method according to the invention epoxy resin compositions are cured, which a) epoxy resins and

b) contain a compound of the above general formula I.

Such epoxy resin compositions are already in the patent application

PCT / EP201 1/059767 of BASF (BASF patent PF 70167) described. PCT / EP201 1/059767 also discloses particular embodiments of compounds of formula I, the epoxy resins and uses of the epoxy resin formulations containing compounds of formula I. Reference is made to the entire disclosure content of PCT / EP201 1/059767 and the entire disclosure content of PCT / EP201 1/059767 is here considered to be inserted.

To the epoxy resins

Suitable epoxy resins are, in particular, those which are customarily used in curable epoxy resin compositions. Particular mention may be made of compounds having from 1 to 10 epoxide groups, preferably having at least two epoxide groups in the molecule. The content of epoxide groups in typical epoxy resins is in the range from 120 to 3000 g / equivalent, calculated as so-called epoxide equivalent according to DIN 16945.

Preferred among these are so-called glycidyl-based epoxy resins, in particular those which are prepared by etherification of aromatic, aliphatic or cycloaliphatic polyols with epichlorohydrin. Such substances are often referred to as polyglycidyl ethers of aromatic, or polyglycidyl ethers of aliphatic or cycloaliphatic polyols.

The epoxy resins may be liquid resins, solid resins or mixtures thereof. Liquid resins differ from solid resins in their lower viscosity. In addition, liquid resins generally have a higher proportion of epoxide groups and, accordingly, a lower epoxide equivalent. The content of epoxide groups in typical liquid resins is usually in the range of 120 to 200 g / equivalent and that of the solid resins in the range of 450-3000 g / equivalent, calculated as so-called epoxide equivalent according to DIN 16945. The viscosity of the liquid resins is usually 25 ° C. in the range of 1 to 20 Pas, preferably in the range of 5 to 15 Pas. The viscosity of the solid resins is usually in the range 5 to 40 Pas, preferably in the range of 20 to 40 Pas at 25 ° C. The viscosities stated here are the values determined in accordance with DIN 53015 at 25 ° C. as 40% strength solutions of the resins in methyl ethyl ketone.

Suitable epoxy resins are, for example, commercially available under the trade names EPILOX®, EPONEX®, EPIKOTE®, EPONOL®, D.E.R, ARALDIT® or ARACAST®.

In a preferred embodiment, the epoxy resin is selected from polyglycidyl ethers of aromatic polyols. Examples of these are the resins derived from the diglycidyl ether of bisphenol A (DGEBA resins, R '= CH 3) and the resins derived from bisphenol F (R' = H), which can be described by the following general formula:

 O

R = CH ₂ -> R '= H or CH ₃

In the formula, the parameter n indicates the number of repeating units, the mean value of n corresponding to the respective average molecular weight.

Examples of epoxy resins based on polyglycidyl ethers of aromatic polyols are also glycidyl ethers of phenol- and cresol-based novolacs. Novolacs are produced by the acid-catalyzed condensation of formaldehyde and phenol or cresol. Reaction of the novolaks with epichlorohydrin gives the glycidyl ethers of novolacs.

In another preferred embodiment of the invention, the epoxy resin is selected from polyglycidyl ethers of cycloaliphatic polyols and the polyglycidyl esters of cycloaliphatic polycarboxylic acids. Examples of polyglycidyl ethers of cycloaliphatic polyols are the core hydrogenation products of bisphenol A-based polyglycidyl ethers, the core hydrogenation products of bisphenol-F-based polyglycidyl ethers, the core hydrogenation products of novolac-based polyglycidyl ethers, and mixtures thereof. Such compounds are usually prepared by selective hydrogenation of the aromatic rings in the aforementioned aromatic polyglycidyl ethers. Examples of such products are the P 22-00 from the company LeunaHarze and Eponex 1510 from Hexion. Examples of polyglycidyl esters of cycloaliphatic polycarboxylic acids are hexahydrophthalic acid diglycidyl esters Epoxy resins for paint formulations are also polyacrylate resins containing epoxide groups. These are generally prepared by copolymerization of at least one ethylenically unsaturated monomer which contains at least one epoxide group, in particular in the form of a glycidyl ether group, in the molecule with at least one further ethylenically unsaturated monomer which contains no epoxide group in the molecule, preferably at least one of the comonomers is an ester of acrylic acid or methacrylic acid. Examples of the ethylenically unsaturated monomers containing at least one epoxide group in the molecule are glycidyl acrylate, glycidyl methacrylate and allyl glycidyl ether. Examples of ethylenically unsaturated monomers which contain no epoxide group in the molecule are alkyl esters of acrylic and methacrylic acid which contain 1 to 20 carbon atoms in the alkyl radical, in particular methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, butyl methacrylate, 2-ethyl hexyl acrylate and 2-ethylhexyl methacrylate. Other examples of ethylenically unsaturated monomers that do not contain epoxide groups in the molecule are acids, such as acrylic acid and methacrylic acid. Acid amides such as acrylic and methacrylamide, vinyl aromatic compounds such as styrene, methylstyrene and vinyltoluene, nitriles such as acrylonitrile and methacrylonitrile, vinyl and vinylidene halides such as vinyl chloride and vinylidene fluoride, vinyl esters such as vinyl acetate and hydroxyl-containing monomers such as hydroxyethyl and hydroxyethyl methacrylate. The epoxide group-containing polyacrylate resin usually has an epoxide equivalent weight of from 400 to 2500, preferably from 500 to 1500, particularly preferably from 600 to 1200. The number average molecular weight (determined by gel permeation chromatography using a polystyrene standard) is typically in the range from 1000 to 15,000, preferably from 1200 to 7000, more preferably from 1500 to 5000. The glass transition temperature (TG) is typically in the range from 30 to 80 ° C, preferably from 40 to 70 ° C, more preferably from 50 to 70 ° C (measured by differential scanning calorimetry (DSC)). Epoxide group-containing polyacrylate resins are known (cf., for example, EP-A-299 420,

DE-B-22 14 650, DE-B-27 49 576, US-A-4,091,048 and US-A-3,781,379). Examples of such resins are Epon 8021, Epon 81 1 1, Epon 8161 from Hexion. The epoxy resins can also be derived from other epoxides (non-glycidyl ether

Epoxy resins). These include, in particular, compounds, including oligomers and polymers, which have at least one, in particular a plurality of epoxidized cycloaliphatic groups, in particular 7-oxabicyclo [4.1.0] heptyl groups, which are obtainable by epoxidation of compounds having cyclohexenyl groups. Examples of the epoxidation products of compounds having at least one cycloolefinic group are 4-epoxyethyl-1,2-epoxycyclohexane and the compound of the following formula:

(CAS number 2386- which is marketed, for example, by the company Cytec under the name Uvacure 1500. Preference is given to using the compounds which have at least one, in particular a plurality of epoxidized cycloaliphatic groups, in particular 7-oxabicyclo [4.1.0] heptyl groups, which are obtainable by epoxidation of compounds having cyclohexenyl groups, and their oligomers not alone but instead in combination with one or more of the aforementioned substances which have at least two glycidyl ether groups in the molecule.

To compounds of the formula I Preference is given to the compounds of the formula (I) in which the radicals R ¹ , R ² , R ³ and R ^4, independently of one another, have one or more of the following meanings:

R ¹ is selected from hydrogen, C 1 -C 6 -alkyl, in particular C 1 -C 4 -alkyl, particularly preferably methyl, ethyl, n-propyl and isopropyl, in particular methyl and ethyl, C 1 -C 4 -alkoxy-C 1 -C 4 -alkyl , Cs-Ce-cycloalkyl, in particular cyclohexyl, phenyl, phenyl-C 1 -C 4 -alkyl, in particular benzyl, C 2 -C 6 -alkenyl and C 2 -C 6 -alkynyl;

R ² is selected from hydrogen, C ¹ -C 6 -alkyl, in particular C ¹ -C ⁴ -alkyl, particularly preferably methyl, ethyl, n-propyl and isopropyl, especially methyl or ethyl, C 1 -C 4 -alkoxy-C 1 -C 4 -alkyl , Cs-Ce-cycloalkyl, in particular cyclohexyl, phenyl, phenyl-Ci-C4-alkyl, in particular benzyl, C2-C6-alkenyl and C2-C6-alkynyl;

R ¹ and R ² can also together be a C 3 -C 5 -alkylene group, preferably a C 4 -C 6 -alkylene group, such as, for example, 1,4-butanediyl, 1,5-pentanediyl or 1,6-hexanediyl, in particular a linear Cs Alkylene group (1, 5-pentanediyl);

R ³ is selected from hydrogen, C ₁ -C ₆ -alkyl, C ₁ -C ₄ -alkoxy-C ₁ -C ₄ -alkyl, C ₁ -C ₆ -cycloalkyl, phenyl, phenyl-C ₁ -C ₄ -alkyl, C ₂ -C ₆ -alkenyl and C ₂ -C ₆ alkynyl. R ⁴ is selected from hydrogen, d-Ce-alkyl, _{Ci-C4-alkoxy-Ci-C4-alkyl,} Cs-Ce-cycloalkyl, phenyl, phenyl-Ci-C ₄ alkyl, C ₂ -C ₆ - Alkenyl and C ₂ -C ₆ alkynyl.

R ³ and R ⁴ can also together be a C4-C6-alkylene group, such as 1, 4-butanediyl, 1, 5-pentanediyl or 1, 6-hexanediyl.

Preferably, at least one of R ¹ , R ² , R ³ and R ^{4 is} not hydrogen. In particular, one of the radicals R ¹ or R ^{2 is} not hydrogen.

In preferred compounds of the formula I, at least one of the radicals R ³ and R ⁴ is or are hydrogen. Particularly preferably, both radicals R ³ and R ^{4 are} hydrogen.

With regard to the use according to the invention, the compounds of the formula (I) are particularly preferred, in which the radicals R ¹ and R ^{2 have} the following meanings, wherein the Radicals R ³ and R ^{4 have} the meanings given above and preferably one of R ³ or R ^{4 is} hydrogen and in particular both R ³ and R ^{4 are} hydrogen: is selected from hydrogen and C ¹ -C ⁴ -alkyl, in particular hydrogen , Methyl or ethyl; is selected from C 1 -C 4 -alkyl, C 1 -C 4 -alkoxy-C 1 -C 4 -alkyl, C 1 -C 6 -cycloalkyl, phenyl, phenyl-C 1 -C 4 -alkyl, C 2 -C 6 -alkenyl and C 2 -C 6 -alkynyl, in particular under C 1 -C 4 -alkyl and C 1 -C 4 -alkoxy-C 1 -C 4 -alkyl and especially under methyl or ethyl;

In a likewise particularly preferred embodiment of the invention, R ¹ and R ² together are a C 4 -C 6 -alkylene group, such as, for example, 1,4-butanediyl, 1,5-pentanediyl or 1,6-hexanediyl, in particular a linear C 5 -alkylene group ( 1, 5-pentanediyl). In this particularly preferred embodiment, the radicals R ³ and R ^{4 have} the meanings given above, where preferably one of the radicals R ³ or R ^{4 is} hydrogen and in particular both radicals R ³ and R ^{4 are} hydrogen.

In a likewise particularly preferred embodiment of the invention, R ¹ and R ² independently of one another are C ¹ -C ⁴ -alkyl, in particular methyl or ethyl. In this very particularly preferred embodiment, the radicals R ³ and R ^{4 have} the meanings given above, wherein preferably one of the radicals R ³ or R ^{4 is} hydrogen and in particular both radicals R ³ and R ^{4 are} hydrogen. Particular preference is accordingly given to compounds of the general formula Ia

in denen R¹ und R² eine der oben gegebenen Bedeutungen aufweisen und deren Gemische. Besonders bevorzugt sind Verbindungen der allgemeinen Formel la, in denen R¹ und R² die in Tabelle 1 beschriebenen Bedeutungen zeigen. Tabelle 1 : Beispiele erfindungsgemäßer Verbindungen der Formel la

in which R ¹ and R ^{2 have} one of the meanings given above and mixtures thereof. Particular preference is given to compounds of the general formula Ia in which R ¹ and R ² show the meanings described in Table 1. Table 1: Examples of compounds of the formula Ia according to the invention

Of these, particularly preferred are the following compounds and mixtures thereof:

4,4-diethyl-5-methylene-1,3-dioxolan-2-one

 4,4-dimethyl-5-methylene-1,3-dioxolan-2-one

 • 4-methyl-5-methylene-1,3-dioxolan-2-one

 4-ethyl-5-methylene-1,3-dioxolan-2-one

4-ethyl-4-methyl-5-methylene-1,3-dioxolan-2-one

 4-isopropyl-5-methylene-1,3-dioxolan-2-one

 4-isopropyl-4-methyl-5-methylene-1,3-dioxolan-2-one

 • 4-methylene-1,3-dioxa-spiro [4.5] decan-2-one

 4-phenyl-4-methyl-5-methylene-1,3-dioxolan-2-one

4-n-propyl-5-methylene-1,3-dioxolan-2-one

 4-n-propyl-4-methyl-5-methylene-1,3-dioxolan-2-one

• 4-methylene-1,3-dioxolan-2-one Very particular preference is given to compounds of the formula Ia, where R ¹ and R ² independently of one another are C ¹ -C ⁴ -alkyl, in particular methyl or ethyl.

The compounds of the formulas I, which are also referred to below as exo-vinylene carbonates, are known in principle from the prior art, for example from DE 1098953 or DE 3433403.

Compounds of the formula I in which at least one of the two radicals R ³ , R ^{4 is} hydrogen can be prepared, for example, by reacting optionally substituted propargyl alcohols with CO 2 or a carboxylic anhydride in the presence of a catalyst, as in PCT / EP201 1/059767 is described.

Compounds of the formula I in which one or both of the radicals R ³ and R ^{4 is} a radical different from hydrogen can be prepared starting from compounds of the formula I in which both radicals R ³ and R ^{4 are} hydrogen by Heck coupling, For example, in analogy to that in Tetrahedron Lett. 2000, 5527-5531 method described.

In the epoxy resin compositions, the compounds of the formula I bring about a reduction in the viscosity and an increase in the reactivity, the latter in particular in the case of amine curing. In general, the desired dilution effect but also the increased reactivity even at a low content of the compound of formulas I. In general, the compound (s) of the formulas I in a total amount of at least 0.001 parts by weight, often at least 0.005 parts by weight, in particular at least 0.01 parts by weight, based on 1 part by weight of the epoxy resins use. Frequently, the compound (s) of the formula I will be used in a total amount of at most 1 part by weight, preferably at most 0.7 part by weight, especially at most 0.5 part by weight, based on 1 part by weight of the epoxy resin component.

Accordingly, in the epoxy resin compositions, the total amount of compounds of the formulas I is generally from 0.1% by weight to 50% by weight, frequently from 0.5 to 40% by weight and in particular from 1 to 30% by weight. -%, Based on the sum by weight of compounds of formulas I and epoxy resin.

To further components of the epoxy resin composition

In addition to the epoxy resins and the compounds of the formula I, the epoxy resin compositions may also contain conventional reactive diluents. These are, in particular, low molecular weight compounds having a molecular weight of preferably at most 250 daltons, for example in the range from 100 to 250 daltons, which have oxirane groups, preferably glycidyl groups, for example in the form of glycidyl ether groups, glycidyl ester groups or glycidylamide groups. The epoxide functionality, ie the number of epoxide groups per molecule, in the case of the reactive diluents is typically in the range from 1 to 3, in particular in the range from 1.2 to 2.5. Preferred among these are, in particular, glycidyl ethers of aliphatic or cycloaliphatic alcohols, which preferably have 1, 2, 3 or 4 OH groups and 2 to 20 or 4 to 20 C atoms, as well as glycidyl ethers of aliphatic polyetherols which have 4 to 20 C atoms. Examples of these are: glycidyl ethers of saturated alkanols having 2 to 20 C atoms, such as, for example, C 2 -C 20 -alkyl glycidyl ethers, such as 2-ethylhexyl glycidyl ether;

 Glycidyl ethers of saturated alkanepolyols having 2 to 20 carbon atoms, e.g. the glycidyl ethers of 1,4-butanediol, 1,6-hexanediol, trimethylolpropane or pentaerythritol, the abovementioned glycidyl ether compounds generally having an epoxide functionality in the range from 1 to 3.0 and preferably in the range from 1, 2 to 2.5;

 Glycidyl ethers of polyetherols having 4 to 20 C atoms, for example glycidyl ethers of diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol or tripropylene glycol;

 Glycidyl ethers of cycloaliphatic alcohols having 5 to 20 C atoms, such as, for example, bis-glycidyl ethers of cyclohexane-1,4-diyl, the bisglycidyl ethers of ring-hydrogenated bisphenol A or of ring-hydrogenated bisphenol F,

 Glycidyl ethers of polyalkylene oxides having 2 to 4 C atoms, such as polyethylene oxide or polypropylene oxide; and mixtures of the aforementioned substances.

If desired, the conventional reactive diluents are used in the formulations according to the invention in a total amount of at least 0.01 parts by weight, frequently at least 0.02 parts by weight, in particular at least 0.05 parts by weight, based on 1 part by weight of the epoxy resins. Since the compounds of the formula I compensate for or even overcompensate the reduction in reactivity frequently caused by conventional reactive diluents, the conventional reactive diluents can be used in greater amounts than in the prior art. In general, however, the conventional reactive diluents in a total amount of at most 1 part by weight, preferably at most 0.8 parts by weight, in particular at most 0.7 parts by weight, based on 1 part by weight of the Epoxidharzkomponente use. Preferably, the total amount of conventional reactive diluent plus compound of the formula I will not be more than 1.1 parts by weight, in particular not more than 1 part by weight and especially not more than 0.9 parts by weight, based on 1 part by weight of the epoxy resins. If the epoxy resin compositions according to the invention comprise one or more conventional reactive diluents, the weight ratio of compound of the formula I to conventional reactive diluent is usually in a range from 1: 100 to 100: 1, in particular in the range from 1:50 to 50: 1 ,

In particular, the conventional reactive diluent will not constitute more than 10% by weight, based on the total amount of reactive diluent + compound I. In another particular embodiment of the invention, the weight ratio of compound I to conventional reactive diluent is in the range from 1:10 to 10: 1, in particular in the range from 1: 5 to 5: 1 and especially in the range from 1: 2 to 2: 1 , The epoxy resin compositions may also contain non-reactive organic diluents. This is understood as meaning organic solvents which have a boiling point below 200 ° C. under atmospheric pressure and which do not undergo any reaction with formation of bonds with the epoxide groups and the groups of an optional reactive diluent. Such diluents are typically organic solvents, for example ketones preferably having 3 to 8 carbon atoms such as acetone, methyl ethyl ketone, cyclohexanone and the like, esters of aliphatic carboxylic acids, preferably acetic acid, propionic acid or butanoic acid, in particular the C 1 -C 6 -alkyl esters - Ser acids such as ethyl acetate, propyl acetate and butyl acetate, aromatic hydrocarbon, in particular alkylaromatics such as toluene, mesitylene, 1, 2,4-trimethylbenzene, n-propylbenzene, isopropylbenzene, cumene, or xylenes and mixtures of alkylaromatics, in particular technical mixtures such as For example, as Solvessomarken commercially available, aliphatic and cycloaliphatic hydrocarbons and alkanols having preferably 1 to 8 carbon atoms and cycloalkanols having preferably 5 to 8 carbon atoms such as methanol, ethanol, n- and isopropanol, butanols, hexanols, cyclopentanol and Cyclohexanol and the like.

In a preferred embodiment, the epoxy resin compositions contain non-reactive organic solvents at most in minor amounts (less than 20 wt .-%, in particular less than 10 wt .-% or less than 5 wt .-%, based on the total weight Epoxy resin and compound of the formula I) and particularly preferably do not contain such a solvent (100% system).

In addition to the aforementioned constituents, the epoxy resin composition may contain the customary fillers and / or additives.

Suitable fillers are, for example, inorganic or organic particulate materials such as calcium carbonates and silicates and inorganic fiber materials such as glass fiber. Organic fillers such as carbon fiber and mixtures of organic and inorganic fillers, such as mixtures of glass and carbon fibers or mixtures of carbon fibers and inorganic fillers may also be used. The fillers may be added in an amount of from 1 to 70% by weight, based on the total weight of the composition. Suitable conventional additives include, for example, antioxidants, UV absorbers / light stabilizers, metal deactivators, antistatics, reinforcing agents, fillers, antifogging agents, blowing agents, biocides, plasticizers, lubricants, emulsifiers, colorants, pigments, rheology agents, impact modifiers, catalysts, adhesion regulators, optical brighteners, flame retardants, Anti-dripping agents, nucleating agents, solvents and reactive diluents, and mixtures thereof.

The optionally used light stabilizers / UV absorbers, antioxidants and metal deactivators preferably have a high migration stability and temperature resistance on. They are selected, for example, from groups a) to t). The compounds of groups a) to g) and i) represent light stabilizers / UV absorbers, while compounds j) to t) act as stabilizers. a) 4,4-diarylbutadienes,

b) cinnamic acid ester,

c) benzotriazoles,

d) hydroxybenzophenones,

e) diphenyl cyanoacrylates,

f) Oxamide,

g) 2-phenyl-1,3,5-triazines,

h) antioxidants,

i) nickel compounds,

j) sterically hindered amines,

k) metal deactivators,

 I) phosphites and phosphonites,

m) hydroxylamines,

n) lemon,

o) amine oxides,

 P) benzofuranones and indolinones,

q) thiosynergists,

 Peroxide-destroying compounds,

s) polyamide stabilizers, and

t) basic costabilizers.

To the amino hardeners

The epoxy resin composition which contains epoxy resins, one or more compounds of the formula I and optionally further constituents is hardened according to the invention by addition of amino hardeners.

Amine hardeners crosslink epoxide resins by reaction of the primary or secondary amino functions of the polyamines with terminal epoxide groups of the epoxy resins. Such amine hardeners have at least two amino groups, in general they have 2 to 6, in particular 2 to 4, amino groups. The amino groups may be primary or secondary amino groups.

Typical amine hardeners are, for example, aliphatic polyamines, such as ethylenediamine, 1,2- and 1,3-propanediamine, neopentanediamine, hexamethylenediamine, octamethylenediamine, 1,10-diaminodecane, 1,1-diaminododecane, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, trimethylhexamethylenediamine. min, 1- (3-aminopropyl) -3-aminopropane, 1, 3-bis (3-aminopropyl) propane, 4-ethyl-4-methylamino-1-octylamine and the like;

cycloaliphatic diamines, such as 1, 2-diaminocyclohexane, 1, 3-bis (aminomethyl) cyclohexane, 1-methyl-2,4-diaminocyclohexane, 4- (2-aminopropan-2-yl) -1-methylcyclohexan-1-amine, Isophoronediamine, 4,4'-diaminodicyclohexylmethane, 3,3'-dimethyl-4,4'-diaminodicyclohexylmethane, 4,8-diamino-tricyclo [5.2.1.0] decane, norbornanediamine, menthanediamine, men- tendiamine and the same;

aromatic diamines, such as toluenediamine, xylylenediamine, in particular meta-xylylenediamine, bis (4-aminophenyl) methane (MDA or methylenedianiline),

 Bis (4-aminophenyl) sulfone (also known as DADS, DDS or dapsone) and the like; cyclic polyamines such as piperazine, N-aminoethylpiperazine and the like;

Polyetheramines, especially difunctional and trifunctional primary polyetheramine based on polypropylene glycol, polyethylene glycol, polybutylene oxide, poly (1, 4-butanediol), poly-THF or polypentylene oxide, for example 4,7,10-Trioxatridecan-1, 3-diamine , 4,7,10-trioxatridecane-1, 13-diamine, 1,8-diamino-3,6-dioxaoctane (XTJ-504 from Huntsman), 1, 10-diamino-4,7-dioxadecane (XTJ-590 of Huntsman), 1,2-diamino-4,9-dioxadodecane (BASF SE), 1,3-diamino-4,7,10-trioxatridecane (BASF), primary polyether amines based on polypropylene glycol having an average molecular weight of 230 as for example, polyetheramines D 230 (BASF SE) or Jeffamine ^® D 230 (Huntsman), difunctional, primary polyetheramine based on polypropylene glycol with an average molar mass of 400, such as polyetheramine D 400 (BASF SE) or Jeffamine ^® XTJ 582 (Huntsman), difunctional, primary polyetheramines based on polypropylene glycol having an average molar mass of 2000, such as, for example, Polyetheramine D 2000 (BASF SE), Jeffam ine ^® D2000 or Jeffamine ^® XTJ 578 (Huntsman), difunctional, primary polyetheramines based on propylene oxide with an average molar mass of 4000, such as polyetheramine D 4000 (BASF SE), trifunctional, primary polyetheramine prepared by reacting propylene oxide with trimethylolpropane followed by amination of the terminal OH groups, with an average molar mass of 403, such as polyetheramine T 403 (BASF SE) or Jeffamine ^® T 403 (Huntsman), trifunctional, primary polyetheramine prepared by reacting propylene oxide with glycerol, followed by amination of the terminal OH groups with an average molar mass of 5000, such as polyetheramines T 5000 (BASF SE) or Jeffamine ^® T 5000 (Huntsman), aliphatic polyether amines, which are composed of a grafted with propylene oxide, polyethylene glycol, and have a mean molar mass of 600, such as Jeffamine ^® ED-600 and Jeffamine ^® XTJ 501 (each Huntsman), a- liphatische Polyetherami ne, which are composed of a propylene oxide-grafted polyethylene glycol and have an average molecular weight of 900, such as Jeffamine ^® ED-900 (Huntsman), aliphatic polyetheramines, which are composed of a propylene oxide-grafted polyethylene glycol and have an average molecular weight of 2000, such as Jeffamine ^® ED-2003 (Huntsman), difunctional, primary polyetheramine prepared by aminating a grafted with propylene oxide, diethylene glycol with an average molar mass of 220, such as Jeffamine ^® HK-51 1 (Huntsman), aliphatic polyetheramine based on a copolymer from poly (tetramethylene ether glycol) and polypropylene glycol with an average molar mass of 1000, such as Jeffamine ^® XTJ-542 (Huntsman), aliphatic polyether amines based on a copolymer of poly (tetra methylene ether glycol) and polypropylene glycol having a mean molecular weight of 1900 such as Jeffamine ^® XTJ-548 (Huntsman), aliphatic polyether amines based on a copolymer of poly (tetramethylene ether glycol) and polypropylene glycol XTJ-559 with an average molar mass of 1400, such as Jeffamine ^® (Huntsman), polyethertriamines produced on the basis of a grafted with butylene oxide, at least trihydric alcohol with an average molar mass of 400, such as Jeffamine ^® XTJ-566 (Huntsman), aliphatic polyetheramines by amination of grafted with butylene oxide alcohols having an average molar mass of 219, such as Jeffamine ^® XTJ-568 (Huntsman), polyetheramines based on pentaerythritol and propylene oxide with an average molar mass of 600, such as Jeffamine ^® XTJ- 616 (Huntsman), Polyether amines based on triethylene glycol with an average molecular weight of 148, eg Jeffam ine ^® EDR-148 (Huntsman), difunctional, primary polyetheramine prepared by aminating a grafted with propylene oxide, ethylene glycol, with an average molar mass von176 such as Jeffamine ^® EDR-176 (Huntsman) and polyetheramines prepared by aminating polyTHF with an average minor mass of 250, eg PolyTHF-amine 350 (BASF SE) and mixtures of these amines.

 Polyamidoamines (amidopolyamines) obtained by the reaction of polycarboxylic acids, in particular dicarboxylic acids such as adipic acid or dimeric fatty acids (eg dimeric linoleic acid) with low molecular weight polyamines such as diethylenetriamine, 1- (3-aminopropyl) -3-aminopropane or triethylenetetramine or other diamines such the aforementioned aliphatic or cycloaliphatic diamines are obtainable or alternatively obtainable by Michael addition of diamines to acrylic ester and subsequent polycondensation of the resulting amino acid esters, or

Phenalamines (also phenolalkanamines), which are understood as meaning phenol or phenol derivatives which are substituted on at least one carbon atom of the ring system by hydrocarbon groups which contain primary or secondary amino groups; Apart from the hydroxyl group of the phenol or phenol derivative and the primary or secondary amino groups, the phenalkamines contain no further functional groups. In particular, the phenalkamines contain both primary and secondary amino groups. Highly suitable phenalkamines preferably contain a total of 2 to 10, in particular 2 to 8 and in a particular embodiment 4 to 6 such amino groups; Preferred are phenalkamines based on cardanol, which is contained in cashew peel oil; Cardanol-based phenalkamines are substituted on at least one, preferably one to three, carbon atoms of the ring system by preferably aliphatic hydrocarbon groups containing primary or secondary amino groups as described above. In particular, these substituents are ortho or para to the hydroxyl group; Phenalcamines can be prepared by Mannich reaction from the phenol or phenol derivative, an aldehyde, and a compound having at least one primary or secondary amino group. The phenalkamines are therefore Mannich bases or adducts of amino compounds, in particular one of the above amino compounds to epoxide compounds and mixtures of the aforementioned amine hardeners.

According to the invention, 0.1 to 50% by weight of the amino hardeners used are aliphatic, cycloaliphatic or aromatic amine compounds having 1 to 4 primary amino groups and optionally further functional groups selected from secondary amino groups, tertiary amino groups and hydroxyl groups, where the primary Amino groups are bound in the case of the cycloaliphatic and aromatic amine compounds as Aminomethyl lengruppen (H2N-CH2-) to the cycloaliphatic or aromatic ring system.

These amine hardeners are hereinafter also referred to as co-hardeners, while other amine hardeners which do not fall under the above definition of the co-hardeners are simply called hardeners in the following. To the co-hardeners

Co-hardeners used according to the invention may be aliphatic, cycloaliphatic or aromatic amine compounds. The co-curing agents having 1 to 4 primary amino groups contain no further functional groups apart from secondary or tertiary amino groups or hydroxyl groups.

Preferred co-hardeners are e.g. aliphatic amine compounds which, apart from a primary amino group, contain no further functional groups, e.g. C 2 to C 8 alkylene amines, such as ethylamine, propylamine or butylamine.

Preferred co-hardeners are e.g. also linear or branched aliphatic amine compounds which contain two primary amino groups and otherwise no further functional groups, e.g. C 2 to C 8 alkylenediamines, such as ethylenediamine, propylenediamine or butylenediamine.

Preferred co-hardeners are e.g. also aliphatic amine compounds which contain one or two primary amino groups and one or two hydroxyl groups and otherwise no further functional groups, e.g. Monoamines, such as C 2 - to C 8 -alkanolamines, such as ethanolamine, isopropanolamine,

Preferred co-hardeners are e.g. also aliphatic amine compounds which contain a primary amino group and a tertiary amino group otherwise no further functional groups. Called e.g. Compounds of the formula II

R \

 N-X-NH,

b ' ²

R In formula II, R ^a and R ^b independently of one another are a C 1 - to C 10 -alkyl, preferably a C 1 - to C 4 -alkyl group. X is a C2 to C10, preferably a C2 to C4 alkylene group. The alkylene group may be branched or linear; it is substituted at any position by the tertiary and primary amino groups. In a preferred embodiment, the alkylene group is linear and terminal substituted by the tertiary and primary amino groups. As one of the particularly preferred co-hardener is, for example, 3-dimethylamino) - propylamine (DMAPA) called.

Preferred co-hardeners are also aliphatic amine compounds which contain one or two primary amino groups, preferably a primary amino group, and one secondary amino group and one hydroxyl group and no other functional groups otherwise. These are in particular N- (2-aminoalkyl) alkanolamines, e.g. N- (2-aminoethyl) ethanolamine (H2N-CH2-CH2-NH-CH2-CH2-OH). Preferably, the two alkylene groups in these compounds consist of 2 to 8 C atoms.

Preferred aromatic co-hardeners are, for example, benzene substituted by one to three aminomethylene groups (H 2 N-CH 2 -). In particular, it is benzene, which is substituted by two H2N-CH2 groups at any position of the benzene ring, for example xylenediamine having the formula

Preferred cycloaliphatic co-hardeners are e.g. also by one to three aminomethylene (H2N-CH2-) substituted cyclohexane. In particular, it is cyclohexane, which is substituted by two H2N-CH2 groups at any position of the benzene ring.

Of course, any mixtures of the above co-hardener come into consideration.

The co-hardeners preferably have a molecular weight of less than 500 g / mol, in particular less than 300 g / mol.

A total of at most 10 C atoms are preferred co-hardeners; particularly preferred co-hardeners consist overall of a maximum of 8 C atoms.

Of the above-mentioned co-curing agents, the aliphatic compounds are preferred; Particularly preferred aliphatic compounds are those having only one primary amino group and optionally a tertiary amino group or optionally a hydroxyl group and no other functional group otherwise.

The weight fraction of the co-hardener is preferably from 2 to 40% by weight, more preferably from 5 to 35% by weight, based on the total by weight of all amino hardeners. The co-curing agents are preferably used in amounts of from 0.1 to 30 parts by weight, more preferably in amounts of from 0.5 to 20 parts by weight, based on epoxy resins a).

The amine hardeners used in addition to the co-hardeners are amine hardeners which do not fall under the above definition of the co-hardeners; these are, as stated above, simply called hardeners in the following. The proportion of these hardeners is then correspondingly preferably 60 to 98 wt.%, Particularly preferably 65 to 95 wt.%, Based on the total by weight of all amine hardener. Such hardeners are e.g. Polyamidoamines, phenalkamines, epoxy-amine adducts, polyetheramines or other different from the co-curing amine compounds or mixtures thereof.

The hardeners are preferably polyamidoamines, phenalkamines, epoxy-amine adducts, polyetheramines or mixtures thereof.

Co-hardeners and hardeners can be mixed in advance and then added to the epoxy resin composition as a mixture, but they can also be added separately. They may also be added simultaneously or in conjunction with other components of the epoxy resin composition. As such components are e.g. the above additives are considered. Also contemplated as such further ingredients are catalysts which accelerate the cure-reaction, e.g. Phosphonium salts of organic or inorganic acids, imidazole and imidazole derivatives or quaternary ammonium compounds. The catalysts (also called accelerators), if desired, in proportions of 0.01 wt .-% to about 10 wt .-%, based on the total weight of the epoxy resin, the compound I and hardener used. In a preferred embodiment, no catalysts are needed, i. H. the content of catalysts in the composition is less than 0.01% by weight. The amount of co-hardener and hardener required for curing is determined in a manner known per se via the number of epoxide groups in the formulation and the number of functional groups in the hardener. The number of epoxide groups in the epoxy resin is given as a so-called epoxide equivalent. The epoxide equivalent is determined according to DIN 16945. The number of primary and secondary amino groups can be calculated by the amine number according to DIN 16945.

The hardeners and co-hardeners are used in amounts such that the ratio of the number of all primary and secondary amino groups and the number of all epoxy groups in the epoxy resin 2: 1 to 1: 2, preferably 1, 5: 1 to 1: 1, 5 and in particular about 1: 1. At a stoichiometric ratio of about 1: 1 gives a cured resin with optimal thermosetting properties. Depending on the desired properties of the resin Networking, it may also be useful to use hardener and epoxy resin in other ratios of the reactive groups.

Accordingly, in the epoxy resin compositions according to the invention, the total amount of compounds of co-hardeners and hardeners is generally from 0.1% by weight to 50% by weight, frequently from 0.5 to 40% by weight and in particular from 1 to 30% by weight .-%, based on the total weight of epoxy resin a), compounds of the formulas I, co-hardeners and hardeners.

In addition to the amine hardener mixture used according to the invention, other hardeners, e.g. Anhydride hardener, to be used. In a preferred embodiment, however, only compounds of amine compounds are used.

For epoxy resin compositions, one generally distinguishes between one-component (1K) and two-component (2K) systems. In 2K systems, the epoxy resin and hardener remain separated until just before curing (hence 2K); Epoxy resin and hardener are very reactive, so the hardener can be added just before curing.

The process according to the invention is in particular a curing process for 2K systems. The addition of the hardener mixture of co-hardener and hardener is accordingly only shortly before use.

The two part epoxy resin composition therefore comprises a separate binder composition containing

a) an epoxy resin and

b) a compound of formula I and a separate hardener mixture containing

c) co-hardener and

d) hardener

After addition of the hardener mixture, at the beginning of the curing, the epoxy resin composition contains a) an epoxy resin

b) a compound of the formula I

c) co-hardener and

d) hardener. The cure can then be thermally heated by heating the composition

respectively. Typically, the curing of the epoxy resin compositions according to the invention takes place at temperatures in the range of -10 to 200 ° C, preferably in the range of -10 to 180 ° C and in particular in the range of -10 to 150 ° C. Alternatively, the curing can be done, for example, microwave-induced. In particular, the curing is carried out at -10 to 80 ° C and in a particularly preferred embodiment at -10 to 40 ° C or at -10 to 20 ° C. It is advantageous that the curing can take place under normal ambient conditions such as room temperature and / or exposure to sunlight.

The process according to the invention or the above-defined epoxy resin composition with constituents a) to d) can be used in many ways. The epoxy resin compositions are basically suitable for all applications in which 1K or 2K epoxy resin formulations are usually used. They are suitable, for example, as a binder component in coating or impregnating agents, as adhesives, for producing composite materials, in particular those based on carbon fiber materials or glass fiber materials, for the production of moldings or as castables, in particular as casting compounds for embedding, bonding or solidification of molded articles , This and the following explanations apply to both the 1K and 2K systems, with preferred systems being the 2K systems for all of the above uses.

As coating agents, e.g. Called paints. In particular, with the epoxy resin compositions according to the invention (1 K or 2 K) or with the process according to the invention, scratch-resistant protective lacquers on any substrates, e.g. be obtained from metal, plastic or wood materials.

Since the reactivity of the epoxy resin compositions is comparatively high, curing at low temperatures, e.g. in the range of 0 to 50 ° C and in particular in the range of 5 to 35 ° C. This makes the epoxy resin compositions particularly suitable for the coating of very large-area substrates, which can not or only with difficulty be heated to temperatures above the ambient temperature. This includes, in particular, the coating of soils, in particular in heavily used areas, e.g. for coating running areas of public buildings or squares or for coating parking areas and access areas of parking areas. This includes, in particular, the coating of large-area metal parts and metal structures, such as those in or on buildings or ships (so-called marine coating).

The epoxy resin compositions are also useful as insulating coatings in electronic applications, e.g. as an insulating coating for wires and cables. Also mentioned is the use for the production of photoresists. They are also particularly suitable as a refinish varnish, e.g. also when repairing pipes without dismantling the pipes (your in-place pipe (CIPP) rehabilitation). They are also suitable for sealing or coating of floors.

The epoxy resin compositions are also suitable as adhesives, for example 2K structural adhesives. Structural adhesives are used for the permanent connection of molded parts with each other. The moldings may be made of any material; materials from art fabric, metal, wood, leather, ceramics, etc. These may also be hotmelt adhesives (hot melt adhesives), which are only able to flow and process at higher temperatures. It can also be floor adhesives. The compositions are also suitable as adhesives for the production of printed circuit boards (electronic curcuits), in particular according to the SMT method (surface mounted technology).

The epoxy resin compositions are especially suitable for the production of composite materials. In composites, different materials, e.g. Plastics and reinforcing materials (fibers, carbon fibers) are joined together by the cured epoxy resin.

The epoxy resin compositions are useful e.g. for the production of fibers impregnated with epoxy resins or for the production of prepreg yarns and fabrics made of fibers, e.g. for the production of prepregs which are further processed into composite materials. Composites for the preparation of composites include the curing of prepreg fibers or fabrics (e.g., prepregs) after storage, or extrusion, pultrusion, winding, and Resin Transfer Molding (RTM), Resin Infusion Technologies (RI). In particular, the fibers or the yarns and fabrics produced therefrom can be impregnated with the composition according to the invention and then cured at a higher temperature.

As casting compounds for embedding, bonding or solidification of moldings, the epoxy resin compositions are e.g. used in electronic applications. They are suitable as flip-chip underfill or as electro casting resins for potting, casting and (glob-top) encapsulation.

The process according to the invention is in particular a process for coating surfaces, in which the epoxy resin composition comprising components a) to d) is applied to the surface to be coated and cured. This coating method is subject to no restrictions with regard to the surface to be coated. Examples of suitable surfaces are metal surfaces, wood surfaces, glass surfaces, plastic surfaces. However, a person skilled in the art can determine by simple preliminary tests whether other surfaces are suitable for coating in accordance with the method according to the invention.

As special advantages of the present invention co-used compounds co-hardener the good performance properties and in particular the high rate of cure called.

Examples:

1) starting materials Compound of the formula I: 4,4-dimethyl-5-methylene-1,3-dioxolan-2-one

 The preparation of this compound was carried out in analogy to that known from DE 3233403

 Provision.

As epoxy resins, the following substances were used:

Epoxy Resin 1: Aromatic bisphenol A based epoxy resin having an epoxide equivalent of 182-192 g / equiv. and a viscosity at 25 ° C in the range of 10-14 Pa s (Epilox A 19-03).

The hardeners used were the following substances:

Phenalkamine (Mannich base of Cardanol (Cardolite NC557)

Polyamidoamine (Ancamide 2353)

PolyTHFamine350 Products) with the formula

As co-hardener, the following substances were used:

3- (dimethylamino) propylamine (DMAPA)

Xylenediamine (MXDA: H ₂ N-CH ₂ -phenyl-CH ₂ -NH ₂ )

isopropanolamine

Aminoethylethanolamine of the formula

2) Application test 1 .1) Determination of gel time

To determine the gel time, rheological tests of the epoxy resin compositions were carried out. The reactivity of the compositions was determined by monitoring the course of the reaction with a rheometer (oscillation mode). For evaluation, the measured memory module G 'was plotted against the loss modulus C. The intersection of both curves is the gel point. The appropriate time is the gel time. The gel time is a measure of the reactivity of the epoxy composition. The shorter the gel time, the higher the reactivity. For this purpose, the hardener and the co-hardener were added to the epoxy resin in the amounts indicated in the table and added directly to the measuring cell of the rheometer. The temperature was 23 ° C or 10 ° C (indicated in the table, respectively). The total amount of hardener and co-hardener was chosen so that the primary and secondary amino groups were in total stoichiometric amounts to the epoxy groups.

Table 1: Gel time (GT stands for parts by weight) 23 ° C

Table 2: Gel time (GT stands for parts by weight) 23 ° C

Table 3: Gel time (GT stands for parts by weight) 23 ° C

Table 4: Gel time (GT stands for parts by weight) 23 ° C

Table 5: Gel time (GT stands for parts by weight) 10 ° C

Table 6: Gel time (GT stands for parts by weight) 10 ° C

Claims

 claims: 1 . Process for the curing of epoxy resins, characterized in that epoxy resin compositions containing a) epoxy resins and  b) a compound of general formula I.

 wherein R ¹ and R ² are each independently hydrogen, Ci-C6-alkyl, _{Ci-C4-alkoxy-Ci-C 4} - alkyl, C ₅ -C ₆ cycloalkyl, phenyl, phenyl-Ci-C ₄ alkyl, C C ₂ -C ₆ -alkenyl or C ₂ -C ₆ -alkynyl, or R ¹ and R ² together represent a C ₃ -C ₅ -alkylene group; R ³ and R ⁴ are each independently hydrogen, Ci-C6-alkyl, _{Ci-C4-alkoxy-Ci-C 4} - alkyl, C ₅ -C ₆ cycloalkyl, phenyl, phenyl-Ci-C ₄ alkyl, C C ₂ -C ₆ alkenyl or C ₂ -C ₆ alkynyl, or R ³ and R ⁴ together represent a C ₄ -C ₆ alkylene group; contain, are hardened by the addition of amino hardeners and it is from 0.1 to 50 wt.% Of the amino hardener to aliphatic, cycloaliphatic or aromatic amine compounds having 1 to 4 primary amino groups and optionally further functional groups selected from secondary amino groups, tertiary amino groups and hydroxyl groups , wherein the primary amino groups in the case of the cycloaliphatic and aromatic amine compounds are bound as aminomethylene groups (H ₂ N-CH ₂ -) to the cycloaliphatic or aromatic ring system (hereinafter referred to as co-hardener). A process according to claim 1, characterized in that the epoxy resins are polyglycidyl ethers of aromatic, aliphatic or cycloaliphatic polyols. Process according to Claim 1 or 2, characterized in that R 1 in formula I is chosen from hydrogen and C 1 -C 4 -alkyl, and R 2 in formula I is selected from C 1 -C 4 -alkyl, C 1 -C 4 -alkoxy-C 1 -C 4 -alkyl alkyl or R1 and R2 together represent a C4-C6 alkylene group. A method according to any one of claims 1 to 3, characterized in that R1 and R2 in formula I independently of one another represent C1-C4-alkyl. 5. The method according to any one of claims 1 to 4, characterized in that R3 and R4 are hydrogen. Process according to any one of Claims 1 to 5, characterized in that the co-curing agents are aliphatic compounds containing two primary amino groups. A process according to any one of claims 1 to 5, characterized in that the co-curing agents are aliphatic compounds having a primary and a tertiary amino group. A process according to any one of claims 1 to 5, characterized in that the co-curing agents are aliphatic compounds having a primary amino group and one or two hydroxyl groups. A process according to any one of claims 1 to 5, characterized in that the co-curing agents are aromatic or cycloaliphatic compounds having two amino-methylene groups. A method according to any one of claims 1 to 9, characterized in that the co-hardener in amounts of 0.1 to 20 wt. Share, based on the epoxy resin a) are used. A method according to any one of claims 1 to 10, characterized in that the other amine hardeners are selected from polyamidoamines, phenalkamines, epoxy-amine adducts, polyetheramines or other different from the co-curing A- minverbindungen (hereinafter called hardener for short). A two part epoxy resin composition comprising a separate binder composition containing  a) an epoxy resin and  b) a compound of formula I and a separate hardener mixture of amine hardeners containing  c) a co-hardener and d) a hardener 13. Epoxy resin composition containing  a) an epoxy resin  b) a compound of the formula I  c) a cohardener and  d) a hardener 14. Use of epoxy resin compositions according to claim 12 or 13 as or in coating compositions. 15. Use of epoxy resin compositions according to claim 12 or 13 in  Casting compounds. 16. Use of epoxy resin compositions according to claim 12 or 13 for the production of composite materials. 17. Use of epoxy resin compositions according to claim 12 or 13 in structural adhesives. 18. Use of epoxy resin compositions according to claim 12 or 13 for the impregnation of fibers or yarns or fabrics made of fibers.