CA2153095A1

CA2153095A1 - Elastic one-component expoxy resin system of high storage stability, process, and use thereof

Info

Publication number: CA2153095A1
Application number: CA002153095A
Authority: CA
Inventors: Manfred Marten; Bernhard Wehner
Original assignee: Hoechst AG
Current assignee: Hoechst AG
Priority date: 1994-07-01
Filing date: 1995-06-30
Publication date: 1996-01-02
Also published as: JPH08100051A; DE4423138A1; KR960004441A; RU95110782A; EP0694571A1

Abstract

Elastic epoxy resin composition including (A) compounds having at least two 1,2-epoxide groups, which are obtainable by reaction of polyepoxides (A1) having at least two epoxide groups per molecule and polyoxyalkylene monoamines (A2) and optionally polycarboxylic acids (A3), (B) optionally compounds having at least two 1,2-epoxide groups, which are obtainable by reaction of poly-epoxides (B1) having at least two 1,2-epoxide groups per molecule and sterically hindered aliphatic mono-amines (B2), (C) 1,2-epoxide compounds which are chosen from polyepoxides which differ from (A1) and (B1) and the unreacted contents of the compounds (A1) or (B1) from the preparation of the compounds (A) and (B), (D) .omega.-imi-dazolyl-alkanoguanamines, (E) latent curing agents and (F) if appropriate further additives, are useful, for example, in elastic coatings and elastic adhesives.

Description

...

ELASTIC ONE-COMPONENT EPOXY RESIN SYSTEM
OF HIGH STORAGE STABILITY, PROCESS, AND USE THEREOF

Backqround of the Invention Epoxy resins, in particular those which are prepared from bisphenol A and epichlorohydrin, are known raw materials for the preparation of high-quality casting - resins, coating compositions, and adhesives. These aromatic epoxy resins, which are cured, for example, with polyamines, have a good adhesive strength on many substrates, in addition, to a good resistance to chemicals and solvents. However, the applicability of these resins/hardener systems is often limited by an i inadequate elasticity or flexibility in the crosslinked state. The elasticity of the nonmodified standard epoxy resin systems is inadequate, in particular, for applications where alternating temperature stresses must be absorbed by a high extensibility of the coating materials.
In the adhesive sector, epoxy resin systems which are still sufficiently elastic at low temperatures, i.e., below 0C, are desired. For example, epoxy resin adhesives which have only little flexibility~ in the completely cured state are used in the automobile industry. Although the gluings obtained with them have a high tensile shear strength, they easily flake by peeling when attacked from the side.
The completely cured epoxy coatings and glued seams often come into contact with aggressive chemicals and solvents. The coating or the glued seam, therefore, should also be resistant under these conditions. The elastic epoxy systems should, therefore, be built up such that they impart to the cured composition the highest possible resistance to chemicals.
Moreover, one-component coating materials and adhesives which can be processed extremely quickly and at 21~30~5 the same time have a good storage stability are desired for the most diverse applications.
In principle, the elasticity of epoxy resin systems can be increased externally by addition of plasticizer or internally by reduction of the crosslinking density.
However, external elasticizing agents are not reactive and are not incorporated into the thermosetting resin network. This type of modification is also limited to only a few fields of use, since it has a number of disadvantages. For example, these external additives lead to a marked disturbance in the thermosetting resin structure, are limited in their plasticizing effect at low temperatures, and tend to exude when exposed to heat and during aging, the cured systems thereby becoming brittle. In internal modification, compounds which react with the epoxy resins or hardeners and are included in the crosslinking are added to increase the elasticity internally. The elasticizing action is achieved by incorporation of long-chain aliphatic or highly branched additives into the resin or hardener components.
Flexible one- and two-componént epoxy resin systems based on polyoxypropylenedi- and -triamines are described by Vazirani [Adhesives Age, October 1980, pages 31-35].
These amines are available commercially from Texaco under the trade name "Jeffamine~". The one-component system is cured with dicyandiamide.
U.S. Patent 4,423,170 describes aqueous epoxy resin compositions which comprise (A) diepoxides obtained by reaction of diepoxides and polyoxyalkyleneamines having 30a molecular weight of 900 to 2500 g/mol and (B) a latent hardener.
EP-B 0 109 174 relates to an epoxy resin composition comprising (A) a polyepoxide and (B) a curing agent, formed by reacting a polyepoxide with 50 to 70 % by weight of a polyoxyalkylene monoamine having a molecular weight of 900 to 2000 g/mol. The resin/hardener mixture described here can be used in the form of a one- or two--21~3095 component system as a flexible adhesive, is distinguished by a low viscosity and can, therefore, be used without addition of solvent.
German Patent Application DE-P 43 42 721.9 (US-SN
08/355 303 of 12/12/1994) describes an epoxy resin composition comprising compounds (A) which contain at least two 1,2-epoxide groups, which are reaction products of compounds (Al) having at least two 1,2-epoxide groups per molecule, polyoxyalkylene monoamines (A2) having a molecular weight of 130 to 900 g/mol and optionally polyoxyalkylene monoamines (A3) having a molecular weight of 900 to 5000 g/mol and optionally polycarboxylic acids (A4), and curing agents (B) and if appropriate customary additives (C).
German Patent Application DE-P 43 42 722.7 (US-SN
08/355 304 of 12/12/1994) describes an elastic epoxy resin composition comprising compounds (A) having at least two 1,2-epoxide groups, which are reaction products of compounds (Al) having at least two 1,2-epoxide groups per molecule, polyoxyalkylene monoamines (A2) having a molecular weight (number average) greater than 900 g/mol, which can optionally contain a molar content of up to - 20 % of oxyethylene units, based on the total amount of oxypropylene and oxyethylene units, optionally polycarboxylic acids (A3), and curing agents (B) and if appropriate customary additives (C). Both specifications disclose reactive adhesives which provide high peel and tensile shear strengths and in particular are distinguished by a high corrosion protection of the cured system on non-degreased metal sheets.
German Patent Application DE-P 44 10 786.2 (US-SN
not yet assigned of 03/23/1995) furthermore discloses an epoxy resin composition comprising compounds (A) containing at least two 1,2-epoxide groups, which are reaction products of compounds (A1) having at least two 1,2-epoxide groups per molecule, optionally mixed with monoepoxides (A2), polyoxyalkyleneamines (A3) and 21S309s optionally polycarboxylic acids (A4), compounds (B) containing at least two 1,2-epoxide groups, which are reaction products of compounds (Bl) having at least two 1,2-epoxide groups per molecule, optionally mixed with monoepoxides (B2), and sterically hindered amines (B3), and 1,2-epoxide compounds (C), which are not the same as (Al), (A2~, (Bl) or (B2), or unreacted contents of the compounds (Al), (A2), (B1) and (B2) from the preparation of the compounds (A) and (B), curing agents (D) and if - 10 appropriate further additives (E).
The epoxy resin composition according to DE-P 44 10 786.2 (US SN not yet assigned) gives lower-viscosity epoxy or epoxy/hardener mixtures, which moreover have an improved elasticity at low temperatures, than the systems described in DE-P 43 42 721.9 (US-SN
08/355 303 of 12/12/1994) and DE-P 43 42 722.7 (US-SN
08/355 304 of 12/12/1994), with equally good corrosion protection and strength values.
From the documents cited above, latent hardeners, in particular dicyandiamide, are known as curing agents for elastic epoxy resins. The DE specifications also disclose the co-use of accelerators. According to the descriptions ofunpublished applications DE-P 43 42 721.9 (US-SN 08/355 303 of 12/12/1994), DE-P 43 42 722.7 (US-SN
08/355 304 of 12/12/1994) and DE-P 44 10 786.2 (US-SN not yet assigned of 03/23/1995), this accelerator can be, inter alia, imidazoles.
Japanese Patent 5-163331 discloses an epoxy resin composition of 100 parts by weight of epoxy resin, enough dicyandiamide for 0.1 to 1.2 amino hydrogen atoms to be present per glycidyl group, and in each case 0.1 to 10 parts by weight of two ~-imidazolyl-alkanoguanamines of the formula \C C ~ NH2 \ N

C N C

21~3095 in which A is an alkylene group having l to 8 carbon atoms, which can optionally additionally be substituted by alkyl groups; and R11, R12 and R13 are hydrogen or an 7alkyl group having l to 20 carbon atoms. ~-Imidazolyl-5 alkanoguanamines according to that invention are regularly also understood as meaning those in which the alkylene group is substituted by further alkyl groups.
This resin/hardener system shows a good storage -stability and cures within a short time even at low lO temperatures. According to the description, glycidyl compounds of phenols, alcohols or aromatic amines, and alicyclic and heterocyclic epoxy resins are used as the epoxy resins.
However, the systems obtained are brittle at room 15 temperature and at a higher temperature. Also, the adhesion to substrates such as sheet metal, plastics or textiles is inadequate.
The compositions described in documents cited above have the common feature of a curing time of 5 minutes to several hours at 140C up to about 200C, depending on the resin/hardener system and the intended use.

Summary of the Invention An object of the present invention is to provide one-component epoxy resin/hardener compositions from which elastic adhesives and coating compositions which are distinguished by the following properties can be prepared:
l. After complete curing, an elastic to highly elastic composition should be obtained.

2. The one-component resin/hardener mixture should be stable to storage over several weeks.

3. The complete curing time of the resin/hardener system should be extremely short; a time 21S3~95 significantly below 5 minutes, for example, 1 minute, is desired.

4. The completely cured composition should be highly crosslinked and resistant to chemicals including salt solutions, dilute acids, and bases and solvents.

5. The resin/hardener system should have the lowest possible viscosity, i.e., the epoxy resin should have a viscosity of less than 25,000 mPas, in particular, less than 10,000 mPas.

With the systems known from the prior art, it is not possible for all the properties required to be achieved , at the same time.
It is also an object of the present invention to provide methods of making and using such systems.
Surprisingly, these and other objects have been achieved according to the invention by an epoxy resin composition including (A) compounds having at least two 1,2-epoxide groups, which are obtained by reaction of polyepoxides (Al) having at least two epoxide groups per molecule and polyoxyalkylene monoamines (A2) and optionally polycarboxylic acids (A3), (B) optionally compounds having at least two 1,2-epoxide groups, which are obtained by reaction of polyepoxides (Bl) having at least two 1,2-epoxide groups per molecule and sterically hindered aliphatic monoamines (B2), (C) 1,2-epoxide compounds which are chosen from polyepoxides which differ from (Al) and (Bl), and the unreacted components of compounds (Al) or (Bl) from the preparation of compounds (A) and (B), (D) ~-imidazolyl-alkanoguanamines, (E) latent curing agents, and, if appropriate, (F) further additives.

21S3~9~
-According to the invention, there is also provided processes for preparing such compositions and coatings containing the composition, and substrates coated with the composition.
Further, objects, features, and advantages of the present invention will become apparent from the detailed description of preferred embodiments that follow.

Detailed Description of Preferred Embodiments Preferred ranges of the ratio of the number of epoxy groups in component (Al) to (primary) amino groups in component (A2) are from 10:1 to 5:4, preferably from 5:1 to 3:2. The same range is preferred for the ratio of the numbers of functional groups (epoxy and amino) in components (B1) and (B2).
If component (B) is present in the composition, its mass fraction is preferably less than 40 per cent of the mass of (A) and (B) taken together, most preferred between 5 and 35 per cent.
As the number of epoxy groups in (A1) or (B1) usually exceeds the number of amino groups in (A2) or (B2), there is a substantial amount of unreacted epoxy components (Al) or (Bl) in the composition. Other epoxy components (C) can still be added. The mass fraction of these unreacted epoxy components and additional epoxy components (C) in the total mass of (A), (B) and (C) is up to 90 per cent, preferably up to 80 per cent.
If present, the ratio of the number of carboxyl groups in component (A3) to the number of epoxy groups in (A1) is up to 1:3, preferably from 1:20 to 1:5.
Useful poly-epoxide compounds (A1), (Bl) and (C) include any known in the art such as the large number of the compounds known for this purpose which contain more than one epoxide group, preferably two epoxide groups, per molecule. These epoxide compounds (epoxy resins) can be either saturated or unsaturated, and aliphatic, 2153~9~

cycloaliphatic, aromatic or heterocyclic, and can also contain hydroxyl groups. They can furthermore contain those substituents which do not cause troublesome side reactions under the mixing or reaction conditions, for example, alkyl or aryl substituents, ether groupings, and the like.
They are preferably glycidyl ethers which are derived from polyhydric alcohols or phenols, in parti-~cular bisphenols and novolaks, and which have molecular -10 weights, divided by the number of epoxide groups ~
("epoxide equivalent weights", "EV values") of between 150 and 500, and in particular between 150 and 250 g/mol.
Glycidyl ethers (A11) of alcohols or phenols having in each case at least two hydroxyl groups, in each case at least two of the hydroxyl groups being glycidylated, polyepoxides (A12) of polyunsaturated aliphatic or mixed aliphatic-aromatic compounds and glycidyl esters (A13) of polybasic organic acids are particularly preferred.
Polyhydric phenols useful in preparing the polyepoxides include, for example: resorcinol, hydro-quinone, 2,2-bis-(4-hydroxyphenyl;propane (bisphenol A), isomer mixtures of dihydroxydiphenylmethane (bis-phenol F), 4,4'-dihydroxydiphenylcyclohexane, 4,4'-dihydroxy-3,3'-dimethyldiphenylpropane, 4,4'-dihydroxydiphenyl, 4,4'-dihydroxybenzophenone, bis-(4-hydroxyphenyl)-1,1-ethane, bis-(4-hydroxyphenyl)-l,l-isobutane, 2,2-bis-(4-hydroxy-tert-butylphenyl)propane, bis-(2-hydroxynaphthyl)methane, 1,5-dihydroxynaphthalene,tris-(4-hydroxyphenyl)methane, bis-(4-hydroxyphenyl) ether, bis-(4-hydroxyphenyl) sulfone and the like, and the chlorination and bromination products of the above-mentioned compounds, such as, for example, tetrabromo-bisphenol A. Liquid diglycidyl ethers based on bisphenol A and bisphenol F
having an epoxide equivalent weight of 180 to 190 g/mol are especially preferred, in particular as epoxide compounds (A1).

It is also possible to use as epoxy (Al), (Bl), and/or (C) polyglycidyl ethers of polyalcohols, such as, for example, ethanediol 1,2-diglycidyl ether, propanediol 1,2-diglycidyl ether, propanediol 1,3-diglycidyl ether, butanediol diglycidyl ether, pentanediol diglycidyl ether, neopentylglycol diglycidyl ether, hexanediol diglycidyl ether, diethyleneglycol diglycidyl ether, dipropyleneglycol diglycidyl ether, higher polyoxy--alkyleneglycol diglycidyl ethers, such as, for example, -10 higher polyoxyethyleneglycol diglycidyl ethers and polyoxypropyleneglycol diglycidyl ethers, mixed polyoxy-ethylene/propyleneglycoldiglycidylethers,polyoxytetra-methyleneglycol diglycidyl ethers, polyglycidyl ethers of glycerol or of 1,2,6-hexanetriole, trimethylolpropane, trimethylolethane, pentaerythritol or sorbitol, poly-glycidyl ethers of oxyalkylated polyols (such as, for -example, of glycerol, trimethylolpropane and penta-erythritol), diglycidyl ethers of cyclohexanedimethanol, bis-(4-hydroxycyclohexyl)methane and 2,2-bis-(4-hydroxy-cyclohexyl)propane, polyglycidyl ethers of castor oil, and triglycidyl tris-(2-hydroxyethyl)-isocyanurate.
Polyoxypropyleneglycol diglycidyl ethers having an epoxide equivalent weight of 150 to 800, in particular 300 to 400 g/mol, are especially preferably employed, in particular as epoxide compounds (Bl).
Useful components (Al) and (Bl) furthermore include poly-(N-glycidyl) compounds which are obtainable by dehydrohalogenation of the reaction products of epi-chlorohydrin and amines, such as aniline, n-butylamine, bis-(4-aminophenyl)methane, m-xylylenediamine or bis-(4-methylaminophenyl)methane. The poly-(N-glycidyl) compounds also include, however, triglycidyl iso-cyanurate, triglycidyl urazole and oligomers thereof, N,N'-diglycidyl derivatives of cycloalkyleneureas and diglycidyl derivatives of hydantoins and the like.
It is furthermore also useful to employ polyglycidyl -esters (A13) of polycarboxylic acids which are obtained 21S3~5 by reaction of epichlorohydrin or similar epoxide compounds with an aliphatic, cycloaliphatic or aromatic polycarboxylic acid, such as oxalic acid, succinic acid, adipic acid, glutaric acid, phthalic acid, terephthalic acid, tetrahydrophthalic acid, hexahydrophthalic acid and 2,6-naphthalene dicarboxylic acid. Examples are diglycidyl adipate, diglycidyl phthalate and diglycidyl hexahydrophthalate. Other suitable glycidyl esters include higher dicarboxylic acid diglycidyl esters, such - 10 as, for example, of dimerized or trimerized linolenic acid. Glycidyl esters of unsaturated carboxylic acids and epoxidized esters of unsaturated alcohols or unsaturated carboxylic acids may furthermore be mentioned.
lS In addition to the polyglycidyl ethers (A1), (C), and optionally (B1), small amounts of monoepoxides which may act as reactive diluents, such as, for example, methylglycidyl ether, butylglycidyl ether, allylglycidyl ether, ethylhexylglycidyl ether, long-chain aliphatic glycidyl ethers, such as, for example, cetylglycidyl ether and stearylglycidyl ether, monoglycidyl ethers of a higher isomeric alcohol mixture, glycidylethers of a mixture of C12 to C13 alcohols, phenylglycidyl ether, cresylglycidyl ether, p-t-butylphenylglycidyl ether, p-octylphenylglycidyl ether, p-phenyl-phenylglycidyl ether, glycidyl ethers of an oxyalkylated lauryl alcohol and monoepoxides such as, for example, epoxidized monounsaturated hydrocarbons (butylene oxide, cyclohexene oxide or styrene oxide), or halogen-containing epoxides, such as, for example, epichlorohydrin, can also be used in the composition, for example, in weight contents generally of up to 30%, preferably 10 to 20%, based on the weight of the polyglycidyl ethers.
A detailed list of the suitable epoxide compounds for the present composition is to be found, for example, in the handbook "Epoxidverbingungen und Epoxidharze (epoxide compounds and epoxy resins)" by A. M. Paquin, - 2153~5 Springer Verlag, Berlin 1958, Chapter IV, and in Lee Neville "Handbook of Epoxy Resins", 1967, Chapter 2, both of which are hereby incorporated by reference.
Epoxides (A1), (Bl), and (C) may be the same or different and are selected from any available compounds, such as described above. Mixtures of several epoxy resins can also be used in each case.
Any desired primary polyoxyalkylene monoamines (A2) or mixtures are useful. Particularly suitable polyoxy-- 10 alkylene monoamines (A2) include the ~-alkoxy-~-2-amino-alkylpolyoxyalkylene, for example, polyoxyalkylene monoamines of the formula Z--C--CH, CH~ -- NH
n 2 X

- in which X is hydrogen a methyl or ethyl radical, Z is a hydrocarbon radical having 1 to 5 carbon atoms and n is an average value of between 2 and 50.
Polyoxyalkylene monoamines in which the aminoalkyl radical is a 2-aminopropyl radical and the alkylene radicals are chosen from ethylene and 1,2-propylene radicals, each of which can form the polyoxyalkylene chain by themselves, as a mixture or in a block structure, are preferably employed.
Polyoxyalkylene monoamines of the formula Z-- C O--CH 2-- C H,~--[ --CH 2--C H--C CH 3~] -- NH

in which Z is a hydrocarbon radical having 1 to 5 carbon atoms, in particular a methyl radical, and, independently of one another, y is 0 to 20 and x is 1 to 41, are preferably employed, and polyoxyalkylene monoamines of the formula 21S309~

Z-- O --CH,-- CH,--C -- CH~ CH-- ~ CH3~] -- NH

in which z is 1 to 20, in particular 9 to 18, are used in particular.
Some selected monoamine block polymers described above having oxyethylene and oxypropylene groups are marketed, for example, by Texaco Chemical Co., Inc. under the trade name Jeffamine~ M series. The Jeffamine~ types M 600 and M 715 may be mentioned as particularly useful.
The polycarboxylic acids (A3) optionally co-used include any known in the art and are preferably long-chain dicarboxylic acids. Examples which may bementioned include aliphatic and cycloaliphatic dicarboxylic acids, the aliphatic radical of which in general contains 1 to 50, preferably 2 to 44, carbon atoms, such as, for example, succinic acid, glutaric acid, adipic acid, suberic acid, azelaic acid, sebacic acid, and dodecanedioic acid. Suitable cycloaliphatic dicarboxylic acids, the cycloaliphatic radical of which usually contains 5 to 12, preferably 6 to 8 carbon atoms include, for example, the various cyclohexanedicarboxylic acid isomers, hexahydrophthalic acid, and tetrahydrophthalic acid.
Dimeric fatty acids which are prepared, for example, from mono- or polyunsaturated naturally occurring or synthetic monobasic aliphatic fatty acids having 16 to 22 carbon atoms, preferably 18 carbon atoms, by known methods, such as, for example, thermal or catalytic polymerization or by copolymerization in the presence of compounds which are capable of polymerization, such as, for example, styrene or homologs and cyclopentadiene, are preferably employed. Dimeric fatty acids having an acid number of 150 to 230 mg of KOH/g are particularly useful.
It is furthermore also useful to employ as component (A3) dicarboxylic acids which contain oxyalkylene, 2 l s3 ~

preferably oxyethylene, groups and which fulfill the formula HOOC-- CH2--C OR~ O--CH2 COOII

in which R10 is a branched or unbranched alkylene radical having 2 to 5, preferably 2 carbon atoms and n is 0 or an integer from 1 to 300, preferably 1 to 50, and in ~ particular 1 to 25. Examples of these compounds include - 3,6-dioxaoctanedioic acid, 3,6,9-trioxaundecanedioic acid, polyglycoldioic acid, having a molecular weight of 400 to 800, preferably about 600 g/mol, or mixtures of such acids. The preparation of these compounds is known (cf., for example, DE-OS 2 936 123 which is incorporated by reference) and is carried out, for example, by oxidation of polyglycols in the presence of catalysts.
The sterically hindered primary amines (B2) may be any desired hindered amines or mixtures thereof, and generally correspond to the formula N H, ~2 in which R1, R2 and R3 in each case independently of one another are a branched or unbranched aliphatic, cycloaliphatic, araliphatic or aromatic hydrocarbon radical each which has l to 30 carbon atoms and each which is optionally substituted by hydroxyl, alkoxy or halogen groups, and in which 25 R2 and R3 in each case independently of one another can also be hydrogen, 21~3095 with the proviso that the amino group is not bonded directly to an aromatic radical, and in the case where R2 and R3 are hydrogen, the remaining radical R1 is one of the following substituents \ R 5 CH CH

\R

\ R

S in which the radicals R4 to R9 in each case independently of one another are a branched or unbranched aliphatic, cycloaliphatic, araliphatic or aromatic hydrocarbon radical each which has 1 to 30 carbon atoms and each which is optionally substituted by hydroxyl, alkoxy or halogen groups; and - 215~9~

R1 and R2 can form an optionally substituted cycloaliphatic ring having up to 8 carbon atoms, and in which R3 is then a hydrogen atom.

Sterically hindered amines (B2) which can be employed for preparation of the 1,2-epoxide compou~ds according to the invention include, for example, t-butylamine (2-methyl-2-aminopropane), 2-methyl-- 2-butylamine, t-alkylamines from the Rohm and Haas Company, such as Primene~ TOA (t-octylamine 1,1,3,3-tetramethylbutylamine), Primene~ 81 R
(t-alkylamines C 12 - C 14), Primene~ JM-T (t-alkylamines C 16 - C 22), 2-amino-2-methyl-1-propanol, 2-amino-2-ethyl-1,3-propanediol, tris(hydroxymethyl)aminomethane, isopropylamine(2-aminopropane),sec-butylamine(2-amino-butane), 2-amino-1-butanol, 3-methyl-2-butylamine, 2-pentylamine,3-pentylamine,cyclopentylamine,4-methyl-2-pentylamine, cyclohexylamine, 2-heptylamine, 3-heptyl-amine, 2-methyl-cyclohexylamine, 4-tert-butylcyclohexyl-amine, 3-amino-2,4-dimethylpentane, 6-methyl-2-heptane-amine, l-phenyl-ethylamine (l-amino-l-phenylethane), l-methyl-3-phenylpropylamine and cyclododecylamine.
2-aminobutane and cyclohexylamine are particularly preferred.
Further amines which are useful include isobutyl-amine (2-methyl-1-propaneamine), 2-methylbutylamine (l-amino-2-methylbutane), isoamylamine (isopentylamine =
l-amino-3-methylbutane), furfurylamine, benzylamine, 4-methoxy-benzylamine, 2-ethylhexylamine and isononyl-amine (mixture of isomeric nonylamines which consists of 3,5,5-trimethylhexylamine to the extent of about 90%), and 2-ethylhexylamine is particularly preferred.
Mixtures of various such sterically hindered monoamines can also be used.

21~3Dg~

The epoxide compounds (B) are in general employed in an amount of 1 to 40%, in particular 1 to lS%, based on the sum of the weights of components (A) and (C).
The ~-imidazolyl-alkanoguanamines (D) employed according to the invention can be any such compound and generally correspond to the formula " R 12 ~ N C
N NA C
C N C

R

in which A is an alkylene radical having 1 to 8 carbon atoms, which can optionally additionally be substituted by alkyl groups, and R11, R12 and R13 in each case 10 independently of one another represent hydrogen or an alkyl or aryl radical each having 1 to 20 carbon atoms.
Examples of suitable compounds include 3-(2'-methyl-imidazolyl)propanoguanamine, 3-(2'-ethyl-4-methyl-imidazolyl)propanoguanamine and 3-(2'-undecyl-15 imidazolyl)propanoguanamine. Mixtures of at least two different ~-imidazolyl-alkanoguanamines are particularly suitable for the invention. Components (D) are preferably employed as a powder having an average particle size of less than 30 ~m.
Latent hardeners (E) which can be employed include all the compounds or mixtures, known for this purpose, and which are generally inert toward the epoxy resin at - room temperature or at elevated temperature, for example, up to 80~C, but rapidly react by crosslinking with the resin as soon as this temperature is exceeded.
Boron trifluoride-amine adducts, particularly tertiary aliphatic amines adducts, for example, can be employed. Dicyandiamide is also suitable and is 21~3~95 preferably employed in finely ground form. Dicyandiamide (cyanoguanidine, Dyhard~ 100 from SKW) is not a curing agent itself at room temperature. It dissociates at higher temperatures and causes curing of the epoxy system f 5 via reactive cleavage products. Other suitable latent hardeners include, for example, aromatic amines, such as, for example, 4,4'- or 3,3'-diaminodiphenylsulfone, guanidines, such as, for example, 1-o-tolyldiguanide, modified polyamines, such as, for example, AnchorX 2014 S
- 10 (Anchor Chemical UK Limited, Manchester), carboxylic acid i hydrazides, such as, for example, adipic acid dihydrazide; isophthalic acid dihydrazide or anthranilic acid hydrazide; triazine derivatives, such as, for example, 2-phenyl-4,6-diamino-s-triazine (benzo-15 guanamine); and melamine.
The curing agents (E) are employed in amounts effective to provide the desired curing and in general are employed in amounts of 0.01 to 50, preferably 1 to 40%, based on the sum of the weights of components (A), (C) and (B) if present. Curing with dicyandiamide is in general carried out in amounts of 0.01 to 20, preferably 0.5 to 15%, based on the sum of the weights of components (A), (C) and if present (B).
Accelerator (D) is added in an amount effective to achieve the desired results and in general added in amounts of 0.01 to 10%, preferably 0.1 to 2%, based on the sum of the weights of components (A), (C) and (B) if present. By addition of the accelerator (D), the amount of dicyandiamide can in general be reduced considerably compared with a non-accelerated system.
During incorporation of the hardener (E) and the accelerator (D), the temperature should be below the reaction temperature of the corresponding resin/hardener system. It may be necessary, thus to cool the reaction mixture during the dispersing operation.
The further optional additives (F) include, for example, flow agents, adhesion promoters, hydrophobizing 21S3~9~

agents, dyestuffs, pigments, reinforcing agents and inert fillers. Any desired additives can be used. They are used in the conventional amounts to achieve the desired properties.
Flow agents which can be employed include, for example, acetals, such as polyvinylformal, polyvinyl-acetal, polyvinylbutyral, polyvinylacetobutyral and the like, polyethyleneglycols and polypropyleneglycols, silicone resins and mixtures of zinc soaps of fatty acids and aromatic carboxylic acids, in particular commercially available products based on polyacrylates. The flow agents can also be added to component (A) in effective amounts such as of 0.1-4% by weight, preferably 0.2-2.0%
by weight.
Silanes, inter alia, can be employed as adhesion promoters and hydrophobizing agents. These can react either with the inorganic substrate or with the organic polymer on the substrate (adhesive, coating composition or the like) to form firm bonds. The mechanical values, in particular after exposure to moisture, can be improved by the improvement in adhesion. Appropriate products are available, for example, under the name DynasylanX from Huls Aktiengesellschaft, Marl and as Silan~ from Degussa AG.
The dyestuffs and pigments can be either inorganic or organic in nature. Examples which may be mentioned are titanium dioxide, zinc oxide, carbon black and conductive carbon black, such as, for example, PrintexX
XE 2 from Degussa AG. The organic dyestuffs and pigments are to be chosen such that they are stable at the curing temperatures and lead to no intolerable shifts in color shade.
Further suitable fillers can have a reinforcing action (for example, fibrous fillers, such as fibers of glass, mineral or textile) or have no substantial influence on the mechanical properties (inert fillers, such as, for example, quartz flour, silicates, chalk, 21~3~9~

gypsum, kaolin, mica, barite and organic fillers, such as, for example, wood flour or polyamide powder).
Thixotropic agents and thickeners which can be used are, for example, Aerosil~ (highly disperse silicon dioxide, ; 5 for example, the types 150, 200, R 202 and R 805 from Degussa), bentonite types (for example, Sylodex~ 24 from Grace) and Bentone~ (NL Chemicals).
The additives and fillers when used are in general incorporated using positive mixers, such as, for example, dissolvers and kneaders. Here also, it may be necessary to avoid premature reaction of the components by cooling the formulated resin/hardener system according to the invention.
The epoxy resin compositions according to the invention may be prepared in any desired manner. For example, they may be prepared by reaction of an epoxy resin (Al) based on a polyhydric phenol with a polyoxy-alkylene monoamine (A2), optionally addition of a further epoxide (C) and subsequent mixing with the latent hardener (E) and at least one ~-imidazolyl-alkano-guanamine (D). A further epoxide-amine adduct of poly-epoxide (Bl) and a sterically hindered amine (B2) can preferably be added to the epoxy resin (A) from the reaction of (Al) and (A2). The epoxide group content which is needed in the uncured resin may be obtained by proper choice of the stoichiometry in components (Al) and (A2), and (Bl) and (B2). In this case, (C) stands for unreacted epoxide compounds of (Al) and (Bl). There may also be added quantities of epoxide compounds which are different from (Al) and (Bl), yet selected from the same group of compounds, after reaction with the amine components (A2) and (B2).
The epoxy resin compositions can be used in coating to coat any desired substrates. Because of their rapid curing, the elastic epoxy resin compositions according to the invention can be employed in all instances where the coated substrate is to be exposed to as little heat as 21S3~

possible. They give elastic coatings and elastic gluings. Examples include coatings and gluings on thermoplastics and multi-layer laminated materials with components of different coefficients of expansion, which - 5 tend to delaminate under prolonged exposure to-heat.
The invention is demonstrated below by examples, which serve to illustrate and not limit the invention.
"Epoxide equivalent" below is to be understood as meaning the molecular weight divided by the average number of epoxide groups per molecule.

EXAMPLES
I. Preparation of the epoxide compounds (component A) Example 1 1260 parts by weight of Jeffamine$ M 1000 are added to 1740 parts by weight of a liquid epoxy resin based on bisphenol A and having an epoxide equivalent (EV) of 183 g/mol in a four-necked flask with a stirrer, thermometer and condenser, under nitrogen. The mixture is then heated to 90C and kept at this temperature for about 5 hours until the EV remains constant. After a subsequent holding time of one hour, the flask is cooled and emptied. The epoxy resin has the following characteristic data:
Epoxide equivalent 417 g/mol Amine number 23.5 mg of KOH/g Viscosity at 25C 7590 mPa.s Example 2 210 parts by weight of Jeffamine$ M 2005 are added to 580 parts by weight of a liquid epoxy resin based on bisphenol A and having an epoxide equivalent (EV) of 183 g/mol in a four-necked glass with a stirrer, thermometer and condenser, under nitrogen. The mixture is then heated to 90C and kept at this temperature for about 2 hours until the EV is constant at 260. 210 parts by weight of Jeffamine$ M 600 are now added and the - 21~3095 reaction mixture is heated further at 90C. After 3 hours, the EV is 427. After a subsequent holding time of one hour, the flask is cooled and emptied. The epoxy resin has the following characteristic data:
Epoxide equivalent 444 g/mol Amine number 25.7 mg of KOH/g Viscosity at 25C 17410 mPa.s II. Preparation of the one-component epoxy mixtures - Dicyandiamide (Dyhard~ 100, SKW Trostberg), as the latent curing agent (E), is dispersed into the epoxide compounds (A) in the course of 15 minutes with a dissolver at 10,000 revolutions/minute. Thereafter, the accelerator (D),3-(2'-methylimidazolyl)propanoguanamine having an average particle size of Zo ~m or, in the comparison examples, 2-methylimidazole (Dyhard~ MI), is stirred in likewise at 10,000 revolutions/minute in the course of 5 to 10 minutes. The Aerosil~ is then incorporated in portions and, depending on the viscosity of the mixture, at 250 to 1200 revolutions/minute.
The one-component epoxy mixtures II.1 to II.6 are prepared in this manner from epoxy resins I.1 and I.2 and as comparison, a liquid epoxy resin having an epoxide equivalent of 183. See Table 1.
In the case of I.1 and I.2, there is still unreacted liquid epoxy resin present in the mixture.

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III. Test methods 1. Storage stability The epoxy resin/hardener mixture is stored at room temperature and tested weekly for an increase in 5 viscosity.

2. Extraction values 2.1 Test sheets Steel sheets of quality ST 1203 30 x 110 mm in size and 0.5 mm thick are degreased with acetone, treated with the release agent Trikote~ 44 NC and fired at 180C for 30 minutes.

2.2 Curing of the one-component epoxy mixtures Test sheets pretreated according to 2.1. are coated with a 20o ,um film of the epoxy resin/hardener mixture and the mixture is cured completely at 240C in a Mathis oven for 60 seconds. After cooling, the film is peeled off.

2.3 Extraction 2 g of the cured film are weighed to the nearest 1 mg in a conical flask, 80 ml of a mixture of ethanol/water 1 + 1 is poured over the film and the flask is left to stand for 7 days. It is shaken briefly once a day. The solution is filtered off from the cured material via a fluted filter and the filtrate is evaporated on a rotary evaporator in a round-bottomed flask at 70C under 30 mbar. The residue is dried to constant weight on a rotary evaporator.

3. Tensile shear strength The tensile shear test specimens are produced from steel sheet of quality ST 1405 of 0.75 mm thickness in accordance with DIN 53 281 Part 2. The strips of steel are glued overlapping over an area of 400 mm2 in the non-degreased state. A defined layer of adhesive of 0.2 mm 21 S~5 is established with spacers of PT~E film. The adhesive is cured completely at 240C in the course of 240-280 seconds. After the test specimens have been cooled, adhesive which has emerged at the side is cut off.

3.1 Neasurement of the tensile shear strength The tensile shear strength of the test specimens prepared according to 3.1. is measured in accordance with DIN 53 283 as the mean of 5 individual values on a tensile tester according to DIN 51 221, Part 2 from Zwick.

4. Peel resistance 4.1 Preparation of the test specimens for measurement of the peel resistance The test specimens are produced from steel sheet of quality ST 1203 of 0.5 mm thickness in accordance with DIN 53 281, Part 2. The strips of steel are degreased with acetone and bent to an angle of 90 with the aid of a vice. The adhesive prepared according to II. is applied in a layer of 0.1 mm to the outer surface of the longer arm using a film drawing unit. The metal strip coated with adhesive in this way is now joined together with another metal strip which has not been coated with adhesive such that a T-shaped test specimen symmetric around the glued joint and having a glued area of 185 x 30 mm results. The adhesive is cured completely at 240C in the course of 240-280 seconds. After cooling, adhesive which has emerged at the side is cut off.

4.2 Measurement of the peel resistance The peel resistance of the test specimens produced according to 4.1. is determined in accordance with DIN 53 282 as the mean of 5 individual values on a tensile tester according to DIN 51 221, Part 3 from Zwick.

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21~3~95 Explanations of the examples Examples II.l and II.3 according to the invention meet the requirement of the common properties:
elasticity of the cured composition, excellent storage stability and low viscosity of the resin/hardener mixture, curing within an extremely short time of about 60 seconds, and optimum resistance of the resulting compositions in ethanol/water.
Comparison Example 6 (which corresponds in principle to JP-5-163331) gives a hard composition with which the high elasticity of the cured material required industrially is not achieved (no measurable peel resistance).
In comparison Examples II.2 and II.4, an imidazole, highly active 2-methylimidazole, is employed as an accelerator according to the prior art, and although relatively low extraction values in comparison with systems containing no accelerator (such as comparison II.5) are achieved, the storage stability of the liquid resin/hardener system is inadequate.
While the invention has been described with reference to certain preferred embodiments, numerous modifications, alterations, and changes to the preferred embodiments are possible without departing from the spirit and scope of the invention.

Claims

1. An elastic epoxy resin composition comprising (A) a compound having at least two 1,2-epoxide groups, which is obtained by reaction of a polyepoxide (A1) having at least two epoxide groups per molecule and a polyoxyalkylene monoamine (A2) and optionally a polycarboxylic acid (A3), (B) optionally a compound having at least two 1,2-epoxide groups, which is obtained by reaction of a polyepoxide (B1) having at least two 1,2-epoxide groups per molecule and a sterically hindered aliphatic monoamine (B2), (C) a 1,2-epoxide compound which is chosen from polyepoxides which differ from (A1) and (B1), and the unreacted components of compounds (A1) or (B1) from the preparation of compounds (A) and (B), (D) an .omega.-imidazolyl-alkanoguanamine, (E) a latent curing agent, and, optionally, (F) further additives.

2. An elastic epoxy resin composition as claimed in claim 1, wherein the ratio of the number of epoxy groups in (A1) to the number of amino groups in (A2) is from 10:1 to 5:4.

3. An elastic epoxy resin composition as claimed in claim 1, wherein the ratio of the number of epoxy groups in (B1) to the number of amino groups in (B2) is from 10:1 to 5:4.

4. An elastic epoxy resin composition as claimed in claim 1, wherein the mass fraction of component (B) in the mass of components (A) and (B) taken together is less than 40 per cent.

5. An elastic epoxy resin composition as claimed in claim 1, wherein the mass fraction of component (C) in the mass of components (A), (B) and (C) taken together is up to 90 per cent.

6. An epoxy resin composition as claimed in claim 1, wherein the polyepoxides (A1), (B1) if present, and (C) are each individually selected from the group consisting of glycidyl ethers (A11) of alcohols and phenols having in each case at least two hydroxyl groups, in each case at least two of the hydroxyl groups being glycidylated; the group consisting of polyepoxides (A12) of polyunsaturated aliphatic or mixed aliphatic/aromatic compounds; and the group consisting of glycidyl esters (A13) of polybasic organic acids.

7. An epoxy resin composition as claimed in claim 1, wherein (A1) comprises a diglycidyl ether of bisphenol A or bisphenol F.

8. An epoxy resin composition as claimed in claim 1, wherein (B1) is present and comprises a polyoxypropylene glycol diglycidyl ether.

9. An epoxy resin composition as claimed in claim 1, wherein the polyoxyalkylene monoamine (A2) is selected from the group consisting of .alpha.-alkoxy-.omega.-2-amino-alkyl-polyoxyalkylenes.

10. An epoxy resin composition as claimed in claim 9, wherein the 2-aminoalkyl radical is a 2-aminopropyl radical and the alkylene radicals in the .alpha.-alkoxy-.omega.-2-aminoalkyl-polyoxyalkylenes are selected from ethylene and 1,2-propylene radicals, each of which can form the polyoxyalkylene chain by themselves, as a mixture, or in a block structure.

11. An epoxy resin composition as claimed in claim 1, wherein (B) is present and the sterically hindered amine (B2) has the formula in which R1, R2 and R3 in each case independently of one another are a branched or unbranched aliphatic, cycloaliphatic, araliphatic, or aromatic hydrocarbon radical, each which has 1 to 30 carbon atoms and each which may be optionally substituted by one or more of hydroxyl, alkoxy, or halogen groups, and in which R2 and R3 in each case independently of one another can also be hydrogen, with the proviso that the amino group is not bonded directly to an aromatic radical, and in the case where R2 and R3 are hydrogen, the remaining radical R1 is one of the following substituents in which the radicals R4 to R9 in each case independently of one another are a branched or unbranched aliphatic, cycloaliphatic, araliphatic or aromatic hydrocarbon radical, each which has 1 to 30 carbon atoms, and each which is optionally substituted by one or more of hydroxyl, alkoxy, or halogen groups; and R1 and R2 can form an optionally substituted cycloaliphatic ring having up to 8 carbon atoms, and in which R3 is then a hydrogen atom.

12. An epoxy resin composition as claimed in claim 1, wherein the polycarboxylic acid (A3) is present and is an aliphatic or cycloaliphatic dicarboxylic acid having a total of 3 to 52 carbon atoms.

13. An epoxy resin composition as claimed in claim 1, wherein the polycarboxylic acid (A3) is selected from the group consisting of dicarboxylic acids of the formula HOOC-CH2-(OR10)-O-CH2-COOH

in which R10 is an alkylene radical having 2 to 5 carbon atoms and n is 0 or an integer from 1 to 300, and from the dimeric fatty acids having an acid number of 10 to 230 mg of KOH/g.

14. An epoxy resin composition as claimed in claim 1, wherein the .omega.-imidazolyl-alkanoguanamine is selected from the group consisting of compounds according to the formula in which A is an alkylene radical having 1 to 8 carbon atoms, which can optionally be substituted by alkyl groups, and R11, R12 and. R13 in each case independently of one another are hydrogen or an alkyl or aryl radical, each having 1 to 20 carbon atoms.

15. An epoxy resin composition as claimed in claim 1, comprising a mixture of at least two different .omega.-imidazolyl-alkanoguanamines.

16. An epoxy resin composition as claimed in claim 1, wherein the latent curing agent (E) is selected from the group consisting of adducts of boron trifluoride and amines and dicyandiamide.

17. An epoxy resin composition as claimed in claim 1, wherein the epoxide compound (B) is employed in an amount of 5 to 35%, based on the sum of the masses of components (A) and (C).

18. A process for the preparation of an elastic epoxy resin composition as claimed in claim 1, which comprises reacting an epoxy resin based on a polyhydric phenol (A1) with a primary polyoxyalkylene monoamine (A2) to give an epoxy-amine adduct, which is then mixed with a latent hardener (E) and at least one .omega.-imidazolyl-alkanoguanamine (D).

19. A process for the preparation of an elastic epoxy resin composition as claimed in claim 1, which comprises reacting an epoxy resin based on a polyhydric phenol (A1) with a primary polyoxyalkylene monoamine (A2) to give an epoxy-amine adduct (A), and mixing this adduct with a further epoxy-amine adduct (B) prepared from an epoxy resin (B1) and a sterically hindered primary amine (B2) and with a latent hardener (E) and at least one .omega.-imidazolyl-alkanoguanamine (D).

20. A process as claimed in claim 18, wherein an epoxide component (C) different from (A1) is added after formation of the epoxy-amine adduct.

21. A process as claimed in claim 19, wherein an epoxide component (C) is added to at least one of the epoxide-amine adducts selected from the group consisting of (A) and (B).

22. An elastic coating comprising an elastic resin composition as claimed in claim 1.

23. An elastic adhesive comprising an elastic epoxy resin composition as claimed in claim 1.

24. A substrate coated with a composition as claimed in claim 1.