Source: http://www.google.com/patents/US5567782?dq=6519629
Timestamp: 2017-11-20 15:51:33
Document Index: 104919095

Matched Legal Cases: ['art 2', 'art 2', 'art 2', 'art 3', 'Application No. 387', 'Application No. 387']

Patent US5567782 - Bonding with polyepoxide-polyoxyalkylenemonoamines product - Google Patents
An epoxy resin composition is disclosed that contains compounds that contain at least two 1,2-epoxide groups. The epoxide group-containing compounds are reaction products of compounds (A1) that contain at least two 1,2-epoxide groups per molecule, compounds (A2) that are polyoxyalkylenemonoamines that...http://www.google.com/patents/US5567782?utm_source=gb-gplus-sharePatent US5567782 - Bonding with polyepoxide-polyoxyalkylenemonoamines product
Publication number US5567782 A
Application number US 08/417,202
Also published as CA2138089A1, DE4342721A1, EP0658584A2, EP0658584A3, EP0658584B1, US5585446
Publication number 08417202, 417202, US 5567782 A, US 5567782A, US-A-5567782, US5567782 A, US5567782A
Inventors Manfred Marten, Bernhard Wehner
Patent Citations (12), Non-Patent Citations (4), Referenced by (8), Classifications (20), Legal Events (4)
Bonding with polyepoxide-polyoxyalkylenemonoamines product
US 5567782 A
1. A method of bonding two materials, comprising the steps of coating a layer of an epoxy resin adhesive composition on a surface of a first material and contacting the coated surface of the first material with a surface of a second material, wherein the epoxy resin composition consists essentially of
(A2) a polyoxyalkylenemonoamine that has a number average molecular weight between 130 and 900, and, optionally, one or both of
(A3) a polyoxyalkylenemonoamine that has a molecular weight of from 900 to 5000, and
(A4) a polycarboxylic acid, and
2. A method as claimed in claim 1, wherein the surface of the second material additionally is coated with a layer of the composition.
3. A method as claimed in claim 1, wherein the two materials are parts of an automobile.
4. A method as claimed in claim 1, wherein the epoxy resin composition additionally consists essentially of at least one additive.
5. A method as claimed in claim 1, wherein the compound (A1) has an epoxide equivalent weight between 150 and 250.
6. A method as claimed in claim 1, wherein polyoxyalkylenemonoamine (A2) has a molecular weight of about 600.
7. A method as claimed in claim 1, wherein polycarboxylic acid (A4) comprises a dicarboxylic acid of the formula
HOOC--CH.sub.2 --[OR].sub.n --O--CH.sub.2 --COOH           (1)
R1 is an alkylene radical that has from 2 to 5 carbon atoms, and
n is 0 or an integer from 1 to 300.
8. A method as claimed in claim 7, wherein polycarboxylic acid (A4) comprises polyglycolic acid having a molecular weight of about 600.
9. A method as claimed in claim 1, wherein the hardener comprises a latent hardener.
10. A method as claimed in claim 9, wherein the latent hardener comprises dicyandiamide.
11. A method as claimed in claim 1, wherein the latent hardener comprises N-aminoethylpiperazine.
12. A method as claimed in claim 9, wherein the latent hardener comprises a mixture of N-aminoethylpiperazine and nonylphenol.
13. A method as claimed in claim 4, wherein the additive comprises an accelerator.
14. A method as claimed in claim 1, wherein polyoxyalkylenemonoamine (A2) comprises a polyoxypropylenemonoamine.
15. A method as claimed in claim 1, wherein polyoxyalkylenemonoamine (A3) comprises a polyoxypropylenemonoamine.
16. A method as claimed in claim 1, wherein the epoxy resin composition is coated on the surface of the first material by one of painting, rolling and deposition as a bead on a substrate.
17. A method as claimed in claim 1, wherein polyoxyalkylenemonoamine (A2) is a compound of the formula
CH.sub.3 --O--CH.sub.2 --CH.sub.2 --[O--CH.sub.2 --CH--(CH.sub.3)].sub.9 --NH.sub.2
18. A method as claimed in claim 1, wherein polyoxyalkylenemonoamine (A2) has the formula
CH.sub.3 --(O--CH.sub.2 --CH.sub.2).sub.y --[O--CH.sub.2 --CH(CH.sub.3)].sub.x --NH.sub.2
where, independently of one another, y is from 0 to 10 and x is from 1 to 41.
19. A method as claimed in claim 1, wherein polyoxyalkylenemonoamine (A3) comprises a compound of the formula
20. A method as claimed in claim 1, wherein polyoxyalkylenemonoamine (A2) has a molecular weight between about 500 and 700.
21. A method as claimed in claim 1, wherein polycarboxylic acid (A4) comprises a dimeric fatty acid that has an acid number between 150 and 230 mg KOH/g.
22. A method as claimed in claim 17, wherein R in formula (1) is an ethylene radical and n is an integer from 1 to 50.
23. A method as claimed in claim 1, comprising from 20 to 80% by weight of component (A2) and, optionally, from 20 to 50% by weight of component (A3) and from 0.1 to 30% by weight of the component (A4), based on component (A1).
This application is a divisional of application Ser. No. 08/355,303, filed Dec. 12, 1994.
The present invention relates to an elastic epoxy resin hardener system. 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, may be cured by means of polyamines, and possess, besides good chemical and solvent resistance, good adhesion to many substrates. The usability of these resin/hardener systems is often limited by insufficient elasticity or flexibility in the cross-linked state. In particular for applications in which temperature-change stresses have to be taken up by a high elasticity of the coating materials, the elasticity of the unmodified standard epoxy resin systems is insufficient. In the adhesives sector, there is a need for epoxy resin systems which are still sufficiently elastic at low temperatures, i.e. below 0° C. In the automobile industry, use is made of epoxy resin adhesives which are only slightly flexible in the cured state. Although the adhesive bonds obtained with these resins have a high tensile shear strength, they easily separate by peeling under a lateral force. It is a known problem that adhesives which allow high tensile shear strengths to be achieved frequently give only a low angle peeling strength.
Vazirani [Adhesives Age, Oct. 1980, pp. 31-35] describes flexible single-component and two-component epoxy resin systems based on polyoxypropylenediamines and polyoxypropylenetriamines. These amines are commercially available from Texaco under the trade name "Jeffamine®". The curing of the single-component system is carried out using dicyandiamide.
EP-B 0 354 498 discloses a reactive melt adhesive which contains a resin component, at least one thermally activatable latent hardener for the resin component and, if desired, accelerators, fillers, thixotropes and further customary additives. The resin component is obtained by reaction of
The resins which are solid at room temperature are ones which for further processing have to be heated to above 50° C. so as to lower the viscosity sufficiently for incorporation of further constituents of the melt adhesive to be made possible. In the reaction of the epoxy resins with the linear polyoxypropylene having amino end groups, a large excess of epoxide groups, based on the amino groups, is required so that the amino groups are completely reacted. A 5-fold to 10-fold excess is typical.
WO 93/00381 describes a further development of EP-B 0 354 498 that has improved low-temperature properties. The amino component comprises linear amino-terminated polyethylene glycols or linear and/or trifunctional amino-terminated polypropylene glycols.
U.S. Pat. No. 4,423,170 discloses water-dilutable epoxy resin compositions which comprise (A) diepoxides that are obtained by reaction of diepoxides and polyoxyalkylenamines that have a molecular weight of from 900 to 2500, and (B) a latent hardener in aqueous medium.
To ensure sufficient water solubility of the system, the polyoxyalkyleneamines have to have high proportions of ethylene oxide. Epoxy resin systems built up using such amines do not give sufficient corrosion resistance when used as adhesives, for example, in the automobile industry.
EP-B 0 109 174 describes an epoxy resin composition that contains (A) a polyepoxide and (B) a hardener, wherein the polyepoxide has been reacted with from 50 to 70% by weight of a polyoxyalkylenemonoamine that has a molecular weight of from 900 to 2000. The resin-hardener mixture described in this document can be used as a flexible adhesive in the form of a single-component or two-component system, has a low viscosity and can therefore be used without addition of solvent. It is disclosed that only one series of adducts, namely those prepared from Jeffamine M-1000, shows a uniformly low viscosity independent of the amine content. In addition, it is pointed out that compositions containing less than 50% of polyoxyalkylenemonoamine have a relatively low flexibility at a high viscosity and compositions containing more than 70% of polyoxyalkylenemonamine have relatively low adhesive strength and decreasing viscosity.
It is an object of the present invention to provide reactive, flexible adhesives which have high peeling strength not only at room temperature but also at low temperatures, e.g. of 0° C. and lower. At the same time, the tensile shear strength values should not be impaired. Sufficient wash-out resistance and good corrosion protection of the cured adhesive system are to be ensured. It is advantageous if the epoxy resins have viscosities which make possible easy processing without requiring additional apparatus.
These and other objects according to the invention are provided by an epoxy resin composition comprising
Preferably, the oxyalkylene groups in (A2) and (A3) are selected from oxypropylene, oxyethylene and their mixtures.
In a particularly preferred embodiment, one or both of polyoxyalkylenemonoamine (A2) and polyoxyalkylene-monoamine (A3) are polyoxypropylenemonoamines.
The present invention further provides a method of bonding two materials, comprising the steps of coating a layer of the inventive composition on a surface of a first material and contacting the coated surface of the first material with a surface of a second material. The surface of the second material additionally may be coated with a layer of the composition in this process. In particular, the two materials may be parts of an automobile.
It has now surprisingly been found that excellent corrosion-resistant flexible adhesive bonds can be achieved by curing of epoxy resins which are obtained by reacting 1,2-epoxides with polyoxyalkylenemonoamines that have molecular weights of below 900.
The present invention accordingly provides epoxy resin compositions comprising
(A1) compounds that contain at least two 1,2-epoxide groups per molecule
(A2) polyoxyalkylenemonoamines that have a molecular weight of from 130 to 900 and, if desired, of
(A3) polyoxyalkylenemonoamines that have a molecular weight of from 900 to 5000 and, if desired, of
(A4) polycarboxylic acids and
Suitable epoxide components (A1) are many compounds known for this purpose which contain on average more than one epoxide group, preferably two epoxide groups, per molecule. These epoxide compounds (epoxy resins) can be either saturated or unsaturated. They can be aliphatic, cycloaliphatic, aromatic or heterocyclic, and may contain hydroxyl groups. They can contain substituents which do not cause any interfering secondary reactions under the mixing or reaction conditions, for example, alkyl or aryl substituents, ether groups and the like. Preferably these compounds are glycidyl ethers which are derived from polyhydric phenols, in particular, bisphenols and novolaks and whose epoxide equivalent weights are between 150 and 500, but in particular between 150 and 250.
Examples of polyhydric phenols which may be mentioned include: resorcinol, hydroquinone, 2,2-bis(4'-hydroxyphenyl)propane (bisphenol A), mixtures of isomers of dihydroxydiphenylmethane (bisphenol F), tetrabromobisphenol A, 4,4'-dihydroxydiphenylcyclohexane, 4,4'-dihydroxy-3,3'-dimethyldiphenylpropane, 4,4'-dihydroxybiphenyl, 4,4'-dihydroxybenzophenone, bis(4'-hydroxyphenyl)-1,1-ethane, bis(4'-hydroxyphenyl)-1,1-isobutane, bis(4'-hydroxy-tert-butylphenyl)-2,2-propane, bis(2-hydroxynaphthyl)methane, 1,5-dihydroxynaphthalene, tris(4-hydroxyphenyl)methane, bis(4-hydroxyphenyl) ether, bis(4-hydroxyphenyl) sulfone, inter alia, and also the chlorination and bromination products of the above mentioned compounds. Very particular preference is given to liquid diglycidyl ethers based on bisphenol A that have an epoxide equivalent weight of from 180 to 190.
In particular cases, small amounts of reactive diluents also can be used in addition to the polyglycidyl ethers. Examples of such diluents include methyl glycidyl ether, butyl glycidyl ether, allyl glycidyl ether, ethylhexyl glycidyl ether, long-chain aliphatic glycidyl ethers such as cetyl glycidyl ether and stearyl glycidyl ether, monoglycidyl ethers of a higher isomeric alcohol mixture, glycidyl ether of a mixture of C12 to C13 alcohols, phenyl glycidyl ether, cresyl glycidyl ether, p-t-butylphenyl glycidyl ether, p-octylphenyl glycidyl ether, p-phenylphenyl glycidyl ether, glycidyl ether of an alkoxylated lauryl alcohol, etc. in amounts of up to 30%, preferably 10-20%, based on polyglycidyl ether.
Further suitable compounds are poly(N-glycidyl) compounds which are obtainable by dehydrohalogenation of the reaction products of epichlorohydrin and amines such as aniline, n-butylamine, bis(4-aminophenyl) methane, m-xylylenediamine or bis (4-methylaminophenyl) methane. However, the poly (N-glycidyl) compounds also include triglycidyl isocyanurate, N,N'-diglycidyl derivatives of cycloalkylene ureas and diglycidyl derivatives of hydantoins, etc.
A comprehensive listing of suitable epoxide compounds is given in the handbook "Epoxidverbindungen und Epoxidharze" by A. M. Paquin, Springer Verlag, Berlin 1958, chapter IV, and in Lee Neville "Handbook of Epoxy Resins", 1967 chapter 2 Furthermore, reference is here made to EP-A 272 595 and 286 933. Mixtures of a plurality of epoxy resins can also be used.
The polyoxyalkylenemonoamines which have been found to be particularly useful for forming the epoxides (A) are compounds of the formula ##STR1## where X is hydrogen, a methyl or ethyl radical, Z is a hydrocarbon radical having from 1 to 5 carbon atoms, and n is an average which lies between 2 and 50.
Preference is given to polyoxyalkylenemonoamines of the formula:
Z--(O--CH.sub.2 --CH.sub.2).sub.y --[O--CH.sub.2 --CH(CH.sub.3)].sub.x --NH.sub.2,
where Z is a hydrocarbon radical having from 1 to 5 carbon atoms, in particular a methyl radical, and, independently of one another, y is from 0 to 10 and x is from 1 to 41. Preferably, one or both of polyoxyalkylenemonoamine (A2) and (A3) have the formula
CH.sub.3 --(O--CH.sub.2 --CH.sub.2).sub.y --[O--CH.sub.2 --CH(CH.sub.3)].sub.x --NH.sub.2,
As component (A2) or (A3), preference is given to using polyoxyalkylenemonoamines of the formula:
Z--O--CH.sub.2 --CH.sub.2 --[O--CH.sub.2 --CH--(CH.sub.3)].sub.z NH.sub.2
where z is from 1 to 15, in particular 9. Preferably, polyoxyalkylenemonoamine (A2) has a molecular weight between about 500 and 700 g/mol.
Some selected representatives of the above-described monoamine block copolymers that contain oxyethylene and oxypropylene groups are sold, for example, by Texaco Chemical Co., Inc. under the trade name ®Jeffamine M series. Particular mention may here be made of the ®Jeffamine grades M 600, M 1000, M 2005 and M 2070.
Preference is given to using dimeric fatty acids which are prepared from monounsaturated or polyunsaturated natural or synthetic monobasic aliphatic fatty acids that have from 16 to 22 carbon atoms, preferably 18 carbon atoms, by known methods such as thermal or catalytic polymerization or by copolymerization in the presence of polymerizable compounds such as styrene or homologs, cyclopentadiene, etc. Particular preference is given to using dimeric fatty acids that have an acid number of from 150 to 230 mg KOH/g.
The components (A4) also can be dicarboxylic acids containing oxyalkylene, preferably oxyethylene groups, and that have the formula:
HOOC--CH.sub.2 --[OR].sub.n --O--CH.sub.2 COOH
where R is a branched or unbranched alkylene radical having from 2 to 5, preferably 2, carbon atoms and n is 0 or an integer from 1 to 300, preferably from 1 to 50 and in particular from 1 to 25. Examples of these compounds include: 3,6-dioxaoctanedioic acid, 3,6,9-trioxaundecanedioic acid, polyglycol dicarboxylic acid that have a molecular weight of about 400, preferably of about 600, or mixtures of these acids. The preparation of these compounds is known (for example DE-A 2 936 123) and is carried out, for example, by oxidation of polyglycols in the presence of catalysts.
The epoxide compounds of the invention (component A) can be prepared by reacting the epoxides (A1) with the polyalkylenemonoamines (A2) and (A3) while stirring and generally while heating until the theoretically calculated epoxide equivalent weight is reached, that is, until all active hydrogens of the polyoxyalkylenemonoamine have reacted with the excess of epoxide groups present. The reaction temperatures are generally kept at from 25° to 200° C., preferably at from 50° to 150° C., in particular at from 80° to 130° C. Depending on the temperature and the epoxides and amines used, the reaction times are generally between a few minutes and a number of hours. In most cases no additional catalysts are required for quantitative reaction of the amines with the epoxides.
In the preparation of the epoxide compounds (A) of the invention, it is also possible to use various epoxides (A1) as a mixture and react them directly with polyoxyalkylenemonoamines (A2) and, if desired, (A3). It is also possible to carry out a targeted, stepwise build-up using various epoxides successively by first reacting an epoxide I (A1) with an excess of the polyoxyalkylenemonoamines, e.g. 2 active amine hydrogens per epoxide equivalent, and, after complete reaction of the epoxide groups of the epoxide I, reacting a further epoxide II (A1) in excess with the active amine hydrogens still available.
Any modification to be carried out using the polycarboxylic acids (A4) is usually carried out by reaction of the epoxide (A1) with the acid component (A4) prior to the reaction with the monoamines (A2) and (A3), but can in principle also be carried out after the epoxide (A1)-amine (A2 and (A3) reaction.
Preferably, the composition comprises from 20 to 80% by weight of component (A2) and, optionally, from 20 to 50% by weight of component (A3) and from 0.1 to 30% by weight of the component (A4), based on component (A1).
The reaction of the polycarboxylic acid (A4) with the epoxide compounds (A1) or the adduct of (A1), (A2) and, if desired, (A3) can be carried out at elevated temperatures without catalysts, but proceeds substantially more quickly and gives much lower residual acid numbers if catalysts are used.
Examples of catalysts which can be used for the targeted and accelerated reaction of the carboxyl groups of the component (A4) and the epoxide groups of the component (A1) or the reaction product of the component (A1) with the components (A2) and (A3) include: sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium carbonate, chromium compounds such as CrCl3, CrO3, chromium acetylacetonate, imidazoles, imidazolines, quaternary ammonium and phosphonium compounds such as benzyltrimethylammonium chloride, tetraethylammonium chloride, tetramethylammonium chloride, benzyltrimethylammonium hydroxide, benzyldodecyldimethylammonium chloride, methyltriphenylphosphonium iodide, triphenyl (2,5-dihydroxyphenyl)phosphonium hydroxide, ethyltriphenylphosphonium acetate, triphenyl-ethylphosphonium bromide and also organic phosphines such as triphenylphosphine, tricyclohexylphosphine, tributylphosphine, cyclohexyloctylphosphine, furthermore aromatic amines such as N,N-dimethylaniline, N,N-diethylaniline, N,N-dimethyl-p-toluidine, N,N-diethyl-p-toluidine and also amines such as triethylamine, tributylamine, benzyldimethylamine, benzyldiethylamine, triethylenediamine, N-methylmorpholine, N-methylpiperidine, N-alkylamines such as n-butylamine and alkanolamines such as diethanolamine, dimethylethanolamine, diethylethanolamine, dibutylethanolamine, triethanolamine, triisopropanolamine, methyldiethanolamine, di(3-phenoxy-2-hydroxypropyl)alkylamines such as di(3-phenoxy-2-hydroxypropyl)-n-butylamine, etc. These catalysts are generally used in amounts of from 0.01 to 5%, preferably from 0.05 to 2%, based on the weights of (A1) to (A4).
The component (B) used can be, for a two-component process, any known amine hardener for 1,2-epoxides. Examples which may be mentioned include: aliphatic amines such as the polyalkylenepolyamines, diethylenetriamine and triethylenetetramine, trimethylhexamethylenediamine, 2-methylpentanediamine (Dytek A), oxyalkylenepolyamines such as polyoxypropylenediamineandpolyoxypropylenetriamine and 1,13-diamino-4,7,10-trioxatridecane, cycloaliphatic amines such as isophoronediamine (3,5,5-tri-methyl-3-aminomethylcyclohexylamine), 4,4'-diaminodicyclohexylmethane, 3,3'-dimethyl-4,4'-diaminodicyclohexylmethane, N-cyclohexyl-1,3-propanediamine, 1,2-diaminocyclohexane, piperazine, N-aminoethylpiperazine, TCD-diamine (3(4), 8(9)-bis(aminomethyl)tricyclo[5.2.1.02,6 ]decane), araliphatic amines, such as xylyenediamines, aromatic amines such as phenylenediamines, 4,4'-diaminodiphenylmethane, etc., adduct hardeners which are the reaction products of epoxide compounds, in particular glycidyl ethers of bisphenol A and F, with excess amine, polyamidoamine hardeners which are obtained by condensation of monocarboxylic and polycarboxylic acids with polyamines, in particular by condensation of dimeric fatty acids with polyalkylenepolyamines, Mannich-base hardeners which are obtained by reaction of monohydric or polyhydric phenols with aldehydes, in particular formaldehyde, and polyamines.
Use of single-component systems is often desired, since the processor does not have to carry out mixing of individual components directly before use of the system, for example, as an adhesive. Single-component systems are obtained by mixing the epoxide component (A) with a latent hardener. Such mixtures generally have a storage stability of a number of weeks or months at room temperature, i.e. the viscosity remains constant or rises only slightly over this period of time. One of the widely used latent hardeners is dicyandiamide. Dicyandiamide (cyanoguanidine, e.g. ®Dyhard 100 SKW) is itself not a hardener at room temperature. It decomposes at elevated temperatures and effects a hardening of the epoxide system via reactive dissociation products. Flexible single-component epoxy resin systems are prepared by dispersion of the latent hardener, for example the dicyandiamide, as component (B) in the flexibilized epoxy resin component (A), if desired together with additives (C) such as, for example, a thixotrope.
The hardeners (B) generally are used in amounts of from 0.01 to 50, preferably from 1 to 40, % by weight, based on the component (A). Curing with dicyandiamide is generally carried out using amounts of from 0.01 to 20, preferably from 0.5 to 15, % by weight, based on the component (A). If desired, an accelerator can be added in an amount of from 0.01 to 10, preferably from 0.1 to 7, % by weight, based on the component (A) (cf. additives (C), accelerator).
During the incorporation of the hardeners (B) and during the addition of any accelerators (cf. additives (C), accelerator), the temperature should be below the reaction temperature of the respective resin/hardener system. It can here become necessary to cool the reaction mixture during the dispersion process.
Using the polyamine hardeners specified for the two-component process, it is possible in principle to cure the components (A) and (B) at room temperature. However, these relatively low temperatures frequently do not give optimum properties of the cured system. For the single-component system using latent hardeners, such as dicyandiamide, an elevated temperature is required in any case for initiating the crosslinking reaction. The curing temperature of the composition of the invention is generally from 5° to 260° C., preferably from 120° to 200° C. The curing time at temperatures of from 120° to 200° C. is generally from 10 to 200 minutes.
The accelerators used, in particular for curing by the two-component process using amine hardeners, can be, for example, phenols and alkylphenols having 1-12 carbon atoms in the alkyl group, cresol, the various xylenols, nonylphenol, polyphenols such as bisphenol A and F, OH-containing aromatic carboxylic acids such as salicylic acid, m-hydroxybenzoic acid, p-hydroxybenzoic acid and tertiary amines such as benzyldimethylamine, 1,3,5-tris(dimethylamino)phenol and the like.
In detail, suitable imidazolines or imidazoles are, for example, the following compounds: 2-methylimidazoline, 2-ethyl-4-methylimidazoline, 2-phenylimidazoline, 2-undecylimidazoline, 2-heptadecylimidazoline, 2-ethylimidazoline, 2-isopropylimidazoline, 2,4-dimethylimidazoline, 2-phenyl-4-methylimidazoline, 2-benzylimidazoline, 2-(o-Tolyl) imidazoline, 2-(p-Tolyl)imidazoline, tetramethylenebisimidazoline, 1,1,3-trimethyl-1,4-tetramethylenebisimidazoline, 1,3,3-trimethyl-1,4-tetramethylenebisimidazoline, 1,1,3-trimethyl-1,4-tetramethylenebis-4-methylimidazoline, 1,2-phenylenebisimidazoline, 1,3-phenylenebisimidazoline, 1,4-phenylenebisimidazoline, 1,4-phenylenebis-4-methylimidazoline. It is also possible to use any desired mixtures of the imidazolines.
Suitable imidazoles are imidazole itself, 1-methylimidazole, 2-methylimidazole, 4-methylimidazole, 5-methylimidazole, 1-ethylimidazole, 2-ethylimidazole, 1-propylimidazole, 2-propylimidazole, 2-isopropylimidazole, 1-butylimidazole, 2-octylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 2-cyclohexylimidazole, 1-phenylimidazole, 2-phenylimidazole, 2,4-dimethylimidazole, 1,2-dimethylimidazole, 4,5-dimethylimidazole, 2-ethyl-4-methylimidazole, 1-ethyl-2-methylimidazole, 1-methyl-2-isopropylimidazole, 4-butyl-5-ethylimidazole, 2-cyclohexyl-4-methylimidazole, 1-benzyl-2-methylimidazole, 2-phenyl-4-methylimidazole, 4,5-diphenylimidazole, 2-ethyl-4-phenylimidazole, 2,4,5-trimethylimidazole, 2,4,5-tricyclohexylimidazole, 1,2,4,5-tetramethylimidazole and benzimidazoles and derivatives thereof. It is also possible to use any desired mixtures of the imidazoles.
Leveling agents which can be used are, for example, acetals such as polyvinylformal, polyvinylacetal, polyvinylbutyral, polyvinylacetobutyral, etc., polyethylene and polypropylene glycols, silicone resins, mixtures of zinc soaps, of fatty acids and aromatic carboxylic acids, in particular commercial products based on polyacrylates. The leveling agents also can be added to the component (A) in amounts of 0.1-4% by weight, preferably 0.2-2.0% by weight.
As coupling agents and hydrophobicizing agents, use can be made of silanes. These can react both with the inorganic substrate and also with the organic polymer (adhesive, coating composition or the like) to form strong bonds. The improved adhesion can improve the mechanical properties, in particular after exposure to moisture. Appropriate products are offered, for example, under the name Dynasylan® from Huls AG or as silanes by Degussa AG.
The dyes and pigments can be either inorganic or organic in nature. Examples which may be mentioned include titanium dioxide, zinc oxide, carbon black, conductivity black such as, for example, ®Printex XE 2 from Degussa AG. The organic dyes and pigments should be stable at the curing temperatures and should not to lead to any unacceptable shift in shade of color.
Suitable fillers are, for example, quartz flour, silicates, chalk, gypsum, kaolin, mica, barite, organic fillers such as, for example, polyamide powder and the like. Thixotropes and thickeners which can be used are, for example, Aerosil® (a finely divided silicon dioxide, e.g. the grades 150, 200, R 202, R 805 from Degussa), bentonite types (e.g. ®Sylodex 24 from Grace) and Bentone (Trademark of NL Chemicals).
The epoxy resin composition of the invention can be used for coating and adhesive bonding of a great variety of materials, for example, metals, light metals, and also nonmetallic materials such as ceramic, glass, leather, rubber, wood, plastic, etc. The materials can be bonded adhesively to the same or other materials.
The application to the substrate is carried out by known methods, for example by painting, rolling and deposition as a bead of adhesive from suitable machines.
I. Preparation of the epoxide compounds (component A)
In a four-neck flask fitted with stirrer, thermometer and condenser, 70 parts by weight of ®Jeffamine M 10001) were added under nitrogen to 100 parts by weight of a liquid epoxy resin based on bisphenol A and having an epoxide equivalent (EV) of 183. The mixture was then heated to 90° C. and kept at this temperature until the EV remained constant (about 5 hours). After a further holding time of 1 hour, the mixture was cooled and the flask was emptied. The epoxy resin had the following properties:
______________________________________Epoxide equivalent   405Amine number         22.4 mg KOH/gViscosity at 25° C.                7500 mPa.s______________________________________
Using a method similar to that of Example 1, 100 parts by weight of the liquid epoxy resin based on bisphenol A and having an EV of 183 was reacted with 43.5 parts by weight of ®Jeffamine M 6002). The epoxy resin had the following properties:
______________________________________Epoxide equivalent   361Amine number         31.8 mg KOH/gViscosity at 25° C.                44260 mPa.s______________________________________
1) ®Jeffamine M 1000 has, according to the manufacturer's leaflet, a molecular weight of 1000 and a PO/EO ratio of 3/19.
2) ®Jeffamine M 600 has, according to the manufacturer's leaflet, a molecular weight of 600 and a PO/EO ratio of 9/1.
Using a method similar to that in Example 1, 100 parts by weight of the liquid epoxy resin based on bisphenol A and having an EV of 183 were reacted with 48.3 parts by weight of ®Jeffamine M 600 and 24.1 parts by weight of ®Jeffamine M 1000. The epoxy resin had the following properties:
______________________________________Epoxide equivalent   525Amine number         36.9 mg KOH/gViscosity at 25° C.                42170 mPa.s______________________________________
In a four-neck flask fitted with stirrer, thermometer and condenser, 5 parts by weight of the dimeric fatty acid Pripol 1004 (C 44 dimeric acid from Unichema International) were added under nitrogen to 95 parts by weight of a liquid epoxy resin based on bisphenol A and having an epoxide equivalent of 183. The reaction mixture was heated to 140° C. and 0.1 part by weight of triethanolamine was added. After 1 hour, the acid number was 0.1 mg KOH/g. The mixture was cooled to room temperature under nitrogen and the flask was emptied. The epoxy resin had the following properties:
______________________________________Acid number          0.1 mg KOH/gEpoxide equivalent   199Viscosity at 25° C.                12100 mPa.s______________________________________
Using a method similar to that in Example 1, 100 parts by weight of the liquid epoxy resin from Example 4 having an EV of 199 were reacted with 36.2 parts by weight of ®Jeffamine M 600. The epoxy resin had the following properties:
______________________________________Epoxide equivalent   366Viscosity at 25° C.                47620 mPa.s______________________________________
Eighty parts by weight of the epoxy resin from Example 5 were mixed with 20 parts by weight of a polyoxypropylene glycol diglycidyl ether (Hoechst Beckopox EP 075). The epoxy resin mixture had an EV of 361.
The epoxy resin component A was heated to 60° C. and the dicyandiamide (Dyhard® 100 SKW Trostberg) was dispersed in this resin for 15 minutes using a dissolver at 10000 revolutions/minute. The ®Aerosil R202 subsequently was added in portions and, depending on the viscosity of the component (A), the mixture of the invention was homogenized at from 250 to 4000 revolutions/minute using the dissolver.
The epoxide compounds (component A) from the Examples I. 1, 2, 3, 5 and 6 were used to make up the adhesive formulations II. 1, 2, 3, 4 and 5 (see Table 1).
TABLE 1______________________________________Composition of the adhesives           1           (Com-Example II      parison) 2      3    4    5______________________________________Epoxy resin component A           1        2      3    5    6from Example IParts by weight 100      100    100  100  100 ® Dyhard 100 Parts by           10       10     10   10   10weight(Dicyandiamide from SKWTrostberg) ® Aerosil R202 (Degussa           4        4      4    4    4AG) Parts by weight______________________________________
The tensile shear test specimens are produced in accordance with DIN 53 281 Part 2 from steel sheet grade ST 1405 having a thickness of 0.75 mm. The steel strips are, without having been degreased, adhesively bonded on an overlapping area of 400 mm2. Spacers of PTFE film are used to obtain a defined adhesive layer of 0.2 mm. The adhesive is cured for 30 minutes at 180° C. After cooling the test specimen, adhesive which has exuded out the side is cut off.
The tensile shear strength of the test specimens made in accordance with III.1. is measured in accordance with DIN 53 283 as the mean of 5 individual values on a tensile tester in accordance with DIN 51 221, Part 2, from Zwick.
The test specimens prepared in accordance with III.1. are, without degreasing, primed twice using a two-component epoxy resin primer. In this procedure, the entire surface including the overlap zone is coated. After each treatment, the coating is dried and cured for 10 minutes at 120° C.
The test sheets prepared in accordance with III.3. are stored in a salt spray test apparatus in accordance with DIN 50 021 for, for example, 500 hours. The test specimens are then dried for 3 hours at room temperature and the tensile shear strength is measured in accordance with III.2. ##EQU1## 5. Preparation of the test specimens for measuring the peeling resistance
The test specimens are produced in accordance with DIN 53 281, Part 2, from steel sheet grade ST 1203 having a thickness of 0.5 mm. The steel strips are degreased with acetone and bent to an angle of 90° using a vice. Using a film drawing apparatus, a layer of 0.1 mm of the adhesive prepared in accordance with II. is applied to the outer surface of the longer shank. The metal strip thus coated with adhesive is then put together with a further metal strip not coated with adhesive to form a T-shaped test specimen which is symmetrical about the adhesive joint and which has an adhesively bonded area of 185×30 mm. The adhesive is cured in 30 minutes at 180° C. After cooling, adhesive exuded out the side is cut off.
The peeling resistance of the test specimens produced in accordance with III.5. is determined in accordance with DIN 53 282 as the mean of 5 individual values on a tensile tester in accordance with DIN 51 221, Part 3, from Zwick.
Tensile sheer strength, peeling resistance and residual strength after a salt spray test are reported in Table 2.
TABLE 2______________________________________     Tensile shear                 Peeling     Residual     strength in resistance in                             strength after     accordance  accordance  salt spray test     with        with        (DIN 50 021)     DIN 53 283  DIN 53 282  after 500Example   N/mm.sup.2  N/mm        hours %______________________________________II.1. (Compari-     16.0        3.7         1.3son)II.2.     16.1        8.5         100.0II.3.     16.1        6.8         54.5II.5.     16.6        7.8         97.6II.6.     16.5        7.2         86.7______________________________________
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U.S. Classification 525/523, 528/111, 525/423, 525/481, 525/526, 156/330, 525/486, 525/533
International Classification C08G59/20, C08G59/40, C08G59/50, C08G59/12, C09J163/00, C08G59/10
Cooperative Classification C09J163/00, C08G59/10, C08G59/12
European Classification C09J163/00, C08G59/10, C08G59/12