CA1228950A - Method for producing materials containing epoxy resins - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
The present invention relates to epoxy resin diammonium salt emulsions comprising a liquid epoxy resin, a latent curing agent and an emulsifier. Diamines of formula I or II:
H2N - CH2 - R - NH2 (I) H2N - R - CH2 - R - NH2 (II) wherein R is a substituted alkylene or a cycloalkylene residue with 6 to 9 C atoms or an aralkylene residue with 7 to 9 C atoms, are neturalized with an acid consisting of or containing oxalic acid and are used as the latent curing agent, while C8- to C14-alcohols and/or adducts thereof with up to 10 ethylene-oxide groups are used as the emulsifier. The emulsions of the present invention are useful in epoxy resin mortars or epoxy resin cement mortars and for sealing concrete surfaces to improve the water retention capacity.

Description

X28~ 23443-2~0 The present invention relates to epoxy resin diammonium salt emulsions comprising a liquid epoxy resin, a latent curing agent and an emulsifier. Epoxy resins have many uses in the con-struction field (cf., for example, B.H. S~ECHTLING, "Bauen mit KunststoEfen", Carl-Hanser Verlag, Munich 1973). In addition to pure epoxy resin mortars used for coatings and primers, for example, there are many interesting applications in the construc-tion field for epoxy resin cement mortars because of their good adhesion, their good shrinkage behaviour and their ability to retain water.
An essential pre-requisite for the processing of epoxy resins i5 that the resin and the curing agent react completely with each other, within a reasonable time, under the a-tmospheric conditions at the site.
A mixture of bonding agen-ts is described in Gérman Offenlegungsschrift 28 40 874 and consists of a hydraulic binder, an epoxy resin (the adduct oE a polyamine and an epoxy compound), water and, if necessary, reactive diluents, pigments and other auxiliary substances. This mixture is particularly suitable for restoring damaged reinforced-concrete parts because the use of a primer, to provide protection against corrosion, is unnecessary with this mixture.
A disadvantage of this two-component system is that, due to its limited stability, it must be prepared at the building site and used within a relatively short time (about half an hour). The hardener : epoxy resin ratio is known to be of critical impor-tance. Thus, the method cited, which requires rapid, very careful ~,~
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~2~89S~) and thorough mixing if the quality is not to suffer has practicaldisadvantages.
As described in United States Patent 3,926/886, it is better to start with an epoxy resin diammonium-acetate or -formate emulsion consisting of a liquid epoxy resin, water and a substi-tuted diammonium salt and to effect curing in the presence of cement.
In the method described in United States Patent 3,926,886, the diammonium salt has two functions to perform.
Firstly, it releases the basic diamine after reacting with the alkaline-reacting cement, the diamine then curing the epoxy resin;
secondly, it fulfills the function of an emulsifier. However, the stability of this emulsion is not assured, especially if the pro-cess must be carried out under extreme atmospheric conditions. It is therefore already proposed, in United States Patent 3,926,886, to add to the mixture up to 15% of a commercially available emul-siEier, but even after this, the stability of the emulsion is a critical factor.
another unsatisfactory feature is that the amine compo-nents used must be specific diamines containing ether groups, ofthe Eormula: -R1 - O - R2 - NH - R3 - NH2, where R1 represents an alkyl residue with at least 8 carbon atoms and R2 and R3 are lower alkyl residues with 2 to 4 carbon atoms.
It is, however, desirable to be able to use more readily available diamines for the production of emulsions. In contrast to the diamines of United States Patent 3,926,886, most of the readily

- 2 -~ZZ8950 available diamines are miscible with water in any proportion.
The formates and acetates thereof cannot be emulsified with con-ventional emulsifiers, such as fatty alcohol ethoxylates, alkyl sulphonates or alkyl phosphoric-acid semi-esters. On the other hand, only homogeneous, stable emulsions are capable of ensuring cold-curing of uniform quality of the liquid epoxy compounds used.
It is therefore a purpose of the invention to develop formulations which will make it possible to produce, with diamines 1 n suitable for curing epoxy resins and which themselves have no emulsifying action, stable aqueous epoxy-resin diammonium-salt emulsions, useful in the construction field.
Thus, in accordance with an aspect of the present invention, there is provided an epoxy resin diammonium salt emulsion compris-ing a liquid epoxy resin, a latent curing agent, an emulsifier and water, wherein:
a) the emulsifier is a primary aliphatic alcohol of 8 to 14 carbon atoms or its adduct with up to 10 ethylene-oxide groups;
and b) the latent curing agent is a reaction product obtained by complete neutralization with an acid consisting of or containing oxalic acid of a diamine of the formula I or II;
H2N - CH2 - R - NH2 (I) H2N - R - CH2 - R - NH2 (II) wherein R is selected from the group consisting of a substituted alkylene, a cycloalkylene residue with 6 to 9 carbon atoms and an aralkylene residue with 7 to 9 carbon atoms.

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In accordance with another aspect of the present invention there is provided a method for producing an epoxy resin diammonium salt emulsion described above which comprises:
a) adding sufficient acid to an aqueous solution of the diamine to neutralize the solution, b) adding khe emulsifier and c) adding the liquid epoxy resin.
In accordance with a further aspect of the invention, there is provided a method for sealing fresh concrete surfaces for improving the water-retaining ability of the concrete, which comprises coating the surface with the epoxy-resin diammonium-salt emulsion.
In accordance with a further aspect of the present invention, there is provided an epoxy resin cement mortar mixture comprising the epoxy resin diammonium salt emulsion and cement mortar. In accordance with a still further aspect of the present invention, there is provided with an epoxy resin mortar compris-ing the epoxy resin diammonium salt emulsion and a hardening mixture containing an alkaline-reacting substance. The amount of the epoxy resin diammonium salt emulsion in the epoxy resin cement mortar mixture or in the epoxy resin mortar is such that the epoxy resin cures under atmospheric conditions, preferably 10 to 30~ by weight based on the mortar or the hardening mixture.
Within the scope of this application, emulsions mean not only the two-phase systems produced by dispersion of one liquid phase in another liquid phase, but also those systems in which a solid phase is dispersed in a liquid phase, and all ~Z~39~;~

transitions of these two systems.
Thus, the amine component is not to react, us described for example in EP-Al-00-43 463, with epoxy resins or with adducts - 4a -, ::

~Z~3g50 which are rendered water-soluble and dispersible by addition of acid, at an elevated temperature. Instead, an emulsion is to be produced from a diammonium salt and an epoxy resin, in which the curing process is initiated after the addition of an alkaline-reacting substance.
According to the present invention, the emulsions may be used in epoxy resin mortars and also in epoxy resin cement mor-tars. They are also suitable for sealing fresh concrete surfaces for the purpose of improving the water-retaining ability of the concrete.
Diamines which are components of the latent curing agent are of formula I or II:
H2N - CH2 - R - NH2 (I) 2N - R - CH2 - R - NH2 (II) wherein R is a substituted alkylene or a cycloalkylene residue with 6 to 9 carbon atoms or an aralkylene residue with 7 to 9 carbon atoms. Particularly suitable are tolylene residues and alkylene and cyclohexylene residues substituted by one to three methyl groups. It is preferable to use 2,2,4-trimethylhexamethyl-ene diamine (TMD), xylyl-diamines, or diamines containing one or two cyclohexane rings, for example 3-aminomethyl-3,5,5-trimethyl-cyclohexylamine (isophorone-diamine, IPD) or 4,4'-diamine-3,3'-dimethyldicyclohexylmethane.
Up to 25% by weight of the oxalic acid may be replaced by acetic acid. The oxalic acid may also be replaced by aliphatc dicarboxylic acids with 3 to 6 carbon atoms or by isomers of phthalic acid, but the acid mixture must contain at least 40% by weight of oxalic acid. Aliphatic dicarboxylic acids, for example malonic acid or adipic acid, unsaturated acids, for example fumar-ic acid, or acids containing hydroxyl groups, for example tartaric acid, can be used.
IJinear primary alcohols with to 14 carbon atoms, and mixtures thereof, are suitable as the emulsifiers. Also suitable are adducts of these alcohols with up to 10 ethylene-oxide groups.
lauryl alcohol is particularly preferred. If necessary, the sta-bility of the emulsions can be improved by addition of lauric acid. Addition of from 10 to 25~ of emulsifiers, in relation to the amount of epoxy resin used, have been found to be satisfac-tory.
Liquid epoxy-compounds suitable for cold-curing are mainly reaction products of epichlorhydrin or glycidol and 2,2-bis(4-hydroxyphenyl)alkanes. The precise chemical structure of commercially obtainable epoxy resins, for example EUREPOX* by Schering, Berlin or XUTAPOX* VE 2913 by Bakelite GmbH, Duisburg, is unknown.
mulsions are produced by preparing an aqueous solution of the diamine. The amount of diamine is governed by data from the epoxy resin manufacturer, for example the epoxy value of the epoxy resin used or the ratio of the mixture of resin and curing agent. The most satisfactory amount of water for an emulsion depends mainly upon the type of diamine. In the case of diamines with a relatively small number of carbon atoms for example 7, *Trade Mark

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less water is needed than for diamines with a larger number of carbon atoms, for example 12. The optimal amount may be easily determined in comparative test by varying the amount of water between 30 and 130% of the amount of epoxy resin used.
Enough acid is then added to the aqueous solution of diamine for complete neutralization. If the reaction heat is considerable, it is desirable to cool the reaction mixture. The emulsifier is then stirred into the solution which is at room temperature. The epoxy resin is then slowly added to the mixture, which is again at room temperature, with rapid stirring. Stirring is continued for 0.5 to 1.0 hours after all of the epoxy resin has been added. In this way, emulsions are obtained which are stable at a room temperature for months. If phase separation occurs, the mixtures may be rapidly homogenized again by renewed stirring.
The invention is further illustrated in the following examples.
a) Production of emulsions.
(Amounts of oxalic acid always relate to the dihy-drate).
Example 1.
105 parts by weight of water and 28.2 parts by weight of isophoronediamine (IPD) were placed in a flat-bottomed flask having a magnetic stirrer. 10.2 parts by weight of oxalic acid,

4.5 parts by weight of acetic acid, and 7.5 parts by weight of phthalic acid were added to this solution. After the reaction mixture had cooled to room temperature, 6.0 parts by weight of lauryl alcohol and 17.4 parts by weight of luric acid, in por-~2;~:~950 tions, were stirred into the mixture. Thereafter, 120 parts by weight of epoxy resin RUTAPOX* VE 2913 were slowly added to the mixture with rapid stirring (at about 1,000 r.p.m.). Stirring was continued, at the same r.p.m., for another hour. This produced a low-viscosity emulsion which showed no change after two months.
Comparison example A.
The procedure was as in Example 1, but in this case neutralization of the diamine was effected entirely with 21.6 parts by weight of acetic acid. The emulsion obtained kroke down after a few mintutes.
Comparison example B.
The procedure was as in Example 1, but in this case neutralization of the diamine was effected entirely with 16.2 parts by weight oE formic acid. The emulsion obtained broke down after a few minutes.
Example 2.
A stable, low viscosity emulsion was produced, as des-cribed in Example 1, from 90 parts by weight of water, 28.2 parts by weight of IPD, 19.8 parts by weight of oxalic acid, 3 parts by weight of tartaric acid, 12 parts by weight of lauryl alcohol J and 120 parts by weight of epoxy resin RUTAPOX* VE 2913. The slight segregation arising after three months of storage was eliminated by stirring the mixture.
Example 3.
A stable, low viscosity emulsion was produced, as * Trade Mark o described in Example 1, from 15 parts by weight of water, 4.4 parts by weight of 2,2,4-trimethylhexamethylene-diamine (TED), 3.5 parts by weight of oxalic acid, 2.0 parts by weight of lauryl alcohol, and 20 parts by weight of epoxy resin RUTAPOX* VE 2913.
Example 4.
A stable, medium viscosity emulsion was produced, as described in Example 1, from 20 parts by weight of water, 6.6 parts by weight of 4,4'-diamino-3,3'-diemthyldicyclohexyl-methane, - 3.8 parts by weight of oxalic acid, 2.0 parts by weight of lauryl alcohol, and 20 parts by weight of epoxy resin ~UTAPOX* VE 2913.
Example 5.
A stable emulsion was produced, as described in Example 1, from 10 parts by weight of water, 3.8 parts by weight of xylylene~diamine (a mixture of isomers), 3.6 parts by weight of oxalic acid, 2.0 parts by weight of lauryl alcohol, 2.0 parts by weight of lauric acid, and 20 parts by weight of RUTAPOX * VE
2913.
Example 6.
A low viscosity emulsion was produced, as described in Example 1, from 40 parts by weight of water, 9.4 parts by weight of IPD, 3.2 parts by weight of fumaric acid, 3.5 parts by weight of oxalic acid, 4.0 parts by weight of lauryl alcohol, 4.0 parts by weight of lauric acid, and 40 parts by weight of epoxy resin R~TAPOX* VE 2913.

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_ g _ ~8g~0 Example 7.
A low viscosity emulsion was produced, as described in Example 1, from 35 parts by weight of water, 9.4 parts by weight of IPD, 3O5 parts by weight of oxalic acid, 4.1 parts by weight of adipic acid, 2.0 parts by weight of lauryl alcohol, 2.0 parts by eight of lauric acid, and 40 parts by weight of epoxy resin RUT~POX* VE 2913.
Example 8.
A low viscosity emulsion was produced, as described in Example 1, from 35 parts by weight of water, 9.4 parts by weight of IPD, 3.5 parts by weight of oxalic acid, 2.9 parts by weight of malonic acid, 2.0 parts by weight of lauryl alcohol, 2.0 parts by weight of lauric acid, and 40 parts by weight of epoxy resin RUTAPOX* VE 2913.
Example 9.
A low viscosity emulsion was produced, as described in Example 1, from 35 parts by weight oE water, 9.4 parts by weight of IPD, 1.5 parts by weight of acetic acid, 2.5 parts by weight of phthalic acid, 3.5 parts by weight of oxalic acid, 2.0 parts by weight oE lauryltriglycol, 2.0 parts by lauric acid, and 40 parts by weight of epoxy resin RUTAPOX* VE 2913.
Example 10.
A low viscosity emulsion was produced, as described in Example 1, from 15 parts by weight of water, 4.7 parts by weight of IPD, 0.5 parts by weight of tartaric acid, 3.3 parts by weight of oxalic acid, 2.0 parts by weight of lauryl alcohol, 0.5 parts * Trade Mark ~:28950 by weight of a mixture of dodecyl- and tetradecyl alcohol (ALFOL*
12/14) which had been reacted with 9 moles of ethylene-oxide, and 20 parts by weight of epoxy resin RUTAPOX* VE 2913.
Example 11.
A medium viscosity emulsion was produced, as described in Example 1, from 12 parts by weight of water, 4.7 parts by weight of IPD, 0.5 parts by weight of tartaric acid, 3.3 parts by weight of oxalic acid, 2.0 parts by weight of lauryl triglycol, and 20 parts by weight of epoxy resin RUTAPOX* VE 2913.
10 Example 12.
A stable emulsion was produced, as described in Example 1, from 10 parts by weight of water, 3.5 parts by weight of oxalic acid, 4.7 parts by weight of isophorone-diamine, 1.5 parts by weight of 2-ethylhexanol, and 20 parts by weight of epoxy resin RUTAPOX* VE 2g13.
b) Production of epoxy resin cement mortars.
Example 13.
For the purpose of producing an epoxy resin cement mortar, 100 parts by weight of Portland cement 35F were mixed with 20 45 parts by weight of water, 20 parts by weight of the emulsion described in Example 1, and 485 parts by weight of filler (60 parts by weight of EFA filler, 170 parts by weight of sand HSE
2/3 mm, 170 parts by weight of sand 0/1 mm, 85 parts by weight of sand 1/3 mm) (as in DIN 1164). Test specimens prepared from this mixture were subjected to seven days of storage in a humid * Trade Mark ~LZ;~895~

atmosphere and 21 days of storage at room temperature. Proper-ties, measured in accordance with DIN 1164, amounted to 53.5 N/mm2 compressive strength and 8.67 N/mm2 tensile bending strength.
Example 14.
As described in Example 13, the mortar was produced from 100 parts by weight of Portland cement 35F with 60 parts by weight of water, 23.4 parts by weight of the emulsion from Example 2, and 485 parts by weight of filler. The properties of the test speci-mens, measured in accordance with DIN 1164, amounted to 43.8 N/mm2 compressive strength and 8.88 N/mm2 tensile bending strength.
c) Production of epoxy-resin mortars.
Example 15.
40 parts by weight of 0/1 mm sand were mixed with 15 parts by weight of the emulsion described in Example 1. 1.5 parts by weight of a 50% caustic soda solution were incorporated in the mass obtained producing a`homogeneous mortar capable of flowing which cured to a solid, tack-free mass within 24 hours at a temperature of 23C.
Example 16.
An epoxy resin mortar was produced, as described in Example 15, from 40 parts by weight of 0/1 mm sand, 15 parts by weight of the emulsion described in Example 1, and 0.65 parts by weight of calcium hydroxide.
Example 17.
An epoxy resin mortar was produced, as described in Example 15, from 40 parts by weight of 0/1 mm sand, 10 parts, by weight of the emulsion described in Example 2, and 1 part by Z289~

weight o:E a 50% caustic soda solution.
d) Sealing fresh concrete surfaces Example 18 -The surface of a fresh concrete test piece with a bulk density of 2,380 kg/m3 (made from Portland cement 35F, water-cement value 0.55 and ac3ditives) was coated with the emulsion described in Example 1 (169 g/m2). After six weeks of room storage, the bulk-density of the test piece was 2,292 kg/m3. In the case of the reference test piece (with the same fresh bulk density of 2t380 kg/m3), the surface of which remained untreated, the bulk density after six weeks storage under the same conditions was 2,262 kg/m3.

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Claims (17)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. An epoxy resin diammonium salt emulsion comprising a liquid epoxy resin, a latent curing agent, an emulsifier and water in an amount of 30 to 130% by weight based on the epoxy resin, wherein:
a) the emulsifier is a primary aliphatic alcohol of 8 to 14 carbon atoms or its adduct with up to 10 ethylene-oxide groups; and b) the latent curing agent is a reaction product obtained by compelte neutralization, with an acid consisting of or containing at least 40% by weight of oxalic acid of a diamine of the formula I or II:
H2N - CH2 - R - NH2 (I) H2N - R - CH2 - R - NH2 (II) wherein R is selected from the group consisting of a substituted alkylene, a cycloalkylene residue with 6 to 9 carbon atoms and an aralkylene residue with 7 to 9 carbon atoms.

2. An epoxy-resin diammonium-salt emulsion according to claim 1, wherein the emulsifier also contains lauric acid.

3. An epoxy-resin diammonium salt emulsion according to claim 1 or 2, wherein the acid contains up to 25% of acetic acid.

4. An epoxy-resin diammonium-salt emulsion according to claim 1 or 2, wherein the acid contains up to 60% of an acid selected from the group consisting of dicarboxylic acid with 3 to 6 carbon atoms which is unsubstituted or is substituted with hydroxyl groups and an isomer of phthalic acid.

5. An epoxy-resin diammonium salt emulsion according to claim 1 or 2, which contains 10 to 25% by weight of the emulsifier based on the epoxy resin.

6. An epoxy-resin diammonium-salt emulsion according to claim 1, or 2, wherein the diamine of the formula (I) or (II) is 2,2,4-trimethylhexamethylenediamine, a xylyldiamine, 3-amino-methyl-3,5,5-trimethylcyclohexylamine, 4,4'-diamino-3,3'-dimethyl-dicyclohexylamine or a mixture thereof.

7. An epoxy-resin diammonium-salt emulsion according to claim 1 or 2, wherein the liquid epoxy resin is a reaction product of epichlorhydrin or glycidol with a 2,2-bis(4-hydroxyphenyl)-alkane.

8. An epoxy-reisn diammonium-salt emulsion according to claim 1 or 2, wherein the amount of the emulsifier is 10 to 25% by weight based on the epoxy resin; the diamine of the formula (I) or (II) is 2,2,4-trimethylhexamethylenediamine, a xylyldiamine, 3-aminomethyl-3,5,5-trimethylcyclohexylamine, 4,4'-diamino-3,3'-di-methyldicyclohexylamine or a mixture thereof; and wherein the liquid epoxy resin is a reaction product of epichlorhydrin or glycidol with a 2,2-bis(4-hydroxyphenyl)alkane.

9. A method for producing an epoxy resin diammonium salt emulsion according to claim 1 which comprises:
a) adding a sufficient amount of the acid to an aqueous solution of the diamine to neutralize the solution, b) adding the emulsifier, and c) adding the liquid epoxy resin,

10. An epoxy resin cement mortar comprising the epoxy resin diammonium salt emulsion according to claim 1 and cement mortar, wherein the amount of the epoxy resin diammonium salt emulsion is such that the epoxy resin cures under atmospheric conditions.

11. An epoxy resin mortar comprising the epoxy resin diammonium salt emulsion according to claim 1 and a hardening mixture containing an alkaline reacting substance, wherein the amount of the epoxy resin diammonium salt emulsion is such that the epoxy resin cures under atmospheric conditions.

12. An epoxy resin mortar according to claim 11, which further comprises a mineral filler.

13. An epoxy resin mortar according to claim 12, wherein the amount of the epoxy resin diammonium salt emulsion is 10 to 30% by weight based on the hardening mixture.

14. An epoxy resin cement mortar according to claim 10, wherein the cement mortar comprises Portland cement, a filler and water

15. An epoxy resin cement mortar according to claim 14, wherein the amount of the epoxy resin diammonium salt emulsion is 10 to 30% by weight based on the cement mortar.

16. An epoxy resin mortar according to claim 11, 12 or 13, wherein the hardening mixture comprises sand, water and an alkaline substance selected from the group consisting of caustic soda and calcium hydroxide.

17. A method for sealing fresh concrete surfaces for improving the water-retaining ability of the concrete, which method comprises coating the surface with the epoxy resin diammonium salt emulsion according to claim 1.