DE1117871B - Process for hardening polyepoxides - Google Patents

Description

The invention relates to a method for curing polyepoxides using adducts of Epoxies and polyvalent amino compounds that contain amino hydrogens. The invention is of of particular importance when curing solvent-free paint systems at room temperature.

Solvent-free paints do not contain any volatile substances that are removed from the paint during curing Need to become. One advantage of these systems is that they can be thin in a single operation Layers can be used what e.g. B. important in the manufacture of furnishings is. In such systems the polyepoxide used is (also called epoxy or ethoxylin resin) a liquid low molecular weight epoxy resin, and the curing agent is generally one polyvalent amine, e.g. B. diethylenetriamine (see Lee and Neville, "Epoxy resins", 1957, p. 267).

It is advantageous if solvent-free paint systems do not need to be cured at high temperatures, as the paint is off the painted object could expire. Accordingly, it is desirable to use hardeners that are already at room temperature harden. For this reason, a large number of hardeners are suitable for use in solvent-free Unsuitable for paint systems.

Further disadvantages of some hardeners, such as diethylenetriamine, are tarnishing or cloudiness, the unpleasant odor and toxicity, as well as the appearance of surface defects in the hardened Layers because of the insufficient compatibility of the paint components.

From British patent specification 691543 it is known that some of these disadvantages, e.g. B. the unpleasant odor and cloudiness, due to hardening of Glycidyl polyethers with the reaction product of a glycidyl ether with an excess of a polyamine can be remedied, but the cure speed is too slow.

In the German Auslegeschrift 1 006 152 a method for curing epoxy resins is used of adducts of epoxides and polyvalent aliphatic amines of the triethylenetetramine type and diethylenetriamine. However, the use of these adducts brings that It has the disadvantage that the paints produced with them are considerably cloudy and sweat out. In addition, the curing rate at room temperature is very slow, which is common in many Cases is a very significant disadvantage.

Furthermore, from the German Auslegeschrift 1041688 the use of adducts from aromatic poly processes to harden polyepoxides

Applicant:

Shell International Research
Maatschappij NV, The Hague

Representative: Dr.-Ing. F. Wuesthoff, Dipl.-Ing. G. Pulse and Dipl.-Chem. Dr. rer. nat. E. Frhr. v. Pechmann, patent attorneys, Munich 9, Schweigerstr. 2

Claimed priority:
Netherlands 29 April 1959

Johannes Jacobus Zonsveld

and Geoffrey Robin Edwards, DeIEt (Netherlands), have been named as inventors

amines and monoepoxides known. With these adducts, only very low curing rates are achieved achieved. There is practically no hardening or crosslinking at room temperature, which is common to many Cases is very disadvantageous.

Finally, di & use is-of xylylenediamine Already known for curing epoxy resins from Western Plastics, February 1957, p. 15, it became however, it has been found that this curing agent alone does not produce satisfactorily cured films for solventless films Paints, especially with regard to the occurrence of surface defects.

The above disadvantages are overcome by the invention.

The invention provides a method for hardening Polyepoxides by adducts of epoxies and. having at least three amino hydrogen atoms polyvalent amino compounds, the adduct being an epoxy with di- or Tri- (a-aminomethyl) benzene is used.

It has been found that those of di- or tri- (aaminomethyl) benzene with at least three amino hydrogen atoms, preferably m-xylylenediamine, derived Epoxy adducts are suitable for use as hardeners in solvent-free paint systems particularly suitable. In this way it was found possible to cure them quickly and completely Effect systems at room temperature, with the cured paint layer completely smooth and free from

109 740/085

Surface flaws was. There was no cloudiness and no exudation.

The adduct to be used according to the invention is a reaction product of an epoxide and a di- or Tri- (a-aminomethyl) -benzene with at least three 5 amino hydrogen atoms. The di- or tri- (a-aminomethyl) benzene with at least 3 amino hydrogen atoms has the formula

IO

(CH ₂ NR ₂ ), *

where η is 2 or 6 and R represents a hydrogen atom or an alkyl radical, in particular a methyl radical. R is preferably hydrogen. At least three R should therefore mean hydrogen atoms, but if adducts of monoepoxides, such as butyl glycidyl ether, are used, then at least four R should be hydrogen atoms. The liquid m-xylylenediamine

CH ₃ NH ₃

CH ₂ NH ₂

turned out to be particularly suitable.

The polyepoxides to be hardened according to the invention are preferably made from polyhydric alcohols or Phenols, e.g. B. glycerine, butanetriol, diphenylolpropane, diphenylolmethane, resorcinol and hydroquinone, manufactured glycidyl polyethers. These epoxy resins have more than 1.0 epoxy groups per molecule. Particularly suitable glycidyl polyethers are derived from diphenylol propane. As has already been stated, the invention is particularly, but not exclusively, in normally liquid polyepoxides in solvent-free systems are significant.

In some cases it is desirable to reduce the viscosity of such a system; This can by adding reactive diluents such as monoglycidyl esters and ethers, e.g. B. Phenyl glycidyl ether, allyl glycidyl ether and preferably butyl glycidyl ether, take place. It can also be a liquid glycidyl polyether of a polyhydric alcohol as a reactive diluent for Glycidyl polyethers of polyhydric phenols can be used.

That for the production of the adduct of a di- or tri - («- aminomethyl) -benzene with at least 3 amino hydrogen atoms The epoxy to be used can be different from the polyepoxy to be hardened with this adduct be. Examples of epoxides suitable for adduct formation are butyl glycidyl ether, phenyl glycidyl ether, Glycidyl esters of carboxylic acids, diglycidyl ethers of diphenylolpropane, glycidyl polyethers of glycerine, etc. and mixtures of these epoxies.

The adduct is produced by reacting the amine with the epoxy, which is generally Reaction temperatures of 20 to 150 ° C proved to be suitable. In this case, there is an excess of Amine used, d. That is, there are at least 4, in particular 4 to 25, amino hydrogen atoms per epoxy group available. The order in which the reactants are added is important. By adding the polyepoxide to the amine with stirring, the occurrence of a deficit in the Amine, which could lead to hardening, prevented at any time during the reaction. Possibly can be solvents or other substances, such as accelerators and plasticizers, which are specified below will be present during the adduct formation.

When the adduct is mixed with the polyepoxide, hardening begins. Such amounts of the Polyepoxide and adduct mixed with one another that about 1, generally 0.7 to 1.5 epoxide groups are present per amino hydrogen atom. The polyepoxide is preferably in a low stoichiometric Excess, based on the adduct, used.

Curing at room temperature can be achieved by adding accelerators, e.g. B. triphenyl phosphite, p-Toluenesulfonic acid and its morpholine salts, as well as Compounds containing hydroxyl groups such as phenol, tri- (dimethylaminomethyl) phenol and Salicylic acid.

It was also found that it is advantageous to use one of the known plasticizers or other additives, e.g. B. Urea or melamine-formaldehyde resins, certain alkyd and ketone resins, etc., should be used.

The hardening accelerators and / or plasticizers are used in amounts of up to 20 percent by weight on the polyepoxide to be cured. They can be added to this polyepoxide, but they will preferably added to the adduct either during or after manufacture. There will also be accelerators which can act as hardeners, generally added to the adduct.

In addition to the above ingredients, the polyepoxide mixture to be cured may contain other ingredients, e.g. B. additional Polyepoxy hardeners, e.g. B. polyamide resins, pigments, fillers, fiberglass, coal tar and other bitumens.

As has already been stated, the method according to the invention is of particular importance in Connection with solvent-free paint systems using liquid polyepoxides and Adducts, although the inventive method also z. B. in connection with adhesives, potting resins, Resins and flooring compounds used in the manufacture of laminates can.

example

Production of the adduct used as hardener

Were prepared by heating at 6O ⁰ C with stirring two adducts:

AWAY
18.4 18.4 parts by weight of m-xylylenediamine.

9.2 9.2 parts by weight of a glycidyl polyether of diphenylolpropane with a Content of butyl glycidyl ether with an epoxy equivalent weight of 190 and a viscosity of 7 P. at 25 ° C (hereinafter referred to as glycidyl polyether 1).

2.5 10 parts by weight of phenol.

6 6 parts by weight of a urea-formaldehyde resin.

a) There were 48.3 parts by weight of adduct B with 100 parts by weight of glycidyl polyether 1

mixed properly. This mixture, which was applied as a lacquer (thickness of the layer: 200 μ), cured rapidly at room temperature to form a solid material, leaving the lacquer layer after 2 hours was dry. The paint can be applied using a spray gun with two nozzles, the Components are mixed with one another outside the actual device. This has the advantage with it that the mixture does not harden prematurely. After 10 hours you could apply the layer with your fingernails no longer be damaged, was perfectly smooth and free from haze.

b) For comparison purposes, different amounts of the glycidyl polyether 1 and of the adducts A or B mixed and the properties of the resulting paint layers compared:

Stoichiometric Adduct B: Hardness after Solution relationship Glycidyl 24 hours medium attempt AdductA: polyether persistence
after Glycidyl at 2O ⁰ C * 2 days in polyether 288 Seconds ** 1 110% 268 500 2 100% 110% 244 500 3 90% 100% 264 400 4th 90% 264 400 5 218 600 6th 400

* Measured using the Persoz pendulum. ** After 2 days, methyl ethyl ketone is applied to the layer of the paint film and the number of seconds is determined after which the film can be scratched with the fingernails.

The Persoz hardness was 200 for 24 hours. If the paint was cured at -5 ° C for 1 week, then the Persoz hardness was about 100.

e) For comparison purposes, an attempt was made to harden the glycidyl polyether 1 with m-phenylenediamine and a cycloaliphatic polyamine and with the adducts of these amines. at There was little or no curing (crosslinking) at room temperature, although a solid, however, a crumbly and completely soluble paint film formed. A hardening attempt was also made of the glycidyl polyether 1 carried out with m-xylylenediamine (not in adduct form). In this case it was no intact paint film obtained.

f) To demonstrate the superiority of the m-xylylenediamine adducts Comparative tests were carried out on the adducts of aliphatic amines, such as diethylenetriamine. The same were compared Adducts of m-xylylenediamine and diethylenetriamine, which with equimolar amounts of the same glycidyl polyether were mixed. The paints obtained were on wood and glass in a layer thickness of

25 μ applied and the exudation effect and the Turbidity observed. The haze on the glass plate is in a haze meter based on the ASTM method D 1003-52 based, has been measured.

On wood:
m-xylylenediamine adduct

Diethylenetriamine adduct
30th

on glass:

m-xylylenediamine adduct
Diethylenetriamine adduct

Tests to test the weather resistance for 6 months showed that the paint films 5 and 6 were completely intact, while the paint films 1 to 4 more or less influenced by the weather became.

When a paint film of a Glycidylpolyäther having an epoxy equivalent of 500 (Glycidylpolyäther 2) [melting point of 70 ⁰ C; in the form of a solution having a 50% concentration in organic solvents] and diethylenetriamine, then it is generally impossible to make films larger than 50μ. A 25-μ-Ρϊ1πι had a solvent resistance and hardness that are comparable with the paints produced according to the invention only after at least 7 days.

c) It was made from the glycidyl polyether 1 and an adduct B, in which, however, the phenol by a the same amount by weight of triphenyl phosphite (10 parts by weight) was replaced, a paint film was produced. Even this hardened quickly and had almost the same advantageous properties.

d) Example a) was repeated using adduct B with the difference that also 100 parts by weight of pigment (titanium dioxide) and 10 parts by weight of dioctyl phthalate are incorporated into the mass became. After 3 hours a dry, glossy and completely smooth paint film was formed. To no exudation, little exudation;

clear, cloudy.

35 Results of the turbidity measurement

Diethylenetriamine adduct 32%

m-xylylenediamine adduct 8%

The haze is the mean value of three measurements at three different points on the paint layer.

Claims (3)

PATENT CLAIMS: 1. A process for curing polyepoxides by adducts of epoxies and polyvalent amino compounds containing at least three amino hydrogen atoms, characterized in that an adduct of an epoxide with di- or tri- (a-aminomethyl) benzene is used. 2. Embodiment according to claim 1, characterized in that the polyepoxide with a such amount of the adduct converts that about 0.7 to 1.5 epoxy groups of the polyepoxide each Amino hydrogen atom of the adduct are present. 3. Embodiment according to claim 1 and 2, characterized in that one carries out the reaction with the addition of a hardening accelerator. Publications considered: German Auslegeschriften No. 1 006 152, 1 041 688. © 109 740/585 11.61