CS240881B1 - Process for preparing polyamine hardeners - Google Patents

Abstract

The solution concerns the preparation of a new type of polyamine hardeners for epoxy resins and compositions based on them. These hardeners eliminate or substantially reduce the need to use liquid physiologically harmful reactive diluents of the glycidyl ether type for adjusting the viscosity of the compositions. The essence of the solution lies in the fact that aliphatic and/or cycloaliphatic amines, with a number of carbon atoms of 2 to 18 and nitrogen atoms of 1 to 5, are subjected to reactions at a temperature of 20 to 200 °C for a period of 10 to 200 minutes with aldehydes with a number of carbon atoms of 1 to 7 in a molar ratio of 1 : 0.8 to 1.2 during or after the reaction, the water present is optionally removed, preferably by distillation.

Description

The present invention relates to the preparation of a new type of polyamine hardener for the curing of epoxy resins and compositions based thereon.

To date, a variety of compounds have been proposed for curing epoxy resins, generally containing functional groups capable of reacting with epoxy groups. One of the most important and most widespread types of these hardeners are amino compounds, aliphatic and aromatic, cyclic and linear, monomeric and polymeric, modified and unmodified. The most important of these are aliphatic and cycloaliphatic amines. The properties of the cured resins depend on the particular type of hardener, the curing method, the curing temperature and the possible addition of a curing accelerator. The use of amines or derivatives thereof in general for the curing of epoxy resins and in many cases also for their preparation is subject to a considerable number of older and newer patents, such as the Belgian patent. Nos. 861 056 and 867 589, Japanese Pat. No 51 082400,

No. 098732 and 52 021093, U.S. Pat. Germany No. 2,611,019 and U.S. Pat. No. 4,007,160. The assortment of aliphatic and cycloaliphatic amines used is evident, for example, from Tab. 44, published in monograph M. Lidařík et al .: 'Epoxy resins, SNTL, Prague 1983 on pages 144 and 145. General lack of hardeners

However, the amine-based 240 881 is the curing time and temperature limit for each type of resin resulting from the fact that these hardeners react practically only with the epoxy group, exceptionally with the hydroxyl group.

This drawback is overcome by the present invention, which relates to a process for the preparation of a new type of polyamine hardener for the curing of epoxy resins and compositions based thereon. SUMMARY OF THE INVENTION The present invention is characterized in that aliphatic and / or cycloaliphatic amines having carbon numbers of 2 to 18 and nitrogen atoms of 1 to 5 are reacted at 20 to 120 ° C for 10 to 200 minutes with aldehydes of 1 to 7 carbon atoms. in mol. a ratio of components of 1: 0.8 to 1.2, optionally during or after completion of the reaction, partially or completely remove the water present, preferably by distillation.

The hardeners prepared by the process according to the invention have some advantages over the prior art types. In particular, they are suitable for curing epoxy compositions whose viscosity has been adjusted by ketone-type diluents which are now incorporated into the resin backbone by means of these hardeners. At the same time, there is no need to use liquid glycidyl ethers hitherto applied as reactive diluents or allow for a maximum reduction in their content, which is very important for health reasons because glycidyl ethers have negative physiological properties. Since the reactivity of these new hardeners with reactive diluents varies, both systems that react rapidly at about 0 ° C as well as systems that have a long processing time at room temperature can be prepared. In the case of very reactive mixtures, a considerable amount of heat is released in a short period of time, which further accelerates the curing process. Therefore, such compositions are particularly suitable for outdoor applications;

in cold seasons, eg when gluing lining bricks of cement kilns, cementing floors in the building industry, etc.

240 881

A further advantage of the hardeners obtained according to the invention is their applicability also for compositions applied to wet substrates.

Among the amines, aliphatic amines, such as diethylenetriamine, triethylenetetramine, tetraethylenepentamine, dipropylenetriamine, trimethylhexamethylenediamine, etc., or cycloaliphatic amines, e.g. in aqueous solution, or as paraformaldehyde, but also acetaldehyde, benzaldehyde and the like.

In the preparation of the hardener, it is preferred to add the aldehyde to the polyamine, whether in liquid form (e.g. as an aqueous formaldehyde solution) or in powder form (i.e., paraformaldehyde).

The hardeners prepared by the above process are applicable to various types of epoxy resins and compositions applied as adhesives, sealants, casting materials and flooring, plastic concretes, impregnating materials, contact resins for laminates and other products, solvent-free paints, etc. in a wide range of industries and other industries .

Example 1

103.2 wt. parts of diethylenetriamine, allowed to warm to 20 ° C and 30 wt. parts of paraformaldehyde (molar ratio 1: 1). Due to the exothermic reaction, the temperature of the reaction mixture was gradually raised to 50 ° C and then allowed to react at 70 ° C for a further 140 minutes. The product thus prepared had an amine number of 820 mg KOH / g and a viscosity of 0.8 Pa.s / 20 ° G.

For curing the low molecular weight dian type by mol. weight 400 24 wt. parts of hardener per 100 wt. The workability of the mixture at 20 ° C is epoxy resin used in the proportion of parts of resin. 45 minutes, a solid gel is formed after 90 minutes.

Example 2 240 ββι

A flask equipped with a reflux condenser and stirrer was charged with 103.2 wt. 85.8% by weight of diethylenetriamine and at 40 DEG C. are added over 30 minutes. % of a 35% aqueous formaldehyde solution (1: 1 mole ratio). By exothermic reaction, the mixture is heated to 55-60 ° C and then heated at 60 ° C for a further 2 hours. After this time, the reflux condenser is replaced by a descending condenser and reaction water and formaldehyde water are distilled off at 120 ° C. The resulting product had an amine number of 900 mg KOH / g and a viscosity of 0.12 Pa.s / 20 ° C.

When used to cure an epoxy composition consisting of 75 wt. parts of dian-type epoxy resin of mol. weight 500, 15 wt. parts of dibutyl maleate and 5 wt. 15 parts by weight of di (2-ethylhexyl) maleate; parts of hardener per 100 wt. The pot life at 20 ° C was 50 minutes.

Example 3

A flask equipped with a reflux condenser and stirrer was charged with 146 wt. 68.6% by weight of triethylenetetramine are added at 80 DEG C. over 10 minutes. % by weight of a 35% aqueous formaldehyde solution (molar ratio of components 1: 0.8). After this time, the reaction was quenched by cooling. The product obtained had an amine number of 860 mg KOH / g and a viscosity of 0.2 Pa.s / 20 ° C.

The hardener is used to cure the low molecular weight epoxy resin by mole. weight 400 containing 16% by weight of cresol in a ratio of 20% by weight; parts of hardener per 100 wt. resin parts. The gelation time of the mixture at 20 ° C is 5 minutes.

Example 4

A flask equipped with a reflux condenser and stirrer was charged with 156.3 wt. part of cyclohexylaminopropylamine;

240 881 was heated to 70 ° C, 180.2 wt. of a 20% aqueous solution of formaldehyde (molar ratio of components is 1: 1.2) and the mixture is allowed to react at this temperature for 1 hour. A downstream condenser is then added, water present is distilled up to 120 ° C and the product is tempered. 120 ° C for 1 h.

The hardener obtained had an amine number of 634 mg KOH / g and was used in an amount of 25 wt. parts per 100 wt. % by weight of epoxy resin (mol. weight 400) containing 10 wt. phenol. The gelation time of the mixture at 20 ° C is 20 minutes.

Example 5

A flask equipped with a reflux condenser and stirrer was charged with 131 wt. parts by weight of dipropylene triamine, 10 wt. 84.9% by weight of cyclohexylamine are added at 30 DEG C. over a period of 30 minutes. % benzaldehyde and then 22 wt. parts of acetaldehyde. The mixture was stirred without heating for 1 h, then the temperature was raised to 60 ° C and allowed to react for 2 h.

The hardener is used to cure a composition consisting of 80 wt. parts by weight of epoxy resin (mol. weight 400), 10 wt. parts of cresol and 10 wt. 30 parts by weight of nonylphenol; parts of hardener per 100 wt. parts of the composition.

Curing occurs at 120 ° C in 2 hours.

Claims (1)

SUBJECT OF THE INVENTION 240 881: A process for preparing polyamine hardeners for curing epoxy resins and compositions based thereon, characterized in that aliphatic and / or cycloaliphatic amines having 2 to 18 carbon atoms and 1 to 5 nitrogen atoms are reacted at 20 to 120 ° C for 10 to 200 minutes with aldehydes having a carbon number of 1 to 7 in mol. ratio of components 1: 0.8 to 1.2, optionally during or after the reaction, the water present is partially or completely removed, preferably by distillation.