CS249440B1 - Process for preparing polyamine hardeners - Google Patents

Abstract

The solution relates to a new type of polyamine hardeners based on reaction products of amines and aldehydes with phenol, or its derivatives. They are used for curing epoxy resins and compositions based on them. The preparation of these hardeners consists in the mutual reaction at a temperature of 20 to 120 DC for 10 to 200 minutes of aliphatic and/or cycloaliphatic amines with a number of carbon atoms of 2 to 18 and nitrogen atoms of 1 to 5 with aldehydes with a number of carbon atoms of 1 to 7 in a molar ratio of 1 : 0.8 to 1.2, after which the reaction water is removed, preferably by distillation, and then the resulting product is subjected to a reaction with phenol or its derivatives at a temperature of 20 to 150 °C for 10 to 200 minutes in a ratio of 0.6 to 1.5 moles of phenol per 1 mole of the starting amine.

Description

The invention relates to a process for the preparation of polyamine hardeners based on the reaction products of amines and aldehydes with phenols or derivatives thereof. These hardeners are used to cure epoxy resins and compositions based thereon.

To cure the epoxy resins, a number of different compounds have generally been proposed, 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, and 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. Nos. 5,102, 400, 5, 098 732 and 5,202, 093; Germany No. 2 6.1 0.9 and Pat. USA ě. 4,007,160.

The assortment of aliphatic and cycloaliphatic amines used can be seen eg in Tab. 44, monograph M. Lidařík et al .: Epoxy resins, SNTL Praha 1983, pp. 44-145.

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

An important group of hardeners are the later used condensates of amines, aldehydes and phenols. They excel in their ability to be used on damp substrates in cold rooms, providing good mechanical properties. The disadvantage of these hardeners, however, is the phenol content of the waste water, especially the distilled water, which disrupts the waste water management. A considerable amount of oxygen is required to break down these impurities.

The above-mentioned drawbacks overcome the present invention, which is directed to a process for preparing polyamine hardeners by reacting amines and aldehydes with phenol or derivatives thereof suitable for curing epoxy resins and compositions based thereon.

SUMMARY OF THE INVENTION The subject of the present invention is to first treat aliphatic or cycloaliphatic amines having carbon numbers of 2 to 18 and nitrogen atoms of 1 to 5 with aldehydes having carbon numbers of from 20 to 20 ° C for 0 to 200 minutes atoms of 1 to 7 in a molar ratio of 1: 0.8 to 1.2. The reaction water formed is preferably removed by distillation and then the product is reacted with phenol or its derivatives at a temperature of 20 to 150 ° C for 10 to 200 minutes in a ratio of 0.6 to 1.5 moles of phenol per mole of starting amine .

The advantage of the present invention lies in particular in the fact that during the hardening process in the reaction of the amine with the aldehyde, water is formed which is immediately removed by distillation, both condensation water and water from the raw materials used, e.g. in the form of an aqueous solution. This means that the effluent leaving does not contain any phenol or derivatives thereof, at this stage no compounds were dosed into the reaction mixture, and thus water management is not disturbed.

Among the amines, aliphatic amines, such as diethylenetriamine, triethylenetetramine, tetraethylenepantamine, dipropylenetriamine, trimethylhexamethylenediamine, etc., or cycloaliphatic amines, e.g. in aqueous solution or as paraformaldehyde, but also acetadehyd, benzylaldehyde and the like. Phenol, cresol, xylenol and nonylphenol are used in particular. In the preparation of the hardener, the first step is preferably by adding 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, plaat concrete, impregnating materials, contact resins for laminates and other products, brushless paints, etc. in a wide range of industrial and other applications. industry.

Example 1

A flask equipped with a reflux condenser and stirrer was charged with 131.2 wt. parts of dipropylene triamine, warm 3e to 60 ° C and add 85.8 wt. parts 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 2 hours. At this time, the reflux condenser was replaced by a descending condenser, and the reaction water and formaldehyde water were distilled off at a temperature of up to 110 ° C. It is then cooled to 50 ° C and 151.4 wt. parts of o-creaol (ratio I: 1.4) and the mixture was allowed to stir at 60 ° C for 120 minutes. The product has an amine number of 510 mg KOH / g and is suitable for construction cements. It can also be used on damp substrates. Epoxy resin of mol. with a weight of 500 with 20% provides with 20 parts by weight of this hardener per 100 wt. resin parts bond strength of 19 MPa, peel strength of 0.8 N-mm ´.

Example 2

A flask equipped with a reflux condenser and stirrer was charged with 156.3 wt. parts by weight of cyclohexylaminopropylamine, heated to 90 ° C, 180.2 wt. parts of a 20% aqueous formaldehyde solution (molar ratio 1: 1.2) and the mixture was allowed to react for 2 hours. Water is then distilled off. 122.16 wt. parts of xylenol. The product is suitable for curing adhesives and sealants. An amount of 30 wt. parts per 100 wt. parts of glue. The amine number of the hardener is 650 mg KOH / 100 g.

Example 3

A flask equipped with a reflux condenser and stirrer was charged with 103.2 wt. parts by weight of diethylantriamine; 84.9% by weight of cyclohexylamine are added at 30 DEG C. over a period of 30 minutes. parts of benzaldehyde and 22 wt. parts of acetaldehyde. The mixture was stirred without heating for 1 hour, then the temperature was raised to 120 ° C and allowed to react for a further 2 hours. Water is then distilled off and cooled to 60 ° C. 94 wt. parts of phenol at a temperature of 60 to 80 ° C, then at the same temperature regime of 230 wt. parts of nonylphenol. Allow to react for 2 hours at 120 to 150 ° C. The hardener is added in an amount of 50 wt. parts per 100 wt. parts of a low molecular weight epoxy resin with an epoxy group content of 0.51 eq / g. After curing, it provides a tough product.

Example 4

103.2 wt. parts of diethylenetriamine, warm to 20 ° C and add 36 wt. parts of paraformaldehyde (molar ratio 1: 1.2).

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 120 minutes, then the temperature was raised to 120 ° C.

After reaching this temperature, the reaction mixture was cooled to 60 ° C. 64.9 wt.

parts of o-cresol (0.6 mole / mole amine ratio) and allowed to stir at 20 ° C for 20 minutes.

The product has an amine number of 690 mg KOH / g. For curing a palm-type low molecular weight epoxy resin containing 0.51 eq. epoxy / 100g, 30 wt. parts per 100 wt. resin parts. After two hours, a tough gel with good water resistance is formed. Blinds made according to ČSN 66 8510 provide a shear strength of 15 MPa, according to ČSN 66 8516 a peel strength of 0.6 N.mm ^-1 .

Example 5

A flask equipped with a condenser and stirrer was charged with 146 wt. 68.6 parts of a 35% aqueous formaldehyde solution (mole ratio of components 1: 0.8) are added over 10 minutes at 80 ° C. After this time, the reaction was quenched by cooling to 50 ° C. 122.2 wt. parts of xylenol, reacted at 60 ° C for 1 hour.

The hardener is reactive, a gelation time with a low molecular weight epoxy resin to which 25 wt. parts per 100 wt. parts of resin is 20 minutes. It can be used to cure a medium molecular epoxy resin with an epoxy group content of 0.20 eq / 100 g in acetone solution. At 190 wt. 10 parts by weight of resin are added. hardener parts. The resin solution (10-20%) is suitable for concrete impregnation. The system is not sensitive to moisture in the concrete.

Claims (1)

SUBJECT OF THE INVENTION A process for preparing polyamine hardeners by reacting amines and aldehydes with phenol or derivatives thereof, suitable for curing epoxy resins and compositions based thereon, characterized in that they are first reacted at 20 to 120 ° C for 10 to 200 minutes with aliphatic or cycloaliphatic amines having 2 to 18 carbon atoms and 1 to 5 nitrogen atoms with aldehydes having 1 to 7 carbon ethers in a molar ratio of 1: 0.8 to 1.2, after which the reaction water is removed, preferably by distillation, and then the resulting product is reacted with phenol or its derivatives at a temperature of 20 to 150 ° C for 10 to 200 minutes in a ratio of 0.6 to 1.5 moles of phenol per mole of starting amine.