CS260730B1 - Hardener for epoxy resins - Google Patents

Abstract

Hardener for epoxy resins based on adducts of polyempolyamines with an average molecular weight of 100 to 310 with low molecular weight diane epoxy resins with an average molecular weight of 340 to 650 in a molar ratio of 2.9 to 12:1, which contains as an accelerator 0.1 to 5% by weight of a compound of formula I, where x y represents the number 1 or 2 and R represents dimethylene or propylene. Unlike other conventional accelerators, the said compounds are not excreted from the cured products. HXN (R—OH)y

Description

The invention relates to a hardener for epoxy resins, and in particular to the problem of developing accelerators from a cured mass.

For many applications, epoxy resins are commonly cured with amine hardeners such as:

diethylenetriamine, dipropylenetriamine, isophorone diamine, trimethylhexamethyldiamine and the like.

Due to the high haziness of these polyamines, air humidity and carbon dioxide are absorbed in the mixing, casting and curing process, thereby degrading the casting surface. According to the prior art, this problem has been solved relatively successfully by modifying polyamines, for example, by precondensing them with alkylene oxides, epoxides or low molecular weight epoxy resins. Although the curing process of the compositions is somewhat accelerated, it is still insufficient for many applications.

Known methods for increasing the cure rate include the use of catalytic amounts of water, polyalcohols, phenolic compounds, carboxylic acids and the like. Most popular is the use of water and phenolic compounds, which show a sufficient effect to accelerate the curing process. However, their disadvantage is that the accelerator is deposited on the surface of the hardened mass, which in many cases is a technical defect. A solution to the problem of the hardening of the hardening accelerator is not described in the available literature.

We have now found a solution to the technical problem of modifying the epoxy resin polyamine addition product by adding 0.1 to 5% by weight. compounds

H _X N (R = OH) _y where x, y ~ 1 to 2

R ~ —CH2CH2— or —CHCH2—

AND

CII3

Addition products are usually prepared by known methods by reacting low molecular weight epoxides of 340 to 650 average molecular weight with 100 to 310 average molecular weight polyamines, in a molar ratio of 1: 2.9 to 12. Most preferred polyamines are:

diethylenetriamine, triethylenetetramine, tetraethylenepentamine, dipropylenetriamine, tripropylenetetramine, tetrapropylenepentamine and other similar polyamines. The polyaddition reaction is usually carried out by adding an epoxy melt to the present polyamines such that the reaction temperature does not exceed 100 degrees Celsius. Among the compounds to be modified according to the invention, the following are preferably used:

monoethanolamine, monoisopropanolamine, diethanolamine or diisopropanol.

The hardener according to the invention not only achieves a substantial increase in the curing speed compared to the unmodified adducts, but the accelerator evacuation is completely avoided since it is involved in the polymer network construction in the hardening process. A favorable side effect is the reduction of surface tension, which is manifested by a homogeneous glossy surface of the casting.

Example 1

To the apparatus consisting of a three-necked Keller flask equipped with a stirrer, a contact thermometer, and a tempered dropper, 12 moles of technical tetrapropylenepentamine of average molecular weight 306 are introduced and a melt of dian epoxy resin of medium molecular weight is added dropwise at 50-60 ° C. mass 628 (1 mol). Cooling with a jet of air ensures that the temperature does not exceed 80 ^{C |} C. After completion of the dropwise addition, the reaction mixture was allowed to react for 60 minutes at 80 ° C, after which 43 g (0.1 pbw of monoisopropanolamine) were added and the mixture was cooled and spun after thorough homogenization. / g and an equivalent weight of 68.1.

100 g of low molecular weight epian resin of mean molecular weight 392 are mixed with 35 g of hardener and allowed to cure at room temperature. The hardened material is homogeneous, glossy, tough, has a non-sticky and defect-free surface.

Example 1 a d 2

413 g (4 moles) of diethylenetriamine and 39.9 g (5 parts by weight) of diethanolamine are introduced into the apparatus described above, at 60 DEG C., 1 mole of 342 diane epoxy resin with an average molecular weight of 342 is added dropwise with stirring. so that the reaction temperature does not exceed 70-75 [deg.] C. The mixture is left to react for 30 to 40 minutes, the product being a viscous liquid having an amine number of 639 mg KOH / g and an equivalent weight of 79.4. 392 is mixed with 40.5 g of hardener and allowed to cure after homogenization The surface of the casting is hard, glossy, free of exudates and surface defects.

The invention can be used for the production and application of hardeners for curing application types of epoxy masses with a large surface area to thickness ratio, especially in the production of poured floors, plastic concrete elements, sealants, gravel and the like.

Claims (1)

before μ Ε τ Hardener for epoxy resins based on polyenpolyamine adducts having an average molecular weight of 100 to 310 with low molecular weight palm epoxy resins of an average molecular weight of 340 to 650 in a molar ratio of 2.9 to 12: 1, characterized in that it contains 0.1 to 5% by weight compounds of formula OF THE INVENTION H _X N (R - OH) _y where x, y - 1 to 2 R = - CH 2 CH 2 - or -CHCH 2 - CH3