CS218373B1 - Tough mass containing secondary amine groups - Google Patents

Abstract

The invention relates to a tough epoxy resin-based material having improved toughness and resistance to rapid temperature changes. The material according to the invention comprises 5 to 50 parts by weight of acrylic acid alkyl esters and 70 to 95 parts by weight of epoxy resin, said mixture being cured with diethylenetriamine or dipropylenetriamine in an amount of 103 to 150% of theory, based on the content of epoxy and acrylic groups.

Description

The invention relates to a tough material containing secondary amine groups, which can be prepared by reacting modified epoxy resins with polyamines.

Epoxy resins, modified esters of acrylic acid, are increasingly used in various industrial sectors. This is made possible by the relatively very favorable processing parameters of these modifiers, especially their low viscosity, excellent reactivity, relatively low toxicity - and the like. According to the known state of the art, modifiers of epoxy resins and acrylates are cured with a theoretical amount of aliphatic or cycloaliphatic polyamines. In addition to the favorable properties of the cured modifiers, one can also observe unwelcome phenomena, such as relatively high embrittlement, significant internal stress and a tendency to crack formation. The solution to these shortcomings has not yet been described in the available literature.

It has now been found that these shortcomings are eliminated by a tough material according to the invention, which can be prepared by curing a mixture consisting of - 50 parts by weight of alkyl esters of acrylic acid with 3 to 10 carbon atoms in the alkyl and - 95 parts by weight of epoxy resin with an average molecular weight of 312 - 700, diethylenetriamine and/or dipropylenetriamine in an amount of 103 to 150% by weight of theory, based on the content of epoxy and acrylic groups.

Compared to previously known materials, cured with stoichiometric or substoichiometric amounts of polyamines, the materials are

those according to the invention substantially more tenacious, says 9.90 g/100 g modifier. 'Quantity cured material parameters CHILDREN tensile strength elasticity (%) impact strength (% theory) (MPa) (J/ ^cm2 ) avg. max. avg. max. average max. 100 22.4 22.9 5.3 6' 47.5 48.1 105 33.7 35.7 7.3 12 i 55.6 128.3 110 46.5 47.9 8.6 11 80.6 over 150 115 43.8 46.0 9.8 13 ; 46.1 48.0 120 42.6 45.0 .15 15 22.0 31.0 130 30.7 31.8 30 31 20.0 20.0 140 21.2 25.3 64 72 14.3 21.0 150 9.8 10.0 12Í3.5 1125 7.0 9.0

they better withstand rapid changes and have little or negligible internal stress.

In the preparation of the material according to the invention, low molecular weight epoxy resins based on diane with an average molecular weight of 312-700 and an epoxy group content of 0.286-0.641 mol/100 g of epoxides are used in particular.

From the alkyl esters of acrylic acid, both esters of primary and secondary mono-alcohols, normal or isomeric with 3-10 carbon atoms in the chain, are used. Curing is carried out in the range of 10-80 °C, or in the presence of hardening accelerators even at temperatures below 0 °C. The hardener is diethylenetriamine or dipropylenetriamine, but hardening can also be carried out with their mixtures. Curing is carried out with a superstoichiometric amount of hardener in the range of 103-150% of theory, based on the content of epoxy and acrylic groups in the modified material.

Example 1

225 g of diane-based epoxy resin, with an average molecular weight of 546 and an epoxy group content of 0.366 mol/100 g, are mixed with 75 g of n-butyl acrylate. The prepared modification has a viscosity of 710 mPa.s/25 °C, contains 0.275 mol/100 g of epoxy groups and 0.195 mol/100 g of acrylic groups. The modification is cured with diethylenetriamine in an amount of 100 — 150% of theory, based on the content of epoxy and acrylic groups. The parameters of the cured mass are given in the table. 100% of theory of diethylenetriamine (DETA) fromExample 2 g of low molecular weight epoxy resin based on bisphenol F with an average molecular weight of 315, are mixed with 5 g of n-decyl acrylate. The composition has a viscosity of 3630 mPa.s.

. s/25 °C, contains 0.0237 mol/100 g of acrylic groups and 0.601/100 g of epoxy groups. 100 g of the modifier cures 13.51 g of diethylenetriamine (103% of theory) and 14.43 g of diethylenetriamine (110% of theory). The parameters of the cured mass are given in the table.

5 6 DEET quantity cured material parameters (% theory] tensile strength elasticity (%) impact strength (MPa) (j/ ^cm2 ) avg. max. avg. max. avg. max.

103 47.1 52.0

110 57.2 59.0

3.1 4 12.5 14.1

5.5 7 15.4 17.0

Example 3 g of a low molecular weight epoxy resin based on novolak, with an average molecular weight of 700 and an epoxy group content of 0.284 mol/100 g, are mixed with 30 g of isopropyl acrylate. The composition has a viscosity of 5720 mPa.

tensile strength: ductility:

impact strength:

average 35.2 MPa; average 12.5 %/o; average 92.3 J/cm ² ;

. s/25 °C, contains 0.199 mol/100 g of epoxy groups and 0.2'63 mol/100 g of acrylic groups. The theoretical amount of dipropylenetriamine is 12.18 g per 100 g of the modifier. After curing 110% of the theory of dipropylerythriamine, the material has the following parameters:

max. 37.1 MPa max. 15% max. 115 J/cm ² .

Claims (1)

Tough compound containing secondary amine groups, obtainable by curing a mixture consisting of 5 - 50 wt. parts of alkyl esters of C 3 -C 10 acrylic acid; and 70 - 95 wt. parts of epoxy resin OF THE INVENTION having an average molecular weight of 312-700, diethylenetriamine and / or dipropylenetriamine in an amount of 103 to 150% by weight. theory, Based on the content of epoxy and acrylic groups.