CS242007B1 - Epoxy composition - Google Patents

Abstract

The invention relates to the field of epoxy resins. The technical problem of preparing modifiers providing tough materials after curing polyenepolyamine is solved. The essence of the invention is a composition of acrylates with intermediate resins. The invention can be used in the production of laminates and composite binders

Description

The invention relates to a composition of epoxy resins with acrylic acid esters.

Compositions of low molecular weight diane epoxy resins with an average molecular weight of 340 to 400, with acrylic acid esters, provide low-viscosity combinations, which after curing with aliphatic polyamines are very hard, brittle, have relatively high tensile strengths but low values of ductility and impact toughness. Materials with such parameters do not have widespread use. Compositions of medium molecular weight diane epoxy resins with an average molecular weight of 700 to 2,000, with acrylic acid esters provide combinations with increased viscosity, but after curing with polyamines, rubber-like flexible materials are obtained, having fairly high values of ductility, good impact toughness but relatively low tensile strengths. Between low molecular weight and medium molecular diane epoxy resins, there is a small group of resins with an average molecular weight of about 410 to 650, which differs quite significantly from both groups. This group is sometimes assigned to low molecular weight epoxides, sometimes to medium molecular weight epoxy resins. The compositions of this intermediate group with acrylic acid esters have not yet been described.

We have now found that compositions consisting of 5 to 30 wt. % of acrylic acid esters with Cd—C12 alcohols and 70 to 95 wt. % of intermediate epoxy resin with an average molecular weight of 415 to 650 and an epoxy group content of 0.300 to 0.480 mol/100 g, provide, after curing, polyenepolyamines with high toughness materials with high impact toughness, sufficient tensile strength and relatively significant strength. In Fig. 1 it can be observed that the impact toughness curve increases from the inflection point, corresponding to an average molecular weight of about 415, to a maximum around an average molecular weight of 540, after which it decreases to a second inflection point corresponding to an average molecular weight of about 645, and then decreases with increasing average molecular weight in a very flat curve. This demonstrates the distinct difference of the Intermediate group of epoxy resins and at the same time their suitability for the production of highly tough casting materials and binder composites.

For the composition according to the invention, esters of acrylic acid with aliphatic, cyclanic or aromatic alcohols having 4 to 12 carbon atoms in the molecule and a single hydroxyl group are used. Preferably, the following are used: n-butanol, isobutanol, sec.butanol, amyl alcohols, n-octanol, ethylhexyl alcohol, lauryl alcohol, cyclohexanol, benzyl alcohol and others.

The viscosity of the composition usually ranges between 500 and 10,000 mPa.s/25°C. The amount of hardener (polyamide) is calculated according to the formula:

m = H . (Éi + A), where m = amount of hardener in g/100 g of composition,

H — equivalent weight of hardener (hydrogen equivalent),

Ei = content of epoxy groups in the composition in mol/100 g and

A = content of acrylic groups in the composition in mol/100 g.

Curing is usually carried out in the range of 15 to 16 °C for a period of 24 to 100 hours. At temperatures below 10 °C, the curing process is catalyzed by the addition of phenolic accelerators.

The compositions according to the invention are particularly suitable as a component of binders for composites, casting and impregnating resins.

Example 1 g of epoxy resin of the selected average molecular weight is mixed with 25 grams of ethylhexyl acrylate. The composition is cured at room temperature with the calculated amount of diethylenetriamine. The parameters of the cured masses are given in Fig. 1 and in the following table.

average mol. wt. of epoxide tensile strength (MPa) ductility % impact strength (kj/m ² ) 340.9 63.9 1.4 7.3 363 56.8 6.0 8.2 377 56.5 6.9 10.9 390 54.5 7.5 12.8 400 54.0 8.8 11.1 415 52.8 8.9 15.8 430 51.6 10.1 49.8 450 50.1 19.6 62.2 508 45.8 19.2 73.8 563 43.0 26.3 72.9 618 40.2 35.0 67.5 648 36.5 43.3 55.3 705 32.0 52.7 40.6 956 22.8 164 30.8 1,041 15.8 196 28.8 1300 6.7 255 27.6

Example 2 average molecular weight 530. The resulting composition is cured with a theoretical amount of

Different amounts of n-butacrylate are mixed with different amounts of epoxy resin o by dipropylenetriamine at room temperature. The results are given in the table: Amount of n-BuA viscosity of the camp. tensile strength ductility impact toughness. O/o (Pa . s/25°C) (MPa) % (kJ/ ^m2 ) 5 1,397.0 65.1 1.9 7.2 10 144.3 51.6 4.1 12.3 20 29.9 49.8 15.2 28.3 30 1.5 18.7 35.6 144.1 Example 3 A M 645, El — 0.3081 mol/100 g Β M 416, El = 0.4801 mol/100 g 25 g of your chosen acrylic with misi 75g resin A or B. Resin: Composition is hardened by theoretical

by the amount of diethylenetriamine:

Resin A tensile strength (MPa) elasticity % impact strength (kj/m ² ) Acrylate viscosity (Pa . s/25°C) isobutyl 6.68 45.5 12.1 40.8 cyclohexyl 11.54 46.2 15.0 55.7 lauryl 54.15 22.7 45.7 146.1 benzyl 8.12 44.8 14.3 28.1 Resin B Acrylate viscosity (Pa . s/25°C) tensile strength (MPa) elasticity % impact strength (kj/m ² ) isobutyl 1.05 52.8 10.6 29.9 cyclohexyl 5.18 48.9 12.1 37.8 lauryl 19.80 28.5 39.6 132.9 benzyl 3.46 53.5 12.9 25.3

SUBJECT

Claims (1)

Epoxy composition, characterized in that it consists of 1 wt 5 to 30% of esters of acrylic acid with C4 to C12 alcohols and according to the invention 70 to 95% epoxy resin having an average molecular weight of 415 to 650 and an epoxy group content of 0.300 to 0.480 mol per 100 g.