Blends comprising epoxy resins and mixtures of amines with guanidine derivatives
The present invention provides a blend comprising one or more epoxy resins and a mixture which comprises 0.3 to 0.9 amine equivalent, per equivalent of epoxide of the epoxy resin used, of a hardener component a) and as hardener component b) a compound of the formula I, a process for preparing this blend, the use of the blend of the invention for producing cured epoxy resin, and an epoxy resin cured with the blend of the invention.
1. A blend comprising
α) one or more epoxy resins and
β) a mixture comprising
a) a hardener component comprising at least two hardener components a1) and a2) provided in a weight ratio of a1) to a2) ranging from 1.5 to 10:1; and
b) tetramethylguanidine provided in an amount of 5% to 55% by weight, based on the weight of the mixture β);
wherein hardener component a1) is a polyetheramine selected from the group consisting of: difunctional, primary polyetheramine based on polypropylene glycol, with an average molar mass of 230; difunctional, primary polyetheramine based on polypropylene glycol, with an average molar mass of 400; trifunctional, primary polyetheramine prepared by reacting propylene oxide with trimethylolpropane, followed by amination of the terminal OH groups, with an average molar mass of 403; and trifunctional, primary polyetheramine prepared by reacting propylene oxide with glycerol, followed by amination of the terminal OH groups, with an average molar mass of 5000;
wherein hardener component a2) is selected from the group consisting of: isophoronediamine, aminoethylpiperazine, 1,3-bis(aminomethyl)cyclohexane, and triethylenetetraamine; and
wherein the mixture β) is present in an amount of 10 to 60 mol % less than the amount needed for reaction of the active epoxy groups of the one or more epoxy resins α) and the amine functions of the mixture β), and such that hardener component a) is present in an amount of 0.3 to 0.9 amine equivalent per epoxide equivalent of the one or more epoxy resins α).
2. The blend according to claim 1 , wherein the blend further comprises reinforcing-fiber material.
3. A process for preparing the blend according to claim 1 , which comprises mixing the one or more epoxy resins α) with the mixture β) at temperatures below the initial curing temperature of the hardener component a).
4. A cured epoxy resin obtained by a process comprising curing the blend according to claim 1 .
5. The cured epoxy resin according to claim 4 , wherein the cured epoxy resin is a molding.
6. A molding according to claim 5 , which is fiber-reinforced.
7. The molding according to claim 6 , obtained by a process comprising: lining a mold with a reinforcing-fiber material; introducing the blend according to claim 1 into the mold with infusion technology; and curing the blend in the mold.
8. The molding according to claim 6 , wherein the molding is a reinforced component for rotor blades of wind turbines.