Catalyst for curing epoxides

A latent catalyst for curing a composition comprising epoxy compounds comprising a 1,3-substituted imidazolium salt of the formula I

• in which
• R1 and R3 independently of one another are an organic radical having 1 to 20 C atoms,
• R2, R4, and R5 independently of one another are an H atom or an organic radical having 1 to 20 C atoms, it also being possible for R4 and R5 together to form an aliphatic or aromatic ring,
• X is the anion of a phosphorus oxyacid, selected from the group consisting of hypophosphite, phosphite, metaphosphites, metaphosphate, monoalkylphosphites, monoalkylphosphates, dialkylphosphates, and dimeric or oligomeric compounds formed by elimination of water from the corresponding acids, the monoalkylphosphites and mono- and dialkylphosphates having 1 to 20 C atoms, and
• n is 1, 2 or 3.

A curable composition comprising epoxy compounds and a latent catalyst of the formula I

• in which
• R1 and R3 independently of one another are an organic radical having 1 to 20 C atoms,
• R2, R4, and R5 independently of one another are an H atom or an organic radical having 1 to 20 C atoms, it also being possible for R4 and R5 together to form an aliphatic or aromatic ring,
• X is the anion of a phosphorus oxyacid, selected from the group consisting of hypophosphite, phosphite, metaphosphites, metaphosphate, monoalkylphosphites, monoalkylphosphates, dialkylphosphates, and dimeric or oligomeric compounds formed by elimination of water from the corresponding acids, the monoalkylphosphites and mono- and dialkylphosphates having 1 to 20 C atoms, and
• n is 1, 2 or 3.