Fire-retardant resins and composite materials

An epoxide resin for the manufacture of a fibre-reinforced composite material having fire retardant properties and/or for use as an adhesive or hot-melt adhesive having fire retardant properties, the epoxide resin being halogen-free and phenolic resin-free, the epoxide resin comprising:

• A. a mixture of (i) at least one first non-halogenated multifunctional epoxide-containing resin which has an epoxide functionality of greater than 2 and which is solid at 20° C., and (ii) at least one second non-halogenated multifunctional epoxide-containing resin which has an epoxide functionality of less than or equal to 2 and which is liquid at 20° C.;
• B. at least one catalyst for curing the mixture of epoxide-containing resins to form a cured epoxy resin;
• and
• C. a mixture of first, second and third fire retardant additives for reacting together to form an intumescent char when the cured epoxy resin is exposed to a fire,
• wherein (i) the first fire retardant additive comprises a blowing agent for generating a non-combustible gas, (ii) the second fire retardant additive comprises an acid donor for decomposing to form a phosphoric acid when the cured epoxy resin is exposed to a fire, wherein the second fire retardant additive comprises or consists of ammonium polyphosphate and the ammonium polyphosphate of the second fire retardant additive is present in a concentration of from 27 to 32.5 wt % based on the weight of the epoxide resin, and (iii) the third fire retardant additive comprises at least one or both of (a) a ceramic or glass material and (b) a ceramic or glass material precursor for to form a ceramic or glass material when the cured epoxy resin is exposed to a fire, wherein in the mixture of first, second and third fire retardant additives, the first, second and third fire retardant additives are present in a weight ratio of 1:6-6.5:1.3-1.7.