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In a process for hardening phenol-formaldehyde resol resins, comprising conducting the hardening of the resins with an acidic solution of water and/or an organic solvent having dissolved therein an aromatic sulphonic acid and/or concentrated sulphuric acid, the improvement comprising the hardening i

In a process for hardening phenol-formaldehyde resol resins, comprising conducting the hardening of the resins with an acidic solution of water and/or an organic solvent having dissolved therein an aromatic sulphonic acid and/or concentrated sulphuric acid, the improvement comprising the hardening in the presence of aniline added to the phenolic resin beforehand in a quantity of between about 0.5 and 2% relative to the weight of the phenolic resin whereby the pot life is extended and the cure time is satisfactory, the resultant products being especially useful as prepegs.

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1. In a process for hardening phenol-formaldehyde resol resins, comprising conducting the hardening of the resins with an acidic solution of water and/or an organic solvent having dissolved therein an aromatic sulphonic acid and/or concentrated sulphuric acid, the improvement comprising conducting t

1. In a process for hardening phenol-formaldehyde resol resins, comprising conducting the hardening of the resins with an acidic solution of water and/or an organic solvent having dissolved therein an aromatic sulphonic acid and/or concentrated sulphuric acid, the improvement comprising conducting the hardening in the presence of aniline added to the phenolic resin beforehand in a quantity of between about 0.5 and 2% relative to the weight of the phenolic resin. 2. A process according to claim 1, wherein the quantity of aniline employed is between about 0.8 and 1.5% relative to the weight of the phenolic resin. 3. A process according to claim 1 wherein the formaldehyde to phenol molar ratio is about 1.5:1 to 2.5:1. 4. A process according to claim 1 wherein the hardening catalyst concentration is about 4-25% based on the weight of the phenolic resin. 5. A process according to claim 1 wherein the hardening catalyst concentration is about 6-12% based on the weight of the phenolic resin. 6. A composition consisting essentially of an uncured phenol-formaldehyde resol and about 0.5-2% aniline by weight relative to the weight of the resol. 7. A composition according to claim 6 containing 0.8-1.5% by aniline. 8. A process according to claim 1 conducted in the presence of a reinforcing agent. 9. A process according to claim 8 wherein said reinforcing agent in glass, asbestos, or cellulose fiber or fabric. 10. A process according to claim 8 wherein the reinforcing agent is glass rovings. 11. A prepeg produced according to claim 8. 12. A prepeg produced according to claim 9. 13. A prepeg produced according to claim 10.