Abstract: In order to improve the mechanical strength after ageing, particularly in a wet medium, of an insulation product, especially a thermal and/or acoustic insulation product, based on mineral wool provided with a size, a latex is incorporated in the sizing composition which contains especially a phenolic resin. The presence of the latex allows the loss of mechanical performance after ageing to be very considerably reduced. The sizing composition advantageously comprises a latex based on an aqueous dispersion or emulsion of a polymer phase carrying hydrophilic functional groups. Application to the manufacture of insulation products intended to be exposed to atmospheric condensation and/or based on mineral wool of lower hydrolytic resistance.

Abstract: To improve the reduction in tensile strength due to aging as well as the recovery, a weak acid is applied to a glass fiber mat containing a phenolic condensation resin binder before the binder is hardened.

Abstract: A phenolic binder for glass fibers is prepared using an aqueous mixture including a phenol-formaldehyde resole resin, modified with urea in the presence of ammonia. The urea and ammonia are added after the basic mixture including the resole resin has been neutralized. The urea-modified resole resin shows greater stability than urea-modified resins prepared without ammonia.

Abstract: A condensation product of phenol, formaldehyde and urea condensed in the presence of a basic catalyst, said condensation product being a liquid and having a free phenol content below 0.5%, a free formaldehyde content below 3%, expressed by weight based on the total weight of liquid, and a dilutability, measured at 20.degree. C., of at least equal to 1000%.

Abstract: A condensation product of phenol, formaldehyde and urea condensed in the presence of a basic catalyst, said condensation product being a liquid and having a free phenol content below 0.5%, a free formaldehyde content below 3%, expressed by weight based on the total weight of liquid, and a dilutability, measured at 20.degree. C., of at least equal to 1000%.

Abstract: An etherified melamine-formaldehyde resin is disclosed that has prolonged shelf life, comparatively low free formaldehyde content, and is especially adapted as a binder for glass fiber mats. The melamine-formaldehyde resin is prepared in several distinct stages including condensation in a basic aqueous solution, etherification by cooling and acidification, neutralization with triethanolamine, and final stabilization. The free formaldehyde content of the resin so produced can be adjusted by reacting it with urea.