High temperature mineral fiber binder

Claim 1

A mineral fiber thermal insulation product having a density of about 5 to about 10 pounds per cubic foot and having distributed throughout a cured resin obtained by spraying the mineral fiber with a binder comprising the reaction product of a modified phenol formaldehyde condensate, boric acid, ammonium hydroxide and urea and curing at a temperature in the range of 400° to 500° F.; wherein said modified phenol formaldehyde condensate, consisting essentially of the reaction product of phenol, formaldehyde and a di-functional nitrogenous compound, is initially prepared by reacting one mole of a di-functional compound in which said functional groups are amido or imino groups capable of reacting with the hydroxymethylene groups of the poly-hydroxymethyl phenols formed by the condensation of phenol and formaldehyde, with about 2.5 to 3 moles of phenol and about 6 to 7.5 moles of formaldehyde such that said modified phenol formaldehyde condensate contains less than 2% by weight of free phenol and less than 5% by weight of free formaldehyde and about 12 to 15% by weight of nitrogen with substantially no unreacted nitrogenous compound; and, thereafter reacting said modified phenol formaldehyde condensate with about 12 to 16 parts by wt. of boric acid for each 100 parts by wt. of said condensate, and about 40 to 80 parts by wt. of urea for each 100 parts by weight of said condensate and sufficient ammonium hydroxide so that the final composition has a pH of about 7 to 9.