Process for preparing phenolic binder

A process for preparing a phenolic binder for glass fibers, the process comprising:

• a) preparing a water-soluble phenol-formaldehyde resole resin in a single stage process by:
• 1) preparing an initial aqueous mixture including formaldehyde and phenol, the formaldehyde-to-phenol mole ratio being from about 2.5:1 to 4.2:1;
• 2) maintaining the aqueous mixture at a first temperature of from about 40.degree. C. to 50.degree. C. while adding a basic polymerization catalyst;
• 3) permitting the temperature of the aqueous mixture to rise to a second temperature between from about 60.degree. C. and 80.degree. C.;
• 4) maintaining the aqueous mixture at the second temperature during reaction of the phenol and formaldehyde to form the water-soluble phenol-formaldehyde resole resin until the free formaldehyde content of the aqueous mixture drops to a predefined level, the predefined level being about 40 percent by weight of the free formaldehyde in the initial aqueous mixture;
• 5) cooling the aqueous mixture to a third temperature between 20.degree. C. and 30.degree. C.;
• and
• 6) neutralizing the aqueous mixture to a pH of from about 7.2 to 7.6;
• b) preparing an aqueous reaction mixture including the phenol-formaldehyde resole resin, urea, and ammonia, the phenol-formaldehyde resole resin being prepared by a basic process not including an acid-catalyzed step, the weight ratio of ammonia to the resin solids of the unmodified resole resin being from about 1.0:100 to 3.0:100, the mole ratio of the urea to the free formaldehyde of the phenol-formaldehyde resin being from about 1:1 to 1.75:1;
• c) permitting the urea to react with the phenol-formaldehyde resole resin in the presence of the ammonia by waiting at least about 30 minutes after mixing the urea and the resole resin, the aqueous reaction mixture being agitated for at least a time sufficient to ensure complete mixing of the resole resin, the urea, and the ammonia, the aqueous mixture being maintained at a temperature of from about 5.degree. C. to 30.degree. C. while permitting the urea to react with the resole resin in the presence of the ammonia to form a modified resin;
• the urea and ammonia being added within about three days after neutralization;
• and
• d) subsequently completing preparation of the binder by adding a catalyst for curing the modified resole resin, a mineral oil lubricant, and an organo-silane adhesion promoter to the aqueous mixture.

A process for preparing a phenolic binder for glass fibers, the process comprising:

• a) preparing a water-soluble phenol-formaldehyde resole resin and eventually modified by urea in a single state process by:
• 1) preparing an initial aqueous mixture including formaldehyde and phenol;
• 2) maintaining the aqueous mixture at a first temperature of from about 40.degree. C. to 50.degree. C. while adding a basic polymerization catalyst;
• 3) permitting the temperature of the aqueous mixture to rise to a second temperature between from about 60.degree. C. and 80.degree. C.;
• 4) maintaining the aqueous mixture at the second temperature during reaction of the phenol and formaldehyde to form the water-soluble phenol-formaldehyde resole resin until the free formaldehyde content of the aqueous mixture drops to a predefined level;
• 5) cooling the aqueous mixture to a third temperature between 20.degree. C. and 30.degree. C.;
• and simultaneously adding a nitrogenous prereactant during the cooling and,
• 6) neutralizing the aqueous mixture;
• b) neutralizing the aqueous reaction mixture including the phenol-formaldehyde resole resin, urea, and ammonia, the phenol-formaldehyde resole resin being prepared by a basic process not including an acid-catalyzed step;
• c) permitting the urea to react with the phenol-formaldehyde resole resin in the presence of the ammonia by waiting at least about 30 minutes after mixing the urea and the resole resin to form a modified resin, the urea and ammonia being added within about three days after neutralization;
• and,
• d) subsequently completing preparation of the binder by adding a catalyst for curing the modified resole resin.