Water-resistant additives for gypsum wood fiber products

A method for making an emulsion, comprising the steps of:

• (a) heating to a temperature ranging from about 185° F. to about 210° F. a mixture containing at least one wax, an alkyl phenol, and at least one surfactant selected from the group consisting of a sorbitan ester and a polyoxyethylene sorbitan ester, producing a wax phase mixture;
• (b) heating to a temperature ranging from about 185° F. to about 210° F. a mixture containing polynaphthalenesulfonic acid, an alkali metal hydroxide, and water, producing a water phase mixture;
• (c) adding the water phase mixture to the wax phase mixture to provide a mixture;
• (d) homogenizing the mixture of step (c) at a pressure from about 2000 psig. to about 4000 psig.;
• and
• (e) cooling the homogenized mixture at a rate effective to control the stability and viscosity of the homogenized mixture.

An emulsion comprising:

• a first wax having a melting point of at least 120° F. in an amount of about 30 wt. % to about 45 wt. % by weight, based on the total weight of the emulsion;
• a saponifiable wax in an amount from about 3 to about 5 wt. %, based on the total weight of the emulsion;
• a combination of surfactants in an amount from about of about 0.5 to about 5 wt. %, based on the total weight of the emulsion;
• an alkyl phenol in an amount from about 0.5 to about 10 wt. %, based on the total weight of the emulsion;
• a polynaphthalenesulfonic acid in an amount from about 0.25% to about 5 wt. %, based on the total weight of the emulsion;
• water in an amount from about 45 to about 65 wt. %, based on the total weight of the emulsion;
• and
• an alkali metal hydroxide in an amount from about 0.5% to about 3 wt. %, based on the total weight of the emulsion.

A gypsum wood fiber article, comprising:

• (a) a wood fiber;
• (b) gypsum;
• and
• (c) a wax emulsion.

A gypsum wood fiber article, comprising:

• (a) a wood fiber;
• (b) gypsum;
• and
• (c) a wax emulsion, the wax emulsion a complexed starch, the complexed starch comprising a starch and a complexing agent selected from the group consisting of a borate compound and a molybdenum compound.