Three hour fire resistant door, panel or building element, and method of manufacturing the same

Claim 2

A three-hour fire resistant door comprising in combination: a generally rectangular, planar calcium silicate-asbestos fiber core having peripheral edges and opposed faces; stiles and rails framing the edges of said core, said stiles and rails being of 3 to 5 plywood contruction and being monoammonium phosphate borax, ammonium sulphate pressure treated elements; cement asbestos board cross bands disposed on opposite faces of said core and in intimate contact therewith; and two face veneers disposed on the exposed faces of said cement asbestos board cross bands.

Claim 3

Process for the manufacture of a three-hour fire resistant door comprising the steps of: preparing a core consisting essentially of calcium silicate and asbestos fiber, said core being generally rectangular and having a peripheral edge and opposed face surfaces; framing said core with stiles and rails of three to five plywood structure; affixing two cement asbestos board cross bands band sheets to two veneer sheets to form two two-ply skins; and affixing said two two-ply skins respectively to the opposed face surfaces of the core such that the cement asbestos board cross bands are intermediate said core and said veneer sheets.

Claim 4

Process for the manufacture of a three-hour fire resistant door comprising the steps of: preparing a core consisting essentially of calcium silicate and asbestos fiber, said core being generally rectangular and having a peripheral edge and opposed face surfaces; framing said core with stiles and rails of three to five plywood structure; affixing two cement asbestos board cross bands band sheets to two veneer sheets to form two two-ply skins; and affixing said two two-ply skins respectively to the opposed face surfaces of the core such that the cement asbestos board cross bands are intermediate said core and said veneer sheets.

Claim 5

Process as defined by claim 2 wherein said core consists essentially of about 70% by weight to 90% by weight of calcium silicate and 5% by weight to 20% by weight of asbestos fibers.

Claim 6

Process as defined by claim 2 wherein said stiles and rails are monoammonium phosphate, borax, ammonium sulfate pressure treated elements.

Claim 7

Process as defined by claim 4 wherein said pressure treatment is conducted at a temperature in the range of about 100° to 200° F., at a pressure in the range of about 125 psi to 225 psi for a time period of about 15 to 21 hours.

Claim 8

Process as defined by claim 2 wherein said cement asbestos board cross bands are of a density in the range of about 85 lbs. to 105 lbs./Ft. 3 and of a thickness in the range of about 1/16 to about one-fourth inch.

Claim 9

Process as defined by claim 6 wherein said cross bands are affixed to said veneer faces at a temperature in the range of about 275° to 300° F., at a pressure in the range of about 100 to 250 psi and for a time period in the range of about 4 to 8 minutes.