Patent ID: 7410688

Claim:
A composite board comprising as components, a core and paper facer sheet material adhesively laminated to at least one face of the core, the core including a substantially uniform mixture of perlite, binder and cellulose fiber, the core being formed as a water slurry, the perlite being in an expanded state such that its particles include internal voids and exhibit a density of about 3 to about 15 pounds per cubic foot, the perlite comprising between about 15% to about 40% of the weight of the core, the cellulose fiber comprising between about 10% to about 30% of the weight of the core, the binder comprising between about 5% to about 15% of the weight of the core, the cellulose fiber and binder forming a matrix in the interstices between the perlite particles, the binder adhering the cellulose fibers to one another and adhering the cellulose fibers to the perlite particles, the paper facer material being laminated to the core with a water based adhesive applied across substantially the full area of the facer material, the formulation of the perlite, cellulose fiber, binder and other constituents of the core and paper facer material being selected to produce a composite board density of about 30 pounds per cubic foot or less and a nail pull of at least about 56 pounds when the composite board caliper is nominally ⅜″ and at least about 77 pounds when the composite board caliper is nominally ½″.