Dense paper and method of manufacturing

Claim 1

A process for manufacturing dense paper comprising the steps, performed in the following sequence, of: advancing a web of paper having a dry uncalendered density between opposite surfaces in a range of between about 7 to about 11 lbs/mil; impregnating the advancing web by applying to both of said surfaces an excess amount of an aqueous dispersion containing a blend of a rigid polymeric material and an inorganic filler, said blend consisting essentially of from about 35 to about 90% of said polymeric material and from about 10 to about 65% of said inorganic filler, said percentages being by weight based on the weight of the blend, said rigid polymeric material having a glass transition temperature in a range of between about 15 to about 60° C., and passing said advancing web between opposed squeeze rolls to ensure penetration of said web by said dispersion and to remove excess dispersion from said surfaces; and heating said web after it passes between said rolls and said excess dispersion has been removed to fuse said blend in said web in a range of between about 8.5% to about 50%, by weight, of the blend, said weight being based on the dry weight of the web.