Method of finishing paper utilizing substrata thermal molding
AssigneeS. D. Warren Company
InventorJay H. Vreeland
Life of this patent
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Abstract
Disclosed in a process for producing gloss and smoothness on the surface of a paper web, comprising: A. advancing a web of papermaking fibers through a nip formed by a smooth metal finishing drum and a resilient backing roll; and B. heating the drum to a temperature at least high enough to heat a substrate portion of the web to a temperature in which gloss and smoothness rapidly increase with increasing temperature due to thermoplastic molding of the substrate beneath the surface and at a temperature higher than where substantial gloss and smoothness would have already been obtained by molding of the surface of the web.
Claims21
Process for producing gloss and smoothness on the surface of a paper web, comprising the steps of:
- A. providing a finishing apparatus comprising a smooth metal finishing drum and a resilient backing roll pressed against the drum at a force up to 700 KN/M (4000 pounds per lineal inch) to form a nip with pressure against the paper of at least 13,780 KN/M.sup.2 (2000 pounds per square inch) and less than 60,000 KN/M.sup.2 (8,700 pounds per square inch);
- B. advancing a web of papermaking fibers having a moisture content of from 3% to 7% of the bone dry weight of the fibers through the nip at a speed which results in the web dwelling in the nip from 0.3 milliseconds to 12 milliseconds;
- and
- C. simultaneously with step B, heating the drum to a surface temperature having a value between 20.degree. C. below and 25.degree. C. above the Ts value determined by the following formula:
- Ts=[Ti.times.0.357t.sup.-0.479 -234.2e.sup.-0.131m] /[0.357t.sup.-0.479 -1]
- where:
- Ts=surface temperature of the heated drum, in .degree.C.;
- Ti=the initial temperature of the web just prior to entering the nip, in .degree.C.;
- t=dwell time of the web in the nip, in milliseconds;
- e=the base of the natural logarithm;
- and
- m=moisture content of the fibers in the web in weight percent of the bone dry fiber weight.
Dependencies are inferred from the claim text.