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US 7,451,643 B2Granted
Test to measure curling tendency of paper in laser printers
AssigneeInternational Paper Company
InventorsKapil Mohan Singh, William Shields, Frederick Karsa
Life of this patent
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Abstract
The invention provides an apparatus and method for testing the tendency of a paper to curl. The paper is cut from a paper making machine and rapidly humidified to standard TAPPI conditions, and is thereafter run through an apparatus having a substantially vertically oriented nip. The paper is measured for curl, all data are tabulated and fed back into a data acquisition or paper machine control system.
Claims27
A method for measuring the tendency of a paper to achieve curl, comprising
- moving a paper sample from a paper making machine through a substantially vertical nip positioned such that the paper sample exits from the substantially vertical nip in a substantially vertical orientation:
- and predicting the tendency of a paper to curl with a regression analysis equation that accounts for the moisture content of the paper sample and the diagonal curl of the paper sample, wherein the regression analysis equation is Sx Max =325−142*(Moisture) +15.6*(MoistSQ)+0.341 Total Crl;
- wherein Sx Max is Maximum simplex curl, Moisture is ambient moisture found in a newly opened ream of paper, MoistSQ is square of the ream moisture, and Total Crl is diagonal curl.
A method for measuring the tendency of a paper to achieve-curl, comprising
- moving a paper sample from a paper making machine through a substantially vertical nip positioned such that the paper sample exits from the substantially vertical nip in a substantially vertical orientation,
- measuring the diagonal curl of the paper sample as or after the paper sample exits the substantially vertical nip, and
- tabulating corrective data to correct the tendency of a non-sample paper to curl in the paper making machine based on the predicted final printer curl.
Dependencies are inferred from the claim text.