A method for preparing a blade-coated paper and a blade-coated paper product

• Main Authors: MULCAHY, LEO THOMAS, PETERSON, RALPH SCOTT, STREISEL, ROBERT CHARLES, HANK, MARK ALAN
• Format: Patent
• Language: English; French; German
• Published: 11.11.1998
• Edition: 6
• Subjects: APPARATUS THEREFOR; FIBROUS RAW MATERIALS OR THEIR MECHANICAL TREATMENT; IMPREGNATING OR COATING OF PAPER; PAPER NOT OTHERWISE PROVIDED FOR; PAPER-MAKING; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; PRODUCTION OF CELLULOSE; PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCESFROM CELLULOSE-CONTAINING MATERIALS; PULP COMPOSITIONS; REGENERATION OF PULPING LIQUORS; TEXTILES; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; TREATMENT OF THE MATERIALS BEFORE PASSING TO THE PAPER-MAKINGMACHINE

The invention describes a method for preparing a blade-coated paper having less than 20 ppm per unit area solid, non-fibrous contaminants of size greater than 0.3 mm2, and including at least 5% by weight recycled paper, comprising the steps of:a) combining a quantity of paper to be recycled, containing lignin, cellulosic fibers and solid non-fibrous contaminants, with aqueous liquid to form a slurry containing about 9-15% by weight solids and agitating in a low shear mixer at a temperature less than 65.5°C for a time sufficient to separate said lignin fibers from said solid contaminants without significantly degrading said solid contaminants, and then sequentially,b) removing from said slurry gross contaminants of a size in a range greater than about 5 mm by passing through holes of a predetermined diameter;c) removing from the slurry contaminants of specific gravity in a range greater than 1;d) removing from the slurry intermediate contaminants having a size in a range greater than about 2 to 3 mm by passing the slurry through holes of a predetermined size,e) removing sand from the slurry,f) removing from the slurry fine contaminants of a size in a range greater than about 0.15 mm, by passing the slurry through elongated slots of predetermined width,g) removing from the slurry contaminants with a specific gravity less than 1,h) dewatering the slurry to form a wet friable pulp having a water content of about 30-60%,i) digesting said pulp in a cooking liquor for a time and at a temperature sufficient to hydrolyze a substantial portion of the lignin remaining in intimate association with said pulp,j) separating said digested pulp from spent cooking liquor,k) preparing paper from said separated pulp, andl) coating said paper with a clay containing coating using a blade to regulate coating weight.