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US 7,608,164 B2Granted
Fabric-crepe process with prolonged production cycle and improved drying
AssigneeGeorgia-Pacific Consumer Products LP
InventorsHung Liang Chou, Mark S. Hunter, Kang Chang Yeh
Life of this patent
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Abstract
A method of manufacturing absorbent sheet is directed to a wet-press/fabric-crepe process wherein add-on of adhesive to the Yankee surface is at relatively low levels, yet sheet transfer is maintained and production increased. Materials are selected and process parameters are controlled such that a paper machine can be operated for at least 4 hours before the Yankee coating needs to be stripped. Preferably, average increase in Yankee hood temperature is less than 1° F./minute during a production interval.
Claims55
A method of making a fabric-creped absorbent cellulosic sheet comprising:
- (a) compactively dewatering a papermaking furnish to form a cellulosic web and concurrently applying the web to a heated rotating backing cylinder;
- (b) fabric-creping the web from the heated backing cylinder surface at a consistency of from about 30% to about 60% utilizing a patterned creping fabric, the creping step occurring under pressure in a fabric-creping nip defined between the backing cylinder surface and the creping fabric wherein the fabric is traveling at a second speed slower than the speed of said backing cylinder surface, the fabric pattern, nip parameters, velocity delta and web consistency being selected such that the web is creped from the backing cylinder surface and transferred into the creping fabric;
- (c) providing a hygroscopic, re-wettable resinous adhesive coating composition comprising a polyvinyl alcohol to a surface of a heated drying cylinder of a Yankee dryer at an add-on rate of less than 20 mg/m2 of drying cylinder surface such that a resinous adhesive coating is formed, the Yankee dryer also having a dryer hood with a characteristic operating temperature limit;
- (d) transferring the web from the creping fabric to the surface of the heated drying cylinder of the Yankee dryer such that the web is adhered to the drying cylinder by the resinous adhesive coating;
- (e) drying the web on the surface of the drying cylinder;
- (f) removing the dried web from the drying cylinder surface;
- and
- (g) periodically stripping at least a portion of the resinous adhesive coating from the drying cylinder surface as the characteristic operating temperature limit of the drying hood of the Yankee dryer is approached;
- wherein the furnish and resinous adhesive coating composition are selected and heating of the backing cylinder and drying cylinder is controlled such that a production interval between successive strippings of adhesive coating from the drying cylinder has a duration of at least 4 hours, and during which production interval a predetermined target production rate of dried sheet is met.
6 more elements
A method of making a fabric-creped absorbent cellulosic sheet comprising:
- (a) compactively dewatering a papermaking furnish to form a web and concurrently applying the web to a heated rotating backing cylinder;
- (b) fabric-creping the web from the backing cylinder surface at a consistency of from about 30% to about 60% utilizing a patterned creping fabric, the creping step occurring under pressure in a fabric-creping nip defined between the backing cylinder surface and the creping fabric wherein the fabric is traveling at a second speed slower than the speed of said backing cylinder surface, the fabric pattern, nip parameters, velocity delta and web consistency being selected such that the web is creped from the backing cylinder surface and transferred into the creping fabric;
- (c) providing a hygroscopic, re-wettable resinous adhesive coating composition comprising a polyvinyl alcohol to a surface of a heated drying cylinder of a Yankee dryer at an add-on rate of about 15 mg/m2 of drying cylinder surface or less such that a resinous adhesive coating is formed, the Yankee dryer also having a dryer hood configured to provide drying energy to the web on the Yankee drying cylinder in the form of a heated air stream, the hood having a characteristic operating temperature and a characteristic operating temperature limit;
- (d) transferring the web from the creping fabric to the surface of the heated drying cylinder of the Yankee dryer such that the web is adhered to the drying cylinder by the resinous adhesive coating;
- (e) drying the web to a predetermined dryness on the surface of the drying cylinder;
- (f) removing the dried web from the drying cylinder surface;
- and
- (g) periodically stripping at least a portion of the resinous adhesive coating from the drying cylinder surface as the characteristic operating temperature limit of the drying hood of the Yankee dryer is approached;
- wherein the furnish and resinous adhesive coating composition are selected and heating of the backing cylinder and drying cylinder is controlled and such that a production interval between successive strippings of adhesive coating from the drying cylinder has a duration of at least 4 hours, and during which production interval a predetermined target production rate of dried sheet is met, the production interval further characterized in that the average rate of increase of the characteristic operating temperature of the dryer hood over the production interval is less than 1° F./minute.
6 more elements
A method of making a fabric-creped absorbent cellulosic sheet comprising:
- (a) preparing an aqueous papermaking furnish including pulp comprising pre-dried papermaking fibers which have been dried to at least 80% air-dry prior to preparing the aqueous furnish;
- (b) depositing the papermaking furnish on a formaninous support;
- (c) compactively dewatering the papermaking furnish to form a nascent web and concurrently applying the web to a heated rotating backing cylinder;
- (d) fabric-creping the web from the heated backing cylinder surface at a consistency of from about 30% to about 60% utilizing a patterned creping fabric, the creping step occurring under pressure in a fabric-creping nip defined between the backing cylinder surface and the creping fabric wherein the fabric is traveling at a second speed slower than the speed of said backing cylinder surface, the fabric pattern, nip parameters, velocity delta and web consistency being selected such that the web is creped from the backing cylinder surface and transferred into the creping fabric;
- (e) providing a hygroscopic, re-wettable resinous adhesive coating composition comprising a polyvinyl alcohol to a surface of a heated drying cylinder of a Yankee dryer at an add-on rate of about 15 mg/m2 of drying cylinder surface or less such that a resinous adhesive coating is formed, the Yankee dryer also having a drying hood with a characteristic operating temperature limit;
- (f) transferring the web from the creping fabric to the surface of the heated drying cylinder of the Yankee dryer such that the web is adhered to the drying cylinder by the resinous adhesive coating;
- (g) drying the web to a predetermined dryness on the surface of the drying cylinder;
- (h) removing the dried web from the drying cylinder surface;
- and
- (i) periodically stripping at least a portion of the resinous adhesive coating from the drying cylinder surface as the characteristic operating temperature limit of the drying hood of the Yankee dryer is approached;
- wherein the furnish and resinous adhesive coating composition are selected and heating of the backing cylinder and drying cylinder is controlled such that a production interval between successive strippings of adhesive coating from the drying cylinder has a duration of at least 4 hours, and during which production interval a target production rate of dried sheet is met.
8 more elements
Dependencies are inferred from the claim text.