Patent Publication Number: US-2010122787-A1

Title: Application of chemical aids after a headbox of a papermaking process

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application is a continuation-in-part of U.S. Ser. No. 12/274,682, which is herein incorporated by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     Sizing chemicals play an important role in the papermaking process, e.g. prevents the penetration of liquids into a paper sheet and/or improves the receipt of ink onto a paper sheet. A more efficacious way of applying sizing agents is sought by the papermaking industry. 
     SUMMARY OF THE INVENTION 
     The present invention provides for a method of applying one or more chemicals to a papermaking process comprising: applying said chemicals between a headbox slice opening and a first drainage element of said papermaking process, wherein said chemicals include at least one of the following: sizing chemicals; internal sizing chemicals; surface sizing chemicals; rosin; alkenyl succinic anhydride (ASA); alkyl ketene dimmer (AKD); styrene-maleic anhydride (SMA); and ethylene-acrylic acid (EAA). 
     The present invention also provides for a method of improving sheet and/or web properties formed from a cellulosic suspension of a papermaking process comprising: applying one or more chemicals between a headbox slice opening and a first drainage element of said papermaking process, wherein said chemicals are selected from the group consisting of: sizing chemicals, internal sizing chemicals, surface sizing chemicals, rosin, alkenyl succinic anhydride (ASA), alkyl ketene dimmer (AKD), styrene-maleic anhydride (SMA), and ethylene-acrylic acid (EAA); optionally performing one or more measurements of the sizing properties of a sheet and/or web of said papermaking process; optionally wherein a plurality of said measurements provide a cross-directional profile of said web and/or said sheet properties in said papermaking process; and optionally controlling said web and/or sheet properties by adjusting the application of said chemicals to the papermaking process in response to said one or more measurements. 
     The present invention also provides for a method to activate a papermaking process chemical program containing a plurality of chemical components that are applied to said papermaking process comprised of: applying a first chemical component before a headbox slice opening and wherein a second chemical component is applied between a headbox slice opening and a first drainage element of said papermaking process, wherein said first chemical component contains at least one of the following: sizing chemicals; internal sizing chemicals; surface sizing chemicals; rosin; alkenyl succinic anhydride (ASA); alkyl ketene dimmer (AKD); styrene-maleic anhydride (SMA); and ethylene-acrylic acid (EAA). 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Definitions 
     “Papermaking process”/“papermaking processes” refer to a method(s) of making any kind of paper products (e.g. paper, tissue, board, etc.) from pulp comprising forming an aqueous cellulosic papermaking furnish, draining the furnish to form a sheet and drying the sheet. The steps of forming the papermaking furnish, draining and drying may be carried out in any manner known to those skilled in the art. The papermaking process/processes may also include a pulping stage, e.g. making pulp from wood and/or non-wood raw material and bleaching stage, e.g. chemical treatment of the pulp for brightness improvement. 
     “Wet end” refers to papermaking process operations in the approach system, sheet forming section and pressing section. 
     “Sheet”/“sheets” refer to sheet(s) formed as a result of or during a papermaking process/papermaking processes. 
     The selection and application scheme of sizing chemicals, which is appropriate for a papermaking process, would be appreciated by one of ordinary skill in the art. By choosing various sizing chemistries and schemes for applying these chemistries the sheets structural and/or physical properties can be controlled. 
     How much sizing chemicals are added to a papermaking process depends on various factors, which would be appreciated by one of ordinary skill in the art. For example, factors such as the type of papermaking process, e.g. board, paper sheet, or tissue may impact the amount of chemistry added to a papermaking process. 
     A. Effective Application of Sizing Chemicals 
     As stated above, the sizing chemicals are applied between a headbox slice opening and a first drainage element of a papermaking process. 
     In one embodiment, the chemicals are applied to a papermaking process location that is proximate to a headbox slice opening. 
     In a further embodiment, proximate refers to a distance from 0 cm to about 20 cm. 
     In a further embodiment, proximate refers to a distance from 0 cm to about 10 cm. 
     In another embodiment, the papermaking process contains a foudrinier paper machine. 
     In another embodiment, the papermaking process contains a gap forming paper machine. 
     The application of the sizing chemicals to the papermaking process can take place in various ways, e.g. non-contact ways or through a non-contact applicator, which would be appreciated by one of ordinary skill in the art. 
     In one embodiment, the chemicals are applied to the papermaking process by a spray bar, optionally wherein the spray bar is installed onto a headbox top slice cover. 
     In another embodiment, the chemicals are applied to the papermaking process by a curtain applicator. 
     In another embodiment, the chemicals are applied to a papermaking process by using a slice blade, which is associated with the papermaking process. 
     In another embodiment the methodology further comprises adding sizing chemicals to an additional area of the papermaking process aside from between a headbox slice opening and a first drainage element. These areas include typical application areas, including, but not limited to, the dilution headbox stream or channels inside the headbox installed hardware. 
     B. Improving Sheet and Web Quality 
     The application of sizing agents between a headbox slice opening and a first drainage element of said papermaking process can be utilized to improve sheet qualities, e.g. the improvement in sheet and/or web properties can result in a given amount of chemicals imparting a better sheet/web property compared to a situation when the chemicals are added only to an area before the free jet, e.g. into dilution lines leading to the headbox and/or the headbox itself. 
     This disclosure, therefore, can encompass a method of improving sheet and/or web properties formed from a cellulosic suspension of a papermaking process. The method comprises: applying one or more chemicals between a headbox slice opening and a first drainage element of said papermaking process, wherein said chemicals are selected from the group consisting of: sizing chemicals, internal sizing chemicals, surface sizing chemicals, rosin, alkenyl succinic anhydride (ASA), alkyl ketene dimmer (AKD), styrene-maleic anhydride (SMA), and ethylene-acrylic acid (EAA); optionally performing one or more measurements of the sizing properties of a sheet and/or web of said papermaking process; optionally wherein a plurality of said measurements provide a cross-directional profile of said web and/or said sheet properties in said papermaking process; and optionally controlling said web and/or sheet properties by adjusting the application of said chemicals to the papermaking process in response to said one or more measurements. 
     In one embodiment, the chemicals are applied to a papermaking process location that is proximate to a headbox slice opening. In a further embodiment, proximate refers to a distance from 0 cm to about 20 cm. In a further embodiment, proximate refers to a distance from 0 cm to 10 cm. 
     In another embodiment, the chemicals are applied to a headbox free jet of a papermaking process. One of ordinary skill in the art would appreciate the scope of what is meant by a free jet of a papermaking process, e.g. a free jet is the fluid that flows out from the headbox, typically the free jet is 5 cm in length from the headbox and can be 2 cm in height, depending upon the slice opening that is associated with the headbox. 
     In another embodiment, the papermaking process contains a foudrinier paper machine. 
     In another embodiment, the papermaking process contains a gap forming paper machine. 
     The application of the chemicals to the papermaking process can take place in various ways, e.g. non-contact ways or through a non-contact applicator, which would be appreciated by one of ordinary skill in the art. 
     In one embodiment, the chemicals are applied to said papermaking process by a spray bar, optionally wherein the spray bar is installed onto a headbox top slice cover. 
     In another embodiment, the chemicals are applied to said papermaking process by a curtain applicator. 
     In another embodiment, the chemicals are applied to a papermaking process by using a slice blade, which is associated with the papermaking process. 
     In another embodiment, the methodology further comprises adding chemicals to an additional area of the papermaking process aside from between a headbox slice opening and a first drainage element. These areas include typical application areas, including, but not limited to, the dilution headbox stream or channels inside the headbox installed hardware of said papermaking process. 
     In another embodiment, the methodology provides for performing the measurement of the sizing properties of a forming section and/or formation properties of the sheet and/or web and optionally wherein a plurality of said measurement(s) provide a cross-directional profile of said web and/or said sheet properties in said papermaking process. 
     In a further embodiment, the plurality of measurements of the sheet properties (e.g. formation, ash, and air permeability) is practically done by taking a dry-sheet CD strip from the reel and the properties are measured in the lab. 
     In another embodiment, the web profile allows an operator to control the distribution of chemicals added to a web/sheet and pinpoint the application of chemical in one area over the other to produce a sheet that has an even application of chemicals, e.g. sizing chemicals, applied to it. 
     In a further embodiment, the basis weight CD profile is controlled. 
     In a further embodiment, the ash CD profile is controlled. 
     In a further embodiment, the sheet formation CD profile is controlled. 
     In a further embodiment, the sheet permeability CD profile is controlled. 
     C. Program Management 
     As stated above, the present invention also provides for a method to activate a papermaking process chemical program containing a plurality of chemical components that are applied to said papermaking process comprised of: applying a first chemical component before a headbox slice opening and wherein a second chemical component is applied between a headbox slice opening and a first drainage element of said papermaking process, wherein said first chemical component contains at least one of the following: sizing chemicals; internal sizing chemicals; surface sizing chemicals; rosin; alkenyl succinic anhydride (ASA); alkyl ketene dimmer (AKD); styrene-maleic anhydride (SMA); and ethylene-acrylic acid BAA). 
     In one embodiment, the second chemical component is applied to a forming wire that contains a papermaking furnish and wherein said application is optionally applied across the whole forming wire width. 
     In another embodiment, the second component is at least one of the following: alum or PAC.