Patent Abstract:
A fabric for use in a papermaking machine, the fabric including a first end portion of the fabric having a first flexibility, and a second end portion of the fabric having a second flexibility. At least one of the first end portion and the second end portion is treated with an agent to reduce the flexibility associated therewith. The first end portion and the second end portion are coupled together. The agent is substantially removed from the first end portion and the second end portion. The reduced flexibility of the first end portion and/or the said second end portion define a stiffness that is substantially unaffected by a humid environment.

Full Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to papermaking machines, and, more particularly, to press fabrics used in papermaking machines. 
     2. Description of the Related Art 
     In the papermaking process a fibrous slurry is formed and deposited onto a moving forming fabric in a forming section of a papermaking machine. A significant amount of water is drained from the slurry through the forming fabric, leaving the fibrous web on a surface of the forming fabric. The formed fibrous web passes from the forming section to a press section, which may include press nips or press belts. The fibrous web passes through the pressing section as compressive forces squeeze water from the web. The fibrous web proceeds to a drying section that may include one or more rotatable dryer drums or cylinders, such as Yankee dryers. The formed web may travel through a serpentine path sequentially around a series of drums, which serve to further drive the web into paper or fiberboard product. 
     The fabrics used in the forming, press and dryer sections all take the form of endless loops that are utilized by the papermaking machine and function in a manner that facilitates the conveyance of the web through its change from a slurry to a fibrous sheet. 
     Press fabrics are utilized in an endless belt form because a forming fibrous web is susceptible to marking in the press section and any non-uniformity in the press fabric may result in a marking on the paper. That is why it is important in the seaming region of a press fabric that the seam perform as the rest of the fabric or as closely thereto as possible. One method of seaming the belts together is the use of seaming loops that are formed in the machine direction yarns of the fabric. The seam is closed by bringing the two ends of the press fabric together by interdigitating the seaming loops at the ends of the fabric, and by directing a pin or pintel through the passage defined by the interdigitated seaming loops to thereby lock the ends of the fabric together. 
     What is needed in the art is a method of facilitating an accurate aligning of the ends of the fabric as well as facilitate the seaming thereof. 
     SUMMARY OF THE INVENTION 
     The present invention provides a fabric that is treated and seamed together and a method for treating the fabric thereof. 
     The invention in one form is directed to a fabric for use in a papermaking machine, the fabric includes a first end portion of the fabric having a first flexibility, and a second end portion of the fabric having a second flexibility. The first end portion and for the second end portion are treated with an agent to reduce the flexibility associated therewith. The first end portion and the second end portion are coupled together. The agent is substantially removed from the first end portion and the second end portion. The reduced flexibility of the first end portion and/or the said second end portion define a stiffness that is substantially unaffected by a humid environment. 
     An advantage of the present invention is that it is easier to seam ends of fabric that are not highly flexible. 
     Another advantage of the present invention is that the treatment is easily removed after the ends of the fabric are seamed together. 
     Another advantage of the present invention is that the treatment is removed from the fabric by the normal operation of the papermaking machine. 
     Yet another advantage of the present invention is that the stiffness of the end portions is substantially unaffected by prolonged storage in a high humidity environment. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above-mentioned and other features and advantages of this invention, and the manner of attaining them, will become more apparent and the invention will be better understood by reference to the following description of an embodiment of the invention taken in conjunction with the accompanying drawings, wherein: 
         FIG. 1  schematically illustrates a side view of a papermaking machine utilizing an embodiment of a fabric belt of the present invention 
         FIG. 2  is a schematicized top view of a fabric belt utilized in the papermaking machine of  FIG. 1 ; and 
         FIG. 3  is a cross-sectional view of the fabric of  FIG. 2  utilized in the papermaking machine of  FIG. 1 . 
     
    
    
     Corresponding reference characters indicate corresponding parts throughout the several views. The exemplification set out herein illustrates one embodiment of the invention, in one form, and such exemplification is not to be construed as limiting the scope of the invention in any manner. 
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to the drawings, and more particularly to  FIG. 1 , there is shown a schematicized view of an embodiment of the present invention of fabric belts being utilized in a papermaking machine  10 . Papermaking machine  10  includes a headbox  12 , a fabric belt  14 , a fabric belt  16 , between which a web  18  is formed and a press belt  20 . Even though three belts are shown it is understood that papermaking machine  10  may have more or fewer belts than illustrated in  FIG. 1 . A slurry material containing cellulosic fibers is directed from headbox  12  into a gap between fabric belt  14  and fabric belt  16 . Belts  14  and  16  come together around a roller and water is removed from the material allowing web  18  to be formed. Web  18  passes onto a press section having a press belt  20  where moisture is further removed. 
     Now, additionally referring to  FIGS. 2 and 3  there is shown a belt  14 ,  16  or  20  having end portions  22  and  24  that are to be joined together. Although belts  14 ,  16 , and  20  are discussed herein any of the other belts, which are not numbered can also be used with the present invention. Belt  14 ,  16  or  20  may have a batt layer  26  that is needled to a woven or non-woven fabric  28 . End portion  22  and end portion  24  may be complimentarily shaped to enhance the bonding between the end portions and to reduce any marking protuberances that may extend from a surface of belt  14 ,  16  or  20 . In the process of seaming end portions  22  and  24  together by way of joining loops or other features of the end portions it is advantageous to have the ends less flexible so they can be more easily aligned and seamed during that process. A treatment agent is applied to end portions  22  and for  24  to reduce the flexibility of belts  14 ,  16  and  20  at least in the end portions  22  and  24 . Although the treatment can be applied to the entire belt  14 ,  16  or  20  since the seaming operation takes place in end portions  22  and  24  the present invention is described, for purposes of clarity, as only treating end portions  22  and  24 . The treatment is applied so that the end portions become stiffer and are stiffened in a substantially linear fashion so that the end portions will properly align for more efficient seaming of the end portions together. 
     Once end portions  22  and  24  are seamed together the treatment agent is removed so that the water absorption characteristics and airflow characteristics in end portions  22  and  24  are not substantially different from the rest of belt  14 ,  16  or  20 . The removal of the treatment agent can be an incidental treatment of simply operating the papermaking machine causing the treatment agent to fracture and depart from belt  14 ,  16  or  20 . 
     The treatment agent may be a resin, such as polyvinyl acetate, phenoxy and/or may be a water-based treatment that imparts a stiff yet brittle characteristic to end portions  22  and  24 . The brittle property of the coating leads to a short-term life of the treating agent once the belt is cycled through the papermaking machine  10 . Since end portions  22  and  24  would be subjected to pressing pressures as well as bending moments the fracturing of the coating comes as a material with the operation of papermaking machine  10 . The stiffer end portions  22  and  24  are easier to install, and in general the seaming area is easier and faster to join together. 
     Fabric  14 ,  16  or  22  may be pre-stiffened in the manufacturing operation by application of the thermoplastic resin, and more particularly a phenoxy resin. The phenoxy is a high molecular weight thermoplastic polyether resin based on bisphenol-A and epichlorohydrin with bisphenol-A terminal groups. The agent may be a water base type treatment, thereby being cost effective to apply. The agent may be considered a sacrificial resin application that has a brittle nature once applied, which leads to a short-term life once installed on papermaking machine  10 . Once the treatment agent has been removed there is a permeability change of no more than 25% and preferably no more than 15% in end portions  22  and  24  as compared to untreated fabric in the rest of the fabric  14 ,  16  or  20 . The treatment agent utilized on end portions  22  and  24  retains a stiffness even in hot and high humidity storage conditions yet it is brittle and a temporary bonding with the textile substrate. When installed on the papermaking machine the treatment quickly shatters and dissipates when exposed to the press nip and cleaning showers so there is little risk of it changing any performance of the fabric nor does the treatment change how the fabric is constructed. The treatment agent creates a stiffness when dry, but is also largely hydrophobic. The phenoxy resin, such as PKHW-34, from InChem of Rockhill, S.C., may be sprayed at approximately 5-25% solids in the seam area, also known as end portions  22  and  24 . The quantity applied amounts to approximately 50 gsm of solids that are added on to the fabric. The treatment may be dried or cured at approximately 140° C. surface temperature with a 1.5 minute dwell time. End portions  22  and  24  may be approximately six inches in length across the full width of belts  14 ,  16  and  20 . 
     Alternatively, the agent can be applied as a powder or a scrim. The agent applied is then melted to the fabric to provide the stiffness and other characteristics noted herein. 
     The agent applied in the treatment of end portions  22  and  24  substantially maintains the stiffness of end portions  22  and  24  while the belt is in storage even though the storage may be for a prolonged period of time and the storage condition include a humid and/or moist environment. It is the nature of the agent used in the present invention that interacts with end portions  22  and  24  to maintain the stiffness, yet have the flexibility and permeability of end portions  22  and  24  restored once belt  14 ,  16  or  20  is utilized in the papermaking machine. The fracturing of the agent when cycled a few times in the papermaking machine causes the agent to separate from the fabric of end portions  22  and  24  and to no longer influence the operation of the belt. Subsequent washing of the belt also serves to remove portions not separated from the belt once it is fractured. The removal of the agent can be considered a dissipation of the agent, which means that the agent is not interacting with the fabric and is so incidental that the agent may simply leave the papermaking machine as a part of the product, part of the belt washings or when routine cleaning is done in the work area in which the belt is being used. 
     While this invention has been described with respect to at least one embodiment, the present invention can be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains and which fall within the limits of the appended claims.

Technology Classification (CPC): 3