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Paper machine fabric with release coatingPaper machine fabric with release coating description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20070167099, Paper machine fabric with release coating. Brief Patent Description - Full Patent Description - Patent Application Claims
CROSS REFERENCE TO PROVISIONAL APPLICATION [0001]This application claims the benefit of the filing date of provisional patent application 60/759,650 filed Jan. 17, 2006. BACKGROUND OF THE INVENTION [0002]The present invention relates to paper machine fabrics. Paper machine fabrics are conventionally used in the manufacture of paper towels, facial tissue, bathroom tissue, table napkins and the like. [0003]U.S. Pat. Nos. 6,017,417 and 6,331,230 and Publication WO 01/44568 describe the manufacture of tissue and the like using through-air drying. Typically, in such processes, a slurry of cellulosic fibers is fed onto a forming fabric or between two forming fabrics, where the paper web is formed and partially dewatered before the web is transferred, often via a transfer fabric, to a through-air drying (TAD) fabric for further water removal by way of one or multiple TAD units. The web is then fed by way of the TAD fabric to a presser roll where a nip is formed between the TAD fabric and a Yankee cylinder. Here the paper web transfers to the Yankee cylinder where further drying and creping takes place. In one variation of this process, the Yankee cylinder is removed, thus eliminating the pressing nip. In this case, the web is transferred from the TAD fabric to a further fabric. [0004]It is conventional to spray a chemical release agent, e.g. silicone oil onto the paper machine fabrics in order to provide good sheet release, whether it be to aid the transfer of the sheet on to another fabric or on to the Yankee cylinder, after exiting the presser roll nip. There are a number of potential problems associated with using a chemical release agent in the TAD process, two of these being that they are messy to utilize and very expensive. [0005]A significant problem with the use of a chemical release agent is the fact that the agent remains in the recycled white water system. Most modern paper machines tend to have closed water systems, and so the water that is removed from the cellulosic stock during the papermaking process and the reclaimed fabric shower water is collected, recycled and then reused as shower water and also to dilute the new cellulosic stock. In the interim period, the water is stored in holding tanks. In these tanks, minute beads of chemical release agent coalesce into larger globules. It is extremely difficult to separate the chemical release agent from the water and the globules end up coating these tanks, which finally make their way back into the system. When the globules find their way into the cellulosic stock, there are potentially a number of problems, all of which result in a reduction of paper quality and machine operating efficiency. [0006]Another approach to improve release is to coat the fabric, and typical coatings include thermoset polyurethane (TPU), hydrophobic materials and the like. [0007]It is clear that the need remains for an environmentally friendly system which can be applied to paper making machine fabric and other belts or rolls to improve release behavior without adversely impacting other performance attributes. SUMMARY OF THE INVENTION [0008]According to the invention, the foregoing need has been met. [0009]According to the invention, a paper machine fabric is provided which comprises a fabric having a roll side and a paper side and a surface matrix on the paper side; and a chrome complex treatment on the surface matrix. The chrome complex treatment serves to enhance release properties of the fabric without requiring sanding of the fabric and without using materials which interfere with the complex paper system and/or the paper making machine itself. Further, the treatment is applied in a water based system, and chemically reacts with the surface of the fabric. [0010]According to the invention, the chrome complex treatment can preferably be an organic metal complex, preferably a fatty acid metal complex. BRIEF DESCRIPTION OF THE DRAWINGS [0011]A detailed description of preferred embodiments of the present invention follows, with reference to the attached drawings, wherein: [0012]FIG. 1 schematically illustrates a fabric having a coating according to the invention. DETAILED DESCRIPTION [0013]The invention relates to fabric for papermaking machines and, more particularly, to a treatment for such fabric which improves the release properties of the fabric. [0014]The treatment according to the invention is applied to the paper side of a fabric, preferably a fabric 10 having a base 12 and batt layers 14, 16 attached at each side of base 12. A surface matrix 18 can be attached to or otherwise defined on a surface of batt layer 14, and the treatment 20 according to the invention is preferably applied at least to surface matrix 18. [0015]According to the invention, the surface treatment comprises a water based system containing a chrome complex. One example of particularly suitable chrome complexes is a family of products marketed by Dupont under the trademark Quillon.RTM., certain examples of which include chromium pentahydroxy(tetradecanoato)di-; tetradecanoato chromic chloride hydroxide; octadecanoato chromic chloride hydroxide and others. [0016]The treatment composition can be applied in relatively low concentrations, for example at concentrations of less than 10% volume, preferably at concentrations of less than 2% volume. The composition can be applied using known techniques such as spray or kiss roll application. After application to the fabric, the composition is preferably dried and cured, preferably at a temperature of about 100.degree. C. plus or minus about 50.degree. C. This leads to chemical reaction of the composition with the fabric which leads to desirable release properties of the fabric. It is believed that the composition reacts with the polar groups of the fabric, and when cured the complex forms an insoluble layer of a polymerized chromium network chemically bonded to the substrate. Hydrophobic fatty acid chains of the composition are left oriented away from the surface of the substrate, giving rise to a unique and unexpected release property. [0017]The treatment according to the present invention can advantageously be applied to various papermaking machine clothing or fabric and other industrial fabrics, for example including forming fabrics, press fabrics, impermeable press belts, dryer fabrics, TAD and other industrial fabrics, and can be applied to rolls and sleeves. [0018]The composition of the present invention can also be engineered with other aqueous polymer systems such as poly vinyl alcohol (PVA) or poly vinyl acetate (PVAc) to provide control over surface energy, wetting behavior and the like. [0019]A particular advantage of the present invention is that the fabric does not need to be sanded or ground or otherwise treated in a potentially harmful way in order to apply the composition. Continue reading about Paper machine fabric with release coating... Full patent description for Paper machine fabric with release coating Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Paper machine fabric with release coating patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. 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