Abstract:
A method of treating hemp fiber and yarn by partially impregnating the hemp fibers with treating compositions is disclosed. The treating compositions are water-based or organic solvent-based and may contain true soaps, starches, waxes, polyalkalene resins or another chemical that demonstrates the ability to provide the advantages listed herein. The key to the present invention is the partial impregnation of the hemp fibers and yarns, which are also part of the invention.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]    This utility application claims priority of Provisional application No. 60/279,958, filed Mar. 29, 2001. 
     
    
     
       BACKGROUND  
         [0002]    1. Field of the Invention  
           [0003]    This invention relates to a method of treating hemp fibers and yarns with a variety of different treating compositions chosen to improve their useful qualities. It also relates to the resultant fibers and yarns.  
           [0004]    2. Description of Prior Art  
           [0005]    Historically, hemp has proven to be a versatile and durable substance. As a crop, it is low-maintenance and resilient, and requires none of the weeding and heavy use of pesticides usually required in farming. The resulting plant has literally tens of thousands of uses ranging from textiles to paper and foodstuffs. Oil derived from hemp seeds can be used in cosmetics, paints, sealants, and even the manufacturing of plastics. Hemp is particularly effective as a source for textiles. The fibers drawn from the hemp plant are the strongest and longest in nature. Fabrics, twines, yarns and cords made from hemp are durable and versatile. It can be combed into any gauge or quality of fiber. As a substitute for such diverse substances as cotton, trees, or petroleum, hemp proves to be more environmentally sound than all of its alternatives and its versatility and resilience make it economically sound as well.  
           [0006]    Hemp has been under-appreciated heretofore as a viable alternative to cotton, cellulosic or petroleum-based products, possibly as a result of its connotative association with marijuana. Hemp fiber itself, however, is not psychoactive and is surprisingly useful as a cotton, paper, cellulosic or polymer substitute when it is treated according to the present invention. Apart from the present treatment, however, hemp fiber is characterized by undesirable susceptibility to moisture and rot due to molds and mildews and the like. Hemp fiber is also characterized by a strong, naturally-occurring odor which makes it unacceptable as a substitute for other odorless fibers. Moreover, hemp fiber in its natural spun state is susceptible to fraying and has a rough hand and feel. A need therefore remains for a hemp product which is suitably strong, soft, flexible, moisture-resistant and rot-resistant and generally suitable for substitution in applications previously focused on the cotton, paper and petroleum-fiber industries.  
         SUMMARY OF THE INVENTION  
         [0007]    In order to meet this need, the present invention is a method for treating hemp fiber by partially impregnating the hemp fiber with a treating composition. The treating composition may be selected from the group consisting of true soaps, starches such as amylose, waxes such as paraffin and/or polyalkalene resins including polyfluoroalkalene (i.e., polytetrafluorethylene), depending on the desired qualities of the finished product. Regardless of the impregnant chosen, the key to the present invention is the partial (rather than the complete) impregnation of the hemp fiber. Partial impregnation not only retains the desirable characteristics of the hemp such as breathability, natural hand and feel and maintenance of elasticity and flexibility, but it also increases water resistance, masks odor, and controls fraying. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0008]    The present invention is a method for treating hemp fiber by partially impregnating the hemp fiber with a treating composition. The treating composition may be selected from such impregnants as true soaps, starches such as amylose, waxes such as paraffin, polyalkalene resins including polyfluoroalkalene (i.e., polytetrafluoroethylene) and other impregnants as may be apparent to those skilled in the art. Although certain impregnants are more preferred than others, the key to the present invention is the partial (rather than complete) impregnation of the hemp fiber. Partial impregnation not only retains the desirable characteristics of the hemp such as breathability, natural hand and feel and maintenance of elasticity and flexibility, but it also increases water resistance, masks odor, and controls fraying. The partial impregnation with the treating substance also increases the already considerable strength of the hemp fibers.  
         [0009]    The term hemp generally embraces any fibers derived from plants of the genus Cannabis, but for the purpose of the present invention can be understood further to embrace any bast fiber such as Manila Hemp, sisal and/or jute. In the preferred embodiments of the present invention, however, the hemp fibers are derived from Cannabis and more preferably are derived from  Cannabis sativa  1.  
         [0010]    Generally central to the partial impregnation of the hemp fiber is the use of a treatment bath of the impregnant rather than any direct coating of the hemp fiber with the pure impregnant. For example, a treating composition of water, 20% paraffin emulsion, 0.01-10% zirconium ion and 0.01-20% acetic acid may be used as a treating bath for hemp fibers, which are dipped in the treating bath and allowed to cure or dry at ambient temperatures in air. The use of the treating bath with the paraffin emulsion causes partial impregnation of the hemp with the paraffin but does not create a solid paraffin coating over the hemp fiber. In this fashion, the hemp retains its characteristic hand and feel, as well as substantially all of its unique appearance, but the partial impregnation with the paraffin provides the desired water resistance, etc. Alternative treating solutions include polyethylene, polypropylene, and polyfluoroalkylenes, including but not limited to, polyfluoralkylene, Other impregnants can include industrial soap (true soap), starches such as amylose or waxes such as paraffin, carnauba wax, tallow, etc.  
         [0011]    As a general matter, the preferred embodiments of the invention incorporate a 20% emulsion of the wax or polymer to be used to partially impregnate the hemp fiber in an aqueous bath including additional ions as desired. However, the amount of treating composition in the bath can range from about 5% to about 80% of the bath and the bath itself may incorporate emulsions of more than one material. Although aqueous or emulsion treatment baths are preferred, any method of partially impregnating the hemp fibers falls within the scope of the present invention. Polytetrafluoroethylene is a particularly preferred treating composition.  
         [0012]    In a preferred embodiment, a hemp yarn was temporarily submerged in a treating composition (bath) composed of 20% fluorocarbon resin with trace amounts of isopropyl alcohol and acetic acid in with the remainder of the heated bath composed of water. This trial run produced a yarn that demonstrated exceptional resistance to water.  
         [0013]    The present invention should be contrasted with prior art methods of polishing yams. Heretofore it has been known to use aqueous emulsions of waxes and other treating compositions as a final polishing or finishing treatment for yams of many types. In the most preferred embodiments of the present invention, the partial impregnation of the hemp fiber is accomplished, usually with an aqueous emulsion treating bath, prior to the initial spinning of the individual yams and/or prior to the twisting of multiple plies of yam into twine. Notwithstanding the above, it is to be understood to be within the scope of the present invention to accomplish partial impregnation of the twine with the treating material even after the twine is twisted. The use of elevated pressure, heat or organic solvents such as acetone, may be employed to enhance the impregnation of the hemp with the treating composition. Ordinarily, although not necessarily, when previously twisted twine is treated after twisting, the impregnating substance will be a fluorocarbon resin in an organic solvent such as acetone.  
         [0014]    Hemp as treated according to the above partial impregnation methods has a wide variety of uses. It can substitute for wicker or caning in the furniture and other industries. The treated hemp has reduced or eliminated odor and is therefore acceptable in a wide variety of upholstery or other interior or exterior design applications. Treated hemp according to the present invention may be incorporated in canopies, tents, shower curtains, stain-resistant pillows, window treatments, vehicle upholstery, and luggage, carpets, rugs, ground cover, agricultural textiles, and other applications in which natural products having water resistance and durability are desired. Therefore, in addition to the above, the present fibers, yams and twines are suitable for use in clothing, apparel, accessories, machine loomed and hand woven and loomed garments, jewelry applications, awnings, military field personal clothing and armament protection applications, general upholstery, personal bedding, household furniture, canvas for paintings, and other general textile applications, without limitation.  
         [0015]    It is understood that the above-described embodiments of the invention are illustrative only and modifications thereof may occur to those skilled in the art. Accordingly, it is desired that this invention not be limited to the embodiments disclosed herein but is to be limited only as defined by the appended claims and their legal equivalents.