Abstract:
A process for manufacturing a differential function, double-face fabric, comprises the steps of a) providing two different yarns, the first yarn exhibiting hydrophilic behavior and the second yarn exhibiting hydrophobic behavior; b) providing a knot yarn; and c) producing a fabric by simultaneously weaving said two yarns, and linking them with said knot yarn.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates to the manufacture of a novel differential-function woven clothing article. More particularly, the invention relates to a breathable fabric comprising a water-repellent hydrophobic external layer, and internal hydrophilic layer, wherein water or sweat moisture is diffused out through the internal layer. The invention further relates to garments made of such fabric.  
       BACKGROUND OF THE INVENTION  
       [0002]     Clothing fabrics may be produced for various objectives and needs. Traditionally, it is common in the art to provide formal and casual garments for outwear as monofunctional fabrics which have one dominant property, for example; heat retention or wind protection provided by natural or synthetic yarns of weaves and knits. Another traditional approach is to provide fabrics with additive function; to improve the functionality of fabrics by the application of various chemicals/polymers and by adding certain features to the garment, for example: water repellence, antibacterial or UV protection, flame retardancy, shrink-proofing, etc.  
         [0003]     Another common approach is to modify the fabric properties by coating or lamination by using various polymers. However, fabric that is single-layered, may offer only one function, or additive functions, but not contrasting chemical function such as hydrophobicity and hydrophilicity. A known method used to achieve such result is to provide a multilayer fabric by introducing a membrane between two layers, leading to different functionality of the two sides of the multilayer fabric.  
         [0004]     U.S. Pat. No. 5,787,503 teaches the joining together of two different layers, one hydrophobic and the other hydrophilic, by knitting, to form a double-layer sweater, wherein the linking between the two layers is a polygonal-shaped quilting stitch pattern forming insulating pockets between the layers. The purpose of this configuration is to manufacture a sweater that keeps the wearer dry as well as warm.  
         [0005]     A different approach for a double-layered garment is described in U.S. Pat. No. 6,128,783, which teaches the production of a reversible sweater having one layer composed of knit fabric, and the other of micro-fiber fabric. According to this patent, the wearer may select which side of the sweater to wear according to weather conditions.  
         [0006]     The use of a dual-function garment has been considered also for medical applications. U.S. Pat. No. 6,148,444 discloses the use of a sweater for hemodialysis patients. According to this patent, the sweater is warm and keeps the patient dry at the same time, and contains a series of openings that will allow access to grafts or fistulas, as well as catheters, during medical procedures.  
         [0007]     It is a purpose of the present invention to provide a combination of desired properties in a garment generating a double-layered fabric, without introducing any membrane between the two layers, choosing two compatible layers, wherein one face of the fabric has a desired property, and the other has a different desirable property, and then superimpose the two layers together.  
         [0008]     It is another purpose of the present invention to provide an outwear that combines desired properties in a comfortable, economic and simple to manufacture manner.  
         [0009]     It is still another purpose of the invention to provide a two-layered fabric, comprising an external face, designated as face-side, made from wool alone or wool wrapped with nylon or cellulosic yarn, and an internal layer, designated as back-side, made from polyester. The face-side is water-repellent, and prevents permeability of water droplets inside the fabric while the back-side is hydrophilic, water-absorbent allowing the perspiration to diffuse through the fabric outside, and then to evaporate.  
         [0010]     It is a further object of the invention to provide a breathable fabric, moving moisture away from the skin.  
         [0011]     It is a further object of the invention to provide a process for the manufacture of a light clothing or garment possessing the above mentioned properties.  
         [0012]     Other purposes and advantages of this invention will become apparent as the description proceeds.  
       SUMMARY OF THE INVENTION  
       [0013]     The invention relates to a process of manufacturing a differential function fabric, which can be further used to prepare a breathable garment, which can aid moisture evaporation from the skin. In one aspect, the invention is directed to the preparation of a double face fabric comprising the steps of dyeing, chemically treating two different yarns, simultaneously weaving the yarns in a warp and weft, and linking them by a knot yarn. The knot yarn is preferably—but non limitatively—made from nylon 66.  
         [0014]     According to a preferred embodiment of the invention, the first of the two yarns is made from wool alone, or from wool wrapped with nylon 66 filament, or cellulosic yarn, or wool wrapped with covered elastane or cellulosic yarn with elastane.  
         [0015]     In this specification, the term “elastane” (also known as “Spandex”) is used to designate man-made elastic fiber, consisting of polyester diol, or polyether diol with diisocyanate.  
         [0016]     According to another preferred embodiment, the second yarn is made from spun or filament polyester selected from polyethyleneterephthalate (PET), polymethyleneterephthalate (PTT), or polybutyleneterephthalate (PBT).  
         [0017]     According to a preferred embodiment of the invention, a double face fabric which has differential functionality is provided, comprising two layers, a face side which is hydrophobic and water-repellent, and a back side which is hydrophilic, and water-absorbent.  
         [0018]     Preferably, the face side is wool or wool-based or cellulosic-based, and the back face is polyester. According to another aspect of the invention, the wool yarn or cellulosic yarn is treated with fluorocarbons, and the polyester yarn is treated with polysiloxanes.  
         [0019]     The invention will be further understood through the following illustrative and non-limititative examples. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0020]     In the drawings:  
         [0021]      FIG. 1  is a flow-chart of the manufacturing steps of a differential-function fabric;  
         [0022]      FIG. 2  is a schematic illustration of a cross-section of a double-layer fabric. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0023]     As stated, the invention relates to a process for the manufacturing of a fabric comprising two layers, to a fabric made thereby and to breathable garments made of the fabric.  
         [0024]     In order to achieve the desired effect, a fabric is produced from two different yarns through spinning, weaving, dyeing and chemical treatments, and through the weaving process these two layers are knotted by a third yarn to produce the desired product. The production steps of an illustrative and non-limitative process are schematically illustrated in  FIG. 1 , and are as follows: 
        a) A fabric consists of two basic yarns  1  and  2  each made from a different material (in the example of  FIG. 1 , wool and polyester);     b) The knot yarn is made from a third material  3 , which can be the same as, or different from, the material of yarn  2 ;     c) All three yarns are dyed ( 4 ) separately by known methods for wool, polyester and nylon;     d) The two yarns are woven together ( 5 ) in a double-face weave, in a warp and weft fashion, and are joined simultaneously by knot yarn  3 , which combines the warp yarns and introduce it into the weft direction in a certain sequence to form woven fabric  5 ;     e) The woven fabric is then processed through a finishing step ( 6 ), consisting, e.g., of wet treatment of the fabric through washing, drying and continuous decatizing steps;     f) A light double-layered garment ( 7 ) is made from the fabric by methods known in the art.        
 
         [0031]     The wool yarn used in the present invention can be a yarn made from wool alone, or wrapped with nylon, particularly nylon  66  or can be made from cellulosic yarn. The polyester yarn can be made of any suitable polyester, and is preferably, but non limitatively, made of polyethyleneterephthalate (PET). The wool yarn or cellulosic yarn serves as the face-side of the fabric, and the polyester yarn is provided for the back-side of the fabric.  
         [0032]     According to a preferred embodiment of the invention the wool yarn is dyed in an acid dye bath at about 100° C. (or any other suitable temperature) with an acid dye, or the known metal complex 1:2 dyestuf, or by a reactive dyestuff, such as alpha-bromoacrylamide, or vinylsulfone derivatives, followed by cleaning in order to improve the wet fastness properties of the yarn, and then rinsed with water.  
         [0033]     According to a preferred embodiment of the invention the cellulosic yarn is dyed in an alkaline bath mainly with cold or warm reactive dyes (mono or bifunctional dyes) at a temperature range of 50° C. -80° C., followed by multiple rinsing and soaping cycle to improve the wet fastness properties of the yarn.  
         [0034]     In order to achieve the desired water-repellency of the final product, it is important to chemically treat the wool or cellulosic yarn. This is obtained by immersing the wool or cellulosic yarn in a water bath, and then by adding 4-5 wt % of a fluorocarbon derivative. In an illustrative and non-limitative process this step is carried out at about 40° C. for about 20 minutes, and then the solution is drained. Thus, by this process, the yarn becomes hydrophobic. The yarn is checked for hydrophobicity by methods known in the art, which are not discussed herein, for the sake of brevity.  
         [0035]     The polyester yarn is scoured prior to the dyeing process by immersion in a solution of a mixture of non-ionic surface-active material and soda ash. In an illustrative and non-limitative process the solution is then heated to about 60° C. at a rate of 2° C. per minute, and kept under such conditions for about 20 minutes.  
         [0036]     The scouring removes the majority of the spin finishes and waxes formed in the spun polyester yarn. The yarn is then dyed in a dyeing bath, at 115-130° C. by employing cationic/disperse dyestuffs.  
         [0037]     In order to achieve a better water-permeability of the polyester yarn, it is important to increase its hydrophilicity. This can be done by immersing the polyester yarn in a solution of 4-5 wt % of a functional polysiloxane derivative, prepared at ambient temperature. In an illustrative and non-limitative process the treatment is carried out at about 40° C. for about 20 minutes, and the solution is then drained. Finally, the yarn is checked for its hydrophilicity and absorbency by methods known in the art.  
         [0038]     The knot yarn is made from polyamides, preferably (but non limitatively) from Nylon 66, and it is scoured prior to dyeing as described previously. The dyeing is performed typically by a mixture of metal complex 1:2, or an acid dyestuff. The dyeing is typically carried out at about 100° C. In order to achieve dark shades, the nylon yarn is fixed, by immersing it in a solution of 2-3% on weight of fiber (owf) of a fixative agent, in an acetic acid medium at pH 5. In an illustrative and non-limitative process the fixation step is carried out at about 50° C., for about 20 minutes. Finally, the solution is drained. Since the fixation can sometimes interfere with the wicking force of the yarn, it is desirable to monitor this property, following the completion of the fixation.  
         [0039]     The wool or cellulose and the polyester yarns are then woven on the Rapier looms to form a double-layered fabric. The two layers are linked together by the nylon knot yarn that combines the warp yarns of the two layers, introducing it into the weft. In order to achieve a fabric (constructed from wool and polyester) that is machine-washable, the wool fiber can be treated by subtractive antifelt finish, for applications like oxidizing agents, and/or by additive antifelt finish (of polymers such as, polyurethanes, polysiloxanes).  
         [0040]     The scouring process of the fabric consists of the application of 1-2 wt % non-ionic surfactant and is typically carried out at about 60° C., in an open-width washing machine having several compartments at an illustrative fabric speed of 15 m/min. It is important to dry the fabric at a temperature of less than 110° C., since higher temperatures may induce change in the fabric color and affect the functionality of the fabric. The process is been finalized by continuous decatizing. This step is carried out in a decatizing machine, which does not contain metal surfaces.  
         [0041]      FIG. 2  schematically illustrates a cross-section of the formed double-layer fabric, in which the face-side  21  is hydrophobic, thus causing it to repel water in the direction indicated by arrow  22 , and the back-side  23  is hydrophilic, water-absorbent, causing body moisture to diffuse out through the two layers, in the direction indicated by arrow  24 , and then to evaporate. The two layers of the fabric are linked together by knot yarn  25 .  
         [0042]     According to a preferred embodiment of the invention, a wool or cellulosic yarn is woven together with a polyester yarn, and a knot yarn made of nylon is used to link the two yarns, to produce a double-layered fabric, in which the fabric external face is a wool or cellulosic layer, while its internal face is polyester, and these layers are knotted together by the nylon yarn.  
         [0043]     The following examples serve to illustrate the invention, and are not intended to limit it in any way.  
       EXAMPLE 1  
       [0044]     A double-layer fabric with differential functionality was manufactured by the procedures described above, using the following conditions:  
         [0045]     The weave was: double face plain weave, color woven, rigid fabric. Fabric weight was 200 gr/m 2 .  
         [0046]     The fabric composition was: 50% wool, 41% polyester, 9% nylon 66.  
         [0047]     The yarns were as follows: first yarn: worsted wool yarn, count 40/1 Nm. This yarn was wrapped with nylon 66 filament, 11 dtex at 880 turns per meter (tpm). The wool micron was 20.5  
         [0048]     The second yarn was made from polyester (Dacron 702, Coolmax Ex. Dupont) with yarn count of 50/1 Nm. The two yarns were woven together with a knit yarn, polyamide 66. The knot was introduced in the weft and combined with warp yarns.  
       EXAMPLE 2  
       [0049]     A double-layer fabric, weft stretch was manufactured by the procedures described above, using the following conditions:  
         [0050]     The weave of the fabric; double face plain weave with weft stretch. The fabric weight was 220 gr/m 2 .  
         [0051]     The fabric composition was: 58% wool, 37% polyester, 2% elastane, and 3% polyamide.  
         [0052]     The yarns were: in the warp direction: worsted warp wool yarn count 40/1 Nm. This yarn was wrapped with nylon 66 filament at 880 turns per meter (tpm). The second yarn was polyester, Dacron 702 in a yarn count of 50/1 Nm at 1270 tpm. The knot yarn, polyamide 66, 78 dtex was used to combine the two yarns in the weaving step.  
         [0053]     Weft direction: the weft consisted of wool yarn, 40/1 Nm and polyester yarn, 50/1 Nm. Both yarns were wrapped with elastane.  
       EXAMPLE 3  
       [0054]     A bistretch double layer fabric was manufactured by the procedures described above, using the following conditions:  
         [0055]     The weave of the fabric was double face plain weave with bistretch elasticity.  
         [0056]     The fabric weight was 265 gr/m 2  and the fabric composition: 60% wool, 35% polyester (Dacron 702), 11% nylon 66, and 4% elastane.  
         [0057]     Yarns in a warp and weft as follows: worsted wool 40/1 Nm wrapped with elastane and polyester 50/1 Nm wrapped with elastane.  
         [0058]     While embodiments of the invention have been described by way of illustration, it will be understood that the invention can be carried out by persons skilled in the art with many modifications, variations and adaptations, without departing from its spirit or exceeding the scope of the claims.