Enhanced Thickness Fabric and Method of Making Same

Abstract

The present invention provides thickened fabrics and reinforcements for use as a spacer or reinforcement for a matrix system. The fabric includes in a first embodiment a woven fabric comprising weft and warp yarns containing glass fibers. A portion of the weft yarns are undulated into a sinusoidal path forming a generally “C” shaped bridge between adjacent warp yarns which results in an increased thickness for the fabric. The fabric is coated with a polymeric resin or bonding agent, for substantially binding the weft yarns in the undulated condition. This invention also includes methods for making such fabric by increasing the thickness of a woven or non-woven material by such methods as applying tension to warp yarns having opposite twists during weaving operations, or using unbalanced yarns, for example.

1 . A fabric comprising:
 an open woven layer including interwoven warp and weft yarns, wherein at least a pair of adjacent ones of said warp yarns are provided with the same twist directions, said adjacent warp yarns being mechanically manipulated to at least partially untwist said adjacent warp yarns, whereby a weft yarn disposed between said adjacent warp yarns forms a curved sinusoidal path having a generally “C” shaped configuration bridging said adjacent warp yarns and providing increased thickness to said fabric; and   a polymeric coating disposed over at least a portion of said warp and weft yarns so as to retain said generally “C” shaped configuration.   
   
   
       2 . The fabric of  claim 1  wherein said warp and weft yarns comprise polymeric fibers, inorganic fibers, or both. 
   
   
       3 . The fabric of  claim 1  wherein said weft and warp yarns comprise glass fibers. 
   
   
       4 . The thickened fabric of  claim 1  wherein said weft fibers are mechanically manipulated to increase the layer's thickness by at least about 50%. 
   
   
       5 . The fabric of  claim 1  wherein said weft yarn forms one full wave length between alternating warp yarns beginning and ending approximately at warp yarn intersection points. 
   
   
       6 . A corrosion-resistant fabric for use as a reinforcement in a matrix, comprising:
 a woven, braided, scrim-type or knitted open fabric comprising high strength, non-metallic weft and warp yarns, whereby a portion of said weft yarns are mechanically manipulated to form a generally “C” shaped bridge between adjacent warp yarns, said bridge increasing the fabric's thickness by at least about 50%, and a bonding agent for retaining said weft and warp yarns in a relatively fixed position.   
   
   
       7 . The fabric of  claim 6  wherein said fabric comprises a leno weave. 
   
   
       8 . The fabric of  claim 7  wherein said weft and warp yarns are spaced apart by at least about 1 mm. 
   
   
       9 . The fabric of  claim 7  wherein said adjacent warp yarns are twisted in opposite directions. 
   
   
       10 . The fabric of  claim 7  wherein said warp yarns are subjected to a tensile force which assists in causing said weft yarns to become undulated to a height of at least 1 mm. 
   
   
       11 . The fabric of  claim 7  wherein said warp yarns have a combined weight which is greater than the combined weight of the weft yarns. 
   
   
       12 . The fabric of  claim 7  wherein a portion of said warp yarns are heavier than a portion of said weft yarns, said warp yarns are fewer in number than said weft yarns, or both. 
   
   
       13 . A matrix reinforcement comprising:
 an open, woven fabric comprising interwoven weft and warp yarns whereby a portion of said weft yarns are undulated into a curved sinusoidal path having inflection points located substantially only at intersection points with said warp yarns, resulting in an increased thickness for said fabric;   said fabric coated with a polymeric resin for substantially binding said weft yarns in said undulated condition.   
   
   
       14 . The reinforcement of  claim 13  wherein said polymeric resin comprises styrene butadiene rubber, acrylic, styrene acrylic, or combinations or derivatives thereof. 
   
   
       15 . The reinforcement of  claim 14  bonded to a matrix comprising an organic or inorganic material. 
   
   
       16 . The reinforcement of  claim 14  wherein said undulated weft yarns comprise a substantially regular sinusoidal-like pattern forming a full wave length between alternating ones of said warp yarns. 
   
   
       17 . The reinforcement of  claim 14  wherein adjacent ones of said weft yarns of said fabric have different sinusoidal-like patterns which are not overlapping when observed from the plane of the fabric. 
   
   
       18 . A method of making a fabric having increased thickness comprising:
 (a) providing a scrim-type, braided, woven or knitted open fabric comprising interwoven weft and warp yarns containing glass fibers, adjacent ones of said warp yarns having oppositely disposed twists;   (b) applying a tensile force to said warp yarns, whereby a portion of said weft yarns become undulated in a generally “C” shaped configuration between adjacent warp yarns, resulting in an increased thickness for said fabric; and   (c) binding said fabric with a bonding agent whereby said undulated weft yarns become substantially fixed.   
   
   
       19 . The method of  claim 18  wherein said providing step (a) provides weft and warp yarns containing different weights, different numbers of fiber, or a combination thereof. 
   
   
       20 . The method of  claim 19  wherein said binding step (c) comprises applying said bonding agent to at least the cross over points between said weft and warp yarns. 
   
   
       21 . The method of  claim 19  wherein said applying a tensile force step (b) comprises employing a tenter frame to apply tension to said warp yarns. 
   
   
       22 . The method of  claim 21  wherein said binding step (c) occurs at least partially during the time said warp yarns are in tension.