Patent Publication Number: US-2006016546-A1

Title: Method of producing woven webbing

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
      This is a continuation of PCT Serial No. PCT/EP2003/008311, filed Jul. 28, 2003, which claims priority to German Application No. 102 35 227.5-26, filed Aug. 1, 2002, both of which are incorporated by reference herein. 
    
    
     BACKGROUND AND SUMMARY OF THE INVENTION  
      The present invention relates to a method of producing woven webbing, particularly for vehicular seat belts, especially for use in motor vehicles, comprising warp threads, and at least one weft thread.  
      Methods of producing such webbing and the disadvantages of webbing produced as such are known in a wealth of variants. As a rule, the warp threads of such webbing are made of multifil yarns. Whereas for the weft thread(s) use is made solely of multifil yarns or solely of monofil yarns or combinations of monofil and multifil yarns. Making webbing exclusively with weft thread material of multifil yarn has the disadvantage that it features hardly any stiffness and elasticity in the cross machine direction (CD). Although webbing made of monofil material weft threads exhibits the necessary CD stiffness and elasticity, it has, however, the drawback that the monofil weft thread at its so-called reversals after critical wear and tear juts out from the edge of the webbing as sharp as a sawtooth profile which is damaging to the clothing of the vehicle occupant and injurious to trunk and neck locations. Apart from this, webbing made of monofil weft thread material is relatively bulky as compared to webbing made exclusively of multifil material.  
      The invention is based on the object of proposing a method of producing woven webbing which avoids, or at least greatly reduces, the disadvantages of prior art. This object is achieved by a method as set forth in claim  1 . This method has the advantage that working the multifil yarn weftwise now makes it possible to achieve the positive structures of the keying points in the weave. Each individual fibril of the multifil yarn consists of a core sheathed in a fusible skin. This yarn, simply termed “two-component yarn” hereinafter is woven weftwise and forms flexible elliptical and flat lying keying points in the shed end, which are unachievable with monofil yarns. In setting, after weaving, the multifil yarn is heated in accordance with the invention, resulting in the fibrils of the multifil yarn interbonding due to fusion of the fusible skin and the undulating multifil yarn melting into a uniform elastomeric monofil type yarn body in thus enhancing the CD stiffness of the webbing. 
    
    
     DETAILED DESCRIPTION  
      The process as described for engineering the mechanical properties—in achieving the desired CD stiffness and elasticity—occurs with the threads configured undulating, results in the thickness of the woven webbing being less and the surface of the webbing formed by the warp threads being smoother, because the tips of the keying points are less pronounced. As indicated above, an elliptically flattened soft reversal is now achieved in the edge portion when producing webbing in accordance with the invention due to the multifil yarn structure of warp and weft threads. Damage to the edges of the webbing resulting from abrasion of the selvedge now no longer results in the feared sawtooth effect and its possible negative consequences known from prior art.  
      In one advantageous aspect of the method in accordance with the invention the multifil, respectively its outlying fibrils, are additionally bonded to the warp threads interlacing them in the keying points in thermosetting, to now make it possible to achieve an even higher CD consolidation of the webbing. In another advantageous aspect of the method in accordance with the invention polyamide is used for the skin and polyester for the core, resulting in an optimal harmonizing marriage thereof in the webbing. In still another advantageous aspect of the invention polyester is used for both the skin and the core of the multifil thread of the warp thread. This has additionally the great advantage of enhanced recycling. Advantageously, the polyester skin in this case is made of an engineered polyester.  
      In textile sheeting made by thermally treating the two-component yarn at approx. 220° C. in the method in accordance with the invention the individual fibrils interbond such that a monofil yarn body having the mechanical properties (elastic response, low fluffiness, stiffness) of a monofil yarn is attained in the weft thread. Thus combines all positive features of multifil and monofil yarn in the method in accordance with the invention and in the product thereof. The method in accordance with the invention is compatible, of course, with all known types of webbing. The advantages now achievable for the first time are obvious: thinner webbing, smoother webbing surface, gentle reversals in the edge portion, elastic response, CD stiffness and a perfect surface finish. To advantage, multifil yarns are employed as the weft thread whose skin-to-core mass ratio is in the range of approx. 20%-80% to approx. 30%-70%.