Separate sheets of materials, such as fabrics, have been traditionally attached together for a variety of purposes using seams that were stitched or sewn into the fabrics. However, the stitching of seams into fabrics can be a relatively slow, expensive process that is undesired in some applications. Moreover, the use of sewn stitches may be completely undesired for certain types of materials, such as barrier fabrics, that require the seam area to also retain a barrier function.
Thus, in response to such problems, various other methods for attaching separate fabrics have been developed. For instance, various thermal methods that rely on the melting behavior of the fabrics have been utilized to produce seams. Specifically, the fabric and seam are heated to a certain temperature such that the materials of the fabric and seam begin to melt. Upon melting, thermal bonds are formed at the crossover points of the melted fabric and seam fibers. Other methods have also utilized adhesives, such as solvent-based liquid adhesives or glues. However, one problem with these techniques is that the seams are subject to stress fracture at low temperatures, and even at elevated temperatures, the divergent thermal melting points cause the resulting seam to be relatively weak.
In an attempt to improve strength, some methods have also utilized adhesive and/or thermal methods in conjunction with a conventional sewn seam. For instance, one such method includes sewing a seam, such as a lap seam or double-felled needle seam, between two fabrics. Thereafter, one piece of a tape is placed in its entirety only on the upper surface of the first fabric, while another piece of tape is placed in its entirely only on the lower surface of the second fabric. The tapes are then sealed under heat and pressure. Nevertheless, one problem with such a process is that it is relatively inefficient and costly. In particular, during manufacturing, a seam must be first sewn into the substrates and then the tapes are applied. Such multiple tasks add manufacturing costs and raw material costs. In addition, holes are often formed in the substrate by the needles during sewing. Although the tape can sometimes seal the needle holes, it is still possible that the fill-in might be incomplete. Unfortunately, the presence of any holes in a substrate can be undesirable for certain applications, such as when the substrate is used as a barrier fabric.
As such, a need currently exists for an improved method of forming a relatively strong seam between two or materials.