Patent Application
20050188907
My invention relates to an improved garment seam and method for making the seam. More specifically, the improved seam of my invention is bonded together with a molten polymer because the method of my invention uses a low melt sewing thread as one of the threads used to sew the seam. Upon heating the finished seam the low melt thread melts and bonds the garment fabric together. It also coats and bonds the conventional high melt sewing thread, which is sewn in conjunction with the low melt thread, to the fabric and thus prevents unraveling of the stitch. My invention can be used in any garment seam, including the side and French seams of a dress shirt or in trouser seams or in skirt hems or in any article made of fabric.
Bonding of seams using molten polymers is known to the art of garment manufacturing, as exemplified by U.S. Pat. No. 6,079,343. This patent teaches the placement of an adhesive strip or tape inside the seam before the seam is sewn with conventional high melt threads in an attempt to produce a shirt garment with seams that are pucker-free. The patent teaches that after the tape is melted, the adhesive bonds the fabric in the seam to produce a smooth and pucker free seam even after multiple laundering operations. Unfortunately, the use of such an adhesive strip not only adds additional material cost to the manufacture of garments, it significantly increases the “standard minute value” associated with the manufacturing process. This value is a measure of the man hours it takes to assemble a garment. Higher values translate directly into higher manufacturing costs. Manufacturers work very hard to reduce the standard minute value associated with a particular garment's construction. Another drawback when using the adhesive strip is the extra time it takes the sewing machine operator to position and align the strip in the seam. In essence, this is an extra or separate manufacturing step.
Another limitation of the adhesive tapes or strips used in prior art processes is that when they melt the adhesive only bonds fabric to fabric. There is no way for the molten polymer to coat the conventional high melt sewing threads used to stitch the seam, let alone cause these threads to bind directly to the seam fabric. As such, the prior art tape cannot prevent or reduce “stitch run back,” which is one cause of high “return to manufacture” (RTM) values associated with a garment's manufacture. Like the standard minute value, a high RTM is not desirable in that it results in increased cost to the manufacturer. “Stitch run back” occurs when a stitch is missed during the sewing of a seam or hem and the stitch begins to unravel, thus causing the seam to fail. Yet another disadvantage of the adhesive tape is the degree of difficulty in placing it in small diameter seams, such as in a French seam or a trouser seam. Because of the stiffness of the tape, it is very difficult to align the tape to follow the tight radius of curvature of such seams without causing the tape to bunch.
Clearly, the art is in need of a low cost and efficient solution to form strong, pucker-free seams in garments without the attendant disadvantages of adhesive tape and further that reduces the RTM for a given garment.
It is therefore a general object of my invention to provide a garment seam, especially the side or French seam regions of a dress shirt or the hems on trousers or skirts, and a method for making the seam which will obviate or minimize difficulties of the type previously described.
It is a specific object of my invention to provide a garment seam and method for production which will reduce the standard minute values of garments and that will produce a pucker-free seam.
It is another object of my invention to provide a pucker-free garment seam and a method of production of the seam which lowers RTM values.
It is still another object of my invention to provide a strong garment seam and method for production that can withstand numerous laundry cycles and prevents accidental seam failure.
It is yet another object of the invention to provide garment side and French seams and a method for production which provides for a cost effective solution to the disadvantages associated with the use of adhesive tapes and strips.
Finally, another object of my invention is to provide a means to the bond conventional high melt sewing thread that is used to stitch the seam to the fabric in the seam to prevent stitch run back.
Accordingly, my invention is directed to an improved garment seam whereby a combination of low melt sewing thread and conventional high melt sewing thread is used in a sewing machine to stitch the seam together. Once the seam is sewn together with the combination of low and high melt threads, the seam is subjected to a sufficient amount of heat, and if needed, pressure, to cause only the low melt thread to soften and melt. The melted thread behaves like an adhesive as it flows over the surfaces of fabric in the seam thereby permanently bonding first and second garment components together along the seam. The melted thread also coats and bonds the high melt sewing thread to the fabric, which then prevents and significantly reduces stitch runback. My invention also relates to an improved method for creating a seam that is durable, pucker-free, and resists accidental failure. The method involves stitching the seam using at least one low melt sewing thread in combination with at least one high melt sewing thread, and then subjecting the seam to a heating step to melt the low melt thread so that it bonds the fabric and the high melt thread together as well as bonding fabric to fabric.
Other objects and advantages of the present invention will become apparent from the following detailed description of preferred embodiments thereof taken in conjunction with the accompanying drawings, wherein:
The term “fiber” as used herein refers to a fundamental component used in the assembly of yarns and fabrics. Generally, a fiber is a component which has a length dimension which is much greater than its diameter or width. This term includes ribbon, strip, staple, and other forms of chopped, cut or discontinuous fiber and the like having a regular or irregular cross section. “Fiber” also includes a plurality of any one of the above or a combination of the above.
The term “filament” as used herein refers to a fiber of indefinite or extreme length such as found naturally in silk. This term also refers to manufactured fibers produced by, among other things, extrusion processes. Individual filaments making up a fiber may have any one of a variety of cross sections to include round, serrated or crenular, bean-shaped or others.
The term “yarn,” as used herein refers to a continuous single ply or strand of textile fibers, filaments or material that can be used to form multi-ply products. The terms “thread” or “sewing thread” refer to two or more plies of yarn in a form suitable for processing on any type of sewing machine that is used in the manufacture of garments. Thread can occur in a variety of forms to include a spun yarn consisting of staple fibers usually bound together by twist; a multi filament thread consisting of many continuous filaments or strands; or a mono filament thread which consist of a single strand. Typically, the thread or sewing thread refers to the final product that is used in a sewing process, whereas yarn is a more generic term and can refer to the precursors used to manufacturer the final thread.
The terms “air entangling” or “air texturizing” as used herein refers to subjecting one or more yarns to an air jet for the purposes of intermingling the strands from each of the yarns to produce a single yarn or a multi-ply yarn composite that is then finished to produce a sewing thread. For example, in my invention both a low melt yarn and a conventional high melt yarn can be fed to an air texturing machine to form a composite yarn that exhibits final properties that are a mix of the individual yarn properties. A composite or compounded thread of both high and low melt yarns may be formed in various ways. In one way a continuous filament low melt yarn can be combined with one or more ends of a continuous filament high melt effect yarn with the filament ends being combined during a texturing operation, such as air jet texturing, false twist texturing, twisting, prior twisting, conventional covering and the like. Depending on the apparatus used to perform air entangling or jet texturing, it may be necessary to modify the process to prevent the entangled composite yarn from being exposed to temperatures that may melt the low melt yarn component. Such modification can include avoiding heated godets or manipulation of temperature settings to keep the maximum temperature below the melting point of the composite yarn. In a second approach, low melt and high melt staple fibers may be homogeneously mixed or blended, then processed according to standard staple yarn processing techniques. Another approach is to use a low melt staple and to spin the staple around a high melt core. However, in its simplest embodiment, my invention involves a physical combination of one or more sewing threads composed of 100% low melt synthetic polymer with one or more conventional sewing threads having a higher melting point in a stitch using a conventional sewing machine and then subjecting the stitched seam to a heat treatment to melt the low melt sewing thread. This is illustrated in
As used herein, the term “low melt” refers to a yarn or sewing thread constructed of a material having a melting point that allows it to be used on commercial heat setting equipment such that it melts and becomes flowable to an extent that the melt extends beyond the location where it was sewn and causes the fabric in the seam to bond to itself. Various examples of such materials are known in the art. Preferably, the low melt yarn will have a melting point of between about 40° C. to about 200° C. More preferably, the low melt yarn has a melting temperature between about 85° C. to about 120° C. Desirably, the low melt yarn is comprised of nylon, polyester, polyethylene, a polyethylene-based copolymer or another thermoplastic material such as polypropylene or any synthetic cross-linkable polymer. Alternatively, the low melt yarn or thread can be composed of a mixture of these various polymers. Regardless of the specific polymer chosen, the key to my invention is that the melting point of the low melt thread must be less than that of the high melt thread such that when the seam is subjected to the heating step only the low melt thread melts. A suitable low melt thread is composed of nylon and is available from Thornton, Kelly & Co., Yorkshire, UK. As mentioned, the low melt thread need not be comprised entirely of fusible material such that the entire thread would melt. For example, the low melt thread could be comprised of a high melt core and a low melt sheath. The low melt sheath may be applied using a co-extrusion process or spinning process. Alternatively, the low melt thread may be a multifilament construction made of some low melt strands and some non-low melt strands. Either of the options just discussed is acceptable so long as a sufficient amount of the low melt fiber is presented for bonding to the fabric in the seam of my invention during heat setting and to bond the high melt thread to the fabric.
In the method of my invention a conventional industrial sewing machine will be set-up with at least one low-melt thread and at least one conventional high-melt thread, however, it is within the scope of my invention that the at least one thread is a composite of high and low melt yarns or strands.
Referring now to the drawings and particularly to
As viewed in
In order to form seam 16 in accordance with the invention, as depicted in
As shown in
The stitches used to secure the seams together can be made using any type of sewing machine. Typical machines would include a cover stitch, a chain stitch, and an overlock machine. Each of these types of machines employs two or more thread feeds and one or more needles.
As shown in
The distance 50 between stitches 40 and 42, as shown in
Although the specific embodiment as shown in the Figures is directed to a side seam of a dress shirt, it is to be understood that the seam and method for production of the present invention can advantageously be utilized for a variety of seams, for example in various seams of shirts or other garments such as trouser and skirt hems, for example. Accordingly, the seam and method depicted in the Figures is only an exemplary seam and is not intended to limit the scope of the invention.
In describing my invention, reference has been made to preferred embodiments and illustrative advantages of the invention. Those skilled in the art, however, and familiar with the art of garment manufacturing, will recognize additions, deletions, modifications, substitutions and other changes which fall within the purview of the subject invention.
