Moldable fabric

Abstract

A moldable fabric for a garment component (such as a brassiere cup) is made by using standard knitting techniques (such as Simplex) using a combination of thermoplastic and elastomeric yarns. The fabric is knitted and processed in a manner that imparts it with isometric stretching properties.

Description

RELATED APPLICATIONS

[0001] This application claims priority to provisional application S. No. 60/388,004 filed on Jun. 12, 2002 for a MOLDABLE BRASSIERE FABRIC, incorporated herein by reference.

BACKGROUND OF THE INVENTION

[0002] A. Field of Invention

[0003] This invention relates to an improved moldable fabric and a method of making the same. More specifically, the invention involves an improved moldable fabric that has isotropic properties. The fabric is particularly suitable for making garments such as brassieres, swimwear, corsets, bandages, leggings and other garments having one or more sections made of a material having shape-retaining characteristics.

[0004] B. Description of the Prior Art

[0005] For many years, attempts have been made to produce a fabric with shape-retaining characteristics. For example, brassieres have typically been manufactured by cutting cup components from standard fabrics and then sewing these components together to form three dimensional cups which were subsequently incorporated in the body of the brassiere. Another method included making the brassiere components out of special fabrics with underdrawn synthetic yarns and then molding the same. Obviously this process is time consuming, labor intensive and requires extensive expertise. In addition, the brassieres made by this process had other disadvantages. For example, the sewn cups have ridges and seems that are unsightly and render them uncomfortable to wear.

[0006] Attempts have been made to find other alternatives to the sewn-cup. One such attempt includes thermal molding. This process converts a planar fabric portion into a three-dimensional, paraboloid-like cup which does not have any seams and accordingly offers many functional, aesthetic and economic advantages over the conventional method described above. Molded cups eliminate the chafing seams and their revealing outlines on the outer garments, as well as offer attractive savings by dispensing with the skilled labor involved in cutting, assembling and sewing of the cup components.

[0007] The first attempts at fabric molding involved woven fabrics incorporating partially drawn thermoplastic synthetic polymer yarns such as linear polyamide (nylon), linear polyester and, to a lesser extent, linear polypropylene, polyurethane and polyvinyl chloride. Woven fabrics containing these undrawn yarns were formed into three dimensional shapes, such as brassiere cups, under intense heat and pressure using molding equipment. The results of these early attempts were unsatisfactory because woven fabrics did not respond well to the molding process due to the inherent rigidity of the woven structures. Moreover, woven fabrics experienced loss of their integrity caused by slippage of the warp and filling threads.

[0008] Another attempt at resolving this problem involved knit fabrics, mainly warp knit type fabrics. The inherent stretch or extensibility of knit structures was found to be much more compatible with the molding process than the rigid woven structure, and resulted in good conformance to the contours of the molding equipment without any loss of fabric integrity. Both nylon and polyester undrawn filament yarns were used in making warp knit fabrics in either tricot (single face fabric) or Simplex (double face fabric) constructions, the latter being the preferred one.

[0009] While knit fabrics could be used much better for making molded fabrics then woven fabrics, there were still serious problems associated with the use of undrawn yarns in the process, which yarns were, by nature, mechanically unstable and non-uniform, and resulted to streaked fabric, warping and knitting difficulties and poor laundering performance in the form of shrinkage and shape retention irregularities caused by the incomplete drawing of the yarns in the molding process.

[0010] The final phase in the development of molded fabrics arrived with the general availability of spandex yarns some 35 years ago. According to the definition adapted by the FTC, spandex is a long chain synthetic polymer composed of at least 85% of segmented polyurethane. Perhaps the best-known example of spandex is DuPont's Lycra® fiber however elastomeric fibers, based on polyether and polyester chemistry are increasingly becoming popular as well.

[0011] The great advantage of spandex yarn is its excellent moldability due to its high stretch factor, which readily induces good contour conformance to the mold, and its heat setting temperature that is compatible with that of both nylon and polyester. Moreover, in fabric structures combining spandex yarns with non-elastic yarns, such as filament nylon, polyester or other thermoplastics, the presence of spandex provides a vehicle to achieve a permanently molded product without the need to utilize the troublesome undrawn yarns. For these reasons, fabrics made of combination of spandex and other fabrics easily conform to the shape of the mold and result in a finished molded fabric, such as a brassiere cup that has good stretch-recovery properties, provide very good fit and, when necessary, support. Moreover, such molded fabrics are further advantageous because they can be constructed with just enough residual stretch to offer very good fit, while allowing for periodic fluctuations in a normal body weight fluctuations.

[0012] Nevertheless, despite the improved moldability of spandex yarns, the prior art has not been able to overcome certain deficiencies in fabrics used for manufacturing garment components for several reasons. First, current molded fabrics made as discussed above lack isotropic stretch characteristics. While some fabrics can achieve a maximum percentage of stretch in the lengthwise direction, they lack the power to stretch proportionately widthwise.

[0013] While these latter molded fabrics were superior to the earlier attempts, they still had several disadvantages. Edges of these fabrics when cut need to be finished to prevent unraveling or fraying. Moreover, they were not very stretchable and therefore each set of components had to dimensioned for a final product of a preselected size. In other words, separate components had to be molded for products of each size. Finally, brassieres are typically made with a rubber layer in the ‘wing’ or side panels of the bra that cause irritation to the skin, and discolor or otherwise degrade the aesthetics of the brassiere.

[0014] U.S. Pat. No. 6,164,092 to Menaker discloses a knitted fabric composed of blend of spandex and polyester-cotton yarns. However, Menaker does not teach a fabric with isotropic properties. Furthermore, the fabric taught by Menaker does not solve the other problems and concerns that are prevalent in the brassiere manufacturing industry.

OBJECTIVES AND SUMMARY OF THE INVENTION

[0015] In view of prior art deficiencies, the principal objective of the present invention is to provide an improved molded fabric with isotropic stretch and power characteristics.

[0016] A further objective is to provide a moldable fabric that can be formed into garments or garment portions such as brassieres.

[0017] A further objective is to provide a fabric with edges that are stable when cut.

[0018] A still further objective is to provide a versatile fabric that is flexible and/or expandable so that it can be formed into garment portions that can be used in garments having different sizes.

[0019] Additional objectives will be apparent from the description of the invention as contained herein.

[0020] In its broadest aspects, the invention presents an improved moldable isotropic fabric and a method for creating said fabric. Generally, the fabric comprises elastomeric yarns, preferably spandex, and a thermoplastic yarns, preferably nylon. These yarns are knit, using standard knitting techniques, such as a double-faced “Simplex” type technique.

[0021] The new fabric achieves isotropic stretch properties through a combination of steps during the knitting and processing of the fabric. Maintaining consistent fabric quality from the standpoint of elastic, and hence, molding performance, requires close control at each manufacturing phase. Significant amounts of moisture are extracted from the fabric during processing to prevent the fabric from sagging The resulting fabric is stretchable substantially evenly along its length and width when subjected to a standard manual stretch test. When standard mechanical stretch tests are applied, the fabric undergoes substantially equal differential stretching in both directions.

BRIEF DESCRIPTION OF THE DRAWINGS

[0022] FIG. 1 is a plan view of a fabric constructed in accordance with this invention;

[0023] FIG. 2 shows enlarged details of the fabric of FIG. 1;

[0024] FIG. 3 shows the knitting parameters of an embodiment of the fabric of FIG. 1;

[0025] FIG. 4 shows the knitting parameters of another embodiment of the subject fabric having a lighter weight relative to the fabric of FIG. 2;

[0026] FIG. 5 is a flowchart of the processing sequence of the fabric after knitting;

[0027] FIG. 6 shows physical properties of an embodiment of the fabric based on test results from the Zwick and IP4 Modulus under varying weight loads; and

[0028] FIG. 7 shows a brassier with panels incorporating fabrics constructed in accordance with this invention.

DETAILED DESCRIPTION OF THE INVENTION

[0029] FIG. 1 is a plan view of a section of a fabric 10 constructed in accordance with the invention. For the purposes of this invention the direction along the width of the fabric 12 is referred to as the x axis and the direction along the length 14 of the fabric is referred to us the y-direction.

[0030] The present invention pertains to a fabric having superior molding characteristics including isotropic stretching properties. These characteristics are achieved through a combination of knitting techniques and fabric processing technology. As utilized herein, the terms “isotropic” and “isotropic stretch” are defined as the fabric's ability to stretch in substantially equivalent proportions, length- and widthwise. Thus, the fabric 10 in FIG. 1 is isotropic because it stretches by the same amount when forces are applied to it either along the x- or the y-axis.

[0031] FIG. 2 is a simplex stitch pattern used for the fabric 10. As seen in this Figure, the fabric is knitted of three threads designated as 13A, 13B and 13C. Threads 13A are preferably thermoplastic threads, while threads 13B and 13C are preferably elastomeric threads. The simplex stitch pattern is shown in FIG. 2 in a somewhat simplified or schematic form, since, as it is well known to one skilled in the art an accurate graphic presentation would be very difficult to create in a manner that can be followed easily. One important feature of this simplex knit is that it has knit stitches appearing on both faces of the fabric 10. Advantageously, this double-faced simplex fabric 10 is denser, smoother and without the surface ridges of prior art fabrics, making it particularly suitable as a moldable fabric for the manufacture of three dimensional garment components such as brassieres and other garments.

[0032] Typical prior art molding fabrics have a warp knit jersey construction characterized by surface ridges on one face that render the garment uneven on that face and, thus less comfortable to wear then the double faced simplex knit fabric 10 disclosed herein. Moreover, these molding fabrics do not possess the isotropic character present in the subject fabric 10.

[0033] The fabric 10 may be produced using a 2-guide bar Simplex knitting machine. In order to produce the fabric 10, one of the bars of the machine is threaded with a thermoplastic yarn, while the other is threaded with an elastomeric yarn. Many suitable thermoplastics and elastomers are readily available on the market, however nylon and spandex are preferable for the subject invention. FIG. 3 shows the knitting parameters of a first embodiment of the invention and FIG. 4 shows the knitting parameters for a second embodiment. In these embodiments, the preferable stitch notation in forming the fabric of the first guide bar is 1-0/1-2/3-4/3-2 and that of the second guide bar is 4-5/3-2/1-0/2-3.

[0034] In addition to these knitting parameters other parameters also affect the characteristics of fabric 10 including elasticity, thickness, weight, content, denier and runner length (amount of yarn or thread fed into each guide bar). In the embodiment of FIG. 3, it is preferable to employ yarn systems containing approximately 57% nylon 66 and 43% bright spandex, using 40 denier, 34-filament nylon and 70/1 denier spandex. The runner lengths of nylon and spandex should be 55.5 and 44 inches respectively. Using these parameters, a knit fabric is produced with a stitch count of 67/68 wales per inch and 93/94 courses per inch and a width of approximately 40/41 inches and a weight of approximately 13.8 ounces per square yard.

[0035] The knitting parameters shown in FIG. 4 may be used to construct a fabric having less weight, thus making it more suitable for lightweight garments In this embodiment, the content of Nylon 66 to Bright Spandex is 71% to 29%, with nylon 66 threads having a 40 denier, 34-filament and the spandex threads having a finer denier, preferably 40/1. In addition, the runner lengths of nylon and spandex are 51.5 and 39 inches respectively. Using these parameters, a fabric is obtained having a stitch count of 72/73 wales and 84/85 courses per inch, and a weight of 9.6 ounces per square yard.

[0036] As discussed above, other compatible yarns or threads may be employed instead of nylon and spandex for knitting of the subject fabric. For example, yarns may be used having a dernier in the range of 20-100. Similarly, the percentages of thermoplastic and elastomeric threads, the denier, runner lengths and stitch counts may be modified as well, depending on specific characteristics desired for each fabric while still keeping within the scope of this invention.

[0037] FIG. 5 shows details of the method used to generate a final moldable fabric in accordance with this invention. In this Figure, oval shaped boxes (such as 24) identify water and moisture removal steps while rectangular shape boxes identify other intermediate steps performed before each stage of water and moisture removal.

[0038] The fabric is knit in step 20 using the materials and apparatus disclosed above. In step 22 the fabric is dyed. Many methods of dyeing a knit fabric are known in the art, including beck dyeing, beam dyeing, jet dyeing, jig dyeing and pad dyeing. According to the present invention, a somewhat preferable technique for imparting color to the fabric is jet dyeing 22. Jet dyeing 22 is a simple and efficient method to color fabric swiftly and uniformly. Jet dyeing 22 typically involves taking the fabric through a tube or column where a jet of dye solution is forced through the fabric at high pressures and temperatures. The dye is continually circulated through the fabric. The minimal tension imposed on the fabric during the course fo dying induces relaxation and consolidation of the knitted structures. In one embodiment, the jet dyeing 22 is accomplished with dyeing machinery manufactured by Gaston County at a pressure in a range of approximately 17-20 pounds per square inch and at a temperature of approximately 210 degrees Fahrenheit. The time for jet dyeing a batch of fabric may range from 3 to 4 hours, the average dyeing time being about 3 hours and 42 minutes.

[0039] Water that is retained by the fabric after dyeing is removed by hydroextraction (step 24). During this phase, it is important to achieve a high level of hydroextraction efficiency without the unwarranted tensing of the fabric. Generally a hydroextractor may operate by centrifuge or compression. Centrifugal extractors rely on the force generated by the speed of rotation measured in conjunction with the distance from the center of rotation to the outer rim of the container to spin out the water. Although the amount of force is a significant factor in removing moisture from the load, other variables apply such as the type of fabric, time, thickness of load being spun, and chemicals present in the textiles being processed (i.e., fabric softener). Compression extractors apply pressure to the fabric and literally squeeze the water out of the fibers. The amount of water extracted depends on the total pressure exerted, the uniformity and effectiveness of the pressure throughout the load, and whether the outward flow of water is restricted in any way by the volume of fabric and/or the openings in the container that holds the load. Preferably, a centrifugal hydroextractor is utilized to minimize the tension on the fabric that may be caused by squeezing and the application of unwanted and excessive pressure to the fabric by a compression-type hydroextractor.

[0040] After the hydroextraction is completed in step 24, the fabric is detwisted in step 26. This step 26 is typically accomplished by use of a turntable and accompanying mechanisms that detect twists in the fabric, detwist the fabric and subsequently plait the fabric into a hamper.

[0041] Next, the fabric is dewatered using a beater bar system and vacuum extractor 28, which further remove water from the fabric. A beater bar system 28 is basically a series of one-inch solid stainless steel bars, mounted horizontally to form a triangular surface, with vacuum being applied to the fabric between the bar. The steel bars are moved at surface speed that is greater then the speed of the traveling fabric. Other comparable beater bar systems may be utilized as well.

[0042] Next, in step 30 the knitted fabric is placed in a tenter, which is a machine or frame for stretching the fabric onto tenter pins, so that the fabric may dry evenly and maintain its generally rectangular shape. Importantly, a minimum amount of tension is applied to the fabric during this process. Approximately, a ten percent fabric overfeed is applied during this stage of processing. Tentering is also preferably accomplished at approximately fifteen yards per minute to allow consistent and even drying of the fabric. Although tentering may be accomplished at significantly higher speeds, the invention preferably uses this approximate speed in order to avoid undue stretching and tension on the fabric that may be imparted at higher speeds. During this step 30, a gas fading inhibitor, preferably at 4%, and other finishing chemicals may also be padded on the fabric. Thereafter, the fabric is heat set in six zone heaters at 370° F. to impart the fabric its desired dimensions, and, also, to insure sufficient evaporation of any remaining moisture and prevent unwanted dye migration. As the fabric emerges from the heaters, it is vacuum cooled and wound up into 60-80 yard rolls.

[0043] As discussed above, the fabric knit by the parameters outlined in FIG. 3 exhibit a manual stretch of approximately 70% in both length and width directions. Additionally, the fabric knit according to the parameters FIG. 4 has a manual stretch of approximately 80-85% in the length direction and 80% in the width direction. These percentages of manual stretch enable the fabric to be particularly useful, in terms of both form-fifting and support, for brassiere and compressive garments. Typically, standard simplex fabrics that are knitted very tight have almost no manual stretch. Standard simplex fabrics that are knit more loosely typically have a manual stretch of about 7% in length and 25% in width.

[0044] FIG. 6 is a series of test results on fabric #1 in FIG. 3 constructed in accordance with this invention, using an IP4 Modulus tester and a Zwick Modulus atester to determine its stretch properties. A review of these results indicates that the fabric stretches in the x and y directions by a percentage of the same order of magnitude. It is evident that as the weight loads increase, the percent of stretch also increases. In general the fabric stretches by about 30% in the y direction then in the x direction.

[0045] Importantly, the differential stretch by which the fabric extends for different loads is much smaller. More particularly, in tests using the IP4 Modulus, an embodiment of the fabric experiences a 32% increase in stretch in the length direction and a 33% increase in stretch in the width direction when varying the load from 15 pounds to 20 pounds. Similarly, when increasing the force on the fabric from 20 pounds to 30 pounds, the fabric experiences an 38% increase in stretch in the length direction and 39% increase in the width direction. Thus the difference in the percentage stretch between the x and y direction for these cases is less then 6%. Thus, these test results clearly indicate that the fabric constructed in accordance with this invention is at least substantially isotropic and moreover, it exhibits what is hereby termed as being differentially isotropic, meaning that it stretches by substantially equal proportions in response to forces in each of two orthogonal directions.

[0046] Once the processing of the fabric is complete, it is molded using standard techniques well known in the art and then incorporated into various garments. Molding prior art fabrics leads to several problems and result in garment components that are unacceptable. For example, molding prior art fabrics often results in a garment component with pockets that are unmolded, partially molded or overmolded. The fabric produced in accordance with this invention results in perfectly molded components because of its isotropic stretch characteristics.

[0047] FIG. 7 shows an isometric view of a brassiere. The brassiere is formed with cups 52 sewn into the brassiere frame. The brassiere further has a bottom band 54, dorsal panels or wings 56, shoulder straps 58, cross tapes 60 and a fabric insert 62. Cups 52 are molded from the fabric made in accordance with the subject invention.

[0048] The fabric constructed in accordance with this invention is advantageous because it solves many problems associated with the prior art. The fabric's improved isotropic properties and stretch characteristics reduce inventory problems typically experienced by manufacturers. A manufacturer can now use the same garment component (made of the subject fabric) that can fit the molding procedure for a range of cup sizes. Additionally, the inventive fabric can replace trilaminate side panels of the bra, thereby eliminating the drawbacks of allergic reactions to rubber and discoloration of the brassiere. Moreover, the fabric construction and composition provide stable edges that eliminate the need for costly finishing. While the aforementioned advantages have been described in conjunction with brassieres, the described fabric may be incorporated into other garments, such as swimwear, performance athletic wear, corsets, compressive garments, compressive bandages and compressive leggings, shoulder pads, and so on.

[0049] Although this invention has been described with reference to particular embodiments, it is to be understood that these are merely illustrative of an application of the principles of the invention. Numerous modifications to the illustrative embodiments discussed herein may be made and other arrangements may be devised without departing from the spirit and scope of the invention.

Claims

1. A method of producing a moldable fabric comprising the steps of:

knitting a knitted fabric from a plurality of yarns including a set of elastomeric and a set of thermoplastic yarns; and

processing said knitted fabric to form a moldable fabric, said moldable fabric having isometric stretching characteristics.

2. The method of claim 1 wherein said thermoplastic material is nylon.

3. The method of claim 1 wherein said elastomeric material is spandex.

4. The method of claim 1 wherein said processing step includes dyeing said knitted fabric.

5. The method of claim 4 wherein said dyeing is accomplished at an approximate pressure ranging from 17 to 20 pounds per inch squared.

6. The method of claim 4 wherein said dyeing is accomplished at a temperature of approximately 210 degrees Fahrenheit.

7. The method of claim 1 wherein said processing step includes removing moisture from said fabric using a hydroextractor.

8. The method of claim 1 wherein said processing step includes detwisting said knitted fabric.

9. The method of claim 8 wherein said fabric is detwisted using a turntable and plaiting fabric into a hamper.

10. The method of claim 1 wherein said processing step includes the removing moisture from said knitted fabric using a beater bar system.

11. The method of claim 1 wherein said processing step includes the removing moisture from said knitted fabric using a vacuum extractor.

12. The method of claim 1 wherein said processing step includes placing said knitted fabric on a tenter frame, moving said knitted fabric at a minimum of tension to said knitted fabric along a predetermined direction.

13. The method of claim 12 wherein moving said fabric at a minimum of tension is achieved by overfeeding said knitted fabric into said tenter.

14. The method of claim 13 wherein said overfeeding is at approximately 10%.

15. The method of claim 12 wherein a tentering speed of said knitted fabric is set at approximately fifteen yards per minute.

16. The method of claim 1 wherein said processing step further includes heat setting said knitted fabric.

17. The method of 16 wherein said knitted fabric is heat set at approximately 370 degrees Fahrenheit.

18. The method of claim 16 wherein said processing step includes vacuum cooling said knitted fabric after said knitted fabric is heat set.

19. The method of claim 1 wherein said knitted fabric has a length and a width and is stretchable along said length and said width by about 70%-80%.

20. A method of making garment component comprising:

knitting a fabric from a plurality of elastomeric and thermoplastic yarns, said fabric isometric stretching characteristics; and

forming said fabric into a predetermined three-dimensional shape.

21. The method of claim 20 wherein said fabric is knitted from nylon and spandex yarns.

22. The method of claim 21 wherein said fabric contains about 57% nylon yarns.

23. The method of claim 21 wherein said fabric contains about 43% spandex yarns.

24. The method of claim 21 wherein said fabric is knitted using a simplex knitting technique.

25. The method of claim 21 wherein said fabric contains about 57-71% nylon yarns.

26. The method of claim 21 wherein said fabric contains about 29-43% spandex yarns.

27. The method of claim 21 wherein said fabric has a width and a length and is manually stretchable by an approximately equal amount along both said width and length.

28. The method of claim 21 wherein said fabric has a width and a length and when subjected to a standard mechanical stretch test, it stretches by approximately the same incremental amount along said width and said length.

29. A garment component comprising:

a fabric formed into a three-dimensional shape, said fabric being knit from a combination of elastomeric and thermoplastic yarns and wherein said fabric has isotropic characteristics.