Patent Application
20080010793
The accompanying drawings which are incorporated in and which constitute a part of this specification illustrate several exemplary constructions and procedures in accordance with the present invention and, together with the general description given above and the detailed description set forth below, serve to explain the principles of the invention wherein:
While a description will hereinafter be provided in connection with certain exemplary embodiments, procedures and practices, it is to be understood and appreciated that in no event is the invention to be limited to the embodiments, procedures and practices as may be illustrated and described herein. On the contrary, it is intended that the present invention shall extend to all alternatives and modifications as may embrace the broad principles of this invention within the true spirit and scope thereof.
Reference will now be made to the drawings, wherein to the extent possible like reference numerals are utilized to designate like elements throughout the various views. A method as utilized to form a fabric of stitch bonded construction is illustrated schematically in
In the illustrated exemplary practice a substrate material 30 such as a carded and cross-lapped fleece or a needle-punched or spun bonded fleece is conveyed to a stitch-forming position in the direction indicated by the arrow. In a potentially preferred practice, the substrate material 30 is needle-punched fleece formed from about 4 denier polyester staple filaments although other suitable substrate materials may likewise be utilized if desired. The substrate material 30 may include a percentage of low melting point fibers such as low melting point polyester or bicomponent polyester having a core of relatively high melting point material and a sheath of lower melting point polyester to facilitate heat activated point bonding so as to enhance structural integrity.
As illustrated through simultaneous reference to
According to the illustrated practice, three yarn systems are used to form stitches through the substrate material 30. In the illustrated practice, a ground yarn 36 (
As will be appreciated by those of skill in the art, in operation the ground yarn 36 is moved into engagement with the needles which, in turn, carry the ground yarn 36 in reciprocating manner through the substrate material 30 without engaging finger elements 47 of the sinker bar so as to form an arrangement of cooperating ground yarn stitches 40 extending in relatively closely spaced parallel rows along the substrate material 30. By way of example only, and not limitation, the cooperating ground yarn stitches 40 may be held in a full chain stitch configuration although other stitch arrangements including tricot stitches and the like may likewise be utilized if desired. Preferably, the spacing of the stitch lines formed by the ground yarn 36 will be close enough that the ground yarn stitches 40 define a substantially continuous covering across the user contact surface 41 of the substrate material 30. The ground yarn 36 and the substrate material 30 thus define a substantially stable stitch bonded structure. By way of example only and not limitation, one ground yarn 36 that may be particularly suitable is a 70 denier polyester filament yarn, although other yarns may likewise be utilized if desired.
According to one exemplary practice, a first collection of loop elements 42, is formed projecting away from and standing above the ground yarn stitches across the fabric defining a user contact surface 41. If desired, at least a second collection of loop elements 43, may also be formed projecting away from and standing above the ground yarn stitches across the fabric. In the event that multiple collections of loop elements are utilized, it is contemplated that the loop elements 42 and 43 may be formed from either the same or different yarn materials. Thus, the yarns forming the pile may be characterized by either the same or different heat shrinkage characteristics. In this regard, it is contemplated that using yarns with different heat shrinkage character across the fabric may be desirable in some instances.
According to a contemplated practice, the loop elements 42, 43 may be formed substantially concurrently with the formation of the ground yarn stitches 40 through the substrate material 30. The loop elements 42, 43 may be selectively formed in a predefined pattern across the surface 41 of the fabric. In this regard it is to be understood that the first collection of loop elements 42 may be formed in either the same pattern or a different pattern than the second collection of loop elements 43. According to a preferred practice, the loop elements 42, 43 are formed so as to cover substantially the entire face of the fabric. However, it is also contemplated that the loop elements may be present only across selected portions of the fabric if desired to provide a combination of two dimensional and three dimensional surface character.
An exemplary technique for forming the loop elements 42, 43 is illustrated in
According to the illustrated practice, the second collection of loop elements 43 may be formed by a surface yarn 48 fully threaded through moveable yarn guides 49 carried by a front guide bar (not shown). While only a single surface yarn 48 is illustrated for explanatory purposes, it is to be understood that in actual practice, multiple surface yarns 48 are used across the width of the fabric. During the pile formation process, the surface yarn 48 is carried in alternating fashion back and forth between a first pair of needles 34, 34′ thereby forming a row of loop elements 43.
As will be appreciated, the formation practice illustrated results in the formation of double loops formed from two different surface yarns 44, 48. As long as the surface yarns pass between the needles 34, 34′ in a regular stitch forming procedure, a substantially continuous arrangement of loop elements 42, 43 will be formed along the length of the technical face 41 of the fabric. Of course, a single yarn system may also be utilized wherein one of the surface yarns 44, 48 is eliminated. According to a potentially preferred practice, the loop elements 42, 43 are formed so as to form a loop length in the range of about 1 mm to about 5 mm and more preferably a loop length of about 3 mm. Of course, it is likewise contemplated that the fabric formed may have a substantially flat construction. Such a construction may be achieved by simply disengaging the sinker fingers 47. It is also contemplated that the fabric may be formed to have flat zones and pile-forming zones. The stitch density for the surface yarns in the machine direction of both the loop elements and the ground yarns is preferably about 18 to about 60 stitches per inch and more preferably about 40 stitches per inch.
According to one contemplated practice wherein yarns with different heat shrinkage characteristics are utilized across the fabric surface, the surface yarn 44 may have a high heat shrinkage capacity with shrinkage activated at temperatures such as the fabric would encounter during normal heat setting operations, while the surface yarn 48 is preferably characterized by a substantially lower heat shrinkage capacity at the same temperature. Accordingly, loop elements 42 shrink to a greater extent than loop elements 43 when exposed to temperatures such as the fabric would encounter during normal heat setting. In this regard it is to be understood that the term “heat shrinkage capacity” is intended to refer to percentage of shrinkage on a length basis that a yarn undergoes when it is raised to a given temperature.
In the event that different yarn systems having differential heat shrinkage capacity are used, one potentially preferred high shrink yarn is a partially-oriented yarn (POY) of polyester. The polyester POY is preferably a cold drawn yarn with a draw ratio of about 1.35 to about 1.75 (most preferably about 1.57). In this regard, it is to be understood that the term “cold drawn” refers to yarn formed from filaments that are drawn at temperatures below the softening point of the fiber polymer. Most preferably, such drawing is carried out at substantially ambient temperatures. In the absence of elevated temperatures, substantially no thermal setting takes place during the drawing process. The term “partially-oriented yarn” refers to filament yarn that is drawn to a degree such that only partial longitudinal molecular orientation is achieved. One exemplary high shrink capacity surface yarn 44 is 72-filament bright trilobal polyester that has been cold drawn down to 150 denier. An exemplary low shrink capacity surface yarn 48 is a nylon yarn such as a textured yarn formed from Nylon 6 or Nylon 6,6. By way of example only, one such nylon yarn is a 70 denier false twist textured yarn formed from Nylon 6,6. Such yarns undergo a substantially reduced shrinkage at temperatures such as the fabric would encounter during normal heatsetting. As will be described further hereinafter, such yarn combinations facilitate the development of a highly textured face as the greige fabric is passed through a tenter or other heating unit following formation. It is also contemplated that other low shrink capacity yarns such as cellulosic filament yarns of viscose rayon and the like may also be used if desired
In the event that a single yarn system is to be utilized, the selection of the yarn material utilized will be dependent upon the degree of differential height desired across the fabric. Thus, if substantial differential height is desired, a material with high heat shrinkage capacity such as the polyester POY previously described may be desirable. Likewise, if a subtle differential pile height is desired across the fabric, a yarn material such as the false twist nylon or the like may be desirable.
As previously noted, it is to be understood that the stitch bonded fabric constructions as outlined above are exemplary only. In this regard it is likewise contemplated that other greige state fabric constructions as will be known to those of skill in the art may likewise be utilized. By way of example only, and not limitation, such alternative fabric constructions may include woven fabrics, warp knitted fabrics, raschel knitted fabrics, chenille fabrics and the like.
Regardless of whether a single yarn system or a multiple yarn system is utilized, the present system permits the controlled development of surface texturing such that different zones across the finished fabric have different pile heights and dye acceptance characteristics thereby providing substantial tactile and visual differentiation across the fabrics. One exemplary practice for carrying out this method is depicted schematically in
In the event that the surface 41 incorporates POY polyester yarns as described above (either alone or in combination with a higher heat shrinkage yarn), the heat absorbing fluid applied to the greige fabric may have a relatively low heat capacity such as a solution of water with an appropriate thickener such as polyacrylate or the like sufficient to increase the solution's viscosity as may be desired to promote the printing process. A viscosity of about 12,000 centipoise may be desirable to promote controlled application and retention of the heat absorbing fluid in patterned relation across the greige fabric. However, higher and lower viscosity levels may be used as desired. Of course, it is contemplated that other aqueous or non-aqueous solutions may likewise be utilized if desired.
According to one contemplated practice, the heat absorbing fluid may be chilled prior to application to the fabric. By way of example, it has been found that chilling an aqueous polyacrylate solution to about 40 degrees Fahrenheit prior to application to the fabric may be desirable. As will be described more fully hereinafter, the applied fluid is characterized by a heat capacity so as to substantially protect the wetted portions of the fabric from experiencing temperatures that would cause yarn shrinkage. If desired, the applied solution may further include a fugitive tint. The fugitive tint is a temporary coloring that allows an operator to verify that the fabric has been properly wetted according to the desired pattern, thus providing a quality control means to detect and correct any printing errors prior to further processing. Additional or alternative additives may be added to the solution as desired.
As depicted in
Referring again to
The result of the process as described above is a fabric having a three dimensional pattern defined by areas with differential pile height. Without being limited to a specific theory, it is believed that the selective wetting of the fabric protects the wetted zones while the character of the pile yarns concurrently facilitates shrinkage of the dry zones at relatively low levels of heat input during initial heating. Thus, selective shrinkage can be achieved without overwhelming the protective heat absorbing fluid.
As previously noted, it has been found that the differential pile heights may substantially correspond to differential dye acceptance characteristics across the fabric. That is, when the fabric is subjected to substantially uniform dyeing, the zones subjected to protective wetting take on a substantially different shade relative to the zones where substantial shrinkage has taken place. Thus, there is a complementary tactile and visual differentiation between the treated and untreated zones across the fabric.
Aside from the ability to provide simultaneous differentiation of both pile height and dye acceptance character, the process of the instant invention is believed to provide the benefit of substantially retaining the integrity of the fabric construction. Specifically, by using heat induced shrinkage rather than yarn removal or displacement, it is believed that the structural character of the fabric system may be substantially retained. This, in turn, may promote strength in the final product.
It is to be understood that while the present invention has been illustrated and described in relation to potentially preferred embodiments, constructions, and procedures, that such embodiments, constructions, and procedures are illustrative only and that the invention is in no event to be limited thereto. Rather, it is contemplated that modifications and variations embodying the principles of the invention will no doubt occur to those of ordinary skill in the art. It is therefore contemplated and intended that the present invention shall extend to all such modifications and variations as may incorporate the broad aspects of the invention within the true spirit and scope thereof.
