Abstract:
The present invention provides a knitted furniture support fabric having multi-directional stretch characteristics and possessing sufficient strength and durability to function as a support in a seating or bed structure. The furniture support fabric of the present invention is a four bar knit structure including two yarns of textured polyester and two yarns of elastomeric monofilament knit together such that the fabric has an elongation at break of at least 17 percent in both the warp and fill directions.

Description:
FIELD OF THE INVENTION 
     This invention relates generally to furniture support fabric for disposition across a furniture frame and relates more particularly to a four bar knitted fabric construction using two bars of textured polyester yarn and two bars of monofilament yarn knitted together to form a strong lightweight material suitable as a support member in seat bottoms, and backs as well as in beds in lieu of box or wire springs. Such fabric possesses properties of high strength, low weight and multi-directional stretch with good recovery as required for performance under cyclical loading in the preferred environment of use. 
     BACKGROUND 
     Seating and bedding structures typically are constructed from a seating frame and cushions for occupant contact. However, most such structures will also typically require a subcushion support structure disposed across the seating frame to give the cushions the necessary support to provide a comfortable and secure feeling to the user. These support structures have traditionally been based around the concept of coils, spring constructions, sinuous wire and webbing making use of deformation according to spring constant characteristics of the construction being used so as to meet and respond to variable and cyclical loads. 
     The use of specially designed fabrics to either augment or replace traditional coils and springs is known. One such woven fabric is disclosed in U.S. Pat. No. 4,469,739 to Gretzinger et al. (incorporated herein by reference). The present invention provides a lightweight knitted construction furniture support fabric possessing the physical characteristics necessary for long-term use. In particular, the present invention provides a warp knitted fabric having multi-directional stretch characteristics. Accordingly, the present invention represents a useful advancement over the state of the art. 
     OBJECTS AND SUMMARY OF THE INVENTION 
     In view of the foregoing, it is a general object of the present invention to provide a knitted furniture support fabric having multi-directional stretch characteristics and possessing sufficient strength and durability to function as a support in a seating or bed structure. 
     It is a more particular object of the present invention to provide a knitted furniture support fabric which is light in weight. 
     It is a feature of the present invention to provide a knitted furniture support fabric having a four bar warp knit construction incorporating two bars of textured polyester and two bars of elastomeric monofilament yarn. 
     It is a further feature of the present invention to provide a furniture support fabric having a four bar warp knit construction and characterized by an elongation at break of about 17 percent or greater in both the warp and the fill directions. 
     It is yet a further feature of the present invention to provide a furniture support fabric having a four bar warp knit construction which has a weight of about 25 ounces per square yard or less. 
     Other objects, advantages and features of the invention will, of course, become apparent upon reading the following detailed description and by reference to the drawings below. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a composite needle bar diagram illustrating the configuration of each bar stitch within a preferred embodiment of the knit fabric of the present invention; 
     FIG. 2 illustrates the repeating arrangement of the yarn in Bar 1 shown in FIG. 1; 
     FIG. 3 illustrates the repeating arrangement of the yarn of Bar 2 shown in FIG. 1; 
     FIG. 4 illustrates the repeating arrangement of the yarn of Bar 3 shown in FIG. 1; and 
     FIG. 5 illustrates the repeating arrangement of the yarn of Bar 4 shown in FIG. 1. 
     While the invention has been illustrated and will be described in connection with certain preferred embodiments and procedures, it is, of course, to be appreciated that we in no way intend to limit the invention to such particularly described embodiments and procedures. On the contrary, it is intended to include all alternatives, modifications and equivalents as may be included within the true spirit and scope of the invention as may be defined by the claims appended hereto. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Turning now to the drawings, wherein like reference numbers designate like elements in the various views, in FIG. 1 there is shown a potentially preferred stitch arrangement for the knit furniture support fabric of the present invention. 
     The potentially preferred embodiment, the furniture support fabric is a four bar warp knit fabric knitted on a six gauge Raschel knitting machine. The Bar 1 yarn 12 and Bar 2 yarn 14 are preferably textured polyester yarns having deniers between about 70 and about 450. By way of example only, and not limitation, one potentially preferred textured polyester yarn is a two ply 150 denier yarn having 34 filaments per ply which is believed to be available from DuPont Fibers in Wilmington, Del. under the trade designation 56T. 
     As best illustrated in FIG. 2, Bar 1 yarn is knitted in the fabric in a full chain stitch arrangement as will be well known to those of skill in the art. In the potentially preferred practice of the present invention, the particular stitch notation for the Bar 1 yarn is 1-0/0-1//. 
     As best illustrated in FIG. 3, the Bar 2 yarn 14 is knitted in the fabric in a looped crossing pattern. In the illustrated and potentially preferred practice, the particular stitch notation for the Bar 2 yarn is 4-5/1-0//. 
     In the preferred practice, the Bar 3 yarn 16 and Bar 4 yarn 18 are elastomeric monofilament yarns. One such monofilament yarn is believed to be available under the trade designation Elas-Ter™ monofilament marketed by Hoechst Celanese Fibers Corporation group in Charlotte, N.C. In a particularly preferred practice, the monofilament in Bar 3 and Bar 4 will have a denier of about 400 although it is believed that yarn deniers between about 300 and about 800 may be utilized. 
     As best illustrated in FIG. 5, the Bar 4 yarn 18 is preferably knitted in a chain stitch in opposing orientation to the stitch arrangement for the Bar 1 yarn 12 previously described. Accordingly, in the preferred practice of the present invention, the preferred stitch notation for the Bar 4 yarn is 0-1/1-0//. 
     Bar 3 yarn 16 is preferably used in a looped crossing pattern incorporating a stitch notation 1-0/2-3// tying together the augmenting chain stitches of Bar 1 yarn 12 and Bar 4 yarn 18 with the Bar 2 yarn 14 serving to form a textured base for the other adjoined yarns. 
     The above description and related figures describe and illustrate a preferred practice for producing a knit furniture support fabric which exhibits multidirectional stretch and recovery. In order to more fully illustrate the concepts of the subject invention, the following examples are given. However, it is to be understood that any such examples are provided for illustrative purposes only and should in no way be construed as unduly limiting the scope of the invention which is defined and limited only by the scope of the appended claims and equivalents thereto. 
     EXAMPLES 1-8 
     Each of eight fabric samples having the construction as shown in FIGS. 1-5 above was knitted on a six gauge knitting machine with a construction on the machine of 22 courses per inch and 6 wales per inch yielding finished constructions as shown in Table I. Bars 1 and 2 were single ply 150 denier textured polyester having 34 filaments per yarn. Bars 3 and 4 were 400 denier Elas-Ter™ monofilament. The fabric was heat set at 340° F. after which the physical properties of the fabric were measured. 
     Physical properties of weight, ball burst, warp torque, tear and tensile strength in both the warp and fill directions are set forth in Table II. Elongation properties for each of the eight fabric samples are set forth in Table III (Warp) and Table IV (Fill). 
     
                       TABLE I______________________________________SAMPLE CONSTRUCTIONSSample Number  Wales/Inch                    Courses/Inch______________________________________1              6         182              6         183              6         174              9         265              12        306              12        317              7         218              7         21______________________________________ 
    
     
                       TABLE II______________________________________SAMPLE PHYSICAL MEASUREMENTS                   Tongue Peak Grab                                  Peak Grab Weight   Ball     Tear   Tensile TensileSample Oz./Sq.  Burst    Warp   Warp    WeftNo.   Yd.      (Pounds  (Pounds)                          (Pounds)                                  (Pounds)______________________________________1     6.39     102      13.3   77.7    862     6.34     107      13.7   81      80.93     5.36     108      11.6   65.4    78.24     11.89    149      13.2   93      124.65     20.87    N/A      18.1   138     1566     20.66    N/A      17.3   139.2   154.97     8.38     133      14.1   84.9    108.38     8.28     137      13.4   81.9    111.3______________________________________ 
    
     
                       TABLE III______________________________________SAMPLE ELONGATION MEASUREMENTS - WARP  Load     Load     Load   Load  @ 5%     @ 15%    @ 25%  @ 50%  Elonga-  Elonga-  Elonga-                           Elonga-                                  % Elonga-Sample tion     tion     tion   tion   tionNo.    (Pounds) (Pounds) (Pounds)                           (Pounds)                                  @ Break______________________________________1      8.9      42.1     63.2   N/A    26.82      8.7      42.8     71.8   N/A    27.23      8.5      52.6     54.6   N/A    21.74      3.5      14.6     35.4   N/A    40.35      6.2      21.5     41.5   119    55.26      6.2      21.1     40.6   120.8  54.47      5.9      27.1     65.2   N/A    31.98      6.9      32.6     77.4   N/A    25.9______________________________________ 
    
     
                       TABLE IV______________________________________SAMPLE ELONGATION MEASUREMENTS - FILL  Load     Load     Load   Load  @ 5%     @ 15%    @ 25%  @ 50%  Elonga-  Elonga-  Elonga-                           Elonga-                                  % Elonga-Sample tion     tion     tion   tion   tionNo.    (Pounds) (Pounds) (Pounds)                           (Pounds)                                  @ Break______________________________________1      10.1     61.5     N/A    N/A    18.62      9.6      59.2     N/A    N/A    18.43      5.1      59.9     N/A    N/A    17.54      1.9      12.9     47.5   N/A    37.85      3.3      11.6     21.4   70.9   71.56      3.2      11.2     21.1   76.2   68.77      4.7      34.6     99.4   N/A    26.48      3.2      23.2     77.2   N/A    30.3______________________________________ 
    
     While specific embodiments of the invention have been shown and described, it will be understood that the invention is in no way limited thereto, since modifications may be made and other embodiments of the principles of this invention will occur to those skilled in the art, Therefore, it is contemplated by the appended claims to cover any such modifications and other embodiments as incorporate the features of the present invention within the true spirit and scope of the following claims.