Abstract:
A knitted tulle is disclosed, the tulle comprising a plurality of wales, each with a pillar stitch and at least two pairs of weft threads, each pair of weft threads interconnecting and tying-in at least four wales. Also disclosed is a method of knitting the tulle, preferably using a Raschel machine and an embroidered fabric comprising the tulle. The tulle according to the invention is robust and even and has properties similar to bobbinet tulle.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to knitted tulles and methods of knitting tulles. 
     Tulle is a type of fine netting which has applications in embroidery, lingerie, bridal wear and haute couture as well as in technical areas where the durability and flexibility of netting are of particular importance. Such technical applications include military (e.g. radar reflective netting and parachute netting) and medical applications and as light diffusion fabrics in film and theatre applications. 
     Bobbinet tulle is a particular type of tulle which was first produced in the early 19 th  Century following the invention of the bobbinet machine in 1806 by John Heathcoat. The structure of bobbinet tulle provides advantageous properties of uniformity, strength and flexibility. One particularly advantageous property of bobbinet tulle in relation to embroidery is that it is flexible at the scale of the holes in the net structure which reduces the likelihood of yarn breakage when an embroidery needle (especially in machine embroidery) passes through the hole. 
     Unfortunately, the production of bobbinet tulle, which still uses the mechanisms devised by John Heathcoat, is slow. Bobbinet tulle is thus expensive and so is not, in practice, used in applications where its properties would otherwise make it suitable. 
     There have been attempts to devise faster production methods for nets or openwork fabrics using knitting machines, in particular, warp knitting machines. GB-A-1,275,448 relates to a method of producing patterned net fabrics on a Raschel warp knitting machine. GB-A-2,325,674 relates to an openwork knitted fabric that has a high capacity for absorption of size and so can be made harder and stiffer than previous fabrics. 
     There have also been attempts to produce knitted tulles or tulle-like materials. GB-A-1,230,232 relates to tulle having hexagonal openings produced on a Raschel knitting machine. 
     Unfortunately, the tulle described in GB-A-1,230,232 has a pattern which is very sensitive to differences in tension in the inlay threads. Unless the tension in each inlay thread is the same, the tulle is extremely distorted. It is, in practise, very difficult to control the tension of the inlay threads to the required degree because even a relatively narrow warp knitting machine may have over 5,000 separate inlay threads. 
     SUMMARY OF THE INVENTION 
     The present invention aims to provide a knitted tulle having the advantages of bobbinet tulle but avoiding or alleviating the problems of the prior art. 
     The present invention accordingly provides, in a first aspect, a knitted tulle comprising a plurality of wales each wale preferably having a pillar stitch (i.e. overlap) and at least two pairs of weft threads, wherein each pair of weft threads interconnects and ties-in (i.e. underlaps) at least four wales. 
     Preferably, each pair of weft threads interconnects and ties-in four wales only. Each pair of weft threads may interconnect and tie-in more wales than this (for example 5, 6, or more), however, the more wales which are interconnected and tied-in, the more complicated the tulle and, generally, the greater the repeat length. 
     Preferably, the tulle is flat (i.e. not a tube). 
     Preferably, the pattern is such that four or more inlay threads inlay on each wale. This is advantageous because it adds robustness, stability and strength to the pattern. 
     The interconnection and tying-in of at least four wales is greatly advantageous in that any differences in tension between the individual weft threads are spread more evenly across the tulle as a whole providing regularity, evenness, strength and flexibility. In particular, the holes of the tulle fabric are more regular in size which results in a stronger and more robust product and is visually more appealing in the marketplace. 
     Preferably, each weft thread of each pair interconnects and ties-in (i.e. crosses over between) at least three (preferably adjacent) wales. Each weft thread may interconnect and tie-in more wales than three, but this significantly increases the complexity of the pattern and the repeat length. 
     The interconnection and tying-in of at least three wales by each weft thread is advantageous because it also results in differences in tension being spread more evenly across the tulle as a whole, contributing to the regularity, evenness, flexibility and strength of the tulle. 
     Preferably, each weft thread of each pair follows a pattern which is the mirror image of the other weft thread in the pair; the mirror plane being substantially parallel to the wales. 
     Preferably, each pair of weft threads follows the same basic pattern, with respective pairs following patterns that may be shifted (i.e. offset or out-of phase) by a predetermined number of courses with respect to the pattern of another (or patterns of other) pair(s). In addition, or alternatively, respective pairs may follow patterns that are inverted with respect to the pattern of another (or patterns of other) pair(s). Such an inversion may be across a plane substantially perpendicular to the wales (and possibly parallel to the courses). 
     A first pair of weft threads which shares a wale with a second pair of weft threads, may follow a pattern which is out-of-phase with the pattern of the second pair by a predetermined number of courses. 
     Generally, the repeat length of the pattern will be a multiple of the predetermined number of courses to ensure that the pattern is regular. Preferably, the predetermined number of courses is a quarter of the repeat length, although it may be a half, third, fifth or sixth. 
     The predetermined number of courses may be 1 to 24, preferably 4 to 18, or 4 to 12, most preferably 6. The out-of-phase shift is advantageous because it improves the appearance and evenness of the tulle. 
     The first pair of weft threads may additionally, or alternatively, describe a pattern which is an inversion of the pattern of the second pair. Thus, preferably a first pair of weft threads which shares a wale with a second pair of weft threads follows a pattern which is an inversion of the pattern of the second pair. 
     The relationship of the pattern of each weft thread in the pair and of (e.g. immediately) neighbouring pairs of weft threads result in a regular overall pattern in the tulle leading to advantages in strength and robustness of the product. 
     Preferably, the tulle has substantially hexagonal holes. It is also advantageous if the tulle is substantially regular in either weft direction, the warp direction, or preferably both. 
     Usually, the pattern described by each pair of weft threads has a repeat of 12 to 60 courses. More preferably, the pattern followed by each pair of weft threads has a repeat of 12 to 48, 12 to 36, most preferably, of 20 to 30 courses. The preferred embodiment has a repeat of 24 courses. 
     Preferably, the pattern of each pair of weft threads includes at least two cross overs (i.e. two points at which the threads of the pair cross over each other). 
     In the most preferred embodiment of the invention, each weft thread of the first pair crosses to the corresponding wale of the other weft thread over three courses to form a first cross between the two wales, each weft thread of the pair then making six inlays in opposite directions on their respective wales, each weft thread of the pair then crossing over to a wale distal to the wale of the other weft thread in three courses over two wales, each weft thread then making three inlays in opposite directions in three courses, each weft thread then crossing over to its previously occupied wale in three inlays over three courses, crossing over to the corresponding wale of the other weft thread in three inlays over three courses to form a second cross between the two wales and each weft thread then making three inlays over three courses in opposite directions. 
     Preferably, the second pair of weft threads follows a pattern which is the inverse of, and/or is out-of-phase by a predetermined number of courses with, the pattern followed the first pair. 
     The tulle according to the first aspect of the invention may comprise synthetic or natural yarn. Examples of yarn which may be used to produce the tulle may be selected from polyester, polyamide (e.g. 6 or 66), polyaramid (meta and/or para), cotton, wool, hemp, silk and/or a mixture of one or more of these yarns. Generally any yarn which may be used in the textile industry would be suitable, depending on the intended application, however, preferred yarns are silk, cotton, polyester or nylon (i.e. polyamide). 
     The yarn count is preferably from 17 decitex to 280 decitex but may be greater or lesser than this for certain, specific applications. 
     Generally, the hole count of the tulle according to the first aspect of the invention will be between 14 and 128 holes per inch (5 to 51 holes per cm). 
     One of the great advantages of the tulle according to the present invention is that it is flexible, especially at the scale of the holes in the fabric. This is particularly advantageous for tulle used in embroidery because the flexibility of the threads defining each hole means that there is significantly less chance of yarn breakage when an embroidery needle passes through the hole. The applicant has surprisingly discovered that, as in bobbinet tulle, the threads defining the hole are flexible enough to move aside to allow the passage of an embroidery needle even if it is not precisely directed through the centre of the hole. 
     The tulle according to the present invention has a further advantage in that the fabric as a whole is flexible and resilient. 
     As discussed above, the knitted tulle according to the first aspect of the invention is produced by a knitting process. The present invention, accordingly provides, in a second aspect, a method of knitting a tulle, the method comprising forming a plurality of wales, and interconnecting at least some wales with at least two pairs of weft threads, wherein the method is such that each pair of weft threads interconnects and ties-in at least four wales. 
     The preferred method of knitting is warp knitting. Warp knitting is preferably performed using a Raschel knitting machine. 
     In the preferred embodiment of the invention, the Raschel knitting machine has 5 or more guide bars (e.g. 5, 6, 7, 8, or more guide bars). One guide bar is required in order to form the stitches, the remaining 4 guide bars are used to generate the inlays of two pairs of weft threads which define the tulle holes. 
     Preferably the machine gauge of the machine used to knit the tulle is 20 needles per inch to 50 needles per inch (8 needles per cm to 20 needles per cm). 
     Preferably, the machine is a single needle bed machine to produce a flat (i.e. not a tube) fabric. 
     Other preferred and optional features of the method of the second aspect of the invention are generally as described in relation to the first aspect, with appropriate modification. 
     Tulle produced according to the invention finds uses in technical fabrics, embroidery, automotive applications, theatrical, film, military and apparel dress and headwear applications. One particularly important use of the tulle according to the present invention is embroidery both because of the advantages it shares with traditional bobbinet tulle but also because it can be made at a much faster rate and is, therefore, more cost effective. 
     Thus, in a third aspect of the present invention, the present invention provides an embroidered fabric comprising a tulle according to the first aspect of the invention. The present invention also provides a product comprising a tulle as described in relation to the first aspect of the invention. 
     In a fourth aspect of the present invention, there is provided a knitted tulle comprising a plurality of wales and a plurality of weft threads, wherein each weft threads interconnects and ties-in at least three wales. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       By way of example, an embodiment of the present invention will now be described with reference to the accompanying drawings, in which: 
         FIG. 1  illustrates a prior art pattern of a knitted cross-tulle as disclosed in GB-A-1230232. 
         FIG. 2  illustrates the pattern of a single weft thread in a tulle according to the present invention. 
         FIG. 3  illustrates the pattern of a pair of weft threads in a tulle according to the present invention. 
         FIG. 4  illustrates schematically, the pattern of a plurality of first pairs of weft threads over a plurality of wales. 
         FIG. 5  illustrates, schematically, the pattern of a plurality of second pairs of threads over a plurality of wales. 
         FIG. 6  illustrates, schematically, the pattern of the tulle of the present invention consisting of an overlay of the patterns illustrated in  FIGS. 4 and 5 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     A prior art pattern, illustrated, in  FIG. 1 , is of a knitted cross-tulle consisting of single-needle wales  1 ,  2  and  3  which are formed singly and are interlaced only by weft threads. Weft threads  4 ,  5 ,  6  and  7  are shown. The weft threads  4  and  5  form one pair and the weft threads  6  and  7  another pair. 
     The weft threads  4  and  5 , and  6  and  7 , make three laps into the wales in three courses. Two of these adjoining runs of three laps are indicated by numerals  8  and  9 . The weft threads then form a cross  10  and  11 , respectively, between the wales  1  and  2 , and between the wales  2  and  3 , over three courses (described as two courses in the document but more properly considered as three). The weft threads  4  and  5  then effect, in the wales  1  and  2 , and the weft threads  6  and  7  effect, in the wales  2  and  3 , the three laps  8  and  9  respectively, whereupon they return to their initial wales by crossing over three courses. 
     The fabric produced using the pattern of  FIG. 1  is very sensitive to even small differences in tension between the threads. Such differences result in severely distorted fabric. This may be a reason why the fabric of GB-A-1230232 does not appear to have been commercialised. 
     The pattern of a single weft thread in a tulle according to the present invention is illustrated in  FIG. 2 . The pattern has a 24 course repeat, over the course of which the pillar stitches on the wales  14 ( 1 ),  14 ( 2 ),  14 ( 3 ) are interconnected and tied-in. The weft thread  15  makes a complete three inlay cross-over  21  between the first  14 ( 1 ) and second wale  14 ( 2 ) and then makes six inlays  22  over six courses. Over the next three courses, the weft thread  15  crosses over in three inlays  23  to the third wale  14 ( 3 ). The weft thread  15  makes four inlays  24  on the same wale  14 ( 3 ) before crossing over with two inlays  25  back to the second wale  14 ( 2 ). An inlay  26  is made on wale  14 ( 2 ) then the weft thread  15  crosses-over with two inlays  27  to the first wale  14 ( 1 ). The pattern is completed with four inlays  28  on the first wale  14 ( 1 ). 
     The pattern of a pair of weft threads  17 ,  19  is illustrated in  FIG. 3 . The first weft thread  17  of the pair follows a pattern that is the inversion of the pattern as described in relation to  FIG. 2 ; the plane of inversion being parallel to the courses and perpendicular to the wales. The second weft thread  19  of the pair follows a pattern that is a mirror image of the pattern followed by the first weft thread  17 ; the mirror plane being substantially parallel to the wales. Thus, the second weft thread  19  starts the pattern at the third wale  18 ( 3 ) and inlays are lapped in the opposite direction to those of the first weft thread  17 . The first  17  and second  19  weft threads cross at courses four to six,  30 , and again at courses  22  and  24 ,  32 . The pair of weft threads  17 ,  19  interconnects and ties-in four wales  18 ( 1 ),  18 ( 2 ),  18 ( 3 ) and a fourth wale adjacent to  18 ( 3 ) (the fourth wale not being shown in  FIG. 3 ). 
     The pattern of a plurality of the first pairs of weft threads  15 ,  16  is illustrated in  FIG. 4 . Each pair of weft threads  15 ,  16  consists of a first weft thread  15  following the pattern described above and illustrated in  FIG. 2 , and a second weft thread  16  following the mirror image of that pattern.  FIG. 4  illustrates the pattern formed by a plurality of pairs of weft threads  15 ,  16 , and represents the pattern of half of the weft threads in an embodiment of a tulle according to the present invention. The pattern as illustrated over the line  36  repeats above the repeat line  34 . 
     The pattern of a plurality of the second pairs of weft threads  17 ,  19  is illustrated in  FIG. 5 . Each pair of weft threads  17 ,  19  follows the pattern described above and illustrated in  FIG. 3 . The pattern of the second pairs of weft threads  17 ,  19  is an inversion of the first pair of weft threads  15 ,  16  illustrated in  FIG. 4  and represents the pattern of the other half of the weft threads in an embodiment of a tulle according to the present invention. The pattern as illustrated over the wales  38  repeats above the repeat line  34 . 
     The pattern of both the first and second pairs of weft threads  15 ,  16  and  17 ,  19  in a tulle according to an embodiment of the invention is illustrated in  FIG. 6 . The complete pattern as illustrated over the line  40  repeats above the repeat line  34 . The complete pattern exhibits an array of substantially hexagonal holes  46 ,  52 ,  54  defined by the weft threads  15 ,  16  and  17 ,  19  between crosses in the weft threads  15  and  16  at  42  and  48  and crosses between the weft threads  17  and  19  at  44  and  50 . 
     The tulle as illustrated in  FIGS. 2 to 6  may be produced using a Raschel warp knitting machine having 5 or more guide bars. Guide bar  1  is used to define the wales with a pillar stitch with guide bars  2  to  5  used to define inlay weft threads,  17 ,  15 ,  16 ,  19  respectively as illustrated in  FIGS. 2 to 6 . Table 1, below, describes the guide bar movements for the weft threads for the interlacing of the otherwise unconnected wales. 
     As discussed above, the guide bar movements for guide bars  2  and  3  (corresponding to weft threads  17  and  15 ) and guide bars  4  and  5  (corresponding to weft threads  16  and  19 ) are an inversion of each other. Also, the movements of guide bars  3  and  4  (weft threads  15  and  16 ) and guide bars  2  and  5  (weft threads  17  and  19 ) follow patterns that are mirror images of each other. 
     A tulle according to the invention is much more forgiving of differences in tension between threads, the pattern appears to spread out differences in tension, resulting in a much more regular and strong tulle. The knitted tulle&#39;s flexibility and robustness provide a tulle which is directly comparable in its properties to bobbinet tulle. 
     
       
         
               
               
               
               
               
             
           
               
                 TABLE 1 
               
               
                   
               
               
                 Inlays 
                 Bar 2 
                 Bar 3 
                 Bar 4 
                 Bar 5 
               
               
                   
               
             
             
               
                  1/ 
                 2 
                 0 
                 6 
                 4 
               
               
                  2/ 
                 0 
                 2 
                 4 
                 6 
               
               
                  3/ 
                 2 
                 4 
                 2 
                 4 
               
               
                  4/ 
                 0 
                 2 
                 4 
                 6 
               
               
                  5/ 
                 2 
                 4 
                 2 
                 4 
               
               
                  6/ 
                 4 
                 2 
                 4 
                 2 
               
               
                  7/ 
                 2 
                 4 
                 2 
                 4 
               
               
                  8/ 
                 4 
                 2 
                 4 
                 2 
               
               
                  9/ 
                 6 
                 4 
                 2 
                 0 
               
               
                 10/ 
                 4 
                 2 
                 4 
                 2 
               
               
                 11/ 
                 6 
                 4 
                 2 
                 0 
               
               
                 12/ 
                 4 
                 6 
                 0 
                 2 
               
               
                 13/ 
                 6 
                 4 
                 2 
                 0 
               
               
                 14/ 
                 4 
                 6 
                 0 
                 2 
               
               
                 15/ 
                 2 
                 4 
                 2 
                 4 
               
               
                 16/ 
                 4 
                 6 
                 0 
                 2 
               
               
                 17/ 
                 2 
                 4 
                 2 
                 4 
               
               
                 18/ 
                 4 
                 2 
                 4 
                 2 
               
               
                 19/ 
                 2 
                 4 
                 2 
                 4 
               
               
                 20/ 
                 4 
                 2 
                 4 
                 2 
               
               
                 21/ 
                 2 
                 0 
                 6 
                 4 
               
               
                 22/ 
                 4 
                 2 
                 4 
                 2 
               
               
                 23/ 
                 2 
                 0 
                 6 
                 4 
               
               
                 24/ 
                 0 
                 2 
                 4 
                 6