Grasscatcher bag fabric

A 3-bar Raschel warp knit fabric for use in grasscatcher bags which has an additional high tenacity yarn knit in to provide a lower elongation yarn in the course direction to prevent the grasscatcher bag from dragging the ground as it is being filled. The fabric also has a second textured needle lap stitch yarn to provide cover and to prevent the exhaust of dust to the atmosphere from the interior of the bag.

This invention relates to a knit fabric for use in grasscatcher bags which 
requires high tenacity or strength for impact but has reduced elongation 
so it does not drag the ground in use. 
It is an object of the invention to provide a warp knit, high tenacity 
fabric for use in grasscatcher bags which has substantially lower 
elongation in the course or fill direction.

Looking now to FIG. 1 there is shown a conventional lawn mower 10 with a 
grasscatcher bag 12 connected to the discharge chute 14 thereof. The lawn 
mower 10 is shown as a push style but obviously other mowers such as a 
riding mower could employ the bag 12 on the discharge thereof. The 
grasscatcher bag 12 has a suitable snap-on collar or band 15 around the 
course or fill direction of the fabric to engage the circumference of the 
discharge chute 14. 
The standard grasscatcher bag is made from high tenacity yarn (840-1300 
den.) in order to pass the performance requirements set by the Outdoor 
Power Equipment Institute but tends to elongate and stretch when subjected 
to lead as the bag fills up. The standard grass catcher bag shown in FIG. 
1 typically is formed by forming a flat fabric into a tube shape and 
sewing the edges thereof together. The bag tends to sag and sometimes 
drags the ground. To prevent this condition the herein developed fabric 
has been developed. 
The warp knit fabric 16 used in the construction of the bag 12 is a 3-bar 
Raschel warp knit fabric with the additional bar knitting in a lower 
elongation yarn in the course or fill direction. As shown in FIGS. 2 and 
3, bar 3 which is knitting a high tenacity 150 denier polyester yarn 18 
provides lower elongation in the course or fill direction while bars 1 and 
2 knitting a drawn and textured polyester yarn 20 and 22, respectively, to 
maintain the required tensile strength in bag 12. Yarn 20 is a 1/150/34 
drawn polyester yarn while yarn 22 is a 2/150/34 textured polyester yarn. 
To provide the particular fabric 16 the yarn on bar 1 is knitting a 0-1, 
1-0 pattern which is a conventional chain stitch, the yarn on bar 2 is 
knitting a 4-5, 1-0 pattern which is a conventional multiple needle lap 
stitch and the yarn on bar 3 is knitting 2-2, 0-0. It should be noted that 
each adjacent wale is connected to the next adjacent wale by the yarn 18 
to inhibit elongation of the fabric in the course or fill direction 
without inhibiting the overall tensile strength of the fabric. In 
describing the fabric 16 the terms fill and course direction are used 
interchangeably while the term wale and warp direction are used 
interchangeably. By the terms fill or course direction it is meant the 
widthwise direction of the fabric as it is being knit and the warp or wale 
direction is the machine direction of the fabric. 
In the preferred form of the invention the courses/inch is 21 and the 
wales/inch is 18 allowing the use of finer denier yarns without loss of 
strength or permeability. The increased density of the fabric permits the 
use of 150 denier polyester yarn while the texturing of the wale yarn 20 
provides porosity for the passage of air but prevents the exhaust of dust 
therefrom. The use of 150 denier yarn, which is a common yarn, reduces the 
raw material cost of the finished grasscatcher bag fabric. 
U.S. Pat. No. 4,785,613 discloses a grass catcher bag fabric similar to 
that disclosed herein. The herein disclosed fabric employs a closed 
textured needle lap stitch which substantially reduces the air 
permeability of the bag and lowers the elongation of the bag in the fill 
direction to prevent the bag from dragging the ground. To illustrate these 
advantages, the following table illustrates the superior performance of 
the disclosed fabric over that disclosed in U.S. Pat. No. 4,785,613 supra. 
______________________________________ 
U.S. Pat. 
Disclosed No. 4,785,613 
Fabric Fabric 
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Air Permeability 
114.4 274.0 
Lightfastness 60 Hrs. 
5.0 5.0 
Lightfastness 100 Hrs. 
4.5 5.0 
Warp Fill Warp Fill 
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Tensile @ Break (lb) 
180.4 227.2 329.3 588.7 
Elongation @ Break % 
43.3 75.9 81.7 116.7 
Elongation @ 5 lb. % 
1.5 2.9 1.2 17.1 
Elongation @ 10 lb. % 
2.1 7.5 1.7 24.4 
Elongation @ 30 lb. % 
4.3 24.2 3.5 36.4 
Elongation @ 50 lb. % 
8.4 32.2 5.9 43.4 
Elongation @ 100 lb. % 
18.2 46.4 13.2 53.4 
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As indicated in the above chart, the disclosed fabric has an unexpected air 
permeability at least 50% lower than that of the U.S. Pat. No. 4,785,613 
fabric thereby substantially reducing the amount of dust, etc. exhausted 
to the atmosphere and at each level of force (5 lb. to 100 lb.) has a 
lower fill elongation due to the closed stitch construction. 
In a modified form of the invention other polyolefin yarns, such as 
polypropylene, can be used in bar 1 and bar 2 along with the lower 
elongation HT (high tenacity) polyester yarn on bar 3. In this form of the 
invention the needle lap stitch yarn in bar 2 will not be textured. 
It is obvious that the above described fabric provides substantially lower 
elongation at low loads so that the grasscatcher bag made therefrom will 
be sturdier and cheaper but at the same time maintains the warp tensile 
strength to prevent objects from being thrown through the bag material 
while maintaining permeability. 
Although the preferred embodiment of the invention has been described 
specifically it is contemplated that many changes may be made without 
departing from the scope or spirit of the invention and it is desired that 
the invention be limited only by the scope of the claims.