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New national standard for woven bags

     Plastic woven bags are polypropylene, polyethylene resin as the main raw material, extruded, stretched into flat wire, and then woven, bag-making products. National standards for the production of woven bags is China has been the continuation of the national standard to regulate the woven bag industry, the national woven bag manufacturers are in accordance with national standards for production, let us look at the implementation of the new national standard in the end what kind of requirements for woven bags.

      The original standard GB/T 8946-1998 "plastic woven bags", in the "4.1 appearance quality" clause "broken wire" in the provisions of "the same warp, weft and broken wire less than 3 ".

     The original standard GB/T 8947-1998 "composite plastic woven bags", in the "4.1 appearance quality" clause "thin block" in the "interval of 100mm, warp and weft wire breakage of not more than 2 ".

      We suggest that; the newly revised national standard "General technical requirements for plastic woven bags" in the "appearance quality" clause "broken wire", should be specified as: warp, weft flat wire intersection should not be broken at the same time.

      Suggestions are as follows:

      1, this standard to be stricter than the original standard GB/T 8946-1998 "plastic woven bags" and GB/T 8947-1998 "composite plastic woven bags". The original standard requires "the same warp, weft and broken wire less than 3", this standard requires "warp, weft flat wire intersection should not be broken at the same time." In other words, only one broken wire is allowed in the same place.

      2, today's weaving production technology and equipment, warp and weft at the same place, the possibility of simultaneous breakage almost does not exist.

For circular weaving machine, if the warp wire broken, not the introduction of the broken warp wire, there will be a section of double warp wire, the introduction will eliminate the double warp wire or a section of warp wire overlap, in the cloth will not appear at all broken phenomenon; if the weft wire broken, timely stop joint, the cloth will not appear broken, there is only one possibility, not timely stop, there will be a section of thin block cloth, this section of cloth is definitely inferior.

      For the water jet loom, the warp filament breakage is the same as for the circular loom, but the chance of occurrence is smaller than for the circular loom; there is no such thing as a broken weft filament, only the weft filament is not sprayed in place, and a thin block does not appear to be serious, and the continuous appearance is inferior cloth.

      For shuttle looms such as Sulzer, the warp breakage is the same as on circular looms, but less likely to occur than on circular looms; a shuttle breakage or run-out will result in a section of double weft yarn, and whether it is enough to make a thin block depends on the length of the run-out weft yarn and the weft beating situation.

      And these looms are the production of sheet cloth, only suitable for bonded sewing bags, production accounted for very little plastic knitting total.

      3. when weaving warp, weft at the same time the possibility of broken wire is small, this situation is generally the accidental stabbing of the woven fabric.


      4.  since the woven warp and weft at the same time the possibility of breaking small, why do we have to specify this indicator? This is due to the tensile test strength of the part of the warp and weft at the same time broken wire is low, more importantly, when the drop test, warp and weft at the same time broken wire will expand into a hole and leak material.


      Standards for plastic woven bags:


      National standard GB/T8946-1998, "the bag will be flattened, in the bag of the upper, lower two diagonal circled 100mm × 100mm two squares, the outer edge of the square and the bag edge line 100mm apart, visually inspect the square of the warp, weft root, take the average, counting when the final point of less than one, according to a count. "The national standard specifies the woven density at the same time, specifying the density tolerance. Woven density depends mainly on the packaged product and is decided by the user.


    Then we are to understand the parameters of the woven bag: commonly used woven fabric density is 36 x 36 roots/10cm², 40 x 40 roots/10cm², 48 x 48 roots/10cm².


1. Weave density tolerance.

    Woven density tolerance refers to the number of roots that are more or less flat than the given standard woven density.


2. Woven fabric unit area mass.

   Woven fabric weight per unit area is expressed in square meters of grams, is an important technical indicator of the woven fabric. Square meter weight number mainly depends on the warp and weft density and the thickness of the flat wire, square meter weight number affects the tensile strength of woven fabric, load capacity, square meter weight number is a major part of the production enterprises to control costs.

3. Woven fabric tensile load.

    Tensile load is also known as tensile strength, tensile strength. For woven fabric grams to withstand the warp and weft of the two directions of the tensile load, so called warp, weft tensile load.


4. Width.

    A variety of woven fabric width directly affects the bag-making process. For the cylinder cloth with folded warp width, folded warp is equal to half of the circumference. Width shrinkage, the width of all woven fabric weaving rolled, in the roll cutting, printing, sewing, the width of the bag made are slightly less than the width of the roll, we call the width shrinkage.


5.Hand feel.

PP flat wire woven fabric feel thicker, broader, thicker and harder. HDPE flat wire woven fabric feel softer, lubricated, not dense. In the PP flat wire material added calcium masterbatch, the feel is quite broad, PP in less add HDPE will make it softer. Flat wire narrow, woven flat, soft feel, flat wire wide, woven cloth folded wire more, rough feel.