1. Definition
National standard GB/T8946-1998, "the bag flattened, in the bag on the top, bottom two diagonal circled 100mm × 100mm two squares, the outside of the square and the bag edge line 100mm apart, visually inspect the square of the warp, weft roots, 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 packaging product, decided by the user.
2. Raw materials
Plastic woven terminology: woven bags are mainly speaking: plastic woven bags are made of polypropylene (English name pp) as the main raw material, extruded, stretched into flat wire, and then woven, compiled, bag-making.
3. Parameters
Commonly used woven fabric density is 36 × 36 root/10cm², 40 × 40 root/10cm², 48 × 48 root/10cm².
(1) Weave density tolerance
Woven density tolerance is more than the given standard woven density or reduce the number of flat wire roots.
(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 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 withstand the tensile load in both directions, so called the 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 fabrics after weaving and rolling, after spreading and cutting, printing, sewing, the width of the bag made are slightly less than the width of the roll, we call the width shrinkage.
(5) Feel
PP flat wire woven fabric feel thicker, broader, thicker and harder.
HDPE flat wire knitted fabric feel softer, lubricated, not dense.
Add calcium masterbatch in the PP flat wire material, the feel is quite broad, PP with less HDPE will make it softer.
Flat wire narrow, woven flat, soft feel, flat wire wide, woven cloth when the folded wire more, rough feel.
(6) Types
The main raw material for foreign production is polyethylene (PE), and domestic production is mainly polypropylene (PP), which is a thermoplastic resin made by polymerization of ethylene. In industry, it also includes copolymers of ethylene and a small amount of α-olefin. Polyethylene is odorless, non-toxic, feels like wax, has excellent low temperature resistance (the minimum operating temperature can reach -70 ~ -100 ℃), good chemical stability, can resist the erosion of most acids and bases (not resistant to acids with oxidizing properties), insoluble in general solvents at room temperature, small water absorption, excellent electrical insulation properties; but polyethylene is sensitive to environmental stress (chemical and mechanical effects), poor heat aging resistance. The properties of polyethylene vary from species to species, depending mainly on the molecular structure and density. Different production methods can be used to obtain products with different densities (0.91-0.96g/cm3). Polyethylene can be processed by the usual thermoplastic molding methods (see Plastics Processing). It has a wide range of uses, mainly for the manufacture of films, containers, pipes, monofilaments, wires and cables, daily necessities, etc., and can be used as high-frequency insulating materials for television, radar, etc. With the development of petrochemical industry, polyethylene production has been developed rapidly, and the output accounts for about 1/4 of the total plastic output. the total production capacity of polyethylene in the world was 24.65Mt in 1983, and the capacity of units under construction was 3.16Mt.
Polypropylene (PP)
A thermoplastic resin made from the polymerization of propylene. There are three configurations: isotactic, atactic and inter-routine, with isotactic as the main component of industrial products. Polypropylene also includes copolymers of propylene and a small amount of ethylene. It is usually a translucent colorless solid, odorless and non-toxic. Because of its regular structure and high crystallization, it has a high melting point of 167°C. It is heat resistant and its products can be sterilized by steam. The density is 0.90g/cm3, which is the lightest general-purpose plastic. Corrosion resistance, tensile strength of 30MPa, strength, rigidity and transparency are better than polyethylene. The disadvantage is poor resistance to low-temperature impact, easier to aging, but can be overcome by modifying and adding antioxidants, respectively.
Woven bag color is generally white or off-white, non-toxic and tasteless, generally less harmful to the human body, although it is manufactured by a variety of chemical plastics, but its environmental protection, and recycling efforts. Plastic woven bags are made of polypropylene resin as the main raw material, extruded, stretched into flat wire, and then woven, bag-making. Compound plastic woven bags are made of plastic woven fabric as the base material, compounded by the flow-delay method.
Woven bags are widely used, mainly for a variety of items into the packaging and packaging with a wide range of uses in industry. Used for packaging powder or granular solid materials and flexible items.
