The foreign production is mainly polyethylene (PE), and the domestic production is mainly polypropylene (PP), which is a thermoplastic resin made by polymerizing ethylene. In industry, it also includes copolymers of ethylene and a small amount of α-olefins. Polyethylene is odorless, non-toxic, feels like wax, has excellent low temperature resistance (minimum use temperature can reach -70 ~ -100 ℃), good chemical stability, can withstand most acids and alkalis (not resistant to oxidation) Acid), insoluble in common solvents at room temperature, low water absorption, and excellent electrical insulation properties; but polyethylene is very sensitive to environmental stress (chemical and mechanical effects), poor heat aging resistance. The properties of polyethylene vary from species to species, depending 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 using general thermoplastic molding methods (see Plastic Processing). It is widely used, mainly used to manufacture films, containers, pipes, monofilaments, wires and cables, daily necessities, etc., and can be used as high-frequency insulation materials for televisions, radars, etc. With the development of petrochemical industry, polyethylene production has developed rapidly, and the output accounts for about 1/4 of the total output of plastics. In 1983, the total production capacity of polyethylene in the world was 24.65Mt, and the capacity of the equipment under construction was 3.16Mt.
Polypropylene (PP)
A thermoplastic resin produced by the polymerization of propylene. There are three configurations: isotactic, non-regular and inter-regular, and industrial products use isotactic as the main component. Polypropylene also includes copolymers of propylene and a small amount of ethylene. Usually a translucent colorless solid, odorless and non-toxic. Due to the regular structure and high crystallization, the melting point is as high as 167 ℃, heat resistance, products can be steam sterilized is its outstanding advantage. With a density of 0.90g / cm3, it is the lightest general-purpose plastic. Corrosion resistance, tensile strength 30MPa, strength, rigidity and transparency are better than polyethylene. The disadvantage is that the low temperature impact resistance is poor, and it is easier to age, but it can be overcome by modification and addition of antioxidants.
Woven bags are generally white or off-white in color, non-toxic and odorless, and generally do little harm to human bodies. Although they are made of various chemical plastics, they are more environmentally friendly and have greater recycling efforts;
Woven bags are widely used, mainly used for the packaging and packaging of various items, and are widely used in industry;
Plastic woven bags are made of polypropylene resin as the main raw material, extruded and stretched into flat yarn, and then woven and bagged.
Composite plastic woven bag is made of plastic woven cloth as the base material and compounded by casting method.
This series of products is used for packaging powdery or granular solid materials and flexible items. Composite plastic woven bags are divided into two-in-one bags and three-in-one bags according to the main material composition.
According to the sewing method, it can be divided into sewing bottom bag, sewing bottom bag, insertion pocket, and adhesive sewing bag.
According to the effective width of the bag, it is divided into 350, 450, 500, 550, 600, 650, 700mm, and the special specifications are agreed by both parties.