What are the material composition of rice plastic packaging bags
The plastics used in rice plastic packaging bags are made of multiple layers of plastic films, including:
1. Polyethylene (PE for short)
It is a thermoplastic resin obtained by the polymerization of ethylene. In industry, co-polymers of ethylene with small amounts of alpha-ole fins are also included. Polyethylene is odorless, non-toxic, feels like wax, has excellent low temperature resistance (minimum operating temperature can reach -100~-70°C), good chemical stability, and can resist most acid and alkali erosion (not resistant to oxidation nature acid). "Polyethylene" is flexible and flexible, lighter than water, non-toxic, and has superior dielectric properties. It is flammable and continues to burn after leaving the fire. The water permeability is low, and the organic vapor permeability is relatively large. The transparency of polyethylene decreases with the increase of crystallinity. Under a certain crystallinity, the transparency increases with the increase of molecular weight. The melting point range of high density polyethylene is 132-135 ° C, and the melting point of low density polyethylene is lower (112 ° C) and has a wide range. It is insoluble in common solvents at room temperature, with low water absorption and excellent electrical insulation. Above 70℃, it can be dissolved in a small amount in toluene, amyl acetate, trichloroethylene and other solvents.
Processing: Polyethylene can be processed by blow molding, extrusion, injection molding and other methods, and is widely used in the manufacture of films, hollow products, fibers and daily sundries.
Made into film: It can be widely used as packaging materials for various foods, clothing, medicine, fertilizers, industrial products and agricultural films. It can also be processed into a composite film by extrusion for packaging heavy objects. Since 1975, high-density polyethylene film has also been developed, which has high strength, low temperature resistance, moisture resistance, and good print-ability and process-ability. The biggest use of linear low-density polyethylene is also to make film, its strength and toughness are better than low-density polyethylene, puncture resistance and rigidity are also better, although the transparency is poor, it is still slightly better than high-density polyethylene . PE film has strong chemical stability and certain acid and alkali resistance at room temperature, and is insoluble in any solvent. It is often the first choice for the inner layer material of food packaging bags.
2. Polyester film (referred to as PET film)
It is characterized by high temperature resistance, good printing, easy processing, good voltage resistance and insulation, fire resistance through UL certification 94VTM-2 certification, environmental protection has passed SGS, ROSH certification, using polyethylene terephthalate as raw material, using It is made into thick sheet by extrusion method, and then made into thin film material by biaxial stretching. It is a colorless, transparent and glossy film with excellent mechanical properties, high rigidity, hardness and toughness, puncture resistance, friction resistance, high temperature and low temperature resistance, chemical resistance, oil resistance, air tightness and fragrance retention. Good, it is one of the commonly used barrier composite film substrates. However, the price of polyester film is relatively high, and the general thickness is 0.12mm. It is often used as the outer layer material of retort packaging and has good print-ability.
3. Poly-amide (referred to as PA)
The main chain of the system is a polymer containing many repeating amide groups, and this type of polymer is commonly known as nylon. Compared with general plastics, poly-amide has the advantages of wear resistance, toughness, chemical resistance, heat resistance, cold resistance, easy molding, self-lubrication, non-toxicity, easy dyeing, etc. The biggest feature of the film is the low oxygen transmission rate. The packaging container is conducive to the long-term storage of the product without air leakage and moisture deterioration. It is one of the necessary basic materials in vacuum packaging. Among all the varieties of poly-amide, the bi-axially oriented nylon film is mainly used for food packaging; the advantages are high puncture resistance, impact strength, friction strength, bending strength, and good gas barrier properties, but the disadvantage is poor heat sealing , when used, it is often combined with a substrate film with good heat-sealing properties.
For frozen food packaging, it mainly utilizes the characteristics of high film strength, good puncture resistance and excellent cold resistance.
It is used for seasoning packaging of soup noodle liquid, mainly using its high strength, good puncture resistance, especially oil resistance.
It is used for retort-resistant food packaging, mainly using its oil resistance, heat resistance, good gas barrier properties, and puncture resistance.
4. Bi-axially oriented polypropylene film (BOPP for short)
Its production is that the melt of high molecular polypropylene is first made into sheets or thick films through a long and narrow head, and then in a special stretching machine, at a certain temperature and a set speed, simultaneously or step by step. It is a film made by stretching in two vertical directions (longitudinal, transverse), and after appropriate cooling or heat treatment or special processing (such as corona, coating, etc.).
BOPP has high transparency and gloss, excellent ink and coating adhesion, heat sealing strength, water vapor and grease barrier properties, UV barrier properties, high-grade appearance of pearl luster, high barrier properties and low static electricity properties. It is commonly used as a basic material for bag printing and compounding of packaging bags.
The material of the packaging bag container is closely related to chemical properties, and the above is part of the basic material film of common food packaging bags. For example, Kraft paper, aluminum foil, CPP, and YOPP are also one of the composite materials for rice packaging bags.
