Classification of polypropylene film
Polypropylene (PP) has a high melting point and excellent comprehensive properties. It is one of the most promising thermoplastic polymer materials today. Compared with other general thermoplastics, it has low price, small specific gravity, yield strength, tensile strength, and surface It has excellent mechanical properties such as strength, outstanding stress crack resistance and wear resistance, good chemical stability, easy molding and processing, and a wide range of applications. It has been widely used in chemicals, electrical appliances, automobiles, construction, packaging, etc. industry. At present, most of the packaging market from food to sundries uses plastic film instead of paper as a flexible packaging material. The plastic film used for commodity flexible packaging must meet the requirements of protection, workability, convenience and economy of commodity packaging materials, have appropriate strength, have barrier properties, stability, safety, aesthetics and transparency, and economical convenience Sex.
According to different processing techniques, polypropylene film can be divided into CPP film, BOPP film and IPP film. The relevant conditions are as follows:
CPP film and characteristics
CPP films and polypropylene films produced by the casting process. CPP films can be divided into general-purpose, metallized and retort films. The general-purpose type is a commonly used CPP film material, and the film can be adjusted within a certain range; the metalized type is a high-end CPP film product, which is made of polypropylene material with a special process and special specifications, and requires a higher film Heat-seal strength: The cooking type has higher requirements for heat resistance, usually random copolymers are used as raw materials, and the initial heat-sealing temperature is higher.
CPP film is a non-stretched, non-oriented flat extrusion film. It has light weight, high transparency, good flatness, good rigidity, strong mechanical adaptability, excellent heat sealability, moisture resistance and heat resistance, and smooth Good performance, high film production speed, uniform thickness, excellent moisture resistance, oil resistance, heat resistance and cold resistance, easy heat sealing, and its resistance and packaging machinery applicability are better than polyethylene film. It has excellent optical properties and can be used for automatic packaging. This technology has been introduced in China since the 1980s, with a large investment market and high added value of products. CPP film can be used for packaging of food, medicine, stationery, cosmetics and textiles through bag making, and is the largest amount in food packaging. CPP film is used to package heat-sterilized foods, condiments, soups, etc.; it can also be used on the surface, interlayer and auxiliary films of stationery products, such as loose leaves, protective films for photos and collectibles, as well as various labels and sample tapes .
BOPP film and characteristics
BOPP film is a polypropylene film produced by biaxial stretching technology. BOPP film can be divided into: antistatic film, which is obtained by coating an antistatic agent on a substrate or mixing an antistatic agent into a polymer; Anti-fog BOPP film, which has a good fresh-keeping effect, has been rapidly developed in the field of packaging products, and is obtained by stretching the easy-cut BOPP film in the vertical or horizontal direction; the inorganic filled and modified porous BOPP film is mixed with inorganic materials. It is made of blended polypropylene; there is also BOPP film that is easy to print.
BOPP film is a flexible packaging material developed in the 1960s, and it is also a highly transparent packaging material with excellent performance. Due to the orientation of the molecular segments and the increase in crystallinity, the tensile strength, tensile modulus of elasticity, impact strength, tear strength, tortuous life, etc. can be significantly improved, and a strong and tough film with high stiffness can be obtained. In addition, it has good moisture resistance, high gloss, good transparency, good gas barrier, moisture resistance, light weight, non-toxic, odorless, good dimensional stability, wide range of use, good printability, good electrical insulation, and excellent It has advantages such as quality stability and processability. Its comprehensive performance is better than that of transparent films such as moisture-proof cellophane and polyethylene film. It is hailed as the "Packaging Queen" by the packaging industry. Anti-static BOPP film is used for the packaging of carp fillets and other small foods; the easy-to-print BOPP film can be used for the packaging of cereals; the easy-cut BOPP film can be used for the packaging of soups and medicines; the inorganic filled and modified porous BOPP film is used for Packaging of deoxidizers and moisture-proof agents. The BOPP shrink film produced by the secondary stretch flat film method has good shrinkage, high shrinkage, improved tensile elastic modulus, and high gloss. It is often used for cigarette packaging.
IPP film and characteristics
IPP is a polypropylene film produced by down-blowing water-cooled film blowing technology. The optical properties and film thickness deviation of IPP film are slightly lower than CPP and BOPP, but the process is simple and the cost is low, and it can be packaged by simply sealing the upper and lower ends. The thickness of the packaging film is generally 0.03 ~ 0.05mm. The use of copolymer resins can obtain films with excellent strength at low temperatures. The modified IPP film has low temperature, high impact resistance, high smoothness, high transparency, high impact strength, good toughness, and antistatic properties. It includes a single-layer polypropylene film, which can be a homopolymer or a copolymer; a multi-layer co-extrusion blown extruded film is generally made of two kinds of raw materials: homo-isotactic polypropylene and copolymerization. IPP is mainly used for the packaging of fried snacks, bread, textiles, folders, record sleeves, sea vegetables, sports shoes, etc.
