The production of BOPP film is to first make a sheet or thick film from the melt of polymer polypropylene through a narrow machine head, and then stretch it in two vertical directions (longitudinal and transverse) simultaneously or step by step in a dedicated stretching machine at a certain temperature and set speed, and then make the film through appropriate cooling or heat treatment or special processing (such as corona discharge, coating, etc.).
classification
Common BOPP films include: regular biaxially oriented polypropylene film, heat sealed biaxially oriented polypropylene film, cigarette packaging film, biaxially oriented polypropylene pearl film, biaxially oriented polypropylene metalized film, matte film, etc.
advantage
BOPP film is a very important flexible packaging material. BOPP film is colorless, odorless, tasteless, non-toxic, and has high tensile strength, impact strength, rigidity, toughness, and good transparency.
BOPP film has low surface energy and requires corona treatment before coating or printing. After corona treatment, BOPP film has good printing adaptability and can achieve exquisite appearance effects through color matching printing. Therefore, it is commonly used as a surface layer material for composite films.
insufficient
BOPP film also has shortcomings, such as easy accumulation of static electricity and lack of heat sealing properties. On a high-speed production line, BOPP film is prone to static electricity and requires the installation of a static electricity remover.
In order to obtain heat sealable BOPP film, heat sealable resin adhesives such as PVDC latex, EVA latex, etc. can be coated on the surface of the BOPP film after corona treatment. Solvent adhesives can also be coated, and extrusion coating or co extrusion composite methods can be used to produce heat sealable BOPP film.
This film is widely used for packaging bread, clothes, shoes, socks, as well as cover packaging for cigarettes and books. The tear strength of BOPP film increases after stretching, but the secondary tear strength is very low. Therefore, there should be no cuts on both ends of BOPP film, otherwise it is easy to tear off during printing and lamination. After coating with BOPP adhesive, it can produce sealing tape, which is a market with a large amount of BOPP usage.
Production process
BOPP film can be produced using either the tube film method or the flat film method. The performance of BOPP films obtained by different processing methods also varies. The BOPP film produced by the flat film method has a higher tensile ratio (up to 8-10), resulting in higher strength and better uniformity of film thickness compared to the tube film method.
precautions
In order to achieve better comprehensive performance, multi-layer composite methods are usually used in the production process. BOPP can be compounded with various materials to meet special application needs. BOPP can be compounded with LDPE (CPP), PE, PT, PO, PVA, and other materials to achieve high gas resistance, moisture resistance, transparency, high and low temperature resistance, cooking and oil resistance. Different composite films can be applied to packaging oily foods, specialty foods, dry foods, impregnated foods, various steamed and cooked foods, monosodium glutamate, pancakes, rice cakes, and other products.
