BOPP heat-seal film It can be produced using either the tubular‑film or flat‑film process and is a highly important flexible packaging material. It is colorless, odorless, tasteless, and non‑toxic, while also exhibiting high tensile strength, impact resistance, rigidity, toughness, and excellent transparency. Now, let’s explore the advantages and limitations of BOPP heat‑seal films.

　　The production of BOPP heat-seal film involves first extruding a molten polypropylene polymer through a narrow die to form a thin sheet or thick film. This is then processed in a specialized stretching machine, where it undergoes appropriate cooling, thermal treatment, or special surface modifications—such as corona treatment or coating—to produce a plastic film. The film is stretched at a specified temperature and speed, either simultaneously or in stages, along two perpendicular directions: the longitudinal and transverse axes.

　　BOPP heat-seal films can be produced by either the tubular‑film or flat‑film process. Flat‑film‑produced BOPP heat‑seal films, owing to their higher draw ratio (up to 8–10), exhibit greater tensile strength than those made by the tubular‑film method. Depending on the manufacturing process, the resulting BOPP heat‑seal films also differ in performance, with improved thickness uniformity.

　　To achieve excellent overall performance and meet the demands of specialized applications, BOPP can be laminated with LDPE (CPP), PE, PT, PO, PVA, and other materials, yielding superior barrier properties against gases and moisture, as well as exceptional transparency and resistance to high and low temperatures, steam sterilization, and oil. In production, multilayer lamination is typically employed. BOPP heat-seal films can be combined with a wide range of substrates, and the resulting composite films are suitable for packaging oily foods, gourmet products, dried goods, marinated items, and oil‑resistant applications.

　　A highly important flexible packaging material, it has low surface energy and requires surface treatment prior to coating and printing. It exhibits excellent printability, is colorless, odorless, tasteless, and non‑toxic, while also offering high tensile strength, impact resistance, rigidity, toughness, and good transparency. Its ability to accept multicolor printing delivers an attractive visual appearance, making it a common choice as the outer layer in composite films.

　　BOPP film also has certain drawbacks, such as a tendency to accumulate static electricity and the lack of heat‑sealability. To produce heat‑sealable BOPP heat‑seal film, the surface can be treated with corona discharge, followed by coating with heat‑sealable resin dispersions like PVDC latex or EVA latex, or with solvent‑based adhesives. On high‑speed production lines, BOPP heat‑seal film is prone to static buildup, so static eliminators should be installed. Extrusion coating or co‑extrusion can also be employed. This film is widely used for packaging bread, clothing, socks, and for covering tobacco products and book covers. The induced tear strength increases after stretching, but the secondary tear strength remains relatively low. Therefore, no cuts or slits should be left on either end of the BOPP heat‑seal film; otherwise, the film may easily tear during printing or lamination.