Different types of consumer containers are used for food packaging: glass, metal, polymer. Polymer containers are in the greatest demand among consumers, due to such advantages as cheapness, small weight, unlimited range of products and volume, pleasant, bright appearance. In the food industry, hard, semi-hard, soft and other consumer polymer containers are used. To use such packaging in technology with high-temperature heat treatment of food products, it must have a heat-resistant barrier layer. Therefore, the object of research is a polymer combined C-PET container, which consists of a semi-rigid container-tray and a heat-resistant multi-layer polymer soft film for its closure. C-PET packaging is made of barrier polymer materials that ensure its mechanical resistance to high temperatures. Therefore, such containers can withstand high-temperature processing and guarantee the tightness of the package and the microbiological stability of the product during storage. Each polymer material has its own specific indicators of heat resistance. The work solves the problem of using the latest polymeric C-PET containers for long-term storage food products, investigates the conditions for preserving the tightness of the containers during heat treatment, which are ensured by the clogging strength parameter. Different types of polymer films for sealing C-PET packaging with the product are also investigated and their mechanical characteristics are compared. In the course of the study, a standard membrane-compensation method was used to measure the clogging strength or depressurization pressure of the package. The essence of the obtained results: the parameters of the use of different types of polymer films of different types were experimentally determined, on the basis of which the type of film was chosen, which ensures the clogging strength of C-PET containers. The results are explained by the fact that the depressurization pressure value obtained will allow to develop scientifically based thermal modes of sterilization and pasteurization for food products in C-PET containers. This will make it possible in practice for enterprises to apply the same regimes and produce high-quality, biologically stable, safe food products with a long shelf life.