Microporous Film Stretching Sequence for Lower-Cost Production

The patent divides the stretching process into two separate sequential operations (longitudinal stretching followed by transverse stretching) instead of using a single biaxial stretching machine. This segmentation allows the use of simpler, less expensive uniaxial stretching equipment while achieving the same microporous film quality, thereby reducing equipment investment cost while maintaining manufacturing precision

The patent introduces an intermediary aging step between longitudinal and transverse stretching processes. This aging step acts as a mediator that allows the film to stabilize its structure before the second stretching operation, enabling the use of sequential uniaxial stretching instead of simultaneous biaxial stretching, thus reducing equipment complexity and cost while maintaining product quality

The patent segments the complex biaxial stretching process into simpler sequential uniaxial stretching steps with an intermediate aging phase. This segmentation reduces device complexity by using standard uniaxial stretching equipment instead of complex biaxial stretching machines, while maintaining the desired material properties through the combined effect of the sequential processes

The patent applies preliminary aging treatment to the film after longitudinal stretching and before transverse stretching. This preliminary action prepares the film structure to accommodate the second stretching operation, simplifying the overall process by allowing the use of separate uniaxial machines instead of requiring complex synchronized biaxial stretching equipment