Method and apparatus for producing biaxially oriented polymer sheet

摘要

This invention provides a process for producing biaxially oriented polymer sheet. This process includes the steps of introducing a polymer slab into a deformation zone defined between working surfaces of a set of working tools including a first working tool and an opposed second working tool. The polymer slab is worked in the deformation zone to reduce slab gauge, during which the polymer material being worked flows bi-directionally while the material is not restricted in the lateral direction to produce biaxially oriented polymer sheet. At least the portion of the slab being worked is at a temperature above the glass transition temperature and below the melting temperature of the polymer material. The working surface of at least one working tool in the deformation zone is ultrasonically excited during working of the polymer slab. This invention also provides an apparatus for ultrasonically exciting the working surface of at least one working tool in a deformation zone where a polymer slab is introduced and worked between working surfaces of a set of opposed working tools. The apparatus includes tools for advancing the polymer slab and for working the slab by reducing slab gauge during which the polymer material flows bi-directionally to produce biaxially oriented polymer sheet.