| 摘要 |
An improved method for forming closed burstable pouches having breakable seals. The method includes selection of a laminated polymeric film which has two principal layers-an outer layer which is responsive, and an inner layer which is non-responsive, to a radio-frequency (RF) welding field, the inner layer being of a biaxially-oriented polymeric material such that its cohesive strength in its thickness direction is less than the cohesive strength of the outer layer. The outer layer has a higher melting point than the inner layer. With two sheets of such material placed with their inner surfaces in contact, the breakable seal is formed by applying an RF welding field for a time and at an intensity to heat the outer layers sufficiently to fuse the inner layers by heat transfer from the outer layers without melting the outer layers and without destroying the biaxially-oriented structure of the inner layer. |
