sentences:  Rausing strove to improve the Tetra Classic system, beset with many technical problems during the 1950s, and spent enormous amounts on development.The different projects – the tetrahedron, the aseptic packaging technology, Tetra Brik – all demanded large resources and the company had financial troubles well into the 1960s.Tetra Pak's commercial breakthrough did not arrive until the mid-1960s with the new Tetra Brik package, introduced in 1963, and the development of the aseptic technology.