New Possibilities on Greenhouses Films Using Coextruded Structures, 2001 European PLC Conference Proceedings

Antonio Marín Trujillo, Juan Carlos Jiménez García--The coextrusion is a sophisticated technology relatively new in the thermoplastic polymers world. The beginning is dated in the 60’s, consisting basically in the combination of the melt polymer flows from two or more extruders into a single appropriate head. The main applications have been oriented in the direction of coatings, packaging or tubes but more and more are applied in blowing films for agricultural applications: covering greenhouses, mulching, small tunnels, soil disinfection, etc. The objective is to put and to keep in layers different polymers for taking advantage of the best properties of each in order to obtain films with specials characteristics that it should not be possible under monolayer technology. Repsol-YPF has developed special compounds, based on LDPE and EVA copolymers, for producing "tailored coex films" for covering greenhouses. With this compounds, combined in three layers structures, is possible to select the degree of visible light transmission, direct or diffused light, thermal effect, UV blocking, antidripping effect, etc.