TRANSPARENT COEXTRUDED FILMS AND PROCESSES FOR MAKING SUCH FILMS

• Main Authors: VINCK, MICHAEL, VAN LOON, ACHIEL, J, TIERENS, MARC
• Format: Patent
• Language: English; French
• Published: 13.12.2007
• Subjects: AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING; LAYERED PRODUCTS; LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT ORNON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM; PERFORMING OPERATIONS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDEDFOR; SHAPING OR JOINING OF PLASTICS; TRANSPORTING; WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE, IN GENERAL

The invention relates to high clarity multi-layer films where the clarity is improved by reducing the thickness of an LDPE containing core layer beyond its pure draw down limit. More particularly the invention relates to a coextruded multilayer film having (i) a pair of skin layers comprising at least 60 wt% of an LLDPE based on the total weight of polymer in the skin layer; and (ii) at least one core layer comprising from 5 to 100 wt% based on the total weight of polymer in the core layer of an LDPE, which a core layer has a thickness less than the DDL(F0) draw down limit of the LDPE in the core layer. The invention is especially applicable to LDPE's in the core layer having a relatively low MI. L'invention concerne des films multicouches de grande clarté, la clarté étant améliorée en réduisant l'épaisseur d'une couche centrale contenant du LDPE en dessous de sa limite de réduction de l'étirage pure. L'invention concerne plus particulièrement un film multicouche coextrudé ayant (i) une paire de couches externes comprenant au moins 60 % en poids d'un LLDPE par rapport au poids total de polymère dans la couche externe; et (ii) au moins une couche centrale comprenant de 5 à 100 % en poids par rapport au poids total de polymère dans la couche centrale d'un LDPE, la couche centrale ayant une épaisseur inférieure à la limite de réduction de l'étirage DDL(F0) du LDPE dans la couche centrale. L'invention est notamment applicable à des LDPE dans la couche centrale ayant un MI relativement faible.