Plastic films
AssigneeIRPLAST S.p.A.
InventorsCarmelo Di Costanzo, Giuseppe Tiberini, Giulia Antidormi, Giacomo Soluri
Life of this patent
Estimating the term…
Abstract
Use of olefin-based plastic films for obtaining for obtaining roll tapes for closing containers, the films having a thickness in the range from 10 to 22 μm, flexural rigidity (N·mm) in the range 0.5×10−2-4.5×10−2 neglecting a constant 1/[12×(1−v2)] being v the Poisson modulus, an elongation at break in MD, determined according to ASTM D 882, lower than 130%, a dimensional stability, determined according to the OPMA TC 4 standard at 130° C. for 5 minutes in air in MD in the range from 0 to −10% and in TD from −4 to +4%.
Claims22
A process for obtaining roll tapes for closing containers wherein polyolefin-based plastic films having a thickness in the range from 10 to 22 μm;
- a flexural rigidity (N·mm) in the range of 0.5×10−2-4.5×10−2 neglecting a constant 1/[12×(1−v2)], v being the Poisson modulus;
- an elongation at break in MD, determined according to ASTM D 882, lower than 130%;
- and a dimensional stability, determined according to the OPMA TC 4 standard at 130° C. for 5 minutes in air in MD in the range from 0 to −10% and in TD from −4 to +4%, are used.
A process for preparing plastic films, comprising the following steps:
- coextrusion of the film sheet;
- sheet cooling on the surface of cooled chill roll dipped in a water bath;
- sheet heating;
- sheet stretching and orientation by a simultaneous orientation process in MD and TD direction by taking the sheet edges, having an higher thickness than the sheet, with a series of pliers/clamps independently driven by linear synchronous induction motors, wherein the pliers/clamps set runs on divergent stretching rails;
- For the stretching step a stretching frame comprising one or more sections located inside an oven at temperatures comprised between about 150° and 190° C., is used;
- the MD longitudinal stretching ratios being comprised from about 4:1 to about 9:1 and the TD transversal stretching ratios from about 3:1 to about 8:1;
- heat setting in TD, preferably through a convergence of the stretching rails and heat setting in MD by decreasing the linear pliers speed;
- wherein the plastic films are polyolefin-based plastic film having a thickness in the range from 10 to 22 μm;
- a flexural rigidity (N·mm) in the range of 0.5×10−2-4.5×10−2 neglecting a constant 1/[12×(1−v2)], v being the Poisson modulus;
- an elongation at break in MD, determined according to ASTM D 882, lower than 130%;
- and a dimensional stability, determined according to the OPMA TC 4 standard at 130° C. for 5 minutes in air in MD in the range from 0 to −10% and in TD from −4 to +4%.
A polyolefin-based plastic film having a thickness in the range from 10 to 22 μm;
- a flexural rigidity (N·mm) in the range of 0.5×10−2-4.5×10−2 neglecting a constant 1/[12×(1−v2)], v being the Poisson modulus;
- an elongation at break in MD, determined according to ASTM D 882, lower than 130%;
- and a dimensional stability, determined according to the OPMA TC 4 standard at 130° C. for 5 minutes in air in MD in the range from 0 to −10% and in TD from −4 to +4%.
Dependencies are inferred from the claim text.