Oriented polypropylene film

The double-bubble process may be used to produce biaxiaHy oriented film, primarily polypropylene. In this process the first bubble formation is similar to the conventional blown film, except that the bubble is not coUapsed. Rather it is reheated to the orientation temperature and blown and drawn further in a second stage. It is then coUapsed, sUt, and wound. This process is generally limited to a final film thickness of less than 24 p.m. 

BiaxiaHy oriented films have excellent tensile strength properties and good tear and impact properties. They are especially well regarded for their brilliance and clarity. Essentially all poly(ethylene terephthalate) film is biaxiaHy oriented, and more than 80% of polypropylene film is biaxiaHy oriented. Polystyrene film is oriented, and a lesser amount of polyethylene, polyamide, poly(vinyl chloride), and other polymers are so processed. Some of the specialty films, like polyimides (qv), are also oriented. 

Fibrillated tape, again particularly successful with polypropylene, in which oriented film is stretched so much that fibrillation occurs. 

An important application for polypropylene is film tape. This is made by slitting unoriented film (cast or blown) into tapes 2 or 3.5 mm wide and stretching under heat about seven-fold. With cast film the orientation is more completely monoaxial and there is a tendency for the film to split along its length (fibrillate). Tubular film does not self-split so easily and also has a somewhat softer feel. Such tapes may be woven into sacks and these have... 

Sometimes the hazy optical properties of polypropylene are a detriment to its use in thin films. To address this problem, as well as to improve physical properties and reduce material costs, we can orient the molecular chains by stretching the polymer film after it has left the extrusion die. There are two methods of orienting films, film blowing, shown in Fig. 11.6, and tentering, shown in Fig, 19.6. 

Polypropylene film is found in a variety of applications. Films are thin plastic sheets with thicknesses less than 250 pm. Applications for these films include candy mappers, plastic label material, electrical capacitors (which requires very pure polymer), and fiber glass insulation backing. There are two general categories of polypropylene films unoriented and oriented. Films are manufactured through either a cast or a blown film extrusion process. Oriented films exhibit improved strength relative to unoriented films. This means that they can be... 

Oriented polypropylene is used for clear films used as food wrap. What advantageous properties do the oriented films have over standard films How can a polymer that is, typically semicrystalline be transparent ... 

The cellulose used was Whatman 41 filter paper, the polyethylene, low density, was supplied by Union Carbide as film (0.12mm) and polypropylene was isotactic double oriented film (0.06mm) ex-Shell. 

ISO/TS 15874-7 2003 Plastics piping systems for hot and cold water installations -Polypropylene (PP) - Part 7 Guidance for the assessment of conformity ISO 17555 2003 Plastics - Film and sheeting - Biaxially oriented polypropylene (PP) films (available in English only)... 

Biaxially oriented polypropylene (BOPP) films have higher stiffness than cast films and consequently can be used in much thinner gauges. Homopolvmers are used almost exclusively to provide maximum stiffness and water-vapor barrier. Oriented films are produced by the tenter frame and bubble processes. 

Bi-Ax International is a Canadian company dedicated to oriented polylactide film (OPLA) and biaxially oriented polypropylene (BOPP) film. Bi-Ax International is headquartered in Wingham, Ontario, Canada, and operates a separate manufacturing facility in Tiverton, Ontario, Canada. 

Materials. Biaxially oriented polypropylene (PP) films of 50 um thickness were obtained from 3M and have been described (2). PMDA-ODA (PI) was Kapton H polyimide from Dupont. Copper-plated PTFE films were obtained from Spire Corporation (Bedford, MA). They were prepared using the Ion Beam Enhanced Deposition (IBED) process in which a 100 nm thick Cu film was vapor-deposited onto a PTFE substrate in the presence of a beam of 400 eV Ar+ ions of 25 uA/cm2 (IQ). Shortly before SIMS analysis, the Cu film was removed slowly by peeling at 90° in ambient conditions. Metal-coated PI films were prepared by sputtering 50 nm Cr and 1 um Cu onto a 50 um thick Kapton film on both sides. Thermal annealing was performed in a vacuum chamber at 2xl0 6 torr using a quartz lamp as the heating source. The samples were held for 15 min at the desired temperature and then cooled down to ambient temperature inside the chamber for about 2 hours. Just prior to SIMS analysis, the metal films were peeled slowly at 90° and then immediately introduced into the vacuum chamber of the instrument. 

A typical formulation for a polypropylene (PP) film used for wrapping biscuits would be PP 100 pph pentaerythritol tetrakis[3-(3,5-di-tertbutyl-4-hydroxyphenyl) propionate] 0.1 pph phosphorous acid, tris(2,4-di-tert-butylphenyl)ester 0.1 pph emcamide 0.05 pph. Nucleators, such as substituted benzylidene sorbitols, can be added to improve the clarity of PP and LDPE (see Eig. 10.4). Oriented polypropylene (OPP) films are also available where a higher transparency is required with improved strength. 

Of the backbone polymers used, polypropylene was isotactic, doubly oriented film of thickness 0.06 mm ex-Shell Chemicals (Aust) Pty. Limited, the polyethylene film was low density material of thickness 0.12 mm ex-Union Carbide (Aust) Pty Limited while the PVC film (0.20 mm) was supplied by ICI (Aust) Pty Limited. 

The additives were tested in polypropylene (Profax 6501, Hercules) films containing 0.1% Goodrite 3114 (phenolic antioxidant of B.F. Goodrich Co.) and. 05% calcium stearate. The candidate additives were added at 0.25% or 0.5% final concentrations as methylene chloride solutions (100 ml methylene chloride/lOOg polypropylene) and the mixture stirred 15-20 mins, while the solvent was allowed to evaporate. The resultant powder was then dried and extruded into 3/32 inch strand, which was cut into pellets. After drying, the pellets were extruded into a broad (8") band. A 1/4" section was slit from the band and oriented by drawing at 175°F at a 7 1 draw ratio. The dimensions of the oriented film are about 1 x 80 mils. 

Photomicrographs to observe additive compatibility in the oriented film were taken at 400X using a transmission light microscope. Blooming was measured at 70°C using unoriented film samples 7 mil in thickness. Thermal oxidative stability was measured in a circulating air oven at 140°C on polypropylene films 5" x 1" x. 025". 

As a result of this the manufacturers of polymers have found it necessary to exercise leadership in pioneering the methods by which their polymers are formed—sometimes to the extent that the manufacturer has himself often sold the polymer in the fabricated form. Hercules, for example, pioneered in the manufacture and sale of polypropylene resin. We soon realized, however, that the conversion of this resin to fiber and to film and to foam, would have to be done by us because of the complex technologies and large investments involved. Consequently, the resin manufacturer now finds himself selling polypropylene fiber, biaxially-oriented film, and foam—successfully too if I may be allowed to add. 

Ipelene. [IPEL Ltd.] Polypropylene bi-axially oriented film. 

MWB Film. [Hercules] Polypropylene film oriented film for multiwall bags. 

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