Polypropylene Pop Quiz
March 1999
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Suppliers respond to pP's readers' challenges and questions regarding polypropylene substrates.
By Susan Friedman
You asked, and polypropylene film material suppliers responded. After conducting a phone survey to collect pP readers' most-encountered challenges with this popular substrate, related questions were forwarded to suppliers for comment. Read on for their suggestions.
Available Grades
Q: Converters have expressed difficulty finding polypropylene below 60 gauge. Does 60 gauge meet most application needs, or will thinner gauges need to become more accessible in the coming year?
A: Though 50 gauge films are available from a number of suppliers, including Mobil, most BOPP manufacturing and converting processes have better efficiencies when the film thickness is greater than 60 gauge. The interest in thinner materials has been primarily driven by needs to find better economics, but the decrease in cost is not that pronounced for the thinnest gauges that are available. In addition, there are performance trade-offs below 60 gauge, such as increased web handling difficulties and reduced stiffness and water vapor properties.
Dru Kefalos, business manager, Americas Mobil Chemical, Films Division
Q: What types of thinner polypropylene film grades are on the horizon?
A: Super Film has a 50 gauge transparent in its SUPLAIN (label) film and SUPEX (surface print and laminating) film. The company is conducting trials with 45 and 48 gauge transparent co-extrusions. Our B gauge system with Bruckner lines permits thinner gauges with great accuracy and minimal line changeover.
Ross Wooldridge, sales director, Super Film of America
Design Developments
Q: What developments in polyprop formulations could offer improved surface characteristics?
A: Engineering co-extruded skin polymers by chemistry, formulations and by blends continue to be the most potentially successful routes to improving the surface performance of OPP films so as to improve wetting and increase adhesion. One of the hottest topics in polyolefins is extending the application of metallocene chemistry from the successes in polyethylene to the engineering of polypropylene film resins. The potential toughness of a metallocene PP may increase the overall perceived adhesion by increasing the strength of the base film itself. The biggest challenge with metallocene resins for OPP films is that they must be extruded, stretched and oriented.
Leighton Derr, technical service manager, AET Films
Q: One of the biggest challenges converters face with polypropylene is achieving surface adherence in pouches or other multi-layer constructions. What approaches, such as coatings, offer improvements?
A: Often the weak point in triplex laminations for adhesion is the metal-to-film interface. Mobil's efforts are focused on designing films that have treated or high-energy skins that provide better metal adhesion on one side and a good surface for extrusion or adhesive lamination bonds on the other. Coated surfaces are sometimes used in lieu of metal primarily to provide transparency for the package, and may provide benefits with adhesive laminations, but not necessarily better metal adhesion.
By Susan Friedman
You asked, and polypropylene film material suppliers responded. After conducting a phone survey to collect pP readers' most-encountered challenges with this popular substrate, related questions were forwarded to suppliers for comment. Read on for their suggestions.
Available Grades
Q: Converters have expressed difficulty finding polypropylene below 60 gauge. Does 60 gauge meet most application needs, or will thinner gauges need to become more accessible in the coming year?
A: Though 50 gauge films are available from a number of suppliers, including Mobil, most BOPP manufacturing and converting processes have better efficiencies when the film thickness is greater than 60 gauge. The interest in thinner materials has been primarily driven by needs to find better economics, but the decrease in cost is not that pronounced for the thinnest gauges that are available. In addition, there are performance trade-offs below 60 gauge, such as increased web handling difficulties and reduced stiffness and water vapor properties.
Dru Kefalos, business manager, Americas Mobil Chemical, Films Division
Q: What types of thinner polypropylene film grades are on the horizon?
A: Super Film has a 50 gauge transparent in its SUPLAIN (label) film and SUPEX (surface print and laminating) film. The company is conducting trials with 45 and 48 gauge transparent co-extrusions. Our B gauge system with Bruckner lines permits thinner gauges with great accuracy and minimal line changeover.
Ross Wooldridge, sales director, Super Film of America
Design Developments
Q: What developments in polyprop formulations could offer improved surface characteristics?
A: Engineering co-extruded skin polymers by chemistry, formulations and by blends continue to be the most potentially successful routes to improving the surface performance of OPP films so as to improve wetting and increase adhesion. One of the hottest topics in polyolefins is extending the application of metallocene chemistry from the successes in polyethylene to the engineering of polypropylene film resins. The potential toughness of a metallocene PP may increase the overall perceived adhesion by increasing the strength of the base film itself. The biggest challenge with metallocene resins for OPP films is that they must be extruded, stretched and oriented.
Leighton Derr, technical service manager, AET Films
Q: One of the biggest challenges converters face with polypropylene is achieving surface adherence in pouches or other multi-layer constructions. What approaches, such as coatings, offer improvements?
A: Often the weak point in triplex laminations for adhesion is the metal-to-film interface. Mobil's efforts are focused on designing films that have treated or high-energy skins that provide better metal adhesion on one side and a good surface for extrusion or adhesive lamination bonds on the other. Coated surfaces are sometimes used in lieu of metal primarily to provide transparency for the package, and may provide benefits with adhesive laminations, but not necessarily better metal adhesion.
Companies Mentioned:
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