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Do you know your MDOPE from your BOPE?
There are many popular acronyms that we are all familiar with for example ASAP, FYI, AWOL and OMG and more recently with the increase in social media MIRL, NAGI and YGM.
The packaging world really loves an acronym; PET, BOPP, EVOH being just a few examples! Now due to our search for sustainability, we have even more.
So, what is OPE?
Well, it’s oriented polyethylene.
‘OPE’ films have been developed from the desire to create more sustainable flexible packaging constructions by replacing the outer carrier layer, for example polyester (PET), with a recyclable PE layer, creating a mono PE structure. This can be recycled with soft plastics in store.
The two films do a similar job, but MDOPE is vertically extruded at converters and BOPE is horizontally extruded at BOPP film manufacturers. They both can be used as a single web or as part of a laminate structure.
Let’s add some more letters!
Vertically blown PE (MDO)
MDO – machine direction orientation.
The film is blown vertically into a bubble similar to standard PE. After the ‘bubble’ stage of production there is a series of rollers which stretch the film in the machine direction. There is no additional stretch in the transverse direction.
These tend to have 5 or 7 layers of extrusion which can allow for additional barrier and are installed at converters. In food and consumer packaging, MDOPE can be used for a number of products, from pouches and bags, to packing snacks and confectionery.
Horizontally extruded PE (BO)
BO – biaxially orientated (machine and transverse directions)
This film is extruded on a stenter line similar to BOPP and is biaxially stretched in both machine and transverse directions.
New grades of PE giving heat resistance and stiffness have allowed the film to be extruded on a tenter frame. BOPP film manufacturers are installing hybrid BOPE/BOPP lines to go down this route as it provides a lot of manufacturing flexibility, and they are used to making BOPP films of a similar gauge.
Stay with us…… (there are benefits!) - Uses less polymer, better clarity and optics, improved barrier.
MDOPE
- Offers downgauging possibilities
- Can have EVOH added for enhanced oxygen barrier
- Has greater tensile strength in the machine direction
- Excellent bag converting performance
- Is particularly suited for gravure print
- Has better stiffness in machine direction
- Tears better in machine direction
- Offers higher resilience
BOPE
- Is softer
- Has good easy tear in both directions
- Has a higher puncture resistance
An MDO line is considerably cheaper than a BO line and the footprint is much smaller, but the BO lines can produce up to 4 times the amount of film.
Most PE resins can run through an MDO, but BO lines require specialised resins, however this is changing. The specialised resins are more expensive. There are benefits to both films and the end use should be a major driver in which to select.
We would like to talk to you about any projects you may have. If you would like to know more about acronyms in packaging, or the technical aspects of film and printing, please ask us about our Technical Training Workshops.
Originally designed as in-house training for our people, our Technical Training workshops are now available to you, your team, and anyone who feels they may benefit from the service.
So, as they say – “every day is a school day” (or EDIASD!), don't risk having FOMO, book your FREE place today
