Key points
- Start from the end use, not from the price list
- Match thickness to the seal window of your machinery
- Specify surface treatment explicitly, in the unit you mean
- Confirm core and roll geometry before you commit
Choosing a BOPP film is usually presented as a price comparison, but the specification that matters is the one your line can actually run. Two films of the same nominal thickness can behave completely differently once they reach a sealing jaw, a print head or a slitter. A structured shortlist saves far more time than a discount negotiation.
Start from the end use
Write down what the finished pack has to do before you look at any datasheet. Does it need to hold a 500 g bag of coffee on a shelf for six months, or carry a sachet of detergent through a wet supply chain? Barrier requirements, seal window, print substrate and reuse expectations all follow from that description. A clear end-use statement also makes it much easier for a supplier to propose a sensible grade rather than pushing their fastest-moving stock.
Thickness and the sealing window
Nominal thickness is the first number buyers look at, but the useful range is wider. A 30 micron film with a broad sealing window is usually a better production choice than a 25 micron film that needs a narrow temperature band. If your line runs wide-format sealing jaws or high-speed vertical form-fill-seal equipment, ask the supplier for a recommended sealing temperature and dwell time for the exact grade, and check that those numbers fall inside your machine's published window.
Copolymer versus homopolymer
Homopolymer BOPP is stiffer, clearer and more dimensionally stable, which makes it a good choice for label stock and for packs that need puncture resistance. Copolymer BOPP has a lower softening point and a wider heat-seal window, which is why it dominates flexible snack and pouch applications. If the pack will be cold-filled, retorted or vacuum-packed, tell the supplier, because that changes the recommended copolymer level.
Surface treatment, stated properly
Corona treatment improves ink wetting and adhesion, but treatment decays with time and heat. 'Treated' on its own is not a specification. State the treatment level in dynes per centimetre, state which side is treated, and confirm the maximum time between treatment and conversion. An untreated or under-treated surface is one of the most common causes of print adhesion failure and delamination, and it is entirely avoidable.
Core size and roll geometry
Core diameter and roll length decide whether the reel fits your line without a rebuild. A 3-inch core usually suits faster, heavier jobs; a 6-inch core suits lighter web tension. Also check the maximum roll diameter your unwind can accept, because a roll that is too wide for the machine will be rejected on arrival.
Build a specification you can hold us to
A good film specification is short, measurable and unambiguous: nominal thickness with tolerance, grade, treatment side and level, seal window, haze and gloss if appearance is critical, core size, roll length and maximum diameter. Add the packaging requirement - individual wrapping, kraft cores, or a specific labelling format. When a supplier quotes against that document, you are comparing like with like instead of comparing adjectives.
At Asia Pacific Industry Group we publish thickness tolerances and seal windows for every grade we make, and our technical team is available to review your specification before you place a trial order. Sample reels can be dispatched for line trials so you validate the material on your own equipment rather than on a datasheet.
Request samples or a quotation
Tell us the grade, thickness and quantity you need and our team will reply with a specification and lead time.