BOPP (Biaxially Oriented Polypropylene) packing tape is essential for corporate packaging and daily life. However, many consumers still judge tape quality based on "low price" and "hand-feel stickiness," which often leads to purchasing inferior products and compromising packaging safety.
1. Misconception: Is Stickier Always Better?
It's a common misconception that "the stickier it feels, the better the tape." There are two core standards for evaluating tape quality, and they are often inversely related:
- Initial Tack: The adhesive force the moment the tape touches an object (this is what feels "sticky" to the hand).
- Holding Power: The ability of the tape to remain adhered under stress for a long time without falling off.
Inferior tapes often increase the glue coating (with impurities) to boost Initial Tack, making them feel very sticky. However, their cohesion is poor, and they will pop open or detach over time. High-quality tapes strike a perfect balance between the two.
2. Glue Thickness and Standards
Generally, we can determine the usage by the thickness of the glue coating:
- Stationery/Bundling Tape: Glue thickness is usually around 20 microns, with Initial Tack below No. 10 (rolling ball method), suitable for light loads.
- Standard Packing Tape: Glue thickness should be between 22-28 microns, with Initial Tack between No. 15-20. Only this thickness guarantees sufficient Holding Power to ensure boxes don't pop open during transport.
3. Visual Identification: Beware of "Egg Yolk Yellow" & "Pale Green"
To cut costs, many inferior tapes on the market add large amounts of impurities to the glue. To increase thickness and mask these impurities, manufacturers add color powder to the glue.
Therefore, if transparent tape appears egg yolk yellow or pale green, this is usually a sign of inferior quality. High-quality BOPP tape should have high purity and transparency in both the base film and glue, with a neat roll and no obvious color cast.
4. Hands-on Test: The Stretch Method
For colored tapes (like yellow or tan), how to distinguish quality? We can use the "Stretch Method":
Procedure: Pinch the adhesive side tight and pull it apart quickly.
- Observe the Base Film: After pulling part of the glue layer off, observe the exposed base film. High-quality tape has high purity and good transparency.
- Observe Glue State: If the glue stretches into strings or pulls off in spots (uneven coverage), it indicates large amounts of impurities and extremely poor cohesion.
- Observe Moisture: If the tape's stickiness drops significantly, it may be due to excessive moisture in the glue that has evaporated.