What is the difference between the initial adhesion and holding adhesion of hot melt adhesive particles? Comparison and evaluation of book and seal selection

One sentence distinction:Initial adhesion refers to whether one can grasp it at the moment of attachment, while holding adhesion refers to whether it can be firmly held for several months.The adhesive packaging of books and magazines places more emphasis on adhesion, while high-speed sealing places more emphasis on initial adhesion. The two often have a trade-off in formula, so when selecting, it is necessary to first clarify the process rhythm.

Comparison of two indicators

Why do many factories prioritize one over the other

Packaging factories pursue production line speed and tend to choose models with short opening times and extremely high initial adhesion. As a result, in winter, the adhesive layer becomes brittle, and cardboard boxes are opened in batches during the cold chain; On the contrary, book and magazine factories chose glue with high cohesive strength but long opening time to make the spine resistant to folding. As a result, the high-speed glue binding machine entered the next workstation before the book pages were fully formed, resulting in loose pages. This is not because the glue is not good, but because the indicators do not match the rhythm.

How to choose according to the scene

• High speed sealing line (more than 20 boxes per minute)Priority is given to high initial adhesion and short opening time models, and the compression device stroke can be shortened.
• Wireless adhesive packaging for books and periodicalsPriority should be given to adhesion and flexibility, with a stable opening time of 8-12 seconds, and combined with a dual station of back glue and side glue.
• Quick printing of images and text in small batchesChoose a universal balanced type that takes into account the fault tolerance time for manual operation.
• Cold chain/export partsUsing low-temperature adhesion as the hard indicator, it is necessary to conduct drop verification after freezing at -18 ℃ for 24 hours.

Sunlife’s approach: Write two indicators into the supply parameters

Sunlife Commercial Supply of Guangzhou Sunlifehot melt adhesiveThe factory report will simultaneously indicate four items: softening point, melt viscosity, opening time, and curing time. Customers can infer the bias between initial adhesion and holding adhesion based on this. For production lines with special rhythms, we recommend running a full shift of 25kg trial packs, verifying with real paper and real workshop temperature, and then determining the annual model.

Frequently Asked Questions

Q: Is it better to have a higher initial adhesion force?
Answer: No. Excessive initial adhesion is often accompanied by a short opening time, and manual operation or long glue line equipment is more likely to break the glue.

Q: How to easily determine whether the adhesive strength is sufficient?
Answer: After placing the finished product for a week, manually tear it open. If the paper fibers are torn, it indicates that the adhesion is stronger than the paper itself, which is a qualified state.