A mill in Southeast Asia making food packaging paper and tissue came to us with a recurring headache: their food wrapping and fruit bags went soft in damp weather, and their tissue fell apart once wet. They had tried wet strength agents before, but ran into trouble on the machine. Below is the key technical consultation.
When Water Wins
Q: Our food packaging and fruit bags go soft in damp conditions, and the tissue falls apart when wet. Why can't we hold strength through water?
A: Ordinary paper holds together through hydrogen bonds between fibers, and water loosens those bonds - the sheet simply loses its grip. A wet strength agent builds a water-insoluble crosslinked network between fibers so the sheet keeps its strength even soaked. The catch is that many products either fight the rest of your wet-end chemistry or disrupt machine runnability, so mills either can't reach the target or create new problems trying.
Why FU-02
Q: Why do you recommend FU-02 for us?
A: FU-02 is a strongly cationic wet strength resin. Its positive charge anchors it onto the negatively charged fibers, and it forms stable crosslinks between them. It is readily absorbed by fiber, compatible with the rest of the furnish, and does not disturb the wire section or conflict with other additives. It suits tissue, packaging, and specialty grades, and is non-toxic and non-irritating.
How to Use It
Q: What should we watch for in application?
A: Dilute it 3 to 5 times with clean cold water before use, keep the diluted concentration around 2.5%–4%, stir evenly, and use it promptly - don't let the diluted stock sit. Dosage is set against oven-dried pulp, and we tune the point of addition to your machine so it takes effect where the sheet needs it.
Beyond Wet Strength
Q: Does it do anything beyond keeping the sheet strong when wet?
A: Yes. Beyond wet strength, it raises dry strength and helps drainage and machine speed, while improving retention of fillers, sizes, and fine fibers. It also works as a retention aid for rosin and fortified rosin sizes, an enhancer for neutral sizing, and a modifier for cationic starch - so it stabilizes the sheet overall. Compatibility is good and it does not reduce finished-paper brightness. We can also supply different solid-content grades and a low-chlorine eco-friendly variant on request.
If your mill struggles with strength loss in damp or wet service, our technical team can map an FU-02 dosing plan to your specific grades and machine.
