Anionic Wetting Agents
Anionic wetting agents take their solubility from a charged group, carry no cloud point limit and stay soluble in caustic liquor. They are the wetting agents of the bleaching and alkaline desizing baths. Three products in Derin Kimya's anionic family.
Why does an anionic wetting agent work in caustic?
The water solubility of an anionic surfactant comes from the negatively charged group in its structure. That group is far less affected by temperature and alkali than the ethoxylate chain of a nonionic, so the product has no cloud point limit and stays in solution in a caustic bath.
Bleaching and alkaline desizing liquors are therefore the natural home of anionic wetting agents. Wetting speed is usually high as well: anionic structures pull the surface tension of water down quickly, which is what counts on continuous ranges where contact time is short.
Why is hard water a problem?
The anionic group can form insoluble salts with the calcium and magnesium in the water. The resulting precipitate does damage in two directions: it pulls the active part of the wetting agent out of the bath, and it leaves a deposit on the cloth.
The answer is not a different product but prepared water. Adding a sequestering agent to the bath is the condition under which this family works reliably in a hard-water mill. Where the water is hard and no sequestering agent is in the recipe, the performance of an anionic wetting agent varies batch by batch, and the blame usually lands on the product.
Where does foam set the limit?
Anionic structures foam more readily than nonionics. In a pad trough or a continuous saturator that is rarely a problem; in jets and overflow machines it can reach the level that disturbs liquor circulation.
The decision follows the machine. On a continuous range the speed of an anionic wetting agent is what matters; in exhaust work, either a low-foaming type is chosen or an antifoam goes into the recipe. Once an antifoam is added, its effect on wetting power has to be confirmed in the lab: pending from the client.
Which type for which process?
On a continuous pre-treatment range the contact time in the saturator is measured in seconds, and there wetting speed comes ahead of every other criterion. On a jigger or in exhaust work the time is long, so alkali stability and low foam matter more than speed.
At the pre-wash and desizing steps the wetting agent is also expected to do some washing, holding spin finish and dissolved size in the liquor. Those three different needs map to different products inside the same family.
Why will it not mix with cationics?
Bring an anionic wetting agent together with a cationic softener or fixing agent in one bath and they precipitate ionically. The result is neither wetting nor softness: an oily mark on the cloth and residue in the machine.
In practice that means the rinse after pre-treatment has to be done properly. Anionic wetting agent left on the cloth produces the same outcome when it meets the cationic product in the finishing bath.
Product comparison
Comparison
| Product | Description | Alkali stability | Working pH range | Temperature | Dosage |
|---|---|---|---|---|---|
| DK WET 1037 A | Anionic wetting agent | awaiting data | awaiting data | awaiting data | awaiting data |
| DK WET RPD | Anionic wetting agent | awaiting data | awaiting data | awaiting data | awaiting data |
| DK WET RPD K | Anionic wetting agent | awaiting data | awaiting data | awaiting data | awaiting data |
Products
- DK WET 1037 A
Anionic wetting agent that stays soluble in caustic bleaching and alkaline desizing liquors, with no cloud point.
- DK WET RPD
Fast-wetting anionic surfactant chosen for continuous pre-treatment ranges where contact time is short.
- DK WET RPD K
Anionic wetting agent with high alkali stability, staying soluble where pre-treatment recipes raise caustic levels.
Common questions
Can an anionic wetting agent be used in mercerising?
Alkali stability is high, but the caustic concentration in mercerising is a different order. That application takes a mercerising wetting agent formulated against the electrolyte load.
Why does wetting power vary from batch to batch?
Water hardness is the most common reason. Source water hardness moves with the season and with the well, so the same recipe gives different results when the sequestering dosage is held fixed. Analyse the water and set the sequestering dosage against it.
Can anionic and nonionic wetting agents be used together?
They can; the two do not clash ionically, and blends bring together the strengths of both families. Ready-made products built on that logic are grouped under nonionic-anionic wetting agents.
Other families in this category
Related applications
Guides on these products
Not finding what you need?
We develop custom formulations. Tell us your process, machine type and the result you are after, and the lab will set up a trial and send a sample.