Softeners

A softener leaves a thin lubricating film on the fibre surface so the fibres slide over one another more easily. The handle of the cloth changes because that friction drops. The Derin Kimya softener range covers nine products: nonionic and cationic liquids, perfumed grades, and flake forms dissolved in the mill.

How does a softener change the handle?

Whether a cloth feels harsh or soft depends on how easily its fibres move past each other under the hand. A softener molecule anchors on the fibre surface with its fatty chain pointing outwards, and friction at the contact points falls. The fibres slip more freely, so the fabric reads as fuller and more fluid.

Choosing a softener is therefore less a question of how much and more a question of which handle. At the same dosage a cationic quat gives a full, warm handle, while a nonionic ester leaves the cloth drier and closer to its natural feel.

Cationic or nonionic?

Cationic softeners carry a positive charge. Cotton and viscose sit negatively charged in the bath, so these molecules deposit onto the fibre by themselves in exhaust; the liquor usually runs clear and utilisation is high. In return they carry two well-known risks: yellowing under stenter heat, and a shift in the shade of the dyeing.

A nonionic softener has no charge. It does not deposit onto the fibre, so exhaust yield is low and its proper place is the pad-stenter line. On the other hand it will not precipitate in baths holding anionic optical brightener, anionic softener or residual dye. That is why the choice moves to the nonionic side on whites and optically brightened lots.

Why buy a softener as flakes?

A flake grade is the same active without the water. Most of a drum of liquid softener is water; in flake form the mill adds that water from its own line, and freight and storage load drop accordingly.

The price is the dissolving step. Flakes are not thrown straight into the liquor. They are dissolved in a separate vessel under agitation and fed once a clear dispersion has formed. Half-dissolved flake shows on the cloth as an oil-like stain.

When is a hydrophilic softener needed?

The film left by a conventional softener repels water. On towelling, bathrobes, sportswear and underwear, absorbency is a technical requirement, so hydrophilic grades that keep the cloth wettable are used instead. DK HYDROSOFT 12 S is the cationic product formulated for this.

The drop test is the practical control: place a drop of water on the finished cloth and time how long it takes to sink in. The acceptance limit follows the customer specification.

Application and dosage

In exhaust the softener normally goes in after the final rinse, into a warm bath at a set pH. On the padder there is one pass, and the outcome is fixed by liquor concentration and the pick-up of the mangle. The same recipe can give a different handle on two different padders, so the recipe is re-validated when the machine changes.

Dosage, pH and temperature for Derin Kimya products are given on each product page: pending from the client.

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