Package yarn arranged in neat rows in a textile workshop
The moment cotton fabric enters the scouring bath the temperature climbs and the alkali liquor foams over, the foam rises to the lip and spills out, the fabric comes out carrying alkali marks, desizing is uneven and soaping is incomplete, and the levelness of the dyeing step that follows is affected in turn.
Chemi Tech makes defoamers for the scouring, desizing and soaping systems of cotton fabric, drawn from the defoamer KM-901 series. How a grade is matched also depends on the alkali concentration, the process temperature and the circulation method of the equipment. KM-901 is a modified polysiloxane system: it does not demulsify at high temperature and its suppression lasts, so even in a hot, alkaline setting like a scouring bath it performs steadily. Chemi Tech runs a round of foaming comparison against the alkali concentration and the process temperature first, so the defoamer recommended to you is the best fit.
Advantages of Chemi Tech Defoamers
Chemi Tech defoamer KM-901 series does not demulsify at high temperature: it still works in a scouring bath running close to boiling. It also resists strong acid and strong alkali without decomposing or losing effect, so the bath holds its performance. Suppression lasts as well, so one addition covers a whole batch of fabric without topping up as the run goes. Compatibility is good, too: it runs in one bath with the scouring agent and the wetting agent without fighting, and the bath throws no sediment and no floating oil. And there is no side effect on the fabric — no silicone marks left behind, and no effect on the dyeing step that follows.
A note from Chemi Tech: the behaviour above comes from a typical high temperature cotton scouring condition. If the alkali concentration or the process temperature changes, the results move; contact us first and we will run a dedicated test for you.
Industry Pain Points and Solutions
Foaming in the scouring bath looks like a matter of the bath surface, but the core problem is that it drags the fabric and the downstream processes down with it.
The first problem exposed is foam carrying alkali. The foam spills over the lip, alkali liquor drips onto the fabric, alkali marks are left after drying, and dyeing takes unevenly. Chemi Tech places the dosing point at the circulation pump inlet of the scouring bath, so the chemical spreads before the alkali liquor foams over.
What follows is that at higher temperature the other additives scatter. The scouring bath runs close to boiling, an ordinary defoamer demulsifies once added, and the foam turns more stubborn instead. Chemi Tech's approach is to select a high temperature resistant defoamer against the process temperature.
The last point is that topping up the auxiliaries cannot keep pace. The fabric passes through the machine quickly, the auxiliaries in the bath are carried off by the fabric, and the foam gradually piles up again. Chemi Tech's approach is to calibrate the make-up level against fabric weight and machine speed, and line the make-up rhythm up with the production schedule. Chemi Tech defoamers clear these troubles at the root — high temperature stability and suppression duration are the first task we verify.
Typical Conditions and Verification
Customer: a printing and dyeing enterprise in Jiangsu, applying it to the scouring and soaping stages for cotton fabric.
Once this plant raised the scouring bath temperature the foam could not be held down, it spilled over the lip, the fabric carried a good many alkali marks, and the rework rate at the dyeing step that followed was on the high side. The solution offered by Chemi Tech defoamer was: against the alkali concentration and the process temperature, a suitable grade was selected from the KM-901 series, the dosing point was set at the circulation pump inlet, and the make-up level was stepped against fabric weight and machine speed. After use the bath surface ran steady, the alkali marks on the fabric disappeared, and the levelness came back into the normal range. Rework and lost time, and the waste of material, are ruled out.
Frequently Asked Questions
Will the defoamer fail first itself in hot alkali liquor?
There are cases where it does: some chemistry cannot take high temperature and high alkali, demulsifies on entry, and the foam gets worse instead. The KM-901 Chemi Tech supplies to printing and dyeing plants has been compared for stability and suppression duration against the actual scouring bath temperature and alkali concentration, and it only passes onto the machine when both items are through. Chemi Tech will supply the product that fits on the basis of alkali concentration and process temperature, solving the problem at the root for the enterprise and delivering cost reduction with efficiency gains.