Yarn and machinery in chemical fibre production
Spin finish oil for chemical fibre is heated in the circulation tank and sheared by the circulation pump, and air is folded in with it; the foam rises over the tank surface and is entrained in the finish, attaches to the spinning head, and spinning breaks and oil spots increase with it.
Chemi Tech supplies defoamers for chemical fibre spin finish systems, drawn from the defoamer KM-830 series; the ratio is set by the finish type, the circulation temperature and the circulation ratio. The KM-830 series is designed around heat resistance and no oil carry-over, the defoaming action is stable under conditions where the finish is heated and circulated, and it does not easily leave oil spots on the fibre; the KM-880 in the same series is likewise heat resistant with no oil carry-over, and fits finish systems with high-ratio circulation better. Chemi Tech completes heat resistance and attachment comparisons against finish temperature and circulation ratio, and sets the model that fits for the customer accordingly.
Advantages of Chemi Tech Defoamers
Chemi Tech defoamer KM-830 series is heat resistant with no oil carry-over, and the defoaming action does not decay when the finish is heated and circulated; at the same time the foam-breaking speed is high and the foam falls back within a short time after it rises; in addition it is compatible with the finish system, does not separate out and does not turn cloudy, and no oil spots remain on the fibre surface; moreover, it does not interfere with the spinning and drawing processes, and breaks and oil spots fall with it.
Industry Pain Points and Solutions
Foam in chemical fibre spin finish is mostly not a matter of insufficient dosage, but air repeatedly carried into the finish by circulation temperature and shear; the consequence is an oil-fouled spinning head and more breaks.
The first problem to surface lies in foam rising under high-temperature circulation. Once the finish is heated its viscosity falls, air is folded in more easily, the foam rises over the tank surface, and the agent is entrained and attaches to the spinning head. Chemi Tech's answer is to add the heat-resistant KM-830 at the return port of the circulation tank, so that the agent is dispersed before the foam accumulates.
Next comes oil spotting on the fibre surface. If the defoamer is not sufficiently compatible with the finish, the matter that separates out after foam breaking attaches to the fibre and forms oil spots after drying. KM-880 from Chemi Tech has no oil carry-over and is compatible with the finish system, and no oil spots remain on the fibre surface.
There is one more point in high-ratio circulation systems. The higher the circulation ratio, the more violent the air entrainment and the faster the foam regenerates, and ordinary defoamers struggle to hold it. Chemi Tech runs a durability comparison according to circulation ratio, and calibrates the dosage of the KM-830 series together with the top-up point, so that the finish level stays stable.
Typical Operating Conditions and Verification
Customer: a chemical fibre spin finish manufacturer in Jiangsu, for circulation defoaming of polyester spinning finish.
After the plant's finish was circulated and heated, foam rose out, oil fouling of the spinning head led to more breaks, and the finished fibre carried too many oil spots. The solution Chemi Tech defoamer gave for the situation was: taking the finish type and circulation temperature into account, choose the KM-830 series, set the dosing point at the return port of the circulation tank, and grade the dosage by circulation ratio. After the solution was in place, the finish level stayed steady, oil spots on the spinning head dropped noticeably, and the break rate returned to the normal range.
Frequently Asked Questions
Will adding a defoamer to chemical fibre spin finish affect the evenness of finish application and fibre quality?
Not entirely without effect, since with a small number of categories the matter that separates out after foam breaking attaches to the fibre and forms oil spots. For chemical fibre spin finish systems, Chemi Tech has completed heat resistance and attachment comparisons with the KM-830 series, and at normal dosage the finish applies evenly with no oil spots left on the fibre surface. The dosage depends on the finish type and the circulation temperature, and Chemi Tech gives its fitted recommendation after the comparison.