Warp yarns spread layer upon layer on a loom
Finish a polyester fabric for water repellency and the spray rating passes straight off the line, then it fails after a few washes, the handle goes stiff at the same time, the downstream laminating will not hold, two lots are returned by the customer, and the whole batch can only be downgraded.
Chemi Tech makes water repellent finishing agents for chemical fibre fabrics such as polyester and nylon and for industrial textiles, drawn from the water repellent agent KMF-801 series. How a grade is matched depends on the fibre composition, the fabric construction and whether the test protocol the customer asks for is spray rating or hydrostatic head. KMF-801 is built in the direction of continuous repellency with handle kept in balance: film formation across the fibre surface is continuous, and it is not easily lost after washing. If the fluorine content also has to be controlled, the fluorine-free KMWF-01 series is the better match.
Advantages of Chemi Tech Water Repellent Agents
Chemi Tech water repellent agent KMF-801 series forms a continuous film on the fibre surface rather than relying on a layer floating on top, so it is not easily lost after washing. Its compatibility with the common binders and softeners is good as well, so a one-bath run does not fight and the bath throws no sediment, which saves the previous bath from being wasted. The handle is soft, too: the finished fabric does not go stiff or harsh, and the downstream laminating step does not need its parameters changed. Hydrostatic head keeps pace as well, with the spray rating and the hydrostatic head both falling inside the customer's thresholds. It contains no perfluorinated compounds.
Industry Pain Points and Solutions
With water repellency on chemical fibre fabric, the hardest part is holding repellency without dragging the downstream processes with it — but if the base is not solved, the later processes are bound to run into trouble.
Checking only spray rating and leaving hydrostatic head out of the protocol is where the basic mistake most often sits. The sample is fine on the day of sampling, then becomes a finished garment and leaks the moment hydrostatic head is applied. Chemi Tech therefore validates the finishing agent against each test standard in turn, with spray rating and hydrostatic head compared side by side.
The difficulty that follows is the handle collapsing. Repellency goes on, the fabric goes stiff and harsh, and the downstream laminating will not hold. Chemi Tech's approach is to put handle and repellency into one comparison table and verify the boundary at both ends together.
The last problem is the water repellent agent not being compatible with the binder in one bath. It is also incompatible with the adhesive at the next process step, the bath throws sediment, and the fabric carries defect marks. Chemi Tech's approach is to run a one-bath validation of the water repellent agent with each of the common binders, and find the critical problem. Chemi Tech water repellent agents clear these troubles at the root — one-bath compatibility and wash data are the first task we verify.
Typical Conditions and Verification
Customer: a chemical fibre fabric enterprise in Fujian, applying it to the water repellent finishing and downstream laminating of polyester fabric.
The fabric from this plant took the repellent finish and passed the spray rating, then failed after a few washes, and the downstream laminating would not hold either, so two lots were returned by the customer. The solution offered by Chemi Tech water repellent agent was: after comparing the fibre composition and the test protocol, a suitable grade was selected from the KMF-801 series for the customer, and the finishing process was recalibrated together with the curing conditions. After switching to the newer grade from Chemi Tech, the spray rating and the hydrostatic head both passed in one run, the handle held, and the downstream laminating stopped giving trouble.
Frequently Asked Questions
For water repellency on polyester, must the water repellent agent be switched to fluorine-free?
Not necessarily — in most cases a fluorinated system passes; what matters is whether the one-bath compatibility with the binder can hold up. The KMF-801 Chemi Tech supplies to chemical fibre plants has been compared along the fluorinated route against the test protocol; if it is an export order that has to clear fluorine-free testing, then KMWF-01 is the better fit. Which grade to use is decided by Chemi Tech on the basis of testing your incoming sample, after which a customised formulation is given.