Some common problems on TPU elastic tape

TPU tape is a kind of invisible clear elastic, which is usually used for sewing at shoulder part of knitting clothes. TPU tape is produced by extrusion technology. A piece of high quality TPU tape should be clear enough, smooth, good stretchy and no spots on surface. Although TPU tape isn’t the complex product, during the producing process, there are some common problems on TPU tape.

1. Black spots

Some bad TPU tape has some black spots on surface. It is refers to two main reasons. The one is impurity of raw material. If the TPU raw material has impurities itself, the impurities will must absorb on final TPU tape. Of course, there still a situation that TPU raw material is contaminated before melting in machine. For example, we can’t promise that nothing dropped into material container by accident. If a small scrap of paper or some small grain of sand dropped in it, the paper or sand will become black spots on TPU elastic tape after high temperature manufacturing. Therefore, confirming the purity of raw material is important.

The other reason leads to black spots is about machine cleaning. If the machine haven’t been cleaned for a long time, the head of machine, the high temperature part, would be heaped up lots of remanent material. Finally, the remanent material would be carbonized after staying in high temperature space for long time. So the regular cleaning of machine is also important. We have another article to explain those about black spots detailedly.

2. Unmelted spots

Unmelted spots on TPU tape is shown as white spots. Refers to the feature of TPU, it can show its best physical property after high temperature shaping. So before shaped into a piece of tape,  TPU raw material should be melted totally under high temperature of 180 degree. Otherwise, hard white spots will appear on tape.

3. Bubble

Some bad quality TPU elastic tape has bubbles on it. It is not easy to find out when TPU tape just produced. But once the tape with bubbles being sewed, the bubbles will become magnifying holes until the tape break. The appearance of bubbles is the result of moisture. TPU is a kind of eco-friendly material, which is easy to absorb moisture in the air and finally decomposed. If the TPU material isn’t be dried enough, bubbles will occur on TPU tape. So TPU material must be fully dried before manufacturing.

All these three problems above will result in breaking of tape. So manufactures will try to avoid those problems. However, TPU tape with good raw material and good technology will own better quality of course. For example, the performance of skin-friendly, eco-friendly, anti-aging, anti-yellowing, resilience, etc.