Polypropylene BCF yarn is first blended by two fibers with different shrinkage rates into yarn, and then the yarn is treated in steam or hot air or boiling water. At this time, the fiber with high shrinkage rate will shrink and it is located in the center of the yarn , And the mixed low-shrinkage fiber, due to the small shrinkage, is squeezed on the surface of the yarn to form a loop shape, thereby obtaining a bulky, plump, and elastic bulky yarn.
Polypropylene BCF yarnuse: It is mainly used for the weaving of carpets, car mats, door and window tops, blankets, cushions, edging, fabrics, curtain tapes, weaving, etc. It can also be widely used in various decorative materials.
Grey fabrics woven with polypropylene BCF yarns are generally dyed and napped (single-sided or double-sided) after finishing. The fabrics require soft, fluffy, elastic and uniform dyeing. Therefore, the bulkiness of the bulked yarn, the specifications of raw materials, and the uniformity of mixing are the main performance indicators.
Bulkiness is the degree of expansion of the original yarn after wet heat treatment. It is the main factor that determines the bulkiness, softness and elasticity of the fabric. Generally, the bulkiness of the yarn is required to be above 22%. In actual production, the shrinkage of the yarn is generally used as the actual measurement index for checking the bulkiness, which is generally between 18% and 19.5%. Concerning the measurement of shrinkage, the following issues should be noted:
⑴Before measuring the length of the original yarn, a tension of 20g should be pre-applied; ⑵The measured raw material should be steamed in steam for 5 minutes; ⑶The length of the bulked yarn after shrinkage should be measured after adding 20g of tension.
Too much bulking will result in tight grey fabrics, poor fluffy softness, and inelasticity; too little bulking will result in loose grey fabrics and poor plush feel.
The uniformity of the mixing of raw materials is an important factor affecting the dyeing effect. The uneven mixing will cause uneven dyeing of the piece and also affect the bulking performance.
The technology of polypropylene BCF yarn is a bit complicated, and the production cost is therefore higher than that of other finished yarns. It is hoped that the production technology can be greatly improved in the near future to open the way for polypropylene BCF yarn.