The technology of polypropylene BCF yarn is complex, and the technology research road is long

Polypropylene BCF yarn is first blended with 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 shrinks greatly and is located in the center of the yarn. , and the mixed low-shrinkage fibers, due to their small shrinkage, are extruded on the surface of the yarn to form a circle, thereby obtaining a fluffy, plump and elastic bulked yarn.

Grey fabrics woven from polypropylene BCF yarns are generally dyed and raised (single-sided or double-sided) after finishing. The fabrics are required to be soft, fluffy, elastic and dyed evenly. Therefore, the bulking degree of the bulking yarn, the specifications of the raw materials, and the mixing uniformity are its main performance indicators.

The bulking degree 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 bulking degree of the yarn is required to be above 22%. In actual production, the shrinkage of the yarn is generally used as the measured index to test the bulking degree, which is generally between 18% and 19.5%. Regarding the measurement of shrinkage, the following issues should be noted:

(1) The tension of 20g should be added before measuring the length of the original yarn; (2) Steam the measured raw material in steam for 5 minutes; (3) The bulked yarn after shrinkage should also be added with 20g of tension before measuring the length.

Too much bulk will lead to tight fabrics, poor fluffy softness, and no elasticity; too small bulk will lead to slackened gray fabrics and poor plush feel.

The mixing uniformity of the raw materials is an important factor affecting the dyeing effect. Uneven mixing will lead to uneven dyeing of the fabric and also affect the bulking performance.

The process of polypropylene BCF yarn is a little complicated, and the production cost is therefore higher than other finished yarns. It is hoped that the production technology can be greatly improved in the near future, which will open up the way for polypropylene BCF yarn.