Can't tell the difference between viscose, modal and lyocell?

01 Ordinary viscose fiber

Viscose fiber is the full name of viscose fiber. It is a cellulose fiber obtained by extracting and remodeling fiber molecules from natural wood cellulose using "wood" as a raw material.

Preparation

The plant cellulose is alkalized to form alkali cellulose, and then reacted with carbon disulfide to form cellulose xanthate. The viscous solution obtained by dissolving it in dilute lye is called viscose. The viscose is wet-spun and a series of Viscose fibers are formed after the treatment process.

The inhomogeneity of the complex molding process of ordinary viscose fibers will make the cross-section of conventional viscose fibers be waist-circular or irregular, with holes inside and irregular grooves in the longitudinal direction. Viscose has excellent hygroscopicity and easy dyeing, but its modulus and strength are low, especially low wet strength.

02 Modal fiber

Modal fiber is the trade name of high wet modulus viscose fiber. The difference between it and ordinary viscose fiber is that modal fiber improves the shortcomings of low strength and low modulus of ordinary viscose fiber in the wet state. It also has high strength and modulus in the state, so it is often called high wet modulus viscose fiber.

Similar products of different fiber manufacturers also have different names, such as Lenzing ModalTM fiber (Lenzing ModalTM), glass Nosic fiber (Polynosic), strong fiber, tiger kapok and Newal (Newal) and other product names. .

Preparation

The achievement of high wet modulus properties is conferred by the special craftsmanship of the production process. The difference from the general viscose fiber production process is:

(1) Cellulose should have a high average degree of polymerization (about 450).

(2) The spinning dope prepared has a higher concentration.

(3) The appropriate composition of the coagulation bath is prepared (for example, the content of zinc sulfate is increased), and the temperature of the coagulation bath is lowered to delay the molding speed, which is beneficial to obtain fibers with dense structure and high crystallinity. The inner and outer layer structures of the fibers thus obtained are relatively uniform, the skin-core layer structure of the fiber cross-section is not as obvious as that of ordinary viscose fibers, the cross-sectional shape tends to be round or waist-round, and the longitudinal surface is also smoother. It has high strength and modulus, and excellent moisture absorption properties are also suitable for underwear.

The structure of the inner and outer layers of the fiber is relatively uniform, and the skin-core structure of the fiber cross-section is not as obvious as that of ordinary viscose fibers. Excellent.

03Lyocell fiber

Lyocell fiber is a kind of man-made cellulose fiber, which is made of natural cellulose polymer. It was invented by the British Courtauer Company and later produced by the Swiss Lenzing Company. Its trade name is Tencel.

Preparation

Lyocell uses N-methyl morpholino (NMMO) aqueous solution as a solvent, which can directly dissolve cellulose pulp to obtain a spinning solution, and then use wet spinning or dry-wet spinning method to a certain concentration. The NMMO-H2O solution is a new type of cellulose fiber obtained by coagulating the fiber in a coagulation bath, and then drawing, washing, oiling and drying the spun primary fiber.

Compared with the conventional viscose fiber production method, the biggest advantage of this spinning method is that NMMO can directly dissolve cellulose pulp, the production process of spinning dope can be greatly simplified, and the recovery rate of NMMO can reach more than 99%. The production process hardly pollutes the environment.

The morphological structure of lyocell fiber is completely different from that of ordinary viscose. The cross-sectional structure is uniform and round, and there is no skin-core layer. The longitudinal surface is smooth without grooves. It has better mechanical properties than viscose fiber, good washing Dimensional stability (shrinkage rate is only 2%), with high hygroscopicity. Beautiful luster, soft touch, good drapability and good flow.