During the impregnation process, cellulose is combined with NaOH, and even sodium alkoxide is formed, which will swell and reduce the degree of polymerization. The concentration of lye solution is 18%-20%, the immersion time is 45-60 minutes, and the temperature is about 20℃. Pressing and crushing take place in a combined machine. Pressing is to remove excess lye to promote the bamboo yarn yellowing reaction. It's going well because too much lye will consume CS2 and there will be various side effects. Pulverization is the process of extruding very dense alkali cellulose into fine and loose chips and then pulverizing, increasing the surface area and facilitating each step of the subsequent reaction to proceed more uniformly.

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The Old Town takes place in an old box, an enclosed workshop with heating, conveyor belts, etc. The old achievement is to use the oxidation of air to break the molecular chain of alkali cellulose, reduce the degree of polymerization and reduce the viscosity. The key to aging is to control the temperature and time of aging. Generally, low temperature is used instead of high temperature for a long time, because the temperature is too high, and the cracking is violent. It is easy to make the polymerization reaction too low, and the molecular weight distribution is not uniform. Yellowing is the reaction of alkali cellulose and CS2 to form sodium cellulose yellow, which can be dissolved in NaOH solution to form spinning solution. The yellowing reaction is mainly a gas-solid phase reaction, and the reaction process includes the process of CS2 vapor permeating from the surface of the alkali cellulose to the interior according to the diffusion mechanism, and the process of the permeated part of the CS2 reacting with the alkali cellulose.

Hydroxyl groups on alkali cellulose. The yellowing reaction is a reversible reaction, which mainly depends on the concentration of caustic soda and carbon disulfide. The dissolving process of cellulose xanthate is carried out in a dissolving tank with stirring. A large amount of dispersed cellulose xanthate is gradually pulverized into fine particles after continuous stirring and circular grinding. After dissolving, in order to minimize the quality difference between viscose batches, it is necessary to mix the dissolved viscose batches to make the viscose uniform and easy to spin. The series of chemical and physicochemical changes that take place during the placement of the viscose is called the curing of the viscose.

The maturity of the viscose refers to the stability of the viscose to the setting effect. It is generally expressed by the degree of stability of the viscose in NH4Cl solution. Maturity is one of the important indicators of viscose, which directly affects the performance of the finished fiber in the spinning and forming process. At the beginning of curing, the viscosity drops sharply, and as the curing progresses, the viscosity starts to rise again, and even viscose particles are formed. Filtration is the removal of particles from the viscose solution, preventing the spinneret holes from clogging the spinneret during spinning, causing filament breakage, or forming a weak link in the finished fiber structure, i.e. a reduction in fiber strength. Usually through three filtration, the filter media is flannel and muslin.