11941 Scouring Powder

Features & Benefits

1. Contains no APEO or phosphorus, etc. Fits environmental protection requirements.
2. Excellent effect of extraction, bleaching, washing and dispersing for greasy dirt and impurities.
3. Imparts fabrics excellent capillary effect, high whiteness, bright color shade and strong strength.
4. Suitable for scouring, bleaching and whitening one bath process. Greatly simplifies traditional process. Reduces deoxygenization, neutralization and water washing process. Saves energy and reduces pollution.

Typical Properties

Package

50kg cardboard drum & customized package available for selection

TIPS:

Scouring of cotton and other cellulosic fibers

Scouring is the most important wet process applied to textile materials before dyeing or printing. It is mostly a cleaning process in which foreign matter or impurities are removed. The scouring process, while purifying the α-cellulose, imparts the hydrophilic character and permeability necessary for the subsequent processes (bleaching, mercerizing, dyeing or printing). Good scouring is the foundation of successful finishing. The performance of a scouring process is judged by the improvement in wettability of the scoured material.

More specifically, scouring is conducted in order to remove unwanted oils, fats, waxes, soluble impurities and any particulate or solid dirt adhering to the fibers, which would otherwise hamper dyeing, printing and finishing processes. The process essentially consists of treatment with soap or detergent with or without addition of alkali. Depending on the fiber type, alkali may be weak (e.g. soda ash) or strong (caustic soda).

When soap is used, a good supply of soft water is necessary. The metal ion (Fe³⁺ and Ca²⁺) present in hard water and pectin of cotton can form insoluble soap. The problem is more acute when scouring is carried out in a continuous process involving a padding bath where the liquor ratio is much lower than in the batch process; the chelating or sequestering agent, e.g., Ethylenediaminetetraacetic acid (EDTA), Nitrilotriacetic acid (NTA), etc., may be used to prevent scum and film formation. A high-quality synthetic detergent provides a good balance with wetting, cleaning, emulsifying, dispersing and foaming properties, thus providing good cleaning ability. Anionic, non-ionic detergents or their blends, solvent-assisted detergent blends and soaps are mostly used for scouring. For accelerating the scouring process, wetting agents in conjunction with high boiling solvents (cyclohexanol, methylcyclohexanol, etc.) are sometimes used, but the process may not be eco-friendly. The function of solvents is mostly to dissolve insoluble fats and waxes.

Builders are added to the kier-boiling bath to increase the activity of soap or detergents. These are generally salts such as borates, silicates, phosphates, sodium chloride or sodium sulphate. Sodium metasilicate (Na₂SiO₃, 5H₂O) can additionally act as a detergent and buffer. The function of the buffer is to drive soap from the water phase to the fabric/water interface and consequently increase the concentration of soap on the fabric.

During boiling of cotton with caustic soda, entrapped air may cause oxidation of cellulose. This may be prevented by the addition of a mild reducing agent such as sodium bisulphite or even hydrosulphite in the scouring liquor.

Scouring processes for different textile materials vary widely. Among natural fibers, raw cotton is available in the most pure form. The total amount of impurities to be removed is less than 10% of the total weight. Nevertheless, prolonged boiling is necessary as cotton contains waxes of high molecular weight, which are difficult to remove. The proteins also lie in the central cavity of the fiber (lumen) which is relatively inaccessible for the chemical used in scouring. Fortunately cellulose is unaffected by prolonged treatment with caustic solution up to the concentration of 2% in the absence of air. Hence, it is possible to convert all the impurities during scouring, except natural coloring matters, into soluble form, which can be washed away with water.

Scouring of cellulosic fibers other than cotton is quite simple. Bast fibers like jute and fl ax cannot be severally scoured owing to the chances of removal of several non-fibrous components with consequent damage of the material. These are generally scoured using soap or detergent along with soda ash. Jute is frequently used without further purification, but fl ax and ramie are usually scoured and often bleached. Jute for dyeing is pre-scoured but considerable amounts of lignin remain, leading to poor light-fastness.

Since natural impurities such as cotton wax, pectic substances and protein are associated mainly within the primary wall, the scouring process aims to remove this wall.