Desizing enzyme common problems and preventive measures

(1) Desizing enzyme itself

cause

If the concentration of desizing enzyme is too low, the desizing effect is poor.

Desizing enzymes are improperly stored or stored for too long, and their activity is reduced, inactivated or deteriorated.

The optimal use temperature and pH value of desizing enzymes do not match the actual desizing process.

Precaution

Use a desizing enzyme with high activity and good desizing effect.

Use desizing enzymes with good storage stability, and try to use them up within the shelf life.

Select a desizing enzyme that matches the temperature and pH of the actual desizing process

(2) Fabric composition and organizational structure, etc.

cause

Differences in fabric composition, such as pure cotton, polyester/cotton, tencel, rayon, linen and other woven fabrics, due to their own fiber characteristics, there are differences in the adsorption and fixation methods of the pulp, resulting in the same desizing enzyme dosage and desizing process. There will be differences in the desizing effect under the

Differences in fabric structure: yarn count, weaving structure, fabric density, thickness and gram weight.

The cloth surface is not clean (with acid, alkali, oil or heavy metal ions).

Precaution

Determine the appropriate amount of desizing enzyme according to the differences and requirements of fabric types, and form your own desizing process database.

For fine, compact or heavy fabrics, the dosage of penetrant and desizing enzyme should be appropriately increased to prolong the desizing process time.

If the fabric contains oil, acid or alkali, it should be washed and neutralized as much as possible before desizing; if the fabric contains excessive heavy metal ions, an appropriate amount of chelating dispersant should be added during desizing.

(3) Types of pulp and pulp content

cause

At present, there are many types of sizing materials. When fabric sizing, starch, modified starch, PVA, PAC, etc. are used alone or in combination. Due to its specificity, desizing enzymes can only decompose starch and partially modified starch sizing. Therefore, before desizing The composition and proportion of the fabric slurry should be understood or analyzed by the weaving factory first.

The level of sizing content is related to the loom, cloth type, yarn strength, sizing process, etc., and has a specific guiding role for the formulation of the subsequent desizing process.

The cloth surface is not clean, with acid, alkali, oil or heavy metal ions.

Precaution

Determine the appropriate amount of desizing enzyme according to the difference and requirements of fabric types, and form your own desizing process database. If necessary, first test the sample before mass production, and try to remove it at one time; for starch slurry containing PVA, etc. In the case of chemical pulp, it is recommended to increase the hot water washing process before desizing or add a non-ionic emulsifier or refining agent during desizing.

For fabrics with high sizing ratio, the dosage of desizing enzyme should be appropriately increased or the desizing time should be extended.

If the fabric contains oil, acid or alkali, it should be washed with detergent as much as possible before desizing to neutralize it; if the fabric contains excessive heavy metal ions, an appropriate amount of chelating dispersant should be added during desizing.

(4) Desizing equipment

Desizing equipment mainly used in enzymatic desizing currently includes uniform rolling car, J-Box stacking box, crawler steaming box, open width continuous washing machine, airflow or overflow dyeing machine, jigger and so on.

cause

The desizing equipment is seriously stained, and there may be rust, acid or alkali, oxalic acid, oxidants, additives, etc.

Padding uniformity, temperature uniformity during stacking, sealing and uniformity of steam box, equipment speed and mechanical force, etc.

Washing equipment: temperature, number of sections and length of washing box, mechanical strength of washing, water circulation

Precaution

The equipment should be cleaned before desizing to avoid the influence of rust and stains on desizing enzymes.

Before desizing, the operation and maintenance of the equipment should be carefully checked regularly to ensure the normal operation of the equipment, and the operating parameters of the equipment should be adjusted appropriately according to the actual situation and desizing requirements.

In terms of washing equipment, if the washing is not clean, it is easy to cause the products such as dextrins, monosaccharides or polysaccharides after desizing to be removed cleanly, and stick to the cloth after drying, which will affect the actual desizing effect. Therefore, washing equipment should be used. Ensure that the washing box is long enough, the temperature is high enough, and the mechanical force and water circulation of the washing are enhanced.

(5) Desizing process conditions

cause

Rollover rate is low.

When preparing the working solution, the local heating is too fast, resulting in the loss of desizing enzyme activity.

The dosage is low or the head and tail are poor.

The temperature of the rolling liquid or the temperature of the dipping and desizing treatment is insufficient or the temperature is too high.

Too fast speed, short stacking or washing time.

Dirty or insufficient washing.

Precaution

Increase the overroll ratio to 70%-80% or above.

Warm up to the specified temperature before adding the desizing enzyme.

Increase the dosage of desizing enzyme, and adhere to the "small water and long flow" uniform supplement to the supplementary material.

According to the optimal use temperature of the desizing enzyme, the temperature of the rolling groove and the temperature of the desizing process should be appropriately increased or decreased.

Reduce vehicle speed and extend stacking or washing time.

For heavy fabrics, add a small amount of liquid caustic soda or detergent in the washing box to improve the washing effect and improve the water circulation and mechanical force.

(6) Water quality

cause

The pH value of water is high or low. Generally speaking, the best application pH value of desizing enzyme is 5.0-8.0. Too high or too low pH value will lead to the decrease of desizing effect.

The total hardness of water is too high or too low. Generally speaking, Novozymes recommends that the total hardness should be controlled at 30-100ppm when using desizing enzymes.

The content of metal ions in water exceeds the standard, such as Ni+, Cu2+, Ag+, Fe3+, etc., all have different degrees of inhibition on desizing enzymes.

Precaution

The process pH is formulated according to the optimum pH for the use of desizing enzymes.

Use demineralized water or add appropriate amount of chelating dispersant.

A proper amount of chelating dispersant with excellent metal ion chelating performance is added.

(7) Auxiliaries or other chemicals

In the enzymatic desizing process, the auxiliaries and chemicals that may be used include penetrants, degreasers, chelating dispersants, wax removers, in-bath softeners, defoamers, etc. For denim, the fabric may contain fixatives, softeners, alkali sulfides, etc.