What is the treatment process after washing?
After the fabric passes through the main washing and bleaching, the washing comes to an end, but in order to make the clean fabric need to be chemically treated according to different purposes to meet people’s requirements for the best use of the fabric, it needs to be washed after treatment. The post-washing treatment includes six processes: watering, softening, neutralizing, whitening, simmering, and dehydrating.
1. Over water
Whether it is household laundry or industrial laundry, the overall washing quality must be ensured. In addition to the control of the main wash and the supplement of bleach, the over-water link should not be neglected.
Generally, in the washing process, in order to maintain a sufficiently large concentration gradient between the water and the washing residue contained in the fabric to be washed, and to improve the water passing efficiency, a high water level is usually used. The number of times of water passing is closely related to the performance of the fabric and the performance of the detergent used. Pure cotton fiber has excellent water absorption performance. During the washing process, it absorbs many times more lotion than others. The same cotton fiber fabric has different water absorption properties due to different structures. The green towel fabric is better than the plain weave structure. Cotton fiber fabric has excellent water absorption performance. For fabrics washed with detergents containing a large proportion of alkalis, because alkalis have poor rinsing performance, relatively many times of water are required. Experimental data shows that a 50 kg washing machine After washing with high water level, the towel contains 16.7 percent residual lotion after one wash, 3.23 percent after two washes, 0.108 percent after three washes, and four washes. The latter is 0.0117 percent. Therefore, 3 to 4 passes are generally applicable to most fabrics.
After the main wash, the fabric needs a certain amount of heat to pass the water, but there is a principle to choose the temperature, and the water temperature should be reduced in proportion to each time, and it should not be changed suddenly. For example: the main wash temperature is 80%, then the first-pass water temperature is 70%, the second-pass water temperature is 55%, and the third-pass water temperature is 35%. The high-level water is used, and the time should be selected In 1.5-3 minutes, the water-passing time of the washing machine under 50 kg class can be 1.5-2 minutes, and in 50 kg class or above, 2-3 minutes can be selected.
2. Soft
After finishing the main washing and bleaching, for some comfortable, soft and fluffy fabrics, it needs to go through the softening process after washing to achieve the purpose.
Softness: After finishing the main washing and bleaching of the fabric, although it has achieved good cleanliness, it is not very soft. The softening process is to use a softener, which is dispersed in water and has a proper affinity for the fabric to make the fabric fiber. And the process of internal smoothing to a good state, soft, fluffy and antistatic effect,
Softening process: When the fabric is passed through the water once, add softener from the feeding port when the water temperature reaches normal temperature 20 degrees, and keep the water level soft and wash for about 5 minutes.
Softening requirements: when softening, it should be used strictly according to the amount specified in the softener product description. Excessive use will cause fabric dyes to change color. At present, softeners are all cationic softeners, and must not be used at the same time as fluorescent whitening agents. The time must be alternated.
3. Neutralization
Due to the alkalis, chlorine and calcium substances contained in the washing liquid during the main washing and bleaching, when the fabric is heated and treated with water. Due to the influence of washing machine and other factors, it cannot be absolutely guaranteed that these substances will not remain in the fabric, which will cause the white fabric to turn gray or yellow, affect the color vividness of the colored fabric, and make the fabric feel hard. In order to eliminate these remaining substances, it is necessary to carry out the washing treatment process of neutralization. The neutralizing acid agent is used to reduce the alkali substances, so that the pH value of the fabric surface is maintained between 5.8-6.5, and a feeling of comfort is produced. Neutralization removes calcium oxide and calcium chloride substances while whitening the fabric to a soft hand. At the same time, adding a neutralizing acid agent when passing water will reduce the number of times of water passing and save energy.
Neutralization process: two or three times of water, when the water temperature is 30 degrees to 40 degrees, add an appropriate amount of neutralizing acid from the feeding port, and wash for 3 to 5 minutes.
Requirements: The amount of neutralizing acid is generally controlled at 0.2 to 0.3%. In actual operation, it is necessary to test the pH value of the lotion after washing with neutralizing acid to ensure the exact amount of acid in it, so as to prevent the fabric from being heated to cool and corrode the equipment and the fabric after drying.
4. Sizing
This step is mainly for tablecloths, napkins, some uniforms and other cotton fabrics or mixed fiber fabrics in the catering industry. The sizing treatment can make the surface of the sizing fabric stiff, prevent the fiber from fluffing, and have a good look and feel. At the same time, it also provides a protective layer on the surface of the sizing fabric, which prevents the penetration of dirt to a certain extent, and can also make the sizing fabric due to The bonding effect of the slurry can give the fiber a certain strengthening effect, and it can play a certain role in prolonging the service life of the fabric.
When the fabric is sizing, due to the wetting and penetration of the slurry, the relative slippage of the fiber when subjected to external force is prevented, and due to the cohesion and absorption and diffusion of the slurry itself, the wetting and penetration of the slurry makes the slurry and the fabric The bonding ability between the fibers will form a firm layer on the surface of the fabric when subjected to a certain amount of heat.
There are many types of sizing agents. In view of the characteristics of fabric fibers, the frequently used sizing agents should have the following characteristics:
① It has a large cohesive force and a certain degree of adhesion, which can form a layer on the surface of the fiber.
② Have a certain ability to enhance fiber strength
③ It is easy to wash off, and there should be no peculiar smell
④ After sizing, the surface color of the fiber fabric will not be affected.
5. Dehydration
The next step of washing is dehydration, which uses the centrifugal force generated when the drum of the washing machine rotates to reduce the water content of the water-containing fabric in the drum as much as possible. , The high-speed dehydration process of the general industrial washing machine with dehydration function can reduce the moisture content of the fabric to 30 to 45 percent. Dewatering efficiency and equipment, fabrics have a lower moisture content, and vice versa, but under the same centrifugal force and the same operating time, the moisture content of the surface fabric is higher than that of blended fabrics and chemical fibers, and towels are better than pure cotton sheets. To be high. The moisture content of the fabric will directly affect its drying and ironing efficiency. For example, a towel with a low moisture content will consume a shorter drying time than a towel with a high moisture content under the same drying conditions, but has a low moisture content. Under the ironing conditions of the same temperature, the ironing speed of the sheets is faster than that of the sheets with high moisture content.
