Views: 0 Author: Site Editor Publish Time: 2020-10-14 Origin: Site
01 Alkaline problem
The pretreatment of cotton fabrics usually requires a higher concentration of alkali treatment to remove fabric impurities (especially a larger amount of mercerizing alkali). It is not easy to wash the alkali into the fiber. It is also necessary to add alkali during dyeing (reactive vat dyes). The cloth surface may be alkaline during finishing. The chemical fiber fabrics must undergo reduction cleaning after dyeing. At present, printing and dyeing factories are still using sodium hydroxide and caustic soda for cleaning. If the subsequent cleaning is not clean, it will also cause alkali on the soft surface. Ordinary silicone oil is not alkali-resistant and will break under alkaline conditions. This is the reason why the factory sticks to the roll after passing several kilometers when it is soft. Therefore, before softening the cloth surface must be washed with alkaline agent or added acetic acid in the working liquid to maintain the PH5-6 of the rolling tank.
02 Cohesion problem
On fabrics containing short fibers (cotton cloth, T/R cloth, velvet), it is inevitable that some short fibers will fall off during the processing. The short fibers that fall off the cloth will accumulate in the nip, which is different from ordinary Silicone oil produces cohesion, and as the finishing liquid goes up to the rollers, it bonds with the squeezed and demulsified silicone oil to form sticky rollers or silicon spots. When the water quality is relatively poor, it will also condense with ordinary silicone oil to produce sticky rollers. In addition, there will be similar situations in fluffy fabrics. Do a good job of cleaning before driving, and find that the flowers should be cleaned at any time.
03 Charge stability problem
Most of the dyes and brighteners used in cotton are anionic, while the whitening of cotton is basically done on the setting machine. In addition, when the color of the dyed cloth is not right, the color needs to be fine-tuned. The color correction is usually added with a small amount of dye or paint when applying the soft finishing agent. The factory generally uses ordinary silicone oil (weak cation) to cause anion and cation charge attraction reaction, causing agglomeration and sticking to the roller. , And the softness of the anionic silicone oil does not meet the requirements, causing confusion in the factory. Charge uniformity must be considered during processing.
04 Temperature problem
The cloth dyed by the long cotton car must be dried in a drying cylinder, and then packed in large packages or stacked in a cloth box. If it is not sufficiently cooled, especially the cloth in large packages, the surface temperature of the fabric may be higher when it is soft. This causes the temperature of the working fluid in the rolling groove to rise (especially in summer), sometimes reaching above 60°C, and when the heat resistance of ordinary silicone oil is not good, it can also cause sticking to the roll.
The temperature in the rolling groove should not exceed 40°C.
05 Fixed speed problem
When the factory is making some thin fabrics, the speed of shaping is very fast, sometimes reaching a speed of 60 m/min. Due to the poor permeability of ordinary silicone oil, the silicone oil flows back on the rollers and causes sticky rollers. Pay attention to replace the working fluid in the rolling groove and wipe the roll frequently.
06 Dip tank problem
In many factories, when dipping and softening, ordinary silicone oil will stick to the cylinder wall. Over time, some black oil spots will form on the cylinder wall, which will form silicone oil spots on the cloth surface. Strengthen cleaning
07 Hand feeling problem
As the requirements for the hand feel of fabrics in the market are getting higher and higher, and various fabrics need to show a variety of different style requirements due to different seasons and different customer requirements. There are requirements for smooth drape, slippery and flexible, Fluffy and soft, purely elastic, etc. A kind of silicone oil generally can only reflect one style. As a result, many factories have to use many kinds of silicone oils, resulting in chaotic production. Sometimes they cannot find the silicone oil that meets the requirements of customers and can only give up business and cause losses. We can control the molecular weight and molecular distribution by selecting different amino silicone oil end groups with different ammonia values to synthesize amino silicone oils with different ammonia values, viscosity and reaction, to meet the requirements of various fibers in terms of softness, smoothness and elasticity.
08 Cost issue
At present, the most perplexing problem for printing and dyeing factories is the cost issue. Because the prices of water, electricity and steam are rising, while the printing and dyeing processing costs are decreasing, many printing and dyeing factories have been busy for a year, but there is basically no profit. Therefore, the cost control is printing and dyeing. The problem that the factory must solve The cost of finishing auxiliaries is a big part of printing and dyeing factories, so the cost of finishing auxiliaries is an urgent problem for printing and dyeing factories.
09 Yellowing problem
A long time of shutdown during operation causes the fabric to stay yellow and the amino hydrogen of the amino silicone oil is easily oxidized by air to form a chromophore, which turns yellow. The product turns brown, and brown makes the white fabric look like it has lost its most basic white or simply turned yellow. The pH is too high and the temperature is too high during drying, and the accompanying substances of cotton fabric turn yellow. Strengthen process control. Storage is yellowing. Caused by polluted gas in storage.
10 Fluorescence degradation
The interaction between the anionic brightener/cationic softener ions is coagulated and should be divided into two processes.
The brightener is sensitive to acid or the brightener is excessive, and acid-resistant fluorescent brightener should be selected.
Fluorescent brighteners have poor light fastness, and the light effect makes the fabric brown. Choose a fluorescent brightener reasonably.
Water quality impact:
The content of impurities such as microorganisms and seaweed is too high, which can be filtered to remove impurities.