Textile silicone oil soft finishing in printing and dyeing factory
Common problems and Solutions
1. Alkalinity problem
In the pretreatment of cotton fabric, a higher concentration of alkali is usually used to remove the impurities (especially mercerizing alkali is used more). It is not easy to wash when alkali enters into the fiber, and alkali is added when dyeing (reactive vat dyes), so the cloth surface may be alkaline during the post finishing. The chemical fiber fabric should be deoxidized and cleaned after dyeing. At present, the printing and dyeing factory still uses insurance powder and caustic soda for cleaning. If the back cleaning is not clean, it will also cause alkali on the soft front cloth. The common silicone oil is not alkali resistant and will break the emulsion under alkaline conditions, which is the reason why the roller sticking occurs when the mill passes several thousand meters in the process of dip rolling softness. Therefore, before softening, the cloth surface must be cleaned with alkali agent or added with acetic acid in the working solution to keep the groove ph5-6.
2. Cohesion problem
On the fabrics containing short fibers (cotton cloth, t / R cloth and velvet), it is inevitable that some short fibers will fall down during the processing. The short fibers falling down from the cloth will accumulate in the rolling groove, which will generate cohesion with the common silicone oil. As the finishing liquid goes up to the roll, it will bond with the extruded and demulsified silicone oil to form a sticking roll or silicon spot. When the water quality is poor, it will agglomerate with common silicone oil to produce sticky roller. In addition, there will be similar situation for fluffy fabric. Before driving, do a good job of cleaning, and clean the flower hair at any time.
3. Charge stability
The dyes and whitening agents used in cotton cloth are mostly anionic, while the whitening of cotton is basically completed on the setting machine. In addition, when the color of the dyed fabric is not right, it needs to fine tune the color. Usually, a small amount of dye or coating is added when the color is modified with a soft finishing agent, while the common silicone oil (weak cation) is used in the factory, which will generate a negative and positive charge attraction reaction, resulting in condensation and roller sticking, while the hand feel softness of the anionic silicone oil fails to meet the requirements, causing confusion in the factory. Charge consistency must be considered in machining.
4. Temperature problem
The cloth dyed by the long cotton cart must be dried by the drying cylinder. If it is not sufficiently cooled, especially the cloth in the large roll, the surface temperature of the fabric may be higher when it is soft, which may cause the temperature of the working liquid in the rolling groove to rise (especially in summer), sometimes to over 60 ℃, while the ordinary silicone oil with poor heat resistance may also cause roller sticking.
It is better to keep the temperature within 40 ℃.
5. Fixed speed problem
When the factory is making some thin fabrics, the setting speed is very fast, sometimes it can reach the speed of 60m / min. due to the poor permeability of common silicone oil, it causes the silicone oil to flow back on the roller, which results in roller sticking. Pay attention to change the working fluid in the rolling groove and wipe the roll frequently.
6. Problem of staining cylinder
In many factories, ordinary silicone oil will stick to the cylinder wall when it is soaked and soft. After a long time, some black oil spots will form on the cylinder wall and the silicone oil spots will form on the cloth surface. Strengthen cleaning work
7. Hand feeling problems
Due to the higher and higher hand feel requirements of fabrics in the market, and due to different seasons and customers' requirements, various fabrics need to show different style requirements, such as smooth and draping, smooth and flexible, fluffy and soft, pure elastic, etc. A silicone oil can only reflect one style. As a result, many factories have to use many kinds of silicone oil, resulting in production confusion. Sometimes, they can not find silicone oil suitable for customer requirements, so they can only give up business and cause losses. We can control molecular weight and molecular distribution by choosing different amino silicone oil end groups with different ammonia value to synthesize amino silicone oil with different viscosity and reaction to meet the requirements of flexibility and smoothness of various fibers.
8. Cost issues
At present, the most perplexing problem for the printing and dyeing factory is the cost problem. Because the price of water, electricity and steam is rising, while the printing and dyeing processing fee is decreasing, many printing and dyeing factories have been busy for a year, but the profit is basically not available, so the cost control is the problem to be solved by the printing and dyeing factory. The cost of finishing auxiliaries is a big part of the printing and dyeing plant, so the cost reduction of finishing auxiliaries is an urgent problem to be solved.
9. Yellowing problem
Hot yellowing: the long-term shutdown in operation causes the fabric to stay yellowing, while the amino hydrogen of amino silicone oil is easily oxidized by air to form chromophore, and yellowing. The product turns brown, which makes the white fabric look like it has lost its most basic white or simply turned yellow. When the pH is too high, the temperature is too high when the cotton fabric is dried. Strengthen process control. Store yellowing. Caused by polluted gas in storage.
10. Fluorescence degradation
The interaction between anionic brightener and cationic softener is coagulated, which should be divided into two processes.
Pan green: whitening agent sensitive to acid or excessive whitening agent, acid resistant fluorescent whitening agent should be selected.
Light damage: the light fastness of fluorescent whitening agent is poor, the light effect makes the fabric brown, and the fluorescent whitening agent should be selected reasonably.
Water quality impact: microorganism, seaweed and other impurities are too high, which can be filtered and precipitated to remove impurities.
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Source: China textile auxiliary net, edited and reprinted by Dyer Wujiang, please indicate the source
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