.When dispersing red BWFL is used for high temperature and high pressure dyeing, why is it easy to produce color spots? How to prevent it?
Answer: When dispersion red BwFL is used for high temperature and high pressure coloring, the reasons for color spots are as follows.
① The quality of dispersed red BWFL is poor, and sometimes the particle size is large. After the material is mixed, recrystallization of tiny particles occurs. When the recrystallized particles gather together, they will precipitate from the dye and deposit on the fabric or machine wall, causing color point.
② Improper chemical materials can easily cause the dye to form large particles with high viscosity, especially in cold water. It is difficult to dissolve the sticky dye that has formed into “mud”. If the dye solution is poured into The dye vat will adhere to the fabric and form color spots and spots.
③ The temperature rises too fast during coloring, especially if the steam volume is too large or the air pressure is too high in the early stages of coloring, it can destroy the dispersion state of the dye bath, cause dye flocculation or aggregation, and lead to the production of color spots and color spots.
The prevention methods are as follows.
① Strengthen dye quality inspection: The quality of dyes should be tested before they are put into production. Observe the dye particle size distribution and determine the fineness of the dye particles. During detection, the prepared 3% dye solution can be stirred thoroughly and 0.4 mL be drawn. Continuously drip into the small holes of the glass plate (use two glass plates, the upper one has a d=1mm hole drilled in the center, and a piece of filter paper is sandwiched between the two glass plates), and then continue to drip 0·2mL of distilled water every 5 minutes. into the small hole (a total of 5 times, a total of 1.0 mL of distilled water was dropped), wait until it diffuses around until the penetration circle is stable, take out the filter paper, dry it, observe its diffusion performance, and rate it. Level 4-5 is considered qualified (that is, a uniform colored bleeding circle is formed, and the middle spot circle is not obvious). You can also dip a glass rod into a small drop of glycerol and drop it on the slide. Use another slide to spread the glycerin into a thin layer. Then stir the prepared dye solution with a concentration of 0.5g/L and suck it up with a blood pipette. 0.1mL, immediately drop it on the slide that has been coated with a thin layer of glycerin, cover the slide, place it on a 1000x microscope platform, let it sit for a while and observe the dye particles with a diameter equal to 2 μm and greater than 2 μm within a field of view. number. If the diameter is 2 μm or more and within 5 pieces, and the maximum diameter is 3 to 5 μm, it is considered qualified.
② Use co-solvent materials. For most disperse dyes, they only need to be hydrated at 40°C. However, a few disperse dyes such as dispersed scarlet BWFL and dispersed ruby H2GFL use co-solvent materials because they are easy to agglomerate in water. , which can improve efficiency and reduce color point generation. Commonly used co-solvents include ethanol, isopropyl alcohol, acetone, etc. Among them, ethanol is widely used. When making the dye, add ethanol to the dye at a ratio of 1:1, stir it into a slurry, and then rinse it with 10 times the water.
③ Control the heating speed. After fabric pre-treatment and cleaning, when the temperature rises to 60°C, pump the dye solution into the dye vat. After running for 5 minutes, turn on the steam to raise the temperature. The temperature rises from 60°C to 60°C at a rate of 2°C/min. 100℃, the dispersed red BWFL is only adsorbed on the fiber without dyeing below 100℃, while at 100~120℃, it is the critical absorption zone for dye coloring. At this time, the temperature rise should be slow, with 1℃/min as the It is advisable to keep the dyeing process for 40 to 60 minutes after the temperature is raised to 130°C. Since the dispersed red BWFL dyes the fiber slowly, the insulation time should not be too short, and it is also conducive to the migration of the dye. After the coloring is completed, the temperature is lowered to 70°C, and the liquid is drained and restored for cleaning.
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