1. Required before finalizing the nylon fabric Washing water
Normally dyeing nylon fabrics containing spandex needs to be washed before dyeing, because the spandex content is high and the silicone lubricant contained is relatively high (spandex generally contains more than 8% silicone oil). If the silicone oil is not removed before dyeing, When the embryo is set at high temperature, the silicone oil will be cross-linked and adsorbed on the nylon yarn, which will seriously hinder the dyeing of acidic materials during dyeing, thus forming dye flowers.
a. Generally, a dry cleaning machine (tetrachlorethylene is used as the extraction agent) is used to remove oil in a sealed manner. This is a better method and has high silicone oil removal efficiency;
b. Secondly, an open-width water washing machine will be used. The number of sections of the feeding box and water washing box can be adjusted. Degreasers and chelating dispersants can be added. Each tank needs to be overflowed and drained. The total water consumption is controlled at 1:40-1. : 60, the general oil removal efficiency is only 30%-40%, but it can make the oil content of the cloth more evenly distributed and improve the dyeing. It is important to pay attention to the selection of oil remover and dispersant to prevent the washed silicone oil from demulsifying and re-staining, and dyeing. White spots form;
c. Third, a Beam cylinder or JET cylinder will be used to remove oil first (including some indefinite embryos, which are directly dropped into the cylinder to remove oil and dye). The oil removal efficiency will be relatively high, but attention should be paid to the problem of the cloth surface. If there is no pre-shrinking, directly drop the oil in the dyeing vat. After dyeing, creases and chicken claw marks will easily appear on the fabric surface. It is recommended to wash it in open width (phase dyeing and pre-shrinking to eliminate stress), and then drop the oil in the vat;
2. High-temperature predetermined embryos cause dyeing Impact
In nylon fabrics, under high temperature conditions, the terminal amino groups are easily oxidized (acidic material coloring groups). If the nylon high temperature anti-yellowing protective agent is not added at 190 degrees and 193 degrees, the color absorption of subsequent dyeing will be greatly affected. A high-temperature anti-yellowing agent (expensive) for nylon must be added when setting the embryo. It is usually recommended to use LANXESS (Bayer) GR 25-40g/l.
What needs to be mentioned directly is the problem of yarn separation after purchase. We find that often after a batch of yarn comes back, there are always one or two yarns that are colored differently from other yarns, including Korean Hyosung, Asahi Kasei, Toray and Dupont yarns. In the early stage of bulk weaving, yarn trial work is required to separate the yellow and white yarns from the dark and light yarns. Due to the slight difference in color absorption of these yarns, during high-temperature setting, horizontal and straight strips will appear during final dyeing, just like triode amplification;
Sometimes the storage conditions of the yarn count will also cause differences in the color absorption of nylon yarn, so the storage of nylon yarn is very critical.
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