Accidents and mistakes can never be completely avoided.
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In the process of dyeing and finishing, it is inevitable that there will be some batch dyeing defects. Although many problems originate from pre-processing or because of some ongoing operations, dyeing workers are always responsible.
At the same time, people's requirements for the quality of clothing fabrics are getting higher and higher. The textile and dyeing fabrics exported to the European and American markets are more stringent on the appearance quality (color, color, and appearance).
In the past, according to the national standard, it only needed 3 levels (light source 4 40W fluorescent lamps), and now different light sources (such as D65, TL84, U30, etc.) are often used, and the requirement for 4 or more levels is even 4.5.
Therefore, it is inevitable to modify the dyed fabrics.
The lace rope finds that the method used to modify the dyed defects depends largely on the nature of the defects. If the color difference is small and the cloth is even, it can be directly modified with dyes, reactive dyes and other dyestuffs, so as to achieve the quality requirements of the genuine products.
But in most cases, the dyeing defects are often uneven cloth, stain or color completely against the standard sample. In this case, it is very necessary to strip the dyed defects.
The stripped fabric is then tested against the standard sample and then dyed again.
Lace rope belt commonly used color stripping and repair technology to summarize, for colleagues reference.
Stripping principle
It is the use of chemical action to destroy the dye on the fiber and make it lose its color.
There are two main types of chemical stripper. One is the reductive stripping agent, which destroys or decolorization by destroying the Chromogenic System in the structure of dye molecules, such as azo dyes, whose azo groups may be reduced to amino and lose their color.
However, the destruction of dyes by some reducing agents is reversible, and its fading can be resumed, for example, the coloring system of anthraquinone structure.
Safe powder and carved white powder are commonly used reductive stripping agents.
The other one is oxidative stripping agents, the most commonly used are hydrogen peroxide and sodium hypochlorite.
Under certain conditions, oxidants can cause the destruction of some groups of dyestuff molecules, such as azo decomposition, amino oxidation, hydroxyl methylation, complexation of metal ions and so on.
These irreversible structural changes lead to the fading or fading of dyes, so theoretically speaking, the oxidizing stripper can be completely stripped.
This method is better for anthraquinone dyes.
Principle and technology of chromatic light correction
It is necessary to make corrections when the color of the dyed fabric does not meet the requirements.
The principle of chromatic correction is the principle of residual color.
The so-called residual color, that is, the two colors have the characteristics of mutual reduction.
The complementary colors are red, green, orange, blue, yellow and purple.
For example, if the red light is too heavy, a small amount of green paint can be added to reduce it.
But the remaining color is only used to adjust the color light slightly. If the dosage is too large, it will affect the depth and brightness of the color. The general dosage is about lg/L.
Generally speaking, reactive dyed fabrics are difficult to repair, and VAT dyed fabrics are easy to repair. Sulphur dyes are difficult to control when they are reprocessed, usually with vat dyes and subtractive dyes. Direct dyes can be used for color reconditioning, but the dosage should be less than 1 g/L.
Dyed fabrics are slightly darker, more floating color, less color than washing and soaping fastness, and light stripped (refer to dye stripping process, conditions are slightly less than normal stripping process), alkali washing and washing (suitable for alkali sensitive dyes, mostly used for reactive dyes; for example, reactive black KNB dyed coloured dyed fabrics such as light blue, can be achieved by adding proper amount of caustic soda, supplemented by steaming and flat washing to achieve blue light for shallow purposes), and rolling brighteners (suitable for dyeing finished cloth red light, especially for finished fabrics dyed with reduced dyes, which are more effective in medium and light coloring. The usual method is water washing.
Normal bleaching and bleaching can be considered as complex bleaching, but hydrogen peroxide should be used as the main bleaching agent to avoid unnecessary color change and paint coloration.
Post time: 2024-10-16 14:53