Colorants Fabrication
It is very important to have in mind several aspects in the producing colorants process so we can obtain the best quality and more productivity.
Some of them are:
Raw material and inputs for colorants
First of all we need to make sure we are using the right products and the right quality to get the colorants we would like to obtain.
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Availability of the products is another important when producing colorants. That´s why we need to avoid any kind of problem in the technical and administrative area. |
Colorants Technology
Operation Procedures when producing colorants must be as clear as possible in security and process variables as: temperature, pH, reactives, excess, etc. defined in ranges previously studied. This practices will ensure a great quality avoiding undesired results due to colorants chemistry complexity. The process cycles in charges, warm ups, cool downs, reflux, destilations, filtrations and dried; must be determined in the plant and stablished within a better quality at less cost ranges. In each one of the most importants steps of the process there must exist standard controls to measure if the colorant´s quality is going on the right way or if there´s need to make some changes to adjust the process.
The product´s quality final tests, must be as representatives as possible of the final use of the colorant.
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The process performace must be as good as possible because the results depend of the sum of all the steps previously named to get the maximum beneffit.
Two very common reactions when making colorants take place between an aromatic amine with notrous acid to produce a special component, wich later will get mixed with an accoplator and then produce the colorant.
These reactions are known since a long time ago (Griess, 1858), but it wasn´t until recent years that its mechanism has clarified.
Colorants based on this reaction are considered the biggest chemical class ever, with the widest range and different uses.
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Due to the easyness and economy when preparing the colorant by this technique, it has been selected among other cases in an industrial scale.
Besides these two reactions, there are some others: adition, protonization, condensation, oxidation, etc. but they are worthless mentioning.
Next, a list of descriptions with flux diagrams for the colorants fabrications. The next guide is a very general review about the production methods.
BASIC AND DISPERSE COLORANTS
This kind of colorants are produced with more sofisticated equipment than acid and direct colorants using explotion proof equipment due to the kind of reactions used, a very generalized flux diagram is presented in wich the next steps of the process can be seen:
1) Solution
2) Condensation or Copulation
3) Filtration
4) Washed
ACID AND DIRECT COLORANTS
For these colorants fabrication it is necessary to find a kind of flux diagram divided into the next steps:
1) Solution
2) Copulation
3) Filtration and Washed
4) Dried
5) Crushed
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QUALITY CONTROL
Quality´s control during production is obvious. The methods used in the intermediate steps consist mainly in analytic methods along with test made to samples of the plant and processed in the laboratory by similar processes to the one at the main stage.
A lot of methods have been developed to produce colorants. These methos differ in sophystication, from very simple titulations and pH determinations, to nuclear magnetic resonance. There are lots of calutative or semi-cualitative tests used by a colorants chemist to follow a reaction´s course.
One of the most importants weapons for the colorants chemist is the Thin Layer Chromotograhy (TLC). This is simple and quick, it uses non expensive equimpment, and it allows to analyze color. This color chemist knows fibers must dye in the right light.
Along with the chemical analysis and the colorant application to the fiber, there are other kind of test as: solobility, particule´s size, light resistance, sweat, friction, etc. All of them are made having in mind the fiber kind and the colorant.
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