Search results
Results from the WOW.Com Content Network
Solution dyeing, also known as dope or spun dyeing, is the process of adding pigments or insoluble dyes to the spinning solution before the solution is extruded through the spinneret. Only manufactured fibers can be solution dyed.
Dope dyeing: In dope dyeing, pigments are added to the polymer solution itself before extruding the fibers. The process provides the dyed fibers with excellent fastness properties. The dope dyeing applies to synthetic fiber only.
Although almost all dyeing can be done in a vat, the term vat dye is used to describe a chemical class of dyes that are applied to cellulosic fibre (i.e., cotton) using a redox reaction as described below. Because of the use of caustic soda, and the very high pH of the dye bath in the dyeing process, wool cannot be dyed using vat dyestuffs.
N-Methylmorpholine N-oxide is a key solvent in the Lyocell process . At the Lyocell mill, rolls of pulp are broken into one-inch squares and dissolved in N-methylmorpholine N-oxide (NMMO [2]), giving a solution called "dope".
The advantage of this process is the saving of shredding, as the cellulose layers can be added directly into the stirred tank. Acetylating the cellulose: In the commercial production of cellulose acetates, the acetic acid process or the methylene chloride process are usually used for acetylation. In acetic acid processes, the pre-treated ...
[citation needed] In the late 1950s, Courtaulds Ltd began investigating the production of an acrylic fiber later to be called "Courtelle" by a process of solvent polymerization. Methyl acrylate (6%) and acrylonitrile were polymerised in a 50% solution of sodium thiocyanate to produce a dope ready for spinning into a water bath to produce ...
At the time, addicts were lucky to find a hospital bed to detox in. A hundred years ago, the federal government began the drug war with the Harrison Act, which effectively criminalized heroin and other narcotics. Doctors were soon barred from addiction maintenance, until then a common practice, and hounded as dope peddlers.
During the dyeing process, the dye must become close and even with the material in order to produce a uniform color that is fast to moisture, heat, and light. [5] Due to their superior fastness properties and simple application, reactive dyes are currently the most common type of dye for cotton dyeing. [6] The CPB technique uses less water and ...