Tuesday, April 29, 2008

Pilling of garment

Pilling is a garment surface fault characterized by little pills of entangled fibre and clinging to the cloth surface and giving the garment an unsightly appearance. The pills are formed during wear and washing by the entanglement of loose fibre, which protrude from the fabric surface, under the influence of rubbing action. These loose fibres develop into small spherical bundles anchored to the fabric by a unbroken fibres.

Polyester, PAN, nylon etc are strong fibre and pills forms on the garment made out of these fibres accumulate more and more making garment more unsightly.

To minimize pilling tendency, higher twist factor for yarns, the brushing and cropping of fabric surface and special chemical treatments can be used. Also, increasing the filament denier can also minimize the pilling tendency of the garments.

Friday, April 18, 2008

Dye carriers

Dye carriers are accelerators that assist in the dyeing of synthetic fabrics in a shorter time at a lower temperature. They are particularly used for dyeing polyesters with disperse dyes, although they were originally developed for cellulose acetate. There are a number of carriers commonly used for polyester fibres. Some of the good dye carriers are o-phenyl phenol and it’s monochloro derivative, p-phenyl phenol, diphenyl, monomethyl naphthalene, trichlorobenzene, dimethyl terephthalate and methyl salicylate. Other dye carriers in common usage are o-dichlorobenzene, diphenyl ether, n-butyl phthalimide, chloromethoxy ethanol, methyl cresotinate, alkyl and aryl benzoates and tetralin. The dye carrier imbibes deep shades on the polyester and blended fabrics. Acrylic and nylon fibers also can be dyed using dye carriers but this approach is more expensive than the other alternatives available.
In practice, the choice of the dye carrier is governed by its general effectiveness, toxicity, economics and environmental acceptance. Some of the phenolics and chloro-derivatives are getting eliminated. In a typical operation for dyeing polyester fiber, the dye carrier suitably emulsified in water is used in both the exhaust method at atmospheric pressure as well as in high temperature beam dyeing. After dyeing, the dye carrier is removed from the fabric by an after-scouring process. Whereas dye carriers like the chlorobenzenes are used by emulsification, the phenyl phenols can be used as their water soluble sodium salts along with an acid-liberating agent like ammonium phosphate. At about 100C, the free phenol liberated forms the active carrier which is later removed by alkaline scouring. Butyl benzoate is another successful carrier for use in polyester dyeing at the boil at atmospheric pressure.
The dye carriers are generally used with a leveling agent on polyester/wool mixtures in a high temperature process. The formulations usually consist of around 70% active ingredients (one or more dye carriers), 15% leveling agent and 15% solubilising agent. Depending on the color and shade, the dye carrier used is in a variable range of 2-10% of the textile weight.

author : Laxmikant S. Jawale