Ashraful Islam
Denim, the world’s most iconic fabric nowadays, comes from French “serge de Nimes” which refers to a particular type of fabric that was produced in Nimes, a town of France. Alongside accessories like belt, shoes, purses the majority of denim fabric is used in making apparel like jeans, skirts, shirts, jackets etc. Bangladesh is one of the largest denim exporters of the world. According to otexa, 585 million dollar denim goods were exported from Bangladesh to USA in 2019 and in Europe it was more than 1 billion dollar. This article will be described chemical uses in the denim production and their function.
In Pre-treatment stage following chemicals are used-
| Chemical Name | Function |
|
Peroxide Stabilizer |
o Prevents degredation of pinholes and strength by suppressing decpmpositon of peroxide
o Plays an important role to obtain high quality bleach product |
| Scouring Agent | o Eleminating hydrophobic impurities without deteriorating fabric itself |
| Desizing Agent | o It helps in the removal of added impurities in the form of starch and other synthetic sizes without having any adverse effect on the fiber. |
| Caustic Soda | o It is used to open up fabric for absorbtion of dye.
o It is major chemical that fixes the dye and hydrosulphite in fabric. |
In Dyeing stage following chemicals are used-
| Chemical Name | Function |
|
Dispersing Agent |
o Assist the process of particle size reduction of dye.
o Maintain a dispersion in a fine form through dyeing process. |
|
Acrylic Polymer |
o Acrylic polymer containing hydroxyl groups are utilized in base coats as binders, which bind the pigments together usually a catalyzed cross linking mechanism with a polyisocyanate hardener providing a cheap resistant coating. |
|
Polyvinyl Alcohol |
o It gives greater strength to yarn
o It is used to make fabric more resistance to oil & greases |
| Dye Fixative | o Uses to prevent dye bleeding into the white areas |
| Scouring Agent | o Eleminating hydrophobic impurities without deteriorating fabric itself |
| NaOH | o Uses to maintain the pH level |
| Synthetic Dye | o It provides long lasting color effect |
| Sodium Bisulphite | o Use as a disinfectant or bleaching agent |
| Ethylene Diamine (EDTA) | o Prevents metal ion impurities from modifying colors of dyed product. |
| Silicon Defoamer | o Using to remove existing foam from fabric. |
| Ammonia | o Use to increase pH level |
| Potassium Persulphate | o Used as disinfectant and fabric bleach |
In Sizing for weaving stage following chemicals are used-
| Chemical Name | Function |
| Lubricating Agent | o Use to remove crease mark, wrinkle mark |
| Polyvinyl Alcohol | o Use to make fabric resistant to oil & grease |
| Polyacrylates | o Used as a thickening agent because of its unique ability to absorb & hold onto water molecule |
| Modified Polyester | o Used to control shrinkage, wrinkle |
| Anti-Back Staining Agent | o It is an effective washing off agent to remove back stain from processed denim |
In Rinse wash and desinzing following chemicals are used-
| Chemical Name | Function |
| Amylase Enzyme | o It gives denim a softer & worn in look |
| Silicon Softener | o Use to improve the strength of fiber & reduce abrasion |
| Resins | o It makes the fabric more stiffer, harsh & abrasive & increase durability |
| Acetic Acid | o Control pH value |
| Detergent | o Help fabric hold onto dyes & deactive chlorine in the water that can fade colors |
| Sodium Hypochlorite | o It is used when the indigo’s color needs to be lightened as required by fashion |
| HCL | o It is used to remove stubborn stains & debris |
| Acrylic Resins | o It is used to increase abrasion resistance & anti pilling effect |
In wet fades and finishing stage following chemicals are used-
| Chemical Name | Function |
| Silica | o Creates a precise breached look |
| Sodium Hypochlorite | o Clean up the pocket linen & inner face of the jeans |
| Potassium Permanganate | o Used to increase bright effect in sandblast area |
| NaOH | o Remove impurities |
| Polyurethanic Resins | o Increase dimentional stability & anti-creasing effect |
| Acrylic Resins | o It is used to increase abrasion resistance & anti pilling effect |
