Dye- Fibres interaction bonds:

For dye-fibre interaction it is needed that dye has to be substantive (attraction) to the fibre to be dyed. This affinity will enable the dye to be absorbed by the fibre.There are quite a few factors that affect the substantivity of a dye. Among them are the ability of the dye to form strong or weak bonds (e.g ionic and/or hydrogen bonds and /or Van der Waals forces) with the fibre, its polarity, and its size and shape. The rule of thumb that states: ‘Like dissolve like’,  can give us some indication of the expected substantivity.

Attraction forces between dye and fibre: Following are the four attraction forces:

• Van Der Waals forces
• Hydrogen Bond
• Electrostatic attraction
• Co-valent Bond

Van der Waals Forces:

The van der Waals force, named after Dutch scientist Johannes Diderik van der Waals, is the sum of the attractive or repulsive forces between molecules (or between parts of the same molecule) other than those due to covalent bonds, or the electrostatic interaction of ions with one another, with neutral molecules, or with charged molecules. The term includes:

• force between two permanent dipoles 
• force between a permanent dipole and a corresponding induced dipole
• force between two instantaneously induced dipoles (London dispersion force).

Hydrogen Bond:

A hydrogen bond is the attractive force between the hydrogen attached to an electronegative atom of one molecule and an electronegative atom of a different molecule. Usually the electronegative atom is oxygen, nitrogen, or fluorine, which has a partial negative charge.

Covalent Bond:

A covalent bond is a chemical bond that involves the sharing of electron pairs       between atoms. The stable balance of attractive and repulsive forces between         atoms when they share electrons is known as covalent bonding.

Electrostatic attraction/repulsion

Electrostatic attraction is the phenomenon where a negatively charged atom or       molecule is attracted to a positively charged atom or molecule. Electrostatic           repulsion occurs between two atoms of the same charge.

                    

Dye class	Force of attraction
Direct, Vat, Sulphur, Solublized Vat (with Cellulose fibres)	Vander Wall, H-Bond
Reactive with cellulose fibres	Co-Valent Bond
Direct, Acid, Metal Complex with Wool, Silk and Nylon	Ionic or electrostatic
Reactive with Wool, Silk and Nylon	Ionic/Covalent
Disperse with polyester	VanderWaal, H-bond
Cationic with Acrylic	Ionic or Electrostatic