Application of nonionic surfactant in colorants

Vinay BhayaRoll no.16Final Year (Dyes)

Based on the charge on hydrophilic groups, surfactants can be classified into four categories

1. Non Ionic - No charge on the hydrophile2. Anionic - Negative charge on the hydrophile3. Cationic - Positive charge on the hydrophile4. Zwitterionic - positive & negative charges present in the

same molecule.

Main role of surfactant used in dyeing auxiliary product can be classified into 3 types of actions

1. Dye leveling / Retarding agent

2. Surface active compoundsSolubilizingDispersingWetting.

3. Azoic fastness improvers

Levelness

Unlevelness

Main mechanisms of levelling agents

Nonionic surfactants Usually form water-soluble complexes with the dye, some

degree of solubilisation being involved Ionic agents

Dye-substantive Form complexes with the dye and there is competition

between the levelling agent and the fibre for the dye Fibre-substantive

competition between levelling agent and the dye for the fibre

Representation of solubilised acid dye-agent complex

Mechanism of levelling for acid dyes

Dye-SO3-

C

O

N

H

N+H3

Dye-SO3-

C

O

N

H

N+H3

Levelling-SO3-

C

O

N

H

N+H3

Levelling-SO3-

C

O

N

H

N+H3

Dye-SO3-

Levelling-N+R4

Dye-SO3-

Levelling-N+R4

Dye-SO3-

C

O

N

H

N+H3

Dye-SO3-Levelling-SO3

-

Nylon

1. Complex dye-levelling

2. Competitive ionic levelling

Splitting out

Splitting out

Levelling agent for disperse dyes

• Non-ionic levelling agent tend to be separated at high temperature but can increase dyes solubilisation (Low cloud point)

• Anionic levelling agent can increase the cloud point of nonionic agent

• Should synergistic mixing together• 7-10% of B in A can increase cloud point of A alone

(105oC) to 150oC• Fully effective at pH >7 (Carefully selection of dyes)

(A) fatty acid ethoxylate (B) sodiumdodecylbenzenesulphonate

Levelling agent for disperse dyes

• Modified nonionic (or Modified anionic, Weakly anionic)– Phosphate ester ethoxylation• High temperature stability• Protect hardness and trace metal ion• Stabilise under high concentration of electrolyte• Fully effective at pH 4-5 (pH of disperse dyeing)

Levelling agent for Vat dyes

• Leuco form have high affinity for cellulosic fibre• They dye fibre at high rate• Thus production of even shades becomes difficult

Methods to control rate of dyeing

1. Nonionic surfactants competing with dye for fibre sites2. Surfactants combining with dye to form loose complexes

(These are not adsorbed on the fibre)

Note : Quantities in excess of the recommended quantities should not be added, otherwise they may lead to greater restraining action & hence to permanent loss of colour value

Nonionic - Surfactants to be used for vat dyes

Dispersol VL (ICI)Dispersal (Royce Chemical Co.)Berol EGA-07 (Aktiebolaget Berol-Produketer)Emullant CO 18 (Union Chemique Belge)Emullant CO 25 (Union Chemique Belge)

Azoic Fastness Improver

naphthol (alk. sol.)+ diazotised base = azoic colorants

Some of the naphthol drains into the external bath and forms azoic pigment

This gets deposited on the fibre creating rubbing fastness problems

Solution to this problem

When dispersing agent (Cetyl Alcohol-Ethylene oxide) is added, the azoic pigment forms a dispersion, which does not deposit on the fibre

Dispersing agent also stabilises the diazotised base (inhibits the decomposition of the base before coupling) resulting in better utilization of the base

NOTE : The nonionic surfactant may be used to the extent of 2 g/l in the developing bath

Role of nonionic surfactant in Paints

Dispersion of pigment particles (mainly in water)

Stabilization of formulated product without any separation during storage

Dispersion of pigment material

Pigments particles are inorganic materials with hydrophobic surfaces

Pigments do not mix with water unless surfactant is added

Surfactant gets adsorbed at the interface of solid and water & carries out wetting of the powder material.

Stabilization is critical for the product to survive onthe shelf

Stabilization is achieved by creation of a barrier

Potential Energy curve

Thus for effective dispersion & stabilization ,the following types of nonionic surfactants can be used

1.Ethoxylated alkyl phenols (Tergitol 15 S series)

2.Ethoxylated alcohols (Berol 185)

3.Fatty esters of polyols

REFERENCES

1. Nonionic Surfactants: Physical Chemistry, edited by Martin J. Schick

2. Handbook of detergents, Martin Schick, chapter no. 173. Surfactants in textile processing, Arved datyner, chhapter

no.104. Nonionic Surfactants: Chemical Analysis, edited by John

Cross5. Dye-Surfactant Interactions and Their Applications,

ERMANNO BARNI,1991, vol 98-103, p 216. The Interaction between Dyes and Nonionic Surfactants:

the Mode of Action of Nonionic Surfactants in Dyeing, Yoshio Nemoto, 71, 364, (1979)