Leveling agents chemistry and Performance

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Leveling agents: chemistry and
performance
Prof S.K. Laga, Miss Rashmi Joshi.M and Mr. Vignesh Dhanabalan
D.K.T.E.S Textile & Engineering Institute, Ichalkaranji-416115(M.H), India.
E-mail: swapan.laga@gmail.com , vigneshdhanabalan@hotmail.com,
Issue » February, 2014 Volume 07, Issue 02 Print this News
Abstract
The appeal (comfort) of the fabric material is a main parameter that decides the
market flow of the product. To bring in complicated design and trendy material,
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shade variations have always been a hurdle. It remains so as, the dye uptake and
fixation and of the dye material is random. Leveling agent are chemical agents
that work on the dye molecule and help in fixing the dye particles uniformly. In
this paper we have made efforts to share the knowledge on what leveling agents
and dispersing agents are, the necessity of leveling agent, different classes of
leveling agent, their testing methods and some means of synthesizing leveling
agents for industry and laboratory use.
Keywords: Colloidal particle, color tone, dispersing agent, dye uptake, leveling
agents.
Introduction
Dyeing and printing are processes of imparting color onto the substrate. This
imparting of color is done by use of wet and dry processing techniques. In wet
processing, substrate comes in contact with the dye solution and coloring takes
place. Due to various reasons like surface tension, unevenness, capillary action,
polar component and other parameters, the uniform dyeing gets affected. To
yield color in wet processing in a better manner, chemical Auxiliaries are used.
One such kind is leveling agent and the other is dispersing agent. Dispersing
agents are substances that promote the more or less uniform and stable
suspension of relatively small particle in a given matrix. The function of
dispersing agent is to prevent agglomeration of individual dye particle during
dyeing. They play a subsidiary role in dispersion involving in textile coloration.
Dispersing agents are much preferred for Vat dyeing, Disperse dye and pigment
padding. The anionic product ionizes water and form an electrical double layer.
The mutual repulsion between these groups keep dye particle apart and prevent
agglomeration
Many fabrics during dyeing have high initial dye uptake causing unevenness or
shade variation. Leveling agents are added to the dye bath to regulate the
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process of dyeing to obtain uniform shade throughout the substrate. Leveling
agents are soluble in water but, the solubility reduces with increase in
temperature and finally becomes insoluble after a temperature called as the
cloud point. On selection of leveling agent the cloud point temperature of the
leveling agent is an important parameter.
Level dyeing can be broadly classified into two categories
Gross unlevelness throughout the material : The substrate is uniform
throughout both physically and chemically
Localized unlevelness: Non uniformity of substrate (either wise).
Unlevelness, bareness or patchy dyeing occurs during dyeing due to
deformity in fibre/yarn, fabric structure,
Improper dyeing process or condition,
Improper selection of dyestuffs for dyeing.
Difference between leveling and dispersing agent:
Dispersing agents are known to improve the migration and leveling of disperse
dye on polyester during HT dyeing.
Leveling agent tend to slow down the dye uptake of the fibers helping to produce
more uniform color in the textile fiber. They are also termed as retarding agents
or retarders. The use of retarders is essential in situation in which dye tends to
rush on to the fiber and results in unevenly colored textile material. Leveling
agents are surface active agents and are chemically related to soaps, synthetic
detergents and wetting agents. They may be anionic, cationic or non-ionic
organic compounds.
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Effect of leveling agents:
Specific leveling agents, that can be either no-ionic or anionic surfactants or
compounds, increase the solubility of the dye, thereby lowering the initial strike
and overall rate of the dye uptake which can also cause a restraining effect
resulting in a loss of color yield. The solubility of the leveling agent decreases
with increasing temperature, and if, the temperature of the bath increases above
the cloud point of the agent then the dye dispersion takes place resulting in dye
aggregation and attendant of unlevel dyeing.
Herlinger et al proposed that at concentration above CMC, non-ionic agents
lower the dye uptake owing to a corresponding increase in solubility of the dye,
this reduction increases with increase in solubility of the dye. Anionic agents
increase the cloud point of the non-ionic leveling agents. Careful consideration
must be given to the amount of non-ionic leveling agent used owing to the often
marked restraining effect exerted by the compound on dye uptake. [1-3]
Table 1: Commercially available leveling agents
Trade Name Nature Manufacturer
Supersol VL Super
Chem.
Non-ionic (for PET, vat dyes)
Dispersol K paste Anionic ICI, India
Deterzol D Paste Anionic fatty alcohol
sulphate
Associated Enterprise
Dispersol VLH Non-ionic ICI, India
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Archive Issues
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2013 2014 2015

Lyogen DK Wool, Silk and Nylon Sandoz (I)
Lyogen SMK For wool, silk, nylon Sandoz (I)
Tenegal CVN (liquid) Anionic Suhred Geigy Co.
Polylevel SG Non-ionic (for wool) Suhred Geigy Co.
Tenegal CVN (liquid) Anionic (for nylon) Suhred Geigy Co.
Lyogen DFT Non-ionic for PET &
blends
Sandoz (I)
Types (or) classification of leveling agents:
Leveling agents are classified into two main groups based on ionization and
structure wise
1. According to the ionic nature
Anionic
Cationic
Non-ionic [used for PET dyes]
Anionic agent:
The molecules of these compounds consist of largely negative charged or anionic
organic radical. When anionic agents are added to the dye liquor, the anionic
agents will be attracted to any positive sites of the fiber. The anionic agents try to
repel similarly charged anionic dye molecules. As the bath is heated the
molecules develop sufficient energy to overcome the repulsive forces between

the retarder and the dye. These anionic agents tend to give more uniform dye
uptake of the fiber.
Cationic agents:
The molecules of these compounds consist of largely positively charged or
cationic organic radical. When cationic agents are added to the dye liquor, their
captions are attracted to the anionic dye molecule. This neutralizes the electrical
charge of the dye molecule and minimizes the substantively of the fibers. The
energy provided by heating cause the cationic radicals of the leveling agent to
gradually dissociate of the cationic agent from the anionic dye molecule slowly
releases the dye and ensures a more uniform absorption of the polymer system
of the fiber.
Anionic Leveling agents -> silk, wool, nylon, Bast.
Cationic leveling agents -> wool, silk, acrylic, nylon, cellulosic
Non-ionic -> synthetics & blends
2. According to the chemical structure
Fatty Acid (Ethylene Urea)
Fatty alcohol (Sulphates)
Sulphated (Fatty amine)
Alkyl aryl (Sulphonates)
Fatty alcohol ethylene (oxide condensate)
Mechanism of functioning of leveling agents:
The two fundamental mechanisms that contribute to level dyeing are
Control of exhaustion of dye so that it is taken up evenly

Migration of dye after initial unlevel sorption on the fiber.
The attractive force between agent and dye create a counter balancing
mechanism against fiber-dye attractive forces, restraining the uptake of the dye
by the fiber. As the temperature increases the complex gradually breaks down,
progressively releasing the dye for more gradual sorption by the fiber, this
clearly shows leveling agent working by this mechanism that rely on the
attractive force between the fiber and the dye particle but, similarly strong force
of attraction may result in a complex that is difficult to break down.
Leveling agent (a) allows the dye to get in to the fiber regardless of initial
Unevenness. During the course of further dyeing levelness is achieved through
migration. For this selection of dyes for dyeing is of utmost importance or (b) it
controls/retards the rate of dyeing throughout the dyeing cycle. Sometimes the
leveling agent acts in both the ways.
Some mechanisms are stated below:
Non-ionic leveling agents are used in direct dyeing. They promote leveling by
breaking the dye aggregates that migrate slowly.
The action of a non-ionic surfactant in reducing the uptake of dye by wool
and silk is based on the formation of a complex between the dye and the
surfactant; it reduces the effective concentration of dye, i.e. the complex acts
as a reservoir from which dye is gradually released on heating owing to
decomposition of the complex.
Leveling agent selected for vat dyeing must give the required initial
retardation without a significant loss in color yield. Leuco vat dyes have
greater affinity to absorption, which causes unlevel dyeing. The two most
widely used types of Leveling agents for Vat dyes are cationic active
surfactants and non-ionic ethylene oxide condensate. The cation active
products compete with the leuco vat dye for available sites in the fibre and

thus retard the dyeing process. The retarder-dye complex acts as a reservoir
for the leuco vat dye preventing from dye rushing to the fibre in the initial
stages. The complex breaks so that, the dye is slowly released during the
later stage of dyeing.
In case of dyeing nylon with 1:2 metal complex dye, due to poor migration of
dyes unlevel dyeing is obtained. Non-ionic Leveling agents have affinity for
these dyes hence; they retard the exhaustion and produce level dyeing.
If a mixture of mono-sulphonic and trisulphonic acid is used in dyeing of
nylon to produce compound shades, the mono sulphonic acid dye will be
first taken by the fibre and will turn black for the polysulphonic dye. Here,
anionic Leveling agents will complete with monosulphonic acid dyes for
available sites in the fiber and thus it will minimize the blocking effect and
produce level dyeing.
Table 2: Use of leveling agents based on ion type
Ion type Fiber type Dye
Non-Ionic/Anionic Cotton, Wool,
Nylon, Polyester
Azoic, Vat, Direct
milling, Metal Complex,
Disperse
Nonionic/Cationic Wool, Nylon,
Polyester
Direct milling, Metal
Complex, Disperse
Anionic Wool Acid, Mordant, Metal
Complex, Reactant
Weakly Anionic Cotton, Wool,
Nylon, Polyester
Acid, Direct, Disperse

Anionic/Cationic Polyester Acid, Metal-Complex
Cationic Wool, Nylon, Basic, Acid, Metal-
Complex, Reactive
Weakly cationic Acrylic, Wool,
Nylon,
Acid, Mordant, Metal-
Complex
Cationic/Polymeric Cotton Vat, Sulphur
Amphoteric Wool Acid, Mordrant, Metal-
Complex, Reactive
Testing method for evaluation of efficiency of leveling agent:
(a) By Performance Test
Carry out separate dyeing with and without pressure of leveling agent with blue
dyes (which would be easier to plot the blot marks). Then, compare the levelness
of both the samples. Choose any class of blue dye having poor Leveling
properties.
Concentration of Leveling agent = Max. 5 gpl.
Fig 1: optimum concentration to exhaustion rate
Higher the concentration higher will be leveling effect but after certain level the
attraction force becomes very high that it is difficult to break down. By
incorporating certain chemicals in the dyeing liquor we can overcome one or

more causes of non-uniformity.
(b) By determining active content
To determine the active content of the material prepare a solution of 20 ml
Leveling agent sample in 100 ml graduated measuring cylinder and add 20 ml 2
N sulfuric acid to it. Place the measuring cylinder in water bath at 60 0C for 2 hrs
and then cool it. Observe the height of the oil layer after cooling.
The active content can be calculated using the following relationship
V2
Active Content = ———— x 100 %
V1
Where, V1 = Volume of Sample taken.
V2 = Volume of Oil Layer.
(c) By determining the strike percentage
The Strike (S) is defined as the color on 1 min sample expressed as % of the color
on the one hour sample.
To determine the strike percentagePrepare a small fabric sample measuring 2 x
2 cm and another large fabric sample measuring 10 cm x 10 cm and a solution of
(0.1 %) Foron Blue SE2RI 200%.
Prepare the dye-bath using the above dye solution keeping material to liquor
ratio 1: 50 and add 2 gm/liter leveling agent to this dye-bath. Dip the sample in
the dye bath and increase the temperature to 80 0C. Remove small sample after
one minute and the large sample after an hour. Measure the reflectance for both
the using spectrophotometer.

To calculate the strike % using the following relationship
( R0 – R1 )
S = —————– x 100
( R0 – R60 )
Where, R0 = Total reflectance on undyed sample, R1 = Total reflectance on 1 min
sample.
R60 = Total reflectance on 60 min sample.
Efficiency of leveling agent:
Table 3: Test results conducted by ATIRA on different grades of dye with varying
concentrations of leveling agent
Trials were conducted by ATIRA to determine the effect of dye absorption by
leveling agent. Various dyes were used at concentrations between 0.5 to 2.0 g/l of
water and concentrations of leveling agents at 0.25, 0.5, 1.0, 1.5, 2.0 g/l. Dyed
material without use of leveling agent were kept as 100% and the test was
conducted, it was found that leveling agents gave good distribution results up to
0.5 g/l followed by depreciation in the color yield. This loss in effect may be due
to more energy required to break the attraction force between the fiber-dye
solutions.
Root causes for uneven / unlevel dyeing:
Improper dye dissolution.
Too much affinity of dye towards substrate.

Role of leveling agent in dyeing:
The leveling agent will compete with the dyes having affinity towards substrate.
HLB value of leveling agent is higher than that of dispersing agent. For Synthetic
and its blends, generally non-ionic leveling agents are used that can withstand
higher temp of dyeing, Say 1300C. These are the condensates of ethylene oxide
and higher fatty alcohol, fatty amines.
General Preparation of Leveling Agents
The category of chemical used for preparation of leveling agent has been shown
below with an example is illustrated below
Example
Fatty alcohol Sulphates :
Lauryl alcohol and oleum on sulphation at 1.5 atm. pressure. The Sulphated
product is further alkali fused. The product is chemically identical to commercial
product (Gardinal WA). It can be used as leveling agent for dyeing nylon with acid
dyes.
Sulphated fatty amines:

The final product has same chemical composition as the commercial product
EMCOL. It can be used for dyeing of wool, silk with acid colors.
Fatty acid ethylene Urea Product :
General prepration
Example
The final product has same chemical composition as the commercial product
Lyogen SMK. It is used for dyeing of wool with neutral acid dyes.
Alkyl naphthalene Sulphonate :
The final product is a non-ionic alkyl naphthalene sulphonate which has
chemical components similar to Lyogen DFT used as leveling agent in disperses
dyeing.
Commercial Method for preparation of Alkyl naphthalene Sulphonate
In industry first sulphonation is carried out. Then, methylation is done and lastly
alkali fusion.
First step (1600C / 1-2 hrs.) with
Naphthalene = 190 – 200 kg.

98% H2SO4 = 1900 – 2000 liters.
2nd Step: Methylation (80 – 85°C temp. for a period of 18 – 24 hrs.) with
37 – 41% formaldehyde soln. / formalin.
990 kg of formalin
1000 – 1100 lts of water
3rd Step: Alkali fusion [NaOH / Na2CO3] with
NaOH = 0.7 kg [48%] i.e. Caustic lye.
NaCO3 = 1.5 to 1.6 kg.
And then final product is achieved.
In the preparation of Alkyl naphthalene Sulphonate solution 2:1 mole ratio of
naphthalene and HCOH is taken and methylation is carried around 80-85ºC,
followed by sulphonation in the presence of 98% H2SO4 at around 160-170ºC
which is followed by alkali fusion.
Impact of leveling agent on physical properties of the substrate
Leveling agents have no effect on physical properties of the substrate as they do
not interact with the textile fiber. They have profound effect on the dye molecule
only.
Method of removing leveling agent
Generally leveling agents are removed simply by boating with 2-3 gpl NaOH and
2-5 gpl of sodium hydrosulphate at 80-85ºC for 30 min followed by hot wash and
cold wash.

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Limitation of leveling agent:
Depth of the shade is reduced by 10 to 15%. Therefore, in case of Leveling agent
add 10 to 15% more dye from the recipe.
Bibliography
1. K.A.Thakor, N.C shah and R.M Mittal, Amer, Dyest.Rep., 76(9) 58, 1987.
2. A.Murry and K.Mortimer, JSDC, 87, 1971.
3. D.Fiebig and H.Herlinger, Text. Prax, Int, 38,785,1983.
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