FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
AND
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION (See section 10; rule 13)
TITLE OF THE INVENTION “Method for distinguishing between different grades of Carbon Black“
APPLICANT
CEAT LIMITED of RPG HOUSE, 463, Dr. Annie Besant Road,
Worli, Mumbai 400 030, India;
Nationality: India
INVENTORS SANDIP PANDYA, GAURANG PARIKH AND SUJITH NAIR
of Research & Development Department, CEAT Limited, At
Getmuvala, Chandrapura [P.O.], Halol,
Vadodara-389350, Gujarat, India.
All are Indian Nationals
PREAMBLE TO THE DESCRIPTION
The following specification particularly describes the invention and the manner in which it is to be performed

FIELD OF THE INVENTION
The present invention relates to the method of determining and differentiating between different grades of Carbon black employing the light scattering technique. The process of present invention is simple, efficient and accurate vis-à-vis the conventional methods known in the state of art.
BACKGROUND OF THE INVENTION
Carbon black is a material of great industrial importance. It is formed by the incomplete combustion of certain fuels containing carbon. One of its major uses is to strengthen rubber tires. It is carbon black that gives tires their black color. It is also used to make black ink and black pigments, and toners for copy machines and printers. Every application of carbon black requires control of its particle size distribution. For example, tires require larger particle sizes than pigments and inks. To control the particle size distribution requires first being able to measure it. Carbon black particles are particularly difficult to measure because they are very small. A typical carbon black sample contains particles in the range of 40 manometers (nm) to one micrometer (μm) in diameter.
The standard method of measuring the particle size distribution of carbon black is using a transmission electron microscope (TEM) with an automated image analyzer. The particles are too small to be measured using an optical microscope. The procedure for using the TEM is very difficult and time-consuming to perform, and easier and faster methods have been tried.
Centrifugal sedimentation has been used, but the parameter that is measured, Stokes diameter, is not a good representation of particle size. A non-spherical particle can be measured to have a wide range of Stokes diameters. The orientation of the particle with respect to its direction of travel affects the measured Stokes diameter.

A need exists, therefore, for a simple and efficient method of determining and
differentiating between different grades of carbon black that will eliminate or
ameliorate the difficulties described above.
The present invention therefore provides for a simple, low-cost and easy method
for determination of different grades of carbon black employing the light scattering
technique.
OBJECT OF THE PRESENT INVENTION
The present invention has been accomplished in light of the above-mentioned
situation. An object of the present invention is to provide a method for determining
the particle size, particle size distribution and surface area of different carbon black
grades employing the light scattering technique.
It is an object of the present invention to distinguish between different grades of
carbon black in a more efficient, safe and economic way.
It is a further object of the present invention to achieve the aforesaid objectives
without compromising on the accuracy and precision of the determination.
It is yet another object of the present invention to simplify and accelerate the
process of testing to less than 1 minute.
It is a further objection of the present invention that no cryogen gas be used to
measure the particle size of carbon black.
It is another object of the present invention to provide a dynamic light scattering
method for characterizing the different grades of carbon black.
SUMMARY OF THE INVENTION
The process for the present invention is directed to differentiating carbon black grade comprising steps of:
(a) Preparing 0.1% surfactant solution in water;

(b) Dispersing carbon black in the surfactant solution of step (a) by sonication at 40kHz for 1-3 minutes;
(c) Dispersing the mixture of step (b) further by sonication at 80-140kHz for 7 minutes;
(d) Subjecting the sonicated mixture of step (c) to light scattering technique at a transmission level of upper 90% and lower level 70% to distinguish between the different grades of carbon black.
According to one embodiment of the invention, the process does not employ cryogen gas to measure the particle size.
The average particle diameter (D50) of the carbon black measured by dynamic light scattering method of the present process is about 10 nm to 60 nm.
DETAILED DESCRIPTION OF THE INVENTION
In describing and claiming the invention, the following terminology will be used in accordance with the definitions set forth below. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, the preferred methods and materials are described herein. As used herein, each of the following terms has the meaning associated with it in this section. Specific and preferred values listed below for individual components, substituents, and ranges are for illustration only; they do not exclude other defined values or other values within defined ranges for the components and substituents.
As used herein, the singular forms "a," "an," and "the" include plural reference unless the context clearly dictates otherwise.
As used herein, the terms “include”, “includes” and “including” are meant to be non-limiting.

References herein to “one embodiment”, “one aspect” or “one version” of the invention include one or more such embodiment, aspect or version, unless the context clearly dictates otherwise.
The use of numerical values in the various ranges specified in this application, unless expressly indicated otherwise, are stated as approximations as though the minimum and maximum values within the stated ranges were both preceded by the word "about". Thus, slight variations above and below the stated ranges can be used to achieve substantially the same results as values within the ranges. Moreover, in the disclosure of these ranges, a continuous range is intended, covering every value between the minimum and maximum values, including the minimum and maximum end points of the range.
The terms “preferred” and “preferably” refer to embodiments of the invention that may afford certain benefits, under certain circumstances. However, other embodiments may also be preferred, under the same or other circumstances. Furthermore, the recitation of one or more preferred embodiments does not imply that other embodiments are not useful, and is not intended to exclude other embodiments from the scope of the invention.
The process for the present invention is directed to differentiating carbon black grade comprising steps of:
(a) Preparing 0.1% surfactant solution in water;
(b) Dispersing carbon black in the surfactant solution of step (a) by sonication at 40kHz for 1-3 minutes;
(c) Dispersing the mixture of step (b) further by sonication at 80-140kHz for 7 minutes;
(d) Subjecting the sonicated mixture of step (c) to light scattering technique at a transmission level of upper 90% and lower level 70% to distinguish between the different grades of carbon black.
Preferably, the carbon black dispersion for sonication is prepared by dispersing the carbon black sample in a dispersant selected from a non-ionic surfactant made from sorbinate and lauric acid by an ethoxylation process.

The sample of carbon black employed in the present invention is particularly
limited. Examples of such samples of carbon black include various grades of N110,
N220, N330, N550 and/or N660 in ASTM number.
The amount of carbon black dispersed is about 5 ± 1 mg.
The average particle size of the carbon black aggregates finally present in the
dispersion subsequent to sonication is about 10- 60 nm.
The present invention employs light scattering method in lieu of centrifugal
sedimentation method or analysis through transmission electron microscopy (TEM)
methods.
According to one aspect of the present invention, there is provided a dynamic light
scattering apparatus and a method by which the sample of carbon black prepared in
accordance to a method described in the present invention is illuminated by two
type of light one is solid state led and second is solid state laser diode of different
wavelengths and the fluctuations of the light scattered by the sample at each
wavelength is detected.
The light sources may be lasers producing light at various wavelengths, collimated
conventional lights sources emitting light at single or multiple wavelengths, light
emitting diodes or uv light.
The wavelength of the light ray employed in the light scattering method is not
limited in particular and may be selected appropriately in accordance to the particle
size distribution of the sample
The invention is further illustrated in the Examples section which follows. This
section is set forth to aid in an understanding of the invention but is not intended to,
and should not be construed to, limit in any way the invention as set forth in the
claims which follow thereafter.
EXAMPLE 1
1. The particle size analyzer (PSA) was switched on and allowed to stabilize for a minimum of 15 minutes

2. The PSA tank was filled with 12 ml of DM water and circulation speed of 1000-1200 rpm was started.
3. Sonication was performed to remove air bubble from line of PSA machine for 0.2 minutes.
4. Alignment of laser was performed with respect to sample cell and the blank run of water.
5. 0.1% of surfactant solution made from sorbinate and lauric acide by ethoxylation process was prepared in water.
6. The representative sample of carbon black was taken in a glass beaker with a weight accuracy of 10 ± 0.1 mg to which was added 20 ml of 0.1% surfactant solution.
7. The mixture was sonicated at 40 kHz frequency for 3 minutes.
8. the solution was transferred drop wise immediately in PSA machine until transmission level is between 90%-70%.
9. The sample was further sonicated at a frequency range of 80 – 140 KHz for minimum 7 and maximum 9 minutes which resulted in breaking of agglomeration between carbon black particles.
10. After sonication the particle size of dispersed carbon black was measured using particle size analyzer.

11. After completion of experiment, the software automatically provided the value of D(50),D(70),D90. The sample is dispersed in a particle size range of 10 nm to 60 nm for grade analysis through light scattering technique.
Parameter of particle size analyzer
a) % Transmission level : Upper 90% and Lower level 70%
b) Sample : carbon Black RI 1.92-0.522i
c) Dispersion Medium : water RI 1.33
d) Feed Liquid Level : 70 ml
e) Circulation Speed : 1000-1200 rpm
f) Ultra sound Time : 7 min (Before measurement)
g) Ultra sound During Measurement : No
h) Agitation Speed : 0
In a laser diffraction measurement a laser beam passes through a dispersed
particulate
sample and the angular variation in intensity of the scattered light is measured.
Large
particles scatter light at small angles relative to the laser beam and small particles
scatter
light at large angles. The angular scattering intensity data is then analyzed to
calculate the size of the particles that created the scattering pattern using the Mie
theory of light scattering. The particle size is reported as a volume equivalent
sphere diameter.
Table 1: Particle size of different grades carbon black using light scattering technique


Table 2: Particle size of raw carbon black grade of different suppliers & different lots.

CARBON BLACK GRADE D50 D70 D90

Supplier A Supplier B Supplier A Supplier B Supplier A Supplier B

Lot 1 Lot 2 Lot 1 Lot 2 0.31 0.34 0.18 0.37 0.26 Lot 1 Lot 2 Lot 1 Lot 2 0.37 0.43 0.22 0.53 0.35 Lot 1 Lot 2
0.5 0.63 0.34 1.19 0.58 Lot
1
0.5 0.62 0.34 1.21
0.6 Lot 2
0.5 0.63 0.34 1.21 0.62
N110 0.31 0.31 0.31
0.37 0.37 0.37
0.5

N220 0.34 0.34 0.34
0.42 0.42 0.42
0.63

N330 0.18 0.18 0.19
0.22 0.22 0.23
0.34

N550 0.39 0.38 0.39
0.54 0.52 0.52
1.2

N660 0.26 0.26 0.26
0.35 0.36 0.35
0.6

Inference:
Table 1 clearly shows that combination of D50, D70 and D90 values are distinct for each of grade of Carbon black. Hence, employing the combined reading of the D50, D70 and D90 values one can easily differentiate a different grade of carbon black. For Table 1 & 2 standard deviation between two runs is <1% which clearly indicate that the repeatability of the method is excellent irrespective of supplier or lot/batch. The method of present invention clearly enables one to differentiate carbon black grades employing the light scattering technique based on the tabulated D50, D70 and D90 values of carbon black from below table.

Carbon black grade D50 D70 D90
N110 0.31 (±0.02) 0.36 (±.03) 0.5 (±.03)
N220 0.34 (±0.02) 0.42 (±.03) 0.6 (±.03)
N330 0.18 (±0.02) 0.22(±.03) 0.32(±.03)
N550 0.38(±0.02) 0.54(±.03) 1.2(±.03)
N660 0.26(±0.02) 0.35(±.03) 0.6(±.03)
While the invention has been described above with respect to certain particular embodiments thereof, numerous other forms and modifications will be apparent to those skilled in the art. The appended claims and the invention generally should be

construed as covering all such obvious forms and modifications that are within the true spirit and scope of the invention.
It will thus be seen that the objects set forth above, among those made apparent from the preceding description are efficiently attained and since certain changes may be made in the above construction without departing from the scope of the invention, it is intended that all matter contained in the above description shall be interpreted as illustrative and not in a limiting sense.

We claim:
1. A process for differentiating carbon black grade comprising steps of:
(e) Preparing 0.1% surfactant solution in water;
(f) Dispersing carbon black in the surfactant solution of step (a) by sonication at 40kHz for 1-3 minutes;
(g) Dispersing the mixture of step (b) further by sonication at 80-140kHz for 7 minutes;
(h) Subjecting the sonicated mixture of step (c) to light scattering technique at a transmission level of upper 90% and lower level 70% to distinguish between the different grades of carbon black.
2. The process as claimed in claim 1, wherein the surfactant is a non-ionic surfactant made from sorbinate and lauric acide by ethoxylation process.
3. The process as claimed in claim 1, wherein average particle size of the carbon black aggregates finally present in the dispersion subsequent to sonication is about 10- 60 nm.
4. The process as claimed in claim 1 wherein the carbon black samples include various grades of N110, N220, N330, N550 and/or N660 in ASTM number.
5. The process according to any of the preceding claims wherein the D50, D70 and D90 values of Carbon black grade N110 is 0.31 (±0.02), 0.36 (±.03) and 0.5 (±.03) respectively.
6. The process according to any of the preceding claims wherein the D50, D70 and D90 values of Carbon black grade N220 is 0.34 (±0.02), 0.42 (±.03) and 0.6 (±.03) respectively.

7. The process according to any of the preceding claims wherein the D50, D70 and D90 values of Carbon black grade N330 is 0.18 (±0.02), 0.22 (±.03) and 0.32 (±.03) respectively.
8. The process according to any of the preceding claims wherein the D50, D70 and D90 values of Carbon black grade N550 is 0.38 (±0.02), 0.54 (±.03) and 1.2 (±.03) respectively.
9. The process according to any of the preceding claims wherein the D50, D70 and D90 values of Carbon black grade N660 is 0.26 (±0.02), 0.35 (±.03) and 0.6 (±.03) respectively.