Introduction in the Field of Invention:
This invention relates to method of preparation of regenerative type synthetic/semi-
synthetic rolling oil for cold rolling of thin gauge sheet of steel and its formulation.
Prior Art and Drawbacks:
Cold rolling operation involves gauge reduction of hot rolled strip by passing it through a set
of rolls under load. Cold rolling oil is mainly used for lubrication and cooling during cold
rolling operation. In general, a cold rolling lubrication system uses oils in form of oil-in-
water emulsion. This emulsion is applied at the roll bite; used emulsion is then filtered for
various contaminants and then re-circulated in the same system for continuous usage over
a protracted period of time. In cases where the cold rolling mill is not equipped with re-
circulation type emulsion system, used oil is regenerated for its further use.
It is already known to prepare dispersion type cold rolling oil for steel cold rolling mills.
However, it was not known to prepare synthetic/semi-synthetic dispersion type oil with
regeneration property.
The cold rolling oil dispersion has to meet various requirements like optimum lubricity, high
cooling efficiency, optimum emulsion stability, high cleanliness etc. For a cold rolling mill,
which is having recuperative type emulsion system to regenerate the used oil for higher
techno-economics, the rolling oil should have good regeneration property.
Though, the presently available dispersion/emulsion type rolling oils comprising
fats/synthetic organic esters, Extreme pressure(EP) / Anti-wear(AW) additives, detergent
/emulsifier etc., can meet most of the requirements of lubrication for cold rolling, but they
do not have the regeneration property due to the presence of detergent /emulsifier etc.
Naturally available palm oils which sometimes are therefore used as regenerative type
lubricant but they suffer from limitations like lack desirable properties such as improper
dispersion, low load bearing capacity, high consumption of lubricant etc.
In general, any emulsifiable cold rolling oil formulation consists of natural fats/triglycerides
or synthetic esters, or combination of both, along with other additives such as emulsifiers,
load bearing additives, antioxidants, detergents and biocides. Such oils form fairly stable
emulsion under agitation and hence were not found to be suitable for usage in the subject
mill since this could not be recovered in the system designed specifically for palm oil. With
the usage of palm oil, following problems were being faced in the subject mill:
a. Improper dispersion leading to uneven oil plate-out on the strip resulting in
improper lubrication, generation of stain/patches on rolled strips, and high oil
consumption.
b. Due to part emulsification, recovery percentage of palm oil was very low (below
50%).
c. Palm oil being a high titer fat, energy consumption was higher in the mixing
tanks.
d. Palm oil alone could not bear the high load cold rolling operation is done with.
This resulted in frequent strip breakage and poor surface quality.
Thus, there was a persistent need for development of highly economical balanced dispersion
type rolling oil for cold rolling application devoid of any emulsifier and having desired
regeneration property.
Objects of the Invention:
Thus, it is the basic object of this invention to prepare dispersion type rolling oil for use in
the cold rolling of thin gauge sheet of steel, which will have all the properties of a
satisfactory dispersion but without use of emulsifying agent/detergent and also have the
regeneration property.
A further object of the present invention is directed to providing a selective base fluid
formulation comprising lubricant selected from triglycerides of oleic acid / palmitic acid
enriched materials preferably karanja, palm and groundnut, mineral oil in the viscosity
range 30 to 70 cst at 40°C, polyol esters including esters of C8-C18:0,l,2,3 carboxylic acids
and bis, tri and tetra alcohol with other conventional ingredients provided such as to
disperse completely in water phase with oil droplet size in the range from 3 -15 urn, under
high agitation and at 50° to 70°C temperature which can be recuperated after use.
A further object of the present invention is directed to preparation of regenerative type
synthetic cold rolling oil formulation wherein the conventional ingredients are preferably
selected from dispersants, wetting agents, antioxidants, biocides, EP/AW additives.
It is yet another objects to propose dispersion type oil, which maintains its physical
properties and chemical characteristics over a long period of time and can ensure uniform
results.
Brief Statement of the Invention:
The basic aspect of the present invention is therefore directed to a method for preparation
of regenerative type synthetic/semi-synthetic cold rolling oil formulation cornprfsing:
providing a selective base fluid formulation comprising lubricant selected from triglycerides
of oleic acid / palmitic acid enriched materials preferably rapeseed, palm and groundnut,
mineral oil in the viscosity range 30 to 70 cst at 40°C, polyol esters including esters of C8-
C18:0,l,2,3 carboxylic acids and bis, tri and tetra alcohol with other conventional
ingredients provided such as to disperse completely in water phase with oil droplet size in
the range from 3 -15 µm, under high agitation and at 50° to 70°C temperature which can be
recuperated after use.
A further aspect of the present invention directed to a method for preparation of
regenerative type synthetic cold rolling oil formulation wherein the conventional ingredients
are preferably selected from dispersants, wetting agents, antioxidants, biocides, Extreme
Pressure(EP)/Anti-Wear(AW) additives.
Another aspect of the present invention directed to a method for preparation of regenerative
type synthetic cold rolling oil formulation wherein the triglycerides are used at weight
concentration of 20 to 50% and polyol esters are used at weight concentration of 10 to 80%
and preferably 20 to 50%.
A further aspect of the present invention directed to a method for preparation of
regenerative type synthetic cold rolling oil formulation wherein dispersants are selected
such as to disperse the triglycerides/polyol esters in water under mechanical agitation and
are preferably selected from primary/secondary amines with C4-C22 chain length and
monocarboxylic fatty acids with C3 to C12 chain length.
A still further aspect of the present invention directed to a method for preparation of
regenerative type synthetic cold rolling oil formulation wherein the dispersants are used at a
weight concentration of 0.5 to 3%.
A still further aspect of the present invention directed to a method for preparation of
regenerative type synthetic cold rolling oil formulation wherein antioxidants were selected
from stearically hindered butylated para cresylic acid, secondary biphenyl amines and the
weight concentration of antioxidant is in the range of 0.05 to 1.0%.
A still further aspect of the present invention directed to a method for preparation of
regenerative type synthetic cold rolling oil formulation wherein EP/AW additives are selected
from sulfur, nitrogen, phosphorus based and alkylated zinc compounds with N, P and these
are incorporated in the range of 0.1 to 5%.
A still further aspect of the present invention directed to a method for preparation of
regenerative type synthetic cold rolling oil formulation as claimed in anyone of claims 1 to 7
wherein selected biocides are based on methylated, butylated isothiazolon derivatives and
triazines and are added in the range of weight concentration ranging from 0.1 to 1.0%.
According to an important aspect of the present invention said cold rolling emulsion
obtained of the regenerative type sysnthetic cold rolling oil formulation wherein said
emulsion comprising said lubricant oil 2 to 6% and water 94 to 98%.
A still further aspect of the present invention directed a method for cold rolling of steel in
the presence of cold rolling emulsion , comprising:
providing said emulsion with selective oil concentration for various strands wherein
(i) the oil concentration for the emulsion system in between stands 1-2, 2-3 and 3-4
is selected from (a) 2-5% for galvanizing and sheet gauge steels and (b) 3-6%
for tin-plate steel ; and
(ii) the oil concentration for emulsion system between the stands 4-5 is selected
from (a) 1-1.5% for galvanizing and sheet gauge steel and (b) 1-2% for tin-plate
steel.
A still further aspect of the present invention directed tosaid regenerative type synthetic oil
of the present invention as the known regenerative dispersion type oils are derived from
natural oils (e.g. palm oil) and thus contain many undesirable constituents, and involves
preparing a dispersion type oil based on synthetic esters and some natural oils to suit cold
rolling application purposes. The present oil emulsion could be beneficially employed as
hydrodynamic/boundary lubricants with other ingredients to prepare a suitable dispersion
type oil.
A still further aspect of the present invention is that the known method of preparation of oil
and its dispersion could not be employed due to the change in the natures and behaviors of
the ingredients and as such the subject cold rolling mill was designed to use dispersion
based on Palm oil as the lubricant. Herein, a dispersion of oil-in-water is prepared by
agitation at high speed in mixing tanks at elevated temperature (ranging between 50-90°
C). The dispersion thus prepared is applied directly on the strip in between the stands for
lubrication. The used dispersion is then pumped to a recovery system for recovering the
used oil out of the dispersion for reuse in the same system.
According to an aspect of the invention, the recovery process comprises of skimming, hot
water washing and two-stage centrifuging to remove various contaminants and separate oil
from water.
The present invention its objects and advantages are described in further details with
reference to accompanying non-limiting illustrative examples.
Further Details of the Invention:
The work on subject invention was taken up to overcome above listed shortcomings of palm
oil. The developed oil is so designed to disperse uniformly under high agitation in water
phase at temperature range of 50-70° C to a droplet size range of 3-15µm. This uniform
dispersion is then applied on the strips by means of nozzles. The used dispersion separated
rapidly under stationary condition and the oil is recovered in the recovery system for reuse.
With the usage of this oil, increased recovery (up to 70%), better strip finish, lower oil
consumption, lower energy consumption, and decreased frequency of strip breakage were
achieved.
The present invention features composition of cold rolling oil for steel, which includes
hydrodynamic/boundary lubricants, dispersants, wetting agents, anti-oxidants, mineral oils,
biocides, Extreme Pressure(EP)/Anti-Wear(AW) additives.
In this invention, for hydrodynamic/boundary lubrication, raw materials were selected from
triglycerides of oleic acid/palmitic acid enriched materials like rapeseed, palm, and
groundut; mineral oils in the viscosity range 30-70 cSt at 40°C; Polyol esters including
esters of C8-C18:o, 1,2,3 carboxylic acids and bis, tri and tetra alcohol. Triglycerides were used
at weight concentration of 20 to 50% and polyol esters at weight concentration of 20 to
50%. Dispersants were used to disperse the triglycerides/polyol esters in water under
mechanical agitation. Same were selectd from primary/secondary amines with C4-C22 chain
length and monocarboxylic fatty acids with C3 to C12 chain length. Dispersants were used at
a weight concentration of 0.5 to 3%. Monocarboxylic fatty acids were used at a weight
concentration of 0.5% to 3%.
Antioxidants were selected from stearically hindered butylated para cresylic acid, secondary
biphenyl amines. Weight concentration of antioxidant was in the range of 0.05 to 1.0%.
EP/AW additives were selected from sulfur, nitrogen, and phosphorus based and alkylated
zinc compounds with N, P. These were incorporated in the range of 0.1 to 5%. Selected
biocides were based on methylated, butylated iso-thiazolon derivatives and triazines. This
was added in the range of weight concentration ranging from 0.1 to 1.0%.
The invention also suggests the desired emulsion parameters for different emulsion systems
and grades of steel. It further recommends the process conditions to be maintained for
better ease of regeneration. These parameters are summarized below for a typical 5-stand
Tandem Mill:
• Oil concentration for emulsion system in between stands 1-2, 2-3, and 3-4:
a. 2-5% for galvanizing and sheet gauge steels
b. 3-6% for tin-plate steel
• Oil concentration for emulsion system in between stands 4-5:
a. 1-1.5% for galvanizing and sheet gauge steels
b. 1-2% for tin-plate steel
• Dispersion temperature: 50-70°C
• Oil particle size: 3-15
• Temperature of oil during regeneration: 80-90° C
The dispersion according to the present invention, can be made stable at room temperature
under high agitation. It can also be stored at this condition; however, its life will be less
(say 2 months). It can be stored in tanks for higher life (over 4 months) at elevated
temperature (50-70° C) and agitated conditions. At stationary condition, there shall be
separation of oil from the aqueous phase and during storage there can be generation of
bacteria.
Typical example of Preparation:
Example 1:
In a preferred combination of ingredients for a formulation, following steps were followed
during preparation of the oil:
(a) Take triglyceride and mineral oil and heat them up to 70° C,
(b) Add antioxidant and mix thoroughly,
(c) Add polyol ester and mix for Vz to 1 hr at 60-60° C,
(d) Add extreme-pressure and anti-wear additives and mix for Vi - 1 hr at 50-55° C,
(e) Add dispersant and mix for 1-2 hr at 45-50° C,
(f) Add amines and mix for 1-2 hr at 40-45° C,
(g) Add surfactant and mix thoroughly,
(h) Add biocide and mix for 1 - 11/2 hr at 40° C to make the final product ready.
Following steps were followed during preparation of the dispersion :
(a) Take industrial water in the dispersion tank and measure its pH, conductivity,
hardness level etc. The pH value of the dispersion maintained at its desired level
of 6.0-7.0,
(b) Heat water to 50-70° C,
(c) Add metered quantity of fresh oil (or mixture of fresh and recuperated oils) in the
hot water for making dispersion of desired concentration,
(d) While addition the oil and afterwards also agitate the dispersion vigorously,
(e) After the dispersion is sprayed over the strip, collect the used dispersion in
setting tank,
(f) Follow the standard process of recuperation of the used oil. Temperature of the
oil during recuperation should be 80-90°C.
Example 2:
In another experimental formulation, following steps are followed during preparation of the
oil:
(a) Take triglyceride and mineral oil and heat them up to 70° C,
(b) Add antioxidant and mix thoroughly,
(c) Add polyol ester and mix for 1/2 to 1 hr at 60-60° C,
(d) Add extreme-pressure and anti-wear additives and mix for 1/2- 1 hr at 50-55° C,
(e) Add amines dispersant and mix for 1-2 hr at 40-45° C,
(f) Add biocide and mix for 1 - 1/2 hr at 40° C to make the final product ready.
Following steps are followed during preparation of the dispersion :
(a) Take industrial water in the dispersion tank and measure its pH, conductivity,
hardness level etc. The pH value of the dispersion maintained at its desired level
of 6.0-7.0,
(b) Heat water to 50-70° C,
(c) Add metered quantity of fresh oil (or mixture of fresh and recuperated oils) in the
hot water for making dispersion of desired concentration,
(d) While addition the oil and afterwards also agitate the dispersion vigorously,
(e) After the dispersion is sprayed over the strip, collect the used dispersion in
setting tank,
(f) Follow the standard process of recuperation of the used oil. Temperature of the
oil during recuperation should be 80-90°C.
Experimental Results of the prepared sample:
Following are some of the typical laboratory results of the prepared oil:
(a) Specific gravity at 30° C : 0.91
Usefulness of Invention and Advantages:
The subject innovation has exhibited following typical benefits :
a. Technological benefit :
• Superior quality of CR strips/sheets (stain-free coils)
• Improved lubricity (reduction in roll force by 10-20%)
• Reduction in strip breakage (by about 50%)
b. Economic benefit :
• Lower specific rolling oil consumption (10-15%)
• Lower specific roll consumption (40-45%)
c. Impact in industry :
• The innovated rolling oil can be used to substitute the inferior quality palm
oil/industrial palm oil, being used as lubricant in the cold rolling of steel.
There is requirement of over 500 kiioiiters per annum of this type of oil at a
typical Tandem Cold Mill of 400000 MT/year capacity.
d. Advancement of knowledge/science :
• First time a synthetic regeneration type rolling oil has been developed as
lubricant for cold rolling of steel.
e. Social benefit :
• Improved house keeping/mild cleanliness
• Ease of regeneration

WE CLAIM:
1. A method for preparation of regenerative type synthetic cold rolling oil formulation
comprising:
providing a selective base fluid formulation comprising lubricant selected from triglycerides
of oleic acid / palmitic acid enriched materials preferably karanja, palm and groundnut,
mineral oil in the viscosity range 30 to 70 cst at 40°C, polyol esters including esters of C8-
C18:0,l,2,3 carboxylic acids and bis, tri and tetra alcohol with other conventional
ingredients provided such as to disperse completely in water phase with oil droplet size in
the range from 3 -15 nm, under high agitation and at 50° to 70°C temperature which can be
recuperated after use.
2. A method for preparation of regenerative type synthetic cold rolling oil formulation as
claimed in claim 1 wherein the conventional ingredients are preferably selected from
dispersants, wetting agents, antioxidants, biocides, EP/AW additives.
3. A method for preparation of regenerative type synthetic cold rolling oil formulation as
claimed in anyone of claims 1 or 2 wherein the triglycerides are used at weight
concentration of 20 to 50% and polyol esters are used at weight concentration of 10 to 80%
and preferably 20 to 50%.
4. A method for preparation of regenerative type synthetic cold rolling oil formulation as
claimed in anyone of claims 1 to 3 wherein dispersants are selected such as to disperse the
triglycerides/polyol esters in water under mechanical agitation and are preferably selected
from primary/secondary amines with C4-C22 chain length and monocarboxylic fatty acids
with C3 to C12 chain length.
5. A method for preparation of regenerative type synthetic cold rolling oil formulation as
claimed in claim 4 wherein the dispersants are used at a weight concentration of 0.5 to 3%.
6. A method for preparation of regenerative type synthetic cold rolling oil formulation as
claimed in anyone of claims 1 to 5 wherein antioxidants were selected from stearically
hindered butylated para cresylic acid, secondary biphenyl amines and the weight
concentration of antioxidant is in the range of 0.05 to 1.0%.

7. A method for preparation of regenerative type synthetic cold rolling oil formulation as
claimed in anyone of claims 1 to 6 wherein EP/AW additives are selected from sulfur,
nitrogen, phosphorus based and alkylated zinc compounds with N, P and these are
incorporated in the range of 0.1 to 5%.
8. A method for preparation of regenerative type synthetic cold rolling oil formulation as
claimed in anyone of claims 1 to 7 wherein selected biocides are based on methylated,
butylated isothiazolon derivatives and triazines and are added in the range of weight
concentration ranging from 0.1 to 1.0%.
9. A method for cold roiling of steel in the presence of cold rolling emulsion comprising:
providing said emulsion with selective oil concentration for various strands wherein
the oi! concentration for the emulsion system in between stands 1-2, 2-3 and 3-4
is selected from (a) 2-5% for galvanizing and sheet gauge steels and (b) 3-6%
for tin-plate steel ; and
(ii) the oil concentration for emulsion system between the stands 4-5 is selected
from (a) 1-1.5% for galvanizing and sheet gauge steel and (b) 1-2% for tin-plate
steel.
10. A method for preparation of regenerative type synthetic cold rolling oil formulation,
emulsion obtained thereof and its use in cold rolling of steel substantially as hereindescribed
and illustrated with reference to the accompanying examples.
There is disclosed a method for the preparation of regenerative type synthetic/semi-
synthetic cold rolling oil and its dispersion for Tandem Steel Mill. The oil comprises of polyol
esters, based on carboxylic acids of C8 to C18:0,1,2,3 and bis, tris and tetra alcohol, or
triglycerides, antioxidants, dispersants, S and N-P based EP and anti-wear additives, and
biocides which has no emulsifying agent. The composition and the method of preparation
are especially suitable for high speed rolling with wide variation in output strip thickness,
ranging from thin gauge TMBP to thicker sheet gauge materials. The oil forms dispersion in
water and the used oil is easily recuperated for economic reason. The advantages of this
product include superior lubricity, high strip surface cleanliness, low oil and roll
consumptions and high level of regeneration.