FORM 2
THE PATENTS ACT, 1970 (39 of 1970) & THE PATENTS RULES, 2003
COMPLETE SPECIFICATION (See section 10, rule 13)
1. Title of the invention: A PROCESS FOR PREPARING A RUBBER MASTERBATCH
2. Applicant(s)
NAME NATIONALITY ADDRESS
CEAT LIMITED Indian RPG HOUSE, 463, Dr. Annie Besant Road, Worli, Mumbai, Maharashtra 400030, India
3. Preamble to the description
COMPLETE SPECIFICATION
The following specification particularly describes the invention and the manner in which it
is to be performed.

FIELD OF INVENTION
[0001] The present disclosure broadly relates to tire body ply. Particularly, the present invention relates to a process for preparing a rubber masterbatch.
BACKGROUND OF INVENTION
[0002] Tire body ply and belt compounds are composed of high loading of natural rubber and carbon black filler. In a conventional rubber mixing procedure for intermix, the process typically begins with the addition of rubber, fillers, and various processing chemicals during an initial stage, followed by the introduction of curatives in the final stage. While mixing such loaded materials with filler natural rubber compounds, the process requires intense mixing with a lower fill factor to achieve optimum mechanical breakdown of the mixture. However, the rubber mixing process with a low fill factor causes slippage of rubber compounds between the rotors of the machinery, resulting in longer mixing cycle times and the need for multiple stages to achieve thorough mixing. This, in turn, leads to a decrease in productivity.
[0003] Hence, there is a need to develop a process to prepare a rubber master batch, which enables increasing fill factor, eliminating slippage between the rotors, which reduces mixing time with improved mix quality and increases mixing throughput.
SUMMARY OF THE INVENTION
[0004] In a first aspect of the present disclosure, there is provided a process for
preparing a rubber masterbatch in an intermix, the process comprising:
a. mixing a raw rubber with a portion of a first filler, a portion of a second
filler and at least one first additive, with fill factor in a range of 55 to 60%,
under stirring in a range of 45 to 60 rpm to obtain a first mix;
b. blending the first mix with a remaining portion of the first filler with fill
factor in a range of 50 to 60%, under stirring in a range of 35 to 45 rpm to
obtain a second mix; and

c. adding remaining portion of the second filler and at least one second additive with fill factor in a range of 45 to 58%, under stirring in a range of 25 to 42 rpm to the second mix to obtain a rubber masterbatch. [0005] In a second aspect of the present disclosure, there is provided a rubber compound prepared by the process as disclosed herein.
[0006] In a third aspect of the present disclosure, there is provided an article comprising the rubber compound as disclosed herein.
[0007] In a fourth aspect of the present disclosure, there is provided a use of the rubber compound as disclosed herein or the article as disclosed herein. [0008] These and other features, aspects, and advantages of the present subject matter will be better understood with reference to the following description and appended claims. This summary is provided to introduce a selection of concepts in a simplified form. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.
BRIEF DESCRIPTION OF THE FIGURES
[0009] The following drawings form a part of the present specification and are included to further illustrate aspects of the present disclosure. The disclosure may be better understood by reference to the drawings in combination with the detailed description of the specific embodiments presented herein.
[00010] Figure 1 depicts the comparative analysis of the Mooney viscosity of the first mix (before) and rubber masterbatch (after), in accordance with an embodiment of the present disclosure.
[00011] Figure 2 depicts the comparative analysis of the cycling time for the first mix, second mix, and third mix for conventional process (blue) and the process of the present disclosure (orange), in accordance with an embodiment of the present disclosure.
[00012] Figure 3 depicts the comparative analysis of the productivity of the process of the present disclosure (orange; trial) with conventional mixing process (blue;

regular), with respect to the second mix and third mix, in accordance with an embodiment of the present disclosure.
DETAILED DESCRIPTION OF THE INVENTION
[00013] Those skilled in the art will be aware that the present disclosure is subject to variations and modifications other than those specifically described. It is to be understood that the present disclosure includes all such variations and modifications. The disclosure also includes all such steps, features, composites, and compounds referred to or indicated in this specification, individually or collectively, and any and all combinations of any or more of such steps or features. Definitions
[00014] For convenience, before further description of the present disclosure, certain terms employed in the specification, and examples are delineated here. These definitions should be read in the light of the remainder of the disclosure and understood as by a person of skill in the art. The terms used herein have the meanings recognized and known to those of skill in the art, however, for convenience and completeness, particular terms and their meanings are set forth below.
[00015] The articles “a”, “an” and “the” are used to refer to one or to more than one (i.e., to at least one) of the grammatical object of the article.
[00016] The terms “comprise” and “comprising” are used in the inclusive, open sense, meaning that additional elements may be included. It is not intended to be construed as “consists of only”.
[00017] Throughout this specification, unless the context requires otherwise the word “comprise”, and variations such as “comprises” and “comprising”, will be understood to imply the inclusion of a stated element or step or group of element or steps but not the exclusion of any other element or step or group of element or steps. [00018] The term “including” is used to mean “including but not limited to”. “Including” and “including but not limited to” are used interchangeably. [00019] The term “raw rubber” refers to basic latex material comprising isoprene-based polymer. In an aspect of the present disclosure, there is provided a process

for preparing a rubber masterbatch in an intermix, the process comprising: mixing a raw rubber with a portion of a first filler.
[00020] The term “fill factor” refers to the factor by which the rubber mixing chamber is filled with the rubber components. In an aspect of the present disclosure, there is provided a process for preparing a rubber masterbatch, the process comprises mixing a raw rubber with a portion of a first filler, a portion of a second filler, and at least one first additive, with fill factor in a range of 55 to 60%. [00021] The term “Mooney viscosity” refers to the shearing torque resisting rotation of a metal rotor embedded in rubber. In an aspect of the present disclosure, there is provided a process for preparing a rubber masterbatch, wherein the rubber masterbatch exhibits Mooney viscosity in a range of 58 to 61 ML (1+4) 100. In another aspect of the present disclosure, the Mooney viscosity is expressed as, for instance, 60 ML (1+4) 100, where 60 stands for the value of viscosity in Mooney units, M indicates Mooney, L indicates that a large rotor was used (S for small rotor), 1 indicates one minute preheating time, 4 refers to the time in minutes after starting the rotor, and 100°C is test temperature.
[00022] Ratios, concentrations, amounts, and other numerical data may be presented herein in a range format. It is to be understood that such range format is used merely for convenience and brevity and should be interpreted flexibly to include not only the numerical values explicitly recited as the limits of the range, but also to include all the individual numerical values or sub-ranges encompassed within that range as if each numerical value and sub-range is explicitly recited. For example, a weight range of 5 to 20% should be interpreted to include not only the explicitly recited limits of 5 to 20% but also include sub-ranges, such as 5 to 10%, 5 to 11%, 7 to 10%, and so forth, as well as individual amounts, including fractional amounts, within the specified ranges, such as 5%, 11%, 12%, 13.5%, and so on. [00023] 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 disclosure belongs. Although any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the disclosure, the preferred methods, and materials are now described.

[00024] The present disclosure is not to be limited in scope by the specific embodiments described herein, which are intended for the purposes of exemplification only. Functionally equivalent products, composites, and methods are clearly within the scope of the disclosure, as described herein.
[00025] As discussed in the background, there is a need in the art to develop
an efficient process to prepare a rubber compound. In order to achieve better mixing of rubber compound and achieve better throughput, there is a need to reduce the viscosity of the mixture and thereby increase the fill factor so as to enhance the productivity of the process. To solve the technical problem, the present disclosure provides a process for preparing a rubber masterbatch that involves a reduction of mixing time. The process employs optimizing the mixing sequence and modifying the order of addition of dry chemicals/ingredients/filler which enables increasing fill factor, eliminating slippage between rotors and reduced mixing time with improved mix quality and increased mixing throughput. Accordingly, the present disclosure provides a process for preparing a rubber masterbatch wherein the process employs multistep mixing of a high load of filler.
[00026] In an embodiment of the present disclosure, there is provided a
process for preparing a rubber masterbatch, the process comprising: a. mixing a raw
rubber with a portion of a first filler, a portion of a second filler, and at least one
first additive, with fill factor in a range of 55 to 60%, under stirring in a range of 45
to 60 rpm to obtain a first mix; b. blending the first mix with a remaining portion
of the first filler with fill factor in a range of 50 to 60%, under stirring in a range of
35 to 45 rpm to obtain a second mix; and c. adding remaining portion of the second
filler and at least one second additive with fill factor in a range of 45 to 58%, under
stirring in a range of 25 to 42 rpm to the second mix to obtain a rubber masterbatch.
[00027] In another embodiment of the present disclosure, the process
comprising: a. mixing a raw rubber with a portion of a first filler, a portion of a second filler and at least one first additive, with fill factor in a range of 55 to 59%, under stirring in a range of 50 to 60 rpm to obtain a first mix; b. blending the first mix with a remaining portion of the first filler with fill factor in a range of 54 to 60%, under stirring in a range of 40 to 45 rpm to obtain a second mix; and c. adding

remaining portion of the second filler and at least one second additive with fill factor in a range of 48 to 56%, under stirring in a range of 30 to 42 rpm to the second mix to obtain a rubber masterbatch.
[00028] In another embodiment of the present disclosure, the process
comprising: a. mixing a raw rubber with a portion of a first filler, a portion of a second filler and at least one first additive, with fill factor in a range of 56 to 58%, under stirring in a range of 50 to 55 rpm to obtain a first mix; b. blending the first mix with a remaining portion of the first filler with fill factor in a range of 56 to 58%, under stirring in a range of 40 to 45 rpm to obtain a second mix; and c. adding remaining portion of the second filler and at least one second additive with fill factor in a range of 50 to 55%, under stirring in a range of 30 to 40 rpm to the second mix to obtain a rubber masterbatch.
[00029] In an embodiment of the present disclosure, there is provided a
process, wherein the raw rubber is isoprene-based rubber. In an embodiment of the present disclosure, the raw rubber is natural rubber.
[00030] In an embodiment of the present disclosure, there is provided a
process, wherein the portion of the first filler and the portion of the second filler in
step (a) is in a weight range of 60 to 80%, with respect to total weight of filler. In
another embodiment of the present disclosure, the portion of the first filler in step
(a) is in a weight range of 70 to 75%, with respect to total weight of filler. In yet
another embodiment of the present disclosure, the portion of the second filler is in
step (a) is in a weight range of 60 to 70%, with respect to total weight of filler.
[00031] In an embodiment of the present disclosure, there is provided a
process, wherein the remaining portion of first filler in step (b) is in a weight range of 20 to 40%, with respect to total weight of filler. In another embodiment of the present disclosure, the remaining portion of first filler in step (b) is in a weight range of 20 to 35%, with respect to total weight of filler. In yet another embodiment of

the present disclosure, the remaining portion of first filler in step (b) is in a weight range of 25 to 30%, with respect to total weight of filler.
[00032] In an embodiment of the present disclosure, there is provided a
process, wherein the remaining portion of second filler in step (c) is in a weight range of 30 to 40%, with respect to total weight of filler.
[00033] In an embodiment of the present disclosure, there is provided a
process, wherein the first additive is in a weight range of 20 to 40% with respect to total weight of the rubber master batch.
[00034] In an embodiment of the present disclosure, there is provided a
process, wherein the second additive is in a weight range of 1 to 10% with respect to the total weight of the rubber masterbatch.
[00035] In an embodiment of the present disclosure, there is provided a
process, wherein the first additive is selected from peptizers, activators, or combinations thereof.
[00036] In an embodiment of the present disclosure, there is provided a
process, wherein the second additive is selected from activators, antioxidants, adhesive promoters, or combinations thereof.
[00037] In an embodiment of the present disclosure, there is provided a
process, wherein peptizer is selected from 2,2 dibenzamido diphenyl disufide;
activator is selected from zinc oxide, stearic acid, or combinations thereof; adhesive
promoters selected from cobalt boroacylate, cobalt neodecanoate, or combinations
thereof; and antioxidant is selected from 2,2,4,-trimethyl-1,2-dihydroquinoline, 6-
phenyl-p-phenylenediamine, 2,2,4,-trimethyl-1,2-dihydroquinoline, or
combinations thereof.
[00038] In an embodiment of the present disclosure, there is provided a
process, wherein the process further comprises mixing the rubber masterbatch with at least one third additive to obtain a rubber compound.
[00039] In an embodiment of the present disclosure, there is provided a
process, wherein the third additive is selected from a curative, an accelerator, a retarder, an activator, or combinations thereof.

[00040] In an embodiment of the present disclosure, there is provided a
process, wherein the curative is sulfur; the accelerator is selected from
dichlorosilane (DCS), N,N'-dicyclohexyl-2-benzothiazole sulfenamide, N-tert-
butylbenzothiazole-2-sulphenamide, or combinations thereof; the retarder is N-
(cyclohexylthio) phthalimide, and the activator is selected from zinc oxide, stearic
acid, or combinations thereof.
[00041] In an embodiment of the present disclosure, there is provided a
process, wherein the first mix, the second mix and the rubber masterbatch are
subjected to maturation for a period in a range of 4 to 8 hours, prior to further
processing.
[00042] In an embodiment of the present disclosure, there is provided a
process, wherein steps (a), (b), and (c), are carried out at a ram pressure in a range
of 40 to 60 psi, and at a temperature in a range of 100 to 160⁰C.
[00043] In an embodiment of the present disclosure, there is provided a
process, wherein the the rubber compound exhibits Mooney viscosity in a range of
58 to 61.
[00044] In an embodiment of the present disclosure, there is provided a
process, wherein the process exhibits a cycle time efficiency of at least 30%.
[00045] In an embodiment of the present disclosure, there is provided a
rubber compound prepared by the process as disclosed herein.
[00046] In an embodiment of the present disclosure, there is provided an
article comprising the rubber compound as disclosed herein. In another
embodiment of the present disclosure, the article comprising the rubber compound
as disclosed herein is selected from tire body, tire body ply, tire related parts, and
the like.
[00047] In an embodiment of the present disclosure, there is provided a use
of the rubber compound as disclosed herein or the article as disclosed herein. In
another embodiment of the present disclosure, the use of the rubber compound as
disclosed herein, selected from use in manufacturing and processing of tire body,
tire body ply, tire related parts, tire belt, and the like.

[00048] Although the subject matter has been described in considerable
detail with reference to certain examples and implementations thereof, it is understood that other implementations are possible and included within the scope of the present invention.
EXAMPLES
[00049] The disclosure will now be illustrated with following examples, which is intended to illustrate the working of disclosure and not intended to take restrictively to imply any limitations on the scope of the present disclosure. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood to one of ordinary skill in the art to which this disclosure belongs. Although methods and materials similar or equivalent to those described herein can be used in the practice of the disclosed methods and composites, the exemplary methods, devices, and materials are described herein. It is to be understood that this disclosure is not limited to particular methods, and experimental conditions described, as such methods and conditions may apply.
Materials
[00050] Raw natural rubber (RSS4, RSS4DF; ABN impex, Amarjyothy
traders), carbon black (N220, N326; PCBL), highly dispersible silica (HDS; Madhu Silica),
EXAMPLE 1
[00051] In stage 1, raw natural rubber was mixed with 60% by weight of
carbon black (first filler), 70% of silica (second filler), with 20 to 40% by weight
of first additive comprising 2,2-dibenzamido diphenyl disufide (peptizer), zinc
oxide and stearic acid (activator), with fill factor of 57% at rotor stirring rate of 50
rpm, 45 PSI ram pressure and dumping at 155 ⁰C temperature to obtain a first mix
having Mooney viscosity of 112 ML(1+4) at 100⁰C.
[00052] In stage 2, the first mix was blended with the remaining portion 40%
by weight of the carbon black with a fill factor of 57%, under stirring at a rotor
speed of 40 rpm, 55 PSI ram pressure, and dumping at 155⁰C temperature to obtain
a second mix having a Mooney viscosity of 98 ML(1+4) at 100⁰C.

[00053] In stage 3, the remaining portion 30 % by weight of silica was added
to the second mix with cobalt boroacylate (adhesive promotor), zinc oxide and
stearic acid (activator) and 2,2,4,-trimethyl-1,2-dihydroquinoline (antioxidant) with
fill factor of 55%, under stirring rate of 40 rpm for 30 to 50 seconds, 45 PSI ram
pressure, and dumping at 145⁰C temperature to obtain a third mix having a Mooney
viscosity of 80 ML(1+4) at 100⁰C.
[00054] In stage 4, the third mix was added with sulfur (curative),
dichlorosilane (accelerator), and N-(cyclohexylthio) phthalimide (retarder) with
66% fill factor, at 25 rpm rotor speed and 45 PSI ram pressure, dumping at a
temperature of 100 ⁰C to obtain a rubber masterbatch having a Mooney viscosity of
60 ML(1+4) at 100⁰C.
[00055] All these stages of mixing were followed by at least 4 hr of maturation
time to release any unwanted stress residuals generated because of intensive mixing
process.
[00056] The process provided herein provided a rubber master batch having
reduced Mooney viscosity thereby resulting in better rubber processing in
subsequent processes. Figure 1 depicts the comparative analysis of the first mix
(before) and rubber masterbatch (after).
[00057] The productivity of the process disclosed in the present disclosure was
comparatively analyzed with that of the conventional process wherein the carbon
black and silica fillers were added in stage 1 of the process with the temperature
and rotor speed parameters as above. and mixed at differential speeds in stage 2 and
3. In stage 4, the rubber mix was blended with curatives, retarders, accelerator, and
antioxidant, to result in the rubber masterbatch.
[00058] The productivity of the process of the present disclosure was compared
with that of the conventional process to note that the process of the present
disclosure provided increased productivity to the factor of 2.26 and 1.2 for first
stage and second stage respectively.
[00059] Figure 2 depicts the comparative cycling time required for the stages 1,
2, and 3 of the conventional process and the process of the present disclosure. The
process of the present disclosure resulted in first mix, second mix and rubber

masterbatch in stages 1, 2 and 3 respectively having much lesser Mooney viscosity than those of the conventional process. The present disclosure provided a cycle time efficiency of at least 30% over the conventional mixing process.
[00060] Furthermore, the productivity of the process of present disclosure was comparatively analyzed with respect to the regular process as shown in Figure 3. Figure 3 depicts the comparative analysis of the productivity of the process of the present disclosure (orange; trial) with conventional mixing process (blue; regular), with respect to the second mix and third mix. For the process of present disclosure, the productivity of the second mix was obtained in an increased factor of 2.26 than that obtained for the regular process. Further mixing step also showed similar results where the third mix was obtained by an increased factor of 1.2 for the process of present disclosure, than that of the regular process.
ADVANTAGES OF THE PRESENT INVENTION
The process of the present disclosure provides a convenient yet inexpensive method for obtaining better productivity and higher efficiency by reducing the viscosity of the intermixes as well as by facilitating higher fill factor. The present disclosure provides a process wherein the viscosity of mixes is reduced by adding the fillers in multiple stages in specific weight ranges and thereby results in better mixing and throughput. Furthermore, the process of the present disclosure results in lesser cycling time.

I/We Claim:
1. A process for preparing a rubber masterbatch in an intermix, the process
comprising:
a. mixing a raw rubber with a portion of a first filler, a portion of a
second filler, and at least one first additive, with fill factor in a range
of 55 to 60%, under stirring in a range of 45 to 60 rpm to obtain a
first mix;
b. blending the first mix with a remaining portion of the first filler with
fill factor in a range of 50 to 60%, under stirring in a range of 35 to
45 rpm to obtain a second mix; and
c. adding a remaining portion of the second filler and at least one
second additive with fill factor in a range of 45 to 58%, under stirring
in a range of 25 to 42 rpm to the second mix to obtain a rubber
masterbatch.
2. The process as claimed in claim 1, wherein the raw rubber is isoprene-based rubber.
3. The process as claimed in claim 1, wherein the portion of the first filler and the portion of the second filler in step (a) is in a weight range of 60 to 80%, with respect to total weight of filler.
4. The process as claimed in claim 1, wherein the remaining portion of first filler in step (b) is in a weight range of 20 to 40%, with respect to total weight of filler.
5. The process as claimed in claim 1, wherein the remaining portion of second filler in step (c) is in a weight range of 30 to 40%, with respect to total weight of filler.
6. The process as claimed in claim 1, wherein the first additive is in a weight range of 20 to 40% with respect to total weight of the rubber masterbatch.
7. The process as claimed in claim 1, wherein the second additive is in a weight range of 1 to 10% with respect to the total weight of the rubber masterbatch.
8. The process as claimed in claim 1, wherein the first additive is selected from peptizers, activators, or combinations thereof, and the second additive is

selected from activators, antioxidants, adhesive promoters, or combinations thereof.
9. The process as claimed in claim 8, wherein peptizer is 2,2 dibenzamido diphenyl disufide; activator is selected from zinc oxide, stearic acid, or combinations thereof; adhesive promoters selected from cobalt boroacylate, cobalt neodecanoate, or combinations thereof; and antioxidant is selected from 2,2,4,-trimethyl-1,2-dihydroquinoline, 6-phenyl-p-phenylenediamine, 2,2,4,-trimethyl-1,2-dihydroquinoline, or combinations thereof.
10. The process as claimed in claim 1, wherein the process further comprises mixing the rubber masterbatch with at least one third additive to obtain a rubber compound.
11. The process as claimed in claim 10, wherein the third additive is selected from a curative, an accelerator, a retarder, an activator, or combinations thereof.
12. The process as claimed in claim 11, wherein the curative is sulfur; the accelerator is selected from dichlorosilane (DCS), N,N'-dicyclohexyl-2-benzothiazole sulfenamide, N-tert-butylbenzothiazole-2-sulphenamide, or combinations thereof; the retarder is N-(cyclohexylthio) phthalimide, and the activator is selected from zinc oxide, stearic acid, or combinations thereof.
13. The process as claimed in claim 1, wherein the first mix, the second mix and the rubber masterbatch are subjected to maturation for a period in a range of 4 to 8 hours, prior to further processing.
14. The process as claimed in claim 1, wherein steps (a), (b), and (c), are carried out at a ram pressure in a range of 40 to 60 psi, and at a temperature in a range of 100 to 160⁰C.
15. The process as claimed in claim 1, wherein the rubber masterbatch exhibits Mooney viscosity in a range of 58 to 61.
16. The process as claimed in claim 1, wherein the process exhibits a cycle time efficiency of at least 30% as compared with the conventional process .
17. A rubber compound prepared by the process as claimed in claim 1.

18. An article comprising the rubber compound as claimed in claim 17.
19. Use of the rubber compound as claimed in claim 17 or the article as claimed in claim 18.