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: CONTINUOUS PROCESS FOR PREPARING AN ELASTOMER
COMPOUND
2. Applicant(s)
NAME NATIONALITY ADDRESS
CEAT LIMITED Indian RPG HOUSE, 463, Dr. Annie Besant Road, Worli, Mumbai 400 030, 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
[001] The present disclosure broadly relates to a process for preparing an elastomeric compound, and particularly relates to a continuous process for preparing an elastomer compound in a twin-screw extruder.
BACKGROUND OF INVENTION
[002] The elastomer compounds are known to play a pivotal role in the rubber industry as a starting material of each elastomeric product, such as tires, conveyor belts, seals, elastic bellows and the like. Generally, the elastomeric compound comprises the following components: rubber in different forms (lumps, granulated material, powder, liquid), reinforcing fillers, processing aids, curatives, etc. The presence of each of the aforementioned component plays an important role in imparting varied characteristic features to the final rubber compound. For instance, the primary function of the reinforcing filler such as carbon black is to improve the mechanical properties of the rubber compound.
[003] Adequate mixing of the components is required to obtain a final rubber compound that processes properly, cures sufficiently, and has the necessary physical properties for the end-use purposes. The mixing of the individual components to arrive at the final rubber compound utilizes various types of equipment such as two-roll mills, internal batch mixers, continuous mixers, or combinations thereof. The two-roll mills are exclusively used for the mastication as well as for mixing chemicals. However, the disadvantages associated with two-roll mills outnumber the advantages. The disadvantages of the two-roll mills include: (i) multiple steps for mixing the individual components and thereby increasing the length of the mixing cycles, (ii) requirement of a trained personnel to operate the equipment, (iii) difficulty in standardizing the subjective procedures, (iv) difficulty in controlling batch to batch uniformity, etc. Alternate mixing equipment conventionally used for the preparation of rubber compound is an internal mixer. However, the batch mixing deployed in the internal mixer leads to differences in the mixture quality from one batch to another and consequently, the final rubber compound that is prepared does not exhibit the desired properties.

[004] Constant efforts have been made to replace the discontinuous mixing methods with continuous mixing methods. Different continuous mixing methods employed for preparing the rubber compound are disclosed in the literature. For instance, KR200377632Y1 discloses a continuous process for preparing the rubber compound. The process as disclosed in the said document uses a biaxial extruder. [005] CN1680483A discloses a process for preparing a rubber composition. According to the method disclosed in said patent document, a vulcanizable elastomer is dispersed in the thermoplastic matrix polymer material to form a first mixture, and subsequently, the first mixture is heated for a sufficient time at a temperature that allows curing of the elastomeric material and reactive oligomer polymerization. [006] The mixing process and apparatuses employed for processing and mixing of rubber compounds require multiple-steps. Masterbatch and other mixing operations have a direct impact on the mixing efficiency and dispersion quality. In general, these mixing apparatuses are incompetent in mixing the individual components. As a result of which, the final rubber compound that is obtained, exhibits poor mechanical properties. Therefore, there is a dire need in the present state of art to provide an improved and cost-effective continuous process that allows efficient mixing of the rubber components.
SUMMARY OF THE INVENTION
[007] In an aspect of the present disclosure, there is provided a method for continuously producing an elastomer compound, said method comprising: (a) mixing at least one granulated elastomer and at least one solid particulate matter to obtain a premix; and (b) feeding the premix in an extruder using a gravimetric feeder to obtain the elastomer compound, wherein the extruder has a screw speed in the range of 200 rpm - 1000 rpm.
[008] In another aspect of the present disclosure, there is provided an elastomer compound obtained by the method comprising: (a) mixing at least one granulated elastomer and at least one solid particulate matter to obtain a premix; and (b) feeding the premix in an extruder using a gravimetric feeder to obtain the elastomer

compound, wherein the extruder has a screw speed in the range of 200 rpm - 1000 rpm.
[009] 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 ACCOMPANYING DRAWINGS
[0010] 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.
[0011] Figure 1 depicts the co-rotating twin-screw extruder (CRTSE) indicating the
barrels B1-B11, where the extrusion process for preparing the elastomer compound
occurs, in accordance with an embodiment of the present disclosure.
[0012] Figure 2 depicts the elastomer compound obtained by the method as
disclosed herein, extruded continuously in the CRTSE (Figure 1), in accordance with
an embodiment of the present disclosure.
DETAILED DESCRIPTION OF THE INVENTION
[0013] 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, compositions, 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

[0014] 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.
[0015] 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.
[0016] 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”.
[0017] 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.
[0018] The term “including” is used to mean “including but not limited to”.
“Including” and “including but not limited to” are used interchangeably.
[0019] The term “phr” used herein refers to parts per hundred rubber/resin. It is a
unit well defined in the field of rubber technology to define the amount of ingredients
used. The unit “phr” can also be interchangeably used with the unit “gram” as both
denote phr/gram of ingredient per 100 phr/gram of rubber.
[0020] The term “rpm” used herein refers to rotations/revolutions per minute. It is a
unit well used in the field of rubber technology to define the speed of any rotating
part of the machine, in this disclosure especially for co-rotating twin screw extruder
(CRTSE).
[0021] The term “activator” used herein refers to the substances that have a strong
activation effect of increasing the vulcanization speed in the cross-linking reaction
of rubbers. Activators are required to achieve the desired vulcanization and end-user
properties.the generally include both organic and inorganic components. The
inorganic component is generally zinc oxide. The organic components include
stearic acid, lauric acid, palmitic acid, and zinc salts of each of the foregoing.

[0022] The term “accelerator” used herein refers to the substances used with a cross-linking agent to increase the speed of vulcanization of rubber and enhance its physical properties. Examples include, but are not limited to, N-Cyclohexyl-2-benzothiazole sulfonamide (CBS), N-tert-butyl-2-benzothiazyl sulfonamide (TBBS).
[0023] The term “antioxidant” used herein refers to the substances that are used to protect rubber articles against the attack of oxygen. Examples include, but are not limited to, 2,2,4-trimethyl-1,2-dihydroquinoline (TMQ), N-1,3-dimethylbutyl)-N-phenyl-p-phenylenediamine (6PPD).
[0024] The term “antiozonant” used herein refers to the substances that prevent the degradation due to ozone cracking. Examples include, but are not limited to, ethylene di-urea, wax, and others.
[0025] The term “peptizer” used herein refers to the substances which break down
polymer chains and reduce rubber viscosity during its processing. Examples include,
but are not limited to, 2,2’-dibenzamidodiphenyldisulphide (DBD),
pentachlorothiophenol (PCTP) based.
[0026] The term “plasticizer” used herein refers to the substances added to rubber to make them soft, pliable and reduce its viscosity. Examples include, but are not limited to, dicarboxylic ester, tricarboxylic esters, adipates, sebacates, and maleates. [0027] The term “pre-vulcanization inhibitor” used herein refers to the substances added to rubber compounds to delay premature vulcanization during its processing. Examples include, but are not limited to, N-(Cyclohexylthio)phthalimide (CTP). [0028] The term “filler” used herein refers to substances added to resins or binders in order to reduce cost and modify physical, thermal, mechanical and electrical properties such as bulk, strength, viscosity, weight, opacity, etc. Examples include silica, carbon black and others.
[0029] The term “curative” used herein refers to substances that can form chemical bonds between two molecular chains by a chemical reaction. This leads to cross-linking of the molecular chains and provides the substance produced therefrom, mechanical strength and resistance to heat, wear and attack by solvents. Examples include, but are not limited to, sulfur, peroxide, metal oxides.

[0030] The term “process aid” used herein refers to” used herein refers to chemical
additives added to rubber compounds to improve their processing and ease of
handling.
[0031] The term “additive” used herein refers to various substances added to rubber
including emulsifiers, dispersin agents, performance modifiers, antibacterial, and
antifouling agents. Examples include, but are not limited to, wood rosin,
microcrystalline wax.
[0032] The term “distributive mixing” used herein refers to homogenous mixing of
the at least one solid particulate matter in the polymer matrix of the at least one
granulated elastomer.
[0033] The term “50 % modulus” used herein refers to the force required for 50%
elongation of a material. It is measured in units of pressure as MPa or kg/cm2.
[0034] The term “tensile strength” used herein refers to the maximum load a material
can withstand before fracture, breaking, tearing, etc. It is measured in the units of
pressure as MPa or kg/cm2.
[0035] The term “elongation at break (%)” used herein refers to the percentage
change in elongation of a material at the instant of break.
[0036] The term “hardness shore A” used herein refers to the resistance of a material
to indentation. It is measured using a device called shore durometer. There are
several scales of a durometer out of which the two most common scales are A and
D. Scale A is used for measuring the hardness of soft materials, such as polymers,
elastomers and rubber.
[0037] The term “DIN abrasion index” used herein refers to abrasion resistance
index which is measured as a quality control oarameter to test the abrasion resistance
of rubber in practical use. The testing is performed by moving a test piece of rubber
across the surface of an abrasive sheet mounted on top of a revolving drum. This
method is mainly used for rubber samples to be used for making tires and parts of
tires, soles, conveyer/drive belts, hoses, and rubber floor coverings which undergo a
lot of stress in actual service.
[0038] 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, the screw speed of the extruder in the range of about 200–1000 should be interpreted to include not only the explicitly recited limits of about 200 to about 1000, but also to include sub-ranges, such as 205–1000, 200–950, and so forth, as well as individual amounts, including fractional amounts, within the specified ranges, such as 255.5 and 919.5, for example.
[0039] 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. All publications mentioned herein are incorporated herein by reference.
[0040] 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, compositions, and methods are clearly within the scope of the disclosure, as described herein.
[0041] As discussed in the background section, the rubber (elastomer) composites are prepared by a batch process in multiple steps. In order to overcome the limitations of the discontinuous process, many attempts have been made by the rubber industry to establish a continuous compounding process based on the different extrusion techniques. However, the foremost challenge by the conventional mixing and the extrusion process is to feed rubber in a bale form. Also, all the solid particulate matter including curatives are added step-by-step separately, as a result of which, the dispersion and distribution of the solid particulate matter inside the elastomer is very poor, thereby, prohibiting in achieving the final elastomer compound with desired properties. A separate mixer is required to add curatives like sulphur after extruder processing. For instance, according to the process deployed in KR100958128B1, the elastomer and at least one filler were first fed in an extruder, and the filler was

subsequently allowed to mix and disperse in the elastomer by the extruder, to obtain the rubber mixture. The rubber mixture was then allowed to cool and pass through the static mixer as connected to the extruder. All the additives (especially sulphur and vulcanization accelerator) were contacted with the rubber mixture in the static mixture, so as to obtain the rubber composition. Since the extruder processing was carried out at a higher temperature and curing at a lower temperature, therefore, the final rubber compound obtained, did not exhibit the desired properties neither the fillers such as carbon black were dispersed properly in the elastomer matrix. Also, separate apparatus are used for each step of the process, i.e. mixing, dispersion, cooling, and extrusion, etc. Therefore, the production of elastomer composite by the conventional methods is quite expensive and cumbersome.
[0042] To address the problems faced by the conventional methods for preparing the elastomer compound, the present disclosure discloses a single continuous extrusion process for preparing the elastomer compound. The process of the present disclosure, comprises the steps of mixing at least one granulated elastomer and at least one solid particulate matter including curatives to obtain a premix, and then allowing the premix to incorporate into the extruder using a gravimetric feeder, followed by its extrusion in a single step from the extruder run at the screw speed range of 200-1000 rpm. The premix is prepared at a temperature below 130oC to avoid pre-vulcanizaion of the elastomer compound. The final elastomer compound is extruded out continuously from the CRTSE at the rate of 5-20 kg/hr. The aspect of using a single apparatus, i.e. co-rotating twin-screw extruder (CRTSE), is to carry out the mixing and extrusion of the rubber mixture (including additives such as sulphur) from the extruder, simultaneously. Therefore, the process as disclosed herein, allows uniform dispersion and distribution of solid particulate matter inside the elastomer that helps in achieving the final elastomer compound with improved carbon black dispersion and superior tensile properties such as % modulus and hardness. Therefore, the present disclosure provides a very cost-effective and time-saving process for preparing an elastomer compound having high quality and a significant potential to meet the present industrial demands.

[0043] In an embodiment of the present disclosure, there is provided a method for continuously producing an elastomer compound, the method comprising: (a) mixing at least one granulated elastomer and at least one solid particulate matter to obtain a premix; and (b) feeding the premix in an extruder using a gravimetric feeder to obtain the elastomer compound, wherein the extruder has a screw speed in the range of 200 rpm - 1000 rpm. In another embodiment of the present disclosure, the extruder has a screw speed in the range of 250 rpm -950 rpm.
[0044] In an embodiment of the present disclosure, there is provided a method for continuously producing an elastomer compound, the method comprising: (a) mixing at least one granulated elastomer and at least one solid particulate matter at a temperature in the range of 85℃ - 120 ℃ to obtain a premix; and (b) feeding the premix in an extruder using a gravimetric feeder to obtain the elastomer compound, wherein the extruder has a screw speed in the range of 200 rpm - 1000 rpm. In another embodiment of the present disclosure, mixing the at least one granulated elastomer and at least one solid particulate matter is done at a temperature in the range of 90℃ - 110 ℃ to obtain a premix.
[0045] In an embodiment of the present disclosure, there is provided a method for continuously producing an elastomer compound, the method comprising: (a) mixing at least one granulated elastomer and at least one solid particulate matter to obtain a premix; and (b) feeding the premix in an extruder using a gravimetric feeder to obtain the elastomer compound, wherein the extruder has a screw speed in the range of 200 rpm - 1000 rpm, and wherein the at least one granulated elastomer is selected from the group consisting of natural rubber, styrene-butadiene rubber, butadiene rubber, and combinations thereof. In another embodiment of the present disclosure, the at least one granulated elastomer is natural rubber. In yet another embodiment of the present disclosure, the at least one granulated elastomer is styrene-butadiene rubber. In one another embodiment of the present disclosure, the at least one granulated elastomer butadiene rubber.
[0046] In an embodiment of the present disclosure, there is provided a method for continuously producing an elastomer compound, the method comprising: (a) mixing at least one granulated elastomer and at least one solid particulate matter to obtain a

premix; and (b) feeding the premix in an extruder using a gravimetric feeder to obtain the elastomer compound, wherein the extruder has a screw speed in the range of 200 rpm - 1000 rpm, and the premix is prepared at a temperature above 80oC and below 130oC.
[0047] In an embodiment of the present disclosure, there is provided a method for continuously producing an elastomer compound, the method as described herein, wherein the mixing at least one granulated elastomer and at least one solid particulate matter is carried out at a mixing speed in the range of 500-1000 rpm for a time period in the range of 5-20 minutes. In another embodiment of the present disclosure, the mixing at least one granulated elastomer and at least one solid particulate matter is carried out at a mixing speed in the range of 600-900 rpm for a time period in the range of 7-15 minutes. In one another embodiment of the present disclosure, the mixing at least one granulated elastomer and at least one solid particulate matter is carried out for a time period in the range of 9-12 minutes. In yet another embodiment of the present disclosure, the mixing at least one granulated elastomer and at least one solid particulate matter is carried out for a time period of 10 minutes. [0048] In an embodiment of the present disclosure, there is provided a method for continuously producing an elastomer compound, the method as described herein, wherein the feeding the premix in an extruder using a gravimetric feeder to obtain the elastomer compound is carried out at a temperature in the range of 60 oC - 120 oC. In another embodiment of the present disclosure, the feeding the premix in an extruder using a gravimetric feeder to obtain the elastomer compound is carried out at a temperature in the range of 70 oC - 120 oC. In yet another embodiment of the present disclosure, the feeding the premix in an extruder using a gravimetric feeder to obtain the elastomer compound is carried out at a temperature in the range of 80 oC - 100 oC.
[0049] In an embodiment of the present disclosure, there is provided a method for continuously producing an elastomer compound, the method comprising: (a) mixing at least one granulated elastomer and at least one solid particulate matter to obtain a premix; and (b) feeding the premix in an extruder using a gravimetric feeder to obtain the elastomer compound, wherein the extruder has a screw speed in the range of 200

rpm - 1000 rpm, and wherein the at least one solid particulate matter is selected from the group fillers, peptizer, plasticizer, curatives, antioxidant, antiozonant, pre-vulcanization inhibitor, process aids, additives, or combinations thereof. In another embodiment of the present disclosure, fillers are selected from the group carbon black, silica, talc, clay, calcium carbonate, carbon fiber, glass, polyester, polyamide, natural fibers, maize starch, or combinations thereof.
[0050] In an embodiment of the present disclosure, there is provided a method for continuously producing an elastomer compound, the method comprising: (a) mixing at least one granulated elastomer and at least one solid particulate matter to obtain a premix; and (b) feeding the premix in an extruder using a gravimetric feeder to obtain the elastomer compound, wherein the extruder has a screw speed in the range of 200 rpm - 1000 rpm, and wherein the extruder is selected from the group consisting of co-rotating twin-screw extruder (CRTSE), counter-rotating twin screw extruder. In another embodiment of the present disclosure, the extruder is CRTSE. In yet another embodiment of the present disclosure, the extruder is counter-rotating twin-screw extruder.
[0051] In an embodiment of the present disclosure, there is provided a method for continuously producing an elastomer compound, the method comprising: (a) mixing at least one granulated elastomer and at least one solid particulate matter to obtain a premix; and (b) feeding the premix in an extruder using a gravimetric feeder to obtain the elastomer compound, wherein the extruder has a screw speed in the range of 200 rpm - 1000 rpm, and wherein the method provides distributive mixing of the at least one solid particulate matter in the at least one granulated elastomer.
[0052] In an embodiment of the present disclosure, there is provided a method for continuously producing an elastomer compound, the method comprising: (a) mixing at least one granulated elastomer and at least one solid particulate matter to obtain a premix; and (b) feeding the premix in an extruder using a gravimetric feeder to obtain the elastomer compound, wherein the extruder has a screw speed in the range of 200 rpm - 1000 rpm, the at least one granulated elastomer is selected from the group consisting of natural rubber, styrene-butadiene rubber, butadiene rubber, and combinations thereof, and the at least one solid particulate matter is selected from

the group fillers, peptizer, plasticizer, curatives, antioxidant, antiozonant, pre-vulcanization inhibitor, process aids, additives, or combinations thereof. [0053] In an embodiment of the present disclosure, there is provided a method for continuously producing an elastomer compound, the method comprising: (a) mixing at least one granulated elastomer and at least one solid particulate matter to obtain a premix; and (b) feeding the premix in an extruder using a gravimetric feeder to obtain an elastomer compound, wherein the extruder has a screw speed in the range of 200 rpm - 1000 rpm, the at least one granulated elastomer is selected from the group consisting of natural rubber, styrene-butadiene rubber, butadiene rubber, and combinations thereof, the at least one solid particulate matter is selected from the group fillers, peptizer, plasticizer, curatives, antioxidant, antiozonant, pre-vulcanization inhibitor, process aids, additives, or combinations thereof, and the extruder is co-rotating twin-screw extruder (CRTSE).
[0054] In an embodiment of the present disclosure, there is provided a method for continuously producing an elastomer compound, the method comprising: (a) mixing at least one granulated elastomer and at least one solid particulate matter to obtain a premix; and (b) feeding the premix in an extruder using a gravimetric feeder to obtain the elastomer compound, wherein the extruder has a screw speed in the range of 200 rpm - 1000 rpm, the at least one granulated elastomer is selected from the group consisting of natural rubber, styrene-butadiene rubber, butadiene rubber, and combinations thereof, the at least one solid particulate matter is selected from the group fillers, peptizer, plasticizer, curatives, antioxidant, antiozonant, pre-vulcanization inhibitor, process aids, additives, or combinations thereof, and the method provides distributive mixing of the at least one solid particulate matter in the at least one granulated elastomer.
[0055] In an embodiment of the present disclosure, there is provided a method for continuously producing an elastomer compound, the method comprising: (a) mixing at least one granulated elastomer and at least one solid particulate matter to obtain a premix; and (b) feeding the premix in an extruder using a gravimetric feeder to obtain the elastomer compound, wherein the extruder has a screw speed in the range of 200 rpm - 1000 rpm, the at least one granulated elastomer is selected from the group

consisting of natural rubber, styrene-butadiene rubber, butadiene rubber, and combinations thereof, the at least one solid particulate matter is selected from the group consisting of fillers, peptizer, plasticizer, curatives, antioxidant, antiozonant, pre-vulcanization inhibitor, process aids, additives, and combinations thereof, and the extruder is co-rotating twin-screw extruder (CRTSE), and the method provides distributive mixing of the at least one solid particulate matter in the at least one granulated elastomer.
[0056] In an embodiment of the present disclosure, there is provided a method for continuously producing an elastomer compound, the method comprising: (a) mixing at least one granulated elastomer and at least one solid particulate matter at a mixing speed in the range of 500-1000 rpm for a time period in the range of 8-12 minutes to obtain a premix; and (b) feeding the premix in an extruder using a gravimetric feeder at a temperature in the range of 60 oC - 120 oC to obtain the elastomer compound, wherein the extruder has a screw speed in the range of 200 rpm - 1000 rpm, the at least one granulated elastomer is natural rubber, the at least one solid particulate matter is a combination of fillers, peptizer, curatives, antioxidant, antiozonant, pre-vulcanization inhibitor, process aids, and additives, and the extruder is co-rotating twin-screw extruder (CRTSE).
[0057] In an embodiment of the present disclosure, there is provided an elastomer compound obtained by the method comprising: (a) mixing at least one granulated elastomer and at least one solid particulate matter to obtain a premix; and (b) feeding the premix in an extruder using a gravimetric feeder to obtain the elastomer compound, wherein the extruder has a screw speed in the range of 200 rpm - 1000 rpm.
[0058] In an embodiment of the present disclosure, there is provided an elastomer compound obtained by the method comprising: (a) mixing at least one granulated elastomer and at least one solid particulate matter to obtain a premix; and (b) feeding the premix in an extruder using a gravimetric feeder to obtain the elastomer compound, wherein the extruder has a screw speed in the range of 200 rpm - 1000 rpm, and wherein the at least one granulated elastomer is selected from the group

consisting of natural rubber, styrene-butadiene rubber, butadiene rubber, and combinations thereof.
[0059] In an embodiment of the present disclosure, there is provided an elastomer compound obtained by the method, said method comprising: (a) mixing at least one granulated elastomer and at least one solid particulate matter to obtain a premix; and (b) feeding the premix in an extruder using a gravimetric feeder to obtain the elastomer compound, wherein the extruder has a screw speed in the range of 200 rpm - 1000 rpm, and wherein the at least one solid particulate matter is selected from the group fillers, peptizer, plasticizer, curatives, antioxidant, antiozonant, pre-vulcanization inhibitor, process aids, additives, and combinations thereof. [0060] In an embodiment of the present disclosure, there is provided an elastomer compound obtained by the method, said method comprising: (a) mixing at least one granulated elastomer and at least one solid particulate matter to obtain a premix; and (b) feeding the premix in an extruder using a gravimetric feeder to obtain the elastomer compound, wherein the extruder has a screw speed in the range of 200 rpm - 1000 rpm, the extruder has a screw speed in the range of 200 rpm - 1000 rpm, and the extruder is selected from the group consisting of co-rotating twin-screw extruder (CRTSE), and counter-rotating twin screw extruder.
[0061] In an embodiment of the present disclosure, there is provided an elastomer compound obtained by the method, said method comprising: (a) mixing at least one granulated elastomer and at least one solid particulate matter to obtain a premix; and (b) feeding the premix in an extruder using a gravimetric feeder to obtain the elastomer compound, wherein the extruder has a screw speed in the range of 200 rpm - 1000 rpm, and wherein the method provides distributive mixing of the at least one solid particulate matter in the at least one granulated elastomer.
[0062] In an embodiment of the present disclosure, there is provided an elastomer compound obtained by the method, said method comprising: (a) mixing at least one granulated elastomer and at least one solid particulate matter selected from the group fillers, peptizer, plasticizer, curatives, antioxidant, antiozonant, pre-vulcanization inhibitor, process aids, additives, and combinations thereof to obtain a premix; and (b) feeding the premix in an extruder using a gravimetric feeder to obtain the

elastomer compound, wherein the extruder has a screw speed in the range of 200 rpm - 1000 rpm, and wherein the at least one granulated elastomer is selected from the group consisting of natural rubber, styrene-butadiene rubber, butadiene rubber, and combinations thereof, the extruder is co-rotating twin-screw extruder (CRTSE), and the method provides distributive mixing of the at least one solid particulate matter in the at least one granulated elastomer.
[0063] In an embodiment of the present disclosure, there is provided a method for continuously producing an elastomer compound, the method comprising: (a) mixing at least one granulated elastomer and at least one solid particulate matter to obtain a premix; and (b) feeding the premix in an extruder using a gravimetric feeder to obtain the elastomer compound, wherein the extruder has a screw speed in the range of 200 rpm - 1000 rpm, and wherein the extruder has kneading block elements in the range of 10-90%.
[0064] In an embodiment of the present disclosure, there is provided a vulcanizable elastomeric article comprising an elastomer compound obtained by the method, said method comprising: (a) mixing at least one granulated elastomer and at least one solid particulate matter to obtain a premix; and (b) feeding the premix in an extruder using a gravimetric feeder to obtain the elastomer compound, wherein the extruder has a screw speed in the range of 200 rpm - 1000 rpm, and wherein the vulcanizable elastomeric article is selected from the group tires, hose, conveyor belt, boat, dock fenders, mats, hot water bags, O-rings, rail pads, rubber rollers, or the like. [0065] Although the subject matter has been described in considerable detail with reference to certain examples and implementations thereof, other implementations are possible.
EXAMPLES
[0066] The disclosure will now be illustrated with working 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 compositions, 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.
Example 1
Process for preparing the elastomer compound
[0067] The natural rubber in the form of solid granules was prepared from ribbed smoked sheets grade 4 (RSS4) in a co-rotating twin screw extruder (CRTSE) using an under water pelletizer, to obtain the granulated natural rubber (granulated elastomer). The granulated elastomer was mixed with the solid particulate matter such as fillers, peptizer, curatives, antioxidant, antiozonant, pre-vulcanization inhibitor, process aids, additives, in a high-speed mixer at a temperature above 80oC with a speed in a range of 500-1000 rpm for about 10 minutes, to obtain a premix. The premix was then incorporated in the co-rotating twin-screw extruder (CRTSE) using a single gravimetric feeder and was allowed to mix at a low temperature of 60-120°C. The schematic diagram for the preparation of elastomer compound in the CRTSE is illustrated in Figure 1. The various temperatures maintained at different barrels of the CRTSE is depicted in a tabular form in Table 1 below. The screw speed of CRTSE during the whole process ranged between 200-1000 rpm. The torque was maintained in the range of 40-50%. This final mixing of the premix having granulated elastomer and solid particulate matter was followed simultaneously by extrusion of the final compound as the elastomer compound from the extruder. The output of the CRTSE that depends on the size of the machine (barrel diameter), reached in the range of 5-20 kg/h.
Table 1

Temperature (oC) 120oC 110oC 100oC 90oC 80oC B6 80oC B7 70oC B8 70oC B9 60oC B10 60oC B11
Barrel B2 B3 B4 B5

[0068] The mixing of the granulated elastomer and the solid particulate matter including curatives in the extruder at a lower temperature was done to avoid any vulcanization during mixing. Therefore, all the steps of mixing and extrusion were performed simultaneously by a continuous process using a single apparatus (CRTSE). In this elastomeric compound (final compound), the solid particulate matter were uniformly dispersed and distributed inside the granulated elastomer.
Example 2
Working elastomer compound
[0069] The composition of the elastomer compound as prepared by the
aforementioned process described in Example 1, is provided in Table 2 below.
Table 2

Category Solid
particulate
matter Component phr
Granulated elastomer Natural rubber (NR) 100
Solid
particulate
matter Peptizer 2,2’-dibenzamidodiphenyldisulphide (DBD) 0.06

Activator Stearic Acid 2

Zinc oxide 3.5

Additive Wood rosin 1

Antiozonant Wax 1

Antioxidant 2,2,4-trimethyl-1,2-dihydroquinoline (TMQ) 0.7

Filler Carbon black N134 44

Pre-vulcanization inhibitor N-(Cyclohexylthio)phthalimide (CTP) 0.25

Curatives Sulphur 2

Accelerator CBS 0.75
[0070] This elastomer compound (obtained as a black colored compound shown in Figure 2) was compared with a control compound for various tensile properties including % modulus, tensile strength, hardness shore A and DIN abrasion index as

shown in Table 3 below. The control compound was prepared in an intermix by a conventional method. It can be observed from the data revealed in Table 3 that the present elastomer compound showed significant improvement tensile properties such as 50% modulus, 300% modulus, hardness shore A and carbon black dispersion. Hence, it was evidently clear that the present method was highly efficient in providing an elastomer compound with superior properties and high quality.
Table 3

Properties Control compound Elastomer compound
Specific gravity 1.0981 1.0928
Tensile properties
50 % Modulus (kg/cm2) 12.59 13.75
300 % Modulus (kg/cm2) 117.46 122.89
Tensile strength (kg/cm2) 300.61 275.79
Elongation at break (%) 586.6 543.7
Hardness (Shore A) 64.0 65.9
Carbon black dispersion (Z-Value) 83.0 86.4
DIN Abrasion Index (%) 133.44 117.23
Example 3
Studies at varied temperature and screw speed
[0071] Deviating from the disclosed temperature range and a screw speed of the
extruder of the process of the present disclosure was found having a direct impact on
the properties of the elastomer compound. For instance:
(b) Deviating from the screw speed of the extruder (200 rpm -1000 rpm) [0072] When the speed of the screws inside the extruder was below 200 rpm, the shear force generated was not sufficient to allow proper mixing of the granulated elastomer with the solid particulate matter. Also, extrusion of the elastomer compound out of the extruder with such insufficient shear force was difficult.

[0073] Further, when the speed of the extruder was above 1000 rpm, the shear force was very high that lead to the degradation of the polymer and high heat was generated that led to curing of the material inside the extruder.
Advantages of the present disclosure
[0074] The above-mentioned implementation examples as described on this subject matter and its equivalent thereof have many advantages, including those which are described.
[0075] The present disclosure discloses a method for continuously producing an elastomer compound, the method comprising: (a) mixing the at least one granulated elastomer and at least one solid particulate matter to obtain a premix; and (b) feeding the premix in an extruder using a gravimetric feeder to obtain the elastomer compound, wherein the extruder has a screw speed in the range of 200 rpm - 1000 rpm. The step of mixing followed by extrusion of the final compound from the extruder at a lower temperature helps to avoid any vulcanization during mixing. The higher amount of shear exerted inside the granulated elastomer by the CRTSE allows complete dispersion and distribution of solid particulate matter inside the granulated elastomer that helps to achieve the final elastomer compound with significantly improved tensile properties. The elastomer compound as obtained from the process as disclosed herein, can be utilized for preparing the vulcanizable elastomeric article such as tires, hose, conveyor belt, boat, dock fenders, mats, hot water bags, O-rings, rail pads, rubber rollers or the like. Overall, the present disclosure discloses a single-stage, continuous mixing process that is both cost-effective and time-saving. [0076] Although the subject matter has been described in considerable detail with reference to certain embodiments thereof, other embodiments are possible. As such, the spirit and scope of the disclosure should not be limited to the description of the embodiments contained herein.

I/We Claim:
1) A method for continuously producing an elastomer compound, the method
comprising:
(a) mixing at least one granulated elastomer and at least one solid particulate matter to obtain a premix; and
(b) feeding the premix in an extruder using a gravimetric feeder to obtain the elastomer compound, wherein the extruder has a screw speed in the range of 200 rpm - 1000 rpm.

2) The method as claimed in claim 1, wherein the mixing at least one granulated elastomer and at least one solid particulate matter is carried out at a mixing speed in the range of 500-1000 rpm for a time period in the range of 5-20 minutes.
3) The method as claimed in claim 1, wherein the feeding the premix in an extruder using a gravimetric feeder to obtain the elastomer compound is carried out at a temperature in the range of 60 oC - 120 oC.
4) The method as claimed in claim 1, wherein the at least one granulated elastomer is selected from the group consisting of natural rubber, styrene-butadiene rubber, butadiene rubber, and combinations thereof.
5) The method as claimed in claim 1, wherein the at least one solid particulate matter is selected from the group fillers, peptizer, plasticizer, curatives, antioxidant, antiozonant, pre-vulcanization inhibitor, process aids, additives, and combinations thereof.
6) The method as claimed in claim 1, wherein the extruder is selected from the group consisting of co-rotating twin-screw extruder (CRTSE) and counter-rotating twin screw extruder.
7) The method as claimed in claim 1, wherein the method provides distributive mixing of the at least one solid particulate matter in the at least one granulated elastomer.
8) An elastomer compound obtained by the method as claimed in any one of the claims 1-7.