WO2021124350A1

WO2021124350A1 - Granulation of soft elastomer

Info

Publication number: WO2021124350A1
Application number: PCT/IN2020/051028
Authority: WO
Inventors: Sambhu BHADRA; Sujith Sasidharan Nair
Original assignee: Ceat Limited
Priority date: 2019-12-16
Filing date: 2020-12-14
Publication date: 2021-06-24

Abstract

The present disclosure relates to a process for obtaining granulated soft elastomer, said process comprising: a) providing a soft elastomer strand in an extruder; b) heating the soft elastomer strand to obtain a heated soft elastomer; c) extruding the heated soft elastomer through a die to obtain an extruded soft elastomer strand; d) pelletizing the extruded soft elastomer strand in an underwater pelletizer to obtain a soft elastomer pellet; and e) contacting the soft elastomer pellet with at least one surfactant to obtain the granulated soft elastomer, wherein heating the soft elastomer strand to obtain the heated soft elastomer is done at a temperature in the range of 70-150℃, and the at least one surfactant has a concentration in the range of 0.1-20%.

Description

GRANULATION OF SOFT ELASTOMER

FIELD OF INVENTION

[0001] The subject matter disclosed here relates to the field of soft elastomers and in particular relates to the field of granulation of soft elastomers.

BACKGROUND OF THE INVENTION

[0002] Soft Elastomer granulation has important applications in processes such as dissolving, extruding and mixing. In these processes, unvulcanized elastomer, either in the form of a compound or raw material can be used. The main applications of granular soft elastomers are in the manufacture of adhesives and sealants, paints, oil lubricants, modified bitumen and modified polymers. The granular feedstock can be used in various equipment, such as, extruders, continuous mixers, open or internal mills. [0003] Many equipment, such as single, twin, multi screw extruders can intake mainly liquid, powder or granules, but not lump or bale. Soft elastomers, such as natural rubber (NR), styrene butadiene rubber (SBR), butadiene rubber (BR) are generally available in form of bale. Bale form is difficult to process in extruders so as to form powder or granules as these materials are soft and sticky. [0004] There has been constant effort in this field of invention for obtaining granulated forms of rubber/soft elastomers for its use in various applications. JP2018021150 A discloses a process for producing rubber pellets comprising a rubber component and a crosslinking agent. W02006084698A2 discloses a process for granulation of olefin based polymer substrate using a twin screw extruder. [0005] Although a lot of efforts have been made to provide the process for obtaining soft elastomer granules, there is still a need in the state of art to provide a process for obtaining soft elastomer granules or pellets that should have easy processability in further applications. SUMMARY OF THE INVENTION [0006] In an aspect of the present invention, there is disclosed a process for obtaining granulated soft elastomer, said process comprising: a) providing a soft elastomer strand in an extruder; b) heating the soft elastomer strand to obtain a heated soft elastomer; c) extruding the heated soft elastomer through a die to obtain an extruded soft elastomer strand; d) pelletizing the extmded soft elastomer strand in an underwater pelletizer to obtain a soft elastomer pellet; and e) contacting the soft elastomer pellet with at least one surfactant to obtain the granulated soft elastomer, wherein heating the soft elastomer strand to obtain the heated soft elastomer is done at a temperature in the range of 70-150 C, and wherein the at least one surfactant has a concentration in the range of 0.1-20%. [0007] In another aspect of the present invention, there is disclosed a granulated soft elastomer obtained from the process, said process comprising: a) providing a soft elastomer strand in an extruder; b) heating the soft elastomer strand to obtain a heated soft elastomer; c) extruding the heated soft elastomer through a die to obtain an extruded soft elastomer strand; d) pelletizing the extruded soft elastomer strand in an underwater pelletizer to obtain a soft elastomer pellet; and e) contacting the soft elastomer pellet with at least one surfactant to obtain the granulated soft elastomer, wherein heating the soft elastomer strand to obtain the heated soft elastomer is done at a temperature in the range of 70-150°C, and wherein the at least one surfactant has a concentration in the range of 0.1-20%. [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 DRAWINGS [0009] The detailed description is described with reference to the accompanying figures. In the figures, the left-most digit(s) of a reference number identifies the figure in which the reference number first appears. The same numbers are used throughout the drawings to reference like features and components.

[0010] Figure 1 is the image of the soft elastomer granules, in accordance with an implementation of the present subject matter.

DETAILED DESCRIPTION OF THE INVENTION

[0011] 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 [0012] 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.

[0013] 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. [0014] 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”.

[0015] 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.

[0016] The term “including” is used to mean “including but not limited to”. “Including” and “including but not limited to” are used interchangeably. [0017] 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 temperature range of about 70-150°C should be interpreted to include not only the explicitly recited limits of about 70°C to about 150°C but also to include sub-ranges, such as 75-150°C, 70-145°C and so forth, as well as individual amounts, including fractional amounts, within the specified ranges, such as 70.5°C, and 149.2°C for example. [0018] The term “at least one” is used to mean one or more and thus includes individual components as well as mixtures/combinations.

[0019] The term “rpm” used herein refers to rotations/revolutions per minute, 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 an extruder machine and an underwater pelletizer.

[0020] The term “soft elastomer” refers to a polymeric material which possesses viscoelastic property and the polymer may be natural or synthetic. The soft elastomer refers to natural or synthetic rubber. In the present disclosure the term soft elastomer refers to natural rubber, styrene butadiene rubber, butadiene rubber, or combinations thereof. The terms “soft elastomer”, “elastomer” may be used interchangeably. RSS4 used in the present disclosure refers to ribbed smoked sheet, produced from latex of natural rubber. [0021] The term “extruder” refers to a machine comprising a screw and a die through which any material is passed, and the material attains the specific profile same as the die. In the present disclosure, extruder is used to obtain the soft elastomer strand. The elastomer is made to pass through the extruder which rotates at a specific speed and propels through the die of the desired shape. Also, the extruder operates at a temperature range which heats the elastomer and thereby enabling the formation of desired shaped elastomer i.e. strands or strips or tubes or strings or bars. The extruder may include but not limited to twin screw extruder, co-rotating twin screw extruder, single screw extruder, counter rotating twin screw extruder and so on.

[0022] The term “underwater pelletizer” refers to pelletizer which can pelletize the rubber, wherein rubber strand comes out of the extruder directly enter into underwater pelletizer in water environment and becomes colder and harder and the knife in the pelletizer cuts the strand into granules/pellets in presence of water. Any pelletizer cannot be used as hot rubber strand is very soft like paste, which is difficult to cut and even if it can be cut, granules will stick together again due to sticky nature of the soft and hot rubber. Hence in the present disclosure the underwater pelletizer is utilized to obtain non-sticky soft elastomer granules.

[0023] The term “surfactant” refers to a chemical substance that alters interfacial properties by absorbing the boundary between two immiscible phases. These surfactants are also called as surface active agents, stabilize the interface and also provides non-stickiness on the interface. In the present disclosure, surfactant refers to nonionic surfactants, cationic surfactant and anionic surfactant which imparts non stickiness in the soft elastomer pellets or granules. [0024] The term “nonionic surfactant” used herein refers to are surfactants that do not dissociate into ions in aqueous solutions, and they are subclassified depending on the type of their hydrophilic/lipophilic group. Nonionic surfactants having a hydrophilic group are referred to as “water soluble nonionic surfactant” and nonionic surfactants having a lipophilic group are referred to as “oil soluble nonionic surfactant”. Non limiting examples of non-ionic surfactants include ethoxylated and alkoxylated fatty acids, ethoxylated amines, ethoxylated alcohol, alkyl and nonyl- phenol ethoxylates, ethoxylated sorbitan esters,

[0025] The term “cationic surfactant” used herein refers to surfactants comprising hydrophilic group having positive charge. The positive charge may be permanent or may exist only at a specific pH or when contact with water based on pH. Non limiting examples of cationic surfactants include triethylamine hydrochloride or octenidine dihydrochloride, cetrimonium bromide, cetylpyridinium chloride, dimethyldioctadecylammonium chloride, benzethonium chloride. [0026] The term “anionic surfactants” refers to surfactant which are negatively charged permanently or at a certain pH or when contact with water. In the present disclosure, anionic surfactants include but not limited to ammonium laurate, ammonium lauryl sulfate, sodium laureth sulfate, sodium lauryl sarcosinate, sodium myreth sulfate, sodium pareth sulfate, sodium stearte, sodium lauryl sulfate, a olefin sulfonate, and ammonium laureth sulfate.

The term “at least one surfactant has a concentration in the range of 0.1-20%” refers to the weight percentage range of a surfactant in the surfactant solution. For example, 0.1% of at least one surfactant refers to 0.1% by weight of surfactant present in the surfactant solution. Similarly 5% of surfactant solution refers to the 5% by weight of surfactant present in the solution of surfactant.

[0027] 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.

[0028] 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.

[0029] Various synthetic polymeric materials, such as, styrene based copolymers, thermoplastics have been pelletized and made into granules. Existing granulation process includes extrusion of polymeric components along with additives such as partitioning agents, tackifying resins, plasticizers etc. The additives to the rubber components decreased the stickiness of the mbber and thereby enhanced the granulation process. But such rubber granules obtained, were intended only for a particular purpose based on the additives used. Soft elastomers are the toughest of the material to be made into granules or pellets, and different attempts are being made to achieve granulated soft elastomer. Various non-rubber components are usually added in the soft elastomer so as to have granulated soft elastomer. These non-rubber components directly affect the quality of rubber. The present disclosure thus provides a fast, clean, high-quality process for obtaining granulated soft elastomer from soft elastomer, the process comprises a) providing a soft elastomer strand in an extruder; b) heating the soft elastomer strand to obtain a heated soft elastomer; c) extruding the heated soft elastomer through a die to obtain an extruded soft elastomer strand; d) pelletizing the extruded soft elastomer strand in an underwater pelletizer to obtain a soft elastomer pellet; and e) contacting the soft elastomer pellet with at least one surfactant to obtain the granulated soft elastomer, wherein heating the soft elastomer strand to obtain the heated soft elastomer is done at a temperature in the range of 70- 150°C, and wherein the at least one surfactant has a concentration in the range of 0.1- 20%. [0030] The process of the present disclosure provides a soft elastomer granulation process which provides granulated soft elastomer with smooth surface, round, no adhesion of the elastomer particles. The process is simple in operation, provides good solidification effect and has low production costs. [0031] In an embodiment of the present disclosure, there is provided a process for obtaining granulated soft elastomer, said process comprising: a) providing a soft elastomer strand in an extruder; b) heating the soft elastomer strand to obtain a heated soft elastomer; c) extruding the heated soft elastomer through a die to obtain an extruded soft elastomer strand; d) pelletizing the extruded soft elastomer strand in an underwater pelletizer to obtain a soft elastomer pellet; and e) contacting the soft elastomer pellet with at least one surfactant to obtain the granulated soft elastomer, wherein heating the soft elastomer strand to obtain the heated soft elastomer is done at a temperature in the range of 70-150 C, and wherein the at least one surfactant has a concentration in the range of 0.1-20%. [0032] In an embodiment of the present disclosure, there is provided a process for obtaining granulated soft elastomer, wherein heating the soft elastomer strand to obtain the heated soft elastomer is done at a temperature in the range of 70-150°C. In another embodiment of the present disclosure, wherein heating the soft elastomer strand to obtain the heated soft elastomer is done at a temperature in the range of 80- 130°C. In yet another embodiment of the present disclosure, wherein heating the soft elastomer strand to obtain the heated soft elastomer is done at a temperature in the range of 90-110°C . In one another embodiment of the present disclosure, wherein heating the soft elastomer strand to obtain the heated soft elastomer is done at a temperature of 100 °C. [0033] In an embodiment of the present disclosure, there is provided a process for obtaining granulated soft elastomer, wherein the at least one surfactant has a concentration in the range of 0.1-20%. In another embodiment of the present disclosure, wherein the at least one surfactant has a concentration in the range of 1- 15%. In yet another embodiment of the present disclosure, wherein the at least one surfactant has a concentration in the range of 4-12%. In one another embodiment of the present disclosure, wherein the at least one surfactant has a concentration of 5%. [0034] In an embodiment of the present disclosure, there is provided a process for obtaining granulated soft elastomer as described herein, wherein the extruding is carried out with a screw speed in the range of 200-1000 rpm. In another embodiment of the present disclosure, wherein the extruding is carried out with a screw speed in the range of 300-800 rpm. In yet another embodiment of the present disclosure, wherein the extruding is carried out with a screw speed of 400 rpm. [0035] In an embodiment of the present disclosure, there is provided a process for obtaining granulated soft elastomer, said process comprising: a) providing a soft elastomer strand in an extruder; b) heating the soft elastomer strand to obtain a heated soft elastomer; c) extruding the heated soft elastomer through a die to obtain an extruded soft elastomer strand; d) pelletizing the extruded soft elastomer strand in an underwater pelletizer to obtain a soft elastomer pellet; and e) contacting the soft elastomer pellet with at least one surfactant to obtain the granulated soft elastomer, wherein heating the soft elastomer strand to obtain the heated soft elastomer is done at a temperature in the range of 70-150°C, the at least one surfactant has a concentration in the range of 0.1-20%, the extruding is carried out with a screw speed in the range of 200-1000 rpm and the extrusion is carried out at a temperature in the range of 70-200°C.

[0036] In an embodiment of the present disclosure, there is provided a process for obtaining granulated soft elastomer as described herein, wherein the pelletizing is carried out at a temperature in the range of 100-150°C.In another embodiment of the present disclosure, wherein the pelletizing is carried out at a temperature in the range of 110-140 °dh yet another embodiment of the present disclosure, wherein the pelletizing is carried out at a temperature in the range of 120-130 °Oi one another embodiment of the present disclosure, wherein the pelletizing is carried out at a temperature of 100°C

[0037] In an embodiment of the present disclosure, there is provided a process for obtaining granulated soft elastomer, said process comprising: a) providing a soft elastomer strand in an extruder; b) heating the soft elastomer strand to obtain a heated soft elastomer; c) extruding the heated soft elastomer through a die to obtain an extruded soft elastomer strand; d) pelletizing the extruded soft elastomer strand in an underwater pelletizer to obtain a soft elastomer pellet; and e) contacting the soft elastomer pellet with at least one surfactant to obtain the granulated soft elastomer, wherein heating the soft elastomer strand to obtain the heated soft elastomer is done at a temperature in the range of 70-150°C, the at least one surfactant has a concentration in the range of 0.1-20%, and the pelletizing is carried out at a temperature in the range of 100-150°C.

[0038] In an embodiment of the present disclosure, there is provided a process for obtaining granulated soft elastomer as described herein, wherein the underwater pelletizer has a speed in the range of 200-2000 rpm. In another embodiment of the present disclosure, wherein the underwater pelletizer has a speed in the range of 400- 1800 rpm. In yet another embodiment of the present disclosure, wherein the underwater pelletizer has a speed in the range of 600-1500 rpm. In one another embodiment of the present disclosure, wherein the underwater pelletizer has a speed of 1300 rpm.

[0039] In an embodiment of the present disclosure, there is provided a process for obtaining granulated soft elastomer, said process comprising: a) providing a soft elastomer strand in an extruder; b) heating the soft elastomer strand to obtain a heated soft elastomer; c) extruding the heated soft elastomer through a die to obtain an extruded soft elastomer strand; d) pelletizing the extruded soft elastomer strand in an underwater pelletizer to obtain a soft elastomer pellet; and e) contacting the soft elastomer pellet with at least one surfactant to obtain the granulated soft elastomer, wherein heating the soft elastomer strand to obtain the heated soft elastomer is done at a temperature in the range of 70-150°C, and wherein the at least one surfactant has a concentration in the range of 0.1-20%, wherein the underwater pelletizer has a speed in the range of 200-2000 rpm. [0040] In an embodiment of the present disclosure, there is provided a process for obtaining granulated soft elastomer, said process comprising: a) providing a soft elastomer strand in an extruder; b) heating the soft elastomer strand to obtain a heated soft elastomer; c) extruding the heated soft elastomer through a die to obtain an extruded soft elastomer strand; d) pelletizing the extruded soft elastomer strand in an underwater pelletizer to obtain a soft elastomer pellet; and e) contacting the soft elastomer pellet with at least one surfactant to obtain the granulated soft elastomer, wherein heating the soft elastomer strand to obtain the heated soft elastomer is done at a temperature in the range of 70-150°C, wherein the at least one surfactant has a concentration in the range of 0.1-20%, the extruding is carried out with a screw speed in the range of 200-1000 rpm, the pelletizing is carried out at a temperature in the range of 100-150°C, the underwater pelletizer has a speed in the range of 200-2000 rpm and the extrusion is carried out at a temperature in the range of 70-200°C.

[0041] In an embodiment of the present disclosure, there is provided a process for obtaining granulated soft elastomer as described herein, wherein the soft elastomer is selected from the group consisting of natural rubber, styrene butadiene rubber, butadiene rubber and combinations thereof.

[0042] In an embodiment of the present disclosure, there is provided a process for obtaining granulated soft elastomer, said process comprising: a) providing a soft elastomer strand in an extruder; b) heating the soft elastomer strand to obtain a heated soft elastomer; c) extruding the heated soft elastomer through a die to obtain an extruded soft elastomer strand; d) pelletizing the extruded soft elastomer strand in an underwater pelletizer to obtain a soft elastomer pellet; and e) contacting the soft elastomer pellet with at least one surfactant to obtain the granulated soft elastomer, wherein heating the soft elastomer strand to obtain the heated soft elastomer is done at a temperature in the range of 70-150°C, the at least one surfactant has a concentration in the range of 0.1-20%, and the soft elastomer is natural rubber.

[0043] In an embodiment of the present disclosure, there is provided a process for obtaining granulated soft elastomer as described herein, wherein the at least one surfactant is selected from the group consisting of cationic surfactant, anionic surfactant, non-ionic surfactant, and combinations thereof.

[0044] In an embodiment of the present disclosure, there is provided a granulated soft elastomer obtained from the process comprising: a) providing a soft elastomer strand in an extruder; b) heating the soft elastomer strand to obtain a heated soft elastomer; c) extruding the heated soft elastomer through a die to obtain an extruded soft elastomer strand; d) pelletizing the extruded soft elastomer strand in an underwater pelletizer to obtain a soft elastomer pellet; and e) contacting the soft elastomer pellet with at least one surfactant to obtain the granulated soft elastomer, wherein heating the soft elastomer strand to obtain the heated soft elastomer is done at a temperature in the range of 70-150°C, and wherein the at least one surfactant has a concentration in the range of 0.1-20%.

[0045] In an embodiment of the present disclosure, there is provided a granulated soft elastomer as described herein, wherein the granulated soft elastomer has a diameter in the range of 3.0 - 4.0 mm. In another embodiment of the present disclosure, wherein the granulated soft elastomer has a diameter of 2.5mm.

[0046] In an embodiment of the present disclosure, there is provided a process for obtaining granulated soft elastomer, said process comprising: a) providing a soft elastomer strand selected from the group consisting of natural rubber, styrene butadiene rubber, butadiene rubber and combinations thereof in an extruder; b) heating the soft elastomer strand to obtain a heated soft elastomer; c) extruding the heated soft elastomer through a die to obtain an extruded soft elastomer strand; d) pelletizing the extruded soft elastomer strand in an underwater pelletizer to obtain a soft elastomer pellet; and e) contacting the soft elastomer pellet with at least one surfactant selected from the group consisting of cationic surfactant, anionic surfactant, non-ionic surfactant and combinations thereof to obtain the granulated soft elastomer, wherein heating the soft elastomer strand to obtain the heated soft elastomer is done at a temperature in the range of 70-150°C, the at least one surfactant has a concentration in the range of 0.1-20%, the extruding is carried out with a screw speed in the range of 200-1000 rpm, the pelletizing is carried out at a temperature in the range of 100-150°C, the underwater pelletizer has a speed in the range of 200-2000 rpm and the granulated soft elastomer has a diameter in the range of 3.0 - 4.0 mm.

[0047] In an embodiment of the present disclosure, there is provided a process for obtaining granulated soft elastomer, said process comprising: a) providing a soft elastomer strand in an extruder; b) heating the soft elastomer strand to obtain a heated soft elastomer; c) extruding the heated soft elastomer through a die to obtain an extruded soft elastomer strand; d) pelletizing the extruded soft elastomer strand in an underwater pelletizer to obtain a soft elastomer pellet; and e) contacting the soft elastomer pellet with at least one surfactant to obtain the granulated soft elastomer, wherein heating the soft elastomer strand to obtain the heated soft elastomer is done at a temperature 100°C, and wherein the at least one surfactant has a concentration of 5%, wherein the extruding is carried out with a screw speed of 400 rpm and wherein the pelletizing is carried out at a temperature of 100°C, the underwater pelletizer has a speed of 1300 rpm, the soft elastomer is natural rubber, the at least one surfactant is selected from the group consisting of cationic surfactant, anionic surfactant, non-ionic surfactant and combinations thereof and the granulated soft elastomer has a diameter of 2.5 mm.

[0048] Although the subject matter has been described with reference to specific embodiments, this description is not meant to be construed in a limiting sense. Various modifications of the disclosed embodiments, as well as alternate embodiments of the subject matter, will become apparent to persons skilled in the art upon reference to the description of the subject matter. It is therefore contemplated that such modifications can be made without departing from the spirit or scope of the present subject matter as defined. EXAMPLES

[0049] The disclosure will now be illustrated with the 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 ordinary person skilled 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.

[0050] The forthcoming examples explains that how the present disclosure provides a process for obtaining soft elastomer granules. The process of the present disclosure provides a process for obtaining soft elastomer granules without using any additional solid ingredients. The obtained granules are free flowing without showing stickiness. EXAMPLE 1

Process for obtaining soft elastomer granules

[0051] The process for obtaining granulated soft elastomer comprises the following steps. RSS4 strand (soft elastomer strand) was fed into the twin screw extruder at a temperature of 100 C to obtain a heated soft elastomer. The heated soft elastomer was then extruded through a die with a screw speed of 400 rpm to obtain an extruded soft elastomer strand, wherein the die had a temperature of 100°C The extruded (RSS4) soft elastomer strand was then made to flow through the underwater pelletizer ECON UWP. The extruded RSS4 strand was pelletized into soft elastomer pellets using underwater pelletizer at a speed of 1300 rpm at a temperature of 100°C. The obtained soft elastomer pellets were collected in the water tank containing 5% of ammonium laurate (surfactant) solution. The then obtained soft elastomer granules were found to be free flowing. The soft elastomer granules obtained from this process were spherical with a diameter of about 2.5 mm.

[0052] Figure 1 illustrates an image of soft elastomer granules obtained from the process of the present disclosure. It can be observed from the Figure 1 that the soft elastomer granules are free flowing. These free flowing soft elastomer granules can be fed into any equipment, there by the broadening the areas of applications of these elastomer materials.

[0053] A granulated soft elastomer obtained from the aforementioned process described herein, was free-flowing and had a diameter in the range of 3.0 - 4.0 mm. The granulated soft elastomer had decreased stickiness and can be processed in any equipment such as single, twin and multiple extruders. [0054] It is essential to maintain the process parameters such as extruder temperature, extruder speed, die temperature, percentage of surfactant solution in the range as per the present disclosure to obtain free flowing soft elastomer granules. If extruder temperature is less than 70°C, the elastomer does not melt. If extruder temperature is greater than 150°C, then the elastomer gets degraded. Hence, heating the soft elastomer strand is done at a temperature in the range of 70-150 s6,that elastomer becomes heated soft elastomer without any degradation which can be further extruded and pelletized. Further if extruder speed is less than 200 rpm, then shear energy is not sufficient enough to melt the elastomer. And if the extruder speed is greater than 1000 rpm, then shear energy becomes very high, and degrades the elastomer. Similarly if the die temperature is very high, then elastomer degrades, and cooling is not efficient. And if die temperature is very low, then soft elastomer strand is not formed and elastomer gets stuck at the die. Further, the surfactant is maintained in the concentration range as disclosed in present disclosure, since concentration less than 5% causes the granules to remain sticky and concentration greater than 20% then the surfactant gets adhered on the surface of the granules causing higher impurity. Hence any deviation from the process explained in the present disclosure did not result in the desired soft elastomer granules. Advantages of the present disclosure

The present disclosure provides a process for obtaining granulated soft elastomer, said process comprising: a) providing a soft elastomer strand in an extruder; b) heating the soft elastomer strand to obtain a heated soft elastomer; c) extruding the heated soft elastomer through a die to obtain an extruded soft elastomer strand; d) pelletizing the extruded soft elastomer strand in an underwater pelletizer to obtain a soft elastomer pellet; and e) contacting the soft elastomer pellet with at least one surfactant to obtain the granulated soft elastomer, wherein heating the soft elastomer strand to obtain the heated soft elastomer is done at a temperature in the range of 70- 150°C, and wherein the at least one surfactant has a concentration in the range of 0.1- 20%. The process does not involve addition of any other solid ingredients for granulation of raw soft elastomer. The soft elastomer granules obtained are free flowing and can be fed into any equipment thereby widening the application arenas.

Claims

I/We claim:

1) A process for obtaining granulated soft elastomer, said process comprising:

(a) providing a soft elastomer strand in an extruder;

(b) heating the soft elastomer strand to obtain a heated soft elastomer;

(c) extruding the heated soft elastomer through a die to obtain an extruded soft elastomer strand;

(d) pelletizing the extruded soft elastomer strand in an underwater pelletizer to obtain a soft elastomer pellet; and

(e) contacting the soft elastomer pellet with at least one surfactant to obtain the granulated soft elastomer, wherein heating the soft elastomer strand to obtain the heated soft elastomer is done at a temperature in the range of 70-150°C, and the at least one surfactant has a concentration in the range of 0.1-20%.

2) The process as claimed in claim 1, wherein the extruding is carried out with a screw speed in the range of 200-1000 rpm.

3) The process as claimed in claim 1, wherein the pelletizing is carried out at a temperature in the range of 100-150°C.

4) The process as claimed in claim 1 , wherein the underwater pelletizer has a speed in the range of 200-2000 rpm.

5) The process as claimed in claim 1, wherein the soft elastomer strand is selected from the group consisting of natural rubber, styrene butadiene rubber, butadiene rubber and combinations thereof.

6) The process as claimed in claim 1 , wherein the at least one surfactant is selected from the group consisting of cationic surfactant, anionic surfactant, non-ionic surfactant, and combinations thereof.

7) A granulated soft elastomer obtained from the process as claimed in claim 1.

8) The granulated soft elastomer as claimed in claim 7, wherein the granulated soft elastomer has a diameter in the range of 3.0 - 4.0 mm.