Description:FIELD
The present disclosure relates to a process for the preparation of a partially cross linked butyl rubber.
DEFINITIONS
As used in the present disclosure, the following terms are generally intended to have the meaning as set forth below, except to the extent that the context in which they are used indicates otherwise.
Mooney viscosity: The term “Mooney viscosity” refers to a measurement of viscosity of a rubber or compound, determined in a Mooney shearing disk viscometer. Mooney viscosity differentiates between different types and grades of polymers in order to ensure a high processing consistency.
Chain scission: The term “Chain scission” in polymer chemistry refers to the degradation of polymer’s main chain that is often caused by thermal stress (heat) or ionizing radiation (e.g. light, UV radiation or gamma radiation), often involving oxygen.
Partially cross linked rubber itself defines the term wherein the rubber is partially cross linked. The extent of crosslinking is directly proportional to the Mooney viscosity of the rubber.
BACKGROUND
The background information herein below relates to the present disclosure but is not necessarily prior art.
Butyl rubber is a copolymer of isoprene and isobutylene rubber (IIR). Crosslinking of butyl rubber, partially, in gum rubber stage by any means has proven to be an extremely challenging task.
Conventionally, cross linking of butyl rubber is performed through vulcanization process or through melt mixing process. However, to achieve low concentration of cross linking or partial cross linking of butyl rubber, vulcanization is not a suitable process. Further, in melt mixing processes, the material is exposed to harsh conditions such as high temperature (above 150 °C) in the presence of cross linkers and cross linking initiators, causing degradation of rubber which leads to chain scission and in turn results in lower molecular weight cross linked rubber. Further, non-uniform distribution of the cross linker and the catalyst in rubber material during initial milling process leads to exposure of rubber material to higher concentration of reagents, thereby causing higher cross linking than rubber exposed to lesser concentration of regents. This results in less efficient product. Another drawback of the melt mixing process is that as the process is carried out in solid state, the unreacted cross linking initiator are retained in the final product causing the deterioration of the product property over the time. Further, the butyl rubber cross linking at gum rubber stage requires higher alkene content which is achieved by incorporating higher percentage of isoprene content. However, the presence of higher content of isoprene changes the basic properties of butyl rubber which is not desirable.
Therefore, there is, felt a need to provide a process for the preparation of a partially cross linked butyl rubber that mitigates the drawbacks mentioned herein above or at least provides a useful alternative.
OBJECTS
Some of the objects of the present disclosure, which at least one embodiment herein satisfies, are as follows:
It is an object of the present disclosure to ameliorate one or more problems given in the background or to at least provide a useful alternative.
An object of the present disclosure is to provide a process for the preparation of a partially cross linked butyl rubber.
Another object of the present disclosure is to provide a process for the preparation of a partially cross linked butyl rubber that minimizes the degradation of rubber.
Yet another object of the present disclosure is to provide a process for the preparation of a partially cross linked butyl rubber that is carried out in a solution phase.
Still another object of the present disclosure is to provide a process for the preparation of a partially cross linked butyl rubber that has minimal content of isoprene in butyl rubber.
Other objects and advantages of the present disclosure will be more apparent from the following description, which is not intended to limit the scope of the present disclosure.
SUMMARY
The present disclosure relates to a process for the preparation of a partially cross linked butyl rubber. The process comprises dissolving a butyl rubber in a fluid medium at a first predetermined temperature to obtain a slurry. At least one cross linker is added to the slurry under stirring at a second predetermined temperature for a first predetermined time period to obtain a first reaction mixture. At least one radical initiator is added to the first reaction mixture under stirring over a second predetermined time period at a third predetermined temperature to obtain a second reaction mixture. The second reaction mixture is heated under stirring at a fourth predetermined temperature for a third predetermined time period followed by terminating the reaction to obtain a product mixture comprising the partially cross linked butyl rubber. The product mixture is coagulated with at least one antioxidant followed by washing and drying to obtain the partially cross linked butyl rubber.
DETAILED DESCRIPTION
The present disclosure relates to a process for the preparation of a partially cross linked butyl rubber.
Embodiments are provided so as to thoroughly and fully convey the scope of the present disclosure to the person skilled in the art. Numerous details are set forth, relating to specific components, and methods, to provide a complete understanding of embodiments of the present disclosure. It will be apparent to the person skilled in the art that the details provided in the embodiments should not be construed to limit the scope of the present disclosure. In some embodiments, well-known processes, well-known apparatus structures, and well-known techniques are not described in detail.
The terminology used, in the present disclosure, is only for the purpose of explaining a particular embodiment and such terminology shall not be considered to limit the scope of the present disclosure. As used in the present disclosure, the forms "a,” "an," and "the" may be intended to include the plural forms as well, unless the context clearly suggests otherwise. The terms "comprises," "comprising," “including,” and “having,” are open ended transitional phrases and therefore specify the presence of stated features, integers, steps, operations, elements, modules, units and/or components, but do not forbid the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. The particular order of steps disclosed in the method and process of the present disclosure is not to be construed as necessarily requiring their performance as described or illustrated. It is also to be understood that additional or alternative steps may be employed.
The terms first, second, third, etc., should not be construed to limit the scope of the present disclosure as the aforementioned terms may be only used to distinguish one element, component, region, layer or section from another component, region, layer or section. Terms such as first, second, third etc., when used herein do not imply a specific sequence or order unless clearly suggested by the present disclosure.
Conventionally, cross linking of butyl rubber is performed through vulcanization process or through melt mixing process. However, to achieve low concentration of cross linking or partial cross linking of butyl rubber, vulcanization is not a suitable process. In melt mixing processes, material is exposed to harsh conditions such as high temperature (above 150 °C) in the presence of cross linkers and cross linking initiators, causing degradation of rubber which leads to chain scission which in turn results in lower molecular weight cross linked rubber. Further, non-uniform distribution of cross linker and catalyst over rubber material during initial milling process leads to exposure of rubber material to higher concentration of reagents, thereby causing higher cross linking than rubber exposed to lesser concentration of regents. This results in less efficient product. Another drawback of the melt mixing process is that as the process is carried out in solid state, the unreacted cross linking initiator are retained in the final product causing the deterioration of the product property over the time.
The present disclosure provides a process for the preparation of a partially cross linked butyl rubber. The process comprises the following steps:
a. dissolving a butyl rubber in a fluid medium at a first predetermined temperature to obtain a slurry;
b. adding at least one cross linker to the slurry under stirring at a second predetermined temperature for a first predetermined time period to obtain a first reaction mixture;
c. adding at least one radical initiator to the first reaction mixture under stirring over a second predetermined time period at a third predetermined temperature to obtain a second reaction mixture;
d. heating the second reaction mixture under stirring at a fourth predetermined temperature for a third predetermined time period followed by terminating the reaction to obtain a product mixture comprising the partially cross linked butyl rubber; and
e. coagulating the product mixture with at least one antioxidant followed by washing and drying to obtain the partially cross linked butyl rubber.
The process is described in detail herein below.
In a first step, a butyl rubber is dissolved in a fluid medium at a first predetermined temperature to obtain a slurry.
The butyl rubber used in accordance with the present disclosure is commercially available butyl rubber. Butyl rubber (IIR) is a synthetic rubber, a copolymer of isobutylene with isoprene. The commercially available butyl rubber contains up to 3% of olefinic part.
Mooney viscosity of the commercially available butyl rubber used in the process of the present disclosure is in the range of 40 MU to 55 MU. In an exemplary embodiment of the present disclosure, the butyl rubber used in the process of cross linking has a Mooney viscosity of 44 MU.
The fluid medium can be selected from toluene, benzene, xylene, hexane, cyclohexane and heptane. In an exemplary embodiment, the fluid medium is toluene.
The first predetermined temperature is in the range of 50 ºC to 60 ºC. In an exemplary embodiment, the first predetermined temperature is 55 ºC.
In a second step, at least one cross linker is added to the slurry under stirring at a second predetermined temperature for a first predetermined time period to obtain a first reaction mixture.
In accordance with the present disclosure, the cross linker can be selected from 1,1'-(Methylenedi-4,1-phenylene)bismaleimide, N,N'-(1,3-Phenylene) dimaleimide, N,N'-(4-Methyl-1,3-Phynelene)bismaleimide, N,N'-(o-Phenylene)dimaleimide, 1,1'-(3,3'-dimethyl-1,1'-biphenyl-4,4'-diyl)bismaleimde and BM(PEG)2 (1,8-bismaleimido-diethyleneglycol). In an exemplary embodiment, the cross linker is 1,1'-(Methylenedi-4,1-phenylene)bismaleimide.
The concentration of the cross linker is in the range of 5% to 25%. In an exemplary embodiment, the concentration of the cross linker is 10% in toluene.
The mass ratio of the butyl rubber to the cross linker is in the range of 100:1 to 100:10. In an exemplary embodiment, the mass ratio of the butyl rubber to the cross linker is 100:2. In another exemplary embodiment, the mass ratio of the butyl rubber to the cross linker is 100:3. In still another exemplary embodiment, the mass ratio of the butyl rubber to the cross linker is 100:4. In yet another exemplary embodiment, the mass ratio of the butyl rubber to the cross linker is 100:9.5.
The mass ratio of the butyl rubber to the cross linker plays an important role for achieving the desired extent of crosslinking in the partially cross linked butyl rubber i.e. if the ratio varies, crosslinking density changes which in turn increases the mooney viscosity. Thus, different extent of crosslinking can be achieved by varying the mass ratio of the butyl rubber to the cross linker.
The first predetermined time period is in the range of 2 minutes to 10 minutes. In an exemplary embodiment, the first predetermined time period is 5 minutes.
The second predetermined temperature is in the range of 90 ºC to 100 ºC In an exemplary embodiment, the second predetermined temperature is 95 ºC.
In a third step, at least one radical initiator is added to the first reaction mixture under stirring over a second predetermined time period at a third predetermined temperature to obtain a second reaction mixture.
In accordance with the present disclosure, the radical initiator is organic peroxides.
The organic peroxide can be selected from the group consisting of acetyl acetone peroxide, diacetyl peroxide, cumyl hydroperoxide, dicumyl peroxide, benzoyl peroxide, t-butyl hydroperoxide, methyl ethyl ketone peroxide, peracetic acid, peracids and methane hydroperoxide. In an exemplary embodiment, the radical initiator is benzoyl peroxide.
The radical initiator activates the rubber chains by generating free radical centers on rubber chains which can actively participate in cross linking process.
The concentration of the radical initiator is in the range of 1% to 40 %. In an exemplary embodiment, the concentration of the radical initiator is 20% in toluene.
Typically, a chemical process occurs only when it is able to cross the energy of activation (energy barrier). Lower concentration of the reactants generally slows down the reaction kinetics (as per collision theory) and such slow kinetics would not allow the chemical process to cross over energy of activation. Due to this reason, generally higher concentrations of the reactants are preferred. Therefore, the range of the concentration of the radical initiator i.e. 1% to 40 % would work in the same way provided the rubber to initiator ratio is kept constant. However, the higher concentrations of the radical initiator would be preferable.
The mass ratio of the butyl rubber to the radical initiator is in the range of 100:0.1 to 100:5. In an exemplary embodiment, the mass ratio of the butyl rubber to the radical initiator is 100:0.35. In another exemplary embodiment, the mass ratio of the butyl rubber to the radical initiator is 100:0.75. In still another exemplary embodiment, the mass ratio of the butyl rubber to the radical initiator is 100:1. In yet another exemplary embodiment, the mass ratio of the butyl rubber to the radical initiator is 100:1.3. In yet another exemplary embodiment, the mass ratio of the butyl rubber to the radical initiator is 100:4.
The second predetermined time period is in the range of 15 minutes to 60 minutes. In an exemplary embodiment, the second predetermined time period is 30 minutes.
The third predetermined temperature is in the range of 90 ºC to 100 ºC. In an exemplary embodiment, the third predetermined temperature is 95 ºC.
In a fourth step, the second reaction mixture is heated under stirring at a fourth predetermined temperature for a third predetermined time period followed by terminating the heating to obtain a product mixture comprising the partially cross linked butyl rubber.
In accordance with the present disclosure, the fourth predetermined temperature is in the range of 90 ºC to 100 ºC. In an exemplary embodiment, the fourth predetermined temperature is 95 ºC.
The third predetermined time period is in the range of 15 minutes to 50 minutes. In an exemplary embodiment, the third predetermined time period is 30 minutes.
The second reaction mixture is cooled down to a temperature in the range of 25 ºC to 30 ºC.
In a fifth step, the obtained product mixture is coagulated with at least one antioxidant followed by washing and drying to obtain the partially cross linked butyl rubber.
Addition of the antioxidant during the coagulation step results in a product with inbuilt oxidative stability which in turn will protect the rubber during its processing and performance life cycle.
In accordance with the present disclosure, the antioxidant can be selected from Pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate), phenolic antioxidant, amine based antioxidants. In an exemplary embodiment, the antioxidant is tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate.
The coagulated product mixture is washed with acetone. The step of washing of the product mixture removes unreacted peroxide, minimizing any degradation of final product, which is highly advantageous.
The washed coagulated product mixture is dried in vacuum oven at a temperature in the range of 60 °C to 80 °C for a time period in the range of 2 hours to 3 hours till no volatile solvent is found.
In accordance with the present disclosure, a Mooney viscosity of the partially cross linked butyl rubber is in the range of 55 MU to 90 MU.
Higher Mooney viscosity in partially cross linked butyl rubber indicates the extent of cross linking in the product i.e. as the mooney viscosity increases, the crosslinking density increases. Thus, the Mooney viscosity is directly proportional to the crosslinking density.
The percentage (%) of partially crosslinking of the rubber can be varied for different applications/uses. The fully crosslinked rubber i.e., 100% crosslinked rubber cannot be processed further as they are not soluble in solvents. On the contrary, the partially crosslinked rubber can be further processed. The partially crosslinked rubber is soluble in solvents as compared to the fully crosslinked rubber.
In general, when the crosslinking happens in a virgin rubber, Mooney viscosity of the rubber increases. In the case of present disclosure, base raw rubber has Mooney of 44MU. After partial crosslinking, Mooney viscosity increases from 44 MU (no crosslinking) to 55 MU (6 % crosslinking) and then to 65 MU (24 % crosslinking) depending on its degree of crosslinking.
Thus, the partially cross linked butyl rubber of the present disclosure with Mooney viscosity in the range of 55 MU to 90 MU has an extent of cross linking in the range of 5% to 70%.
In an embodiment of the present disclosure, the process for the preparation of the partially cross linked butyl rubber is carried out by solution phase process. The process is carried out at low temperature i.e. below 100 °C. This minimizes the degradation of the butyl rubber. The partially cross linked butyl rubber has minimal amount of isoprene content, up to 2%.
The solution process shows a good control over cross linking due to uniform interaction of butyl rubber and cross linking reagents. The cross linker is evenly distributed in the solvent based rubber solution, the rubber and cross linker are exposed uniformly with each other at any given time. Therefore, such uniform reaction mixture provides efficient cross linking at low temperature. Further, in the solution process, the rubber is not exposed to degradation as the process is carried out at a comparatively low temperature.
The partially cross linked butyl rubber has application as sealants, adhesive, coating, water proofing, impermeable membranes.
The foregoing description of the embodiments has been provided for purposes of illustration and not intended to limit the scope of the present disclosure. Individual components of a particular embodiment are generally not limited to that particular embodiment, but, are interchangeable. Such variations are not to be regarded as a departure from the present disclosure, and all such modifications are considered to be within the scope of the present disclosure.
The present disclosure is further described in light of the following experiments which are set forth for illustration purpose only and not to be construed for limiting the scope of the disclosure. The following experiments can be scaled up to industrial/commercial scale and the results obtained can be extrapolated to industrial scale.
Experimental details:
Experiment 1: Process for the preparation of the partially cross linked butyl rubber in accordance with the present disclosure
Example 1: 120g of butyl rubber (having Mooney viscosity 44 MU) were cut into small pieces (approximately 1cm to 2 cm) and dissolved in 800 ml of toluene in a reactor fitted with overhead stirrer and condenser under stirring at 55 °C till complete dissolution of rubber to obtain a slurry. The slurry was heated to 95 °C to obtain a heated slurry. 36ml of 10% of 1,1'-(Methylenedi-4,1-phenylene)bismaleimide (cross linker) solution in toluene was added to the heated slurry and stirred at 95 °C for 5 minutes to obtain a first reaction mixture. After complete mixing, 6 ml of 20% benzoyl peroxide solution in toluene was slowly added to the first reaction mixture over 30 minutes at 95 °C to obtain a second reaction mixture. The second reaction mixture was heated for 30 minutes under stirring to obtain a product mixture. Heating was terminated when appearance of turbidity was observed. The product mixture was cooled to 30 °C and coagulated with acetone solvent followed by addition of tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate solution (0.4 % with respect to rubber) to obtain coagulated rubber lumps.
The coagulated rubber lumps were washed with acetone to remove unreacted peroxides followed by making the lumps into small pieces in crumbs form and dried in vacuum oven at 70 °C for 2.5 hours till no volatile solvent was found to obtain the partially cross linked butyl rubber.
Examples 2-5: Same procedure as in Example 1 was followed except varying amounts of cross linker and radical initiator were used to prepare the partially cross linked butyl rubber having varying Mooney Viscosity. The varying amounts are summarized in Table 1.
The partially cross linked butyl rubbers prepared in Examples 1 to 5 were characterized using Mooney Viscosity to determine the extent of cross linking. The data is summarized in Table 1.
Comparative Example: Preparation of cross linked butyl rubber by melt mixing process
100 g of butyl rubber was taken into two roll miller and heated at 140 °C to obtain a rubber sheet. 3 g of bis maleimide solid was added over the rubber sheet and mixed for 10 minutes followed by adding 1g of benzoyl peroxide and milled for 30 minutes at 140 °C to obtain the cross linked butyl rubber. The cross linked butyl rubber was characterized for Mooney Viscosity to determine the extent of cross linking. The data is summarized in Table 1.
Table 1: Varying amounts of peroxide and cross linker in PHR used for cross linking of butyl rubber
Examples Starting Material (Butyl
Rubber) 1 2 3 4 5 Comparative example
Maleimide (in PHR) - 2 3 3 4 9.5 3
Peroxide (in PHR) - 0.35 0.75 1 1.3 4 1
Mooney viscosity (MU) 44 62 64 76 78 83 48
*PHR=Parts per hundred rubber
Form Table 1, it is observed that the Mooney viscosity of the partially cross linked butyl rubber prepared in Examples 1 to 5 is higher as compared to the starting material butyl rubber used (having a mooney viscosity of 44 MU) and also as compared to the mooney viscosity of the cross linked butyl rubber of the comparative example. The higher Mooney viscosity indicates higher crosslinking.
Experiment 2: Effect of temperature on Mooney viscosity of the partially cross linked butyl rubbers prepared in Examples 1 to 5 and comparative example
To study the effect of temperature on the Mooney viscosity, the partially cross linked butyl rubbers were prepared by using the same procedure as in example 1 except the temperature was varied as summarized in Table 2.
Table 2: Effect of temperature on Mooney viscosity
Example Peroxide Cross linker Reaction Condition Mooney viscosity (MU)
PHR PHR Temperature
(ºC) Time
(minutes) Solvent
1a 1 3 98 30 toluene 82
1b 1 3 110 30 toluene 68
1c 1 3 85 30 toluene 55
1d 1 3 75 30 toluene 41
From table 2, it is observed that above 110 ºC, the process leads to chain scission in solution phase and below 100 ºC was found to be the optimum temperature range for cross linking. However, below 85 ºC, the reaction does not proceed for cross linking due to poor free radical formation ability.
TECHNICAL ADVANCEMENTS
The present disclosure described herein above has several technical advantages including, but not limited to, the realization of a process for the preparation of the partially cross linked butyl rubber that;
? is simple and economic;
? provides efficient cross linking due to uniform distribution of reagents;
? can be carried out at a comparatively low temperature; and
? minimizes the degradation of the product due to removal of unreacted peroxides.
Throughout this specification the word “comprise”, or variations such as “comprises” or “comprising”, will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.
The use of the expression “at least” or “at least one” suggests the use of one or more elements or ingredients or quantities, as the use may be in the embodiment of the invention to achieve one or more of the desired objects or results. While certain embodiments of the inventions have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Variations or modifications to the formulation of this invention, within the scope of the invention, may occur to those skilled in the art upon reviewing the disclosure herein. Such variations or modifications are well within the spirit of this invention.
The numerical values given for various physical parameters, dimensions, and quantities are only approximate values and it is envisaged that the values higher than the numerical value assigned to the physical parameters, dimensions and quantities fall within the scope of the invention unless there is a statement in the specification to the contrary.
While considerable emphasis has been placed herein on the specific features of the preferred embodiment, it will be appreciated that many additional features can be added and that many changes can be made in the preferred embodiment without departing from the principles of the disclosure. These and other changes in the preferred embodiment of the disclosure will be apparent to those skilled in the art from the disclosure herein, whereby it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the disclosure and not as a limitation. , Claims:WE CLAIM:
1. A process for the preparation of a partially cross linked butyl rubber, said process comprising the following steps:
a. dissolving a butyl rubber in a fluid medium at a first predetermined temperature to obtain a slurry;
b. adding at least one cross linker to said slurry under stirring at a second predetermined temperature for a first predetermined time period to obtain a first reaction mixture;
c. adding at least one radical initiator to said first reaction mixture under stirring over a second predetermined time period at a third predetermined temperature to obtain a second reaction mixture;
d. heating said second reaction mixture under stirring at a fourth predetermined temperature for a third predetermined time period followed by terminating the reaction to obtain a product mixture comprising said partially cross linked butyl rubber; and
e. coagulating said product mixture with at least one antioxidant followed by washing and drying to obtain said partially cross linked butyl rubber.
2. The process as claimed in claim 1, wherein said fluid medium is selected from toluene, benzene, xylene, hexane, cyclohexane and heptane.
3. The process as claimed in claim 1, wherein said first predetermined temperature is in the range of 50 °C to 60 ° C.
4. The process as claimed in claim 1, wherein said cross linker is selected from maleimide and its derivatives.
5. The process as claimed in claim 4, wherein said maleimide is selected from the group consisting of 1,1'-(Methylenedi-4,1-phenylene)bismaleimide, N,N'-(1,3-Phenylene)dimaleimide, N,N'-(4-Methyl-1,3-Phynelene)bismaleimide, N,N'-(o-Phenylene)dimaleimide, 1,1'-(3,3'-dimethyl-1,1'-biphenyl-4,4'-diyl)bismaleimde and BM(PEG)2 (1,8-bismaleimido-diethyleneglycol).
6. The process as claimed in claim 1, wherein said radical initiator is organic peroxides; wherein said organic peroxide is selected from the group consisting of acetyl acetone peroxide, diacetyl peroxide, cumyl hydroperoxide, dicumyl peroxide, benzoyl peroxide, t-butyl hydroperoxide, methyl ethyl ketone peroxide, peracetic acid, peracids and methane hydroperoxide.
7. The process as claimed in claim 1, wherein said antioxidant is selected from pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate), phenolic antioxidant and amine based antioxidants.
8. The process as claimed in claim 1, wherein said second and said third predetermined temperatures are independently in the range of 85 °C to 110 ° C.
9. The process as claimed in claim 1, wherein said first predetermined time period is in the range of 2 minutes to 10 minutes and said second predetermined time period is in the range of 15 minutes to 45 minutes.
10. The process as claimed in claim 1, wherein said fourth predetermined temperature is in the range of 90 °C to 100 ° C and said third predetermined time period is in the range of 15 minutes to 50 minutes.
11. The process as claimed in claim 1, wherein a mass ratio of said butyl rubber to said radical initiator is in the range of 100:0.1 to 100:5.
12. The process as claimed in claim 1, wherein a mass ratio of said butyl rubber to said cross linker is in the range of 100:1 to 100:10.
13. The process as claimed in claim 1, wherein a Mooney viscosity of said partially cross linked butyl rubber is in the range of 55 MU to 90 MU.

Dated this 15th day of December, 2022

_______________________________
MOHAN RAJKUMAR DEWAN, IN/PA – 25
of R.K.DEWAN & CO.
Authorized Agent of Applicant

TO,
THE CONTROLLER OF PATENTS
THE PATENT OFFICE, AT MUMBAI