Description:FIELD
The present disclosure relates to a process for the preparation of an elastomeric co-polyester.
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.
Trans-esterification: The term “trans-esterification” refers to a process in which an alcohol molecule and an ester molecule react, either in the presence of an acid or a base to form a new ester.
Esterification: The term “esterification” refers to a chemical reaction in which an alcohol and an acid reacts to form an ester.
Polycondensation: The term “polycondensation” refers to a condensation reaction for producing a polymer by linking a single or multiple kind of the monomers to form long chains releasing water or a similar simple substance.
BACKGROUND
The background information herein below relates to the present disclosure but is not necessarily prior art.
Thermoplastic co-polyester is a class of thermoplastic elastomers that have combined properties of both, the thermoplastics and the rubbers. Due to these combined properties, the thermoplastic co-polyester is used in variety of fields such as automotive, medical, electrical and the like.
The elastomeric co-polyesters are prepared by the trans-esterification reaction of diacid and diol. The conventional processes for the preparation of a co-polyester are associated with certain drawbacks such as the use of high amount of alkali that makes difficult to attain the desired intrinsic viscosity required for downstream processing. Moreover, the use of 1,4 butane diol as a diol adversely hamper the mechanical properties such as the melting point may drop and the co-polyester may not demonstrate the marked glass transition temperature.
Therefore, the present application provides a process for the preparation of a co-polyester that mitigates the drawbacks mentioned hereinabove or at least provide 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 of the prior art or to at least provide a useful alternative.
An object of the present disclosure is to provide a process for the preparation of an elastomeric co-polyester.
Yet another object of the present disclosure is to provide a simple, economical and environment friendly process for the preparation of an elastomeric co-polyester.
Still another object of the present disclosure is to provide a process for the preparation of an elastomeric co-polyester that has superior elastic properties.
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 an elastomeric co-polyester.
The process comprises the steps of esterifying a predetermined amount of a diacid and a predetermined amount of a first diol in the presence of a first catalyst at a first predetermined process conditions to obtain a first oligomer. Separately, esterifying a predetermined amount of fatty acid and a predetermined amount of a second diol in the presence of a second catalyst at a second predetermined process conditions to obtain a second oligomer. The first oligomer and the second oligomer are mixed in a predetermined ratio for a predetermined time period to obtain a mixture. The mixture is polycondensed at a third predetermined process conditions to obtain the elastomeric co-polyester.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWING
The present disclosure will now be described with the help of the accompanying drawing, in which:
FIGURE 1: illustrates a DSC thermogram of PBT (Polybutylene terephthalate) which is not in accordance with the present disclosure; and
FIGURE 2: illustrates a DSC thermogram of the elastomeric co-polyester obtained in accordance with the present disclosure.
DETAILED DESCRIPTION
The present disclosure relates to a process for the preparation of an elastomeric co-polyester.
Embodiments of the present disclosure will now be described with reference to the accompanying drawing.
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.
As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed elements.
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.
Thermoplastic co-polyester is a class of thermoplastic elastomers that have combined properties of both, the thermoplastics and the rubbers. Due to these combined properties, the thermoplastic co-polyester is used in variety of fields such as automotive, medical, electrical and a like.
The elastomeric co-polyesters are prepared by the trans-esterification reaction of diacid and diol. The conventional process for the preparation of a co-polyester are associated with certain drawbacks such as the use of high amount of alkali makes it difficult to attain the desired intrinsic viscosity of the co-polyester required for downstream processing. Moreover, the use of 1,4 butane diol as a diol adversely hamper the mechanical properties of the polymer such as the melting point may drop and the polymer may not demonstrate the marked glass transition temperature.
The present application provides a process for the preparation of an elastomeric co-polyester. The process comprises the following steps:
i) esterifying a predetermined amount of a diacid and a predetermined amount of a first diol in the presence of a first catalyst at a first predetermined process conditions to obtain a first oligomer;
ii) separately, esterifying a predetermined amount of fatty acid and a predetermined amount of a second diol in the presence of a second catalyst at a second predetermined process conditions to obtain a second oligomer;
iii) mixing the first oligomer and the second oligomer in a predetermined ratio at a predetermined speed for a predetermined time period to obtain a mixture; and
iv) polycondensing the mixture at a third predetermined process conditions to obtain the elastomeric co-polyester.
The process is described in detail.
In a first step, a predetermined amount of a diacid and a predetermined amount of a first diol are esterified in the presence of a first catalyst at a first predetermined process conditions to obtain a first oligomer.
In an embodiment of the present disclosure, the diacid is at least one selected from the group consisting of terephthalic acid, isophthalic acid, naphthalene dicarboxylic acid and diphenyl dicarboxylic acid. In an exemplary embodiment of the present disclosure, the diacid is terephthalic acid.
In an embodiment of the present disclosure, the terephthalic acid is a purified terephthalic acid.
In an embodiment of the present disclosure, the predetermined amount of the diacid is in the range of 50 mass% to 86 mass% with respect to the total mass of the first oligomer. In an exemplary embodiment of the present disclosure, the predetermined amount of terephthalic acid is 58.1 mass% with respect to the total mass of the first oligomer.
In an embodiment of the present disclosure, the first diol is at least one selected from the group consisting of monoethylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, trimethylene glycol, tetramethylene glycol, cyclohexane dimethanol and aromatic diol.
In an embodiment of the present disclosure, the aromatic diol is selected from the group consisting of 2,2-bis(4-hydroxyphenyl)propane, bis(4-hydroxyphenyl) sulphone and bis(4-hydroxydiphenyl)methane.
In an exemplary embodiment of the present disclosure, the first diol is monoethylene glycol.
In an embodiment of the present disclosure, the predetermined amount of the first diol is in the range of 30 mass% to 60 mass% with respect to the total mass of the first oligomer. In an exemplary embodiment of the present disclosure, the predetermined amount of monoethylene glycol is 41.89 mass% with respect to the total mass of the first oligomer.
In an embodiment of the present disclosure, the first predetermined process conditions include a temperature in the range of 200 ºC to 300 ºC and a pressure in the range of 2 kg/cm2 to 2.5 kg/cm2. In an exemplary embodiment of the present disclosure, the first predetermined process conditions include a temperature of 259 ºC and a pressure of 2.1 kg/cm2.
In an embodiment of the present disclosure, the first catalyst is selected from the group consisting of antimony trioxide, antimony triacetate, germanium dioxide and zinc acetate. In an exemplary embodiment of the present disclosure, the first catalyst is antimony trioxide.
In an embodiment of the present disclosure, the first catalyst is used in an amount in the range of 200 ppm to 400 ppm. In an exemplary embodiment the first catalyst is used in an amount of 290 ppm.
In an embodiment of the present disclosure, the predetermined amount of the diacid and the predetermined amount of the first diol are esterified at a first predetermined process conditions to form bis(2-hydroxyethyl terephthalate) (BHET). The bis(2-hydroxyethyl terephthalate) (BHET) which is a low molecular weight oligomer, characterized by having a low degree of polymerisation.
In a second step, separately, a predetermined amount of a fatty acid and a predetermined amount of a second diol are esterified in the presence of a second catalyst at a second predetermined process conditions to obtain a second oligomer.
In an embodiment of the present disclosure, the fatty acid is at least one selected from the group consisting of dimer fatty acid, dimerized oleic acid, trimerized oleic acid, dimerized linoleic acid, trimerized linoleic acid, dimerized linolenic acid and trimerized linolenic acid. In an exemplary embodiment of the present disclosure, the fatty acid is dimer fatty acid.
In an embodiment of the present disclosure, the second diol is at least one selected from the group consisting of monoethylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, trimethylene glycol, tetramethylene glycol, cyclohexane dimethanol and aromatic diol.
In an embodiment of the present disclosure, the aromatic diol is selected from the group consisting of 2,2-bis(4-hydroxyphenyl)propane, bis(4-hydroxyphenyl) sulphone and bis(4-hydroxydiphenyl)methane.
In an exemplary embodiment of the present disclosure, the second diol is monoethylene glycol.

In an embodiment of the present disclosure, the predetermined amount of the fatty acid is in the range of 50 mass% to 90 mass% with respect to the total mass of the second oligomer. In an exemplary embodiment of the present disclosure, the predetermined amount of the dimer fatty acid is 81.88 mass% with respect to the total mass of the second oligomer.
In an embodiment of the present disclosure, the predetermined amount of second diol is in the range of 15 mass% to 50 mass% with respect to the total mass of the second oligomer. In an exemplary embodiment of the present disclosure, the predetermined amount of the monoethylene glycol (second diol) is 18.1 mass% with respect to the total mass of the second oligomer.
In an embodiment of the present disclosure, the second catalyst is selected from the group consisting of titanium butoxide, titanyl oxalates, titanium halides, hydrolyzed products of titanium halides, titanium hydroxide, and titanium oxide hydrate. In an exemplary embodiment of the present disclosure, the second catalyst is titanium butoxide.
In an embodiment of the present disclosure, the second catalyst is used in an amount in the range of 80 ppm to 200 ppm. In an exemplary embodiment of the present disclosure, the titanium butoxide (second catalyst) is used in an amount of 100 ppm.
In an embodiment of the present disclosure, the second predetermined process conditions include, a temperature in the range of 150 ºC to 250 ºC. In an exemplary embodiment of the present disclosure, the second predetermined process conditions include temperature of 185 ºC at an atmospheric pressure.
In a third step, the first oligomer and the second oligomer are mixed in a predetermined ratio at a predetermined speed for a predetermined time period to obtain a mixture.
In an embodiment of the present disclosure, the predetermined ratio of the first oligomer to the second oligomer is in the range of 1:0.05 to 1:0.5. In an exemplary embodiment, the predetermined ratio of the first oligomer to the second oligomer is 1:0.27
The predetermined ratio of the first oligomer to the second oligomer governs the rheological, thermal and mechanical properties of the copolymer.
In an embodiment of the present disclosure, the predetermined speed is in the range of 1350 rpm to 1450 rpm. In an exemplary embodiment, the predetermined speed is 1415 rpm.
In an embodiment of the present disclosure, the predetermined time period is in the range of 60 minutes to 120 minutes. In an exemplary embodiment of the present disclosure, the predetermined time period is 90 minutes.
Lastly, the mixture is polycondensed at a third predetermined process conditions to obtain the elastomeric co-polyester.
In an exemplary embodiment of the present disclosure, the third predetermined process conditions include a temperature in the range of 250 ºC to 300 ºC and a vacuum in the range of 0.1 mmHg to 10 mmHg. In an exemplary embodiment of the present disclosure, the third predetermined process conditions include a temperature of 259 ºC and a vacuum of 0.45 mmHg.
The mixture undergoes polycondensation reaction under vacuum in such a way that it results in the formation a block co-polyester with polymer backbone chain consisting of blocks of polyethylene terephthalate followed by a block of ester chain of dimer fatty acid and monoethylene glycol (MEG).
In an embodiment of the present disclosure, the elastomeric co-polyester obtained are subsequently subjected for melt spinning to obtain a continuous multifilament yarn.
Conversion of the elastomeric co-polyester to continuous multifilament yarn comprises of melt spinning the elastomeric co-polyester to form a fully drawn yarn (FDY). The resultant multifilament yarn, made from the co-polyester prepared by the process of the present disclosure have superior elastic recovery and higher amount of elongation compared to FDY spun from homopolymer polyethylene terephthalate (PET).
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
Example 1: Process for the preparation of the elastomeric co-polyester in accordance with the present disclosure.
34.4 kg of purified terephthalic acid (diacid) and 24.8 kg of monoethylene glycol (first diol) were esterified in the presence of 290 ppm of antimony trioxide (first catalyst) at 259oC and 2.1 kg/cm2 (pressure) for 180 minutes to obtain a bis(2-hydroxyethyl terephthalate) (BHET) (first oligomer).
Separately, 9.275 kg of dimer fatty acid and 2.05 kg of monoethylene glycol (second diol) were esterified in the presence of 100 ppm of titanium butoxide (second catalyst) at 185 oC at atmospheric pressure for 240 minutes to obtain a bis(2-hydroxyethyl) dimerate (second oligomer).
37 kg of bis(2-hydroxyethyl terephthalate) (BHET) (the first oligomer) and 10 kg of bis(2-hydroxyethyl)dimerate (the second oligomer) were mixed at 1415 rpm for 90 mins to obtain a mixture. The so obtained mixture was polycondensed at 259 oC (third predetermined temperature) under 0.45 mmHg (predetermined vacuum) for 90 mins to obtain the elastomeric co-polyester.
Example 2: Comparative examples
2.a : Block co-polymerization of PBT(Polybutylene terephthalate)-co-DFA (dimer fatty acid) co-polymer.
Purified terephthalic acid and butane diol in a mole ratio of 1:1.8 were esterified in a 5 kg batch condensation reactor consisting of an agitator in the presence of 150 ppm of titanium tetra butoxide (catalyst) for 90 mins through which the temperature was raised from a room temperature upto 220 oC to obtain a oligomer. Water condensate coming out from the condenser column seized indicated the completion of the oligomer formation.
The refractive index of the distillate was 1.35. The refractive index (RI) of distillate was similar to water (Refractive index of H2O is 1.33); which confirms very less volatile substances were carried over through condensate.
The low molecular weight product (oligomer) formed had dark red color with slight increase in viscosity. In the so obtained 5 wt % of oligomer, dimer fatty acid (soft co-polymer), was incorporated in an amount of 5 wt% with respect to the total weight of the copolymer in the polycondensation reactor and allowed to react at 270°C and 0.3 mmHg (vaccum) for 120 mins to obtain the co-polyester. The properties of the co-polyester obtained are illustrated in table 1.
Table 1:
Sr. No Properties Values
1 Tm (oC) 217.47
2 Tc (oC) 175.25
3 IV (dL/g) 0.807
4 COOH (meq/kg) 11

Due to less amount of comonomer used for copolymerization, there was no separate distinguishable Tg shift and crystallization peak. Figure 1 illustrates a DSC thermogram of PBT and there is no major change evident with respect to the thermal behavior.

2.b :Block co-polymerization of BHET (bis(2-hydroxyethyl terephthalate))-co-DFA (dimer fatty acid) co-polymer.
5 wt % of dimer fatty acid was directly introduced to the 95 wt % of bis(2-hydroxyethyl terephthalate) (BHET) prior to polycondensation in a reaction autoclave at 260 °C and 0.35 mmHg vacuum and esterified for 90 minutes to obtain the block copolymer.
The resultant block copolymer had intrinsic viscosity of 0.68 dL/g and COOH No. of 14 meq/kg. It was later dried and melt spun to fully drawn filament yarn. The yarn showed elastic recovery similar to homopolymer PET of 47% in cyclic loading tests, which was due to formation of random copolymer of hard segments and soft segments. Response of random copolymer structure to longitudinal stresses is usually non-uniform.
This was overcome by the block co-polyester synthesized by the process of the present disclosure through a two-stage copolymerization process with uniform arrangement of hard and soft segments resulting in enhanced elastic recovery up to 90% under cyclic loading. The block co-polyester (elastomeric co-polyester) of the present disclosure also facilitated melt spinning through existing spinning technologies by attaining the desired melt viscosity.
Example 3: Process for the preparation of yarn by using the elastomeric co-polyester obtained in example 1 in accordance with the present disclosure.
The yarn was prepared by the following process steps:
a) The copolymerized base chips of elastomeric co-polyester obtained in example 1 were crystallized prior to melt spinning process to avoid sintering and formation of lumps when they are reheated during the processing. The copolymerized base chips of elastomeric co-polyester were gradually heated in a fluidized state above its glass transition temperature (Tg) (45°C) for 4 to 5 hours to obtain crystallized chips;
b) the so obtained crystallized chips were thoroughly dried prior to spinning at 120oC for 4 to 5 hours, under air atmosphere to obtain dried crystallized chips;
c) the dried crystallized chips were fed through a hopper to a melt spinning assembly consisting a single screw extruder which rotates at a speed of 62 rpm to melt the dried crystallized chips above its melting temperature (240°C) to obtain melted polymer. Extruder feeds the melted polymer to a manifold which essentially is a pool of melt over the spin pack assembly;
d) the so obtained molten polymer was forced through the spin pack and spinneret assembly aided by a metering pump in order to extrude fine multifilaments of required fineness (75/36). Influence of shear and temperature on the melt rheology was critically monitored through fluctuations in pack pressure and pump discharge pressure; and
e) the multifilaments extruded from the spinnerets were quenched through a cross flow air and drawn-down at a speed of 3730 mpm with draw ratio of 1 to obtain a highly oriented yarn of 75/36 denier.
Example 4: Characterization of the co-polyester/yarn prepared in accordance with the present disclosure.
The co-polyester obtained in example 1 was subjected for the analysis of chemical, thermal and mechanical properties. The results are as follows:
I. Chemical Characterization
• COOH No.: Reactivity of esterification process between dimer fatty acid and monoethylene glycol (MEG) was assessed by examining the carboxyl number which was 100 meq/kg. Post polycondensation stage, it decreased to 16 meq/kg which indicated conversion into ester groups.
• Intrinsic Viscosity: The co-polyester obtained in example 1 was analyzed as per ASTM 4603. The dimer fatty acid-MEG prepolymer gave IV (intrinsic viscosity) of 0.018 dL/g which increased to 0.755 dL/g post polycondensation of the final polymer (elastomeric co-polyester).
II. Thermal characterization
The thermal characterization of the elastomeric co-polyester obtained in example 1 was done through differential scanning calorimetary (DSC) thermographs. Figure 2 illustrates a glass transition temperature was observed at 44 oC while melting point at 236oC indicating drop in thermal transitions after addition of comonomer.
III. Mechanical properties:
The mechanical properties of the yarn obtained in example 3 by using the elastomeric co-polyester obtained in example 1 were measured using the Universal Testing Machine from Instron. Table 2 illustrates the mechanical properties.
Table 2:
Sr. No Mechanical Property PET homopolymer Elastomeric co-polyester -15% bis(2-hydroxyethyl)dimerate Elastomeric co-polyester - 25% bis(2-hydroxyethyl)dimerate
1. Elastic Recovery (%) 47.6 86.9 91.6
2. Tenacity (gpd) 3.3 1.7 1.2
3. Elongation (%) 34.5 53.6 60.8
4. Shrinkage (%) 4.4 24.8 6.9
5.
Modulus @ 5%Elongation 22.5 27.3 7.7
6. Modulus @ 10%Elongation 14.1 15.4 5.6
From table 2, it is observed that the elastomeric co-polyester with 25% copolymer content exhibited superior elastic recovery and elongation, measured by cyclic loading tests.
TECHNICAL ADVANCES AND ECONOMIC SIGNIFICANCE
The present disclosure described herein above has several technical advantages including, but not limited to, the realization of a process for preparing an elastomeric co-polyester, which
• is simple;
• is eco-friendly; and
• is economical and profitable;
and
the elastomeric co-polyester obtained by the process of the present disclosure:
• has a superior elastic properties.
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 mentioned for the various physical parameters, dimensions or quantities are only approximations and it is envisaged that the values higher/lower than the numerical values assigned to the parameters, dimensions or quantities fall within the scope of the disclosure, unless there is a statement in the specification specific to the contrary.
While considerable emphasis has been placed herein on the components and component parts of the preferred embodiments, it will be appreciated that many embodiments can be made and that many changes can be made in the preferred embodiments without departing from the principles of the disclosure. These and other changes in the preferred embodiment as well as other embodiments 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. , C , Claims:WE CLAIM:
1. A process for the preparation of an elastomeric co-polyester, said process comprising the following steps:
a) esterifying a predetermined amount of a diacid and a predetermined amount of a first diol in the presence of a first catalyst at a first predetermined process conditions to obtain a first oligomer;
b) separately, esterifying a predetermined amount of a fatty acid and a predetermined amount of a second diol in the presence of a second catalyst at a second predetermined process conditions to obtain a second oligomer;
c) mixing said first oligomer and said second oligomer in a predetermined ratio at a predetermined speed for a predetermined time period to obtain a mixture; and
d) polycondensing said mixture at a third predetermined process conditions to obtain said elastomeric co-polyester.
2. The process ad claimed in claim 1, wherein said diacid is at least one selected from the group consisting of terephthalic acid, isophthalic acid, naphthalene dicarboxylic acid and diphenyl dicarboxylic acid.
3. The process ad claimed in claim 1, wherein said first diol is at least one selected from the group consisting of monoethylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, trimethylene glycol, tetramethylene glycol, cyclohexane dimethanol and aromatic diol.
4. The process as claimed in claim 3, wherein said aromatic diol is selected from 2,2-bis(4-hydroxyphenyl)propane, bis(4-hydroxyphenyl) sulphone and bis(4-hydroxydiphenyl)methane.
5. The process as claimed in claim 1, wherein said fatty acid is at least one selected from the group consisting of dimer fatty acid, dimerized oleic acid, trimerized oleic acid, dimerized linoleic acid, trimerized linoleic acid, dimerized linolenic acid and trimerized linolenic acid.
6. The process as claimed in claim 1, wherein said second diol is at least one selected from the group consisting of monoethylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, trimethylene glycol, tetramethylene glycol, cyclohexane dimethanol and aromatic diol.
7. The process as claimed in claim 6, wherein said aromatic diol is selected from 2,2-bis(4-hydroxyphenyl)propane, bis(4-hydroxyphenyl) sulphone and bis(4-hydroxydiphenyl)methane.
8. The process as claimed in claim 1, wherein said predetermined amount of said diacid is in the range of 50 mass% to 86 mass% with respect to the total mass of the first oligomer.
9. The process as claimed in claim 1, wherein said predetermined amount of said first diol in step a) is in the range of 30 mass% to 60 mass% with respect to the total mass of the first oligomer.
10. The process as claimed in claim 1, wherein said first predetermined process conditions include a temperature in the range of 200 ºC to 300 ºC; and a pressure in the range of 2 kg/cm2 to 2.5 kg/cm2.
11. The process as claimed in claim 1, wherein said predetermined amount of said fatty acid is in the range of 50 mass% to 90 mass% with respect to the total mass of the second oligomer.
12. The process as claimed in claim 1, wherein said predetermined amount of said second diol in step b) is in the range of 15 mass% to 50 mass% with respect to the total mass of the second oligomer.
13. The process as claimed in claim 1, wherein said first catalyst is selected from the group consisting of antimony trioxide, antimony triacetate, germanium dioxide and zinc acetate.
14. The process as claimed in claim 1, wherein said second catalyst is selected from titanium butoxide, titanyl oxalates, titanium halides, hydrolyzed products of titanium halides, titanium hydroxide, and titanium oxide hydrate.
15. The process as claimed in claim 1, wherein said second predetermined process conditions include a temperature in the range of 150 ºC to 250 ºC and at atmospheric pressure.
16. The process as claimed in claim 1, wherein said predetermined ratio of said first oligomer to said second oligomer is in the range of 1:0.05 to 1:0.5
17. The process as claimed in claim 1, wherein said predetermined speed is in the range of 1350 rpm to 1450 rpm.
18. The process as claimed in claim 1, wherein said predetermined time period is in the range of 60 minutes to 120 minutes.
19. The process as claimed in claim 1, wherein said third predetermined process conditions include a temperature in the range of 250 ºC to 300 ºC and a vacuum in the range of 0.1 mmHg to 10 mmHg.

Dated this 21st 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