Claims:1. Modified polyester fibers comprising hydrated kaolin in the range of 0.25 %w/w to 1.0 %w/w, preferably 0.25 %w/w to 0.75 %w/w; said hydrated kaolin being characterized by particle size in the range of 0.4 microns to 4.0 microns.

2. The modified polyester fibers as claimed in claim 1, wherein said polyester is at least one selected from the group consisting of polyethylene terephthalate (PET), polyglycolic acid (PGA), polylactic acid (PLA), polycaprolactone (PCL), polyhydroxyalkanoate (PHA), polyhydroxybutyrate (PHB), polybutylene terephthalate (PBT), polytrimethylene terephthalate (PTT), polytrimethylene napthalate (PTN), polybutylene naphthalate (PBN), polyethylene naphthalate (PEN) and vectran.

3. A process for the preparation of modified polyester fibers as claimed in claim 1; said process comprising the following steps:
esterifying at least one glycol with at least one acid in a molar ratio in the range of 1.5:1 to 2:1 in the presence of at least one catalyst, sodium hydroxide and phosphoric acid at a temperature in the range of 250°C to 295°C and at a nitrogen pressure in the range of 0.2 kg/cm2 to 2.0 kg/cm2 to obtain an esterification product;
dispersing hydrated kaolin in glycol in a molar ratio in the range of 0.05:1 to 0.2:1 to obtain a dispersion;
introducing said dispersion in said esterification product to obtain an admixture;
polycondensing said admixture at a temperature in the range of 260°C to 290°C and under a pressure in the range of 0.1 mm Hg to 1 mm Hg to obtain a modified polyester; and
melt spinning said modified polyester at a temperature in the range of 250°C to 295°C to obtain said modified polyester fibers wherein, the draw ratio for obtaining the modified polyester fibers is in the range of 2.0 to 4.0 and the percent elongation of the modified polyester fibers is in the range of 30 % to 50 %;
wherein, the denier to filament ratio of the modified polyester fibers is in the range of 0.83 to 2.22.

4. The process as claimed in claim 3, wherein said dispersion is added before or during said step of esterification.

5. The process as claimed in claim 3, wherein the denier of the modified polyester fiber is in the range of 90 units to 160 units, preferably in the range of 102 units to 150.8 units and the tenacity of the modified polyester fiber is in the range of 3.0 gpd to 5.0 gpd, preferably in the range of 3.8 gpd to 4.3 gpd.

6. A cement based composition comprising:
i. modified polyester fibers of claim 1 in an amount in the range of 0.4 % to 1.0 % with respect to the total mass of the composition; and
ii. cement in an amount in the range of 45 % to 65 % with respect to the total mass of the composition.

7. The composition as claimed in claim 6 which includes asbestos fibers, wood pulp and fly ash.

8. The composition as claimed in claim 7 in which the asbestos fibers is in an amount between 5.0 % and 8.0 %, wood pulp is in an amount between 1.3 % and 2 % and fly ash is in an amount between 35 % and 40 % with respect to the total mass of the composition.

9. A process for manufacturing an article, said process comprising the following steps:
dispersing said modified polyester fibers as claimed in claim 1, in water to obtain a dispersion;
preparing a slurry comprising pulp and water;
mixing said dispersion and said slurry to obtain a mixture;
gradually adding fly ash and cement containing asbestos fibers to said mixture while stirring to obtain an admixture;
molding said admixture in a mold under pressure to obtain a green molded mass; and
air curing said mass to form said article.

10. An article manufactured by the process as claimed in claim 9. , Description:The present application is Divisional application to the patent application number 4170/MUM/2014 dated 26/12/2014.
FIELD
The present disclosure relates to a process for the preparation of modified polyester fibers and articles manufactured therefrom for its use in construction.
DEFINITIONS OF TERMS USED IN THE SPECIFICATION
The term ‘Denier’ (abbreviated D), used hereinafter in the specification refers to a unit of measure for the linear mass density of fibers and is defined as the mass in grams per 9000 meters of fibers.
The term ‘denier per filament’ (DPF), used hereinafter in the specification refers to a ratio of total denier to the quantity of uniform filaments.
The term ‘tenacity’ used hereinafter in the specification refers to a customary measure of strength of a fiber or yarn and is defined as the ultimate (breaking) force of the fiber (in gram-force units) divided by the denier.
The terms ‘L, a, b’ used hereinafter in the specification refers to a Lab color-opponent space with dimension ‘L’ for lightness and ‘a’, ‘b’ for the color-opponent dimensions, based on nonlinearly compressed coordinates.
The term ‘MRT’ used hereinafter in the specification refers to test modulus of rupture, defined as the stress in a material just before it yields in a flexure test.
The term ‘MRA’ used hereinafter in the specification refers to the modulus of rupture adjusted to the dry density of the cement specimen.
The term ‘asbestos replacement ratio of 5:25’ for a cement based composition used hereinafter in the specification refers to reducing 25 % w/w of the asbestos in the composition and adding polyester fibers in an amount of 5 % w/w of the asbestos in the composition.
The term ‘pulp’ used hereinafter in the specification refers to wood pulp.
These definitions are in addition to those expressed in the art.

BACKGROUND
Asbestos has been conventionally used in cement for construction purposes due to its desirable physical properties; it is associated with, such as sound absorption, tensile strength, resistance to fire, heat, electrical and chemical damage and affordability. Recently, the carcinogenic potential of asbestos has been brought to light, because of which several nations have banned its use. Asbestos has been replaced with polyester fiber either partially or completely.
An important parameter of an element in the construction industry is its modulus of rupture denoted by the terms MRT and MRA. The term MRT refers to test modulus of rupture, defined as the stress in a material just before it yields in a flexure test and the term MRA refers to the modulus of rupture adjusted to the dry density of the cement specimen. These are important structural parameters for use of an element in construction, particularly load bearing elements. However, the articles manufactured from the cement containing polyester fibers are observed to have MRT and MRA values of 143 kg/cm2 and 144 kg/cm2, respectively.
Since, the articles manufactured from the cement containing polyester fibers have low MRA and MRT values, therefore, there is felt a need to develop a substitute that can increase these values of a construction element.
OBJECTS
Some of the objects of the present disclosure, of 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 modified polyester fiber and a process for the preparation thereof.
Another object of the present disclosure is to provide a composition for construction purposes which is safe and environmentally friendly.
Another object of the present disclosure is to provide a process for the preparation of the afore-stated composition and the article(s) manufactured therefrom.
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 provides kaolin modified polyester fibers and a process for preparation thereof, for inclusion in cement based compositions for construction purposes. The present disclosure also provides a process for the preparation of the aforementioned composition and article(s) manufactured therefrom.
In accordance with an aspect of the present disclosure, the modified polyester fibers of the present disclosure contain 0.25 %w/w to 1.0 %w/w of hydrated kaolin, preferably 0.25 %w/w to 0.75 %w/w of hydrated kaolin with the particle size of the kaolin being in the range of 0.4 microns to 4.0 microns.
In accordance with an embodiment, the polyesters used to obtain modified polyester fibers of the present disclosure is at least one selected from the group consisting of polyethylene terephthalate (PET), polyglycolic acid (PGA), polylactic acid (PLA), polycaprolactone (PCL), polyhydroxyalkanoate (PHA), polyhydroxybutyrate (PHB), polybutylene terephthalate (PBT), polytrimethylene terephthalate (PTT), polytrimethylene napthalate (PTN), polybutylene naphthalate (PBN), polyethylene naphthalate (PEN) and vectran.
In accordance with another aspect, the present disclosure further provides a process for the preparation of modified polyester fibers. The process includes esterification of a glycol with an acid in a molar ratio in the range of 1.5:1 to 2:1 in the presence of a catalyst at a temperature in the range of 250°C to 295°C and at a nitrogen pressure in the range of 0.2 kg/cm2 to 2.0 kg/cm2 to realize an esterification product. Hydrated kaolin is dispersed in glycol in a molar ratio in the range of 0.05:1 to 0.2:1 to obtain a dispersion of kaolin in glycol. The so obtained dispersion of kaolin in glycol is thereafter introduced into the esterification product while stirring with an agitator to form an admixture thereof. The admixture is polycondensed at a temperature in the range of 260°C to 290°C and under a pressure in the range of 0.1 mm Hg to 1 mm Hg. The viscosity of the polycondensed product increases due to polymerization. The final mixing speed maintained during agitation is in the range of 1100 rpm to 1500 rpm. After 38 % rise in torque, the vacuum is broken and the reactor is pressurized with nitrogen, modified polyester is then drained and drawn into strands. The modified polyester is then melt spun at a temperature in the range of 250°C to 295°C to obtain modified polyester fibers.
Typically, the modified polyester fibers are obtained by a process which includes esterification of monoethylene glycol with purified terephthalic acid in a molar ratio of 1.86:1 in the presence of a catalyst at a temperature of 260°C and at a nitrogen pressure of 1.7 kg/cm2 to obtain an esterification product. Hydrated kaolin is dispersed in mono ethylene glycol in a molar ratio in the range of 0.07:1 to 0.15:1 to obtain a dispersion. The dispersion is then introduced in the esterification product while stirring with an agitator to obtain an admixture. In a further step, polycondensation of the admixture is achieved at a temperature of 290°C and under a pressure in the range of 0.18 mm Hg to 0.28 mm Hg. The viscosity of the polycondensed product increases due to polymerization. The final mixing speed maintained during agitation is 1300 rpm. After 38 % rise in torque, the vacuum is broken and the reactor is pressurized with nitrogen, modified polyester is then drained and drawn into strands. Melt spinning of the as obtained modified polyester at a temperature of 276.5°C provides the modified polyester fibers.
In one embodiment, the dispersion can be added before or during the step of esterification.
In accordance with an embodiment, the present disclosure provides a cement based composition containing modified polyester fibers in an amount in the range of 0.4 % to 1.0 % and cement in an amount in the range of 45 % to 65 % with respect to the total mass of the composition.
In accordance with another embodiment, the present disclosure provides a process for manufacturing an article from the cement based composition which includes dispersing the modified polyester fibers in water to obtain a dispersion; preparing a slurry comprising pulp and water; mixing the dispersion and the slurry to obtain a mixture; gradually adding fly ash and cement containing asbestos fibers to the mixture while stirring to obtain an admixture; molding the admixture in a mold under pressure to obtain a green molded mass; and air curing the mass to obtain an article.

DETAILED DESCRIPTION:
In accordance with one aspect, the present disclosure provides modified polyester fibers. The modified polyester fibers of the present disclosure consist of polyester fibers modified with kaolin. Typically, kaolin is present in an amount in the range of 0.25 % to 1.0 % of the total mass of the polyester fibers. Kaolin present in the polyester fibers has good compatibility with the cement present in the composition. This results in a strong bonding between the constituents of the composition; thereby enhancing the strength of the resulting construction articles such as bricks, slabs and the like. Furthermore, the kaolin gives a better dispersion of polyester in cement.
In one embodiment, the kaolin used in the present disclosure is hydrated kaolin having the formula: Al2O3•2SiO2•2H2O. Furthermore, the kaolin is characterized by a particle size in the range of 0.4 microns to 4.0 microns.
The polyester obtained in the present disclosure is at least one selected from the group consisting of polyethylene terephthalate (PET), polyglycolic acid (PGA), polylactic acid (PLA), polycaprolactone (PCL), polyhydroxyalkanoate (PHA), polyhydroxybutyrate (PHB), polybutylene terephthalate (PBT), polytrimethylene terephthalate (PTT), polytrimethylene napthalate (PTN), polybutylene naphthalate (PBN), polyethylene naphthalate (PEN) and vectran.
In accordance with embodiments of the present disclosure, there is provided a process for the preparation of the modified polyester fibers.
In one embodiment, the hydrated kaolin is added before, during or after the esterification process.
In another embodiment, the process for preparing the modified polyester fibers includes the steps presented herein after. Initially, an esterification product is obtained in a vessel by esterifying glycol with an acid in a molar ratio in the range of 1.5:1 to 2:1 in the presence of a catalyst at a temperature in the range of 250°C to 295°C and at a nitrogen pressure in the range of 0.2 kg/cm2 to 2.0 kg/cm2. In another vessel, a dispersion of hydrated kaolin in glycol in a molar ratio in the range of 0.05:1 to 0.2:1 is prepared. The obtained dispersion is then introduced in the esterified product while stirring with an agitator, thus forming an admixture which is further polycondensed at a temperature in the range of 260°C to 290°C and under a pressure in the range of 0.1 mm Hg to 1 mm Hg. The viscosity of the polycondensed product increases due to polymerization. The final mixing speed maintained during agitation is in the range of 1100 rpm to 1500 rpm. After 38 % rise in torque, the vacuum is broken and the reactor is pressurized with nitrogen, modified polyester is then drained and drawn into strands. Modified polyester is then melt spun at a temperature in the range of 250°C to 295°C to obtain modified polyester fibers.
Typically, the process of obtaining modified polyester fibers includes esterification of monoethylene glycol with purified terephthalic acid in a molar ratio of 1.86:1 in the presence of a catalyst at a temperature of 260°C and at a nitrogen pressure of 1.7 kg/cm2 to obtain an esterification product. A dispersion of hydrated kaolin in glycol in a molar ratio in the range of 0.07:1 to 0.15:1 is prepared in another vessel. The dispersion is then introduced in the esterification product while stirring with an agitator to obtain an admixture. In a further step, polycondensation of the admixture is achieved at a temperature of 290°C and under a pressure in the range of 0.18 mm Hg to 0.28 mm. The viscosity of the polycondensed product increases due to polymerization. The final mixing speed maintained during agitation is 1300 rpm. After 38% rise in torque, the vacuum is broken and the reactor is pressurized with nitrogen, modified polyester is then drained and drawn into strands. Melt spinning of the as obtained modified polyester at a temperature of 276.5°C results in the modified polyester fibers.
In accordance with the present disclosure, the molar ratio of monoethylene glycol to purified terephthalic acid is in the range of 1.5:1 to 2:1, preferably 1.86:1.
In accordance with the present disclosure, NaOH is added as a diethylene glycol suppressant at the start of the esterification reaction and in the range of 15 ppm to 35 ppm, preferably 25ppm.
In accordance with the present disclosure, phosphoric acid is added as a thermal stabilizer at the start of the esterification reaction and is in the range of 15 ppm to 35 ppm, preferably 25ppm.
In accordance with the present disclosure, the molar ratio of hydrated kaolin to monoethylene glycol is in the range of 0.05:1 to 0.2:1, preferably in the range of 0.07:1 to 0.15:1.
In accordance with the present disclosure, the polycondensed product is obtained by agitation at a speed in the range of 1100 rpm to 1500 rpm, preferably 1300 rpm.
In accordance with the present disclosure, the esterification time is in the range of 240 min to 270 min, preferably in the range of 254 min to 256 min.
In accordance with the present disclosure, the polycondensation time is in the range of 110 min to 140 min, preferably in the range of 121 min to 131 min.
In accordance with the present disclosure, the intrinsic viscosity of the modified polyester is in the range of 0.5 dL/g to 0.7 dL/g, preferably in the range of 0.596 dL/g to 0.605 dL/g.
In accordance with the present disclosure, the ‘L’ value of the modified polyester is in the range of 50 units to 65 units, ‘a’ value of the modified polyester is in the range of -0.09 units to 0.15 units and ‘b’ value of the modified polyester is in the range of 3 units to 6 units, preferably the ‘L’ value of the modified polyester is in the range of 56 units to 59.2 units, the ‘a’ value of the modified polyester is in the range of -0.08 units to 0.1 units and the ‘b’ value of the modified polyester is in the range of 4.0 units to 4.7 units.
In accordance with the present disclosure, the acid content in the modified polyester is in the range of 15 meq/kg to 20 meq/kg, preferably in the range of 17 meq/kg to 18 meq/kg.
In accordance with the present disclosure, diethylene glycol is generated during the esterification reaction as by product.
In accordance with the present disclosure, the diethylene glycol content in the modified polyester is in the range of 2 %w/w to 4 % w/w, preferably 2.2 %w/w.
In accordance with the present disclosure, the denier to filament ratio of the modified polyester fiber is in the range of 0.83 to 2.22, preferably in the range of 1.39 to 2.08.
In accordance with the present disclosure, the draw ratio for obtaining the modified polyester fiber is in the range of 2.0 to 4.0, preferably in the range of 2.8 to 3.0.
In accordance with the present disclosure, the actual denier of the modified polyester fiber is in the range of 90 units to 160 units, preferably in the range of 102 units to 150.8 units.
In accordance with the present disclosure, the percent elongation of the modified polyester fiber is in the range of 30 % to 50 %, preferably in the range of 39.0 % to 42 %.
In accordance with the present disclosure, the tenacity of the modified polyester fiber is in the range of 3.0 gpd to 5.0 gpd, preferably in the range of 3.8 gpd to 4.3 gpd.
In accordance with yet another aspect, the present disclosure provides a cement based composition for construction purposes that includes, modified polyester fibers, cement, additional occupant(s), asbestos fibers and pulp in pre-determined quantities and proportions with respect to each other.
More specifically, the cement composition comprises modified polyester fibers in an amount in the range of 0.4 % to 1.0 % with respect to the total mass of the composition; cement in an amount in the range of 45 % to 65 % with respect to the total mass of the composition and asbestos fibers in an amount between 5.0 % and 8.0 % with respect to the total mass of the composition.
The composition optionally includes excipients such as property modifying additives and fillers. The additive(s) are selected from the group that includes, vehicles, binding agents, viscosity modifiers, fillers, foamers, rheology modifiers, preservatives, deflocculants, neutralizing agents, wetting and dispersing agents. The fillers are selected from the group that includes vegetable fiber, asphalt, titanium dioxide, silica fume, fly ash, rice husk ash, slate, sand, steel, micro concrete, clay, metal, galvanized metal and coated metal.
In accordance with the present disclosure, the cement composition comprises filler.
In accordance with one embodiment of the present disclosure, the filler in the cement composition is fly ash.
In accordance with a further aspect of the present disclosure, there is provided an article that includes boards, plinths, slabs, columns, sheets, shafts, panels, planks and tiles, which is manufactured from the composition mentioned herein above.
In accordance with the present disclosure, the article is a cement sheet. More specifically the cement sheet is an air cured corrugated/flat product.
In accordance with yet another aspect, the present disclosure provides a process for the manufacturing an air cured corrugated/flat product.
The steps of this process include but are not limited to weighing the raw materials as per the ‘asbestos replacement ratio of 5:25’ where, 25 % w/w of the asbestos in the composition is reduced and modified polyester fibers are added in an amount of 5 % w/w of the asbestos in the composition. Further, the process includes obtaining a dispersion of the modified polyester fiber in water in a vessel, preparing a slurry of wood pulp and water in another vessel while stirring, adding the dispersed modified polyester fiber into the slurry to obtain a mixture, gradually adding fly-ash and cement containing asbestos fibers to the mixture to obtain an admixture, stirring the entire admixture for 1 minute, introducing the admixture in a mold, setting up a filter paper above the admixture, initiating the vacuum pump and ensuring that the vacuum port is cleared, initiating the hydraulic press, operating the hydraulic press slowly as the moisture is removed from the vacuum ports, seizing the operation of the press when the pressure reaches to 550 bar, holding the mixture at 550 bar pressure for 1 minute, slowly releasing the press, placing the supports below the mold, breaking the vacuum, removing the sheet from the hydraulic press and placing it on a wooden plate, placing the sheet for conditioning in a humidity chamber at 27°C and at 90 % humidity for 24 hours, removing the sheet and keeping it in water for 14 days for water curing and air curing all the samples for 24 hours.
In accordance with the present disclosure, the cement composition comprises fly ash in an amount between 35 % and 40 % with respect to the total mass of the composition; preferably the amount of fly ash is 36% with respect to the total mass of the composition.
In accordance with the present disclosure, the cement composition comprises wood pulp in an amount between 1.3 % and 2.0 % with respect to the total mass of the composition. Preferably the amount of wood pulp is 1.4 % with respect to the total mass of the composition.
In accordance with the present disclosure, the cement composition comprises asbestos fibers in an amount between 5.0 % and 8.0 % with respect to the total mass of the composition.
In accordance with the present disclosure, the cement used in the cement based composition is an ordinary Portland cement, 53 grade (OPC-53).
In accordance with the present disclosure, the asbestos fiber replacement ratio in the cement based composition is 5:25.
In accordance with the present disclosure, the density of the cement based composition with the modified polyester fiber is in the range of 1.0 g/cc to 2.0 g/cc, preferably 1.4 g/cc.
In accordance with the present disclosure, the MRT value of the articles prepared from the cement based composition containing the modified polyester fiber is in the range of 140 kg/cm2 to 160 kg/cm2, preferably in the range of 152.2 kg/cm2 to 154.4 kg/cm2.
In accordance with the present disclosure, the MRA value of the articles prepared from the cement based composition containing the modified polyester fiber is in the range of 140 kg/cm2 to 160 kg/cm2, preferably in the range of 153 kg/cm2 to 155 kg/cm2.
In accordance with the present disclosure, the percent improvement in MRA of the articles prepared from the cement based composition containing the modified polyester fiber is in the range of 4 % to 10 %, preferably in the range of 6.2 % to 7.6 % with respect to the cement composition containing commercial grade polyester fiber.
The present disclosure is further illustrated herein below with the help of the following experiments. The laboratory experiments used herein are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the experiments should not be construed as limiting the scope of embodiments herein. These laboratory scale experiments can be scaled up to an industrial/commercial scale.
(A) Experiment describing the preparation of polyester fiber and modified polyester fiber:
Experiment 1 (Comparative experiment) - Process to obtain polyester fiber:
Slurry of monoethylene glycol (MEG) and purified terephthalic acid (PTA) in molar ratio of 1.86:1 was prepared in a vessel. 290 ppm of catalyst Sb2O3, 25 ppm of NaOH and 25 ppm of phosphoric acid were added to the slurry while stirring with an agitator and the esterification reaction was carried out under a nitrogen pressure of 1.7 kg/cm2, at a temperature of 260°C and for a duration of 214 min to obtain an esterification product. The obtained esterified product was then transferred to a polycondensation reactor. Vacuum was applied slowly to the polycondensation reactor and a final vacuum of 0.11 mm Hg was attained in 45 minutes. The temperature was gradually increased to 290°C and maintained at 290°C for duration of 118 min. As the reaction progressed, the viscosity of the polycondensed product (polyester) increased due to polymerization. The final mixing speed maintained during agitation was 1300 rpm. After 38 % rise in torque the vacuum was broken and the reactor was pressurized with nitrogen, polyester was then drained and drawn into strands, subsequently followed by quenching in a water bath. The strands were then cut into chips in a pelletizer and further dried at a temperature of 140°C under hot nitrogen for 180 min to remove the moisture. The chips were then melt spun into filaments at a melt temperature of 276.5°C. The filaments produced were coated with a spin finish and were cut into ranges from 6mm to 12mm cut length to obtain polyester fibers, which were used for the preparation of cement sheet.
Experiment 2 to 5 (In accordance with the present disclosure) - Process to obtain kaolin modified polyester fiber also referred to as modified polyester fiber:
Slurry of monoethylene glycol (MEG) and purified terephthalic acid (PTA) in a molar ratio of 1.86:1 was prepared in a vessel. 290 ppm of catalyst Sb2O3, 25 ppm of NaOH and 25 ppm of phosphoric acid were added to the slurry and the esterification reaction was carried out under a nitrogen pressure of 1.7 kg/cm2, at a temperature of 260°C and for a time period in the range of 254 min to 256 min to obtain an esterification product. A dispersion of appropriate quantities of kaolin in monoethylene glycol as mentioned in table 1 was prepared in another vessel. The dispersion was then added to the esterification product while stirring with an agitator to obtain an admixture. The obtained admixture was then transferred to a polycondensation reactor. Vacuum was applied slowly to the polycondensation reactor and the final vacuum in the range of 0.18 mm Hg to 0.28 mm Hg was attained in 45 minutes. The temperature was gradually increased to 290°C and maintained at 290°C for a time period in the range of 121 min to 131 min. As the reaction progressed, the viscosity of the polycondensed product (modified polyester) or the modified polymer product increased due to polymerization. The final mixing speed maintained during agitation was 1300 rpm. After 38 % rise in torque, the vacuum was broken and the reactor was pressurized with nitrogen, modified polyester was then drained and drawn into strands, subsequently followed by quenching in a water bath. The strands were then cut into chips in a pelletizer and further dried at a temperature of 140°C under hot nitrogen for 180 min to remove the moisture. The kaolin content in the chips was determined based on the ash content obtained by heating the modified polyester at 650°C in a furnace for one hour. The chips were found to comprise 0.25 % to 0.75 % by weight of kaolin. The chips were then melt spun into filaments at a melt temperature of 276.5°C. The filaments produced were coated with a spin finish and were cut into 6.0 mm cut length to obtain modified polyester fiber, which were used for the preparation of cement sheet. No adverse effect in polymerization was observed due to the addition of kaolin.
The following experiments were performed to obtain polyethylene terephthalate polyester (polyester) and modified polyethylene terephthalate polyester (modified polyester). Experimental details are provided in table 1.

Experiment 1 (Comparative experiment): Polyester
Experiment 2 (In accordance with the present disclosure): Modified polyester containing 0.25 % kaolin
Experiment 3 (In accordance with the present disclosure): Modified polyester containing 0.50 % kaolin
Experiment 4 (In accordance with the present disclosure): Modified polyester containing 0.75 % kaolin

Table 1:
Ingredients/Parameters Units Experiment number
1 2 3 4
Monoethylene glycol (MEG) kg 36.5 36.5 36.5 36.5
Purified terephthalic acid (PTA) kg 52.3 52.3 52.3 52.3
Mole ratio MEG: PTA - 1.86:1 1.86:1 1.86:1 1.86:1
Antimony trioxide (Sb2O3) ppm 290 290 290 290
Sodium hydroxide (NaOH) ppm 25 25 25 25
Phosphoric acid (H3PO4) ppm 25 25 25 25

Dispersion of Kaolin in MEG Kaolin g - 150 300 450
MEG g - 500 500 700
Mole ratio Kaolin: MEG - - 0.07:1 0.14:1 0.15:1
Process parameters
Esterification temperature °C 260 260 260 260
Esterification time min 214 256 254 256
Polycondensation time min 118 123 121 131
Final batch temperature °C 290 290 290 290
Final vacuum mm Hg 0.11 0.28 0.18 0.26
Final rpm rpm 1300 1300 1300 1300
Quality parameters
IV (Intrinsic viscosity) dL/g 0.617 0.6 0.596 0.605
L Hunter 63.3 59.2 56 57.3
a Hunter 0.03 -0.08 0.1 0.0
b Hunter 4.6 4.23 4 4.7
COOH meq/Kg 29 18 17 18
DEG (Diethylene glycol) % w/w 2.33 2.2 - 2.2
It is inferred from table 1 that there is no significant change in the intrinsic viscosity, ‘L’ value, ‘a’ value, ‘b’ value, acid content and diethylene glycol content of the modified polyesters obtained in experiments 2, 3 and 4 with respect to the polyester obtained in experiment 1.
The modified polyester obtained after esterification and polycondensation was then subjected to melt spinning to obtain modified polyester fibers.

The following experiments were performed to obtain polyester fibers and modified polyester fibers by melt spinning. Experimental details are provided in table 2.
Experiment 5 (Comparative experiment): Polyester obtained from experiment 1 was used to prepare polyester fiber.
Experiment 6 (Comparative experiment): Polyester obtained from experiment 1 was used to prepare polyester fiber.
Experiment 7 (In accordance with the present disclosure): Modified polyester fiber containing 0.25 % kaolin-Modified polyester obtained from experiment 2 was used to prepare polyester fiber with 0.25 % kaolin.
Experiment 8 (In accordance with the present disclosure): Modified polyester fiber containing 0.25 % kaolin- Modified polyester obtained from experiment 2 was used to prepare polyester fiber with 0.25 % kaolin.
Experiment 9 (In accordance with the present disclosure): Modified polyester fiber containing 0.50 % kaolin- Modified polyester obtained from experiment 3 was used to prepare polyester fiber with 0.50 % kaolin.
Experiment 10 (In accordance with the present disclosure): Modified polyester containing 0.50 % kaolin-Modified polyester obtained from experiment 3 was used to prepare polyester fiber with 0.50 % kaolin.
Experiment 11 (In accordance with the present disclosure): Modified polyester containing 0.75 % kaolin-Modified polyester obtained from experiment 4 was used to prepare polyester fiber with 0.75 % kaolin.
Experiment 12 (In accordance with the present disclosure): Modified polyester containing 0.75 % kaolin-Modified polyester obtained from experiment 4 was used to prepare polyester fiber with 0.75 % kaolin.

Table 2:
Parameters/Properties Units Experiment number
5 6 7 8 9 10 11 12
Denier/Filament ratio - 1.39 2.08 1.39 2.08 1.39 2.08 1.39 2.08
Melt temperature °C 276.5 276.5 276.5 276.5 276.5 276.5 276.5 276.5
Draw ratio - 2.8 3 2.8 3 2.8 3 2.8 3
Winding Speed mpm 3200 3200 3200 3200 3200 3200 3200 3200
Actual denier - 105.5 150.5 104 150.3 104 150.8 102 150.8
Elongation % 34.9 43 39 42 40 42 42 40
Tenacity gpd 4.04 3.75 4.3 3.95 4.2 3.95 4.25 3.8
It is inferred from table 2, that there is no significant change in the actual denier and tenacity of the modified polyester fibers obtained in experiments 7 to 12 with respect to the polyester fibers obtained in experiments 5 and 6.
(B) Composition of the present disclosure
A series of trials were carried out for preparing the composition disclosed in the present disclosure. The contents and the amounts in which the ingredients were present are provided herein below in the form of Table 3.

Table 3: Composition of the present disclosure
Sr. No. Name of ingredient Quantity
(% with respect to the total mass of the composition)

1 Modified polyester fibers 0.48
2 Cement 54.9
3 Asbestos fibers 6.7
4 Pulp 1.4
5 Fly ash 36.5

The air cured corrugated/flat products were manufactured from the composition mentioned in table 3 and as per the method described in detailed description. Experimental details are provided in table 4.

Experiment 13 (Comparative experiment): Cement composition with commercial polyester fiber
Experiment 14 (In accordance with the present disclosure): Cement composition with modified polyester fiber containing 0.75 % kaolin
Experiment 15 (In accordance with the present disclosure): Cement composition with modified polyester fiber containing 0.75 % kaolin

Table 4:
Ingredients/Parameters/Properties Units Experiment number
13 14 15
Total solids g 145.1 145.1 145.1
Cement (OPC-53 grade) containing 9.8g asbestos fibers g 89.4 89.4 89.4
Fly ash g 53 53 53
Pulp g 2 2 2
Commercial grade
Polyester fibers g 0.7 - -
Modified Polyester fibers g - 0.7 0.7
Density g/cc 1.4 1.4 1.4
MRT kg/cm2 143.3 152.2 154.4
MRA kg/cm2 144 153 155
Improvement in MRA w.r.t experiment 13 % NA 6.2 7.6
It is inferred from table 4 that the articles prepared from the cement based composition with modified polyester fiber containing 0.75 % kaolin (experiments 14 and 15) provides 6.2 % and 7.6 % strength improvement in MRA with respect to the articles prepared from the cement based composition with the commercial grade polyester fiber (experiment 13).
TECHNICAL ADVANCES AND ECONOMICAL SIGNIFICANCE
The present disclosure described herein above has several technical advantages including, but not limited to, the realization of:
? a modified polyester fiber;
? a process to obtain modified polyester fiber;
? a process to obtain a cement based composition using modified polyester fiber;
? a process to obtain air cured corrugated/flat products from the aforestated composition;
? an environmental friendly alternative for asbestos in the form of modified polyester fiber for use in a cement composition for construction purpose.
The exemplary embodiment herein quantifies the benefits arising out of this disclosure and the various features and advantageous details thereof are explained with reference to the non-limiting embodiments in the description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein.
The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein.
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 disclosure to achieve one or more of the desired objects or results.
Any discussion of documents, acts, materials, devices, articles and the like that has been included in this specification is solely for the purpose of providing a context for the disclosure. It is not to be taken as an admission that any or all of these matters form a part of the prior art base or were common general knowledge in the field relevant to the disclosure as it existed anywhere before the priority date of this application.
The numerical values mentioned for the various physical parameters, dimensions or quantities are only approximations and it is envisaged that the values ten percent 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 particular features of this disclosure, it will be appreciated that various modifications 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 modifications in the nature of the disclosure or the preferred embodiments 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