WO2012017453A1

WO2012017453A1 - High luster acrylic fiber and process for manufacturing the same

Info

Publication number: WO2012017453A1
Application number: PCT/IN2011/000513
Authority: WO
Inventors: Sahoo Anasuya; Lodha Preeti
Original assignee: Aditya Birla Science And Technology Co.Ltd.
Priority date: 2010-08-03
Filing date: 2011-08-03
Publication date: 2012-02-09

Abstract

A polymer dope composition is provided. Said dope composition comprises 5-20% of acrylic polymer; 30-50% of sodium thiocyanate; and 0.01-30% of first additive. Additionally, a high luster acrylic fiber manufactured by the polymer dope composition and a process for manufacturing the same are provided.

Description

HIGH LUSTER ACRYLIC FIBER AND PROCESS FOR MANUFACTURING THE

SAME

FIELD OF THE INVENTION

The present invention relates a modified polymer dope composition. The present invention also relates to high luster acrylic fibers and a process for manufacturing the same.

BACKGROUND TO THE INVENTION

Acrylic fibers are synthetic fibers containing at least 50% of acrylonitrile monomer. The acrylic fibers are prepared from a polymer polyacrylonitrile which is obtained by free radical polymerization with an average molecular weight of - 100,000. Acrylic is lightweight, soft, and warm, with a wool-like feel. It is resilient, retains its shape, and resists shrinkage and wrinkles. Acrylic fibers arc commonly used in sweaters, hand-knitting yarns, rugs, awnings, boat covers, and beanies; the fiber is also used as a precursor for carbon fiber.

In recent years, synthetic fiber technology has advanced to the stage at which it has been recognized that useful properties can be imparted to synthetic fibers by modifying the cross-sectional configurations which are other than round, such as of dog-bone or dumbbell cross-sectional configuration (e.g. Vinyon^rM or Orion ^{1 M} from the Dimethyl Formamide based process), kidney shaped (e.g. Acrilan^rM from the Dimethyl acetamide based process).

Fibers with non-circular cross-section result in fabrics with significantly different appearances as compared to fabrics made of round fibers. Also, non-circular fibers have higher surface area than corresponding fabrics made of round fibers of comparable denier, which also affect luster, smoothness, wickability, dyeability, drape and other related properties.

The appearance of any product is one of its most important properties which greatly influences a customer's choice for the product, and the luster or gloss of the surface of the fabric is one of the key attributes which affects the appearance and hence the aesthetic performance of the textile fabric. According to the American Society of Testing and Materials, luster is "the appearance characteristic of a surface that reflects more light in some directions than it does in other directions, i.e. it is the amount of specular light the fabric reflects"

Wet spun acrylic fibers with inorganic solvent based systems tend to have circular cross-sections where as non-circular cross-section have been reported in case of acrylic fibers made using organic solvent based systems. Inorganic solvent based acrylic fibers also have lower gloss/luster and softness as compared to organic solvent based acrylic fibers.

Various efforts to make fibers with non-circular cross-section from an inorganic system primarily focus on the use of non-circular spinnerets. Such spinnerets tend to be expensive due to high fabrication cost and in some cases, are more prone to damage when used under high pressure. Productivity is also low because of the low pressure resistance of polymeric spinnerets.

EXISTING KNOWLEDGE

Efforts in the prior art which focused on obtaining fibers having non-circular cross-sections by wet-spinning method using an inorganic solvent have not been successful from an industrial viewpoint.

• Use of Non-circular spinneret: For example, as described in Japanese Patent publication number 2328/1970, satisfactory fibers having non-circular cross-sections can be obtained by using a plastic-made spinneret having a non-circular orifice, but this process results in an industrial problem in that the productivity is low because the spinneret has a low pressure resistance.

To counter this problem, a method was proposed wherein fibers extruded through a metallic spinneret having circular orifices located near to each other, are agglutinated and united to form fibers with non-circular cross-sections. However, in this method, there is unevenness in the agglutination between the peripheral and central parts of the spinneret, so that there are different cross-sectional shapes and also fibers of non-united, circular cross-sections are present in mixture.

In US3676540(1972) and US3760053(1973), methods are disclosed for making shaped fibers by using rectangular spinnerets of low thermal conductivity, such as of plastic material, and unusually high jet stretch.

• Modification of Spinning Process:

US patent No. 45101 1 1(1985) discloses a method to produce cocoon shaped acrylic fibers by a two step coagulation process wherein the first coagulation bath is an aqueous solution of STC having concentration 5% -35% at temperature -5°C to 5°C and residence time is d* l/4 to d seconds (where d is the denier of the filament). The second coagulation bath is maintained with aqueous sodium thiocyanate solution of concentration 5-35% at temperature 6°C - 40°C for a time period of more than d seconds. However, the method disclosed in the US patent No. 45101 1 1 does not provide consistent result.

Polymer Modification: In US3767755 (1973), a method is disclosed to produce non circular brilliant acrylic fiber by modifying the acrylonitrile polymer using methacrylamide or di (lower alkyl) acrylamide. However, the process disclosed in US3767755 does not provide acrylic fiber with high luster.

Accordingly, it is desirable to develop a modified polymer dope composition which can be used to prepare a high luster acrylic fiber.

OBJECTS OF THE INVENTION

It is an object of the present invention to provide a modified polymer dope composition for manufacturing high luster acrylic fiber.

It is another object of the present invention to provide a process for manufacturing high luster acrylic fiber.

It is still another object of the present invention to provide simple a wet-spinning process for manufacturing high luster acrylic fiber wherein the fiber is obtained by spinning a modified polymer composition through circular spinnerets into coagulating bath.

It is yet another object of the present invention to provide a process for manufacturing an acrylic fiber using a modified coagulating bath.

It is another object of the present invention to provide a process manufacturing an acrylic fiber that exhibits improved properties such as whiteness, smoothness, wickability, dyeability, drape and the like with high productivity.

It is a further object of the present invention to provide a process for manufacture a high luster fiber having a non circular or circular cross section which can be ultimately converted into fabrics having good luster, softness, smoothness, whiteness dyeability and drape.

It is still further object of the present invention to provide a process which is efficient and high yielding.

It is another object of the present invention to provide high luster acrylic fiber/yarn with non circular or circular cross section.

SUMMARY OF THE INVENTION

In accordance with the present invention there is provided a polymer dope composition for the manufacture of high luster acrylic fibers; said dope composition comprising 5-20% of acrylic polymer; 30-50% of sodium thiocyanate; and 0.01-30% of first additive, the proportions of the ingredients being based on the total mass of the dope composition.

Typically, the acrylic polymer comprises at least 50 % acrylonitrile monomer and at least one co-monomer selected from the group consisting of methacrylate, methyl methacrylate, vinyl acetate, methacrylic acid, acrylic acid, vinyl chloride, vinylidene chloride, vinyl sulfonic acid, itaconic acid, sodium styrene sulfonate, sodium methallyl sulfonate and sodium sulfophenyl methallyl ether.

Typically, the first additive is at least one compound selected from the group of compounds consisting of sodium thiocyanate, acetic acid, sodium acetate, potassium acetate, sodium chromate, sodium nitrate, sodium sulphate, sodium hexa metaphoshate, sodium dihydrogen orthophosphate dihydrate, disodium hydrogen orthophosphate dihydrate, ammonium di hydrogen phosphate, sodium carbonate, sodium bicarbonate, ammonium thiocyanate, potassium thiocyanate, calcium thiocyanate, zinc chloride, calcium chloride and ammonium chloride and sodium chloride.

In accordance with another aspect of the present invention there is provided a high luster acrylic fiber/yarn with non-circular cross section.

In accordance with another embodiment of the present invention there is provided a high luster acrylic fiber/yarn with circular cross section.

In accordance with still another aspect of the present invention there is provided a process for the manufacture of high luster acrylic fibers; said process comprising the following steps:

- preparing a polymer dope comprising 5-20% of acrylic polymer, 30-50% of sodium thiocyanate and 0.01-30% of first additive, the proportions of the ingredients being based on the total mass of the dope composition;

- extruding the polymer dope at a temperature of about 30 to about 70°C through a spinneret with circular spinning orifices into a coagulating bath comprising 0-20% of sodium thiocyanate, at least one additive selected from the group consisting of first additive, second additive & third additive and a coagulating agent to obtain coagulated filaments; and

- passing the coagulated filaments through a precipitating bath followed by washing, stretching, thermally treating to collapse voids (if any), heat- setting and drying to obtain high luster acrylic fibers.

Typically, the second additive is at least one additive selected from the group consisting of methanol, ethanol, isopropyl alcohol, n-propanol, butanol, iso butanol, pentanol, t-butyl alcohols, di-ethylene glycol, ethylene glycols, tri- ethylene glycol, glycerol, benzyl alcohol, phenol, formic acid, acetic acid, oxalic acid, acetone, diethyl ether, tetra hydro furan, mono and poly substituted alkyl ether, di methyl esters , esters of polyhydric alcohols, ester of ethylene glycol acetate, di methyl formamide, toluene and xylene.

Typically, the third additive is at least one dissociating salt consisting of a cation selected from the group consisting of lithium, zinc, calcium, magnesium, aluminum, copper, silver, iron, ammonium, quaternary ammonium and pyridinium and an anion selected from the group consisting of alkyl carboxylates, phosphates, dialkyl phosphates, alkyl phosphonate, sulfates, chlorides, bromides, iodides, nitrates and thiocyanates.

Typically, the amount of first additive present in the coagulating bath is in the range of about 0 to about 25 %.

Typically, the amount of second additive present in the coagulating bath is in the range of about 0 to about 100 %.

Typically, the amount of third additive present in the coagulating bath is in the range of about 0 to about 60 %. In one of the embodiments of the present invention the coagulating agent is water.

Typically, the step of dope preparation is carried out at a temperature of about of about 30°C to about 80°C.

Typically, the coagulating bath is maintained at a temperature of about -5°C to about 80°C.

DESCRIPTION OF THE INVENTION

In accordance with the present invention the acrylic polymer comprises at least 50 % acrylonitrile monomer and at least one co-monomer selected from the group consisting of methacrylate, methyl methacrylate, vinyl acetate, methacrylic acid, acrylic acid, vinyl chloride, vinylidene chloride, vinyl sulfonic acid, itaconic acid, sodium styrene sulfonate, sodium methallyl sulfonate and sodium sulfophenyl methallyl ether.

Typically, the first additive is at least one compound selected from the group of compounds consisting of sodium thiocyanate, acetic acid, sodium acetate, potassium acetate, sodium chromate, sodium nitrate, sodium sulphate, sodium hexa metaphoshate, sodium dihydrogen orthophosphate dihydrate, disodium hydrogen orthophosphate dihydrate, ammonium di hydrogen phosphate, sodium carbonate, sodium bicarbonate, ammonium thiocyanate, potassium thiocyanate, calcium thiocyanate, zinc chloride, calcium chloride and ammonium chloride and sodium chloride. In accordance with another aspect of the present invention there is provided a high luster acrylic fiber/yarn with non-circular cross section which is prepared by using the polymer dope composition of the present invention.

In accordance with another embodiment of the present invention there is provided a high luster acrylic fiber/yarn with circular cross section which is prepared by using the polymer dope composition of the present invention.

In accordance with still another aspect of the present invention there is provided a process for the manufacture of high luster acrylic fibers with or without a non circular cross section using a circular spinneret. The process in accordance with the present invention is an inorganic solvent based process.

The process of the present invention is described herein below.

In the first step, a polymer dope comprising 5-20% of acrylic polymer, 30-50% of sodium thiocyanate and 0.01-30% of first additive is prepared. The proportions of the ingredients are based on the total mass of the dope composition.

Typically, the step of dope preparation is carried out at a temperature of about 30°C to about 80°C.

In accordance with the present invention the acrylic polymer comprises at least 50 % acrylonitrile monomer and at least one co-monomer selected from the group consisting of methacrylate, methyl methacrylate, vinyl acetate, methacrylic acid, acrylic acid, vinyl chloride, vinylidene chloride, vinyl sulfonic acid, itaconic acid, sodium styrene sulfonate, sodium methallyl sulfonate and sodium sulfophenyl methallyl ether. The obtained polymer dope is then extruding at a temperature of about 30 to about 70°C through a spinneret with circular spinning orifices into a coagulating bath to obtain coagulated filaments. Typically, the coagulating bath comprises 0-20% of sodium thiocyanate, at least one additive selected from the group consisting of first additive, second additive, & third additive and a coagulating agent.

In accordance with the present invention the coagulating bath is maintained at a temperature of about -5°C to about 80°C.

In accordance with one of the embodiments of the present invention the residence time of filament in coagulating bath is about 0.01 to 10 seconds.

Typically, the second additive is at least one additive selected from the group consisting of methanol, ethanol, isopropyl alcohol, n-propanol, butanol, iso butanol, pentanol, t-butyl alcohols, di-ethylene glycol, ethylene glycols, tri- ethylene glycol, glycerol, benzyl alcohol, phenol, formic acid, acetic acid, oxalic acid, acetone, diethyl ether, tetra hydro furan, mono and poly substituted alkyl ether, di methyl esters , esters of polyhydric alcohols, ester of ethylene glycol acetate, di methyl formamide, toluene and xylene. Typically, the third additive is at least one dissociating salt consisting of a cation selected from the group consisting of lithium, zinc, calcium, magnesium, aluminum, copper, silver, iron, ammonium, quaternary ammonium and pyridinium and an anion selected from the group consisting of alkyl carboxylates, phosphates, dialkyl phosphates, alkyl phosphonate, sulfates, chlorides, bromides, iodides, nitrates and thiocyanates.

Typically, the amount of third additive present in the coagulating bath is in the range of about 0 to about 60 %.

In accordance with one of the embodiments of the present invention the coagulating agent is water.

In the next step, the resultant coagulated filaments are passed through a precipitating bath followed by washing, stretching, thermally treating to collapse voids (if any), heat-setting, crimping, finishing and drying to obtain high luster acrylic fibers.

Typically, the cold stretching is carried out at < 30°C and hot stretching is carried out at temperature >80°C.

The invention will now be described with respect to the accompanying non limiting examples which without limiting the scope and nature of the invention exemplify the steps of the process in accordance with this invention. Example 1 (first additive in the dope)

A spinning solution was prepared by dissolving acrylonitrile polymer (consisting of 91.1% acrylonitrile, 8.5% methyl aery late and 0.4% sodium methacryl sulfonate) in a solution containing ammonium thiocyanate, sodium thiocyanate and water in the relative ratio of 1.08: 37.5:50.4, to prepare a 12% spinning solution having a viscosity of 3000 centipoises at 30°C. This spinning solution was extruded at 50°C through 80 micron circular spinneret into an aqueous 14% (by weight) sodium thiocyanate solution at -3°C with a pull away ratio (winding speed/linear speed at spinneret) of 5. Then the filament was cold stretched 1.15 times at 0°C and 2.5 times at 30°C in a water bath and water washed at a temperature 50°C. Further the fiber was hot-wet stretched 4.5 times at 95°C to obtain a 3 denier fiber. Then the fiber was passed through void collapsing process, and sample was sent for mechanical property a testing and luster measurement as per the test protocol. These fibers showed luster enhancement of 42% but no significant change in the mechanical property.

Table No. 1

Example 2:

A spinning solution was prepared by dissolving acrylonitrile polymer (consisting of 91.1% acrylonitrile, 8.5% methyl acrylate and 0.4% sodium methacryl sulfonate) in a solution containing SDOD(Sodium dihydrogen orthophosphate dihydrate) , sodium thiocyanate and water in the relative ratio of 2.04:37.2:49.9, to prepare a 12% spinning solution having a viscosity of 3000 centipoises at 30°C. This spinning solution was extruded at 50°C through 80 micron circular spinneret into an aqueous 14% (by weight) sodium thiocyanate solution at -3°C with a pull away ratio (winding speed/linear speed at spinneret) of 5. Then the filament was cold stretched 1.15 times at 0°C and 2.5 times at 30°C in a water bath and water washed at a temperature 50°C. Further, the fiber was hot-wet stretched 4.5 times at temperature 95°C to obtain a 3 denier fiber. Then the fiber was passed through void collapsing process, and sample was sent for mechanical property a testing and luster measurement as per the test protocol. These fibers showed luster enhancement of 29% but no significant change in the mechanical property.

Table No. 2

Example 3

A spinning solution was prepared by dissolving acrylonitrile polymer (consisting of 91.1% acrylonitrile, 8.5% methyl acrylate and 0.4% sodium methacryl sulfonate) in a solution containing calcium thiocyanate, sodium thiocyanate and water in the relative ratio of 1.29:37.2:50.3, to prepare a 12% spinning solution having a viscosity of 3000 centipoises at 30°C. This spinning solution was extruded at 50°C through 80 micron circular spinneret into an aqueous 14% (by weight) sodium thiocyanate solution at -3°C with a pull away ratio (winding speed/linear speed at spinneret) of 5. Then the filament was cold stretched 1.15 times at 0°C and 2.5 times at 30°C in a water bath and water washed at a temperature 50°C. Further, the fiber was hot- wet stretched 4.5 times at temperature 95°C to obtain a 3 denier fiber. Then the fiber was passed through void collapsing process, and sample was sent for mechanical property a testing and luster measurement as per the test protocol. These fibers showed luster enhancement of 42% but no significant change in the mechanical property.

Table No. 3

Example 4

A spinning solution was prepared by dissolving acrylic polymer (consisting of 91.1% acrylonitrile, 8.5% methyl acrylate and 0.4% sodium methacryl sulfonate) in a solution containing ammonium thiocyanate, sodium thiocyanate and water in the relative ratio of 1.08:37.5:50.4, to prepare a 12% spinning solution having a viscosity of 3000 centipoises at 30°C. This spinning solution was extruded at 50°C through 80 micron circular spinneret into an aqueous 14% (by weight) sodium thiocyanate and 0.5% ammonium thiocyanate at -3°C with a pull away ratio (winding speed / linear speed) of 5. Then the coagulated filament was cold stretched 1.15 times at 0°C and 2.5 times at 30°C in pure water bath and water washed at a temperature 50°C. Further, the fiber was hot-wet stretched 4.5 times at temperature 95 °C to obtain a 3 denier fiber. Then the fiber was passed through void collapsing process, and sample was sent for mechanical property a testing and luster measurement as per the test protocol. These fibers luster enhancement of 40% but showed no significant change in the mechanical property. Table No. 4

Example 5

A spinning solution was prepared by dissolving acrylic polymer (consisting of 91.1% acrylonitrile, 8.5% methyl acrylate and 0.4% sodium methacryl sulfonate) in a solution containing SDOD, sodium thiocyanate and water in the relative ratio of 2.04:37.7:49.9, to prepare a 12% spinning solution having a viscosity of 3000 centipoises at 30°C. This spinning solution was extruded at 50°C through 80 micron circular spinneret into an aqueous 14% (by weight) sodium thiocyanate and 0.5% SDOD at -3°C with a pull away ratio (winding speed / linear speed) of 5. Then the coagulated filament was cold stretched 1.15 times at 0°C and 2.5 times at 30°C in pure water bath and water washed at a temperature 50°C. Further, the fiber was hot-wet stretched 4.5 times at temperature 95°C to obtain a 3 denier fiber. Then the fiber was passed through void collapsing process, and sample was sent for mechanical property a testing and luster measurement as per the test protocol. These fibers showed luster enhancement of 25% but no significant change in the mechanical property.

Table No. 5

Example 6

A spinning solution was prepared by dissolving acrylic polymer (consisting of 91.1% acrylonitrile, 8.5% methyl acrylate and 0.4% sodium methacryl sulfonate) in a solution containing ammonium thiocyanate, sodium thiocyanate and water in the relative ratio of 1.08:37.5:50.4, to prepare a 12% spinning solution having a viscosity of 3000 centipoises at 30°C. This spinning solution maintained at 50°C was extruded through a metallic spinneret having 90 circular orifices, each 80 micron in diameter, into an aqueous 70% (by volume) isopropyl alcohol (IPA) solution maintained at 10°C. (0 coagulating bath) and was held in the bath for 3 seconds. The freshly-formed filaments then passed through the standard sodium thiocyanate based spinning process. The coagulated spinning solution was further passed into an aqueous 14% sodium thiocyanate solution (1^st coagulating bath) maintained at -2.3°C with a pull away ratio of 4.7. Then the coagulated filament was cold stretched 1.14 times at 0°C and 2.5 times at 30°C in pure water bath and water washed at a temperature 50°C. Further, the fiber was passed through a water bath at temperature 95°C and hot wet stretched 4.5 times. The denier of these filaments after the total 13X stretch was 3. The filaments were of non circular configuration. Then the fiber was passed through void collapsing process, and sample was sent for mechanical property a testing and luster measurement as per the test protocol. These fibers showed luster enhancement of 200% but no significant change in the mechanical property.

Table No. 6

Example 7

A spinning solution was prepared by dissolving acrylic polymer (consisting of 91.1% acrylonitrile, 8.5% methyl acrylate and 0.4% sodium methacryl sulfonate) in a solution containing ammonium thiocyanate, sodium thiocyanate and water in the relative ratio of 1.08:37.5:50.4, to prepare a 12% spinning solution having a viscosity of 3000 centipoises at 30°C. This spinning solution maintained at 50°C was extruded through a metallic spinneret having 90 circular orifices, each 80 micron in diameter, into an aqueous 40% (by volume) CaC12 (calcium chloride) solution maintained at 10°C. (0^th coagulating bath) and was held in the bath for 3 seconds. The freshly-formed filaments then passed through the standard sodium thiocyanate based spinning process. The coagulated spinning solution was further passed into an aqueous 14% sodium thiocyanate solution (1^st coagulating bath) maintained at -2.3°C with a pull away ratio of 4.7. Then the coagulated filament was cold stretched 1.14 times at 0°C and 2.5 times at 30°C in pure water bath and water washed at a temperature 50°C. Further the fiber passed through a water bath at temperature 95°C and hot wet stretched 4.5 times. The denier of these filaments after the total 13X stretch was 3. The filaments were of non circular configuration. Then the fiber was passed through void collapsing process, and sample was sent for mechanical property a testing and luster measurement as per the test protocol.

Table No. 7

These fibers showed luster enhancement of 212% but no significant change in the mechanical property.

Example 8: Testing

Test Protocols:

1. Luster Measurement:

The fiber tuft board is prepared by aligning the fibers in parallel manually and fixed to a board to prepare a rectangular test piece of 6 cm X 4.5 cm dimension ensuring that all surface is completely and uniformly covered by the fibers aligned in the 6 cm direction.

The gloss value was measured on the fiber tuft board using a D-410B Mini gloss meter in accordance with the test method of JIS-Z-8741 at 60 degree incidence angle geometry. Here the incident ray will form an angle of 60 deg with the direction of arrangement of the fiber. A total of 5 fiber tuft board were measured for each fiber sample. The fibers were tested without any finish oil.

Luster enhancement of the fibers is calculated by below mentioned formula.

Luster of modified fiber— Luster of control fiber

Luster enhancement (%) = x 100

Luster of Control fiber

The results of luster measurements are provided herein below.

Table No. 8

Example 5 3.1 3.9 25

Example 6 3 9 200

Example 7 3.1 9.7 212

Form the above results it is clear that the fibers of the present invention showed an enhancement of luster in the range of about 10% to about 250%.

2. Mechanical property Measurement:

Mechanical Property of the fibers in terms of tenacity (gpd), elongation (%) was measured as per the ISO5079: 1995 standard procedure.

TECHNICAL ADVANCEMENT

The acrylic fibers manufactured in accordance with the present invention show significantly improved luster as compared to regular fiber without any significant loss in the mechanical and physical properties.

ECONOMICAL SIGNIFICANCE

The process in accordance with this invention is not only relatively inexpensive and high yielding but also provides an end product with luster at costs which are comparable with the costs of fiber prepared in accordance with the conventional processes.

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 and the claims unless there is a statement in the specification 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 invention. These and other changes in the preferred embodiment as well as other embodiments of the invention 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 invention and not as a limitation.

Claims

Claims:

1. A polymer dope composition for the manufacture of high luster acrylic fibers; said dope composition comprising 5-20% of acrylic polymer; 30- 50% of sodium thiocyanate; and 0.01-30% of first additive, the proportions of the ingredients being based on the total mass of the dope composition.

2. The polymer dope composition as claimed in claim 1, wherein the acrylic polymer comprises at least 50 % acrylonitrile monomer and at least one co-monomer selected from the group consisting of methacrylate, methyl methacrylate, vinyl acetate, methacrylic acid, acrylic acid, vinyl chloride, vinylidene chloride, vinyl sulfonic acid, itaconic acid, sodium styrene sulfonate, sodium methallyl sulfonate and sodium sulfophenyl methallyl ether.

3. The polymer dope composition as claimed in claim 1, wherein the first additive is at least one compound selected from the group of compounds consisting of sodium thiocyanate, acetic acid, sodium acetate, potassium acetate, sodium chromate, sodium nitrate, sodium sulphate, sodium hexa metaphoshate, sodium dihydrogen orthophosphate dihydrate, disodium hydrogen orthophosphate dihydrate, ammonium di hydrogen phosphate, sodium carbonate, sodium bicarbonate, ammonium thiocyanate, potassium thiocyanate, calcium thiocyanate, zinc chloride, calcium chloride and ammonium chloride and sodium chloride.

4. A high luster acrylic fiber/yarn with circular cross section prepared from the polymer dope composition as claimed in claim 1.

5. A process for the manufacture of high luster acrylic fibers; said process comprising the following steps:

- preparing a polymer dope comprising 5-20% of acrylic polymer, 30- 50% of sodium thiocyanate and 0.01-30% of first additive, the proportions of the ingredients being based on the total mass of the dope composition;

- extruding the polymer dope at a temperature of about 30 to about 70°C through a spinneret with circular spinning orifices into a coagulating bath comprising 0-20% of sodium thiocyanate, at least one additive selected from the group consisting of first additive, second additive, & third additive and a coagulating agent to obtain coagulated filaments; and

- passing the coagulated filaments through a precipitating bath followed by washing, stretching, thermally treating to collapse voids (if any), heat-setting and drying to obtain high luster acrylic fibers.

6. The process as claimed in claim 5, wherein the first additive is at least one compound selected from the group of compounds consisting of sodium thiocyanate, acetic acid, sodium acetate, potassium acetate, sodium chromate, sodium nitrate, sodium sulphate, sodium hexa metaphoshate, sodium dihydrogen orthophosphate dihydrate, disodium hydrogen orthophosphate dihydrate, ammonium di hydrogen phosphate, sodium carbonate, sodium bicarbonate, ammonium thiocyanate, potassium thiocyanate, calcium thiocyanate, zinc chloride, calcium chloride and ammonium chloride and sodium chloride.

7. The process as claimed in claim 5, wherein the second additive is at least one additive selected from the group consisting of methanol, ethanol, isopropyl alcohol, n-propanol, butanol, iso butanol, pentanol, t-butyl alcohols, di-ethylene glycol, ethylene glycols, tri-ethylene glycol, glycerol, benzyl alcohol, phenol, formic acid, acetic acid, oxalic acid, acetone, diethyl ether, tetra hydro furan, mono and poly substituted alkyl ether, di methyl esters , esters of polyhydric alcohols, ester of ethylene glycol acetate, di methyl formamide, toluene and xylene.

8. The process as claimed in claim 5, wherein the third additive is at least one dissociating salt consisting of a cation selected from the group consisting of lithium, zinc, calcium, magnesium, aluminum, copper, silver, iron, ammonium, quaternary ammonium and pyridinium and an anion selected from the group consisting of alkyl carboxylates, phosphates, dialkyl phosphates, alkyl phosphonate, sulfates, chlorides, bromides, iodides, nitrates and thiocyanates.

9. The process as claimed in claim 5, wherein the amount of first additive present in the coagulating bath is in the range of about 0 to about 25 %.

10. The process as claimed in claim 5, wherein the amount of second additive present in the coagulating bath is in the range of about 0 to about 100 %.

1 1. The process as claimed in claim 5, wherein the amount of third additive present in the coagulating bath is in the range of about 0 to about 60 %.

12. The process as claimed in claim 5, wherein the step of dope preparation is carried out at a temperature of about 30°C to about 80°C.

13. The process as claimed in claim 5, wherein the coagulating bath is maintained at a temperature of about -5°C to about 80°C.