Description:Field of Invention
The present disclosure relates to a modified regenerated cellulosic fiber having prolonged anti-odour and anti-microbial properties, and a process for preparing said modified regenerated cellulosic fiber.

Background
Certain metals, such as copper and silver, have been known for their anti-microbial activity since ancient times. In recent years, there has been a resurgence of interest in exploiting the therapeutic efficacy of such metals, particularly by using silver or copper ions, either alone or in the form of complexes, to disinfect or reduce the microbial load in liquids and solids. One use of metal-based antimicrobials is for textiles. Various methods are known in the art to introduce antimicrobial properties to a target fibre.

In one approach, the metal ions are loaded onto the surface of the fiber or fabric. In this approach, the surface of the fiber or fabric samples is treated with monomeric or polymeric carboxylic acid derivatives containing metal ions. Alternatively, metal ions are bound to the surface of fiber by dipping anionically modified fiber in a metal salt solution, followed by washing, to bind metal ions onto the fiber.

US9995002 discloses a surface treatment of cellulose fibers through chemical, sonochemical, and acoustic cavitation processes, followed by treatment with copper, zinc, and silver oxides for loading the metal oxides on the surface of the fiber.

US5458906 discloses the production of antibacterial fibers or fabrics by immersing the fibers or fabrics into a solution containing copper chloride or copper sulphate and, at the same time or subsequently, treating the fibers in a solution containing carbonate and/or borate anions.
US4637820 discloses the treatment of anionically modified cellulosic fiber by dipping the fibers into a cupric sulphate water solution to bind the copper ion for preparing antimicrobial cellulosic fiber. The cellulose fibers bind around 0.1 to 3.0% of copper with respect to fiber weight.

However, said approach suffers from disadvantages, such as - copper ions are more susceptible to leaching during post-processing and washing stages and difficulty in attaining a continuous or permanent biocidal effect. To address this shortcoming, in some known processes, copper ions (particularly copper salts) are dispersed with some binder, particularly carboxylate functional acrylate polymer, and surface treated on the fiber or fabric. However, the surface-treated fiber or fabric becomes yellow during post-processing steps such as scouring treatment (in the presence of H2O2) due to the coloration of the binder. Additionally, the known processes require offline treatment on fiber or fabric, and continuous processes are not known.

In another approach, metal oxides are added to the viscose dope (in cellulose xanthate solution in aqueous NaOH) or with the molten polymers (polyester, nylon) to make a master batch and then spun to form fibers.

US10667521B2 discloses antimicrobial rayon fibers prepared by incorporating a combination of at least two metal oxide powders comprising a mixed oxidation state and a single oxidation state metal oxide. Wherein the mixed oxidation state oxide constitutes from about 0.05% to about 15% of the total weight of the metal oxide combination. 3 wt.% of the tetra silver tetroxide and copper oxide powder mixture, with respect to cellulose, was added to the cellulose slurry for fiber making.

US8741197B2 discloses the addition of the copper oxide powder to the rayon viscose dope and extruding the dope through an acid bath. In this process, 0.25 to 10% powder of copper oxide particles with respect to the initial cellulose dry weight were added to the viscose dope.

Said approaches have the limitation of requiring a higher loading (at least 0.25 wt.% of the fiber) of metal oxide in the fiber to obtain the desired properties, as metal oxide tends to leach out easily during post-processing steps. The higher loading of the metal oxide fiber inherently makes the fiber difficult to dye in different shades, increases the cost of manufacturing and makes the product heavy, thereby limiting its applicability in textiles.

Also, due to the high viscosity of the viscose dope, the powder of metal oxide particles remains suspended in the dope. Thus, for even distribution, constant stirring is recommended, making the process tedious and increasing the cost of equipment.

Additionally, it is recognized in the literature that such products can be utilized only for restricted purposes because of the heavy influence of the compounds on polymer properties, or else they show poor durability and antibacterial performance because the metal ions are merely contained in or attached to a polymer and, accordingly, they easily leach out of the polymer while being used as they are on the surface.

US20220095626A1 disclosed the manufacturing of multi-layer copper-based zeolite fiber medical material. The cotton fiber is first treated with a zeolite precursor solution and heat treated to obtain cotton zeolite fiber. Next, this cotton zeolite fiber was treated with a copper sulphate salt solution for ion exchange between the copper ion of the salt solution and the ion exchangeable group in the zeolites to obtain copper-based zeolite fiber production.

This process, however, finds limited industrial applicability as it requires multiple steps to be carried out, which makes the process tedious and uneconomical. Also, the process results only in the surface coating of fiber, and the resultant surface coated fibers are less durable and are prone to leach out copper during the downstream processing of fibers as followed in textile industries.

In addition, the use of metal nanoparticles as antimicrobial agents in textiles has been attempted but has generally been unsuccessful due to disadvantages such as clumping and difficulty in obtaining a controlled, uniform dispersion and concentration of the metal nanoparticles in the final textile product.

Summary
A modified regenerated cellulosic fiber is disclosed. Said modified regenerated cellulosic fiber comprises a regenerated cellulosic fiber having 0.015-1.5 wt% of a modifier composition infused therein, wherein the modifier composition comprises a dispersion of 0.003- 0.2 wt% of metal oxide in 0.005-1.5 wt% of zeolite, based on weight of cellulose.

A continuous process for preparing aforesaid modified regenerated cellulosic fiber is also disclosed. Said process comprises:
a. preparing a modifier composition comprising a dispersion of a metal oxide in zeolite by subjecting a mixture of the metal oxide and zeolite in a weight ratio in the range of 1: 0.5 to 1:7 to milling such that the modifier composition is in the form of particles having a particle size in the range of 1-12 µm;
b. treating cellulose in a viscose dope with the modifier composition; and
c. spinning the viscose dope through spinneret into a regeneration bath to obtain modified regenerated cellulosic fiber having 0.015-1.5 wt% of the modifier composition infused therein, the modifier composition comprising a dispersion of 0.003-0.2 wt% of metal oxide in 0.005-1.5 wt% of zeolite, based on weight of cellulose.
Brief Description of Drawings
Figure 1 illustrates a scanning electron microscopy-energy-dispersive X-ray analysis (SEM-EDAX) of a modified regenerated cellulosic fiber in accordance with an embodiment of the present disclosure, at 22000x magnification with copper entrapped zeolite particles enclosed within the fiber.

Figure 2 shows copper retention in modified regenerated cellulosic fiber, in accordance with an embodiment of the present disclosure.

Figure 3 shows comparative colour shade between standard viscose staple fiber (VSF) and modified regenerated cellulosic fiber, in accordance with an embodiment of the present disclosure.

Detailed Description
Reference will now be made in detail to embodiments of the present disclosure. The terminology used in the description presented herein is not intended to be interpreted in any limited or restrictive manner, simply because it is being utilized in conjunction with a detailed description of certain specific embodiments of the invention. Furthermore, embodiments of the invention may include several features, no single one of which is solely responsible for its desirable attributes, or which is essential to practicing the inventions herein described.

It will be understood by those skilled in the art that the foregoing general description and the following detailed description are explanatory of the invention and are not intended to be restrictive thereof.

The terms “a,” “an,”, and “the” are used to refer to “one or more” (i.e., to at least one) of the grammatical object of the article.

Reference throughout this specification to “an aspect”, “another aspect” or similar language means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention.

The terms "comprises", "comprising", or any other variations thereof, are intended to cover a non-exclusive inclusion and are not intended to be construed as “consists of only”, such that a process or method that comprises a list of steps does not include only those steps but may include other steps not expressly listed or inherent to such process or method.

Likewise, the terms “having” and “including”, and their grammatical variants are intended to be non-limiting, such that recitations of said items in a list are not to the exclusion of other items that can be substituted or added to the listed items.

Also, any numerical range recited herein is intended to include all sub-ranges subsumed therein. For example, a range of "1 to 10" is intended to include any and all subranges between and including the recited minimum value of 1 and the recited maximum value of 10, that is, all subranges beginning with a minimum value equal to or greater than 1 and ending with a maximum value equal to or less than 10, and all subranges in between.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. Although any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the disclosure, the preferred methods, and materials are now described. All publications mentioned herein are incorporated herein by reference.

As used herein, the term “Zeolite” refers to three-dimensional crystalline solids of aluminium silicate, having a generic formula M2/nO • Al2O3 • ySiO2 • wH2O (n is the valency of the cation M, predominantly Na, and for Na is n=1; y can range from 2 to 222, and w is the number of water molecules typically between 4 and 40 that are microporous. The composition based on the metals present in the zeolite is typically: Na: 0 - 19.0%, Al: 0,3 - 19.0%, Si: 16.6 - 46.1% (general composition). There are different types of zeolites available, A-type zeolites, P-type zeolites, Y-type zeolites, X-type zeolites, etc. However, the present disclosure is not limited to any specific type of zeolite.

As used herein, the phrase “viscose dope” refers to a honey-like viscous solution of sodium cellulose xanthate in an aqueous solution of sodium hydroxide. The sodium cellulose xanthate was prepared by reacting alkali treated cellulose with carbon disulphide.

In an aspect, a modified regenerated cellulosic fiber is disclosed. Said modified regenerated cellulosic fiber comprises a regenerated cellulosic fiber having 0.015-1.5 wt% of a modifier composition infused therein, wherein the modifier composition comprises a dispersion of 0.003- 0.2 wt% of metal oxide in 0.005-1.5 wt% of zeolite, based on weight of cellulose.

In another aspect, a continuous process for preparing the modified regenerated cellulosic fiber is disclosed. Said process comprises:
a. preparing a modifier composition comprising a dispersion of a metal oxide in zeolite by subjecting a mixture of the metal oxide and zeolite in a weight ratio in the range of 1: 0.5 to 1:7 to milling such that the modifier composition is in the form of particles having a particle size in the range of 1-12 µm;
b. treating cellulose in a viscose dope with the modifier composition; and
c. spinning the viscose dope through spinneret into a regeneration bath to obtain modified regenerated cellulosic fiber having 0.015-1.5 wt% of the modifier composition infused therein, the modifier composition comprising a dispersion of 0.003-0.2 wt% of metal oxide in 0.005-1.5 wt% of zeolite, based on weight of cellulose.

In an embodiment, the metal oxide is selected from the group consisting of copper(I) oxide (Cu2O), copper(II) oxide (CuO), silver oxide (AgO), titanium oxide (TiO2) and zinc oxide (ZnO) and mixtures thereof. In some embodiments, the metal oxide is copper(I) oxide (Cu2O). In an embodiment, both copper(I) oxide and zeolite are used in powder form.

The present inventors found that when a modifier composition comprising a dispersion of 0.003–0.2 wt% of metal oxide in 0.005–1.5 wt% of zeolite is infused or embedded into a cellulosic fiber using the disclosed process, the metal oxide and zeolite act synergistically to impart improved anti-odour property (as shown using % reduction in ammonia, in Table 1) along with anti-microbial activity to the fiber while addressing the shortcomings of the known processes of obtaining fibers having anti-microbial and anti-odour properties. This happens firstly due to zeolite improving the retention of the metal ions in the fiber by trapping the metal ions (when generated in situ in the presence of moisture), and secondly, due to the modifier composition being water insoluble, which causes strong binding to the fiber core, making the fiber highly wash durable.

S. No. Loading of Cu2O(%) owc Loading of Zeolite(%) owc Reduction of ammonia (%)
1 0.00 0.015 33.0
2 0.003 0.00 58.0
3 0.003 0.005 59.0
4 0.003 0.010 83.0
5 0.003 0.015 100.0
owc = on weight of cellulose

Table 1: Synergistic effect of Cu2O and Zeolite on the fiber antiodour properties

The modifier composition comprises 0.003- 0.2 wt% of metal oxide and 0.005-1.5 wt% of zeolite, based on weight of cellulose. In some embodiments, the modifier composition comprises 0.01-0.10 wt% of metal oxide and 0.03-0.8-wt% of zeolite, based on weight of cellulose.

The modifier composition is prepared by subjecting the mixture of metal oxide and zeolite in a weight ratio in the range of 1: 0.5 to 1:7. In some embodiments, the mixture comprises metal oxide and zeolite in the weight ratio of 1:5.

In an embodiment, the modifier composition is prepared by subjecting the mixture of metal oxide and zeolite to milling in the presence of moisture. In an embodiment, the moisture is incorporated by adding water in the mixture of metal and zeolite. In addition to the reduction of the particle size of metal oxide and zeolite during the milling process, the said process also causes in situ generation of some metal ions, and entrapment of these metal ions in the porous structure of zeolite.

The milling is carried out in any known milling apparatus. In some embodiments, the milling is carried out in ball mill.

In an embodiment, the modifier composition comprises of particles having a particle size in the range of 1-12 µm. In some embodiments, the modifier composition comprises of particles having a particle size in the range of 2-8 µm.

In an embodiment, the mixture further comprises an additive selected from the group consisting of a dispersant and wetting agent.

In an embodiment, the dispersant is an anionic surfactant selected from the group consisting of phenol sulphonic acid condensation product, naphthalene sulphonic acid condensation product, alkyldiphenyloxide disulfonates, dioctyl sulfosuccinates and mixtures thereof. In some embodiments, the dispersant is naphthalene sulphonic acid condensation product (generically known as Tamol, manufactured by BASF).

In an embodiment, the wetting agent is a non-ionic surfactant selected from the group consisting of branched or unbranched secondary alcohol ethoxylates, ethylene oxide/propylene oxide (EO/PO) copolymers, octylphenol ethoxylates and mixtures thereof. In some embodiments, the wetting agent is a branched secondary alcohol ethoxylate, for example, Tergitol, manufactured by Dow Chemicals.

The invention will now be described with respect to the following examples, which do not limit the disclosed method in any way and only exemplify the claimed method. It will be apparent to those skilled in the art that various modifications and variations can be made to the method/process of the present disclosure without departing from the scope of the disclosure. Other embodiments will be apparent to those skilled in the art from consideration of the specification and practice of the method/process disclosed herein.

Examples

Example 1: Preparation of modifier composition comprising Copper(I) oxide and zeolite dispersion

Composition: Copper(I) oxide and zeolite were used in various weight ratios as listed in Table 2 to prepare the modifier composition.

S. No. Cu2O to Zeolite Ratio Particle size of the Cu2O -Zeolite dispersion (µm)
1 1: 0 3.6
2 1: 0.6 3.8
3 1: 2 4.5
4 1:5 6
5 1: 6.5 8
Table 2

Process: Copper(I) oxide (Cu2O) and zeolite at different weight ratios (as indicated in Table 2) were mixed together. The sulfonated anionic dispersant- Tamol and wetting agent- Tergitol were added to this solid mixture. Then water was added in the mixture, keeping the minimum solid content to 1 wt.%. The dispersion was ball milled to reduce the particle size to < 12 µm. After the ball milling, a stable dispersion of Cu2O and zeolite was obtained, which was used for infusion into cellulosic fiber.

Example 2: Preparation of cellulosic fiber infused with modifier composition

The modifier composition prepared in Example 1 (Cu2O to Zeolite ratio- 1:5) was used to prepare modified regenerated cellulosic fibers. Table 3 provides the various loading percentages used to prepare modified regenerated cellulosic fibers.

S. No. Target loading of Cu2O
(%) owc The actual loading* of Cu2O (%) (owc)
1 0.003 0.002
2 0.006 0.004
3 0.013 0.010
4 0.038 0.035
5 0.050 0.047
6 0.060 0.055
7 0.090 0.085
8 0.130 0.119
9 0.20 0.19
* Calculated based the Copper ion measured by ICP-AES
Table 3

Process: The copper(I) oxide-zeolite dispersion was stirred before adding to the viscose dope, (6-10% cellulose xanthate dissolved in 4-7% of aqueous NaOH). The dispersion was added to viscose dope for 0.003% loading of Cu2O and 0.015% loading of zeolite (Cu2O to Zeolite ratio -1:5), based on weight of cellulose. After addition of the modifier composition, the mixed viscose solution was mixed thoroughly in a high-speed stirrer for 2-3 minutes. The mixed viscose was pushed through the spinneret in a spin bath containing sulfuric acid, zinc sulfate and sodium sulfate to regenerate modified regenerated cellulosic fiber.

The regenerated cellulosic fiber thus obtained was cut into desired fiber length, followed by successive washing steps as per the normal viscose fiber process, such as, dilute sulfuric acid wash, hot water wash at 90°C, desulphurizing wash with dilute sodium hydroxide solution at 90°C, water wash at 60°C followed by bleaching with sodium hypochlorite at 50°C, water wash, dilute acetic acid rinse and final spin finish application. Post spin finish application, the fiber bed was dried at a temperature of 90-130°C.

Product Characterization:

Tests used:
1. Scouring stability: To assess scouring stability, 10 grams of fiber was treated at 1:10 MLR in a solution containing 2g/L NaOH, 1g/L soda ash and 3g/L 50% hydrogen peroxide with stabilizer at 90°C for 30 minutes, followed by washing in hot DM water thoroughly, neutralizing and drying at 105°C.
2. Dyeing behavior towards reactive dyes: Control fibers and modified regenerated cellulosic fibers were scoured and dyed with reactive dye. 3% dye on weight of fiber (owf) was used for red (Reactofix red HE3BI), yellow, and blue dyeing.

Dye bath comprised of 70g/L sodium sulfate, 18g/L soda ash for red, blue and yellow dye. Whereas, 80g/L sodium sulfate and 20g/L soda ash was used for black dye- 8% owf. Dyeing was done at 60°C for 45 minutes, followed by water wash, 2g/L non-phosphate ECE detergent at 60°C for 30 minutes, hot water wash, cold water wash, and then drying at 105°C. Similar dyeing protocols were used for dyeing the VSF for colour shade comparison between VSF and modified regenerated cellulosic fibers. Color strength and L a b values were measured by Minolta spectrophotometer and tabulated in Table 7.

3. Laundry washing: The final scoured, dyed fiber was washed in a tergotometer at 50°C using 1g/L ECE nonphosphate detergent for 15 minutes. The cycle was repeated 20 and 50 times. The final washed fiber was dried at 105°C.

4. Estimation of copper by Inductively coupled plasma atomic emission spectroscopy (ICP-AES): Briefly, the fiber was heated at 700°C for 6 hours, and then the fiber char was digested in 50% nitric acid followed by dilution with DM water, and the diluted solution was directly used for analysis.

5. SEM-EDAX analysis of fiber: Even though the copper(I) oxide-zeolite dispersion was present in the fiber in a very small amount, in the SEM the copper(I)oxide–Zeolite particles were detected on the fiber cross-section, and the elements were detected using EDX as depicted in the Image 1.

6. Estimation of antimicrobial activity: Antimicrobial activity of fiber samples was estimated for Gram positive bacterium S. aureus and Gram-negative bacterium K. pneumoniae, using AATCC 100-2019 method.
7. Estimation of anti-odour activity: Fiber samples were subjected to analysis as per the AATCC TM211-2021.

8. Estimation of antiviral activity: Fiber samples were subjected to analysis as per the MTCC 100 - 2012 test Method using MS2 Bacteriophage as surrogate virus.

9. Estimation of antifungal activity: Fiber samples were subjected to analysis as per the AATCC Test Method 30; lll 2017 test Method, using Aspergillus niger ATCC 627 as test culture.

Results:

Table 4 summarizes the retention of copper* in modified regenerated cellulosic fiber with respect to loading of 0.06 % Cu2O owc.

S. No. Cu2O to Zeolite Ratio Particle size of the Cu2O -Zeolite dispersion (µm) % Cu retention after scouring % Cu retention after Scouring and dyeing % Cu retention after Scouring dyeing and 20 washes
1 1: 0 3.6 68.9 58.6 32.7
2 1: 0.6 3.8 72.6 64.8 38.1
3 1: 2 4.5 73.4 66.4 40.6
4 1:5 6 78.0 72.0 52.0
5 1: 6.5 8 80.1 76.8 53.3
* Copper ion measured by ICP-AES
Table 4

Table 5 summarizes antibacterial and anti-odour properties obtained by various loading percentages of modifier composition (having Cu2O to Zeolite ratio-1:5) in the modified regenerated cellulosic fiber.

S. No. Cu2O(%) owc Zeolite (%) owc % Reduction of Microorganism Reduction of ammonia (%)#
Staph. aureus K. pneumoniae
1 0.003 0.015 99.88 99.23 100.0
2 0.050 0.250 99.99 99.99 100.0
3 0.20 1. 00 99.99 99.99 100.0
*0.06 % Cu2O owc
#Reduction of ammonia equivalent to antiodour efficiency
Table 5

Table 6 summarizes antibacterial and anti-odour properties obtained by various loading percentages of modifier composition (Cu2O to Zeolite ratio-1:5) in the modified regenerated cellulosic fiber, after multiples washes.

S. No. Sample Name % Reduction of Microorganism %Reduction of Ammonia#
S. aureus K. pneumoniae
1. 20 W- Cu2O-zeolite* loaded VSF 99.99 99.99 100
2. 50 W- Cu2O-zeolite* loaded VSF 99.99 99.99 100
3. 1W-Control VSF No reduction No
reduction No reduction
*0.06 % Cu2O owc, and Cu2O to Zeolite ratio- 1:5
# Reduction of ammonia equivalent to anti-odour efficiency
‘W’ signifies the number of laundry washed samples
Table 6

Table 7 summarizes antifungal and antiviral properties of the modified regenerated cellulosic fiber.

S. no. Test Name Sample Details Results
1 Antiviral Cu2O-zeolite loaded* VSF Percentage Reduction of Virus at 2 hours - 87.23 %
Percentage Reduction of Virus at 24 hours - 99.99 %
2 Antifungal Cu2O-zeolite loaded* VSF Resistance to Fungus (No growth)
*0.06 % Cu2O owc, and Cu2O to Zeolite ratio- 1:5
Table 7

Table 8 lists the reactive dyeing behaviour of the modified regenerated cellulosic fiber consisting of 0.06 % Cu2O owc, with Cu2O to Zeolite ratio of 1:5 and its comparison with that of standard VSF.

S. No. Sample Name Temp(°C) L*(D65) a*(D65) b*(D65) K/S St (max)
1 Control VSF 3% Avi Yell SE 60 73.63 24.59 68.32 100
2 Cu2O-zeolite VSF 3% Avi Yell SE 60 70.81 23.57 64.34 101
3 Control VSF 3% Blue ECR 60 39.13 -0.76 -34.14 100
4 Cu2O-zeolite VSF 3% Blue ECR 60 36.74 -0.33 -33.16 114
5 Control VSF 3% Avi Red SE 60 42.48 56.9 -4.91 100
6 Cu2O-zeolite VSF 3% Avi Red SE 60 39.65 51.7 -8.02 105
9 Control VSF 8% Reactobond Black PG 60 15.04 -0.63 -1.34 100
10 Cu2O-zeolite VSF 8% Reactobond Black PG 60 14.83 1.74 -0.66 91
Table 8

Table 9 provides comparative fiber properties of the standard VSF and modified regenerated cellulosic fiber of the present disclosure.

S. No. Tenacity (g/den) Elongation (%) FFD (Nm/Sec) FMD (Nm/Sec) Cohesion (cm)
Control VSF 2.82 18.9 4337 1151 13.5
Cu2O-zeolite* infused VSF 2.70 19.5 4451 1217 13.2
*0.06 % Cu2O owc and Cu2O to Zeolite ratio- 1:5
Table 9
Observations: It was also observed that the disclosed process does not adversely affect the mechanical properties of the modified regenerated cellulosic fiber as compared to the VSF. Specifically, it was observed that there was no loss of tenacity, negligible change in elongation, and no change in the water retention capability of the modified regenerated cellulosic fiber.

Industrial Applicability
The disclosure provides a modified regenerated cellulosic fibre that exhibits improved anti-microbial and anti-odour properties with minimal loading and higher metal retention. The disclosed fibre finds application in medical textiles, gauges, bandages, face masks, medical wipes, hospital linen, home textiles, socks, undergarments, etc. The modified regenerated cellulosic fiber has the potential to be applied for water filtration.

The disclosed process results in the in situ generation of metal ions that get entrapped in the porous structure of coal. Hence, the disclosed process results in enhanced retention of metal ions in the modified regenerated cellulosic fiber. This enhanced retention was observed even during the downstream processes in textile manufacturing such as scouring, reactive dyeing, and several laundry washes. It was also observed that the modified regenerated cellulosic fiber of the present disclosure exhibits wash durability while demonstrating no leaching of metal for up to 50–60 washes. Thus, the disclosed modified regenerated cellulosic fiber is able to exhibit prolonged biocidal activity.

Further, as there is no or negligible leaching of metal from modified regenerated cellulosic fiber, the loading requirement of the metal oxide is substantially reduced, as compared to conventional fibers, to attain the desired antibacterial and anti-odour properties. The lower loading also helps to reduce costs as well as attain different comparative dye shades for modified regenerated cellulosic fiber with respect to standard VSF.
Also, the disclosed process is continuous and can be scaled up industrially. Further, the disclosed process is economical, and existing equipment can be used to execute the process.

, Claims:1. A modified regenerated cellulosic fiber comprising:
a regenerated cellulosic fiber having 0.015-1.5 wt% of a modifier composition infused therein, wherein the modifier composition comprises a dispersion of 0.003- 0.2 wt% of metal oxide in 0.005-1.5 wt% of zeolite, based on weight of cellulose.
2. The modified regenerated cellulosic fiber as claimed in claim 1, wherein the modifier composition comprises the dispersion of 0.01-0.10 wt% of the metal oxide in 0.03-0.8 wt% of zeolite, based on the weight of cellulose.
3. The modified regenerated cellulosic fiber as claimed in claim 1, wherein the metal oxide is selected from the group consisting of copper(I) oxide (Cu2O), copper(II) oxide (CuO), silver oxide (AgO), titanium oxide (TiO2), zinc oxide (ZnO) and mixtures thereof.
4. The modified regenerated cellulosic fiber as claimed in claim 1, wherein the metal oxide is copper(I) oxide (Cu2O).
5. A continuous process for preparing a modified regenerated cellulosic fiber, said process comprising:
a. preparing a modifier composition comprising a dispersion of a metal oxide in zeolite by subjecting a mixture of the metal oxide and zeolite in a weight ratio in the range of 1: 0.5 to 1:7 to milling such that the modifier composition is in the form of particles having a particle size in the range of 1-12 µm;
b. treating cellulose in a viscose dope with the modifier composition; and
c. spinning the viscose dope through spinneret into a regeneration bath to obtain modified regenerated cellulosic fiber having 0.015-1.5 wt% of the modifier composition infused therein, the modifier composition comprising a dispersion of 0.003-0.2 wt% of metal oxide in 0.005-1.5 wt% of zeolite, based on weight of cellulose.
6. The process as claimed in claim 5, wherein the particles have the particle size in the range of 2- 8 µm.
7. The process as claimed in claim 5, the dispersion of metal oxide in zeolite is prepared by subjecting the mixture of metal oxide and zeolite to milling in a milling apparatus in the presence of moisture.
8. The process as claimed in claim 5, wherein the mixture further comprises an additive selected from the group consisting of a dispersant and a wetting agent.
9. The process as claimed in claim 8, wherein the dispersant is an anionic surfactant selected from the group consisting of phenol sulphonic acid condensation product, naphthalene sulphonic acid condensation product, alkyldiphenyloxide disulfonates, dioctyl sulfosuccinates and mixtures thereof.
10. The process as claimed in claim 8, wherein the wetting agent is a non-ionic surfactant selected from the group consisting of branched or unbranched secondary alcohol ethoxylates, ethylene oxide/propylene oxide (EO/PO) copolymers, octylphenol ethoxylates and mixtures thereof.