DESC:Field of Invention

The present disclosure relates to a continuous process for production of anionic regenerated cellulose fibers for improving the uptake of cationic dyes thereby.

Background

Regenerated cellulosic fibers, such as viscose, are commonly unable to uptake cationic or basic dyes which possess cationic groups. It is desirable to use cationic dyes considering that they have numerous advantages over reactive dyes. Dyeing of cellulosic fibers with reactive dyes consume large amounts of dye and salt, leading to large amount of effluents including excess dye and salt. On the other hand, the dyeing process with cationic or basic dyes requires much lower dye as compared to reactive dyes and is salt and soda free. Further, dyeing process with cationic or basic dyes enables achieving up to hundred percent dye bath exhaustion. This not only reduces environmental pollution but also reduces the cost of dyeing. Additionally, cationic dyes provide brighter shades with high tinctorial value and color depth compared to reactive dyes on cellulosic fibers with the same concentration of dyes.

Researchers have attempted to enable uptake of cationic or basic dyes by regenerated cellulosic fibers by introducing anionic functionality thereon. Japanese Patent No. 158263/1996 discloses modifying cellulose fibers with an insoluble polymer obtained by cross-linking a dihydroxy-diphenylsulfone-sulfonate condensate with epoxy compounds having at least two epoxy groups in the molecule. US4722739A discloses production of a crosslinked cellulosic fabric. Said fabric is composed of a sufficient amount of N-methylol crosslinking agent and amino acid to give the fabric smooth drying properties and affinity for both cationic and anionic dyestuffs, especially basic and direct dye classes.

S. Nag, N. Waghmare, V. Juikar, “Fabrication of Poly (Methacrylic Acid) functionalized cellulosic Fibers with Cationic Dye Uptake Capacity for Textile Applications” IRJET, Vol. 5, Issue 12, Pg. 161-167, 2018 discloses inclusion of anionic polymers like poly (methacrylic acid) in viscose by in-situ polymerization and grafting of methacrylic acid onto viscose fiber.

Brief Description of Drawings

Figure 1 illustrates the mechanism of incorporating anionic functionality in cellulose fibers, in accordance with an embodiment of the present invention.

Detailed Description

For the purpose of promoting an understanding of the principles of the disclosure, reference will now be made to embodiments and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the disclosure is thereby intended, such alterations and further modifications in the disclosed composition and method, and such further applications of the principles of the disclosure therein being contemplated as would normally occur to one skilled in the art to which the disclosure relates.

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

Reference throughout this specification to “one embodiment” “an embodiment” 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 disclosure. Thus, appearances of the phrase “in one embodiment”, “in an embodiment” and similar language throughout this specification may, but do not necessarily, all refer to the same embodiment.
In its broadest scope, the present disclosure relates to a continuous process for improving the uptake of cationic dyes by regenerated cellulosic fibers. Specifically, the present disclosure relates to a process for improving the uptake of cationic dyes by regenerated cellulosic fibers by preparing anionic regenerated cellulose fibers. Said process comprises:

(a) treating cellulose in a viscose dope with dihydroxy diaryl sulfone sulfonate condensate in an amount of 2-20 % by weight of cellulose, said treatment being carried by introducing the dihydroxy diaryl sulfone sulfonate condensate in the viscose dope immediately before spinning the viscose dope to form regenerated cellulose fibers; and
(b) treating the regenerated cellulose fibers obtained in step (a) with a modified N-methylol derivative in an amount of 0.5-5 % by weight of cellulose followed by curing at a temperature between 110-1400C.

An anionic regenerated cellulose fiber is also disclosed. Said anionic regenerated cellulose fiber comprises regenerated cellulose fibers crosslinked with at least one polymeric unit dihydroxydiaryl sulfone sulfonate condensate through a modified N-methylol derivative.

Herein, the anionic functionalization of the regenerated cellulose fibers with dihydroxy diaryl sulfone sulfonate condensate introduces sulfonate moiety in the regenerated cellulose fibers. Preferably said dihydroxy diaryl sulfone sulfonate (DHDPS) condensate is dihydroxy diphenyl sulfone sulfonate condensate. In accordance with an embodiment, in said dihydroxy diphenyl sulfone sulfonate condensate, one or both the phenyl groups of the diphenyl compound are substituted by one or more methyl or other alkyl groups. Said dihydroxy diphenyl sulfone sulfonate condensate was obtained from commercial sources (for instance, Agritan DD from AGROSYN IMPEX)

In accordance with an aspect, dihydroxy diaryl sulfone sulfonate condensate is added to the viscose dope in an amount of 2-20 % of the weight of cellulose, and preferably between 10-12% of the weight of cellulose. In accordance with an embodiment, an aqueous solution of dihydroxy diphenyl sulfone sulfonate condensate having a concentration of about 25% is added.

The modified N-Methylol derivatives acts as a curing agent/ crosslinker between cellulosic fibers and dihydroxy diaryl sulfone sulfonate condensate.

The modified N-methylol derivative is selected from a group consisting of dimethylol dihydroxy ethylene urea (DMDHEU) and dimethylol propylcarbamate. In accordance with a related embodiment, the modified N-methylol derivative is used in low concentrations ranging between 0.5 – 5.0 grams per litre (gpL), and preferably between 0.1. – 1.0 gpL. In accordance with an exemplary embodiment, the modified N-methylol derivative is used in concentrations ranging between 0.2 – 0.5 gpL.

In accordance with an embodiment, said treatment of the anionically functionalized regenerated cellulose fibers is carried out in the presence of a catalyst selected from the group consisting of hydrates of magnesium chloride, Zinc nitrate and PTSA (para-toluenesulfonic acid) and mixtures thereof. Said catalyst is added in an amount ranging between 002-0.1% by weight of cellulose.

Curing of the regenerated cellulose fibers with the modified N-methylol derivative is carried out at a temperature between 110-1400C, and preferably between 110-1200C.

In accordance with an embodiment, the regenerated cellulose fibers obtained in step (b) is optionally treated with an aqueous solution of tannic acid. In accordance with an alternate embodiment, the aqueous solution of tannic acid is added with dihydroxy diaryl sulfone sulfonate condensate to the viscose dope. The treatment of regenerated cellulose fibers with tannic acid increases the anionicity. Also, curing of the regenerate cellulose fibers in the presence of tannic acid results in improvement of wash fastness properties.

In accordance with an embodiment, tannic acid is used in an amount of 0.05-1.0% by weight of the cellulose. In accordance with a preferred embodiment, tannic acid is used in an amount of 0.1 – 0.5% of the weight of the cellulose.

It has been found by the present inventors that anionic functionalization of regenerated cellulosic fibers significantly improves the cationic dye uptake thereof.

In order that this invention may be better understood, the following examples are set forth. These examples are for the purpose of illustration only and the exact compositions, methods of preparation and embodiments shown are not limiting of the invention, and any obvious modifications will be apparent to one skilled in the art.

Specific Embodiments Are Described Below

A continuous process for improving the uptake of cationic dyes by regenerated cellulosic fibers, the process comprising:

(a) treating cellulose in a viscose dope with dihydroxy diaryl sulfone sulfonate condensate in an amount of 2-20 % by weight of cellulose, said treatment being carried by introducing the dihydroxy diaryl sulfone sulfonate condensate in the viscose dope immediately before spinning the viscose dope to form regenerated cellulose fibers; and
(b) treating the regenerated cellulose fibers obtained in step (a) with a modified N-methylol derivative in an amount of 0.5-5 % by weight of cellulose followed by curing at a temperature between 110-1400C,
to obtain anionic regenerated cellulose fibers.
Such process, wherein the dihydroxy diaryl sulfone sulfonate condensate is added to the viscose dope in an amount of 10-12 % of the weight of cellulose.

Such process, wherein the dihydroxy diaryl sulfone sulfonate condensate is dihydroxy diphenyl sulfone sulfonate condensate.

Such process, wherein an aqueous solution of dihydroxy diaryl sulfone sulfonate condensate having a concentration of about 25% is added.

Such process, wherein the modified N-methylol derivative is selected from a group consisting of dimethylol dihydroxy ethylene urea and dimethylol propylcarbamate.

Such process, wherein the modified N-methylol derivative is used in a concentration ranging between 0.1. – 1.0 grams per litre (gpL).

Such process, wherein the treatment of regenerated cellulose fibers with a modified N-methylol derivative in step (b) is carried out in the presence of a catalyst selected from the group consisting of hydrates of magnesium chloride, Zinc nitrate, para-toluenesulfonic acid (PTSA) and mixtures thereof.

Such process, wherein said catalyst is added in an amount ranging between 002-0.1% by weight of cellulose.

Such process, wherein in step (b) the regenerated cellulose fibers are subjected to an additional treatment with an aqueous solution of tannic acid in an amount of 0.05-1.0% by weight of the cellulose.

Such process, wherein the regenerated cellulose fibers are treated with the aqueous solution of tannic acid in an amount of 0.1-0.5% by weight of the cellulose.

Such process, wherein the aqueous solution of tannic acid is added with the dihydroxy diaryl sulfone sulfonate condensate to the viscose dope.
An anionic regenerated cellulose fiber comprising regenerated cellulose fibers crosslinked with at least one polymeric unit dihydroxy diaryl sulfone sulfonate condensate through a modified N-methylol derivative.

Said fiber, wherein the dihydroxy diaryl sulfone sulfonate condensate is dihydroxy diphenyl sulfone sulfonate.

Said fiber, wherein the modified N-methylol derivative is selected from a group consisting of dimethylol dihydroxy ethylene urea and dimethylol propylcarbamate.

Examples:

Comparative Example 1: Dyeing of Acrylic fibers with Basic Dyes-coracryl variants CGNX blue, C4G red, CGL yellow and C8GL yellow (From Colourtex Industries Pvt.Ltd.)

Acrylic fibers were subjected to basic dyeing at 1:30 fiber to liquor ratio with a progressive rise of temperature from 25 to 105? at a rate of 1.4?/minute and then holding at 105? for 30-45 minutes followed by cooling up to 40? and further washing with 1 gpL phosphate free soap. The dye concentration was maintained as 1% on fiber weight basis and pH of dye bath is maintained in the range of 4.0-4.5 with acetic acid.

Dye bath exhaustion was found to be about 99-100% for all dyes.

Comparative Example 2: Dyeing of Regenerated cellulose fibers (without anionic functionalization) with Basic Dyes-coracryl variants CGNX blue, C4G red, CGL yellow and C8GL yellow (From Colourtex Industries Pvt.Ltd.)
Regenerated cellulose fibers were subjected to basic dyeing at 1:30 fiber to liquor ratio with a progressive rise of temperature from 25 to 65? at a rate of 1.4?/minute and then holding at 65? for 30-45minutes followed by cooling up to 40? and further washing with 1 gpL phosphate free soap. The dye concentration was maintained as 1% on fiber weight basis and pH of dye bath is maintained in the range of 4.0-4.5 with acetic acid.

It was observed that dye pick up could not take place.

Characterization methods

Dye bath exhaustion (DBE): DBE was measured by UV-Visible spectroscopic method. Calibration curves of absorbance vs concentration was made for each dyes which is a straight line passing through origin following BEER LAMBERT law. Using the calibration curve for each dyes, the residual dye concentration in dye bath post dyeing operation was measured and converted into dye bath exhaustion in percentage of initial dye concentration.

Color strength of dyed fibers: Color strength was measured by spectrophotometric method.

Light and wash fastness of dyed fibers: Light and wash fastness of dyed fibers were measured by IS:2454:1985 and ISO:105 C10-2006 (A1,B2) respectively.

Example 1: Aqueous solution of dihydroxy diphenyl sulfone sulfonate condensate (DHDPS Condensate) was added to a highly alkaline viscose dope leading to inclusion of 5-20% DHDPS Condensate active molecule on cellulose basis prior to dry jet wet spinning into acidic coagulation bath. The regenerated cellulose fiber thus obtained is subjected to washing steps and dried post application of soft finish. The dried fibers thus obtained is subjected to basic dyeing with CGNX blue dye at 1:30 fiber to liquor ratio with a progressive rise of temperature from 25 to 65? at a rate of 1.4?/minute and then holding at 65? for 30-45minutes followed by cooling up to 40? and further washing with 1 gpL phosphate free soap. The dye concentration was maintained as 1% on fiber weight basis and pH of dye bath is maintained in the range of 4.0-4.5 with acetic acid.

Dye bath exhaustion was found to be about 92-97%. The dye bath exhaustion of this fiber for varying amount of dihydroxy diphenyl sulfone sulfonate condensate are listed in Table 1 below.

Amount of DHDPS Condensate on fiber weight basis (%) Dye bath exhaustion (DBE) (%)
5 92.5
10 96.5
15 97.0
20 97.2

Table 1: Dye bath exhaustion of fibers

Example 2: The regenerated cellulose fiber is subjected to treatment with aqueous solution of 0.2-0.5% Tannic acid and 0.2-0.5% DMDHEU with magnesium chloride hexahydrate together for 2 minutes each in a continuous process prior to washing steps and dried post application of soft finish. The dried fibers thus obtained is subjected to basic dyeing with CGNX blue dye at 1:30 fiber to liquor ratio with a progressive rise of temperature from 25 to 65? at a rate of 1.4?/minute and then holding at 65? for 30-45 minutes followed by cooling upto 40? and further washing with 1 gpL phosphate free soap. The dye concentration was maintained as 1% on fiber weight basis and pH of dye bath is maintained in the range of 4.0-4.5 with acetic acid.

The dye bath exhaustion of this fiber for varying amount of Tannic acid, DMDHEU and magnesium chloride hexahydrate are listed in Table 2.
Amount of TA on fiber (%) Amount of DMDHEU on fiber (%) Amount of magnesium chloride hexahydrate on fiber (%) Dye bath exhaustion (1%)
0.2 0.2 0.02 92.9
0.5 0.5 0.05 94.8

Table 2: Dye bath exhaustion of fibers

Example 3: Example 1 was repeated except that the fibers were treated with 5gpL of Tannic Acid along with soft finish. Dyeing conditions were kept same as example 1. The dye bath exhaustion of this fiber for different basic dyes are listed in Table 3.

Example 4: Example 1 was repeated except that the fibers were additionally treated with DMDHEU and 0.5gpL magnesium chloride hexahydrate along with 5gpL Tannic Acid and soft finish. Dyeing conditions were kept same as Example 1.

Dye bath exhaustion was found to be about 99% when dyed without scouring and comes down to 98-99% when dyed post scouring. Wash fastness properties were found to be much improved compared to example 1. The dye bath exhaustion of this fiber for different basic dyes are listed in Table 3. The color strength of dyed fibers and wash, light fastness of dyed fibers are shown in Table 4 and 5 respectively as compared to Example 1.

Example 5: 25% DHDPS Condensate aqueous solution was added into highly alkaline viscose dope leading to inclusion of 10-12% DHDPS Condensate active molecule on cellulose basis prior to dry jet wet spinning into acidic coagulation bath. The regenerated fiber thus obtained is subjected to treatment with aqueous solution of 0.2-0.5% Tannic acid and 0.1-0.5% antimony potassium tartrate in separate baths for 2 minutes each in a continuous process prior to washing steps and dried post application of soft finish. Dyeing conditions were kept same as example 1. The dye concentration was maintained as 1% on fiber basis and pH of dye bath is maintained in the range of 4.0-4.5 with acetic acid.

Dye bath exhaustion was found to be about 98-99%. The dye bath exhaustion of this fiber for different selected basic dyes are listed in Table 3.

Example 6: Example 5 was repeated except DHDPS Condensate was replaced with suspension of DHDPS Condensate with average particle size of 15µm in water.

Example 7: 25% DHDPS Condensate aqueous solution and Tannic acid aqueous solution and is added into highly alkaline viscose dope leading to inclusion of 10% DHDPS Condensate active molecule and 2-5% Tannic acid on cellulose basis prior to dry jet wet spinning into acidic coagulation bath. Regenerated fiber thus obtained is subjected to treatment with aqueous solution of antimony potassium tartrate prior to washing steps and dried post application of soft finish. Dyeing conditions were kept same as example 1. The dye concentration was maintained as 1% on fiber weight basis and pH of dye bath is maintained in the range of 4.0-4.5 with acetic acid.

Dye bath exhaustion was found to be about 96-97%. The dye bath exhaustion of this fiber for different selected basic dyes are listed in Table 3.

Example 8: 25% DHDPS Condensate aqueous solution and Tannic acid aqueous solution is added into highly alkaline viscose dope leading to inclusion of 10% DHDPS Condensate active molecule and 2-5% Tannic acid on cellulose basis prior to dry jet wet spinning into acidic coagulation bath. Fibers were additionally treated with 0.5gpL magnesium chloride hexahydrate along with 5gpL DMDHEU and soft finish. Dyeing conditions were kept same as example 1. The dye concentration was maintained as 1% on fiber weight basis and pH of dye bath is maintained in the range of 4.0-4.5 with acetic acid.

Dye bath exhaustion was found to be about 97-98%. The dye bath exhaustion of this fiber for different basic dyes are listed in Table 3.

Example Viscose Dope Additive Other Modifier post regeneration Cationic Dye DBE%
1
10-12% DHDPS Condensate - Blue CGNX 96.4
- Red C4G 94.0
2 -- 0.5%TA+0.5% DMDHEU + 0.05% magnesium chloride hexahydrate Blue CGNX 95.1
Red C4G 93.5
3 10-12% DHDPS Condensate 0.5%TA Blue CGNX 98.2
Red C4G 97.1
4 10-12% DHDPS Condensate 0.5%TA + 0.5% DMDHEU + 0.05% magnesium chloride hexahydrate Blue CGNX 99.6
Red C4G 99.8
5 10-12% DHDPS Condensate 0.2-0.5% TA +0.1-0.25% antimony potassium tartrate Blue CGNX 99.0
Red C4G 98.7
6 10-12% Decitan 0.5%TA + 0.5% DMDHEU + 0.05% magnesium chloride hexahydrate Blue CGNX 97.8
Red C4G 97.3
7 2-5% TA and 10% DHDPS Condensate 1-2.5% antimony potassium tartrate Blue CGNX 97.5
Red C4G 96.9
8 2-5% TA and 10% DHDPS Condensate 0.5% DMDHEU + 0.05% magnesium chloride hexahydrate Blue CGNX 98.1
Red C4G 97.2

Table 3: Dyeing performance of

Dyes L*(D65) a*(D65) b*(D65) K/S St.(Max)
C4G RED 1% Acrylic fiber 40.93 60.95 17.33 100.0
Standard VSF 56.28 23.4 -11.1 4.5
Anionic VSF (Ex 1) 38.48 64.42 -12.85 74.51
Anionic VSF (Ex 4) 36.04 61.41 -13.02 77.91
CGNX BLUE 1% Acrylic fiber 25.78 10.54 -44.06 100.0
Standard VSF 60.14 -5.87 -21.32 5.05
Anionic VSF (Ex 1) 37.22 -2.47 -41.83 47.63
Anionic VSF (Ex 4) 35.32 -0.46 -44.21 60.15
CGL YELLOW 1% Acrylic fiber 69.33 31.45 88.82 100.0
Standard VSF 86.53 5.24 7.1 0.51
Anionic VSF (Ex 1) 70.56 33.44 75.63 46.58
Anionic VSF (Ex 4) 68.87 33.81 73.01 46.46
C8GL YELLOW 1% Acrylic fiber 79.1 -0.19 95.00 100.0
Standard VSF 81.9 -3.87 31.7 2.9
Anionic VSF (Ex 1) 80.17 4.95 91.73 52.99
Anionic VSF (Ex 4) 82.38 6.02 95.16 57.57

Table 4: Color strength

Example 1 Example 4
Fastness to Light Exposure Under Xenon Arc Lamp (Blue Wool Rating) IS:2454:1985 2-3 3-4
Colour Fastness to Washing for 30 minutes (ISO:105 C10-2006 (A1,B2)
40°C 50°C 40°C 50°C
Change in Colour 3 1-2 4-5 3-4
Staining on Adjacent Multi-fiber Fabric (ISO:105 C10-2006 (A1,B2)
Wool 4 4 4-5 4-5
Acrylic 4 4 4-5 4-5
polyester 4 4 4-5 4-5
nylon 4-5 4 4-5 4-5
Cotton 4-5 4 4-5 4-5
Diacetate 4 4 4-5 4-5

Table 5: Light and wash fastness

Industrial Applicability

The disclosed process is a continuous process. It is cost effective and environmentally sustainable. Said process imparts affinity to regenerated cellulose fibers for basic dyes and provides a dyeing process having upto100% dye bath exhaustion, similar to acrylic fibers. Said regenerated cellulose fibers are capable of cationic/basic dyeing in a salt and soda free environment unlike reactive dyeing process of standard cellulosic fibers which requires 14-30 gpL soda and 45-80 gpL salt. Thus, the present process has significantly low carbon footprint and is environment friendly.

The dyeing process requires upto 50% less dyes and does not require salt and soda. It also provides brighter shades with high tinctorial value and color depth when compared to conventional reactive dyeing on cellulosic fibers with the same concentration of dyes. Hence, the present process provides an economically viable dyeing process.

Said regenerated cellulose fibers obtained using present process can be extensively used in single bath dyeing process with other cationic dyeable fibers such as polyesters, wools or acrylics. The single bath dyeing for blends comprising of acrylics, wool or cationic dyeable polyesters can be carried out at fiber, yarn or fabrics stage (for example: Melange and pattern dyeing). This provides significant savings in terms of energy, cost and cumbersome process as compared to regular multi-step dyeing comprising of blends. Additionally, single bath dyeable blends of wool or acrylic fibers with regenerated cellulose fibers of present process improves the skin feel in terms of softness due to cellulose content, in rough and scaly wool or acrylics.

Said regenerated cellulose fibers are dyeable with cationic dyes. The concentration of each dye may vary depending on the color desired.
,CLAIMS:1. A continuous process for improving the uptake of cationic dyes by regenerated cellulosic fibers, the process comprising:
(a) treating cellulose in a viscose dope with dihydroxy diaryl sulfone sulfonate condensate in an amount of 2-20 % by weight of cellulose, said treatment being carried by introducing the dihydroxy diaryl sulfone sulfonate condensate in the viscose dope immediately before spinning the viscose dope to form regenerated cellulose fibers; and
(b) treating the regenerated cellulose fibers obtained in step (a) with a modified N-methylol derivative in an amount of 0.5-5 % by weight of cellulose followed by curing at a temperature between 110-1400C,
to obtain anionic regenerated cellulose fibers.

2. The process as claimed in claim 1, wherein the dihydroxy diaryl sulfone sulfonate condensate is added to the viscose dope in an amount of 10-12 % of the weight of cellulose.

3. The process as claimed in claim 1 or 2, wherein the dihydroxy diaryl sulfone sulfonate condensate is dihydroxy diphenyl sulfone sulfonate condensate.

4. The process as claimed in claim 1, wherein an aqueous solution of dihydroxy diaryl sulfone sulfonate condensate having a concentration of about 25% is added.

5. The process as claimed in claim 1, wherein the modified N-methylol derivative is selected from a group consisting of dimethylol dihydroxy ethylene urea and dimethylol propylcarbamate.

6. The process as claimed in claim 1 or 5, wherein the modified N-methylol derivative is used in a concentration ranging between 0.1. – 1.0 grams per litre (gpL).

7. The process as claimed in claim 1, wherein the treatment of regenerated cellulose fibers with a modified N-methylol derivative in step (b) is carried out in the presence of a catalyst selected from the group consisting of hydrates of magnesium chloride, Zinc nitrate, para-toluenesulfonic acid (PTSA) and mixtures thereof.

8. The process as claimed in claim 7, wherein said catalyst is added in an amount ranging between 002-0.1% by weight of cellulose.

9. The process as claimed in claim 1, wherein in step (b) the regenerated cellulose fibers are subjected to an additional treatment with an aqueous solution of tannic acid in an amount of 0.05-1.0% by weight of the cellulose.

10. The process as claimed in claim 9, wherein the regenerated cellulose fibers are treated with the aqueous solution of tannic acid in an amount of 0.1-0.5% by weight of the cellulose.

11. The process as claimed in claim 1, wherein the aqueous solution of tannic acid is added with the dihydroxy diaryl sulfone sulfonate condensate to the viscose dope.

12. An anionic regenerated cellulose fiber comprising:
regenerated cellulose fibers crosslinked with at least one polymeric unit of dihydroxy diaryl sulfone sulfonate condensate through a modified N-methylol derivative.

13. The anionic regenerated cellulose fiber as claimed in claim 12, wherein the dihydroxy diaryl sulfone sulfonate condensate is dihydroxy diphenyl sulfone sulfonate.

14. The anionic regenerated cellulose fiber as claimed in claim 12, wherein the modified N-methylol derivative is selected from a group consisting of dimethylol dihydroxy ethylene urea and dimethylol propylcarbamate.