US3109798A

US3109798A - Treatment of cotton with radiation polymerized acrylonitrile

Info

Publication number: US3109798A
Application number: US21067A
Authority: US
Inventors: Jr Jett C Arthur; Robert J Demint
Original assignee: Individual
Current assignee: Individual
Priority date: 1960-04-08
Filing date: 1960-04-08
Publication date: 1963-11-05
Anticipated expiration: 1980-11-05

Description

3,109,703 TREATR ENT (BF COTTQN WITH RADIATION PQLYMERIZED ACRYLONITRILE Jett C. Arthur, in, Metairie, and Robert J. Demint, New Orleans, La, assignors to the United States of America as represented by the Secretary of Agriculture No Drawing. Filed Apr. 8, 1960, Ser. No. 21,067 2 Claims. (Cl. 204-158) (Granted under Title 35, U.S. Code (1952), sec. 266) A non-exclusive, irrevocable, royalty-free license in the invention herein described, throughout the World for all purposes of the United States Government, with the power to grant sublicenses for such purposes, is hereby granted to the Government of the United States of America.

This invention relates to the treatment of cotton with acrylonitrile monomer and then to the radiation polymerization of the acrylonitrile monomer and has as its objects modifications of the physical properties of cotton, particularly decreases in stillness, increases in elongationat-break, and other changes in related properties of the cotton fibers to impart new and desirable properties for use in finished cotton products.

In the production of cotton products in recent years, chemical modifications of the physical properties of cotton fibers to give them new and desirable properties have become major factors in cotton utilization. Cotton cellulose has very low chemical reactivity; and in effecting chemical modifications of cotton, usually concentrated bases, high temperatures, high pressures, or catalysts must be used. In many modifications there is probably little or no chemical reaction, but the modifying chemicals simply coat the fiber. Generally, many of these chemical treatments of the cotton fibers greatly reduce their tensile properties and are not as durable as the cotton. Much of the beneficial eifects of the chemical treatments may be lost during subsequent using, washing, and cleaning of the cotton products.

Our present invention is an improvement over these processes in that acrylonitrile monomer is applied to the cotton fibers and the small molecules of the monomer penetrate through the outer wall and around the lumen of the fiber. Then when the treated cotton is irradiated with high energy ionizing radiations, the monomer is polymerized to form high molecular Weight polymer Within the outer Wall and the lumen. The radiation polymerized acrylonitrile can not be extracted out of the fiber with N,N-dimethyl formamide, a commonly used solvent for polyacrylonitrile. As shown by electron micrographs, the radiation polymerized acrylonitrile is inside of the cotton fiber as contrasted with the usual treatment which is outside of the fiber. Consequently, the treatment with radiation polymerized acrylonitrile is as durable as the cotton.

We have discovered unexpectedly that this type of treatment with radiation polymerized acrylonitrile significantly decreases the stiffness of the cotton fibers and significantly increases the elongation-at-break of the cotton fibers while other important properties of the cotton are not significantly changed. For example, treated, irradiated cotton fiber containing about 24 percent radiation polymerized acrylonitrile has an average stiffness of 44 grams per tex as compared with raw, untreated fiber of 128 grams per tex and has an elongation-at-break of 23.4 percent as compared with raw, untreated fiber of 13.7 percent. In chemically modified cotton products requiring improved softness and drape, such as cotton fiber blankets and other cotton products, these changes in properties of cotton fibers due to treatment with radiation polymerized acrylonitrile have particular and important values.

A United States Patent 3,109,793 Patented Nov. 5, 1963 In general, the process of this invention is: carried out at room temperature by subjecting cotton fiber immersed in an aqueous solution of acrylonitrile to high energy radiation. The radiation can be from any convenient source, provided the source is capable of supplying the requisite dosage which is, for this reaction, at least about 800,000 roentgens.

The solubility of acrylonitrile in water is limited. It is desirable, therefore, for the purpose of insuring an adequate concentration of aqueous acrylonitrile, to utilize the recognized hydrotropic effect of certain inorganic salts. Zinc chloride, magnesium chloride, the nitrate salts of these elements, as well as certain other inorganic salts, when dissolved in water, markedly enhance the solubility of acrylonitrile in the resultant aqueous salt solution.

Subsequent to the irradiation step, which treatment polymerizes the acrylonitrile to a high molecular weight polymer within the outer wall and the lumen of the cotton fiber, the cotton fibers are freed from the loosely adhering extraneous polymer outside the fiber by washing or extracting the fibers with a good solvent for acrylonitrile polymer. Dimethyl formamide or dimethyl sulfoxide are two such solvents. The acrylonitrile polymer inside the fiber remains unaifected by washing or extraction of the fiber with a polymer solvent. A water wash, of the fibers, followed by drying of the fibers, completes the process.

The following examples illustrate our invention in greater detail:

EXAMPLE I Cotton fiber yarn (4 parts) was treated with an aqueous solution containing 32 parts of acrylonitrile monomer, 54 parts of zinc chloride, and 14 parts of water at room temperature by padding on of the solution to give a twofold increase in weight of the original yarn. The treated yarn was then irradiated to a dosage of 800,000 roentgens by high energy gamma ionizing radiations from radioactive coba1t-60 to radiation polymerize the acrylonitrile monomer. Then loosely adhering polymer was removed by overnight treatment of the yarn at 25 C. with N-N- dimethyl formarnide solvent. The yarn was then washed with water and dried in a current of air at 2.5 C. The

effects of the treatment on the properties of cotton fiber.

containing radiation polymerized acrylonitrile as compared with untreated, control yarns are shown in Table 1.

Table 1.-Efiect of Radiation Polymerization of Acrylonitrile With Cotton on Its Stifiness, Elongation-at- Break, and Related Properties 1 I Where indicated, treating solution: 32 parts of acrylonitriie, 54 parts of zinc chloride, and 14 parts of water; radiation dosage: 800,000 roentgens from high energy gamma ionizing radiations from radioactive cobalt'00.

EXAMPLE II Cotton fiber yarn (4 parts) was treated with an aqueous was extracted and dried as in Example 1.

7 temperature by padding on of the solution to give a twofold increase in weight of the original yarn. The treated yarn was then irradiated to dosages ranging from zero to" tion-at-break, and other related properties of the cotton fibers are shown in Table 2.

Table 2.Efiect of Radiation Dosage on Polymerization of Acrylonitrile Monomer With Cotton and on Its Stifiness, Elongation-at-Break, and Related Properties 1 Dosage, 100,000 roentgens Property of yarn Polymer content, percent 0 0 3. 6 12. 3 15. 9 26 25. 8 Average stifiness, g./tex 141 129 121 101 83 38 43 Elongation-at-break, per- 1; 13.9 12. 6 13. 9 16. 5 24. 6 22. 9 Breaking strength, lb 10. 1 9. 8 8. 7 8. 5 9.1 8. 2 8. 8 Yarn number, tex 241 248 256 276 300 398 401 Breaking stress, g./tex 19. 0 17.9 15. 3 14.0 13.7 9. 3 9. 9 Breaking toughness, g./

tex 0. 79 0.74 0. 58 0. 63 0.73 0.70 0.73 Moisture regain, percent. 7. 6 7. 7 7. 5 7.1 7. 1 6. 5 6. 4

1 Where indicated, treating solution: 32 parts of acrylonitrile, 54 parts of zinc chloride, and 14 parts of water. 2 Untreated, unlrradiated yarn. Treated, unirradiated yarn.

EXAMPLE III solutions to give a two-fold increase in weight of the original yarn. The treated yarn was then irradiated to a dosage of 800,000 roentgensby high energy gamma ionizing radiations from radioactive cobalt-60 to radiation polymerize the acrylonitrile monomer.

The effects of variations in concentrations of acrylonitrile and zinc chloride on the amount of polymer formed in the cotton and the relationship of these quantities to stiffness, elongation-at-break, and other related properties of the cotton fibers are shown in Table 3.

The yarn Table '3.-Efiect of Reagent Concentration on Polymerization of Acrylonitrile Monomer With Cotton and on Its Stiffness, Elongation-at-Break, and Related Properties 1 Treating Solutions 3 Property of Yarn A B C C 3 D E Polymer content, percent 0. 03 4. 9 22. 8 0.0 3. 7 G. 3 Average stifiness, g./tex 134 89 45 129 76 88 Elongation-at-break, percent 13.5 15.6 23. 2 13.9 18. 6 14.9 .Breaking strength, lbs 10.1 '8. 0 8. 7 9. 8 8. 9 8.2 Yarn number, tex 252 281 379 248 286' 283 Breaking stress, g./tex 18.1 13.9 10.4 17. 9 14.1 13.2 Breaking toughness, gJtex 0. 77 0. 69 0.80 0.74 0.86 0.60

1 Radiation dosage: 800,000 roentgens from high energy gamma ionizing radiations from radioactive cobalt-60.

2 Treating solution A: 32 parts of acrylonitrile, 44 parts of zinc chloride, and 24 parts of Water; B: 32, 51, 17; O: 32, 54, 14; D: 20, 60, 20; E: 40, 45, 15, respectively.

3 Treated, um'rradiated yarn.

Weclaim:

1. A process comprising padding cotton fibers to a twofold wet pick-up with an aqueous solution containing at least about 30 weight percent of acrylonitrile monomer and at least about weight percent of an inorganic salt for enhancing the solubility of the acrylonitrile in the resulting aqueous salt solution, irradiating the padded fibers to a dosage of at least about 800,000 roentgens with high energy gamma ionizing radiation to polymerize the acrylonitrile monomer within the cotton fibers to the ex tent that the irradiated fibers contain at least 20 weight percent of acrylonitrile polymer within the fibers, and removing adhering acrylonitrile polymer from the surfaces of the irradiated cotton fibers thereby to obtain cotton fibers that exhibit decreased stiffness and increased elongation-at-break as compared with untreated cotton fibers.

2. The process of claim 1 wherein the inorganic salt is zinc chloride.

References Cited in the file of this patent UNITED STATES PATENTS 2,956,899

OTHER REFERENCES Chemistry and Industry (Apr. 6, 1957), page 412. Textile Research Journal, vol. XXIX, No. 9, September 1959, page 759.

Claims

1. A PROCESS COMPRISING PADDING COTTON FIBERS TO A TWOFOLD WET PICK-UP WITH AN AQUEOUS SOLUTION CONTAINING AT LEAST ABOUT 30 WEIGHT PERCENT OF ACRYLONITRILE MONOMER AND AT LEAST ABOUT 50 WEIGHT PERCENT OF AN INORGANIC SALT FOR ENHANCING THE SOLUBILITY OF THE ACRYLONITRILE IN THE RESULTING AQUEOUS SALT SOLUTION, IRRADIATING THE PADDED FIBERS TO A DOSAGE OF AT LEAST ABOUT 800,000 ROENTGENS WITH HIGH ENERGY GAMMA IONIZING RADIATION TO POLYMERIZE THE ACRYLONITRILE MONOMER WITHIN THE COTTON FIBERS TO THE EXTENT THAT THE IRRADIATED FIBERS CONTAIN AT LEAST 20 WEIGHT PERCENT OF ACRYLONITRILE POLYMER WITHIN THE FIBERS, AND REMOVING ADHERING ACRYLONITRILE POLYMER FROM THE SURFACES OF THE IRRADIATED COTTON FIBERS THEREBY TO OBTAIN COTTON FIBERS THAT EXHIBIT DECREASED STIFFNESS AND INCREASED ELONGATION-AT-BREAK AS COMPARED WITH UNTREATED COTTON FIBERS.