US3460897A - Mild alkaline oxidation treatment of polyacrylonitrile fibers or films to improve flexibility and dyeability - Google Patents
Mild alkaline oxidation treatment of polyacrylonitrile fibers or films to improve flexibility and dyeability Download PDFInfo
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- US3460897A US3460897A US467112A US3460897DA US3460897A US 3460897 A US3460897 A US 3460897A US 467112 A US467112 A US 467112A US 3460897D A US3460897D A US 3460897DA US 3460897 A US3460897 A US 3460897A
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- 239000000835 fiber Substances 0.000 title description 16
- 229920002239 polyacrylonitrile Polymers 0.000 title description 15
- 230000003647 oxidation Effects 0.000 title 1
- 238000007254 oxidation reaction Methods 0.000 title 1
- 239000000243 solution Substances 0.000 description 18
- WQYVRQLZKVEZGA-UHFFFAOYSA-N hypochlorite Inorganic materials Cl[O-] WQYVRQLZKVEZGA-UHFFFAOYSA-N 0.000 description 15
- HEMHJVSKTPXQMS-UHFFFAOYSA-M sodium hydroxide Inorganic materials [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 14
- 238000000034 method Methods 0.000 description 11
- JIAARYAFYJHUJI-UHFFFAOYSA-L zinc dichloride Chemical compound [Cl-].[Cl-].[Zn+2] JIAARYAFYJHUJI-UHFFFAOYSA-L 0.000 description 10
- SVPXDRXYRYOSEX-UHFFFAOYSA-N bentoquatam Chemical compound O.O=[Si]=O.O=[Al]O[Al]=O SVPXDRXYRYOSEX-UHFFFAOYSA-N 0.000 description 9
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 8
- 206010061592 cardiac fibrillation Diseases 0.000 description 8
- 230000002600 fibrillogenic effect Effects 0.000 description 8
- 230000002209 hydrophobic effect Effects 0.000 description 8
- 229920000642 polymer Polymers 0.000 description 8
- 239000011780 sodium chloride Substances 0.000 description 8
- 239000007800 oxidant agent Substances 0.000 description 7
- 239000002904 solvent Substances 0.000 description 7
- 238000009987 spinning Methods 0.000 description 7
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 6
- 239000011592 zinc chloride Substances 0.000 description 5
- 235000005074 zinc chloride Nutrition 0.000 description 5
- 150000008044 alkali metal hydroxides Chemical class 0.000 description 4
- 150000003839 salts Chemical class 0.000 description 4
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 description 3
- 229910052783 alkali metal Inorganic materials 0.000 description 3
- -1 alkalimetal hypochlorite Chemical class 0.000 description 3
- 230000008901 benefit Effects 0.000 description 3
- 239000007788 liquid Substances 0.000 description 3
- 229910021645 metal ion Inorganic materials 0.000 description 3
- SUKJFIGYRHOWBL-UHFFFAOYSA-N sodium hypochlorite Chemical compound [Na+].Cl[O-] SUKJFIGYRHOWBL-UHFFFAOYSA-N 0.000 description 3
- 239000004753 textile Substances 0.000 description 3
- NLHHRLWOUZZQLW-UHFFFAOYSA-N Acrylonitrile Chemical compound C=CC#N NLHHRLWOUZZQLW-UHFFFAOYSA-N 0.000 description 2
- 239000005708 Sodium hypochlorite Substances 0.000 description 2
- 239000007864 aqueous solution Substances 0.000 description 2
- 238000009835 boiling Methods 0.000 description 2
- 239000003795 chemical substances by application Substances 0.000 description 2
- 239000000460 chlorine Substances 0.000 description 2
- 230000001112 coagulating effect Effects 0.000 description 2
- 230000015271 coagulation Effects 0.000 description 2
- 238000005345 coagulation Methods 0.000 description 2
- 238000002845 discoloration Methods 0.000 description 2
- 239000000975 dye Substances 0.000 description 2
- 238000004043 dyeing Methods 0.000 description 2
- 238000001125 extrusion Methods 0.000 description 2
- 239000004744 fabric Substances 0.000 description 2
- 239000011888 foil Substances 0.000 description 2
- 229920001519 homopolymer Polymers 0.000 description 2
- 239000000543 intermediate Substances 0.000 description 2
- AMXOYNBUYSYVKV-UHFFFAOYSA-M lithium bromide Chemical compound [Li+].[Br-] AMXOYNBUYSYVKV-UHFFFAOYSA-M 0.000 description 2
- 230000008961 swelling Effects 0.000 description 2
- ALWXETURCOIGIZ-UHFFFAOYSA-N 1-nitropropylbenzene Chemical compound CCC([N+]([O-])=O)C1=CC=CC=C1 ALWXETURCOIGIZ-UHFFFAOYSA-N 0.000 description 1
- ZKQDCIXGCQPQNV-UHFFFAOYSA-N Calcium hypochlorite Chemical compound [Ca+2].Cl[O-].Cl[O-] ZKQDCIXGCQPQNV-UHFFFAOYSA-N 0.000 description 1
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 description 1
- NMKSBNZBSLHAKW-UHFFFAOYSA-N Cl.ClO Chemical compound Cl.ClO NMKSBNZBSLHAKW-UHFFFAOYSA-N 0.000 description 1
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 1
- 229910019093 NaOCl Inorganic materials 0.000 description 1
- 241000282320 Panthera leo Species 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 239000000980 acid dye Substances 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- 229910001413 alkali metal ion Inorganic materials 0.000 description 1
- 150000001340 alkali metals Chemical class 0.000 description 1
- 229910001420 alkaline earth metal ion Inorganic materials 0.000 description 1
- 238000005904 alkaline hydrolysis reaction Methods 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 230000005587 bubbling Effects 0.000 description 1
- 125000002843 carboxylic acid group Chemical group 0.000 description 1
- 229910052801 chlorine Inorganic materials 0.000 description 1
- 238000007865 diluting Methods 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 239000000839 emulsion Substances 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 230000007062 hydrolysis Effects 0.000 description 1
- 238000006460 hydrolysis reaction Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-M hydroxide Chemical compound [OH-] XLYOFNOQVPJJNP-UHFFFAOYSA-M 0.000 description 1
- 238000002386 leaching Methods 0.000 description 1
- 230000002535 lyotropic effect Effects 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000000465 moulding Methods 0.000 description 1
- 239000003960 organic solvent Substances 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- 230000035515 penetration Effects 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 230000000717 retained effect Effects 0.000 description 1
- 239000011833 salt mixture Substances 0.000 description 1
- 239000012266 salt solution Substances 0.000 description 1
- 230000003068 static effect Effects 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 150000003567 thiocyanates Chemical class 0.000 description 1
- 238000005406 washing Methods 0.000 description 1
- 238000002166 wet spinning Methods 0.000 description 1
Classifications
-
- D—TEXTILES; PAPER
- D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
- D06P—DYEING OR PRINTING TEXTILES; DYEING LEATHER, FURS OR SOLID MACROMOLECULAR SUBSTANCES IN ANY FORM
- D06P1/00—General processes of dyeing or printing textiles, or general processes of dyeing leather, furs, or solid macromolecular substances in any form, classified according to the dyes, pigments, or auxiliary substances employed
- D06P1/44—General processes of dyeing or printing textiles, or general processes of dyeing leather, furs, or solid macromolecular substances in any form, classified according to the dyes, pigments, or auxiliary substances employed using insoluble pigments or auxiliary substances, e.g. binders
- D06P1/673—Inorganic compounds
- D06P1/67333—Salts or hydroxides
- D06P1/6735—Salts or hydroxides of alkaline or alkaline-earth metals with anions different from those provided for in D06P1/67341
- D06P1/67358—Halides or oxyhalides
-
- D—TEXTILES; PAPER
- D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
- D06M—TREATMENT, NOT PROVIDED FOR ELSEWHERE IN CLASS D06, OF FIBRES, THREADS, YARNS, FABRICS, FEATHERS OR FIBROUS GOODS MADE FROM SUCH MATERIALS
- D06M11/00—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with inorganic substances or complexes thereof; Such treatment combined with mechanical treatment, e.g. mercerising
- D06M11/07—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with inorganic substances or complexes thereof; Such treatment combined with mechanical treatment, e.g. mercerising with halogens; with halogen acids or salts thereof; with oxides or oxyacids of halogens or salts thereof
- D06M11/30—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with inorganic substances or complexes thereof; Such treatment combined with mechanical treatment, e.g. mercerising with halogens; with halogen acids or salts thereof; with oxides or oxyacids of halogens or salts thereof with oxides of halogens, oxyacids of halogens or their salts, e.g. with perchlorates
-
- D—TEXTILES; PAPER
- D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
- D06M—TREATMENT, NOT PROVIDED FOR ELSEWHERE IN CLASS D06, OF FIBRES, THREADS, YARNS, FABRICS, FEATHERS OR FIBROUS GOODS MADE FROM SUCH MATERIALS
- D06M11/00—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with inorganic substances or complexes thereof; Such treatment combined with mechanical treatment, e.g. mercerising
- D06M11/32—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with inorganic substances or complexes thereof; Such treatment combined with mechanical treatment, e.g. mercerising with oxygen, ozone, ozonides, oxides, hydroxides or percompounds; Salts derived from anions with an amphoteric element-oxygen bond
- D06M11/36—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with inorganic substances or complexes thereof; Such treatment combined with mechanical treatment, e.g. mercerising with oxygen, ozone, ozonides, oxides, hydroxides or percompounds; Salts derived from anions with an amphoteric element-oxygen bond with oxides, hydroxides or mixed oxides; with salts derived from anions with an amphoteric element-oxygen bond
- D06M11/38—Oxides or hydroxides of elements of Groups 1 or 11 of the Periodic Table
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10S8/00—Bleaching and dyeing; fluid treatment and chemical modification of textiles and fibers
- Y10S8/92—Synthetic fiber dyeing
- Y10S8/927—Polyacrylonitrile fiber
Definitions
- This invention relates to a method for treating polymeric articles such as fibers or films consisting essentially of polyacrylonitrile. More particularly, it relates to a simple, easily controlled treatment of salt spun polyacrylonitrile articles with an aqueous alkaline mild oxidizing agent to improve the flexibility and subsequent resistance to fibrillation, as well as the dyeability thereof.
- polyacrylonitrile may advantageously be fabricated by a wet spinning process wherein the polymer is extruded in polyacrylonitrile-dissolving aqueous saline solvents, particularly aqueous solutions of zinc chloride and its saline equivalents.
- aqueous saline solvents particularly aqueous solutions of zinc chloride and its saline equivalents.
- salt-spinning is oftentimes referred to as salt-spinning with the fibers (or other shaped articles) obtained thereby being salt-spun.
- aqueous saline spinning solution or other composition of the polymer is extruded during the spinning operation into a non-polymer dissolving coagulation liquid, or spin bath, which frequently is a solution of the same salt or salts as are in the spinning solution.
- Homopolymers of acrylonitrile that are salt-spun in the referred to manner are generally formed initially as aquagel intermediates. Such intermediates have a waterswollen or hydrated structure prior to their being finally irreversibly dried to the desired, characteristically hydrophobic product.
- the aquagel structure of polyacrylonitrile may be derived by the extrusion into and coagulation in an aqueous coagulating spin bath of a solution of the acrylonitrile polymer that is dissolved in an aqueous zinc chloride saline solvent therefor. It is usually desirable for zinc chloride to be at least the principal (if not the entire) saline solute in the aqueous saline solvent solution.
- various of the saline equivalents for zinc chloride may also 'be employed in the aqueous saline solvent medium for the spinning solution and the coagulating bath utilized.
- These zinc chloride equivalents include various of the thiocyanates (such as calcium thiocyanate) lithium bromide and the salts and salt mixtures that are solvent members of the so-called lyotropic series as are disclosed, among other places, in U.S. 2,140,921, 2,425,192, 2,648,592, 2,648,593, 2,648,646, 2,648,648, and 2,648,649.
- Fabricated acrylonitrile polymer films, textile fibers and ice like filamentous articles derived from salt-spinning processes are generically described as being capable of lying substantially in a single plane, having at least one major dimension, and at least one minor dimension less than about 0.1 inch, said articles being characterized by having orientation of the molecules parallel to one another and to a major surface of the article. Such articles are often hard and brittle and have a tendency to fibrillate during preparation and such subsequent normal usage of the shaped article.
- fibrillation is used in the textile industry to indicate a type of fiber disintegration or longitudinal fracture generally along the lines of molecular orientation. As a consequence of fibrillation the fiber or filament is longitudinally divided into segments or fibrils. Often, fibrillation may result in a frosty or whitened appearance, even of dyed fibers and fabrics.
- the loss of color or change toward white is affected by several variables including the amount of division and size of fibrils produced during processing of the spun product. Fibrils can be of such small diameters that incident light is scattered. Fibrillation of textile fibers and fabric produced therefrom appears to result from transverse forces which ultimately cause a shattering of the fiber along the lines of least resistance, namely longitudinally. Thus, a fiber or related filamentous article having greater characteristic flexibility may often be loss prone to fibrillation than a corresponding relatively less flexible article,
- homopolymeric acrylonitrile is highly hydrophobic, and that fibers made therefrom are less easily dyed than most other fibers, whether natural or synthetic.
- the treatment of the present invention is a method in which a normally hydrophobic polyacrylonitrile article, such as a fiber or film, is subjected to alkaline hydrolysis with resultant formation of carboxylic acid groups along the polymer chain without accompanying polymer discoloration resulting from such hydrolysis.
- the method comprises (1) immersing such article in a bath of a liquid aqueous alkaline mild oxidizing agent composed essentially of (a) from about 0.2 to 10 percent of an alkali metal hydroxide and (b) from about 1.5 to 10 percent of a hypochlorite, wherein such bath is continuously maintained at a pH of greater than 7 and wherein the article is immersed in the bath for a time inversely related to the temperature, varying from about 3 to 5 minutes near the boiling temperature to from about 1 to about 4 hours at room temperature, and at least for a time sufiicient to provide an article which when washed and dried, exhibits swelling in water.
- a liquid aqueous alkaline mild oxidizing agent composed essentially of (a) from about 0.2 to 10 percent of an alkali metal hydroxide and (b) from about 1.5 to 10 percent of a hypochlorite, wherein such bath is continuously maintained at a pH of greater than 7 and wherein the article is immersed in the bath for a time inverse
- the treatment may be applied to any article made of polyacrylonitrile, but is of special benefit to those thin articles such as fibers and films.
- the aqueous alkaline mild oxidizing agent useful in the invention should ordinarily, and for greatest utility of the treated product, be substantially free from discoloring metal ions, especially those colored polyvalent metal ions which might form chelates with and become bound to the polymer.
- the most economical agents to use have as the only metal ions present, the colorless alkali metal or alkaline earth metal ions.
- the alkalinity of the aqueous oxidizing agents is preferably provided by sodium or potassium hydroxide.
- the oxidizer is a hypochlorite, illustratively sodium hypochlorite or calcium hypochlorite or hypochlorite-chloride.
- concentration of alkali in the treating solution should not be significantly over 2.5 Normal, as much higher concentrations lead to different results. Concentrations of sodium hydroxide or of patasslum hydroxide in the treating solution ranging from about 0.2 percent to about percent, by weight are quite satisfactory.
- concentration of hypochlorite used as the mild oxidizer is conveniently in the range from about 1.5 percent to 10 percent of the weight of solution.
- films or sheets may be treated which were produced by molding or extrusion, or by being cast from solution or emulsion, or by being coagulated from solution by contact with a non-solvent for the polymer which is miscible with the solvent.
- fibers and filaments may be treated which have been wet spun or dry spun from organic solvents or have been wet spun from known, aqueous strong salt solutions and thus coagulated as filamentary aquagel, as is known in the art.
- the present treatment may be applied while the gel condition is retained, or it may be applied after the article has been so thoroughly dried as irreversibly to destroy the aquagel condition.
- an alkaline hypochlorite solution was prepared by dissolving 100 grams of NaOH in water, diluting to one liter, and bubbling chlorine into the solution until the weight had increased by 71 grams.
- the resulting solution contained about one gram mole of NaOCl and about 0.5 gram mole of free NaOH per liter.
- the polymeric products treated in accordance with the invention have less tendency to undergo undesirable fibrillation and to acquire and retain charges of static electricity, than do similar but untreated hydrophobic polyacrylonitrile articles.
- the method which comprises (1) immersing a normally hydrophobic article consisting essentially of polyacrylonitrile in a bath of a liquid aqueous alkaline mild oxidizing agent composed essentially of (a) from about 0.2 to 10 percent of an alkali metal hydroxide and (b) from about 1.5 to 10 percent of an alkali metal hypochlorite, said bath being continuously maintained at a pH greater than 7 and said articles being immersed in said bath for a time inversely related to the temperature, vary from about 3 to 5 minutes near the boiling temperature to from 1 to about 4 hours at room temperature, but at least for a time sufficient to provide an article which when washed and dried exhibits swelling in water, and (2) washing the article to remove the alkaline agent.
- a liquid aqueous alkaline mild oxidizing agent composed essentially of (a) from about 0.2 to 10 percent of an alkali metal hydroxide and (b) from about 1.5 to 10 percent of an alkali metal hypochlorite
- said normally hydrophobic article is a thin, flexible article from the class consisting of foils and filaments.
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- Engineering & Computer Science (AREA)
- Textile Engineering (AREA)
- Chemical & Material Sciences (AREA)
- Inorganic Chemistry (AREA)
- Treatments Of Macromolecular Shaped Articles (AREA)
Description
United States Patent ABSTRACT OF THE DISCLOSURE The treatment or articles of polyacrylonitrile with an aqueous solution of alkali metal hydroxide and alkalimetal hypochlorite to improve flexibility, resistance to fibrillation and dyeability.
This application is a continuation-in-part of copending application Ser. No. 292,771, now abandoned, filed July 3, 1963, which is in turn a continuation-in-part of applica tion Ser. No. 113,117, filed May 29, 1961, now United States Patent No. 3,127,233.
This invention relates to a method for treating polymeric articles such as fibers or films consisting essentially of polyacrylonitrile. More particularly, it relates to a simple, easily controlled treatment of salt spun polyacrylonitrile articles with an aqueous alkaline mild oxidizing agent to improve the flexibility and subsequent resistance to fibrillation, as well as the dyeability thereof.
It is well known that polyacrylonitrile may advantageously be fabricated by a wet spinning process wherein the polymer is extruded in polyacrylonitrile-dissolving aqueous saline solvents, particularly aqueous solutions of zinc chloride and its saline equivalents. Such a procedure, as is well known in the art, is oftentimes referred to as salt-spinning with the fibers (or other shaped articles) obtained thereby being salt-spun. In salt-spinning the fiberforming aqueous saline spinning solution or other composition of the polymer is extruded during the spinning operation into a non-polymer dissolving coagulation liquid, or spin bath, which frequently is a solution of the same salt or salts as are in the spinning solution.
Homopolymers of acrylonitrile that are salt-spun in the referred to manner are generally formed initially as aquagel intermediates. Such intermediates have a waterswollen or hydrated structure prior to their being finally irreversibly dried to the desired, characteristically hydrophobic product.
Advantageously, the aquagel structure of polyacrylonitrile may be derived by the extrusion into and coagulation in an aqueous coagulating spin bath of a solution of the acrylonitrile polymer that is dissolved in an aqueous zinc chloride saline solvent therefor. It is usually desirable for zinc chloride to be at least the principal (if not the entire) saline solute in the aqueous saline solvent solution.
If preferred, however, various of the saline equivalents for zinc chloride may also 'be employed in the aqueous saline solvent medium for the spinning solution and the coagulating bath utilized. These zinc chloride equivalents, as is well known, include various of the thiocyanates (such as calcium thiocyanate) lithium bromide and the salts and salt mixtures that are solvent members of the so-called lyotropic series as are disclosed, among other places, in U.S. 2,140,921, 2,425,192, 2,648,592, 2,648,593, 2,648,646, 2,648,648, and 2,648,649.
Fabricated acrylonitrile polymer films, textile fibers and ice like filamentous articles derived from salt-spinning processes are generically described as being capable of lying substantially in a single plane, having at least one major dimension, and at least one minor dimension less than about 0.1 inch, said articles being characterized by having orientation of the molecules parallel to one another and to a major surface of the article. Such articles are often hard and brittle and have a tendency to fibrillate during preparation and such subsequent normal usage of the shaped article.
The term fibrillation is used in the textile industry to indicate a type of fiber disintegration or longitudinal fracture generally along the lines of molecular orientation. As a consequence of fibrillation the fiber or filament is longitudinally divided into segments or fibrils. Often, fibrillation may result in a frosty or whitened appearance, even of dyed fibers and fabrics.
The loss of color or change toward white is affected by several variables including the amount of division and size of fibrils produced during processing of the spun product. Fibrils can be of such small diameters that incident light is scattered. Fibrillation of textile fibers and fabric produced therefrom appears to result from transverse forces which ultimately cause a shattering of the fiber along the lines of least resistance, namely longitudinally. Thus, a fiber or related filamentous article having greater characteristic flexibility may often be loss prone to fibrillation than a corresponding relatively less flexible article,
It is further well known that homopolymeric acrylonitrile is highly hydrophobic, and that fibers made therefrom are less easily dyed than most other fibers, whether natural or synthetic.
It would be desirable, therefore, to provide a simple treatment capable of producing more flexible and less hydrophobic articles such as filaments and films, having large surface area relative to thickness (or diameter), which are composed of polyacrylonitrile. It is the principle object of this invention to provide such a treatment.
The treatment of the present invention, whereby the foregoing and related objects are attained, is a method in which a normally hydrophobic polyacrylonitrile article, such as a fiber or film, is subjected to alkaline hydrolysis with resultant formation of carboxylic acid groups along the polymer chain without accompanying polymer discoloration resulting from such hydrolysis.
More particularly, the method comprises (1) immersing such article in a bath of a liquid aqueous alkaline mild oxidizing agent composed essentially of (a) from about 0.2 to 10 percent of an alkali metal hydroxide and (b) from about 1.5 to 10 percent of a hypochlorite, wherein such bath is continuously maintained at a pH of greater than 7 and wherein the article is immersed in the bath for a time inversely related to the temperature, varying from about 3 to 5 minutes near the boiling temperature to from about 1 to about 4 hours at room temperature, and at least for a time sufiicient to provide an article which when washed and dried, exhibits swelling in water.
The treatment may be applied to any article made of polyacrylonitrile, but is of special benefit to those thin articles such as fibers and films.
The aqueous alkaline mild oxidizing agent useful in the invention should ordinarily, and for greatest utility of the treated product, be substantially free from discoloring metal ions, especially those colored polyvalent metal ions which might form chelates with and become bound to the polymer. The most economical agents to use have as the only metal ions present, the colorless alkali metal or alkaline earth metal ions. The alkalinity of the aqueous oxidizing agents is preferably provided by sodium or potassium hydroxide. The oxidizer is a hypochlorite, illustratively sodium hypochlorite or calcium hypochlorite or hypochlorite-chloride. The concentration of alkali in the treating solution should not be significantly over 2.5 Normal, as much higher concentrations lead to different results. Concentrations of sodium hydroxide or of patasslum hydroxide in the treating solution ranging from about 0.2 percent to about percent, by weight are quite satisfactory. The concentration of hypochlorite used as the mild oxidizer is conveniently in the range from about 1.5 percent to 10 percent of the weight of solution.
While the invention is not limited to the treatment of foils, fibers and similarly thin, flexible articles, it finds particular advantage with such materials. It is applicable to such articles regardless of the manner in which they were prepared. Thus, films or sheets may be treated which were produced by molding or extrusion, or by being cast from solution or emulsion, or by being coagulated from solution by contact with a non-solvent for the polymer which is miscible with the solvent. Similarly, fibers and filaments may be treated which have been wet spun or dry spun from organic solvents or have been wet spun from known, aqueous strong salt solutions and thus coagulated as filamentary aquagel, as is known in the art. When films or filaments are first formed as an aquagel, the present treatment may be applied while the gel condition is retained, or it may be applied after the article has been so thoroughly dried as irreversibly to destroy the aquagel condition.
In one illustration of the practice of this invention, an alkaline hypochlorite solution was prepared by dissolving 100 grams of NaOH in water, diluting to one liter, and bubbling chlorine into the solution until the weight had increased by 71 grams. The resulting solution contained about one gram mole of NaOCl and about 0.5 gram mole of free NaOH per liter.
Several samples of polyacrylonitrile aquagel, 0.01 inch thick, were immersed in the alkaline hypochlorite solution for periods of between 1 and 24 hours, and then removed from the treating solution, rinsed with water, and dried to destroy the aquagel condition. The dried samples were then immersed in water and their wet flexibility was evaluated qualitatively. Each sample Was then subjected to a standard dyeing procedure, using Irgalan Blue Gl, an acid dye (Colour Index Acid Blue 166), and the color yields were compared, as were the depths of penetration of the dye.
Other samples of the same polymer aquagel were immersed in the alkaline hypochlorite solution for periods of 0.5 to 2 hours at 35 C.; 0.5 hour at 50 C.; 0.1 to 0.25 hour at 70 C.; and 0.05 to 0.1 hour at 90 C. The samples were removed from the treating solution, washed, dried irreversibly, and subjected to dyeing as described above. In each case, the treated product, after exposure as reported above, and when washed and dried, was
found to have highly desirable wet flexibility, was free from undesirable discoloration and was more receptive to dyes than is the normal hydrophobic polyacrylonitrile.
In addition to the benefits previously mentioned, the polymeric products treated in accordance with the invention have less tendency to undergo undesirable fibrillation and to acquire and retain charges of static electricity, than do similar but untreated hydrophobic polyacrylonitrile articles.
I claim:
1. The method which comprises (1) immersing a normally hydrophobic article consisting essentially of polyacrylonitrile in a bath of a liquid aqueous alkaline mild oxidizing agent composed essentially of (a) from about 0.2 to 10 percent of an alkali metal hydroxide and (b) from about 1.5 to 10 percent of an alkali metal hypochlorite, said bath being continuously maintained at a pH greater than 7 and said articles being immersed in said bath for a time inversely related to the temperature, vary from about 3 to 5 minutes near the boiling temperature to from 1 to about 4 hours at room temperature, but at least for a time sufficient to provide an article which when washed and dried exhibits swelling in water, and (2) washing the article to remove the alkaline agent.
2. The method claimed in claim 1, wherein said normally hydrophobic article is a thin, flexible article from the class consisting of foils and filaments.
3. The method claimed in claim 2, wherein the article immersed in the alkaline oxidizing medium is in the aquagel condition at the time of treatment.
4. The method claimed in claim 1, wherein said alkali metal hydroxide is sodium hydroxide and said alkali metal hypochlorite is sodium hypochlorite.
References Cited UNITED STATES PATENTS 3,127,233 3/1964 Lowes 8-55 3,056,645 10/1962 Anderson et al. 8108 XR 2,641,524 6/1953 Chaney et al. 855 2,432,448 12/1947 Richards 855 XR OTHER REFERENCES Sergeant et al.: Journal of the American Chemical Society, vol. 42, An Amperometric Tetration Method for the Leaching Evaluation, pp. 118-129.
NORMAN G. TORCHIN, Primary Examiner JACK P. BRAMMER, Assistant Examiner U.S. Cl. X.R. 84, 55, 108
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
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US46711265A | 1965-06-25 | 1965-06-25 |
Publications (1)
Publication Number | Publication Date |
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US3460897A true US3460897A (en) | 1969-08-12 |
Family
ID=23854407
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US467112A Expired - Lifetime US3460897A (en) | 1965-06-25 | 1965-06-25 | Mild alkaline oxidation treatment of polyacrylonitrile fibers or films to improve flexibility and dyeability |
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US (1) | US3460897A (en) |
Cited By (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4366206A (en) * | 1978-04-18 | 1982-12-28 | Japan Exlan Co., Ltd. | Novel water-swellable fibers having a high degree of water-swellability and excellent physical properties and process for producing the same |
US4374175A (en) * | 1979-01-16 | 1983-02-15 | Japan Exlan Co., Ltd. | Novel water-swellable fibers and process for producing the same |
US4562114A (en) * | 1981-08-10 | 1985-12-31 | Japan Exlan Company Limited | Water-absorbing acrylic fibers |
US4873143A (en) * | 1986-05-06 | 1989-10-10 | Japan Exlan Company Limited | Water-swellable fiber |
US20130255488A1 (en) * | 2011-03-30 | 2013-10-03 | Electric Power Research Institute, Inc. | Method and apparatus for rapid adsorption-desorption co2 capture |
Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2432448A (en) * | 1945-01-10 | 1947-12-09 | Du Pont | Bleaching polyacrylonitrile |
US2641524A (en) * | 1949-07-13 | 1953-06-09 | American Viscose Corp | Acrylonitrile-vinyl amine interpolymers and method of making |
US3056645A (en) * | 1959-10-09 | 1962-10-02 | Pittsburgh Plate Glass Co | Process of bleaching sized cotton fabrics |
US3127233A (en) * | 1964-03-31 | Cross referenci |
-
1965
- 1965-06-25 US US467112A patent/US3460897A/en not_active Expired - Lifetime
Patent Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3127233A (en) * | 1964-03-31 | Cross referenci | ||
US2432448A (en) * | 1945-01-10 | 1947-12-09 | Du Pont | Bleaching polyacrylonitrile |
US2641524A (en) * | 1949-07-13 | 1953-06-09 | American Viscose Corp | Acrylonitrile-vinyl amine interpolymers and method of making |
US3056645A (en) * | 1959-10-09 | 1962-10-02 | Pittsburgh Plate Glass Co | Process of bleaching sized cotton fabrics |
Cited By (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4366206A (en) * | 1978-04-18 | 1982-12-28 | Japan Exlan Co., Ltd. | Novel water-swellable fibers having a high degree of water-swellability and excellent physical properties and process for producing the same |
US4374175A (en) * | 1979-01-16 | 1983-02-15 | Japan Exlan Co., Ltd. | Novel water-swellable fibers and process for producing the same |
US4562114A (en) * | 1981-08-10 | 1985-12-31 | Japan Exlan Company Limited | Water-absorbing acrylic fibers |
US4873143A (en) * | 1986-05-06 | 1989-10-10 | Japan Exlan Company Limited | Water-swellable fiber |
US20130255488A1 (en) * | 2011-03-30 | 2013-10-03 | Electric Power Research Institute, Inc. | Method and apparatus for rapid adsorption-desorption co2 capture |
US8911536B2 (en) * | 2011-03-30 | 2014-12-16 | Electric Power Research Institute, Inc. | Method and apparatus for rapid adsorption-desorption CO2 capture |
US9144766B2 (en) | 2011-03-30 | 2015-09-29 | Electric Power Research Institute, Inc. | Method and apparatus for rapid adsorption-desorption CO2 capture |
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