Classifications

• • 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
  • D06M13/00—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with non-macromolecular organic compounds; Such treatment combined with mechanical treatment
  • D06M13/10—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with non-macromolecular organic compounds; Such treatment combined with mechanical treatment with compounds containing oxygen
  • D06M13/12—Aldehydes; Ketones
  • D06M13/127—Mono-aldehydes, e.g. formaldehyde; Monoketones
• • D—TEXTILES; PAPER
  • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
  • D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
  • D01F6/00—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof
  • D01F6/58—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from homopolycondensation products
  • D01F6/60—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from homopolycondensation products from polyamides
• • 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
  • D06M13/00—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with non-macromolecular organic compounds; Such treatment combined with mechanical treatment
  • D06M13/10—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with non-macromolecular organic compounds; Such treatment combined with mechanical treatment with compounds containing oxygen
  • D06M13/12—Aldehydes; Ketones

Definitions

• This invention relates to new and improved polypyrrolidone fibers and to a process for preparing the same. More particularly, the invention is concerned with new and improved polypyrrolidone fibers prepared by treating said fibers with formaldehyde.
• polypyrrolidone fibers as used herein is to be understood as including within its scope polypyrrolidone, fibers, filaments, monofilament yarns, staple yarns, threads, cords, and woven and non-woven fabrics, being comprised of at least about 50% by weight of polypyrrolidone and in a more specific sense fabrics comprised of 90% and more of polypyrrolidone monofilament yarn and/or staple.
• the process is herein described particularly with reference to fibers comprised substantially entirely of polypyrrolidone, but it is understood that this is intended in an illustrative sense and the invention should not be limited thereby but only insofar as the same may be limited by the appended claims.
• polypyrrolidone to form polypyrrolidone
• Melt extrusion of polypyrrolidone has been employed for formation of filaments which lend themselves admirably to the production of fibers and fabrics having desirable properties of moisture absorption and strength.
• the fibers are generally stretched to improve the mechanical properties by orientation of the structure.
• Polypyrrolidone fibers although generally having excellent properties, possess two disadvantages.
• Fibrillation is a phenomenon induced in fibrous materials by the application of stress, usually in the form of abrasion, and is characterized by the splitting off from the parent filament or fiber of longitudinal sections of material which are usually referred to as fibrils.
• the dimensions of the fibrils are small compared to those of the original filament fiber.
• the splitting off of the fibrils is referred to as fiber breakdown and can readily be observed under the microscope, where the presence of fibrils may be seen. In undyed fabrics, however, the presence of fibrils may not be apparent to casual inspection but it is evidenced by dulling of the finish and can be seen on microscopic examination.
• Dyed fibers of melt extruded and oriented polypyrrolidone readily display the eifects of fibrillation, although because of the ready dyeability of these fibers the visual effect of fibrillation is rather less pronounced than in the case of less readily dyed materials.
• abrasion which causes fibrillation occurring, for example, at wear points of clothing may result in exposure of deeper dyed or undyed portions of the individual fibers with a resultant shade change which is very undesirable for commercial acceptability.
• Another object of the invention is to provide a process for the production or manufacture of non-fibrillating polypyrrolidone structures.
• substantially non-fibrillating polypyrrolidone fibers are produced by cross-linking of the polymer molecules composing the fibers with aldehydic cross-linking agents, preferably formaldehyde, in the presence of a weakly acidic methylolation catalyst, e.g. ammonium chloride.
• aldehydic cross-linking agents preferably formaldehyde
• a weakly acidic methylolation catalyst e.g. ammonium chloride
• the process of the invention comprises the cross-linking of polypyrrolidone fibers under conditions in which the fibers do not dissolve or become appreciably soluble in the agents used in the process.
• the invention comprehends a process in which an oriented, heat-set fiber is treated with an aldehydic agent and the product consists of a highly shrink-resistant, fibrillation-resistant fiber which has greatly improved launderability.
• Hot tempering sometimes also called heat setting, may be performed using conventional machinery for the purpose. placed under a tension of at least 0.05 gram per denier and are then subjected to hot tempering conditions.
• Fibers and filaments may be wound on reels of suitable size and shape, preferably with a foraminous core so that penetration of reactants and convection heating can reach the fibers from both outsideand inside, i.e. maintaining static tension.
• pins in the reel may engage the edges of the fabric to effect lateral tension in the warp.
• Dry hot tempering where the atmosphere used is relatively free from water (e.g. up to 0.2 atmosphere partial pressure), is carried out at temperatures of about 190 to about 235 C. for a time sufficient so that the entire fiber cross-section reaches the desired temperature.
• a hot gas such as air
• dwell times may be from about minutes at 200 C. down to 3 minutes at 230 C.
• dwell times are much shorter, being from about 5 seconds at 190 C. to about 0.3 second at 235 C. Such short times are obviously advantageous for continuous dynamic hot tempering processes.
• Hot tempered fiber is fiber which has been oriented to an appreciable degree and then heated to a temperature sufficient to substantially prevent dimensional change when heated to the boiling point of water.
• the second step of the process of the invention consists in cross-linking the polymer molecules of the oriented fibers with formaldehyde in the presence of a weakly acidic methylolation catalyst.
• formaldehyde is used to encompass aldehydic agents such as formaldehyde and sources thereof, e.g. paraformaldehyde, methylol urea, dimethylol ethylene urea, dimethyl formal, saligenin, formalin, hexamethylene tetramine, and the like.
• This may be viewed as occurring in two stages, first, a reaction to partially methylolate the polypyrrolidone molecules, to an extent sufficient to fix the formaldehyde but which does not solubilize the polypyrrolidone and second, elimination of water from the polypyrrolidone containing the fixed formaldehyde to form crosslinks.
• the hot-tempered polypyrrolidone fiber (preferably, but not necessarily, still under a certain amount of tension) is most conveniently impregnated with the methylolation catalyst and the aldehydic agent in water solution. Under such conditions, saturation of the polypyrrolidone article effects an uptake of about 4 to of the weight thereof of the saturating solution.
• the formaldehyde may be introduced either concomitantly with the aqueous catalyst or subsequently thereto.
• the fiber is heated at a temperature in the range of about 50 to about 150 C. for from about 1 to 60 minutes. Higher temperatures are used with shorter times and vice versa. At the higher temperatures there may be some risk of injuring the fiber, i.e. tendering, unless quite short times of treatment are employed and such temperatures are better utilized in conjunction with continuous operation rather than batch processes.
• the fiber containing the catalyst if first dried and is than exposed to gaseous or vaporous formaldehyde at a temperature of about 120 to about 150 C. for from about 2 to about 30 minutes. It will be evident that the amount of formaldehyde available for reaction will influence the time of reaction in this and other instances as will the bulk of the fibers being treated.
• the gel content of the polypyrrolidone after crosslinking is a measure of the desired and essential extent of crosslinking.
• the gel content of the formaldehyde-treated, crosslinked fiber is determined as follows: One part by weight of treated fiber is added to 50 parts of trifiuoromethanol and the mixture is stirred at about 25 C. for 8 hours, and then is poured into a tared glass suction filter funnel with fritted glass disk. The trifluoroethanol and dissolved polymer is removed by suction, and the remaining insoluble material is Washed with 10 parts of fresh trifluoroethanol. The solvent is again removed by suction and the remaining material is dried in the funnel for 16 hours in a vacuum oven at 120 C., cooled and weighed. The fraction of the original sample which remains, expressed as a percentage, is the gel content.
• Treated fiber having a gel content above about has improved properties, with reduced fibrillation.
• the gel content is over
• fibers having or higher gel content are practically non-fibrillating.
• methylolation catalysts which are useful for the purposes of the invention are those reagents or combination of reagents which produce aqueous solutions of pH values ranging from pH 1 to pH 5.
• Specific examples of such agents include dilute aqueous solutions of strong acids, water-soluble weak acids and salts of acids with weaker bases.
• Such substances include 0.01 N aqueous hydrochloric acid, ammonium chloride, zinc chloride, sodium bisulfite, ammonium sulfate, oxalic acid and very dilute formic acid.
• Glycolic and lactic acid are also suitable as catalysts but have the disadvantage of plasticizing the fibers and thus degrading their mechanical properties.
• a sufficient amount of catalyst is used to ensure take-up of about 0.1 to 10 percent by weight of formaldehyde; or, alternatively, to provide a gel content in the treated fiber above about 80%, when an excess of formaldehyde is used.
• catalysts When smaller amounts of catalysts are used, larger periods of exposure to formaldehyde may be necessary.
• dilute solutions of strong acids it should be noted that the saturated fiber should not be completely dried because the concentration of acid will become excessively great.
• the heating befor periods no longer than the approximate maxima stated hereinabove, where residual fiber strength is a material factor.
• polypyrrolidone fibers treated by the remediation process of the invention possess lowered dye receptivity and strongly enhanced resistance to fibrillation.
• the resistance of the fibers to fibrillation is determined by a useful and reproducible test method which is a variation of the commercial accelerotor abrasion test.
• bundles of fibers are mounted on the periphery of a 4 /2 inch diameter disc so that they extend radially for 1 inch. (Eight such bundles can be accommodated at one time without interference one with the other.)
• the disc is rotated at 1000 r.p.m. for 3 minutes with the bundles of fibers contacting the internal wall of a 5% inch diameter cylinder having 2 small corrugations per inch of periphery on the inner surface each about inch high and with a pool of 35 ml. of water at about 25 C. in the bottom of the cylinder to keep the fibers thoroughly wet.
• This test corresponds approximately to the effect to be expected from 20 cycles of washing in a household washing machine each followed by tumble drying.
• This treatment rapidly produces fibrillation of susceptible fibers, the extent of which is designated by numerical scores.
• a microscope IOU-200x
• a score of 6 or higher up to 10 indicates progressively more felting of the fibril ends in a bundle, 10 indicating a state in which the fibers are completely frayed so that each appears pilose.
• a "score of 6 indicates marked improvement in fibrillation, while a score of 0 indicates no fibrillation.
• the presence of a moderate number of fibrils, i.e. a score of 3-4 is considered to represent an improvement over unreacted fibers which is practically speaking very useful.
• Example 1 Approximately four ounces of 40 denier yarn composed of continuous filaments of polypyrrolidone (formed by melt extruding and oriented by cold drawing in an approximate 3.2:] ratio) are wound on a 4-inch diameter forarninous core and wet hot tempered in an autoclave with saturated steam at about 103 C. for 1 hour. After cooling and drying the yarn is rewound under approximately the same tension onto four 1 /2 inch diameter foraminous stainless steel cores, each containing about one ounce of fiber. An additional small sample is retained as a control. The four test samples are impregnated with an aqueous solution containing 37% formaldehyde and 1.7% ammonium chloride by immersion therein for 5 minutes.
• the four samples are then dried for minutes at 50, 60, 70 and 80 C. respectively (one at each temperature) to fix the formaldehyde and then all are placed in an oven at 150 C. for 5 minutes to effect crosslinking. They are washed to remove residual catalyst and dried. Rating of the different samples for fibrillation as hereinabove described shows that none of the cross-linked yarns fibrillates under the test conditions, therefore all rate 0 as the fibrillation score.
• the samples are further tested by conventional methods to determine tenacity, elongation at. break, modulus of elasticity in grams per denier at 1% elongation and percent shrinkage on boiling for 10 minutes in water under 0.01 gram per denier tension followed by conditioning at 65% relative humidity at 72 F.
• the latter and the three hot tempered specimens are immersed in a 5% solution of ammonium chloride in water for 5 minutes, removed and dried in a vacuum oven at 55 C. for 15 minutes.
• the four impregnated specimens still on the frames are then placed in a vessel heated to C. and gaseous formaldehyde (from heating a slurry of paraformaldehyde in mineral oil) is passed over them for four minutes.
• the specimens are thereafter washed to remove ammonium chloride and dried.
• the uptake of formaldehyde is about 5%. When the uptake is higher, e.g.
• Fibers are obtained from each of these four cross-linked specimen and from. the control by ravelling the specimens so that warp fibers from the treated areas are obtained and the fibers thus obtained are tested as in Example 1 above. The results are shown in Table TAB LE II Tenacity Elonga- Modulus Shrinkage Fibrilla- Specimen gr. per on (gr. per (percent) tion denier (percent) denier) (Score) Control. 2. 7 27 7 42 10 1 1.
• non-woven fabrics havwhich are cross-linked, thus being non-fibrillating, but not heat-set. These fabrics stretch when wet and shrink when dry, much like certain natural products such as chamois leather.
• Example 3 A bolt of taffeta similar to that employed in Example 2 containing yards of material inches wide is wound on a stainless steel mandrel, 8 inches in diameter, which fits a commercial pressure dyeing machine. Without mechanical modification, such a machine does not maintain the lateral tension which is desirable; but useful results are obtained.
• the roll is placed in the machine and hot tempered by circulating water at 105 C. under pressure therethrough for one hour, after which the roll is removed and the fabric transferred to and dried in a hot tenter frame by infrared lamps in a single pass with a dwell time of about seconds.
• a twelve yard length of the goods is run through a dip tank containing 5 gallons of 37% aqueous formaldehyde solution containing 2% of ammonium chloride.
• the excess solution is removed by passing the goods through a padding machine at 80 pounds roll pressure so that the uptake of solution is about -75% by weight.
• the goods are then threaded into a loop drying oven and held at 85-90 C. for 30 minutes to effect drying with fixation of the formaldehyde and cross-linking. They are washed to remove residual ammonium chloride and a piece is ravelled to provide test yarns as in Example 2. Both warp and woof are tested and both score 0 for fibrillation. As noted, because of the lack of lateral tension the woof has a tenacity of 1.1 grams per denier and modulus of 4.0 while the warp is fully beneficiated with tenacity of 2.0 grams per denier and modulus of 11. Nevertheless, both have 0% shrinkage and are non-fibrillating. Treatment at higher temperatures as in examples, provides yarns having higher values of modulus.
• Example 4 This example shows the effect of variation in composition of the treating solution employed. The procedure is that of Example 1 above.
• Yarn specimens on cores are saturated with aqueous formaldehyde solutions of various concentration containing ammonium chloride at several concentrations for 5 minutes and then dried at 60 C. for 15 minutes to fix the formaldehyde and cross-linked by heating for 5 minutes at 150 C.
• the specimens are washed and dried and tested as above.
• the variations in concentrations in the saturating solutions and the results of the tests are Example 5
• An alternative procedure which may be employed in the process of the invention is to subject the yarn continuously to the aldehydic agent and catalyst. In this process dwell times are generally much shorter than employed in the batch-type procedures described above. Adjustment of the temperature of cross-linking or curing for a given dwell time is found to be desirable.
• Yarn such as that used in Example 1 is saturated (10 seconds dwell time) with a solution containing 37% formaldehyde and 1.7% ammonium chloride and is dried for 1 minute at 61 C. It is then cured or crosslinked for 1 minute at various temperatures. The variations in properties of the yarn (after washing and drying) are compared in Table V.
• Beneficiated polypyrrolidone fibers containing an amount of chemically bound formaldehyde effective to substantially reduce the fibrillation properties thereof produced by the process of subjecting polypyrrolidone fibers to the action of formaldehyde in the presence of an acidic methylolation catalyst under non-solubilizing conditions and removing water to effect cross-linking.
• Beneficiated polypyrrolidone fibers containing from about 0.3 to about 5 percent by weight of chemically bound formaldehyde produced by the process of subjecting polypyrrolidone fibers to the action of formaldehyde in the presence of an acidic methylolation catalyst under non-solubilizing conditions and removing Water to eflect cross-linking.
• Beneficiated polypyrrolidone fibers having gel content above about 80 percent and characterized by improved resistance to fibrillation under Wet abrasive c0nditions produced by the process of subjecting polypyrrolidone fibers to the action of formaldehyde in the presence of an acidic methylolation catalyst under non-solubilizing conditions and removing water to effect cross-linking.

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• Engineering & Computer Science (AREA)
• Textile Engineering (AREA)
• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Treatments For Attaching Organic Compounds To Fibrous Goods (AREA)

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Cited By (3)

Citations (4)

• 0
  • NL NL301142D patent/NL301142A/xx unknown
• 1962
  • 1962-12-21 US US246326A patent/US3318658A/en not_active Expired - Lifetime
• 1963
  • 1963-11-07 GB GB44029/63A patent/GB1069644A/en not_active Expired
  • 1963-12-21 FR FR958086A patent/FR1391003A/fr not_active Expired

Patent Citations (4)

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