US2935426A - Treating synthetic fibers with acetylenic glycols - Google Patents

Description

TREATING SYNTHETIC FIBERS wrrn ACETYL- ENIC GLYCOLS ,Thomas C. Spence, Yorktown, Va., and Stanley A. Murdock, Concord, Califl, assignors to The Dow Chemi= cal Company, Midland, Micln, a corporation of Delaware No Drawing. Application April 16, 1958 Serial No. 728,787

12 Claims. (Cl. 117-1383) The present invention contributes to the man-made synthetic textile fiber art. It has reference to improvements in the manufacture of certain varieties of fibers of the type that are based essentially upon acrylonitrile polymers and which are wet spun in and with aqueous saline systems to form intermediate aquagel filamentary structures which, in the final stages of manufacture, are irreversibly dried to provide the desired, characteristically hydrophobic textile fiber product. The present invention relates more particularly to the treatment of such aquagels with specific varieties of opening agents to prevent filamentary bonding, sticking and adhesion during their drying from the highly hydrated aquagel state to their finished textile fiber form.

In the wet spinning of acrylonitrile polymer fibers, it is usually convenient and expedient to form the fibers in continuous or endless filamentary lengths that are assembled in contiguous relationship during their manufacture as multiple filament strands or gatherings. Quite frequently, the filaments are handled during and subsequent to spinning in. multiple filament arrays or arrangements in which a considerable plurality of individual, component continuous filaments are in closely associated, substantially or ostensibly parallel relationship. Such tow bundles or like assemblages may oftentimes be of considerable magnitude. It is not unusual, for example, in the manufacture of, say, 1 to denier products, to

encounter tow bundles that are comprised of from 10,000 or 50,000 to 200,000 or more individual component endless or continuous filaments.

.One of the serious problems encountered when aquagel fibers are being processed in the indicated manner is the tendency of individual filaments to adhere or stick to one another. Such behavior causes coarse, bonded ribbons to be formed which have many undesirable characteristics and which introduce many disadvantages. welded to one another generally suffer from a'hard hand, lumpy feel, stiffness, lack of luster and other deficiencies tending to cause their quality as textile products to be other than premium.

A major cause of fiber sticking inaquagel filaments is thought to be the high surface tension that existsbetween the wet surfaces of adjacent filaments. Such surface tension exerts a considerable bonding force between adjacent fibers. Other causes which contribute to sticking of aquagel filaments are. the particular chemical.

stage processing of the material which would not occur.

in its handling in a dried condition. A

:Problems of interfilamentary sticking and bonding commonly occur in spinning, washing and. stretching operations during the manufacture of various synthetic fibers produced by diverse wet spinning techniques. Many additives, usually referred to and known as being opening agents, have been employed to prevent the adhesion of individual filaments during processing. In the usual early stages of spinning, washing and stretching, the typical opening agent additives that have been utilized are oil emulsions or surface active materials, or both, which are effective to a greater or lesser extent to prevent interfilamentary welding during fiber to fiber I contact in the processing. Agents of this general .variety are also sometimes referred to as lubricants.

In the manufacture of wet spun acrylonitrile polymer fibers by the referred-to aquagel process in which aqueous saline solvents are employed, the problems of interfilament adhesion in spinning and stretching stages are not of particular consequence and, prior to final washing before drying of the aquagel yarn, can be handled quite nicely in the conventional manner. With such filaments, however, the sticking and interfilament bonding problem is severe and exceptionally serious during the hot air drying of intermediate aquagel product to the finally obtained, irreversibly dried, hydrophobic yarn structure.

It would be of considerable advantage to provide opening agents which would be satisfactorily effective to prevent interfilamentary bonding and sticking together of individual yarn strands during the irreversibly-drying.

in hot air of acrylonitrile polymer aquagel fibers.

Therefore, it is the. principal object of the present in? vention to provide new and improved opening agents? for acrylonitrile polymer aquagel fibers effective upon and for the irreversible drying of such aquagel structures to a characteristically hydrophobic, synthetic tex-' of the'present invention, will be manifest in the following description and specification.

. The present invention relatesto a significant improvement in the process of irreversibly drying an acrylonitrile polymer aquagel fiber, or an aquagel structure based essentially on an acrylonitrile polymer (particularly polyacrylonitrile), to the. finally dried, characteristically hydrophobic, synthetic textile fiber form desired. According'to the invention, the improvement consists ofimpregnating a wet spun and washed and, advantageously, stretched (i.e., at least partially, if not completely, oriented) acrylonitrile polymer aquagel fiber prior to its final irreversible drying in hot air with an aqueous solution of a chemical opening agent which consists of a compound, ormixture of compounds, from the class of ditertiary acetylenic glycols characterized in having any of the general structures:

wherein each R is independently an alkyl radical containing from 1 to about 4 carbon atoms; and each Y is independently a cyclizing linear polymethylene unit of from 4 to carbon atoms (i.e., tetramethylene or pentamethylene) which, together with the completing carbon atom to which it is biterminally afi'ixed, forms an alicyclic ring system containing a total of 5-6 carbon atoms. Advantageously, the acetylenic glycol that is employed is 4,7-dimethyl-5-decyne-4,7-diol (commercially available from the Air Reduction Chemical Company as Surfynol 102) wherein, in Formula I, each R is n-propyl. Other beneficial acetylenic glycols that may be utilized in the practice of the present invention are the typical species set forth in the following Table I.

Chemical structures:

Key R Proper Name 1 Methyl 2,5-dimethyl-3-hexyne-2,S-dlol.

2 Ethyl 3,t}dimethyl-e-octyne-b,fi-diol.

3 N-propyl 4,7-dimethyl-5-decyne-4,7-diol.

4 lsobutyl 2,4,7,9-tetrarnethyl-5-decyne-4,I-diol. 5 See Structure below 1,1-ethynylene-dicyclohexenol.

NOTE (8.) of the structure:

In general, the acetylenic glycols are very soluble in acetone, carbon tetrachloride, ethylene glycol, ethyl acetate, methyl ethyl ketone and the like; moderately soluble in benzene, cyclohexanone, ethanol, diethylene glycol, petroleum ether and the like; slightly soluble in kerosene; and insoluble in such solvents as mineral oil, soya bean oil and the like. The opening agents utilized in the practice of the present invention generally produce aqueous solutions or suspensions having surface tensions of less than about 50 dynes per square centimeter; are suificiently water-insoluble to permit their presence as incompatible oils with the fiber after the initial stages of drying (wherein a major part of the water present is removed) and during the critical finishing drying stage, wherein the majority of sticking and interfilamentary bonding occurs; impart a non-adhesive film to the surface of the acrylonitrile polymer fiber that is treated (even when nitrile alloy fibers are involved, i.e., of the type containing polyvinyllactam adjuvants or other watersoluble or, at least, hydrophilic polymeric ingredients as dye-assistants); and are capable of being efl'iciently and effectively removed near the end of the drying under the indicated conditions so as to eliminate the possibility of their chemical reaction with the fiber base and to avoid other undesirable consequences. Such features and characteristics secure for the acetylenic glycols the capability of being quite advantageously utilized as fugitive opening agents in the practice and for the purposes of the present invention. They possibilitate a most satisfactory and beneficial effect.

The acetylenic glycol opening agents of the present invention are applied to the intermediate aquagel 'fiber (0r tow bundles thereof) which has been prepared by wet spinning techniques using aqueous saline solutions to prepare the polymer dissolving spinning solutions as well as the coagulating baths therefor. The opening agent is applied after the aquagel has been washed completely or substantially completely from residual salt and, either concurrently with or subsequent to hot stretching for purposes of orientation of the aquagel fiber product. it is generally most convenient to apply the agent after stretch orientation and to make the application from a flushing bath, wherein the residual moisture or water content in the aquagel fiber is replaced by the applicating solution or dispersion of the acetylenic glycol opening agent. 01": course, as has been indicated, it is most expedient to employ the opening agent on the aquagel fibers in tow bundle form.

Thus, for purposes of further particnlarization, the opening agents of the present invention are applied to strandular, filamentary and the like aquagel structural forms of fiber-forming polymers that are based upon acrylonitrile. These hydrated forms of the polymer, as is well known, may be obtained by extruding a spinning solution of the polymer into an aqueous coagulating bath wherein the spinning solvent in the extruded filamentary structure is replaced to a large extent with water. Such water swollen or hydrated filamentary structures, as has been indicated in the foregoing, can advantageously be prepared by extruding solutions or other spinnable dispersions of the fiber-forming acrylonitrile polymers in polyacrylonitrile-dissolving aqueous saline solvents into aqueous, non-polymer-dissolving coagulating spin bath solutions of the same salt or salts as used in the spinning solution. Advantageously, zinc chloride or its saline equivalents for such purpose are utilized, including such salts as calcium and other thiocyanatcs (as disclosed in US. Patents Nos. 2,140,921 and 2,425,- 192), lithium bromide, salts of the so-called lyotropic" series (as disclosed in US. Patents Nos. 2,648,592; 2,648,593; 2,648,646; 2,648,648, and 2,648,649), and saline equivalents thereof. Although it is desirable for the amount of water that is in the aquagel to at least gravimetrically equal the hydrated polymer that is contained therein, it may oftentimes be preferable for the water to polymer weight ratio in the aquagel to be in the neighborhood of from about 1.5:1 to 2.0:1, respectively. Aquagel structures in which the water to polymer ratio is as high as 2.5 or 3:1 and higher may also be satisfactorily employed.

The aquagel fibers that are treated with the acetylenic glycol opening agents in the practice of the present invention which are based essentially on fiber-forming acrylonitrile polymers may be the usual homopolymer or copolymer compositions containing in the polymer molecule at least about percent by weight of acrylonitrile that are adapted to provide the variety of filamentary products that are conveniently referred to as being acrylic fibers. Or, the basic acrylonitrile polymer composition may contain or have other beneficial. additament ingredients incorporated or combined therein. These may be the typical pigments, delusterants, textile assistants and the like (including antistatic agents) or they may be dye-assisting adjuvant materials. Thus, minor proportions (generally less than about 20 percent and frequently between about 1 and 15 percent, of the dry weight of the fiber) of certain dye-receptive polymers may be incorporated in a polyacrylonitrile or other acrylonitrile polymer aquagel fiber that is treated in accordance with the present invention. The dyereceptive polymers may be vinyl lactam polymers, including poly-N-vinyl-2-pyrrolidone, poly-N-vinyl-Z-caprolactam, and the like; N-vinyl-2-oxazolidinone polymers, in-

cluding poly-N-vinyl-Z-oxazolidinone, poly-N-vinyl-S- methyl-Z-oxazolidinone and the like; poly-N-vinyl-3 ZQQSAQQ inorpholinone and the like; and more or less equivalent polymeric dye-assistant adjuvants. The dye-assisting adjuvant materials of nitrile alloy type fibers may also be present in the essential acrylonitrile polymer base in the form of graft or block copolymerized units of such polymers upon an already formed acrylonitrile polymer base or, alternatively, polymeric products in which the essential acrylonitrile polymer base is graft or block copolymerized on an already formed dye-assisting adjuvant polymer backbone. It is generally preferred, for purposes of terminological classification, to characterize the latter, highly advantageous variety of dye-receptive fibers as being nitrile alloy fibers in order to clearly distinguish them from the conventional, prototype, socalled acrylic fibers that were first known to the art. The applicating bath of the acetylenic glycol opening agent may be either a water solution or colloidal suspension thereof containing from about 0.1 to 1.3 percent, and preferably at least about 0.4 percent, of dispersed active agent. It is generally desirable for the acetylenic glycol opening agents to be formulated in the applicating compositions thereof as saturated solutions, i.e., in aqueous dispersions wherein their concentration is not in excess of that at which they form true solutions or colloidal suspensions. Such manner of employment beneficially avoids the deposition of large oily particles on the aquagel fibers being treated, which might tend to produce non-uniform effects in the treatment. Advantageously, the bath imparts between about 0.75 to 2.5 percent by weight on the Weight of the dry fiber (o.w.f.) of the opening agent on the aquagel fiber. While it is advantageous to apply the opening agent from an impregnating bath, suitable results may also be achieved by spraying, rolling or wiping (as with wick applicators) the applicating solution of the opening agent on the aquagel fibers being treated.

It is generally advantageous to apply the opening agents to the aquagel fibers or tow bundles thereof prior to any wet-crimping operation that may be contemplated for the fibers, if and when such operation is included in the processing sequence. Following the application of the opening agent, the aquagel fibers are irreversibly dried, to provide the desired, characteristically hydrophobic, synthetic textile fiber product. Drying is best accomplished in and with hot air at temperatures between about 100 and 150 C. for periods of time between about 30 and minutes. Fibers treated and dried in accordance with the present invention may generally be obtained in excellent finished form. They have substantially, if not completely, reduced occurrence of undesired sticking and interfilamentary bonding and are in a condition wherein the optimum properties of the fiber product is brought out to best advantage.

One peculiar and distinctively beneficial advantage of the acetylenic glycol opening agents that are, employed in the practice of the present invention lies in their ability to be successfully and satisfactorily recovered for re-use after their application in the process. As is evident in the foregoing, the aquagel tow bundle entering the dryingoven or chamber can be shown to contain the agent. However, the irreversibly dried fiber product leaving the drying area contains none or vanishingly smalland insignificant quantities of the agent. This is experienced despite the fact that successful opening action has been accomplished and the agent has operated in the desired manner during the drying step. It is believed that the agent is removed from the aquagel structure being dried by means of steam distillation. Thus, recovery of the condensate and re-use of the agent is an attractive feature of the present invention. Of at least as great importance is the fact that, due to the fugitive and nonresidual character of the acetylenic glycol opening agents, they are absent from the finally dried fiber, thus avoid ing any possibility for interfering with subsequent processing operations and normal usage of the textile proda net. -In'-this way, fibers preparedfollowing' the practice of the present invention experience no decrease in heat or light stability, luster or dyeability. They have a completely dry and non-oily hand, and are not subject to being tacky or otherwise altered due to the presence of residual opening agent on their surfaces.

' The invention is further illustrated in and by the following examples wherein, unless otherwise indicated, all parts and percentages are to be taken by weight.

Example 1 A polyacrylonitrile spinning solution was prepared by dissolving about one part of a fiber-forming species of the polymer having an average molecular weight between about 30 and 35 thousand in about 10 parts ofa percent aqueous solution of zinc chloride. The "spinning solution had a viscosity of about 2200 poises at a temperature of about 25 C. It was extruded at about 30 C. through a spinnerette system into about 15 thousand separate, individual aquagel filaments. The diameter of each jet hole through which each individual 'filament was extruded was about 6 mils. The extruded spinning solution was coagulated in a coagulating liquid comprised of about a 43 percent aqueous solution of zinc chloride at 15 C. The aquagel filaments were withdrawn from the coagulating liquid and assembled in the form of a relatively flat, ribbon-like, multiple filament tow bundle. The wet spun tow was then passed into a water wash bath, wherein it was washed to the point at which the zinc chloride content was not in excess of about 0.05 percent. The washed tow was then oriented by being stretched to a total length of about 12 times its original length. By these operations there was obtained a washed and oriented filamentary tow bundle of the 15,000 individual aquagel strands. The total aquagel denier of the washed and oriented tow bundle was about 100,000. The tow bundle had an average width of about one inch and an average thickness of about 20 thousandths of an inch. The oriented aquagel structures contained about 2.0 parts of water for each partof fiberforming polya crylonitrile that was present therein. In addition, the aquagel contained about 8 percent of poly- N-vinyl-2-pyrrolidone (PVP) (based on the dry weight fiber) that had been incorporated therein as a polymeric dye-assisting adjuvant by impregnation of the watersoluble polymer (from an impregnating bath in which it was contained in aqueous solution) into the aquagel structure.

. The washed and oriented tow was then passed in a.

relaxed state onto a continuous belt drier and driedin hot air at 150" C. for about 15 minutes to achieve the irreversible drying and convert the aquagel to the final,

' 3 denier per filament, characteristically hydrophobic,

synthetic textile fiber structure. The tow bundle was then tested by a standard method of analysis to determine the. number of sticks per gram in the finally obtained product. The analysis method employed is one common and well known to the art, wherein a card web of the, fiber is observed in order to count neps or blemishes therein. A segment of carded web fiber is visually examined after a specified number of passes through a sample card. Sticks per gram are an expression of the number of bonded fibers 'counted on a standard sample. Two passes through the sample card arefound to approximate the standard cotton carding operation performed'on a production scale. The sticks observed after such treatment provide an accurate picture orrepresentation of the frequency or number of bonded fibers present. The change in sticks or number of bonded fibers present after four passes of the fiber sample through a sample card give a measure of the severity of bonding. It should benoted, incidentally, that there is no sig-"' nificant dilference in the test method between measures of say, 0 and 4 sticks per gram. Such values are 'essen-.--

tially the same within the accuracy of the examination procedure used. The untreated tow bundle was found to have been prepared with about 280 sticks per gram after the second pass over the card web and with about 38 sticks per gram after the four passes over the sample card.

In contrast with the foregoing, the spinning and drying procedure was repeated on three additional tow bundle samples excepting that, immediately prior to drying the washed and stretched tow bundles, they were passed through an aqueous applicating solution of an acetylenic glycol opening agent in accordance with the practice of the present invention at room temperature with a two second residence (immersion) time of each tow bundle sample in the bath. Each of the treating baths employed had a different concentration of the opening agent therein. The treated tow bundle was not rinsed prior to drying. The acetylenic glycol employed was 4,7-dimethyl--decyne-4,7-diol (Surfynol 102). The results are set forth in the following tabulation, wherein the untreated control sample (sample A) referred to in the foregoing is included for comparative purposes and the quantity of the acetylenic glycol employed in the separate treating baths for each of the treated samples B, C and D is also indicated.

By way of additional contrast with the foregoing, an aquagel 3 denier per filament tow bundle prepared in the same way as above described was dried in a completely relaxed state and without opening agent treatment to obtain the final synthetic fiber structure. The procedure was duplicated excepting to soak an identical wet tow in a 0.4 percent aqueous solution of Surfynol 102. After drying, each tow bundle was dipped into a 1 percent solution of Emulphor EL-719 (a synthetic detergent consisting of a nonionic acyl (fatty) polyoxyethylene glycol supplied by General Aniline & Film Corporation), squeezed, and again dried for 10 minutes in a 150 C. oven. The Emulphor is a standard finishing agent used for antistatic and lubricating purposes for the finally dried product. It is not an opening agent. The product treated with opening agent had 219 sticks per gram. The untreated tow, by way of comparison, was found to contain about 389 sticks per gram.

The same results were obtained when the foregoing procedure was identically duplicated excepting to omit application of the Emulphor EL719 to the tow bundles.

Example 3 An aquagel tow bundle was prepared identically as in Example 1 with the major exception that no PVP was incorporated in the polyacrylonitrile fibers. The tow bundle, prior to drying, was treated with Surfynol 102 in the same way as in the first example. The dried, treated tow bundle was exceptionally open and flufiy. Its individual component filaments were distinctly individal and non-bonded. in marked contrast therewith, an identical polyacrylonitrile aquagel tow bundle that was dried without being treated in accordance with the present invention had a significantly inferior and undesirable shredded wheat" fibrous appearance and feel.

Example 4 Similar results are obtained when the foregoing is repeated excepting to use other forms and types of unmodified polyacrylonitrile or to employ unmodified acrylonitrile copolymer fibers or when using nitrile alloy fibers containing other polymeric dye-assisting adjuvants in place of the poly-N-vinyl-2-pyrrolidone, such as poly- N vinyl 2 oxazolidinone, poly N vinyl 5 methyl 2 oxazolidinone, poly N vinyl 3 morpholinonc, etc. Analogous excellent results are also obtained when using either Surfynol 82 or Surfynol 104 as the opening agent, as well as any other of the acetylenic glycols specifically illustrated in Table I or fitting within the scope of the Formulae I, II and III.

The scope and purview of the invention is to be gauged in the light of the hereto appended claims rather than strictly from the decent embodiments that have been set forth in the foregoing description and specification.

What is claimed is:

1. In the method of irreversibly drying an acrylonitrile polymer aquagel fiber to convert it to a synthetic, characteristically hydrophobic, textile fiber product, said aquagel consisting essentially of an acrylonitrile polymer that contains at least about weight percent of acrylonitrile polymerized therein, any balance being another polymerized monoethylenically unsaturated monomer that is copolymerizable with acrylonitrile, said aquagel containing between about 1 and 3 parts by weight of hydrated water to each part of dry polymer therein, the improvement which consists of applying to said aquagel fiber prior to drying between about 0.75 to 2.5 percent based on the weight of the aquagel fiber, of an acetylenic glycol opening agent selected from the class consisting of those having the structural formulae:

wherein each R is independently an alkyl radical containing from about 1 to 4 carbon atoms; and each Y is a cyclizing linear polymethylene unit which, together with the completing carbon atom to which it is aifixed, forms an alicyclic radical of from 5 to 6 carbon atoms; then irreversibly drying the aquagel in hot air at a temperature between about and C. for a period of time between about 30 and 5 minutes.

2. The method of claim 1, wherein said opening agent is applied to said aquagel fiber from an applicating aqueous bath of said agent containing between about 0.1 and I 1.3 percent by weight, based on the weight of the bath,

of said opening agent dispersed therein.

3. The method of claim 2, wherein opening agent is applied by immersing said fiber in said applicating bath.

4. The method of claim 1, wherein said aquagel fiber is treated and dried while it is assembled in tow bundle form. 1 a 1 5. The method of claim 1, wherein said aquagel fiber is a polyacrylonitrile fiber. I

6. The method of claim 1, wherein said aquagel fiber is a nitrile alloy fiber which consists essentially of a composition of (1) at least about 80 weight percent,

based on the dry weight of the composition, of an acrylonitrile polymer that contains at least about 80 weight percent of polymerized acrylonitrile therein, any balance being another polymerized monoethylenically unsaturated monomer that is copolymerizable with acrylonitrile, and (2) up to about 20 weight percent, based on the dry weight of the composition, of a polymerized dyeassisting adjuvant selected from the group consisting of polymerized N-vinyl-2-pyrrolidone, polymerized N-vinyl- 2-caprolactam, polymerized N-vinyl-Z-oxazolidinone, polymerized N vinyl 5 methyl 2 oxazolidinone and polymerized N-vinyl-3-morpholinone.

7. The method of claim 6, wherein said nitrile alloy fiber is comprised of polyacrylonitrile containing intimately blended therewith up to about 20 percent by Weight, based on the dry weight of the fiber, of poly- N-vinyl-Z-pyrrolidone as a dye-assisting adjuvant.

8. The method of claim 1, wherein said opening agent is 4,7-dimethy1-5-decyne4,7-diol.

9. The method of claim 1, wherein said opening agent is 3,6-dimethyl-4-octyne-3,6-diol.

10. The method of claim 1, wherein said opening agent is 2,4,7,9-tetramethyl-5-decyne-4,7-diol.

11. The method of claim 1, wherein said opening agent is 2,5-dimethyl-3-heXyne-2,5-diol.

12. The method of claim 1, wherein said opening agent is 1,1'-ethynylene-dicyclohexanol.

References Cited in the file of this patent UNITED STATES PATENTS

Claims (1)

1. IN THE METHOD OF IRREVERSIBLY DRYING AN ACRYLONTRILIE POLYMER AQUAGEL FIBER TO CONVERT IT TO A SYNTHETIC, CHARACTERISTICALLY HYDROPHOBIC, TEXTILE FIBER PRODUCT, SAID AQUAGEL CONSISTING ESSENTIALLY OF AN ACRYLONTITRILE POLYMER THAT CONTAINS AT LEAST ABOUT 80 WEIGHT PERCENT OF ACRYLONITRILE POLYMERZIED THEREIN, ANY BALANCE BEING ANOTHER POLYMERZIED MONOETHYLENCIALLY UNSATURATED MONOMER THAT IS COPOLYMERIZABLE WITH ACRYLONTIRILE, SAID AQUAGEL CONTAINING BETWEEN ABOUT 1 AND 3 PARTS BY WEIGHT OF HYDRATED WATER TO EACH PART OF DRY POLYMER THEREIN, THE IMPROVEMENT WHICH CONSISTS OF APPLYING TO SAID AQUAGEL FIBER PRIOR TO DRYING BETWEEN ABOUT 0.75 TO 2.5 PERCENT BASED ON THE WEIGHT OF THE AQUAGEL FIBER, OF AN ACETYLENIC GLYCOL OPENING AGENT SELECTED FROM THE CLASS CONSISTING OF THOSE HAVING THE STRUCTURAL FORMULAE: