US2653112A

US2653112A - Heat stabilized cellulose yarn

Info

Publication number: US2653112A
Application number: US779208A
Authority: US
Inventors: Roseveare William Earl
Original assignee: EI Du Pont de Nemours and Co
Current assignee: EIDP Inc
Priority date: 1947-10-10
Filing date: 1947-10-10
Publication date: 1953-09-22
Anticipated expiration: 1970-09-22

Description

Patented Sept. 22, 1955 HEAT STABILIZED CELLULOSE YARN William Earl Roseveare, Richmond, Va., assignpr to E. I. du Pont de Nemours & Company, Wilmington, Del., a corporation of Delaware No Drawing. Application October 1947,, Serial No. 779,208

3 Claims. (Cl. 11771) 1 This invention relates to organic textile structures such as yarns, threads, cords and the like, and more particularly, it relates to the treatment thereof with a material for increasing the resistance of such organic textile structures to deterioration by heat.

Certain cellulosic yarns, for example, regenerated cellulose yarns, have the disadvantageous characteristic of deteriorating to a considerable extent when subjected to elevated temperatures. While certain materials, such as urea or biuret or phenyl biguanide, have been used successfully as heat aging inhibitors, more effective agents have been desired to reduce even further the extent of deterioration in the yarns.

It is an object of the: present invention to treat cellulosic and other structures in such a manner as to increase their resistance to deteriorationv by heat.

It is another object of this invention to treat certain structures, for example, regenerated cel-' lulose yarns having high dry tenacities, in such a manner that the resultant yarns will have: an increased resistance to deterioration by heat..

It is a further object of this invention to prepare articles containing. cellulosic or other yarns, as, for example, regenerated cellulose: yarns, which articles are' suitable for' use at elevated temperatures.

Astill more specific object of the present invention is the production of. rubber goods reinforced with cellulose yarns, for example, regenerated cellulose yarns which have been treatedin such a manner as to increase their resistance by heat.

Other objects of the invention will appear hereinafter.

The objects of the invention. may be accomplished, in general, by intimately associating the structures, for example, regenerated celluloseyarns, with a readily oxid-izable metal. For purposes of this invention such a metal. isone Whichat temperatures of about 150 Ctreacts withboth air and water to form alkaline" products. products are in themselves heat-aging inhibitors. The metals preferred for use in the: process of. this invention are those which have. only one positive valence and those whose hydroxidesare no more water-soluble than'strontium: hydroxide. It has been discovered. that both: moisture and oxygen hasten heat degradation and that. when they are acting simultaneously a synergistic effect'results- This invention; then, is based upon the removal of botlr water and oxygen by reaction with: a metal; Advantageously, in the removal These of degradative materials, as oxygen and water, by the process of this invention, increased useful life of the structure results. The desired application is conducted so that the resultant structure contains an optimum amount of the particular metal being used. Other factors being equal, the degree of increased resistance to deterioration by heat of the structures thus treated will be proportional to the amount of metal with which they are impregnated, up to a certain limit.

In accordance with the present invention, it has been discovered that cellulosic and other structures, for example, regenerated cellulose threads such as viscose rayon threads, or cuprammonium rayon threads, may be stabilized against the deteriorative action of heat by im pregnation of the threads with ametal such as aluminum or magnesium. Whereas an untreated regenerated cellulose thread subjected to heat ing at C-. for a period of 4 hours in sealed tubes containing air and I2% moisture shows a loss of strength of over 50%, similar yarn when impregnated with about 0 .2 of magnesium flake shows on heating for 4 hours at 150 C. a loss of metalby' the process of this invention. These examples, wherein parts are by weight, are illustrative only and are not to be construed as limitative;

Example I A. high tenacity regenerated cellulose yarn produced by the viscose process was passed through a slurry consisting. of magnesium flake suspended in an 8% aqueous solution of polyvinyl alcohol (a 4% aqueous solution of this polymer at 20 C. has a medium viscosityo'f 24 centipoises). The suspension was maintained by stirring; After the cord was run through the slurry, it was partially dried and was then dipped into a bath containing an adhesive. The adhesive was a resorcinol-formald'ehyde-rubber latex adhesive which was predominantly rubber latex. The yarn was then dried by hot air at a temperature of 105 C. The speed of yarn travel during these operations was about 5 yards per minute. The quantity of magnesium deposited on the yarn was about 0.3%. The heat aging was conducted in all cases in sealed tubes heated to a temperature of 150 C. and maintained at that temperature for 16 hours. These conditions were employed to simulate the conditions obtaining when the structures are covered with relatively impermeable coatings which prevent the free escape of degradation products.

The cords treated with magnesium and then dipped in the adhesive bath and dried st only 14.2% of their original strength whereas dipped, untreated cords run as controls lost over 23% of their strength. As pointed out in copending application, Serial No. 717,813, new U. S. Patent No. 2,577,593, similar yarn protected with 0.22% l-phenylbiguanide lost 16% of its original strength after 16 hours at 150 C. and yarn protected with 0.25% urea and similarly heat-aged lost 62% of its strength. Thus, it is shown that the process of this invention is an effective means of stabilizing cellulosic yarns against the deteriorative action of heat.

Example II Several samples of cotton tire cord were heated L at 150 C. for 17 hours in sealed tubes containing air and about 6% moisture. After this treatment the cords possessed, on the average, only 32% of their original strengths. A similar set of samples was impregnated with an amount of magnesium powder equal to 1% of the weight of the cotton. These impregnated samples were similarly aged. The impregnated cords were found to have, on average, 47% of their original strengths. Upon comparison of the above figures, the inhibiting effect of magnesium can readily be seen. Like cotton structures those composed of polyarnides, such as polyhexamethylene adipamide, polyhexamethylene sebaceamide and the like, or polymeric esters, such as those prepared from terephthalic acid, are stabilized against degradation by heat by impregnation with magnesium as described above. Any of the metals of this invention may be used with structures composed of these non-cellulosic polymers to obtain greater heat stability.

Example III Several samples or nylon tire cord were heated at 150 C. for 16 hours in sealed tubes containing air and 3.4% moisture. After this treatment, the cords possessed on the average only 40% of their original strength. A similar set of samples was impregnated with an amount or magnesium powder equal to 1% of the weight of the nylon. These samples were similarly aged. The impregnated samples were found to have lost appreciably less than 25% of their original strength.

Example I V Skeins of yarn taken from one spool of bobbinspun, high tenacity, regenerated cellulose yarn used commercially in preparing tires were treated in the following manner: Six of the skeins were dipped in a finish comprising about 1.5% of the composition Z described below, about 0.5% polyvinyl alcohol and 98% water. The composition Z consisted of about 25 parts of sulfated peanut oil, 25 parts of a sulfated fatty acid ester such as the sulfated glyceride of oleic acid or other higher fatty acids, 17 parts of mineral oil, 17 parts of peanut oil and 17 parts of a fatty acid ester. These six skeins were not heat aged. Strengths, that is dry tenacities, were measured on these directly to obtain a representative figure for comparison to heat-aged yarns. Four skeins, referred to as lot A in the table below, were similarly dipped and then aged. An additional six skeins were treated by running the yarn through a bath containing in addition to the above finish 0.5% of aluminum flake. These aluminum containing skeins were dried at 60 C. and allowed to condition in the standard testing laboratory atmosphere. Two of the aluminum containing skeins were not heat aged (lot B) and of the aluminum containing skeins were heat aged (lot C).

Percent Strength Losses Finished, heat aged controls Aluminum impregnated, imaged Aluminum impregnated, heat-aged Magnesium impregnated, unaged Magnesium impregnated, heat-aged By comparison of the above figures it can be seen that in these experiments the magnesium containing yarns have the lowest strength losses on heat-aging. Further improvement in the use of magnesium for increasin the resistance of cellulosic yarns to deterioration of heat may be obtained by using magnesium flake of very small mesh. The magnesium flake used in the above experiment was mesh whereas the aluminum used was in the form of a fine powder. It is dimcult to obtain a proper dispersion of the magnesium in the finish when such large particles are used. Further, it can be seen that a loss in strength of 3.7% occurs merely in impregnating with magnesium whereas no loss occurs in impregnating with aluminum. It is believed that the 3.7% loss is due to abrasion of the yarn caused by the large particles of magnesium. For example, better results may be obtained by the use of magnesium in fine flake form. Further, the finer the particle size the more intimate is the contact of the inhibitors with air and moisture. Thus, for best results it is preferred to use the metals in finely divided form. Of course, the metals incorporated, will be substantially unoxidized. The magnesium, after heat-aging, looks like an ash, the magnesium particles having reacted with moisture and air to form magnesium oxide or magnesium hydroxide or magnesium carbonates. Such alkaline materials act further as inhibitors for heat aging, since they neutralize any acidic compounds present.

Similar alkaline products are formed when aluminum is used. However, aluminum does not appear to be changed as extensively as magnesium. This is to be expected since magnesium is the more reactive metal. Any common metal which becomes oxidized with comparative case at elevated temperatures, for example, about C., and which reacts with water or steam may be employed providing it or its reaction products will not react with the physical structure 'to -deteriorate it. Thus, metal other than 'magnesium and aluminum may be employed, "such as strontium or calcium. It is preferred *to use those metals whose hydroxides are not more water-soluble than strontium hydroxide. The reactiveness or alkali metals 'and barium andthe alkalinity of their hydroxides lirriits their usefulnes in this invention. Certain "other *metals, such as zin'c, cadmium, lead andtin, c'an 'form peroxides which tend to 'degrad'ecertain structures, as, for example, those of cellulose. Accordingly, it is preferred fto use those metals which do not have a variable-valence'andwhich do not form peroxides. ot-those :metals which have-only one valence,'-it is preferred-tofuse-ma nesium or-alu'minum, "thi'sjprefereiic'ebeing based upon their chemical reactivity, upon their availability and upon the inertn'ess of 'the-metaIstheir oxides and salts' toward' cellulose.

One method of application'consists of simply immersing thestruc'ture ina proper-"medium containing the metal suspended therein in proper concentration. "The medium-may also contain-a finish. The application of fini'sh is'not necessary to the heat aging inhibition effect, as shown above in Example "I, but is preferred because inter-filament lubrication is obtained which facilitates the-obtainingof proper twisting and the desired mobility of the filaments '=in the final structures. In commercial operation the -'metal may be appliedeither iinmediatelyprevious 'to or in conjunction with -'the application of a rubber .adhesive in thepreparation of-useful rubber articles. Thus, it is not necessary to employ an extra size or finish. The rubber adhesive being used in the particular commercial'operation may act as a vehicle for the metal fiake such as the magnesium flake. 'The treatment of the 'cellulosic threads withare'sin late'x 'adh'e'si've may be in the manner *of Charch -'and Maney, 3. 2,128,635 and the types of adhesives f disclosed therein or an other adhesive '-treatmeiit =may be employed in thi's invention. While theproces'sof this invention is applicable to uncoated structures, it is used chiefiy in -the preparation of coated structures. Elie coatings ma'y be -'prepared from any of thefcommercially available polymers. It is --preferred to use a coating having a lowperm'eability to' air and moisture. For the most part, such-coatings reduce the- -amount of air and moisture difiusing into the yarn' to an amount less than that which may be taken up by the inhibitors. 'Aspoint'ed out above, the process of this invention is particularly useful in the preparation oi rubber articles, employing either natural or synthetic rubbers. Other polymers which maybe used, amonga largenumber, are vinylpolymers a polyvinyl chloride, polyvinyl acetate, polyvinyl butyral, polyethylene interp'olymers of vinyl chloride-vinyl "acetate, vinyl chloride-vinyl cyanide, hydrolyzed'ethylene-vinyl acetate interpolymers, vinylidene chlorideinterpolymers, rubber hydrochloride, chlorinated rubber, etc.

In'i-mmersion processes, the-structure, such as a yarn, in a form of a single-- strand ora-"fabric,

may be passed continuouslythrough the bath so that a suitable length of the structure is immersed at any instance and so that it runs at a suitable rate or the immersion may be accomplished by simply dipping an entire structure, for example, a skein, in the solution and allowing it to remain there for a suitable period of time. If

the impregnation is by passage of a sin n of yarn through a 'bath, it is important .that this be done without the application of undue -tension to the yarn or with as little tension as is practioable in order to attain the penetration of :and hence the greatest stabilizing activity from a given amount of metal. 'Thisis accomplished by running the yarn over 'asimp'le system :of freely rotating pulleyseoas to-give a length of yarn of about 30 inches immersed at any instant and being wound up on a mechanically driven areel. The reel :is rotated'at suchazspeed that the rate of traverse of the yarn through the bath is about yards per minute and the period of immersion Iis, :therefore, about 40.5 seconds. (Dther yarn speeds ranging from 10 to 300 yards per minute may also be used. After passage through the bath, the :yarn is Iallowed to :remain on "the reel until dry. :Drying may also -Joe accomplished using ovens, contact driers or air drying means. The temperatures for "drying :may vary from about 70 C. to about- C.

If the impregnation is by .dipping 'the structure, such :as a skein or .yarn,.in a bath allat once, the structure may lbeffreed .of excessive liquor by wringing out in:a:centrifuge or. by other suitable means. -When bathlme'diumsareused, they may be unheated .or heated as desired. Methods other than immersiontproeesses may be employed. For example, the .metal :may he melted in an are or atflameeand then blown as a fine spray :onto ith'e structure many of the well known methods of applying metals to textiles. In any of the .methods,.itiis Ipreferred itO apply themetal to theifinish'ed structure to iavoidilo'sses which occurinrtwistingoperations. For-example, lit-has beentshown thatisuchilosses oiimetal ocour when the i. metal is 5. applied :to- .yarn which is rthen'twisted. The-loss of metal which occurs depends, among other factors, .upon' the degree of subdivision or'the metal usedz'andaupon the nature of thefinish, sizeor adhesive employed. Further, in any ofithe methods,ithe'concenrtration of the Imetal in ith'e bath or in the spray' is'determined by the extent to whihittisdesiredto impregnate theyarn or-cord. 'Itis apparent that one may stabilizeithe'iyarn' rtothe desireddegree by varying the amount :of metal applied to theyarn or the extentof the impregnation. Efiective results are :obtained using :concentrations of magnesium from :*about 0.2 to about 2-.0% "by weight of the yarn :or cord. For :reasons of practicality and :economy, the preferred concentration is from about 0.5 toabout 1.5%. "Similar concentrations of :aluminum flake or other metals may be used.

Although it will :generally be desired to treat the structures according i to' the immersion method described above, "other bath' ingredients may be used than those mentioned. Instead: of water as a vehicle, organic liquids "or mixtures of thesewith or without water may 'be' employed. For example, cyelo'hexa'ne, benzene, and-similar liquids maybe employed in the-immersion'baths providing these liquids permitthe formation of the desired dispersion of metal. Likewise, it-is possible to use the adhesive as a dispersing medium. *Other liquids may be-a'dded to theadhesive to give the desired fluidity. The adhesive, which is used to obtain more stable impregnations, is not essential and may be dispensed with, as, for example, in the spraying methods of impregnation. In these methods or other methods it is possible to spray the adhesive on along with, prior to or after the application of the metal,

Finishes other than composition Z mentioned above may be employed and sizing agents other than polyvinyl alcohol may be used. In general, any of the numerous, well-known cellulose finishes and sizes may be employed in the baths to obtain better adhesion of the metal to the structural material, such as cellulose, providing, of course, the compositions are not reactive toward the agents of this invention. Dispersing agents may also be incorporated in the baths to obtain stable dispersions of the metal. The particular dispersing agent may be chosen from the multitude of well-known dispersants taking into consideration the nature of the size, finish or adhesive in admixture with which the metal is to be applied. While finishes, sizes and peptizing agents are not essential to the process of this invention, they may be used frequently to obtain better uniformity of impregnation and greater adhesion. Generally, it is preferred to use a bath containing about 1.25 to about 1.75% of a finish, about 0.4 to about 0.6% of a size such as polyvinyl alcohol and about 0.4 to about 0.6% of magnesium flake. A bath of this composition when used in the process of this invention will lead to the impregnation of the structure to an extent which efiectively protects it for a considerable length of time at high temperatures without loading it excessively.

Furthermore, the process of this invention may be applied to the impregnation of thread such as viscose rayon yarn while it is still in the gel state.

The increased resistance to deterioration by heat imparted by the processes of this invention to the structures of this invention, such as cellulosic yarn or cord, makes the yarn particularly useful where it is to be subjected to elevated temperatures. Viscose rayon yarn or similar cellulosic yarns so treated to associate the metal intimately with the yarn, may be used for all purposes to which such a yarn might otherwise be put and which subject it eventually to elevated temperatures such as would more rapidly destroy the usefulness of the untreated than the treated yarn. The yarn treated according to this invention may be twisted into cord or other materials for use as reinforcement for rubber articles, including motor vehicle tires and steam hose. Such treated yarn will Withstand, far better than the untreated yarn, deterioration during the manufacture of rubber products involving such operations as vulcanization at elevated temperatures or in use where the products are subjected to elevated temperatures. Also, yarn so treated may in one form or another be Woven into fabricsfor uses at elevated temperatures, as for example, coverings for laundry mangles and as zinc oxide fume bags.

Among other uses for treated structures of this invention are automobile top materials; masks and protectors around steel furnaces and the like; fabric tubes for discharge ends of chutes for hot materials as in cement mills; bags for heating pads; strainers for hot oil and other nonaqueous materials; belt driers such as on blueprint machines; and conveyor belts for hot materials. In general, this invention may be ap- 8 plied to the manufacture of coated fabrics or similar articles which are exposed to elevated temperatures.

Whereas present cellulosic yarn, such as viscose rayon yarn, is ordinarily deteriorated on exposure to heat, the present invention makes possible the treatment of this yarn so that it possesses a marked stability under the same conditions. This is true also for structures composed of cellulose derivatives, of polyamides or polymeric esters. The use of metal such as aluminum and magnesium has the further advantage in that impregnation of organic textile struc tures will cause very little loss of the initial strength of the structures. The use of these metals is furthermore advantageous in that the protective chemical reactions they induce do not occur extensively at low or room temperatures. That is, the metals are retained for use at the high temperatures at which they are needed, no loss of metal or protective action occurring because at consumption of the protecting agent at lower temperatures. Even if the metal is converted to some extent at low temperatures, to its oxide or a salt, such as its carbonate, no loss is sustained since these alkaline products are effective heat age inhibitors. The metal, heat-aging inhibitors of this invention are further advantageous in that they are relatively inexpensive materials and very readily obtainable.

Since it is obvious that many changes and modifications may be made in the above described details without departing from th nature and spirit of the invention, it is understood that this invention is not limited except as set forth in the appended claims.

I claim:

1. A heat stabilized article comprising a yarn produced from regenerated cellulose impregnated with about 0.2% to about 2.0% of fine particles of a metal selected from the group consisting of aluminum and magnesium, said impregnated yarn being coated with a rubber.

2. A heat stabilized article comprising a yarn produced from regenerated cellulose impregnated with about 0.2% to about 2.0% of fine particles of magnesium, said impregnated yarn being coated with a synthetic rubber.

3. A heat stabilized article comprising a yarn produced from regenerated cellulose impregnated with about 0.2% to about 2.0% of fine particles of magnesium, said impregnated yarn being coated with a natural rubber.

WILLIAM EARL ROSEVEARE.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,184,015 Price May 23, 1916 1,825,252 Taylor Sept. 29, 1931 2,034,008 Taylor Mar. 17, 1936 2,227,843 Quenelle Jan. 7, 1941 FOREIGN PATENTS Number Country Date 432,019 Great Britain July 15, 1935

Claims

1. A HEAT STABILIZED ARTICLE COMPRISING A YARN PRODUCED FROM REGENERATED CELLULOSE IMPREGNATED WITH ABOUT 0.2% TO ABOUT 2.0% OF FINE PARTICLES OF A METAL SELECTED FROM THE GROUP CONSISTING OF ALUMINUM AND MAGNESTIUM, SAID IMPREGNATED YARN BEING COATED WITH A RUBBER.