US2895287A - Production of bulky resin spun rayon yarn - Google Patents

Description

July 21,

1959 HYUNGDUK YOO 2,895,287

PRODUCTION OF BULKY RESIN SPUN RAYON YARN Filed Sept. 21, 1956 RESIN-SPUN RAYON SUPER-TWISTING (SPOOL) TREAT' WITH HOT FORMALDEHYDE AND ACIDIC CATALYST CENTRIFUGING DRYING CURING sPooL l DETWISTING TO ZERO BULKY YARN Un d States Patent PRODUCTION OF BULKY RESIN SPUN RAYON YARN Hyungduk Yoo, Swarthmore, Pa., assignor to American Viscose Corporation, Philadelphia, Pa., a corporation of Delaware Application September 21, 1956, Serial No. 611,216

14 Claims. (Cl. 57-164) The present invention is directed toward a process for the preparation of bulky yarn. More specifically it is directed to a process for making a laundry-resistant bulky rayon yarn by treating yarn chemically along with mechanical twisting and detwisting.

It is known in the prior art that thermoplastic yarns such as nylon may be given a fairly permanent crimp by heating highly twisted yarn, preferably in the presence of steam, to set the twist, followed by untwisting. The resulting yarn has a strongly curled or crimped wooly appearance (see US. 2,290,253 and 2,564,245). The prior art describes a process wherein a rayon yarn is impregnated with formaldehyde, twisted, cured, and detwisted to produce a wooly yarn. In a modification of this process a rayon yarn is given a supertwist, moistened to set the twist, untwisted to produce a wool-like yarn, and then treated with formaldehyde in the presence of an acidic catalyst followed by thermal curing. Both processes however require reacting the cellulosic yarn with formaldehyde under strongly acidic conditions which cause severe damage to the fiber structure through depolymerization and hydrolysis of the cellulose, as well as causing excessive cross-linking, with resulting embrittlement of the fiber and reduced extensibility. In addition such yarns are diificult to dye after this treatment due to resinification of the surface. A process has been needed which will preserve the residual yarn properties of the fiber while at the same time effecting the desired cross-linking.

Accordingly it is an object of the present invention to prepare a cross-linked cellulosic fiber by means which will avoid the degradation of the fiber which accompanies conventional methods of formaldehyde treatment. A further object is the provision of means for producing a bulky cellulosic yarn which can be more rapidly crosslinked by conventional means than plain viscose rayon and will have a lower water retention and a correspondingly greater dimensional stability when wet. A further object is the provision of a process of the foregoing type which will avoid the dyeing difiiculties mentioned above.

These objects are achieved according to the present invention by supertwisting a resin spun rayon yarn, setting the twist therein by treating the supertwisted yarn with hot liquid formaldehyde in the presence of a mildly acidic catalyst, then drying and curing to effect crosslinkage between the formaldehyde, resin, and the cellulose, followed by detwisting, this process being illustrated diagrammatically by the drawing. The resulting.

yarn is very fluffy and crimped due to retention of some of the twist and it retains the twistwhen immersed in water. It has been established that the aforesaid treatment etfects a three-way cross-linkage between the resin, the cellulose, and the formaldehyde with a correspondingly stronger bond than the conventional two-way linkage between rayon and formaldehyde. 'This in turn gives the formaldehyde-treated fiber an unusually low water retention property and the ability to retain its flutfy and bulkystructure when immersed in water. It is also evi- A" Patented July 21, 1959 I, dent that it requires less time to effect the same amount "of cross-linkage between the formaldehyde and the two fiber components as compared to that required to effect a conventional two-way bond. This means a shorter time of exposure of the fiber to the acid reaction environment and correspondingly less of the fiber degradation porating a suitable linear polymer into the viscose formed, I

the filaments are spun, followed by reacting the spun-in polymer with formaldehyde While the yarn is in highly twisted form and then-bringing the reaction product toheat-hardened, insoluble condition in and on the fiber.

The composition of the resins must satisfy the require-' ments of linearity and proper degree of polymerization as those parameters determine their behavior. Withthis. combination the resin loss to the spin bath can be kept low and the swelling of the fibers can be reduced. In addition they must also contain the necessary functional groups: to make them soluble in the viscose solution, without causing undesirable reactions. Furthermore, they must' lead to a desired modification of the fiber properties such as reduced swelling without embrittlement, i.e., without undue reduction in extensibility.

The polymers or resins which fulfill these conditions: I

are limited in number and so far'as presently known are limited to three types. The first of these is polyacrylamide or a substituted derivative thereof, the second is a poly (ureidoalkyl vinyl ether), the third is a poly(viny1oxyalkyl: alkylene urea).

These reactive linear polymers are long-chain linearsubstances and although they are water-dispersible at the time they are added to the viscose, and are added in the form of their water dispersions, there is no scumming,

of the bath or other evidence that they are leached out during spinning or aftertreating. Also, analysis for nitrogen on the final articles comprising the fully reacted con-- densate shows that the resin is retained. This is apparent-- restricted class of related compounds which may be de-.

fined in more technical fashion as follows: a monoamide, having a single unsaturated carbon to carbon bond, of an acid of the group consisting of acrylic acid and alphaalkylor beta-alkyl-substituted alpha-methylene monocarboxylic acids, and N-alkyl substituted derivatives thereof, the alkyl substituents consisting of methyl or ethyl, the amidehaving only a single carbonyl group attached to the N atom, and at least one hydrogen atom attached to the N atom. These amides have the general consisting of hydrogen, methyL-and ethyl.

1 3. rn; mq araid. Palmer? polyme o monoamide is intended to be generic to homopolymers and copolymers of the compounds just defined, whether they arev produced 1 directly...by. polymerization or copolymerization or indirectlybyhydrolysis, saponificatiomon other reaction upon a-previously. produced polymer or, copolymer. When copolymers. are used, the monomeric unit other than thatcontaining the amide group;may be:

considered to be-derivedfrom any other ethylenically; unsaturated monomer, such as vinyl acetate, vinylohloa, ride, vinyl alcohol, acrylicacid, acrylonitrile, methacrylic acid, methacrylonitrile, vinylidene chloride, ethylene, etc., v The spinning technology .o f thi s,. class of polymers is discussed further in relatedapplica or. mixtures thereof.

qn S i .No- .243,. filed an arv' 2n1952r me assignee.

Tllinina q e ec nd g o p of p y e smp y d in. this, invention, the .term ureidoalkyl vinyl ether, polymer on -polymeric ureidoalkylether; as hereafter used means homopolymers and copol yrr ers of the formula whereC H represents an alkylene group of; two toeighteen-carbon atoms, and R is a hydrocarbongroup, especially-an alkylgroup of'not overfourcarbonatoms, a benzyl, a phenyl, a cycloalkyl, or an alkenyl group, or hydrogen. The preferred memberof this. groupis the homopolymer ofCH =CHOCH CH NHCONH hereafterreferred to as poly UEVE.

Asuseful unsaturated compounds for forming the.c0-- polymers there may be used acrylic acid, methacrylic, acid, estersof acrylic acid or methacrylic acid and monohydric alcohols such as methyl, ethyl, butyl, octyl,.dodecyl, cyclohexyl, allyl, methallyl, undecenyl, cyanoethyl, aminoethyl, and the like; esters ofitaconic acid and; simi laralcohols; esters from maleic, fum aric or citraconic acids, and likewise similar alcohols; vinyl esters'of carboxyliciacids such as acetic, propionic butyric, and the like; vinyloxyalkyl esters suchas.vinyloxyethyl.acetate,

etc.; vinyl ethers such asethyl vinyl ether, butyl vinyl ether, octyl vinyl ether, allyl vinylether, hydroxyethyl. vinyl ether, aminoethyl vinylether, aminopropyl vinylv ether, dimethylaminoethyl vinyl ether, vinyloxyethoxyethanol, vinyloxypropoxyethanol; methacrylonitrile or, acrylonitrile; acrylamide, or methacrylamide, and N-sub:L stituted amidesof these types; vinyl chloride, vinyl bro: mide, vinylidenechloride, l-chloro-l-fiuoroethylene, or

ethylene; 1'-acetoxy-1,3-butadiene; styrene, 2-vinylpyridine, 4-vinylpyridine, or divinylbenzene; ethylene diacrylate or dimethacrylate, bis(vinoxyethyl)urea, vinoxyethyl acrylate, vinoxypropyl acrylate,--etc.

The spinning of this class of polymers with viscose is discussed further in related application Serial No. 606,781, filed August 28, 1956,, same assignee.

4 h r sv mposed. of earpo yme st f. vinyloxy ky alkyleneurea, and have the formula A CH:=CHOZN/ \NH X wherein X is selected from the class consisting of oxygen and sulfur, A is an alkylene group of two to three carbon atoms at least two of which occur between the nitrogen atoms, and Z is an alkylene chain of not over 18 carbons, of which at least two carbon atoms are between oxygen and ,nitrogen;- the ,latter. chainmmay besubstitutedby phenyl, alicyclic, vinyl, or alkyl radicals. The preparation of these polymers is 'described'in' US. 2,727,019. After regenerating the cellulose by extrusion of the solution into an aqueous coagulating bath, the regenerated cellulose is treated withtormaldehyde and heateduo cross-link the polymer chains.

Examples of the polymers ofthisgroup are-the homopolymers of 2-(2-ketoimidazolidy'l) ethyl 'vinyl ether,- 1- (2-vinyloxyethyl)-2-hexahydropyrimidone, 1- (2 vinyloxypropyl)-2 irnidazolidone,' 1-(2-phenyl 2 vinylo'xyethyl)-2-'imidazolidone, 1-(3-vinyloxypropyl 2 hexahy dropyrimidone, 1-(2-cyclohexyl 2-vinyloxyethyl )-2 imidazolidone, 1-(2'-cyclohexyl-2-vinyloxyethyl-)"-2 thioimidazolidone, 1-(2-vinyl-2-vinyloxyethyl) -2-imidazolid0'ne, I

l-(4-vinyloxycyclbhexyl)-2-imidazolidone, N (vinyloxyg ethyl) -2-thioimidazolidone, etc. A- preferred member of this group is poly (vinyloxyethylethyleneurea)', the mone 1 omer-of which' has the formula.

H 0H,- CH, CHFC-O-CHr-CH2-N NHL.

w ichv ispolymerizable with a free 1 radical catalyst l-canr;

be readily prepared. Typical vinylidene compounds include acrylic acid, methacrylic acid, acrylamide, meth-. acrylamide, N-substituted acrylamide and methacrylamide, such as the N-methyl or N-benzyl amides, esters of acrylic or methacrylic acid, such as the methyl, ethyl,

butyl, amyl, octyl, dodecyl, octadecyl, methoxyethyl,. phenoxyethyl, ethoxyethyl, cyclohexyl, benzyl, tetrahy--. drofurfuryl, oleyl, andnitroethyl, alkyl itaconates, vinylesters, suchas the acetate, propionate, butyrate, and laurate, vinyl-ethers other than those of thisinvention,

allylesters, such as the acetate and butyrate, styrene,

methylstyrenes, and vinylpyridine, as typicalexamples-of. monovinylidene compounds which form soluble copoly,

mers. Polyvinylidene compounds can. also. be used as comonomers, such as allyl acrylate, vinyloxyethyl acrylate, ethylene diacrylate, or the comparable methacrylate, divinylben zene, diallyl phthalate, etc. These lead to cross elinkingand insolubilizing of theinterpolymers an eflectwhieh is sometimes-desired EXAMPLE I An aqueous dispersion of a reactive polyacrylamide' (i.e., polymeric acrylamide containing free amido groups) was mixed with viscosecontaining 7% cellulose, 7% sodium hydroxide, 37% CS and aged to a sodium chloride salt test value of 4.7. The amount of theaqueous solution added .to the viscose was such that the.viscose contained 10%. of thepolyacrylamide based on the cel-I lulose, The mixture wasspun into an aqueous coagulate ing and regenerating bath containing 10% sulfuric acid 4.5% .zinc sulfate, and.24-% sodium sulfate at about 45 C. Theffilarnents .thus formed .were. given a 13-inch assess? immersion in the bath, withdrawn, and stretched 40% between godets to produce a 150 denier, 40 filament yarn which was box spun, and the cake processed by the following steps: washed acid free, treated with a desulfiding solution comprising a weak solution of sodium sulfide and sodium carbonate, and then treated successively with a water rinse, a bleach, an acid, an antichlor (sodium thiosulfate), and a water wash.

A skein of the finished yarn of 150/40 denier (3% denier per filament) was given a twist of 55 t.p.i. (turns per inch) and wound on a spool under tension. In this form it was soaked for 20 minutes at 84 C. in a water solution of formaldehyde, 3.6% methanol, and 0.3% of a catalyst comprising the reaction product of 1.0 mole HCl, 0.9 mole monoethanolamine, and 2.0 moles formaldehyde (percentages are .by-weight based on total solution). The pH of the soaking bath was 3.5. The impregnated yarn was then dried for 25 minutes at 75 C., cured for 35 minutes at 150 (2., and

detwisted 57 t.p.i. The resulting yarn is strongly crimped and wool-like, and this eifect is substantially fast to washing. In addition, its swelling capacity in water is reduced compared to that of plain viscose yarn.

A sample of this yarn was then compared. with a sample of Viscose Helanca to determine the relative percent fixed formaldehyde in the two yarns. Results are given in Table I.

Table I Percent HCHO Bulky Yarn Sample 151; run 2d run PAA resin spun 0. 74 V 0. 70 Helanca 1 0. 66 0. 65

1 Viscose Helanca is made by supertwisting a 400 denier bright rayon yarn, then treating it with a urea-tormaldehyde resin, curing, and detwisting.

EXAMPLE II yarn from the bath, stretched 35%, and collected as a cake in a conventional boxspinning'unit. The cake was doffed and cabinetted for 24 hours at 90% relative hu- Inidity and a temperature of 33 C. to efiect complete regeneration of the cellulose therein. A skein prepared from the cake was then washed acid free, treated with a desulfiding solution comprising a weak solution of sodium sulfide and sodium carbonate, and then treated successively with a waterrinse, a bleach, an acid, an antichlor (sodium thiosulfate), and a water wash.

A skein of the finished yarn of 150/40 denier (3% denier per filament) was then given a twist of t.p.i. (turns per inch) and wound on a spool under tension.

In this form it was soaked for 20 minutes at 84 C.

in a water solution of 10% formaldehyde, 3.6% methanol, and 0.3% of a catalyst comprising the reaction product of 1.0 mole HCl, 0.9 mole monoethanolamine, and 2.0 moles formaldehyde. (percentages are by weight based on water). The pH of the soaking'bath was 3.5. The impregnated yarn was then dried for 25' minutes at C., .cured for 35 minutes at 150 C., and de-' twisted 57 t.p.i. The resulting yarn is strongly crimped and wool-like, and this effect is substantially fast to washing. In addition, its swelling capacity in water is reduced compared to thatof plain viscos yarn.

6.1 A sample of this detwisted yarn was compared for swelling with a sample of the polyacrylamide-spun yarn of Example I. Under the same conditions the poly' UEVE spun yarn swelled 22.5% as compared to 31.1%

for the other. When it is remembered that regular rayon yarn swells 85-90%, the remarkably low swelling of this resin-spun sample is evident.

Samples of the detwisted yarn from Examples I and II were compared for percent fixed formaldehyde, both It is believed that. the explanation for the improved crimp imparted to the fibers by the process of this in-.

vention results in large part from the fact that when the yarn is formaldehyde-treated in supertwisted form. the outer portions of the yarn are reacted to a greater extent than the portion in the interior of the yarn.

Since the individual filaments are looped in and out of the twisted fiber because of the helical pattern of the twisted yarn, any given filament in the yarn will in evitably emerge to the surface of the yarn at regular intervals and disappear into the interior of the yarn ,at intermediate intervals. Hence at regular intervals along the length of the filament it will be heavily cross-linked while in the intervening portion there will be less crosslinking. Thus, uneven periodic treatment along the length of the filament will result in a ditferential crimp withthe more rigid portions taking the interior of the loop and the less-reacted portions taking the exterior of the loop. Thus, if the degree of formaldehydetreatment were to be plotted against the length of the filament a sine curve pattern .would result. In order to demonstrate the heterogeneous fiber treatment a portion of yarn treated according to the process of Example II (poly UEVE resin spun yarn) was divided into two adjoining segments, labelled A and B, and several individual filaments in each segment were compared for swelling, and their deviation from the average was noted. The results are set out in Table III below:

Table III Percent Filament Percent Deviation Section N o. Swelling from Average Average 26.2

In the case of poly-UEVE, there are two nitrogens pet" Polyacrylamide has but-one 7. one'carb'onyl, group, leaving a" better possibility for reaction.

In general it may be said'that the'degreof supertwist varies inversely with the denier of the yarn. A range of 150400 denier would be translated into a range of about '5'-40"t.p'.i.' o'f supertwist.

While the process ofithis invention is of very practical value in impartingja permanent crimp to a continuous filament yarn and'in reducing its-water retention and wet extensibility; the process is of' even greater value with staple fibers. Dimensional stability is much more important in staple than in continuous filament. In addition the bulking is better in the case of yarn spun from stapleprepared by this process than in the case of a plain regenerated cellulose staple, because of the resin-containing staple is stifier than the other and therefore it resists packing together in the spun yarn. Thisleave s voids in the resin-containing yarn which are absent in the-ordinary-staple yarn and thereby increases its volume per unit weight accordingly. Furthermore the incorporation of the resin. in the filament improvesits crush resistance in pile fabrics both in the form of continuous filament and staple. In addition, the inclusion of the resin increases the crease resistance of flat fabrics since the fabric is less water sensitive and thereforefaster drying. The difference in dyeing properties between the resin-containing fiber and the. conventional regenerated cellulose fiber canbe put to good use in fabrics. Since the. plain cellulose fiber takes dye better than the other it is'possible to effect a plaid'pattern in a textile by alternating the number of parallel strands of resin-con taining cellulose with the. number of strands of plain cellulose and then subjecting the combination to a level dyeing operation. It shouldbe noted here that if the yarn is to be dyed this should be doneprior to twisting and formaldehyde-treating since the resinified twisted fiber is notreceptiveto dyeing. Because it is not receptive to dyeing the most practical'method of coloring is to color-spin, i.e., to add the pigment to the viscose along with the resin as the. viscose is spun.

Suitable colored inorganic pigment may be employed to obtain the desired color-or shade. For a yellow color, ochre, sienna, chrome yellow, tin bronze, etc., maybe employed. For a red color Venetial red, red lead, vermilion, etc., may be employed. For a blue color, ultramarine, Prussian blue, Milori blue, etc., may be used. For green, Guignets green verdigris, chrome green may be employed. For brown, raw umber, burnt umber or Vandyke brown may be used. To obtain metallic effects, finely divided-or colloidal metals may be employed. For shading, that is to get darker. colors, lamp black, graphite or other black pigment may be added. To obtain any other colors, the pigments may be mixed as is well understood in the paint art.

The pigment is preferably added to the dope or spinning solution containing the cellulose compound in the form of a concentrated suspension in a liquid; usuallyabout a 20%. pigment-in-water dispersion. The amount of pigment added will vary with the depth of color desired and the nature of the pigment employed and will generally be from 0.1 to of the weight of the cellulosic material present in the finished yarn. The pig:

mentis preferably in very fine form, the particles having a diameter of less than 0.1 to 5 microns for increased the strength and the-other properties'of theyarnx This fine size may be obtained by grinding theinbrganic,

colored pigment either with.water, an oil, part of the spinning solution, or the solvent used in the. spinning solution in a ball miller colloid mill.

It willbe'app'arent'frorn the foregoing that the inu. vention' provides a new method of improving the bulk or crimp while" reliably decreasing and controlling the water-swelling andjwetextensibility of regenerated cellulose yarns and textilesi Various modifications and adjustments may be made in practicing the invention'without departing from its spirit andscope.

Iclaim: v

l 'A process'for' producing a bulky yarn from a resin spuncellulosic yarncomprising supertwisting the yarn, setting thev twist therein by impregnating the twisted yarnwith formaldehyde at an elevated temperature and in'the presence'of an acidic catalyst, followed by thermal curing'fof the impregnated yarn, and then detwisting the cellulosicyarn tolproduce'a wooly effect which is substantially fast to washing-K V 2. Process; of. claim 1 wherein the catalyst is an ammonium phosphate;

31 Process of claim 1 wherein the catalyst is a heterogenous reaction product of monoethanolamine, HCl, and formaldehyde.

4. Product of claim 3 wherein the reaction product is formed from about 0.9 mole monoethanolamine, about 1.0 mole HCl, and about 2.0 moles formaldehyde.

5. Process of claim 1 wherein a coloring matter is incorporated into the yarn at a point prior to supertwisting.

6. A process for producinga bulky yarn from a resin spun cellulosic yarn of'about 150-300 denier comprising supertwisting' the yarn to a twist of about 5540 turns per inch,"im'pregnating the twisted yarn with a formaldehyde solution containing about 0.2S0.3% of an acidic catalyst, centrifuging, drying at an elevated temperature, curing for a time of 1040 minutes at a temperature of 175 C., and then detwisting to zero to produce a crimped yarn.

7. Process of claim 6 wherein the yarn is a pigmented yarn.

8. Process for producinga bulky yarn from a resinspun cellulosic yarn having distributed therethrough a linear polymer capable of reacting with formaldehyde to form a resinous condensatein situ, comprising supertwisting the resin -spun yarn, setting the twist therein by treating thetwi'sted yarnwith hot formaldehyde, and heating the impregnated yarn in the presence of an acidic cross-linking catalyst to cure' the resinous condensate, and then detwisting the yarn to'about the zero point to form thereby a .crimped and bulky yarn.

9. Process of claim 7 wherein the polymer is a linear polymer. of. an. amide having the formula:

kit, I]!

wherein R, R R R are each selected from the group consisting of hydrogen, methyl, and ethyl.

10.; Process of. claim 9 wherein the polymer is polyacrylamide. H V a 11. Process of claim 8 wherein the polymer is a linear polymerofa compound of the formula:

0 cnFo onmmh-Nm wherein A-is selected from I the group consisting of analkylene group of 2 -18 carbon atoms and a hydrocarbon-substituted alkylene group of 2:18 carbon atoms, at least two thereof occurring between the oxygen and nitrogen, andR is a member of the class consisting of H and monovalent hydrocarbon groups of not over 18 carbons. V

12. Process of 'claimflly wherein. the. polymer is polyfureidoethyljvinyhether); the. monomer having the formula.

13. Process of claim 8 wherein the polymer is a poly(vinyloxyalky1 alkyleneurea) 14. Process of claim 13 wherein the polymer is poly(viny1oxyethy1 ethyleneurea), the monomer having the formula CHI-CHI References Cited in the file of this patent UNITED STATES PATENTS Kagi Oct. 29, 1935 Graham July 25, 1950 Lyon Jan. 15, 1957 FOREIGN PATENTS Great Britain Mar. 14, 1941

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