US3084021A - Process for producing regenerated cellulose filaments - Google Patents

Description

April 2, 1963 SAlCHl MORIMOTO PROCESS FOR PRODUCING REGENERATED CELLULOSE FILAMENTS Filed Feb. 25, 1961 INVENTOR Soichi Morimoto Attorneys 3,084,021 Patented Apr. 2, 1963 3 084,021 PROCESS FOR PRQ DUCliNG REGENERATED CELLULOSE FILAMENTS Saichi Morimoto, 191 Kurumaji-cho, Karnide, @tsn, Japan Filed Feb. 23, 1961, Ser. No. 102,082 Claims priority, application Japan Feb. 29, 1960 13 Claims. (Cl. 18-54) This invention relates to novel regenerated cellulose fibres, products formed therefrom, and to processes for producing the same.

The industry of viscose regenerated cellulose fibres has been making steady developments in spite of the fact that various other and novel synthetic fibres have been developed and appeared on the market. Among the products of viscose regenerated cellulose fibres, those finding and developing a market most successfully today are (l) regenerated cellulose yarns for industrial uses such as rayon cords for reinforcement of tires, (2) crimped woollike regenerated cellulose fibres and (3) cotton-like re generated cellulose fibres with high tenacity and high wet modulus. In these fields, however, it is still required, in common, to further improve the mechanical properties of viscose regenerated cellulose fibres. lit is also desired that their specific properties depending upon the particular field of use he further improved. Among the persistently sought are, for instance, an increase in the number of crimps, improvement in crimp stability, increase in fatigue resistance of the fibres.

Accordingly, it is the general and primary object of this invention to provide improved viscose regenerated cellulose fibres with various excellent properties to meet the demands outlined above, and to provide processes for preparing the same.

More particularly, it is an object of this invention to provide a novel and improved process for producing viscose regenerated cellulose fibres of high tenacity and increased fatigue resistance suitable as fibres for reinforcement in industrial uses.

Another object of this invention is to provide a novel and improved process for producing cotton like viscose regenerated cellulose fibres of high tenacity and lower water swelling or high wet modulus.

It is a further object of this invention to provide woollike viscose regenerated fibres having more than 30 inherent crimps per inch, and to provide a novel method for producing the same.

It is a still further object of this invention to provide viscose regenerated cellulose fibres of the type mentioned above which are further improved in their crimp stability, and also to provide a novel resin treatment for producing the same.

Other objects of the invention will become apparent from the following detailed description.

The drawing is a schematic representation of an embodiment of the invention.

Viscose regenerated cellulose fibres have heretofore come to be improved in their properties due to repeated studies and efforts made in the art. For example, the so-called high tenacity rayon has come to be produced, with an outstanding commercial success, by the development of stretch spinning process with two spinning baths. Furthermore owing to the discovery of certain additives sometimes referred to as coagulation modifiers, the high tenacity rayon has further been improved so remarkably as to be called super high tenacity rayon. On the other hand, recently, through optical, X-ray and chemical researches, the inner structure of viscose regenerated cellulose fibres has come to be disclosed. Thus, it has now come to be recognized in the art that the properties, particularly mechanical properties of the viscose regenerated cellulose fibre depend upon the degree of orientation and degree of crystallinity of the cellulose molecules forming the fibre, and that these orientation and crystallinity degrees of cellulose molecules largely depend upon or are greatly influenced by the particular mechanical stretch imparted to the viscose gel yarn during its passage through coagulating and regenerating baths.

However, no industrially applicable work hasbeen reported up to the present to determine what magnitude of stretch should be imparted to such gel yarn in what stage in the continuous process of the yarn formation to bring about most desirable properties of the ultimate yarn due to the internal structural change resulted from such stretch. The reason for this is in that there has been accomplished no satisfactory or practical method for promptly determining an analyzing (quantitatively) the accurate number of residual xanthate groups as contain in viscose gel yarn at any stage in the spinning process from the viscose to the final or ultimate yarn, or at any stage during the spinning process from the extrusion stage of the viscose through a spinneret up to the final yarn which has completed the regeneration.

Various proposals have heretofore been made to determine the number of xanthate groups contained in a viscose gel yarn. All of these known methods have commonly been characterized by directly measuring the amount of combined alkali or xanthate groups in the gel yarn. However they have been unreliable particularly because of inevitable errors incurred in the process of measurement such as in discontinuation of the decomposition reaction of the cellulose xanthate, purification of the product to be measured, and removal of by-products, etc., and resulting inaccuracy of the value obtained.

It has now been found that it is possible to promptly determine the accurate number of residual xanthate groups without the drawbacks of the known methods, by taking a viscose gel yarn at any stage of spinning process, treating the yarn with an alkaline ammonium salt solution to convert all of the sodium xanthate groups present into the ammonium xanthate groups and simultaneously discontinue the decomposition reaction, washing the so treated yarn to remove any excess or free ammonium ions, decomposing the ammonium cellulose xanthate, and then quantitatively analyzing the ammonium salt formed by the above decomposition. More particularly, for example, a partially or incompletely regenerated viscose gel yarn in an amount corresponding to 0.25 to 0.35 g. of dry cellulose is taken up at any desired stage of spinning process into a cooled (e.g. below 5 C.) ammonial alkaline ammonium salt aqueous solution (saturation) to discontinue the decomposition of the xanthate. The mixture is left to stand for about 5 minutes to substitute all the residual or remaining xanthate groups with ammonium ions. Then the whole is transferred into a cooled wateralcohol (4:6) mixture and washed for 15 minutes repeatedly while replacing the washing liquid so as to remove free or excess ammonium ions. After this purification the ammonium xanthate now formed is decomposed in a 0.5% hydrochloric acid to form ammonium chloride. According to this method any insoluble ammonium salt is formed in the purification. The decomposed product is filtered to separate the regenerated cellulose, which is washed and dried, then weighed (this weight is represented by S in gram). The filtrate is made alkaline with sodium hydroxide in a round-bottomed flask, which is connected with a condenser to subject the solution to distillation. Ammonia gas distilled out thereby is introduced into a N sulfuric acid (A cc.). After confirming that the distillation of ammonia has been completed, the sulfuric acid solution is titrated with N sodium hydroxide.

, The amount consumed in this titration is represented by B cc. Through this measurement, the number of the (A-BgXLGZ Residual xanthate ratio (percent) This residual xanthate ratio is equal or corresponds, in the chemical nature, to the cellulose xanthate ratio (or gamma number) in a viscose. However, the important significance of the residual xanthate ratio in this invention is in that it is in respect of a viscose gel yarn and not of a viscose solution before spinning. For convenience, the residual xanthate ratio having the meaning substantially same as given above is referred to as RX hereinafter. The values RX as given in this specification and examples have been determined by the particular procedure just mentioned above, but it would be understood by those skilled in the art that the procedure can be modified without departing from the principle, and therefore the residual xanthate ratio referred to in this invention generally means a ratio (percent) of the number of xanthate groups in a viscose gel yarn with respect to the unit of glucose constituting the cellulose in said yarn and its method of measurement is not limited to the above indicated particular one, although this is believed to be most convenient and reliable at the present.

As described before I have succeeded in accurately and promptly determining the residual xanthate ratio (RX) of a viscose gel yarn on the way of its regeneration, and therefore I have been able to observe and investigate in detail the process of coagulation and regeneration of a viscose yarn during spinning. Particularly, the effect of stretch in various degree imparted to the viscose gel yarn at various stages on the orientation and/or crystallization of cellulose molecules constituting the yarn has been carefully observed and investigated.

From this work, it has been found that the gel structure of a viscose yarn being subjected to stretching has great influence upon the properties of the ultimate yarn, and also that the conditions of a viscose gel yarn and its treatment should be critical to improve the properties of the ultimate yarn.

As a result, it has been found that, generally, when a highly xanthated viscose is extruded into an aqueous acidic precipitating bath to form a yarn, and the yarn is adjusted or controlled so as to be within RX 40-20 just before being stretched, and then the yarn is stretched twice or more in a plurality of successive aqueous regenerating baths (in which any bath is not weaker in the regenerating power than that of the preceding bath), there are obtained excellent orientation and/or crystallinity of the cellulose molecules which remarkably improve the properties of the resulting ultimate yarn.

It has also been found that, in the above case, when the adjustment of RX 20-40 is effected under substantially relaxed or non-stretched condition in a secondary bath having not more than /2 acidity of the primary or fibre-forming bath and hence having a low regeneration power, the effect of the subsequent stretching is more remarkable. The present invention is based upon this finding or principle.

The above principle is applicable to a spinning process wherein a viscose of an ordinary viscosity less than about 150 poises (usually 100-50 poises) is spun into a Mueller-type spinning bath to produce yarns with a skin formed by the coagulating action of sulfates in the bath, as well as to a spinning process wherein a viscose of a high viscosity (more than about 150 poises) is spun into a bath having a poor regeneration and coagulation power to form yarns having substantially no skin.

Viscose which may be used in this invention may be prepared according to the conventional methods by dissolving wood pulp or cotton linter pulp. However, the present invention requires a highly xanthated or substantially unripened (at least 50% in xanthate ratio or more than 50 in gamma number) at extrusion, and therefore an alkali cellulose prepared from a cellulose substance should be xanthated with carbon disulfide in an amount more than 40% based upon the weight of the cellulose, and the viscose after the preparation should be kept at a lower temperature (e.g. below 15 C.) so as to prevent the progress of the ripening as much as possible. The aging degree of the alkali cellulose may be suitably selected depending upon the desired degree of polymerization of the cellulose.

The substantially unripened or highly xanthated viscose thus prepared is spun in accordance with the principle of this invention mentioned before. This may conveniently be carried out with a four aqueous bath system, as shown in the drawing, consisting of a primary bath, 3, which may be referred to as fibre or yarn forming bath, a secondary bath, 6, which may be referred to as residual xanthate ratio controlling bath, a third bath, 10, which may be referred to as stretching bath and a fourth bath, 17, which may be referred to as regenerating and setting bath.

The primary bath or yarn forming bath, 3, is the bath for forming a gel yarn, 4, from a viscose extruded therein through a spinneret or spinning nozzle 12, connected to a source line, 1. In case the viscose is about poises or less, an ordinary Mueller-type bath solution containing sulfuric acid, sodium sulfate and zinc sulfate and heated above normal temperature is required to be used in the primary bath, while when the viscose is of a viscosity higher than about 150 poises a bath solution containing a smaller amount of sulfuric acid and sodium sulfate and a very small amount of zinc sulfate and being kept at a temperature around or below normal temperature is required to be used.

The secondary bath, 6, or residual xanthate ratio controlling bath is the bath for adjusting the residual xanthate ratio of the filament yarn formed in the primary bath so as to be within 20-40%. It is necessary that the re generating power of the secondary bath be smaller than that of the primary bath and it is preferable that the acidity of the secondary bath is kept about or less than /2 that of the primary bath.

During the passage through the primary and secondary baths the gel filament yarn should have applied thereto to it as little stretch as possible or no stretch at all so as to substantially avoid any elongation of the yarn at these stages.

The third bath, -10, or stretching bath is the bath for imposing a first and positive stretch on the gel filament yarn during its passage therethrough. The third bath may be of the same composition and temperature as the secondary bath. Generally it is preferable, however, to use a bath with regenerating power a little stronger than that of the secondary 'ba-th so as to decompose 4060%, at most 70%, of the residual xanthate groups (in the gel yarn just before entering this bath) during the stretching process in this bath.

The fourth bath, 17, or regenerating and setting bath is the bath for imposing a second stretch on the gel filament yarn and for substantially decomposing the remaining xanthate groups to set the internal structure of the regenerated cellulose yarn.

As mentioned before the primary bath or viscose filament yarn forming bath according to this invention may generally be classified into two types depending upon the viscosity of a viscose employed. A series of the baths following to the primary bath also vary in their compositions and other conditions depending upon the primary bath. More particularly, the primary bath and hence the subsequently associated bath vary in their conditions depending upon whether (A) the viscosity of the spinning viscose solution is less than about 150 poises or (B) it is higher than about 150 poises. In conjunction with the baths, filament guide rolls 5, 7, 8, 11, 12, 15 and 16 are employed. As prime movers, godet rollers 9, 13 and 14 are placed respectively after the second, third and fourth baths.

(A) SPINNING A VISCOSE OF LESS THAN ABOUT 150 POISES The degree of polymerization of cellulose in a viscose to be employed in the case of (A) may be ordinary one (eg about 250-400) or may be high (cg. more than about 500). However it is necessary to make its viscosity below about 150 poises, preferably within about 50-100 poises, by controlling the cellulose content depending upon the polymerization degree. It is generally preferable to use a viscose containing 3-11% cellulose and 3-13% total alkali and whose combined carbon disulfide amount is at least 50%, preferably 75-90%, as expressed by xanthate ratio (or gamma number).

A Mueller-type bath is used as the primary or filament forming bath, and the subsequent spinning conditions are selected in accordance with the, principle of this invention mentioned hereinbefore. It has been found that the use of the following baths with conditions indicated give satisfactory results.

Primary Bath General range Preferable range Sulfuric acid Sodium sulfate rz.[l- 180-300.

Zinc sulfate .g./l 40-80.

Temperature 55-65.

Travel length (Immersion) Not so as to re- Approximately for duce RX of filaneutralizing the ment below viscose alkalin- 20%. ity.

Stretch (as little as] possible) Secondary Bath General Preferable range range Sulfuric acid g./l-. 5-30 -25 Sodium sulfateg./l 30-120 80-100 Zine sulfate g./l 0-100 10-30 Temperature 0.- 5-30 10-20 RX of yarn just before entering the thlrd bath percent- -40 -35 Str (as little als possible) Third Bath General Preferable range range Sulfuric acid g./l 10-50 25-35 Sodium sulfate ./1 -120 50-{30 71nc sulfate /1 0-100 10-30 Temperature. 10-50 25-35 Stretch percent 30-100 50-80 Fourth Bath General Preferable range range Sulfuric acid 50-70 Sodium sulfate Less than 30 Temperature 80-100 Stretch 30-50 The yarn obtained in this case of (A) is useful because of its remarkable high tenacity and high fatigue resistance as cords for reinforcement in industrial uses, such as cords for reinforcement of automobile tires and hoses; and for reinforcement fabric or cords of conveyor belts, etc. The yarn is, of course, useful as usual textile uses.

(A) SPINNING A VISCOSE OF LESS THAN ABOUT 150 POISES FOR PRODUCING CR-lMPED FIBRES WITH MORE THAN 30 PERMANENT CRI-MPS PER INCH It has been found that when a particular range of conditions among those in the case of the above mentioned (A) is selected, there is obtained a filament yarn which can be, through a conventional after-treatment, effectively crimped so as to have a number of permanent crimps more than 30 per inch. For this purpose, it is preferable to use a viscose having a x-anthate ratio between -75%. The primary bath is selected as follows:

Sulfuric acid ....g./l -100 Sodium sulfate g./l 250-350 Zinc sulfate -g./l 40-70 Temperature C- 65-75 Stretch As little as possible The subsequent spinning conditions may be same as those of (A) indicated before, but it is preferable that the residual xanthate ratio (RX) of the filament just before entering the third bath is controlled to be 30'- 40%. Crimp development may be effected by, any suitable conventional manner. For example the crimp formation can be carried out by relaxing the regenerated filament yarn (cut into staple or not), under non-tensioned condition, into a cellulose swelling liquid such as water, warm Water, a dilute aqueous solution of sodium hydroxide and the like. The number of permanent crimps to be formed somewhat depends upon the fineness of filaments spun. Generally, the coarser the filament is, the crimp number is less. However, in accordance with this invention, even when each filament is 10 deniers or above it is possible to form about 30 or more crimps per inch. In case of fineness of 1-3 deniers, the number of crimps per inch would come up to 50-70. The crimped filaments or staple fibres obtained in the case of (A) are useful as wool-like fibres. Particularly, those having more than 50 inherent crimps per inch obtainable according to this process are entirely novel and unprecedented in the art. These crimps are not lost by usual handling or mechanical stretching. Even if the crimp is partly lost by repeated carding, combing and other severe mechanical handling it is easily recovered by simply suspending the fibre in Water or other aqueous swelling liquid such as a dilute aqueous solution of sodium hydroxide, in the absence of tension. Thus, the crirnped fibres of this invention, even with such increased number of crimps show about 70-100% when measured by the crimp recovery from stretch test (this may be referred to as a wet meth- (*B) SPINNING A VISCOS'E OF MORE THAN ABOUT 150 POISES I The high viscosity (higher than about 150 poises) of viscoses may be obtained by increasing the content of the viscose cellulose or the cellulose polymerization degree in a conventional manner well known in the art. It is generally preferable to use a viscose containing 3-ll% cellulose and 3-13% total alkali and whose combined carbon disulfide amount is at least 50%, preferably -90%, as expressed by xanthate ratio (or gamma number).

In the present case (B) the primary or filament forming bath is conditioned so as to be poor in the coagulating and regenerating power, and the subsequent spinning conditions are selected in accordance with the principle of this invention mentioned hereinbefore. It has been found that the use of the following baths with the conditions indicated give satisfactory results.

s,os4,021

Primary Bath General range Preferable range Sulfuric acid g./l Less than 60 15-45.

Sodium sulfate g./l Less than 100 30-70 Zine sulfate.-. g./l Less than 5 Less than 1.

Temperature. (3.. -30 -20.

Travel length (Immersion)- Note so as to reduce RX of filament below Approximately for neutralizing the viscose alkalinity.

Stretch (as little als possible) Secondary Bath General range Preferable range Less than 30 20S0 0-30 Sulfuric acid g./l Sodium sulfate--. g./1.- Temperature RX of yarn just before entering the third bath percent Stretch 20-40 25- (as little as possible) Third Bath General range Preferable range Sulfuric acid g./l Less than 30 Sodium sulfate- .g./l.. 20-80 Temperature. G 0-30 Stretch 30-150 Fourth Bath General range Preferable range Sulfuric acid Sodium sulfate ponds (coagulation modifiers) cooperate with the zinc sulfate and serve to reduce the degree of primary gel swelling of the gel filaments, and therefore the use of such modifiers is particularly useful in cases of the above mentioned (A) and (A') or where a Mueller-type bath is used as the primary or filament forming bath for a viscose having a viscosity less than about 150 poises.

Among such compounds are, for example, polyoxyethylene mercapt-ans of the formula:

wherein R is a member selected from the group consisting of alkyl, aryl and cycloalkyl, R is a member selected from the group consisting of hydrogen and alkyl groups containing 1-4 carbon atoms, and n is an integer at least equal to 1.

Examples of the compounds expressed by the above formula are diethyleneglycolbutylmercaptan, decaethylencglycolpropylmercaptan, pentadecaethyleneglycolphenylmercaptan, decaethyleneglycolbutylmercaptan, etc.

Aliphatic and alicyclic amines are also useful as the coagulation modifiers, among which are, for example, triethanolamine, triethylamine, cyclohexylamine, benzylaminc, etc.

The salts of N-substituted dithiocarbamic acid are also useful, among which are, for example, amyl dithiocarbamate, cyclohexyl dithiocarbamatc, N-methylcyclohexyl dithiocarbamate, methyl dithiocarbamate, etc.

Further examples of the compounds useful as the coagulation modifiers are those having the following general formula:

wherein each of R and R is a member selected from the group consisting of hydrogen, alkyl and aryl, n is an integer equal to at least 1. Among those compounds expressed by the above formula are, for instance, polyethyleneglycol, phenoxycthanol, ethoxyethoxyethanol, butoxylethoxyethanol, etc.

Among other compounds useful as the coagulation modifiers are mercaptoamines and N-substituted mercap todithiocarbamatcs, such as B-mercaptoethylamine, 'y-mcrcaptopropylamine, orthoaminothiophenol, N-substituted- B-mercaptoethylcarbamate, etc.

No further explanation would be required on these and other coagulation modifiers because they are well known per se in the art.

The amount of these modifiers to be present in the viscose may vary depending upon the particular viscose, spinning speed and bath conditions. Generally, good results are obtained if the modifier(s) is used in an amount from 0.1 to 1.0 millimolc per grams of the viscose. A larger amount of the modifiers over the range recited above may be used, but the effect of the modifier is not progressively enhanced by such an excess amount of use.

The incorporation or addition of such modifier to a viscose may be carried out at any stage in the process of preparation of the viscose. For example, it is possible to predissolve or predisperse the modifier in a dilute aqueous solution of sodium hydroxide to be used later for dissolving a cellulose xanthate. Alternatively, it may be added directly to the viscose.

As previously mentioned herein, a two-bath stretch spinning system is known to produce the so-called high tenacity rayon or super high tenacity rayon. The conventional two-bath stretch spinning process is characterized by forming a gel filament yarn in the primary bath and then immediately stretching the so formed gel yarn in the secondary bath to effect orientation of the cellulose molecules. This conventional process has inherent defects, that is an improvement of one respect of the fibre properties, such as tenacity has inevitably accompanied sacrifice in other valuable properties.

In sharp contrast thereto, according to the novel process of this invention, the gel yarn formed in the primary bath is not immediately stretched but is controlled so as to obtain a particular regeneration state with a stretch as little as possible, and thereafter it is progressively regenerated while being subjected to suitable successive stretching during its passage through the subsequent successive baths in which the regenerating power increases progressively. By this novel spinning process I have produced filaments having increased tenacity comparable with the known two-bath spinning process with additional outstanding properties now persistently sought in the regenerated cellulose industry.

In carrying out the spinning process of this invention any suitable apparatus may be used so far as it is adapted to fulfill the spinning conditions as specified above. Most typically, the four baths are arranged in series at suitable intervals, each being provided with suitable guides. A viscose is extruded through a spinneret into the primary bath. The filaments formed in the bath are guided upwardly out of the bath to a guide roller located between and above the primary bath and sec ondary bath. Since the filaments must be controlled so as to have a residual xanthate ratio from 25-35% when entering the third bath, the travel or immersion length of the filaments within the primary bath should be selected so that the filaments leaving the primary bath do not become below about 20% in the residual Xanthate ratio.

jet velocity or rate at the spinneret, that substantially no tension is imposed on the filaments during their travel up to this godet roller. From this first godet roller the filaments are passed through the third bath while being guided by suitable guides therein and, after leaving the bath, are taken upwardly by a second godet roller located between and above the third bath and the fourth bath. While passing through the third bath the filaments are stretched due to a differential in speed between the first and second godet rollers. From this second godet roller the filaments are passed through the fourth bath while being guided by suitable guides therein and, after leaving the bath, taken upwardly by a third godet roller located at a short distance beyond the fourth bath. While passing through the fourth bath the filaments are stretched due to a differential in speed between the second and third godet rollers. From the third godet roller the filaments may be passed to a conventional purification apparatus such as for washing with water followed or not followed by refining, bleaching, etc. It will be understood that if the secondary bath and the third bath are identical in the composition and temperature, a single bath may be used therefor but the second godet roller is arranged above the bath at a suitable position. a

Generally, the spinning speed (final wind-up speed) is 20-80 m./min. for the process of (A) and (A'), and is -30 m./min. for the process of (B).

The regenerated cellulose fibres produced by the novel multi-bath spinning process of this invention as described above and products such as fabrics made of such fibres have outstanding properties and are very useful as such. However, sometimes, it may be desired that these fibres and their products have more excellent compressive resiliency, crimp recovery from stretch in dry state and other properties. It has been found that these desirable additional properties are obtained if these regenerated fibres or their products are subjected to the particular resin treatment which will be fully described hereinlater. For example, when the crimped fibres obtained in the above mentioned process (A') are resin-treated as hereinbelow described their crimp recovery from stretch (in dry state) when tested in accordance with the procedure as hereinlater described attains to a value from about 80% up to approaching 100%.

(C) RESIN TREATMENT It has been conventional in the art of resin treatment for such purpose to employ a preor primary polymer (or condensate) of urea-formaldehyde resins, melamineformaldehyde resins, etc. The primary condensate is applied to fibres or their products and is then heat cured thereon. densates are, as against the monomers (methylol urea, methylol melamine), so large that it is difficult for them to penetrate into very small spaces in the internal fi bre structure or crystalline structure. Therefore, a considerably large amount of the resin is required to attain a satisfactory effect of such treatment, and furthermore the resin unevenly adheres only on the surface area of the fibre, so that there have been various drawbacks that the product is hard in hand feeling, a large amount of the resin is removed upon laundering with a result of loss of the effect of the resin finish.

However, the molecules of these primary con- 7 It has been proposed to impregnate fibres with a sub stance such as urea and thiourea which is reactive with formaldehyde, and then to react it with formaldehyde to effect resin formation in the fibres. However, said substance easily forms its dimer so that a subsequent reaction with formaldehyde becomes difficult. Thus, a satisfactory effect of resin finish is not obtainable. Further drawbacks of this method are that the finish has no good resistance to laundering and that the so treated fibres considerably lose the strength.

If fibres could be impregnated with melamine in the form of monomer and not as a primary condensate with formaldehyde and then formaldehyde could be allowed to react with the melamine in the fibres to effect the resin formation, an excellent resin finish should be obtained. However, since melamine is so hardly soluble in water that such melamine resin treatment has been practically impossible. Although it is possible :to increase the solubility of melamine by converting it into salts of strong acids such as hydrochloric acid, the use of such strong acid salts would cause discoloration and loss of strength of the treated product during the heat treatment and the product would be impaired in appearance and feeling.

It has now been found that an excellentresin treatment can be effected by impregnating fibres or articles made thereof with an aqueous solution of a salt of melamine with an oxy acid containing hydroxyl group(s) in the molecule, such as lactic acid, glycolic acid, thioglycolic acid, gluconic acid, etc., and then allowing formaldehyde gas (vapor) to at thereon in the presence of a small amount of water. As these melamine salts of oxy acids are high in solubility in water they are advantageous in many respects. Furthermore as they are salts of weak acids there is no fear of discoloration and loss of strength of the fibres in the heat treatment, and advantageously they serve as a good catalyst in the condensation reaction during the heat cure treatment. Further advantages of this novel method are that since melamine monomers in the form of a solution sufficiently penetrate into very narrow spaces of the internal fibrous and crystalline structure the use of a relatively small amount of the material affords excellent results or increase in elastic recoverability, crease resistance, shrink resistance and dimensional stability, and that as the resin is deeply distributed in the internal fibrous structure the effect of the resin finish is rather permanental and is excellent in resistance to laundry.

In carrying out the novel process of resin treatment according to this invention, it is suitable that an oxy acid is'reacted with melamine in the proportions of 0.3-3.0 moles of the oxy acid per mole of melamine. In an aqueous solution containing 0.5 to 4% of the melamine 'salt, at a temperature from normal temperature to. the

boiling point of the solution, fibres or their products such as textiles, knitted fabrics, etc. to be treated are immersed and impregnated with the solution. The impregnated article is squeezed or centrifuged to remove an excess liquid and dried at a temperature ranging from 60 to C. Thereafter formaldehyde vapor is allowed to act on the fibres or article. The temperature of the formalde hyde vapor may be from normal temperature to 100 C., but preferably 30 C. to 50 C. If the temperature at the formaldehyde treatment exceeds 100' C. there is a danger that the formaldehyde is connected in a polymerized form to melamine with a result .to cause enbrittlement of the fibres. In reacting formaldehyde with melamine as adsorbed in the fibres, the presence of 10 to 30% (based on the weight of the fibres) of Water is required. However, the-presence of an excessive amount of water should be avoided because it would induce a violent reaction which would embrittle the fibres or impair the feeling of the fibres. If the amount of water is insufiicient the reaction is difficult to proceed. The amount of water as considered here means that contained in the formaldehyde vapor plus that remaining in the fibres or their products. The time for the reaction varies widely from about 10 minutes to 5 hours depending upon the temperature. As for formaldehyde, a moist formaldehyde vapor produced by heating at a temperature below 80 C. a 30-40% aqueous formalin may be employed. Alternatively, formaldehyde gas produced by heating at a temperature below 100 C. para-formaldehyde may be used. It is preferable that the amount of formaldehyde to be employed is about 2 to 5 moles per mole of melamine as contained in the fibres. After the treatment with formaldehyde vapor, the article is dried at 60-100 C. for 5-15 minutes, and then set or cure the resin by a heat treatment at a temperature of 120-1 60 C. for a period of time required for setting the resin, for example more than 2 minutes. The article is then washed to finish, or subjected to a conventional after-treatment.

For illustrative purposes, the following specific examples are given. Among them, Examples 1-4 are to illustrate the multi-bath spinning process of (A), Examples 5-7 relate to the process of (A') and Examples 8-10 are to illustrate the spinning process of (B). Examples 11-14 are to illustrate the resin treatment of (C).

EXAMPLE 1 A cotton linters cellulose pulp was steeped for 2 hours in an aqueous solution containing 230 g./l. of sodium hydroxide and the alkali cellulose was pressed until to be 2.6 times the weight of the original pulp used. After shredding the alkali cellulose in a conventional manner, carbon disulfide in the amount of 50% based upon the weight of a-cellulose was added thereto, and the xanthation reaction was then allowed to proceed for 3.5 hours while elevating the temperature from 20 to 28 C. After the reaction the cellulose xanthate was dissolved by adding thereto predetermined amounts of sodium hydroxide and water to give a viscose containing 7.0% cellulose and 6.0% total sodium hydroxide. After ripening at 5 C. for hours, its viscosity was 91 poises and the xanthate ratio was 70%.

The viscose in the substantially unripened state was spun through a spinneret having 720 holes of 0.06 mm. diameter into a primary bath under the following condition to form viscose gel yarn:

Sulfuric acid 120 g./l.

Sodium sulfate 300 g./l.

Zinc sulfate 5O g./l.

Temperature 60 C.

Travel length (immersion) As required for approximately neutralizing viscose alkalinity. Then this gel yarn was passed through the following secondary bath;

Sulfuric acid g./l 15 Sodium sulfate g./l 60 Zinc sulfate g./l 50 Temperature C 15 composition:

Sulfuric acid g./l Sodium sulfate g./l 70 Temperature C 20 The yarn, while passing through this bath, was stretched 60% by a differential in speed between a second godet roller loca-ted beyond the third bath and the first godet roller. The yarn thus subjected to a low temperature stretch was Wound up on the second godet roller.

Then the yarn was passed from this second godet roller into and through the following fourth bath;

Sulfuric acid g./l 100 Sodium sulfate g./l 150 Temperature C 70 The yarn, while passing through this bath, was stretched 30% by a difference in speed between a third godet roller (peripheral speed about 30 m./min.) located behind the fourth bath and the second godet roller, and was completely regenerated during receiving this high temperature stretch to give a yarn of 720 filaments of 1100 deniers. The yarn was successively washed with water, oiled and dried and was wound up on a bobbin. To a single strand of this yarn was imparted a twist in the amount of 12.5 per inch and two such twisted single yarns were twisted together into a cord while applying 12.5 twists per inch. The properties of this cord are given below:

The values given in the above parentheses are of cord, for comparison, obtained by the following two-bath stretch spinning method. That is to say, the viscose prepared by the same method as of this example was, after ripening at 15 C. for 20 hours, spun at a viscosity of 83 poises and a xanthate ratio of 63% into the following primary bath under the following condition:

Sulfuric acid g./l 130 Sodium sulfate -g./l 250 Zinc sulfate g./l 60 Temperature C 60 The yarn which, after leaving the primary bath, was 23 in the residual xanthate ratio was then passed through the following secondary bath under the following condition:

Sulfuric acid g./l.. Temperature C 98 During the passage of this secondary bath the yarn was subjected to stretch between godets and completed the regeneration, to give a yarn of 720 filaments of 1100 deniers. The yarn was then washed with water, oiled and dried, and was twisted under the same conditions as in the above example into a cord for testing.

EXAMPLE 2 A dissolving wood pulp was steeped for 2 hours in an aqueous solution containing 230 g./l. of sodium hydroxide and the alkali cellulose was pressed until to be 2.7 times the weight of the original pulp. Then the alkali cellulose was shredded at 30 C. for 15 hours. Immediately there after or without being aged, to the alkali cellulose was added 45% carbon disulfide (based on the weight of a-cellulose), and the xanthation reaction was then allowed to proceed for 3 hours while elevating the temperature from 20 C. to 28 C. After the reaction the cellulose xanthate was dissolved in a sodium hydroxide solution in which decaethylene glycol tertiary butyl mercaptan had been dissolved in such an amount as to be 0.3 millimole/ grams of viscose. Thereby a viscose having a cellulose content of 6% and a total sodium hydroxide content of 6% was obtained. This viscose was deaerated while being ripened at 5 C. for 20 hours, and was, under the conditions of a viscosity of 78 poises and a xanthate ratio of 65%, extruded through a spinneret of 720 holes 13 of 0.06 mm. diameter into a primary bath of the following conditions:

Sulfuric acid g./1 120 Sodium sulfate g./-l 300 Zinc sulfate g./l 50 Temperature C 58 Travel length (immersion) As required for approximately neutralizing viscose alkalinity.

The formed viscose gel yarn was then immediately and, Without imposing a tension as possible, passed into and through the following secondary bath:

Sulfuric acid g./l Sodium sulfate g./l 50 Zinc sulfate g./l 60 Temperature C During the passage of this bath the yarn was stretched as little as possible, and the residual xanthate ratio of the yarn after leaving the second bath was controlled so as to be The gel yarn was then passed into and through the following third bath:

Sulfuric acid g./l 30' Sodium sulfat g /1 50 Temperature C 15 The yarn, while being passed through the third bath, was stretched 60% by godet rollers located respectively before and behind the third bath. The residual xanthate ratio of the yarn leaving the third bath was controlled so as to be 15%. Then the yarn was stretched by in the fourth bath of the following condition:

Sulfuric acid g./l 60 Temperature C 80 Oven-dry breaking strength 4.68 g./d.

4.02 g./d.). Oven-dry breaking elongation 10.4% (17.3%). Loss of strength after 2 hrs. at

Fatigue test with Goodrich cord tension vibrator (under load of 7 282 minutes lbs.) (262 minutes).

The values given in the above parentheses are of cord, for comparison, obtained by the following two-bath stretch spinning method. That is to say, the viscose prepared by the same method as of this example was, after ripening at 10 C. for 8 hours, spun at a viscosity of 65 poises and a xanthate ratio of 60% into the primary bath of the following condition:

Sulfuric acid g./l 120 Sodium sulfate g./l 270 Zincsulfatefla g./l 60 Temperature C The yarn (R.X. 20) was then completely regenerated while being stretched 80% between godet rollers and being passed through the following secondary bath:

Sulfuric acid g./l Temperature C 95 By this way, a yarn of 720 filaments of 1650 deniers was obtained. The yarn was then washed with water, oiled and dried, and was twisted under the same conditions as in Example 1 into a cord for testing.

EXAMPLE 3 An alkali cellulose prepared by the same operation as in Example 1 from a cotton cellulose pulp was shredded at 15 C. for 2 hours. After the addition of 50% (based upon the weight of a-cellulose) carbon disulfide, xanthation reaction was allowed to proceed for 3 hours while elevating the temperature from 20 C. to 25 C. The highly xanthated cellulose thus obtained was dissolved in a dilute aqueous solution of sodium hydroxide in which cyclohexyl amine had been dissolved in such an amount as to be 2 millimoles/ grams of viscose. In this way, a high polymerization degree, low cellulose content v-iscose having a cellulose content of 3.5%, a total sodium hydroxide content of 60% and an average cellulose polymerization degree of 630 was obtained. This viscose was of a xanthate ratio of 70% and a viscosity of 62 poises. This viscose, without being ripened, was extruded as in Example 1 through a spinneret into the following primary bath:

Sulfuric acid g./l Sodium sulfate g./l 330 Zinc sulfate g./l 80 Temperature C 60 The formed gel filament yarn was then immediately and without being stretched, passed into the following secondary bath:

Sulfuric acid g./l 10 Sodium sulfate g./l 100 Temperature C 10 Sulfuric acid- -g./l- 20 Sodium sulfate g./l 70 Temperature C 30 The yarn while passing this bath was stretched by 70% at the low temperature between two 'godet rollers. The residual xanthate ratio of the yarn after leaving the third bath was controlled to be 14%. Then the yarn was passed through the following fourth bath:

Sulfuric acid g./l 100 Sodium sulfate -1 g./l Temperature C 70 While the yarn was stretched by 40% at the high temperature in this fourth bath, it was completely regenerated to obtain a yarn of 1000 filaments of 1100 deniers.

The yarn was successively washed with water, oiled and dried, and was then wound up on a bobbin (about 50 m./min.). The yarn was twisted into a two-ply twisted cord under the same conditions as in Example 1. The properties of this cord are as follows:

Oven-dry breaking strength 5.02 g./d.

(4.10 g./d.). Oven-dry breaking elongation 10.6% (16.8%). Lossof strength after 2 hrs. at

Fatigue test with Goodrich cord tension vibrator (under load of 7 225 minutes lbs. (206 minutes).

Sulfuric acid g./l 100 Sodium sulf /-l 300 Zinc sulfate g./l 50 Temperature C 60 The yarn (RX. 26) was thereafter completely regenerated while being stretched 75% between godet rollers and being passed through the following secondary bath:

Sulfuric acid g./l 40 Temperature C 95 Thus, a yarn of 1000 filaments of 1100 deniers was obtained. The yarn was then washed with water, oiled and dried, and was wound up on a bobbin. Thereafter, the yarn was twisted into a cord under the same conditions as in Example 1.

EXAMPLE 4.

Sulfuric acid g./l 110 Sodium sulfate g./l 270 Zinc sulfate g./l 60 Temperature C 63 The condition of the secondary bath (residual xanthate ratio controlling bath) was as follows:

Sulfuric acid g./l 10 Sodium sulfate g./l 100 Temperature C 15 The residual xanthate ratio of the gel yarn leaving the secondary bath was controlled so as to be 33%. The gel yarn which had not been stretched up to the passage through this secondary bath was then stretched by 60% in the following third bath (low temperature stretching bath):

Sulfuric acid g./1 30 Sodium sulfate g./l 100 Temperature C 15 The yarn was further stretched by 50% during the passage through the following fourth bath (regenerating and setting bath):

Sulfuric acid ..g./l 100 Sodium sulfate g./l 150 Temperature C 95 In this bath the yarn was completely regenerated and was then wound up on a bobbin (about 30 m./min.). Then, the yarn was cut into a staple length of 38 mm. and was refined and dried in a conventional manner. The properties of the staple fibres thus obtained are as follows:

Filament fineness deniers 1.5 Dry tenacity g./d 4.51 Wet tenacity g./d 3.97 Dry elongation percent 18.8 Wet elongation do 23.3 Knot strength -g./d 3.55

The following Examples 5 to 7 are to illustrate the manufacture of crimped fibres according to this invention hereinbefore outlined under (A'). In these Examples the evaluation of the crimp recoverability was made by the crimp recovery from stretch test outlined in the before mentioned United States Patent No. 2,287,099.

EXAMPLE 5 A viscose prepared by the same operation as in Example 2 except that beta-mercapto-ethyl amine was. added to the viscose in the amount of 3 millimoles/lOO grams of viscose, was filtered and deaerated. The viscose hav- The primary bath was as follows:

Sulfuric acid g./l- Sodium sulfate g./l 300 Zinc sulfate g./l 60 Temperature C 63 The secondary bath was as follows:

Sulfuric acid g./l 10 Sodium sulfate g./l 100 Temperature C 15 Up to the passage through the secondary bath, the gel yarn was handled so as to be stretched as little as possible. The residual xanthate ratio of the yarn leaving the secondary bath was controlled to be 35%.

The third bath was as follows:

Sulfuric acid g./l 30 Sodium sulfate g./l 80 Temperature C 20 In this bath, the gel yarn was stretched by 50% between godets.

The fourth bath was as follows:

Sulfuric acid g./I 60 Temperature C 97 In this bath, the yarn was completely regenerated while being stretched by 30%. The yarn was then wound up on a bobbin (about 40 m./min.). The yarn was then cut into staple length of 38 mm. and was immersed in hot water, in a relaxed state, Crimps were developed thereby. During the subsequent purification and bleaching, no substantial change in the crimp was observed. After the fibre was refined and dried, the number of crimps was 60 per inch, and the properties of the fibre were as follows:

Filament fineness deniers 3.2 Dry tenacity -g./d 3.52

Wet tenacity ..g./d- 2.56 Dry elongation .Percent 23.2 Wet elongation do 30.1 Crimp recovery from stretch do 95 EXAMPLE 6 A cellulose xanthate prepared by the same operation as in Example 1 was dissolved in a predetermined amount of a dilute aqueous solution of sodium hydroxide in which benzyl amine had been dissolved so as to be of a concentration of 0.7 millimole/ 100 grams of viscose, to obtain a viscose containing 7% cellulose and 8% total sodium hydroxide. This viscose was immediately filtered and deaerated and was then spun by the same spinning apparatus as in Example 1, at a xanthate ratio of 70% and a viscosity of poises.

The primary bath was as follows:

Sulfuric acid g./l Sodium sulfate g./l 350 Zinc sulfate g./l 40 Temperature C 70 The secondary bath was as follows:

Sulfuric acid g./l 20 Sodium sulfate g./l 50 Zinc sulfate g./l 60 Temperature C 20 Up to the passage through the second bath, the gel yarn was handled so as to be stretched as little as possible. The residual xanthate ratio of the yarn leaving the secondary bath was controlled to be 25%.

17 The third bath was as follows:

Sulfuric acid g /l 50 Sodium sulfate g /1 100 Temperature C 20 The yarn was stretched by 60% in this third bath. The fourth bath was as follows:

Sulfuric id g/l- 30 Temperature C 90 In this bath, the yarn was stretched by 30% and was completely regenerated. This yarn was Wound upon a bobbin (about 40 m./min.), and then cut into staple length of 38 mm. The fibre was immersed under relaxation in water, whereupon 55 permanent crimps per inch were developed on the yarn. After refining and drying, the properties of the fibre were as follows:

Filament fineness deniers 2.5 Dry tenacity g./d 3.85 Wet tenacity 'g./d 2.72 Dry elongation percent 20.2 Wet elongation do 29.2 Crimp recovery from stretch do 100 For comparison, the same viscose which contained benzyl amine in a concentration of 0.7 millimole/ 100 grams of viscose and which contained 7% cellulose and 8% total sodium hydroxide was prepared from the cellulose xanthate obtained by the same operation as in Example 1. After the viscose was filtered and deaerated, it was spun at a xanthate ratio of 70% and a viscosity of 85 poises into the following primary bath:

Sulfuric acid ..g./l 80 Zinc sulfate g./l 320 Temperature C 70 The viscose yarn formed in this bath was completely regenerated while being stretched by 80% in the following secondary bath:

Sulfuric acid g./l Temperature C The yarn thus obtained was cut into staple length of 38 mm. and was immersed in 1% aqueous solution so- 7 dium hydroxide so as to develop crimps. After refining and drying, the properties of the fibre were as follows:

Filament fineness der1iers 2.5

Dry tenacity g./d 2.86

Wet tenacity g./d 1.71

Dry elongation percent 22.6

Wet elongation do 25.6

Crimp recovery from stretch do 45 EXAMPLE 7 A cellulose xanthate prepared by the same operation as in Example 2 was dissolved in a dilute aqueous solution of sodium hydroxide containing no additive or modifier to produce a viscose containing 6% cellulose and 7% total sodium hydroxide. This viscose, under the conditions of a xanthate ratio of 70% and a viscosity of 64 poises, was spun by the same spinning apparatus as in Example 1.

The primary bath was as follows:

Sulfuric acid"; ./1 70 Sodium sulfate -4 g./l 280 Zinc sulfate g./l 80 Temperature C 65 The secondary bath was as follows: Sulfuric acid g./l 10 Sodium sulfate g./l.. 100 Temperature C The residual xanthate ratio of the yarn leaving the secondary bath was controlled to be 28%.

18 The third bath was as follows: Sulfuric acid g./l 10 Sodium sulfate g./l 100 Temperature C 25 In this third bath, the gel yarn was stretched by 60%. The fourth bath was as follows:

Sulfuric d g./l 100 Sodium sulfate -g./l 80 10 Temperature C 80 In this four-th bath, the yarn was stretched by 40% and completely regenerated therein. Then the yarn was Wound up on a bobbin (about 50 m./min.). After washing with water the yarn Was cut into staple length of 51 mm. and was immersed in an aqueous solution of 1% sodium hydroxide under relaxed state, whereupon 40 crimps per inch were developed. The properties of the staple fibre obtained in this example were as follows:

Filament fineness deniers 2.0 Dry tenacity g./d 3.4-8 Wet tenacity g./d 2.38 Dry elongation percent 18.3 Wet elongation do 25.0 Crimp recovery from stretch do 75 EXAMPLE 8 An alkali cellulose prepared by a conventional method from a dissolving wood pulp was shredded and aged.

Then 70% (based upon the weight of u-cellulose) carbon disulfide was added thereto and the xanthation reaction was proceeded for 3 hours while elevating the temperature from 17 C. to 23 C. The cellulose xanthate was dissolved in -a cooled (10 C.) dilute aqueous solution of sodium hydroxide, thereby a viscose having an average cellulose polymerization degree of 350, a cellulose content of 10% and a total sodium hydroxide content of 7% was obtained. This viscose, at a viscosity of 220 poises and a xanthate ratio of 78%, was spun with the a spinneret of 2000 holes and 0.05 mm. diameter. The first bath .was as follows:

Sulfuric acid g./l Sodium sulfate -g./l 65 Zinc sulfate g./l 0.3 Temperature C p 8 The viscose gel yarn formed in this bath was then passed into and through the following secondary bath:

Sulfuric acid g./l Sodium sulfate g./1

Temperature C The' gel yarn passed through the bath so as to bestretched as little as possible and the residual xanthate ratio of the yarn leaving this bath was controlled to be 28%. This yarn after leaving this bath was Wound up on a rubber godet of a peripheral speed of 5 m./min.

and therefrom passed into the third bath of the same temperature and composition as of the secondary bath where.

in it was stretched by 20% during the passage through the following fourth bath:

same spinning apparatus as in Example 1 but through 1,9 EXAMPLE 9 An alkali cellulose prepared by a conventional method from a"cottoii1if1'trs cellulose pulp was shredded, and; 70% carbon disulfide (b'asedupon'tlie weight of a-CClllT- lose) was added ther eto withoutageing the alkali cellulose. After'the-xanthationas in Example 8, the cellulose xanthate was dissolved in a dilute aqueous solution of sodium hydroxide. Thus a viscose havingan average cellulose polymerization degree of 7 50, a cellulose con l I a I H *plesyanous. numencatvalues or test results llldlQatfld.

tent of 35% and a total sodium hydroxide content of was obtained.

This viscose, at aviscosity of 280 poisesand a xanthate ratioof 75 %l, wasspun with the same spinning apparatus asin Example 1. 5

' The first bath was as follows: Sulfuric acid; g./1 29 o ium. ul at 0 Zing: sulfate g,/1 0.120 Temperature C The gel .viscose yarn after leaving this bath was immediately passed .through. the following secondaryibathz Sulfuric acid 1 1.0 51

Sodium sulfate g 1 50 Temperature f C-- 15 The yarn was passed through the secondary bath so as to The stretched as little as possible, and the residual xanthate ratio of the yarn leaving this-bath was controlled 4 to be 27%. The yarn was passed from this bath through a godet roller (5,m./min.)' into the subsequent third bath havi'rigthe same temperature and composition as of the second bath. During the passage through this bath the yarn was stretchedby 110%, and the residual 'Xanthate ratio (R.X.) of the yarn leaving the bath was controlled; tobe Then 'theyarii 'wascomplet ely regenerated whilebeihg stretchedby %fin the ren n tonnage Sulfuric Acid ..g./1..- 60 Sodium sulfate g./1 100 7, e p r tur The completely regenerated yarn was wound up ona bobbin-and wasthen refined and'dried by a conventional manner. The properties of the yarn were "as follows:

Filament fineness eniers 1.2 Dry tenacity; Zg;/d 5.63. We: tenacity g/d 4.71 Dry elrifigatihn per c e nt 7.8 Wet elongationgnu; do.." 7.8

Emerald" An alkfi celluloseprepared by a conventional manner from a cotton lin'ters cellulose pulp was shredded and. aged. Thereafter, %,,(based uponjthe'weight of a cellulpseYcarbo'ri disulfi'de was added thereto, and the l xanth ation' reaction and"dissolution of the resulting, xanthate were effected by the same method in Example 8 .to prepa'r" a 'visc'ose "having" a cellulosecontent;

The average cllirlo'sepolynierization degree of the viscose was 480 This viscose at a"visc'o sit y of. 300 poises. and "a xapthate ratio of 73% was spun withwth e same spinning apparatusas in Example 8. The. primary bathw was'a's follows: K

Filament fineness deniers 1.5. Dry tenacity a g./d 4.82 we: tenacity; g'./d 4.10

Dr'yelong'atiomtm; percent 8.0 Wet elongation do 8.5

20 and was then treated the same as in Example 8. The properties of the yarn were as follows:

The following Examples 11-14 illustrate the novel resin treatment according to.thisjnvention. In these Examwere determined the following procedures.

Tear strength: Measured by Pendulum methodtunit, g.).

Crease resistance: .Measured by Monsanto method (unit,

degree), directionplus filling direction.

Abrasion resistance: .Measured with Universal Weartester (unit, number of times).

Compressiveresilienc'e: Cut fibres are piled up on a flat plate" and are" compressed by a column body "at a speed of 10 cm./min. When the pressure has reached 25.5 g./c'm.'-, the compression is discontinued and the column body is returned'to the original position ata speed of 10 cmL/min'. The same compression as in the above is againapplied. 'Whilelthese procedures the pressure. variation is continuouslymeasured by Instron (tensile tester) to findtthework done. If the. workdonein fthefirst compression stroke is F and the :work done in the second compression stroke is F then the compressive resilience is representedas follows:

Compressive resilience=, X

Stress relaxation coeflicient: The fibres are compressed as 1 applied to the lower end, to measure the length of the filament (a m Then a load of 50 mg. per denier is "appliedand the lengthtb cm.) of the filament is' measured after l minutef Then the load is removed and .upon -the lapse of '1 minute a load of 5 mgQis again applied to measure the length (c cm.). Then, the crimp recovering is represented as'follows:

Crimp recovery from stretch (dry state) =g X100 1 mole to lactic acid 0.68 1110a Afterrem ovin g an the form ofa lacticacid saltin' a molejratio pfjmelamine excess solution, the fabric was dried to be 20 %Zwater content. Then the fabric'was exposed to formaldehyde gas; geperated. by. heating. paraeformaldehydeto 50 C.,

After ,dryingat 85.....C. for .3 minutes, the fabric was heat-treated,at,.150i. C. for. 5 minutes, and was then washed with hot water and dried. For comparison, ac-

cording to a conventional method, the same muslin fabric as in the above was soaked in a 6% trimethylol melamine solution containing 0.6%of magnesium chloride as a catalyst. Thereafter the fabric was dried at 85 Cfor 5 minutes, and then heatftreated .at C. for 5 minutes. Then the fabr icwas washed with-hot water and Abrasion resistance (number of times) Crease resistance (degrees) Tear Deposition strength- (a) of resin (percent) Lactic acid melamine- Trimethylol melamine.-. Untreated EXAMPLE 12 Crimp recovery (percent) Stress relaxation cocifieient Compressive resilience (percent) Untreated Treated with glycolic acid melamine r The crimped staple fibres so treated did not lose the crimps even through carding operation.

EXAMPLE 13. I

A bulk of crimped staple fibres obtained in Example 6 was immersed in a 3% solution of melamine lactate (melamine to lactic 'acid' in equimolecular proportions) at 70 C. After removing an excess solution by a centrifugal separation, the fibres were dried at 80 C. Then the fibres were exposed to a 38% formalin vapor at 30 C. for hours, and then were subjected to heat treatment at 160 C. for 3 minutes. The fibres thus treated were 78% in compressive resilience and 98% in crimp recovery from stretch (in dry state). The fibres were spun and woven into muslin 9. The properties of this fabric are as follows:

Deposit of Tear Crease resin strength resistance (percent) (g) (degree) Treated 4. 56 1,058 275 Untreated 1, 211 211 EXAMPLE '14 A weft sateen woven from the staple fibres obtained in Example 8 was immersed in a 3% solution of melamine salt (containing 1.5% thioglycolic acid) at 60 C. After removing an excess liquid, the fabric was dried at 80 C. for 10 minutes, and then exposed to a 37% formalin vapor at 50 C. for one hour. Thereafter the fabric was subjected to a heat treatment at 150 C. for 5 minutes. The

(1) extruding highly xanthated viscose, containing 3-11% by weight cellulose and 3-13% by weight total alkali, said viscose having a xanthate ratio of at least about 50 and a viscosity of less than about 150 poises, into a primary aqueous acidic precipitation bath to form gel filaments under substantially non-stretched condition,.said primary bath contain-' ing 40-180 gms./l. of sulfuric acid,. 150-400 gmSL/l. of sodium sulfate and 10-150 gms./l. of zinc sulfate and being maintained at a temperature of about 45 to C., said gel filaments being controlled to be within 20-40 in residual xanthate ratio,

(2) passing the resultant filaments, under substantially non-stretched condition, through a secondary bath containing 5-30 gins/1. of sulfuric acid, 30-120 gins/l. of sodium sulfate and 0-100 gms./l. of zinc sulfate and being maintained at a temperature of about 5 to 30 C., said gel filaments being controlled to be within 20-40 in residual xanthate ratio immediately prior to stretching, and I (3) stretching said filaments more than twice while passing them through a third and fourth bath, said third bath being at least equal in regenerating power to the secondary bath, and containing 10-50 gms./l. of sulfuric acid, 30-120 gms/i. of sodium sulfate and 0-100 gms/l. of zinc sulfate and being maintained at a temperature of about 10 to 50 C., said third bath reducing the residual xanthate ratio by at most 70%, said fourth bath containing 30-100 gms./l. of sulfuric acid and 0-200 gms./l. of sodium sulfate and being maintained at a temperature of above 50 C., the stretch at said third bath being 30 to and at said fourth bath, 10 to 80%, and

each successive bath in the plurality of baths being at least as strong in regenerating power as its preceding bath.

2. A process as claimed in claim 1 wherein the viscose is about 50-100 poises in viscosity, the primary bath contains 60-150 g./l. of sulfuric acid, 180-300 g./l. of

sodium sulfate, 40-80 g./l. of zinc sulfate and is maintained at a temperature between 55 C. and 65 C., the secondary bath contains 10-25 g./l. of sulfuric acid, 80- 100 g./l. of sodium sulfate and 10-30 g./l. of zinc sulfate and maintained at a temperature between 10 C. and 20 C., the third bath contains 25-30 g./l. of sulfuric acid, 50-80 g./l. of sodium sulfate and 10-30 g./l. of zinc sulfate and maintained at a temperature between 25 C. and 35 C., the fourth bath contains 50-70 g./l. of sulfuric acid, less than 30 g./l. of sodium sulfate and maintained at a temperature between 80 C. and 100 C., the stretch at the third bath being 50-80% and the stretch at the fourth bath being 30-50%, and the residual xanthate ratio just before entering the third bath being 25-35%.

3. A process as claimed in claim 1 and particularly useful for the production of regenerated cellulose filaments having the property of spontaneously crimping upon being immersed under relaxation in an aqueous liquid, wherein the viscose is 65-75% in the viscose xanthate ratio (gamma number) and the primary bath contains 70-100 g./l. of sulfuric acid, 250-350 'g./l. of sodium sulfate and 40-70 g./l. of zinc sulfate and is maintained at a temperature between 65 C. and 75 C., the rate of regeneration at the secondary bath being controlled so that the filaments just before entering the third bath preferably have a residual xanthate ratio of 30-40% 4. A process as claimed in claim 1 wherein the viscose is more than about poises in viscosity, the primary bath contains less than 60 g./l. of sulfuric acid, less than 100 g./l. of sodium sulfate and less than 5 g./l. of zinc sulfate and is maintained at a temperature between 0 C. and 30 C., the secondary bath contains less than 30 g./l. of sulfuric acid, 20-80 g./l. of sodium sulfate and is maintained at a temperature between 0 C. and 30 C., the third bath contains less than 30 g./l. of sulfuric acid, 20-80 g./l. of sodium sulfate and is maintained at a temperature between 0 C. and 30 C., and the fourth bath contains 30-100- g./l. of sulfuric acid and 50-150 g./l. of sodium sulfate and is maintained at 23 a temperature above 20. C., the stretch at the third bath being 3 0 l5 0% and the stretch at the fourth bathbeing -50%..

5. A,proce ss asclaimed in claim 1 wherein the-primary bathcontains.1545 g./l. of sulfuric acid, -70 g. -/l. of sodiumfsulfa'teand. less than 1 g./1. of zinc sulfate and.is-maintained atatemperature between 5 C. and 20 C., the secondary bathcontains 5-15-g.'/l. of sulfuric acid, 40. .60 g./l. o f so dium sulfate and is maintained a-tlatemperature between. 5 C. and 20 C., the third bath contains-5 15 g./l. of sulfuric acid, g./l. of.sodiun1 sulfate and is maintained at'a temperature between 5 C. and 20 C., and the fourth bath contains 40 70..g. l. of sulfuric acid'and g./l. of sodium sulfate andfismaintained at, a temperature between :30 C. and 70 C., the stretch at the third bath being 60- and the-stretch at the fourth bath being 10-30%, and theresidual xanthate ratio just'before entering the thirdbathbeing,25 35%.

6. A processaccordingtoclaim l wherein the.viscose. contains dissolvedtherein about 0.1 to 10 millimoles per 100.;grar'ns of the viscose of a coagulation modifier which lowers the-degree of primary gel swelling of the viscose filaments.

7. A process for treatingfilament produced according to a process-as claimedin claim. 1, which comprises applyingjo the filament a solution of a salt of melamine and an oxy.acid,j exposing the filament to a formaldehydevapor in thepresence of .a small amount of-water, andthensubjectingthe ,filamentto a heat treatment.

8. A. process as..claimed. .in claim 7 whereinthe salt consists of melamine and'an-oxy acid inthe proportions of 0.3-3.0 moles of the oxy .acid per mole of melamine. 35

9. Aprocessasclaimed in claim 7 wherein the solution contains 0.5 to 4% of the salt.

10. A process as claimed in claim 7 wherein the reaction of formaldehyde with melamine is effected in the presence 01510 to 30%, based upon the weight of the product, of water;

11. A process as claimed in claim 7 wherein the amount of formaldehyde is about 2 to 5 moles per mole of melamine as contained in the fibres.

12. A process as claimedinclairn 7 wherein the heat treatment is carried out at a-temperature of 120160 C. for a period of time necessary-to set the resin.

13. Procession treating fibers which comprises (a) applyingrto said fibers a 0.5 to 4% solution of a'salt-com sistingof'melamine and an oxyacid in the proportions of 0.3 to 3.0 moles of the oxy acid per mole of melamine, r

(b) exposing. the fibers to formaldehyde vapor, the amount of formaldehyde being about 2 to 5 moles per mole of melamine applied'to the fibers, in the presence of from l0.to:30%, based upon the weight of the prodnet, .of water, and- (c) setting-the formed resin at a term" perature of from 120 to C.

References Cited in the file of this patent UNITED 'STATES' PATENTS 2,192,074 Givens et al. Feb. 27, v1940 2,327,516 Fin k et al. Aug-24, 1943 2,427,993 McLellan Sept. 23, 1947 2,479,218. Dosne Aug. 16, 1949 2,517,694 Merion et al. Aug. 8,1950 2,611,928 Merion et al-.- Sept. 30, 1952 2,715,763 Marley Aug. 23, 1955 2,858,185 Schappel Oct. 28, 1958 2,894,802 Braunlich -July.14, 1959

Claims (1)

1. PROCESS FOR PRODUCING REGENERATED CELLULOSE FILAMENTS WHICH COMPRISES (1) EXTRUDING HIGHLY XANTHATED VISCOSE, CONTAINING 3-11% BY WEIGHT CELLULOSE AND 3-13% BYY WEIGHT TOTAL ALKALI, SAID VISCOSE HAVING A XANTHATE RATIO OF AT LEAST ABOUT 50 AND A VISCOSITY OF LESS THAN ABOUT 150 POISES, INTO A PRIMARY AQUEOUS ACIDIC PECIPITATION BATH TO FORM GEL FILAMENTS UNDER SUBSTANTIALLY NON-STRETCHED CONDITION, SAID PRIMARY BATH CONTAINING 40-180 GMS./1. OF SULFURIC ACID, 150-400 GMS./1. OF SODIUM SULFATE AND 10-150 GMS./1. OF ZINC SULFATE AND BEING MAINTAINED AT A TEMPERATURE OF ABOUT 45 TO 80*C., SAID GEL FILAMENTS BEING CONTROLLED TO BE WITHIN 20-40 IN RESIDUAL XANTHATE RATIO, (2) PASSING THE RESULTANT FILAMENTS, UNDER SUBSTANTIALLY NON-STRETCHED CONDITION, THROUGH A SECONDARY BATH CONTAINING 5-30 GMS./1. OF SULFURIC ACID, 30-120 GMS./1. OF SODIUM SULFATE AND 0-100 GMS./1. OF ZINC SULFATE AND BEING MAINTAINED AT A TEMPERATURE OF ABOUT 5 TO 30*C., SAID GEL FILAMENTS BEING CONTROLLED TO BE WITHIN 20-40 IN RESIDUAL XANTHATE RATIO IMMEDIATELY PRIOR TO STRETCHING, AND 9 TAINED AT A TEMPERATURE OF ABOUT 10 50*C., SAID (3) STRETCHING SAID FILAMENTS MORE THAN TWICE WHILE PASSING THEM THROUGH A THIRD AND FOURTH BATH, SAID THIRD BATH BEING AT LEAST EQUAL IN REGENERATING POWER TO THE SECONDARY BATH, AND CONTAINING 10-50 GMS./1. OF SULFURIC ACID, 30-120 GMS./1. OF SODUIM SULFATE AND 0-100 GMS./1. OF ZINC SULFATE AND BEING MAINTHIRD BATH REDUCING THE RESIDUAL XANTHATE RATIO BY AT MOST 70%, SAID FOURTH BATH CONTAINING 30-100 GMS./1. OF SULFURIC ACID AND 0-200 GMS./1. OF SODIUM SULFATE AND BEING MAINTAINED AT A TEMPERATURE OF TO 100% AND AT SAID FOURTH BATH 10 TO 80%, AND EACH SUCCESSIVE BATH IN THE PLURALITY OF BATHS BEING AT LEAST AS STRONG IN REGENERATING POWER AS ITS PRECEDING BATH. ABOVE 50*C., THE STRETCH AT SAID THIRD BATH BEING 30

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