USRE22489E - Method of improving the processing - Google Patents

Description

at a stage prior to Reissues! May 30, 1944 METHOD OF IMPROVING F REFINED CHEM! CAL rnn rnocsssmc runes m'ro vis- COSE BY ADDING ANION ACTIVE AGENTS Paul Henry Salomon-Kenneth Russell Gray, and

Earl Grand Hallonqnlst, signers to llayonler Incorporated, San

Shelton, Willi. al-

Fran

co,.Caiii., a corporation of Delaware No Drawing.

ber 19, 1943, Serial Original No. 2,331,985, Cited Octo- No. 321,894, March 1, 1940.

Application for reissue April 8, 19M,

14 Claims. (01. 28021'I] Our invention relates to improving the processing of refined chemical pulp into viscose by adding anion active agents.

More particularly, our invention relates to the adding of anion active agents to refined chemical pulp or to one of the viscose forming materials completion or xanthation to provide an improved viscose solution. These solutions in turn are designed to be used in further manufacturing processes. The viscose solutions resulting from our invention or discovery may be employed in the manufacture of cellulose products, as artificial yarn or rayon, staple fiber, transparent films, or sausage casings.

While our invention relates primarily to improvements in the preparation of, cellulose solutions by the viscose process, it should be understood that the principles involved are 0! a broad nature and may be applied also to the preparation of cellulosic solutions of other types, such as cuplammonium solutions of cellulose agd solutions of cellulose derivatives, such as cellulose acetates, nitrates or others.

' In all these instances the objective is to bring the cellulose into proper solution and the providing for this constitutes the primary object of our invention.

Specifically our invention provides a great improvement in most of the steps, such as shredding, xanthati g, dissolving, filtering, and emulsifying or disper ing, which steps are involved in forming viscose solutions and preparing the same for use for further manufacturing processes.

Accordingly, for purposes of definiteness and clearness of description and illustration, our invention will be set forth as respects the steps involved in forming viscose solutions and preparing the same for use in further manufacturing processes, but it is to be understood that the invention is not to be limited to any such specific application.

In general, our invention, for a summary statement may be said to relate to treating, with certain anion active agents, the pulp or one or more of the viscose forming materials at any stage prior to the completion of xanthation while such pulp is being formed into a solution by the viscose process.

The procedure in preparing viscose solutions ordinarily involves the treatment of cellulose withcaustic soda of about 18% concentration,

then with carbon bisulphide and finally dissolving the xanthated fibers, resulting in a cellulosic solution with a caustic soda content of 5-8 Since the viscose solution is essentially a cellulose solution, therefore it is desirable to keep all additions of foreign agents to an absolute minimum. Obviously, if any agent is to be added it should be present in very minute quantities and the question then arises as to whether it would be effective. Our invention comprises the discovery of agents which are very effective in greatly improving the preparation of the viscose, even when employed in very minute quantities and which at the same time are not otherwise objectionable.

In the customary manufacture of viscose solutions from refined chemical pulp for the spinning of artificial yarn or rayon, the pulp is subjected, in general, to the following steps, and the purpose of these steps is mainly as indicated:

Steeping.-The first step in the viscose process is known as steeping. Its purpose is mainly twofold, (l) to provide the pulp fibers with a certain amount of caustic soda necessary in the xanthating step and (2) to dissolve out certain impurities such as hmicelluloses. In steeping, the pulp, commonly employed in sheet form, is immersed in caustic soda solutions of mercerizing strength, as commonly used about 18%, and thereafter removed and subjected to pressing to eliminate part of the adhering caustic soda, together with the'greater part of the dissolved impurities. The product after steeping is known as alkali cellulose. The action of the caustic soda in this steeping process should be uniform and complete, otherwise there would be parts of the fibers improperly prepared for xanthating.

SnreddingL-The second step in the viscose process is that of shredding the alkali cellulose. Its purpose is the comminution of the sheet structure which still remains on completion of the steeping process. One object of this comminution is to properly expose the individual fibers to the action of oxygen for proper alkali cellulose ageing, i. e., ,to permit the lowering of viscosity.

A second purposeof this comminutionis to expose all portions of the fiber so that'in the xanthating step where carbon bisulphide is added,

all of the individual fibers will be completely treated.

ening.

1 thated cellulose if properly formed,- dissolves readily in dilute caustic soda to form the solu tion commonly known as viscose. C

Ripeuing.-Immediately on solution of the xanthated cellulose in dilute caustic soda, certain chemical reactions take place, which gradually alter the chemical and physical properties of the viscose. These reactions are allowed to proceed to a definite extent under controlled conditions in order to impart the desired properties to the viscme necessary for satisfactory spinning. This operation is known as viscose Filtering. In the viscose solution there is usually a certain amount of undisolved fibers and gel-like material due to incomplete reaction of the cellulose fibers with the carbon bisulphide during xanthation. In the course of the ripening period the viscose. solution is filtered several times to remove these gels and undlssolved fibers. Thisis of importance as otherwise the fine openings in the s'plnnerets through which the viscose is extruded during the subsequent spinning process would soon become clogged.

Emalsijmng or dispersina.lf the viscose solution is spun without further treatment, a high lustre yam results. In marry cases it is desirable to manufacture a yarn with subdued lustre, and this result may be obtained by emulsifying or ripening.

dispersing small amounts of mineral oil or other immiscible materials in the viscose. Naturally it is of importance that these emulsions or dispersions be characterized by uniform minuteness of particle size in order to avoid breaking or weakening of the filaments by the interruption of the constant fiow of viscose through the minute orifices of the spinneret. Further the emuls sions or dispersions must be characterized by extreme stability, in that they must not detericrate during the period required for viscose rip- Normal dissolving pulps in present use consist mainly "of cellulose but contain appreciable amounts of non-cellulosic impurities such as hemicelluloses, fats, resins, waxes, etc. One of the main objects in the manufacture of a satisfactory dissolving pulp is to remove as much as possible of the non-cellulosic impurities, so that a whiter, purer pulp results which is capable in general of producing a higher .grade yarn.

We find, however, that not all the non-cellulosic materials which can be removed are undesirable and in fact that certain of such impurities normally present in small amounts are h y beneficial in the steps involved in the preparing of the viscom solution. These beneficial impurities for the most part are surface active materials or materials which can give'rise to the production of surface active materials during the steps of steeping or the other steps prior to completion of xanthation in the manufacture of rayon. In apulpwhichhasnotbeenhlghly refined. these beneficial substances which are of cacao the nature of fats, resins and waxes constitute a portion of the materials which are removable I by organic solvents, for example ether, benzene. alcohol, etc. In general we find there is a direct relationship between filtration of the viscose and the ether extract of the pulp. n

In theory. the problem of making a good pulp would be solved by removing all the undesirable. and retaining all the desirable substances. In practice, such a clean-cut separation is diilicult to accomplish directly. We have discovered that better results are obtained by removing most of or all the undesirable materials without regard to the beneficial portion thereof and then to add to the pulp a sufliaient amount of materials or agents having a similar action to the natural beneficial portion. Let it be noted that our invention lays no claim in connection with the purification of pulp to a certain degree of purity. White, highly purified pulps are very advantageous in the production of high grade yarns and for this reason are highly desired by the trade. Such high grade pulps are in general not yield the'highest grade yams, nevertheless their processing into viscose is relatively simple and thus in such pulps there is usually little need 9 for our invention.

We have discovered that there are agents, some chemically similar to, and some chemically difierent from, that portion of the impurities naturally present providing beneficial action. In

48 general theagents which we have discovered are much more eifective than the beneficial portion of the impurities naturally present. Accordingly, the compounds or agentsof our discovery can be used in very minute quantities. This is doubly l0 advantageous, because such additions of materials are inexpensive and also because the very pure pulp treated with our agents is substantially free from non-cellulosic materials due to the minuteness of the quantity of theagents required.

' The surface active portion of the beneficial impurities, naturally present as such in the refined pulps or formed during the processing, are predominately of the general class known as anion active materials. By surface active agent" we mean, for purposes herein set forth, such fsuriace active agen which are at least dispersible in viscose solutions.

If agents of the anion active class are to be added directly to the pulp as such, 1. e., while in the sheet or prior to its formation, they should be of the class which is substantially insoluble in caustic soda of the usual steeping concentration. The reason for this is that otherwise the agent or agents will be largely extracted from the 70 pulp bythe mercerizing caustic soda used in the steeping step. The final caustic soda concentration of the viscose solution will be from 54% and, heretofore it was thought necessary that only those anion active agents should be employed which are substantially soluble in such eases To adopt both the above limit the agents to dilute caustic soda. solubility requirements would be used for treating the pulp to that group are insoluble in 18% caustic soda but soluble in -896 caustic soda solutions and the surface active agents of this group are very limited in number. Our experiments establish that of these few agents those that are available are not satisfactory or are undesirable in achieving the improvements herein set forth. We have found, however, that it is not necessary to limit ourselves to the use of materials which are soluble in 54% caustic soda. Our experiments show that there are a great many anion active compounds which are substantially insoluble in 18% and also substantially insoluble in 54% caustic soda concentrations and that they can be added to the pulp with the beneficial results in the various subsequent steps as will be herein, set forth. The agents of this class of our discovery become dispersed in the viscose in a very fine state and hence tend to make the viscose slightly turbid, but such viscose solutions, nevertheless, are entirely satisfactory for most purposes and are improved in their properties as will be herein set forth.

Our experiments show that our agents neither beneficially contribute to or interferewith the penetration or wetting of the pulp in the steeping step. In short, the improvement brought about by our agents does not relate primarily to which .In the initial use of such a treated pulp commercially the added agents would be in part, though not completely, extracted by the caustic sodain the steeping operation. The steeping caustic soda however, is largely re-used and after a number of steeping operations an equilibrium would eventually be reached where the added agent would be largelyretained by the pulp. In the rayon industry, however, the maintenance of the utmost uniformity is considered an extremely important requisite and for this reason it is much more practical to restrict'treatment of the pulp by anion .active agents to those agents which are insoluble in mercerizing caustic. As regards use of anion active agents subsequent to steeping it is of course practical to use either the class insoluble in 18% caustic soda or the soluble class.

If addition of anion active materials is made to the viscose solution, such additions merely lower the surface tension of the spinning solution or influence the coagulating conditions during spinning. We have discovered, however, that the great advantages and improvements in the the penetration or wetting of the pulp. For instance, if only portions of the pulp employed in the manufacture of the viscose solution are treated with our agents, nevertheless there is no appreciable lessening of the improvements resulting from the use of our agents as respects the subsequent steps. The agents of our invention or discovery need not be applied to each or every sheet of the pulp, but such agents may be applied to alternate sheets of said pulp or to only a portion of the pulp material being processed into viscose. Moreover, our agent or agents can be added after steeping, for example during the shredding operation and yet nearly the full benefits of our invention accrue as if our agents were added to the original pulp itself. However, there ,are advantages in adding our agents to the pulp, firstly as a matter of convenience and secondly, in that a very uniform distribution is assured.

Our experiments also have shown that there are many anion active compounds which are soluble in 18% and soluble in 5-8% caustic soda concentrations, and that these can be added to the material being-processed into viscose prior to the completion of xanthation with beneficial re,-

sults. These anion active agents which are soluble in both concentrations of caustic soda may be added to the steeping solutions or they may be applied to the shredded pulp during the shredding step or at any stage prior to the completion of xanthation.

-Accordingly, we have discovered that as respects anion active materials, that those anion active materials are applicable which have a solubility characteristic which is the same both in 18% caustic soda solutions and in the 5 to 8% caustic soda solutions. In other words, the compounds may be either insoluble in both concentrations of the caustic soda or may be soluble in both concentrations.

In connection with using anion active agents to treat the pulp it should be noted that it is possible to demonstrate experimentally, beneficial improvements through use of the class of matevarious steps of viscose manufacture as will be herein set forth accrue only provided such materials or agents are added to the pulp or to the materials being processed prior to the completion of xanthation.

If these materials are added after xanthation, a viscose product of improved characteristics, such as is obtained when the said reagents are added prior to the xanthation step is not obtained. It is noteworthy that.the viscose of our invention is characterized by being particularly free from undissolvedor partly dissolved fibers which greatly facilitates subsequent filtrations. We have found that any filtration improvements which may be obtained by subsequently adding surface active materials to the viscose itself stood that all conditions and temperatures normally employed in the preparation of viscose may be employed with the use of our agents.

1. Steeping.-In the steeping process the action of the caustic soda should be uniform and complete; otherwise there would be parts of the fibers improperly prepared for xanthation. This uni,- formity of penetration can be. properly insured by, mechanical means, i. e., by correct sheet structure,

and proper manipulation in the steeping opera-- tion. Our invention does not in any way relate to improved steeping properties of the sheet. The presence of our agents in the pulp in the concentrations employed by us during this steepin process does not'to our knowledge affect the normal wetting and penetrating action of the caustic.

2. Shredding.-A principal object of shredding is comminution of the sheet structure in order to expose all portions of the fibers to the action of carbon bisulphide in the subsequent xanthating step. It is also important that this comminution can be brought about without excessive mechanical action on individual fibers and it is thus an advantage to have an alkali cellulose which will shred up readily. The pulps treated with our rials soluble in mercerizing (18%) caustic soda.

v nigh moon longer time. H This result is of extreme importancgsince it cannot be realized otherwise suchas by merely agents disintegrate much more easily and com- 'pletely in the. shredding operation. In other words, our agents. we have discovered, bring about a very positive opening up of the fibers over and above that which occurs when the pulp or alkali cellulose is not treated with our agents. This increased degree of comminution is evidenced by an increase in the volume of the shreddai crumb. With unchanged time, this increase may amount to 25 percent. On the other hand shorter shredding times are possible, resulting in considerable there is an interference with normal processing.

erties 'ortne finished viscose solution, so that 0n the other hand our discovery includes the unexpected result in. the xanthation reaction,

saving in power as well as time. Examples oi? the decrease in apparent density of the shredded alkali'cellulose produced by theaddition of surface active agents when using refined chemical pulp are shown'in Tamer. It is to be notedthat no such decrease in apparent density took place when using rayon-grade cotton linters.

' Tan: 1

that with the use of our agents it is also possible to use lesser amounts of carbon bisulphide than are normally employed in xanthating. The quantity of carbon bisulphide involved in producing.

viscose is fairly standard and accordingly it was very unexpected that our discovery or invention should result in producing viscose of satisfactory quality with a smaller amount or carbonbisub phide than heretoiore has been found necessary to produce yarn of a'given quality. This has the direct result of lessening the viscose ripening time, as well as a saving or chemicals-thus lessening the production cost.

It has been stated above that with the use of.

Eflectof treatment with onion active. materials prior to completion oj, shredding on the apparent density of the shredded alkali cellulose Apgarent dmsity oi V m d M s tglddad alkali -ee wen... s... we

Untreated Treated (a) usmo RE-FXNED CHEMICAL, PuLPs CONTAINING APPROXIMATELY 0.065% n'rnsa EXTRACT Y 7 Fatty acidsosps I arm in 1k; lsul a tea A ary p on: 5

Sulphated iatty alcohols"; .195 .175 1 Sulphonated others 195 175 r Sulphonated na hthsnlc acid .105 .170 Phoerhoratedo V .195 .175

ysulphonatedoil .196 .180

(0) came nlivon-oasnncorrorq Lm'rnns Boap To Ilium--.

It will be evident that the improvement in the comminution of the alkali cellulose. resulting from I our invention may be appliedto oth'er fields than that of viscose, e. g. the preparation of cellulose ethers and cuprammonium solutions from pulp by V processes using shredded alkali cellulose.

3. Xanthati0n.--The pulps treated with our 7 agents xanthate much more completely and-uni- Iormly. This is probably due in part toimprovements in the prior step of shredding, but as evidenced from our experiments, is alsodue in part to an actual improvement of the xanthation reaction itself.- This improvement in the xanthation from undissolved fibers and partly dissolved fibers or gels. This is very advantageous in that when the'viscose is subsequently filtered,- nitration is much more rapid and the filters remain-open tor a using an unduly large excess of carbon'bisulphide in the xanthation reactionexcesses not only alter the properties 01' the :nanthated crumb m n undesirable manner, but also alter-the prop- 75 our agents it is possible to use lower amountsot carbon bisulphide than normally employed in xanthating and to thus shorten the ripening time. Under'normal conditions the use of less carbon use vof smaller amounts of carbon bisulphidelies in the fact that the tendency toward undesirable milkiness in the rayon is materially minimized.

4. Dissolving.--The thoroughness and uniformity of the xanthation reaction when carried out .with the use of surface active agents according to our invention is evidenced by the low number of partially reacted and unreacted fibers remaining after the xanthated product is dissolved in dilute caustic soda. Microscopic comparison of normal viscose preparations with viscose prepared using surface active agents according to our invention show very substantial reductions in undissolved and partly dissolved fibers as can be seen from Table II. Such reduction in the amount of undissolved fibers and gels was not obtained in the similar using rayon-grade cotton linters.

experiments Eject 0] treatment with onion active materials prior to completion of mtho'tion on the amount of undissoloed and partially dissolved fiberb in the viscose Total numbc oi undissolved and partially m of we 3%? ffi Where seam MM film/w- Untreated Treated (a) USING BEF INED CHEMICAL PULPB CONTAINING APPROXIMATELY 0.006%

ETHEB EXTRACT .05 0 sodium oleate To pulp Over 500 so Fatty acid soaps .1 sodium fln 1, 700 02 .1 sodium oi do 442 42 Resin acid soaps .15 rosin soap do Over 500 1a Soap lorming materials .l lfi linseed o g Ovei 7 g A ikln (1 19mm! "Bantomerse No. 3". do Ov r 500 7: Highly euipbonnted oil .06 o "Preetabit V" To steeping caustic.. l, 700 42 (b) USING RAYON-GRADE COTTON LINTERS gf x g g l mwnwi ver 1,332 over og a o Alkyl sryl sulphonates ns Nm an 1' m2 1:118

5. Filtration-Our inventionremarkably tacilbrought about by our agents over normally preitates the yarious filtration steps which the vispared vismse when using a, refined chemical pulp cos'e undergoes subsequent to xanthation. This 30 are shown by the laboratory filtration data in increase in filtration rate is due at least in part Table III. It will again be noted that no such to a very substantial reduction in undissolved improvement was obtained when rayon-gradeilbers and gels which are very efiective in clogcotton iinters were used.

' TABL: III

Efiect of treatment with. union active material: prior to completion of :canthation on the viscose filtration rate Viscose filtration rate A t 1 per sq. cm. per Type or material $31 5 5? gag Where added m Untreated Treated (a) USING BEIINED CHEMICAL PULPS CONTAINING APPROXIMATELY 0.086 ETHER EXTRACT sodium oleate.- 5'27 625 Fatty acid soaps sodium olent 176 810 sodium cl 275 710 Resin acid soaps rosin mp 175 370 new." 2:: r2 v n Soap forming materials I myeolvoleateu 33o 510 hemlock n. 62'! 690 Alksnol 275 910 Alkyl u sun, m NR" 175 750 Blntomerse No. 3".-. 527 590 Sulphsted fatty alcohols sodiumlaurylsulphate. 527 678 Bulphonated ether .06. "Tensol No. 52" 521 775 Sulphonated naphtbcnic acid a lulngilaonated nnph- ML 690 I m Phoephorated oil .05 phosphoratedcsstoroii. -.-.do I 52! 790 H! m on {.06 rrestabitl Tostee ingeeustie 325 655 I .05 a I A it v"- 8pm inshredder; w 700 (b) USING RAYON-GRADE COTTON LINTERB 240 210 240 270 Bosp iorming materials 53g 195 Alkyi aryl sulphonstes 290 52g gins the filtration medium. If the product is Table IV shows: (11 That to obtain the greatrelatively free of undissolved or partially dis- 7o er part of the improvement it is not necessary solved fibers or gels, the filter medium will conto provide a uniform distribution of the surface tinue unclogged for long periods eliminating active'agents in the pulp sheet, which in turn irequent interruptions of the filtering process to demonstrates that our invention is not primarily permit the installation of fresh filtering media. concerned with an improvement in wetting 015 This is obviously a distinct advantage. pulp sheets during steeping and (2) that it is Examples of the improvement in filtration absolutely necessary to add the surface active materials before completion of xanthatlon in order to obtain the improvement claimed in our invention.

TAIL! IV Eflect of method of adding anion active materials to viscose process [Using refined chrmical pulp of 0.080% ether extract] Total number of 6. Emulsificctioml'he use of anion active agents according to our invention substantially improves the ease with which mineral oil may be dispersed in the viscose and the stability of emulsions thus formed in the production of delustered yarns. 'These anion active agents of our discovery provide emulsions characterized by minuteness of particle size.

The particular anion active agents of our discovery, orthe agents giving rise thereto, may be classified as follows:

A. Agents substantially insoluble in both approximately 18% caustic soda and 5 to 8% caustic soda 1. Soaps-alkali salts fatty acids, e. g. sodium oleate.

2. Soaps-alkali salts of resin acids, e. g. sodium rosinate.

3. Soap forming agents-natural and synthetic fats, fatty and resin acids, etc, e. g. coconut oil, linseed oil, soya bean oil, cottonseed oil, glycol dioleate. oleic acid, rosin, tall oil (comprising resins, iats, waxes, etc. from wood). These will be transformed into soaps in the steeping step.

4. Alkyl aryl sulphonates, e. g. "Alkanol B,

"Nacconol N- R., (Santomerse #3."

5. Sulphated fatty alcohols. e. g. sodium lauryl sulphate.

6. Sulphonated ethers substantially insoluble in both approximately 18% caustic soda and to 8% caustic soda, 0! which one sold under the trade name of Tensol #52, is found very suitable in our invention.

7. Sulphonated naphthenic acids.

8. Phosphorated oil, e. g., phosphorated castor oil.

' B, Agent3 soluble in both. dpm'oflmatelp 13% 1 caustic soda and Sto 8% cuusticsoda The eifective range of the compound employed has been found by us. to be from 95% to 15%. With 0.01% some of the improvements of our Invention begin to manifest themselves and this eflect increases as the concentration increases up to about .1%. Thereafter there seems to be little improvement 1. e., in filtration. There are dmadvantages to using higher concentrations than .15% other than the matter of expense. As

regards treatment of the pulp such higher con-' centratious would cause excessive softness in the sheet resulting in mechanical diiiiculties in steeping. Also the viscose obtained would be excessively turbid andthere would even be dangers of clogging .the filters or of obtaining poor yam. Furthermore with either the material insoluble in 18% caustic soda or those soluble in 18% caustic soda. hi her concentrations ,of the agents cause dimculties, in xanthation due to excessive ball formation, in dissolving due to excessive foaming and subsequently in tie-aerating the viscose.

It will be understood that the use of anion active agents according to our invention is not subiect to any limitations as to the methods oi appllcatio'n other than that the materials be added prior to the completion of xanthation. Practical methods for, carrying out the invention include both treatment of the pulp prior to use in the viscose process and the introduction oi the agents at some point during the processing of the pulp into viscose prior to the completion of xanthation. In

the latter case, for example, the agents may be sprayed into the shredder prior to the completion of shredding or if they are of the class soluble incaustic soda of memorizing strength, they may be dissolved in the steeping caustic solution.

As regards treatment of the pulp with the agents oi'ourdiscoverypriortouseintheviscose -substantially the same refined chemical Pulp process, examples of practical methods of treatment follow though it is to be understood that our invention is not limited to any specific method of application. A very suitable point in pulp manufacture for treatment with anion active agents is the addition to the pulp on the machine Subsequent to sheet formation but prior to drying. The agents can be suitably added from aqueous solutions either by means of sprays or by means of a rotating roll partly immersed in the treating solution.

It is also possible to treat the pulp while in s spension prior to sheet formation as for example in a stock chest, but this would necessitate,

the almost complete re-use of the white water on the machine without diversion to other parts of the plant in order to prevent excessive loss of the materials and to prevent interference with other parts of the process.

We claim:

1. The method of improving the processing of containing not more than 0.15%. ether extractable matter into viscose. comprising forming refined chemical pulp containin not more than 0.15% ether extractable matter into an alkali cellul shredding said alkali cellulose; reacting said shredded alkali cellulose with carbon dlsulphid whereby xanthation occurs; providing a viscose which comprises the.

reaction products of said shredded alkali cellulose and said-carbon disulphide: and adding at a stage prior to completion of xanthation a surface active agent of the anion active class 'which has solubility characteristic of both mercerinng and strengths normally P esent in in caustic sodasolutions the more dilute vis ose.

saidagentsbeingaddedinthemgeof aasso 7 0.01% to 0.15% by weight, such percentages being based upon the weight or the bone dry pulp.

2. The method of improving the processing of refined chemical pulp containing not more'than 0.15% ether extractable matter into viscose, comprising iorming refined chemical pulp containin not more than 0.15% ether extractable matter into an alkali cellulose; shredding said alkali cellulose: -reacting said shredded alkali cellulose with carbon disulphide, whereby xanthatlon occurs; providing a viscose which comprises thereaction products of said shredded alkali cellulose and said carbon disulphide; and adding at a stage prior to completion or xanthatlon a surface active agent 01' the anion active class which is substantially insoluble in caustic soda solutions of both mercerizing and the more dilute strengths normally present in viscose, said agents being added in the range of 0.01% to 0.15% by weight, such percentages being based upon the weight of the-bone dry pulp.

3. The method of improving the processing of refined chemical pulp containing not more than 0.15% ether extractable matter into viscose, comprising forming refined chemical pulp containing not more than 0.15% ether extractable matter into an alkali cellulose; shredding said alkali cellulose; reacting said shredded alkali cellulose with carbon disulphide, whereby xanthatlon occurs; providing a viscose which comprises the reaction products of said shredded alkali cellulose and said carbon disulphide: and adding at a stage prior to completion of xanthatlon a surface active agent of the anion active class which is substantially soluble in caustic soda solutions of both mercerizlng and the more dilute strengths normally present in viscose, said agents being added in the range of 0.01% to 0.15% by weight, such percentages being based upon the weight of the bone dry pulp.

4. The method oi improving the processing of refined chemical pulp containing not more than 0.15% ether extractable matter into viscose, comrising iorming refined chemical pulp containing not more than 0.15% ether extractable matter into an alkali cellulose; shredding said alkali cellulose: reacting said shredded alkali cellulose with carbon disulphide, whereby xanthatlon occurs: providing a viscose which comprises the reaction products of said shredded alkali'cellulose and said carbon disulphide; and adding at a stage prior to completion of xanthatlon a surface active agent of the anion active class of the alkyl aryl sulphonate group in the range or 0.01% to 0.15% by weight, such percentages being based upon I the weight or the bone dry pulp.

5. The method of improving the processing of refined chemical pulp containing not more than 0.15% ether extractable matter into viscose, comprising forming refined chemical pulp containing not more than 0.15% ether extractable matter into an alkali cellulose: shredding said alkali cellulose: reacting saidshredded alkali cellulose with carbon disulphide. whereby xanthatlon occurs: providing a viscose which comprises thereactlon products of said shredded alkali cellulose and said carbon disulphide; and adding at a stage prior to completion of xanthation a fatty acid soap in the range of 0.01% to 0.15% by weight, such percentages being based upon the weight oi the bone dry pulp.

6. The method of improving the processing of refined chemical pulp containing not more than 0.15% ether extractable matter into viscose, comprising forming refined chemical pulp containing not' more than'ii.15% ether extractable matter into an alkali cellulose; shredding said alkali cellulose; reacting said shredded alkali cellulose with carbon disulphide, whereby xanthatlon -occurs; providing a viscose which comprises the reaction products 01 said shredded alkali cellulose and said carbon disulphide; and adding at a stage prior to completion of xanthatlon sodium action products of said shredded alkali cellulose and said carbon disulphide: and adding at a stage prior to completion of shredding a surface active agent of the anion active class which ha substantially the same solubilityv characteristic in caustic soda solutions of both mercerlzing and 5-8% strengths, said agents being added in the range of 0.0 to 0.15% by weight, such percentages being based upon the weight of the bone dry pulp.

8. The method of improving the processing of efined chemical pulp containing not more than 0.15% ether extractable matter into viscose, comprising iorming refined chemical pulp containing not more than 0.15% ether extractable matter into an alkali cellulose: shredding said alkali cellulose: reacting said shredded alkali cellulose with carbon disulphide, whereby xanthation occurs; providing a viscose which comprises the reaction products of said shredded alkali cellulose and said carbon disulphide; and adding to the pulp prior to use a surface active agent of the anion active class which has substantially the same solubility characteristic in caustic soda solutions of both mercerizing and the more dilute strengths normally present in viscose, said agents being added in the range of 0.01% to 0.15% by weight, such percentages'beingbased upon the weight of the bone dry pulp. V

9. The method of improving the processing of refined chemical pulp containing not more than 0.15% ether extractable matter into viscose, comprising forming refined chemical pulp containing not more than 0.15% ether extractable matter into an alkali cellulose; shredding said alkali cellulose; reacting said shredded alkali cellulose with carbon 1 disulphide, whereby xanthatlon occurs; providipg a viscose which comprises the reaction products of said shredded alkali cellulose and said carbon disulphide; and adding to the pulp prior to use a surface active agent of the anion active class which is substantially insoluble in caustic soda solutions of both mercerizing and the more dilute strengths normally present in viscose, said agents being added in the rangeof 0.01% to 0.15% by weight, such percentages being based I upon the weight of the bone'dry pulp.

10. The method of improving the processing of refined chemical pulp containing not more than 0.15% ether extractable matter into viscose, comprising forming refined chemical pulp containing not more than 0.15% ether extractable matter into an alkali cellulose; shredding said alkali cellulose; reacting said shredded alkali cellulose with carbon disulphide, whereby xanthatlon occurs; providing a viscose which comprises the I reaction productsof said shredded alkali cellulose and said" carbon disulphide; and adding to the pulp prior to use a surface active agent oi theanion active class of the alkyl aryl sulphonate group in the range or 0.01% to.,0.15% by weight, such percentages being based upon the weight oi the bone dry pulp. r I

l1.-The method, of improving the processing of refined chemical pulp containing not more than,0.15% ether extractable matter intoviscose, comprising forming refined chemical pulp containing not more than 0.15% ether extractable matter into an alkali cellulose; shredding said alkali cellulose; reacting said shredded alkali cellulose with carbon disulphide, whereby xanthation occurs; providing a viscose which comprises the reaction products of said shredded alkali cellulose and said carbon disulphide; and adding to the pulp prior to use a fatty acid soap in the range of 0.01% to 0.15% by weight. such percentages being based upon the weight of the bone dry pulp.

12. The method of improving the processing of refined chemical pulp containing not more than 0.15% ether extractable matter into viscose, comprising forming refined chemical pulp containing not more than 0.15% ether extractable matter. into an alkali cellulose: shredding said alkali cellulose: reacting said shredded alkali cellulose with carbon disulphide, whereby xanthation occurs; providing a viscose which comprises the reaction products of said shredded alkali cellulose and said carbon disulphide; and adding to a the pulp prior to use sodium oleate in the range of 0.01% to 0.15% by weight, such percentages being based upon the weight of the bone dry pulp. I

13. The method of improving the processing of refined pulp containing not more than 0.15% ether extractable matter into viscose, com- 4 prising forming refined chemical pulp containing not more than 0.15% ether extractable matter into an. alkali cellulose: shredding said alkali cellulose: reacting said shredded alkali cellulose withcarbon disulphide, whereby xanthation occurs; providing a viscou which comprises the reaction products of said shredded alkali cellulose and said carbon disulphide; and adding at a stage prior to completion of xanthation a soap alkali cellulose and said carbon disulphide; and

forming agent derived from a fatty acid, said agent being added in the range of 0.01% to 0.15% by weight, such percentages being based upon the weight oi the bone dry pulp, whereby a surface active agent of the anion active class develops prior to completion of xanthation.

14. The method of improving the processing of refined chemicalpulp containing not more than 0.15% ether extractable matter into viscose, comprising iorming refined chemical pulp containing not more than 0.15% ether extractable matter into an alkali cellulose; shredding said alkali cellulose: reacting said shredded alkali cellulose with carbon disulphide, whereby Xanthation occurs: providing a viscose which comprises the reaction products of said shredded adding to the pulp prior to use s. soap forming agent derived from a fatty acid, said agent being added in the range oi 0.01% to 0.15% by weight,

such percentages; being based upon the weight of the bone dry'pulp, whereby a surface active agent otthe anion active class develops priorto completion oi xanthation.

PAUL HENRY BCHIOSSER. KENNETH RUSSELL GRAY. EARL GRAND HALLONQUIST.