Patented June 8, 1948 2,442,973 UNITED STATES PATENT of FICE 2,442,973 TREATMENT OF TEXTILE MATERIAL WITH ALRALINE CELLULOSE ZNCATE SOLU TIONS Sidney M. Edelstein, Elizabeth, N.J. No Drawing. Application July 12, 1944, Serial No. 544,650 9 Claims. (C. 8-115.6) 2 This invention relates to the treatment of a shapes and sizes of the meshes, as in a mosquito textile material. More particularly it relates to netting. treating a textile fabric with a solution of cellu In general, a coating is applied to a textile lose in alkali metal zincate containing an excess material, as by passing a fabric through a solu of alkali over the amount required to convert the 5 tion of wood pulp in sodium zincate solution, add Zinc present to zincate, precipitating the cellulose ing a precipitating agent to precipitate cellulose from the solution upon the fabric and then wash upon the textile, and then washing and drying ing the thus coated fabric preferably to remove the product. most but not all of the zinc present, the zinc It is necessary that the washing of the fabric left being bonded by the coating to the fabric 0. with precipitated cellulose thereon be continued and giving special desirable properties to the until most of the zinc is removed. This is nec product. essary to give a clear, non-hazy film of the cellu This application is a continuation in part of lose. On the other hand, the washing is not to my copending application Serial No. 423,163, filed be continued until the last of the zinc is removed December 16, 1941, now abandoned, for Textile 5 if all of the special results from the cellulose zinc material and method of making, which, in turn, ate treatment of the fabric are to be obtained. contains subject matter derived from my appli Washing of the fabric with precipitated cellu cation Serial No. 407,445, issued as Patent lose coating adhered thereto is best effected for 2,322,427, on June 22, 1943. the present purposes so as to give removal of the The invention comprises the herein described 20 Zinc compound to about the extent obtained in product and the method of making it including the following manner: if the precipitation of the the incomplete removal of the zinc as stated cellulose is effected by treatment of the cellulose above. In a preferred embodiment the invention Zincate solution with a concentrated solution of Comprises application of the cellulose solution in alkali, the alkalinity remaining is partly removed alkali metal zincate to a fabric to be mercerized, 25 by Washing and then neutralized and in fact precipitating the cellulose from the solution by acidified with an acid such as dilute sulfuric acid. means of the mercerizing sodium hydroxide solu If the precipitation is effected initially by the tion, and then washing and drying the product, addition of an acid such as dilute sulfuric, then the precipitation by the mercerizing solution giv the additional acidification is of course unneces ing a product in which the stiffness or 'hand' 30 sary. In either case the acidified treated fabric of the coated textile is not reduced materially by is washed with water until most of the acid is repeated laundering. removed. Then the remaining trace of acid is The invention comprises also the addition of neutralized as by a dilute solution of sodium car an acid to cause precipitation of cellulose from bonate or ammonium hydroxide. That part of alkali metal zincate solution applied to a fabric, 35 the zinc which remains at the conclusion of the Washing the fabric and thus formed cellulose washing is precipitated by the carbonate or ann coating thereon until most but not all of the zinc monia treatment. In an alternative method, the present is removed, and then converting the re final neutralizing with soda or ammonia, is maining zinc to insoluble form, as by the addition omitted and the washing is discontinued when of an alkaline zinc precipitating agent such as 40 the pH of the washed goods is about 3 to 4. Sodium carbonate or ammonium hydroxide to The treatment of a fabric with the zincate establish a pH above 7. Solution, precipitation of the cellulose, and wash In a preferred embodiment, the invention com ing out the precipitating agent removes most of prises the use, as textile material to be treated, the zinc but leaves a substantial proportinn of of cellulosic fabric as, for example, one of cotton 45 it in the fabric, aS, for instance, about 0.02% to or viscose rayon. With such fabrics the alkali 0.4% of the dry weight of the fabric. Larger metal zincate solution partially dissolves the sur amounts of zinc than 0.4% may be present in face portion of the fabric which, in turn, is re certain goods processed according to this inven precipitated along with the cellulose of the cellu tion but are not necessary. This zinc is itself lose zincate solution. As a result, there is prac 50 mostly embedded in the coating of cellulose so tically integral union of the coating to the inner that it is anchored thoroughly to the fabric. portions of the cellulosic base material. Also, the This zinc left in the coating of the fabric not, partial solution of the base fabric followed by only retards development of mildew but also in subsequent precipitation causes bonding together creases the retentivity for pigments and fillers of the threads at the positions of crossing. This 55 as, for example, for iron Oxide pigments, thio Strengthens the fabrics. It also stabilizes the cyanine or clear filler. 2,442,973 3 4 An especially important result is obtained clear and may be applied to textile materials when the sodium zincate solution of cellulose is without further clarification. If desired, how added to a fabric and the fabric then treated with ever, the solutions so made may be filtered, alkali as in the common process for mercerizing Settled, or centrifuged, to remove any suspended cotton. Here the concentrated alkali, say of material that may be present in objectionable strength about 20%, precipitates the cellulose. amount. The fabric is then soured in a usual manner, The solution is applied to the selected textile washed and dried: I have discovered that zinc material in any suitable or conventional manner. ate solutions of cellulose so added and then pre Thus, fabric or thread may be passed through cipitated with alkali are retained on the fabric O the cellulose solution and then between squeeze after repeated launderings better than when the rolls to remove excess of solution. Or, the textile precipitation is effected by acidification. In fact, material may be passed over a roll which at its it has seemed from a number of experiments that lower part only contacts the solution and then the stiffness or 'hand' of the fabric containing between Squeeze rolls, a suitable arrangement the coating of cellulose precipitated by strong 15 being a two-roll system in which the lower roll alkali is either unaltered or actually slightly in dips into the Solution and the overriding roll and creased by repeated laundering. The greater lower roll Squeeze the textile between them. . . retention of the cellulose when precipitated by After the Solution has been placed upon the alkalinity, as compared to precipitation by such textile material, the treated material is then sub agents as sulfuric acid, is considered to be due 20. jected to treatment to cause precipitation of the to the effect of the strong alkali upon the fibers cellulose in situ. This precipitation may be made of the cotton or like material at the moment of . in various ways, the precipitation of the cellulose. In a. particularly satisfactory method, the As the textile material to be treated, there is treated textile. is passed through an acid bath selected one that is not rapidly soluble in alkalies containing, for example, dilute sulfuric, hydro at room temperatures. Cotton, flax, and viscose 25. chloric, acetic, or other relatively inexpensive acid rayon are particularly satisfactory as the textile in concentration of about 1 to 5 parts for 100 material. Silk and acetate rayon may also be parts of water. A large excess of the acid solu used if the treatment with my cellulose solution tion is used, so that acidity remains after pre is made rapidly and the treated product is then 30 cipitation. Particularly good results from the promptly neutralized with acid. Particular advan standpoint of toughness of the cellulose film are tages are obtained when glass fibers are used as obtained when the acid used is a strong mineral the textile material, the alkalinity of my solu acid, such as sulfuric or hydrochloric, and its tion so modifying the surfaceportions of the glass concentration in the bath after the precipitation fibers, as by incipient or substantial solution, that 35 is approximately 2%, say 1 to 4%. When acetic satisfactory adherence of the cellulose coating is acid is used, on the other hand, the treated mate obtained. Glass fibers so coated unay be dyed in rial after drying is inclined to be somewhat softer accordance with technique for viscose rayon or. and suitable for uses in which softness of the cotton. textile is required. The textile material to be treated is preferably In place of the precipitation by acid, the cellu in the form of a fabric, although the treatment lose may be precipitated in any manner described may be applied less conveniently to the textile in my said patent, or by (1) heating the textile material in the form of single strands of yarn or and adhering cellulose solution by steam heat, thread. air, or quick immersion in hot water; (2) drying The cellulose solution in the aqueous sodium 45 the coated textile in air at atmospheric tempera zincate solution is prepared as described in my tures, the cellulose precipitating as the water is U. S. Patent 2,322,427, issued June 22, 1943, for evaporated; (3) addition of electrolytes such as Cellulose product. Briefly stated, the cellulose Soluble salts or additional alkali such as sodium, zincate Solution is made by dissolving cellulose potassium, or lithium hydroxide; or (4) by ad Such as rayon waste, purified cotton linters, or 50 mixing alcohol, acetone, glycerine, glycol, or like the like in a Solution made by dissolving zinc, zinc Water-soluble dehydrating materials into the oxide, or zinc hydroxide in an excess of an alkali Water solution to cause precipitation of cellulose. metal hydroxide such as sodium or potassium When non-volatile strong acid such as sulfuric hydroxide at low temperatures and then warming has been used for precipitating the cellulose, then the resulting solution to moderate temperatures, 5 5 the textile set with adhering cellulose must be all according to the conditions specifically recited neutralized with ammonium hydroxide, sodium in my said patent. carbonate, or the like or washed to remove the 2inc oxide is the most convenient to use of the acid. When there has been used, in making the readily available zinc materials. There is no ob precipitation, no agent that is harmful to the jection to the use of zinc hydroxide except for 00 textile, even though the agent is not removed by. the unnecessary inconvenience of providing an drying, then the Washing may be omitted and the economical supply of the hydroxide. Also, there textile and precipitated cellulose film dried is no objection to the use of metallic zinc if one directly. Washing is not harmful in any case. wishes to use zinc and does not object to the Drying is required to remove water from the relative slowness with which the metal dissolves treated product, this drying being effected in any in the alkali. The three materials give the same usual manner such as passing the treated textile product when dissolved in alkali in equivalent material over steam heated drying rolls, through proportions and the term "zinc oxide" is used to hot air driers, or over heated calenders. include all of them. . The invention will be illustrated in further de The Sodium hydroxide is used in large excess tail by description in connection with the follow over the amount theoretically required to convert ing specific examples: the zinc compound to zincate and suitably in the Ecample 1 pation of about 8 to 15 parts for 100 parts of Water. The anti-mildew effect of my treatment is ill The solutions so made are ordinarily practically 5 lustrated by this example. 2449,978. 5 6 A cotton fabric was treated with a cellulose Eacample 3 ether solution containing 5% of the ether and A cotton sheeting is singed in usual manner also treated with 5% cellulose in aqueous sodium and then treated with an aqueous solution con zincate solution. These fabrics were washed with taining 3% cellulose, 8.5% of sodium hydroxide, sulfuric acid, rinsed thoroughly to remove about 5 and 2.9% of zinc oxide. The treated fabric is as much zinc as possible. Fabrics were then then allowed to dry if a continuous machine is dried and treated with various commercial anti used. Otherwise it is allowed to stand for sev mildew agents and were subjected to culture tests eral minutes and is then passed through sulfuric with Chaetonium globosum. acid, washed thoroughly and then either kidered in all cases the fabrics originally were increased O or handled in any manner usual at this stage. 15 to 20% in strength by the cellulose treatment. When the fabric is finally finished it will be In all cases, however, the samples subjected to noted that the surface hairs which were not COm the mildew test showed 15 to 20% less strength pletely removed by the singeing but which were when they had been treated with the cellulose at least partly changed chemically by the singe ether than when treated with the solution of 15 cellulose in zincate. ing have dissolved in the zincate Solution and To samples without any commercial anti-mil have given results which normally would have dew agent, one coated with the cellulose ether required a coating solution containing about 4 and one with the cellulose zincate, were also sub or 5% of cellulose, in a non-zincate solution, for jected to the mildew test. After three weeks, obscuring the hairs, as contrasted with 3% of cel the ether treated sample showed complete loss of lulose in the zincate solution used to accomplish textile structure and could not be removed whole the result of dissolving of the hairs and thus giv from the cultur medium. The cellulose-zincate ing the fabric a clean, non-fuzzy appearance. treated sample retained its structural form and This would not happen with viscose or other could be lifted from the medium. Although the 25 alkaline (non-zinc) solutions of cellulose because cotton itself had been attacked, the cellulose film of the lack of solvent power in such solutions as containing zinc was not attacked. applied to the fabric, A third plain fabric with no cellulosic coating Eacample 4 and no added anti-mildew agent, when subjected to the cultur test, showed complete loss of textile 30 In this treatment, the singeing may be omitted structure. when its degrading effect and the increased rate - Eacample 2 of solubility of the fuzz is not desired. In many cases it is desirable to apply a cellu The following example shows in detail the ef lose solution to a fabric and set the cellulose fect of applying the zincate solution of cellulose 35 with high heat leaving the cellulose dissolving before mercerizing, upon the "hand' of the stock, agent in the fabric for substantial periods of . both before and after laundering. time, as for example, in sizing. With zincate A cotton fabric is padded through full strength Solutions of cellulose, it is possible to pass the solution of cellulose (about 5% on the dry basis) yarn or goods through the solution and dry to dissolved in sodium zincate solution of the kind 40 a moisture Content as low as 1% and then allow described. The treated fabric is divided into two the goods to stand in this form for hours or weeks parts. One part is soured in dilute sulfuric acid, without any deterioration in strength or with rinsed and dried. The other part is passed out any objectionable swelling or changing of the through mercerizing caustic solution (about textile fibers themselves. In the case of other 20%), then washed thoroughly with warm water alkali solutions of cellulosic materials, such as on a mercerizing frame, and then either dried or ethers or viscose, the fabric or yarn would lose soured in dilute sulfuric acid, rinsed and dried. its strength immediately upon drying, and be On examination of the two fabrics it is found . Come still weaker on standing. When certain that the One coagulated by the mercerizing proc organic solvents for cellulose are used, the fabric ess is sheerer and slightly-stiffer than the one would actually dissolve on the long contact. treated by the acid coagulation. It is also to be noted that the cellulose-zincate Upon washing the two samples in a laundry treated goods, containing all the alkali in dried wheel for 1 hour, it is found that the fabric co form, actually increases in strength on standing agulated by mercerizing has lost very little hand and becomes stronger than fabric obtained with and also shows considerably less shrinkage than any of the previously used finishing treatments. the same fabric coagulated by the acid method. Eacample 5 It is to be noted that in the mercerizing method of coaguilation, there is no substantial loss of Sodium zincate solution is prepared as follows: cellulose from the treating solution and the cellu 100 parts of zinc oxide are stirred into 280 parts lose is bonded better to the cotton. 60 of water. 280 parts of caustic soda are then in When, on the other hand, a cellulose ether solu troduced and stirred in the zinc oxide and water tion is applied and later precipitated in the mer mixture until the stadium hydroxide is dissolved. Cerizing liquid, there is removal of a substantial Then 100 parts of water are admixed. This gives part of the ether during the processing described. a Solution of sodium zincate. Although the ether is precipitated by the strong To dissolve the cellulose in the zincate solution, caustic present initially in the mercerizing pad, 27 parts of powdered viscose rayon are stirred there comes a stage, in the washing of the fabric into a mixture of 218 parts of water and 175 parts carrying the precipitated ether, at which the of chopped ice. Then 120 parts of the zincate ether is in contact with alkali of the most favor Solution prepared as above are added and thor able concentration for dissolving the ether. In oughly stirred into the mixture. Washing the cellulose precipitated from the zinc As soon as the temperature of the whole mix ate, on the other hand, the zinc compound be ture is lowered by the melting ice to -3°.C., comes excessively diluted before the alkalinity warming is started at once and the temperature reaches what would otherwise be a favorable raised to approximately 15 C. concentration for solution of the cellulose. 75 This solution of cellulose in sodium zincate may 2,442,973 7 8 be used directly on fabric. When, however, it is waxes, and flexibilizing resins such as alkyd desired that the treated fabric be not too stif, resins, soft urea-formaldehyde resins, meth as in the case of treated cotton sheeting, the Solu acrylate resin, and the like. These agents if tion is diluted, as, for example, to about one-half water-soluble may be applied in solution or if not of its usual concentration before application to soluble emulsified in the solution before applica the fabric. tion to the textile material. The solution, either at the original concentra ... My cellulose-zincate solution, being of relatively tion or after dilution, is applied to the selected low viscosity for a given content of cellulose, fabric by one of the machines described previ penetrates well into the surface portions of pene ously. The thus impregnated and coated fabric O trable textile material being treated and thus is passed through a sulfuric acid bath of concen gives excellent anchorage of the cellulose after tration 2 to 5 parts of the acid for 100 parts of regeneration in the textile materia. the solution. For some purposes, however, I may include in The sulfuric acid causes precipitation of cellu the solution a wetting or penetrating agent. For lose not only upon the surface of the fabric but 15 this purpose I have found particularly suitable a also within the fabric at positions to which the minor proportion of one of the conventional sul cellulose solution has penetrated. The fabric is fated higher alcohol wetting agents, a water then thoroughly washed and dried. soluble protein condensation product, and sul Eacample 6 fonated hydrocarbon wetting agents. The wet 20 ting agents selected should be not decomposable The cellulose-zincate solution described under rapidly by 10% sodium hydroxide and should not Example 5 is applied to marquisette mosquito cause precipitation of the cellulose from the netting. cellulose solutions I have described. To avoid The mosquito netting is first thoroughly singed possible decomposition of certain wetting agents and mercerized and then can dried. The dried 25 by the sodium hydroxide and premature precipi goods are then padded through the cellulose tation of cellulose, prefer to introduce the wet , zincate solution and passed immediately to a ting agent, if used at all, into the cellulose solution tentering frame where the goods are held out to immediately before the use of the solution so that width and then dried while tentered. The dry only a very short time of contact of the wetting goods are then soured in dilute sulfuric acid, 30 agent with the alkali cellulose solution is allowed washed, can dried, padded through a solution of before the solution is applied to the textile. direct dye, and finally frame dried to width. While cellulose-zincate solutions made as de Eacample 7 scribed above give outstanding results, less satis factory solutions may be used if the high quality The cellulose-zincate solution of Example 5 is 35 of the treated fabric is not to be maintained. applied to spun rayon. Thus, there may be used solutions made by dis The spun rayon fabric is padded through a solving cellulose at ordinary temperatures in my solution of the cellulose-zincate solution which zincate solution or at my low temperatures with has been diluted down to one-third of the original different ratios of Zinc to sodium hydroxide and cellulose content with a 4% caustic solution and 40 different concentrations of the zincate solution is allowed to fall immediately into a large box from those described above. When, however, the containing 2% sulfuric acid in water. After pas cellulose is dissolved in the sodium zincate at sage through the sulfuric acid bath, the goods ordinary room temperatures, there is produced a are washed thoroughly with water and are then finished solution that is objectionably high in vis dyed to shade in a dye tub or on a dye gig and are 45 COSity for a given concentration of dissolved cel finally frame dried. lulose, that does not penetrate well into the fabric Eacample 8 being treated, that does not give the desired re sistance to shrinkage of a treated fabric on being Fabricated glass wool fibers are padded through washed with water, and that does not carry pig a solution of the cellulose-zincate solution which 50 iments into the fabric so as to give the desired uni has been diluted 50% with water. After that the formity and depth of coloring when pigments are fabric is immediately neutralized in dilute sul used. When zinc in ratios substantially above furic acid. those shown are used, there is uneconomical use In the above examples additional ingredients of the zinc and unnecessarily increased cost of the . may be incorporated in the cellulose-zincate solu 55 solution and the stability of the solution at low tion to give special effects. temperatures is adversely affected. When the Thus, there may be used a pigment or a dye. ratio of Zinc oxide to sodium hydroxide is much In such case the coloring material is precipitated less than that shown above, then there is required and dried. Any kind of dye or pigment may be for making the solution of cellulose even lower used so long as it is not decomposed or objection 60 temperatures than those that are preferred with ably discolored by alkalinity of the cellulose solu the optimum ratio of zinc oxide and there is pro tion. Even direct dyes may be used in this proc duced, even with the use of abnormally low ten ess as their inclusion in the cellulose film on the peratures, a solution of the cellulose that is un finished product makes them at least moderately stable at room temperatures. If one is prepared fast. 65 to accept these serious disadvantages, then any Also, I may incorporate starch into the cellulose solution of cellulose in sodium zincate may be solution. Thus I may use potato, corn, Or any used. usual laundry starch in the proportion of about It will be understood that certain details given 20 to 100 parts for 100 parts of dissolved cellulose. are for the purpose of illustration, not restriction With the starch, there may be included any usual 70 of the invention, and that variations within the textile filler, so that the application of the solu spirit of the invention are intended to be included tion and suspended material produces a back within the scope of the appended claims. filling of the textile. There may be used agents to modify the film What claim is: in the direction of greater plasticity such as oils, 76 firmly1. In adhering treating coatinga textile thereupon, material tothe provide method a 2,442,973 9 10 which comprises applying to the textile material a tion, applying to the singed fabric a solution of solution of unsubstituted cellulose dissolved in an unsubstituted cellulose in sodium zincate solution, aqueous alkali metal Zincate solution containing then applying a precipitating agent to precipitate an excess of alkali over the zinc present, contact cellulose from the said solution as a coating upon ing the textile material and applied solution with the fabric, and washing and drying the product, an agent causing precipitation of cellulose from the treatment described causing a part of the the said solution upon the fabric, and washing the singed fuzz to dissolve in the sodium zincate solu thus coated fabric to remove most but not all of tion and the rest of the fuzz to be obscured by the precipitating agent, the incomplete Washing the cellulose coating. thus effected serving to remove most but not all 10 8. In treating a textile fabric to provide a firmly of the zinc compound from the product. adhering cellulose coating thereupon, the method 2. In treating a textile fabric to provide a firmly which comprises applying to the fabric a solution adhering cellulose coating thereupon, the method of unsubstituted cellulose in an aqueous solution which comprises applying to a cellulosic fabric a of an alkali metal zincate containing an excess of solution of unsubstituted cellulose in an aqueous 5 alkali over the zinc present, precipitating cellulose solution of an alkali metal zincate containing an from the said solution upon the fabric by adding excess of alkali over the zinc present, precipitating an acid precipitating agent, then washing the cellulose from the said solution upon the fabric treated textile with water to remove most but not by the addition of an acid precipitating agent, all of the precipitating agent and zinc compound washing with water to remove the precipitating 20 present, adding to the material so washed an al agent until the pH becomes about 3 to 4, and then kaline zinc precipitating agent and then drying discontinuing the washing, the incomplete wash the product. . ing thus effected leaving a substantial proportion 9. The method of treating cellulose textile ma of zinc compound in the washed product. terial which comprises applying to the material 3. The method described in claim 2, the said 25 an alkaline solution of unsubstituted cellulose in cellulosic fabric being viscose rayon. an aqueous sodium zincate solution, subjecting 4. In treating a textile material to provide a the material to treatment with an aqueous caustic firmly adhering coating thereupon, the method alkali solution of mercerizing strength whereby which comprises applying to the textile a solution said unsubstituted cellulose is precipitated on the of unsubstituted cellulose in an aqueous alkali 30 material, and washing the material to remove al metal zincate solution containing an excess of kalinity therefrom. alkali over the zinc present, precipitating the cel lulose in the applied solution by treatment with SIDNEY M. EDELSTEIN. an aqueous caustic alkali solution of concentra REFERENCES C TED tion adequate to cause mercerization of cellulosic. 35 textiles, washing the resulting product to remove The following references are of record in the alkalinity therefrom, and then drying the washed file of this patent: material, the precipitation of the cellulose by the UNITED STATES PATENTS said caustic alkali solution and the Subsequent Number Name Date Washing and drying causing such firm bonding of 40 1,085,783 . Aylsworth ------Feb. 3, 1914 the precipitated cellulose to the base fabric that 1,269,340 Wanderkleed et al. --- June 11, 1918 there is no substantial loss of stiffness of the 2,009,015 Powers ------July 23, 1935. fabric on repeated laundering. 2,072,770 Reid ------Mar. 2, 1937 5. The method described in claim 1, the fabric 2,129,708 Schreiber ------Sept. 13, 1938 used being composed of glass fibers, the precipita 2,204,859 Hyatt et al. ------June 18, 1940 tion being effected by the addition of acid and the 2,322,427 Edelstein ------June 22, 1943 alkali metal zincate solution causing a roughening 2,289,085 Halewijn ------July 7, 1942 of the surface of the glass fibers so that the cel lulose when precipitated adheres to the surfaces 2,299,612 Clayton et al. ------Oct. 20, 1942 and the cellulose coating which results from the 50 FOREIGN PATENTS treatment giving to the glass fabric dyeing prop Number w Country Date erties characteristic of cellulose fabrics. 320,062 Great Britain ------Oct. 2, 1929 6. The method described in claim 2 which in cludes adding an alkaline zinc precipitating mate OTHER REFERENCES rial after the said washing with water, so as to 55 Trotman, Bleaching, Dyeing and Chem. Tech. neutralize acid and convert to insoluble form zinc of Textile Fibres, 1925, Griffin & Co. Ltd., London, remaining at that stage. page 336. (Copy in Div. 43.) 7. The method of making a clean cellulosic fab Salvin, Influence of Zinc Oxide on Paint Molds, ric which comprises singeing an originally some Ind. & Eng. Chem., vol. 36, No. 4, April 1944. pages what fuzzy fabric to degrade the cellulose fuzz and increase its solubility in sodium zincate solu to 336-340.