Patented July 12, 1932 1866,917

UNITED STATES PATENT OFFICE EDWARD CHAUNCEY WORDEN, 1st, OF MILBURN, NEWJERSEY, ASSIGNOR TO BANSON & ORTH, OF NEW YORK, N. Y., A FIRM. COMPOSED OF CHARLEs D. oRTH, SR, AND CHARLES D. ORTH, JR., AND MICHAEL. J. SMITH . MANUFACTURE OF CELLULOSE MATERIAL FROM HEMP FIBERs No Drawing. Application filed March 16, 1929. Serial No. 347,728. This invention relates to the industrial rification be entirely mechanical or not, are treatment and utilization of the fibers for distinguished by their great tensile strength, the production of purified cellulose there and also by their resistance to chemical treat from, of various kinds, species or grades of ment with the minimum of degradation, de 5 "hemp', said cellulose in the purified state, polymerization or hydrolysis of the cellulose 50 having been found highly advantageous for or cellulose aggregates contained therein. the manufacture of rayon, as more specifical Furthermore, this tensile strength appears to ly set forth in my co-pending application, be intimately associated with the length Serial No. 347,457 of March 15, 1929, for of the individual fiber or cell, and ad U "manufacture of rayon from hemp fiber'. mits of purification for the formation there 515 By “rayon’ or “artificial filaments' is under from and separation of a cellulose or stood to comprise those esters and ethers of cellulosic material relatively high. in al cellulose, which, after being placed in solu phacellulose or resistant cellulose, and con tion, are afterwards forced through minute taining but small amounts of hemicelluloses 5 orifices into a liquid or other medium where and other inferior celluloses or cellulosic 60 by they are precipitated into a hydrated cel bodies, which renders purified hemp cellu lulose with decomposition of the cellulose lose, peculiarly adapted to the formation of compound or cellulose ester, or deposited as high strength artificial filaments, provided the cellulose ester by the volatilization of a the series of treatments or steps to which the volatile solvent. Of the first group would cellulosic materialis subjected in transforma 65 be included rayon produced from viscose and tion from cellulose to artificial filaments, is cuprammonium cellulose. From the second carried on without serious weakening of the group, would be included the nitrocellulose hemp cellulosic structure or strength. . filaments which are afterwards denitrated, In the cellulose ester and cellulose ether 25 the organic esters of cellulose such as acetated art in general, and in the nitrocellulose in 70 cellulose, and the alkyl- and aryl-celluloses, dustry in particular, those who have “lived” typified by ethylcellulose and benzyl-cellu the art, and not merely “worked’ in it, have OSes been aware that in an identical method and There appears to be a looseness in the use procedure of esterification, the initial length 2 of the word “hemp' by some writers. Hemp and strength of the cellulose fiber to be esteri 75 in this invention is intended to cover "hemp' fied bears a definite relation to the strength fibers, as stated on page 190 of Report No. 9, of the esterified cellulose made therefrom, U. S. Department of Agriculture, “A descrip and this relationship of strength and tenacity tive catalogue of useful fiber plants of the is especially exemplified when the esterized 35 world', by Charles Richards Dodge, pub cellulose is dissolved and placed in filament 80 lished at the Government Printing Office, or film form from an evaporation therefrom Washington, D. C., 1897. Of these “hemp' of the volatile solvents contained therein. fibers therein listed, I have obtained especial In other words, where the tensile strength ly useful cellulosic fibers for the production and length of fiber of the initial purified cel 40 of rayon and artificial filaments by the use lulose is relatively high, other conditions of 85 of fibers and other components from the bo treatment being the same, the esterified prod tanical group Musa, of which Musa teatilis uct will be correspondingly high in tensile and Musa sapientum are perhaps most well strength and other desirable characteristics. 45 known. Hemp fibers in general, when in That is, they are increased with an increase the partially purified state, whether that pu in strength of the original cellulose from 90 2 1866,917 which produced by the esterifying or other usually linters on account of its inexpensive process to which the cellulosic fibers are sub eSS. jected, and that the stronger the original puri In general, from a chemical reactive point fied cellulosic fiber, other conditions remain of view, cotton cellulose is more obdurate to ing substantially the same, the stronger will treatment than is wood cellulose, and purified 70 films and filaments be when the cellulose is hemp fiber cellulose than is cotton cellulose, transformed into ester form, dissolved and especially when subjected to the various steps deposited either as a film by the removal of involved in esterification primarily for rayon solvent, or as a filament by the same proce production, and corresponding variations dure, by precipitation, setting, coagulation and adjustment in chemicals, concentration, 75 10 or otherwise. time, temperature and similar factors are re That is, a relatively long fiber cotton upon quired in order to esterify under optimum nitration, for example, will produce a cellu conditions as to yield and quality of resultant lose ester, which when dissolved and the sol product obtained. vent removed therefrom, forms a film or fila This generalization holds true likewise, in 80 s ment of greater tensile strength and other de the manufacture of cellulose ester filaments, sirable physical qualities than will a relative especially to viscose rayon filaments from ly much shorter cotton fiber (such as inters highly purified cellulose from hemp over both or fly). This difference has been found to be that of cellulose as obtained from wood and due in a measure to the greater length and from cotton, and departure from the standard 85 20 strength of the individual cellulose cell in the procedure for alkalicellulose formation and longer fiber cotton. subsequent xanthation is necessary to obtain Furthermore, in the production of those best results, and in order to induce optimilm cellulose esters represented by the xanthated conditions in the various phases of treatment celluloses (viscose) it has been noted that the from initial cellulosic material to finished relatively shorter wood cellulose fibers do not product, whether that product be an ester or admit of the production of a rayon filament an ester which has been de-esterified, usually of as high tensile strength and other desirable with the production of hydrated cellulose. physical characteristics as when the relatively This invention, therefore, is primarily con 30 longer purified cotton cellulose fibers have cerned with the respective steps in treatment 95 been submitted to the same esterification steps of the fibers commercially classified under under comparable conditions, and cotton cel the general heading of “hemp' as heretofore lulose fiberis being admixed with wood cellu indicated, for the preparation therefrom of a lose fiber at the present time for viscose rayon cellulosic material high in alphacellulose, and 00 35 manufacture, in order to increase the tensile relatively low in hemicellulose and other in strength both in the wet and dry state and ferior cellulosic bodies, and admirably adapt other qualities, over that which would nor ed for the transformation into ravons and mally resultif wood cellulose alone be used. other artificial filaments, films, etc. by virtue There appears to be a well defined relation of its high alphacellulose or resistant cellulose 05 40 ship between the length and strength of the content, and virtue of practical absence of original cellulose fiber used for esterification inferior of cellulose and cellulosic bodies. purposes and the tensile strength and other In the illustrative example to follow, it is qualities of filaments and films producible to be understood that the method of proce therefrom, irrespective of whether the final dure will necessarily vary, as well as the 0 product is the cellulose ester in the solid form amounts and nature of chemicals used, time, or whether the final product is a de-esterified temperature, pressure and concentration fac filament or film as in viscose and nitrocellu tors, depending upon the source from which lose rayon. the hemp was obtained, whether from the It is conceded that "hemp' fiber possesses male or female plant, and the physical condi 5 unusual strength when compared with wood tion as to disintegration of the fibers or bun fiber or coucon cellulose fiber, all in the puri dles of fibers, at the time the treatment of fied state. purification is commenced. Coincidental with an increase in tensile It is immaterial whether the hemp has been strength of initial purified cellulosic. fiber as submitted to a retting operation, is scutched 120 55 used for esterification purposes, usually or heckled, or a combination of two or more comes a diminished reactivity, especially to of the operations has been applied to it. I chemical treatments, and adjustments of con prefer as the first chemical operation (the centration, avidity of reactiveness, time fac fiber previously having been placed in physi tor, tenniperature, etc. are usually necessary cal condition to make it of maximum recep 25 60 die to this property, when operating upon tivity to chemical treatment) to boil the fibers celluloses from various origins. This is read or fiberbundles or aggregates with an excess ily seen at the present time, in endeavors to of water containing 3%-7% free sodium hy supplant a portion of the wood cellulose here droxide, 0.5%-3% alkali silicate and 0.5%- tofore used in viscose rayon production, with 4% cottonseed oil or other readily saponi 30 an equivalent amount of purified cotton fiber, fiable vegetable or animal oil, or an equivalent 1,866,917 3 amount of the oil already saponified. Satis trations of the baths may be increased or factory results have also been obtained by diminished, as conditions may arise. substituting for the saponified oil, the alkali The purified hemp cellulose, as the mean metal salts of the sulfonated oils (i.e. Turkey of determinations of several runs, gave red oil, alizarin assistant, saponified sulfo figures as follows:- 70 nated corn oil, etc.). The fiber is placed in 48 Per cent a pressure kier, and submitted to heat, pref Moisture (drying at 105° C.).------6.1 erably at a temperature of around 110° C. Ether extractive ------0.12 circulation being aided, if desired, by means Hemicellulose and similar bodies. ---- 0. of a circulatory arrangement for pumping ------(less than) -- 1. 5 continuously the boil-off liquor over the mass Ash (inorganic impurities)------0.14 of fibers. It has been found that the addition The absorption of the cellulose is shown by to the boil-off liquor of an amount of soluble the fact that a pledget of the same placed water glass is especially beneficial in scouring upon the surface of water at room tempera 5 and removal of intercellular and cementitious ture will be immersed by its own weight, 80 material, fats, oil, wax and similar encrust usually in less than 30 seconds. Alphacellu ing and adhering impurities, and tends to lose determinations made on various samples leave the fiber in an especially porous and indicated that it was practically pure alpha absorptive condition for quick and complete or resistant cellulose, and with but negligible 20 penetration of reagents used in normal esteri amounts of other cellulosic materials pres 85 fying and etherifying processes. The boil ent, while the original tensile strength of the off operation is continued from 3 to 8 hours fiber was substantially conserved. The color depending upon the comparative amounts of of the individual fibers varies from a light impurities in the fibers or fibrous aggregates, straw color to pure white, depending upon 25 after which the boil-off liquor is allowed to the thoroughness and care exercised in the O drain off, and clear water added, and heat purification treatments. Inasmuch, how applied, and this alternate addition of water, ever, as rayon filaments are usually bleached, heating, and discarding of the wash water is I prefer to submit the cellulose to what is continued until the wash waters are practi known in the trade as between a three 30 cally colorless, and a sample of material when quarters and full bleach, in order to conserve 95 extracted in a Soxhlet or other suitable ap to the maximum, the tensile strength of the paratus with a chemical such as ether, gives individual cellulosic fibers. practically no extractive. I am aware that it is proposed to produce The fibers are, still in the wet condition, paper from hemp fibers by the addition there 35 passed through friction rollers which tend to to in a partially purified state of varying 00 break down and disintegrate the fibrous amounts of filling and loading materials, bundles or masses, the fibers being subjected sizes, albuminous and other organic and in to a running cold water washing treatment. organic products to induce specific surface in an elutriating manner, whereby inter and interior effects in the paper so produced. 40 cellular and encrusting material is disinte Ilay no claim to this. grated, and floats off in the water. The . But what I do claim and desire to secure by fibers are then hydro-extracted, and sub Letters Patent is: mitted to an electrolytic (preferably) chlo 1. A process for treating hemp fibers for rine bleach, care being taken that the fibers the isolation therefrom of alphacellulose in 45. are not exposed to the atmosphere during the a highly purified condition, comprising me 0. bleaching and subsequent acidifying opera chanically disintegrating said fibers, remov tion, to minimize formation of oxycellulose ing impurities therefrom by treatment with and other oxidation cellulosic compounds. a hot solution of alkaline hydroxide, alkaline The now nearly white fibers are washed silicate and a softening body, removing re 50 until all traces of reactants are removed, and actants and products of decomposition by 5 dried at a comparatively low temperature. washing, bleaching the same in the absence For ease in manipulation during esterifica of the air, and washing free from chemicals, tion, and the steps preceding and succeeding substantially as herein set forth. it, it is advisable to make the fibers into sheet 2. A process for treating hemp fibers com 55 paper, either along or with admixture thereto. prising mechanically disintegrating the same, of other celluloses suitable for esterification removing therefrom alkali-soluble matter by treatment, such as wood pulp cellulose, cot boiling in Water, removing water-soluble ton, linters, and the like, the proportions components by Washing and bleaching, final used, depending upon the final results de ly removing reacting chemicals by washing 60 sired, and the details of treatment to which until a neutral mass is obtained, as herein 25 the cellulosic material is to be subjected. described. One or more of the foregoing steps may 3. A process for the production of cell be prolonged, shortened or repeated, depend losic material relatively high in alpha-cellu ing upon the comparative refractoriness of lose and relatively low in hemicellulosic and w the hemp fiber to be purified, or the concen other inferior cellulosic bodies from hemp 33 4. 1,866,917 fiber, comprising boiling the original fibers in an aqueous solution containing the hy droxide and silicate of an alkali metal until all alkali-soluble material has become water soluble, washing until neutral, and remov ing coloring matter therefrom by ways now known, as herein set forth. 4. A process for the treatment of hemp fibers to obtain therefrom cellulose of maxi 10 mum suitability for esterification purposes, comprising treating the hemp fiber suitably subdivided with a saponified vegetable oil containing an excess of alkali until non-cel lulosic bodies have been saponified, emulsi ls fied or otherwise rendered water-soluble or removable by washing, eliminating said im purities by a washing treatment, decoloriz ing the purified cellulose, and washing to a neutral reaction, substantially as herein set 20 forth. 5. A process for the treatment of hemp fibers to obtain therefrom purified resistant cellulose, comprising treating the finely sub divided fibers with a non-solvent of cellu 2 lose containing alkali hydroxide and silicate which is at the same time a solvent or emulsi fier of the non-cellulosic impurities there in, removing said non-cellulosic bodies by a washing process in water with the minimum 0 of degradation of the cellulosic portion, then bleaching and Washing to a neutral reaction the purified cellulose so obtained, asset forth herein. 6. A process for the purification of hemp 35 fibers from the non-cellulosic bodies nor mally contained therein, comprising treat ing said fibers preferably in a fine state of subdivision with an emulsifying and sa ponifying agent containing alkaline metal 40 hydroxide and silicate, and which is at the same time a solvent of hemicelluloses and a non-solvent of alphacellulose, continuing said treatment in a hot aqueous solution un til the alphacellulose has been separated from its impurities, washing to remove said impurities, bleaching the alphacellulose thus formed to increase its porosity and recep tiveness for esterifying chemicals, then wash ing until neutral, substantially as herein set 50 forth. In witness whereof I attach my signa ture hereto. w EDWARD CHAUNCEY WORDEN, 1st. 35

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