[1]United States Patent Office 39154@6 14 3,154,614 PROCESS FOR SPINNIING A 1-UGI-I -VISCOSITY, HIGH GAPVUVIA VISCOSE Yashikazu Aoki, Otsa, and Teruji Kamei, Sakyo-.'iu, Kyoto, Jgpan, assignors to Tachikawa Research Institute, Iligashlyamalp-i, X@yoto, Japan, a corporation of Japan No Drawing. Filed June 27, 1962, Ser. No. 205,565 5 Claims. (Cl. 264-188) This invention relates to a process for producing rayon a,s re.- enerated cellulose in the form of fhaments or fibe@rs. I.n particular, it is concemed with an improved method fOr Tegenerating cellulose by the spinning of viscose in the manufacture of viscose rayon yarn. This is a conti nuation-in-part of application Serial No. 64,730, now ,abandoned, ffied October 25, 1960. The basic process coiitemplated by this invention essentially entails the spinning of unripered viscose in a low acid concentration bath, @the temperature of the bath being controlled and the viscose having a Wgh degree of p oly@-nerization. Processes of this type are known to ,the art being described, for exarnple, in U.S. Patp-nts Nos. 2,592,355, 2,732,279 and 2,607,955. T@liese i)roc,esses have proved dissatisfactory Lrom th@- standpoipc that the spinning velocity may not be increased beyopd a certain limit without seriously diriiinishing the tenacity of the -resulting fflapient or fiber and jeopardizing the stability of t@he process itself due to agtual breakage of ,the seniicoagulated viscose thread witwii tne bath or outside thereof as it is beipg reeled onto the -stretching or tension impaxting components. Thus far, it has been found that for high viscosity viscose a spinning velocity of 20 meters per minute is aboul the per@missible maximum in com-Tnercial practice and this relatively low veloc.ity has been considered a disadvantage. The inventive concept herein is idire&,ed toward the solution of the problem of spinning viscose which has a hgh degrce of polyinerization. That the problern is significant is due to the fact that the higher the degree of poly@merization of the spun fiber, the more nearly will it have the intrinsic properties of nattiral fiber. As pointed out in Patent No. 2,732,279, it had been thoaght that an essential condition of spinning high D.P. viscose is to keep the bath temperatur@- b(-Iow 30' C. This requirement was due to ,the unduly bigh rate of regeneration of @the viscose rayon fiber at higher temperatures which adversely aitected the strength of the regenerat-@ng filar@ients. However, the Telatively low batn temper-ature limits the permissible spinning velority. According to the instant process, the h,:gh D.P. viscose is spun in a coa.-ulating bath the tomperature of wliich is raised above 30' C. which, as is well known, enables higher spinning v@lorities. Conco.-nitantly, however, the, nature and percentage composition of the bath is maintained within critical limits and also in critical relation to the temperature so as to permit the raised temperature without the resultin.- adverse effect thereof. The present invention envisioris, therefore, a spinnii,.g p,rocess in wych high D.P. viscose is spun at 30 meters per minute or more and which is adapted to prodtice fflaments or fibers with superior properties. The sWphuric acid concentration in the bath is low, for example, within the range of 1 to 30 grams 'per liter and the initial material is unripened viscose having a hi.-h viscosity or degree of polyinerization. A weak acid bath is hereby defined as one in wbich the acid concentration is within the approxiinate liniits stated above aiid high viscosity cellulose has a viscosity above 250. In addition, t-tie gamma value of the viscose is above 50 and preferably between 50 and 100. Principal features of the irivenPc,.tented Oct. 27, 1964 2 tion relate to such factors as ternperature of the spinning bath and zinc sulphate concentration and are directly productive of the desired higher ispinning velocity and @stability of the spinnin@g process as an operation as well as improvemeiit i-D the characteristics of the resulting fibers. In order for tl-.ese i@mprovementr, -to be obtairied, it is required that the temperature of the spinning bath be not less than 30' centigrade and the ZnSO4 concentration be within the range of frorn 0.2 to 2.0 10 grams per liter. Moreover, it was found that permissible spinning velocity and bath temperatlire over 30' centigrade can be directly related provided the bath contains the necessary controlled amount of ZnSO4. In conventional processes wh;ch do not provide ZnSO4 in 15 the bath the regeneration of the viscose rayon fiber pro:ceeds so rapidly that its strength is @not sufficient to withstandthe friction from movement of the spinning liquor at the hi,&iier spinning velocities. This is due to the fact that the thread cannot be sufficiently stretched when re20 generation occurs rapidly. It is the funetion of the ZnSO4 ill coritrolled amounts to slow the regeneration process or the decomposition of @the vis-@ose as measured by its -y-value so that stretching can occur;smoothly and as long as regeneration occurs. The stretohing may be 25 effected by means of sdecial,godets such as are described and illustrated in U.S. Patent No. 2,732,279. As the condition of the viscose changes frorn a -y-value to say 30 to a state where the viscose has completely decomposed and its y-value is, therefore, 0, a substantial 30 amount of stretrhing is possible either inside or outside the bath provided the change in state of the @material is controlled which is the function of the ZnSO4- Under these stipul-ated conditions, the th@read can, in fact, be stretrhed more than 200,llo which wil,', assure sufficient 35 tenaiz@ity of the coagtilating fiber to allow a marked increase in spinning velooity. The following relat-ion between temperatur-- of the -spinning bath and concentraton Of ZnSO4, which iare -the key fartors in the improved spinning process, a@d spin40 @ning velocity have been observed. Con@ -entration FavorableSpinTemp erature of the SDinDing bath- of ZnSO4, ning Velocity, centig ra4e Gram s per Meter s per Liter Minut e 45 - 3 0'-35 --------------------------------- 0.2- 0.5 35 3 61-40, -------------------------------- 0. 5-0. 7 40 4 01-50, -------------------------------- 0.7- 2.0 50 I - .50 The filaments obtained by this process have a homo,-eneous di L"bution 4of the zinc xanthate -throughout the viscose colunin being incor@orated tlierein under high osmotic pressure. The fibrous material thus formed is very strong. In addition, the Tesulting fiber is round in 55 Gross section, ;sup-.rior in dyestuff absorption, is low s-@velling in water and dilute alkali s(>Iution and has a high wet modulus. The following exainples may help to give a clearer understanding of oiir process for producing rayon which 60 includes, in par-ticular, the improved method of viscose spinning. Example I Wood t)ulp with a degree of polymerization of 850 65 is steeped one hour at 20' centigrade in 1'0% NAOH solution, and after being pressed to 2.6 times the wei.aht of the original pulp, it is crushed at 18' centigrade for 2 hours. Alkali-cellulose without agina, is subjected to xanthation with 45% CS2 tO the wei.-ht of the cellulose 70 at 19-28' centigrade for 2.5 hours. The composition of the resulting viscous is 5% cellulose and 3.5% NAOH. This viscose is filtered, deaerated and spun as soon as
[2]3 possible after xanthation, its viscosity (by fallin@. ball method) being 250 and its y-value 60. The spinning conditions are as follows: H2SO4 concentration in the spinning bath is 8.0 grams per liter, ZnSO4 concentratioi in the bath is 0.5 gram per liter, temperature of the bath is 35' centigrade, and the thread is stretched to 210% by a godet located outside of the bath, and the final spinning velocity is 40 meters per minute. Characteristics of filament are: 1.4 denier, dry tenacity 4.3 grams per denier, wet tenacity 3.2 grams per denier, dry elongation 12.7%, wet elongation 13.5%, dry knot tenacity 2.1 -rams pe@r denier, flex cycle 650. Example 2 Linter pulp with degree of polymerization of 1(350 is steeped in 19% NAOH solution for 2 hours at 20' centigrade and after being pressed to 2.8 times of the weight of pulp, it is disintegrated for 2.5 hours at 31' centigrade. Without aging, the alkali-cellulose is xanthated with CS2 in the amount of 60% to the weight of the cellulose for 3 hours at 20-33' centigrade. The composition of the viscose thus obtained is 4.5% cellulose and 4.5% NAOH, its viscosity being 450 and its -y-valu-, 80. The spinning is carried out in a spinning bath containing 5.4 grams per liter H2SO4, 1.0 gram per liter ZNSO@ and at a bath temperature of 40' centi.orade. The spinning velocity is 45 meters per minute. The thread, after traveling 15 cm. in the bath, is stretched to 250% by a godet immersed in the spinning bath. The characteristics of the resulting fiber are: 1.0 denier, dry tenacity 5.5 grams per denier, wet tenacity 4.2 grams per denier, dry elongation 12.4%, wet elongation 16.5%, dry knot tenacity 2@4 grams per denier, flex cycle 1100. Exatnple 3 Wood pulp with a degree of polymerization of 1270 is steeped for 2 hours at 20' C. in 19.0% NaOI4 solution, and after being pressed 2.8 times the weight of the original pulp, it is crushed at 24' C. 'L'Or 2 hours. Alkalicellulose, thus obtained, is subjected to xanthation with 55% CS2 to the weight of the cellulose at 20-28' C. for 2.5 bours. The composition of the resulting viscose is 4.5 % cellulose and 3.8 % NAOH ' After being filtered and deaerated, this viscose is spun, its viscosity (by falling ball method) being 750 and its 7-value 100. The sr)innin1 conditions are as follows: H2SO4 concentration in the spinning bath is 9.2 grams per liter, ZnSO4 concentration in the bath is 0.2 gram per liter, temperature of the bath is 30' C., and the thread of 1,000 filaments is stretched by a godet, and the final velocity is 35 meters per minute. The characteristics of the resulting fibers are: 1.2 denier, dry tenacity 5 grams per denier, wet tenacity 4 grams per denier, dry elongation 13%, wet elongation 16%, dry knot tenacity 2.1 grams per denier. Example 4 Wood pulp with a degree of polymerization of 1,100 is steeped for 2 hours at 20' C. in 18.5% NAOH solution, and after being pressed 2.8 times the weight of tile original pulp, it is crushed at 27' C. for 2.5 hours, alkalicellulose, thus obtained, is subjected to xanthation with 50% CS2 to the weight of the cellulose at 19-27' C. for 2.5 hours. The composition of the resulting viscose is 5.2% cellulose and 3.6% NAOH. After being filtered and reaerated, this viscose is spun, its viscosity bein.- 610 and its y-value 85. The spinning conditions are as follows: H2SO4 concentration in the spinning bath is 15.6 grams per liter, ZnSO4 concentration in the bath is 0.5 gram per liter, temperature of the bath is 35' C., i@-id the thread of 6,000 filan-ients is stretched by a odet, and the final spinning v-.Iocity is 40 meters per minute. Tho characteristics of the resulting fibers are: 1.5 denier, dry tenacity 4.8 grams per denier, wet tenacity 3.6 grams per denier, dry elongation 12%, wet elon-ation 15%, dry knot tenacity 1.8 grams per denier. 3,154,614 4 Example 5 Wood pulp with a degree of polymerization of 950 is steeped for 2 hours at 20' C. in 18.2% NAOH solution, and after being pressed 2.9 times the weight of the original pulp, it is crushed at 28' C. for 2.5 hours, alkali-cellulose, thus obtain-,d, is subjected to xanthation with 45% CS2 to the weight of the cellulose at 18-26' C. for 2.5 hours. The composition of the resulting viscose is 5.5% 10 cellulose and 3.3% NAOH. After being filtered and d--aerated, this viscose is spun, its viscosity being 520 and its -y-value 75. The spinninconditions are as follows: H2SO4 concentration in the spinning bath is 30.0 grams per liter, ZnSO4 concentration in the bath is 1.2 -,rams 1,5 per liter, temperature of the bath is 50' C., and the thread of 18,000 filaments is stretched by a godet, and the final spinning velocity is 50 meters per minute. The characteristics of the resulting fibers are: 1.5 denier, dry tenacity 4.5 grams per denier, wet tenacity 3.2 grams 20 per denier, dry elongation 11%, wet elongation 14%, dry knot tenacity 1.6 grams per denier. As mentioned above, the complete abs-.-@ice of the ZnSO4 in the spinning bath precludes the possibility of imparting sufficient stretch to the coagulating material 25 to permit of high velocity spinning. On the other hand too much ZnSO4 in the bath which has a low acid concentration and low temperature causes the formation of the zinc xanthate to become too irregular which also results in the formation of a thread of low tenacity which 30 cannot be spun with higher than conventional spi nninvelocities. Various modifications in the process as above described may be effected by persons skilled in the art without departing from the principle and scope of invention as de35 fined in the appended claims. What is
