Mod-08 Lec-08 Viscose Rayon and Acetate rayon

We’re discussing the module 8 of the organicchemical technological know-how course, which is in regards to the polymer, elastomere and artificial fibreand within the earlier three lectures we discussed concerning the nylons. We discussed about the nylon6, nylon 66, polyester and then the acrylic fibre and the way the development that has takingplace in these sectors and the way it has played major position in meeting the bogus fibredemand of the developing population. Now at present, I will probably be discussing about theviscose rayon that’s acetate rayon and cuprammonium rayon, which is one of the very importantsector in case of artificial fibre and due to the fact that of its superb fine and the appearancelike the silk rayon that has been in use and for simplest thing that in here the differencebecause in case of the all the other synthetic fibre, which is we call it the authentic syntheticfibre or the artifical fibre that is the nylon or the polyester or the acrylic fibre whichthe raw material most important uncooked fabric is from the petrochemical fibre, here rayons are basedon the cellulose raw fabric, excellent excellent of cellulose having alpha cellulose, loosesemi cellulose and the pentagon.So, these are the some of the normal change, herewe are stylish upon the average raw material. So, the insurance plan of the lecture that willbe on the introduction, residences of the viscose rayon, Indian potential of the viscoserayon, application of the viscose rayon, then the method important points of the viscose rayon manufacture.Then we will be able to be discussing about the acetate rayon and the cuprammonium rayon. Althoughthe quantity of the complete capacity when you see the creation sensible it is extra in case ofthe, rather more, in case of the viscose rayon than the acetate and cuprammonium rayon, but,one of the different uncooked material most likely that will be from the petrochemical. That is you will see that the viscose fibre howit looks like and it is just like woollen fabric or the acrylic fibre which you could sayand the brightness you can find the brightness of the fibre additionally and considering the fact that of the moreand more alleviation we are having in case of the viscose now using the viscose inthe cloth that is increasing daily.This is also is the acetate fibre which was once,that is additionally the silk like look we are having. So, the rayon is created from cellulose derivedfrom typical happening fabric, chiefly the timber we’re using here, wooden pulp we areusing in case of the rayon making. Probably the most customary rayons are the viscose rayonacetate rayon and the cuprammonium rayon. Amongst the quite a lot of rayon, viscose rayon isthe most commonly commercially manufacture rayon and in finding extensive software in fabric,tire twine industry, for the reason that as I instructed you previous additionally that the tire cord that has beenone of the fundamental consumer of the factitious fibre however, with the coming of the opposite fibrethe petrochemical headquartered artificial fibre now, increasingly polyester or it usually is the polypropylene fibre or it can be the nylon that’s stepping into tire cord industry. But, the importancedefinitely in view that the viscose that was to be had prior than the approaching of the your thesenylons or it could be the acrylic fibre.So, the significance of the viscose rayon is bothin the oven and non oven. More than a few type of the viscose rayon and thatwe are having the normal rayon, high tenacity rayon, excessive moist modulus rayon, flame retardantrayon, tremendous adsorbent rayon. Viscose rayon has a silk aesthetic with superbdrape and the believe and retains its rich first-rate color, which I confirmed you within the diagram,the snapshot of the viscose fibre first rate color. It has high moisture absorbency similarto cotton and this is the motive why we are ingesting increasingly viscose compositionblend along with the it may be the acrylic fibre or it could be the polyester, becausethe fee of the viscose is less than the cotton, breathable, relaxed to wear and easilydried, since within the earlier stages of the coming of the artifical fibre death used to be alsoa concern for synthetic fibre, chiefly the polyester and the nylon and the lot ofthe development that took position in case of the dye manufacture also and so the dyingthat used to be the extra easier in case of the substitute fibre with the coming of the brand new breed ofthe dyes.So, the in case of the viscose rayon, it iscomfortable delicate skin and has average, considering that that was the softness that was once your problemin case of the polyester when it came into the market due to the fact, most of the cloth 100percent polyester suitings one hundred percentage polyester shirts had been there and so, that wasnot comfortable. So, one of the crucial expertise in case of the viscose and now we can seein market the very soft textile materials are there which is considering of the viscoserayon, the gentle epidermis and has average dry strength and low abrasion resistance and nostatic construct up, as in case of the other polyester and the nylon is there, moderate resistanceto acid and alkali, immoderate flammable, but, that is the one of the vital drawback.Thermal property is negative and loses force about 9 degree chars and decomposes at sothe melting point, this used to be the cause why the from the viscose to nylons or the polyesterin the tire wire industry that was once considering, what we need in case of the tire wire industryhigher melting point and that used to be the rationale for the reason that in case of the nylon and polyesteror the acrylic that’s we are having plus 230 melting factor or the sticking factor.So,that’s the one of the most drawback in case of the viscose rayon that’s the low meltingpoint. Tenacity ranges between 2 point 0 to 2 point6 gram per den right here and dry and 1 point 0 to 1 point 5 den right here when moist. It has poorcrease recovery, when you consider that this is the 1 of the obstacle even in case of the cotton however,thus far the crease is concerned ironing property is there it is higher in case of the polyesteror in case of the nylon but, in case of the viscose and the cotton this the crease problemis there in case when you are utilising in case of the cloth.So, it has negative crease healing and crease retention in evaluation to the polyester becauseof the low melting point decrease utility in the tire wire that is there. But, earlierwhen it was once not on hand the people have been using the viscose rayon additionally however, the yousee the now the speed of the automobiles that’s growing and so, the temperature riseis there and so, we need the more excessive temperature high melting factor material for the tire cordindustry and so, that used to be the transferring from the viscose rayon to your polyester or thenylons.These are the more than a few grades of the viscoserayon types of the rayon: typical high moist modulus, high tenacity, micro fibres, Tencelrayon the lyocell these are the one of the crucial alternate name additionally that is these. These are the some of the most important producersof the rayon. 1 is the century rayon that is on the grounds that; these types of companies are bythe Birla crew considering the fact that they are pioneer in also the paper making. So, century rayon theyare having the 1 unit is at Kalyan, one more the pulp they’re making at the century pulpand paper and that provides Kashipur that they’re having 1 plant. Grasim industry they areheavier polyfibre, these are the opposite that are making the rayon get pulp.Kesoram rayonthey are making rayon, Indian rayon, countrywide rayon, Baroda rayon and so that is the domesticdemand of the viscose So, the applications of the viscose rayon;yarn, then embroidery, chenille, cord, novelty yarn. The material; crepe, garadines, suiting,lace, outwear fabrics and lining of the coats and outwear. So, these are the in case ofthe material we are utilising even the liner section is there have been extra your softness that is required.So, lining part of the coats we’re having the viscose fabric. Apparel are attire, blouses,saris, jackets, lingerie, linings, hats millinery, slacks, sporting activities shirts, sports clothing, suit tiesand the work material. So, these are the probably the most apparel thatwe are making from the home textiles bed spreads, mattress sheets, blankets, curtains, draperies,slip covers, desk clothes and the hosiery. In Industrial textiles, high tenacity rayonis used as reinforcement to mechanical rubber items, tires, conveyor so, right here genuinely therequirement that’s the excessive tenacity rayon, so the tires, conveyor, belts, hoses, applicationwithin the aerospace agriculture textiles industry after which the braided cords and thetapes.Miscellaneous uses; that could be the in the sausage casing, cellophane and thenthe female hygiene. What are the raw substances you see? Right here yousee the predominant uncooked material which we are utilizing for the making of, whether or not it’s viscose rayonor the acetate rayon that’s the cellulose. Then the caustic soda, carbon disulphide,sulphuric acid, titanium oxide to delustre the yarn after which the sodium sulphide, sodiumsulphite, sodium hypochlorite these are the one of the most different clearly the raw materials.1 of the a further foremost uncooked material that we are making use of the carbon disulphide in caseof the viscose rayon, acid and acetate anhyde in case of the opposite rayons that we are using.This is the requirement specifically in case of per ton of the rayon fibre of the variousraw fabric pulp, NaOH, H2SO4, carbon disulphide, zinc sulphate, on account that here the spinning sothat is the spinning bar that we are doing incidentally it is.This is referred to as the regenerationwet spinning that is being executed in case of the viscose rayon and different rayons. These are the more than a few steps concerned in caseof the viscose rayon that is, the first step that is the creation of the dissolving,on account that the pulp which we’re using, considering we are making use of the pulp for making the paperand the information print, here the pulp which we are making use of for the making of the rayon thatwe call the dissolving grade pulp for top alpha cellulose because what’s happeningeven where 1 of the method which we’re making use of in case of your treating with the causticsoda, so, alpha cellulose, high alpha cellulose content material that’s required and so that is thebeta and gamma cellulose which gift that we are disposing of.So, the stripping pressing, shredding aging, xanthation ripening, filtering degassing,extruding by means of spinneret and acid tub drawing, washing and slicing.So these arethe steps. And easy steps we will be able to be discussing in detailbecause there may be significance of the each step within the manufacture of the viscoserayon for the reason that to be able to impact the nice of the viscose that we’re making. First thingthat is the pulp, which we have become, what is going to be the supply of the cellulose. Celluloseused for the manufacture of the viscose rayon. So, rayon grade pulp we call it that we areusing. So, rayon grade pulp or dissolving pulp is the source of the cellulose. Dissolvinggrade pulp is created from the wooden, probably it is the timber pulp that’s favored and especiallythe softwood but, some eucalyptus in view that eucalyptus having the superb nice ofthe pulp so that has been additionally used.So, dissolving grade pulp is constituted of the wood.The pulp will have to have high cellulose low hemicellulose with the uniform molecular weight distribution.Unique bleaching sequence, in view that you see the lot of the detoriation within the qualityand the strength of the pulp is there during the bleaching once we are making use of the conventionalbleaching of the chlorine or chlorine dioxide or the hypo chloride bleaching.Right here, we needthis some of the other modified bleaching sequences for the making of the rayon gradepulp and 1 of them is the enzymatic bleaching. Additionally, the oxygen chlorine dioxide or the oxygendelignification which may be there or it usually is polysulphide pulping. So, different typeof the pulping techniques additionally there but, bleaching we will have take care so, that the minimumdamage is there and even as the selective elimination of the pentagon can also be there whenyou are utilising the enzymes. So, that is the elemental requirement in caseof the your rayon grade pulp and also you see the exceptional, it’s not the similar procedure whichyou are making from the huge system is identical which we’re making the pulp for the papermaking but, right here the detailed pleasant of the rayon grade pulp in an effort to be required formaking with the high alpha cellulose hemicelluloses pentagon all people who must be minimal. So, the first step in case of the manufactureof the viscose rayon is the steeping method. This contain the pulp sheets are placed insteeping compartment and reacted with 18 to twenty percentage NaOH at 20 to 22 degree centigradefor about 1 to four hour, considering you see the cause why if you happen to see the definition of thealpha cellulose beta and gamma cellulose, so, the alpha beta and gamma cellulose whenwe are treating with the 17 point 5 percentage of the NaOH, so, alpha cellulose that remainsas such and the beta and gamma cellulose they dissolve.So, that is the intent of the keepingthe 18 to 20 percentage NaOH. Then what is the purpose? That is 1 purposeto break the intermolecular bonds of the cellulose to develop the solubility of the cellulosexanthate seeing that subsequently, we’re treating with the carbon disulphide for xanthation.So, to convert the cellulose into alkali cellulose seeing that, this alkali cellulose that furtherwe are using. The swell cellulose fibre, on account that the swelling of the fibre and so, the betteractually your reaction of the carbon disulphide to be able to be there, to dissolve the low molecularweight hemi cellulose.Then, the next move in case of the viscoserayon manufacture is the pressing section. This is performed to eliminate the surplus liquid whichis there and so, finally, after the urgent the your cellulose that will go to the shadingand the white crumb that we will be getting, the alkali cellulose received after pressingare result in shredder at about 20 degree centigrade for 90 to a hundred and twenty minutes.This involves shreddingof the pressing sheet, which we are becoming from the previous step, to produce white crumb,which is fluffy which allow air to penetrate with ease inside of.So, on account that if you’re taking as such the pulp if it’s not fluffy then the reactionof, xanthation response which we’re using within the substance levels to be able to be no longer strong.So, this used to be shredding and the making of the white crumb that is also very main stepin case of the viscose rayon manufacture.Then it comes the aging. After shredding thewhite crumb are aged to bring down measure of the polymerization. This entails agingof the crumb via exposure of the white crumb to oxygen. It helps in maintaining theproper viscosity. This is your next step after your shredding. That is the important reactionwhich is taking place in case of the viscose rayon and that is likely one of the very importantreactions that is xanthation the place the we are reacting with the carbon disulphide afteraging.The soda cellulose crumbs are fed into airtight rotating churns, these are also churning process. The procedure involves healing ofthe white crumb with carbon disulphide under controlled condition at 20 to 30 degree centigradeto kind a cellulose xanthate. That is referred to as the yellow crumb, which we are becoming andthis goes for the further processing to get the viscose rayon. The yellow crumb isdissolved in caustic soda to form viscose. Then the next move in case of the viscoserayon is the ripening, filtering and de-aeration. The system includes ripening of the viscoseby keeping it for four to five days, due to the fact that here the low temperature is there and so, thatis additionally 1 of the main requirement in case of the viscose manufacture, by using keepingthis quite a lot of varieties of the fibres being made. Ripeness measured via the Hotteen number, thatis 1 of the number of the ripeness is there.After ripening the ripen viscose is filteredand degassing, degassing is one more step there to remove the air bubbles which is there. Now the let us speak about the spinning of theviscose, for the reason that as I advised you earlier here what are doing? We are doing this bed spinningand that is also referred to as the regenerated mobile. So, spinning of the viscose is done with the aid of wetspinning by passing by way of spinnerette in acid in acid bath leading to formation ofrayon filament. This is your bath composition. Sulphuric acid,sodium sulphate, glucose, zinc sulphate and water. This is the composition of your bathin case of the spinning tub which we known as it the sodium sulphate precipitates sodiumcellulose xanthate into filament type. For this reason sodium sulphate that has been addedand acid converts it into cellulose. Zinc sulphate offers brought force. Extra processinginvolves, after this rayon is formed or the yarn is formed so, what is the next move?Further process involved washing, desulphurising, bleaching, conditioning and drying. Drawing And reducing; Drawing is the processof stretching the rayon filament which is straighten out the fibres, on account that this is1 of the very drawing in the entire circumstances of the fibre drawing is very most important in togive force to the yarn.The continuous yarn is cut into for producing staple fibres. What are the various variables concerned incase of the viscose rayon? The spinning system, temperature and composition of the bathtub, speedof the coagulation, length of the immersion, pace of the spinning, stretch imparted tothe filament, considering the fact that the that is as I advised you the stretch imparted to the filament thatis additionally very foremost. So these are the one of the parameters that are affecting yourspinning process. This is the reaction that is taking placeand the cellulose with NaOH. Then it is the sodium cellulose that you are getting andafter reacting with the carbon disulphide, cellulose xanthate and this cellulose xanthateagain we have become the regenerated cellulose and within the type of the yarn. So, that is the procedure which I discussedabout the manufacture of the viscose rayon. This cellulose sheets in the type of the sheetswe are getting the pulp and that sheet or the pulp sheet or cellulose sheet, whateveryou say it, that is going to the steeping and press section.Then the shredder alkali cellulose getting older tank, xanthation reaction the place the for regulatingthe dissolving tank filtration, ripening, de-aeration, that’s elimination of the air bubbleand then the viscose spinning.These were the in reality the steps which you discussedin detail prior and so, this is the procedure glide diagram and then the viscose spinningthat will go to spinning tub the place the viscose fibre with the intention to be getting. That is aboutyour, it is going to the coagulating bathtub that is the makeup tank the place H2SO4 and Na2SO4that we’re including. So, this is the showering, desulphurisation, the bleaching and the conditioningand drawing. These are the some of the different steps that are concerned.Now let us come to this. This used to be about theviscose rayon. You see, the viscose rayon, as I told you, that is 1 of the very importantpart of synthetic fibre which we’re using in our daily life. Another form of the rayonwhich was produced prior that was once the acetate rayon and that is the simply appearance silklike look. It’s only like the artificial silk we used to name it and we are callingthe acetate rayon. Acetate rayon is the opposite cellulose basedmanmade fibre and has silk like appearance. The uncooked fabric is cellulose, acetic acid,acetic anhydride. Once more the acetic acid or acetic anhydride can also be from the alcohol routeor it usually is from the petrochemical route. Here, the purified cotton linters, where thecotton linters or cellulosic is a cellulose, cellulosic fabric both the cotton lintersthat is the fibre is more stronger than the cellulose, is fed to the acetylator containingacetic anhydride and acetic acid and targeted sulphuric acetylation is implemented at 25to 30 degree centigrade. That is the response combination called the aciddope is allowed for ripening for roughly 10 to twenty hours.In the course of ripening that’s the conversionof the acetate companies takes place. After this, the blend is diluted with water with continuousstirring. During the method flakes acetate rayon isprecipitated which is dried and sent to the spinning bath where dry spinning of the acetaterayon takes place through dissolving in the solvent and passing by way of spinneretted.So, that is not the degenerated as in case of the viscose rayon we’re doing the wetspinning. Right here, in case of the acetate rayon where we’re having dry spinning additionally. Thesolvent is evaporated by scorching air throughout this spinning approach, where the considering that the itwill move by way of the quantity of folds are there in spinnerette and the continuous rayonthat might be getting and the drying of the removal of the your solvent with a view to be there. Activation with the acetic acid; the processinvolves steeping of the purified cotton acetic acid which makes swelling and makes the cellulosemore reactive. So, that was once the rationale of the activation with the acetic acid acetylation,already we mentioned this phase. The pre-handled cotton and the acetic acidis then acetated with the excess acetic acid, acetic anhydride, with sulphuric acid to promotethe reaction.So, 1 a part of the purified cellulose, three part of the acetic anhydride and 5 partof the acetic acid, that’s the mixture. Sulphuric acids as catalyst zero factor 1 section,response is exothermic, the temperature is around 20 measure centigrade for first hourand 25 to 30 measure centigrade for the following 7 to 8 hours. Then the hydrolysis of the triacetate; thetriacetate type is hydrolysed to convert triacetate to diacetate. The consequent combo is pouredin water to precipitate the cellulose acetate fibre with the measure of polymerization 350to four hundred. Homes of the acetate rayon; tenacity 1 point four gram per denser, melting point 230degree centigrade and decompose when melted conveniently, soluble in acetone methyl, ethylketone, methyl acetate, ethyl acetone, chloroform and the ethylene chloride So, this is the spinning, already I told youthis spinning is dissolved in the acetone that we’re utilizing as a solvent after which thefilter de-aerated and passed through the spinnerette in sizzling air environment, which evaporates thesolvent. So, that is the spinning system dry spinning process that we are utilizing. So,low rate and availability here truly as we’re utilizing significant amount of the acetic acidand Acetic anhydride, so, the one of the competitively priced construction to be able to rely uponthe low cost and availability of the acetic acid and acetic anhydride healing of theacetic acid.That may be very fundamental in case of the polyester, also, recovery of the aceticacid that may be very essential. Right here the healing of the acetone that we are making use of for the spinningthat is that needs to be recovered quite simply and economically.So, these are the one of the most problems concerned in case of the 1 of the most important challenge thathas been in case of the the entire rayons, on account that we are utilizing the wooded area uncooked material, meansthe wood for making of the pulp. So, that is from the environment factor of view andthe deforestation factor of view. So, that is the process which I instructed you theacetic anhydride H2SO4, acetic acid and the pulp and the here acetylator. That is thecotton linter or the timber pulp that is going to the acetylation and then the it’s goingaging, precipitation, centrifuging and cellulose acetate for spinning that’s going when weare doing the dry spinning we are doing. This is the reaction that is taking placeduring the acetylation. Now, let us come to an additional primary classification of the cellulosicbase rayon that is the cuprammonium rayon.Despite the fact that the amount of acetate and cuprammoniumis a lot less than what you might have in case of the viscose rayon however, these are the apartof this rayon every other rayons are also there that are created from the ordinary fibre, thatis only a galvinate fibre, soyabeen fibre so, all those things are additionally there. Let usdiscuss now the cuprammonium rayon. Cuprammonium is comprised of reaction of cellulosewith copper salt and ammonia. After bleaching cellulose is added to the ammonia solutionof copper sulphate resulting in formation of cuprammonium cellulose, which is spun intowater and the yarn is washed with acid to cast off the traces of the ammonia and dried.So, this is the approach which we are usingfor the and when you see the here also the shredding and cleansing, caustic digestion, sodium hypochloride for bleaching that we are adding and in case of that is the timber pulp the cottonlinter that is going. So, this is after the shredding given that the extra strong reactionsmay be there and so, the caustic digestion after the shredding that’s been finished. Mixingand decision, filtration, spinning, washing and drying, so, that is the procedure that weare utilizing in case of the cuprammonium. So, this was the actually concerning the variousrayons and that we are manufacturing and as I instructed you within the establishing additionally the viscoserayon that has performed very important function in assembly the demand of the fabric industry.And once more now we are finding the development out there is to use the extra viscose rayonand the various blends of the polyester or the acro nitrate, due to the fact the fee point ofview and at the same time more alleviation is there when you’re having the viscose rayon.So, the one of the actually fundamental obstacle that has been in case of your viscose rayon crops,the entire viscose rayon plants, seeing that here which I forgot tell you, we are utilizing hugeamount of the caustic soda and that caustic soda now lots of the viscose rayon manufacturingthey are having their possess caustic chlorine plant and earlier as you see, earlier than comingof the membrane method, it was best the mercury mobile process that was once getting used within the makingof the caustic chlorine.So, in case of the the entire plants one of theanother obstacle that has been there, the place to move? The place will be chlorine? So, chlorine handlingthat has been 1 of the predominant due to the fact that that needs to be offered somewhere when you consider that duringthe manufacture of the caustic. So, this used to be the 1 of the limitation. One other issue in caseof the viscose rayon, the your atmosphere factor of view when you consider that you see in case of thecarbon disulphide that’s enormously poisonous and the smell of the carbon disulphide that isthere within the plant.So, 1 of the foremost dilemma that has been in case of the viscose rayonis the chemical a part of the chemical factory of the viscose rayon, on the grounds that normallythey are having the in case of the any viscose rayon so one can be 1 of the carbon disulphideunit, caustic chlorine plant after which the finally, the viscose rayon manufacturing.So, just like you take the case of that they are having the membranes also most of nowthe caustic chlorine plant they have got been converted to membrane caustic chlorine plantbut, the obstacle of the this chlorine that there. So, that is 1 of the component which is affectingthe rate of the viscose additionally..