Oxidative paraffinic products for use as leather lubricants/fatliquors

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1 ndian Jurnal f Chemical Technlgy YL 3, March 1996, pp. 1-6 Oxidative paraffinic prducts fr use as leather lubricants/fatliqurs V Haribabu, C Saikumar,S C Sumathi & S C Shaw Central Leather Research nstitute, Adyar, Madras , ndia Received 1 Januafy 1995; accepted 15 May 1995 Lubricatin f leather is dne by using the prcess f fatliquring in which fatty cnstituents frm marine, vegetable and synthetic surces are used after sulphitatin and sulphnatin. The present study is devted t the xidatin f paraffinic hydrcarbns fr preparatin f base' material fr leather lubricatin. The cndi~n f xidatin and the effect f catalyst are dealt at length. The xidised paraffins are als subjected t dispersability studies and leather applicatins. The investigatins reveal that xidised paraffin frmulatin d impart smewhat limited lubricating effect, but lacks sufficient dispersability and fixatin. Lubricatin f leather is an imprtant prcess which makes it supple, sft and pliable in additin t cnferring mechanical stability. Hllstein 1 defines lubricatin and fatliquring as a means t disperse fat int the three-dimensinal fibre structure f leather t cmpensate fr the lss f natural fatty' substances during the earlier stages f liming and deliming prcess f leather making. Thus a variety f fatty substances ranging frm naturally ccurring vegetable ils, marine ils and animal fats t the synthetic fatty acids based n hydrcarbns have fund applicatin in the fatliquring peratin as lubricants fr leather2-4 Fatliquring peratin is designed t intrduce the ils and fats int the leather matrix in finely dispersed frm in water medium. This has been usually achieved by emulsificatin prcesses thrugh intrductin f sulphate, sulphnate and sulphite salls int the structure f ils and fats5 6 Depending n the nature f ils and fats the physical and chemical prperties f prcessed leathers vary widely. Therefre, t strike the ptimum balance, usually a blend f varius ils and synthetic hydrcarbns are used as lubricants 7 The recent trend in leather prcessing places emphasis n envirnment friendly prcesses and use f multifunctinal prducts which help in reducing the pllutin and prmte gd fixatin in the leather matrices. The interactin f leather prtein cnagen with varius functinal grups invlving synthetic tannins, fatliquring and mineral tannages has been the subject f interest in recent Present address: Departrnenl f Chemistry, Patna University, Patna times8- One aspect which is cnsidered significant is that hydrphbic interactins play a majr rle in many f these prcessesll. Further, the fixatin f varius tannins and lubricants are due t the frmatin f plyinic netwrks (PNs) between amin acids f cllagen and the inic and nn-inic functinal grups present in these prducts 12. Therefre, by emplying multifunctinal reagents the interactin and fixatin effect get enhanced. n the present study, lng chain hydrcarbns have been subjected t air xidatin t generate carbnyl cmpunds and fatty acids which are then tested fr leather applicatins. The xidative cnditins like catalyst, temperature and air flw rate have a bearing and these have been dealt at length t ptimie these parameters. Experimental Prcedure N-paraffin, manganese leate, manganese stearate, manganese palmitate, manganese ricinleate, Surce: PCL, Vaddra, ndia Table -P.araffin characteristcs Prperty Value Biling range C Specific gravity Chain length C14-C15 5-% C % C17-CS -15% C19-C20 5-% Average mlecular weight 226

2 2 NDAN 1. CHEM. TECHNOL., MARCH 1996 cbalt naphthenate and manganese naphthenate are used. The paraffin characteristics are given in Table 1. Air xidatin prcedure Fr air xidatin, the apparatus cnsisted f a cylindrical glass tube with tw necks at the tp and ne side tube at the bttm. A thermmeter was placed n ne neck and the ther neck was fitted with a Dean and Stark arrangement. The glass cylinder was surrunded by means f an insulated metal jacket. Air rendered dry by means f passing thrugh cncentrated sulphuric acid, CaCl2 and dried silica gel was sent thrugh a rtameter t measure the flw rate and it was then led t the glass cylinder thrugh a finely sintered plate which dispersed the air current unifrmly. Apprpriate quantities f paraffin was placed in the glass cylinder and the apprpriate catalyst was added t the paraffin and mixed thrughly. The thermmeter was then placed in cntact with the paraffin and the cntents were heated. As sn as the desired temperature was reached, the air flw rate was adjusted by rtameter and the xidatin dne fr the specified perid f time. Samples were drawn peridically and tested fr acid value and carbnyl value. Acid value-t gives a measure f available free fatty acid cntent in an il. Acid number is defined as the number f milligrams f ptassium hydrxide t neutralise the free fatty acids present in 1 g f the il. O.N alchlic ptassium hydrxide (AR) is prepared and standardised against ptassium hydrgen phthalate (LR). A slvent mixture f benene and ethyl alchl (2:1, V/V) is prepared and kept vernight. Abut 1 t 2 g f il is weighed int a rund bttm flask and 40 ml f the slvent mixture is added. The flask with the cntents is warmed and shaken thrughly t disslve the il and cled. One ml f the indicatr is added and titrated against 0.1 N alchlic pt~ssium hydrxide till a permanent pink clur persi'sts. A blank is als run in the same manner, excluding sample frm the abve prcedure. The acid value is calculated as given belw: Acid value'= 5.6~ x (E - b) w where w is weight f sample; a is vlume f alchlic ptassium hydrxide used fr the experiment; b is vlume f alchlic ptassium hydrxide used fr the blank. Carbnyl value-this methd gives the ttal amunt f carbnyl grups present in the sample under study. t is expressed as a percentage f carbnyl grups present in the xidised hydrcarbn. Standardise perchlric acid slutin using standard tris (hydrxy methyl) aminmethane. Weigh 2 g f the sample in 150 ml glass stppered flask. Add exactly 20 ml f 2-dimethyl aminethanl slutin (O,25M) and then 25 ml f hydrxylamine hydrchlride slutin (0.4M). Stpper the flask, swirl gently t mix and let it stand fr the required length f time. Ten minutes at rm temperature is sufficient fr mst f the. aldehydes and simple aliphatic ketnes. Sme ketnes take lnger reactin time, vi., aryl ketnes, hindered aliphatic cmpunds and dicarbnyl cmpunds require apprximately a perid f 45 min r lnger at 70De. Add 5 drps f Martius yellw indicatr and titrate against 0.2 M perchlric acid. Nte the change frm yellw t clurless r blue-grey as end-pint. Cnduct a blank experiment. VXmxM Percentage carbnyl cmpunds = where V= Vb - Vs = (vlume f perchlric acid slutin required t neutralise blank) - (vlume vf perchlric acid required t neutralise sample slutin); m= mlarity f perchlric acid slutin; M = mlecular weight f sample; W= weight f sample taken. The R spectra fr N-paraffin and after xidatin are shwn in Figs 1 and 2. The peak bservances are recrded in Table 2. The xidised paraffin btained by using different catalysts were subjected t emulsificatin studies by dispersin in water as such and with the aid f aninic emulsifi- Table 2-R Data fr N-paraffin and xidised paraffin Absrbance N-parartm Oxidised paraffin - CH3 stretching vibratin -CH2grups C - CH3 defrmatn Acid grups Aldehyde grups Ketnic grups 2950cm~(B) B-Brad band, S-Single sharp peak 2950cm-(B) 2800 cm- (B) 2850 cm- (B) 1460 and 1470 and 1380 cm - 1 (S) 1385 cm - (S) 1715 cm- (verlapping peaks fr all three)

3 HARBABU et af.: OXDATVE PARAFFNC PRODUCTS AS LEATHER LUBRCANTS : gj ~ 40.. a: in ~ 40.. a: ~ ~br---t cm cm-1 4 Fig. l-r spectra f raw paraffin Fig. 2-R spectra f xidised paraffin % NO(A) ND(A) PE(F) % 20% PEPE ME 15% ME Withut Carbnyl emulsifier TableWith 3-Dispersibility 5%SLS characteristics in water ND Nt dispersible ND(A)'Nt dispersible with immediate phase separatin PE Partial emulsifi~atin PE(F) Partial emulsificatin with flccui.-till ME Mderate emulsificatin Table 4-Effects f xidised parafin n fatilquring prperties f leather Prperty Oxyparaffin* Oxyparaffin Cntrl** as such with 5% SLS Slvent extractable matter % Water (i) Time absrptin in minutes (dynamic) *Using manganese stearate as catalyst **A mixture f cmmercially available synthetic and vegetable il based fatliqurs er,(table 3). Oxidised paraffin samples were tested fr fatliquring and lubricating effects in cmparisn with cnventinal fatliqurs and the results are given in Table 4. Results and Discussin Several studies n xidatin f paraffin reveal that the chice f catalyst and the nature f paraffin cmpunds play a majr rle in determinfng the end prduct' 3, 14. The mechanism invlved in liquid phase xidatin has been studied by Kbe and MckettalS and Enamall6 and the reactin prceeds in well-defined stages, vi., (i) hydrperxide frmatin and (ii) interactin f hydrperxides t

4 4 NDAN J. CHEM. TECHNOL., MARCH 1996 give varius end prducts. This mechanism S sh}vllin Scheme 1. CH3- CHrlCH2120CH2 1 ~OJ - CH2 -c~ CH3 - CH2-CH2120-~ -CH 2-C~ OOH CH3-CH2 -COCH2118-CH2-COOH.-----CH3 (Ket acid)./ Hydrperx ide CH3- CH2 - CH2) 20- CH- cii'2-ch3-ch. 3~-(CH 2120-COCH2- CH3 OH Ketne (Alchl) ~ Acid ~ ~ SCHEMf: FOg g~qaton OF PARAFFN CH3-CH2-C.H2120-COOH +C2H6 - CH2 -Ctt-(CH2118-CH2 -COOH OH (Hydrx y acid) The frmatin f xy prducts were cnfirmed by cmparing R spectra f raw paraffm with that f xidised paraffin. The R spectra are shwn in Figs 1 and 2 and the results f peaks given in Table 2 indicate the frmatin f desired end prducts namely the carbnyl cmpunds and fatty acids during xidatin.. Further, the effects f catalyst n the xidatin f paraffin fr the varius catalysts are shwn in Figs 3 and 4 and the values are given in Tables 5 and 6. t has been bserved that Mn leate was very effective in giving the maximum acid value while a carbnyl value f abut 6 was btained with Mn stearate. Therefre, the Mn salts are preferable t cbalt salts in terms f catalytic activity. Similarly, the time f xidatin and the effect f air flw rate have been studied using manganese stearate alne and are represented in Figs 5 and 6 and values are given in Tables 7 and 8. Frm these studies, it is clear that the xidatin f paraffin leads t xy cmpunds and fatty acids which culd then be tested fr applicatin nt leather.. Fr this purpse, it becmes essential t study the dispersibility characteristics f xidised prducts in water s that the resultant slutin culd be used fr lubricating purpse. The individial cmpunds were dispersed in water up t a cncentratin f 20% starting frm a limit f 5%. The results f these studies are given in Table 3. The results indic&te that the xidised paraffin cmpunds were nly partially miscible and the emulsificatin characteristics were nt gd enugh and there was a tendency fr phase separatin. Nevertheless, the xidised paraffin, btained using manganese stearate as catalyst was applied n the leather after dispersing in water and leather characteristics were studied. The xidised paraffins were als emulsified using sdium lauryl sulphate (SLS) (aninic emulsifier) at 5% cncentratin based n the weight f.. '5.. ~" ClO Mal)ganese Recinlett" 2. Manganese Naphth«lQte 3. Manganen Palmitate 4:Cball Naphthenate 5.Mangnen Stearte 4h:.ManganeH Olea~ Cbalt Naphthenate 2. Manganese Nphthenate 3 Manganese Recinleate 4 Mangant-se Oleate 5.Manganese Palmitate 6 Manganese Stearate ClO!..., 2 ;;)... c> Q U C CATALYST Fg. 3- The effect f catalysts n the xidatin f paraffin (acid values) Fig. 4- The effect f catalysts n the xidatin f paraffin (carbnyl values)

5 HARBABU et at.: OXDATVE PARAFFNC PRODUC'TS AS LEATHER LUBRCANTS 5 xidied paraffin. The frmatin f emulsin was again studied fr cncentratin range f xidised paraffin frm 5 t 20% while keeping SLS cncentratin at 5% based n the weight f xidied paraffin. t was bserved that up t a cncentratin f % f xidied paraffin, emulsificatin was achieved sati~factrily and beynd this cncentratin the emulsin tended t flcculate. The emulsin thus, btained using % f xidised.paraffin btained using man!anese stearate Table 5-Effect f catralysts n the yield f acidic grups as determined by acid value Cncentratin =0.1 % Time = 24 h Temperature = 1 C Air flw rate = 70 LPH Name f ciualyst Acid value Manganese ricinleate Manganese nllphthenate Manganese palmitate Cbalt naphthenate Manganese stearate Manganese leate (mgfkoh/gfil) Table 6-Effect f catalysts n the yield f carbnyl value Cncentratin =0.1 % Time = 24 h Temperature'" 1 C Air flw rate = 70 LPH Name f catalyst % yield f carbnyl value Cbalt naphthenate 0.7 Manganese naphthenate 1.6 Manganese ricinleate 2.48 Manganese leate 3. ~8 Manganese palmitate 3.23 Manganese stearate 5.66 as catalyst and 5% SLS was als tested n leather fr its lubricatin effect. Frm the leather studies, as can be seen in Table 4, the results suggest that uptake f the pdised paraffin tk place nly marginally and mst f it remained n the surface f leather, thereby indicating lack f penetratin due t the presence f hydrphbic mieties. The lubricatin effect fqr this was very lw. The emulsified xidised paraffin when applied n leather shwed imprvements in penetratin and lubricatin was marginally better. Hwever, there is a tendency fr wetting and cnsequently the water absrptin values were higher. The studies indicate that the xidised paraffins having multifunctinality are ptential base materi- Table i-effect f air flw rate n the yield f acid value Catalyst: Manganese stearate (0.1%) Temperature: 95 C Time h 5 15 Yield f acid value (mg f KOHl g f il) Air flw rate 70LPH LPH Table 8-Effect f air flw rate n the yield f carbnyl.value Catalyst: Manganese stearate (0.1%) Temperature: 95 C Time h LPH % yield f carbnyl value Air flw rate 0LPH AR FLOW RATE MANGANESE STEARATE ~3-0!? e~ 2 0 ell E ;:)... ~ H U c 0-70 LPH.-0 LPH 12,~ 8... ~ ~ 6 ~ ~ u 4 i AR FLOW RATE 0-70 LPH.-0 LPH MANGANESE STEARATE _./... " " "",'" TME h Fig. 5- The effect f air flw rate and time f xidatin n lcid values 4 8 TME, ~ Fig. 6- The effect f air flw rate and time f xidatin n carbnyl values 12

6 6 NDAN 1. CHEM. TECHNOL., MARCH 1996 al fr lubricatin, filling and fr fixatin prvided prper hydrphilic/hydrphbic balance is built int the structure. These studies further reveal that a prper mdificatin in terms f the hydrphbic/hydrphilic balance is needed s that a stable emulsin with unifrm distributin characteristics are btained. Cnclusin Oxidatin f paraffin and frmatin f multifunctinal.grups give lubricatin effects n leather. Hwever, these alne are nt sufficient in terms' f frmatin f a stable emulsin and gd fixatin. Therefre, ther means f mdificatin are required fr enhancing the perfrmance characteristics f the xidised prducts. References 1 Hllstein H, Das Leder, 23 (1972) Bailey A E, ndustrial il and fatty prducts, 2nd ed (nterscience, New Yrk), 1951, 3 Krishenhaver H G, Fats and ils: An utline f their chemistry and technlgy, 2nd ed (Reinhld, New Yrk), Asinger F P, Paraffin chemistry and technlgy (Pergamn Press, Oxfrd), Maei F, Reavistade-la Assciatin Agrentinade ls Quimics, Y Tecnics de la ndustria delacuer, (1968). 6 Cellades R & Cllaghan A 0, Bl Ass Quim Esp nd Cuer, 15(1) (1964) Mclangiein G D & Theis E R, Chemistry f Leather Manufacture ACD 5 Mngraph, 1 (1945) Vinklarek, Vndrusku & Kupec, J Sc Leather Trade Chem, 74 (1990) Krenek Z, Vinklarek Z, Mikulik J & Vmhustek M, J Sc Leather Trade Chem, 75(3) (1990). Tuichidu, Abe & Hnma, Macrmlecules, 9 (1976) Tamfrd C, The hydrphbic effect, Frmatin f micelles and bilgical membranes (Wiley, New Yrk), Almela M, Maldnad E, Oter A & Cstalpe J, J Sc Leather Trade Chem, 76 (1992) PerchenkA A, Maslb-Zhi Prm, 25 (1959) Baskhirv A N, Kim Nauke Prm, 1 (1956) Kbe K A & Mcketta J J, Advance in petrleum chemistry and refining (nterscience, New Yrk), 1960, Enamel N M, The xidatin f hydrcarbns in the liquid phase (Pergamn Press, Oxfrd),

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