Journal of Scientific & IndustrialTOLIW ResearchAL et al: WATER-SOLUBLE BINDER SYSTEM FROM SOYABEAN OIL 141 Vol. 67, February 2008, pp.141-146 Water-soluble binder system from by product of refining of soyabean oil S D Toliwal*, C J Patel and Kalpen Patel Department of Industrial Chemistry, Institute of Science and Technology for Advanced Studies and Research (ISTAR), Vallabh Vidyanagar 388 120 Received 23 April 2007; revised 23 November 2007; accepted 30 November 2007 Oil recovered from spent bleaching earth (ORSBE), which is used for bleaching of soyabean oil, has been malenized at 210°C using three different mole ratios of oil and maleic anhydride till desirable acid value of resultant product is achieved. Malenized products were neutralized with triethylamine to make them water compatible. N, N-Bis (2-hydroxy ethyl) fatty amide (HEFA) was prepared by reacting ORSBE with diethanolamine using zinc oxide as catalyst. Water compatible malenized products were blended with HEFA in different ratios to prepare water based stoving compositions. Certain compositions had comparable performance with water based alkyd-HEFA compositions. Keywords: HEFA, Oil recovered, ORSBE, Spent bleaching earth, Soyabean oil, Water-soluble binder system Introduction characteristics. It can, therefore, be maleic modified for Water borne coatings1 are increasingly being used for possible value added applications in water borne decorative and industrial coating applications. Malenized coatings. It can also be derivatized to HEFA, which could drying oils are used for manufacture of water-reducible possibly be used as eco-friendly curing agent to formulations for coatings2. Maleic anhydride can be substitute traditional toxic volatile cross linking agents reacted with unsaturated oils to produce maleic for water-based coating formulation. anhydride adduct. Pendent acid group can be neutralized In this study, water-based stoving compositions have with ammonia or amines to yield water-soluble oils been prepared using water compatible malenized (Fig. 1). Application of malenized oils3-8 in water based products blended with HEFA. coating formulations and malenized soyabean oil for other applications9-10 are reported. Use of N, N-Bis (2-hydroxy Materials and Methods ethyl) fatty amide (HEFA) as environment friendly Materials substitute for conventional cross-linking agents for ORSBE was procured from refining unit of Adani coating system has also been reported11-13. Wilmar Limited, Mundra (Gujarat). Physico-chemical Vegetable oil processing generates large quantities analysis15 of oil gave: sp gr30°C, 0.913; acid value, 46.26; of by-products14 like gums, soap-stock, acid oil and spent iodine value, 92.01; and sponification value, 188.63. bleaching earth (oil, 30-35% dry wt basis). Oil associated Fatty acid composition16 of ORSBE was found to be: with spent bleaching earth, being costliest component palmitic, 12.33; stearic, 2.1; oleic, 42.0; linoleic, 33.1; of bleaching, needs to be recovered as much as possible linolenic, 0.3; arachidic, 0.2 %. Commercial grade of though it degrades in quality during the process of conventional water soluble alkyd (CWSA), used as recovery. Oil recovered from spent bleaching earth reference was medium oil soya based alkyd with pendent (ORSBE) for soyabean oil is a by-product of semidrying acid functionality in backbone of polymer, procured from nature, high in linoleic acid and similar in chemical Usha coatings, V U Nagar, (Gujarat) and its physical composition with soyabean oil except physico-chemical properties were determined as per BIS methods17 as: *Author for correspondence color (Gardner) 9; solids, 51.2% and acid value, 71.3. E-mail: toliwalsd@ yahoo.co.in All other chemicals were of laboratory grade. 142 J SCI IND RES VOL 67 FEBRUARY 2008 (A C CHCH C C 2 CH2C CHC C Non conjucted unsatuarted Conjucated carban carban atom C C C C CH2C CHC C + C C C Conjucated carban C C C O C O O C C Maleic anhydride O O O maleic adduct (B) O OH H2C OCOR CH CH OH CH CH OH CH2 2 2 ZnO 2 2 + + OH HC OCOR HN R C N CH2 CH CH OH 200 CH2CH2OH 2 2 CH2 OH H2C OCOR Oil Diethanolamine Glycerol (C C2H 3 + N C2H COO COO COO C2H + + COON+(C H ) COON H(C H5) COON (C2H5) 2 5 (D O CH2CH2OH + R C N COO COO COO CH2CH2OH O COO C O CH2CH N C R CH2CH2O Fig. 1—Reaction scheme for: (A) Malenization of unsaturated oil; (B) Preparation of HEFA; (C) Neutralization of malenized oil; (D) Curing reaction Preparation of HEFA methanol solubility test19. Samples were periodically Oil and diethanolamine18 (1:1) were taken in a three- withdrawn with a siphoning device to study progress of necked flask and heated at 190 ± 5°C using 0.02 M zinc reaction by TLC technique. Heating was stopped when oxide as catalyst with constant stirring for 3 h. sample (1 vol) got mixed with methanol (2 vols) at room Temperature was raised to 200°C and maintained till temperature. After cooling, product was extracted with TOLIWAL et al: WATER-SOLUBLE BINDER SYSTEM FROM SOYABEAN OIL 143 diethyl ether and washed 2-3 times with distilled water Neutralization of Malenized Oil with Triethyl Amine to separate glycerol and unreacted amine. Ether extract Malenized oil was neutralized with triethyl amine was dried over anhydrous sodium sulphate, filtered and (TEA) to get solubility (Table 1). Neutralized mass was ether removed. Product was cooled and stored in diluted (50% solids) using isopropyl alcohol (10%) and anhydrous condition at room temperature. Physico- water (40%). chemical analysis of HEFA gave: sp gr30°C, 0.91; Preparation and Characterization of Stoving Compositions viscosity25°C (Gardner), 4.0 poise; acid value, 2.42; and Diluted solution (50%) of neutralized malenized oil nitrogen content, 3.02 (practical) and 4.86 (theoretical) was blended with water soluble HEFA in four %(wt basis). proportions (85:15, 80:20, 75:25 and 70:30, wt basis) and resulting mixture was diluted (40% solids) and Malenization of ORSBE applied on test panels. Similarly, stoving composition Oil and maleic anhydride20 were taken in three-necked was prepared using CWSA: HEFA (75:25) and applied flask and heated at 200-210°C under constant agitation on test panels. Coated panels were stoved at 120°C for for 3 h. Reaction mass was cooled below 50°C and 45 min for complete curing of the films. Coatings were product was washed with water to remove free maleic tested for non-volatile matter, viscosity, specific gravity, anhydride. Three sets of malenized oil were prepared color and drying and curing characteristics as per BIS (Table 1). methods21 (Table 2). IR spectrum of HEFA, malenized Table 1 – Composition and chemical characteristics of malenized ORSBE Composition Mole ratio of Free* Acid value Amount of code ORSBE: (unreacted) TEA maleic anhydride maleic anhydride required for malenized oil (100 g) % Set I 1.0: 1.0 10.18 110.33 19.23 Set II 2.0: 1.0 15.32 78.10 10.24 Set III 3.0: 1.0 16.01 46.32 8.53 * On the basis of maleic anhydride taken for the reaction Table 2—Physical properties of malenized ORSBE-HEFA based stoving composition Set No. Ratio Non-volatile Viscosity by Color Sp.gravity oil: matter ORSBE (120oC/2h) FCB IV at 30oC (Gardner) at 30oC % 85:15 50.07 186 sec 14 1.02 I 80:20 49.36 180 sec 13 1.04 75:25 46.28 166 sec 12 1.06 70:30 42.13 140 sec 12 1.06 85:15 51.24 190 sec 13 1.00 II 80:20 48.13 172 sec 12 1.00 75:25 44.26 160 sec 12 1.04 70:30 41.18 148 sec 13 1.05 85:15 48.33 188 sec 14 1.02 III 80:20 45.11 182 sec 13 1.04 75:25 41.06 174 sec 12 1.06 70:30 40.23 153 sec 12 1.06 144 J SCI IND RES VOL 67 FEBRUARY 2008 Table 3–Stoved film properties of the stoving compositions Chemical resistance unaffected Set Ratio Scratch Impact Flexibility NaOH HCl Xylene Water No Oil- HEFA Hardness resistance 1/8 “ (3 %) (5 %) 72 h 48 h kg lb.inches mendral 2 h 24 h (Passes) (Passes) 85:15 1.000 55 P 0 1 3 2 I 80:20 1.200 50 F 2 2 2 4 75:25 1.400 55 F 3 4 2 3 70:30 1.500 60 P 4 5 5 4 85:15 1.150 50 P 0 2 2 5 II 80:20 1.250 35 F 1 3 3 4 75:25 1.350 55 F 3 3 1 2 70:30 2.000 65 P 3 4 5 4 85:15 1.400 60 P 0 2 3 0 III 80:20 1.600 45 F 1 4 3 3 75:25 1.700 50 P 3 3 4 4 70:30 2.200 70 P 5 5 4 5 IV CWSA 2.500 76 P 5 4 3 5 P = Passes the test; F = Fails; 0 = Film completely removed; 1 = Slight swelling & cracking; 2 = Film partially cracked; 3 = loss in gloss; 4 = slight loss in gloss; 5 = unaffected Fig. 2—IR spectrum of HEFA ORSBE and malenized ORSBE and HEFA cured film Results and Discussion was determined (Fig. 2). Cured films were evaluated Mechanical Properties for flexibility, scratch hardness, impact strength and Scratch hardness is found to be better with higher resistance to chemicals, water and solvent (Table 3). HEFA ratio for all the experimental sets due to more TOLIWAL et al: WATER-SOLUBLE BINDER SYSTEM FROM SOYABEAN OIL 145 Fig.