Cardanol - Cashew Phenol
Commercial CNSL Under reduced Pressure was distilled at a temperature of 225o C under reduced pressure (1mm of Hg) to obtain cardanol. A pale yellow to brown liquid of refractive index 1.5 at 30o C . Cardanol is a phenol that has a C15 unsaturated alkyl chain with 1-3 double bonds at m-position. Cardanol is a mixture of cardanol 90% and cardol 10%.
Application of Cardanolti
Laminating Industry -Resole type cardanol formaldehyde resin solution in slcohol are used as adhesives for laminates
All types of bondings -Alkemine condensates of cardanol are powerful adhesives used in metal to metal bonding
Insulating Varnish-Cardanol used as diluents in bis-phenol based epoxy resin provides extremely good insulating properties.
Putty and electrical-Polyurethane resins of cardanol are used in sealants encapsulating puttys.
Surface active agents (Emulsifiers, dispersants and wetting agents)-
Ethoxylated cardanol and sulfonated ethers of cardanol are used as oil in water emulsifiers in pesticides and as wetting agent in textile industries.
Specifications of Cardanol
Specifications of Cardanol
Properties Grade-I Grade-II
Appearance Water White Pale Straw Yellow
Color on Gardner Scale Max 5 Min 12
Specific Gravity @ 30 Degree Celsius 0.92+-0.01 0.93+-0.01
Viscosity CPS Max 45 Max 65
Viscosity @ 30 Degree Celsius Sec bt f4 CUP 21+-1 25+2
Ash Content % NIL NIL
Volatiles at 163 Degree Celsius Max 1.0 Max 1.0
Acid Value mg KOH/g Max 3.0 Max 5.0
Iodine Value (wiz's method) 200+-20 200+-20
Polymerization time in Mins Max 12 Max 10
Boiling point Degree celcius @ VAC.3 to 5 TORR 215-218 225-230
CArdanol processing technology
Cardnol is distilled from Cashew Nut Shell Liquid. A batch of Decarboxylated CNSL is heated to 280degree celcius under Vaccum in a reactor. After few minutes of heating the vapours of Cardanol come into the condenser where it is cooled using suitable coolant to convert the vapour into liquid.
The liquid is collected into a reciever. The process runs for a fixed time after which the receivers and reactors are emptied and fresh batch is started. The Cardanol is filled in tanks or barrels and Residol in barrels after few minutes of cooling.
Samples are drawn for preliminary testing of Colour, Viscosity and pH.
Cashew nut shell liquid from different sources is purchased and stored separately for distillation.
Cashew nut shell liquid is measured using a batch tank and taken into reactor where it is distilled under vacuum at 280 degree celcius.
After the stipulated batch time , Cardanol (Grade 2) is drained from the receiver and stored in vacuum tanks or packed in drums as required . Residol is drained from the reactor into a cooling tank and stored in MS drums .
Some customers prefer double distilled cardanol also known as Grade 1 Cardanol. This is manufatured by re distilling the Cardanol at low temperature under vacuum. The distillate is almost colourless liquid and has application is many products like PU resins etc.
Residol is a thick viscous liquid formed due to polymerisation on non Cardanol components in Cashew Nut Shell Liquid . Residol in cold conditions is highly viscous and often during winters requires external heating of drums to discharge the residol. To avoid this few manufacturers prefer residol to be diluted with cashew nut shell liquid . Depending upon the viscosity requirement of customers , appropriate amount of CNSL is added.
Process Flow of Cardanol & Residol Manufacturing
Packing of Cardanol
Cardanol has a tendency to oxidise and acquire colour on exposure to light and air. Depending upon the time of storage of cardanol , one can either go for MS drums or GI drums. Cardanol retains its natural colour best in GI drums. Drums usually hold 190/195 kgs net weight of cardanol only.
Bulk consumers can however prefer ISO tanks , Flexi tanks , Tanker trucks etc.