CNSL (Cashew Nut Shell Liquid)

Cashew Nut Shell Liquid

Cashew Nut Shell Liquid or CNSL is a versatile by product of the Cashew industry. The nut has a shell of about 1/8 inch thickness inside which is a soft honeycomb structure containing a dark reddish brown viscous liquid. It is called CASHEW NUT SHELL LIQUID or CNSL. Which is the pericarp fluid of the Cashew Nut. It is often considered as the better and cheaper material for unsaturated phenols.

CNSL has innumerable applications, such as friction linings, paints, laminating resins, rubber compounding resins, cashew cements, polyurethane based polymers, surfactants, epoxy resins, foundry chemicals, and intermediates for chemical industry. It offers much scope and varied opportunities for the development of other tailor-made polymers.

CNSL undergoes all the conventional reactions of phenols, CNSL aldehyde condensation products and CNSL based phenolic Resins are used in applications such as surface coatings, adhesives. Various polyamines synthesised from CNSL are used s curing agents for epoxy resins. CNSL and its derivatives have been used as antioxidants, plasticizers and processing aids for rubber compounds, modifiers for plastic materials and used to provide oxidative resistance sulphur-cured natural rubber products. It is also added to rubber gum stock or nit rile rubber to improve the process ability, mechanical properties and resistance to crack and cut properties of the vulcanises.

Advantages of CNSL based Polymers:

  • Improved Flexibility and reduced brittleness.
  • Solubility in Organic Solvents.
  • Improved Processability.
  • Low Fade Characteristics for Friction.
  • Resistance to 'Cold Wear'.
  • Good Electrical Resistance.
  • Better Water Repellence.
  • Improved alkali and acid resistance.
  • Compatibility with other polymers.
  • Antimicrobial Property.
  • Termite and Insect Resistance.
  • Structural Features for Transformation into High Performance Polymers.



Polymerisation Characteristics of CNSL

CNSL can be polymerised by a variety of methods:

  • Addition Polymerisation through the side chain double bonds using cationic initiators such as sulphuric acid, diethylsulphate etc.
  • Condensation Polymerisation through the phenolic ring with aldehydic compounds.
  • Polymerisation after Chemical Modification to introduce speciality properties.
  • Oxidative Polymerisation.
  • Various Combinations of the above.

Industrial Significance of CNSL

  • Low Cost Phenol.
  • Versatility in Polymerisation and Chemical Modification.
  • Possibilities for Development of High Performance Polymers.
  • Property advantage over phenolics in certain applications such as impact resistance, flexibility, faster heat dissipation etc.

Reactivity

CNSL undergoes all the conventional reactions of phenols. Cardanol differs from phenol only in the C15 side chain. It undergoes the well known formaldehyde condensation reaction of phenols that gives rise to phenolic polymers. Moreover, it can be polymerised through the unsaturation in the side chain although the bulky nature of the side chain restricts the molecular weight attainable to oligomers. One of the significant advantage of the cardanol is its amenability to chemical modification to effect desirable structural changes so as to get specific properties for making tailor-made polymers of high value. Thus, structural changes could be effected at the hydroxyl group, on the aromatic ring and on the side chain.

Packing of CNSL

  • MS Drums/ Plastic Drums
  • IBC Tanks
  • Flexi tanks
  • ISO Tanker