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Primary Products
Cashew Nut Shell Liquid (CNSL Oil)
CNSL Resins
Cardanol Resins
Copper Sulphate – ( CuSo4 )
Zinc Sulphate ( ZnSo4 )
Manganese Sulphate ( MnSo4 )
Alum – Ferric & Non Ferric
Ferous Sulphate
Hydrochloric Acid
Nitric Acid
Sulphuric Acid – ( H2SO4 )
Dilute Sulphuric Acid
Humic Acid
Calcium Chloride
Copper Carbonate
  Cashew Nut Shell Liquid (CNSL Oil)

The raw cashew 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 the cashew nut shell liquid (CNSL), which is the pericarp fluid of the cashew nut. It is obtained by the process of roasting of raw cashew nut shell.

Cashew Nut Shell Liquid is considered as a cost effective modern material, in the search for the cost effective modern materials, CNSL and its products have a significant role to play. Being renewable, it offers much advantage over synthetics. Its versatility stems from its innumerable applications in many areas. Recent research has shown that the constituents of CNSL possess special structural features for transformation into specialty chemicals and high value polymers. This involves a value addition of many orders of magnitude and the chemical transformation provides 100% chemically pure products. Thus, CNSL offers vast scope and opportunities for the production of specialty chemicals, high value products and polymers.


Cashew Nut Shell Liquid has innumerable applications in polymer based industries such as friction linings, paints and varnishes, 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. There are more than 200 patents on CNSL for its industrial applications

  Some common Applications

Manufacturing of C.N.S.L Based Resins, Varnishes

Manufacturing of Cardanol (Card Phenol)

Manufacturing of Foundry Resins

Manufacturing of Anti Corrosive Lining Chemicals

Manufacturing of Acid resistant Paints

Manufacturing of Insecticides and Fungicides

Manufacturing of Rubber Compounding Resins

Manufacturing of Cashew Lacquers

Manufacturing of Enamels / Paints


Advantages of C.N.S.L based Polymers


Improved flexibility and reduced brittleness

Solubility in organic solvents

Improved process ability

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

Polymerization Characteristics of C.N.S.L
C.N.S.L can be polymerized by a variety of methods


Additional polymerization through the side chain double bonds using cationic initiators such as sulphuric acid, diethylsulphate etc.

Condensation polymerization through the phenolic ring with aldehydic compounds.

Polymerization after chemical modification to introduce specialty properties.

Oxidative polymerization.

Various combinations of the above

  Industrial Significance of C.N.S.L

Low cost Phenol

Versatility in polymerization and chemicals modification.

Possibilities for development of high performance polymers.

Property advantage over phenolics in certain application such as impact resistance, flexibility, faster heat dissipation etc.


C.N.S.L 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 polymerized 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 advantages 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.
Raw Cashew Nut Shell is processed by two methods i.e.
(a) Roasting process (b) Oil extraction process
Some manufacturers use the first method while some others prefer the second method from which the oil is obtained as a by-product.

Raw Cashew Nut Shell contains over 20% CNSL. In the oil bath process about 10% of oil is recovered as a by-product. By using expellers for extraction, it is possible to extract a further quantity of about 10% more from the shells. Thus from 1 tonne of shells using oil bath process, up to 100 Kg of good quality of CNSL could be extracted by using oil expellers.
  Quality Control and Standards

(i) The revised specifications of the Indian Standards Institution, New Delhi, for untreated cashew nut shell liquid (IS 840:1964) is reproduced below


Specific gravity 30 degree C

0.950 to 0.97

Viscosity at 30 degree C, in centipoises


Moisture, % by weight


Matter insoluble in toluene, % by weight


Loss in weight on heating, % by weight


Ash, % by weight


Iodine value

a) Wij’s method


b) Catalytic method



a) Time in minutes


b) Viscosity at 30 degree C, in centipoises


c) Viscosity after acid washing at 30ºC, in centipoises



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