Cashew resin

Unmodified or rubber-modified liquid cashew resins have been used to make wet drum lining mixes. These resins are inexpensive and help to improve product... 

The resins can be a novolak—hexa or a resole—novolak blend. In some appHcations Hquid resoles are used. Addition of alkylated phenol, oil, or cashew nutsheU Hquid (CNSL) reduces hardness and increases abrasion resistance. Modification by mbber improves the coefficient of friction and reduces brake fading. 

Property Modifiers. Property modifiers can, in general, be divided into two classes nonabrasive and abrasive, and the nonabrasive modifiers can be further classified as high friction or low friction. The most frequently used nonabrasive modifier is a cured resinous friction dust derived from cashew nutshell Hquid (see Nuts). Ground mbber is used in particle sizes similar to or slightly coarser than those of the cashew friction dusts for noise, wear, and abrasion control. Carbon black (qv), petroleum coke flour, natural and synthetic graphite, or other carbonaceous materials (see Carbon) are used to control the friction and improve wear, when abrasives are used, or to reduce noise. The above mentioned modifiers are primarily used in organic and semimetallic materials, except for graphite which is used in all friction materials. 

Other higher boiling phenolic bodies obtainable from coal tar distillates are sometimes used in the manufacture of oil-soluble resins. Mention may also be made of cashew nut shell liquid which contains phenolic bodies and which is used in certain specialised applications. 

During the past four decades phenolic resins have become of increased significance in rubber compounding. For example, the resin based on cashew nut shell liquid, which contains phenolic bodies such as anacardic acid (Figure 23.23), may, when blended with hexamine, be incorporated into nitrile rubber (butadiene-acrylonitrile rubber). 

Structural carbon shapes fabricated by heating coke with a mixture of tar and pitches are porous and are made impermeable by impregnation with a resin (usually a phenolic resin). Cashew nut shell liquid resin is used when resistance to alkalis and acids is required. 

Resol resins thermoset on heating and are used for adhesives. Novolacs require a further source of formaldehyde in the form of hexamethylenetetramine to produce molding powders. Phenolic moldings are resistant to heat, chemicals, and moisture with good electrical and heat insulation qualities. Complex phenols from, e.g., cashew-nut shell liquid, are used in making brake... 

Akajou, m. acajou (either cashew or mahogany tree), -harz, n. acajou resin, -nuss, /. cashew nut, -31, n. cashew (nut) oil. Akaridentod, m. acaricide. 

Development of Value Added Polymer Resins Products from Cashew Nut Shell Liquid, Project report No. RT.09/MO/50, Regional Research Laboratory, Trivandrum (1987). 

Substituted phenols such as cresols, p-fcrf-butylphenol, / -phcnylphenol, resorcinol, and cardanol (derived from cashew nut shells) have also been used as precursors for phenolic resins. Alkylphenols with at least three carbons in the substituent lead to more hydrophobic phenolic resins that are compatible with many oils, natural resins, and rubbers.7 Such alkylphenolic resins are used as modifying and crosslinking agents for oil varnishes, as coatings and printing inks, and as antioxidants and stabilizers. Bisphenol-A (2,2-p-hydroxyphenylpropane),... 

Cardanol, a main component obtained by thermal treatment of cashew nut shell liquid (CNSL), is a phenol derivative having mainly the meta substituent of a C15 unsaturated hydrocarbon chain with one to three double bonds as the major. Since CNSL is nearly one-third of the total nut weight, a great amount of CNSL is obtained as byproducts from mechanical processes for the edible use of the cashew kernel. Only a small part of cardanol obtained in the production of cashew kernel is used in industrial fields, though it has various potential industrial utilizations such as resins, friction-lining materials, and surface coatings. Therefore, development of new applications for cardanol is very attractive. 

Talbiersky, J., Polaczek, J., Ramamoorty, R. and Shishlov, O. (2000) Phenols from cashew nut shell oil as a feedstock for making resins and chemicals. OIL GAS European Magazine, 35, 33-40. 

This is used in manufacture of brake linings and is a polymer based on cashew nutshell liquid admixed with formaldehyde or furfuraldehyde and other ingredients. The polymerised resin mixture is cast into 8 cm thick slabs and then ground finely to produce the friction dust. Several fires have been experienced during bulk storage of the dust, attributed to autoxidation of the still partially unsaturated resin compound. Previously, linseed oil was used in place of the nutshell liquid, but fires were then more frequent. 

Synthesis Epoxy resins consisting ofglycidyl ether, ester and amines are generally prepared by the condensation reaction between diol, dibasic acid or amine and epichlorohydrin in the presence of sodium hydroxide with the elimination of hydrochloric acid. The commercially available epoxy resins are, however, made by the reaction of epichlorohydrin and bisphenol-A. Cashew nut shell liquid (CNSL)-based novolac epoxy resins have also been reported [342]. 

Cashew nut shell liquid (CNSL) is the exudate from the cashew nut shell. It is mainly phenolic in nature. Industrially used for making polymeric resins etc. A bath of the CNSL is traditionally used for heating the whole nuts with shells. 

Special grades of glycidyl ether epoxies have been made with components such as glycerol, polyglycols, pentaerythritol, and cashew nut oil. Other epoxy-polyglycidol resins have been produced from the reaction of epichlorohydrin and polyester polyol based on... 

Epoxy resins derived from acid functional oils (dimer acid, cashew nut oil, and Castor oil)... 

Commercial products are available where n varies from 2 to 7. The flexible epoxy resins based on polyglycol also make excellent reactive diluents because they have a viscosity of 100 cP at 25°C. Table 4.4 shows the effect of two polyglycol diepoxides on the physical properties of a cured epoxy system. Another type of flexible epoxy resin is derived from dimerized unsaturated fatty acid, cashew nut oils, and other vegetable oils. Other flexible epoxy resins can be made with thiols, aliphatic acids, and hydroxyl-terminated compounds. Applications where flexible epoxy resins are valued include... 

Thermosetting resins similar to Bakelite (Section 30.7) have also been prepared from renewable feedstocks. One method uses cardinol, the major constituent of the liquid obtained from roasted cashew nutshells. What polymer is obtained when cardinol is treated with formaldehyde (H2C=0) in the presence of a proton source ... 

Many efforts have been made to base polymers on furfural made from pentoses.159 The polymers may be useful, but tend to have lower thermal stability than the usual synthetic polymers. Polyesters based on furfural were mentioned earlier. The acid-catalyzed polymerization of furfuryl alcohol is used in foundry cores.160 Furfural has been condensed with cardanol (m-pentadecadienylphenol) from cashew nut shell oil in the presence of other phenols to produce polymeric resins.161 Cardanol and hydrogenated cardanol have been polymerized with horseradish peroxidase to soluble polymers in up to 85% yield.162 Plasticizers that are effective in polyvinyl chloride, such as (12.31), have been made from furfural.163... 

The primary objective in cashew processing has been to recover the desirable kernel. The by-product, technical cashew nut-shell liquid, later became of interest as a raw material for friction dusts with superior properties to previous materials which were based on composites of phenol/formaldehyde resins with highly unsaturated glyceride oils. Because of its intractability the cashew nut has been termed in Mozambique, the devil s nut Most CNSL world-wide is now extracted or cracked by an automated process (refs. 170, 177), the hot CNSL bath method, developed comparatively recently, in which raw humidified cashew nuts are submerged in technical CNSL on a slowly-travelling conveyer belt and heated to... 

Other epoxy resins are also being manufactured, but their commercial j utilization is not so far advanced as those based on bisphenol A and i epichlorohydrin. For instance, resorcinol and a mixture of diphenol-poly-(hydroxyphenyl)-pentadecanes, obtained by the addition reaction of phenol with an unsaturated phenol derived from cashew-nut oil (see structure below) can be reacted with epichlorohydrin to produce epoxy resins. ... 

Other resins, such as resorcinol and cashew nut resins, other acidic catalysts, such as p-toluene sulfonic acid and other aggregates, such as asbestos, glass flakes, and slag microfibers (PMF) have been substituted for the original ingredients but basically the formulations for the relatively widely used phenolic resin mortars have not changed radically during more than a half century of satisfactory use. 

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