Chemicals from cashew nut shell

Who knew you can use liquid extracted from cashew nut shell and use it for chemical feedstock?


The blog received this news from BioBased Technologies (a US biobased polyol producer) about their partnership with Palmer International, a US company working with Cashew Nut Shell Liquid (CNSL) for over 50 years. The firms is developing a new bio-based polyols from CNSL in rigid foam systems.

The blog was immediately intrigued about CNSL given the unfamiliarity of this material. After a bit of googling, the blog came across this document submitted to the US EPA (dated June 2002) from New Jersey, US-based Cardolite Corporation about CNSL. Cardolite is another company working on CNSL for decades.

According to Cardolite, CNSL, a source of naturally occuring phenols, is composed of 70% anacardic acid, 18% cardol and 5% cardanol, with the rest made of other phenols via cold, solvent extraction. In technical CNSL (such as heat extracted), the composition is 52% cardanol, 10% cardol, 30% polymeric material and the rest are other substances.

Here are some of the industrial uses of CNSL:

  • CNSL resins have typically been used in the manufacture of friction-resistant components in applications such as brake and clutch linings. CNSL-aldehyde condensation products and CNSL-based phenolic resins are used in applications such as surface coatings, adhesives, varnishes and paints. Various polyamines synthesised from CNSL or cardanol are used as curing agents for epoxy resins.

  • CNSL and its derivatives have been used as antioxidants, plasticisers and processing aids for rubbercompounds and modifiers for plastic materials. Resins based on the reaction products of cardanol phenol and formaldehyde are used to improve the resistance of rubber articles to cracking and ozone. 

  •  CNSL, cardanol and cardol are all used to provide oxidative resistance to sulfur-cured natural rubber products. Cardanol, CNSL or sulfurated CNSL is added to rubber gum stock or nitrile rubber to improve the processability, mechanical properties and resistance to crack and cut properties of the vulcanisates.

  • A number of products based on CNSL are used as antioxidants, stabilisers and demulsifiers for petroleum products. Metal xanthates of partially hydrogenated, sulfurised cardanol is used to lower the pour point of lubricating oils as well as acting as antioxidant and anticorrosive properties. Soluble metal derivatives of CNSL are used to improve the resistance to oxidation and sludge formation of lubricating oils. 

  •  Oxidised CNSL and its derivatives are used as demulsifying agents for water in oil type petroleum emulsions.

Cardolite said it is already offering CNSL-based polyols for polyurethane coatings and rigid polyurethane foams. As for Biobased Technologies and Palmer, the companies said they need to make sure their CNSL-based products will be a drop-in replacement for traditional polyols that they are targeting to replace.

BioBased Technologies will be responsible for R&D of the new polyol in rigid foam systems, marketing and sales of the final product. Palmer will be responsible for scale-up and manufacturing. The partners will use both companies’ existing research and manufacturing facilities.

By the way, a 2004 study by the United Nation’s Food and Agricultural Organization (UN FAO) reported main markets for CNSL back then were the United States, the European Union (mainly the United Kingdom), Japan and the Republic of Korea. Together these account for over 90% of world trade, most of which is supplied by India and Brazil.

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