Phenol Aralkyl Resins

Properties and Applications

Phenol aralkyl resins are a relative new class of synthetic thermosetting resins. They are synthesized by condensation of aralkylethers (such as dimethoxy-p-xylene) with an excess of phenol at temperatures between 70°C to 240°C and in the presence or absence of a catalyst.^1,2 These resins can be crosslinked with epoxies or maleimides at elevated temperatures. The thermosets obtained by these reactions have excellent heat, moisture and chemical resistance as well as excellent mechanical properties including good thermal shock resistance. However, phenol aralkyl resins cure noticeably slower than ordinary phenolic resins and thus require stronger catalysts/accelerators and higher temperatures to achieve full cure. Their sluggish reactivity and their higher price are two major reasons why these resins are less popular than common phenolics.³

Phenol aralkyl resins can be used in a variety of products including heat resistant adhesives, binders, laminates, coatings and molding materials. Due to their good adhesion properties and excellent mechanical properties they can function as matrix resins in glass, carbon and aramid fiber reinforced high-performance composites. One of the most important applications is in the automotive industry where they are used as binders in brake pad and clutch facing disc friction materials.

Manufacturers & Distributors

¹T. Kawabata, Y. Ono, T. Yuasa; Y. Fukui, Preparation Process of Phenol Aralkyl Resins, JP Patent 9,341,191 (1997) & US Patent 6,127,511 (2000)
²T. Kawabata, S. Limuro, T. Yuasa; Phenol Aralkyl Resins, Preparation Process Thereof and Epoxy Resin Compositions, EP0688805A1 (1995)
³The chemical structure of phenol aralkyl resins is very similar to that of novolacs but with xylylene instead of methylene bridges linking the phenolic units. The structural differences, especially the lower concentration of hydroxyl groups, reduces the polarity of the resin which in turn improves chemical resistance and electrical properties.