Hot-setting phenolics

Hot-setting phenolic adhesives are processed for up to 15 minutes at 100-150°C and at 0.7-1.7 MPa bonding pressure. The film form is processed for up to 15 minutes at 120-150°C and at 0.7-1.4 MPa. This type of phenolic is resistant to weather, boiling water, and biodeterioration. It has superior temperature stability to that of the acid-catalyzed form. Applications of this adhesive include fabrication of exterior-grade weather- and boil-proof plywood and for bonding glass to metal for electric light bulbs. ... 

Phenolic Resins [9003-35-4], Curable phenol-formaldehyde resins of the resol type are of considerable importance as hot-setting reactive adhesives for bonding wood and metals. Suitable types are used also in combination with poly(vinyl acetals) and epoxy resins for special, in some cases filmlike, reactive adhesives for bonding metals. 

Plan B. What reagent is hot, cheap, and likely to react quickly at sulfur in a tosylate n-BuLi came immediately to mind, and fortunately, this was actually the ticket to success for this seemingly trivial step. Exposure of tosylate 12 dissolved in THF at 0°C to a standard, commercial source of this base/nucleophile/electron donor in hexanes led to a very clean unmasking to the free phenol 13 upon mild acid workup (Scheme 8). That two equivalents of -BuLi are required for frill consumption of educt (47% yield with only stoichiometric use), is good evidence that an SET process is the likely mechanism, as opposed to... 

The objectives of the extender-filler in glue mixes are to improve the adhesive performance, to help control the mix viscosity and to conserve the phenolic and urea adhesives. These fillers and extenders serve specific needs in these glue mixes. They extend the resin solution from its original non-volatile state to lower levels, such as 26 percent resin solids in the mix. They also function as a means of maintaining the very low resin molecular weight and size molecules on the surface when they are applied to the veneer to prevent over-penetration prior to hot press pressure and temperature which gels the resin to a permanently set condition. 

An emulsion polymer-isocyanate adhesive, a crosslinked polyvinyl acetate adhesive, a resorcinol-formaldehyde adhesive, a phenol-resorcinol-formalde-hyde adhesive, and an acid-catalyzed phenolic-formaldehyde adhesive developed bonds of high shear strength and wood failure at all levels of acetylation in the dry condition. A neoprene contact bond adhesive and a moisture-curing polyurethane hot-melt adhesive performed as well on acetylated wood as untreated wood in tests of dry strength. Only a cold-setting resorcinol-formal-... 

Ozonized fibers of 100-130 g were mixed with powdered phenol resin (PR-311 or PR-11078, Sumitomo Bakelite Co., Ltd.) Addition of the resin was 15-20% on fibers. The fibers were then smoothly set ina25x21 cm form and prepressed between aluminum plates with Teflon sheets. The pre-pressed mat of fibers was hot-pressed at 200°C for 3 minutes with a 2 mm spacer between aluminum plates. 

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