Butyl phenolic resin reactant

Reactant for /-butyl phenolic resins. Magnesium oxide reacts in solution with /-butyl phenolic resin to produce an infusible resinate (Fig. 36) which provides improved heat resistance. The resinate has no melting point and decomposes above 200°C. Although oxides of calcium, lead and lithium can also be used, they are not as efficient as magnesium oxide and also tend to separate from solution. Where clear adhesive solutions are required epoxide resins, zinc-calcium resinates or zinc carbonate can be used. 

As will be discussed in the section on resins, metal oxides also react in solution with r-butyl phenolic resins. The reaction product, an infusible metal resinate, increases the heat resis-aance of adhesive films. Although oxides of calcium, lead, and lithium also exhibit reactivity, magnesium oxide is the most useful and widely used reactant. 

Generally about five parts of zinc oxide and four to eight parts of magnesium oxide are used in adhesives with 40 phr resin. Four parts of the magnesium oxide are included to act as an acid acceptor and to retard scorch. An additional four parts are included as a resin reactant if the adhesive system contains a t-butyl phenolic resin. 

The esterification of -butyl alcohol and oleic acid with a phenol—formaldehydesulfonic acid resin (similar to amberHte IR-100) is essentially second order after an initial slow period (52). The velocity constant is directiy proportional to the surface area of the catalyst per unit weight of reactants. 

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