High efficiency aqueous resole solutions being stable to crystallization and emulsifiable with method of manufacture
AssigneeMonsanto Company
InventorHarold P. Higginbottom
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Abstract
High efficiency stable aqueous emulsifiable resoles which contain low concentration of free phenol and free formaldehyde and cause substantially less pollution of the atmosphere than prior art resins. The resoles are prepared by a two-stage reaction which controls the molecular weight, water tolerance and the ratio of methylolated 2,2'-, 2,4'- and 4,4'-dihydroxydiphenylmethanes. Stability is promoted by inhibition of the crystallization of bis(4-hydroxy-3,5-dimethylolphenyl) methane.
Claims19
An aqueous solution of an emulsifiable resole wherein the solution has a pH in the range 6 to 8.5 and contains less than 2 percent of free phenol, less than 2 percent of free formaldehyde and between about 1 and about 12 percent of an emulsifier based on the weight of the resole and wherein the resole has a number average molecular weight of less than 300, a water tolerance between about 100 and 800 percent, a combined formaldehyde to phenol molar ratio in the range of 2.0:1 to 2.9:1, and contains sufficient methylolated 2,2'- and 2,4'-dihydroxydiphenylmethanes to inhibit crystallization of the resole solution and wherein the emulsifier is selected to provide a stable emulsion of the resole when water in excess of the water tolerance is added to the solution.
A process of preparing an aqueous storage stable emulsifiable resole solution which comprises:
- a. reacting 1.0 mole phenol with from 0.05 to 0.30 moles formaldehyde under conditions for formation of novolac resin,
- b. adding from 1.75 to 3.5 moles formaldehyde and reacting under basic conditions to produce a resole of molecular weight less than 300, and containing less than 2 weight percent free phenol,
- c. adjusting the pH of the aqueous resole to between about 6 and 8.5, and
- d. adding between 1 and 12 percent of an emulsifier based on the weight of the resole, selected to provide a stable emulsion of the resole when water in excess of the water tolerance is added to the resole solution.
Dependencies are inferred from the claim text.