Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Patent
1981-04-20
1983-02-08
Pertilla, Theodore E.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
524596, 525501, 528147, 528155, C08L 6114
Patent
active
043730620
ABSTRACT:
Phenol-formaldehyde and phenol-resorcinol-formaldehyde resinous aqueous syrups useful as thermosetting binders or adhesives are prepared by reacting, a phenol-formaldehyde resin composition firstly at atmospheric reflux temperature at a substantially neutral pH of 5.8 to 8.5 and a formaldehyde to phenol mol ratio between 1.7 to 2.8 for a period of 20 to 120 minutes; reacting secondly with added formaldehyde, if necessary, and also needed alkali metal hydroxide to produce mol ratios of 2.1 to 2.8 and 0.10 to 0.38, respectively, per mol of phenol, for a period of at least two minutes at reflux to produce a liquid phenol-formaldehyde thermosetting resin. The setting time can be decreased, if desired, by using two portions of syrup, reacting one portion for a greater time-temperature period than the other and combining the two portions. By scavenging the remaining free formaldehyde by addition of a suitable reactant and then adding resorcinol and proceeding with a time-temperature period of copolymerization until the desired viscosity, water dilution tolerance, and potential setting speed upon formaldehyde addition are attained, a phenol-resorcinol-formaldehyde resin is obtained. The liquid resinous product is storable and is useful as an adhesive when activated by the addition of monomeric or polymeric formaldehyde to form a hard solid.
REFERENCES:
patent: 2614096 (1952-10-01), Spahr
patent: 3428593 (1969-02-01), Higginbottom et al.
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