| 摘要 |
In the preparation of resin solutions such as lacquers, as described in the parent Specification, in which phenolaldehyde resins in the resitol stage are dissolved in specified solvents, the initial condensation between the phenol and the aldehyde is effected in the presence of the solvent. Solvents specified are cyclic ketones and their homologues, cyclic alcohols or esters thereof, hydrogenated phenols or naphthalenes other than tetra hydronaphthalene, phenol esters, furfural or mixtures of these, or a mixture of furfural, cyclohexanol or methyl cyclohexanol with linseed, wood, poppy-seed or stand oil. Phenol is dissolved in hexalin and is heated at 170 DEG C. with hexamethylene tetramine. Thereafter two further quantities of phenol are added at intervals, and heating is continued until the condensation is complete. Phenol may be replaced by cresol, resorcin, dioxydiphenyl dimethylethane, or mixtures thereof. The novolac resin, first formed, may be converted to the resitol by addition of basic catalysts such as caustic soda or ammonia, or by acid catalysts such as sodium bisulphate, in which case paraformaldehyde is used in the first stage of the condensation, and hexamethylene tetramine in the subsequent stages. The condensation may be effected under normal, reduced or increased pressure, and plasticizers, fire-resisting agents and diluents may be added. Specification 347,611 is referred to. Reference has been directed by the Comptroller to Specification 329,313, [Class 95, Paints &c.].ALSO:In the preparation of resin solutions such as lacquers, as described in the parent Specification, in which phenol-aldehyde resins in the resitol stage are dissolved in specified solvents, p the initial condensation between the phenol and the aldehyde is effected in the presence of the solvent. Solvents specified are cycloketones and their homologues, cyclic alcohols or esters thereof, hydrogenated phenols or naphthalenes, other than tetrahydronaphthalene, phenol esters, furfural, or mixtures of these, or a mixture of furfural, cyclohexanol or methylcyclohexanol with linseed, wood, poppy seed, or stand oil. Phenol is dissolved in cyclohexanol and heated to 170 DEG C. with hexamethylene tetramine. Thereafter two further quantities of phenol are added at intervals, and heating is continued until the condensation is complete. Phenol may be replaced by cresol, resorcin, dioxydiphenyl dimethylethane, or mixtures thereof. The initially formed novolac resin may be converted into the resitol by addition of basic catalysts, such as caustic soda or ammonia, or by acid catalysts such as sodium bisulphate, in which case paraformaldehyde is used in the first stage of the condensation, and hexamethylene tetramine in the subsequent stages. The condensation may be effected under normal, reduced or increased pressure, and diluents, plasticizers, and fire-resisting agents may be added. Specification 347,611, [Group III], also is referred to. Reference has been directed by the Comptroller to Specification 329,313, [Class 2 (iii), Dyes, &c.].
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