| 摘要 |
<p>1,272,972. Resin compositions. ASHLAND OIL Inc. 23 April, 1969 [24 April, 1968], No. 20776/69. Headings C3N and C3R. Resin compositions comprise a resin component which is an organic solvent-soluble phenolic resin containing benzylic ether groups or methylol groups, a hardener component comprising a liquid polyisocyanate containing at least two isocyanate groups and a curing catalyst which is a base having a pK b value of 4 to 13. The phenolic resin containing benzylic ether groups suitably has the repeating unit wherein A, B and C are hydrogen, hydrocarbon or oxyhydrocarbon radicals, or halogen and R<SP>1</SP> is hydrogen or a hydrocarbon radical of 1 to 8 carbon atoms, and is prepared by reacting a phenol with an aldehyde in the liquid phase, in the substantial absence of water at temperatures below 130‹ C. in the presence of catalytic concentrations of a metal ion dissolved in the reaction medium. The methylol-terminated phenolic resins are resole resins which are organic solvent soluble. Conventional aliphatic, cycloaliphatic or aromatic polyisocyanates may be used. The catalyst is suitably an organic compound containing nitrogen or phosphorus atoms and is preferably a heterocyclic compound containing at least one nitrogen atom in the ring structure. The composition may be prepared in the presence of a solvent, preferably a mixture of an aromatic solvent and an ester or ether solvent. The composition is most preferably used as a binder for particulate solids. A foundry mix may be prepared by admixing the binder or its components with sand, moulded into the desired core or shape and cured by standing at room temperature. The foundry mix may also contain iron oxide, ground flax fibres, wood cereals, pitch and refractory flours.</p> |
