| 摘要 |
A new foundry binder composition comprises a selected phenol-formaldehyde resin, a polyisocyanate, and a selected solvent therefor. A preferred solvent is ketal or an acetal such as butyl acetal. The resole is essentially anhydrous, should contain about 8% free phenol, and is further preferably characterized by the presence of substituent -(CH2-O)n-R groups replacing a phenolic hydrogen, R being a hydrocarbon radical such as butyl. Methylene and ether bridges linking phenolic nuclei are predominantly ortho-para with some para-para bridges. Also disclosed is the admixture of a reactive polyisocyanate and a solvent such as butyl acetal.
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