Polyurethane-forming no-bake foundry binder systems
AssigneeAshland Inc.
InventorsWilliam R. Dunnavant, Ken K. Chang, Robert B. Fechter
Life of this patent
Estimating the term…
Abstract
This invention relates to polyurethane-forming foundry no-bake binder systems comprising a phenolic resin component and polyisocyanate component. The phenolic resin component comprises a blend of (a) polyphenol resin and (b) a phenolic resole resin. The binder systems have reduced phenol and free formaldehyde due to the presence of the polyphenol resin in the phenolic resin component. Foundry shapes are made by the no-bake process and are used in making ferrous and non ferrous metal castings.
Claims20
A polyurethane-forming no-bake binder system comprising as separate components:
- (a) polyisocyanate component;
- (b) a phenolic resin component comprising a blend of
- (1) a polyphenol resin wherein the phenolic units of the resin are directly bonded to one another through positions ortho or para to the hydroxyl group, and
- (2) a phenolic resole resin;
- and
- (c) a liquid amine curing catalyst.
A foundry mix composition which comprises in admixture:
- (a) a major amount of aggregate;
- and
- (b) an effective bonding amount of a polyurethane-forming binder comprising in admixture with the aggregate:
- (1) polyisocyanate component;
- (2) a component comprising a blend of a polyphenol resin wherein the benzene rings of the resin are directly bonded to each other, and a phenolic resole resin;
- and
- (3) a liquid amine curing catalyst.
A no-bake process for preparing a foundry shape which comprises:
- (a) mixing a foundry aggregate with a bonding amount of up to about 10% by weight, based upon the weight of the aggregate, of a polyurethane-forming binder comprising in admixture with the aggregate:
- (1) polyisocyanate component;
- (2) a phenolic resin component comprising a blend of a polyphenol resin wherein the benzene rings of the resin are directly bonded to each other, and a phenolic resole resin;
- and
- (3) a liquid amine curing catalyst;
- (b) introducing the foundry mix obtained from step (a) into a pattern;
- (c) hardening the foundry mix in the pattern to become self-supporting;
- and
- (d) thereafter removing the shaped foundry mix of step (c) from the pattern and allowing it to further cure, thereby obtaining a hard, solid, cured foundry shape.
Dependencies are inferred from the claim text.