Binders for foundry cores and moulds
US4588013A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Mar 29, 1985 |
| Grant date | May 13, 1986 |
| Priority date | — |
| Expiry date | Mar 29, 2005 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB22C1/222
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
A binder for a foundry core or mould consists of an alkali metal salt of a polybasic organic acid or of a polymerized monobasic organic acid, for example sodium polyacrylate, an alkaline earth metal hydroxide such as calcium hydroxide, one or more polyvalent metal oxides, preferably magnesium oxide, and calcium citrate, together with water. The mixture may also include another polyvalent metal oxide, for example zinc oxide. The inclusion of calcium citrate in the binder composition, particularly in the presence of magnesium oxide, has been found to reduce the problem of `softening back` in which the strength of the core or mould interior deteriorates over storage periods of a few days due to the continued absorption of carbon dioxide from the atmosphere in damp conditions.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.