US4072649A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for the production of foundry cores and molds
Assignee: Bayer AG
•
Filing: 1975-08-07
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Granted: 1978-02-07
•
Expires: 1995-08-07
Abstract
Abstract Foundry cores and molds are produced from foundry sand and/or other inert fillers, polyhydroxyl compounds, polyisocyanates and tertiary amine catalysts. The precatalyzed mixtures can be stored for long periods of time without any adverse effects on the subsequent processing or core properties when at least 80% by weight of the polyisocyanate used is of the diphenyl alkane series in which the isocyanate groups are sterically hindered solely by substituents in at least one ortho position.
Inventors
- 👤 Rolf Kubens
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 16:59
CPC Classifications
B; B22; B22C; B22C1/00; B22C1/16; B22C1/20; B22C1/22; B22C1/2233; B22C1/2273; B22C1/162; C; C08; C08G; C08G18/00; C08G18/06; C08G18/70; C08G18/72; C08G18/74; C08G18/76; C08G18/7657; C08G18/7664
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
64 words
In a process for the production of foundry cores and molds wherein a mixture of inert fillers, polyhydroxyl compounds, polyisocyanates and tertiary amines is cured in a mold, the improvement wherein at least 80% by weight of the polyisocyanate component used consists of polyisocyanates of the diphenyl alkane series which solely contain isocyanate groups sterically hindered by substituents in at least one ortho position.
Claim 2
Dependent Claim
64 words
In a process for the production of foundry cores and molds wherein a mixture of inert fillers, polyhydroxyl compounds, polyisocyanates and tertiary amines is cured in a mold, the improvement wherein at least 80% by weight of the polyisocyanate component used consists of polyisocyanates of the diphenyl alkane series which solely contain isocyanate groups sterically hindered by substituents in at least one ortho position.
Claim 3
Dependent Claim
16 words
The process of claim 1 wherein at least 90% of said sterically hindered polyisocyanate is used.
Claim 4
Dependent Claim
14 words
The process of claim 1 wherein said sterically hindered polyisocyanate is 4,4'-diisocyanato-3,3'-dimethyl diphenyl methane.
Claim 5
Dependent Claim
16 words
The process of claim 1 wherein said polyhydroxyl compound is a phenol resin containing hydroxyl groups.
Claim 6
Dependent Claim
12 words
The process of claim 1 wherein said inert filler is foundry sand.
Claim 7
Dependent Claim
14 words
The process of claim 1 wherein the NCO/OH ratio is between 2:1 and 1:2.
Claim 8
Dependent Claim
11 words
The process of claim 1 wherein the NCO/OH ratio is 1:1.
Claim 9
Dependent Claim
55 words
The process of claim 1 wherein said polyisocyanate is ##STR4## where R 1 represents an aliphatic hydrocarbon radical having from 1 to 4 carbon atoms, R 2 and R 3 are the same or different and represent hydrogen or the radical R 1 , and n is 0 or an integer from 1 to 8.
Claim 10
Dependent Claim
21 words
The process of claim 8 wherein R 1 = methyl, R 2 and R 3 = hydrogen and n = 0.
Claim 11
Dependent Claim
15 words
The process of claim 8 wherein n is an integer of from 1 to 3.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1981-02-06 | 1981-08-08 | 1982-02-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-02-06 | 1985-08-08 | 1986-02-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-02-06 | 1989-08-08 | 1990-02-07 | $7700.00 | Window Closed / Lapsed |