US4162238A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Foundry mold or core compositions and method
Assignee: DU PONT AND POWER SILICATES Inc A CORP OF
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Filing: 1976-03-24
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Granted: 1979-07-24
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Expires: 1996-03-24
Abstract
Abstract Compositions and method for producing foundry sand cores or molds of initial high strength but with essentially no strength after casting metals above 700° C. which involves shaping and setting a composition containing foundry sand and a binder comprising sodium, potassium, or lithium silicate and sufficient amorphous silica so that the fraction of the total silica in the binder solution which is present as amorphous silica is from 2 to 75%, the amorphous silica having a particle size in the range from about 2 nanometers to 500 nanometers and the binder having a molar ratio of silica to alkali metal oxide ranging from 3.5:1 to 10.1.
Inventors
- 👤 Horacio E. Bergna
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 23:46
CPC Classifications
B; B22; B22C; B22C1/00; B22C1/02; B22C1/16; B22C1/167; B22C1/18; B22C1/186; B22C1/188
Claims Analysis
Total Claims: 28
Claim 1
Independent Claim
151 words
A sand core or mold composition comprising of foundary sand, 1-6% by weight of the sand of an aqueous solution or dispersion of a firm-forming resin adhesive and 3 to 15% by weight of the sand of an aqueous binder comprising an aqueous sodium, potassium or lithium silicate solution or mixtures thereof and amorphous silica, the binder characterized by (1) a molar ratio of silica to alkali metal oxide of from 3.5:1 to 10:1; (2) a weight fraction of the total silica present as amorphous silica is from 2 to 75%; (3) a weight fraction of the total silica present as silicate ions is from 98 to 25% and the amorphous silica has a particle size of from 2 nanometers to 500 nanometers and the sand core or mold possesses a compressive strength sufficiently low to permit easy crushing after said core or mold is used in preparing a metal casting.
Claim 2
Dependent Claim
151 words
A sand core or mold composition comprising of foundary sand, 1-6% by weight of the sand of an aqueous solution or dispersion of a firm-forming resin adhesive and 3 to 15% by weight of the sand of an aqueous binder comprising an aqueous sodium, potassium or lithium silicate solution or mixtures thereof and amorphous silica, the binder characterized by (1) a molar ratio of silica to alkali metal oxide of from 3.5:1 to 10:1; (2) a weight fraction of the total silica present as amorphous silica is from 2 to 75%; (3) a weight fraction of the total silica present as silicate ions is from 98 to 25% and the amorphous silica has a particle size of from 2 nanometers to 500 nanometers and the sand core or mold possesses a compressive strength sufficiently low to permit easy crushing after said core or mold is used in preparing a metal casting.
Claim 3
Dependent Claim
38 words
The composition of claim 1 wherein the weight fraction of the total silica as amorphous silica is from 2 to 50% and the weight fraction of the total silica present as silicate ions is from 98 to 50%
Claim 4
Dependent Claim
56 words
The composition of claim 1 wherein the molar ratio is from 4:01 to 6:1, the weight fraction of the total silica as amorphous silica is from 10 to 50%, the fraction of total silica as silicate ions is from 90 to 50% and the amorphous silica has a particle size of from 12 to 60 nanometers.
Claim 5
Dependent Claim
38 words
The composition of claim 1 wherein the weight fraction of the total silica as amorphous silica is from 30 to 50% and the weight fraction of the total silica present as silicate ions is from 70 to 50%.
Claim 6
Dependent Claim
11 words
The composition of claim 1 wherein the silicate is sodium silicate.
Claim 7
Dependent Claim
23 words
The composition of claim 1 containing in addition 0.5 to 10% by weight based on the foundry sand of a clay or alumina.
Claim 8
Dependent Claim
10 words
The composition of claim 6 wherein the clay is kaolin.
Claim 9
Dependent Claim
22 words
The composition of claim 7 containing in addition from 0.5 to 4 weight percent based on the foundry sand of a pitch.
Claim 10
Dependent Claim
17 words
The composition of claim 1 wherein the film-forming resin adhesive is a water dispersion of polyvinyl acetate.
Claim 11
Dependent Claim
19 words
The composition of claim 1 wherein the film-forming resin adhesive is a water dispersion of a vinyl acetate-ethylene copolymer.
Claim 12
Dependent Claim
17 words
The composition of claim 8 wherein the film-forming resin adhesive is a water dispersion of polyvinyl acetate.
Claim 13
Dependent Claim
18 words
The composition of claim 8 wherein the film-forming resin adhesive is a water dispersion of a vinyl-acetate-ethylene copolymer.
Claim 14
Independent Claim
157 words
A method for making a sand core or a sand mold useful in the casting of molten metal which comprises mixing foundry sand 1-6% by weight of the sand of an aqueous solution or dispersion of a film-forming resin adhesive and 3 to 15% by weight of the sand of a binder which comprises an aqueous sodium, potassium or lithium silicate solution or mixtures thereof and amorphous silica having a particle size of from 2 nanometers to 500 nanometers, the amount of silicate and amorphous silica being adjusted to form a binder with (1) a molar ratio of silica to alkali metal oxide ranging from 3.5:1 to 10:1, (2) the weight fraction of total silica present as amorphous silica of from 2 to 75% and (3) a weight fraction of the total silica present as silicate ions of from 98 to 25%, forming the sand and binder mixtures into the desired shape and setting the formed mixture.
Claim 15
Independent Claim
157 words
A method for making a sand core or a sand mold useful in the casting of molten metal which comprises mixing foundry sand 1-6% by weight of the sand of an aqueous solution or dispersion of a film-forming resin adhesive and 3 to 15% by weight of the sand of a binder which comprises an aqueous sodium, potassium or lithium silicate solution or mixtures thereof and amorphous silica having a particle size of from 2 nanometers to 500 nanometers, the amount of silicate and amorphous silica being adjusted to form a binder with (1) a molar ratio of silica to alkali metal oxide ranging from 3.5:1 to 10:1, (2) the weight fraction of total silica present as amorphous silica of from 2 to 75% and (3) a weight fraction of the total silica present as silicate ions of from 98 to 25%, forming the sand and binder mixtures into the desired shape and setting the formed mixture.
Claim 16
Dependent Claim
38 words
The method of claim 13 wherein the weight fraction of total silica present as amorphous silica is from 2 to 50% and the weight fraction of the total silica present as silicate ions is from 98 to 50%.
Claim 17
Dependent Claim
18 words
The method of claim 13 wherein amorphous silica and the silicate solution is added to the sand separately.
Claim 18
Dependent Claim
23 words
The method of claim 14 wherein the amorphous silica is added to the sand and mixed before the addition of the silicate solution.
Claim 19
Dependent Claim
16 words
The method of claim 13 wherein all the amorphous silica is present in the silicate solution.
Claim 20
Dependent Claim
27 words
The method of claim 13 wherein the amorphous silica is present in the silicate solution and additional silica is added in the form of a silica sol.
Claim 21
Dependent Claim
67 words
The method of claim 14 wherein the molar ratio of silica to alkali metal oxides ranges from 4:1 to 6:1 and the fraction of total silica present as amorphous silica is 10 to 50% by weight and the remaining 90 to 50% of the total silica is present as silicate ions and the amorphous silica has a particle size in the range of 12 to 60 nanometers.
Claim 22
Dependent Claim
15 words
The method of claim 13 wherein the formed mixture is set with CO 2 .
Claim 23
Dependent Claim
17 words
The method of claim 13 wherein the film-forming resin adhesive is a water dispersion of polyvinyl acetate.
Claim 24
Dependent Claim
18 words
The method of claim 13 wherein the film-forming resin adhesive is a water dispersion of vinyl acetate-ethylene copolymer.
Claim 25
Dependent Claim
24 words
The method of claim 13 wherein the mixture additionally contains from 0.5 to 4 weight percent based on the foundry sand of a pitch.
Claim 26
Dependent Claim
17 words
The method of claim 23 wherein the film-forming resin adhesive is a water dispersion of polyvinyl acetate.
Claim 27
Dependent Claim
18 words
The method of claim 23 wherein the film-forming resin adhesive is a water dispersion of vinyl acetate-ethylene copolymer.
Claim 28
Dependent Claim
18 words
The method of claim 13 wherein the mixture is set by the addition of an acetin curing agent.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1982-07-23 | 1983-01-22 | 1983-07-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1986-07-23 | 1987-01-22 | 1987-07-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1990-07-23 | 1991-01-22 | 1991-07-24 | $7700.00 | Window Closed / Lapsed |