Patent US4790367A successfully refreshed from Google Patents.
US4790367A
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Methods for preparing a formed cellular plastic material pattern employed in metal casting
Assignee: Dow Chemical Co
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Filing: 1988-01-28
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Granted: 1988-12-13
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Expires: 2008-01-28
Abstract
Abstract Expandable and expanded plastic materials having a majority of alkyl acrylate monomeric repeat units are disclosed. These materials when expanded have a volume expansion of at least 60 and maintain that volume expansion for a period of at least 30 minutes under expansion conditions after reaching the volume expansion of 60. Expandable and expanded plastic materials having a majority of alkyl acrylate monomeric repeat units and an inhibitor for the monomer(s) and a crosslinker incorporated into the plastic material upon monomer polymerization are also disclosed. Also disclosed are expandable and expanded plastic materials having a majority of alkyl acrylate monomeric repeat units with blowing agents of 2,2-dimethylbutane, 2,3-dimethylbutane or mixtures of one or both with 1-chloro-1,1-difluoroethane or mixtures of at least 30 percent of one or both with other volatile blowing agents. These specific types of formed patterns and core assemblies, wholly or partially formed from the destructible expanded closed-cell cellular plastic materials of the present invention have a decreased tendency to form nonvolatile residue during the casting of metals such as iron. Superior castings are thereby obtained without resort to uneconomic casting methods. Further disclosed is a method of casting metal castings using the disclosed expanded plastic material articles (Lost Foam or Evaporative Pattern Casting). The disclosed expanded plastic material articles are especially preferred for metal castings having a final carbon percentage of 1.8 weight percent or less in the final casting.
Inventors
- 👤 Norman G. Moll
- 👤 David R. Johnson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 07:04
CPC Classifications
B; B22; B22C; B22C9/00; B22C9/02; B22C9/04; B22C9/046; B22C7/00; B22C7/02; B22C7/023
Claims Analysis
Total Claims: 39
Claim 1
Independent Claim
256 words
A method of replica-casting a metal casting comprising the steps of: (a) forming a pattern having a heat-destructible portion with the heat-destructible portion being an expanded multicellular closed-cell cellular plastic material having: (A) a plastic material, polymerized from one or more monomers, containing a majority, by weight of the plastic material, of monomeric repeat units of the formula: --CH.sub.2 CR'(COOR-- wherein R is selected from the group consisting of alkanes having 1-4 carbon atoms (C), hydroxy alkanes having 1-4 C and cycloalkanes having 3-6 C, and R' is selected from the group consisting of CH 3 and C 2 H 5 ; and (B) a volatile blowing agent entrapped in the expanded closed-cell cellular plastic material; wherein the expanded closed-cell cellular plastic material article after expansion from an expandable plastic material particle has (i) a volume increase by a factor of at least 20 after a period of 5 minutes from the start of expansion conditions; (ii) a maximum volume expansion of at least 60; and (iii) maintains a volume expansion of at least 60 for an additional period of 30 minutes under expansion conditions after reaching a volume expansion of 60; all wherein the the expansion of the expandable plastic material particle article into the expanded closed-cell cellular plastic material article occurs at ambient pressure with hot air in an oven at a temperature of 25° C. above the glass transition temperature of the plastic material; and casting the metal casting with the pattern having the heat-destructible portion being the expanded closed-cell cellular plastic material.
Claim 2
Independent Claim
256 words
A method of replica-casting a metal casting comprising the steps of: (a) forming a pattern having a heat-destructible portion with the heat-destructible portion being an expanded multicellular closed-cell cellular plastic material having: (A) a plastic material, polymerized from one or more monomers, containing a majority, by weight of the plastic material, of monomeric repeat units of the formula: --CH.sub.2 CR'(COOR-- wherein R is selected from the group consisting of alkanes having 1-4 carbon atoms (C), hydroxy alkanes having 1-4 C and cycloalkanes having 3-6 C, and R' is selected from the group consisting of CH 3 and C 2 H 5 ; and (B) a volatile blowing agent entrapped in the expanded closed-cell cellular plastic material; wherein the expanded closed-cell cellular plastic material article after expansion from an expandable plastic material particle has (i) a volume increase by a factor of at least 20 after a period of 5 minutes from the start of expansion conditions; (ii) a maximum volume expansion of at least 60; and (iii) maintains a volume expansion of at least 60 for an additional period of 30 minutes under expansion conditions after reaching a volume expansion of 60; all wherein the the expansion of the expandable plastic material particle article into the expanded closed-cell cellular plastic material article occurs at ambient pressure with hot air in an oven at a temperature of 25° C. above the glass transition temperature of the plastic material; and casting the metal casting with the pattern having the heat-destructible portion being the expanded closed-cell cellular plastic material.
Claim 3
Dependent Claim
63 words
A method of replica-casting a metal casting, as recited in claim 1, wherein the expanded closed-cell cellular plastic material article after expansion from the expandable plastic material particle has a maximum volume expansion of at least 75 and maintains a volume expansion of at least 75 for an additional period of 30 minutes under expansion conditions after reaching the volume expansion of 75.
Claim 4
Dependent Claim
63 words
A method of replica-casting a metal casting, as recited in claim 1, wherein the expanded closed-cell cellular plastic material article after expansion from the expandable plastic material particle has a maximum volume expansion of at least 90 and maintains a volume expansion of at least 90 for an additional period of 30 minutes under expansion conditions after reaching the volume expansion of 90.
Claim 5
Dependent Claim
27 words
A method of replica-casting a metal casting, as recited in claim 1, wherein the plastic material has a majority of monomeric repeat units of the formula: ##STR2##
Claim 6
Dependent Claim
18 words
A method of replica-casting a metal casting, as recited in claim 1, wherein the plastic material is poly(methylmethacrylate).
Claim 7
Independent Claim
173 words
A method of replica-casting a metal casting comprising the steps of: (a) forming a pattern having a heat-destructible portion with the heat-destructible portion being an expanded multicellular closed-cell cellular plastic material having: (A) a plastic material, polymerized from one or more monomers, containing a majority, by weight of the plastic material, of monomeric repeat units of the formula: --CH;hd 2CR'(COOR)-- wherein R is selected from the group consisting of alkanes having 1-4 carbon atoms (C), hydroxy alkanes having 1-4 C and cycloalkanes having 3-6 C, and R' is selected from the group consisting of CH 3 and C 2 H 5 ; (B) a volatile blowing agent entrapped in the expanded closed-cell cellular plastic material; (C) an inhibitor for the monomer(s) incorporated into the plastic material upon polymerization of the monomer(s); and (D) a crosslinking agent incorporated into the plastic material upon polymerization of the monomer(s) to provide crosslinking of the plastic material; and (b) casting the metal casting with the pattern having the heat-destructible portion being the expanded closed-cell cellular plastic material.
Claim 8
Independent Claim
173 words
A method of replica-casting a metal casting comprising the steps of: (a) forming a pattern having a heat-destructible portion with the heat-destructible portion being an expanded multicellular closed-cell cellular plastic material having: (A) a plastic material, polymerized from one or more monomers, containing a majority, by weight of the plastic material, of monomeric repeat units of the formula: --CH;hd 2CR'(COOR)-- wherein R is selected from the group consisting of alkanes having 1-4 carbon atoms (C), hydroxy alkanes having 1-4 C and cycloalkanes having 3-6 C, and R' is selected from the group consisting of CH 3 and C 2 H 5 ; (B) a volatile blowing agent entrapped in the expanded closed-cell cellular plastic material; (C) an inhibitor for the monomer(s) incorporated into the plastic material upon polymerization of the monomer(s); and (D) a crosslinking agent incorporated into the plastic material upon polymerization of the monomer(s) to provide crosslinking of the plastic material; and (b) casting the metal casting with the pattern having the heat-destructible portion being the expanded closed-cell cellular plastic material.
Claim 9
Dependent Claim
43 words
A method of replica-casting a metal casting, as recited in claim 6, wherein the inhibitor is present, prior to incorporation into the plastic material, at a level of about at least 25 parts by weight per million parts by weight of the monomer(s).
Claim 10
Dependent Claim
39 words
A method of replica-casting a metal casting, as recited in claim 7, wherein the inhibitor is present, prior to incorporation into the plastic material, at a level of about at least 50 parts per million parts of the monomer(s).
Claim 11
Dependent Claim
46 words
A method of replica-casting a metal casting, as recited in claim 8, wherein the crosslinking agent is present, prior to incorporation into the plastic material, in an amount of from about 1.5×10 -4 to about 6.2×10 -4 moles of crosslinking agent per mole of the monomer(s).
Claim 12
Dependent Claim
46 words
A method of replica-casting a metal casting, as recited in claim 9, wherein the crosslinking agent is present, prior to incorporation into the plastic material, in an amount of from about 3.1×10 -4 to about 4.6×10 -4 moles of crosslinking agent per mole of the monomer(s).
Claim 13
Dependent Claim
19 words
A method of replica-casting a metal casting, as recited in claim 10, wherein the crosslinking agent is divinyl benzene.
Claim 14
Dependent Claim
25 words
A method of replica-casting a metal casting, as recited in claim 11, wherein the inhibitor is selected from the group consisting of hydroquinone and methoxyhydroquinone.
Claim 15
Dependent Claim
26 words
A method of replica-casting a metal casting, as recited in claim 12, wherein the plastic material has a majority of repeat units of the formula: ##STR3##
Claim 16
Dependent Claim
37 words
A method of replica-casting a metal casting, as recited in claim 13, wherein the plastic material has an apparent weight average molecular weight in the range of 220,000 to 320,000 and a polydispersity of at least 2.7.
Claim 17
Dependent Claim
19 words
A method of replica-casting a metal casting, as recited in claim 14, wherein the plastic material is poly(methyl methacrylate).
Claim 18
Dependent Claim
31 words
A method of replica-casting a metal casting, as recited in claim 15, wherein the plastic material is poly(methyl methacrylate) which has been polymerized in the presence of a chain transfer agent.
Claim 19
Dependent Claim
28 words
A method of replica-casting a metal casting, as recited in claim 16, wherein the plastic material is poly(methyl methacrylate) prepared with a chain transfer agent of carbon tetrabromide.
Claim 20
Dependent Claim
52 words
A method of replica-casting a metal casting, as recited in claim 17, wherein the chain transfer agent of carbon tetrabromide is present, prior to incorporation into the plastic material, in an amount of from about 2.51×10 -4 to about 20.20×10 -4 moles of chain transfer agent per mole of methyl methacrylate monomer.
Claim 21
Dependent Claim
52 words
A method of replica-casting a metal casting, as recited in claim 18, wherein the chain transfer agent of carbon tetrabromide is present, prior to incorporation into the plastic material, in an amount of from about 5.02×10 -4 to about 20.10×10 -4 moles of chain transfer agent per mole of methyl methacrylate monomer.
Claim 22
Dependent Claim
46 words
A method of replica-casting a metal casting, as recited in claim 19, wherein the volatile blowing agent contained within the plastic material is present in an amount of from about 0.09 moles to about 0.21 moles of blowing agent per mole of polymerized methyl methacrylate monomer.
Claim 23
Dependent Claim
46 words
A method of replica-casting a metal casting, as recited in claim 20, wherein the volatile blowing agent contained within the plastic material is present in an amount of from about 0.15 moles to about 0.19 moles of blowing agent per mole of polymerized methyl methacrylate monomer.
Claim 24
Dependent Claim
113 words
A method of replica-casting a metal casting, as recited in claim 21, wherein the volatile blowing agent is selected from the group consisting of: (a) 1,1,2-trichloro-1,2,2-trifluoroethane; (b) a mixture having at least 20 weight percent of 1,1,2-trichloro-1,2,2-trifluoroethane by weight of the mixture, with the remainder of the mixture selected from the group consisting of: (1) 1,2-dichloro-1,1,2,2-tetrafluoroethane; and (2) one or more other volatile blowing agents; (c) 2,2-dimethylbutane; (d) 2,3-dimethylbutane; (e) a mixture of 2,2-dimethylbutane and 2,3-dimethylbutane; (f) a mixture of (c), (d) and (e) with 1-chloro-1,1-difluoroethane; and (g) a mixture of at least 30 percent of (c), (d) and (e) by weight of the mixture with one or more other volatile blowing agents.
Claim 25
Dependent Claim
30 words
A method of replica-casting a metal casting, as recited in claim 22, wherein the heat-destructible portion of the pattern has a density of 0.7 to 5.0 pounds per cubic foot.
Claim 26
Dependent Claim
30 words
A method of replica-casting a metal casting, as recited in claim 23, wherein the destructible portion of the pattern has a density of 1.0 and 2.2 pounds per cubic foot.
Claim 27
Dependent Claim
44 words
A method of replica-casting a metal casting, as recited in claim 24, wherein the metal to be cast is a steel alloy, a stainless steel or a stainless steel alloy having a carbon percentage, after casting of 0.1 weight percent to 0.5 weight percent.
Claim 28
Dependent Claim
27 words
A method of replica-casting a metal casting, as recited in claim 25, wherein the carbon specification, of the metal as cast, is less than 0.1 weight percent.
Claim 29
Dependent Claim
20 words
A method of replica-casting a metal casting, as recited in claim 6, wherein the metal to be cast is aluminum.
Claim 30
Dependent Claim
20 words
A method of replica-casting a metal casting, as recited in claim 6, wherein the metal to be cast is bronze.
Claim 31
Dependent Claim
21 words
A method of replica-casting a metal casting, as recited in claim 6, wherein the metal to be cast is ductile iron.
Claim 32
Dependent Claim
117 words
A method of replica-casting a metal casting, as recited in claim 6, wherein pre-expanded plastic material articles used to prepare the heat-destructible portion of the pattern having a molding window time range of at least 5 seconds as determined by a test wherein pre-expanded plastic material articles are expansion-molded in steam at a temperature that is 21° C. above the glass transition temperature of the plastic material, and wherein molding window time range is defined as the difference in time between the maximum period under which good molding occurs and the minimum time under which good molding occurs for a molded foam having a density within the range of from 1.35 to 1.6 pounds per cubic foot.
Claim 33
Dependent Claim
41 words
A method of replica-casting a metal casting, as recited in claim 30, wherein the replica-casting uses at least one top gate for feeding molten metal towards the foam pattern and wherein the molding window time range is at least 12 seconds.
Claim 34
Dependent Claim
141 words
A method of replica-casting a metal casting, as recited in claim 6, wherein an expanded closed-cell cellular plastic material article used to prepare the heat-destructible portion of the pattern after expansion from an expandable plastic material particle has (i) a volume increase by a factor of at least 20 after a period of 5 minutes from the start of expansion conditions; (ii) a maximum volume expansion of at least 60; (iii) maintains a volume expansion of at least 60 for an addtional period of 30 minutes under expansion conditions after reaching the volume expansion of 60; all wherein the the expansion of the expandable plastic material particle article into the expanded closed-cell cellular plastic material article occurs at ambient pressure with hot air in an oven at a temperature of 25° C. above the glass transition temperature of the plastic material;
Claim 35
Dependent Claim
72 words
A method of replica-casting a metal casting, as recited in claim 6, wherein an expanded closed-cell cellular plastic material article used to prepare the heat-destructible portion of the pattern after expansion from an expandable plastic material particle has a maximum volume expansion of at least 75 and maintains a volume expansion of at least 75 for an additional period of 30 minutes under expansion conditions after reaching the volume expansion of 75.
Claim 36
Dependent Claim
72 words
A method of replica-casting a metal casting, as recited in claim 6, wherein an expanded closed-cell cellular plastic material article used to prepare the heat-destructible portion of the pattern after expansion from an expandable plastic material particle has a maximum volume expansion of at least 90 and maintains a volume expansion of at least 90 for an additional period of 30 minutes under expansion conditions after reaching the volume expansion of 90.
Claim 37
Independent Claim
185 words
A method of replica-casting a metal casting comprising the steps of: (a) forming a pattern having a heat-destructible portion with the heat-destructible portion being an expanded multicellular closed-cell cellular plastic material having: (A) a plastic material, polymerized from one or more monomers, containing a majority, by weight of the plastic material, of monomeric repeat units of the formula: --CH.sub.2 CR'(COOR)-- wherein R is selected from the group consisting of alkanes having 1-4 carbon atoms (C), hydroxy alkanes having 1-4C and cycloalkanes having 3-6C, and R' is selected from the group consisting of CH 3 and C 2 H 5 ; (B) at least one volatile blowing agent entrapped in the expanded closed-cell cellular plastic material; and (b) casting the metal casting with the pattern having the heat-destructible portion being the expanded closed-cell cellular plastic material and with a metal selected from the group consisting of: (1) an iron base alloy; (2) a steel; (3) a stainless steel; and (4) a stainless steel alloy; so that the metal casting, after casting, has a carbon percentage of less than about 1.8 weight percent based on metal weight.
Claim 38
Independent Claim
185 words
A method of replica-casting a metal casting comprising the steps of: (a) forming a pattern having a heat-destructible portion with the heat-destructible portion being an expanded multicellular closed-cell cellular plastic material having: (A) a plastic material, polymerized from one or more monomers, containing a majority, by weight of the plastic material, of monomeric repeat units of the formula: --CH.sub.2 CR'(COOR)-- wherein R is selected from the group consisting of alkanes having 1-4 carbon atoms (C), hydroxy alkanes having 1-4C and cycloalkanes having 3-6C, and R' is selected from the group consisting of CH 3 and C 2 H 5 ; (B) at least one volatile blowing agent entrapped in the expanded closed-cell cellular plastic material; and (b) casting the metal casting with the pattern having the heat-destructible portion being the expanded closed-cell cellular plastic material and with a metal selected from the group consisting of: (1) an iron base alloy; (2) a steel; (3) a stainless steel; and (4) a stainless steel alloy; so that the metal casting, after casting, has a carbon percentage of less than about 1.8 weight percent based on metal weight.
Claim 39
Dependent Claim
27 words
A method of replica-casting a metal casting, as recited in claim 35, wherein the metal casting has a carbon content of from 0.05 to 0.5 weight percent.
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) | 1991-12-13 | 1992-06-13 | 1992-12-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-12-13 | 1996-06-13 | 1996-12-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-12-13 | 2000-06-13 | 2000-12-13 | $7700.00 | Window Closed / Lapsed |