Claims
- 1. 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.sub.3 and C.sub.2 H.sub.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.degree. 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.
- 2. 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.
- 3. 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.
- 4. 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##
- 5. A method of replica-casting a metal casting, as recited in claim 1, wherein the plastic material is poly(methylmethacrylate).
- 6. 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.sub.3 and C.sub.2 H.sub.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.
- 7. 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).
- 8. 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).
- 9. 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.times.10.sup.-4 to about 6.2.times.10.sup.-4 moles of crosslinking agent per mole of the monomer(s).
- 10. 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.times.10.sup.-4 to about 4.6.times.10.sup.-4 moles of crosslinking agent per mole of the monomer(s).
- 11. A method of replica-casting a metal casting, as recited in claim 10, wherein the crosslinking agent is divinyl benzene.
- 12. 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.
- 13. 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##
- 14. 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.
- 15. A method of replica-casting a metal casting, as recited in claim 14, wherein the plastic material is poly(methyl methacrylate).
- 16. 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.
- 17. 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.
- 18. 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.times.10.sup.-4 to about 20.20.times.10.sup.-4 moles of chain transfer agent per mole of methyl methacrylate monomer.
- 19. 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.times.10.sup.-4 to about 20.10.times.10.sup.-4 moles of chain transfer agent per mole of methyl methacrylate monomer.
- 20. 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.
- 21. 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.
- 22. 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.
- 23. 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.
- 24. 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.
- 25. 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.
- 26. 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.
- 27. A method of replica-casting a metal casting, as recited in claim 6, wherein the metal to be cast is aluminum.
- 28. A method of replica-casting a metal casting, as recited in claim 6, wherein the metal to be cast is bronze.
- 29. A method of replica-casting a metal casting, as recited in claim 6, wherein the metal to be cast is ductile iron.
- 30. 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.degree. 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.
- 31. 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.
- 32. 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.degree. C. above the glass transition temperature of the plastic material;
- 33. 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.
- 34. 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.
- 35. 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.sub.3 and C.sub.2 H.sub.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.
- 36. 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.
Parent Case Info
This is a continuation-in-part of Application Ser. No. 890,036, filed July 28, 1986.
US Referenced Citations (4)
Continuation in Parts (1)
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Number |
Date |
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890036 |
Jul 1986 |
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